WO2023026435A1

WO2023026435A1 - Rotating shaft structure, and machine

Info

Publication number: WO2023026435A1
Application number: PCT/JP2021/031384
Authority: WO
Inventors: 一隆中山
Original assignee: ファナック株式会社
Priority date: 2021-08-26
Filing date: 2021-08-26
Publication date: 2023-03-02
Also published as: JPWO2023026435A1; TW202310992A

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

Rotating shaft structure and machine

The present disclosure relates to rotating shaft structures and machines.

A rotating shaft structure of a machine (specifically, a robot) is known (for example, Patent Document 1).

JP 2009-028875 A

　Conventionally, there has been a demand for high-density machine design, and for that reason, there has been a demand for a compact rotating shaft structure for the machine.

In one aspect of the present disclosure, the rotary shaft structure includes a hollow fixed part, a hollow rotary part provided in the fixed part so as to be rotatable about an axis, the first rotary element, and the a rotating part having a second rotating element interposed between the first rotating element and the stationary part and fixed to the first rotating element; A protective tube having a cylindrical portion and a flange portion extending radially outward from the cylindrical portion, and a filamentary body being wired so as to pass through the interior of the cylindrical portion. a tube, the protective tube being held such that the tubular portion extends parallel to the axis by sandwiching the flange portion between the first rotating element and the second rotating element; It rotates with respect to the stationary part together with the first rotating element and the second rotating element.

According to the present disclosure, the protective tube can be stably held without using fasteners such as bolts, so compared to the case where the flange portion is fixed using fasteners, the axial direction of the rotating shaft structure Dimensions can be compact.

1 is a perspective view of a machine according to one embodiment; FIG. 1 is a side cross-sectional view of a rotating shaft structure according to one embodiment; FIG. FIG. 3 is a view of the sensor shown in FIG. 2 as seen from the axial direction; 3 is an enlarged view of a flange portion shown in FIG. 2; FIG. It is the figure which looked at the rotating shaft structure shown in FIG. 2 from the axial direction rear side. It is the figure which looked at the rotating shaft structure shown in FIG. 2 from the axial direction front side. It is a side sectional view of the rotating shaft structure which concerns on other embodiment, Comprising: It is the enlarged view which expanded the principal part.

Hereinafter, embodiments of the present disclosure will be described in detail based on the drawings. In addition, in various embodiments described below, the same reference numerals are given to the same elements, and redundant descriptions are omitted. First, referring to FIG. 1, a machine 10 according to one embodiment will be described. Machine 10 is a vertical articulated robot comprising base 12 , pivoting base 14 , upper arm 16 , forearm arm 18 and wrist 20 . In this embodiment, each of pivot base 14, upper arm 16, forearm arm 18, and wrist 20 are hollow.

The base part 12 is fixed on the floor of the work cell or on an automatic guided vehicle (AGV). The swivel base 14 is provided on the base portion 12 so as to be rotatable around the first axis J1. The first axis J1 may be arranged parallel to the vertical direction. The upper arm 16 is provided on the swivel base 14 so that its proximal end 16a can rotate about a second axis J2 perpendicular to the first axis J1.

In this embodiment, the forearm arm 18 has a proximal arm 22 and a distal arm 24 . The base end arm 22 includes a base portion 22a provided at the distal end portion 16b of the upper arm portion 16 so as to be rotatable around a third axis line J3 parallel to the second axis line J2, and from the base portion 22a, and a cylindrical portion 22b extending in the direction of a fourth axis J4 orthogonal to the third axis J3. On the other hand, the distal end arm 24 is provided on the cylindrical portion 22b so that the base end portion 24a thereof can rotate around the fourth axis J4.

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 distal end portion 24b of the distal arm 24 so as to be rotatable around a fifth axis J5 perpendicular to the fourth axis J4. there is The wrist flange 20b is provided on the wrist base 20a so as to be rotatable around a sixth axis J6 orthogonal to the fifth axis J5.

An end effector (robot hand, welding torch, cutting tool, laser processing head, etc.) (not shown) is detachably attached to the wrist flange 20b. Machine 10 pivots base 14, upper arm 16, forearm arm 18 (proximal arm 22, distal arm 24), and wrist 20 (wrist base 20a, wrist flange 20b) about respective axes J1-J6. By rotating the end effector, the end effector is positioned at an arbitrary position, and a predetermined work (workpiece handling, welding, cutting, laser processing, etc.) is performed on the work by the end effector. In this paper, the "axis" can also be defined as the "rotational axis".

The machine 10 further comprises a filament 26 and a rotating shaft structure 50 . The filamentary body 26 is, for example, a power line for supplying electric power to an electric motor (eg, a servo motor) built in the machine 10, a control signal line for transmitting a signal for controlling the end effector, an air tube, or the like. include.

One end of the filament 26 is connected to a controller (not shown) of the machine 10, and the other end is connected to an end effector. Striatum 26 is routed to pass through base 12, pivot base 14, upper arm 16, forearm arm 18, and wrist 20 to connect to the end effector. The filamentary body 26 and the rotating shaft structure 50 constitute the actuator of the machine 10 .

A pivot structure 50 is disposed between the proximal arm 22 and the distal arm 24 to rotationally drive the distal arm 24 relative to the proximal arm 22 about a fourth axis J4. 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. Also, for convenience, the direction indicated by arrow B in FIG. 2 is referred to as the axial forward direction.

The rotating shaft structure 50 includes an electric motor 52, a speed reducer 54, a sensor 56 (first rotating element), a protective tube 58, and

clamp members

59 and 60. In this embodiment, the electric motor 52, the speed reducer 54, and the sensor 56 are arranged substantially coaxially with the fourth axis A4 as a reference, and arranged side by side in the axial direction.

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 has a tubular shape and houses the stator 64 , the rotor 66 , the encoder 68 and the electromagnetic brake 70 inside. Housing 62 is secured to cylindrical portion 22b of proximal 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 . The rotor 66 is rotatably arranged radially inside the stator 64 . Specifically, the rotor 66 has a rotor shaft 76 (third rotating element) and a rotor core 78 .

The rotor shaft 76 is cylindrical and extends straight in the axial direction. Rotor shaft 76 is rotatably supported in housing 62 by

bearings

80 and 82 . The bearing 80 is interposed between the support wall 62 a of the housing 62 and the rotor shaft 76 , and the bearing 82 is interposed between the support wall 62 b of the housing 62 and the rotor shaft 76 . An annular oil seal 83 is interposed between the support wall 62 b and the rotor shaft 76 .

The support wall 62a is arranged on the rear side of the stator 64 and the rotor core 78 in the axial direction, while the support wall 62b is arranged on the front side of the stator 64 and the rotor core 78 in the axial direction. A space S1 that accommodates the stator 64 and the rotor core 78 is defined inside the housing 62 by the

support walls

62a and 62b.

The rotor core 78 is a cylindrical member containing a plurality of magnets (not shown) arranged in the circumferential direction, and is fixed to the outer peripheral surface of the rotor shaft 76 so as to rotate integrally with the rotor shaft 76 . ing. The stator 64 generates a rotating magnetic field in the circumferential direction by the voltage applied to the coil 74, thereby generating power to rotationally drive the rotor core 78 in the circumferential direction. Rotor 66 is thus rotated relative to housing 62 and stator 64 about fourth axis A4.

The encoder 68 detects rotation of the rotor 66 (for example, rotational position or rotational angle). Specifically, the encoder 68 has a rotary slit 68a, a light emitter 68b, and a light receiver 68c. The rotary slit 68a has a plurality of slits and is fixed to the outer peripheral surface of the rotor shaft 76 so as to rotate together with the rotor shaft 76. As shown in FIG. The rotating slit 68a is arranged between the light emitting portion 68b and the light receiving portion 68c.

The light emitting part 68b is fixed to the housing 62 and outputs light toward the rotating slit 68a. The light receiving portion 68c is fixed to the housing 62 and receives light output from the light emitting portion 68b. More specifically, the light output from the light emitting section 68b is patterned by passing through a slit formed in the rotating slit 68a, and enters the light receiving section 68c. The encoder 68 detects the rotation of the rotor 66 based on the patterned light received by the light receiving section 68c.

The electromagnetic brake 70 brakes the rotation of the rotor 66. Specifically, the electromagnetic brake 70 has a brake disk 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 together with the rotor shaft 76. As shown in FIG.

The end plate 70b is fixed to the brake core 70d. The armature 70c is arranged to face 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 arranged 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.

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 magnetized, whereby the armature 70c is attracted to the brake core 70d and separated from the brake disc 70a. Thus, the electromagnetic brake 70 releases braking on the rotor 66 and the rotor 66 is allowed to rotate.

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. The electromagnetic brake 70 thus brakes the rotation of the rotor 66 . The encoder 68 and the electromagnetic brake 70 are arranged on the axial rear side of the support wall 62 a , and the encoder 68 and the electromagnetic brake 70 are arranged inside the housing 62 by the support wall 62 a and the axial rear end wall 62 c of the housing 62 . A space S2 that accommodates the brake 70 is defined.

The reduction gear 54 is provided on the front side in the axial direction of the electric motor 52 and reduces the rotation of the rotor 66 . Specifically, the speed reducer 54 is, for example, a planetary gear speed reducer, a strain wave gear speed reducer, or a cycloidal speed reducer, and includes a housing 84, an internal gear 86 (fourth rotating element), an external gear 88 (fourth 4 rotating elements), and an output shaft 90 (second rotating element).

The housing 84 is cylindrical and fixed to the housing 62 of the electric motor 52 . The internal gear 86 is arranged to surround the axial front end of the rotor shaft 76 and meshes with a gear portion formed on the axial front end. The external gear 88 is rotatably supported by the housing 62 via a bearing 92 , is arranged radially outside the internal gear 86 and meshes with the internal gear 86 .

The output shaft 90 has an annular shape and is provided on the front side in the axial direction of the housing 84 so as to be rotatable around the fourth axis J4. More specifically, output shaft 90 has a body portion 94 , an outer flange 96 and an inner flange 98 . The body portion 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 body portion 94 through the output pin 95 . An annular oil seal 100 is interposed between the inner peripheral surface 94 a of the body portion 94 and the rotor shaft 76 . The oil seals 83 and 100 prevent the lubricant filled inside the rotary shaft structure 50 from leaking.

The outer flange 96 protrudes radially outward from the outer peripheral surface 94b of the body portion 94 and extends in the circumferential direction. On the other hand, the inner flange 98 protrudes radially inward from the inner peripheral surface 94a of the body portion 94 and extends in the circumferential direction. The inner flange 98 is spaced axially forward from the axial front end 76 a of the rotor shaft 76 .

The sensor 56 is arranged adjacent to the front side in the axial direction of the output shaft 90 and detects a force (for example, torque) acting on the sensor 56 . The sensor 56 will be described below with reference to FIG. 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 .

The inner ring 102 has a through hole at its center. The outer ring 104 is spaced radially outward of the inner ring 102 . The beam portions 106 extend in the radial direction between the inner ring 102 and the outer ring 104 and are arranged side by side at substantially equal intervals in the circumferential direction. A gap 110 is defined between two beams 106 that are circumferentially adjacent to each other.

A strain gauge 108 is provided on each beam portion 106 and converts the 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 with fasteners such as bolts (not shown), while the outer ring 104 is attached to the base end portion 24a of the tip arm 24 with fasteners such as bolts (not shown). not shown). In this state, the inner ring 102 abuts the output shaft 90 while the outer ring 104 and the beam 106 are separated from the output shaft 90 .

　Referring to FIG. 2 again, the protection tube 58 is hollow and is arranged inside the electric motor 52, the reduction gear 54, and the sensor 56. In this 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.

More specifically, the protective tube 58 has a cylindrical portion 112 and a flange portion 114. The tubular portion 112 is a cylindrical member that extends straight in the axial direction, and the rotor shaft 76 is mounted on the tubular portion 112 so as to surround the tubular portion 112 from the outside in the radial direction. They are spaced apart radially outward. Therefore, the outer peripheral surface of the cylindrical portion 112 and the inner peripheral surface of the rotor shaft 76 are separated from each other in the radial direction so as not to come into contact with each other.

The flange portion 114 has an annular shape, extends radially outward from the axial front end of the tubular portion 112, and extends in the circumferential direction. More specifically, as shown in FIG. 4, the flange portion 114 has an axially front end surface 114a, an axially rearward end surface 114b, and an annular recess 114c formed in the end surface 114a.

The flange portion 114 is sandwiched between the inner flange 98 of the output shaft 90 and the inner ring 102 of the sensor 56, whereby the protective tube 58 has the cylindrical portion 112 extending parallel to the fourth axis A4. retained as Thus, the protective tube 58 includes the electric motor 52 (specifically the housing 62, the stator 64 and the rotor 66), the speed reducer 54 (specifically the housing 84, the internal gear 86, the external gear 88 and the output shaft 90). ), and the sensor 56 with respect to the fourth axis A4.

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 an O-ring made of, for example, a rubber material, and is accommodated in a recess 114c of the flange portion 114 so as to protrude axially forward from the end face 114a of the flange portion 114. As shown in FIG.

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 the end surface 114a of the flange portion 114 is aligned with the axial rear end surface 102a of the inner ring 102. spaced axially rearward from the That is, in this embodiment, the elastic member 116 contacts the inner ring 102 while the flange portion 114 does not contact the inner ring 102 .

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 surface 114b of the flange portion 114 is pressed against the axially front end surface 98a of the inner flange 98 of the output shaft 90, thereby pressing the end surface 114b. The protective tube 58 is held in surface contact with the end surface 98a so as to rotate integrally with the sensor 56 and the output shaft 90 .

Note that the end surface 98a of the inner flange 98 may be formed by cutting in order to improve flatness. According to this configuration, the end face 98a of the inner flange 98 and the end face 114b of the flange portion 114 are brought into close contact with each other, and the frictional force therebetween can be increased. Therefore, when the sensor 56 and the output shaft 90 are rotated, the flange portion 114 of the protective tube 58 is prevented from being displaced in the circumferential direction with respect to the sensor 56 and the output shaft 90, thereby providing protection. Tube 58 can be rotated integrally with sensor 56 and output shaft 90 .

Again referring to FIG. 2, the clamp member 59 is arranged on the rear side of the housing 62 of the electric motor 52 in the axial direction. Specifically, as shown in FIGS. 2 and 5, the clamp member 59 has a body portion 118, a clamp arm 120, and a clamp portion 122. As shown in FIG. The 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 (for example, bolts).

The clamp arm 120 includes a first arm 120a extending radially inward from the radially inner end of the body portion 118 and a second arm extending axially forward from the radially inner end of the first arm 120a. 120b. The second arm 120b is orthogonal to the first arm 120a and extends so that its front end in the axial direction enters the interior of the cylindrical portion 112 . The clamp portion 122 is, for example, an annular member, fixed to the axial front end portion of the second arm 120b, and arranged radially inside the tubular portion 112 .

The clamp part 122 clamps the filamentous body 26 by inserting and fixing the filamentous body 26 therein. The clamping part 122 is not limited to an annular member, and has a pair of claws that can be opened and closed. There may be. Alternatively, the clamp part 122 may wrap the filamentous body 26 with a protective elastic body, and bind the outer periphery of the elastic body to the clamp arm 120b with a restraining tool such as a nylon band. .

The first arm 120a is spaced axially rearward 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 tubular portion 112. In addition, the second arm 120b and the clamping portion 122 are spaced radially inward from the cylindrical portion 112. As shown in FIG.

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

The clamp member 60 is arranged on the front side of the sensor 56 in the axial direction. Specifically, as shown in FIGS. 2 and 6, the clamp member 60 has a body portion 126, a clamp arm 128, and a clamp portion . The main body portion 126 is a hollow flat plate member having a substantially rectangular outer shape, and is fixed to the output shaft 90 by a plurality of fasteners 132 (for example, bolts) so as to be separated axially forward of the sensor 56 . there is In this embodiment, each fastener 132 passes through the gap 110 of the sensor 56 and its tip is fastened to a fastening hole 94 c ( FIG. 4 ) formed in the main body 94 of the output shaft 90 .

The clamp arm 128 includes a first arm 128a extending radially inward from the inner surface of the portion forming one apex angle of the body portion 126, and extending axially rearward from the radially inner end of the first arm 128a. and a second arm 128b. The second arm 128b is orthogonal to the first arm 128a and extends such that its axial rear end portion enters the inner ring 102 of the sensor 56 .

The clamp portion 130 is, for example, an annular member, fixed to the axial rear end portion of the second arm 128b, and arranged radially inward of the inner ring 102 . The clamp portion 130 clamps the filamentary body 26 by inserting and fixing the filamentous body 26 therein. The clamp section 130 may have a pair of claws that can be opened and closed, and may clamp the linear body 26 by sandwiching the linear body 26 with the pair of claws.

Alternatively, the clamping part 130 may wrap the filamentous body 26 with a protective elastic body, and bind the outer circumference of the elastic body to the clamp arm 128b with a restraining tool such as a nylon band. . In this embodiment, the axial rear end of the second arm 128b and the clamp portion 130 are spaced apart axially forward of the flange portion 114 of the protective tube 58 .

Further, the main body portion 126 and the first arm 128a are spaced apart from the sensor 56 in the axial direction, and the second arm 128b and the clamp portion 130 are positioned closer to each other than the inner ring 102 and the inner peripheral surfaces of the cylindrical portion 112. It is located radially inward. Thus, in this embodiment, clamp member 60 is spaced from sensor 56 and does not contact sensor 56 . Additionally, as noted above, fastener 132 also does not contact sensor 56 by passing through gap 110 of sensor 56 .

Thus, the clamping member 60 and the fasteners 132 that secure the clamping member 60 to the output shaft 90 are completely spatially separated from the sensor 56 thereby allowing the clamping member 60 and the fasteners 132 to separate the sensor 56 from the clamping member 60 and the fasteners 132 . The force applied to the can be made practically zero. Thereby, the force detection accuracy of the sensor 56 can be improved.

Also, since the clamp member 60 is not in contact with the protective tube 58 and the rotor 66, it does not interfere with the rotation of the protective tube 58 and the rotor 66. On the other hand, the second arm 128b and the clamping portion 130 are arranged at a position spaced radially outward from the fourth axis J4. The radial distance (offset distance) between the clamping portion 122 and the fourth axis A4 may be the same as the radial distance between the clamping portion 130 and the fourth axis A4.

The filamentary body 26 is wired so as to pass through the cylindrical portion 112 of the protective tube 58 and the inner ring 102 of the sensor 56 . Specifically, the filamentous body 26 extends into the tubular portion 112 from an opening on the rear side in the axial direction of the tubular portion 112 , and clamps the clamp portion 122 at the position of the rear end portion in the axial direction of the rotating shaft structure 50 . is clamped by

The filamentary body 26 extends from the clamp portion 122 while bending forward in the axial direction, and is clamped by the clamp portion 130 at the axial front end portion of the rotating shaft structure 50 . The filamentous body 26 extends axially forward from the clamp portion 130 , passes through the inner ring 102 and the clamp member 60 , and is pulled out axially forward of the rotary shaft structure 50 . Here, in the present embodiment, the clamping

portions

122 and 130 clamp the filamentous body 26 so that the filamentous body 26 bends between them.

That is, the total length of the filamentous body 26 extending between the clamping

portions

122 and 130 is longer than the axial distance between the clamping

portions

122 and 130. According to this configuration, the filamentous body 26 is not pulled between the

clamp portions

122 and 130, and excessive tension can be prevented from being applied to the filamentous body 26 during operation of the rotary shaft structure 50. Therefore, it is possible to extend the life of the filamentous body 26 .

Next, the operation of the rotating shaft structure 50 will be described. When stator 64 of electric motor 52 rotates rotor 66 circumferentially at speed V1, rotor shaft 76 (third rotating element) also rotates internal gear 86 and external gear 88 (fourth rotating element) of reduction gear 54. rotated respectively. 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 rotate the rotor shaft 76 from speed V1 to speed V2 (<<V1). and then transmitted to the output shaft 90 via the output pin 95 . Thus, the speed reducer 54 slows down the rotation of the rotor 66 . For example, the speed V2 is 1% or less of the speed V1.

Sensor 56 (first rotating element) rotates circumferentially together with output shaft 90 at speed V2. is rotated to Thus, distal arm 24 will rotate relative to proximal arm 22 .

Thus, the power generated by the stator 64 rotates the rotor 66 (rotor shaft 76, rotor core 78), internal gear 86, external gear 88, output shaft 90, and sensor 56, respectively. Thus, in this embodiment, rotor 66 , internal gear 86 , external gear 88 , output shaft 90 , and sensor 56 constitute rotating portion 134 of rotating shaft structure 50 .

On the other hand, the housing 62 and stator 64 (stator core 72, coil 74) of the electric motor 52 and the housing 84 of the speed reducer 54 are fixed to the base end arm 22. Therefore, in this embodiment, the

housings

62 and 84 and the stator 64 constitute the 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.

When the output shaft 90 and the sensor 56 are rotated, the protection tube 58 also rotates in the circumferential direction together with the output shaft 90 and the sensor 56 at the 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 tubular portion 112 is held to extend parallel to the fourth axis A4, thereby radially separating the tubular portion 112 and the rotor shaft 76 from each other.

With this configuration, the cylindrical portion 112 and the rotor shaft 76 can be reliably separated from each other. The protection tube 58 does not interfere with the rotation of the rotor shaft 76 and can prevent damage to the protection tube 58 due to contact between the protection tube 58 and the rotor shaft 76 .

When the output shaft 90 is rotated, the clamp member 60 fixed to the output shaft 90 also rotates in the circumferential direction together with the output shaft 90 at the speed V2. Therefore, the clamping portion 130 of the clamping member 60 is displaced in the circumferential direction with respect to the clamping portion 122 of the clamping member 59 . Along with this, the filamentous body 26 is twisted between the

clamp portions

122 and 130 .

However, as described above, since the total length of the filamentous body 26 between the clamping

portions

122 and 130 is set longer than the axial distance between the clamping

portions

122 and 130, the filamentous body 26 is twisted. Even if it is pulled, it is possible to prevent excessive tension from being applied to the filamentous body 26 .

As described above, in the present embodiment, the rotating shaft structure 50 is provided in the hollow fixed portion 136 (

housings

62 and 84, stator 64) and the fixed portion 136 so as to be rotatable around the axis J4. a hollow rotating part 134 (rotor 66, internal gear 86, external gear 88, output shaft 90, and sensor 56); there is

Then, the rotating part 134 includes a first rotating element (sensor 56 ) and a second sensor disposed between the first rotating element 56 and the fixed part 136 and fixed to the first rotating element 56 . The protective tube 58 has a flange portion 114 sandwiched between the first rotating element 56 and the second rotating element 90 so that the tubular portion 112 is aligned with the axis A4. held parallel to the

According to this configuration, the protective tube 58 can be stably held without using fasteners such as bolts. can be made compact in axial dimension. Therefore, the rotary shaft structure 50 can be applied to a relatively small machine, and the weight of the rotary shaft structure 50 and the number of parts can be reduced. In addition, since the cylindrical portion 112 can be stably held in parallel with the axial direction, even if the protective tube 58 rotates during operation of the rotating shaft structure 50, the filament wire wired inside the cylindrical portion 112 can be prevented. The body 26 can be stably protected.

In addition, in the present embodiment, the rotating portion 134 and the third rotating element (rotor shaft 76) are arranged separately radially outwardly of the cylindrical portion 112 so as to surround the cylindrical portion 112. , a fourth rotating element ( It also has an internal gear 86 and an external gear 88).

According to this configuration, the rotation torque of the second rotation element 90 can be increased by the

fourth rotation elements

86 and 88 . Further, 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 protecting tube 58 during operation of the rotating shaft structure 50, interference between the protecting tube 58 and the third rotating element 76 is prevented as described above. It is possible to prevent the protective tube 58 from being damaged.

Further, in this embodiment, the fixed portion 136 has a stator 64 that generates power to rotationally drive the rotating portion 134, and the first rotating element 56, the second rotating element 90, and the stator 64 are shafts. arranged side by side. According to this configuration, the radial dimension of the rotating shaft structure 50 can be made compact.

Also, 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 the elastic restoring force generated by the elastic member 116 compressed between the first rotating element 56 and the flange portion 114 .

Further, in this embodiment, the first rotating element 56 is the sensor 56 that detects the force acting on the first rotating element 56 , and the elastic member 116 is between the sensor 56 and the flange portion 114 . Interposed, the flange portion 114 is spaced from the sensor 56 . According to this configuration, it is possible to prevent the force from being applied to the sensor 56 from the flange portion 114. On the other hand, the force applied from the elastic member 116 to the sensor 56 causes a relatively small strain on the sensor 56, so that the force detection of the sensor 56 can be prevented. Accuracy can be improved.

In this embodiment, the sensor 56 includes an inner ring 102, an outer ring 104 arranged radially outside the inner ring 102, and a beam portion 106 radially extending 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 .

According to this configuration, the strain generated in the inner ring 102 by the elastic member 116 is relatively small as described above. It is possible to reliably prevent the gauge 108 from being affected by the force applied from the elastic member 116 . Therefore, the force detection accuracy of the sensor 56 can be improved more effectively.

Also, in this embodiment, the protective tube 58 is made of resin. According to this configuration, it is possible to reduce the possibility that the filamentous body 26 is damaged by the filamentary body 26 coming into contact with the protective tube 58, so that the filamentous body 26 can be stably protected. In addition, in the present embodiment, the rotating portion 134 and the protection tube 58 are arranged coaxially with the axis J4 as a reference. According to this configuration, when the protective tube 58 rotates together with the first rotary element 56 and the second rotary element 90, the protective tube 58 is not radially displaced. Therefore, the filamentous body 26 can be stably protected during rotation of the protective tube 58 .

Next, a rotating shaft structure 50' according to another embodiment will be described with reference to FIG. The rotating shaft structure 50' differs from the rotating shaft structure 50 described above in the protective tube 58'. The protective tube 58' has a tubular portion 112' and a flange portion 114. As shown in FIG. In this embodiment, the tubular portion 112 ′ has its axial front end 112 a located inside the inner ring 102 of the sensor 56 .

Note that 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 applied to the sensor 56 from the protective tube 58' can be prevented. Further, the axial front end face 112 b of the cylindrical portion 112 ′ may be arranged at substantially the same axial position as the axial front end face of the sensor 56 . The clamping portion 130 is arranged inside the inner ring 102 at an axial position between the flange portion 114 and the end face 112b of the tubular portion 112'.

In addition, in the

rotary shaft structure

50 or 50 ′, the clamp portion 130 may be arranged in the inner ring 102 at substantially the same axial position as the axially front end surface of the sensor 56 . In addition, in the rotating shaft structure 50 or 50', the clamping portion 122 (Fig. 2) is arranged inside the tubular portion 112 or 112' in substantially the same axial direction as the end surface of the tubular portion 112 or 112' on the rear side in the axial direction. It may be placed in a directional position.

According to this configuration, the distance between the clamping

portions

122 and 130 arranged inside the rotating portion 134 and the fixed portion 136 can be maximized in the rotating shaft structure 50 or 50'. Therefore, even if the clamping portion 130 is displaced in the circumferential direction with respect to the clamping portion 122 during operation of the rotary shaft structure 50 or 50', the twisting of the filamentous body 26 can be relaxed, and thus the filamentous body 26 can be reduced.

The protection tube 58 or 58' may be made of a combination of resin and metal (for example, iron). For example, the tubular portion 112 or 112' may be made of resin while the flange portion 114 is made of metal. In this case, the axial rear end surface 114b of the flange portion 114 may be formed by cutting in order to improve the flatness. According to this configuration, the end surface 114b and the end surface 98a of the inner flange 98 are brought into close contact with each other, and the frictional force therebetween can be increased. Note that the protection tube 58 or 58' may be composed only of metal.

Also, in the above-described embodiment, the case where the first rotating element is the sensor 56 that detects force has been described. However, not limited to this, the first rotating element may have the sensor 56 and a member fixed to the sensor 56 . Alternatively, the first rotating element may simply be a metal member or may be part of the proximal end 24a of the distal arm 24. As shown in FIG. Similarly, the second rotating element 90 is not limited to the output shaft 90 of the speed reducer 54, and may be, for example, a sensor that detects force, or any other member.

Also, the speed reducer 54 can be omitted from the rotating shaft structure 50 or 50' described above. In this case, an annular second rotating element is fixedly attached to the axial front end of the rotor shaft 76 and between the second rotating element and the first rotating element (e.g. sensor 56) a protective The flange portion 114 of the tube 58 may be clamped.

Also, in the above-described embodiment, the case where the electric motor 52, the speed reducer 54, and the sensor 56 are arranged substantially coaxially with the fourth axis A4 as a reference and arranged side by side in the axial direction has been described. However, not limited to this, for example, the electric motor 52 may be arranged at a position offset from the axis A4.

In this case, the electric motor 52 includes a stator 64 arranged at a position offset from the axis A4, an output shaft rotatably driven by the stator 64, a rotor shaft 76 arranged coaxially with the axis A4, and the output shaft to the rotor shaft 76 (for example, a pulley mechanism). Also, the electric motor 52 may be arranged radially outside the speed reducer 54 and the sensor 56 .

Also, the elastic member 116 may be omitted from the rotating shaft structure 50 or 50' described above. 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 contact the sensor 56 . Further, the sensor 56 is not limited to having the inner ring 102, the outer ring 104, and the beam portion 106, but may have a form in which the strain gauge 108 is provided on an annular member such as the inner ring 102, for example.

Also, in the above-described embodiment, the case where the protective tubes 58 and 58' are arranged coaxially with the rotating part 134 with the axis J4 as a reference has been described. However, the present invention is not limited to this, and the protective tube 58 or 58' may be arranged at a position where its central axis is radially offset 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' extends from the fourth axis A4 by a predetermined distance. They are radially displaced by the distance.

Further, in the above-described embodiment, the case where the housing 62 is fixed to the cylindrical portion 22b of the proximal end arm 22 and the sensor 56 (outer ring 104) is fixed to the proximal end portion 24a of the distal end arm 24 has been described. . However, without being limited to this, the housing 62 may be fixed to the proximal end portion 24 a of the distal arm 24 and the sensor 56 (for example, the outer ring 104 ) may be fixed to the cylindrical portion 22 b of the proximal arm 22 .

In this case, when the stator 64 of the electric motor 52 generates power to rotate the rotor 66, the sensor 56 and the output shaft 90 of the rotating portion 134 are fixed to the cylindrical portion 22b of the base end arm 22. The portion 136 will rotate with respect to the rotating portion 134 and the cylindrical portion 22b. Even in this case, the rotating portion 134 can be considered to rotate relative to the fixed portion 136 . That is, in this paper, the "rotating part" can be defined as rotating relative to the "fixed part".

Also, in the above-described embodiment, pivot structures 50 and 50' are disposed between proximal arm 22 and distal arm 24 to position distal arm 24 relative to proximal arm 22 on fourth axis J4. The case of rotationally driving around has been described. However, the pivot structure 50 or 50' may be provided on any joint axis J1, J2, J3, J5, or J6 of the machine 10.

For example, pivot structure 50 or 50' may be positioned between pivot base 14 and proximal end 16a of upper arm arm 16 to pivot upper arm 16 relative to pivot base 14 along second axis J2. It may be rotationally driven about or positioned between the distal end 16b of the upper arm 16 and the base 22a of the forearm arm 18 to rotate the forearm arm 18 relative to the upper arm 16. 3 may be rotationally driven around an axis J3.

In addition, the machine 10 is not limited to the vertical multi-joint robot as shown in FIG. It may be any type of machine with movable components driven to rotate about axis A. As described above, the present disclosure has been described through the embodiments, but the above-described embodiments do not limit the invention according to the scope of claims.

REFERENCE SIGNS LIST 10 machine 26 linear body 50, 50' rotating shaft structure 52 electric motor 54 speed reducer 56 sensor (first rotating element)
58 Protective 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 ring 104 outer ring 106 beam portion 108 strain gauge 112, 112' tubular portion 114 flange portion 116 elastic member 134 rotating portion 136 fixed portion

Claims

a hollow fixed part;
A hollow rotating part provided in the fixed part so as to be rotatable about an axis, comprising: a first rotating element; and disposed between the first rotating element and the fixed part; a rotating part having a second rotating element fixed to the first rotating element;
A hollow protective tube disposed inside the fixed part and the rotating part, comprising a tubular part and a flange part extending radially outward from the tubular part, a protection tube through which the striatum is wired so as to pass through,
The protective tube is held so that the cylindrical portion extends parallel to the axis by sandwiching the flange portion between the first rotating element and the second rotating element, A rotating shaft structure that rotates with respect to the fixed part together with the first rotating element and the second rotating element.
The rotating part is
a third rotating element spaced radially outward of the tubular portion so as to surround the tubular portion;
a fourth rotating element interposed between the second rotating element and the third rotating element, decelerating the rotation of the third rotating element and transmitting it to the second rotating element; 2. The rotating shaft structure of claim 1, further comprising:
The fixed part has a stator that generates power to rotationally drive the rotating part,
3. The rotating shaft structure according to claim 1, wherein said first rotating element, said second rotating element, and said stator are arranged side by side in the direction of said axis.
The rotating shaft structure according to any one of claims 1 to 3, further comprising an elastic member interposed between the first rotating element and the flange portion.
the first rotating element has a sensor that detects a force acting on the first rotating element;
5. The rotating shaft structure according to claim 4, wherein the elastic member is interposed between the sensor and the flange, and the flange is spaced apart from the sensor.
The sensor is
inner ring;
an outer ring arranged radially outward of the inner ring;
a beam extending radially between the inner ring and the outer ring;
a strain gauge provided on the beam,
The rotary shaft structure according to claim 5, wherein the elastic member is interposed between the inner ring and the flange portion.
The rotating shaft structure according to any one of claims 1 to 6, wherein the protective tube is made of resin.
The rotating shaft structure according to any one of claims 1 to 7, wherein the rotating part and the protective tube are arranged coaxially with respect to the axis.
A rotating shaft structure according to any one of claims 1 to 8;
A machine comprising the striatum.
A rotating shaft structure according to any one of claims 1 to 8;
A robot comprising the striatum.
A rotating shaft structure according to any one of claims 1 to 8;
and the striatum.