Filament fixation structure, machine, robot, and actuator

Abstract

This wire body fixing structure comprises an actuator that is provided with a through hole through which a wire body passes, and a fixing part that fixes, in the space inside the through hole, the wire body between the axis of the actuator and the inner surface of the through hole.

Description

[Technical field]

[0001] The present invention relates to a filament fixing technology for a machine, and more particularly to a filament fixing structure, a machine, a robot, and an actuator. [Background technology]

[0002] In general, a collaborative robot requires a structure in which a filament such as a cable, tube, or wire is laid inside the robot mechanism so that it does not get entangled with a person. Even in robots other than collaborative robots, a filament may be laid inside the robot mechanism so that it does not interfere with objects in the robot's working space. In such a robot joint structure, a technology has been proposed in which a through hole is provided in an actuator such as an electric motor to which an electric motor, a reducer, a sensor, etc. is attached, a protective tube for protecting the filament is placed inside the through hole, and the filament is inserted into the protective tube to prevent the filament from contacting the actuator and improve the life of the filament. On the other hand, a technology has been proposed in which the filament is fixed and laid outside the exit of the through hole.

[0003] However, in the case of a rotating shaft structure of a machine such as a robot, a vehicle, or a construction machine, when a configuration is adopted in which a wire is inserted through the aforementioned through hole or protective tube, the space through which the wire passes becomes narrow, so there is a problem that the number of wires that can be passed through is limited. In particular, in the wrist shaft of a multi-joint robot, the actuator is small and the through hole tends to be narrow, making it difficult to pass many wires through. In recent years, the number of wires that can be passed through has tended to increase with the improvement in the performance of robot tools such as hands and sensors.

[0004] In addition, when the filament is fixed at a location outside the exit of the through hole and radially away from the rotation axis in the rotating shaft structure of the machine, the filament is subjected to not only torsional stress but also bending stress in response to the rotating operation of the machine. In addition, when the filament is fixed at the outside of the exit of the through hole, it becomes difficult to make the machine compact in the direction of the rotation axis due to the protrusion of the fixing member. The following documents are known as technologies related to the present application.

[0005] Patent Document 1 describes that in a wrist device for a robot, cables such as signal lines and power supply lines are led through a grommet into a first rotating part that rotates around a fourth axis, inserted into a first through hole of a swinging part that swings around a fifth axis, and further inserted into a second through hole of a second rotating part that swings around a sixth axis, and led through a grommet in a hand. It also describes that a cable protection tube is fixed to the second rotating part, and even if the cable is twisted by the rotation of the second rotating part, the cable is prevented from sliding against the first through hole of the swinging part and being damaged.

[0006] Patent Document 2 describes a robot device that includes a crank shaft having a hollow portion through which a cable is inserted, a first clamp that clamps the cable to a rotating housing, and a second clamp that clamps the cable to a support housing, and that the cable is fixed to the rotating housing and the support housing by the first and second clamps so that the cable is in an untwisted state when the rotation angle is 0 degrees.

[0007] Patent document 3 describes a rotating shaft structure for a robot that includes a first member, a second member rotatably supported relative to the first member, an actuator that rotates the second member relative to the first member, a sensor that detects a physical quantity acting between an output shaft member of the actuator and the second member, and a fixing member that fixes a wire, the fixing member being fixed to the output shaft member with a predetermined gap between it and the sensor.

[0008] Patent document 4 describes a drive unit for a robot in which a wire is inserted into a hollow hole in a reducer, and a first fixing member and a second fixing member for fixing the wire are attached to the end face of the reducer and to a bracket for mounting the reducer and motor, respectively.

[0009] Patent document 5 describes a robot wrist mechanism in which a control cable covered with a protective tube is partially wound around a hollow drive shaft, then unwound, passed through a pull-out section formed by cutting out part of the flange of the hollow drive shaft, and secured by a clamp just before the pull-out section.

[0010] Patent Document 6 describes an industrial robot in which cables are routed inside and outside the manipulator through a cable passage hole provided on the side of the manipulator, a cable protection tube is provided on the outside of the cables, and a cable protection tube fixture is provided that is connected to one end of the cable protection tube. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] JP 2009-125846 A [Patent Document 2] JP 2013-99826 A [Patent Document 3] Patent Publication No. 2021-3787 [Patent Document 4] Patent Publication No. 2021-84207 [Patent Document 5] JP 2006-021299 A [Patent Document 6] International Publication No. 2008 / 044348 Summary of the Invention [Problem to be solved by the invention]

[0012] In view of the problems of the prior art, an object of the present invention is to provide a filament fixing technique that can maintain or increase the number of filaments passing through while reducing the stress acting on the filaments. [Means for solving the problem]

[0013] One aspect of the present disclosure provides a filament fixing structure comprising: an actuator having a through hole through which a filament passes; and a fixing portion that fixes the filament in the internal space of the through hole between the axis of the actuator and the inner surface of the through hole. The actuator has a hollow member formed to rotate about an axis. The fixed portion includes a support member that supports the filament. The support member is formed to support the filament at a position separated from an inner circumferential surface of the hollow member so that the filament does not contact the hollow member. Another aspect of the present disclosure provides a machine, a robot, or an actuator including the aforementioned filamentary solid structure. Effect of the Invention

[0014] According to one aspect of the present disclosure, by fixing the filament in the internal space of the through hole, bending stress is not applied to the filament during operation of the actuator, compared to when the filament is fixed outside the outlet of the through hole and at a location radially away from the axis. Also, by fixing the filament at a position spaced a predetermined distance from the axis of the actuator, stress acting on the filament due to twisting of the filament during operation of the actuator can be alleviated, compared to when the filament is fixed on the axis of the actuator, and even if the internal space of the through hole becomes narrow, the internal space of the through hole can be made as wide as possible, so that the number of filaments inserted into the through hole can be maintained or increased. [Brief description of the drawings]

[0015] [Figure 1] 1 is a perspective view of a machine equipped with a wire body fixing structure of a first embodiment. FIG. [Diagram 2] FIG. 2 is a cross-sectional view of the filament fixing structure of the first embodiment. [Diagram 3] FIG. 2 is a rear view of the wire body fixing structure of the first embodiment. [Figure 4] FIG. 2 is a front view of the wire body fixing structure of the first embodiment. [Diagram 5] FIG. 2 is an enlarged rear cross-sectional view of the wire body fixing structure of the first embodiment. [Figure 6] FIG. 2 is an enlarged front cross-sectional view of the filament fixing structure of the first embodiment. [Figure 7] FIG. 11 is a cross-sectional view of a filament fixing structure according to a second embodiment. [Figure 8] FIG. 11 is a cross-sectional view of a wire body fixing structure according to a third embodiment. [Figure 9] FIG. 13 is a cross-sectional view of a wire body fixing structure according to a fourth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Hereinafter, the embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. In each drawing, the same or similar components are given the same or similar reference numerals. In addition, the embodiments described below do not limit the technical scope of the invention described in the claims and the meaning of the terms. Please note that in this specification, the term "front" or "front" refers to the output side or load side of the actuator, and the term "rear" or "back" refers to the opposite output side or opposite load side of the actuator. Also, please note that the term "axis" means the rotation axis in the case of a rotary actuator, and the linear axis in the longitudinal direction in the case of a linear actuator.

[0017] FIG. 1 is a perspective view of a machine 10 equipped with a filament fixing structure 1 of the first embodiment. The machine 10 of this embodiment is a robot, but in other embodiments, it may be another machine such as a vehicle or a construction machine. For example, the machine 10 is an industrial robot (e.g., a collaborative robot) with one or more filaments 2 installed therein, but in other embodiments, it may also include other types of robots such as humanoids. The filament fixing structure 1 of this embodiment is a joint structure of a robot, but in other embodiments, it may be a rotating shaft structure of a machine such as a vehicle or a construction machine. For example, the filament fixing structure 1 is a robot joint structure of a fourth axis J4, but may be a robot joint structure of an axis other than the fourth axis J4 as in the embodiment described later.

[0018] The machine 10 includes a base 11 and a rotating body 12 supported rotatably relative to the base 11 about a first axis J1. The machine 10 also includes a first arm 13 supported rotatably relative to the rotating body 12 about a second axis J2 perpendicular to the first axis J1, a second arm 14 (first link) supported rotatably relative to the first arm 13 about a third axis J3 parallel to the second axis J2, and a three-axis wrist unit 15 (second link) attached to the tip of the second arm 14. The machine 10 may further include a tool attached to the tip of the wrist unit 15, although not shown. For example, the tool may include a hand, a welding torch, a spot gun, etc.

[0019] The wrist unit 15 includes a first wrist element 16 supported rotatably with respect to the second arm 14 about a fourth axis J4 perpendicular to the third axis J3, and a second wrist element 17 supported rotatably with respect to the first wrist element 16 about a fifth axis J5 perpendicular to the fourth axis J4. Furthermore, the wrist unit 15 includes a third wrist element 18 supported rotatably with respect to the second wrist element 17 about a sixth axis J6 perpendicular to the fifth axis J5.

[0020] 2 to 4 are a cross-sectional view, a rear view, and a front view of the filament fixing structure 1 of the first embodiment, respectively. The filament fixing structure 1 of this embodiment includes an actuator 3 having a through hole 35 through which the filament 2 passes, and two fixing parts 4 and 5 that fix the filament 2 in the internal spaces S1 and S2 of the through hole 35. Furthermore, the filament fixing structure 1 of this embodiment includes a protective tube 36 that protects the filament 2 from the power transmission element of the actuator 3. For ease of understanding, it should be noted that the fixing parts 4 and 5 of this embodiment fix only one filament 2, but generally or in other embodiments, the fixing parts 4 and 5 fix a plurality of filaments 2. The filament 2 includes, for example, a wrist unit 15, a cable, a tube, a wire, etc. for operating a tool, etc.

[0021] The actuator 3 of this embodiment rotates the wrist unit 15 (second link) relative to the second arm 14 (first link) around the fourth axis J4. The actuator 3 of this embodiment includes an electric motor 30, a reducer 31, and a sensor 32. The electric motor 30 is formed, for example, by a known motor, the reducer 31 is formed, for example, by a known gear mechanism, and the sensor 32 is formed, for example, by a known torque sensor. The electric motor 30 is fixed to the second arm 14 (first link), an output shaft 30a of the electric motor 30 is connected to an input part (not shown, for example, an input gear) of the reducer 31, an output part 31a (for example, an output shaft or a case) of the reducer 31 is fixed to the sensor 32, and the sensor 32 is fixed to the wrist unit 15 (second link).

[0022] When the output shaft 30a of the electric motor 30 rotates, the output part 31a of the reduction gear 31 rotates at a speed slower than the rotation speed of the output shaft 30a of the electric motor 30, and the output part 31a of the reduction gear 31, the sensor 32, and the wrist unit 15 rotate together. As shown in Figs. 2 and 4, the sensor 32 of this embodiment includes an inner ring 32a fixed to the output part 31a of the reduction gear 31, an outer ring 32b fixed to the wrist unit 15 (second link), a plurality of beams 32c connecting the inner ring 32a and the outer ring 32b, and a strain gauge 32d attached to at least one beam 32c. The sensor 32 converts the amount of strain (amount of twist) generated in the beam 32c into an electric quantity (for example, a voltage value) and detects the torque around the axis of the actuator 3 (around the fourth axis J4 in this embodiment).

[0023] The actuator 3 has a through hole 35 through which the filament 2 passes. The through hole 35 in this embodiment passes through all of the electric motor 30, the reducer 31, and the sensor 32. The rear fixing part 4 fixes the filament 2 in the internal space S1 behind the through hole 35, and the front fixing part 5 fixes the filament 2 in the internal space S2 ahead of the through hole 35. More specifically, the rear fixing part 4 fixes the filament 2 in the internal space S1 of the electric motor 30 at a position spaced apart from the axis of the electric motor 30 (the fourth axis J4 in this embodiment), and the front fixing part 5 fixes the filament 2 in the internal space S2 of the sensor 32 at a position spaced apart from the axis of the sensor 32 (the fourth axis J4 in this embodiment). The two fixing parts 4 and 5 each have a support member 41, 51 that supports the filament 2, and a fastener 42, 52 that fastens the filament 2 to the support member 41, 51, respectively. The support members 41, 51 are constituted by brackets made of a rigid material such as metal, and the fasteners 42, 52 are constituted by clamps made of a flexible material such as resin. The support members 41, 51 include, for example, an L-shaped bracket or a U-shaped bracket, and the fasteners 42, 52 include, for example, a cable tie, a C-clamp, a U-bolt, etc. The fasteners 42, 52 may be a type in which the filament 26 is wrapped in a protective elastic body and the outer periphery is directly bound to the support members 41, 51 with a nylon band, or the like.

[0024] As shown in FIG. 2 and FIG. 3, the rear support member 41 of this embodiment has a fixed end 41a fixed to the rear of the housing 30b of the electric motor 30 by a fastener 43 such as a screw, and a free end 41b disposed in the internal space S1 behind the through hole 35. The rear support member 41 also has a main body portion 41c having the fixed end 41a, and an L-shaped portion 41d extending from the main body portion 41c to the free end 41b in an L-shape. The main body portion 41c may have, but is not limited to, a plurality of fixed ends 41a extending in the circumferential direction of the through hole 35 so as not to bend due to the load of the filament 2. The plurality of fixed ends 41a are fixed to the housing 30b of the electric motor 30 by a plurality of fasteners 43. The L-shaped portion 41d has a support surface 41e that supports the filament 2. The support surface 41e faces the axis of the actuator 3 (the fourth axis J4 in this embodiment). The rear fastener 42 of this embodiment fastens the filament 2 to the support surface 41e in the internal space S1 behind the through hole 35.

[0025] As shown in FIG. 2 and FIG. 4, the front support member 51 of this embodiment has a fixed end 51a fixed to the output part 31a of the reducer 31 by a fastener 53 such as a screw, and a free end 51b disposed in the internal space S2 in front of the through hole 35. The fastener 53 and the fixed end 51a are fixed to the output part 31a through the gap 32e of the sensor 32 without touching the sensor 32 so as not to affect the torque detection performance of the sensor 32. The front support member 51 also has a main body part 51c having the fixed end 51a, and an L-shaped part 51d extending from the main body part 51c in an L-shape to the free end 51b. The main body part 51c may have, but is not limited to, a plurality of fixed ends 51a extending in the circumferential direction of the through hole 35 so as not to bend due to the load of the filament 2. The plurality of fixed ends 51a are fixed to the output part 31a of the reducer 31 by a plurality of fasteners 53. The L-shaped portion 51d has a support surface 51e that supports the filament 2. The support surface 51e faces the axis of the actuator 3 (the fourth axis J4 in this embodiment). The front fastener 42 in this embodiment fastens the filament 2 to the support surface 51e in the internal space S2 in front of the through hole 35.

[0026] If the two fixing parts 4, 5 respectively fixed the filament 2 in the internal space near the middle of the through hole 35, rather than in the internal spaces S1, S2 respectively near the exits of the through hole 35, the distance D0 between the rear fastener 42 and the front fastener 52 would be relatively small, resulting in strong twisting of the filament 2. However, in this embodiment, the two fixing parts 4, 5 respectively fixed the filament 2 in the internal spaces S1, S2 respectively near the exits of the through hole 35, so the distance D0 between the rear fastener 42 and the front fastener 52 would be relatively large, thereby reducing twisting of the filament 2.

[0027] Furthermore, if the two fixing parts 4, 5 fix the filament 2 not in the internal spaces S1, S2 of the through hole 35 but outside the exit of the through hole 35 and away from the axis of the actuator 3 in the radial direction, not only torsional stress but also bending stress is applied to the filament 2 when the actuator 3 operates. However, since the two fixing parts 4, 5 of this embodiment fix the filament 2 in the internal spaces S1, S2 of the through hole 35, bending stress is less likely to act on the filament 2 when the actuator 3 operates.

[0028] Furthermore, if the two fixing parts 4, 5 each fix the filament 2 on the axis of the actuator 3, rather than between the axis of the actuator 3 (the fourth axis J4 in this embodiment) and the inner circumferential surface of the through-hole 35, the torsional stress of the filament 2 becomes relatively strong when the actuator 3 is in operation. However, since the two fixing parts 4, 5 in this embodiment each fix the filament 2 at a position spaced a predetermined distance from the axis of the actuator 3, the torsional stress of the filament 2 when the actuator 3 is in operation can be correspondingly alleviated.

[0029] In addition, the joint structure of the robot, particularly around the fourth axis J4, is smaller than the joint structures of the robots around the other axes, such as the first axis J1 to the third axis J3, and therefore the internal spaces S1, S2 of the through hole 35 tend to become narrower. However, in this embodiment, the two fixing portions 4, 5 each fix the filament 2 at a position away from the fourth axis J4. Therefore, even if the internal space of the through hole 35 becomes narrower, the internal spaces S1, S2 of the through hole 35 can be made as wide as possible, and therefore the number of filaments 2 inserted into the through hole 35 can be maintained or increased.

[0030] Furthermore, the actuator 3 rotates the wrist unit 15 (second link) forward or backward by 180 degrees from the reference position of the actuator 3 relative to the second arm 14 (first link). However, if the two fixing parts 4, 5 (two fasteners 42, 52) do not fix the filament 2 at approximately the same angular position or at an angular position shifted by approximately 180 degrees from each other around the axis of the actuator 3 at the reference position of the actuator 3, but fix the filament 2 at an angular position shifted by 45 degrees or an angular position shifted by 60 degrees from each other around the axis of the actuator 3, the filament 2 may already be twisted at the reference position of the actuator 3, and the twisting of the filament 2 during the operation of the actuator 3 will become even stronger. However, the two fixing parts 4, 5 of this embodiment fix the filament 2 at approximately the same angular position or at an angular position shifted by approximately 180 degrees from each other around the axis of the actuator 3 at the reference position of the actuator 3, and therefore the twisting of the filament 2 during the operation of the actuator 3 can be mitigated. Also, when passing the wire through the through hole, it is easier to pass the wire through in a straight line at the reference position of the actuator 3.

[0031] Since the filament 2 is pulled by a pulling force every time the actuator of another connecting part of the machine 10 (another joint part of the robot in this embodiment) operates, the filament 2 is laid between the two fixing parts 4, 5 (two fasteners 42, 52) with a predetermined amount of slack, and at least one of the support surfaces 41e, 51e of the supporting members 41, 51 supporting the filament 2 and the contact surfaces of the fasteners 42, 52 with respect to the filament 2 should be smooth so that the filament 2 does not break due to friction with the supporting members 41, 51 or the fasteners 42, 52. The "predetermined amount" is the difference between the length between the two fixing parts 4, 5 when stretched straight and the length between the two fixing parts 4, 5 when slackened, but in other embodiments, it may be the radius of curvature of the slack. The predetermined amount should be determined in advance by performing an experiment in which all connecting parts of the machine 10 are operated. For example, the contact surfaces of the support surfaces 41e, 51e and the fasteners 42, 52 may be made smooth with resin or the like, or may be coated with a lubricant such as lubricating oil or grease. Coating the entire movable part of the wire with grease is expected to improve the life of the wire.

[0032] In addition, the filament 2 in this embodiment is inserted into the hollow hole 36c of the protective tube 36, and the protective tube 36 protects the filament 2 from the power transmission elements of the actuator 3. The filament 2 is fixed to the output part 31a of the reducer 31 by the front fixing part 5, and therefore rotates forward and backward by 180 degrees together with the output part 31a of the reducer 31, the sensor 32, and the wrist unit 15. However, when the actuator 3 includes the reducer 31 as in this embodiment, the rotation speed of the output shaft 30a of the electric motor 30 is much higher than the rotation speed of the output part 31a of the reducer 31, so that the filament 2 may come into contact with the power transmission elements of the actuator 3, such as the output shaft 30a of the electric motor 30 or the input part (e.g., an input gear) of the reducer 31, in the through hole 35, and may be damaged or broken. Therefore, the protective tube 36 protects the filament 2 from the power transmission elements of the actuator 3.

[0033] The protective tube 36 is a flanged tubular member made of, for example, resin. The protective tube 36 is shorter than the length of the through hole 35 and is disposed within the through hole 35. The protective tube 36 includes a cylindrical portion 36a and a flange portion 36b extending radially from the cylindrical portion 36a. The flange portion 36b of the protective tube 36 in this embodiment is sandwiched between the output portion 31a (first member) of the reducer 31 and the sensor 32 (second member). When the flange portion 36b is fixed to the output portion 31a of the reducer 31 by a fastener such as a screw, the axial size of the actuator 3 increases by only the head portion of the screw. However, by sandwiching the flange portion 36b between the first member and the second member as in this embodiment, the axial size of the actuator 3 can be made compact.

[0034] The filament fixing structure 1 may further include an elastic body 37 interposed between the flange portion 36b of the protective tube 36 and the sensor 32. For example, the elastic body 37 may be an O-ring made of an elastic material such as an elastomer. The elastic body 37 is housed in a ring-shaped recess formed in the flange portion 36b of the protective tube 36, but is not limited thereto. The elastic body 37 may protrude forward in the axial direction from the flange portion 36b and may be in surface contact with the sensor 32, thereby increasing the frictional force with the sensor 32. In other words, the longitudinal section of the elastic body 37 may be rectangular. Also, it is preferable that only the elastic body 37 having a relatively high friction coefficient contacts the inner ring 32a of the sensor 32, and that the flange portion 36b of the protective tube 36 having a relatively low friction coefficient does not contact the inner ring 32a of the sensor 32. When the inner ring 32a of the sensor 32 is fixed to the output part 31a of the reducer 31, the elastic body 37 is compressed between the inner ring 32a of the sensor 32 and the flange portion 36b of the protective tube 36, and the restoring force of the elastic body 37 presses the flange portion 36b of the protective tube 36 against the end face of the output part 31a of the reducer 31, thereby clamping the protective tube 36 between the output part 31a of the reducer 31 and the sensor 32.

[0035] Only the elastic body 37 having a relatively high friction coefficient contacts the inner ring 32a of the sensor 32, and the flange portion 36b of the protective tube 36 is pressed against the end surface of the output portion 31a of the reducer 31 by the restoring force of the elastic body 37, so that the protective tube 36 rotates together with the output portion 31a of the reducer 31 and the sensor 32 without shifting in the circumferential direction relative to the sensor 32 when the actuator 3 is in operation. If the protective tube 36 shifts in the circumferential direction relative to the sensor 32, the torque detection performance of the sensor 32 may be affected, but since the protective tube 36 of this embodiment rotates together with the sensor 32, the torque detection performance of the sensor 32 is not affected. In addition, the elastic body 37 comes into surface contact with the inner ring 32a of the sensor 32, and the flange portion 36b of the protective tube 36 is pressed against the end surface of the output portion 31a of the reducer 31 by the restoring force of the elastic body 37, the protective tube 36 and the elastic body 37 also have a secondary effect of improving the waterproofness of the front side of the actuator 3.

[0036] Furthermore, the flange portion 36b of the protective tube 36 extends perpendicular to the cylindrical portion 36a, and the flange portion 36b is in surface contact with the end face of the output portion 31a of the reducer 31, so that the cylindrical portion 36a extends parallel to the axis (fourth axis J4) of the actuator 3. This makes it difficult for the cylindrical portion 36a of the protective tube 36 to come into contact with power transmission elements of the actuator 3, such as the output shaft 30a of the electric motor 30 and the input portion (e.g., an input gear) of the reducer 31, inside the through hole 35.

[0037] Since the protective tube 36 is shorter than the length of the through hole 35, the two fixing parts 4, 5 fix the filament 2 in the internal spaces S1, S2 of the through hole 35 on the outer side of the outlet of the protective tube 36, respectively. The front fixing part 5 is fixed to the output part 31a of the reducer 31 and therefore rotates integrally with the protective tube 36, but the rear fixing part 4 is fixed to the rear part of the housing 30b of the electric motor 30 and therefore does not rotate integrally with the protective tube 36. The rear fixing part 4 is disposed in the internal space S1 of the through hole 35 as described below so that the filament 2 fixed by the rear fixing part 4 is not damaged by contact with the protective tube 36 that rotates when the actuator 3 is operated.

[0038] 5 is an enlarged rear cross-sectional view of the filament fixing structure 1 of the first embodiment. The support member 41 of the rear fixing part 4 is disposed so that the distance D1 from the axis of the actuator 3 (fourth axis J4 in this embodiment) to the support surface 41e of the support member 41 is shorter than the distance D2 from the axis of the actuator 3 to the inner peripheral surface of the hollow hole 36c of the protective tube 36 (i.e., D2-D1>0). As a result, the filament 2 does not come into contact with the protective tube 36 that rotates when the actuator 3 is in operation, so that damage or breakage of the filament 2 can be prevented.

[0039] In addition, the support member 41 of the rear fixed part 4 is preferably arranged so that the distance D3 from the free end 41b of the support member 41 to the end face 36d of the protective tube 36 is shorter than the thickness D4 of the filament 2 or the bundle of filaments 2 (i.e., D3-D4<0). This prevents the filament 2 from coming into contact with the protective tube 36 that rotates when the actuator 3 operates and from being entangled between the end face 36d of the protective tube 36 and the free end 41b of the support member 41, thereby preventing damage or breakage of the filament 2. In addition, the corners of the free end 41b of the support member 41 on the filament 2 side are preferably rounded so that the slack filament 2 is not damaged even if it comes into contact with the free end 41b of the support member 41.

[0040] 6 is an enlarged front cross-sectional view of the filament fixing structure 1 of the first embodiment. Unlike the rear fixing part 4, the front fixing part 5 is fixed to the output part 31a of the reducer 31 and rotates integrally with the protective tube 36. Therefore, the support member 51 of the front fixing part 5 may be provided so that the distance D1 from the axis of the actuator 3 (the fourth axis J4 in this embodiment) to the support surface 51e of the support member 51 is substantially the same as the distance D2 from the axis of the actuator 3 to the inner peripheral surface of the hollow hole 36c of the protective tube 36 (i.e., D2-D1=0). As a result, even if the hollow hole 36c of the protective tube 36 becomes narrow, the number of filaments 2 inserted into the hollow hole 36c of the protective tube 36 can be maintained or increased.

[0041] Similarly to the rear fixed part 4, the support member 51 of the front fixed part 5 is preferably disposed such that the distance D3 from the free end 51b of the support member 51 to the end face 36d of the protective tube 36 is shorter than the thickness D4 of the filament 2 or the bundle of filaments 2 (i.e., D3-D4<0). This causes the filament 2 to enter between the end face 36d of the protective tube 36 and the free end 51b of the support member 51 and not to come into contact with the sensor 32, thereby suppressing the effect on the torque detection performance of the sensor 32 caused by contact between the filament 2 and the sensor 32.

[0042] As described above, according to the first embodiment of the filament fixing structure 1, by fixing the filament 2 in the internal spaces S1 and S2 of the through hole 35, bending stress is less likely to act on the filament 2 during operation of the actuator 3, and only torsional stress is applied, compared to the case where the filament 2 is fixed on the outside of the exit of the through hole 35. Furthermore, by fixing the filament 2 at a position away from the axis of the actuator 3 (the fourth axis J4 in this embodiment), torsion of the filament 2 during operation of the actuator 3 can be alleviated, compared to the case where the filament 2 is fixed on the axis of the actuator 3, and even if the internal space of the through hole 35 becomes narrow, the number of filaments 2 inserted into the through hole 35 can be maintained or increased.

[0043] Modifications of the filament fixing structure 1 of the first embodiment will be described below. The actuator 3 of the first embodiment rotates the wrist unit 15 (second link) relative to the second arm 14 (first link) about the fourth axis J4, but as in a fourth embodiment described later, the actuator 3 may also rotate the first arm 13 (second link) relative to the rotating body 12 (first link) about the second axis J2. The actuator 3 of other embodiments may also rotate the second arm 14 relative to the first arm 13 (first link) about the third axis J3. In other words, the filament fixing structure 1 can be applied to any rotation shaft structure of the machine 10.

[0044] Moreover, the actuator 3 in the first embodiment includes the electric motor 30, the reducer 31, and the sensor 32, but may include the electric motor 30 connected to at least one of the reducer 31, the sensor 32, and other mechanical elements as in a second, third, or fourth embodiment described below. Also, the actuator 3 in other embodiments may include only the electric motor 30. Moreover, the actuator 3 in the first embodiment is a rotary actuator, but may be a linear actuator in other embodiments.

[0045] In addition, the through hole 35 of the actuator 3 in the first embodiment penetrates all of the electric motor 30, the reducer 31, and the sensor 32, but it may also penetrate at least one of the electric motor 30, the reducer 31, the sensor 32, and other mechanical elements, as in the second, third, or fourth embodiment described below.

[0046] Further, although the filament fixing structure 1 of the first embodiment includes two fixing parts 4, 5, in other embodiments, it may include either one of the two fixing parts 4, 5. Furthermore, as in a third or fourth embodiment described later, at least one of the two fixing parts 4, 5 may fix the filament 2 in the internal spaces S1, S2 of the through hole 35, and the other may fix the filament 2 in the external space of the through hole 35. Furthermore, as in a second, third, or fourth embodiment described later, at least one of the two fixing parts 4, 5 may be fixed to the first link (e.g., the second arm 14 or the rotating body 12) or the second link (e.g., the wrist unit 15 or the first arm 13) instead of the actuator 3.

[0047] In addition, the filament fixing structure 1 of the first embodiment includes the protective tube 36, but when the actuator 3 does not include the reducer 31 as in the second embodiment described later, the filament fixing structure 1 may not include the protective tube 36. In addition, the flange portion 36b of the protective tube 36 of the first embodiment is sandwiched between the output portion 31a (first member) of the reducer 31 and the sensor 32, but when the actuator 3 does not include the sensor 32 as in the third or fourth embodiment described later, the flange portion 36b of the protective tube 36 may be sandwiched between the first member (the output portion 31a of the reducer 31) and the second member (wrist unit 15, first arm 13, etc.). In addition, as in the second, third, or fourth embodiment described later, the filament fixing structure 1 may include at least one of the first link (e.g., the second arm 14 or the rotating body 12) and the second link (e.g., the wrist unit 15 or the second arm 14).

[0048] 7 is a cross-sectional view of the wire body fixing structure 1 of the second embodiment. The actuator 3 of the second embodiment differs from the wire body fixing structure 1 of the first embodiment in that it does not include a reduction gear 31, but only includes an electric motor 30 and a sensor 32. The sensor 32 is fixed to the output shaft 30a of the electric motor 30. The front fixed part 5 is also fixed to the output shaft 30a of the electric motor 30. The output shaft 30a of the electric motor 30, the sensor 32, and the wrist unit 15 (second link) rotate together. The through hole 35 of the actuator 3 passes only through the electric motor 30 and the sensor 32.

[0049] Since the actuator 3 of the second embodiment does not include the reducer 31, the rotation speed of the output shaft 30a of the electric motor 30 does not become excessively higher than the rotation speed of the output part 31a of the reducer 31. Since the output shaft 30a of the electric motor 30 and the sensor 32 rotate forward or backward by only 180 degrees when the actuator 3 is in operation, the filament fixing structure 1 of the second embodiment does not include the protective tube 36. However, since the rear fixing part 4 does not rotate integrally with the output shaft 30a of the electric motor 30 and the sensor 32, the filament 2 is fixed between the axis of the actuator 3 (the fourth axis J4 in this embodiment) and the inner circumferential surface of the through hole 35 in the internal space S1 behind the through hole 35 so that the filament 2 does not come into contact with the output shaft 30a of the electric motor 30 and is not damaged when the actuator 3 is in operation. More specifically, the rear fixing portion 4 fixes the filament 2 in the internal space S1 of the electric motor 30 at a position spaced apart from the axis of the electric motor 30 (the fourth axis J4 in this embodiment).

[0050] On the other hand, since the front fixing part 5 rotates integrally with the output shaft 30a of the electric motor 30 and the sensor 32, the filament 2 does not come into contact with the output shaft 30a of the electric motor 30 and is not damaged when the actuator 3 is in operation. However, the front fixing part 5 fixes the filament 2 between the axis of the actuator 3 (the fourth axis J4 in this embodiment) and the inner circumferential surface of the through hole 35 in the internal space S2 in front of the through hole 35. More specifically, the front fixing part 5 fixes the filament 2 at a position separated from the axis of the sensor 32 (the fourth axis J4 in this embodiment) in the internal space S2 of the sensor 32. As a result, compared to the case where the filament 2 is fixed on the axis of the actuator 3, it is possible to reduce the twisting of the filament 2 when the actuator 3 is in operation, and even if the internal space of the through hole 35 becomes narrow, the internal spaces S1 and S2 of the through hole 35 can be made as wide as possible, so that the number of filaments 2 passing through the through hole 35 can be maintained or increased.

[0051] In addition, in order to make the number of wires 2 passing through the through hole 35 approximately the same in the internal spaces S1 and S2 of the through hole 35, it is preferable that the distance D1a from the axis of the actuator 3 (the fourth axis J4 in this embodiment) to the support surface 41e of the rear support member 41 is approximately the same as the distance D1b from the axis of the actuator 3 to the support surface 51e of the front support member 51 (i.e., D1a = D1b).

[0052] The wire body fixing structure 1 of the second embodiment also differs from the wire body fixing structure 1 of the first embodiment in that the rear fixing part 4 is fixed to the inside 14a of the second arm 14 (first link) instead of to the rear part of the housing 30b of the electric motor 30. In other words, the rear fixing part 4 does not necessarily need to be fixed to the actuator 3. The support member 41 of the rear fixing part 4 is fixed to the inside 14a of the second arm 14 by a fastener 43 such as a screw. On the other hand, the front fixing part 5 is fixed to the output shaft 30a of the electric motor 30 without touching the sensor 32 so as not to affect the torque detection performance of the sensor 32. Since the rear fixing part 4 is fixed to the second arm 14, the wire body fixing structure 1 of the second embodiment may further include the second arm 14 (first link).

[0053] As described above, according to the wire body fixing structure 1 of the second embodiment, even if the actuator 3 does not include the reducer 31, by fixing the wire body 2 in the internal spaces S1 and S2 of the through hole 35, bending stress is not applied to the wire body 2 during operation of the actuator, compared to the case where the wire body 2 is fixed on the outside of the outlet of the through hole 35. Furthermore, by fixing the wire body 2 at a position away from the axis of the actuator 3 (the fourth axis J4 in this embodiment), twisting of the wire body 2 during operation of the actuator 3 can be alleviated, compared to the case where the wire body 2 is fixed on the axis of the actuator 3, and even if the internal space of the through hole 35 becomes narrow, the internal spaces S1 and S2 of the through hole 35 can be made as wide as possible, so that the number of wire bodies 2 inserted into the through hole 35 can be maintained or increased.

[0054] Furthermore, since the distance D1a from the axis of the actuator 3 (the fourth axis J4 in this embodiment) to the support surface 41e of the rear support member 41 is approximately the same as the distance D1b from the axis of the actuator 3 to the support surface 51e of the front support member 51 (i.e., D1a = D1b), it becomes possible to make the number of filaments 2 passed through the through hole 35 approximately the same in the internal spaces S1 and S2 of the through hole 35.

[0055] FIG. 8 is a cross-sectional view of the filament fixing structure 1 of the third embodiment. The actuator 3 of the third embodiment is different from the filament fixing structure 1 of the first embodiment in that it does not include a sensor 32, and includes only an electric motor 30 and a reducer 31. The output portion 31a of the reducer 31 is fixed to the wrist unit 15 (second link). In addition, the flange portion 36b of the protective tube 36 is sandwiched between the output portion 31a (first member) of the reducer 31 and the wrist unit 15 (second member). The elastic body 37 is interposed between the flange portion 36b of the protective tube 36 and the wrist unit 15 (second member). The output portion 31a of the reducer 31, the protective tube 36, and the wrist unit 15 (second link) rotate together. The through hole 35 of the actuator 3 passes through only the electric motor 30 and the reducer 31.

[0056] Similar to the filament fixing structure 1 of the first embodiment, the rear fixing part 4 fixes the filament 2 in the internal space S1 behind the through hole 35 between the axis of the actuator 3 (the fourth axis J4 in this embodiment) and the inner circumferential surface of the through hole 35. More specifically, the rear fixing part 4 fixes the filament 2 in the internal space S1 of the electric motor 30 at a position spaced apart from the axis of the electric motor 30 (the fourth axis J4 in this embodiment). In other words, the rear fixing part 4 fixes the filament 2 in the internal space S1 of the through hole 35 outside the outlet of the protective tube 36.

[0057] On the other hand, the internal space S2 in front of the through hole 35 is occupied by the protective tube 36 and is therefore narrower than the internal space S1 behind the through hole 35. Therefore, the wire body fixing structure 1 of the third embodiment differs from the wire body fixing structure 1 of the first embodiment in that the front fixing part 5 fixes the wire body 2 not in the internal space of the through hole 35 but in the internal space of the wrist unit 15 (second link) outside the outlet of the through hole 35. More specifically, the front fixing part 5 fixes the wire body 2 in the internal space of the wrist unit 15 at a position spaced apart from the axis of the wrist unit 15 (the fourth axis J4 in this embodiment).

[0058] The support member 51 of the front fixed part 5 is fixed to the inside 15a of the wrist unit 15 with a fastener 53 such as a screw. The rear fixed part 4 is fixed to the actuator 3, but the front fixed part 5 is not necessarily fixed to the actuator 3. Since the front fixed part 5 is fixed to the wrist unit 15, the filament fixing structure 1 of the third embodiment may further include a wrist unit 15 (second link).

[0059] As described above, according to the third embodiment of the filament fixing structure 1, even if the actuator 3 does not have a sensor 32, the two fixing portions 4, 5 fix the filament 2 at a position away from the axis of the actuator 3 (the fourth axis J4 in this embodiment), as in the first embodiment of the filament fixing structure 1. Therefore, compared to the case where the filament 2 is fixed on the axis of the actuator 3, twisting of the filament 2 during actuator operation can be reduced. Furthermore, even if the internal space of the through hole 35 becomes narrow, the internal spaces S1, S2 of the through hole 35 can be made as wide as possible, so that the number of filaments 2 inserted into the through hole 35 can be maintained or increased.

[0060] FIG. 9 is a cross-sectional view of the filament fixing structure 1 of the fourth embodiment. The filament fixing structure 1 of the fourth embodiment is different from the filament fixing structure 1 of the first embodiment in that it is a robot joint structure of the second axis J2, not a robot joint structure of the fourth axis J4. That is, the actuator 3 of the fourth embodiment rotates the first arm 13 around the second axis J2 with respect to the rotating body 12 (first link). The actuator 3 of the fourth embodiment does not include a sensor 32, but includes an electric motor 30, a plurality of reducers 31, 33, and other mechanical elements 34. The rear reducer 33 is configured with a known gear mechanism, like the front reducer 31, and the mechanical elements 34 are configured with, for example, a known chain, belt, gear mechanism, or the like. The plurality of reducers 31, 33 are connected in series.

[0061] The electric motor 30 is fixed to the rotating body 12 (first link), the output shaft (not shown) of the electric motor 30 is connected to the mechanical element 34, and the mechanical element 34 is connected to an input part (not shown, for example, an input gear) of the rear reducer 33. The output part 33a of the rear reducer 33 is connected to an input part (not shown, for example, an input gear) of the front reducer 31, and the output part 31a of the front reducer 31 is fixed to the first arm 13 (second link). The flange part 36b of the protective tube 36 is clamped between the output part 31a (first member) of the reducer 31 and the first arm 13 (second member). The elastic body 37 is interposed between the flange part 36b of the protective tube 36 and the first arm 13 (second member).

[0062] When the output shaft of the electric motor 30 rotates, the output portion 33a of the rear reducer 33 rotates at a slower speed than the output shaft of the electric motor 30, and the output portion 31a of the front reducer 31 rotates at a slower speed than the output portion 33a of the rear reducer 33, so that the output portion 31a of the front reducer 31, the protective tube 36, and the first arm 13 (second link) rotate together. The through hole 35 of the fourth embodiment passes through only the multiple reducers 31, 33.

[0063] The rear fixing part 4 fixes the filament 2 in the internal space S1 behind the through hole 35 between the axis of the actuator 3 (the second axis J2 in this embodiment) and the inner circumferential surface of the through hole 35. More specifically, the rear fixing part 4 fixes the filament 2 in the internal space S1 of the reducer 31 at a position spaced apart from the axis of the reducer 31 (the second axis J2 in this embodiment). In other words, the rear fixing part 4 fixes the filament 2 in the internal space S1 of the through hole 35 outside the outlet of the protective tube 36.

[0064] On the other hand, the internal space S2 in front of the through hole 35 is occupied by the protective tube 36 and is therefore narrower than the internal space S1 behind the through hole 35. Thus, the filament fixing structure 1 of the fourth embodiment differs from the filament fixing structure 1 of the first embodiment in that the front fixing part 5 fixes the filament 2 not in the internal space of the through hole 35 but in the internal space of the first arm 13 (second link) outside the outlet of the through hole 35. More specifically, the front fixing part 5 fixes the filament 2 in the internal space of the first arm 13 at a position spaced apart from the axis of the first arm 13 (second axis J2 in this embodiment).

[0065] The support member 51 of the front fixing part 5 is fixed to the interior 13a of the first arm 13 with a fastener 53 such as a screw. The rear fixing part 4 is fixed to the actuator 3, but the front fixing part 5 is not necessarily fixed to the actuator 3. Since the front fixing part 5 is fixed to the first arm 13, the filament fixing structure 1 of the fourth embodiment may further include a first arm 13 (second link).

[0066] As described above, according to the fourth embodiment of the filament fixing structure 1, even if the joint structure of another robot is used, or even if the actuator 3 has multiple reducers 31, 33 and the through hole 35 passes only through the multiple reducers 31, 33, the two fixing portions 4, 5 fix the filament 2 at a position away from the axis of the actuator 3 (the second axis J2 in this embodiment), as in the first embodiment of the filament fixing structure 1. Therefore, compared to the case where the filament 2 is fixed on the axis of the actuator 3, twisting of the filament 2 during operation of the actuator can be reduced, and even if the internal space of the through hole 35 becomes narrow, the internal spaces S1, S2 of the through hole 35 can be made as wide as possible, so that the number of filaments 2 inserted into the through hole 35 can be maintained or increased.

[0067] Although various embodiments have been described herein, it should be appreciated that the present invention is not limited to the above-described embodiments, but may be modified in various ways within the scope of the appended claims. [Explanation of symbols]

[0068] 1. Striatal fixation structure 2. Striatum 3 Actuator 4, 5 Fixed part 10 machines 11. Base 12 Swivel body 13 First Arm 13a Inside the first arm 14 Second Arm 14a Inside the second arm 15 Wrist Unit 15a Inside the wrist unit 16 First wrist element 17 Second Wrist Element 18 Third Wrist Element 30 Electric motor 30a Output shaft 30b Housing 31 Reducer 31a Output section 32 Sensors 32a Inner Circle 32b Outer ring 32c beam part 32d Strain Gauge 32e void 33 Reducer 34 Mechanical Elements 35 Through hole 36 Protection tube 36a Cylindrical part 36b Flange part 36c hollow hole 36d end face 41, 51 Support member 41a, 51a fixed end 41b, 51b free end 41c, 51c Main body 41d, 51d L-shaped part 42, 42 Fastener 43, 53 Fasteners J1~J6 axis D0 Distance between rear and front fasteners D1: Distance from the axis of the actuator to the support surface of the support member D2 Distance from the axis of the actuator to the inner surface of the hollow hole of the protective tube D3 Distance from the free end of the support member to the end face of the protective tube D4 Thickness of the striatum or thickness of the striatum bundle D1a Distance from the axis of the actuator to the support surface of the rear support member D1b Distance from the axis of the actuator to the support surface of the front support member

Claims

1. an actuator having a through hole through which a filament passes; a fixing portion that fixes the filament between an axis of the actuator and an inner circumferential surface of the through hole in an internal space of the through hole, the actuator includes a hollow member configured to rotate about the axis; the fixing portion includes a support member that supports the filament, A filament fixing structure, wherein the support member is formed to support the filament at a position radially spaced from an inner surface of the hollow member so that the filament does not come into contact with the hollow member.

2. 2. The wire fixing structure according to claim 1, further comprising a protective tube disposed in the through hole to protect the wire from a power transmission element of the actuator, the fixing portion fixing the wire in an internal space of the through hole outside an outlet of the protective tube.

3. A filament fixing structure as described in Claim 2, wherein the distance from the axis to the support member is shorter than or approximately the same as the distance from the axis to the inner surface of the protective tube.

4. 4. The wire fixing structure according to claim 2, wherein a distance from the free end of the support member to an end face of the protective tube is shorter than a thickness of the wire or a thickness of the bundle of wires.

5. The wire fixing structure according to claim 1 , wherein a corner of the free end of the support member facing the wire is rounded.

6. 6. The wire fixing structure according to claim 1, wherein the actuator comprises only an electric motor, or comprises an electric motor connected to at least one of a reducer, a sensor, and other mechanical elements, and the fixing portion fixes the wire in an internal space of the electric motor, the reducer, or the sensor.

7. The filament is supported at two points on the load side and the anti-load side of the actuator, The filament fixing structure according to claim 1 , wherein the filament is fixed by the fixing portion on at least one of a load side and an anti-load side.

8. The fixing portion is arranged on both the load side and the anti-load side of the actuator, 8. The wire fixing structure according to claim 7, wherein the load side fixing portion and the anti-load side fixing portion fix the wire at approximately the same angular positions or angular positions shifted by approximately 180 degrees from each other around the axis of the actuator at a reference position of the actuator.

9. 9. The wire fixing structure according to claim 7 or 8, wherein the fixing portion includes a fastener for fastening the wire to the support member, the wire is laid loosely between two fasteners, and at least one of a support surface of the support member supporting the wire and a contact surface of the fastener with respect to the wire is smooth.

10. A filament fixing structure as described in Claim 7, wherein the filament is fixed at the fixing portion on the anti-load side of the actuator.

11. The actuator includes an electric motor, The wire fixing structure according to claim 1 , wherein the support member is fixed to a housing of the electric motor.

12. A machine having a filament fixing structure described in any one of claims 1 to 11.

13. A robot having a filament fixing structure described in any one of claims 1 to 11.

14. An actuator having a filament fixing structure described in any one of claims 1 to 11.

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