US20160195183A1 - Rotation transmission device - Google Patents

Rotation transmission device Download PDF

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Publication number
US20160195183A1
US20160195183A1 US14/901,063 US201314901063A US2016195183A1 US 20160195183 A1 US20160195183 A1 US 20160195183A1 US 201314901063 A US201314901063 A US 201314901063A US 2016195183 A1 US2016195183 A1 US 2016195183A1
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United States
Prior art keywords
section
sections
shaft
axial direction
end section
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Abandoned
Application number
US14/901,063
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English (en)
Inventor
Yasuyuki Matsuda
Daisuke Gunji
Masafumi Hikida
Kazutaka Tanaka
Tooru Ueda
Tetsu Takehara
Tomoharu Saito
Hiroyasu Yoshioka
Yuka Kaneko
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NSK Ltd
Original Assignee
NSK Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from JP2013132497A external-priority patent/JP6083333B2/ja
Priority claimed from JP2013224610A external-priority patent/JP6075266B2/ja
Priority claimed from JP2013224156A external-priority patent/JP2015087154A/ja
Priority claimed from JP2013225481A external-priority patent/JP6179350B2/ja
Priority claimed from JP2013229682A external-priority patent/JP6075269B2/ja
Priority claimed from JP2013229873A external-priority patent/JP6075270B2/ja
Priority claimed from JP2013229952A external-priority patent/JP2015090313A/ja
Priority claimed from JP2013231070A external-priority patent/JP2015090340A/ja
Application filed by NSK Ltd filed Critical NSK Ltd
Publication of US20160195183A1 publication Critical patent/US20160195183A1/en
Assigned to NSK LTD. reassignment NSK LTD. ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: TAKEHARA, TETSU, TANAKA, KAZUTAKA, SAITO, TOMOHARU, UEDA, TOORU, GUNJI, DAISUKE, HIKIDA, Masafumi, KANEKO, Yuka, MATSUDA, YASUYUKI, YOSHIOKA, HIROYASU
Abandoned legal-status Critical Current

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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16H—GEARING
    • F16H57/00—General details of gearing
    • F16H57/0018—Shaft assemblies for gearings
    • F16H57/0037—Special features of coaxial shafts, e.g. relative support thereof
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C19/00—Bearings with rolling contact, for exclusively rotary movement
    • F16C19/22—Bearings with rolling contact, for exclusively rotary movement with bearing rollers essentially of the same size in one or more circular rows, e.g. needle bearings
    • F16C19/34—Bearings with rolling contact, for exclusively rotary movement with bearing rollers essentially of the same size in one or more circular rows, e.g. needle bearings for both radial and axial load
    • F16C19/36—Bearings with rolling contact, for exclusively rotary movement with bearing rollers essentially of the same size in one or more circular rows, e.g. needle bearings for both radial and axial load with a single row of rollers
    • F16C19/364—Bearings with rolling contact, for exclusively rotary movement with bearing rollers essentially of the same size in one or more circular rows, e.g. needle bearings for both radial and axial load with a single row of rollers with tapered rollers, i.e. rollers having essentially the shape of a truncated cone
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C19/00—Bearings with rolling contact, for exclusively rotary movement
    • F16C19/22—Bearings with rolling contact, for exclusively rotary movement with bearing rollers essentially of the same size in one or more circular rows, e.g. needle bearings
    • F16C19/44—Needle bearings
    • F16C19/46—Needle bearings with one row or needles
    • F16C19/463—Needle bearings with one row or needles consisting of needle rollers held in a cage, i.e. subunit without race rings
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C33/00—Parts of bearings; Special methods for making bearings or parts thereof
    • F16C33/30—Parts of ball or roller bearings
    • F16C33/58—Raceways; Race rings
    • F16C33/581—Raceways; Race rings integral with other parts, e.g. with housings or machine elements such as shafts or gear wheels
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C33/00—Parts of bearings; Special methods for making bearings or parts thereof
    • F16C33/30—Parts of ball or roller bearings
    • F16C33/66—Special parts or details in view of lubrication
    • F16C33/6637—Special parts or details in view of lubrication with liquid lubricant
    • F16C33/6659—Details of supply of the liquid to the bearing, e.g. passages or nozzles
    • F16C33/6677—Details of supply of the liquid to the bearing, e.g. passages or nozzles from radial inside, e.g. via a passage through the shaft and/or inner ring
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16F—SPRINGS; SHOCK-ABSORBERS; MEANS FOR DAMPING VIBRATION
    • F16F15/00—Suppression of vibrations in systems; Means or arrangements for avoiding or reducing out-of-balance forces, e.g. due to motion
    • F16F15/10—Suppression of vibrations in rotating systems by making use of members moving with the system
    • F16F15/12—Suppression of vibrations in rotating systems by making use of members moving with the system using elastic members or friction-damping members, e.g. between a rotating shaft and a gyratory mass mounted thereon
    • F16F15/121—Suppression of vibrations in rotating systems by making use of members moving with the system using elastic members or friction-damping members, e.g. between a rotating shaft and a gyratory mass mounted thereon using springs as elastic members, e.g. metallic springs
    • F16F15/1216—Torsional springs, e.g. torsion bar or torsionally-loaded coil springs
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L3/00—Measuring torque, work, mechanical power, or mechanical efficiency, in general
    • G01L3/02—Rotary-transmission dynamometers
    • G01L3/04—Rotary-transmission dynamometers wherein the torque-transmitting element comprises a torsionally-flexible shaft
    • G01L3/10—Rotary-transmission dynamometers wherein the torque-transmitting element comprises a torsionally-flexible shaft involving electric or magnetic means for indicating
    • G01L3/101—Rotary-transmission dynamometers wherein the torque-transmitting element comprises a torsionally-flexible shaft involving electric or magnetic means for indicating involving magnetic or electromagnetic means
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L3/00—Measuring torque, work, mechanical power, or mechanical efficiency, in general
    • G01L3/02—Rotary-transmission dynamometers
    • G01L3/04—Rotary-transmission dynamometers wherein the torque-transmitting element comprises a torsionally-flexible shaft
    • G01L3/10—Rotary-transmission dynamometers wherein the torque-transmitting element comprises a torsionally-flexible shaft involving electric or magnetic means for indicating
    • G01L3/101—Rotary-transmission dynamometers wherein the torque-transmitting element comprises a torsionally-flexible shaft involving electric or magnetic means for indicating involving magnetic or electromagnetic means
    • G01L3/104—Rotary-transmission dynamometers wherein the torque-transmitting element comprises a torsionally-flexible shaft involving electric or magnetic means for indicating involving magnetic or electromagnetic means involving permanent magnets
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L3/00—Measuring torque, work, mechanical power, or mechanical efficiency, in general
    • G01L3/02—Rotary-transmission dynamometers
    • G01L3/04—Rotary-transmission dynamometers wherein the torque-transmitting element comprises a torsionally-flexible shaft
    • G01L3/10—Rotary-transmission dynamometers wherein the torque-transmitting element comprises a torsionally-flexible shaft involving electric or magnetic means for indicating
    • G01L3/101—Rotary-transmission dynamometers wherein the torque-transmitting element comprises a torsionally-flexible shaft involving electric or magnetic means for indicating involving magnetic or electromagnetic means
    • G01L3/105—Rotary-transmission dynamometers wherein the torque-transmitting element comprises a torsionally-flexible shaft involving electric or magnetic means for indicating involving magnetic or electromagnetic means involving inductive means
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L3/00—Measuring torque, work, mechanical power, or mechanical efficiency, in general
    • G01L3/02—Rotary-transmission dynamometers
    • G01L3/04—Rotary-transmission dynamometers wherein the torque-transmitting element comprises a torsionally-flexible shaft
    • G01L3/10—Rotary-transmission dynamometers wherein the torque-transmitting element comprises a torsionally-flexible shaft involving electric or magnetic means for indicating
    • G01L3/109—Rotary-transmission dynamometers wherein the torque-transmitting element comprises a torsionally-flexible shaft involving electric or magnetic means for indicating involving measuring phase difference of two signals or pulse trains
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C2361/00—Apparatus or articles in engineering in general
    • F16C2361/65—Gear shifting, change speed gear, gear box
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16H—GEARING
    • F16H59/00—Control inputs to control units of change-speed- or reversing-gearings for conveying rotary motion
    • F16H59/14—Inputs being a function of torque or torque demand
    • F16H2059/147—Transmission input torque, e.g. measured or estimated engine torque

Definitions

  • the present invention relates to a rotation transmission device that is assembled in various kinds of machinery such as an automatic transmission for an automobile, and has a function for transmitting torque using a rotary shaft, as well as a function for measuring the torque that is transmitted by that rotary shaft.
  • An automatic transmission for an automobile includes a mechanism that measures the rotational speed of a rotary shaft of the automatic transmission, and measures the torque that the rotary shaft transmits, and then performs transmission control for controlling the automatic transmission itself, or output control for controlling the output of the engine.
  • a device for measuring torque is a device disclosed in JPH01254826 (A) that converts the amount of elastic torsional deformation of the rotary shaft that transmits torque to a phase difference of output signals from a pair of sensors, and measures the torque based on the phase difference.
  • FIG. 66 illustrates a first example of a conventional torque measurement device that includes this kind of construction.
  • This torque measurement device includes a pair of encoders 2 that are fastened on the outside of the rotary shaft 1 at two locations in the axial direction of the rotary shaft 1 , and sensors 3 that correspond to each of the encoders 2 and that are supported in a housing that is not illustrated in the figure.
  • the outer-circumferential surfaces of these encoders 2 function as detected sections, and the magnetic characteristics of these encoders 2 change in an alternating manner at a uniform pitch in the circumferential direction.
  • the pitches at which the magnetic characteristics vary in the circumferential direction on the outer-circumferential surface of these encoders 2 are equal to each other.
  • the sensors 3 are arranged so that the detecting sections of the sensors 3 face the outer-circumferential surfaces of the encoders 2 . These sensors 3 cause the output signals that are outputted from the sensors 3 to change according to the change in the magnetic characteristics on the outer-circumferential surfaces of the encoders 2 that the detecting sections face.
  • the output signals from the sensors 3 change periodically as the encoders 2 rotate together with the rotary shaft 1 .
  • the frequency and period of this change are values that correspond to the rotational speed of the rotary shaft 1 . Therefore, it is possible to find the rotational speed of the rotary shaft 1 based on that frequency and period.
  • the rotary shaft 1 transmits torque
  • the rotary shaft 1 undergoes elastic torsional deformation, which causes relative displacement between the encoders 2 .
  • This phase difference ratio is a value that corresponds to the amount of elastic torsional deformation of the rotary shaft 1 due to transmitting torque. Therefore, the torque that the rotary shaft 1 transmits can be found based on this phase difference ratio.
  • the torsional rigidity of the rotary shaft 1 that is the target of torque measurement is high, so there is a problem in that it is difficult to sufficiently maintain the amount of elastic torsional deformation of the rotary shaft 1 , and the resolution of the torque measurement becomes low.
  • it is necessary to install the two sensors 3 so as to be separated in the axial direction so there is also a problem in that it becomes difficult to arrange two harnesses 4 that run from these sensors 3 .
  • JPH01254826 (A) discloses a torque measurement device in which the sensors have a unit-like construction.
  • FIG. 67 illustrates a second example of a conventional torque measurement device that has this kind of construction.
  • the detected sections of a pair of encoders 2 a that are fastened at two locations in the axial direction of the rotary shaft 1 extend toward the center section in the axial direction, and detecting sections of a pair of sensors of a single sensor unit 5 that is placed in the center section in the axial direction of the rotary shaft 1 faces the detected sections of the encoders 2 a .
  • the torque measurement device of this second example of conventional construction to an automatic transmission for an automobile as well, even though the installation of the sensor unit 5 is simplified, it does not mean that the problem of low resolution of the torque measurement has been solved.
  • JPH02017311 discloses a torque measurement device having construction that uses a torsion bar. More specifically, the torque measurement device of this third example of conventional construction is constructed so that encoders are fastened to the outer-circumferential surfaces of a pair of rotary shafts that are arranged along the same line, and these rotary shafts are connected by a torsion bar that undergoes elastic torsional deformation more easily than these rotary shafts. In this case, the amount of relative displacement in the rotational direction between the encoders can be made large due to the elastic torsional deformation of the torsion bar that occurs when transmitting torque, so it is possible to improve the resolution of the torque measurement.
  • JP2010185478 A torsion bar having high fatigue strength and that is able to handle large stress loads, and a manufacturing method for manufacturing that torsion bar are disclosed in JP2010185478 (A).
  • the object of the present invention is to achieve construction of a rotation transmission device that can measure transmitted torque by using only a pair of encoders and one sensor unit, and that can increase the resolution of the torque measurement regardless of whether the space in the axial direction between a pair of gears is large or small.
  • the rotation transmission device of the present invention includes a rotary-shaft unit, a first gear, a second gear, a first encoder, a second encoder and a sensor unit.
  • the rotary-shaft unit includes: a first rotary shaft and a second rotary shaft that are both hollow, and together with being arranged so as to be concentric with each other, are combined so that the end sections of each are able to rotate relative to each other, and in this state are supported by a housing so as to rotate freely; and a torsion bar that is hollow and concentrically arranged on the inner-diameter side of the first and second rotary shafts, with one end section being connected to the first rotary shaft so that relative rotation is not possible, and the other end section being connected to the second rotary shaft so that relative rotation is not possible.
  • the first gear is provided in the middle section in the axial direction of the outer-circumferential surface of the first rotary shaft.
  • the second gear is provided in the middle section in the axial direction of the outer-circumferential surface of the second rotary shaft.
  • the first and second gears can be made to be separate from the first and second rotary shafts and fastened to the middle sections in the axial direction of the outer-circumferential surfaces of the first and second rotary shafts, or can be integrally formed with the middle sections in the axial direction of the outer-circumferential surfaces of the first and second rotary shafts.
  • the first encoder is fastened to one of the first and second rotary shafts so as to be concentric with the one rotary shaft, and has a first detected section that is magnetized so that the magnetic characteristics change in an alternating manner at a uniform pitch.
  • a second encoder is fastened to the other of the first and second rotary shafts so as to be concentric with the other rotary shaft, and has a second detected section that is magnetized so that the magnetic characteristics change in an alternating manner at a uniform pitch.
  • the first and second detected sections can be circular ring-shaped, or can be circular disk-shaped.
  • the first and second encoders can be made separate from the rotary shafts, or members that rotate in synchronization with the rotary shafts and fastened to and supported by the rotary shafts or these members, or can be integrally formed with these members.
  • the sensor unit is supported by the housing, and comprises at least one sensor that faces the first and second detected sections, and causes an output signal to change in correspondence to the change in magnetic characteristics of a portion of the first and second detected section where the at least one sensor faces.
  • the first encoder is directly or indirectly fastened to an input shaft, which is the first rotary shaft
  • the second encoder is directly or indirectly fastened to an output shaft, which is the second rotary shaft.
  • the torsion bar includes a spring section, which is a portion in the middle section in the axial direction of the torsion bar that undergoes elastic torsional deformation when torque is transmitted; the dimensions of that spring section being larger than the space in the axial direction between the first and second gears.
  • the spring section includes a tube section having a wall thickness in the radial direction in the middle section in the axial direction except for the portions of the edges on both ends in the axial direction that is less than those portions of the edges on both ends in the axial direction, and is such that the inner-circumferential surface and outer-circumferential surface are single cylindrical surfaces that are concentric with each other; the ratio di/do of the inner-diameter dimension di and outer-diameter dimension do of that tube section being within the range 0.5 ⁇ di/do ⁇ 0.8.
  • the ten-point average roughness Rz of that tube section is within the range Rz ⁇ 22 ⁇ m.
  • one end section and the other end section of the torsion bar are connected to the end sections of the first and second rotary shafts that are opposite the end sections that are combined together.
  • the end sections of the first and second rotary shafts that are combined together are one end section of the second rotary shaft and the other end section of the first rotary shaft
  • the one end section of the torsion bar is connected to the one end section of the first rotary shaft
  • the other end section of the torsion bar is connected to the other end section of the second rotary shaft.
  • a coupling shaft that is arranged on the inner-diameter side of the torsion bar and arranged concentric with the torsion bar, with one end section thereof being connected to the one rotary shafts so that relative rotation is not possible, and the other end section protruding in the axial direction from the end section of the torsion bar, the first encoder is fastened to the other end section of the coupling shaft, the second encoder is fastened to the end section of the other rotary shaft on the other end section side of the coupling shaft so as to be close to the first encoder, and the first and second detected sections are arranged so as to be close to each other (for example, arranged with a space between of less than 10 mm, and more preferably, less than 5 mm).
  • the end sections of the first and second rotary shafts that are combined together are taken to be one end section of the second rotary shaft and the other end section of the first rotary shaft, one end section of the torsion bar is connected to the one end section of the first rotary shaft, and the other end section of the torsion bar is connected to the other end section of the second rotary shaft, one end section of the coupling shaft is connected to the one end section of the first rotary shaft, and the other end section of the coupling shaft protrudes in the axial direction of the other end section of the second rotary shaft, and together with the first encoder being fastened to the other end section of the coupling shaft, the second encoder is fastened to the other end section of the second rotary shaft.
  • the first and second encoders and the sensor unit are arranged on one end section in the axial direction of the rotary-shaft unit (the one end section in the axial direction or the other end section in the axial direction).
  • a sliding bearing is provided between the inner-circumferential surface of the end section of the other rotary shaft on the other end section side of the coupling shaft and the outer-circumferential surface of the coupling shaft or a fitting cylindrical section of a metal core of the first encoder that fits on the coupling shaft.
  • a rim section is provided on the outer-circumferential surface of the one end section of the coupling shaft, and the coupling shaft is supported by the one rotary shaft so that relative rotation is not possible with the rim section being pressure fitted with the inner-circumferential surface of the end section of the one rotary shaft on the one end side of the coupling shaft.
  • the other rotary shaft is supported by the housing so as to rotate freely using a rolling bearing that is located between the portion of the outer-circumferential surface of the other rotary shaft that is near the end section on the other end section side of the coupling shaft and the inner-circumferential surface of the housing; and the sensor unit includes a sensor cover and a detecting section that is fastened to and supported by the inside of the sensor cover; and by fastening the sensor cover to and supporting the sensor cover by the end section of the outer ring of the rolling bearing on the other end section side of the coupling shaft of the other rotary shaft so that the first and second encoders are located in a space inside the sensor cover, the detecting section is made to face the first and second detected sections.
  • the second rotary shaft is supported by the housing by a rolling bearing that is located between a portion of the second rotary shaft near the other end and the inner-circumferential surface of the housing, the sensor cover of the sensor unit is fastened to and supported by the end section of the outer ring of the rolling bearing on the other end section side of the second rotary shaft, and the first encoder that is fastened to the other end section of the coupling shaft, and the second encoder that is fastened to the other end section of the second rotary shaft are located in a space inside the sensor cover.
  • a seal device is located between the space where plural rolling bodies of the rolling bearing are located and the space on the inside of the sensor cover where the first and second detected sections are located, and functions as a partition between these spaces.
  • the other rotary shaft is supported by the housing so as to rotate freely using a rolling bearing that is located between the portion of the outer-circumferential surface of the other rotary shaft near the end section on the other end section side of the coupling shaft and the inner-circumferential surface of the housing, and the second encoder is fastened around the outside of the end section of the inner ring of the rolling bearing on the other end section side of the coupling shaft.
  • the second rotary shaft is supported by the housing using a rolling bearing that is located between a portion of the outer-circumferential surface of the second rotary shaft near the other end and the inner-circumferential surface of the housing, and the second encoder is fastened around the outside of the other end section of the inner ring of the rolling bearing.
  • the first and second detected sections can both be cylindrical shaped, and at least one end section in the axial direction of the first and second detected sections can be arranged around the outer-diameter side of the end section of the other rotary shaft on the other end section side of the coupling shaft, or of another part that is fastened around the outside of the end section, in a position that overlaps in the radial direction that end section of the other rotary shaft or the other part.
  • at least part of the cylindrical shaped first and second detected sections is arranged around the outer-diameter side of the other end section of the second rotary shaft or of construction that is fastened to the end section, in a position that overlaps these in the radial direction.
  • the first encoder is fastened to the first rotary shaft in a position between the first and second gears in the axial direction
  • the second encoder is fastened to the second rotary shaft in a position between the first and second gears in the axial direction. That is to say, in this form, the first and second encoders and the sensor unit are arranged in the middle section in the axial direction of the rotary-shaft unit.
  • the rotary-shaft unit is supported by the housing by plural rolling bearings so as to rotate freely; and the first rotary shaft or second rotary shaft is integrally formed with the inner ring of at least one of the plural rolling bearings.
  • the first rotary shaft or second rotary shaft is integrally formed with the torsion bar.
  • the sensor unit includes a first sensor that faces the first detected section, and a second sensor that faces the second detected section, and the first and second sensors generate output signals that change in correspondence to the change in magnetic characteristics of the portions of the first and second detected sections that the first and second sensors face; where the first and second detected sections can both be circular ring-shaped and arranged close to each other in the axial direction of the rotary-shaft unit; and in that case, the first and second sensors are made to face the first and second detected sections in the radial direction of the rotary-shaft unit.
  • first and second detected sections can both be circular disk-shaped and arranged close to each other in the radial direction of the rotary-shaft unit; and in that case, the first and second sensors are made to face the first and second detected sections in the axial direction of the rotary-shaft unit.
  • the first and second encoders are made of a magnetic material;
  • the first and second detected sections include sections with material removed and solid sections that are arranged in an alternating manner at a uniform pitch in the circumferential direction, and are arranged so as to be close to each other and overlap in the radial or axial direction;
  • the sensor unit includes a stator made of a magnetic material, and plural coils that are made of one conducting wire, and is constructed so that when a driving voltage is applied to the conducting wire, the output current or the output voltage from the conducting wire is used as an output signal;
  • the stator includes: plural core sections that are arranged at a uniform pitch in the circumferential direction, extend in the overlapping direction of the first and second detected sections, and the tip-end surfaces face one of the first and second detected sections from one side in the overlapping direction of the first and second detected sections; and a circular ring-shaped rim section that connects together the base-end sections of the plural core sections; and the plural coils are fastened one by one around the plural core sections
  • the first and second encoders are made of a magnetic material;
  • the first and second detected sections include sections with material removed and solid sections that are arranged in an alternating manner at a uniform pitch in the circumferential direction, and the solid sections of the first detected section and the solid sections of the second detected section are arranged in an alternating manner in the circumferential direction with a space in between each in the circumferential direction;
  • the sensor unit includes one sensor that faces the portion where the solid sections of the first and second detected sections are alternatingly arranged, and the sensor generates an output signal that changes in correspondence to the change in the magnetic characteristics of the portion where the sensor faces the solid sections of the first and second detected sections are alternatingly arranged.
  • the first and second detected sections include a pair of cylindrical surfaces that face each other in the radial direction or a pair of circular ring surfaces that face each other in the axial direction, and are arranged so the S poles and N poles of these detected sections alternate at a uniform pitch in the circumferential direction; and the sensor unit includes a magnetism-detecting element or coil that is arranged between the first and second detected sections, and the output voltage or output current from that magnetism detecting unit, or the output voltage or output current from the coil is used as the output signal.
  • the end sections of the first and second rotary shafts are combined in a state in which displacement in a direction in the axial direction toward each other is prevented
  • the first and second gears are both helical gears
  • the directions of inclination of the first and second gears are regulated so as to be directions in which the gear reaction forces in the axial direction that act on the first and second gears during forward operation of the first and second gears (rotation in a direction of rotation that occurs often during use, for example, rotation when the automobile is moving forward) are toward each other (press toward each other).
  • one of the combination cylindrical sections of the first combination cylindrical section that is provided on the other end section of the first rotary shaft and the second combination cylindrical section that is provided on one end section of the second rotary shaft is inserted into the inner-diameter side of the other combination cylindrical section, a radial bearing (radial rolling bearing, or radial sliding bearing) is placed between the opposing circumferential surfaces of the first and second combination cylindrical sections, and a thrust bearing (thrust rolling bearing, or thrust sliding bearing) is placed between a stepped surface that is provided on the base-end section of the outer-circumferential surface of one of the combination cylindrical sections, and the tip-end surface of the other combination cylindrical section.
  • a radial bearing radial rolling bearing, or radial sliding bearing
  • a thrust bearing thrust rolling bearing, or thrust sliding bearing
  • a pair of sections with material removed that connect a pair of spaces that exist in positions on both sides in the radial direction of the portion between the stepped surface and the tip-end surface are formed at one or plural location in the circumferential direction of the thrust washer (preferably, plural evenly spaced locations).
  • the sections with material removed it is possible to use slits or through holes that pass through both side surfaces of the thrust washer, or it is also possible to use concave grooves that are provided in at least one of the side surfaces of the thrust washer.
  • the outer-circumferential edge of the thrust washer protrudes outward in the radial direction from a portion between the stepped surface and the tip-end surface, and a reinforcing cylindrical section is formed around the entire outer-circumferential edge.
  • a first male spline section that has a first plating layer on the surface layer thereof is provided on the outer-circumferential surface of one end section of the torsion bar, and a first female spline section that is able to engage with the first male spline section is provided on the inner-circumferential surface of the first rotary shaft.
  • the metal of the first plating layer is a metal that is softer than the metal of the torsion bar and first rotary shaft.
  • a second male spline section having a second plating layer on the surface layer thereof is provided on the outer-circumferential surface of the other end section of the torsion bar, and a second female spline section that is able to engage with the second male spline section is provided on the inner-circumferential surface of the second rotary shaft.
  • the metal of the second plating layer is a metal that is softer than the metal of the torsion bar and second rotary shaft.
  • the metal material of the first and second plating layers is copper or nickel.
  • the output signal from the sensor unit changes in correspondence to the rotational speed due to the first and second encoders (first and second detected sections) rotating together with the rotary-shaft unit (first and second rotary shafts). Therefore, when necessary, it is possible to measure the rotational speed based on the output signal from the sensor unit. Moreover, when the rotary-shaft unit transmits torque between the first and second gears, there is relative displacement in the direction of rotation between the first and second gears (between the first and second rotary shafts, and between the first and second encoders) as elastic torsional deformation occurs in the middle section in the axial direction of the torsion bar.
  • the output signal from the sensor unit changes in correspondence to that relative displacement (size of the torque). Therefore, it is possible to measure the torque based on the output signal from the sensor unit.
  • the first rotary shaft that is provided with the first gear in the middle section in the axial direction of the outer-circumferential surface thereof, and the second rotary shaft that is provided with the second gear in the middle section in the axial direction of the outer-circumferential surface are both hollow, the torsion bar is arranged on the inner-diameter side of these rotary shafts and both end sections of the torsion bar are connected to these rotary shafts so that no relative rotation is possible.
  • the case of the present invention differs from construction in which the rotary-shaft unit is one rotary in that it is possible to sufficiently increase the amount of relative displacement in the direction of rotation between the first and second gears (first and second rotary shaft, first and second encoders) that occurs when torque is transmitted, regardless of whether the space in the axial direction between the first and second gears is large or small. Therefore, it is possible to sufficiently increase the resolution of the torque measurement.
  • the rotary-shaft unit is a single rotary shaft, it is easy to plan and design the relationship (gain) between the torque and the amount of relative displacement in the direction of rotation of the first and second encoders.
  • the first and second encoders can be arranged so as to be concentrated at one end section of the rotary-shaft unit, or more specifically, at one end section of the input shaft, which is the first rotary shaft, or the other end section of the output shaft, which is the second rotary shaft. Therefore, the sensor unit can be supported by a portion of the housing that is near the end section having high rigidity, and thus it is possible to maintain precision of torque measurement by the sensor unit regardless of deformation of the housing due to gear reaction forces in the radial direction that act on the first and second gears (input gear and output gear) when torque is being transmitted.
  • only one sensor is used, so only one harness that leads from the sensor unit needs to be used, and that harness can be easily installed.
  • only one support and fastening section needs to be provided in the housing for the sensor unit, so processing the housing can be performed easily.
  • FIG. 1 is a perspective view illustrating a rotation transmission device of a first example of an embodiment of the present invention
  • FIG. 2 is a side view of the rotation transmission device illustrated in FIG. 1 ;
  • FIG. 3 is an end view of the other end side of the rotation transmission device illustrated in FIG. 1 ;
  • FIG. 4 is an end view of the one end side of the rotation transmission device illustrated in FIG. 1 ;
  • FIG. 5 is an exploded perspective view of the rotation transmission device illustrated in FIG. 1 ;
  • FIG. 6 is a cross-sectional view of section a-a in FIG. 3 of the rotation transmission device illustrated in FIG. 1 ;
  • FIG. 7 is an enlarged view of the other end section of the rotation transmission device illustrated in FIG. 1 ;
  • FIG. 8 is an enlarged view of area b in FIG. 6 (where the end sections of the input shaft and output shaft are combined together);
  • FIG. 9 is a view as seen from the outer-diameter side of part in the circumferential direction of the first detected section and second detected section of the encoder of the rotation transmission device illustrated in FIG. 1 ;
  • FIG. 10 is an enlarged cross-sectional view of the area of the rotation transmission device illustrated in FIG. 1 where the sensor unit faces the encoders;
  • FIG. 11A to FIG. 11C are perspective views that illustrate three examples of a thrust washer that can be applied in the rotation transmission device illustrated in FIG. 1 ;
  • FIG. 12 is a cross-sectional view for explaining the torque transmission path in the rotation transmission device illustrated in FIG. 1 ;
  • FIG. 13 is a view as seen from the outer-diameter side of the a portion in the circumferential direction of the first detected section and second detected section of the encoder in a rotation transmission device of a second example of an embodiment of the present invention
  • FIG. 14 is an enlarged cross-sectional view of the area where the sensor unit faces the encoders in the rotation transmission device of the second example of an embodiment of the present invention.
  • FIG. 15A is an end view of a first encoder
  • FIG. 15B is an end view of a second encoder of the rotation transmission device of a third example of an embodiment of the present invention
  • FIG. 16 is an enlarged cross-sectional view of the area where the sensor unit faces the encoders in the rotation transmission device of the third example of an embodiment of the present invention, and illustrates a state in which the first encoder and second encoder are joined by pins;
  • FIG. 17 is a perspective view of a first encoder and a second encoder of a rotation transmission device of a fourth example of an embodiment of the present invention.
  • FIG. 18A is an end view of a first encoder
  • FIG. 18B is an end view of a second encoder in a rotation transmission device of a fifth example of an embodiment of the present invention
  • FIG. 19 is an enlarged cross-sectional view of a part in the circumferential direction of an involute spline engagement between a torsion bar and input shaft or output shaft in a rotation transmission device of a sixth example of an embodiment of the present invention.
  • FIG. 20 is an enlarged cross-sectional view of part in the circumferential direction of the involute spline engagement illustrated in FIG. 19 , and illustrates a state before providing a plating layer on the surface of the male involute spline section;
  • FIG. 21 is a graph illustrating the relationship between the sensor output and the transmitted torque in the rotation transmission device of the sixth example of an embodiment of the present invention.
  • FIG. 22 is an enlarged cross-sectional view of one end of a rotation transmission device of a seventh example of an embodiment of the present invention.
  • FIG. 23 is an enlarged perspective view of one end of a coupling shaft that is used in the seventh example of an embodiment of the present invention.
  • FIG. 24 is a cross-sectional view in the axial direction that illustrates a rotation transmission device together with the sensor of an eighth example of an embodiment of the present invention.
  • FIG. 25 is an enlarged cross-sectional view of the other end section of a rotation transmission device of a ninth example of an embodiment of the present invention.
  • FIG. 26 is an end view of the other end side of the rotation transmission device illustrated in FIG. 25 ;
  • FIG. 27 is a cross-sectional view of section c-c in FIG. 25 of the rotation transmission device illustrated in FIG. 25 ;
  • FIG. 28 is an exploded perspective view of the first encoder, the second encoder and the sensor unit of the rotation transmission device illustrated in FIG. 25 ;
  • FIG. 29A is a view of a part in the circumferential direction of the area where the sensor unit faces the encoders in the rotation transmission device illustrated in FIG. 25 , and illustrates a state in which torque is not transmitted;
  • FIG. 29B illustrates this part in a state in which torque is transmitted;
  • FIG. 29C is a graph illustrating the output signals from the sensor unit of this device when torque is not transmitted and when torque is transmitted;
  • FIG. 30 is an enlarged vice of the other end section of a rotation transmission device of a tenth example of an embodiment of the present invention.
  • FIG. 31 is a view as seen from the outer-diameter side of an encoder of the rotation transmission device illustrated in FIG. 30 ;
  • FIG. 32 is an end view of the other end section of the rotation transmission device illustrated in FIG. 30 , and illustrates a state in which the sensor unit is omitted;
  • FIG. 33 is an exploded perspective view of the encoders of the rotation transmission device illustrated in FIG. 30 , and illustrates a state in which the first encoder and second encoder are separated;
  • FIG. 34A is a graph for the rotation transmission device of the tenth example of an embodiment of the present invention, and illustrates the output signal of the sensor unit when torque is not transmitted; and FIG. 34B is a graph that illustrates the output signal of the sensor unit when torque is transmitted;
  • FIG. 35 is a graph for the rotation transmission device of the tenth example of an embodiment of the present invention, and illustrates the relationship between the duty ratio s of the output signal of the sensor and the torque;
  • FIG. 36 is an enlarged cross-sectional view that illustrates the other end section of a rotation transmission device of an eleventh example of an embodiment of the present invention.
  • FIG. 37 is an end view of the other end side of the rotation transmission device illustrated in FIG. 36 ;
  • FIG. 38 is an exploded perspective view of the encoders of the rotation transmission device illustrated in FIG. 36 , and illustrates a state in which a first encoder and a second encoder are separated;
  • FIG. 39 is an enlarged cross-sectional view of the other end section of a rotation transmission device of a twelfth example of an embodiment of the present invention.
  • FIG. 40 is an end view of the other end side of the rotation transmission device illustrated in FIG. 39 ;
  • FIG. 41A is a schematic drawing illustrating the positional relationship between the magnetic poles of the first detected section and second detected section and the detecting section of the sensor in the area where the sensor unit faces the encoders in the rotation transmission device illustrated in FIG. 39 in a state in which torque is not transmitted; and FIG. 41B illustrates that positional relationship in a state in which torque is transmitted;
  • FIG. 42 is a graph illustrating the output signal from the sensor unit of the rotation transmission device of the twelfth example of an embodiment of the present invention.
  • FIG. 43 is a cross-sectional view illustrating a rotation transmission device of a thirteenth example of an embodiment of the present invention.
  • FIG. 44 is a cross-sectional view illustrating a rotation transmission device of a fourteenth example of an embodiment of the present invention.
  • FIG. 45 is a cross-sectional view illustrating a rotation transmission device of a fifteenth example of an embodiment of the present invention.
  • FIG. 46 is a cross-sectional view illustrating a rotation transmission device of a sixteenth example of an embodiment of the present invention.
  • FIG. 47 is a cross-sectional view illustrating a rotation transmission device of a seventeenth example of an embodiment of the present invention.
  • FIG. 48 is an enlarged view illustrating the section where the end sections of the input shaft and output shaft of a rotation transmission device of an eighteenth example of the present invention are combined together;
  • FIG. 49 is an enlarged view illustrating the section where the end sections of the input shaft and output shaft of a rotation transmission device of a nineteenth example of the present invention are combined together;
  • FIG. 50 is a cross-sectional view illustrating the torsion bar of a rotation transmission device of a twentieth example of an embodiment of the present invention.
  • FIG. 51 is a cross-sectional view of a device that was used in testing that was performed for confirming the effect on the durability and precision of torque measurement for the rotation transmission device of the twentieth example of an embodiment of the present invention.
  • FIG. 52 is a cross-sectional view illustrating a rotation transmission device of a twenty-first example of an embodiment of the present invention.
  • FIG. 53 is a cross-sectional view illustrating a rotation transmission device of a twenty-second example of an embodiment of the present invention.
  • FIG. 54 is a cross-sectional view illustrating a rotation transmission device of a twenty-third example of an embodiment of the present invention.
  • FIG. 55 is a cross-sectional view illustrating a rotation transmission device of a twenty-fourth example of an embodiment of the present invention.
  • FIG. 56 is a cross-sectional view illustrating a rotation transmission device of a twenty-fifth example of an embodiment of the present invention.
  • FIG. 57 is an enlarged cross-sectional view of the other end section of the rotation transmission device illustrated in FIG. 56 ;
  • FIG. 58 is an enlarged cross-sectional view illustrating one end section of a rotation transmission device of a twenty-sixth example of an embodiment of the present invention.
  • FIG. 59 is an enlarged cross-sectional view illustrating the other end section of a rotation transmission device of a twenty-seventh example of an embodiment of the present invention.
  • FIG. 60 is an end view of the other end section of the rotation transmission device illustrated in FIG. 59 ;
  • FIG. 61 is an enlarged cross-sectional view illustrating the other end section of a rotation transmission device of a twenty-eighth example of an embodiment of the present invention.
  • FIG. 62 is a side view illustrating a rotation transmission device of a twenty-ninth example of an embodiment of the present invention.
  • FIG. 63 is a cross-sectional view of section d-d in FIG. 62 of the rotation transmission device illustrated in FIG. 62 ;
  • FIG. 64 is a cross-sectional view of section e-e in FIG. 62 of the rotation transmission device illustrated in FIG. 62 ;
  • FIG. 65 is a cross-sectional view of section f-f in FIG. 63 of the rotation transmission device illustrated in FIG. 62 ;
  • FIG. 66 is a side view illustrating a torque measurement device of a first example of conventional construction.
  • FIG. 67 is a side view illustrating a torque measurement device of a second example of conventional construction, and illustrates a state in which part is cut away.
  • FIG. 1 to FIG. 12 illustrate a first example of an embodiment of the present invention.
  • the rotation transmission device of this example is incorporated and used with a counter shaft and counter gear portion of an automatic transmission for an automobile such as a front-wheel drive automobile or a four-wheel drive automobile that uses the same motor and transmission arrangement as a front-wheel drive automobile in which a so-called transverse engine is mounted.
  • the rotation transmission device of this example includes: a rotary-shaft unit 6 that functions as a counter shaft; a first gear, which is an input gear 7 , and a second gear, which is an output gear 8 , that function as counter gears; a coupling shaft 9 , a first encoder 10 , a second encoder 11 and one sensor unit 12 .
  • the rotary-shaft unit 6 includes: an input shaft 13 , which is a hollow first rotary shaft; an output shaft 14 , which is a hollow second rotary shaft; and a hollow torsion bar 15 .
  • Both the input shaft 13 and the output shaft 14 are formed into a cylindrical shape using steel, are arranged concentric with each other, and the end sections of the input shaft 13 and the output shaft 14 (the other end section of the input shaft 13 and the one end section of the output shaft 14 ) are combined together so as to be able to rotate relative to each other.
  • an input-side combination cylindrical section 16 which is a first combination cylindrical section, is provided on the other end section of the input shaft 13
  • an output-side combination cylindrical section 17 having an inner diameter that is larger than the diameter of the input-side combination cylindrical section 16 , is provided on the one end section of the output shaft 14 .
  • the input-side combination cylindrical section 16 is inserted into the inner-diameter side of the output-side combination cylindrical section 17 .
  • a radial needle bearing 18 is provided between the cylindrical shaped circumferential surfaces of the input-side and output side combination cylindrical sections 16 , 17 that face each other.
  • a circular disk-shaped thrust washer 21 which is a thrust sliding bearing, is held between a stepped surface 19 that is provided on the base end section of the outer-circumferential surface of the input-side combination cylindrical section 16 and the tip-end surface 20 of the output-side combination cylindrical section 17 .
  • slits 22 that are long in the radial direction are formed by removing material at plural locations that are uniformly spaced in the circumferential direction of a circular disk-shaped main portion so as to be open on the inner-circumferential edge of the main portion.
  • a reinforcing cylindrical section 23 that is bent in the radial direction at a right angle from the outer-circumferential edge of the main portion of the thrust washer 21 is formed around the entire outer-circumferential edge.
  • the thrust washer 21 is fitted around the base end section of the input-side combination cylindrical section 16 with the edge of the tip end of the reinforcing cylindrical section 23 facing the one end side of the input shaft 13 so that there is no large looseness in the radial direction.
  • the middle section in the radial direction of the main portion of the thrust washer 21 is held between the stepped surface 19 and the tip-end surface 20 .
  • the slits 22 connect a pair of spaces that exist on both sides in the radial direction of the portion between the stepped surface 19 and the tip-end surface 20 with each other.
  • the diameter of the inscribed circle of the slits 22 (the inner diameter of the main portion of the thrust washer 21 ) is made to be smaller than the diameter of the inner-circumferential edge of the tip-end surface 20
  • the diameter of the circumscribed circle of the slits 22 is made to be larger than the diameter of the outer-circumferential edge of the tip-end surface 20 .
  • the torsion bar 15 is formed into a cylindrical shape using a steel alloy such as carbon steel, and is concentrically arranged on the inner-diameter side of the input shaft 13 and output shaft 14 .
  • One end section of the torsion bar 15 is connected to the input shaft 13 so that relative rotation is not possible, and the other end section is connected to the output shaft 14 so that relative rotation is not possible.
  • the outer-diameter dimensions of both end sections of the torsion bar 15 are made to be a little less than the outer-diameter dimension of the middle section of the torsion bar 15 , and the outer-circumferential surfaces of both end sections of the torsion bar 15 fit with the portion near one end of the inner-circumferential surface of the input shaft 13 and with the portion near the other end of the inner-circumferential surface of the output shaft 14 so that relative rotation is not possible.
  • an involute spline connection 24 a is formed by fitting a first male involute spline section 62 , which is a first male spline section that is provided on the outer-circumferential surface of one end section of the torsion bar 15 , with a first female involute spline section 63 , which is a first female spline section that is provided on the inner-circumferential surface of the one end section of the input shaft 13 so that there is no looseness in the circumferential direction.
  • an involute spline connection 24 b is formed by fitting a second male involute spline section 64 , which is a second male spline section that is provided on the outer-circumferential surface of the other end section of the torsion bar 15 , with a second female involute spline section 65 , which is a second female spline section that is provided on the inner-circumferential surface of the other end section of the input shaft 14 so that there is no looseness in the circumferential direction. It is also possible to use other construction for preventing rotation such as the connections between the torsion bar 15 and the input shaft 13 and output shaft 14 .
  • the torsion bar 15 By holding the torsion bar 15 on both sides in the axial direction by a pair of retaining rings 25 a , 25 b that are fastened around the inner-circumferential surfaces of the input shaft 13 and output shaft 14 , the torsion bar 15 is prevented from displacing in the axial direction.
  • the dimension L of the portion in the middle section in the axial direction of the torsion bar 15 that undergoes elastic torsional deformation when torque is transmitted is made to be larger than the space W in the axial direction between the input gear 7 and output gear 8 (L>W) (in the example in the figures, L is a little over 4 times W).
  • the input gear 7 is a helical gear that is formed using a steel alloy such as carbon steel, and is fastened around the outside of the middle section of the input shaft 13 .
  • the connection between the inner-circumferential surface of the input gear 7 and the outer-circumferential surface of the input shaft 13 is formed by arranging a cylindrical connecting section 26 a that is for maintaining concentricity (connecting section that is formed by pressure fitting together the cylindrical surface sections of the inner-circumferential surface of the input gear 7 and outer-circumferential surface of the input shaft 13 ) and an involute spline connection 24 c that is for preventing relative rotation so as to be adjacent to each other in the axial direction.
  • positioning the input gear 7 in the axial direction with respect to the input shaft 13 is accomplished by bringing the inner-circumferential portion of the other end side of the input gear 7 in contact with a stepped surface 27 that is formed on a portion of the middle section of the outer-circumferential surface of the input shaft 13 that is near the other end.
  • a parking-lock gear 28 is integrally formed with the inner-circumferential portion of the side surface of the other end side of the input gear 7 .
  • the output gear 8 is also a helical gear that is formed using a steel alloy such as carbon steel, and is integrally formed with the output shaft 14 in a portion near one end of the middle section of the outer-circumferential surface of the output shaft 14 . It is also possible to separately form the output gear 8 and fasten the output gear 8 around the outside of the output shaft 14 .
  • the rotary-shaft unit 6 when the rotary-shaft unit 6 is rotating in the forward direction (when the automobile is advancing in a forward direction), the torque that is inputted to the input shaft 13 from the input gear 7 is transmitted to the output shaft 14 by way of the torsion bar 15 and outputted from the output gear 8 .
  • the middle section in the axial direction of the torsion bar 15 undergoes elastic torsional deformation by an amount that corresponds to the size of the torque.
  • the rotary-shaft unit 6 is supported so as to be able to freely rotate with respect to a housing (transmission case) that is not illustrated in the figures by a pair of conical roller bearings 29 a , 29 b that are arranged such that the contact angles are opposite each other.
  • a pair of conical roller bearings 29 a , 29 b that are arranged such that the contact angles are opposite each other.
  • an inner ring 30 a of one of the conical roller bearings 29 a is fitted around a portion near one end of the input shaft 13 .
  • a spacer 31 is held between the end surface on the large-diameter side of the inner ring 30 a and the side surface of the one end side of the input gear 7 .
  • the inner ring 30 a and the input gear 7 are joined and fastened to the input shaft 13 by pressing the end surface on the small-diameter side of the inner ring 30 with a nut 32 a that is tightly screwed onto and fastened to the one end section of the outer-circumferential surface of the input shaft 13 .
  • an inner ring 30 b of the other conical roller bearing 29 b is fitted around the outside of a portion near the other end of the output shaft 14 .
  • the end surface on the large-diameter side of the inner ring 30 b is brought into contact with a stepped surface 33 that is formed on a portion near the other end of the output shaft 14 .
  • the inner ring 30 b is fastened to and supported by the output shaft 14 by pressing the end surface on the small-diameter side of the inner ring 30 b with a nut 32 b that is tightly screwed onto and fastened to the other end section of the outer-circumferential surface of the output shaft 14 .
  • the direction of inclination of the teeth of the input gear 7 and output gear 8 which are both helical gears, is regulated so that when these gears 7 , 8 are rotating in the forward direction (when the rotary-shaft unit 6 is rotating in the forward direction), the gear reaction forces in the axial direction that act on these gears 7 , 8 are in directions toward each other (press against each other).
  • the gear reaction forces in that axial direction that act on the input gear 7 and output gear 8 are able to at least partially cancel each other out.
  • the coupling shaft 9 is concentrically arranged on the inner-diameter side of the torsion bar 15 .
  • the other end section of the coupling shaft 9 protrudes from an opening on the other end side of the output shaft 14 .
  • an outward-facing flange-shaped rim section 34 is formed around a portion of the outer-circumferential surface of the one end section of the coupling shaft 9 that protrudes from the opening on the one end side of the torsion bar 15 , and by forming an involute spline connection 24 d between the outer-circumferential surface of the rim section 34 and the inner-circumferential surface of the input shaft 13 , the rim section 34 and the input shaft 13 fit together so that relative rotation is not possible.
  • it is also possible to use other construction for preventing rotation such as a key connection.
  • the coupling shaft 9 is prevented from displacement in the axial direction.
  • the first male involute spline section 62 of the involute spline connection 24 a that is provided on the one end section of the torsion bar 15 , and a male involute spline section of an involute spline connection 24 d that is provided on the rim section 34 of the coupling shaft 9 are provided so as to be connected together on the one end section of the inner-circumferential surface of the input shaft 13 , and the specifications of each are the same.
  • the involute spline connections 24 a , 24 d share the first involute spline section 63 that is provided around the inner-circumferential surface of the one end section of the input shaft 13 as the female involute spline sections of these involute spline connections 24 a , 24 d.
  • the first encoder 10 is concentrically fastened around the outside of the other end section of the coupling shaft 9 .
  • the first encoder 10 is fastened to and supported by the input shaft 13 via the coupling shaft 9 . Therefore, the first encoder 10 is able to rotate in synchronization with the input shaft 13 .
  • the second encoder 11 is concentrically fastened around the outside of the other end section of the output shaft 14 . Therefore, the second encoder 11 is able to rotate in synchronization with the output shaft 14 .
  • the first encoder 10 includes a circular ring-shaped metal core 35 that is made of a magnetic metal and that is fastened around the outside of the other end section of the coupling shaft 9 , and a cylindrical permanent magnet 37 that is fastened around the outer-circumferential surface of a cylindrical section that is located on the outer-circumferential section of the metal core 35 .
  • the second encoder 11 also includes a circular ring-shaped metal core 36 that is made of a magnetic metal and that is fastened around the outside of the other end section of the output shaft 14 , and a cylindrical permanent magnet 38 that is fastened around the outer-circumferential surface of a cylindrical section that is located on the outer-circumferential section of the metal core 36 .
  • the outer-circumferential surface of the permanent magnet 37 of the first encoder 10 functions as a first detected section 39
  • the outer-circumferential surface of the permanent magnet 38 of the second encoder 11 functions as a second detected section 40 .
  • the first and second detected sections 39 , 40 have the same diameter as each other, are concentric with each other, and are arranged so as to be closely adjacent to each other in the axial direction; for example, are separated in the axial direction by 10 mm or less, and preferably 5 mm or less.
  • the S poles and N poles of the detected sections 39 , 40 are arranged on these detected sections 39 , 40 so as to alternate at a uniform pitch in the circumferential direction.
  • the total number of magnetic poles (S poles and N poles) is the same for both of these detected sections 39 , 40 .
  • the detected sections 39 , 40 have not rotated relative to each other in the direction of rotation, and the phases in the circumferential direction of the magnetic poles of the detected sections 39 , 40 coincide with each other.
  • the poles are arranged so that poles of these detected sections 39 , 40 that are the same as each other are adjacent to each other in the axial direction.
  • the fitted section where the inner-circumferential surface of the metal core 35 of the first encoder 10 fits with the outer-circumferential surface of the other end section of the coupling shaft 9 is formed by arranging a cylindrical fitting section 26 b for maintaining concentricity, and an involute spline connection 24 e for preventing relative rotation so as to be adjacent in the axial direction. Furthermore, the metal core 35 is prevented from coming out by a retaining ring 25 d that is fastened around the outer-circumferential surface of the other end section of the coupling shaft 9 . On the other hand, the metal core 36 of the second encoder 11 is fastened around the outside of the other end section of the output shaft 14 by an interference fit.
  • the sensor unit 12 includes a holder 41 made of a synthetic resin, and a first sensor 42 a and second sensor 42 b that are embedded in the tip-end section of the holder 41 .
  • a magnetic detecting element such as a Hall element, Hall IC, MR element, GNR element or the like is embedded in the detecting sections of the first and second sensors 42 a , 42 b .
  • the sensor unit 12 is supported by a housing so that the detecting section of the first sensor 42 a closely faces the first detected section 39 , and the detecting section of the second sensor 42 b closely faces the second detected section 40 . In this example, as illustrated in FIG.
  • the first and second sensors 42 a , 42 b are arranged in opposite directions, and the detecting sections of the first and second sensors 42 a , 42 b face the same position in the circumferential direction of detected sections 39 , 40 .
  • the phase difference between the output signals of the sensors 42 a , 42 b is 180 degrees (the phase difference ratio is 0.5).
  • an oil inlet passage 43 that is open on only the one end surface of the coupling shaft 9 is provided in the center section in the radial direction of the coupling shaft 9 .
  • oil passages 44 a , 44 b are provided in portions near both ends of the coupling shaft 9 , torsion bar 15 , input shaft 15 and output shaft 14 .
  • These oil passages 44 a , 44 b connect the portions near both ends of the oil inlet passage 43 with minute ring-shaped spaces 45 a , 45 b that are located on the inner-diameter side of the small-diameter end sections of the inner rings 30 a , 30 b of the conical roller bearings 29 a , 29 b .
  • oil grooves 46 a , 46 b that extend in the radial direction are formed at one location or plural locations in the circumferential direction of the tip-end surfaces of the nuts 32 a , 32 b .
  • lubrication oil that is introduced from the opening on the one end section of the oil inlet passage 43 can pass through the oil passages 44 a , 44 b , ring-shaped spaces 45 a , 45 b and oil grooves 46 a , 46 b and be supplied to the inside of the conical roller bearings 29 a , 29 b.
  • part of the lubrication oil that is fed into the oil passages 44 a , 44 b passes from the middle sections of these oil passages 44 a , 44 b through spaces that exist in the involute spline connections 24 a , 24 b , and then fed to the outer-circumferential surface of the middle section of the torsion bar 15 and to the inside of a cylindrical space 47 that exists between the inner-circumferential surfaces of the middle sections of input shaft 13 and output shaft 14 .
  • the lubrication oil that is fed inside the cylindrical space 47 passes through the space that exists between the tip-end surface 48 of the input-side combination cylindrical section 16 and a stepped surface 49 that exists at the base-end section of the inner-circumferential surface of the output-side combination cylindrical section 17 , and is supplied to the area where the radial needle bearing 18 is installed and the area where the thrust washer 21 is held so as to lubricate these portions.
  • the lubrication oil that reaches the area where the thrust washer 21 is held provides lubrication to this area where the thrust washer 21 is held, and also smoothly passes through this area where the thrust washer 21 is held by passing through the plural slits 22 that are provided in the thrust waster 21 .
  • a thrust washer 21 a such as illustrated in FIG. 11B in which the reinforcing cylindrical section on the outer circumference is omitted, or a simple circular disk-shaped thrust washer 21 such as illustrated in FIG. 11C in which the reinforcing cylindrical section on the outer circumference and the plural slits are omitted.
  • a thrust washer 21 , 21 a having slits 22 such as illustrated in FIG. 11A and FIG.
  • 11B is preferred, and furthermore, from the aspect of maintaining the strength of the outer-circumferential section of the thrust washer (particularly the peripheral edge of the slits 22 ), using a thrust washer 21 having a reinforcing cylindrical section 23 as illustrated in FIG. 11A is preferred.
  • lubrication oil is also fed from the center section of the oil passages 44 a , 44 b into the inside of a minute space that exists between the inner-circumferential surface of the torsion bar 15 and the outer-circumferential surface of the coupling shaft 9 (cylindrical space having a thickness in the radial direction of about 0.2 mm).
  • concave grooves 66 a , 66 b are provided around the entire circumference of the portion of the outer-circumferential surface of the coupling shaft 9 that is aligned in the axial direction with the oil passages 44 a , 44 b .
  • the lubrication oil that is filled into a minute space that exists between the inner-circumferential surface of the torsion bar 15 and the outer-circumferential surface of the coupling shaft 9 functions as a film damper that dampens small vibration of the coupling shaft 9 .
  • the output signals from the first and second sensors 42 a , 42 b of the sensor unit 12 change periodically as the first and second encoders 10 , 11 rotate together with the input shaft 13 and output shaft 14 of the rotary-shaft unit 6 .
  • the frequency and period of this change are values that correspond to the rotational speed of the rotary-shaft unit 6 . Therefore, by investigating beforehand the relationship between the frequency or period of the output signal from the first and second sensors 42 a , 42 b and the rotational speed, it is possible to find the rotational speed based on the frequency or period of these output signals.
  • the input gear 7 (input shaft 13 , first encoder 10 ) and the output gear 8 (output shaft 14 , second encoder 11 ) undergo relative displacement in the direction of rotation as the middle section in the axial direction of the torsion bar 15 undergoes elastic torsional deformation.
  • this phase difference ratio is a value that corresponds to the torque that is transmitted by the rotation transmission device. Therefore, by investigating beforehand the relationship between the phase difference ratio of the output signals from the first and second sensors 42 a , 42 b and the torque of the rotation transmission device, it is possible to find the torque that is transmitted by the rotation transmission device based on this phase difference ratio.
  • the shaft is divided into two, an input shaft 13 and an output shaft 14 ; the input gear 7 is fastened around the middle section in the axial direction of the outer-circumferential surface of the input shaft 13 , and the output gear 8 is fastened around the middle section in the axial direction of the outer-circumferential surface of the output shaft 14 ; and both the input shaft 13 and output shaft 14 have hollow construction.
  • a torsion bar 15 that is connected to the input shaft 13 and the output shaft 14 so that both end sections are not capable of relative rotation is arranged on the inner-diameter side of the input shaft 13 and output shaft 14 , and furthermore, a coupling shaft 9 that supports a first encoder 10 on the other end section is arranged on the inner-diameter side of the torsion bar 15 .
  • the rotation transmission device with a torque measurement device has a triple structure that includes an input shaft 13 and output shaft 14 , a torsion bar 15 and a coupling shaft 9 .
  • the dimension L in the axial direction of the middle section in the axial direction of the torsion bar 15 is sufficiently longer than the space W between the input gear 7 and the output gear 8 (L>W). Therefore, it is possible to sufficiently maintain the amount of elastic torsional deformation of the middle section in the axial direction of the torsion bar 15 that occurs when transmitting torque.
  • the relationship between the torque that is transmitted by the rotation transmission device and the amount of relative displacement in the direction of rotation of the first and second encoders 10 , 11 (gain) can be easily designed to obtain a desired value.
  • the sensor unit 12 is a single unit, so it is possible to run only one harness (not illustrated in the figures) from the sensor unit 12 , so it is possible to easily install the required harness.
  • only one area inside the housing is needed for supporting and fastening the sensor unit 12 , so processing of the housing is simplified.
  • the first and second encoders 10 , 11 are arranged so as to be concentrated on the other end side of the output shaft 14 , so the sensor unit 12 can be supported by a portion of the housing that is near the end section with high rigidity. Therefore, even when the housing is deformed due to gear reaction forces, contact between the sensor unit 12 and the first and second encoders 10 , 11 is prevented. Consequently, it is possible to reduce the space between the first detected section 39 of the first encoder 10 and the detected section 40 of the second encoder 11 , and to improve the precision of torque measurement.
  • the rotary-shaft unit 6 is constructed by combining an input-side combination cylindrical section 16 of the input shaft 13 and an output-side combination cylindrical section 17 of the output shaft 14 together by way of a radial needle bearing 18 and a thrust washer 21 , so gear reaction forces are mainly applied to the connection between the input-side combination cylindrical section 16 and the output-side combination cylindrical section 17 , and supported by the radial needle bearing 18 and thrust washer 21 . As a result, the gear reaction forces are prevented from becoming concentrated in the torsion bar 15 .
  • the detected sections of the first and second encoders are a pair of circular disk-shaped detected sections having radial dimensions that differ from each other, and these detected sections are arranged so as to be concentric with each other when facing in the same axial direction (overlap in the radial direction), and the detecting sections of the pair of sensors of the sensor unit that are arranged so as to be separated in the radial direction of the rotary-shaft unit are made to face these detected sections in the axial direction.
  • FIG. 13 and FIG. 14 illustrate a second example of an embodiment of the present invention.
  • the phases in the circumferential direction of the magnetic poles of the detected sections 39 , 40 of the first and second encoders 10 , 11 are shifted 180 degrees from each other.
  • poles of these detected sections 39 , 40 that are different from each other are arranged so as to be adjacent to each other in the axial direction.
  • the pair of sensors 42 a , 42 b of the sensor unit 12 are arranged so that each faces in the same direction, the detecting sections of these sensors 42 a , 42 b face the same position in the circumferential direction of the detected sections 39 , 40 .
  • the transmitted torque is in a rotated state of zero, the phase difference between the output signals of the sensors 42 a , 42 b is 180 degrees (the phase difference ratio is 0.5).
  • FIG. 15A , FIG. 15B and FIG. 16 illustrate a third example of an embodiment of the present invention.
  • two through holes 67 a , 67 b which are both regulating parts, are provided in the metal core 35 b of the first encoder 10 f and are separated in the circumferential direction.
  • one concave hole 68 which is a regulating part, is provided in the metal core 36 b of the second encoder 11 f .
  • the center axes of these encoders 10 f , 11 f are made to coincide with each other, and a pin 69 is passed through or inserted into one of the through holes 67 a , 67 b and into the concave hole 68 as a regulating member so that there is no looseness.
  • the encoders 10 f , 11 f can be positioned in the circumferential direction.
  • the pin 69 passes through one of the through holes 67 a , 67 b and is inserted into the concave hole 68 positions the encoders 10 f , 11 f in the circumferential direction, and these encoders 10 f , 11 f are then installed in the location of use.
  • the encoders 10 f , 11 f in the location of use with a positional relationship as illustrated in FIG. 9 when installing the magnetized encoders 10 f , 11 f in the location of use with a positional relationship as illustrated in FIG.
  • the through hole of the encoder 10 f though which the pin 69 is passed is changed from the one though hole of the through holes 67 a , 67 b to the other through hole, and then with the relative positional relation in the circumferential direction of the encoders 10 f , 11 f shifted an amount of the pitch of one magnetization from the positional relationship at the time of magnetization, the encoders 10 f , 11 f are installed and fastened in the location of use, after which the pin 69 is removed from the through hole 67 a or 67 b and the concave hole 68 .
  • FIG. 17A and FIG. 17B illustrate a fourth example of an embodiment of the present invention.
  • a pair of concave sections 70 a , 70 b which are regulating sections, are provided in one end surface in the axial direction (the end surface on the second encoder 11 g side) of the permanent magnet 37 b of the first encoder 10 g so as to be separated in the circumferential direction.
  • one convex section 71 which is a regulating section, is provided on one end surface in the axial direction (end surface on the first encoder 10 g side) of the permanent magnet 38 b of the second encoder 11 g .
  • the pitch of the concave sections 70 a , 70 b is equal to the pitch of one magnetization of the encoders 10 g , 11 g.
  • the ends in the axial direction of the permanent magnets 37 b , 38 b of the encoders 10 g , 11 g are placed against each other, and by fitting one of the concave sections 70 a , 70 b with the convex section 71 , the encoders 10 g , 11 g are positioned in the circumferential direction.
  • the detected sections 39 , 40 of the encoders 10 g , 11 g are simultaneously magnetized so that the S poles and N poles are in the same phase in the circumferential direction, and so as to alternate at a uniform pitch in the circumferential direction.
  • one of the concave sections 70 a , 70 b is fitted with the convex section 71 , which positions the encoders 10 g , 11 g in the circumferential direction, and then the encoders 10 g , 11 g are installed in the location of use.
  • the encoders 10 g , 11 g in the location of use with a positional relationship such as illustrated in FIG. 9 When installing the encoders 10 g , 11 g in the location of use with a positional relationship such as illustrated in FIG.
  • one of the end surfaces in the axial direction of the permanent magnets 37 b , 38 b of the encoders 10 g , 11 g are placed together, and by fitting the other concave section of the concave sections 70 a , 70 b with the convex section 71 as illustrated in FIG. 17B , the encoders 10 g , 11 g are positioned in the circumferential direction, and then the encoders 10 g , 11 g are installed in the location of use.
  • the work of installing the encoders 10 g , 11 g in the location of use can be performed easily and accurately.
  • the other construction and functions are the same as in the first and second examples of embodiments.
  • FIG. 18 illustrates a fifth example of an embodiment of the present invention.
  • a pair of markings 72 a , 72 b , 73 a , 73 b such as concave sections or convex sections, which are regulating sections, are provided on the other end surface in the axial direction (end surface on the side opposite from the second encoder 11 h ) of the permanent magnet of the first encoder 10 h , and on the one end surface in the axial direction (end surface on the first encoder 10 h side) so as to be separated in the circumferential direction.
  • the positions in the circumferential direction of the marking 72 a , 72 b that are provided on the first encoder 10 h coincide with the positions in the circumferential direction of two magnetization boundaries (boundaries between S pole and N pole) that are adjacent in the circumferential direction of the detected section 39 of the first encoder 10 h .
  • the positions in the circumferential direction of the marking 73 a , 73 b that are provided on the second encoder 11 h coincide with the positions in the circumferential direction of two magnetization boundaries that are adjacent in the circumferential direction of the detected section 40 of the second encoder 11 h.
  • the work of installing the encoders 10 h , 11 h in the location of use is performed in the assembled state, making sure that the positions in the circumferential direction of both the markings 72 a , 72 b and the markings 73 a , 73 b coincide, or so that the positions in the circumferential direction of the marking 72 a and the marking 73 b (or the marking 72 b and the marking 73 a ) coincide.
  • the work of installing the encoders 10 h , 11 h in the location of use can be performed easily and accurately.
  • the other construction and functions are the same as those of the first and second examples of embodiments.
  • FIG. 19 to FIG. 21 illustrate a sixth example of an embodiment of the present invention.
  • a first plating layer 74 is provided on the surface layer of a first male involute spline section 62 a that is provided on the outer-circumferential surface of the one end of the torsion bar 15 b
  • a second plating layer 75 is provided on the surface layer of a second male involute spline section 64 a that is provided on the outer-circumferential surface of the other end section of the torsion bar 15 b .
  • the first and second plating layers 74 , 75 are formed using a metal such as copper or nickel that are softer than the steel alloy such as carbon steel of the torsion bar 15 , input shaft 13 and output shaft 14 (see FIG. 6 ).
  • the first male involute spline section 62 a (second male involute spline section 64 a ) is press fitted into a first female involute spline section 63 a that is provided on the inner-circumferential surface of the input shaft 13 (second female involute spline section 65 a that is provided on the inner-circumferential surface of the output shaft 14 ) so that the interference is less than the thickness dimension in the free state of first plating layer 74 (second plating layer 75 ).
  • an involute spline connection 24 a 1 (involute spline connection 24 b 1 ) can be formed by fitting the first male involute spline section 62 a (second male involute spline section 64 a ) with the first female involute spline section 63 a (second female involute spline section 65 a ) so that there is no looseness in the circumferential direction.
  • a space remains between the tip of the tooth and bottom of the tooth of the first male involute spline section 62 a (second male involute spline section 64 a ) and the first female involute spline section 63 a (second female involute spline section 65 a ), and these spaces function as passages for lubrication oil.
  • the thickness dimension T in the free state of the first plating layer 74 (second plating layer 75 ) is greater than the space t between the teeth surfaces in the state before forming the first plating layer 74 (second plating layer 75 ) on the first male involute spline section 62 a (second male involute spline section 64 a ) illustrated in FIG. 20 (T>t).
  • This space t can also be found by measurement using a conventionally known measurement pin or by using some other method.
  • the involute spline connections 24 a 1 , 24 b 1 are connections in which there is no looseness in the circumferential direction. Therefore, when the direction of rotation of the input shaft 3 , which is the rotary shaft on the side where torque is inputted, rotates in the reverse direction, it is possible to prevent relative rotation in the space in the circumferential direction in the involute spline connections 24 a 1 , 24 b 1 that is the cause of looseness. In other words, when the direction of rotation of the input shaft 13 is in the reverse direction and relative rotation occurs in the involute spline connections 24 a 1 , 24 b 1 in the spaces in the circumferential direction, relative rotation also occurs between the first and second encoders 10 , 11 .
  • the occurrence of relative rotation in the spaces in the involute spline connections 24 a 1 , 24 b 1 that are the cause of looseness is prevented.
  • the occurrence of relative rotation between the first and second encoders 10 , 11 is also prevented.
  • linearity of the characteristic curve that expresses the relationship between the sensor output and the torque is maintained overall, and so it is possible to accurately measure minute torque.
  • deformation of the copper or nickel of the first and second plating layers 74 , 75 occurs at a smaller force than the deformation of the steel of the main portion of the involute spline sections 62 a , 64 a , 63 a , 65 a , so it is possible to keep the force required for performing a press fit low.
  • metal such as copper, nickel or the like that has suitable crushing characteristics and rigidity is used as the metal of the first and second plating layers 74 , 75 , so even when used over a long period of time, it is possible to make it difficult for spaces to occur between the plating layers 74 , 75 and the teeth surfaces of the female involute spline sections 63 a , 65 a .
  • involute spline connections 24 a 1 , 24 b 1 it is also possible to apply construction for eliminating looseness in the circumferential direction by using a suitable and relatively soft plating layer in the involute spline connections 24 c to 24 e (se FIG. 6 ). Moreover, in applications in which it is not necessary to measure minute torque, it is also possible to use connections having a little looseness in the circumferential direction for any of the involute spline connections 24 a to 24 e (see FIG. 6 ) without applying the construction of this example, and that construction is also within the scope of the present invention.
  • the other construction and functions are the same as those of the first through fifth examples of embodiments.
  • FIG. 22 and FIG. 23 illustrate a seventh example of an embodiment of the present invention.
  • a rim section 34 a that is provided on one end section of the coupling shaft 9 b is fastened around the inside of the one end section of the input shaft 13 a with an interference fit.
  • the outer-circumferential surface of the rim section 34 a is taken to be a cylindrical surface 76 , and that cylindrical surface 76 is fitted around a cylindrical surface 77 that is provided on the inner-circumferential surface of the other end section of the input shaft 13 a with an interference fit.
  • FIG. 24 illustrates an eighth example of an embodiment of the present invention.
  • the inner ring 30 c of one of the conical roller bearings 29 c is made so as to be integrated with the input shaft 13 b
  • the inner ring 30 d of the other conical roller bearing 29 d is made so as to be integrated with the output shaft 14 a .
  • the nuts 32 a , 32 b for preventing the inner rings 30 c , 30 d from coming out are eliminated.
  • the dimension of the inner diameter of the input gear 7 that is fastened around the outside of the input shaft 13 b is made to be larger than the dimension of the outer diameter of the inner ring 30 c .
  • FIG. 25 to FIG. 29 illustrate a ninth example of an embodiment of the present invention.
  • the first encoder 10 a that is fastened around the outside of the other end section of the coupling shaft 9 is formed into a complete ring shape having an L-shaped cross section using a magnetic metal, and the outer circumference of the first encoder 10 a functions as a flat gear shaped first detected section 39 a .
  • the first detected section 39 a is constructed so that plural convex sections 50 that protrude to the outer-diameter side from the portion near the outer circumference of the first encoder 10 a are arranged at a uniform pitch in the circumferential direction.
  • the convex sections correspond to solid sections, and portions between convex sections 50 that are adjacent in the circumferential direction correspond to sections where material has been removed.
  • the second encoder 11 a that is fastened around the outside of the other end section of the output shaft 14 is formed into a complete cylindrical shape using magnetic metal plate, and the tip half section that protrudes in the axial direction from the other end surface of the output shaft 14 functions as a comb shaped second detected section 40 a .
  • the second detected section 40 a is constructed so that plural tongue pieces 51 that extend in the axial direction toward the tip end side from the middle section in the axial direction of the second encoder 11 a are arranged at a uniform pitch in the circumferential direction.
  • the total number of these tongue pieces 51 is the same as the total number of convex section 50 .
  • the width in the circumferential direction that is expressed by the center angle of these tongue pieces 51 is equal to the width in the circumferential direction that is expressed by the center angle of the convex sections 50 .
  • the tongue pieces 51 correspond to solid sections, and the spaces between tongue pieces that are adjacent in the circumferential direction correspond to sections with material removed.
  • the first and second detected sections 39 a , 40 a are arranged so as to be concentric with each other, or in other words, so as to overlap in the radial direction.
  • the phases in the circumferential direction of the convex sections 50 and the tongue pieces 51 coincide with each other.
  • the sensor unit 12 a is formed into a complete circular ring shape, and concentrically arranged around the outer-diameter side of the first and second detected sections 39 a , 40 a .
  • the sensor unit 12 a includes a stator 52 made of a magnetic material, and plural coils 54 that are formed using one conducting wire 53 .
  • the stator 52 includes plural core sections 55 that are long in the radial direction, and a circular ring-shaped rim section 56 that connects the base-end sections, on the outer-diameter side of the core sections 55 .
  • the total number of core sections 55 is the same as the total number of convex sections 50 and tongue pieces 51 .
  • the width in the circumferential direction that is expressed by the center angle of the tip-end surfaces on the inner-diameter side of the core sections 55 is equal to the width in the circumferential direction of the tongue pieces 51 (width in the circumferential direction of the convex sections 50 ).
  • the end surfaces on the inner-diameter side of such core sections 55 are made to closely face the outer-circumferential surface of the second detected section 40 a .
  • the coils 54 together with being wound around the core sections 55 , are such that the winding directions of coils that are adjacent to each other in the circumferential direction are opposite each other. Therefore, in this example, the total number of coils 54 is an even number ( 10 coils 54 in the example in the figures), and the total number of convex sections 50 and tongue pieces is also an even number.
  • the coils 54 have both a driving function for generating a magnetic field, and a detection function for detecting change in the magnetic field.
  • a driving voltage to the coils 54 (conducting wire 53 )
  • a driving current flows through these coils 54 , and between coils 54 that are adjacent in the circumferential direction, a loop-shaped magnetic fluxes such as illustrated by the bold arrow lines in FIG. 27 flow inside the stator 52 and first and second encoders 10 a , 11 a .
  • the density of the loop-shaped magnetic flux periodically changes, and as this occurs, a periodic induced current flows in the coils 54 .
  • the output of the conducting wire 53 which is the output of the sensor unit 12 a , and more specifically, the voltage and current (when the driving voltage is an alternating-current voltage, the peak values or effective values of these) periodically change as illustrated in FIG. 29C .
  • the frequency (and period) of this output is a value that corresponds to the rotational speed of the rotary-shaft unit 6 . Therefore, by investigating the relationship between the frequency (or period) of this output and the rotational speed, it is possible to find the rotational speed based on this frequency (or period).
  • the encoders 10 a , 11 a displace relative to each other in the direction of rotation due to elastic torsional deformation of the torsion bar 15 , and as a result, the phase in the circumferential direction of the convex sections 50 and the tongue pieces 51 of the detected sections 39 a , 40 a shift in the order as illustrated from FIG. 29A to FIG. 29B .
  • the widths in the circumferential direction of the magnetic paths inside the encoders 10 a , 11 a which are the portions where the convex sections 50 overlap the tongue pieces in the radial direction, decreases.
  • the size of the output of the conducting wire 53 decreases in the order as illustrated from the dashed line to the solid line in FIG. 29C .
  • the shift in phase (the amount of decrease in the width in the circumferential direction of the magnetic path) becomes larger the larger the torque becomes. Therefore, the size of the output decreases more the larger the torque becomes.
  • the size of the output not only changes due to the torque, but also changes due to the rotational speed.
  • the size of the induced current that flows in the coils 54 (induced electromotive force in the coils 54 ) is proportional to the rate of change in the magnetic flux that passes through the coils 54 . The rate of change of this magnetic flux becomes large in proportion to the rotational speed.
  • the size (amplitude) of the output becomes larger in proportion to the rotational speed.
  • the effect that the torque has on the size of the output, and the effect that the rotational speed has on the size of the output are both investigated beforehand.
  • the rotational speed is found based on the frequency (or period) of the output, and correction is performed to return the size of the output that has changed due to the effect of the rotational speed to the original size. By doing so, it is possible to accurately find the torque based on the size of the output after this correction.
  • the driving voltage that is applied to the conducting wire 53 can also be a direct-current voltage, however, in order to increase the resistance to noise, an alternating-current voltage is preferred.
  • the sensor unit 12 a is combined with the stator 52 and coils 54 and does not include precision electronic parts such as a magnetism-detecting device, so has excellent heat resistance and vibration resistance. Moreover, in this example, there is only one output that is used for measuring the rotational speed and the torque, so there is no need for complex signal processing when performing measurement. Consequently, it is possible to use an inexpensive computing device that does not have very high processing capability as the computing device used in performing this signal processing.
  • the detected sections of the first and second encoders are a pair of circular disk-shaped detected sections having the same dimensions in the radial direction, and these detected sections are arranged so as to overlap in the axial direction.
  • the core sections of the sensor unit are formed so as to be long in the axial direction. The tip-end surfaces of these core sections can face the detected sections from one side in the axial direction, which is the direction in which these detected sections overlap.
  • FIG. 30 to FIG. 35 illustrate a tenth example of an embodiment of the present invention.
  • the first encoder 10 b that is fastened around the outside of the other end section of the coupling shaft 9 , and the second encoder 11 b that is fastened around the outside of the other end section of the output shaft 14 are formed into a complete circular ring shape using a magnet metal, and each encoder 10 b , 11 b includes a comb-shaped cylindrical detection section 39 b ( 40 b ).
  • the first detected section 39 b of the first encoder 10 b , and the second detected section 40 b of the second encoder 11 b are formed so that plural tongue pieces 51 a ( 51 b ) that are long in the axial direction are arranged at a uniform pitch in the circumferential direction, and so that the base-end sections of these tongue pieces 51 a ( 51 b ) are connected together.
  • the shape and dimensions of the detected sections 39 b , 40 b are the same as each other, however, the direction that each faces in the axial direction is opposite of each other.
  • the tongue pieces 51 a of the first detected section 39 b and the tongue pieces 51 b of the second detected section 40 b are arranged so that when located in a space in the circumferential direction, the tongue pieces alternate one tongue piece at a time in the circumferential direction.
  • the widths in the circumferential direction of the portions between tongue pieces 51 a , 51 b that are adjacent in the circumferential direction are all the same.
  • the widths in the circumferential direction of the portions between tongue pieces 51 a , 51 b that are adjacent in the circumferential direction are the same as the widths in the circumferential direction of the tongue pieces 51 a , 51 b . This is so that the duty ratios when torque is not being transmitted is 0.5.
  • the tongue pieces 51 a ( 51 b ) correspond to solid sections, and the portions between tongue pieces 51 a ( 51 b ) that are adjacent in the circumferential direction correspond to sections where material has been removed.
  • the sensor unit 12 b includes a holder 41 a that is made of a synthetic resin, and one sensor 42 c that is embedded in the tip-end section of the holder 41 a ; and the detecting section of the sensor 42 c is made to closely face the outer-circumferential surface of the detected sections 39 b , 40 b (portions where the tongue pieces 51 a , 51 b are arranged in an alternating manner in the circumferential direction).
  • the sensor 42 c includes a permanent magnet that is magnetized in the direction that the outer-circumferential surfaces of the detected sections 39 b , 40 b face the detecting section of the sensor 42 c , and a magnetic detecting element such as Hall element, Hall IC, MR element, GMR element and the like that is arranged on the end surface of both end surfaces in the magnetized direction of the permanent magnet that faces the outer-circumferential surfaces of the detected sections 39 b , 40 b.
  • a magnetic detecting element such as Hall element, Hall IC, MR element, GMR element and the like that is arranged on the end surface of both end surfaces in the magnetized direction of the permanent magnet that faces the outer-circumferential surfaces of the detected sections 39 b , 40 b.
  • the output signal from the sensor 42 c of the sensor unit 12 b periodically changes as the first and second encoders 10 b , 11 b rotate together with the rotary-shaft unit 6 .
  • the widths in the circumferential direction of the portions between tongue pieces 51 a , 51 b that are adjacent in the circumferential direction change. More specifically, the widths in the circumferential direction of every other one of the portions between the tongue pieces 51 a , 51 b become larger, and the widths in the circumferential direction of the remaining portions become smaller.
  • the amount that the widths in the circumferential direction of the portions between tongue pieces 51 a , 51 b that become larger (smaller) is a value that corresponds to the torque that is transmitted by the rotation transmission device, so the duty ratio s is also a value that corresponds to the torque. Therefore, by investigating in advance the relationship between the duty ratio s and the torque such as illustrated in FIG. 35 , the torque can be found based on this duty ratio ⁇ .
  • the 2-pulse period A is a value that corresponds to the rotational speed of the rotary-shaft unit 6 . Therefore, by investigating the relationship between the 2-pulse period A and the rotational speed, it is possible to find the rotational speed based on the 2-pulse period A.
  • the detected sections of the first and second encoders 10 b , 11 b are made to overlap in the circumferential direction, so it is possible to shorten the dimension in the axial direction of the portions where these detected sections 39 b , 40 b are located, and thus construction that conserves space by this amount is possible. Moreover, it is sufficient to install only one magnetism-detecting element in the sensor unit 12 b , so the cost of the sensor unit 12 b can be suppressed.
  • the other construction and functions are the same as those of the first through eighth examples of embodiments.
  • FIG. 36 to FIG. 38 illustrate an eleventh example of an embodiment of the present invention.
  • the first detected section 39 c of the first encoder 10 c that is fastened around the outside of the other end section of the coupling shaft 9 and the second detected section 40 c of the second encoder 11 c that is fastened around the outside of the other end section of the output shaft 14 are both formed into a comb-like circular ring shape.
  • the tongue pieces 51 c , 51 d of the detected sections 39 c , 40 c are arranged in an alternating manner in the circumferential direction when located in a space in the circumferential direction.
  • the detecting section of one sensor 42 c of the sensor unit 12 b is made to face in the axial direction the side surface in the axial direction of the portion where the tongue pieces 51 c , 51 d are arranged.
  • FIG. 39 to FIG. 42 illustrate a twelfth example of an embodiment of the present invention.
  • the first encoder 10 that is fastened to and supported by the other end section of the coupling shaft 9 includes a ring-shaped metal core 35 a that is made of a magnetic material and that is fastened around the outside of the other end section of the coupling shaft 9 , and a cylindrical-shaped permanent magnet 37 a that is fastened around the outer-circumferential surface of a cylindrical section that exists on the outer circumference of the metal core 35 a .
  • the second encoder 11 d that is fastened to and supported by the other end section of the output shaft 14 includes a ring-shaped metal core 36 a that is made of magnetic metal sheet and that is fastened around the outside of the other end section of the output shaft 14 , and a cylindrical shaped permanent magnet 38 a that is fastened around the inner-circumferential surface of a cylindrical section that exists on the outer circumference of the metal core 36 a .
  • the second detected section 40 d which is the inner-circumferential surface of the permanent magnet 38 a , is concentrically arranged on the outer-diameter side of the first detected section 39 d so that there is a specified space in the radial direction.
  • the first and second detected sections 39 , 40 d face each other through a specified space in the radial direction.
  • the total number of magnetic poles (S poles, N poles) that are arranged on the second detected section 40 d and the total number of magnetic poles that are arranged on the first detected section 39 d are the same as each other.
  • the detected sections 39 d , 40 d are arranged so that the centers of different poles face each other in the radial direction.
  • the sensor unit 12 c that is supported by the housing includes a holder 41 b made of a synthetic resin, and one sensor 42 d that is embedded in the tip-end section of the holder 41 b ; and the sensor 42 d is arranged so as to be in the center position in the radial direction between the detected sections 39 d , 40 d .
  • a magnetism-detecting element such as a Hall element, Hall IC, MR element, GMR element or the like is assembled in the detecting section of the sensor 42 d , and the sensing direction of that magnetism-detecting element is such that the center section of the element coincides with the radial direction of the first and second detected sections 39 d , 40 d .
  • the sensing direction of this magnetism-detecting element is in the up-down direction in FIG. 41A and FIG. 41B , and the magnetic flux density in this up-down direction is proportional to the size of the output (voltage, current) of the magnetism-detecting element, which is the output signal of the sensor unit 12 c.
  • the positional relationship of different poles of the detected sections 39 d , 40 d shifts in the circumferential direction, so the direction of the magnetic flux that passes through the magnetism-detecting element becomes inclined overall with respect to the direction of sensitivity of the element.
  • the magnetic flux density decreases by the amount of this inclination, and thus the output of the magnetism-detecting element also decreases by that amount.
  • the size of this inclination becomes larger the larger the torque (shift in the circumferential direction) is. Therefore, the output of the magnetism-detecting element becomes a maximum when torque is zero, and becomes small as the torque becomes larger.
  • the output of the magnetism-detecting element has a sinusoidal shape as illustrated in FIG. 42 .
  • the size (amplitude) of this output becomes larger as the torque becomes larger. Therefore, by investigating the relationship between the size of the output and the torque beforehand, the torque can be found based on the size of the output.
  • the frequency (and period) of the output is a value that corresponds to the rotational speed of the rotary-shaft unit 6 . Therefore, by investigating the relationship between the frequency (or period) and the rotational speed beforehand, it is possible to find the rotational speed based on the frequency (or period).
  • the location of the magnetic poles of the detected sections 39 d , 40 d are shifted at an electrical angle of 90 degrees with respect to the circumferential direction, or in other words, it is possible to make the center of the magnetic poles of one of the detected sections face in the radial direction the boundary between magnetic poles of the other detected section.
  • the output of the magnetism-detecting element becomes a minimum when torque is not being transmitted, and becomes larger as the torque being transmitted becomes larger.
  • a coil instead of using a magnetism-detecting element as the detecting section of the sensor 42 d of the sensor unit 12 c .
  • the center axis of the coil is made to coincide with the radial direction of the first and second detected sections 39 d , 40 d .
  • the direction and size of the magnetic flux that passes through the coil changes periodically, so the output (voltage, current) of the coil, which is the output signal of the sensor unit 12 c , changes periodically.
  • the frequency (and period) of this output is a value that corresponds with the rotational speed, so it is possible to find the rotational speed based on the frequency (or period).
  • the density of the magnetic flux that passes perpendicular to the coil changes according to the size of the torque (amount of shift in the position in the circumferential direction of the different poles of the detected sections 39 d , 40 d ). Therefore, the size of the output of the coil changes according to the size of the torque.
  • the size of the output of the coil also changes according to the rotational speed.
  • the detected sections of the first and second encoders are a pair of circular disk-shaped detected sections that have the same radial dimensions, and are arranged so that these detected sections face each other in the axial direction.
  • the detecting section of the one sensor of the sensor unit is arranged between these detected sections.
  • FIG. 43 illustrates a thirteenth example of an embodiment of the present invention.
  • the first and second encoders 10 , 11 and the sensor unit 12 are arranged so as to be concentrated around one end section of the input shaft 13 .
  • the outer-circumferential surface of the other end section (left-end section in FIG. 43 of the coupling shaft 9 a that is arranged on the inner-diameter side of the torsion bar 15 is connected to the inner-circumferential surface of the other end section of the output shaft 14 by an involute spline connection or key connection so that relative rotation is not possible.
  • FIG. 43 is a simplified drawing, and part of the drawing and reference numbers are omitted. The other construction and functions are the same as those of the first example of an embodiment.
  • FIG. 44 to FIG. 47 illustrate fourteenth to seventeenth examples of embodiments of the present invention.
  • the arrangement of the thirteenth example of an embodiment is applied to the construction of the ninth to twelfth examples of embodiments, and the first and second encoders 10 a to 10 d , 11 a to 11 d and the sensor units 12 a to 12 d are arranged so as to be concentrated around one end of the input shaft 13 .
  • FIG. 44 to FIG. 47 are simplified drawings, and part of the drawing and reference numbers are omitted. The other construction and functions are the same as those of the ninth to twelfth examples and thirteenth example of embodiments.
  • FIG. 48 and FIG. 49 illustrate eighteenth and nineteenth examples of embodiments of the present invention.
  • the radial bearing is a cylindrical sleeve bearing 57 , which is a radial sliding bearing
  • the thrust bearing is a thrust needle bearing 58 .
  • the thrust needle bearing 58 is fastened around the outside of the base-end section of the input-side combination cylindrical section 16 so that there is no large looseness in the radial direction, and as a result, the position of thrust needle bearing 58 is set in the radial direction.
  • the radial bearing and thrust bearing that are installed in the combination section of the input shaft 13 and output shaft 14 are a cylindrical shaped sleeve bearing 57 and a circular disk-shaped thrust washer 21 c .
  • the thrust washer 21 c By fastening the thrust washer 21 c around the outside of the base-end section of the input-side combination cylindrical section 16 so that there is no large looseness in the radial direction, the position of the thrust washer 21 c is set in the radial direction.
  • the thrust washer 21 c is such that by fitting a pin 59 that is embedded in the stepped surface 19 in an engagement hole 60 that is formed in part of the thrust washer 21 c itself, the position in the circumferential direction of the thrust washer 21 c is set.
  • an oil passage 61 is formed in the base-end section of the input-side combination cylindrical section 16 .
  • Lubrication oil can be supplied though this oil passage 61 from a cylindrical space 47 to the space where the radial bearing is installed and the space where the thrust bearing is installed, which improves the lubrication of these bearings.
  • the other construction and functions are the same as those of the first through eighteenth examples of embodiments.
  • FIG. 50 illustrates a twentieth example of an embodiment of the present invention.
  • a spring section 115 which is the portion in the middle section in the axial direction of the torsion bar 15 (see FIG. 5 and FIG. 6 ) that undergoes torsional deformation when torque is transmitted, does not break (fracture) due to fatigue even when torque is repeatedly transmitted.
  • the construction of the torsion bar 15 is devised so that maintaining the durability necessary for preventing the spring section 115 a of the torsion bar 15 from breaking due to repeated transmission of torque, and maintaining the amount of elastic torsional deformation (twist angle) per unit torque that is required in order to improve the precision and resolution of torque measurement are both achieved to a high degree.
  • the spring section 115 a of the torsion bar 15 a includes a cylindrical tube section 78 in the middle section in the axial direction except for the portions on both end edges in the axial direction, that has thinner wall thickness than the portions on both end edges in the axial direction, and is a single cylindrical surface of which the inner-circumferential surface and outer-circumferential surface are concentric with each other.
  • the inner-circumferential surface of the center hole of the torsion bar 15 a including the middle section in the axial direction, which is the inner-circumferential surface of the spring section 115 a , is a single cylindrical surface along the entire length.
  • the outer-circumferential surface of the cylindrical tube section 78 is a single cylindrical surface that is concentric with the inner-circumferential surface of the center hole of the cylindrical tube section 78 . Therefore, the wall thickness in the radial direction of the cylindrical tube section 78 is uniform overall.
  • the outer-circumferential surfaces of the portions on both end edges in the axial direction of the spring section 115 a are inclined in a direction so that the dimension of the diameter becomes larger going toward both ends in the axial direction of the spring section 115 a , and form a pair of inclined surface sections 79 .
  • the outer-circumferential surface of the cylindrical tube section 78 and a pair of male involute spline sections 62 , 64 on both end sections in the axial direction of the outer-circumferential surface of the torsion bar 15 a are provided so as to be continuous by way of the pair of inclined surface sections 62 , 64 . Therefore, the portions on both end edges in the axial direction of the spring section 115 a where the inclined surface sections 79 are provided are such that the wall thickness in the radial direction becomes larger than that of the cylindrical tube section 78 . In other words, the wall thickness in the radial direction of the spring section 115 a is a minimum in the cylindrical tube section 78 .
  • the dimension s in the axial direction of this cylindrical tube section 78 is greater than the width W in the axial direction of the input gear 7 and the outer gear 8 (see FIG. 6 ) (s>W).
  • the wall thickness in the radial direction of the spring section 115 a is a minimum in the cylindrical tube section 78 , so the torsional rigidity per unit length of the spring section 115 a is also a minimum in the cylindrical tube section 78 . Therefore, the amount of elastic torsional deformation per unit length that occurs in the spring section 115 a when torque is being transmitted becomes a maximum in the cylindrical tube section 78 .
  • the spring section 115 a except for the edge portions on both ends in the axial direction, is mostly the cylindrical tube section 78 . Consequently, the amount of elastic torsional deformation that occurs in the spring section 115 a when torque is being transmitted mostly occurs in the cylindrical tube section 78 .
  • the ten-point average roughness Rz of the outer-circumferential surface of the cylindrical tube section 78 is put within the range Rz ⁇ 22 ⁇ m. Furthermore, of the surface of the torsion bar 15 a , at least the hardness of the outer-circumferential surface of the spring section 115 a is made to be 450 Hv (and preferably 500 Hv or greater).
  • spring steel JIS G 4801
  • Spring steel includes silicon manganese steel (SUPE, SUPT), manganese chromium steel (SUP9, SUP9A), chromium vanadium steel (SUP10), manganese chromium boron steel (SUP11A), silicon chromium steel (SUP 12), and chromium molybdenum steel (SUP13); and the mechanical properties of these are a yield stress (0.2% yield strength): 100 to 1100 MPa, and hardness: 350 Hv to 450 Hv.
  • the spring section 115 a of the torsion bar 15 a of the rotation transmission device with torque measurement device of this example in order to achieve a high degree of both maintenance of durability and maintenance of elastic torsional deformation per unit torque, using a material having a high yield stress ⁇ y and fatigue strength ⁇ w as the material of the torsion bar 15 a is effective; and more specifically, using a material having a yield stress ⁇ y of 1100 MPa or greater (and preferably 1200 MPa or greater) and a fatigue strength ⁇ w of 500 MPa or greater (an preferably 600 MPa or greater) is effective. Moreover, there is a correlation between the yield stress ⁇ y and fatigue strength ⁇ w and the hardness, and a hard hardness is preferred.
  • making the hardness of at least the outer-circumferential surface of the spring section 115 a of the surface of the torsion bar 15 a 450 Hv (upper limit of the hardness of the spring steel material used as the material for a typical torsion bar as described above) or greater (and preferably 500 Hv or greater) is effective.
  • this hardness is made to be 850 Hv or less (and preferably, 800 Hv or less).
  • a material having a higher carbon concentration than the spring steel JIS G 4801, carbon concentration of 0.45 to 0.65%
  • the carbon concentration of the metal material of the torsion bar 15 a is 0.65% or greater (and preferably, 0.7% or greater).
  • the carbon concentration is made to be 1.5% or less (and preferably, 1.25% or less, and even more preferably, 1.2% or less). More specifically, high carbon chromium bearing steel (carbon concentration: 0.9 to 1.1%) or carbon tool steel (carbon concentration: 0.65 to 1.5%) is used as the metal material of the torsion bar, and tempering is performed at 800 to 860° C., after which annealing is performed at 150 to 500° C.
  • spring steel is used as the metal material of the torsion bar 15 a
  • the torsion bar 15 a is made by performing annealing at a temperature (450° C. or less, and preferably 400° C.) that is lower than the annealing temperature (450 to 570° C.) for normal spring steel. More specifically, the torsion bar 15 a is made by performing tempering of the spring steel at 800 to 880° C., and then performing annealing at 150 to 450° C.
  • the torsion bar 15 a is made by performing a carburizing process in a carburizing gas atmosphere of propane, methane, butane gas or the like at 700° C. to 900° C.
  • machine structure carbon steel JIS G 4052
  • machine structure alloy JIS G 4053: nickel chromium steel, nickel chromium molybdenum steel, chromium steel, chromium molybdenum steel, manganese steel, manganese chromium steel or the like
  • performing a carbo-nitriding process in a mixed atmosphere of a carburizing gas and ammonia gas and then performing an annealing process at 150° C. to 500° C.
  • the torsion bar 15 a is made by performing a tempering process at 830° C. to 870° C. on a spring steel material, and then performing an annealing process at 460° C. to 570° C., and when necessary, further performing a polishing process, and then finally performing a shot-peening process.
  • Shot-peening balls made of a material such as steel, glass or ceramic and having a diameter of 0.1 to 1 mm are used in the shot-peening process.
  • the shot-peening process By performing this kind of shot-peening process, not only is it possible to improve the hardness of the torsion bar 15 a , but it is also possible to improve the fatigue strength by generating compressive residual stress.
  • the compressive residual stress on the surface layer of the torsion bar 15 a is preferably 200 MPa or greater.
  • the shot-peening process can also be performed on the inner-circumferential surface.
  • the ratio di/do of the inner-diameter dimension di and the outer-diameter dimension do of the cylindrical tube section 78 , and the ten-point average roughness of the outer-circumferential surface Rz of the cylindrical tube section 78 are kept within the respective ranges described above (0.5 ⁇ di/d ⁇ 0.8, R ⁇ 22 ⁇ m), so it is possible to maintain at a high degree both durability and the amount of elastic torsional deformation of the spring section 115 a , of which the cylindrical tube section 78 is the main portion.
  • the ratio di/do of the inner-diameter dimension di and outer-diameter dimension do of the cylindrical tube section 78 is 0.8 or less (di/do ⁇ 0.8), so the maximum shear stress that acts on the outer-circumferential surface of the cylindrical tube section 78 can be kept low.
  • the ten-point average roughness Rz of the outer-circumferential surface of the cylindrical tube section 78 is 22 ⁇ m or less (Rz ⁇ 22 ⁇ m), so even when the maximum shear stress is repeatedly applied to the outer-circumferential surface of the cylindrical tube section 78 , it is possible to make it difficult for cracking, which is the start of fatigue fracture, to occur on the outer-circumferential surface of the cylindrical tube section 78 .
  • the ratio di/do of the inner-diameter dimension di and outer-diameter dimension do of the cylindrical tube section 78 is 0.5 or greater (0.5 ⁇ di/do), so it is possible to prevent the wall thickness (torsional rigidity) in the radial direction of the cylindrical tube section 78 from becoming excessively large, and thus it is possible to sufficiently maintain the amount of elastic torsional deformation per unit torque in the spring section 115 a.
  • the hardness of the outer-circumferential surface of at least the spring section 115 a is 450 Hv or greater (and preferably, 500 Hv or greater). Therefore, it is possible to more easily maintain the durability of the spring section 115 a of the torsion bar 15 a.
  • the spring section 115 a of the torsion bar 15 a it is important to maintain at a high degree, both the durability required for preventing fatigue fracture due to repeatedly transmitting torque, and the amount of elastic torsional deformation per unit torque that is necessary for improving the precision and resolution of torque measurement.
  • Equation (1) when the inner-diameter dimension di is made small with respect to the outer-diameter dimension do, the maximum shearing stress ⁇ max becomes small by that amount, so it become difficult for fatigue fracture to occur in the cylindrical tube section 78 . Therefore, the durability of the spring section 115 a , of which the cylindrical tube section 78 is the major part, is improved the smaller the inner-diameter dimension di is with respect to the outer-diameter dimension do.
  • plural torsion bars 15 a having ratios di/do of the inner-diameter dimension di and outer-diameter dimension do of the cylindrical tube section 78 that were different from each other were prepared, and testing of these specimens was performed by applying a torque load to the spring section 115 a . More specifically, in order to perform this testing, a tester such as illustrated in FIG. 51 was used. In other words, of the torsion bar 15 a , one end section that is separated from the spring section 115 a (left end section in FIG. 51 ) and one end section of the coupling shaft 9 that is passed through the center hole of the torsion bar 15 a (left end section in FIG.
  • the senor unit 12 is supported by and fastened to a fixed support (not illustrated in the figure).
  • a hydraulic device (not illustrated in the figure) rotates the second fastener 81 , which applies a torque to the spring section 115 a of the torsion bar 15 a .
  • the other test conditions are as given below.
  • the tester described above was used, and a 500 Nm torque T was repeatedly applied as a load to the spring section 115 a of the torsion bar 15 specimens.
  • the variation width in the torque measurement values that was found based on the phase difference ratio of the output signals from the pair of sensors, and the measurement error of the torque measurement was found by dividing the variation width by the torque T (500 Nm) load.
  • the ratio di/do when the ratio di/do becomes 0.5 or greater (0.5 ⁇ di/do), the error of the torque measurement rapidly decreases (6% or less). Therefore, in order to sufficiently maintain the precision (resolution) of torque measurement, the ratio di/do should be 0.5 or greater (0.5 ⁇ di/do).
  • the ratio di/do should be kept within the range 0.5 ⁇ di/do ⁇ 0.8.
  • the maximum shearing stress ⁇ mas in Equation (1) acts on the outer-circumferential surface of the cylindrical tube section 78 . Therefore, when the cylindrical tube section fractures due to fatigue, first, cracking occurs on the outer-circumferential surface, and that cracking progresses toward the inside until fracture occurs. In this case, when the surface roughness of the outer-circumferential surface is large, minute unevenness on the outer-circumferential surface becomes the cause of concentrated stress, and it becomes easy for cracking to occur, so the fatigue strength decreases by that amount.
  • the inventors performed additional testing.
  • material material having a ten-point average roughness Rz of the outer-circumferential surface of the cylindrical tube section 78 of about 60 ⁇ m
  • material material having a ten-point average roughness Rz of the outer-circumferential surface of the cylindrical tube section 78 of about 60 ⁇ m
  • FIG. 52 illustrates a twenty-first example of an embodiment of the present invention.
  • a feature of the rotation transmission device of this example the reduction in manufacturing cost by integrating part of the members of this device.
  • an input-side rotating body 82 is constructed by fastening an input gear 7 around the outside of the middle section in the axial direction of an input-side unit 83 so as to be concentric with the input-side unit 83 , and so as to be able to rotate in synchronization with the input-side unit 83 .
  • the input-side unit 83 is an integrally formed part that is formed by integrating together an input shaft 13 c , an inner ring 30 e of a conical roller bearing 29 e that supports the input shaft 13 c so as to be able to freely rotate with respect to the housing, and a torsion bar 15 b .
  • the input-side unit 83 is such that a stepped surface 27 that faces one end side in the axial direction of the input shaft 13 c is provided around the outer-circumferential surface of the middle section in the axial direction.
  • the input-side unit 83 is made by performing plastic working such as forging or by cutting a metal material such as a chromium steel like SCr420 or SCM420, or a chromium molybdenum steel such as SCM420 or the like, and then performing heat treatment such as carburizing or carbo-nitriding.
  • plastic working such as forging or by cutting a metal material such as a chromium steel like SCr420 or SCM420, or a chromium molybdenum steel such as SCM420 or the like, and then performing heat treatment such as carburizing or carbo-nitriding.
  • the input gear 7 is positioned in the axial direction with respect to the input-side unit 83 by the portion near the inner circumference of one side surface (left side surface of FIG. 52 ) coming in contact with the stepped surface 27 .
  • the input gear 7 is prevented from displacing in the axial direction with respect to the input-side unit 83 by a retaining ring engaging with a portion on the outer-circumferential surface of the input-side unit 83 that comes in contact with the one end side in the axial direction of the input gear 7 .
  • the inner-diameter dimension of the input gear 7 is larger than the outer-diameter dimension of the inner ring 30 e .
  • the input shaft 13 c , the inner ring 30 e of the conical roller bearing 29 e that supports the input shaft so as to be able to freely rotate with respect to the housing, and the torsion bar 15 b are integrally formed, so it is possible to suppress the cost of managing parts and the assembly cost. Furthermore, there is no need for parts such as the retaining ring 25 a , spacer 31 , nut 32 a and the like that are used for assembling the members 13 c , 30 e , 15 b so as not to separate from each other; and from this aspect as well, it is possible to suppress the cost of managing parts. As a result, it is possible to reduce the manufacturing cost of the rotation transmission device.
  • FIG. 53 illustrates a twenty-second example of an embodiment of the present invention.
  • the input gear 7 a in addition to the inner ring 30 e , input shaft 13 c and torsion bar 15 b , the input gear 7 a is also integrally formed. Therefore, the input gear 7 a does not need to be formed as an independent part, and thus it is possible to eliminate parts such as the retaining ring for preventing the input gear 7 a from displacing in the axial direction with respect to the input shaft 13 c . Consequently, it is possible to suppress the cost for managing parts and the assembly cost by that amount, and thus it is also possible to further reduce the manufacturing cost of the rotation transmission device.
  • the other construction and functions are the same as those of the twenty-first example of an embodiment.
  • FIG. 54 illustrates a twenty-third example of an embodiment of the present invention.
  • an output-side rotating body 84 is formed by fastening an output gear 8 a around the outside of the middle section in the axial direction of an output-side unit 85 so as to be concentric with the output-side unit 85 , and so as to be able to rotate in synchronization with the output-side unit 85 .
  • the output-side unit 85 is an integrally formed part by integrally forming an output shaft 14 a , an inner ring 30 f of a conical roller bearing 29 f that supports the output shaft 14 a so as to rotate freely with respect to a housing, and a torsion bar 15 c .
  • the output-side unit 85 is such that a stepped surface 86 that faces toward the other end side in the axial direction of the output shaft 14 a is provided around the outer-circumferential surface of the middle section in the axial direction.
  • the output-side unit 85 is made by performing plastic working such as forging or by cutting a metal material such as a chromium steel like SCr420 or SCM420, or a chromium molybdenum steel such as SCM420 or the like, and then performing heat treatment such as carburizing or carbo-nitriding.
  • the output gear 8 a is positioned in the axial direction with respect to the output-side unit 85 by one side surface (right side surface in FIG. 54 ) of the output gear 8 a coming in contact with the stepped surface 86 .
  • the output gear 8 a is prevented from displacement in the axial direction with respect to the output-side unit 85 by a retaining ring or the like engaging with a portion on the outer-circumferential surface of the output-side unit 85 that is in contact with the other side in the axial direction of the output gear 8 a .
  • the inner-diameter dimension of the output gear 8 a is larger than the outer-diameter dimension of the inner ring 30 d , so it is possible to pass the outer gear 8 a in the axial direction over the inner ring 30 f when installing the outer gear 8 a in the output-side unit 85 or removing the output gear 8 a from the output-side unit 85 .
  • the output shaft 14 a , the inner ring 30 f of the conical roller bearing 29 f and the torsion bar 15 c are integrally formed, so it is possible to suppress the cost of managing parts and assembly costs. Furthermore, there is no need for parts such as a retaining ring 25 b and nut 32 b that are used for assembling these members 14 a , 30 f , 15 c so as not to separate from each other, and so from this aspect as well, it is possible to suppress the cost of managing parts. Therefore, it is possible to reduce the manufacturing cost of the rotation transmission device.
  • FIG. 55 illustrates a twenty-fourth example of an embodiment of the present invention.
  • the output gear 8 in addition to the inner ring 30 f , the output shaft 14 a and torsion bar 15 c , the output gear 8 is also integrally formed. Therefore, there is no need to form the output gear 8 as an independent part, and it is possible to eliminate installing parts for preventing the output gear 8 from displacing in the axial direction with respect to the output shaft 14 c . Consequently, it is possible to suppress the cost of managing parts and the assembly cost, and to further reduce the manufacturing cost of the rotation transmission device by that amount.
  • the other construction and functions are the same as those of the twenty-third example of an embodiment.
  • FIG. 56 and FIG. 57 illustrate a twenty-fifth example of an embodiment of the present invention.
  • the amount of run-out of the first encoder 10 with respect to the second encoder 11 that is associated with error in the torque measurement is kept small by improving the concentricity of the centers of rotation of the first and second encoders 10 , 11 .
  • the first encoder 10 is concentrically fastened around the other end section of the coupling shaft 9 .
  • the first encoder has a metal core 35 made of a magnetic metal, and a permanent magnet 37 .
  • the metal core 35 includes: a cylindrical shaped fitting cylindrical section 87 that fits onto the coupling shaft 9 ; an outward-facing flange shaped wheel section 88 that is provided around the middle section in the axial direction of the fitting cylindrical section 87 ; and a cylindrical section 89 that is provided in a direction toward one end side in the axial direction of the coupling shaft 9 from the outer-circumferential edge of the cylindrical section 89 .
  • the permanent magnet 37 is fastened around the entire outer-circumferential surface of the cylindrical section 89 .
  • a sliding bearing 91 that is made of a material that slides easily such as oil-impregnated metal, synthetic resin or the like is provided between a large-diameter section 90 that is provided on the outer-circumferential surface of the other end section of the output shaft 14 b and the outer-circumferential surface of one end section (right-end section in FIG. 57 ) of the fitting cylindrical section 87 .
  • the coupling shaft 9 is supported by the input shaft 13 by connecting the outer-circumferential surface of a rim section 34 that is formed on one end section of the coupling shaft 9 and the inner-circumferential surface of one end section of the input shaft 13 by an involute spline connection 24 d .
  • the rim section 34 is held on both sides in the axial direction by a pair of retaining rings 25 a , 25 c that are fastened around the inner-circumferential surface of the input shaft 13 , which prevents the coupling shaft 9 from displacing in the axial direction with respect to the input shaft 13 .
  • the hollow cylindrical shaped torsion bar 15 is inserted into the inner-diameter sides of the input shaft 13 and output shaft 14 b from the opening on the other end side of the output shaft 14 b .
  • an involute spline connection 24 a is formed by connecting a first male involute spline section 62 that is provided on the outer-circumferential surface of one end section of the torsion bar 15 with a first female involute spline section 63 that is provided on the inner-circumferential surface of one end section of the input shaft 13
  • an involute connection 24 b is formed by connecting a second male involute spline section 64 that is provided on the outer-circumferential surface of the other end section of the torsion bar 15 with a second female spline section 65 that is provided on the inner-circumferential surface of the other end section of the output shaft 14 b .
  • the torsion bar 15 is supported on the inner-diameter side of the input shaft 13 and output shaft 14 b .
  • the sliding bearing 91 is pressure fitted into the large-diameter section of the output shaft 14 b , and one side surface (right-side surface in FIG. 57 ) of the sliding bearing 91 is pressed against the other end surface of the torsion bar 15 .
  • the torsion bar 15 is held on both sides in the axial direction between the retaining ring 25 a and sliding bearing 91 , which prevents the torsion bat 15 from displacing in the axial direction with respect to the input shaft 13 and the output shaft 14 b .
  • an involute connection 24 e for preventing the relative rotation with respect to a cylindrical surface connecting connection 26 b for maintaining concentricity is formed by fastening the fitting cylindrical section 87 of the metal core 35 of the first encoder 10 onto a small-diameter section 92 that is provided on the other end section of the coupling shaft 9 , and a retaining ring 25 d prevents the metal core 35 from displacing in the axial direction.
  • the first encoder 10 is fastened to and supported by the input shaft 13 by way of the coupling shaft 9 so as to be concentric with the input shaft 13 , and so as to be able to rotate in synchronization with the input shaft 13 , and the outer-circumferential surface of one end section (right-end section in FIG. 57 ) of the fitting cylindrical section 87 is made to slide over or closely face the inner-circumferential surface of the sliding bearing.
  • the procedure for assembling the rotation transmission device of this example is not limited to the procedure described above.
  • a sliding bearing 91 is provided between the large-diameter section 90 that is provided on the inner-circumferential surface of the other end section of the output shaft 14 b and the outer-circumferential surface of one end section of the fitting cylindrical section 87 of the metal core 35 of the first encoder 10 , so it is possible to keep the amount of run-out of the first encoder 10 with respect to the second encoder 11 that is associated with the error in torque measurement small.
  • the inner-circumferential surface of the sliding bearing 91 that is pressure fitted into the large-diameter section 90 is made to slide over or closely face the outer-circumferential surface of the fitting cylindrical section 87 that is fastened around the outside of the other end section of the coupling shaft 9 , so it is possible to improve the concentricity between the center of rotation of the first encoder 10 that is fastened to and supported by the other end section of the coupling shaft 9 and the center of rotation of the second encoder 11 that is fastened to and supported by the output shaft 14 b . As a result, it is possible to keep the amount of run-out of the first encoder 10 with respect to the second encoder 11 small.
  • one side surface of the sliding bearing 91 that is pressure fitted into the large-diameter section 90 of the output shaft 14 b is pressed against the other end surface of the torsion bar 15 . Therefore, when compared with the case when the torsion bar 15 is held on both sides in the axial direction by retaining rings 25 a , 25 b that are fastened around the inner-circumferential surfaces of the input shaft 13 and output shaft 14 ( 14 a ) (see FIG. 6 ), it is possible to effectively prevent looseness in the axial direction of the torsion bar 15 with respect to the input shaft 13 and output shaft 14 b . Moreover, it is not necessary to provide a fastening groove for fastening the retaining ring 25 b (see FIG.
  • FIG. 58 illustrates a twenty-sixth example of an embodiment of the present invention.
  • a feature of this example, and in the twenty-fifth example of an embodiment, is to keep the amount of run-out of the first encoder 10 with respect to the second encoder 11 that is associated with error in torque measurement small by improving the concentricity of the centers of rotation of the first and second encoders 10 , 11 .
  • the coupling shaft 9 c is supported by the input shaft 13 d so as to be concentric with the input shaft 13 d and so as to rotate in synchronization with the input shaft 13 d by pressure fitting an outward-facing flange shaped rim section 34 b that is formed around the outer-circumferential surface of one end section of the coupling shaft 9 c into a large-diameter section 93 that is provided around the inner-circumferential surface of one end section of the input shaft 13 d . Then, the other side surface (right-side surface in FIG. 58 ) of the rim section 34 b is pressed against one end surface (right-end surface in FIG. 58 ) of the torsion bar 15 , directly, or in other words, not by way of another member.
  • the coupling shaft 9 c is supported by the input shaft 13 d by pressure fitting the rim section 34 b of the coupling shaft 9 c into the large-diameter section of the input shaft 13 d . Therefore, when compared with the case of supporting the coupling shaft 9 by the input shaft by way of the involute spline connection 24 a , it is possible to improve the concentricity of not only the center axis of the coupling shaft 9 a and the center axis of the input shaft 13 a , but the center axis of the output shaft 14 as well.
  • the other side surface of the rim section 34 b that is pressure fitted into the large-diameter section 93 of the input shaft 13 d is pressed against one end surface of the torsion bar 15 . Therefore, compared with the case of holding the torsion bar 15 on both sides in the axial direction by the retaining rings 25 a , 25 b that are fastened around the inner-circumferential surfaces of the input shaft 13 and output shaft 14 , it is possible to effectively prevent looseness in the axial direction of the torsion bar 15 with respect to the input shaft 13 a and output shaft 14 .
  • FIG. 59 and FIG. 60 illustrate a twenty-seventh example of an embodiment of the present invention.
  • the construction of the sensor unit 12 d and the construction for supporting the sensor unit 12 by the housing (not illustrated in the figures) is devised in order to simplify positioning of the sensor unit 12 d with respect to the first and second encoders 10 , 11 , and to improve the reliability of the torque measurement.
  • the output shaft 14 is supported by a conical roller bearing 29 g that is located between a portion near the other end (left end in FIG. 59 ) of the outer-circumferential surface of the output shaft 14 and the inner-circumferential surface of the housing so as to rotate freely with respect to the housing.
  • the half of the outer ring 94 of the conical roller bearing 29 g near the other end side in the axial direction functions as an extended cylindrical section 95 that protrudes further in the axial direction than the end section on the small-diameter side of the inner ring 30 g of the conical roller bearing 29 g .
  • the inner-circumferential surface of the extended cylindrical section 95 is screwed onto the other end section of the outer-circumferential surface of the output shaft 14 and tightened so as to face the outer-circumferential surface of a nut 32 b.
  • the sensor unit 12 includes a sensor cover 96 , a sensor holder 97 , and a first and second sensor 42 a , 42 b .
  • the sensor cover 96 is formed using metal sheet into a cylindrical shape with a bottom, and includes a cover cylinder section 98 and a cover bottom plate section 99 that covers the opening on the base end of the cover cylinder section 98 .
  • an outward-facing flange shaped rim section 100 is provided on the portion near the tip end of the outer-circumferential surface of the cover cylinder section 98 , and a through hole 101 is provided in part of the cover bottom plate section 99 (portion near the outer circumference in the example in the figure).
  • the sensor holder 97 is formed into a complete cylindrical shape with a bottom using a synthetic resin, and is fastened to and supported by the inner surface of the sensor cover 96 by insert molding or adhesive.
  • First and second sensors 42 a , 42 b are embedded in the cylindrical portion of the sensor holder 97 that is located on the inner-diameter side of the cover cylinder section 98 .
  • a connector section 102 that is provided on part of the sensor holder 97 protrudes through the through hole 101 to the outside of the sensor cover 96 .
  • the end section of a harness for the output signals from the first and second sensors 42 a , 42 b can be connected to or disconnected from this connector section 102 .
  • the sensor unit 12 a having construction such as described above is fastened to and supported by the housing by way of an outer ring 94 . More specifically, the tip-end section of the cover cylinder section 98 of the sensor cover 96 is pressure fitted into the inner-circumferential surface of the tip-end section of the extended cylindrical section of the outer ring 94 and connected with an interference fit. Moreover, the sensor unit 12 d is positioned in the axial direction with respect to the outer ring 94 by bringing the side surface of a rim section 100 that is provided on the portion near the tip end of the outer-circumferential surface of the cover cylinder section 98 into contact with the tip-end surface of extended cylindrical section 95 .
  • the first and second encoders 10 , 11 are placed in a space on the inside of the sensor cover 96 , and detecting sections of the first and second sensors 42 a , 42 b are made to face first and second detected sections 39 , 40 of the first and second encoders 10 , 11 .
  • a seal ring 104 is installed between a space where plural rollers 103 of the conical roller bearing 29 g are located, and a space on the inside of the sensor cover 96 where the first and second detected sections 39 , 40 are arranged, and functions as a seal device for partitioning between these spaces.
  • the seal ring 104 includes a circular ring-shaped metal core 105 having an L-shaped cross section, and a circular ring-shape seal member 106 that is reinforced by the metal core 105 .
  • the metal core 105 fits around the outer-circumferential surface of the tip-end section of the nut 32 , which is a cylindrical surface, by an interference fit, and the tip-end edge of the seal lip of the seal member is made to come in contact with the inner-circumferential surface of the base-end section of the extended cylindrical section 95 , which is a cylindrical surface.
  • lubrication oil that includes foreign magnetic matters such as iron powder that is supplied to the space where the conical rollers 75 are located is prevented from passing through the portion between the inner-circumferential surface of the extended cylindrical section 95 and the outer-circumferential surface of the tip-end section of the nut 32 b , and getting into the space inside the sensor cover 96 .
  • This kind of seal device is not limited to this seal ring 104 , and various forms can be used.
  • a seal member in which a metal core fits around the inner-circumferential surface of the extended cylindrical section 95 , and the tip-end edge of the seal lip comes in sliding contact with the surface of the nut 32 b (or output shaft 14 ). In either case, using a seal device having good seal characteristics, and for which the sliding resistance between the tip-end edge of the seal lip and the opposing surface is kept low is preferred.
  • the sensory unit 12 d is fastened to and supported by the outer ring 94 of a conical roller bearing 29 c that is installed between the output shaft 14 and the housing. Therefore, when compared with construction in which the sensor unit 12 and the rotary-shaft unit 6 (see FIG. 6 ) that supports the first and second encoders 10 , 11 are separately fastened to and supported by the housing, it is easier to maintain the positioning precision of the sensor unit 12 d with respect to the first and second encoders 10 , 11 . Moreover, it is possible to assemble the sensor unit 12 d and rotary-shaft unit 6 in a specified positional relationship before assembly inside the housing, and that positional relationship does not move after that, so from this aspect, maintaining positional precision becomes easier.
  • the first and second detected sections 39 , 40 and the detecting sections of the first and second sensors 42 a , 42 b are arranged inside the sensor cover 96 , and a seal ring 104 is installed between the space inside the sensor cover 96 and the space where the plural conical rollers 103 of the conical roller bearing 29 g are located so as to be a partition between these spaces. Therefore, it is possible to suppress or prevent lubrication oil that is inside the housing and that includes magnetic foreign matter (including lubrication oil that is supplied to the space where the conical rollers 103 are located) from adhering to the first and second detected sections 39 , 40 and the detecting sections of the first and second sensors 42 a , 42 b . As a result, it is possible to further improve the reliability of torque measurement.
  • the first and second encoders 10 , 11 are housed in a space inside the sensor cover 96 , so, for example, the first and second encoders 10 , 11 are prevented from bumping the housing and becoming damaged when assembling the sensor unit 12 d and rotary-shaft unit 6 in the housing after the sensor unit 12 d and rotary-shaft unit 6 (see FIG. 6 ) have been assembled. Moreover, in the stage before assembling portions other than the housing inside the housing, it is possible to check the output signals of the first and second sensors 42 a , 42 b .
  • the rolling bearing for supporting the input shaft and output shaft so as to freely rotate with respect to the housing is not limited to a conical roller bearing, and it is also possible to use other types of bearings such as an angular ball bearing.
  • the other construction and functions are the same as those of the first through twenty-sixth examples of embodiments.
  • FIG. 61 illustrates a twenty-eighth example of an embodiment of the present invention.
  • the construction of the installation location of the first and second encoders 10 a , 11 a is devised in order to improve the precision of torque measurement.
  • the inner ring 30 h of a conical roller bearing 20 h for supporting the output shaft 14 c so as to rotate freely with respect to the housing is fastened around a portion near the other end of the output shaft 14 c , and the end surface on the large-diameter side of the inner ring 30 is made to come in contact with a stepped surface 33 that s formed in a portion near the other end of the outer-circumferential surface of the output shaft 14 c .
  • the inner ring 30 h is fastened around the outside of the output shaft 14 c by pressure fitting the end surface on the small-diameter side of the inner ring 30 h with a nut 32 c that is screwed onto the other end section of the outer-circumferential surface of the output shaft 14 c and tightened.
  • a cylindrical shaped extended cylindrical section 107 that protrudes in the axial direction from the inner-diameter side of the outer ring 94 a of the conical roller bearing 29 h is integrally provided on the end section on the small-diameter side of the inner ring 30 h , which is the end section on the other end side of the output shaft 14 c .
  • a through hole 108 in the radial direction is provided in a portion near the small-diameter side of the inner ring 30 h .
  • Lubrication oil can be supplied from an oil passage 44 b through this through hole 108 to the inside of the conical roller bearing 29 h.
  • the metal core 36 a of the second encoder 11 a is fastened around the outside of the extended cylindrical section 107 .
  • the second encoder 11 a is fastened around the outside of a portion near the other end of the output shaft 14 c by way of the extended cylindrical section 107 of the inner ring 30 h .
  • the metal core 36 a of the second encoder 11 a is formed into a complete circular ring shape having a crank shaped cross section, and includes a small-diameter cylindrical section 109 and large-diameter cylindrical section 110 that are arranged so as to be concentric with each other, and a ring section 111 that connects the edges on the ends in the axial direction of these cylindrical sections 109 , 110 .
  • a cylindrical shaped permanent magnet 38 a is fastened to the outer-circumferential surface of the large-diameter cylindrical section 110 .
  • the second encoder is fastened to the inner ring 30 h by fastening the small-diameter cylindrical section 109 of the metal core 36 a around the outside of the extended cylindrical section 107 of the inner ring 30 h with an interference fit.
  • the large-diameter cylindrical section 110 and permanent magnet 38 a are arranged on the other-diameter side of half (right half in FIG. 61 ) in the axial direction of the nut 32 c in positions that overlap in the radial direction with this half in the axial direction.
  • the cylindrical shaped second detected section 40 a which is the outer-circumferential surface of the permanent magnet 38 a , is arranged on the outer-diameter side of half in the axial direction of the nut 32 c so as to overlap in the radial direction this half in the axial direction (and other end section of the output shaft 14 c ).
  • the metal core 35 a of the first encoder 10 a is formed into a complete circular ring shape with a C-shaped cross section, and includes a small-diameter cylindrical section 112 and a large-diameter section 113 that are arranged so as to be concentric with each other, and a ring section 114 that connects the end sections in the axial direction of these cylindrical sections 112 , 113 .
  • a cylindrical-shaped permanent magnet 37 a is fastened around the outer-circumferential surface of the large-diameter cylindrical section 113 .
  • the small-diameter cylindrical section 112 of the first encoder 10 a is fastened around the outside of the other end section (left-end section in FIG. 61 ) of the coupling shaft 9 .
  • connection between the inner-circumferential surface of the small-diameter cylindrical section 112 and the outer-circumferential surface of the other end section of the coupling shaft 9 is formed by arranging a cylindrical connection 26 b for maintaining concentricity and an involute spline connection 24 e for preventing relative rotation so as to be adjacently in contact with each other in the axial direction.
  • the small-diameter cylindrical section 112 is prevented from coming apart from the coupling shaft 9 by a retaining ring 25 d that is fastened around the outer-circumferential surface of the other end section of the coupling shaft 9 . In this state, one end section (right-end section in FIG.
  • one end section and middle section in the axial direction of the cylindrical-shaped first detected section 39 a which is the outer-circumferential surface of the permanent magnet 37 a , is arranged around the outer-diameter side of the other half in the axial direction of the nut 32 c , in a position that overlaps in the radial direction the other half section (or output shaft 14 c ) in the axial direction.
  • the first detected section 39 a and second detected section 40 a are adjacent in the axial direction and are arranged close to each other (for example, arranged so as to be separated by a space of 5 mm or less in the axial direction).
  • the sensor unit 12 is fastened to and supported by the housing so that of the first and second sensor 42 a , 42 b of the sensor unit 12 , the detecting section of the first sensor 42 a closely faces in the radial direction the first detected section 39 a , and the detecting section of the second sensor 42 b closely faces in the radial direction the second detected section 40 a.
  • the cylindrical shaped second detected section 40 a of the second encoder 11 a is arranged around the outer-diameter side of half in the axial direction of the nut 32 c so as to overlap in the radial direction that half in the axial direction, so compared with the first example of an embodiment, it is possible to shorten the distance D 40 in the axial direction from the center section in the axial direction of the array of rolling bodies of the conical roller bearing 29 h to the second detected section 40 a .
  • the cylindrical shaped first detected section 39 a of the first encoder 10 a that is fastened around the outside of the other end section of the coupling shaft 9 , the one end section to middle section in the axial direction is arranged around the outer-diameter side of the other half in the axial direction of the nut 32 c in a position that overlaps in the radial direction this other half in the axial direction.
  • FIG. 62 to FIG. 65 illustrates a twenty-ninth example of an embodiment of the present invention.
  • the first and second encoder 10 e , 11 e , and the sensor unit 12 e are arranged in the middle section of the rotary-shaft unit 6 a , in a portion between the input gear 7 and output gear 8 in the axial direction.
  • the first encoder 10 e is integrally formed on the tip-end surface (left-end surface in FIG. 62 and FIG. 65 ) of a parking-lock gear 28 that is integrally formed in a portion near the inner circumference on one side surface of the input gear 7 .
  • the first encoder 10 e is formed by arranging plural magnetic metal convex sections 50 a that are integrally formed so as to protrude in the axial direction from the tip-end surface of the parking-lock gear 28 so as to have a uniform pitch in the circumferential direction.
  • the entire first encoder 10 e functions as a first detected section 39 e .
  • the first encoder 10 e is fastened to the input shaft 13 by way of the input gear 7 and parking-lock gear 28 .
  • the second encoder 11 e is integrally formed with a portion that is near the outer-circumferential surface of the output shaft 14 , and that is adjacent in the axial direction to the output gear 8 .
  • the second encoder 11 e is formed by arranging plural magnetic metal convex sections 50 b that are integrally formed so as to protrude in the radial direction from a portion near on end of the outer-circumferential surface of the output shaft 14 so as to have a uniform pitch in the circumferential direction.
  • the entire second encoder 11 e functions as a second detected section 40 e .
  • the first and second encoders 10 e , 11 e have the same outer-diameter dimensions, and are arranged so as to be concentric with each other and so as to be closely adjacent to each other in the axial direction.
  • the total number of convex sections 50 a and the total number of convex sections 50 b are the same as each other.
  • the width in the circumferential direction of the convex sections 50 a and the width in the circumferential direction of the convex sections 50 b are the same as each other.
  • the phases in the circumferential direction of the convex sections 50 a and convex sections 50 b coincide.
  • the sensor unit 12 e includes a holder 41 c that is made of a synthetic resin, and first and second sensors 42 e , 42 f that are embedded in the tip-end sections of the holder 41 c .
  • the sensor unit 12 e is supported by a housing (not illustrated in the figures) so that the detecting section of the first sensor 42 e closely faces the outer-circumferential surface of the first encoder 10 e (first detected section 39 e ), and the detecting section of the second sensor 42 f closely faces the outer-circumferential surface of the second encoder 11 e (second detected section 40 e ).
  • Each of the sensors 42 e , 42 f includes a permanent magnet that is magnetized in the direction that the outer-circumferential surface of the encoder 10 e , 11 e faces the detecting section of the sensor 42 e , 42 f ; and a magnetism-detecting element such as a Hall element, Hall IC, MR element, GMR element or the like that is located in the end surface of both end surfaces in the direction of magnetization of the permanent magnet.
  • One permanent magnet can also be shared as the permanent magnet of the sensors 42 e , 42 f.
  • the frequency (and period) of the output signals from the first and second sensors 42 e , 42 f of the sensor unit 12 e is a value that corresponds to the rotational speed of the rotary-shaft unit 6 a . Therefore, it is possible to find the rotational speed based on the frequency (or period).
  • the other construction and functions are the same as those of the first example of an embodiment.
  • the form of a transmission in which the present invention is assembled and used is not particularly limited as long as the construction has a counter shaft and a counter gear, and it is possible to use various kinds of transmissions such as an automatic transmission (AT), continuously-variable transmission (CVT), manual transmission (MT) and the like. Moreover, the rotational speed and torque that are measured can be used for other control of an automobile besides transmission control. Furthermore, a motor that is placed on the up-stream side of the transmission does not absolutely need to be an internal-combustion engine such as a gasoline engine or a diesel engine, and it is also possible for the motor to be an electric motor that is used, for example, in a hybrid automobile or an electric automobile. In either case, present invention can be widely applied to various kinds of machinery in which it is necessary to transmit torque by a rotary shaft, and to measure the torque that is transmitted by the rotary shaft.
  • AT automatic transmission
  • CVT continuously-variable transmission
  • MT manual transmission
  • the rotational speed and torque that are measured can be used for other control of an automobile

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  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Mechanical Engineering (AREA)
  • General Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Acoustics & Sound (AREA)
  • Aviation & Aerospace Engineering (AREA)
  • Control Of Transmission Device (AREA)
  • Transmission And Conversion Of Sensor Element Output (AREA)
US14/901,063 2013-06-25 2013-11-08 Rotation transmission device Abandoned US20160195183A1 (en)

Applications Claiming Priority (17)

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JP2013132497A JP6083333B2 (ja) 2012-06-29 2013-06-25 トルク測定装置付回転伝達装置
JP2013-132497 2013-06-25
JP2013-224610 2013-10-29
JP2013224610A JP6075266B2 (ja) 2013-10-29 2013-10-29 トルク測定装置付回転伝達装置
JP2013-224156 2013-10-29
JP2013224156A JP2015087154A (ja) 2013-10-29 2013-10-29 トルク測定装置付回転伝達装置
JP2013-225481 2013-10-30
JP2013225481A JP6179350B2 (ja) 2013-10-30 2013-10-30 トルク測定装置付回転伝達装置
JP2013229682A JP6075269B2 (ja) 2013-11-05 2013-11-05 トルク測定装置付回転伝達装置
JP2013-229682 2013-11-05
JP2013229873A JP6075270B2 (ja) 2013-11-06 2013-11-06 トルク測定装置付回転伝達装置
JP2013-229873 2013-11-06
JP2013-229952 2013-11-06
JP2013229952A JP2015090313A (ja) 2013-11-06 2013-11-06 トルク測定装置付回転伝達装置
JP2013231070A JP2015090340A (ja) 2013-11-07 2013-11-07 トルク測定装置付回転伝達装置
JP2013-231070 2013-11-07
PCT/JP2013/080358 WO2014207953A1 (fr) 2013-06-25 2013-11-08 Dispositif de transmission de rotation

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EP3015836A1 (fr) 2016-05-04
EP3309419A2 (fr) 2018-04-18
EP3309419B1 (fr) 2019-12-25
US20170227111A1 (en) 2017-08-10
US10480635B2 (en) 2019-11-19
WO2014207953A1 (fr) 2014-12-31
EP3015836A4 (fr) 2017-06-21

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