CN112050979A

CN112050979A - Torque detection sensor, power transmission device, and robot

Info

Publication number: CN112050979A
Application number: CN202010498944.1A
Authority: CN
Inventors: 髙木大辅; 羽泉乔平; 坪根太平; 伊凡·哥得勒
Original assignee: Nidec Shimpo Corp
Current assignee: Nidec Drive Technology Corp
Priority date: 2019-06-06
Filing date: 2020-06-04
Publication date: 2020-12-08
Anticipated expiration: 2040-06-04
Also published as: CN112050979B; CN115112277A

Abstract

The invention provides a torque detection sensor, a power transmission device and a robot, which can detect torque applied to a circular body with high precision and can be applied to a small-diameter circular body. The torque detection sensor detects a torque applied to the circular body, and includes a substrate having a conductor layer. The conductor layer includes a resistive line pattern. The resistance line pattern includes an arc-shaped or annular pattern, and is formed by arranging a plurality of resistance lines inclined to one side of the circumferential direction with respect to the radial direction of the circular body in the circumferential direction and connecting the resistance lines in series.

Description

Torque detection sensor, power transmission device, and robot

Technical Field

The invention relates to a torque detection sensor, a power transmission device, and a robot.

Background

In recent years, there has been a rapid increase in demand for speed reducers mounted on joints of robots (robot). Conventional speed reducers are described in, for example, japanese patent laid-open nos. 2000-131160 and 2005-69401. In these publications, a strain gauge is attached to a gear that rotates at a reduced rotation speed. The torque applied to the gear can thereby be detected.

Disclosure of Invention

[ problems to be solved by the invention ]

However, in the structure of the above publication, strain gauges are attached discretely at several positions in the circumferential direction of the gear. The torque detected by each strain gauge is a torque of a local part of the gear. With this structure, it is difficult to detect the torque applied to the entire periphery of the gear with high accuracy.

Therefore, it is also conceivable to attach the strain gauge over a wide range (for example, the entire circumference) in the circumferential direction of the gear. However, this structure is difficult to apply to a small-diameter gear.

The invention provides a torque detection sensor which can detect torque applied to a circular body with high precision and is also applicable to a small-diameter circular body.

[ means for solving problems ]

An aspect of the present application provides a torque detection sensor that detects a torque applied to a circular body, and includes a substrate having a conductor layer. The conductor layer contains a pattern of resistive lines. The resistive line pattern includes: the circular arc-shaped or annular pattern is formed by arranging a plurality of resistance wires inclined towards one side of the circumferential direction relative to the radial direction of the circular body along the circumferential direction and connecting the resistance wires in series.

[ Effect of the invention ]

According to an aspect of the present invention, there is provided a torque detection sensor that can detect torque applied to a circular body with high accuracy and that can be applied to a small-diameter circular body.

Drawings

Fig. 1 is a longitudinal sectional view of a power transmission device of a first embodiment.

Fig. 2 is a cross-sectional view of the power transmission device of the first embodiment.

Fig. 3 is a plan view of the torque detection sensor of the first embodiment.

Fig. 4 is a rear view of the torque detection sensor according to the first embodiment.

Fig. 5 is a circuit diagram of a Wheatstone bridge circuit (Wheatstone bridge circuit) according to the first embodiment.

Fig. 6 is a plan view of a torque detection sensor of the second embodiment.

Fig. 7 is a rear view of the torque detection sensor according to the second embodiment.

Fig. 8 is a plan view of a torque detection sensor of the third embodiment.

Fig. 9 is a rear view of a torque detection sensor according to a third embodiment.

Fig. 10 is a plan view of a torque detection sensor of the fourth embodiment.

Fig. 11 is a rear view of a torque detection sensor according to a fourth embodiment.

Fig. 12 is a plan view of a torque detection sensor of the fifth embodiment.

Fig. 13 is a rear view of a torque detection sensor according to a fifth embodiment.

Fig. 14 is a plan view of a torque detection sensor of the sixth embodiment.

Fig. 15 is an enlarged view of the resistance line pattern of the sixth embodiment.

Fig. 16 is an enlarged view of the resistance line pattern of the sixth embodiment.

Fig. 17 is a plan view of a torque detection sensor according to a modification of the sixth embodiment.

Fig. 18 is a plan view of a torque detection sensor of the seventh embodiment.

Fig. 19 is a sectional view of a torque detection sensor of the seventh embodiment.

Fig. 20 is a sectional view of a torque detection sensor according to an eighth embodiment.

Fig. 21 is a sectional view of a torque detection sensor of the ninth embodiment.

Fig. 22 is a sectional view of a torque detection sensor according to a modification of the seventh to ninth embodiments.

Fig. 23 is a plan view of a torque detection sensor of the tenth embodiment.

Fig. 24 is a plan view of a torque detection sensor of the tenth embodiment.

Fig. 25 is a plan view of a part of the torque detection sensor of the tenth embodiment viewed in the axial direction.

Fig. 26 is a graph showing a relationship between a tilt angle and an error component of the torque detection sensor according to the tenth embodiment.

Fig. 27 is a graph showing a tilt angle at which an error component of the torque detection sensor according to the tenth embodiment becomes minimum.

Fig. 28 is a graph showing a relationship between a tilt angle and an error component in the case where rr < θ θ of the torque detection sensor according to the tenth embodiment.

[ description of symbols ]

1: power transmission device

9: center shaft

10: internal gear

11: internal tooth

20: flexible gear

21: cylindrical part

22: flat plate part

23: external tooth

30: wave generator

31: cam wheel

32: flexible bearing

40: torque detection sensor

41: substrate

42: wheatstone bridge circuit

43: signal processing circuit

45: anchoring layer

221: diaphragm part

222: thick wall part

411: body part

412: flap part

Q: imaginary straight line

L1-L4: conductive layer

L1: first conductor layer

L2: second conductor layer

R1-R21: resistance line pattern

Ra: a first fixed resistor

Rb: second fixed resistor

rr: strain in radial direction

θ θ: strain in circumferential direction

V: voltage meter

r 1-r 21: resistance wire

ra1, ra2, rb1, rb2, rc1, rc 2: a folded part

ra 11: first slow bending part

ra 12: second slow bending part

S2: imaginary straight line

α: inclination angle

Detailed Description

Hereinafter, exemplary embodiments of the present application will be described with reference to the drawings. In the present application, a direction parallel to the central axis of the power transmission device is referred to as an "axial direction", a direction perpendicular to the central axis of the power transmission device is referred to as a "radial direction", and a direction along an arc centered on the central axis of the power transmission device is referred to as a "circumferential direction". However, the "parallel direction" also includes a substantially parallel direction. The "orthogonal direction" also includes a substantially orthogonal direction.

< 1. first embodiment >

< 1-1. construction of Power Transmission device

Fig. 1 is a longitudinal sectional view of a power transmission device 1 of the first embodiment. Fig. 2 is a cross-sectional view of the power transmission device 1 viewed from a-a position of fig. 1. The power transmission device 1 is a device that: the rotational motion of a first rotational speed obtained from a motor is transmitted to a rear stage while being decelerated to a second rotational speed lower than the first rotational speed. The power transmission device 1 is incorporated into a joint of a robot together with a motor, for example, and used. However, the power transmission device of the present invention may be used for other devices such as auxiliary clothing (assist unit), unmanned transport vehicle, and the like.

As shown in fig. 1 and 2, the power transmission device 1 of the present embodiment includes an internal gear (internal gear)10, a flexible gear (flex gear)20, a wave generator 30, and a torque detection sensor 40.

The internal gear 10 is an annular gear having a plurality of internal teeth 11 on an inner peripheral surface. The internal gear 10 is fixed to a housing of the device on which the power transmission device 1 is mounted by, for example, screwing. The internal gear 10 is disposed coaxially with the central shaft 9. The internal gear 10 is located radially outward of a cylindrical portion 21 of the flexible gear 20, which will be described later. The rigidity of the internal gear 10 is much higher than that of the cylindrical portion 21 of the flexible gear 20. Therefore, the internal gear 10 can be substantially regarded as a rigid body. The internal gear 10 has a cylindrical inner peripheral surface. The plurality of internal teeth 11 are arranged at a constant pitch in the circumferential direction on the inner peripheral surface. Each internal tooth 11 protrudes inward in the radial direction.

The flexible gear 20 is an annular gear having flexibility. The flexible gear 20 is rotatably supported centering on the center shaft 9. The flexible gear 20 is an example of the "circular body" of the present invention.

The flexible gear 20 of the present embodiment includes a cylindrical portion 21 and a flat plate portion 22. The cylindrical portion 21 extends in a cylindrical shape in the axial direction around the center axis 9. The axial tip of the cylindrical portion 21 is located radially outward of the wave generator 30 and radially inward of the internal gear 10. The cylindrical portion 21 is flexible and thus deformable in the radial direction. In particular, the distal end portion of the cylindrical portion 21 located radially inward of the internal gear 10 is a free end, and thus can be displaced radially more than the other portions.

The compliant gear 20 has a plurality of external teeth 23. The plurality of external teeth 23 are arranged at a constant pitch in the circumferential direction on the outer peripheral surface near the axial distal end portion of the cylindrical portion 21. Each external tooth 23 protrudes outward in the radial direction. The number of internal teeth 11 of the internal gear 10 is slightly different from the number of external teeth 23 of the flexible gear 20.

The flat plate portion 22 has a diaphragm (diaphragm) portion 221 and a thick portion 222. The diaphragm portion 221 extends radially outward from the axial proximal end of the cylindrical portion 21 in a flat plate shape and extends in an annular shape around the central axis 9. The diaphragm portion 221 is slightly flexible in the axial direction. The thick portion 222 is an annular portion located radially outward of the diaphragm portion 221. The thickness of the thick portion 222 in the axial direction is greater than the thickness of the diaphragm portion 221 in the axial direction. The thick portion 222 is fixed to a component to be driven of the device on which the power transmission device 1 is mounted, for example, by screwing.

The wave generator 30 is a mechanism that generates periodic flexural deformation in the cylindrical portion 21 of the flexible gear 20. The wave generator 30 has a cam 31 and a flexible bearing 32. The cam 31 is rotatably supported about the center shaft 9. The cam 31 has an elliptical outer peripheral surface as viewed in the axial direction. The flexible bearing 32 is interposed between the outer peripheral surface of the cam 31 and the inner peripheral surface of the cylindrical portion 21 of the flexible gear 20. Therefore, the cam 31 and the cylindrical portion 21 can rotate at different rotation speeds.

The inner race of the flexible bearing 32 contacts the outer peripheral surface of the cam 31. The outer ring of the flexible bearing 32 contacts the inner peripheral surface of the flexible gear 20. Accordingly, the cylindrical portion 21 of the flexible gear 20 is deformed into an elliptical shape along the outer peripheral surface of the cam 31. As a result, the external teeth 23 of the flexible gear 20 mesh with the internal teeth 11 of the internal gear 10 at two positions corresponding to both ends of the major axis of the ellipse. At other positions in the circumferential direction, the external teeth 23 are not meshed with the internal teeth 11.

The cam 31 is directly connected to the motor, or is connected to the motor via another power transmission mechanism. When the motor is driven, the cam 31 rotates around the center shaft 9 at a first rotational speed. Thereby, the major axis of the ellipse of the flexible gear 20 is also rotated at the first rotational speed. Then, the meshing position of the external teeth 23 with the internal teeth 11 also changes in the circumferential direction at the first rotation speed. As described above, the number of internal teeth 11 of the internal gear 10 slightly differs from the number of external teeth 23 of the flexible gear 20. Due to the difference in the number of teeth, the meshing position of the external teeth 23 with the internal teeth 11 slightly changes in the circumferential direction per one rotation of the cam 31. As a result, the flexible gear 20 rotates about the central shaft 9 with respect to the internal gear 10 at the second rotational speed lower than the first rotational speed. Thus, a rotational movement of the reduced second rotational speed can be derived from the flexspline 20.

< 1-2 > about torque detecting sensor

The torque detection sensor 40 is a sensor that detects a circumferential torque applied to the flexible gear 20. As shown in fig. 1, in the present embodiment, the torque detection sensor 40 is fixed to the circular surface of the disc-shaped diaphragm portion 221.

Fig. 3 is a plan view of the torque detection sensor 40 viewed in the axial direction. Fig. 4 is a rear view of the torque detection sensor 40 viewed in the axial direction. As shown in fig. 3 and 4, the torque detection sensor 40 includes a substrate 41. The substrate 41 of the present embodiment is a double-sided flexible substrate whose both sides are flexibly deformable. The base plate 41 includes an annular main body 411 centered on the central axis 9, and a flap (flap) portion 412 protruding radially outward from the main body 411. The substrate 41 has a first conductive layer L1 and a second conductive layer L2. The first conductor layer L1 of the present embodiment is a surface conductor layer located on one end surface (front surface) of the substrate 41 in the axial direction. The second conductor layer L2 of the present embodiment is a rear surface conductor layer located on the other axial end surface (rear surface) of the substrate 41.

As shown in fig. 3, the first conductor layer L1 includes a first resistance line pattern R1 and a second resistance line pattern R2. As will be described later, the first resistance line pattern R1 and the second resistance line pattern R2 are incorporated into the wheatstone bridge circuit 42. In other words, the wheatstone bridge circuit 42 is mounted on the surface of the body 411. Further, the signal processing circuit 43 is mounted on the flap portion 412.

The first resistance line pattern R1 is a pattern in which one conductor is bent and extends in the circumferential direction, and is entirely arc-shaped or annular. In the present embodiment, the first resistance line pattern R1 is provided in a range of about 360 ° around the center axis 9. As for the material of the first resistance line pattern R1, for example, copper or an alloy containing copper may be used. The first resistance line pattern R1 includes a plurality of first resistance lines R1. The plurality of first resistance wires r1 are arranged in a substantially parallel posture at equal intervals in the circumferential direction. In the first resistance line pattern R1, the circumferentially adjacent first resistance lines R1 are alternately connected to each other on one side and the other side in the radial direction, and are connected in series as a whole. Each of the first resistance lines r1 is inclined to one side in the circumferential direction with respect to the radial direction of the flexible gear 20 when viewed from one side in the axial direction of the substrate 41. The first resistance line r1 is inclined at a certain angle with respect to the radial direction, for example, to one side in the circumferential direction. The angle of inclination of the first resistance line r1 with respect to the radial direction is, for example, 45 °.

The second resistance line pattern R2 is a pattern in which one conductor is bent and extends in the circumferential direction, and is entirely arc-shaped or annular. In the present embodiment, the second resistance line pattern R2 is provided in a range of about 360 ° around the center axis 9. As for the material of the second resistance line pattern R2, for example, copper or an alloy containing copper may be used. The second resistance line pattern R2 is located more radially inward than the first resistance line pattern R1. That is, the first resistance line pattern R1 and the second resistance line pattern R2 are disposed at positions that do not overlap with each other. The second resistance line pattern R2 includes a plurality of second resistance lines R2. The plurality of second resistance wires r2 are arranged in a substantially parallel posture at equal intervals in the circumferential direction. In the second resistance line pattern R2, the circumferentially adjacent second resistance lines R2 are alternately connected to each other on one side and the other side in the radial direction, and are connected in series as a whole. When viewed from one side of the axial direction of the substrate 41, each second resistance line r2 is inclined to the other side in the circumferential direction with respect to the radial direction of the flexible gear 20. The second resistance line r2 is inclined at an angle of, for example, -45 ° with respect to the radial direction.

Fig. 5 is a circuit diagram of the wheatstone bridge circuit 42 including the first resistance line pattern R1 and the second resistance line pattern R2. As shown in fig. 5, the wheatstone bridge circuit 42 of the present embodiment includes a first resistance line pattern R1, a second resistance line pattern R2, a first fixed resistance Ra, and a second fixed resistance Rb. The first resistance line pattern R1 is connected in series with the second resistance line pattern R2. The first fixed resistor Ra and the second fixed resistor Rb are connected in series. In addition, between the + pole and the-pole of the power supply voltage, the columns of the two resistance line patterns R1, R2 are connected in parallel with the columns of the two fixed resistances Ra, Rb. The midpoint M1 of the first and second resistance line patterns R1 and R2 and the midpoint M2 of the first and second fixed resistors Ra and Rb are connected to the voltmeter V.

The respective resistance values of the first resistance line pattern R1 and the second resistance line pattern R2 vary according to the torque applied to the flexible gear 20. For example, when a torque is applied to the flexible gear 20 toward one side in the circumferential direction about the central axis 9 as viewed from one side in the axial direction, the resistance value of the first resistance line pattern R1 decreases, and the resistance value of the second resistance line pattern R2 increases. On the other hand, when a torque is applied to the flexible gear 20 toward the other side in the circumferential direction about the central axis 9 as viewed from one side in the axial direction, the resistance value of the first resistance line pattern R1 increases, and the resistance value of the second resistance line pattern R2 decreases. Thus, the first resistance line pattern R1 and the second resistance line pattern R2 show mutually opposite resistance value changes with respect to the torque.

Further, when the respective resistance values of the first resistance line pattern R1 and the second resistance line pattern R2 change, the potential difference between the midpoint M1 of the first resistance line pattern R1 and the second resistance line pattern R2 and the midpoint M2 of the first fixed resistance Ra and the second fixed resistance Rb changes, and thus the measurement value of the voltmeter V changes. Therefore, the direction and magnitude of the torque applied to the flexible gear 20 can be detected based on the measurement value of the voltmeter V.

The signal processing circuit 43 is a circuit for detecting the torque applied to the flexible gear 20 based on a potential difference signal between the midpoint M1 and the midpoint M2 measured by the voltmeter V. In other words, the signal processing circuit 43 detects the torque applied to the flexible gear 20 based on the output signal of the wheatstone bridge circuit 42. The wheatstone bridge circuit 42 including the first resistance line pattern R1 and the second resistance line pattern R2 is electrically connected to the signal processing circuit 43. The signal processing circuit 43 includes, for example, an amplifier that amplifies the potential difference between the middle points M1 and M2, or a circuit that calculates the direction and magnitude of torque based on the amplified electric signal. The detected torque is output to an external device connected to the signal processing circuit 43 by wire or wirelessly.

The torque detection sensor 40 is fixed to the diaphragm portion 221 of the flexible gear 20 by, for example, a double-sided tape. Specifically, the front surface of the diaphragm portion 221 and the back surface of the substrate 41 are fixed via a double-sided tape. The double-sided tape is obtained by molding a material having adhesive force into a tape shape and curing the tape to such an extent that the shape can be maintained. When such a double-sided tape is used, the fixing operation of the torque detection sensor 40 to the diaphragm portion 221 is facilitated compared to the case of using an adhesive having fluidity. Further, the variation of the fixing work by the worker can be reduced.

In order to transmit the deformation of the diaphragm portion 221 to the torque detection sensor 40 with high accuracy, the double-sided tape is preferably formed of an adhesive material alone without a base film (base film).

Also, as shown in fig. 3, the first conductor layer L1 includes a third resistance line pattern R3. The third resistance line pattern R3 is mounted on the surface of the body portion 411 together with the first and second resistance line patterns R1 and R2. The third resistance line pattern R3 is electrically connected to the signal processing circuit 43. As for the material of the third resistance line pattern R3, for example, the same copper or copper-containing alloy as the first resistance line pattern R1 and the second resistance line pattern R2 may be used.

The third resistance line pattern R3 is a pattern extending in an arc shape or an annular shape along the circumferential direction of the flexible gear 20. Therefore, the variation in the resistance value of the third resistance line pattern R3 due to the torque in the circumferential direction is extremely small. Therefore, the change in the resistance value of the third resistance line pattern R3 due to temperature becomes dominant. Therefore, by measuring the resistance value of the third resistance line pattern R3, a signal reflecting the temperature of the flexible gear 20 or the ambient temperature can be obtained.

The signal processing circuit 43 corrects the signal output from the wheatstone bridge circuit 42 including the first resistance line pattern R1 and the second resistance line pattern R2 by the resistance value of the third resistance line pattern R3. Specifically, the value of the signal output from the wheatstone bridge circuit 42 is increased or decreased in a direction in which the change due to temperature is eliminated. Next, a torque is detected based on the corrected output signal. Thus, the torque applied to the flexible gear 20 can be detected with high accuracy by using inexpensive copper or an alloy containing copper while suppressing the influence of temperature change.

As shown in fig. 4, the second conductor layer L2 includes a fourth resistance line pattern R4 and a fifth resistance line pattern R5 as patterns for detecting thrust strain. The fourth resistance line pattern R4 and the fifth resistance line pattern R5 are electrically connected to the signal processing circuit 43. As for the material of the fourth resistance line pattern R4 and the fifth resistance line pattern R5, for example, copper or an alloy containing copper may be used.

The fourth resistance line pattern R4 is a pattern in which one conductor is bent and extends in the circumferential direction, and is entirely arc-shaped or annular. In the present embodiment, the fourth resistance line pattern R4 is provided in a range of about 360 ° around the center axis 9. The fourth resistance line pattern R4 is located at a position axially overlapping the first resistance line pattern R1. The fourth resistance line pattern R4 includes a plurality of fourth resistance lines R4. The plurality of fourth resistance wires r4 are arranged in a substantially parallel posture at equal intervals in the circumferential direction. In the fourth resistance line pattern R4, the circumferentially adjacent fourth resistance lines R4 are alternately connected to each other on one side and the other side in the radial direction, and are connected in series as a whole. Each fourth resistance line r4 extends in the radial direction of the flexible gear 20.

The fifth resistance line pattern R5 is a pattern in which one conductor is bent and extends in the circumferential direction, and is entirely arc-shaped or annular. In the present embodiment, the fifth resistance line pattern R5 is provided in a range of about 360 ° around the center axis 9. The fifth resistance line pattern R5 is located more radially inward than the fourth resistance line pattern R4. Specifically, the fifth resistance line pattern R5 is located at a position that overlaps the second resistance line pattern R2 in the axial direction. The fifth resistance line pattern R5 includes a plurality of fifth resistance lines R5. The fifth resistance lines r5 are arranged substantially parallel to each other at equal intervals in the circumferential direction. In the fifth resistance line pattern R5, the fifth resistance lines R5 adjacent in the circumferential direction are alternately connected to each other on one side and the other side in the radial direction, and are connected in series as a whole. Each fifth resistance line r5 extends in the radial direction of the flexible gear 20.

In this way, the fourth resistance line R4 included in the fourth resistance line pattern R4 and the fifth resistance line R5 included in the fifth resistance line pattern R5 each extend in the radial direction. Therefore, variations in the resistance values of the fourth resistance line pattern R4 and the fifth resistance line pattern R5 due to the torque in the circumferential direction are extremely small. However, when the diaphragm portion 221 of the flexible gear 20 is displaced in the axial direction, the resistance values of the fourth resistance line pattern R4 and the fifth resistance line pattern R5 greatly change. Therefore, by measuring the resistance values of the fourth resistance line pattern R4 and the fifth resistance line pattern R5, a signal reflecting the amount of displacement in the axial direction of the diaphragm portion 221 can be obtained.

The signal processing circuit 43 corrects the signal output from the wheatstone bridge circuit 42 including the first resistance line pattern R1 and the second resistance line pattern R2 by using the respective resistance values of the fourth resistance line pattern R4 and the fifth resistance line pattern R5. Specifically, the value of the signal output from the wheatstone bridge circuit 42 is increased or decreased in a direction in which the influence of the axial displacement of the diaphragm portion 221 is eliminated. Next, a torque is detected based on the corrected output signal. This makes it possible to detect the torque applied to the flexible gear 20 with high accuracy while suppressing the influence of the axial displacement of the diaphragm portion 221.

Further, a wheatstone bridge circuit for thrust strain detection (not shown) may be formed by the fourth resistance line pattern R4 and the fifth resistance line pattern R5. In this case, the axial displacement amount of the diaphragm portion 221 can be detected with high accuracy based on a signal output from a wheatstone bridge circuit for thrust strain detection. Therefore, the correction value for the signal output from the wheatstone bridge circuit 42 including the first resistance line pattern R1 and the second resistance line pattern R2 can be calculated more appropriately.

< 1-3. summarization >

As described above, in the power transmission device 1 of the present embodiment, the torque applied to the flexible gear 20 is detected by the torque detection sensor 40. Therefore, the detected torque can be used for control of a device in which the power transmission device 1 is mounted or for failure detection. In particular, in the present embodiment, the torque detection sensor 40 is fixed to the flexible gear 20, which is the most output-side component among the constituent components of the power transmission device 1. In this way, the external force applied to the flexible gear 20 from the output side can be detected with high accuracy by the torque detection sensor 40. Therefore, for example, control for urgently stopping the apparatus when an external force is detected can be performed with good responsiveness.

In particular, in the torque detection sensor 40 of the present embodiment, the first resistance line pattern R1 and the second resistance line pattern R2 are provided over substantially the entire circumference of the flexible gear 20 in the circumferential direction, instead of attaching the strain gauge only to a part of the flexible gear 20 in the circumferential direction. This allows the torque applied to the flexible gear 20 to be detected with higher accuracy.

In the torque detection sensor 40 of the present embodiment, the substrate 41 includes the first conductor layer L1 and the second conductor layer L2. The first conductor layer L1 includes a first resistance line pattern R1, a second resistance line pattern R2, and a third resistance line pattern R3. The second conductor layer L2 includes a fourth resistance line pattern R4 and a fifth resistance line pattern R5. The resistance line pattern R1, the resistance line pattern R2, and the resistance line pattern R3 of the first conductor layer L1 partially overlap in the axial direction with the resistance line pattern R4 and the resistance line pattern R5 of the second conductor layer L2. Thus, the substrate 41 can be miniaturized in the radial direction while securing a space for arranging the resistance line patterns R1 to R5 in the substrate 41. Therefore, the torque detection sensor 40 that can be applied to the small-sized flexible gear 20 is realized.

In the torque detection sensor 40 of the present embodiment, the first conductor layer L1 is a front-surface conductor layer, and the second conductor layer L2 is a rear-surface conductor layer. This makes it possible to reduce the thickness of the torque detection sensor 40.

In the torque detection sensor 40 according to the present embodiment, the first conductor layer L1 includes a resistance line pattern R1 and a resistance line pattern R2. The second conductor layer L2 includes a resistance line pattern R4 and a resistance line pattern R5 as patterns for detecting thrust strain. Thus, the torque applied to the diaphragm portion 221 can be detected in consideration of the axial strain of the diaphragm portion 221.

In the torque detection sensor 40 of the present embodiment, the first conductor layer L1 includes the third resistance line pattern R3. Thus, the torque applied to the diaphragm portion 221 can be detected in consideration of the temperature of the diaphragm portion 221 or the ambient temperature.

In the torque detection sensor 40 of the present embodiment, the conductor layer L1 and the conductor layer L2 are made of copper or an alloy containing copper. This can suppress the material cost of the torque detection sensor 40. The torque detection sensor 40 can be manufactured by the same manufacturing process as that of a normal printed wiring board.

In the torque detection sensor 40 of the present embodiment, the resistance line pattern R1 and the resistance line pattern R2 are incorporated in the wheatstone bridge circuit 42. Thus, the torque applied to the flexible gear 20 can be detected with high accuracy using the wheatstone bridge circuit 42.

In the power transmission device 1 of the present embodiment, the flexible gear (circular body) 20 includes the cylindrical portion 21, the external teeth 23, and the diaphragm portion 221. Further, the substrate 41 is fixed to the diaphragm portion 221. Thereby, the torque applied to the diaphragm portion 221 of the flexible gear 20 can be detected.

< 2. second embodiment >

Next, the torque detection sensor 40 of the second embodiment will be explained. Fig. 6 is a plan view of the torque detection sensor 40 of the present embodiment. Fig. 7 is a rear view of the torque detection sensor 40 of the present embodiment. The torque detection sensor 40 differs from the first embodiment in the following respects, namely: the first conductor layer L1 includes a first resistance line pattern R1 and a sixth resistance line pattern R6, while the second conductor layer L2 includes a fourth resistance line pattern R4 and a seventh resistance line pattern R7. In the following description, the same components and functions as those in the first embodiment are denoted by the same reference numerals, and redundant description thereof will be omitted.

As shown in fig. 6, the first conductor layer L1 of the present embodiment includes a first resistance line pattern R1 and a sixth resistance line pattern R6. That is, the first resistance line pattern R1 and the sixth resistance line pattern R6 are mounted on the surface of the substrate 41. The shape of the first resistance line pattern R1 is equivalent to that of the first resistance line pattern R1 of the first embodiment. The first resistance line pattern R1 and the sixth resistance line pattern R6 are electrically connected to the signal processing circuit 43.

The sixth resistance line pattern R6 is a pattern in which one conductor extends while being bent, and has an arc shape or an annular shape as a whole. In the present embodiment, the sixth resistance line pattern R6 is provided in a range of about 360 ° around the center axis 9. As for the material of the sixth resistance line pattern R6, for example, copper or an alloy containing copper may be used. The sixth resistance line pattern R6 includes a plurality of sixth resistance lines R6. The sixth resistance wires r6 are arranged substantially parallel to each other at equal intervals in the circumferential direction. In the sixth resistance line pattern R6, the sixth resistance lines R6 adjacent in the circumferential direction are alternately connected to each other on one side and the other side in the radial direction, and are connected in series as a whole. Each sixth resistance line r6 extends in the radial direction of the flexible gear 20.

As shown in fig. 7, the second conductor layer L2 of the present embodiment includes a fourth resistance line pattern R4 and a seventh resistance line pattern R7. That is, the fourth resistance line pattern R4 and the seventh resistance line pattern R7 are mounted on the rear surface of the substrate 41. The shape of the fourth resistance line pattern R4 is equivalent to the shape of the fourth resistance line pattern R4 of the first embodiment. The fourth resistance line pattern R4 and the seventh resistance line pattern R7 are electrically connected to the signal processing circuit 43. The first resistance line pattern R1 and the seventh resistance line pattern R7 are incorporated into the wheatstone bridge circuit 42.

The seventh resistance line pattern R7 is a pattern in which one conductor is bent and extends in the circumferential direction, and is entirely arc-shaped or annular. In the present embodiment, the seventh resistance line pattern R7 is provided in a range of about 360 ° around the center axis 9. As for the material of the seventh resistance line pattern R7, for example, copper or an alloy containing copper may be used. The seventh resistance line pattern R7 includes a plurality of seventh resistance lines R7. The seventh resistance wires r7 are arranged in a substantially parallel posture at equal intervals in the circumferential direction. In the seventh resistance line pattern R7, the seventh resistance lines R7 adjacent in the circumferential direction are alternately connected to each other on one side and the other side in the radial direction, and are connected in series as a whole. When viewed from the other axial side of the substrate 41, each of the seventh resistance lines r7 is inclined to one circumferential side with respect to the radial direction of the flexible gear 20. The angle of inclination of the seventh resistance line r7 with respect to the radial direction is, for example, 45 °.

The respective resistance values of the first resistance line pattern R1 and the seventh resistance line pattern R7 vary according to the torque applied to the flexible gear 20. For example, if a torque is applied to the flexible gear 20 toward one side in the circumferential direction about the central axis 9 as viewed from one side in the axial direction, the resistance value of the first resistance line pattern R1 decreases, and the resistance value of the seventh resistance line pattern R7 increases. On the other hand, when a torque is applied to the flexible gear 20 toward the other side in the circumferential direction about the central axis 9 as viewed from one side in the axial direction, the resistance value of the first resistance line pattern R1 increases, and the resistance value of the seventh resistance line pattern R7 decreases. Thus, the first resistance line pattern R1 and the seventh resistance line pattern R7 show mutually opposite resistance value changes with respect to the torque. In the present embodiment, the direction and magnitude of the torque applied to the flexible gear 20 can be detected based on the measurement value of the voltmeter V provided in the wheatstone bridge circuit 42 by utilizing the above-described properties.

In the torque detection sensor 40 of the present embodiment, the resistance line pattern R1 and the resistance line pattern R6 of the first conductor layer L1 partially overlap with the resistance line pattern R4 and the resistance line pattern R7 of the second conductor layer L2 in the axial direction. Thereby, it is possible to secure a space for arranging the resistance line pattern R1, the resistance line pattern R4, the resistance line pattern R6, and the resistance line pattern R7 in the substrate 41, and to miniaturize the substrate 41 in the radial direction. Therefore, the torque detection sensor 40 that can be applied to the small-sized flexible gear 20 is realized.

In the present embodiment, a resistance line pattern for acquiring a signal reflecting the temperature of the flexible gear 20 or the ambient temperature is not provided. In this way, the resistance line pattern corresponding to the third resistance line pattern R3 of the first embodiment may also be omitted.

< 3. third embodiment >

Next, the torque detection sensor 40 of the third embodiment will be explained. Fig. 8 is a plan view of the torque detection sensor 40 of the present embodiment. Fig. 9 is a rear view of the torque detection sensor 40 of the present embodiment. The torque detection sensor 40 differs from the first to second embodiments in the following respects: the first conductor layer L1 includes a first resistance line pattern R1 and a second resistance line pattern R2, while the second conductor layer L2 includes a third resistance line pattern R3.

As shown in fig. 8, the first conductor layer L1 of the present embodiment includes a first resistance line pattern R1 and a second resistance line pattern R2. That is, the first resistance line pattern R1 and the second resistance line pattern R2 are mounted on the surface of the substrate 41. The first resistance line pattern R1 and the second resistance line pattern R2 are electrically connected to the signal processing circuit 43. The first resistance line pattern R1 and the second resistance line pattern R2 are incorporated into the wheatstone bridge circuit 42.

The shapes of the first resistance line pattern R1 and the second resistance line pattern R2 are equivalent to those of the first resistance line pattern R1 and the second resistance line pattern R2 of the first embodiment. Therefore, in the present embodiment, the first resistance line pattern R1 and the second resistance line pattern R2 also show mutually opposite resistance value changes with respect to the torque. In the present embodiment, the direction and magnitude of the torque applied to the flexible gear 20 can be detected based on the measurement value of the voltmeter V provided in the wheatstone bridge circuit 42 by utilizing the above-described properties.

As shown in fig. 9, the second conductor layer L2 of the present embodiment includes a third resistance line pattern R3. That is, the third resistance line pattern R3 is mounted on the rear surface of the substrate 41. The shape of the third resistance line pattern R3 is equivalent to that of the third resistance line pattern R3 of the first embodiment. Therefore, in the present embodiment, when the resistance value of the third resistance line pattern R3 is measured, a signal reflecting the temperature of the flexible gear 20 or the ambient temperature can be obtained. The signal processing circuit 43 corrects the signal output from the wheatstone bridge circuit 42 including the first resistance line pattern R1 and the second resistance line pattern R2 by the resistance value of the third resistance line pattern R3. Specifically, the value of the signal output from the wheatstone bridge circuit 42 is increased or decreased in a direction in which the change due to temperature is eliminated. Next, a torque is detected based on the corrected output signal. This makes it possible to detect the torque applied to the flexible gear 20 with high accuracy while suppressing the influence of temperature change.

In particular, in the present embodiment, the third resistance line pattern R3 is arranged in the radial gap between the first resistance line pattern R1 and the second resistance line pattern R2 as viewed in the axial direction. In this way, the third resistance line pattern R3 for temperature correction can be arranged at a position close to both the first resistance line pattern R1 and the second resistance line pattern R2. Therefore, the correction value for the output signal of the wheatstone bridge circuit 42 can be calculated more appropriately based on the resistance value of the third resistance line pattern R3.

< 4. fourth embodiment >

Next, the torque detection sensor 40 of the fourth embodiment will be explained. Fig. 10 is a plan view of the torque detection sensor 40 of the present embodiment. Fig. 11 is a rear view of the torque detection sensor 40 of the present embodiment. The torque detection sensor 40 is different from the first to third embodiments in that: the first conductor layer L1 includes a first resistance line pattern R1, and the second conductor layer L2 includes a third resistance line pattern R3 and a seventh resistance line pattern R7.

As shown in fig. 10, the first conductor layer L1 of the present embodiment includes a first resistance line pattern R1. That is, the first resistance line pattern R1 is mounted on the surface of the substrate 41. The shape of the first resistance line pattern R1 is equivalent to that of the first resistance line pattern R1 of the first embodiment. The first resistance line pattern R1 is electrically connected to the signal processing circuit 43.

As shown in fig. 11, the second conductor layer L2 of the present embodiment includes a third resistance line pattern R3 and a seventh resistance line pattern R7. That is, the third resistance line pattern R3 and the seventh resistance line pattern R7 are mounted on the rear surface of the substrate 41. The third resistance line pattern R3 and the seventh resistance line pattern R7 are electrically connected to the signal processing circuit 43. The first resistance line pattern R1 and the seventh resistance line pattern R7 are incorporated into the wheatstone bridge circuit 42.

The shape of the first resistance line pattern R1 is equivalent to that of the first resistance line pattern R1 of the second embodiment. The shape of the seventh resistance line pattern R7 is identical to that of the seventh resistance line pattern R7 of the second embodiment. Therefore, in the present embodiment, the first resistance line pattern R1 and the seventh resistance line pattern R7 also show mutually opposite resistance value changes with respect to the torque. In the present embodiment, the direction and magnitude of the torque applied to the flexible gear 20 can be detected by using the above-described properties.

The shape of the third resistance line pattern R3 is equivalent to the shape of the third resistance line pattern R3 of the first embodiment. Therefore, in the present embodiment, when the resistance value of the third resistance line pattern R3 is measured, a signal reflecting the temperature of the flexible gear 20 or the ambient temperature can be obtained. The signal processing circuit 43 corrects the signal output from the wheatstone bridge circuit 42 including the first resistance line pattern R1 and the seventh resistance line pattern R7 by the resistance value of the third resistance line pattern R3. Specifically, the value of the signal output from the wheatstone bridge circuit 42 is increased or decreased in a direction in which the change due to temperature is eliminated. Next, a torque is detected based on the corrected output signal. This makes it possible to detect the torque applied to the flexible gear 20 with high accuracy while suppressing the influence of temperature change.

< 5. fifth embodiment >

Next, the torque detection sensor 40 of the fifth embodiment will be described. Fig. 12 is a plan view of the torque detection sensor 40 of the present embodiment. Fig. 13 is a rear view of the torque detection sensor 40 of the present embodiment. The torque detection sensor 40 is different from the first to fourth embodiments in that: the first conductor layer L1 includes an eighth resistance line pattern R8, a ninth resistance line pattern R9, a tenth resistance line pattern R10, and an eleventh resistance line pattern R11, while the second conductor layer L2 includes a twelfth resistance line pattern R12, a thirteenth resistance line pattern R13, a fourteenth resistance line pattern R14, and a fifteenth resistance line pattern R15.

As shown in fig. 12, the first conductor layer L1 of the present embodiment includes an eighth resistance line pattern R8, a ninth resistance line pattern R9, a tenth resistance line pattern R10, and an eleventh resistance line pattern R11. That is, the eighth resistance line pattern R8, the ninth resistance line pattern R9, the tenth resistance line pattern R10, and the eleventh resistance line pattern R11 are mounted on the surface of the substrate 41. The eighth resistance line pattern R8, the ninth resistance line pattern R9, the tenth resistance line pattern R10, and the eleventh resistance line pattern R11 are electrically connected to the signal processing circuit 43.

The eighth resistance line pattern R8 is a pattern in which one conductor is bent and extends in the circumferential direction, and the entire pattern is arc-shaped. In the present embodiment, the eighth resistance line pattern R8 is provided in a semicircular shape in a range of about 180 ° around the center axis 9. The eighth resistance line pattern R8 includes a plurality of eighth resistance lines R8. The eighth resistance wires r8 are arranged in a substantially parallel posture to each other in the circumferential direction. Each eighth resistance line r8 is inclined to one side in the circumferential direction with respect to the radial direction of the flexible gear 20 when viewed from one side in the axial direction. The angle of inclination of the eighth resistance line r8 with respect to the radial direction is, for example, 45 °.

The ninth resistance line pattern R9 is a pattern in which one conductor is bent and extended in the circumferential direction, and the entire pattern is arc-shaped. In the present embodiment, the ninth resistance line pattern R9 is provided in a semicircular shape in a range of about 180 ° around the center axis 9. The ninth resistance line pattern R9 includes a plurality of ninth resistance lines R9. The plurality of ninth resistance wires r9 are arranged in a substantially parallel posture to each other in the circumferential direction. When viewed from one side in the axial direction, each ninth resistance line r9 is inclined to the other side in the circumferential direction with respect to the radial direction of the flexible gear 20. The ninth resistance line r9 is inclined at an angle of, for example, -45 ° with respect to the radial direction.

The eighth resistance line pattern R8 and the ninth resistance line pattern R9 are concentrically and line-symmetrically arranged. Specifically, the eighth resistance line pattern R8 is disposed on one side and the ninth resistance line pattern R9 is disposed on the other side with respect to an imaginary straight line Q passing through the central axis 9 when viewed from one side in the axial direction. Also, the eighth resistance line pattern R8 has the same radius with respect to the central axis 9 as the ninth resistance line pattern R9.

The tenth resistance line pattern R10 is a pattern in which one conductor is bent and extends in the circumferential direction, and the entire pattern is arc-shaped. In the present embodiment, the tenth resistance line pattern R10 is provided in a semicircular shape in a range of about 180 ° around the center axis 9. The tenth resistance line pattern R10 is located more radially inward than the eighth resistance line pattern R8. The tenth resistance line pattern R10 includes a plurality of tenth resistance lines R10. The tenth resistance wires r10 are arranged in a substantially parallel posture to each other in the circumferential direction. When viewed from one side in the axial direction, each tenth resistance line r10 is inclined to the other side in the circumferential direction with respect to the radial direction of the flexible gear 20. The tenth resistance line r10 is inclined at an angle of, for example, -45 ° with respect to the radial direction.

The eleventh resistance line pattern R11 is a pattern in which one conductor is bent and extends in the circumferential direction, and the entire pattern is arc-shaped. In the present embodiment, the eleventh resistance line pattern R11 is provided in a semicircular shape in a range of about 180 ° around the center axis 9. The eleventh resistance line pattern R11 is located more radially inward than the ninth resistance line pattern R9. The eleventh resistance line pattern R11 includes a plurality of eleventh resistance lines R11. The eleventh resistance wires r11 are arranged in a substantially parallel posture to each other in the circumferential direction. When viewed from one side of the axial direction, each eleventh resistance line r11 is inclined to one side of the circumferential direction with respect to the radial direction of the flexible gear 20. The angle of inclination of the eleventh resistance line r11 with respect to the radial direction is, for example, 45 °.

The tenth resistance line pattern R10 and the eleventh resistance line pattern R11 are concentrically and line-symmetrically arranged. Specifically, the tenth resistance line pattern R10 is disposed on one side and the eleventh resistance line pattern R11 is disposed on the other side with respect to a virtual straight line Q passing through the central axis 9 when viewed from one side in the axial direction. Also, the tenth resistance line pattern R10 has the same radius with respect to the central axis 9 as the eleventh resistance line pattern R11.

As shown in fig. 13, the second conductor layer L2 of the present embodiment includes a twelfth resistance line pattern R12, a thirteenth resistance line pattern R13, a fourteenth resistance line pattern R14, and a fifteenth resistance line pattern R15. That is, the twelfth resistance line pattern R12, the thirteenth resistance line pattern R13, the fourteenth resistance line pattern R14, and the fifteenth resistance line pattern R15 are mounted on the rear surface of the substrate 41. The twelfth resistance line pattern R12, the thirteenth resistance line pattern R13, the fourteenth resistance line pattern R14, and the fifteenth resistance line pattern R15 are electrically connected to the signal processing circuit 43.

The twelfth resistance line pattern R12 is a pattern in which one conductor is bent and extends in the circumferential direction, and the entire pattern is arc-shaped. In the present embodiment, the twelfth resistance line pattern R12 is provided in a semicircular shape in a range of about 180 ° around the center axis 9. The twelfth resistance line pattern R12 includes a plurality of twelfth resistance lines R12. The twelfth resistance wires r12 are arranged in a circumferential direction in a substantially parallel posture. When viewed from the other axial side, each of the twelfth resistance lines r12 is inclined to one circumferential side with respect to the radial direction of the flexible gear 20. The angle of inclination of the twelfth resistance line r12 with respect to the radial direction is, for example, 45 °. That is, the twelfth resistance line pattern R12 is repeated with the ninth resistance line pattern R9 as viewed in the axial direction.

The thirteenth resistance line pattern R13 is a pattern in which one conductor is bent and extends in the circumferential direction, and is entirely arc-shaped. In the present embodiment, the thirteenth resistance line pattern R13 is provided in a semicircular shape in a range of about 180 ° around the center axis 9. The thirteenth resistance line pattern R13 includes a plurality of thirteenth resistance lines R13. The thirteenth resistance wires r13 are arranged in a circumferential direction in a substantially parallel posture. When viewed from the other side in the axial direction, each thirteenth resistance line r13 is inclined to the other side in the circumferential direction with respect to the radial direction of the flexible gear 20. The thirteenth resistance line r13 is inclined at an angle of-45 ° with respect to the radial direction, for example. That is, the thirteenth resistance line pattern R13 overlaps with the eighth resistance line pattern R8 as viewed in the axial direction.

The twelfth resistance line pattern R12 and the thirteenth resistance line pattern R13 are concentrically and line-symmetrically arranged. Specifically, the twelfth resistance line pattern R12 is disposed on one side and the thirteenth resistance line pattern R13 is disposed on the other side with respect to a virtual straight line Q passing through the central axis 9 when viewed from the other axial side. Also, the twelfth resistance line pattern R12 has the same radius with respect to the central axis 9 as the thirteenth resistance line pattern R13.

The fourteenth resistance line pattern R14 is a pattern in which one conductor is bent and extends in the circumferential direction, and is entirely arc-shaped. In the present embodiment, the fourteenth resistance line pattern R14 is provided in a semicircular shape in a range of about 180 ° around the central axis 9. The fourteenth resistance line pattern R14 is located more radially inward than the twelfth resistance line pattern R12. The fourteenth resistance line pattern R14 includes a plurality of fourteenth resistance lines R14. The fourteenth resistance lines r14 are arranged in a substantially parallel posture in the circumferential direction. When viewed from the other side in the axial direction, each fourteenth resistance line r14 is inclined to the other side in the circumferential direction with respect to the radial direction of the flexible gear 20. The fourteenth resistance line r14 is inclined at an angle of, for example, -45 ° with respect to the radial direction. That is, the fourteenth resistance line pattern R14 overlaps with the eleventh resistance line pattern R11 as viewed in the axial direction.

The fifteenth resistance line pattern R15 is a pattern in which one conductor is bent and extends in the circumferential direction, and is entirely arc-shaped. In the present embodiment, the fifteenth resistance line pattern R15 is provided in a semicircular shape in a range of about 180 ° around the center axis 9. The fifteenth resistance line pattern R15 is located more radially inward than the thirteenth resistance line pattern R13. The fifteenth resistance line pattern R15 includes a plurality of fifteenth resistance lines R15. The fifteenth resistance lines r15 are arranged in a substantially parallel posture with respect to each other in the circumferential direction. When viewed from the other axial side, each fifteenth resistance line r15 is inclined to one side in the circumferential direction with respect to the radial direction of the flexible gear 20. The angle of inclination of the fifteenth resistance line r15 with respect to the radial direction is, for example, 45 °. That is, the fifteenth resistance line pattern R15 overlaps with the tenth resistance line pattern R10 as viewed in the axial direction.

The fourteenth resistance line pattern R14 and the fifteenth resistance line pattern R15 are concentrically and line-symmetrically arranged. Specifically, the fourteenth resistance line pattern R14 is disposed on one side and the fifteenth resistance line pattern R15 is disposed on the other side with respect to a virtual straight line Q passing through the central axis 9 when viewed from the other axial side. Also, the fourteenth resistance line pattern R14 has the same radius with respect to the central axis 9 as the fifteenth resistance line pattern R15.

The eighth to fifteenth resistance line patterns R8 to R15 are incorporated in the wheatstone bridge circuit. For example, a series connection R8+ R13 of the eighth resistance line pattern R8 and the thirteenth resistance line pattern R13, a series connection R9+ R12 of the ninth resistance line pattern R9 and the twelfth resistance line pattern R12, a series connection R10+ R15 of the tenth resistance line pattern R10 and the fifteenth resistance line pattern R15, and a series connection R11+ R14 of the eleventh resistance line pattern R11 and the fourteenth resistance line pattern R14 are incorporated into the wheatstone bridge circuit 42.

In the present embodiment, the resistance line pattern R8+ resistance line pattern R13 and the resistance line pattern R9+ resistance line pattern R12 show mutually opposite resistance value changes with respect to the torque. Further, the resistance line pattern R10+ the resistance line pattern R15 and the resistance line pattern R11+ the resistance line pattern R14 show mutually opposite resistance value changes with respect to the torque. In the present embodiment, the direction and magnitude of the torque applied to the flexible gear 20 can be detected based on the measurement value of the voltmeter V provided in the wheatstone bridge circuit 42 by utilizing the above-described properties.

As described above, in the present embodiment, by connecting patterns that repeat when viewed in the axial direction in series with each other, the resistance value can be made larger. In other words, the resistance line patterns can be efficiently arranged using both surfaces of the substrate 41. Therefore, the sensor sensitivity of the torque detection sensor 40 can be improved.

When the power transmission device 1 is driven, the diaphragm portion 221 of the flexible gear 20 is slightly displaced in the axial direction. The axial displacement amount differs depending on the position of the diaphragm portion 221 in the radial direction. In addition, the displacement of the diaphragm portion 221 in the axial direction also affects the resistance values of the resistance line patterns R8 to R15. However, in the present embodiment, the resistance line pattern R8+ the resistance line pattern R13 and the resistance line pattern R9+ the resistance line pattern R12 are arranged at the same diameter position with respect to the central axis 9. Similarly, the resistance line pattern R10+ the resistance line pattern R15 and the resistance line pattern R11+ the resistance line pattern R14 are arranged at the same diameter position with respect to the central axis 9. Therefore, the displacement in the axial direction of the diaphragm portion 221 causes the resistance line pattern R8+ resistance line pattern R13 to change similarly to the resistance line pattern R9+ resistance line pattern R12. Similarly, the resistance line pattern R10+ resistance line pattern R15 changes in the same manner as the resistance line pattern R11+ resistance line pattern R14. Therefore, the detection value of the voltmeter V of the wheatstone bridge circuit 42 is less susceptible to the axial displacement. Therefore, the influence of the axial displacement of the diaphragm portion 221 can be suppressed, and the circumferential torque applied to the flexible gear 20 can be detected with high accuracy.

In the torque detection sensor 40 of the present embodiment, the resistance line patterns R8 to R11 of the first conductor layer L1 and the resistance line patterns R12 to R15 of the second conductor layer L2 partially overlap in the axial direction. Thus, the substrate 41 can be miniaturized in the radial direction while securing a space for arranging the resistance line patterns R8 to R15 in the substrate 41. Therefore, the torque detection sensor 40 that can be applied to the small-sized flexible gear 20 is realized.

< 6. variations of the first to fifth embodiments

The first to fifth embodiments of the present invention have been described above, but the present invention is not limited to the above embodiments.

In the above embodiment, the first conductor layer L1 is a front-surface conductor layer of the substrate 41, and the second conductor layer is a rear-surface conductor layer of the substrate 41. However, the first conductor layer L1 may be a rear surface conductor layer of the substrate, and the second conductor layer L2 may be a front surface conductor layer of the substrate. That is, which surface of the substrate is fixed to the surface of the diaphragm portion of the flexible gear is arbitrary.

In the above embodiment, the substrate has a front surface conductive layer and a back surface conductive layer. However, the substrate may also comprise an intermediate conductor layer. In this case, the first conductor layer may be any one of a front surface conductor layer, a back surface conductor layer, and an intermediate conductor layer, and the second conductor layer may be any other one of the front surface conductor layer, the back surface conductor layer, and the intermediate conductor layer. Alternatively, any of the resistance line patterns may be arranged in all of the front surface conductor layer, the back surface conductor layer, and the intermediate conductor layer. Thus, the resistance line pattern can be arranged in each layer of the substrate having the multilayer structure. As a result, the substrate can be further miniaturized in the radial direction.

In the fifth embodiment, for example, the eighth resistance line pattern R8 overlaps with the thirteenth resistance line pattern R13 as viewed in the axial direction. That is, the eighth resistance line R8 of the eighth resistance line pattern R8 and the thirteenth resistance line R13 of the thirteenth resistance line pattern R13 are parallel to each other as viewed in the axial direction. However, instead of this, the eighth resistance line R8 of the eighth resistance line pattern R8 may intersect the thirteenth resistance line R13 of the thirteenth resistance line pattern R13 when viewed in the axial direction. At this time, the intersection angle of the eighth resistance line r8 and the thirteenth resistance line r13 is arbitrary. At this time, a space for arranging the resistance line pattern in the substrate 41 can be secured, and the substrate 41 can be miniaturized in the radial direction. Therefore, a torque detection sensor that is also applicable to a small circular body is realized.

In the above embodiment, both the wheatstone bridge circuit 42 and the signal processing circuit 43 are mounted on the substrate 41. However, the signal processing circuit 43 may be provided outside the substrate 41.

In the above embodiment, copper or an alloy containing copper is used as a material of each resistance line pattern. However, as the material of the resistance line pattern, other metals such as constantan, Stainless Steel (SUS), and aluminum may be used. As a material of the resistance line pattern, a non-metal material such as ceramic or resin may be used. Further, as for the material of the resistance line pattern, conductive ink may also be used. When the conductive ink is used, each resistance line pattern may be printed on the surface of the substrate 41 using the conductive ink.

In the flexible gear 20 of the above embodiment, the diaphragm portion 221 is extended radially outward from the base end portion of the cylindrical portion 21. However, the diaphragm portion 221 may be expanded radially inward from the proximal end portion of the cylindrical portion 21.

In the embodiment, the object to be detected is the flexible gear 20. However, the torque detection sensor 40 having the same configuration as that of the above-described embodiment may be used to detect a torque applied to a circular body other than the flexible gear 20.

The resistance line patterns of the embodiments are all resistance line patterns used directly or indirectly for detecting the strain in the circumferential direction of the circular body. The number and position of these resistance line patterns can be appropriately designed and changed. Further, the detailed configurations of the torque detection sensor and the power transmission device may be appropriately modified within a range not departing from the gist of the present invention. Further, elements appearing in the above embodiments and modifications may be appropriately combined in a range not inconsistent with each other.

< 7. sixth embodiment >

< 7-1 > about torque detecting sensor

Next, the torque detection sensor 40 of the sixth embodiment will be described. The torque detection sensor 40 is a sensor that detects a circumferential torque applied to the flexible gear 20. As shown in fig. 1, in the present embodiment, the torque detection sensor 40 is fixed to the circular surface of the disc-shaped diaphragm portion 221.

Fig. 14 is a plan view of the torque detection sensor 40 viewed in the axial direction. As shown in fig. 14, the torque detection sensor 40 includes a substrate 41. The substrate 41 of the present embodiment is a flexible substrate that can be flexibly deformed. The base plate 41 includes an annular main body 411 centered on the central axis 9, and a flap portion 412 protruding radially outward from the main body 411. The substrate 41 has a third conductor layer L3. The third conductor layer L3 of the present embodiment is located on one surface in the axial direction of the substrate 41.

As shown in fig. 14, the third conductor layer L3 includes a sixteenth resistance line pattern R16 and a seventeenth resistance line pattern R17. The sixteenth resistance line pattern R16 and the seventeenth resistance line pattern R17 are incorporated into the wheatstone bridge circuit 42. In other words, the wheatstone bridge circuit 42 is mounted on the surface of the body 411. Further, the signal processing circuit 43 is mounted on the flap portion 412.

The sixteenth resistance line pattern R16 is a pattern in which one conductor is bent and extended in the circumferential direction, and is entirely in the shape of an arc or a ring. In the present embodiment, a sixteenth resistance line pattern R16 is provided in a range of about 360 ° around the center axis 9. As for the material of the sixteenth resistance line pattern R16, for example, copper or an alloy containing copper may be used. The sixteenth resistance line pattern R16 includes a plurality of sixteenth resistance lines R16 and a plurality of folded portions ra 1. The sixteenth resistance wires r16 are arranged in a substantially parallel posture at equal intervals in the circumferential direction. In the sixteenth resistance line pattern R16, sixteenth resistance lines R16 adjacent in the circumferential direction are alternately connected to each other at one side and the other side in the radial direction by the folded-back portions ra1, and are connected in series as a whole. Each sixteenth resistance line r16 is inclined to one side in the circumferential direction with respect to the radial direction of the flexible gear 20 when viewed from one side in the axial direction of the substrate 41. The angle of inclination of the sixteenth resistance line r16 with respect to the radial direction is, for example, 45 °. The fold-back portion ra1 will be described in detail below.

The seventeenth resistance line pattern R17 is a pattern in which one conductor is bent and extended in the circumferential direction, and is entirely arc-shaped or circular. In the present embodiment, a seventeenth resistance line pattern R17 is provided in a range of about 360 ° around the central axis 9. As for the material of the seventeenth resistance line pattern R17, for example, copper or an alloy containing copper may be used. The seventeenth resistance line pattern R17 is located further radially inward than the sixteenth resistance line pattern R16. That is, the sixteenth resistance line pattern R16 and the seventeenth resistance line pattern R17 are disposed at positions that do not overlap with each other. The seventeenth resistance line pattern R17 includes a plurality of seventeenth resistance lines R17 and a plurality of folded portions ra 2. The seventeenth resistance wires r17 are arranged in a substantially parallel posture at equal intervals in the circumferential direction. In the seventeenth resistance line pattern R17, seventeenth resistance lines R17 adjacent in the circumferential direction are alternately connected to each other at one side and the other side in the radial direction by the folded-back portions ra2, and are connected in series as a whole. Each seventeenth resistance line r17 is inclined to the other side in the circumferential direction with respect to the radial direction of the flexible gear 20 when viewed from one side in the axial direction of the substrate 41. The seventeenth resistance line r17 is inclined at an angle of, for example, -45 ° with respect to the radial direction. The fold-back portion ra2 will be described in detail below.

In the power transmission device 1 configured as described above, the diaphragm portion 221 repeats flexural deformation with rotation of the flexible gear 20. Therefore, stress is likely to concentrate on the radially outer folded portion ra1 of the sixteenth resistance line pattern R16 and the radially inner folded portion ra2 of the seventeenth resistance line pattern R17. More specifically, if the folded-back portions ra1 and ra2 are simply circular arcs, stress concentrates particularly at the beginning or end of the circular arc. Therefore, in the portion, the disconnection is easily generated. In this regard, in the present embodiment, the folded portion ra1 and the folded portion ra2 are formed into unique shapes in order to prevent the breakage of the folded portion ra1 and the folded portion ra 2.

< 7-2 > explanation on details of the folded-back portion

The fold-back portion ra1 and the fold-back portion ra2 will be described in detail below with reference to fig. 15. Fig. 15 is an enlarged view of the resistance line pattern R16. Since the folded portion ra2 has the same shape and function as the folded portion ra1, only the folded portion ra1 will be described below.

The folded-back portions ra1 have an inner shape and an outer shape in which ends of the resistance wires r16 adjacent in the circumferential direction are connected to each other in series by a curve having a gently changing curvature. In the present embodiment, the outer shape of the folded-back portion ra1 has a shape substantially similar to the inner shape. Each of the folded portions ra1 has a first gentle curve ra11 and a second gentle curve ra12 as a plurality of gentle curves.

The first gentle curved portion ra11 is provided in a vicinity of a connection point between one of the adjacent resistance lines r16, i.e., r16, and the start of the folded portion ra 1. The tangential direction of the inner shape of the first gentle curve ra11 substantially coincides with the radial direction of the flexible gear 20. As shown in fig. 15, the inner shape of the first gentle curve portion ra11 has a radius of curvature larger than a half of the distance D1 between the adjacent resistance lines r 16.

The second gentle curve ra12 is provided in a vicinity of a connection point between the other resistor r16 of the adjacent resistor r16 and the end of the folded-back portion ra 1. The tangential direction of the inner shape of the second gentle curve ra12 substantially coincides with the radial direction of the flexible gear 20. As shown in fig. 15, the inner shape of the second gentle curve portion ra12 has a radius of curvature larger than a half of the distance D1 between the adjacent resistance lines r 16.

The folded-back portion ra1 includes a portion having a radius of curvature smaller than a half of the distance D1 in the inside shape between the first gentle curve portion ra11 and the second gentle curve portion ra 12. Specifically, the folded portion ra1 of the present embodiment has a smaller radius of curvature of the inner shape as it approaches the second gentle curve portion ra12 from the first gentle curve portion ra11, and further has a larger radius of curvature of the inner shape as it approaches the second gentle curve portion ra 12. As described above, the inner shape of the folded-back portion ra1 of the present embodiment does not have a portion where the radius of curvature is sharply reduced. The inner shape of the folded-back portion ra1 of the present embodiment may be formed by a curve having a curvature radius that changes continuously and gently.

The folded portion ra1 having such a configuration is connected as a whole by a curve having a large curvature, and therefore, there is no portion where stress is extremely concentrated when the flexible gear 20 rotates. Particularly, in the vicinity of the connection between the folded-back portion ra1 and the resistance line r16, there is a portion extending in the radial direction of the flexible gear 20. Although stress is likely to concentrate in the above-described portion, the radius of curvature of the inner shape here is particularly large in the present embodiment. Therefore, disconnection of the resistance line pattern R16 and the resistance line pattern R17 can be effectively prevented.

As described above, in the torque detection sensor 40 of the present embodiment, the folding portion ra1 includes at least one first slow-curved portion ra11 as a slow-curved portion. The inner shape of the first gentle curve ra11 has a radius of curvature larger than a half of the distance D1 between the adjacent resistance lines r 16. Thus, stress concentration can be suppressed in the first gentle curve portion ra11 in which the radius of curvature is set large. Therefore, disconnection of the resistance line pattern R16 can be suppressed.

In the torque detection sensor 40 of the present embodiment, the tangential direction of the inner shape of the first gentle curve portion ra11 substantially coincides with the radial direction of the flexible gear 20. This makes it possible to suppress stress concentration by the inside shape at the portion where stress is particularly likely to concentrate among the folded-back portions ra 1. Therefore, the disconnection of the resistance line pattern R16 can be further suppressed.

As shown in fig. 15, in the torque detection sensor 40 according to the present embodiment, a curve S1 formed by connecting the centers of inscribed circles inscribed in the inner shape of the folded portion ra1 in order is formed as approaching the radial direction of the flexible gear 20 from the resistance line r16 side toward the folded portion ra1 side. Thus, the entire inner shape of the folded portion ra1 is a shape capable of suppressing local stress concentration.

In the torque detection sensor 40 of the present embodiment, the circumferential width of the folded portion ra1 is shorter than the circumferential interval between the adjacent resistance lines r 16. Accordingly, without making the length of the folded portion ra1 of the resistance line pattern R16 excessively long, stress concentration can be suppressed, and disconnection of the resistance line pattern R16 can be suppressed. As a result, the torque detection sensor 40 can be downsized.

< 7-3. detailed explanation on the folding back part from other points of view >

Hereinafter, the fold back portion ra1 and the fold back portion ra2 will be described in detail with reference to fig. 16 from a different viewpoint from the above. Fig. 16 is an enlarged view of the resistance line pattern R16. Since the folded portion ra2 has the same shape and function as the folded portion ra1, only the folded portion ra1 will be described below.

The folded-back portions ra1 have an inner shape and an outer shape in which ends of the resistance wires r16 adjacent in the circumferential direction are connected to each other in series by a curve having a gently changing curvature. In the present embodiment, the outer shape of the folded-back portion ra1 has a shape substantially similar to the inner shape. The folding portion ra1 has a first gentle curve ra11 and a second gentle curve ra12 as a plurality of gentle curves.

The first gentle curved portion ra11 is provided in a vicinity of a connection point between one of the adjacent resistance lines r16, i.e., r16, and the start of the folded portion ra 1. The tangential direction of the inner shape of the first gentle curve ra11 substantially coincides with the radial direction of the flexible gear 20. As shown in fig. 16, the curvature center C1 of the inner shape of the first gentle curve portion ra11 is located on the opposite side of the first gentle curve portion ra11 with respect to a virtual straight line S2, and the virtual straight line S2 passes through both ends P1 and P2 of a segment formed by connecting centers of circles having both adjacent resistance lines r16 as tangents in order. Therefore, the first gentle curve portion ra11 has a larger curvature than the inner shape of the other most part of the region of the folded-back portion ra 1. In other words, the inner shape of the first gentle curve portion ra11 becomes a curve gentler than the inner shape of the other region (region other than the second gentle curve portion ra 12) of the folded portion ra 1.

The second gentle curve ra12 is provided in a vicinity of a connection point between the other resistor r16 of the adjacent resistor r16 and the end of the folded-back portion ra 1. The tangential direction of the inner shape of the second gentle curve ra12 substantially coincides with the radial direction of the flexible gear 20. As shown in fig. 16, the center of curvature C2 of the inner shape of the second gentle curve portion ra12 is located on the same side as the side on which the second gentle curve portion ra12 is arranged with respect to a virtual straight line S2, and the virtual straight line S2 is formed by connecting the centers of circles having both adjacent resistance lines r16 as tangents in order, and has both ends P1 and P2 of a line segment. More specifically, the center of curvature C2 of the inner shape of the second gentle curve ra12 is located between the second gentle curve ra12 and the virtual straight line S2. However, the second gently-curved portion ra12 has a larger curvature than the inner shape of the other most region of the folded-back portion ra 1. In other words, the inner shape of the second gentle curve ra12 becomes a curve more gentle than the inner shape of the other region (region other than the first gentle curve ra 11) of the folded portion ra 1.

The folded-back portion ra1 includes a portion having a radius of curvature smaller than a half of the distance D1 in the inside shape between the first gentle curve portion ra11 and the second gentle curve portion ra 12. Specifically, the folded portion ra1 of the present embodiment has a smaller radius of curvature of the inner shape as it approaches the second gentle curve portion ra12 from the first gentle curve portion ra11, and further has a larger radius of curvature of the inner shape as it approaches the second gentle curve portion ra 12. As described above, the inner shape of the folded-back portion ra1 of the present embodiment does not have a portion where the radius of curvature sharply decreases. The inner shape of the folded-back portion ra1 of the present embodiment is formed by a curve having a curvature radius that changes continuously and gently.

The folded portion ra1 having such a configuration is connected to each other entirely by a curved line having a large curvature, and therefore, there is no portion where stress is extremely concentrated when the flexible gear 20 rotates. Particularly, in the vicinity of the connection between the folded-back portion ra1 and the resistance line r16, there is a portion extending in the radial direction of the flexible gear 20. Although stress is likely to concentrate in the above-described portion, the radius of curvature of the inner shape here is particularly large in the present embodiment. Therefore, disconnection of the resistance line pattern R16 and the resistance line pattern R17 can be effectively prevented.

As described above, in the torque detection sensor 40 of the present embodiment, the folded portion ra1 has the first gentle curve ra 11. The curvature center C1 of the inner shape of the first gentle curve portion ra11 is located on the opposite side of the first gentle curve portion ra11 with respect to a virtual straight line S2, and the virtual straight line S2 passes through both ends P1 and P2 of a segment formed by sequentially connecting centers of circles having two adjacent resistance lines r16 as tangents. This can suppress stress concentration in the first gentle curve portion ra11 at the folded-back portion ra 1. Therefore, disconnection of the resistance line pattern R16 can be suppressed.

In the torque detection sensor 40 of the present embodiment, the tangential direction of the inner shape of the first gentle curve portion ra11 substantially coincides with the radial direction of the flexible gear 20. This can alleviate stress concentration by the inner shape at the portion where stress is particularly likely to concentrate among the folded-back portions ra 1. Therefore, the disconnection of the resistance line pattern R16 can be further suppressed.

< 8 > variation of the sixth embodiment

The sixth embodiment of the present invention has been described above, but the present invention is not limited to the above embodiment.

In the above embodiment, the shape unique to the present application is applied to both the radially inner and radially outer folded portions ra1 of the sixteenth resistance line pattern R16. Similarly, the shape unique to the present application is applied to both of the radially inner and radially outer folded portions ra2 of the seventeenth resistance line pattern R17. However, instead of this, the shape unique to the present application may be applied only to the radially outer folded portion ra1 of the sixteenth resistance line pattern R16 and the radially inner folded portion ra2 of the seventeenth resistance line pattern R17. This is because the diaphragm portion 221 of the flexible gear 20 is particularly easily deformed in the radial direction outer end region and the radial direction inner end region. This is illustrated in fig. 17. Fig. 17 is a plan view of a torque detection sensor 40 according to a modification of the sixth embodiment.

In the above embodiment, the outer shape of the folded-back portion ra1 is substantially similar to the inner shape, but the present invention is not limited thereto. For example, the width of the metal line at the folded back portion may be thicker than the width of the resistance line r 16.

< 9. seventh embodiment >

< 9-1 > about torque detecting sensor

Next, the torque detection sensor 40 of the seventh embodiment will be explained. The torque detection sensor 40 is a sensor that detects a circumferential torque applied to the flexible gear 20. As shown in fig. 1, in the present embodiment, the back surface of the torque detection sensor 40 is fixed to the circular surface of the disc-shaped diaphragm portion 221.

Fig. 18 is a plan view of the torque detection sensor 40 viewed in the axial direction. As shown in fig. 18, the torque detection sensor 40 includes a substrate 41. The substrate 41 of the present embodiment is a flexible substrate that can be flexibly deformed. The base plate 41 includes an annular main body 411 centered on the central axis 9, and a flap portion 412 protruding radially outward from the main body 411. The substrate 41 has a fourth conductor layer L4. The fourth conductor layer L4 of the present embodiment is located on one end surface (front surface) in the axial direction of the substrate 41.

As shown in fig. 18, the fourth conductor layer L4 includes an eighteenth resistance line pattern R18 and a nineteenth resistance line pattern R19. The eighteenth resistance line pattern R18 and the nineteenth resistance line pattern R19 are incorporated into the wheatstone bridge circuit 42. In other words, the wheatstone bridge circuit 42 is mounted on the surface of the body 411. Further, the signal processing circuit 43 is mounted on the flap portion 412.

The eighteenth resistance line pattern R18 is a pattern in which one conductor is bent and extends in the circumferential direction, and is entirely arc-shaped or annular. In the present embodiment, an eighteenth resistance line pattern R18 is provided in a range of about 360 ° around the center axis 9. As for the material of the eighteenth resistance line pattern R18, for example, copper or an alloy containing copper may be used. The eighteenth resistance line pattern R18 includes a plurality of linear eighteenth resistance lines R18 and a plurality of folded portions rb 1. The eighteenth resistance lines r18 are arranged in a substantially parallel posture at equal intervals in the circumferential direction. In the eighteenth resistance line pattern R18, eighteenth resistance lines R18 adjacent in the circumferential direction are alternately connected to each other at one side and the other side in the radial direction by the folded-back portions rb1, and are connected in series as a whole. Each eighteenth resistance line r18 is inclined to one side in the circumferential direction with respect to the radial direction of the flexible gear 20 when viewed from one side in the axial direction of the substrate 41. The angle of inclination of the eighteenth resistance line r18 with respect to the radial direction is, for example, 45 °.

The nineteenth resistance line pattern R19 is a pattern in which one conductor is bent and extends in the circumferential direction, and is entirely arc-shaped or annular. In the present embodiment, a nineteenth resistance line pattern R19 is provided in a range of about 360 ° around the center axis 9. As for the material of the nineteenth resistance line pattern R19, for example, copper or an alloy containing copper may be used. The nineteenth resistance line pattern R19 is located more radially inward than the eighteenth resistance line pattern R18. That is, the eighteenth resistance line pattern R18 and the nineteenth resistance line pattern R19 are disposed at positions that do not overlap with each other. The nineteenth resistance line pattern R19 includes a plurality of straight nineteenth resistance lines R19 and a plurality of folded portions rb 2. The nineteenth resistance wires r19 are arranged in a substantially parallel posture at equal intervals in the circumferential direction. In the nineteenth resistance line pattern R19, nineteenth resistance lines R19 adjacent in the circumferential direction are alternately connected to each other at one side and the other side in the radial direction by the folded-back portions rb2, and are connected in series as a whole. Each nineteenth resistance line r19 is inclined to the other side in the circumferential direction with respect to the radial direction of the flexible gear 20 when viewed from one side in the axial direction of the substrate 41. The nineteenth resistance line r19 is inclined at an angle of, for example, -45 ° with respect to the radial direction.

In the power transmission device 1 configured as described above, the diaphragm portion 221 repeats flexural deformation with rotation of the flexible gear 20. In particular, the diaphragm portion 221 is greatly deflected at the radially outer end of the diaphragm portion 221 and the radially inner end of the diaphragm portion 221 of the flexible gear 20. Therefore, if the portion of the substrate 41 including the radially outer folded portion rb1 of the eighteenth resistance line pattern R18 and the radially inner folded portion rb2 of the nineteenth resistance line pattern R19 is completely fixed to the diaphragm portion 221, the strain of the diaphragm portion 221 is directly transmitted to the folded portions rb1 and rb2, and stress is easily concentrated. Therefore, a disconnection may occur in the folded-back portions rb1 and rb 2. In this respect, in the present embodiment, in order to prevent the disconnection of the folded-back portion rb1 and the folded-back portion rb2, the torque detection sensor 40 is fixed to the diaphragm portion 221 of the flexible gear 20 by a unique method.

< 9-2 > about the fixation of the torque detecting sensor to the flexible gear

Specifically, the torque detection sensor 40 is fixed to the diaphragm portion 221 of the flexible gear 20 by the fixing layer 45. The anchor layer 45 will be described in detail below.

Fig. 19 is a sectional view of a torque detection sensor 40 of the seventh embodiment. As shown in fig. 19, the torque detection sensor 40 has a fixing layer 45. The fixing layer 45 is located between the body portion 411 and the diaphragm portion 221 of the substrate 41. In this embodiment, the fixing layer 45 is located on the back surface of the main body 411 of the substrate 41. The anchor layer 45 has a certain thickness in the axial direction. The fixing layer 45 of the present embodiment is a double-sided tape. The double-sided tape is obtained by molding a material having adhesive force into a tape shape and curing the tape to such an extent that the shape can be maintained.

As shown in fig. 19, when the flexible gear 20 is viewed in the axial direction, the anchor layer 45 is located in a region avoiding the radially outer folded-back portion rb1 of the eighteenth resistance line pattern R18 and the radially inner folded-back portion rb2 of the nineteenth resistance line pattern R19. In other words, the anchor layer 45 is located in all regions of the back surface of the diaphragm portion 221 except for a region facing the radially outer folded-back portion rb1 of the eighteenth resistance line pattern R18 and a region facing the radially inner folded-back portion rb2 of the nineteenth resistance line pattern R19. With this configuration, the strain of the diaphragm portion 221 can be suppressed from being transmitted to the radially outer folded portion rb1 of the eighteenth resistance line pattern R18 and the radially inner folded portion rb2 of the nineteenth resistance line pattern R19. Therefore, stress applied to the radially outer folded-back portion rb1 of the eighteenth resistance line pattern R18 and the radially inner folded-back portion rb2 of the nineteenth resistance line pattern R19 can be reduced, and disconnection of the resistance line patterns R18 and R19 can be suppressed.

On the other hand, in the main body 411 of the substrate 41, since the regions facing the eighteenth resistance line r18 and the nineteenth resistance line r19 are fixed to the diaphragm portion 221 via the fixing layer 45, the strain of the diaphragm portion 221 is transmitted to the eighteenth resistance line r18 and the nineteenth resistance line r19 in a favorable manner. Therefore, the torque applied to the entire circumference of the circular body can be detected with high accuracy.

< 9-3. summarization >

As described above, the torque detection sensor 40 of the present embodiment includes the substrate 41 and the anchor layer 45. The fixing layer 45 is located between the body portion 411 of the substrate 41 and the flexible gear 20. When the flexible gear 20 is viewed in the axial direction, the fixing layer 45 is located in a region avoiding the folded-back portions rb1 and rb 2. Thereby, the strain of the flexible gear 20 can be suppressed from being transmitted to the folded-back portion rb1 of the resistance line pattern R18, the folded-back portion rb2 of the resistance line pattern R19. Therefore, disconnection of the resistance line pattern R18 and the resistance line pattern R19 can be suppressed.

In the torque detection sensor 40 of the present embodiment, the anchor layer 45 has a thickness in the axial direction. Thus, the folded-back portion rb1 of the resistance line pattern R18 and the folded-back portion rb2 of the resistance line pattern R19 face the flexible gear 20 with air interposed therebetween, for example. Therefore, the strain of the flexible gear 20 can be suppressed from being transmitted to the folded-back portions rb1, rb 2. As a result, disconnection of the resistance line pattern R18 and the resistance line pattern R19 can be suppressed.

In the torque detection sensor 40 of the present embodiment, the fixing layer 45 is a double-sided tape. This makes it possible to easily attach the substrate 41 of the torque detection sensor 40 to the flexible gear 20.

< 10. eighth embodiment >

The power transmission device 1 according to the eighth embodiment is explained below with reference to fig. 20. In the following description, the same components as those in the above-described embodiment in terms of their configurations and functions will be denoted by the same reference numerals as those in the above-described embodiment, and redundant description thereof will be omitted.

Fig. 20 is a sectional view of a torque detection sensor 240 of the eighth embodiment. As shown in fig. 20, the torque detection sensor 240 includes a substrate 41 having a fourth conductor layer L4, a fixing layer 45, and a spacer 46. The fixing layer 45 is located between the body portion 411 and the diaphragm portion 221 of the substrate 41. The anchor layer 45 is located on the back surface of the substrate 41. The anchor layer 45 has a certain thickness in the axial direction. In the present embodiment, the fixing layer 45 is also a double-sided tape.

When the flexible gear 20 is viewed in the axial direction, the spacer 46 is located in a region other than the anchor layer 45. Specifically, the spacer 46 is located in a region of the back surface of the substrate 41 that faces the radially outer folded portion rb1 of the eighteenth resistance line pattern R18 and the radially inner folded portion rb2 of the nineteenth resistance line pattern R19. The spacer 46 is formed of a material having a lower friction than the material of the anchor layer 45. The spacer 46 is not fixed to the back surface of the substrate 41.

As described above, the torque detection sensor 240 of the present embodiment includes the spacer 46. Thus, in the substrate 41, a portion including the folded-back portion rb1 of the resistance line pattern R18 and the folded-back portion rb2 of the resistance line pattern R19 contacts the spacer 46, for example. The spacer 46 is not fixed to the back surface of the substrate 41. Thus, even if the flexible gear 20 is strained, the folded-back portion rb1 of the resistance line pattern R18 and the folded-back portion rb2 of the resistance line pattern R19 are less likely to be strained. Therefore, the stress applied forcibly to the fold back portion rb1 and the fold back portion rb2 can be suppressed, and disconnection of the resistance line pattern R18 and the resistance line pattern R19 can be suppressed.

< 11 > ninth embodiment

Hereinafter, the power transmission device 1 according to the ninth embodiment will be described with reference to fig. 21.

Fig. 21 is a sectional view of a torque detection sensor 340 of the ninth embodiment. As shown in fig. 21, the torque detection sensor 340 includes the substrate 41 having the fourth conductor layer L4, the anchor layer 45, and the second anchor layer 48. The fixing layer 45 is located between the body portion 411 and the diaphragm portion 221 of the substrate 41. The fixing layer 45 is located on the back surface of the body portion 411 of the substrate 41. The anchor layer 45 has a certain thickness in the axial direction. The anchor layer 45 of the present embodiment is formed of a material having lower fluidity than the material of the second anchor layer 48.

When the flexible gear 20 is viewed in the axial direction, the second anchor layer 48 is located in a region other than the anchor layer 45. Specifically, the second anchor layer 48 is located in a region of the back surface of the substrate 41 that faces the radially outer folded portion rb1 of the eighteenth resistance line pattern R18 and the radially inner folded portion rb2 of the nineteenth resistance line pattern R19. The second anchor layer 48 is formed of a material having higher fluidity than the material of the anchor layer 45.

The second anchor layer 48 is less likely to transmit strain of the diaphragm portion 221 to the substrate 41 than the anchor layer 45. Therefore, compared to the case where the anchor layer 45 is present on the entire back surface of the substrate 41, the structure of the present embodiment can also suppress stress concentration on the radially outer folded portion rb1 of the eighteenth resistance line pattern R18 and the radially inner folded portion rb2 of the nineteenth resistance line pattern R19. Therefore, disconnection of the resistance line pattern R18 and the resistance line pattern R19 can be suppressed.

< 12 > variations of the seventh to ninth embodiments

Next, a power transmission device 1 according to a modification of the seventh to ninth embodiments will be described with reference to fig. 22.

Fig. 22 is a sectional view of a torque detection sensor 440 according to a modification of the seventh to ninth embodiments. As shown in fig. 22, the torque detection sensor 440 includes the substrate 41 having the fourth conductor layer L4 and the anchor layer 49. The fixing layer 49 is located between the body portion 411 and the diaphragm portion 221 of the substrate 41. The anchor layer 49 is located on a part of the back surface of the body portion 411 of the substrate 41. The anchor layer 49 has a certain thickness in the axial direction.

The diaphragm portion 221 of the flexible gear 20 is located on the opposite side of the main body 411 of the substrate 41 with the fixing layer 49 interposed therebetween. The width of the diaphragm portion 221 in the radial direction is substantially equal to the width of the anchor layer 49 in the radial direction. On the other hand, the radial widths of the fourth conductor layer L4 and the body portion 411 are longer than the radial widths of the diaphragm portion 221 and the anchor layer 49. Specifically, the fixing layer 49 is bonded to the back surface of the main body portion 411 of the substrate 41 in a state in which a region facing the radially outer folded portion rb1 of the eighteenth resistance line pattern R18 and a region facing the radially inner folded portion rb2 of the nineteenth resistance line pattern R19 protrude in the radial direction. On the other hand, the adhesive layer 49 is bonded to a region facing the eighteenth resistance line R18 and the nineteenth resistance line R19, a region facing the radially inner folded portion rb1 of the eighteenth resistance line pattern R18, and a region facing the radially outer folded portion rb2 of the nineteenth resistance line pattern R19 on the back surface of the main body portion 411 of the substrate 41.

Thus, the region of the fourth conductor layer L4 corresponding to the sensing portion for torque detection is fixed to the diaphragm portion 221 via the body portion 411 and the fixing layer 49. On the other hand, in the fourth conductor layer L4, the radially outer folded portion rb1 of the eighteenth resistance line pattern R18 and the radially inner folded portion rb2 of the nineteenth resistance line pattern R19, which are supposed to be fixed to the diaphragm portion 221 so that stress is easily concentrated, are not fixed to the diaphragm portion 221. As a result, it is possible to suppress the occurrence of disconnection in the folded-back portion rb1 on the outer side in the radial direction of the eighteenth resistance line pattern R18 and the folded-back portion rb2 on the inner side in the radial direction of the nineteenth resistance line pattern R19.

< 13 > other modifications of the seventh to ninth embodiments

The seventh to ninth embodiments of the present invention have been described above, but the present invention is not limited to the above embodiments.

In the embodiment, the anchor layers 45 and 49 have a thickness in the axial direction. However, not limited thereto, the anchor layer may not have a thickness in the axial direction. In this case, if the region of the back surface of the substrate corresponding to the folded portion is not fixed to the diaphragm portion, the strain of the diaphragm portion can be prevented from being directly transmitted to the folded portion. As a result, disconnection of the resistance line pattern can be suppressed.

< 14. tenth embodiment >

Hereinafter, the power transmission device 1 of the tenth embodiment will be described. Fig. 23 and 24 are plan views of the torque detection sensor 40 viewed in the axial direction.

A wheatstone bridge circuit 42 including a twentieth resistance line pattern R20 and a twenty-first resistance line pattern R21, and a signal processing circuit 43 are mounted on the substrate 41. The twentieth resistance line pattern R20 is disposed on a surface of the front and back surfaces of the body portion 411 that does not face the diaphragm portion 221. The twenty-first resistance line pattern R21 is disposed on the back surface of the body portion 411, which is opposite to the diaphragm portion 221. The twentieth resistance line pattern R20 and the twenty-first resistance line pattern R21 are disposed at positions overlapping each other when viewed in the axial direction, and are disposed on concentric circles. The signal processing circuit 43 is disposed on the flap portion 412. Further, the illustration of the twentieth resistance line pattern R20 is omitted in fig. 24, and the twenty-first resistance line pattern R21 is indicated by a broken line.

The twentieth resistance line pattern R20 is a pattern in which one conductor extends in the circumferential direction while being bent in a zigzag manner, and is entirely arc-shaped or annular. In the present embodiment, the twentieth resistance line pattern R20 is provided in a range of about 360 ° around the center axis 9. The twentieth resistance line pattern R20 includes a plurality of twentieth resistance lines R20 and a plurality of first fold portions rc 1. The twentieth resistance wires r20 are arranged in a substantially parallel posture to each other in the circumferential direction. Each twentieth resistance line r20 is inclined to one side in the circumferential direction with respect to the radial direction of the flexible gear 20. The first folded back portions rc1 alternately connect the ends of the twentieth resistance lines r20 adjacent in the circumferential direction to each other on both sides in the radial direction. Thus, the plurality of twentieth resistance wires r20 are connected in series as a whole.

The twenty-first resistance line pattern R21 is a pattern in which one conductor extends in the circumferential direction while being bent in a zigzag manner, and is entirely circular-arc-shaped or annular. In the present embodiment, a twenty-first resistance line pattern R21 is provided in a range of about 360 ° around the center axis 9. Also, the twenty-first resistance line pattern R21 includes a plurality of twenty-first resistance lines R21 and a plurality of second folding portions rc 2. The twenty-first resistance lines r21 are arranged in a substantially parallel posture with respect to each other in the circumferential direction. Each twenty-first resistance line r21 is inclined to the other side in the circumferential direction with respect to the radial direction of the flexible gear 20. The second fold back portions rc2 alternately connect the ends of twenty-first resistance lines r21 adjacent in the circumferential direction to each other on both sides in the radial direction. Thus, the plurality of twenty-first resistance wires r21 are connected in series as a whole.

< 15. Angle of inclination with respect to resistance line Pattern >

Fig. 25 is a plan view of a part of the torque detection sensor 40 viewed in the axial direction. As shown in fig. 25, the twentieth resistance line R20 of the twentieth resistance line pattern R20 is inclined at a certain inclination angle α to one side in the circumferential direction with respect to the radial direction of the flexible gear 20. At this time, the twenty-first resistance line R21 of the twenty-first resistance line pattern R21 is inclined at a certain inclination angle α to the other side in the circumferential direction with respect to the radial direction. The inclination angle α is an angle at which the resistance line extends in the radial direction at the midpoint of each resistance line. In the torque detection sensor 40 of the present embodiment, the inclination angle α is set to a certain angle larger than 45 ° and smaller than 90 °.

When the power transmission device 1 operates, the cam 31 rotates, and the cylindrical portion 21 of the flexible gear 20 deforms into an elliptical shape. With the deformation, a radial strain rr and a circumferential strain θ θ are generated in the diaphragm portion 221. The radial strain rr is greater than the circumferential strain theta. In the case where these strains rr, θ do not apply a torque to the compliant gear 20, the compliant gear 20 may also be elliptically deformed. That is, the diaphragm portion 221 is subjected to the radial and circumferential strains rr and θ θ caused by the elliptical deformation of the flexible gear 20, regardless of the strain caused by the torque to be measured. Therefore, the detection value of the torque detection sensor 40 includes a component reflecting the torque to be originally measured and an error component due to the strains rr and θ θ.

Fig. 26 is a graph showing a relationship between the inclination angle α of the twentieth resistance line r20 and the twenty-first resistance line r21 and the error component due to the strain rr and the strain θ θ. The horizontal axis of fig. 26 represents the inclination angle α of the twentieth resistance line r20 and the twenty-first resistance line r 21. The vertical axis of fig. 26 represents the absolute value of the value obtained by normalizing the error component of the detection value of the torque detection sensor 40 with the detection sensitivity of the torque to be originally measured. That is, in the graph of fig. 26, the detection sensitivity of the torque to be originally measured is S, and the error component of the detection value of the torque detection sensor 40 is a value representing |/S |.

The torque detection sensitivity S is a ratio of an output signal to an input signal (strain due to load torque). The torque detection sensitivity S is maximized at α ═ 45 °, and can be represented by S ═ sin2 α. Further, an error component of the detection value of the torque detection sensor 40 may be represented by 1/2{ rr + θ θ + (rr- θ θ) cos2 α }. Therefore, the graph of fig. 26 is a graph of |/S | ═ 1/2S { | + | θ θ θ | + (| rr | - | θ |) cos2 α } -, 1/2sin2 α { | + | rr | + | θ θ | + (| rr | - | θ |) cos2 α }.

A line graph PT1 in fig. 26 shows a change in |/S | when the ratio of the strain rr to the strain θ θ is rr/θ θ equals 1. A line graph PT2 in fig. 26 shows a change in |/S | when the ratio of the strain rr to the strain θ θ is rr/θ θ equal to 2. A line graph PT3 in fig. 26 shows a change in |/S | when the ratio of the strain rr to the strain θ θ is rr/θ θ equal to 3. A line graph PT4 in fig. 26 shows a change in |/S | when the ratio of the strain rr to the strain θ θ is rr/θ θ equal to 4.

From the results of fig. 26, in the graph PT1, the value of | S | is the smallest when the inclination angle α of the twentieth resistance line r20 and the twenty-first resistance line r21 is 45 °. In contrast, in the graphs PT2, PT3, and PT4, the value of | S | is the smallest when the inclination angle α is an angle greater than 45 ° and smaller than 90 °, not 45 °. Specifically, in the line graph PT2, the value of |/S | is the smallest when α is 54.7 °, in the line graph PT3, the value of |/S | is the smallest when α is 60 °, and in the line graph PT4, the value of |/S | is the smallest when α is 63.4 °.

Fig. 27 is a graph showing the result of examining the inclination angle α at which the value of |/S | becomes minimum by changing the ratio rr/θ θ of the strain rr and the strain θ θ more finely. The horizontal axis of fig. 27 represents the ratio rr/θ θ of the strain rr to the strain θ θ. The vertical axis of fig. 27 represents the inclination angle α at which the value of |/S | becomes minimum. As shown in fig. 27, when the strain rr in the radial direction is larger than the strain θ θ θ in the circumferential direction (when rr/θ θ > 1), the inclination angle α at which the error component is minimized is an angle larger than 45 ° and smaller than 90 °. Particularly for the flexible gear 20, the ratio rr/θ θ is usually in the range of 1.5 to 7.5. Therefore, according to the graph of fig. 27, the inclination angle α of the twentieth resistance line r20 and the twenty-first resistance line r21 is preferably 50 ° or more and 70 ° or less. In addition, the ratio rr/θ θ of the flexible gear 20 is in a range of 2.0 to 3.5 in many cases. Therefore, according to the graph of fig. 27, the inclination angle α of the twentieth resistance line r20 and the twenty-first resistance line r21 is more preferably 54 ° or more and 62 ° or less.

In this way, if the inclination angle α of the twentieth resistance line r20 and the twenty-first resistance line r21 is set to a constant angle greater than 45 ° and smaller than 90 °, an error component caused by the periodic elliptical deformation of the flexible gear 20 in the detection value of the torque detection sensor 40 can be suppressed. Therefore, the torque applied to the flexible gear 20 can be detected with higher accuracy using the torque detection sensor 40.

Further, by setting the inclination angle α of the twentieth resistance line R20 and the twenty-first resistance line R21 to a certain angle larger than 45 ° and smaller than 90 °, the radial dimensions of the twentieth resistance line pattern R20 and the twenty-first resistance line pattern R21 can be suppressed. This makes it possible to further reduce the size of the torque detection sensor 40 in the radial direction.

< 16. variation of the tenth embodiment

While one embodiment of the present invention has been described above, the present invention is not limited to the embodiment.

Case of < 16-1.rr < θ θ >

In the above embodiment, a case where the strain rr in the radial direction of the diaphragm portion 221 is larger than the strain θ θ θ in the circumferential direction is described. In contrast, a case where the radial strain rr of the diaphragm portion 221 is smaller than the circumferential strain θ θ is described below.

Fig. 28 is a graph showing a relationship between the inclination angle α of the twentieth resistance line r20 and the twenty-first resistance line r21 and the error component due to the strain rr and the strain θ θ in the case where rr < θ θ. A line graph PT1 in fig. 28 shows a change in |/S | when the ratio of the strain rr to the strain θ θ is rr/θ θ equal to 1. A line graph PT5 in fig. 28 shows a change in |/S | when the ratio of the strain rr to the strain θ θ is rr/θ θ 1/2. A line graph PT6 in fig. 28 shows a change in |/S | when the ratio of the strain rr to the strain θ θ is rr/θ θ 1/3. A line graph PT7 in fig. 28 shows a change in |/S | when the ratio of the strain rr to the strain θ θ is rr/θ θ 1/4.

From the results of fig. 28, in the line graph PT5, the line graph PT6, and the line graph PT7, the value of | S | is the smallest when the inclination angle α is an angle smaller than 45 ° and larger than 0 °, not 45 °. In this way, when the strain rr in the radial direction is smaller than the strain θ θ θ in the circumferential direction (when rr/θ θ < 1), the inclination angle α of the twentieth resistance line r20 and the twenty-first resistance line r21 is set to an angle smaller than 45 ° and larger than 0 °, whereby an error component caused by the periodic elliptical deformation of the flexible gear 20 in the detection value of the torque detection sensor 40 can be suppressed. Therefore, the torque applied to the flexible gear 20 can be detected with higher accuracy using the torque detection sensor 40.

< 16-2. other modifications

The torque detection sensor 40 according to the embodiment and the modified examples described above includes the twentieth resistance line pattern R20 and the twenty-first resistance line pattern R21, respectively. However, the torque detection sensor 40 may also include any one or both of the twentieth resistance line pattern R20 and the twenty-first resistance line pattern R21, which are two or more. That is, the conductor layer of the substrate 41 may include at least one of the twentieth resistance line pattern R20 and the twenty-first resistance line pattern R21. Also, the twentieth resistance line pattern R20 and a part of the twenty-first resistance line pattern R21 may be also incorporated into a circuit different from the wheatstone bridge circuit 42.

In the embodiment, the object to be detected is the flexible gear 20. However, the torque detection sensor 40 having the same configuration as that of the above-described embodiment may be used to detect a torque applied to a circular body other than the flexible gear 20. However, it is preferable that the circular body to be measured is periodically deformed while accompanied by radial strain and circumferential strain smaller than the radial strain.

[ Industrial availability ]

The torque detection sensor, the power transmission device and the robot comprising the power transmission device can be used for the torque detection sensor and the power transmission device.

Claims

1. A torque detecting sensor detects a torque applied to a circular body, and

the method comprises the following steps: a substrate having a conductive layer,

the conductor layer comprises a pattern of resistive lines,

the torque detection sensor is characterized in that,

the resistive line pattern includes: the circular arc-shaped or annular pattern is formed by arranging a plurality of resistance wires inclined towards one side of the circumferential direction relative to the radial direction of the circular body along the circumferential direction and connecting the resistance wires in series.

2. The torque detection sensor according to claim 1,

the substrate has a first conductive layer and a second conductive layer,

the first conductor layer and the second conductor layer respectively comprise resistance line patterns,

the resistance line pattern of at least either of the first conductor layer and the second conductor layer includes: and an arc-shaped or annular pattern in which a plurality of resistance wires inclined to one side in the circumferential direction with respect to the radial direction of the circular body are arranged in the circumferential direction and connected in series.

3. The torque detection sensor according to claim 2,

the substrate has a surface conductor layer and a back conductor layer,

the first conductor layer is any one of the surface conductor layer and the back conductor layer,

the second conductive layer is the other of the surface conductive layer and the back conductive layer.

4. The torque detection sensor according to claim 2,

the substrate has a surface conductive layer, a back conductive layer and an intermediate conductive layer,

the first conductor layer is any one of the surface conductor layer, the back conductor layer and the intermediate conductor layer,

the second conductive layer is any one of the surface conductive layer, the back conductive layer and the intermediate conductive layer.

5. The torque detection sensor according to claim 2,

the resistance line pattern of any other one of the first conductor layer and the second conductor layer includes: and an arc-shaped or annular pattern formed by connecting a plurality of resistance wires extending in the radial direction of the circular body in series and arranged in the circumferential direction.

6. The torque detection sensor according to any one of claims 2 to 5,

the resistance line pattern of at least one of the first conductor layer and the second conductor layer includes a pattern extending in an arc shape or a circular ring shape.

7. The torque detection sensor according to claim 1,

the resistive line pattern includes:

a plurality of resistance wires inclined at a predetermined angle to one side of the circumferential direction with respect to the radial direction of the circular body; and

a plurality of folded-back portions connecting end portions of the plurality of resistance wires to each other,

the plurality of resistance wires are arranged at equal intervals in the circumferential direction, end portions of the resistance wires adjacent in the circumferential direction are alternately connected by the folded portions on both sides in the radial direction and are connected in series as a whole,

the fold back portion has at least one gradual curve portion.

8. The torque detection sensor according to claim 7,

the inside shape of the gentle curve portion has a radius of curvature larger than a half of a distance between adjacent ones of the resistance lines.

9. The torque detection sensor according to claim 8,

the tangential direction of the inner shape of the gentle curve portion coincides with the radial direction of the circular body.

10. The torque detection sensor according to claim 9,

has a plurality of said gradual curves away from each other.

11. The torque detection sensor according to claim 10,

the folded-back portion includes a portion having an inner shape with a radius of curvature smaller than a half of the distance between adjacent ones of the gently curved portions.

12. The torque detection sensor according to claim 7,

the folded-back part is provided with a first slow bending part,

the center of curvature of the inner shape of the first gentle curve portion is located on the opposite side of the first gentle curve portion with an imaginary straight line passing through both ends of a line segment formed by connecting centers of circles having both adjacent resistance lines as tangents in order.

13. The torque detection sensor according to claim 12,

a tangential direction of an inner shape of the first gently curved portion coincides with the radial direction of the circular body.

14. The torque detection sensor according to claim 12 or 13,

the folded-back part is provided with a second slow bending part,

the center of curvature of the inner shape of the second gentle curve portion is located on the same side as the second gentle curve portion with respect to the virtual straight line.

15. The torque detection sensor according to any one of claims 7 to 13,

a curve that is formed by connecting the centers of inscribed circles inscribed in the inner shape of the folded portion in this order approaches the radial direction from the side of the resistance line toward the side of the folded portion.

16. The torque detection sensor according to any one of claims 7 to 13,

the width of the folded portion in the circumferential direction is shorter than the interval between the adjacent resistance lines in the circumferential direction.

17. The torque detection sensor according to claim 1, characterized by comprising:

a fixation layer located between the substrate and the circular body,

the resistive line pattern includes:

a plurality of resistance wires inclined at a certain angle to one side of the circumferential direction; and

the fixing layer is located in a region avoiding the folded-back portion when the circular body is viewed in the axial direction.

18. The torque detection sensor according to claim 17,

the anchor layer has a thickness in the axial direction.

19. The torque detection sensor according to claim 17 or 18,

the spacer is located between the substrate and the circular body and is not located in the region where the fixing layer is located when the circular body is viewed in the axial direction,

the spacer is not fixed to the substrate.

20. The torque detection sensor according to claim 17 or 18,

between the substrate and the circular body, and in a region where the fixing layer is not located when the circular body is viewed in the axial direction, further comprising: a second anchor layer having higher fluidity than the anchor layer.

21. The torque detection sensor according to claim 17 or 18,

the fixing layer is a double-sided adhesive tape.

22. The torque detection sensor according to claim 1,

the conductor layer contains at least one of the following resistor line patterns:

a first resistance line pattern of circular arc shape or circular ring shape; and

a circular arc or annular second resistance line pattern arranged on a concentric circle with the first resistance line pattern,

the first resistance line pattern includes:

a plurality of first resistance lines inclined at a predetermined angle to one side of the circumferential direction with respect to the radial direction of the circular body, the predetermined angle being greater than 0 ° and less than 45 °, or greater than 45 ° and less than 90 °; and

first folded portions connecting end portions of the first resistance lines adjacent in the circumferential direction alternately on both sides in the radial direction and connected in series as a whole,

the second resistance line pattern includes:

a plurality of second resistance wires inclined at the predetermined angle to the other side in the circumferential direction with respect to the radial direction of the circular body; and

and second folded portions that connect end portions of the second resistance lines adjacent in the circumferential direction alternately on both sides in the radial direction and are connected in series as a whole.

23. The torque detection sensor according to claim 22,

the certain angle is 50 ° or more and 70 ° or less.

24. The torque detecting sensor according to claim 23,

the predetermined angle is 54 ° or more and 62 ° or less.

25. The torque detection sensor according to any one of claims 1 to 5, 7 to 13, 17, 18, and 22 to 24,

the substrate is a double-sided flexible substrate.

26. The torque detection sensor according to any one of claims 1 to 5, 7 to 13, 17, 18, and 22 to 24,

the conductor layer is made of copper or copper-containing alloy.

27. The torque detection sensor according to any one of claims 1 to 5, 7 to 13, 17, 18, and 22 to 24,

the resistor line pattern is incorporated into a wheatstone bridge circuit.

28. The torque detection sensor according to claim 27, comprising:

and a signal processing circuit for detecting the torque applied to the circular body based on the output signal of the Wheatstone bridge circuit.

29. The torque detecting sensor according to claim 28,

the signal processing circuit is mounted on the substrate or a substrate different from the substrate.

30. A power transmission device characterized by comprising:

the torque detection sensor of any one of claims 1 to 5, 7 to 13, 17, 18, and 22 to 24; and

the circular body.

31. The power transmission device according to claim 30,

either one of the circular body and the substrate has: and a positioning portion that is in contact with any one of the circular body and the substrate in the radial direction.

32. The power transmission device according to claim 30,

the circular body has:

a flexible cylindrical portion extending in a cylindrical shape in an axial direction;

a plurality of external teeth provided on an outer peripheral surface of the cylindrical portion; and

a flat plate-like diaphragm portion extending from one side of the cylindrical portion in the axial direction toward the outside in the radial direction or the inside in the radial direction,

the substrate is fixed to the diaphragm portion.

33. A robot, comprising:

the power transmission device of claim 30.