A rotation angle detection sensor, a torque detection sensor, and a power transmission device

Abstract

Provided are a rotation angle detection sensor, a torque detection sensor, and a power transmission device. The rotation angle detection sensor includes a substrate having a conductor layer. The conductor layer includes a plurality of first resistance line patterns arranged at equal intervals in a circumferential direction, and a plurality of second resistance line patterns arranged at equal intervals in a region in which the first resistance line patterns are not arranged in the circumferential direction in a concentric circular shape. The first resistance line pattern is a pattern in which first resistance lines extending in either one of a radial direction and a circumferential direction are connected in series. The second resistance line pattern is a pattern in which second resistance lines extending in either one of a radial direction and a circumferential direction are connected in series. Based on changes in resistance values of the first resistance line patterns and the second resistance line patterns, a rotation angle of a rotational motion input to a circular body can be detected.

Description

TECHNICAL FIELD

[0001] The present application relates to a rotation angle detection sensor, a torque detection sensor, and a power transmission device. BACKGROUND

[0002] In recent years, there has been a rapid increase in demand for speed reducers mounted on joints of robots and the like. As for a conventional speed reducer, for example, Japanese Patent Application Publication No. 2004-198400 is described. In this publication, a strain gauge is attached to a flexible external gear that rotates at a reduced rotational speed. Thus, it is possible to detect the torque applied to the flexible external gear.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2004-198400

[0004] However, the flexible external gear used in such a speed reducer repeatedly undergoes periodic flexural deformation. Therefore, the output value of the strain gauge contains a component caused by the torque to be measured and an error component caused by the periodic deformation of the flexible external gear. This error component varies depending on the rotation angle of the rotational motion input to the flexible external gear. Therefore, in order to accurately measure the torque, it is necessary to eliminate the error component corresponding to the rotation angle from the output value of the strain gauge.

[0005] However, in the conventional configuration, the strain gauge itself cannot detect the rotation angle of the rotational motion input to the flexible external gear. Therefore, in order to calculate the above-described error component, it is necessary to obtain information on the rotation angle from a motor connected to the speed reducer. SUMMARY

[0006] An object of the present application is to provide a rotation angle detection sensor that can detect the rotation angle of a rotational motion input to a circular body such as a flexible external gear.

[0007] The present application is a rotation angle detection sensor that detects a rotation angle of a rotational motion input to a circular body, wherein the rotation angle detection sensor includes a substrate having a conductor layer, the conductor layer including: a plurality of first resistance line patterns arranged at equal intervals in a circumferential direction; and a plurality of second resistance line patterns arranged at equal intervals in a region in which the first resistance line patterns are not arranged in the circumferential direction in a concentric circular shape with the first resistance line patterns, the first resistance line pattern being a pattern in which first resistance lines extending in either one of a radial direction and a circumferential direction are connected in series, and the second resistance line pattern being a pattern in which second resistance lines extending in the one direction are connected in series.

[0008] According to the present application, based on changes in the resistance values of the plurality of first resistance line patterns and the plurality of second resistance line patterns, it is possible to detect the rotation angle of the rotational motion input to the circular body. BRIEF DESCRIPTION OF DRAWINGS

[0009] Figure 1 is a longitudinal sectional view of a power transmission apparatus.

[0010] Figure 2 is a transverse sectional view of a power transmission apparatus.

[0011] Figure 3 is a view showing the back surface of a torque detection sensor.

[0012] Figure 4 is a view showing the front surface of a torque detection sensor.

[0013] Figure 5 is a partial sectional view of a diaphragm portion and a torque detection sensor.

[0014] Figure 6 is a circuit diagram of a first Wheatstone bridge circuit.

[0015] Figure 7 is a circuit diagram of a second Wheatstone bridge circuit.

[0016] Figure 8 is a graph showing the measured values of a first voltage meter and a second voltage meter.

[0017] Figure 9 is a circuit diagram of a third Wheatstone bridge circuit.

[0018] Figure 10 is a view conceptually showing a correction process.

[0019] Figure 11 is a view showing the back surface of a torque detection sensor of a modification.

[0020] Explanation of Reference Signs

[0021] 1: Power transmission device; 9: Central axis; 10: Internal gear; 20: Flexible gear; 21: Cylindrical part; 22: Flat part; 23: External gear; 30: Wave generator; 40: Torque detection sensor; 41: Circuit board; 42: Insulating layer; 43: Conductor layer; 44: Double-sided adhesive tape; 221: Diaphragm part; 222: Thick-walled part; 411: Main body part; 412: Baffle part; C1: First Wheatstone bridge circuit; C2: Second Wheatstone bridge circuit; Ct: Third Wheatstone bridge circuit; P1: Rotary P2: Resistance wire pattern for angle detection; P3: Resistance wire pattern for torque detection; P4: Resistance wire pattern for temperature detection; R1, Ra~Rd: First resistance wire pattern; R2, Re~Rh: Second resistance wire pattern; R3: Third resistance wire pattern; R4: Fourth resistance wire pattern; Rs: Fixed resistor; V1: First voltmeter; V2: Second voltmeter; Vt: Third voltmeter; r1: First resistance wire; r2: Second resistance wire; r3: Third resistance wire; r4: Fourth resistance wire. Detailed Implementation

[0022] In the following description, exemplary embodiments of this application will be illustrated with reference to the accompanying drawings. Furthermore, in this application, the direction parallel to the central axis of the power transmission device is referred to as the "axial direction," the direction perpendicular to the central axis of the power transmission device is referred to as the "radial direction," and the direction along an arc centered on the central axis of the power transmission device is referred to as the "circumferential direction." The term "parallel direction" also includes substantially parallel directions. Similarly, the term "perpendicular direction" also includes substantially perpendicular directions.

[0023] <1. Structure of the power transmission device>

[0024] Figure 1 This is a longitudinal sectional view of the power transmission device 1 according to the first embodiment. Figure 2 From Figure 1 The image shows a cross-sectional view of the power transmission device 1 as viewed from position AA. This power transmission device 1 is a device that reduces rotational motion from a first speed derived from a motor to a second speed lower than the first speed and transmits it to the next stage. The power transmission device 1 is used, for example, in conjunction with a motor in the joints of a robot. However, the power transmission device of the present invention can also be used in other devices such as auxiliary equipment and automated guided vehicles.

[0025] like Figure 1 and Figure 2 As shown, the power transmission device 1 of this embodiment includes an internal gear 10, a flexible gear 20, a wave generator 30, and a torque detection sensor 40.

[0026] The ring gear 10 is a ring-shaped gear having a plurality of internal teeth 11 on an inner peripheral surface. The ring gear 10 is fixed to a frame of a device in which the power transmission device 1 is installed, for example, by a screw. The ring gear 10 is disposed coaxially with the center axis 9. In addition, the ring gear 10 is located radially outward of a later-described cylindrical portion 21 of the flexible gear 20. The rigidity of the ring gear 10 is much higher than the rigidity of the cylindrical portion 21 of the flexible gear 20. Therefore, the ring gear 10 can be regarded as a rigid body substantially. The ring gear 10 has a cylindrical inner peripheral surface. The plurality of internal teeth 11 are arranged at a certain interval in the circumferential direction on the inner peripheral surface. Each of the internal teeth 11 protrudes toward the radially inner side.

[0027] The flexible gear 20 is a ring-shaped gear having flexibility. The flexible gear 20 is supported so as to be rotatable about the center axis 9. The flexible gear 20 is an example of the "circular body" in the present application.

[0028] The flexible gear 20 of the present embodiment has 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 front end in the axial direction of the cylindrical portion 21 is located radially outward of the wave generator 30 and radially inward of the ring gear 10. Since the cylindrical portion 21 has flexibility, it can be deformed in the radial direction. In particular, since the front end portion of the cylindrical portion 21 located radially inward of the ring gear 10 is a free end, it can be displaced in the radial direction more than other portions.

[0029] The flexible gear 20 has a plurality of external teeth 23. The plurality of external teeth 23 are arranged at a certain interval in the circumferential direction on the outer peripheral surface near the front end portion in the axial direction of the cylindrical portion 21. Each of the external teeth 23 protrudes toward the radially outer side. The number of the internal teeth 11 possessed by the above-described ring gear 10 is slightly different from the number of the external teeth 23 possessed by the flexible gear 20.

[0030] The flat plate portion 22 has a diaphragm portion 221 and a thick wall portion 222. The diaphragm portion 221 expands in a flat plate shape toward the radially outer side from the base end portion in the axial direction of the cylindrical portion 21 and expands in a ring shape with the center axis 9 as the center. The diaphragm portion 221 can be slightly flexibly deformed in the axial direction. The thick wall portion 222 is a ring-shaped portion located radially outward of the diaphragm portion 221. The axial thickness of the thick wall portion 222 is thicker than the axial thickness of the diaphragm portion 221. The thick wall portion 222 is fixed to a component of a device on which the power transmission device 1 is mounted, which is a target of driving, for example, by a screw.

[0031] The wave generator 30 is a mechanism that causes the cylindrical portion 21 of the flexible gear 20 to generate a periodic flexural deformation. The wave generator 30 has a cam 31 and a flexible bearing 32. The cam 31 is supported so as to be able to rotate about the center axis 9. The cam 31 has an elliptical outer peripheral surface when 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. Thus, the cam 31 and the cylindrical portion 21 are able to rotate at different rotational speeds.

[0032] The inner ring of the flexible bearing 32 is in contact with the outer peripheral surface of the cam 31. The outer ring of the flexible bearing 32 is in contact with the inner peripheral surface of the flexible gear 20. Thus, 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, at two portions corresponding to the both ends of the major axis of the ellipse, the external teeth 23 of the flexible gear 20 engage with the internal teeth 11 of the internal gear 10. At other positions in the circumferential direction, the external teeth 23 do not engage with the internal teeth 11.

[0033] The cam 31 is connected to the motor directly or through other power transmission mechanisms. If the motor is driven, the cam 31 rotates about the center axis 9 at a first rotational speed. By this, the major axis of the above-described ellipse of the flexible gear 20 also rotates at the first rotational speed. In this way, the engagement positions of the external teeth 23 and the internal teeth 11 also change in the circumferential direction at the first rotational speed. In addition, as described above, the number of the internal teeth 11 of the intermediate gear 10 is slightly different from the number of the external teeth 23 of the flexible gear 20. According to this difference in the number of teeth, the engagement positions of the external teeth 23 and the internal teeth 11 change slightly in the circumferential direction every time the cam 31 rotates one revolution. Thus, the flexible gear 20 rotates about the center axis 9 relative to the internal gear 10 at a second rotational speed that is lower than the first rotational speed. Thus, it is possible to obtain a rotational motion at the second rotational speed after deceleration from the flexible gear 20.

[0034] <2. Torque detection sensor>

[0035] <2-1. Structure of torque detection sensor>

[0036] The torque detection sensor 40 is a sensor that detects a circumferential torque applied to the flexible gear 20. As shown in FIG. 9, in the present embodiment, the torque detection sensor 40 is fixed to the circular surface of the diaphragm portion 221 that is a circular plate. Figure 1

[0037] Figure 3 FIG. 10 is a view showing the back surface of the torque detection sensor 40 that opposes the diaphragm portion 221 among the front surface and the back surface of the torque detection sensor 40.

[0038] Figure 4 FIG. 11 is a view showing the surface of the torque detection sensor 40 that does not oppose the diaphragm portion 221 among the front surface and the back surface of the torque detection sensor 40.

[0039] Figure 5 ​is a partial cross-sectional view of the diaphragm portion 221 and the torque detection sensor 40.

[0040] As shown in Figures 3 to 5 , the torque detection sensor 40 has a circuit board 41. The circuit board 41 of the present embodiment is a flexible printed board (FPC) that can be deformed softly. The circuit board 41 has a circular ring-shaped main portion 411 that is centered on the center axis 9 and a baffle portion 412 that protrudes from the main portion 411 to the outer side in the radial direction.

[0041] As shown in Figure 5 , the circuit board 41 of the torque detection sensor 40 has an insulating layer 42 and a conductor layer 43. The insulating layer 42 is composed of a resin that is an insulator. The conductor layer 43 is composed of a metal that is a conductor. The material of the conductor layer 43 uses, for example, copper or an alloy containing copper. The circuit board 41 of the present embodiment has the conductor layer 43 on both the front surface and the back surface of the insulating layer 42.

[0042] In addition, as shown in Figure 5 , the torque detection sensor 40 is fixed to the diaphragm portion 221 of the flexible gear 20 by a double-sided adhesive tape 44. Specifically, the surface of the diaphragm portion 221 and the back surface of the circuit board 41 are fixed by the double-sided adhesive tape 44. The double-sided adhesive tape 44 is a material that is molded into a tape shape and cured to a degree that the shape can be maintained. If such a double-sided adhesive tape 44 is used, the fixing work of the torque detection sensor 40 with respect to the diaphragm portion 221 becomes easy compared to the case where an adhesive having fluidity is used. In addition, it is possible to reduce the deviation of the fixing work of the worker.

[0043] In addition, in order to transmit the deformation of the diaphragm portion 221 to the torque detection sensor 40 with high precision, it is preferable that the double-sided adhesive tape 44 does not have a base film and is composed only of an adhesive material.

[0044] The rotation angle detection resistance pattern P1, the torque detection resistance pattern P2, and a signal processing circuit P3 are mounted on the circuit board 41. The rotation angle detection resistance pattern P1 is disposed on the back surface of the main portion 411 that opposes the diaphragm portion 221 among the front surface and the back surface. That is, the conductor layer 43 on the back surface side includes the rotation angle detection resistance pattern P1. The torque detection resistance pattern P2 is disposed on the surface of the main portion 411 that does not oppose the diaphragm portion 221 among the front surface and the back surface. That is, the conductor layer 43 on the surface side includes the torque detection resistance pattern P2. The signal processing circuit P3 is disposed on the baffle portion 412.

[0045] <2-2. Regarding the rotation angle detection function>

[0046] The rotation angle detection resistance pattern P1 is a pattern for detecting the rotation angle of the rotational motion input to the flexible gear 20. As shown inFigure 3 As shown, the rotation angle detection resistance line pattern P1 includes four first resistance line patterns R1 and four second resistance line patterns R2.

[0047] The four first resistance line patterns R1 are arranged at equal intervals in the circumferential direction around the center axis 9. The first resistance line pattern R1 is a pattern in which one conductor is bent in a zigzag manner and extends in the circumferential direction, and is a circular arc as a whole. In the present embodiment, one first resistance line pattern R1 extends over an angle of about 45° around the center axis 9. Further, the first resistance line pattern R1 includes a plurality of first resistance lines r1. The plurality of first resistance lines r1 are arranged at small intervals in the circumferential direction. Each first resistance line r1 extends linearly in the radial direction of the flexspline 20. The end portions of the first resistance lines r1 adjacent in the circumferential direction are alternately connected to each other on the inner side or the outer side in the radial direction. Thus, the plurality of first resistance lines r1 are connected in series as a whole.

[0048] The four second resistance line patterns R2 are arranged at equal intervals in the circumferential direction around the center axis 9. The second resistance line pattern R2 is a pattern in which one conductor is bent in a zigzag manner and extends in the circumferential direction, and is a circular arc as a whole. In the present embodiment, one second resistance line pattern R2 extends over an angle of about 45° around the center axis 9. Further, the second resistance line pattern R2 includes a plurality of second resistance lines r2. The plurality of second resistance lines r2 are arranged at small intervals in the circumferential direction. Each second resistance line r2 extends linearly in the radial direction of the flexspline 20. The end portions of the second resistance lines r2 adjacent in the circumferential direction are alternately connected to each other on the inner side or the outer side in the radial direction. Thus, the plurality of second resistance lines r2 are connected in series as a whole.

[0049] The four second resistance line patterns R2 are concentric with the first resistance line patterns R1, and are arranged in regions in which the first resistance line patterns R1 are not arranged in the circumferential direction. In the present embodiment, the first resistance line patterns R1 and the second resistance line patterns R2 are alternately arranged in the circumferential direction. Further, the four first resistance line patterns R1 and the four second resistance line patterns R2 extend in a circular ring shape as a whole with the center axis 9 as the center.

[0050] Figure 6 is a circuit diagram of the first Wheatstone bridge circuit C1 including the four first resistance line patterns R1. In Figure 6 the example, the four first resistance line patterns R1 are distinguished as Ra, Rb, Rc, and Rd. The first resistance line patterns Ra, Rb, Rc, and Rd are arranged in the order of Ra as the first one, in the counterclockwise direction, in Figure 3

[0051] As shown in FIG. 6, the first resistance line pattern Ra includes a plurality of first resistance lines r1. The plurality of first resistance lines r1 are arranged at small intervals in the circumferential direction. Each first resistance line r1 extends linearly in the radial direction of the flexspline 20. The end portions of the first resistance lines r1 adjacent in the circumferential direction are alternately connected to each other on the inner side or the outer side in the radial direction. Thus, the plurality of first resistance lines r1 are connected in series as a whole. Figure 6 ​As shown, the four first resistance line patterns Ra, Rb, Rc, Rd are incorporated in the first Wheatstone bridge circuit C1. The first resistance line pattern Ra and the first resistance line pattern Rb are connected in series in this order. The first resistance line pattern Rd and the first resistance line pattern Rc are connected in series in this order. And, between the power supply voltage + and - poles, the two series of the first resistance line patterns Ra, Rb and the two series of the first resistance line patterns Rd, Rc are connected in parallel. The midpoints M11 of the first resistance line patterns Ra and Rb and the midpoints M12 of the first resistance line patterns Rd and Rc are connected to the first voltmeter V1.

[0052] Figure 7 is a circuit diagram of a second Wheatstone bridge circuit C2 including four second resistance line patterns R2. In Figure 7 the example, the four second resistance line patterns R2 are distinguished as Re, Rf, Rg, Rh. In Figure 3 , the second resistance line pattern Re is located between the first resistance line pattern Ra and the first resistance line pattern Rd. In addition, the second resistance line patterns Re, Rf, Rg, Rh are arranged in this order clockwise with Re as the first one. Figure 3

[0053] As shown, the four second resistance line patterns Re, Rf, Rg, Rh are incorporated in the second Wheatstone bridge circuit C2. The second resistance line pattern Re and the second resistance line pattern Rf are connected in series in this order. The second resistance line pattern Rh and the second resistance line pattern Rg are connected in series in this order. And, between the power supply voltage + and - poles, the two series of the second resistance line patterns Re, Rf and the two series of the second resistance line patterns Rh, Rg are connected in parallel. In addition, the midpoints M21 of the second resistance line patterns Re and Rf and the midpoints M22 of the second resistance line patterns Rh and Rg are connected to the second voltmeter V2. Figure 7

[0054] When the power transmission device 1 is driven, portions elongated in the radial direction (hereinafter referred to as "elongated portions") and portions contracted in the radial direction (hereinafter referred to as "contracted portions") are generated on the diaphragm portion 221. Specifically, two elongated portions and two contracted portions are generated alternately in the circumferential direction. That is, the elongated portions and the contracted portions are generated alternately at intervals of 90° in the circumferential direction. And, the generation sites of these elongated portions and contracted portions rotate at the first rotational speed described above.

[0055] ​​The resistance values of the first resistance line patterns Ra, Rb, Rc, Rd and the second resistance line patterns Re, Rf, Rg, Rh provided on the back of the torque detection sensor 40 change in accordance with the radial deformation of the diaphragm portion 221. For example, when the elongated portion overlaps a certain resistance line pattern, the resistance value of the resistance line pattern increases. In addition, when the contracted portion overlaps a certain resistance line pattern, the resistance value of the resistance line pattern decreases.

[0056] In Figure 3 the example, when the contracted portion overlaps the first resistance line patterns Ra and Rc, the elongated portion overlaps the first resistance line patterns Rb and Rd. In addition, when the elongated portion overlaps the first resistance line patterns Ra, Rc, the contracted portion overlaps the first resistance line patterns Rb, Rd. Therefore, in the first Wheatstone bridge circuit Cl, the first resistance line patterns Ra, Rc and the first resistance line patterns Rb, Rd indicate reverse resistance value changes.

[0057] In addition, in Figure 3 the example, when the contracted portion overlaps the second resistance line patterns Re, Rg, the elongated portion overlaps the second resistance line patterns Rf, Rh. In addition, when the elongated portion overlaps the second resistance line patterns Re, Rg, the contracted portion overlaps the second resistance line patterns Rf, Rh. Therefore, in the second Wheatstone bridge circuit C2, the second resistance line patterns Re, Rg and the second resistance line patterns Rf, Rh indicate reverse resistance value changes.

[0058] Figure 8 is a graph showing the measurement values vl of the first voltage meter Vl of the first Wheatstone bridge circuit Cl and the measurement values v2 of the second voltage meter V2 of the second Wheatstone bridge circuit C2. As Figure 8 indicated, the measurement values vl, v2 of the first voltage meter Vl and the second voltage meter V2, respectively, are output as periodic sine wave shapes. The period T of the measurement values corresponds to 1 / 2 times the period of the first rotational speed. In addition, depending on whether the phase of the measurement values of the second voltage meter V2 leads or lags the phase of the measurement values of the first voltage meter Vl by 1 / 8 of the period of the first rotational speed (1 / 4 of the period of the measurement values vl, v2), the direction of the input rotational motion can be determined.

[0059] Therefore, based on the output values of the two Wheatstone bridge circuits C1, C2, the rotational angle of the rotational motion input to the flexspline 20 can be detected. Specifically, for example, a function table in which combinations of the respective measurement values v1, v2 of the first voltage meter V1 and the second voltage meter V2 are associated with rotational angles is prepared in advance, and by inputting the measurement values v1, v2 to this function table, the rotational angle can be output. In this way, the torque detection sensor 40 of the present embodiment has the function of a rotational angle detection sensor that detects the rotational angle of the rotational motion input to the flexspline 20.

[0060] <2-3. Regarding the torque detection function>

[0061] The torque detection resistance line pattern P2 is a pattern for detecting the torque applied to the flexspline 20. As shown in FIG. 6, the torque detection resistance line pattern P2 includes a third resistance line pattern R3 and a fourth resistance line pattern R4. Figure 4

[0062] The third resistance line pattern R3 is a pattern in which one conductor is bent in a meandering manner while extending in the circumferential direction, and is in the shape of a circular arc or a circular ring as a whole. In the present embodiment, the third resistance line pattern R3 is provided in a range of about 360° around the center axis 9. In addition, the third resistance line pattern R3 includes a plurality of third resistance lines r3. The plurality of third resistance lines r3 are arranged in the circumferential direction in a posture in which they are substantially parallel to each other. Each of the third resistance lines r3 is inclined toward the circumferential direction side with respect to the radial direction of the flexspline 20. The inclination angle of the third resistance lines r3 with respect to the radial direction is, for example, 45°. The end portions of the third resistance lines r3 adjacent in the circumferential direction are alternately connected to each other on the inner side or the outer side in the radial direction. Thus, the plurality of third resistance lines r3 are connected in series as a whole.

[0063] The fourth resistance line pattern R4 is a pattern in which one conductor is bent in a meandering manner while extending in the circumferential direction, and is in the shape of a circular arc or a circular ring as a whole. The fourth resistance line pattern R4 is located at a position that is on the inner side in the radial direction from the third resistance line pattern R3. In the present embodiment, the fourth resistance line pattern R4 is provided in a range of about 360° around the center axis 9. In addition, the fourth resistance line pattern R4 includes a plurality of fourth resistance lines r4. The plurality of fourth resistance lines r4 are arranged in the circumferential direction in a posture in which they are substantially parallel to each other. Each of the fourth resistance lines r4 is inclined toward the other side of the circumferential direction with respect to the radial direction of the flexspline 20. The inclination angle of the fourth resistance lines r4 with respect to the radial direction is, for example, 45°. The end portions of the fourth resistance lines r4 adjacent in the circumferential direction are alternately connected to each other on the inner side or the outer side in the radial direction. Thus, the plurality of fourth resistance lines r4 are connected in series as a whole.

[0064] Figure 9 is a circuit diagram of a third Wheatstone bridge circuit Ct that includes the third resistance line pattern R3 and the fourth resistance line pattern R4. As shown in FIG. 7, the third Wheatstone bridge circuit Ct includes a third voltage meter V3 and a fourth voltage meter V4.​Figure 9 As shown, the 3rd Wheatstone bridge circuit Ct of the present embodiment includes a 3rd resistance line pattern R3, a 4th resistance line pattern R4, and two fixed resistors Rs. The 3rd resistance line pattern R3 and the 4th resistance line pattern R4 are connected in series. The two fixed resistors Rs are connected in series. And, between the + and - poles of the power supply voltage, the column of the two resistance line patterns R3, R4 and the column of the two fixed resistors Rs are connected in parallel. Further, the midpoint Ml of the 3rd resistance line pattern R3 and the 4th resistance line pattern R4 and the midpoint M2 of the two fixed resistors Rs are connected to the 3rd voltage meter Vt.

[0065] The resistance values of the 3rd resistance line pattern R3 and the 4th resistance line pattern R4 vary depending on 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 with the center axis 9 as the center, the resistance value of the 3rd resistance line pattern R3 decreases and the resistance value of the 4th resistance line pattern R4 increases. On the other hand, when a torque is applied to the flexible gear 20 toward the other side in the circumferential direction with the center axis 9 as the center, the resistance value of the 3rd resistance line pattern R3 increases and the resistance value of the 4th resistance line pattern R4 decreases. In this way, the 3rd resistance line pattern R3 and the 4th resistance line pattern R4 indicate resistance value changes that are opposite to each other with respect to the torque.

[0066] Further, if each of the resistance values of the 3rd resistance line pattern R3 and the 4th resistance line pattern R4 changes, the potential difference between the midpoint Ml of the 3rd resistance line pattern R3 and the 4th resistance line pattern R4 and the midpoint M2 of the two fixed resistors Rs changes, and thus the measured value vt of the 3rd voltage meter Vt changes. Therefore, based on the measured value vt of the 3rd voltage meter Vt, the direction and the magnitude of the torque applied to the flexible gear 20 can be detected.

[0067] <2-4. Regarding fluctuation correction>

[0068] However, during the driving of the power transmission apparatus 1, periodic flexural deformation occurs on the flexible gear 20. Therefore, the measured value of the 3rd voltage meter Vt includes a component that reflects the torque to be measured as it is and an error component (fluctuation) that arises from the periodic flexural deformation of the flexible gear 20. This error component varies depending on the rotation angle of the rotational motion input to the flexible gear 20.

[0069] Therefore, the signal processing circuit P3 performs a correction process for eliminating the above-described error component based on the measured value of the 3rd voltage meter Vt. Figure 10 is a graph conceptually showing the correction process of the signal processing circuit P3. As shown, the signal processing circuit P3 includes a subtracter 31, a multiplier 32, and an adder 33. Figure 10As shown, the respective measurement values vl, v2, vt of the first voltage meter Vl, the second voltage meter V2, and the third voltage meter Vt are input to the signal processing circuit P3. The signal processing circuit P3 first detects the rotation angle of the rotational motion input to the flexible gear 20 based on the measurement values vl and v2 of the first voltage meter Vl and the second voltage meter V2. Then, based on the detected rotation angle, the above-described error component is estimated. Then, the measurement value vt of the third voltage meter Vt is corrected using the estimated error component. As a result, the torque applied to the flexible gear 20 can be output with higher accuracy.

[0070] In addition, the signal processing circuit P3 can not calculate the above-described rotation angle, but multiply the respective measurement values vl, v2 of the first voltage meter Vl and the second voltage meter V2 by a predetermined coefficient, and synthesize the measurement value vt of the third voltage meter Vt. In this way, since the processing load of the calculation of the rotation angle is reduced, the operation speed of the signal processing circuit P3 can be improved.

[0071] <2-5. Regarding temperature correction>

[0072] In addition, as described above, when copper or an alloy containing copper is used in the material of the conductor layer 43, the material cost of the torque detection sensor 40 can be suppressed. However, compared to other high-priced materials, the resistance value of copper easily changes due to the environmental temperature. Therefore, in the present embodiment, in order to correct the influence of the temperature, a temperature detection resistance line pattern P4 is provided on the torque detection sensor 40. As shown in FIG. 6, the temperature detection resistance line pattern P4 is arranged on the same surface of the circuit board 41 as the torque detection resistance line pattern P2. That is, the surface-side conductor layer 43 contains the temperature detection resistance line pattern P4. Figure 4

[0073] The temperature detection resistance line pattern P4 is a pattern extending in a circular arc shape or a circular ring shape along the circumferential direction of the flexible gear 20. Therefore, the change in the resistance value of the temperature detection resistance line pattern P4 based on the circumferential direction torque is extremely small. Therefore, the change in the resistance value of the temperature detection resistance line pattern P4 due to the temperature becomes dominant. Therefore, as long as the resistance value of the temperature detection resistance line pattern P4 is measured, a signal reflecting the temperature of the flexible gear 20 or the environmental temperature can be obtained.

[0074] The signal processing circuit P3 corrects the measurement value of the third voltage meter Vt not only considering the above-described rotation angle, but also considering the resistance value of the temperature detection resistance line pattern P4. Specifically, the measurement value vt of the third voltage meter Vt is increased or decreased in a direction to eliminate the change due to the temperature. In this way, while using inexpensive copper or a copper alloy, the influence of the temperature change can be suppressed, and the torque applied to the flexible gear 20 can be detected with higher accuracy.

[0075] <3. Modified example>​

[0076] The above describes one embodiment of the present application, but the present application is not limited to the above-described embodiment.

[0077] In the above-described embodiment, the plurality of first resistance lines r1 included in the first resistance line pattern R1 and the plurality of second resistance lines r2 included in the second resistance line pattern R2 respectively extend in the radial direction. This is to detect the periodic deformation of the diaphragm portion 221 in the radial direction. However, at the time of driving the power transmission device 1, the diaphragm portion 221 is periodically deformed not only in the radial direction but also in the circumferential direction. Therefore, as shown in FIG. 6, the directions of the first resistance lines r1 and the second resistance lines r2 can be the circumferential direction. That is, the plurality of first resistance lines r1 included in the first resistance line pattern R1 and the plurality of second resistance lines r2 included in the second resistance line pattern R2 respectively extend in either one of the radial direction and the circumferential direction. Figure 11

[0078] However, the directions of the first resistance lines r1 and the second resistance lines r2 are preferably the direction in which the deformation is larger, out of the radial direction and the circumferential direction, according to the circular body that is the detection target. That is, in the case where the deformation in the radial direction of the circular body that is the detection target is larger than the deformation in the circumferential direction, as shown in FIG. 6, it is preferable to set the directions of the first resistance lines r1 and the second resistance lines r2 to the radial direction. In contrast, in the case where the deformation in the radial direction of the circular body that is the detection target is smaller than the deformation in the circumferential direction, as shown in FIG. 7, it is preferable to set the directions of the first resistance lines r1 and the second resistance lines r2 to the circumferential direction. Figure 3 Figure 11

[0079] Specifically, as in the above-described embodiment, in the case where the torque detection sensor 40 is attached to the diaphragm portion 221 of the flexible gear 20, it is preferable that the directions of the first resistance lines r1 and the second resistance lines r2 are the radial direction. In addition, in the case where the torque detection sensor 40 is attached to the cylindrical portion of the flexible gear 20 or the inner gear 10, it is preferable that the directions of the first resistance lines r1 and the second resistance lines r2 are the circumferential direction.

[0080] In addition, the rotation angle detection resistance line pattern P1 of the above-described embodiment includes four first resistance line patterns R1 and four second resistance line patterns R2. However, the number of the first resistance line patterns R1 and the second resistance line patterns R2 included in the rotation angle detection resistance line pattern P1 can be other than four.

[0081] ​​​In addition, the conductor layer 43 of the circuit board 41 can include a resistance line pattern other than the rotation angle detection resistance line pattern P1, the torque detection resistance line pattern P2, and the temperature detection resistance line pattern P4. For example, the conductor layer 43 can include a resistance line pattern for detecting axial deformation of the flexible gear 20.

[0082] In addition, in the above-described embodiments, the signal processing circuit P3 is mounted on the circuit board 41. However, the signal processing circuit P3 can be provided outside the circuit board 41.

[0083] In addition, in the above-described embodiments, copper or an alloy including copper is used as the material of each resistance line pattern. However, other metals such as SUS and aluminum can be used as the material of the resistance line pattern. In addition, a non-metallic material such as ceramic or resin can be used as the material of the resistance line pattern. In addition, a conductive ink can be used as the material of the resistance line pattern. In the case where a conductive ink is used, each resistance line pattern can be printed on the surface of the circuit board 41 with the conductive ink.

[0084] In addition, in the flexible gear 20 of the above-described embodiments, the diaphragm portion 221 extends to the radially outer side from the base end portion of the cylindrical portion 21. However, the diaphragm portion 221 can extend to the radially inner side from the base end portion of the cylindrical portion 21.

[0085] In addition, in the above-described embodiments, the object of the torque detection is the flexible gear 20. However, the torque detection sensor 40 having the same structure as that of the above-described embodiments can be used to detect a torque applied to a circular body other than the flexible gear 20. However, the circular body is preferably periodically flexibly deformed according to an input rotational motion.

[0086] For example, in a planetary reducer having a sun gear and a plurality of planetary gears that revolve around the sun gear while rotating, the rotation angle detection sensor or the torque detection sensor of the present application can be mounted on a ring in which the plurality of planetary gears are inscribed. In this case, the circuit board can be fixed to the circular surface of the ring. That is, the circular body in the present application can be the ring of the planetary reducer.

[0087] Further, the details of the structure of the rotation angle detection sensor, the torque detection sensor, and the power transmission device can be appropriately changed within a range not departing from the gist of the present application. In addition, the elements appearing in the above-described embodiments and each modification example can be appropriately combined within a range not producing a contradiction.

[0088] Industrial Applicability

[0089] The present application can be used for a rotation angle detection sensor, a torque detection sensor, and a power transmission device.

Claims

1. A rotation angle detecting sensor that detects a rotation angle of a rotational movement input to a circular body having a cylindrical portion and a flat plate portion having a diaphragm portion and a thick wall portion, wherein the rotation angle detecting sensor includes a substrate having a conductor layer, the conductor layer includes: a plurality of first resistance line patterns that are arranged at equal intervals in a circumferential direction; and a plurality of second resistance line patterns that are concentric with the first resistance line patterns and are arranged at equal intervals in the circumferential direction in regions where the first resistance line patterns are not arranged, the first resistance line pattern is a pattern in which first resistance lines extending in either one of a radial direction and a circumferential direction are connected in series, the second resistance line pattern is a pattern in which second resistance lines extending in the one direction are connected in series, the substrate having the resistance line patterns is fixed to the circular body that is a detection target, and a rotation angle is detected based on resistance values of the first resistance line patterns and the second resistance line patterns that change in accordance with a radial deformation of the diaphragm portion of the circular body that is the detection target.

2. The rotation angle detecting sensor according to claim 1, wherein the plurality of first resistance line patterns and the plurality of second resistance line patterns are respectively incorporated in Wheatstone bridge circuits.

3. The rotation angle detecting sensor according to claim 1 or 2, wherein the first resistance line patterns and the second resistance line patterns are respectively circular arc shapes.

4. The rotation angle detecting sensor according to claim 3, wherein the conductor layer has four first resistance line patterns and four second resistance line patterns, the first resistance line patterns and the second resistance line patterns respectively extend in a range of an angle of 45° with a center axis of the circular body as a center.

5. The rotation angle detecting sensor according to claim 4, wherein the first resistance line patterns and the second resistance line patterns as a whole extend in a shape of one annular ring.

6. A torque detecting sensor that includes the rotation angle detecting sensor according to any one of claims 1 to 5, wherein the conductor layer includes a torque detecting resistance line pattern for detecting a torque applied to the circular body.

7. The torque detecting sensor according to claim 6, wherein the torque detecting sensor has a signal processing circuit that corrects a measured value of the torque detecting resistance line pattern in accordance with the rotation angle detected by the rotation angle detecting sensor.

8. The torque detecting sensor according to claim 6 or 7, wherein the conductor layer includes a temperature detecting resistance line pattern for detecting a temperature of the circular body.

9. The torque detecting sensor according to claim 6 or 7, wherein a material of the conductor layer is copper or an alloy including copper.

10. The torque detecting sensor according to claim 6 or 7, wherein the torque detecting sensor has a plurality of the conductor layers.

11. A power transmitting apparatus that has: the torque detecting sensor according to any one of claims 6 to 10; and the circular body.

12. The power transmitting apparatus according to claim 11, wherein the circular body has: a The flexible cylindrical portion extends in a cylindrical shape in the axial direction; A plurality of external teeth are provided to an outer peripheral surface of the cylindrical portion; and The flat plate-shaped diaphragm portion expands from an axial one side of the cylindrical portion to the radial direction outside or the radial direction inside, The substrate is fixed to the diaphragm portion.

13. The power transmission apparatus according to claim 11, wherein The circular body is a ring in which a plurality of planetary wheels are inscribed, the planetary wheels orbiting around a sun wheel while self-rotating, The substrate is fixed to a surface of the ring.

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