JPH0322402A - Rotary potentiometer - Google Patents

Abstract

PURPOSE:To achieve a fail-safe function, reduce the cost, and facilitate the adjustment by assembling two slider segments and resistors electrically independently of each other and providing a variable resistor, which is connected to a circuit so that it is adjustable from outside of a casing, on one resistor. CONSTITUTION:When an input shaft 3 is rotated relative to a pinion shaft 5, a slider 53 linked to these two shaft 3, 5 via a driving pin 58 slides on the pinion shaft 5. Due to this sliding motion of the slider 53, a rotary shaft 65 of a rotary potentiometer 64 is slidably rotated in the direction of the shaft center of the pinion shaft 5, and the sliding amount of the slider 53 is measured in terms of rotational angle. Moreover, in the rotary potentiometer 64, two slider segments 74a, 74b and resistors 75a, 75b are assembled electrically independently of each other, and a variable resistor 77 is connected to either one resistor 75a or 75b so that the resistor 77 is adjustable from outside of a casing 68. Therefore, accidental power-assist due to false detection can be avoided.

Description

[Detailed Description of the Invention] Industrial Application Fields The present invention provides a rotation system suitable for use in electric power steering devices, etc. that electrically detect relative displacement between input and output shafts to provide power assist. Regarding type potentiometer.

Conventional technology> Electric power steering systems, which are capable of fine-grained control according to vehicle driving conditions, are being developed as an alternative to the commonly used hydraulic power steering systems. .

Examples of such electric power steering devices include those shown in FIGS. 10 and 11, for example.

First, a cylindrical input shaft 3 is rotatably supported by an upper cover 1 via a bearing 2, and the upper end of this human-powered shaft 3 protrudes from the upper cover 1. A steering handle shaft 4 is coupled to the upper end of the input shaft 3. Further, at the lower end of the input shaft 3, the upper end of a binion shaft 5 as a steering gear shaft (output shaft) disposed coaxially with the input shaft 3 can be relatively rotated via a bearing metal 6. has been done.

Further, the pinion shaft 5 is rotatably supported by a pinion case 9 via bearings 7 and 8. A torsion bar 10 as a torsion rod spring is disposed at the axial center of the input shaft 3, and the upper end of this torsion bar 10 is connected and fixed to the upper end of the input shaft 3 via a press-fit pin 11. On the other hand, the lower end of the torsion bar 10 is press-fitted into the pinion shaft 5 and spline-coupled.

A flange 12 is formed on the outer periphery of the intermediate portion of the input shaft 3, and a driven gear (driven gear) is formed on the upper end of the pinion shaft 5.
13 is formed.

Further, a housing 14 is provided between the upper cover 1 and the pinion case 9. This housing 14 has a cylindrical gear housing part 15 surrounding the collar part 12 of the input shaft 3.
are integrally formed.

A flange 16 is formed on the inner edge of the upper end of the gear housing portion 15 . Further, a swinging ring gear 17 having teeth formed on the inner circumference is rotatably fitted into the inner periphery of the upper half of the gear housing part 15, and the upper end surface of the swinging ring gear 17 is regulated by the edge flange 16. has been done. Further, on the inner periphery of the lower half of the gear housing portion 15, a fixed ring gear 19 is provided with a rotatable disk-shaped plate 18 interposed between it and the swing ring gear 17, and teeth are formed on the inner periphery. It is press-fitted. A sun gear 20 is rotatably fitted to the input shaft 3,
The upper end surface of the sun gear 20 is regulated by the flange 12.

From the bottom surface of the flange 12, three first bottles 21 are inserted at regular intervals.
are projected, and a first planetary gear 22 is rotatably fitted to each first pin z1. This first planetary gear 2
2 meshes with the swing ring gear 17 and the sun gear 20. Three second pins 23 protrude from the upper surface of the driven gear 13 coaxially with the first pin 21, and each second pin 2
3, a second planetary gear 24 is rotatably fitted into each of them.

This second planetary gear 24 meshes with the fixed ring gear 19 and the sun gear zO.

As a result, when a rotational force is applied to the input shaft 3 via a handle (not shown), the pinion shaft 5 rotates via the toshie 3-v member 10, and the first planetary gear 22, the second planetary gear 24, and the sun gear rotate. 20 is dragged and rotated within the swinging ring gear 17 and the fixed ring gear 19.

When the resistance on the pinion shaft 5 side is large, only the input shaft 3 rotates, causing twisting of the torsion lever 10. At this time, the second planetary gear 24 neither revolves nor rotates, so the sun gear 20 is in a fixed state, and due to the rotation of the input shaft 3, the first planetary gear 22 revolves and rotates, and N1llb
Rotate the ring gear 17. The amount of rotation of the swing ring gear 17 is proportional to the amount of relative rotation between the input shaft 3 and the pinion shaft 5.

An electric motor 26 is fixed to the upper cover 1 with bolts 25, and a rotating shaft 27 of the electric motor 26 is connected to a drive gear 29 via an electromagnetic clutch 28.

On the other hand, the intermediate shaft 30 is rotatably supported by the upper cover 1 and the pinion case 9 so as to be adjacent to the motor output section structure configured as described above. A driving gear 29 is provided on the upper part of the intermediate shaft 30 (the upper part of the gear housing part 15).
A first reduction gear 31 that meshes with the intermediate shaft 30 is provided.
(lower part of the gear housing part 15) is the driven gear 1.
A second reduction gear 32 that meshes with the gear 3 is provided.

Therefore, when the electromagnetic clutch 28 is connected, the driving force of the electric motor 26 is transmitted through the power transmission gear mechanism including the drive gear 29, the first reduction gear 31, the second reduction gear 32, and the driven gear 13. The driving force is increased with deceleration and transmitted to the pinion shaft 5, and the pinion shaft 5 rotates in response to this drive input.

Further, a rack 34 is engaged with the steering gear 33 of the pinion shaft 5, and the rack 34 is connected to a tie rod 35. A steering receiving arm connected to a wheel to be steered is connected to the tie rod 35. That is, the rotational force of the pinion shaft 5 is transmitted to the tie rod 35 via the steering gear 33 and the rack 34, and turns the wheels via the steering receiving arm.

Furthermore, as shown in FIG. 11, a drive groove 36 extending in the width direction is formed on the outer circumferential surface of the swing ring gear 17, and the tip of the drive bin 37 is rotatably fitted into the drive groove 36. are doing. The drive bin 37 is disposed within a holding hole 38 formed in the housing 14.

On the other hand, a spool hole 40 is provided in the housing 14 in a direction perpendicular to the axis of the input shaft 3 and perpendicular to the retainer 38, and the spool hole 40 is biased in one direction by a spring 41. The spool 42 is slidably fitted therein. A displacement sensor 43 is provided in the housing 14 on the tip end side in the biasing direction of the Subur 42.
A sensor rod 44 is disposed within the spool hole 40. The spool 42 and the sensor rod 44 are pin-coupled and attached to the intersection 42 between the retainer 638 and the spool hole 40.

Therefore, when the swinging ring gear 17 rotates, the spool 42 slides in the spool hole 40 via the drive bin 37 to drive the sensor rod 44, and the swinging ring gear 1
The rotational displacement of 7 is detected by the displacement sensor 43. and,
The detected value of the displacement sensor 43 is input to a control device (not shown), and the control device outputs an operation control signal for the electric alI 26 based on the detected value from the displacement sensor 43.

In FIG. 11, reference numeral 45 indicates a cap that closes the retainer 638, and 48 indicates an air hole formed in the spool 42.

Problems to be Solved by the Invention> By the way, in the electric power steering system as described above, if an abnormality occurs in the displacement sensor, the steering wheel may turn on its own without steering, which may be dangerous. .

Therefore, in the past, as in Japanese Patent Application Laid-Open No. 63-828757, multiple torque sensors are provided, and when an abnormality occurs in one torque sensor, power assist force control is performed by selectively using a normal torque sensor. There is something that is designed to continue. Also, JP-A-63-1623
As in Publication No. 70, first and second displacement-to-electrical signal converters are provided in the torque sensor to make torque detection a dual system, and when the deviation between the two output signals exceeds a predetermined value, the control Some devices determine that there is an abnormality and stop the power arrest by cutting off the motor current and voltage applied to the electromagnetic clutch.

However, in the former case, the number of parts increases, which increases the complexity and cost of the device, and in the latter case, after the torque sensor is assembled, the first and second parts may be damaged due to processing and assembly errors. If a large deviation occurs in the output signal of the second displacement-to-electrical signal converter, this is extremely inconvenient because it cannot be adjusted in any way.

Therefore, it is an object of the present invention to provide a rotary potentiometer that is inexpensive and convenient despite having a fail-safe function.

Means for Solving the Problems> In order to achieve the above object, the rotary potentiometer according to the present invention has rotors that are fixed to a rotating shaft and can freely rotate within a casing, electrically independent of each other. The first provided
and a second sliding piece, first and second resistors disposed on a substrate in the casing and in sliding contact with each of the sliding pieces, and one of these resistors. and a variable resistor connected to the circuit so as to be adjustable from outside the casing.

Effect> According to the above-described configuration, the fail-safe function is achieved by the two output signals. Furthermore, if a large deviation occurs between the two output signals due to machining of parts or assembly errors during assembly, the zero point can be easily adjusted from outside the casing using a variable resistor even after assembly.

Embodiment Examples Based on the attached drawings, the rotary type button i/* of the present invention will be described below.
An example in which the meter is applied to an electric power steering system will be described, but in FIGS. 1 to 10, the same members as in FIGS. 11 and 12 are given the same reference numerals, and detailed explanations will be omitted. .

As shown in FIG. 1, the upper cover 1 is directly assembled to the upper part of the pinion case 9 with bolts 50.

A pinion shaft (steering gear shaft) 5 is supported in the lower half of the input shaft 3 which is rotatably supported by the upper cover 1 in the axial direction by the hair angular bearings 7A and 8A of the binion case 9. The fitting cylinder portion 51 on the upper end side is fitted to be relatively rotatable. Note that 52 in the figure is a nut for adjusting the preload on the angular bearings 7A, 8A.

A cylindrical slider 53 is fitted to the outer circumferential surface of the fitting cylinder 51 via a bearing metal 54 so as to be relatively rotatable and slidable in the vertical direction. It is constantly urged upward by a compression coil spring 55 interposed between the shaft 5 and the driven gear 13 fitted thereto.

As shown in FIGS. 2(8) and 2(a), the upper part of the slider 53 is provided with the input shaft 3 slidably passing through a diagonal hole 56 formed in the fitting cylinder part 51. Two drive pins 58 with rollers whose tips are tightly engaged with engagement grooves 57 carved on the outer periphery of the lower part are integrally provided at symmetrical positions. In the illustrated example, a threaded rod portion 59 that is integral with the drive pin 58 is threaded into a threaded hole 60 of the slider 53 . This drive pin 58 protrudes inward in the radial direction of the slider 53,
It tightly engages with the oblique hole 56 and is slidable along an engagement groove 57 formed in the longitudinal direction of the input shaft 3.

Therefore, when relative rotation with twisting of the torsion suspension bar 10 occurs between the human power shaft 3 and the pinion shaft 5, the rotation occurs through the drive pin 58 that engages with the engagement groove 57 of the input shaft 3. The slider 53 also rotates together with the input shaft 3, but as a result of the relative rotation between the fitting cylinder part 51 and the slider 53, the drive pin 58 is displaced along the diagonal hole 56 of the fitting cylinder part 51. The circumferential surface of the portion 51 is turned spirally to be displaced in the vertical direction. In addition, the first
In the figure, 61 is fitted into the upper end of the fitting cylinder part 51 and the drive bin 5 is
8 is an annular cap to prevent loosening, 62 is input shaft 3
This stopper mechanism is provided between the facing surfaces of the fitting cylinder portion 51 and controls the amount of relative rotation between the input shaft 3 and the pinion shaft 5, and is based on a rattling serration blind system.

Further, an annular groove 63 is formed on the outer periphery of the lower part of the slider 53, and as shown in FIG. A predetermined distance lt from the center of rotation of the shaft body portion 65b! are offset and fitted so as to be slidable along the annular groove -12-63. In the illustrated example,
A roller 67 is attached to the input end 65a via a leaf spring-like retainer 66 to prevent it from falling off during assembly.

The rotary potentiometer 64 detects the vertical displacement of the slider 53 by converting it into a rotation angle.
The stepped cylindrical casing 68 is assembled to the pinion case 9 via a seal member 69.

In addition, in the rotary potentiometer 64, as shown in FIGS. 4 and 5 (4), (6), and 0, first, the shaft body of the rotating shaft 65 is attached to the receiving cylinder portion 68a of the casing 68. The upper half of the portion 65b is rotatably supported via a bush 68c, and the rotor 71 is fitted around the outer periphery of a rotor boss 70 that is press-fitted into the lower half of the shaft body 65b. An oil pipe 72 is interposed between the opposing surfaces of the rotor boss 70 and the bearing cylinder portion 68a, and the rotor 71 and rotating shaft 65 are always urged downward by a compression coil spring 73. At point-symmetrical positions on the lower surface of the rotor 71, first and second electrically independent
Sliding pieces 74a, 74b are provided, and first and second resistors 75a, 75b made of conductive plastic or the like, with which these sliding pieces 74a, 74b come into sliding contact, are attached to the casing 6.
Ceramic substrate 7 assembled to main body cylindrical portion 68b of 8
It is located at 6. A variable resistor I#77 is attached to the lower surface of the ceramic substrate 76 and is connected to one of the first and second resistors 75a, 75b in a circuit so as to be adjustable from outside the casing 68. Finally, the first and second resistors 75a, 75b and the terminals 80 of the connector 79 integrated with the cap 78 are connected by flat foldable conductors 81, and the ceramic The board 76 is always urged upward by a leaf spring 82 whose board is supported on the upper surface of the cap 78, and is pressed against the downward step of the main body cylinder part 68b. In addition, 83 in the figure is a variable resistor @7 bored in the cap 78.
This is a plug that seals the adjustment hole 84 of No. 7.

Therefore, two detected values are input to a control device (not shown), and this control device outputs an actuation signal corresponding to the detected value to the electric motor 26 (described later) only when the two detected values are the same value. do.

Further, as shown in FIG. 6, the above-mentioned rotating shaft 65 is formed by bending one end of the shaft material I with a bender to have a predetermined curvature, and then using a lathe to form an input end 65a and a shaft main body 65b. It is formed by cutting into a predetermined shape. In the illustrated example, the input end 65a is formed with a reduced diameter in two stages so as to have a mounting seat surface for the roller 67 and the holder @66.

On the other hand, a fitting cylindrical portion 85 is protruded from the upper surface of the upper cover 1.
The above-mentioned electric motor 26 is integrally assembled to the upper cover 1 using the fitting cylinder portion 85.

That is, the lower end opening of the casing 15 ring 86 is fitted into the outer periphery of the fitting cylinder part 85, and the casing 86
An upper fi 87 that closes the upper end opening is connected to the upper cover 1 with bolts 88.

Further, a brush holder 89 made of resin is loosely fitted into the inner periphery of the fitting cylinder portion 85, and this brush holder 89 and its cover plate 90 are fastened to the upper cover 1 with bolts 91. A brush 92 is provided inside the brush holder 89.
An annular groove 93 is formed to receive wear powder, and two notches 95a and 95b are formed at the lower outer periphery of the brush holder 89 for wiring lead wires 94. As shown in FIGS. 7 and 8, the lead wire 94 is pushed through two through holes 96 formed in the upper cover 1 via a cylindrical grommet 97, and led out.

Furthermore, the motor chamber B in the casing 86 is connected to a communication passage 98.
It communicates with a relatively large-volume gear chamber 8 defined by the upper cover 1 and the binion case 9 through. As shown in FIG. 9, the communication passage 98 is provided with a through hole 98a provided vertically in the upper cover 16 and the brush holder so as to communicate the through hole 98a with the two notches 95a, 95a. A narrow groove 98b horizontally provided on the lower surface of the brush holder 89 and a fitting gap 98 between the brush holder 89 and the fitting cylinder part 85.
It consists of c.

The lower end side of the rotating shaft 27 in the electric motor 26 is reduced in diameter in two stages, and the smallest diameter portion 27a is connected to the binion case 9.
It is extended until it substantially penetrates through. Then, the minimum diameter portion 2
A hollow gear shaft 99 is loosely fitted to 7a,
A drive gear 29 that meshes with the first reduction gear 31 is integrally formed in an intermediate portion of the gear shaft 99. Both ends of the gear shaft 99 are reduced in diameter to have approximately the same outer diameter as the intermediate diameter portion 27b at the lower end of the rotating shaft 27, and the upper end thereof is arranged to also serve as the intermediate diameter portion 27b. The installed first bearing 10
It is rotatably supported by the upper cover 1 via 0a. On the other hand, the lower end of the gear shaft 99 is rotatably supported by the pinion case 9 via a second bearing 100b. In addition, the rotating shaft 2
A lock nut 101 is screwed onto the lower end of 7, and by tightening this lock nut 101, the gear shaft 99 is held between the inner rings of the first and second bearings 100a and 100b, and the rotating shaft is rotated. It is pressed against the shoulder of 27, and the thrust force at this time causes both shafts 2? , 99 are integrally connected. In addition, in FIG. 1, 102 is a positioning pin, 103 is a cap, and 104 is a dust plate.

Because of this configuration, when the input shaft 3 rotates relative to the pinion shaft 5, the drive pin 58 is connected to both shafts 3 and 5.
A slider 53 connected to the pinion shaft 5 slides on the pinion shaft 5. At this time, the two drive bins 58 are provided at point-symmetrical positions, and the compression coil spring 55 is used to move the slider 53.
Since the slider 53 is always urged upward, the slider 53 operates smoothly and accurately without play due to twisting or play, and the detection accuracy of the rotary potentiometer 64, which will be described later, is improved.

As the slider 53 slides, the rotary shaft 65 of the rotary potentiometer 64 swings and rotates in the axial direction of the pinion shaft 5, and the slider 53 eventually rotates in accordance with the relative rotation amount of the shafts 3 and 5. The amount of sliding is measured with respect to the rotation angle.

In this way, if the rotary displacement sensor 64 is used, it is easier to seal the lubricating oil than with a sliding displacement sensor, and even an overhung bearing structure can be used.

Further, the above-mentioned rotating shaft 65 has a shaft main body part 65b and an input end part 65a offset from the shaft main body part 65b, and since these are integrally formed by bending the shaft material I, the axial accuracy can be improved. It can be easily removed and manufactured at low cost. Furthermore, in the rotary potentiometer 64, two sliding pieces 74a, 74b and resistors 75a, 75b are assembled electrically independently from each other, and either one of the resistors 75a or 75b
-19 Since the variable resistor @77 is connected so that it can be adjusted from outside the casing 68, it is possible to avoid inadvertent power assist due to erroneous detection, and it is also possible to avoid machining of parts, etc. If a deviation occurs between the two detected values due to an assembly error, zero point adjustment can be easily performed using the variable resistor 77 even after assembly.

Further, in this embodiment, a fitting cylinder part 85 is provided protrudingly on the upper surface of the upper cover 1 which is directly connected to the binion case 9, and the electric motor is connected to the upper cover 1 using the fitting cylinder part 85. 26 are integrally assembled, the number of parts and assembly man-hours can be significantly reduced. Further, since the motor chamber RO communicates with the gear chamber 8 through the communication passage 98, pressure changes due to temperature changes in the motor chamber RO can be reduced, and water and the like can be prevented from entering the motor chamber RO. Furthermore, a hollow gear shaft 99 is fitted onto the rotating shaft 27 of the electric motor 26, and the gear shaft 99 is fixed with a lock nut 101 screwed onto the end of the shaft 20 of the rotating shaft 27.
The first and second bearings 100a and 100b are arranged on both sides and tightened to fix both shafts 27 and 99 without any play in the axial direction.
6 can be reliably transmitted to the drive gear 29 without any play.

Note that the rotary potentiometer of the present invention is applicable not only to electric power steering devices but also to other devices.

Effects of the Invention> As explained above, according to the present invention, a fail-safe function can be provided by a simple structure in which two sliding pieces and a resistor are assembled electrically independently from each other, and the above-mentioned effects can be achieved. By using a variable resistor connected to one of the resistors in the circuit, it is possible to easily adjust the deviation between the two detected values due to errors in machining and assembly of parts, etc., even after assembly. type potentiometer can be provided.

[Brief explanation of the drawing]

FIG. 1 is a side sectional view showing one embodiment of the present invention, and FIG.
) is a cross-sectional view of the input shaft, Figure 2 (5) is a side view of the fitting tube part, Figure 3 is a partially cutaway plan view of the rotary potentiometer mounting part, and Figure 4 is the rotary potentiometer. A cross-sectional view of
Figure 5 (6) is a top view of the ceramic substrate, Figure 5 (B)
5 is a bottom view of the ceramic substrate, FIG. 5 is a bottom view of the rotor, FIG. 6 is an explanatory diagram showing how to make the rotating shaft, FIG. A cross-sectional view showing the opening position, Figure 9 is a cross-sectional view along the ■■ line in Figure 8, and Figure 10 is a cross-sectional view showing the opening position.
The figure is an overall side sectional view of a conventional example, and FIG. 11 is a partially cutaway plan view thereof. In addition, in the drawing, 1 is the upper cover, 3 is the input shaft, 4 is the steering handle shaft, 5 is the pinion shaft, 9 is the pinion case, 10
is a torsion par, 13 is a driven gear, 26 is an electric motor, 2
9 is a drive gear, 51 is a fitting cylinder portion, 53 is a slider, 56
57 is a diagonal hole, 57 is an engagement groove, 58 is a drive pin, 63 is an annular groove, 64 is a rotary potentiometer, 65 is a rotating shaft, 65
74a and 74b are first and second sliding pieces, 75a and 75b are first and second resistors, and 77 is a variable resistor.

Claims (1)

[Claims] First and second sliding pieces are provided electrically independently of each other on a rotor that is fixed to a rotating shaft and can freely rotate within a casing; The movable piece is provided with first and second resistors in sliding contact with each other, and a variable resistor connected to one of these resistors in a circuit so as to be adjustable from outside the casing. Features a rotary potentiometer.