Rotating shaft structure and machinery

Abstract

Conventionally, there has been a demand for a technology that, for example under the necessity of downsizing a rotary shaft structure, enables wiring of an increased number of filament bodies within the rotary shaft structure. This rotary shaft structure 50 comprises: a hollow fixed part 136; a hollow rotary part 134 that is disposed on the fixed part 136 so as to be rotatable about a rotary axis J4 and that, together with the fixed part 136, defines a through-hole 138 which penetrates the rotary part 134 and the fixed part 136 in the direction of the rotary axis J4 and through which filament bodies 26 pass; and a restriction member 58 that restricts the filament bodies 26 in the rotary part 134 so as to allow the filament bodies 26 to rotate along with the rotary part 134 within a section A between one open end 138a and the other open end 138b of the through-hole 138.

Description

[Technical Field]

[0001] The present disclosure relates to a rotating shaft structure and a machine. [Background technology]

[0002] BACKGROUND ART A rotating shaft structure for a machine (so-called actuator) is known (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-159397 Summary of the Invention [Problem to be solved by the invention]

[0004] Conventionally, for example, in response to a demand for miniaturization of a rotating shaft structure, there has been a demand for a technology that enables wiring of a larger number of wires inside the rotating shaft structure. [Means for solving the problem]

[0005] The rotating shaft structure includes a hollow fixed portion, a hollow rotating portion provided on the fixed portion so as to be rotatable around the rotation axis, the rotating portion penetrating the rotating portion and the fixed portion in the direction of the rotation axis and defining, together with the fixed portion, a through hole through which the filament passes, and a restraining member restraining the filament to the rotating portion so that the filament rotates together with the rotating portion in the section from one opening end to the other opening end of the through hole. [Effects of the Invention]

[0006] According to the present disclosure, even when the rotating part rotates, the wires are not twisted inside the through-hole. Therefore, the wires can be densely wired inside the through-hole, and therefore, even when the rotating shaft structure is miniaturized, a sufficient number of wires can be wired inside the through-hole. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a perspective view of a machine according to one embodiment; [Figure 2] FIG. 2 is a cross-sectional view of the rotating shaft structure shown in FIG. [Figure 3] FIG. 3 is a view of the sensor shown in FIG. 2 as seen from the axial direction. [Figure 4] FIG. 10 is a perspective view of a machine according to another embodiment. [Figure 5] FIG. 5 is a cross-sectional view of the rotating shaft structure shown in FIG. [Figure 6] FIG. 10 is a cross-sectional view of a rotating shaft structure according to another embodiment. [Figure 7] FIG. 7 is a view of the rotating shaft structure shown in FIG. 6 as seen from the axial front side. [Figure 8] FIG. 10 is a perspective view of a machine according to yet another embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. Note that in various embodiments described below, similar elements will be given the same reference numerals, and redundant description will be omitted. First, a machine 10 according to one embodiment will be described with reference to FIG. 1. In this embodiment, the machine 10 is a vertical articulated robot and includes a robot base 12, a rotating body 14, an upper arm 16, a forearm 18, and a wrist 20. In this embodiment, the rotating body 14, the upper arm 16, the forearm 18, and the wrist 20 are each hollow.

[0009] The robot base 12 is fixed to the floor of a work cell or on an automated guided vehicle (AGV). The rotating body 14 is provided on the robot base 12 so as to be rotatable about a first rotation axis J1. The first rotation axis J1 may be arranged parallel to the vertical direction. The upper arm 16 is provided on the rotating body 14 so as to have a base end 16a thereof rotatable about a second rotation axis J2 that is perpendicular to the first rotation axis J1.

[0010] In this embodiment, the forearm 18 has a base arm 22 and a distal arm 24. The base arm 22 has a base portion 22a provided at the distal end 16b of the upper arm 16 so as to be rotatable about a third rotation axis J3 parallel to the second rotation axis J2, and a cylindrical portion 22b extending from the base portion 22a in the direction of a fourth rotation axis J4 perpendicular to the third rotation axis J3. On the other hand, the distal arm 24 has a base end portion 24a provided on the cylindrical portion 22b so as to be rotatable about the fourth rotation axis J4.

[0011] The wrist section 20 has a wrist base 20a and a wrist flange 20b. The wrist base 20a has a substantially L-shaped outer shape and is provided at the distal end section 24b of the distal arm 24 so as to be rotatable about a fifth rotation axis J5 that is perpendicular to the fourth rotation axis J4. The wrist flange 20b is provided at the wrist base 20a so as to be rotatable about a sixth rotation axis J6 that is perpendicular to the fifth rotation axis J5.

[0012] An end effector (not shown, such as a robot hand, welding torch, cutting tool, or laser processing head) is detachably attached to the wrist flange 20b. The machine 10 rotates the rotating body 14, upper arm 16, forearm 18 (base arm 22, distal arm 24), and wrist 20 (wrist base 20a, wrist flange 20b) about the respective rotation axes J1 to J6 to position the end effector at any desired position, and performs a predetermined task on a workpiece (such as workpiece handling, welding, cutting, or laser processing) using the end effector.

[0013] The machine 10 further includes a umbilical member 26 and a rotary shaft structure 50. The umbilical member 26 includes, for example, a power line that supplies power to an electric motor (e.g., a servo motor) built into the machine 10, a control signal line that transmits a signal for controlling the end effector, an air tube, or the like.

[0014] One end of the umbilical member 26 is connected to a control device (not shown) of the machine 10, and the other end is connected to the end effector. The umbilical member 26 is wired so as to pass through the inside of the robot base 12, the rotating body 14, the upper arm 16, the forearm 18, and the wrist 20 and connect to the end effector.

[0015] The rotating shaft structure 50 is referred to as an actuator and is disposed between the base arm 22 and the distal arm 24. The rotating shaft structure 50 rotates the distal arm 24 about a fourth rotation axis J4 relative to the base arm 22. The rotating shaft structure 50 will be described below with reference to FIG. 2. In the following description, the direction of the fourth rotation axis J4 is referred to as the axial direction, the radial direction of a circle centered on the fourth rotation axis J4 is referred to as the radial direction, and the circumferential direction of the circle is referred to as the circumferential direction. For convenience, the direction indicated by arrow D in FIG. 2 will be referred to as the axial forward direction.

[0016] The rotating shaft structure 50 includes an electric motor 52, a reducer 54, a sensor 56, and a restraining member 58. In this embodiment, the electric motor 52, the reducer 54, and the sensor 56 are arranged approximately coaxially with respect to the fourth rotation axis J4 and are arranged side by side in the axial direction. The electric motor 52 includes a housing 62, a stator 64, a rotor 66, an encoder 68, and a brake mechanism 70.

[0017] The housing 62 is cylindrical and accommodates the stator 64, the rotor 66, the encoder 68, and the brake mechanism 70. The housing 62 is fixed to the cylindrical portion 22b of the base-end arm 22 (FIG. 1). The stator 64 has a cylindrical stator core 72 fixed to the housing 62 and a coil 74 wound around the stator core 72.

[0018] The rotor 66 is rotatably disposed radially inside the stator 64. Specifically, the rotor 66 has a rotor shaft 76 and a rotor core 78. The rotor shaft 76 is cylindrical and extends straight in the axial direction. The rotor shaft 76 is rotatably supported in the housing 62 by annular bearings 80 and 82.

[0019] The bearing 80 is interposed between the support wall 62a of the housing 62 and the rotor shaft 76, and the bearing 82 is interposed between the support wall 62b of the housing 62 and the rotor shaft 76. In addition, an annular oil seal 83 is interposed between the support wall 62b and the rotor shaft 76.

[0020] The support wall 62a is disposed axially rearward of the stator 64 and the rotor core 78, while the support wall 62b is disposed axially forward of the stator 64 and the rotor core 78. A space S1 that houses the stator 64 and the rotor core 78 is defined inside the housing 62 by the support walls 62a and 62b.

[0021] The rotor core 78 is a cylindrical member incorporating a plurality of magnets (not shown) arranged in the circumferential direction, and is fixed to the outer circumferential surface of the rotor shaft 76 so as to rotate integrally with the rotor shaft 76. The stator 64 generates a circumferential rotating magnetic field by applying a voltage to the coils 74, thereby generating power that rotates the rotor core 78 in the circumferential direction. In this way, the rotor 66 rotates about the fourth rotation axis J4 relative to the housing 62 and the stator 64.

[0022] The encoder 68 detects the rotation (for example, the rotational position or rotation angle) of the rotor 66. Specifically, the encoder 68 has a rotational slit 68a, a light-emitting portion 68b, and a light-receiving portion 68c. The rotational slit 68a has a plurality of slits and is fixed to the outer circumferential surface of the rotor shaft 76 so as to rotate integrally with the rotor shaft 76. The rotational slit 68a is disposed between the light-emitting portion 68b and the light-receiving portion 68c.

[0023] The light-emitting unit 68b is fixed to the housing 62 and emits light toward the rotary slit 68a. The light-receiving unit 68c is fixed to the housing 62 and receives the light output by the light-emitting unit 68b. More specifically, the light output by the light-emitting unit 68b is patterned by passing through a slit formed in the rotary slit 68a and is then incident on the light-receiving unit 68c. The encoder 68 detects the rotation of the rotor 66 based on the patterned light received by the light-receiving unit 68c.

[0024] The brake mechanism 70 brakes the rotation of the rotor 66. Specifically, the brake mechanism 70 has a brake disc 70a, an end plate 70b, an armature 70c, and a brake core 70d. The brake disc 70a is fixed to the outer peripheral surface of the rotor shaft 76 so as to rotate integrally with the rotor shaft 76.

[0025] The end plate 70b is fixed to the brake core 70d. The armature 70c is disposed opposite the end plate 70b and is attached to the brake core 70d so as to be movable in the axial direction. The brake disc 70a is disposed between the end plate 70b and the armature 70c, and the armature 70c is biased toward the brake disc 70a by a biasing member (not shown) such as a coil spring.

[0026] The brake core 70d is fixed to the housing 62, and a brake coil (not shown) is wound around the brake core 70d. When a voltage is applied to the brake coil, the brake core 70d is excited, which attracts the armature 70c to the brake core 70d and moves it away from the brake disc 70a. In this way, the brake mechanism 70 releases the braking force applied to the rotor 66, allowing the rotor 66 to rotate.

[0027] On the other hand, when the voltage applied to the brake coil becomes zero, the brake core 70d is de-energized, and the armature 70c is pressed against the brake disc 70a by the action of the biasing member. In this way, the brake mechanism 70 brakes the rotation of the rotor 66. The encoder 68 and the brake mechanism 70 are disposed on the axial rear side of the support wall 62a, and a space S2 that houses the encoder 68 and the brake mechanism 70 is defined inside the housing 62 by the support wall 62a and the axial rear end wall 62c of the housing 62.

[0028] The reducer 54 is provided axially forward of the electric motor 52 and reduces the rotation speed of the rotor 66. Specifically, the reducer 54 is, for example, a planetary gear reducer, a wave gear reducer, or a cycloid reducer, and has a housing 84, an internal gear 86, an external gear 88, and an output shaft 90. The housing 84 is cylindrical and is fixed to the housing 62 of the electric motor 52.

[0029] The internal gear 86 is disposed so as to surround the axial front end of the rotor shaft 76, and meshes with a gear portion formed at the axial front end. The external gear 88 is rotatably supported by the housing 84 via an annular bearing 92, and is disposed radially outside the internal gear 86 and meshes with the internal gear 86.

[0030] The output shaft 90 is annular and is provided axially front of the housing 84 so as to be rotatable about the fourth rotation axis J4. More specifically, the output shaft 90 has a main body 94, an outer flange 96, and an inner flange 98. The main body 94 is connected to the external gear 88 via an output pin 95, and the rotation of the external gear 88 is transmitted to the main body 94 through the output pin 95. Note that instead of the output pin 95, a bolt or the like may be used to directly connect the main body 94 and the external gear 88.

[0031] In addition, an annular oil seal 100 is interposed between an inner peripheral surface 94a of the main body 94 and the rotor shaft 76. The oil seals 83 and 100 prevent the lubricant filled inside the rotating shaft structure 50 from leaking out, and also prevent foreign matter from entering the rotating shaft structure 50 from the outside.

[0032] The outer flange 96 protrudes radially outward from the outer peripheral surface 94b of the main body portion 94 and extends circumferentially. Meanwhile, the inner flange 98 protrudes radially inward from the inner peripheral surface 94a of the main body portion 94 and extends circumferentially. The inner flange 98 is disposed axially forward and spaced apart from the axial front end 76a of the rotor shaft 76.

[0033] The sensor 56 is disposed adjacent to the axial front side of the output shaft 90, and detects a force (e.g., torque) acting on the sensor 56. The sensor 56 will be described below with reference to Fig. 3. The sensor 56 is annular, and has an inner ring 102, an outer ring 104, a plurality of beams 106, and a plurality of strain gauges 108.

[0034] The inner ring 102 has a through hole in its center. The outer ring 104 is disposed radially outward from the inner ring 102 at a distance. The beam portions 106 extend radially between the inner ring 102 and the outer ring 104 and are disposed side by side at approximately equal intervals in the circumferential direction. A gap 110 is defined between two beam portions 106 adjacent to each other in the circumferential direction.

[0035] Strain gauges 108 are provided on each beam portion 106 and convert strain generated in the beam portion 106 into an electrical signal. In this embodiment, the inner ring 102 is fixed to the main body portion 94 of the output shaft 90 with fasteners (not shown) such as bolts, while the outer ring 104 is fixed to the base end portion 24a of the distal arm 24 with fasteners (not shown) such as bolts. In this state, the inner ring 102 abuts against the output shaft 90 (specifically, the main body portion 94), while the outer ring 104 and beam portions 106 are separated from the output shaft 90.

[0036] When the stator 64 of the electric motor 52 rotates the rotor 66 in the circumferential direction at a speed V1, the internal gear 86 and external gear 88 of the reducer 54 are also rotated by the rotor shaft 76. The internal gear 86 and external gear 88 are interposed between the rotor shaft 76 and the output shaft 90, and transmit the rotation of the rotor shaft 76 to the output shaft 90 via the output pin 95 after reducing the rotation speed from speed V1 to speed V2 (<<V1).

[0037] In this way, the reducer 54 decelerates the rotation of the rotor 66. For example, the speed V2 is 1% or less of the speed V1. The sensor 56 rotates integrally with the output shaft 90 in the circumferential direction at the speed V2, and as a result, the distal arm 24 fixed to the outer ring 104 of the sensor 56 also rotates in the circumferential direction at the speed V2. In this way, the distal arm 24 rotates relative to the base arm 22.

[0038] In this way, the rotor 66 (rotor shaft 76, rotor core 78), rotation slit 68a, brake disc 70a, internal gear 86, external gear 88, output shaft 90, and sensor 56 are rotated by the power generated by the stator 64. Therefore, in this embodiment, the rotor 66, rotation slit 68a, brake disc 70a, internal gear 86, external gear 88, output shaft 90, and sensor 56 constitute a rotating part 134 of the rotating shaft structure 50. Each of the rotor 66, rotation slit 68a, brake disc 70a, internal gear 86, external gear 88, output shaft 90, and sensor 56 can be defined as a rotating element of the rotating part 134.

[0039] On the other hand, the housing 62 and stator 64 (stator core 72, coil 74) of the electric motor 52, the light-emitting portion 68b and light-receiving portion 68c of the encoder 68, the end plate 70b and brake core 70d of the brake mechanism 70, and the housing 84 of the reducer 54 are fixed to the base end arm 22.

[0040] Therefore, in the present embodiment, the housings 62 and 84, the light-emitting unit 68b and the light-receiving unit 68c, the end plate 70b and the brake core 70d, and the stator 64 constitute a fixed portion 136 of the rotating shaft structure 50. Each of the housings 62 and 84, the light-emitting unit 68b and the light-receiving unit 68c, the end plate 70b and the brake core 70d, and the stator 64 can be defined as a fixed element of the fixed portion 136.

[0041] The rotating portion 134 is provided on the fixed portion 136 so as to be rotatable in the circumferential direction, and each of the rotating portion 134 and the fixed portion 136 is hollow, and a through hole 138 is defined inside the rotating portion 134 and the fixed portion 136, passing through the rotating portion 134 and the fixed portion 136 in the axial direction.

[0042] In the present embodiment, the through hole 138 is disposed approximately coaxially with the fourth rotation axis J4, and has a first open end 138a that opens to the outside at the axial rear end 76b of the rotor shaft 76 (or the axial rear end of the end wall 62c), and a second open end 138b that opens to the outside at the axial front end of the sensor 56 (specifically, the inner ring 102). The wire 26 is wired to pass through the inside of the through hole 138.

[0043] Restraint member 58 restrains filament 26 to rotating portion 134 so that filament 26 rotates together with rotating portion 134 in axial section A from first open end 138a to second open end 138b. Specifically, restraint member 58 has a restraint tube 140, a first fixing member 142, and a second fixing member 144.

[0044] Restraint tube 140 is disposed inside through hole 138 so as to surround filament 26 from the radially outer side across section A. More specifically, restraint tube 140 is made of, for example, metal, resin, rubber, or a combination thereof, and has a tubular portion 146 that surrounds filament 26 in section A, and a flange portion 148 that extends radially outward from tubular portion 146.

[0045] In this embodiment, the tubular portion 146 is cylindrical and extends within the through-hole 138 so that its axial rear end portion 146a protrudes axially rearward beyond the axial rear end 76b of the rotor shaft 76 and the axial rear end surface of the end wall 62c, while its axial front end portion 146b protrudes axially forward beyond the axial front end surface of the sensor 56.

[0046] Flange portion 148 is disposed at a position closer to axial front end 146b than to axial rear end 146a of cylindrical portion 146, and extends circumferentially around the entire circumference of outer circumferential surface 146c of cylindrical portion 146. In the present embodiment, flange portion 148 is sandwiched between inner ring 102 of sensor 56 and inner flange 98 of output shaft 90, whereby restraint pipe 140 is disposed approximately coaxially with rotor shaft 76 with respect to fourth rotation axis J4, and is held inside through hole 138 so that cylindrical portion 146 extends parallel to the axial direction.

[0047] In this way, with flange portion 148 sandwiched between inner ring 102 and inner flange 98, restraint pipe 140 is fixed to sensor 56 and output shaft 90 of rotating portion 134, and rotates integrally with sensor 56 and output shaft 90 at speed V2. At this time, outer peripheral surface 146c of cylindrical portion 146 is approximately parallel to inner circumferential surface 76c of rotor shaft 76, and is spaced radially inward from inner circumferential surface 76c.

[0048] Therefore, the cylindrical portion 146, which rotates at speed V2 together with the sensor 56 and the output shaft 90, does not interfere with the rotor shaft 76, which rotates at speed V1. This prevents the cylindrical portion 146 from being damaged by interference with the rotor shaft 76, which rotates at a higher speed.

[0049] An elastic member (such as an O-ring) may be interposed between flange portion 148 and inner ring 102. In this case, flange portion 148 and inner ring 102 may be spaced apart from each other in the axial direction. With this configuration, the force applied from flange portion 148 to inner ring 102 can be reduced, thereby improving the force detection accuracy of sensor 56.

[0050] Furthermore, restraint pipe 140 may be fixed to inner flange 98 (or inner ring 102) by fastening flange portion 148 to inner flange 98 (or inner ring 102) with fasteners such as bolts. In this case, flange portion 148 may be disposed so as to be spaced apart from inner ring 102.

[0051] The first fixing member 142 is provided at the axial rear end portion 146a of the tubular portion 146 so as to be adjacent to the first open end 138a, and fixes the filament 26 to the axial rear end portion 146a so as not to rotate relative to the filament 26. In the present embodiment, the first fixing member 142 is disposed slightly axially rearward from the first open end 138a (or the axial rear end 76b of the rotor shaft 76 and the axial rear end surface of the end wall 62c).

[0052] The first fixing member 142 is, for example, a heat-shrinkable resin (so-called heat-shrinkable tubing), a shape-memory resin, or a restraining band (for example, a nylon band), and fastens the filament 26 and the axial rear end portion 146a from the outer periphery, thereby fixing the filament 26 to the axial rear end portion 146a so that it cannot rotate relative to the filament 26.

[0053] On the other hand, the second fixing member 144 is provided at the axial front end 146b of the tubular portion 146 so as to be adjacent to the second open end 138b, and fixes the filament 26 to the axial front end 146b so as not to rotate relative to it. In this embodiment, the second fixing member 144 is disposed slightly axially forward from the second open end 138b (or the axial front end face of the sensor 56).

[0054] The second fixing member 144 is made of a heat-shrinkable resin, a shape-memory resin, a restraining band, or the like, similar to the first fixing member 142, and fastens the filament 26 and the axial front end portion 146b from the outer periphery, thereby fixing the filament 26 to the axial front end portion 146b so as not to rotate relative to the filament 26. An adhesive may be applied to the inner circumferential surface of at least one of the first fixing member 142 and the second fixing member 144.

[0055] Furthermore, the axial rear end portion 146a of the cylindrical portion 146 may be disposed at a distance radially inward of the rotor shaft 76 (in other words, housed inside the through-hole 138). In this case, the axial rear end portion 146a of the cylindrical portion 146 does not protrude axially rearward beyond the axial rear end 76b of the rotor shaft 76 and the axial rear end surface of the end wall 62c.

[0056] Similarly, the axial front end 146b of the cylindrical portion 146 may be disposed radially inwardly of and spaced from the inner ring 102 of the sensor 56 (in other words, housed inside the through hole 138). In this case, the axial front end 146b of the cylindrical portion 146 does not protrude axially forward beyond the axial front end face of the sensor 56.

[0057] In this way, when the axial rear end 146a and the axial front end 146b of the tubular portion 146 are housed inside the through hole 138, at least one of the first fixing member 142 and the second fixing member 144 may be housed inside the through hole 138 so as not to come into contact with the rotor shaft 76 and the inner ring 102 of the sensor 56.

[0058] By being fixed to restraint tube 140 by first fixing member 142 and second fixing member 144, wire body 26 is restrained inside inner circumferential surface 146d of tubular portion 146 so as not to be able to rotate relative to the inside of inner circumferential surface 146d, and is wired so as to extend in the axial direction inside inner circumferential surface 146d. Wire body 26 is then fixed to sensor 56 and output shaft 90 of rotating portion 134 via restraint tube 140, first fixing member 142, and second fixing member 144.

[0059] By means of such restraint member 58 (restraint tube 140, first fixing member 142 and second fixing member 144), the filament 26 is restrained to the sensor 56 and the output shaft 90 so that when the sensor 56 and the output shaft 90 rotate, the filament 26 rotates at a speed V2 together with the sensor 56 and the output shaft 90 in section A.

[0060] As described above, in this embodiment, the rotating shaft structure 50 comprises a hollow fixed portion 136, a hollow rotating portion 134 that is rotatably mounted on the fixed portion 136 and defines a through hole 138 together with the fixed portion 136, and a restraining member 58 that restrains the filament 26 to the rotating portion 134 so that the filament 26 rotates together with the rotating portion 134 (specifically, the sensor 56 and the output shaft 90) in section A.

[0061] According to this configuration, even if the rotating part 134 rotates, the umbilical member 26 does not twist in the section A inside the through-hole 138. Therefore, the umbilical member 26 can be densely wired inside the through-hole 138, so that even if the rotating shaft structure 50 is made compact, for example, a sufficient number of the umbilical member 26 can be wired inside the through-hole 138.

[0062] Furthermore, in this embodiment, restraint member 58 is disposed inside through hole 138 so as to surround filament 26 in section A, and has a cylindrical restraint tube 140 fixed to rotating section 134 so as to rotate together with rotating section 134 (sensor 56 and output shaft 90), with filament 26 being restrained inside restraint tube 140 so as not to rotate relative to the rotating section 134. According to this configuration, filament 26 can be effectively restrained to rotating section 134 across section A via restraint tube 140, and therefore filament 26 can be effectively prevented from twisting in section A when rotating section 134 rotates.

[0063] Moreover, in the present embodiment, restraint pipe 140 has a cylindrical portion 146 that surrounds filament 26 in section A, and a flange portion 148 that extends radially outward from cylindrical portion 146 and is fixed to rotating portion 134 (sensor 56, output shaft 90). According to this configuration, filament 26 can be restrained by cylindrical portion 146 across section A, while restraint pipe 140 can be easily fixed to rotating portion 134 via flange portion 148.

[0064] In addition, in this embodiment, the restraint member 58 further has a first fixing member 142 that is provided adjacent to the first opening end 138a and fixes the filament 26 to the rotating part 134 (sensor 56, output shaft 90), and a second fixing member 144 that is provided adjacent to the second opening end 138b and fixes the filament 26 to the rotating part 134.

[0065] According to this configuration, the filament 26 can be restrained by the rotating part 134 at a position adjacent to the first opening end 138a and at a position adjacent to the second opening end 138b, thereby more effectively preventing the filament 26 from twisting in section A when the rotating part 134 rotates.

[0066] At least one of first fixing member 142 and second fixing member 144 may be omitted from restraint member 58. In this case, restraint member 58 may have restraint tube 140 and an adhesive applied to inner circumferential surface 146d of tubular portion 146 of restraint tube 140. In this case as well, it is possible to restrain filament 26 inside tubular portion 146.

[0067] Alternatively, instead of providing an adhesive on inner circumferential surface 146d, wire 26 may be densely wired inside restraint tube 140 so that wire 26 is tightly attached to inner circumferential surface 146d of tubular portion 146 with pressure. In this case, wire 26 is restrained inside restraint tube 140 by the frictional force between wire 26 and inner circumferential surface 146d. In this way, restraint member 58 may have any structure for restraining wire 26 to tubular portion 146 so that it cannot move.

[0068] Next, a machine 30 according to another embodiment will be described with reference to Figures 4 and 5. The machine 30 differs from the above-described machine 10 in that it includes a first type of filament 26A, a second type of filament 26B, a fixing structure 32, and a rotary shaft structure 150. The fixing structure 32 is provided on the base-end arm 22 (specifically, the base portion 22a or the cylindrical portion 22b), and is disposed axially rearward of the through-hole 138 at a distance.

[0069] More specifically, the fixing structure 32 has a main body 32a fixed to the base arm 22 and a clamp 32b fixed to the main body 32a. The second type of filament 26B is inserted into and fixed to the clamp 32b, and is thereby fixed to the base arm 22 and the fixing portion 136.

[0070] Rotating shaft structure 150 differs from the above-described rotating shaft structure 50 in restraint member 152. Specifically, restraint member 152 further has a circuit relay portion 154 in addition to the above-described restraint tube 140, first fixed member 142, and second fixed member 144. In the present embodiment, circuit relay portion 154 is incorporated integrally with first fixed member 142, and is fixed to sensor 56 and output shaft 90 of rotating portion 134 via restraint tube 140.

[0071] As one example, the circuit relay unit 154 is a connector that electrically connects the first type of wire body 26A and the second type of wire body 26B. As another example, the circuit relay unit 154 may be a circuit board (such as a printed circuit board (PCB)) that electrically connects the first type of wire body 26A and the second type of wire body 26B by soldering or the like. As yet another example, the circuit relay unit 154 may be soldering itself, which connects the first type of wire body 26A and the second type of wire body 26B, instead of a circuit board. As yet another example, the circuit relay unit 154 may have a crimp terminal that connects the first type of wire body 26A and the second type of wire body 26B.

[0072] The first-type umbilical member 26A is, for example, a non-movable umbilical member that extends axially forward from the circuit relay portion 154 and passes through Section A. On the other hand, the second-type umbilical member 26B is, for example, a movable umbilical member that has higher resistance to deformation (specifically, torsion or bending) than the first-type umbilical member 26A. The second-type umbilical member 26B is disposed axially rearward of the through-hole 138, extends in Section B (second section) between the through-hole 138 (specifically, the circuit relay portion 154) and the fixing structure 32 (specifically, the clamp portion 32b), and is connected to the first-type umbilical member 26A via the circuit relay portion 154.

[0073] In this embodiment, the circuit relay section 154 is entirely housed inside the first fixing member 142, so that the front end 26B' ​​of the second type of filament 26B, which is connected to the circuit relay section 154, is surrounded and fixed by the first fixing member 142. Note that at least a portion of the filament 26A or 26B may be formed from a circuit board.

[0074] When the sensor 56 and the output shaft 90 are rotated, the circuit relay portion 154 rotates circumferentially relative to the clamp portion 32b of the fixing structure 32, and as a result, the second-type filament 26B is twisted in the section B. Here, as described above, the second-type filament 26B has higher resistance to deformation (torsion or bending) load than the first-type filament 26A, and therefore can be prevented from breaking even if it is twisted in the section B.

[0075] Furthermore, in this embodiment, as described above, the front end 26B' ​​of the second-type umbilical member 26B is surrounded and fixed by the first fixing member 142. With this configuration, even if the second-type umbilical member 26B is twisted in section B in conjunction with the rotation of the sensor 56 and the output shaft 90, the torsion of the second-type umbilical member 26B can be prevented from being transmitted to the circuit relay portion 154 through the front end 26B'.

[0076] This prevents the electrical continuity between the first type of filament 26A and the second type of filament 26B from being cut off at the circuit relay section 154. An annular clamp member may be built into the first fixing member 142, and the front end 26B' ​​of the second type of filament 26B may be clamped by the clamp member, thereby immobilizing the front end 26B' ​​inside the first fixing member 142.

[0077] In addition, the axial distance L of section B B is the axial distance L of section A A or more (i.e., L B ≧L A ) may be set as the distance L B By setting the above, the shear force acting on the second type filament 26B when the second type filament 26B is twisted in the section B can be reduced, thereby effectively preventing breakage.

[0078] As described above, in this embodiment, the machine 30 further includes the fixing structure 32 that fixes the umbilical member 26B to the fixing portion 136 outside the through-hole 138, and as the rotating portion 134 (sensor 56 and output shaft 90) rotates, the umbilical member 26B is twisted in section B. With this configuration, by fixing the umbilical member 26B to the base end arm 22, wiring can be effectively performed inside the base end arm 22. Note that the fixing structure 32 may be fixed to the fixing portion 136 of the rotating shaft structure 150 via a mounting fixture.

[0079] In this embodiment, the umbilical member 26 includes a first-type umbilical member 26A extending in section A, and a second-type umbilical member 26B extending in section B, connected to the first-type umbilical member 26A, and having higher resistance to deformation (torsion or bending) load than the first-type umbilical member 26A. This configuration effectively prevents the second-type umbilical member 26B from breaking even if it is twisted in section B.

[0080] In this embodiment, the restraining member 152 is fixed to the rotating portion 134 (the sensor 56 and the output shaft 90) and includes a circuit relay portion 154 that electrically connects the first type of umbilical member 26A and the second type of umbilical member 26B. This configuration allows the first type of umbilical member 26A and the second type of umbilical member 26B to be easily connected and disconnected. In this embodiment, the second type of umbilical member 26B (or the first type of umbilical member 26A) may be used as the umbilical member 26 in both sections A and B. In this case, the circuit relay portion 154 can be omitted.

[0081] Next, a method for assembling rotating shaft structure 150 and wire bodies 26A and 26B will be described. First, the manufacturer inserts first type of wire body 26A into restraint tube 140, first fixing member 142, and second fixing member 144, and connects one end of the wire body to circuit relay section 154, thereby manufacturing wire body unit 156 as an assembly of first type of wire body 26A and restraint member 152.

[0082] Next, the manufacturer manufactures an assembly of electric motor 52 and reducer 54. Next, the manufacturer fixes sensor 56 to output shaft 90 with flange portion 148 of restraint tube 140 interposed between sensor 56 and output shaft 90. In this way, flange portion 148 is sandwiched between sensor 56 and output shaft 90, and umbilical unit 156 is fixed to rotating portion 134 (specifically, sensor 56 and output shaft 90).

[0083] Next, the manufacturer inserts and fixes the second type of wire body 26B into the clamp portion 32b of the fixing structure 32, and connects one end of the wire body 26B to the circuit relay portion 154. In this way, the wire bodies 26A and 26B are wired to pass through sections A and B, thereby completing the assembly of the rotating shaft structure 150 and the wire bodies 26A and 26B.

[0084] Note that the above-described restraint pipe 140 may be made of a combination of resin and metal (e.g., iron). For example, flange portion 148 may be made of metal, while tubular portion 146 may be made of resin. In this case, the axial rear end surface of flange portion 148 may be formed by cutting to increase flatness. With this configuration, the axial rear end surface of flange portion 148 and the axial front end surface of inner flange 98 facing the rear end surface are brought into close contact with each other, thereby increasing the frictional force between them. Note that restraint pipe 140 may be made of only metal. Also, first type umbilical cord 26A may be made of second type umbilical cord 26B. In this case, second type umbilical cord 26B is wired in sections A and B.

[0085] 6 and 7, a rotating shaft structure 160 according to another embodiment will be described. The rotating shaft structure 160 differs from the above-described rotating shaft structure 150 in a restraining member 162. The restraining member 162 is made of, for example, metal or resin, and, like the above-described restraining member 58, restrains the umbilical member 26 to the sensor 56 and the output shaft 90 of the rotating unit 134 so that the umbilical member 26 rotates together with the sensor 56 and the output shaft 90 in section A.

[0086] More specifically, the restraint member 162 has an attachment portion 164, a first arm portion 166, a second arm portion 168, a first fixing member 170, and a second fixing member 172. The attachment portion 164 is a hollow flat member having a substantially rectangular outer shape as shown in FIG. 7, and is fixed to the output shaft 90 by a plurality of fasteners 174 (e.g., bolts) so as to be spaced apart axially forward of the sensor 56. In this embodiment, each fastener 174 passes through the gap 110 of the sensor 56, and its tip is fastened to a fastening hole 94c formed in the main body portion 94 of the output shaft 90.

[0087] The first arm portion 166 extends radially inward from the inner surface of the portion that forms one vertex of the mounting portion 164, and extends radially to a position adjacent to the second open end 138b. The second arm portion 168 extends axially rearward from the radially inner end of the first arm portion 166, and extends axially to a position adjacent to the first open end 138a.

[0088] The first fixing member 170 is, for example, an annular member, and is provided integrally with the axial rear end of the second arm portion 168 so as to be adjacent to the first open end 138a. The first fixing member 170 has the umbilical member 26 inserted therethrough and fixed thereto, thereby fixing the umbilical member 26 to the sensor 56 and the output shaft 90 of the rotating portion 134. In this embodiment, the first fixing member 170 is disposed inside the through-hole 138.

[0089] The first fixing member 170 may have a pair of openable and closable claws that sandwich the filament 26 to clamp the filament 26. Alternatively, the first fixing member 170 may wrap the filament 26 in a protective elastic body and bind the outer periphery of the elastic body to the second arm portion 168 with a restraining band (such as a nylon band) to restrain the filament 26.

[0090] Alternatively, the first fixing member 170 may be a heat-shrinkable resin or the like that fastens the filament 26 to the second arm portion 168, like the first fixing member 142 described above, or the first fixing member 142 may be applied in addition to the first fixing member 170, and the filament 26 may be fastened to the first fixing member 170 by the first fixing member 142.

[0091] On the other hand, the second fixing member 172 has a configuration similar to that of the first fixing member 170, and is provided integrally with the axial front end of the second arm portion 168 so as to be adjacent to the second open end 138b. The second fixing member 172 has the wire body 26 inserted therethrough and fixed thereto, thereby fixing the wire body 26 to the sensor 56 and the output shaft 90 of the rotating portion 134. In this embodiment, the second fixing member 172 is disposed inside the inner ring 102 of the sensor 56.

[0092] The second fixing member 172 may be a heat-shrinkable resin or the like that fastens the filament 26 to the second arm portion 168, like the second fixing member 144 described above, or the second fixing member 144 may be applied in addition to the second fixing member 172, and the filament 26 may be fastened to the second fixing member 172 by the second fixing member 144.

[0093] In this embodiment, the restraining member 162 is separated from the sensor 56 and does not come into contact with the sensor 56. As described above, the fastener 174 also passes through the gap 110 of the sensor 56 and does not come into contact with the sensor 56. By completely spatially separating the restraining member 162 and the fastener 174 from the sensor 56 in this way, the force applied to the sensor 56 from the restraining member 162 and the fastener 174 can be made substantially zero. This improves the force detection accuracy of the sensor 56.

[0094] The restraining member 162 restrains the filament 26 so that it cannot rotate relative to the sensor 56 using the first fixing member 170 and the second fixing member 172. As a result, the filament 26 is restrained by the sensor 56 and the output shaft 90 so that when the sensor 56 and the output shaft 90 rotate, the filament 26 rotates together with the sensor 56 and the output shaft 90 at a speed V2 in section A.

[0095] As described above, in this embodiment, the restraint member 162 has a first fixing member 170 that is provided adjacent to the first opening end 138a and fixes the filament 26 to the rotating part 134 (sensor 56, output shaft 90), and a second fixing member 172 that is provided adjacent to the second opening end 138b and fixes the filament 26 to the rotating part 134.

[0096] According to this configuration, the filament 26 can be restrained by the rotating part 134 at a position adjacent to the first opening end 138a and at a position adjacent to the second opening end 138b, thereby more effectively preventing the filament 26 from twisting in section A when the rotating part 134 rotates.

[0097] It is possible to combine the features of the above-described rotating shaft structures 50, 150, and 160. For example, flange portion 148 may be omitted from restraint tube 140 of rotating shaft structure 50 and applied to rotating shaft structure 160, with wire body 26 inserted inside restraint tube 140 and restraint tube 140 clamped to first fixing member 170 and second fixing member 172 of restraint member 162. Alternatively, circuit relay portion 154 of rotating shaft structure 150 may be provided integrally with first fixing member 170 of rotating shaft structure 160, with first type wire body 26A wired in Section A and second type wire body 26B wired in Section B, and the two connected at circuit relay portion 154.

[0098] The above-described machine 10 or 30 (or the machine 30′ described below) may further include an electronic component such as a circuit board disposed within the through-hole 138. The reducer 54 may also be omitted from the above-described rotating shaft structure 50, 150, or 160 (so-called direct drive system).

[0099] In the above embodiment, the electric motor 52, the reducer 54, and the sensor 56 are arranged approximately coaxially with respect to the fourth axis of rotation J4 and are arranged side by side in the axial direction. However, this is not limiting, and for example, the electric motor 52 may be arranged at a position offset from the axis of rotation J4.

[0100] In this case, the electric motor 52 may include a stator 64 disposed at a position offset from the rotation axis J4, an output shaft that is rotationally driven by the stator 64, a rotor shaft 76 disposed coaxially with the rotation axis J4, and a rotation transmission mechanism (for example, a pulley mechanism) that transmits the rotation of the output shaft to the rotor shaft 76. The electric motor 52 may also be disposed radially outward of the reducer 54 and the sensor 56.

[0101] Furthermore, the sensor 56 is not limited to a configuration having the inner ring 102, the outer ring 104, and the beam portion 106, and may be a configuration in which, for example, a strain gauge 108 is provided on a circular member such as the inner ring 102. Furthermore, in the rotating shaft structure 50, 150, or 160, any circular member may be used as a rotating element instead of the reducer 54 or the sensor 56.

[0102] Furthermore, in the above-described embodiment, the case has been described in which restraint pipe 140 is disposed coaxially with rotor shaft 76 with axis J4 as the reference. However, this is not limiting, and restraint pipe 140 may be disposed at a position where its central axis is offset in the radial direction from fourth rotational axis J4. In this case, cylindrical portion 146 is held so as to extend parallel to fourth rotational axis J4, while the central axis of cylindrical portion 146 is disposed offset in the radial direction from fourth rotational axis J4 by a predetermined distance.

[0103] In the above embodiment, the case has been described in which the housing 62 is fixed to the cylindrical portion 22b of the base-end arm 22, and the sensor 56 (outer ring 104) is fixed to the base end portion 24a of the distal arm 24. However, this is not limiting, and the housing 62 may be fixed to the base end portion 24a of the distal arm 24, and the sensor 56 (e.g., the outer ring 104) may be fixed to the cylindrical portion 22b of the base-end arm 22. Such a configuration is shown in FIG.

[0104] In the machine 30′ shown in FIG. 8, the rotary shaft structure 150 shown in FIGS. 4 and 5 is arranged inside the base arm 22 and the tip arm 24 with the axial direction reversed, and the outer ring 104 of the sensor 56 is fixed to the cylindrical portion 22b of the base arm 22, while the housing 62 of the electric motor 52 is fixed to the base end portion 24a of the tip arm 24.

[0105] The fixing structure 32 is provided inside the distal arm 24 and is disposed at a distance from the through-hole 138 (specifically, the open end 138a) in a direction toward the distal end 24b of the distal arm 24. The second type of filament 26B extends from the rotation shaft structure 150 toward the distal end 24b of the distal arm 24 and is inserted into and fixed to the inside of the clamp portion 32b (FIG. 5) of the fixing structure 32. In this way, the second type of filament 26B is fixed to the distal arm 24 and the fixing portion 136.

[0106] In this embodiment, when the stator 64 of the electric motor 52 generates power to rotate the rotor 66, the sensor 56 and output shaft 90 of the rotating part 134 are fixed to the cylindrical part 22b of the base end arm 22, while the fixed part 136 rotates around the fourth rotation axis J4 relative to the rotating part 134, thereby causing the tip arm 24 to be rotationally driven around the fourth rotation axis J4 relative to the base end arm 22.

[0107] Even in this case, the rotating part 134 can be considered to rotate relatively to the fixed part 136. That is, in this document, the "rotating part" can be defined as something that rotates relatively to the "fixed part." As the fixed part 136 and the distal arm 24 rotate, the second type of filament 26B is twisted in section B (see FIG. 5).

[0108] According to this embodiment, it is possible to provide section B on the distal arm 24 side, and as a result, it is possible to set a longer section B. Furthermore, it is possible to arrange the rotation shaft structure 150 on the base end side of the distal arm 24, which also reduces the inertial force of the distal arm 24 during rotation.

[0109] In the above-described embodiments, the rotary shaft structures 50, 150, and 160 are disposed between the base arm 22 and the distal arm 24, and are described as being arranged to rotate the distal arm 24 about the fourth rotation axis J4 relative to the base arm 22. However, the rotary shaft structures 50, 150, or 160 may be provided on the rotation axis J1, J2, J3, J5, or J6 of any of the joints of the machine 10.

[0110] For example, the rotational axis structure 50, 150, or 160 may be disposed between the robot base 12 and the base end 16a of the upper arm 16 to rotate the upper arm 16 about the second rotational axis J2 relative to the robot base 12, or may be disposed between the tip end 16b of the upper arm 16 and the base end 22a of the forearm 18 to rotate the forearm 18 about the third rotational axis J3 relative to the upper arm 16.

[0111] Furthermore, the machine 10 or 30 is not limited to a vertical articulated robot, but may be any type of robot, such as a horizontal articulated robot or a parallel link robot, or any type of machine that has a movable component that is driven to rotate about a rotation axis J, such as a rotary positioner that rotatably supports a workpiece. While the present disclosure has been described above through the embodiments, the above-described embodiments do not limit the invention according to the claims. [Explanation of symbols]

[0112] 10, 30, 30' machine 26, 26A, 26B Striatum 32 Fixed structure 50, 150, 160 Rotating shaft structure 58, 152, 162 Restraining member 134 Rotating part 136 Fixed part 138 Through Hole 138a, 138b open end 140 Restraint tube 146 Cylindrical part 148 Flange 142, 144, 170, 172 Fixing members

Claims

1. A hollow fixed part having a stator of an electric motor; a hollow rotating part provided on the fixed part so as to be rotatable about a rotation axis relative to the fixed part, the rotating part having a first rotating element that penetrates the rotating part and the fixed part in the direction of the rotation axis and defines, together with the fixed part, a through hole through which a filament passes, the first rotating element being rotated at a first speed by power generated by the stator, and a second rotating element that is connected to the first rotating element via a reducer that reduces the first speed to a second speed and is rotated at the second speed; a restraining member that restrains the filament to the second rotating element so that the filament rotates at the second speed together with the second rotating element in a section from one opening end to the other opening end of the through hole.

2. a hollow fixing portion; a hollow rotating part provided on the fixed part so as to be rotatable about a rotation axis, the rotating part penetrating the rotating part and the fixed part in the direction of the rotation axis and defining, together with the fixed part, a through hole through which a filament passes; a restraining member that restrains the filament to the rotating part so that the filament rotates together with the rotating part in a section from one opening end to the other opening end of the through hole, the restraint member is disposed inside the through hole so as to surround the filament over the section, and includes a cylindrical restraint tube fixed to the rotating part so as to rotate together with the rotating part, A rotation axis structure in which the filament is restrained inside the restraint tube so as not to rotate relative to the restraint tube.

3. The restraint pipe is a cylindrical portion surrounding the filament in the section; The rotating shaft structure according to claim 2 , further comprising: a flange portion extending radially outward from the cylindrical portion and fixed to the rotating portion.

4. The restraining member is a first fixing member provided adjacent to the one open end and fixing the filament to the rotating part; a second fixing member provided adjacent to the other open end and fixing the filament to the rotating portion.

5. A rotating shaft structure according to any one of claims 1 to 4, The umbilical member.

6. a fixing structure that fixes the filament to the fixing portion outside the through hole, The machine of claim 5 , wherein as the rotating part is rotated, the filament is twisted in the second section between the through hole and the fixed structure.

7. The striatum a first type filament extending in the section; 7. The machine of claim 6, further comprising: a second type of filament extending in the second section and connected to the first type of filament, the second type of filament having a higher resistance to deformation than the first type of filament.

8. 8. The machine according to claim 7, wherein the restraining member has a circuit relay portion fixed to the rotating portion and electrically connecting the first type of wire body and the second type of wire body.

9. A rotating shaft structure, a hollow fixing portion; a hollow rotating part provided on the fixed part so as to be rotatable about a rotation axis relative to the fixed part, the rotating part penetrating the rotating part and the fixed part in the direction of the rotation axis and defining, together with the fixed part, a through hole through which a filament passes; a restraining member that restrains the filament to the rotating part so that the filament rotates together with the rotating part in a section from one opening end to the other opening end of the through hole; and The striatum; a fixing structure that fixes the filament to the fixing portion outside the through hole, As the rotating part is rotated, the filament is twisted in the second section between the through hole and the fixed structure.

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