JPH10206251A - Torque detector - Google Patents

Abstract

(57) [Problem] To effectively improve the torque detection accuracy by effectively using a magnetostrictive material for torque detection over substantially the entire circumference thereof. A shaft member (12) extending along an axis (G) and having at least an outer peripheral portion formed of a magnetostrictive material (14), and a pair of opposing portions (A) and (B) on the surface of the magnetostrictive material, separated from each other along the axis. A pair of exciting coils 20A and 20B having cores 18A and 18B disposed at one end close to a pair of opposing portions that are separated from each other by 180 ° about the axis;
It has a pair of detection coils and 24A and 24B arranged between the other ends C and D of the pair of cores on both sides of the magnetostrictive material.
When a torque acts on the shaft, the magnetic flux in the two magnetic flux paths 26A and 26B is changed by the tensile stress and the compressive stress generated in the ± 45 ° direction with respect to the axis on the magnetostrictive material, and this is detected by the detection coils 24A and 24B.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a torque detecting device, and more particularly, to a torque detecting device utilizing torque-magnetic conversion.

[0002]

2. Description of the Related Art As one of torque detecting devices utilizing torque-magnetic conversion, as disclosed in Japanese Patent Application Laid-Open No. Sho 62-203030, for example, a cylinder fixed to the outer peripheral surface of a cylindrical torque transmitting body. -Shaped magnetostrictive tube, and a pair of detection coil poles spaced apart from each other in the axial direction, and an excitation coil arranged at a position corresponding to a vertex of a right-angled isosceles triangle having a base connected to a line connecting the pair of detection coil poles 2. Description of the Related Art A torque detection device including a pole and a housing made of a magnetic material that connects and supports a pair of a detection coil pole and an excitation coil pole is conventionally known.

Generally, when a torque around the axis acts on the shaft, a compressive stress and a tensile stress are generated in the magnetostrictive tube in a direction inclined by ± 45 ° with respect to the axis, and the magnetostrictive effect is generated by these stresses. When the constant is positive, the magnetic permeability in the direction of tensile stress increases and the magnetic permeability in the direction of compressive stress decreases. The increase or decrease of the magnetic permeability is determined by the direction of the torque, and the increase or decrease of the magnetic permeability is determined by the magnitude of the torque.

Therefore, according to the torque detecting device, the induced magnetic field is generated when the magnetostrictive tube is alternately excited by the exciting coil pole, and the direction in which the permeability change due to the torque acting on the shaft is largest, that is, the axis line. ± 45 ° to
Since the change in the magnetic flux of the induction magnetic field in the inclined direction is detected, the magnitude and direction of the torque acting on the shaft can be detected more accurately than when, for example, the change in the magnetic flux in the axial direction is detected. .

[0005]

However, in the conventional torque detecting device as described above, the magnetic permeability change due to the torque is used only for a part of the magnetostrictive material when viewed in the circumferential direction. The change in the magnetic permeability due to the torque at the time is not effectively used, and therefore, there is room for improvement in order to further improve the accuracy of detecting the magnitude and direction of the torque.

The present invention has been made in view of the above-mentioned problems in the conventional torque detecting device in which only a part of the magnetostrictive material is used in the circumferential direction, and a main object of the present invention. Is to further improve the torque detection accuracy by effectively utilizing the magnetostrictive material for the torque detection over substantially the entire circumference.

[0007]

According to the present invention, a main object as described above is to provide a shaft member extending along an axis and having at least an outer peripheral portion formed of a magnetostrictive material; A pair of exciting coils each having a core disposed at one end close to a pair of opposing portions that are spaced apart from each other along the axis and 180 ° apart from each other around the axis; And a pair of detection coils disposed between the other ends of the pair of cores on both sides of the magnetostrictive material (the configuration of claim 1), or at least the outer periphery extending along the axis A shaft member formed of a magnetostrictive material, and a pair of opposing portions on the surface of the magnetostrictive material, the pair of opposing portions being spaced apart from each other along the axis and 180 ° around the axis. A pair of cores located at one end close to the A connecting member extending at least on both sides of the magnetostrictive material and connecting the other ends of the pair of cores, and an exciting coil disposed on at least one of the pair of cores;
This is achieved by a torque detection device (a configuration according to claim 2) including a pair of detection coils disposed on the connection member between the other ends of the pair of cores.

In the configuration according to the first aspect, the pair of cores, the magnetostrictive material, the atmosphere,
First and second magnetic flux paths through the detection coil are defined;
In the configuration of the second aspect, a pair of cores, a magnetostrictive material,
First and second magnetic flux paths through the atmosphere, connections, and sensing coils are defined. When the first and second magnetic flux paths are excited by the excitation coil, an induced electromotive force is generated in the pair of detection coils. In these configurations, when a torque around the axis acts on the shaft to generate a compressive stress and a tensile stress in the direction inclined ± 45 ° with respect to the axis as described above, the direction of the tensile stress is reduced. As the magnetic permeability increases, the magnetic permeability in the direction of the compressive stress decreases, whereby the induced electromotive force of one detection coil increases and the induced electromotive force of the other detection coil decreases. Respectively correspond to the direction and magnitude of the torque.

Also, since the first and second magnetic flux paths extend substantially 180 ° around the axis in the magnetostrictive material, the extending range of the magnetic flux path in the magnetostrictive material is limited. The change in the magnetic permeability of the magnetostrictive material due to the action of the torque on the shaft is more effectively used than in the case of a comparatively small conventional torque detecting device. Therefore, according to the first and second aspects,
The magnitude and direction of the torque acting on the shaft is detected with even higher accuracy.

According to the present invention, in order to effectively achieve the above-mentioned main object, in the structure of claim 1 or 2, the pair of detection coils are provided on both sides of the magnetostrictive material. It is configured to extend along a line connecting the other ends of the cores (the configuration of claim 3).

According to the first or second aspect of the present invention, the change in magnetic flux due to the torque acting on the shaft in the portion of the first and second magnetic flux passages around the magnetostrictive material is most remarkable. Is a direction along a line connecting the other ends of the pair of cores. According to the configuration of the third aspect, the pair of detection coils extend along the line connecting the other ends of the pair of cores on both sides of the magnetostrictive material. A change in the magnetic flux in the second magnetic flux path is most efficiently detected.

Further, according to the present invention, in order to effectively achieve the above-mentioned main object, in the structure of claim 1 or 2, the pair of detection coils are provided on both sides of the magnetostrictive material. It is configured to extend in a direction other than a direction perpendicular to a line connecting the other ends of the cores and along a virtual plane parallel to the axis (the configuration of claim 4).

[0013] In the structure of claim 1 or 2, the direction perpendicular to a line connecting the other ends of the pair of cores on both sides of the magnetostrictive material and along a virtual plane parallel to the axis is equal magnetic potential. If the pair of detection coils extend in a direction other than the direction perpendicular to the line connecting the other ends of the pair of cores and in the direction along the virtual plane, An induced electromotive force is generated due to a magnetic potential difference from the equipotential surfaces at both ends.

These induced electromotive forces are the same when no torque acts on the shaft. However, when torque acts on the shaft, the induced electromotive force of one detection coil increases and the induction electromotive force of the other detection coil increases. The electromotive force decreases, and the increase and decrease of the induced electromotive force correspond to the direction and magnitude of the torque, respectively. Therefore, according to the configuration of claim 4, the magnitude and direction of the torque acting on the shaft are detected based on the increase and decrease and the increase and decrease of the induced electromotive force.

According to the present invention, in order to effectively achieve the above-mentioned main object, in the above-mentioned structure of the first or second aspect, the excitation coil is controlled based on the sum of outputs of the pair of detection coils. The output or the output of the pair of detection coils is configured to be corrected (the configuration of claim 5).

The amount of increase and decrease of the permeability of the magnetostrictive material in the first and second magnetic flux paths due to the torque acting on the shaft regardless of the magnitude and direction of the torque is substantially the same as each other; Therefore, since the amount of increase and decrease of the magnetic flux in the two magnetic flux paths are substantially the same, the first and second magnetic flux paths are excited by the exciting coil unless a disturbance acts on the torque detecting device. The effective value of the sum of the magnetic fluxes generated by this operation is substantially constant, and therefore, the effective value of the sum of the outputs of the pair of detection coils is also substantially constant. In other words, a change in the effective value of the sum of the outputs of the pair of detection coils means a disturbance such as a temperature change.

According to the fifth aspect, the output of the exciting coil or the output of the pair of detection coils is corrected based on the sum of the outputs of the pair of detection coils, so that the influence of disturbance such as a temperature change is eliminated. Therefore, the accuracy of torque detection is further improved as compared with the configuration of the first aspect.

According to the present invention, in order to effectively achieve the above-described main object, in the above-mentioned structure of the first aspect, a feedback is provided around the magnetostrictive material between the pair of exciting coils. A coil is arranged, and the output of the exciting coil or the output of the pair of detection coils is configured to be corrected based on the output of the feedback coil (the configuration of claim 6). The excitation coil is disposed on one of the pair of cores, and a feedback coil is disposed on the other of the pair of cores. Based on an output of the feedback coil, an output of the excitation coil or an output of the pair of detection coils is output. It is configured to be corrected (the configuration of claim 7).

Since the feedback coils of the sixth and seventh aspects detect the induced electromotive force due to the magnetic flux flowing through both the first and second magnetic flux paths, the output of these feedback coils is the same as that of the fifth aspect. It functions similarly to the sum of the outputs of a pair of detection coils. Accordingly, claims 6 and 7
According to the configuration, the torque detection accuracy is further improved as in the case of the fifth aspect, as compared with the case of the first aspect.

[0020]

According to a preferred aspect of the present invention, in the configuration according to any one of claims 1 to 7, the radial interval and the axial interval of the pair of cores are substantially equal. Are configured to be identical to

According to another preferred embodiment of the present invention, in any one of the above-mentioned constitutions, the pair of detection coils are arranged at a position equidistant from the other end of the pair of cores. You.

According to another preferred aspect of the present invention, in the configuration of the first aspect, the pair of exciting coils and the pair of detecting coils are arranged to extend along the axis of the shaft member. .

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Some embodiments of a torque detecting device according to the present invention will be described below in detail with reference to the accompanying drawings.

First Embodiment FIG. 1 is a front view (A) and a side view (B) showing a first embodiment of a torque detecting device according to the present invention, and FIG. 2 shows a magnetostrictive tube of the first embodiment. It is a perspective view (A) and a development view (B).

Referring to FIG. 1, a torque detector 10 includes a substantially cylindrical shaft 12 which fits closely along an axis G.
And includes a substantially cylindrical magnetostrictive tube 14 and a magnetic detector 16 disposed around and in close proximity to the magnetostrictive tube 14. The shaft 12 is formed of a non-magnetic material having a low magnetic permeability, and the magnetostrictive tube 14 is formed of a magnetostrictive material having a positive magnetostriction constant, and these are integrally fitted to each other by shrink fitting.

The magnetic detector 16 includes a pair of cores (legs) 18A and 18B formed of a soft magnetic material. The cores 18A and 18B are arranged close to a pair of opposing portions A and B on the surface of the magnetostrictive tube 14 and extend in the radial direction with respect to the magnetostrictive tube 14. The opposing portions A and B are spaced apart from each other along an axis G and are 180 ° apart from each other about the axis. The radial spacing and the axial spacing of the opposing portions A and B are substantially the same, so that the line segments La and Lb spirally connecting the opposing portions A and B along the surface of the magnetostrictive tube 14 are shown in FIG. As seen in the developed view of FIG.
At an angle. The above configuration is the same for other embodiments described later unless otherwise specified.

In this embodiment, the excitation coils 20A and 20A for exciting the corresponding cores in the same direction (in the opposite direction with respect to the magnetostrictive tube 14) are respectively connected to the cores 18A and 18B.
OB is wound with the same number of turns, and these coils are connected in series with each other. In addition, the magnetic detector 16
Are a pair of cores 22A and 22B formed of a soft magnetic material.
Contains. The cores 22A and 22B are located at the midpoints of the line segments Lc and Ld which spirally connect the ends of the cores 18A and 18B on the side opposite to the magnetostrictive tube 14 substantially in parallel to the surface of the magnetostrictive tube. It extends along Lc and Ld. The detection coils 24A and 24B are wound around the cores 22A and 22B with the same number of turns, respectively. Although not shown in the figure, the cores 18A and 18B and the core 22A,
22B is supported by a housing formed of a non-magnetic material.

Therefore, as shown in FIG. 1B, the core 18A, the portion of the magnetostrictive tube 14 along the line segment La, and the core 18A
B, first magnetic flux path 26A through atmosphere and core 22A
And the second magnetic flux passage 2 passing through the core 18A, the portion along the line segment Lb of the magnetostrictive tube 14, the core 18B, the atmosphere, and the core 22B.
6B, and the detection coils 24A and 24B
Are the first magnetic flux path 26A and the second magnetic flux path 2 respectively.
6B is detected. Excitation coils 20A, 20B
The detection coils 24A and 24B are connected to a control device 28.

As shown in FIG. 3, controller 28 has amplifiers 30A and 30B connected to sense coils 24A and 24B, respectively, the outputs of which are input to summing amplifier 32 and differential amplifier 34. Is done. Further, the control device 28 has an oscillation circuit 36 connected to the exciting coils 20A and 20B, and the oscillation circuit 36 has several K to 100 KH.
A sine wave or pulse high frequency voltage of about z is applied to the excitation coils 20A and 20B.

When the exciting coils 20A and 20B are
6, when the intersecting magnetic flux is given to the first magnetic flux path 26A and the second magnetic flux path 26B, the detection coil 2
Since induced electromotive force corresponding to the change of magnetic flux is generated in 4A and 24B, the voltage of these induced electromotive force is amplified by amplifiers 30A and 30B, respectively. Summing amplifier 3
2 adds and amplifies the outputs of the amplifiers 30A and 30B, and the output is input to an AGC (auto gain control) 38. The differential amplifier 34 differentially amplifies the outputs of the amplifiers 30A and 30B and outputs the result to the effective value conversion circuit 39. The voltage rmsized by the rms circuit 39 indicates the magnitude and direction of the torque by its magnitude and sign, respectively.
The display device 40 receiving the voltage signal displays the magnitude and direction of the torque.

In particular, the gains of the amplifiers 30A and 30B are adjustable, and these gains are adjusted so that the output of the differential amplifier 32 is zero in situations where no torque is acting on the shaft 12, thereby increasing the core. The difference in magnetic resistance between the two magnetic flux paths 26A and 26B due to the difference in clearance between the outer peripheral cylindrical surface of the magnetostrictive tube 14 and the outer circumferential surface of the magnetostrictive tube 14 is corrected. The AGC 38 also controls the sum of the effective values of the outputs of the amplifiers 30A and 30B based on the output from the summing amplifier 32, in other words, the sum of the electromotive forces generated by the magnetic fluxes flowing through the two magnetic flux paths 26A and 26B. The gain of the oscillation circuit 36 is controlled so that the energy always has a substantially constant relationship with the excitation energy applied to the excitation coils 20A and 20B by the oscillation circuit 36.

In this embodiment, two magnetic flux paths 2
Assuming that the magnetic resistances of 6A and 26B are the same and that the leakage flux can be neglected, if the exciting coils 20A and 20B are driven and the cores 18A and 18B are excited in a state where no torque acts on the shaft 12, The magnetic flux flowing through these cores is equally divided into two magnetic flux paths 26A and 26B. Therefore, the induced electromotive force generated in the detection coils 24A and 24B is the same, the output of the differential amplifier 32 becomes 0, and it can be seen that no torque acts on the shaft 12.

On the other hand, as shown in FIG. 4A, when the torque Td acts on the shaft 12, the axis G
When a tensile stress Fdt and a compressive stress Fdc acting in a direction inclined by 45 ° with respect to the magnetostrictive tube 14 act on the magnetostrictive tube 14, the permeability in the direction of the tensile stress Fdt (the direction parallel to the first magnetic flux passage 26A) increases and the compressive stress Fdc increases. Direction (second magnetic flux path 26
(The direction parallel to B) decreases, and the amount of increase or decrease is substantially proportional to the magnitude of the torque Td. As shown in FIG. 4 (B), when the torque Td acts in the opposite direction to the case of FIG. 4 (A), the tensile stress Fdt and the compressive stress Fdc in the direction inclined by 45 ° with respect to the axis G. Figure 4
When acting in the direction opposite to the case of FIG. 4A, the magnetic permeability increases and decreases in a manner opposite to the case of FIG. 4A, and in this case also, the amount of increase or decrease of the magnetic permeability depends on the magnitude of the torque Td. Substantially proportional.

Therefore, according to the first embodiment, the torque T
According to the direction of d, the magnetic permeability of one of the first magnetic flux passage 26A and the second magnetic flux passage 26B increases and the magnetic permeability of the other decreases, and the differential amplifier 34 increases or decreases according to the increase or decrease of the magnetic permeability.
Becomes positive or negative, and the output voltage of the differential amplifier 34 increases or decreases according to the magnitude of the torque Td.
2 can be detected in the direction and the magnitude of the torque Td acting on the second.

According to the first embodiment, the magnetostrictive tube 14
Magnetic flux passage 26A and second magnetic flux passage 26
Since B is inclined at ± 45 ° with respect to the axis G and extends over a range of 180 ° around the axis G, the inclination directions of the two magnetic flux paths are directions other than ± 45 ° with respect to the axis. In this case, the magnetostrictive effect of the magnetostrictive material 14 can be more effectively used than in the conventional structure in which the extension range of the magnetic flux passage is only a part around the axis G, and the torque T
The direction and magnitude of d can be accurately detected.

4A and 4B, the torque is applied to the shaft 12 so that the magnetic permeability of one of the first magnetic flux passage 26A and the second magnetic flux passage 26B is reduced. Since the amount of increase and the amount of decrease in the other magnetic permeability are substantially the same, the total energy of the electromotive force generated by the magnetic flux flowing through the two magnetic flux paths 26A and 26B and the excitation applied to the exciting coils 20A and 20B by the oscillation circuit 36 The change in the deviation from the energy or the change in the ratio between these energies is due to disturbances, such as a change in the magnetic permeability due to a change in temperature.

According to the first embodiment shown, the total energy of the electromotive force generated by the magnetic flux flowing through the two magnetic flux paths 26A and 26B is always substantially equal to the excitation energy applied to the excitation coils 20A and 20B by the oscillation circuit 36. Since the gain of the oscillation circuit 36 is controlled by the AGC 38 so that a constant relationship is established between the torque Td and the direction and magnitude of the torque Td, disturbance components such as a change in magnetic permeability due to a temperature change can be removed. Can be accurately detected.

Second Embodiment FIG. 5 is a front view (A) and a side view (B) showing a torque detection device according to a second embodiment of the present invention, and FIG. 6 shows an electric circuit of the second embodiment. It is a block diagram. In FIGS. 5 and 6, parts corresponding to the parts shown in FIGS. 1 and 3, respectively, are given the same reference numerals as those given in FIGS. 1 and 3. The same applies to other embodiments described later.)

In this embodiment, the magnetic detector 16
Is a pair of legs 18A and 18B which are arranged close to the pair of opposing portions A and B and extend in the radial direction, and a substantially cylindrical shape which extends around the magnetostrictive tube 14 concentrically with the axis G. Connection member 18C for integrally connecting legs 18A and 18B
And The connecting member 18C is also formed of a soft magnetic material, and the connecting member 18C is provided with two pairs of grooves 40 on both sides of the magnetostrictive tube 14. Detection coils 24A and 2
4B is wound around the portion between these grooves 40 and extends along the line segments Lc and Ld, respectively. The exciting coil 20 is wound around the leg 18A, but the exciting coil is not wound around the leg 18B.

This embodiment is otherwise the same as the first embodiment. Only the leg 18A is excited by the exciting coil 20, and the first magnetic flux passage 26A and the second magnetic flux passage 26A are formed. 26B operates in the same manner as the first embodiment except that the portion between the outer ends of the legs 18A and 18B is defined by the connecting member 18C. The direction and magnitude of the torque Td acting on the shaft 12 can be accurately detected by removing disturbance components such as changes in the torque.

According to this embodiment, the connection member 18
C may also function as a substantially cylindrical housing, and the legs 18A and 18B may be fixed to the inner surface of the connecting member 18C by, for example, screws, so that the case of the first embodiment is compared. The number of parts and cost can be reduced.

Third and Fourth Embodiment FIG. 7 is a front view (A) and a side view (B) showing a third embodiment of a torque detecting device according to the present invention, and FIG. 8 is an electric diagram of a third embodiment. FIG. 9 is a block diagram showing a circuit, and FIG. 9 is a front view (A) showing a fourth embodiment of the torque detector according to the present invention.
FIG. 10 is a block diagram showing an electric circuit according to the fourth embodiment.

The third embodiment shown in FIGS. 7 and 8 corresponds to the first embodiment. In this embodiment, the excitation coils 20A, 20B and the detection coils 24A,
A feedback coil 42 is provided in addition to the legs 18A and 18B.
Is wound around the magnetostrictive tube 14. On the other hand, the fourth embodiment shown in FIGS. 9 and 10 corresponds to the second embodiment, and in this embodiment,
An excitation coil 20 is wound around A, and a feedback coil 42 is wound around the leg 18B.

As shown in FIGS. 8 and 10,
The control device 28 of these embodiments is not provided with the summing amplifier 32 of the first and second embodiments,
The voltage of the induced electromotive force generated in the feedback coil 42 is amplified by the amplifier 44, and the output of the amplifier 44 is
Input to C38. In the feedback coil 42, an electromotive force equal to the sum of the electromotive force generated by the magnetic flux flowing through the first magnetic flux path 26A and the electromotive force generated by the magnetic flux flowing through the second magnetic flux path 26B is generated.
The GC 38 also controls the gain of the oscillation circuit 36 so that the total energy of the electromotive force generated by the magnetic flux flowing through the two magnetic flux paths 26A and 26B substantially matches the excitation energy given to the excitation coil 20 by the oscillation circuit 36.

The third and fourth embodiments are otherwise formed similarly to the first and second embodiments, respectively, and thus operate similarly to the first and second embodiments. Therefore, in these embodiments as well, it is possible to accurately detect the direction and magnitude of the torque Td acting on the shaft 12 by removing disturbance components such as a change in magnetic permeability due to a temperature change.

Fifth Embodiment FIG. 11 is a front view (A) and a side view (B) showing a fifth embodiment of the torque detector according to the present invention, and FIG. 12 is a sixth embodiment of the torque detector according to the present invention. FIGS. 13A and 13B are a front view (A) and a side view (B) showing the embodiment. FIGS. It is a development view showing the magnetostrictive tube of an embodiment.

In the fifth embodiment shown in FIG. 11, the pair of cores 22A and 22B extend parallel to the axis G, so that the detection coils 24A and 24B also extend parallel to the axis G. doing. On the other hand, in the sixth embodiment shown in FIG. 12, the pair of cores 22A and 22B
And extends in a direction parallel to an imaginary plane (not shown) passing through the pair of opposed portions A and B and perpendicular to the line segments La and Lb, respectively, whereby the detection coils 24A and 24B also become the line segments La and Lb, respectively. It extends in a direction perpendicular to Lb. The other embodiments are formed similarly to the first embodiment in other respects.

When the residual tensile stress in the circumferential and axial directions due to shrink fitting of the magnetostrictive tube 14 is small and no torque acts on the shaft 12, as shown in FIG. When the exciting coils 20A and 20B are driven, the cores become equal because the equi-potential surfaces Pc and Pd of the first magnetic flux path 26A and the second magnetic flux path 26B around the axis are perpendicular to the line segments Lc and Lc. An electromotive force is generated in the detection coils 24A and 24B by the excitation difference from the equi-magnetic planes Pc and Pd at both ends of 22A and 22B, and the electromotive forces are substantially equal to each other.

On the other hand, when the torque Td acts on the shaft 12 as shown in FIG. 4B, for example, the magnetic permeability of the magnetostrictive tube 14 increases in the direction of the tensile stress Fdt due to the torque Td, and the compressive stress Fdc 13B, the magnetic flux in the first magnetic flux passage 26A increases, but the magnetic flux in the second magnetic flux passage 26B decreases, as shown in FIG. 13B. Therefore, the electromotive force generated in the detection coil 24A increases, but the electromotive force generated in the detection coil 24B decreases. The difference is proportional to the magnitude of the torque Td acting on the shaft 12, and the sign of the difference is It corresponds to the direction of the acting torque Td.

Therefore, in these embodiments, as in the other embodiments described above, the torque T acting on the shaft 12 by removing disturbance components such as a change in magnetic permeability due to a temperature change is removed.
The direction and magnitude of d can be accurately detected. From the first, fifth, and sixth embodiments, it is understood that the two detection coils 24A and 24B only need to extend in directions other than the direction perpendicular to the line segments Lc and Ld, respectively.

Although the present invention has been described in detail with reference to specific embodiments, the present invention is not limited to the above-described embodiments, and various other embodiments may be included within the scope of the present invention. It will be clear to those skilled in the art that is possible.

For example, in each of the above embodiments, the pair of legs 18A and 18B extend perpendicular to the axis G of the magnetostrictive tube 14, but these legs extend in the axial direction of the magnetostrictive tube 14. It may extend, or may extend along a straight line connecting the opposing portions A and B linearly.

In each of the above embodiments, the shaft 12
Is formed of a non-magnetic material, but the shaft is made of a magnetostrictive material having a negative magnetostriction constant so that the same reverse phenomenon as that of the magnetostrictive effect in the magnetostrictive tube 14 also occurs in the shaft. It may be formed, and in that case, the torque detection sensitivity and the detection accuracy can be further improved as compared with the case of each of the illustrated embodiments.

In the second and fourth embodiments described above, an exciting coil may be wound around the leg 18B. In the third and fourth embodiments, the detection coils 24A and 24B May be set in any direction other than the direction perpendicular to the line segments Lc and Ld, respectively, and the feedback coil 42 may be wound around the leg 18B in the fourth embodiment.

In each of the above-described embodiments, the detection coils 24A and 24B are provided at the midpoints of the line segments Lc and Ld, respectively.
Alternatively, as long as the position is substantially equidistant from the other end of 18B, it may be located at the other end of the leg 18A or the other end of the 18B from the illustrated position, or the axis G may be located more than the illustrated position. May be located at a position closer to or farther from.

Further, in each of the above-described embodiments, the total energy of the electromotive force generated by the magnetic flux flowing through the two magnetic flux paths 26A and 26B is supplied to the exciting coil 20A by the oscillation circuit 36.
The gain of the oscillating circuit 36 is controlled by the AGC 38 so as to always have a substantially constant relationship with the excitation energy given to the 20B or 20B. By controlling the gain of the differential amplifier 34 based on the above, the total energy of the electromotive force generated by the magnetic flux flowing through the two magnetic flux paths 26A and 26B is always equal to the excitation energy given to the excitation coils 20A and 20B or 20 by the oscillation circuit 36. It may be controlled to make a substantially constant relationship.

[0057]

As is apparent from the above description, in the configuration of the first aspect, the first and second magnetic flux paths passing through the pair of cores, the magnetostrictive material, the atmosphere, and the detection coil are defined. According to the configuration of the second aspect, the first and second magnetic flux paths passing through the pair of cores, the magnetostrictive material, the atmosphere, the connection portion, and the detection coil are defined, and the first and second magnetic flux paths are Since the magnetostrictive material extends substantially 180 degrees around the axis, the magnetic flux passage in the magnetostrictive material has a relatively small extension range as compared with the conventional torque detecting device. Therefore, the change in the magnetic permeability of the magnetostrictive material due to the torque acting on the shaft can be effectively used. Therefore, according to the first and second aspects, the magnitude and direction of the torque acting on the shaft can be further reduced. Detection can be performed with higher accuracy.

According to the third aspect of the present invention, since the pair of detection coils extend along the line connecting the other ends of the pair of cores on both sides of the magnetostrictive material, torque acts on the shaft. , The change in the magnetic flux in the first and second magnetic flux paths can be detected most efficiently.

According to the fourth aspect of the present invention, the pair of detection coils act on the shaft as the increase and decrease of the induced electromotive force generated due to the difference in magnetic potential from the equipotential surfaces at both ends thereof. The magnitude and direction of the torque can be detected.

According to the configuration of claim 5, the output of the excitation coil or the output of the pair of detection coils is corrected based on the sum of the outputs of the pair of detection coils. According to the configuration of claim 7, the output of the excitation coil or the output of the pair of detection coils is corrected based on the output of the feedback coil disposed around the magnetostrictive material between the excitation coils. Since the excitation coil is arranged and the output of the excitation coil or the output of the pair of detection coils is corrected based on the output of the feedback coil arranged on the other of the pair of cores, it is possible to eliminate the influence of disturbance such as temperature change. Therefore, according to these configurations, the torque detection accuracy can be further improved as compared with the configuration of the first or second aspect.

[Brief description of the drawings]

FIG. 1 is a front view (A) and a side view (B) showing a first embodiment of a torque detection device according to the present invention.

FIG. 2 is a perspective view (A) and a developed view (B) showing the magnetostrictive tube of the first embodiment.

FIG. 3 is a block diagram illustrating an electric circuit according to the first embodiment.

FIG. 4 is a vector diagram showing stress generated in a magnetostrictive tube when a torque acts on a shaft.

FIG. 5 is a front view (A) and a side view (B) showing a second embodiment of the torque detecting device according to the present invention.

FIG. 6 is a block diagram illustrating an electric circuit according to a second embodiment.

FIG. 7 is a front view (A) and a side view (B) showing a third embodiment of the torque detecting device according to the present invention.

FIG. 8 is a block diagram illustrating an electric circuit according to a third embodiment.

FIG. 9 is a front view (A) and a side view (B) showing a fourth embodiment of the torque detection device according to the present invention.

FIG. 10 is a block diagram illustrating an electric circuit according to a fourth embodiment.

FIG. 11 is a front view (A) and a side view (B) showing a fifth embodiment of the torque detection device according to the present invention.

FIG. 12 is a front view (A) and a side view (B) showing a sixth embodiment of the torque detection device according to the present invention.

FIG. 13 is a development view showing the magnetostrictive tubes according to the fifth and sixth embodiments for a case where torque is not acting on the shaft (A) and a case where torque is acting on the shaft (B).

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Torque detection device 12 ... Shaft 14 ... Magnetostrictive tube 16 ... Magnetic detector 18A, 18B ... Leg (core) 20, 20A, 20B ... Detection coil 24A, 24B ... Detection coil 26A4, 26B ... Magnetic flux path 28 ... Control device

Claims (7)

[Claims] A shaft member extending along an axis and having at least an outer peripheral portion formed of a magnetostrictive material; and a pair of opposing portions on the surface of the magnetostrictive material, the shaft member being spaced apart from each other along the axis, and Between a pair of exciting coils having a core disposed at one end close to a pair of opposing portions separated from each other by 180 ° around an axis, and between the other ends of the pair of cores on both sides of the magnetostrictive material And a pair of detection coils disposed in the torque detection device. 2. A shaft member extending along an axis and having at least an outer peripheral portion formed of a magnetostrictive material, and a pair of opposing portions on the surface of the magnetostrictive material, the shaft member being spaced apart from each other along the axis, and A pair of cores arranged at one end close to a pair of opposing portions 180 ° apart from each other around an axis, and extend at least on both sides of the magnetostrictive material and connect the other ends of the pair of cores. A torque detecting device comprising: a connecting member; an exciting coil disposed on at least one of the pair of cores; and a pair of detecting coils disposed on the connecting member between the other ends of the pair of cores. 3. The torque detection device according to claim 1, wherein the pair of detection coils extend along a line connecting the other ends of the pair of cores on both sides of the magnetostrictive material. A torque detecting device characterized by the above-mentioned. 4. The torque detecting device according to claim 1, wherein the pair of detecting coils are in directions other than a direction perpendicular to a line connecting the other ends of the pair of cores on both sides of the magnetostrictive material. And extending in a direction along a virtual plane parallel to the axis. 5. The torque detecting device according to claim 1, wherein an output of said exciting coil or an output of said pair of detecting coils is corrected based on a sum of outputs of said pair of detecting coils. Torque detector. 6. A torque detecting device according to claim 1, wherein a feedback coil is arranged around said magnetostrictive material between said pair of exciting coils, and an output of said exciting coil is based on an output of said feedback coil. Alternatively, the output of the pair of detection coils is corrected. 7. The torque detecting device according to claim 2, wherein the exciting coil is arranged on one of the pair of cores, and a feedback coil is arranged on the other of the pair of cores.
An output of the excitation coil or an output of the pair of detection coils is corrected based on an output of the feedback coil.