Torque sensor

Abstract

To make a driving mechanism compact by shortening the axial length of the driving mechanism including a rotary motor, a reduction gear and a torque sensor.SOLUTION: A force receiving body (32) fixed between the motor case (16) and the reduction gear case (22) is arranged so as to surround the outside of the reduction gear case (22). A frame body (36) fixed to the mounting part (26) is arranged so as to surround the outside of the reduction gear case (22). A plurality of beams (40) are spaced around the reducer case (22). At least one of the beams (40) is provided with a strain measuring part (42).SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a torque sensor that detects the output torque of a reducer. [Background technology]

[0002] Patent Document 1 discloses a torque sensor that detects motor torque of a rotary motor by utilizing a reaction torque acting on the rotary motor. The rotary motor disclosed in Patent Document 1 is used to transmit motor torque to an actuating member (also called a rotating object) called a converter. For this purpose, the actuating member is connected in series to the rotary motor (see, for example, FIG. 2 of Patent Document 1). Furthermore, in order to detect the motor torque transmitted from the rotary motor to the actuating member, the technology of Patent Document 1 interposes a torque sensor in series between the rotary motor and the actuating member. That is, in the prior art, the rotary motor, the torque sensor, and the actuating member are arranged in series in this order. The configuration of the torque sensor (called a torque converter in Patent Document 1) according to this prior art can be briefly described as follows.

[0003] The torque sensor includes an annular motor plate disposed around the outside of the output shaft of the rotary motor (referred to as the drive shaft of the motor in Patent Document 1), and the motor plate is located on the base end side of the output shaft of the rotary motor. The motor plate is fixed to the motor case of the rotary motor, and ears that protrude radially outward are formed on parts of the circumferential direction of the motor plate.

[0004] The torque sensor includes an annular mounting plate disposed around the outside of the output shaft of the rotary motor, the mounting plate being located on the tip side of the output shaft of the rotary shaft. The mounting plate is fixed to a mounting base (referred to as a fixed plate in Patent Document 1) for mounting the rotary motor, and a lug is formed on part of the circumferential direction of the mounting plate, protruding radially outward.

[0005] The torque sensor includes an open ring (referred to as a flex ring in Patent Document 1) arranged so as to surround the outside of the output shaft of the rotary motor, and the open ring is located between the motor plate and the mounting plate. Ears (referred to as flanges in Patent Document 1) that protrude radially outward are formed on a pair of open ends of the open ring. The gap between the pair of ears of the open ring is displaced in response to the reaction torque acting on the rotary motor. One ear of the open ring is fixed to an ear of the motor plate with a fastener, and the other ear of the open ring is fixed to an ear of the mounting plate with a fastener.

[0006] The torque sensor includes a strain measuring unit provided on the inner peripheral surface of the open ring at a position facing the gap between the pair of ears, and the strain measuring unit measures the curvature (deflection) of the open ring. By measuring the curvature of the open ring with the strain measuring unit, the motor torque of the rotary motor can be detected by utilizing the reaction torque acting on the rotary motor.

[0007] The output shaft of the rotary motor is connected to an operating member (referred to as a converter in Patent Document 1). The rotary motor, mounting base, and torque sensor constitute a drive mechanism that rotationally drives the operating member. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Special Publication No. 2017-512299 Summary of the Invention [Problem to be solved by the invention]

[0009] However, in the prior art, as described above, the rotary motor, torque sensor, and actuating member are arranged in series in this order. Furthermore, in the torque sensor according to the prior art, the motor plate, mounting plate, and release ring are arranged to surround the output shaft of the rotary motor. Therefore, when connecting the output shaft of the rotary motor to the actuating member, the length of the output shaft of the rotary motor must be longer than the axial length of the torque sensor. As a result, the axial length of the drive mechanism including the rotary motor and the torque sensor becomes longer, making it difficult to make the drive mechanism compact.

[0010] Furthermore, when a rotary motor is used to transmit motor torque to an actuating member, a reducer may be used to adjust the motor torque to a desired magnitude. In this case, the reducer is interposed in series between the rotary motor and the torque sensor. That is, when a rotary motor is used in combination with a reducer and a torque sensor, the rotary motor, reducer, torque sensor, and actuating member are arranged in series in this order. As a result, the axial length of the drive mechanism including the rotary motor, reducer, and torque sensor becomes long, making it difficult to compact the drive mechanism. For these reasons, when emphasis is placed on compactness in the axial length, it has been difficult to use a rotary motor, reducer, and torque sensor in combination.

[0011] Therefore, one aspect of the present invention aims to reduce the axial length of a drive mechanism including a rotary motor, a reducer, and a torque sensor, thereby making the drive mechanism more compact. [Means for solving the problem]

[0012] In order to solve the above-mentioned problems, a torque sensor according to one embodiment of the present invention is a torque sensor that detects a reaction torque acting on a reducer in a rotary actuator including a rotary motor and a reducer connected in series to the rotary motor, and includes: a force receiving body that is arranged so as to surround the outside of the reducer case of the reducer and is fixed between the motor case of the rotary motor and the reducer case, and receives the reaction torque; a frame body that is arranged so as to surround the outside of the reducer case and is fixed to an attachment portion; a plurality of beams that are arranged to connect between the force receiving body and the frame body and are arranged at intervals around the reducer case; and a strain measuring unit that is arranged on at least one of the plurality of beams and measures the strain of the beam. [Effects of the Invention]

[0013] According to one aspect of the present invention, the axial length of a drive mechanism including a rotary motor, a reducer, and a torque sensor can be shortened, thereby making the drive mechanism more compact. Note that the reaction torque acting on the reducer can be expressed as the output torque of the reducer (or rotary actuator). Therefore, one aspect of the present invention functions as a torque sensor that detects the output torque of the reducer (or rotary actuator) by detecting the reaction torque acting on the reducer. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a schematic side view of a drive device according to a first embodiment of the present invention. [Figure 2] 1 is a schematic perspective view of a drive device according to a first embodiment of the present invention. [Figure 3] 1 is a schematic cross-sectional side view of a torque sensor according to a first embodiment of the present invention. FIG. [Figure 4] FIG. 1 is a schematic perspective view of a torque sensor according to a first embodiment of the present invention, as viewed from the front side. [Figure 5] FIG. 2 is a schematic perspective view of the torque sensor according to the first embodiment of the present invention, as viewed from the rear side. [Figure 6]FIG. 6 is a schematic side view of a drive device according to a second embodiment of the present invention. [Figure 7] FIG. 10 is a schematic perspective view of a drive device according to a second embodiment of the present invention. [Figure 8] FIG. 10 is a schematic cross-sectional side view of a torque sensor according to a second embodiment of the present invention. [Figure 9] FIG. 10 is a schematic perspective view of a torque sensor according to a second embodiment of the present invention, as viewed from the front side. [Figure 10] FIG. 10 is a schematic perspective view of a torque sensor according to a second embodiment of the present invention, as viewed from the rear side. DETAILED DESCRIPTION OF THE INVENTION

[0015] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the specification and claims of this application, the axial direction refers to a direction parallel to the rotation shaft of a rotary motor or the output shaft of a reducer. In the drawings, "SD" refers to the axial direction, "SDa" refers to the front side or forward direction, which is one side of the axial direction, and "SDb" refers to the rear side or rear direction, which is the other side of the axial direction.

[0016] [Embodiment 1] A first embodiment of the present invention will be described with reference to FIGS.

[0017] (Outline of the drive mechanism 10, rotary motor 14) 1 and 2, a drive mechanism 10 according to a first embodiment of the present invention is a mechanism for rotationally driving an actuating member 12, and is used, for example, in a joint of a robot arm. The drive mechanism 10 includes a rotary motor 14 for rotating the actuating member 12. The rotary motor 14 has a motor case 16 and a rotary shaft 18 rotatably mounted on the motor case 16. An annular flange portion 16f is formed on one axial end (front end) of the motor case 16.

[0018] (Reduction gear 20, mounting base 26) As shown in FIGS. 1 and 2 , the drive mechanism 10 includes a reducer 20 that reduces the rotation speed of the rotary shaft 18 of the rotary motor 14, and the reducer 20 is connected in series with the rotary motor 14. The reducer 20 increases the motor torque of the rotary motor 14, outputs the increased motor torque, and transmits the output torque to the operating member 12. The reducer 20 includes a reducer case 22 connected in series to the flange portion 16f of the motor case 16, and an output shaft 24 rotatably provided on the reducer case 22 and interlocked with the rotary shaft 18 of the rotary motor 14. The output shaft 24 of the reducer 20 is connected to the operating member 12, and the operating member 12 is rotationally driven by the rotation of the output shaft 24. Note that when the reducer 20 is considered to be part of the rotary motor 14, the reducer case 22 of the reducer 20 can also be considered to be part of the motor case 16, and the output shaft 24 of the reducer 20 can also be considered to be the output shaft of the rotary motor 14.

[0019] (Rotary Actuator) In the drive mechanism 10 configured in this manner, the rotary motor 14 and the reducer 20 connected in series to the rotary motor 14 constitute one aspect of a rotary actuator. Note that the reducer 20 in the rotary actuator may be omitted depending on the output torque of the rotary actuator that is to be transmitted to the operating member 12.

[0020] The drive mechanism 10 includes a mounting base 26 as a mounting portion for mounting the rotary motor 14 via the reducer 20. The mounting base 26 is formed with an insertion hole 26h for inserting the output shaft 24 of the reducer 20 therethrough.

[0021] (Overview of Torque Sensor 28) 1 and 2, the drive mechanism 10 includes a torque sensor 28, which is disposed outside the reducer case 22 of the reducer 20. The specific configuration of the torque sensor 28 according to the first embodiment of the present invention is as follows.

[0022] (Stretch body 30, force receiving body 32) As shown in FIGS. 1 to 5, the torque sensor 28 includes a strain body 30 disposed outside the reducer case 22. The strain body 30 has a force receiving body 32 that receives a reaction torque acting on the output shaft 24 of the reducer 20. The force receiving body 32 is disposed outside the reducer case 22 so as to surround it. The force receiving body 32 is formed in the shape of a square plate of the reducer 20, and a square opening 32a is formed in the center of the force receiving body 32 for inserting the reducer case 22. The force receiving body 32 is interposed between the motor case 16 and the reducer case 22 and is fixed to the motor case 16 and the reducer case 22 (see FIGS. 1 and 3). In other words, the motor case 16, the force receiving body 32, and the reducer case 22 are fixed so that their relative positions do not change. In this embodiment, the force receiving body 32 is formed with multiple (four in this embodiment) through-holes 32v for passing set screws 34 therethrough (see FIG. 5). Furthermore, a plurality of through holes for threading the set screws 34 are formed in the flange portion 16f of the motor case 16 at positions corresponding to the plurality of through holes 32v. A plurality of screw holes for threading the set screws 34 are formed in the rear bottom surface of the reducer case 22, the bottom surface closest to the force receiving body 32 (the bottom surface indicated by the arrow SDb in FIG. 3 ), at positions corresponding to the plurality of through holes 32v. The plurality of set screws 34 then fasten the flange portion 16f, the force receiving body 32, and the reducer case 22 together with the flange portion 16f and the force receiving body 32 interposed between the screw heads and the reducer case 22. The structure for fastening the motor case 16, the force receiving body 32, and the reducer case 22 is not limited to the structure of this embodiment. The force receiving body 32 may be formed in a rectangular plate shape other than a square. The opening 32a of the force receiving body 32 may be formed in a rectangular shape other than a square or a circular shape.

[0023] (Frame 36) As shown in FIGS. 1 to 5 , the strain body 30 includes a frame 36 disposed around the outside of the reducer case 22. The frame 36 is spaced apart from the force receiving body 32 in the axial direction and is not in contact with the reducer case 22. The outer shape (the outline shape of the outer peripheral edge) and inner shape (the outline shape of the inner peripheral edge) of the frame 36 are both square. The frame 36 is located closer to the rotary motor than the portion of the output shaft of the reducer that protrudes from the reducer case. The frame 36 is fixed to the mounting base 26, which serves as the mounting portion, with a plurality of set screws 38. The frame 36 is formed with a plurality of screw holes 36v for threading the set screws 38. The outer and inner shapes of the frame 36 may each be rectangular rather than square.

[0024] (Beam 40) As shown in FIGS. 1 to 5 , the strain generator 30 includes a plurality of beams 40 that are connected between the outer peripheral edge of the force receiving body 32 and the inner peripheral edge of the frame 36. The beams 40 are arranged at equal intervals around the reducer case 22 in the circumferential direction. Each beam 40 is elastically deformable in response to a reaction torque acting on the reducer 20 in accordance with the output of the reducer 20, and the central portion of each beam 40 has a constricted shape. Note that as long as the beams 40 are arranged at intervals around the reducer case 22, the beams 40 may be arranged at unequal intervals. The edge of each beam 40 may include a straight portion extending in the axial direction. The output of the reducer 20 can also be expressed as the output of a rotary actuator.

[0025] As described above, the flexure body 30 has the force receiving body 32, the frame body 36, and the plurality of beams 40. In other words, the force receiving body 32, the frame body 36, and the plurality of beams 40 are configured by the flexure body 30, which is a single member.

[0026] (Strain gauge type strain measurement unit 42) As shown in FIGS. 1, 2, 4, and 5, the torque sensor 28 includes a strain gauge-type strain measuring unit 42 that is provided on the outer surface of each beam 40 and measures the strain of each beam 40. Each strain gauge-type strain measuring unit 42 has a plurality of strain gauges (not shown). Each strain gauge-type strain measuring unit 42 measures the strain of each beam 40, thereby making it possible to detect the reaction torque acting on the reducer 20. The output torque of the reducer 20 (output torque of the rotary actuator) and the reaction torque acting on the reducer 20 have an action-reaction relationship. Therefore, the torque sensor 28 can detect the output torque of the reducer 20 (output torque of the rotary actuator) by detecting the reaction torque acting on the reducer 20.

[0027] The strain gauge type strain measuring unit 42 may be provided on the inner surface of each beam 40 instead of on the outer surface of each beam 40. The strain gauge type strain measuring unit 42 may be provided on the outer surface and the inner surface of each beam 40. The strain gauge type strain measuring unit 42 may be provided on at least one of the multiple beams 40 instead of on each beam 40. Furthermore, the torque sensor 28 may include a capacitance type strain measuring unit (not shown) or an optical type strain measuring unit (not shown) that measures the strain of the beam 40 instead of the strain gauge type strain measuring unit 42. A direct film formation method may be used to provide the strain gauge.

[0028] According to the configuration of the torque sensor 28 according to the first embodiment of the present invention, as described above, the force receiving body 32 and the frame 36 are each arranged so as to surround the outside of the reducer case 22. The multiple beams 40 are arranged at intervals around the reducer case 22. Therefore, the torque sensor 28 does not interfere with the connection between the output shaft 24 of the reducer 20 and the operating member 12. As a result, the output shaft 24 of the reducer 20 can be connected to the operating member 12 without the length of the output shaft 24 of the reducer 20 being longer than the length of the torque sensor 28 in the axial direction.

[0029] Therefore, according to the first embodiment of the present invention, the axial length of the drive mechanism 10 including the rotary motor 14, the reducer 20, and the torque sensor 28 can be shortened, thereby making the drive mechanism 10 more compact. In particular, because the frame 36 is located closer to the rotary motor 14 than the portion of the output shaft 24 of the reducer 20 that protrudes from the reducer case 22, the axial length of the drive mechanism 10 can be further shortened, making the drive mechanism 10 more compact and reducing the risk of wires getting tangled.

[0030] Furthermore, according to the configuration of torque sensor 28 according to embodiment 1 of the present invention, as described above, frame body 36 is spaced apart in the axial direction from force receiving body 32. Therefore, according to embodiment 1 of the present invention, it is possible to prevent torque sensor 28 from expanding in the radial direction of output shaft 24 of reducer 20, thereby making torque sensor 28 more compact.

[0031] Furthermore, according to the configuration of the torque sensor 28 according to the first embodiment of the present invention, as described above, the force receiving body 32, the frame body 36, and the plurality of beams 40 are configured by a single member, the strain generating body 30. Therefore, according to the first embodiment of the present invention, the number of parts of the torque sensor 28 can be reduced, and the configuration of the torque sensor 28 can be simplified.

[0032] Furthermore, according to the configuration of the torque sensor 28 according to the first embodiment of the present invention, a strain gauge type strain measuring unit 42 is provided on each beam 40. Therefore, according to the first embodiment of the present invention, each strain gauge type strain measuring unit 42 measures the strain of each beam 40, and thus the reaction torque acting on the reducer 20 can be detected with high accuracy, and as a result, the output torque of the reducer 20 can be detected with high accuracy.

[0033] [Embodiment 2] A second embodiment of the present invention will be described with reference to Figures 6 to 10. For ease of explanation, members having the same functions as those described in the first embodiment will be denoted by the same reference numerals, and their description will not be repeated.

[0034] (Outline of drive mechanism 44) 6 and 7, a drive mechanism 44 according to a second embodiment of the present invention is a mechanism for rotationally driving an operating member 12, and is used, for example, in a joint of an arm of a robot. Similar to the drive mechanism 10 (see FIGS. 1 and 2), the drive mechanism 44 includes a rotary motor 14, a reducer 20, and a mounting base 26. In the drive mechanism 44, an annular flange 22f is formed on the other axial end (rear end) of the reducer case 22. The flange 22f of the reducer case 22 is joined to a flange 16f of the motor case 16.

[0035] (Outline of Torque Sensor 46) 6 and 7, the drive mechanism 44 includes a torque sensor 46, which is disposed outside the reducer case 22 of the reducer 20. The specific configuration of the torque sensor 28 according to the second embodiment of the present invention is as follows.

[0036] (Stretch body 48, force receiving body 50) As shown in FIGS. 6 to 10 , the torque sensor 46 includes a strain body 48 disposed outside the reducer case 22. The strain body 48 has a force receiving body 50 that receives a reaction torque acting on the reducer 20, and the force receiving body 32 is disposed outside the reducer case 22 so as to surround it. The force receiving body 50 is formed in a ring plate shape, and a circular opening 50a is formed in the center of the force receiving body 50, through which the reducer case 22 is inserted. The force receiving body 50 is fixed to the flange portion 16f of the motor case 16 via the flange portion 22f of the reducer case 22 by a plurality of set screws 52. A plurality of screw holes 50v are formed in the force receiving body 50, into which the set screws 52 are screwed. The opening 50a of the force receiving body 50 may be formed in a rectangular shape, including a square shape.

[0037] (Frame 54) As shown in Figures 6 to 10, the strain body 48 includes a frame body 54 arranged to surround the outside of the reducer case 22. The frame body 54 is spaced apart from the force receiving body 50 in the axial direction and is not in contact with the reducer case 22. The frame body 54 is formed in the shape of a ring plate, and a circular opening 54a is formed in the center of the frame body 54, through which the reducer case 22 is inserted. The outer shape of the frame body 54 is the same as the outer shape of the force receiving body 50. The frame body 54 is fixed to the mounting base 26, which serves as a mounting portion, by a plurality of set screws 56. The frame body 54 is formed with a plurality of screw holes 54v into which the set screws 56 are threaded.

[0038] (Beam 58) As shown in FIGS. 6 to 10 , the strain generating body 48 includes a plurality of beams 58 that are provided to connect between one axial side surface (front side surface) of the force receiving body 50 and the other axial side surface (rear side surface) of the frame body 54. The plurality of beams 58 are arranged at equal intervals along the circumferential direction around the reducer case 22. Each beam 58 is elastically deformable in response to the reaction torque acting on the reducer 20, and the central portion of each beam 58 has a constricted shape. Note that as long as the plurality of beams 58 are arranged at intervals around the reducer case 22, the arrangement of the plurality of beams 58 may be uneven. The edge of each beam 58 may include a straight portion extending in the axial direction.

[0039] As described above, the flexure body 48 has the force receiving body 50, the frame body 54, and the plurality of beams 58. In other words, the force receiving body 50, the frame body 54, and the plurality of beams 58 are configured by the flexure body 48, which is a single member.

[0040] (Strain gauge type strain measurement unit 60) 6, 7, 9, and 10, the torque sensor 46 includes a strain gauge-type strain measuring unit 60 that is provided on the outer surface of each beam 58 and measures the strain of each beam 58. Each strain gauge-type strain measuring unit 60 has a plurality of strain gauges (not shown). Each strain gauge-type strain measuring unit 60 measures the strain of each beam 58, thereby making it possible to detect the reaction torque acting on the reducer 20. Therefore, similar to the torque sensor 28 described in the first embodiment, the torque sensor 46 can detect the output torque of the reducer 20 (the output torque of the rotational actuator) by detecting the reaction torque acting on the reducer 20.

[0041] The strain gauge type strain measuring unit 60 may be provided on the inner surface of each beam 58 instead of on the outer surface of each beam 58. The strain gauge type strain measuring unit 60 may be provided on the outer surface and the inner surface of each beam 58. The strain gauge type strain measuring unit 60 may be provided on at least one of the plurality of beams 58 instead of on each beam 58. Furthermore, the torque sensor 46 may include a capacitance type strain measuring unit (not shown) or an optical type strain measuring unit (not shown) that measures the strain of the beam 58 instead of the strain gauge type strain measuring unit 60. A direct film formation method may be used as a method for providing the strain gauge.

[0042] According to the configuration of the torque sensor 46 according to the second embodiment of the present invention, as described above, the force receiving body 50 and the frame body 54 are each arranged so as to surround the outside of the reducer case 22. A plurality of beams 58 are arranged at intervals around the reducer case 22. Therefore, the torque sensor 46 does not interfere with the connection between the output shaft 24 of the reducer 20 and the operating member 12. As a result, the output shaft 24 of the reducer 20 can be connected to the operating member 12 without the length of the output shaft 24 of the reducer 20 being longer than the length of the torque sensor 46 in the axial direction.

[0043] Therefore, according to the second embodiment of the present invention, the axial length of the drive mechanism 44 including the rotary motor 14, the reducer 20, and the torque sensor 46 can be shortened, thereby making the drive mechanism 44 more compact. In particular, because the frame 54 is located closer to the rotary motor 14 than the portion of the output shaft 24 of the reducer 20 that protrudes from the reducer case 22, the axial length of the drive mechanism 44 can be further shortened, making the drive mechanism 44 more compact and reducing the risk of wires getting tangled.

[0044] Furthermore, according to the configuration of torque sensor 46 according to the second embodiment of the present invention, as described above, frame body 54 is spaced apart in the axial direction from force receiving body 50. Therefore, according to the second embodiment of the present invention, the torque sensor 46 can be prevented from expanding in the radial direction of output shaft 24 of reducer 20, thereby making the torque sensor 46 more compact.

[0045] Furthermore, according to the configuration of the torque sensor 46 according to the second embodiment of the present invention, as described above, the force receiving body 50, the frame body 54, and the plurality of beams 58 are configured by the single member, the strain body 48. Therefore, according to the second embodiment of the present invention, the number of parts of the torque sensor 46 can be reduced, and the configuration of the torque sensor 46 can be simplified.

[0046] Furthermore, according to the configuration of the torque sensor 46 according to the second embodiment of the present invention, a strain gauge type strain measuring unit 60 is provided on each beam 58. Therefore, according to the second embodiment of the present invention, each strain gauge type strain measuring unit 60 measures the strain of each beam 58, so that the reaction torque acting on the reducer 20 can be detected with high accuracy, and as a result, the output torque of the reducer 20 can be detected with high accuracy.

[0047] 〔summary〕 A torque sensor according to a first aspect of the present invention is a torque sensor that detects a reaction torque acting on a reducer in a rotary actuator that includes a rotary motor and a reducer connected in series to the rotary motor, and includes: a force receiving body that is arranged so as to surround the outside of the reducer case of the reducer and is fixed between the motor case of the rotary motor and the reducer case, and that receives the reaction torque; a frame body that is arranged so as to surround the outside of the reducer case and is fixed to an attachment portion; a plurality of beams that are arranged to connect between the force receiving body and the frame body and are arranged at intervals around the reducer case; and a strain measuring unit that is arranged on at least one of the plurality of beams and that measures the strain of the beam.

[0048] According to the above configuration, as described above, the force receiving body and the frame are disposed so as to surround the outside of the reducer case. The multiple beams are disposed at intervals around the reducer case. Therefore, when the rotary motor, the reducer, and the torque sensor are used together, the torque sensor is not arranged in series with respect to the reducer, and the torque sensor does not interfere with the connection between the output shaft of the reducer and the operating member. This allows the output shaft of the reducer to be connected to the operating member without the length of the output shaft of the reducer being longer than the axial length of the torque sensor. As a result, the axial length of the drive mechanism including the rotary motor, the reducer, and the torque sensor can be shortened, thereby achieving a compact drive mechanism. Note that the reaction torque acting on the reducer can be expressed as the output torque of the reducer (or rotary actuator). Therefore, one aspect of the present invention functions as a torque sensor that detects the output torque of the reducer (or rotary actuator) by detecting the reaction torque acting on the reducer.

[0049] A torque sensor according to a second aspect of the present invention is the torque sensor of the first aspect, wherein the force receiving body, the frame body, and the plurality of beams may be configured by a strain generating body that is a single member.

[0050] According to the above configuration, the number of parts of the torque sensor can be reduced, and the configuration of the torque sensor can be simplified.

[0051] A torque sensor according to a third aspect of the present invention is based on the first or second aspect, and the frame may be located closer to the rotary motor than a portion of the output shaft of the reducer that protrudes from the reducer case.

[0052] According to the above configuration, the axial length of the drive mechanism can be further shortened, thereby making the drive mechanism more compact.

[0053] A torque sensor according to a fourth aspect of the present invention is in any one of the first to third aspects, wherein the frame body is spaced apart from the force receiving body in the axial direction.

[0054] According to the above configuration, the torque sensor can be prevented from expanding in the radial direction of the output shaft of the reducer, thereby making the torque sensor more compact.

[0055] [Additional Notes] The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention. [Explanation of symbols]

[0056] 10: drive mechanism, 12: operating member, 14: rotary motor, 16: motor case, 16f: flange portion, 18: rotary shaft, 20: reducer, 22: reducer case, 22f: flange portion, 24: output shaft, 26: mounting base (mounting portion), 26h: insertion hole, 28: torque sensor, 30: strain generating body, 32: force receiving body, 32a: opening, 32v: through hole, 34: set screw, 36: frame, 36v: threaded hole, 38: set screw, 40: beam, 42: strain gauge type strain measuring unit, 44: drive mechanism, 46: torque sensor, 48: strain generating body, 50: force receiving body, 50a: opening, 50v: threaded hole, 52: set screw, 54: frame, 56: set screw, 58: beam, 60: strain gauge type strain measuring unit

Claims

1. A torque sensor for detecting a reaction torque acting on a reducer in a rotary actuator including a rotary motor and a reducer connected in series to the rotary motor, a force receiving body that is disposed around the outside of a reducer case of the reducer, is fixed between the motor case of the rotary motor and the reducer case, and receives the reaction torque; a frame body disposed around the outside of the reducer case and fixed to the mounting portion; a plurality of beams provided to connect between the force receiving body and the frame body and arranged at intervals around the reducer case; a strain measuring unit provided on at least one of the plurality of beams, for measuring strain of the beam.

2. 2. The torque sensor according to claim 1, wherein the force receiving body, the frame body, and the plurality of beams are configured by a single strain generating body.

3. 2. The torque sensor according to claim 1, wherein the frame is located closer to the rotary motor than a portion of the output shaft of the reducer that protrudes from the reducer case.

4. The torque sensor according to claim 1, wherein the frame is spaced apart from the force receiving body in the axial direction.

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