Rotating shaft structure, machine, robot, and actuator

Abstract

Conventionally, there has been a demand for the joint structure of a robot to be made compact. In the present invention, a joint structure 50 of a robot comprises: a fixed part 136; a rotating part 134 which is provided to the fixed part 136 so as to be rotatable about an axis J4 and which has a first rotating element 56 and a second rotating element 90 provided between the first rotating element 56 and the fixed part 136; and a protective tube 58 which is disposed inside the fixed part 136 and the rotating part 134, which has a cylindrical section 112 and a flange section 114, and which has a filament body 26 wired so as to pass through the inside of the cylindrical section 112. The protective tube 58 is held such that the cylindrical section 112 extends in parallel to the axis J4 as a result of the flange section 114 being sandwiched and held between the first rotating element 56 and the second rotating element 90.

Description

[Technical field]

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

[0002] 2. Description of the Related Art A rotating shaft structure for a machine (specifically, a robot) is known (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2009-028875 A Summary of the Invention [Problem to be solved by the invention]

[0004] Conventionally, there has been a demand for higher density machine designs, which in turn has led to a demand for compact rotating shaft structures for the machines. [Means for solving the problem]

[0005] In one aspect of the present disclosure, the rotating shaft structure includes a hollow fixed portion, a hollow rotating portion provided on the fixed portion so as to be rotatable around an axis, the rotating portion having a first rotating element and a second rotating element arranged between the first rotating element and the fixed portion and fixed to the first rotating element, and a hollow protective tube arranged inside the fixed portion and the rotating portion, the protective tube having a cylindrical portion and a flange portion extending radially outward from the cylindrical portion, and a wire is wired to pass through the inside of the cylindrical portion, the flange portion of the protective tube being clamped between the first rotating element and the second rotating element, so that the cylindrical portion is held extending parallel to the axis, and the protective tube rotates relative to the fixed portion together with the first rotating element and the second rotating element. Effect of the Invention

[0006] According to the present disclosure, the protective tube can be stably held without using fasteners such as bolts, thereby making it possible to make the axial dimension of the rotating shaft structure more compact compared to when the flange portion is fixed using fasteners. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a perspective view of a machine according to one embodiment. [Diagram 2] FIG. 2 is a side cross-sectional view of a rotating shaft structure according to one embodiment. [Diagram 3] FIG. 3 is a view of the sensor shown in FIG. 2 as viewed from the axial direction. [Figure 4] FIG. 3 is an enlarged view of a flange portion shown in FIG. 2. [Diagram 5] 3 is a view of the rotating shaft structure shown in FIG. 2 as viewed from the axial rear side. [Figure 6] 3 is a view of the rotating shaft structure shown in FIG. 2 as viewed from the axial front side. [Figure 7] FIG. 11 is a side cross-sectional view of a rotating shaft structure according to another embodiment, and is an enlarged view of a main portion. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

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

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

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

[0011] The wrist 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 tip 24b of the tip arm 24 so as to be rotatable about a fifth axis J5 perpendicular to the fourth axis J4. The wrist flange 20b is provided at the wrist base 20a so as to be rotatable about a sixth axis J6 perpendicular to the fifth axis J5.

[0012] An end effector (not shown, such as a robot hand, a welding torch, a cutting tool, or a laser processing head) is removably attached to the wrist flange 20b. The machine 10 positions the end effector at an arbitrary position by rotating the swivel base 14, the upper arm arm 16, the forearm arm 18 (base arm 22, distal arm 24), and the wrist 20 (wrist base 20a, wrist flange 20b) about each of the axes J1 to J6, and the end effector performs a predetermined task on a workpiece (workpiece handling, welding, cutting, laser processing, etc.). In this paper, the "axis" can also be defined as the "axis of rotation."

[0013] The machine 10 further includes a umbilical member 26 and a rotating shaft structure 50. The umbilical member 26 includes, for example, a power line that supplies power to an electric motor (for example, 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 cord 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 cord 26 is wired so as to pass through the insides of the base portion 12, the rotating base 14, the upper arm arm 16, the forearm arm 18, and the wrist 20 and be connected to the end effector. The umbilical cord 26 and the rotating shaft structure 50 constitute an actuator of the machine 10.

[0015] The rotating shaft structure 50 is disposed between the base arm 22 and the tip arm 24, and drives the tip arm 24 to rotate about a fourth 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 axis J4 is defined as the axial direction, the radial direction of a circle centered on the fourth axis J4 is defined as the radial direction, and the circumferential direction of the circle is defined as the circumferential direction. For convenience, the direction indicated by the arrow B 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 (first rotating element), a protective tube 58, and clamp members 59 and 60. In the present embodiment, the electric motor 52, the reducer 54, and the sensor 56 are disposed approximately coaxially with respect to the fourth axis A4, and are disposed side by side in the axial direction.

[0017] The electric motor 52 has a housing 62, a stator 64, a rotor 66, an encoder 68, and an electromagnetic brake 70. The housing 62 is cylindrical and accommodates therein the stator 64, the rotor 66, the encoder 68, and the electromagnetic brake 70. The housing 62 is fixed to the cylindrical portion 22b of the base end arm 22 (FIG. 1).

[0018] The stator 64 has a cylindrical stator core 72 fixed to the housing 62, and a coil 74 wound around the stator core 72. The rotor 66 is rotatably disposed radially inside the stator 64. Specifically, the rotor 66 has a rotor shaft 76 (third rotating element) and a rotor core 78.

[0019] 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 bearings 80 and 82. support 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 frontward 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 a voltage applied to the coil 74, thereby generating power that rotates the rotor core 78 in the circumferential direction. In this way, the rotor 66 is rotated about the fourth axis A4 relative to the housing 62 and the stator 64.

[0022] The encoder 68 detects the rotation (for example, the rotation position or the rotation angle) of the rotor 66. Specifically, the encoder 68 has a rotation slit 68a, a light-emitting portion 68b, and a light-receiving portion 68c. The rotation 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 rotation 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 outputs light toward the rotation 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 rotation slit 68a and enters 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 electromagnetic brake 70 brakes the rotation of the rotor 66. Specifically, the electromagnetic brake 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 circumferential 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 provided on 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, whereby the armature 70c is attracted to the brake core 70d and moves away from the brake disc 70a. In this way, the electromagnetic brake 70 releases the braking force applied to the rotor 66, and the rotor 66 becomes rotatable.

[0027] On the other hand, when the voltage applied to the brake coil becomes zero, the excitation of the brake core 70d is released, and the armature 70c is pressed against the brake disc 70a by the action of the biasing member. In this way, the electromagnetic brake 70 brakes the rotation of the rotor 66. The encoder 68 and the electromagnetic brake 70 are disposed on the axial rear side of the support wall 62a, and a space S2 for accommodating the encoder 68 and the electromagnetic brake 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 (fourth rotating element), an external gear 88 (fourth rotating element), and an output shaft 90 (second rotating element).

[0029] The housing 84 is cylindrical and fixed to the housing 62 of the electric motor 52. 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 supported by a bearing 92. of Through the housing 84 The gear 86 is rotatably supported by the bearing 82 and is disposed radially outside the gear 86 so as to mesh with the gear 86 .

[0030] The output shaft 90 is annular and is provided on the axial front side of the housing 84 so as to be rotatable about the fourth 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. 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.

[0031] The outer flange 96 protrudes radially outward from an outer circumferential surface 94b of the main body portion 94 and extends circumferentially. Meanwhile, the inner flange 98 protrudes radially inward from an inner circumferential surface 94a of the main body portion 94 and extends circumferentially. The inner flange 98 is disposed axially forwardly away from the axial front end 76a of the rotor shaft 76.

[0032] 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.

[0033] The inner ring 102 has a through hole in its center. The outer ring 104 is disposed radially outwardly of 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.

[0034] The 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 output shaft 90 by a fastener such as a bolt (not shown), while the outer ring 104 is fixed to the base end portion 24a of the distal arm 24 by a fastener such as a bolt (not shown). In this state, the inner ring 102 abuts against the output shaft 90, while the outer ring 104 and the beam portion 106 are separated from the output shaft 90.

[0035] 2 again, the protective tube 58 is hollow, and is disposed inside the electric motor 52, the reducer 54, and the sensor 56. In the present embodiment, the protective tube 58 is made of resin, and has higher flexibility than the rotor 66 (specifically, the rotor shaft 76), the sensor 56, and the output shaft 90.

[0036] More specifically, the protective tube 58 has a tubular portion 112 and a flange portion 114. The tubular portion 112 is a cylindrical member extending straight in the axial direction, and the rotor shaft 76 described above is disposed at a distance from the tubular portion 112 on the radially outer side so as to surround the tubular portion 112 from the radially outer side. Therefore, the outer circumferential surface of the tubular portion 112 and the inner circumferential surface of the rotor shaft 76 are spaced apart from each other in the radial direction and do not come into contact with each other.

[0037] The flange portion 114 has an annular shape and extends radially outward from the axial front end of the cylindrical portion 112 and extends in the circumferential direction. More specifically, as shown in Fig. 4, the flange portion 114 has an axially front end face 114a, an axially rear end face 114b, and an annular recess 114c formed in the end face 114a.

[0038] The flange portion 114 is clamped between the inner flange 98 of the output shaft 90 and the inner ring 102 of the sensor 56, whereby the protective tube 58 is held so that the cylindrical portion 112 extends parallel to the fourth axis A4. In this way, the protective tube 58 is disposed approximately coaxially with the electric motor 52 (specifically, the housing 62, the stator 64, and the rotor 66), the reducer 54 (specifically, the housing 84, the internal gear 86, the external gear 88, and the output shaft 90), and the sensor 56, with the fourth axis A4 as the reference.

[0039] Here, in the present embodiment, the rotating shaft structure 50 further includes an elastic member 116 interposed between the flange portion 114 and the sensor 56. The elastic member 116 is, for example, an O-ring made of a rubber material, and is housed in a recess 114c of the flange portion 114 so as to protrude axially forward from an end face 114a of the flange portion 114.

[0040] More specifically, the elastic member 116 is interposed between the flange portion 114 and the inner ring 102 of the sensor 56 and comes into contact with the inner ring 102. When the sensor 56 is fixed to the output shaft 90, the elastic member 116 is compressed between the flange portion 114 and the inner ring 102, and an end face 114a of the flange portion 114 is separated axially rearward from an end face 102a on the axial rear side of the inner ring 102. That is, in this embodiment, the elastic member 116 comes into contact with the inner ring 102, while the flange portion 114 does not come into contact with the inner ring 102.

[0041] Due to the elastic restoring force generated by the elastic member 116 compressed between the flange portion 114 and the inner ring 102, the end face 114b of the flange portion 114 is pressed against the axially front end face 98a of the inner flange 98 of the output shaft 90 and comes into surface contact with the end face 98a, thereby holding the protective tube 58 so as to rotate integrally with the sensor 56 and the output shaft 90.

[0042] The end face 98a of the inner flange 98 may be formed by cutting in order to increase the flatness. With this configuration, the end face 98a of the inner flange 98 and the end face 114b of the flange portion 114 can be brought into close contact with each other, thereby increasing the frictional force between them. Therefore, when the sensor 56 and the output shaft 90 are rotated, the flange portion 114 of the protective tube 58 is prevented from shifting in the circumferential direction relative to the sensor 56 and the output shaft 90, and the protective tube 58 can be rotated integrally with the sensor 56 and the output shaft 90.

[0043] 2 again, the clamp member 59 is disposed on the axial rear side of the housing 62 of the electric motor 52. Specifically, as shown in Fig. 2 and Fig. 5, the clamp member 59 has a main body portion 118, a clamp arm 120, and a clamp portion 122. The main body portion 118 is a flat plate member having a substantially trapezoidal outer shape, and is fixed to the axial rear side of the end wall 62c of the housing 62 by a plurality of fasteners 124 (e.g., bolts).

[0044] The clamp arm 120 has a first arm 120a extending radially inward from a radially inner end of the main body portion 118, and a second arm 120b extending axially forward from the radially inner end of the first arm 120a. The second arm 120b extends perpendicular to the first arm 120a, with its axial front end entering the inside of the cylindrical portion 112. The clamp portion 122 is, for example, an annular member, and is fixed to the axial front end of the second arm 120b and disposed radially inside the cylindrical portion 112.

[0045] The clamp portion 122 clamps the filament 26 by inserting and fixing the filament 26 therein. The clamp portion 122 is not limited to an annular member, and may have a pair of openable and closable claws, and may clamp the filament 26 by sandwiching the filament 26 between the pair of claws. Alternatively, the clamp portion 122 may wrap the filament 26 in a protective elastic body, and fasten the outer periphery of the elastic body to the clamp arm 120b with a restraining device such as a nylon band to restrain the filament 26.

[0046] The first arm 120a is disposed axially rearward and spaced apart from the end wall 62c of the housing 62, the axial rear end of the rotor shaft 76, and the axial rear end of the cylindrical portion 112. The second arm 120b and the clamp portion 122 are disposed radially inward and spaced apart from the cylindrical portion 112.

[0047] Therefore, the clamp member 59 does not come into contact with the protective tube 58 and the rotor 66, and does not interfere with the rotation of the protective tube 58 and the rotor 66. On the other hand, the second arm 120b and the clamp portion 122 are disposed at a position spaced radially outward from the fourth axis J4 (in other words, offset from the fourth axis J4).

[0048] The clamp member 60 is disposed axially forward of the sensor 56. Specifically, as shown in Figs. 2 and 6, the clamp member 60 has a main body 126, a clamp arm 128, and a clamp portion 130. The main body 126 is a hollow flat member having a substantially rectangular outer shape, and is fixed to the output shaft 90 by a plurality of fasteners 132 (e.g., bolts) so as to be spaced axially forward of the sensor 56. In this embodiment, each fastener 132 passes through the gap 110 of the sensor 56, and its tip is fastened to a fastening hole 94c (Fig. 4) formed in the main body 94 of the output shaft 90.

[0049] The clamp arm 128 has a first arm 128a extending radially inward from the inner surface of a portion that forms an apex angle of the main body 126, and a second arm 128b extending axially rearward from the radially inner end of the first arm 128a. The second arm 128b extends perpendicular to the first arm 128a and has an axial rear end that enters the inside of the inner ring 102 of the sensor 56.

[0050] The clamp portion 130 is, for example, a circular member, which is fixed to the axial rear end of the second arm 128b and disposed radially inside the inner ring 102. The clamp portion 130 clamps the filament 26 by having the filament 26 inserted and fixed therein. The clamp portion 130 may have a pair of openable and closable claws, and may clamp the filament 26 by sandwiching the filament 26 between the pair of claws.

[0051] Alternatively, the clamp portion 130 may be configured to wrap the filament 26 in a protective elastic body and bind the outer periphery of the elastic body to the clamp arm 128b with a restraining device such as a nylon band to restrain the filament 26. In this embodiment, the axial rear end of the second arm 128b and the clamp portion 130 are disposed axially forward and spaced apart from the flange portion 114 of the protective tube 58.

[0052] Furthermore, the main body 126 and the first arm 128a are disposed axially forwardly away from the sensor 56, and the second arm 128b and the clamp 130 are disposed radially inwardly of the inner circumferential surfaces of the inner ring 102 and the cylindrical portion 112. Thus, in this embodiment, the clamp member 60 is separated from the sensor 56 and does not come into contact with the sensor 56. Furthermore, as described above, the fastener 132 also does not come into contact with the sensor 56 by passing through the gap 110 of the sensor 56.

[0053] In this way, the clamp member 60 and the fastener 132 that fixes the clamp member 60 to the output shaft 90 are completely spatially separated from the sensor 56, so that the force applied to the sensor 56 from the clamp member 60 and the fastener 132 can be made substantially zero. This improves the force detection accuracy of the sensor 56.

[0054] Furthermore, the clamp member 60 is not in contact with the protective tube 58 and the rotor 66, and therefore does not interfere with the rotation of the protective tube 58 and the rotor 66. Meanwhile, the second arm 128b and the clamp portion 130 are disposed at a position spaced radially outward from the fourth axis J4. Note that the radial distance (offset distance) between the clamp portion 122 and the fourth axis A4 and the radial distance between the clamp portion 130 and the fourth axis A4 may be the same.

[0055] The wire 26 is wired so as to pass through the cylindrical portion 112 of the protective tube 58 and the inside of the inner ring 102 of the sensor 56. Specifically, the wire 26 extends from an opening on the axial rear side of the cylindrical portion 112 into the inside of the cylindrical portion 112, and is clamped by a clamp portion 122 at the position of the axial rear end portion of the rotating shaft structure 50.

[0056] The filament 26 extends axially forward from the clamp portion 122 while bending, and is clamped by the clamp portion 130 at the position of the axial front end portion of the rotating shaft structure 50. The filament 26 extends axially forward from the clamp portion 130, passes through the inside of the inner ring 102 and the clamp member 60, and is pulled out to the axial front side of the rotating shaft structure 50. Here, in this embodiment, the clamp portions 122 and 130 clamp the filament 26 so that the filament 26 bends between them.

[0057] That is, the total length of the filament 26 extending between the clamping portions 122 and 130 is longer than the axial distance between the clamping portions 122 and 130. With this configuration, the filament 26 is not pulled between the clamping portions 122 and 130, and excessive tension can be prevented from being applied to the filament 26 when the rotating shaft structure 50 is in operation. Therefore, the life of the filament 26 can be extended.

[0058] Next, the operation of the rotating shaft structure 50 will be described. 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 the external gear 88 (fourth rotating element) of the reducer 54 are also rotated by the rotor shaft 76 (third rotating element). The internal gear 86 and the external gear 88 are interposed between the rotor shaft 76 and the output shaft 90 (second rotating element), and transmit the rotation of the rotor shaft 76 to the output shaft 90 via the output pin 95 after reducing the speed from V1 to a speed V2 (<<V1). In this way, the reducer 54 reduces the speed of the rotor 66. For example, the speed V2 is 1% or less of the speed V1.

[0059] The sensor 56 (first rotating element) rotates integrally with the output shaft 90 in the circumferential direction at a speed V2, and as a result, the distal arm 24 fixed to the outer ring 104 of the sensor 56 is also rotated in the circumferential direction at the speed V2. In this way, the distal arm 24 rotates relative to the base arm 22.

[0060] In this manner, the rotor 66 (rotor shaft 76, rotor core 78), 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, internal gear 86, external gear 88, output shaft 90, and sensor 56 constitute a rotating portion 134 of the rotating shaft structure 50.

[0061] On the other hand, the housing 62 and the stator 64 (stator core 72, coil 74) of the electric motor 52, and the housing 84 of the reducer 54 are fixed to the base end arm 22. Therefore, in the present embodiment, the housings 62 and 84 and the stator 64 configure a fixed portion 136 of the rotating shaft structure 50. Each of the rotating portion 134 and the fixed portion 136 is hollow, and the rotating portion 134 is provided on the fixed portion 136 so as to be rotatable in the circumferential direction.

[0062] When the output shaft 90 and the sensor 56 rotate, the protective tube 58 also rotates in the circumferential direction together with the output shaft 90 and the sensor 56 at a speed V2. Therefore, the rotor shaft 76 rotates relative to the protective tube 58 at a relative speed ΔV=V1-V2. Here, as described above, the flange portion 114 is sandwiched between the output shaft 90 (specifically, the inner flange 98) and the sensor 56 (specifically, the inner ring 102), so that the cylindrical portion 112 is held to extend parallel to the fourth axis A4, and as a result, the cylindrical portion 112 and the rotor shaft 76 are spaced apart from each other in the radial direction.

[0063] According to this configuration, the cylindrical portion 112 and the rotor shaft 76 can be reliably separated from each other, so that even if the rotor shaft 76 rotates relative to the protective tube 58 when the rotating shaft structure 50 is in operation, the protective tube 58 does not interfere with the rotation of the rotor shaft 76, and damage to the protective tube 58 due to contact between the protective tube 58 and the rotor shaft 76 can be prevented.

[0064] When the output shaft 90 rotates, the clamp member 60 fixed to the output shaft 90 also rotates in the circumferential direction at a speed V2 together with the output shaft 90. Therefore, the clamp portion 130 of the clamp member 60 is displaced in the circumferential direction relative to the clamp portion 122 of the clamp member 59. Accordingly, the filament 26 is twisted between the clamp portions 122 and 130.

[0065] However, as described above, since the total length of the filament 26 between the clamp portions 122 and 130 is set to be longer than the axial distance between the clamp portions 122 and 130, even if the filament 26 is twisted, excessive tension can be prevented from being applied to the filament 26.

[0066] As described above, in this embodiment, the rotating shaft structure 50 includes a hollow fixed portion 136 (housings 62 and 84, stator 64), a hollow rotating portion 134 (rotor 66, internal gear 86, external gear 88, output shaft 90, and sensor 56) provided on the fixed portion 136 so as to be rotatable around axis J4, and a hollow protective tube 58 arranged inside the fixed portion 136 and the rotating portion 134.

[0067] The rotating part 134 has a first rotating element (sensor 56) and a second rotating element (output shaft 90) that is arranged between the first rotating element 56 and the fixed part 136 and fixed to the first rotating element 56, and the protective tube 58 is held so that the tubular part 112 extends parallel to the axis A4 by clamping the flange part 114 between the first rotating element 56 and the second rotating element 90.

[0068] According to this configuration, the protective tube 58 can be stably held without using fasteners such as bolts, and the axial dimension of the rotating shaft structure 50 can be made more compact than in the case where the flange portion 114 is fixed using fasteners. Therefore, the rotating shaft structure 50 can be applied to a relatively small machine, and the weight and number of parts of the rotating shaft structure 50 can be reduced. In addition, since the cylindrical portion 112 can be stably held parallel to the axial direction, the wire 26 wired inside the cylindrical portion 112 can be stably protected even if the protective tube 58 rotates when the rotating shaft structure 50 is in operation.

[0069] In addition, in this embodiment, the rotating portion 134 further has a third rotating element (rotor shaft 76) arranged at a distance radially outside the cylindrical portion 112 so as to surround the cylindrical portion 112, and a fourth rotating element (internal gear 86 and external gear 88) interposed between the second rotating element 90 and the third rotating element 76 to reduce the rotation of the third rotating element 76 and transmit it to the second rotating element 90.

[0070] According to this configuration, the rotational torque of the second rotating element 90 can be increased by the fourth rotating elements 86 and 88. Furthermore, by holding the cylindrical portion 112 parallel to the axial direction, the cylindrical portion 112 and the third rotating element 76 can be reliably separated from each other. As a result, even if the third rotating element 76 rotates relative to the protective tube 58 during operation of the rotating shaft structure 50, interference between the protective tube 58 and the third rotating element 76 can be prevented as described above, and thus damage to the protective tube 58 can be prevented.

[0071] In this embodiment, the fixed part 136 has a stator 64 that generates power to rotate the rotating part 134, and the first rotating element 56, the second rotating element 90, and the stator 64 are arranged side by side in the axial direction. With this configuration, the radial dimension of the rotating shaft structure 50 can be made compact.

[0072] Moreover, in this embodiment, the rotating shaft structure 50 further includes an elastic member 116 interposed between the first rotating element 56 and the flange portion 114. According to this configuration, the protective tube 58 can be stably held by an elastic restoring force generated by the elastic member 116 compressed between the first rotating element 56 and the flange portion 114.

[0073] In this embodiment, the first rotating element 56 is a sensor 56 that detects a force acting on the first rotating element 56, and the elastic member 116 is interposed between the sensor 56 and the flange portion 114, and the flange portion 114 is spaced apart from the sensor 56. This configuration can prevent force from being applied to the sensor 56 from the flange portion 114, while the distortion caused in the sensor 56 by the force applied to the sensor 56 from the elastic member 116 is relatively small, thereby improving the force detection accuracy of the sensor 56.

[0074] In addition, in this embodiment, the sensor 56 has an inner ring 102, an outer ring 104 arranged radially outside the inner ring 102, a beam portion 106 extending radially between the inner ring 102 and the outer ring 104, and a strain gauge 108 provided on the beam portion 106, and an elastic member 116 is interposed between the inner ring 102 and the flange portion 114.

[0075] According to this configuration, the strain that the elastic member 116 causes in the inner ring 102 is relatively small as described above, and in addition, since the elastic member 116 does not contact the beam portion 106, it is possible to reliably prevent the force applied from the elastic member 116 from affecting the strain gauge 108 provided on the beam portion 106. Therefore, the force detection accuracy of the sensor 56 can be more effectively improved.

[0076] In the present embodiment, the protective tube 58 is made of resin. This configuration reduces the risk of the filament 26 coming into contact with the protective tube 58 and damaging the filament 26, so that the filament 26 can be stably protected. In the present embodiment, the rotating part 134 and the protective tube 58 are coaxially arranged with the axis J4 as a reference. This configuration prevents the protective tube 58 from being displaced in the radial direction when the protective tube 58 rotates together with the first rotating element 56 and the second rotating element 90. Therefore, the filament 26 can be stably protected when the protective tube 58 rotates.

[0077] Next, a rotating shaft structure 50' according to another embodiment will be described with reference to Fig. 7. The rotating shaft structure 50' differs from the above-described rotating shaft structure 50 in a protective tube 58'. The protective tube 58' has a cylindrical portion 112' and a flange portion 114. In this embodiment, the cylindrical portion 112' has an axial front end portion 112a disposed inside the inner ring 102 of the sensor 56.

[0078] The axial front end portion 112a may be spaced radially inward from the inner peripheral surface of the inner ring 102. In this case, contact between the protective tube 58' and the sensor 56 can be avoided, and force can be prevented from being applied to the sensor 56 from the protective tube 58'. The axial front end face 112b of the cylindrical portion 112' may be disposed at approximately the same axial position as the axial front end face of the sensor 56. The clamp portion 130 is disposed inside the inner ring 102 at an axial position between the flange portion 114 and the end face 112b of the cylindrical portion 112'.

[0079] In the rotating shaft structure 50 or 50', the clamp portion 130 may be disposed inside the inner ring 102 at approximately the same axial position as the axial front end face of the sensor 56. In the rotating shaft structure 50 or 50', the clamp portion 122 (FIG. 2) may be disposed inside the cylindrical portion 112 or 112' at approximately the same axial position as the axial rear end face of the cylindrical portion 112 or 112'.

[0080] According to this configuration, in the rotating shaft structure 50 or 50', it is possible to maximize the distance between the clamping portions 122 and 130 disposed inside the rotating portion 134 and the fixed portion 136. Therefore, even if the clamping portion 130 is displaced in the circumferential direction relative to the clamping portion 122 during operation of the rotating shaft structure 50 or 50', it is possible to alleviate the twisting of the filament 26, thereby reducing the tension applied to the filament 26.

[0081] The protective tube 58 or 58' may be made of a combination of resin and metal (e.g., iron). For example, the flange portion 114 may be made of metal, while the cylindrical portion 112 or 112' may be made of resin. In this case, the end face 114b on the axial rear side of the flange portion 114 may be formed by cutting to increase flatness. With this configuration, the end face 114b and the end face 98a of the inner flange 98 can be brought into close contact with each other, thereby increasing the frictional force between them. The protective tube 58 or 58' may be made of only metal.

[0082] In the above embodiment, the first rotating element is the sensor 56 that detects a force. However, the present invention is not limited to this, and the first rotating element may include the sensor 56 and a member fixed to the sensor 56. Alternatively, the first rotating element may be a simple metal member, or may be a part of the base end portion 24a of the distal arm 24. Similarly, the second rotating element 90 is not limited to the output shaft 90 of the reducer 54, and may be, for example, a sensor that detects a force, or any other member.

[0083] Also, the reducer 54 may be omitted from the above-described rotating shaft structure 50 or 50'. In this case, a ring-shaped second rotating element may be fixed to the axial front end of the rotor shaft 76, and the flange portion 114 of the protective tube 58 may be sandwiched between the second rotating element and the first rotating element (e.g., the sensor 56).

[0084] In the above embodiment, the electric motor 52, the reducer 54, and the sensor 56 are disposed approximately coaxially with respect to the fourth axis A4 and are arranged side by side in the axial direction. However, the present invention is not limited to this, and for example, the electric motor 52 may be disposed at a position offset from the axis A4.

[0085] In this case, the electric motor 52 may have a stator 64 disposed at a position offset from the axis A4, an output shaft that is rotationally driven by the stator 64, a rotor shaft 76 disposed coaxially with the axis A4, and a rotation transmission mechanism (e.g., 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.

[0086] Furthermore, the elastic member 116 may be omitted from the above-described rotating shaft structure 50 or 50'. In this case, the flange portion 114 of the protective tube 58 may be sandwiched between the sensor 56 and the output shaft 90 so as to come into contact with the sensor 56. Furthermore, the sensor 56 is not limited to a form having the inner ring 102, the outer ring 104, and the beam portion 106, and may be a form in which the strain gauge 108 is provided on a circular member such as the inner ring 102, for example.

[0087] In the above embodiment, the protective tubes 58 and 58' are disposed coaxially with the rotating portion 134 with respect to the axis J4. However, this is not limiting, and the protective tube 58 or 58' may be disposed at a position where its central axis is offset in the radial direction from the fourth axis A4. In this case, the cylindrical portion 112 or 112' is held so as to extend parallel to the fourth axis A4, while the central axis of the cylindrical portion 112 or 112' is disposed at a position shifted in the radial direction by a predetermined distance from the fourth axis A4.

[0088] Further, in the above-described embodiment, a 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 (the 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.

[0089] In this case, 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 with respect to the rotating part 134 and the cylindrical part 22b. Even in this case, the rotating part 134 can be considered to rotate relatively to the fixed part 136. In other words, in this document, the "rotating part" can be defined as something that rotates relatively to the "fixed part".

[0090] In the above-described embodiment, the rotating shaft structures 50 and 50' are disposed between the base arm 22 and the distal arm 24, and the distal arm 24 is rotated about the fourth axis J4 relative to the base arm 22. However, the rotating shaft structure 50 or 50' may be provided on the axis J1, J2, J3, J5, or J6 of any of the joints of the machine 10.

[0091] For example, the rotating shaft structure 50 or 50' may be disposed between the pivot base 14 and the base end 16a of the upper arm arm 16 to rotate the upper arm arm 16 about the second axis J2 relative to the pivot base 14, or may be disposed between the tip end 16b of the upper arm arm 16 and the base end 22a of the forearm arm 18 to rotate the forearm arm 18 about the third axis J3 relative to the upper arm arm 16.

[0092] 1, the machine 10 may be any type of robot, such as a horizontal articulated robot or a parallel link robot, or any type of machine equipped with a movable component that is driven to rotate around an axis A, such as a rotary positioner that rotatably supports a workpiece. Although the present disclosure has been described above through the embodiments, the above-mentioned embodiments do not limit the invention according to the claims. [Explanation of symbols]

[0093] 10 machines 26 Striatum 50,50' Rotating shaft structure 52 Electric motor 54 Reducer 56 Sensor (first rotating element) 58 Protection tube 64 Stator 76 rotor shaft (third rotating element) 86 Internal gear (fourth rotating element) 88 External gear (fourth rotating element) 90 Output shaft (second rotating element) 102 Inner Circle 104 Outer Ring 106 Beam section 108 Strain Gauge 112,112' Cylindrical section 114 Flange part 116 Elastic Members 134 Rotating Part 136 Fixed part

Claims

1. A hollow fixing portion; a hollow rotating part provided on the fixed part so as to be rotatable about an axis, the rotating part having a first rotating element and a second rotating element disposed between the first rotating element and the fixed part and fixed to the first rotating element; a hollow protective tube disposed inside the fixed portion and the rotating portion, the protective tube having a cylindrical portion and a flange portion extending radially outward from the cylindrical portion and spaced apart from the first rotating element, and a wire is wired so as to pass through the inside of the cylindrical portion; an elastic member that is interposed between the first rotating element and the flange portion and compressed to generate an elastic restoring force; The protective tube is held such that the cylindrical portion extends parallel to the axis by the flange portion being sandwiched between the first rotating element and the second rotating element, A rotating shaft structure in which the elastic member presses the flange portion against the second rotating element by the elastic restoring force, thereby rotating the protective tube together with the first rotating element and the second rotating element relative to the fixed portion.

2. The rotating part is a third rotating element disposed radially outwardly of the cylindrical portion so as to surround the cylindrical portion; and 2. The rotating shaft structure according to claim 1, further comprising a fourth rotating element interposed between the second rotating element and the third rotating element, which reduces the rotation of the third rotating element and transmits it to the second rotating element.

3. the fixed portion has a stator that generates power for rotating the rotating portion, The rotating shaft structure according to claim 1 or 2, wherein the first rotating element, the second rotating element, and the stator are arranged side by side in the axial direction.

4. A hollow fixing portion; a hollow rotating part provided on the fixed part so as to be rotatable about an axis, the rotating part having a first rotating element and a second rotating element disposed between the first rotating element and the fixed part and fixed to the first rotating element; a hollow protective tube disposed inside the fixed portion and the rotating portion, the protective tube having a cylindrical portion and a flange portion extending radially outward from the cylindrical portion, and a wire is wired to pass through the inside of the cylindrical portion; the flange portion of the protective tube is sandwiched between the first rotating element and the second rotating element, so that the cylindrical portion is held to extend parallel to the axis, and the protective tube rotates together with the first rotating element and the second rotating element relative to the fixed portion; A rotating shaft structure, wherein the first rotating element has a sensor that detects a force acting on the first rotating element, and the flange portion is spaced from the sensor.

5. The rotating shaft structure according to claim 4 , further comprising an elastic member interposed between the sensor and the flange portion.

6. The sensor includes: With the inner circle, an outer ring disposed radially outward of the inner ring; a beam portion extending in a radial direction between the inner ring and the outer ring; A strain gauge provided on the beam portion, The rotating shaft structure according to claim 5 , wherein the elastic member is interposed between the inner ring and the flange portion.

7. The rotating shaft structure according to any one of claims 1 to 6, wherein the protective tube is made of resin.

8. The rotating shaft structure according to any one of claims 1 to 7, wherein the rotating portion and the protective tube are arranged coaxially with respect to the axis.

9. A rotating shaft structure, A hollow fixing portion; a hollow rotating part provided on the fixed part so as to be rotatable about an axis, the rotating part having a first rotating element and a second rotating element disposed between the first rotating element and the fixed part and fixed to the first rotating element; a hollow protective tube disposed inside the fixed portion and the rotating portion, the protective tube having a cylindrical portion and a flange portion extending radially outward from the cylindrical portion and spaced apart from the first rotating element, and a wire is wired so as to pass through the inside of the cylindrical portion; an elastic member interposed between the first rotating element and the flange portion; a first clamp member provided on the fixed portion and configured to clamp the filament at one end of the rotating shaft structure in the axial direction; a second clamp member provided on the rotating part and clamping the filament at the other end of the rotating shaft structure in the axial direction, the second clamp member being displaced around the axial line relative to the first clamp member as the rotating part rotates relative to the fixed part; A rotating shaft structure in which the protective tube is held so that the tubular portion extends parallel to the axis by clamping the flange portion between the first rotating element and the second rotating element, and rotates relative to the fixed portion together with the first rotating element and the second rotating element.

10. A rotating shaft structure according to any one of claims 1 to 9, A machine comprising the filament.

11. A rotating shaft structure according to any one of claims 1 to 9, The robot comprises the filament.

12. A rotating shaft structure according to any one of claims 1 to 9, An actuator comprising the filament.

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