WO2023210114A1

WO2023210114A1 - Strain-wave gearing and industrial robot

Info

Publication number: WO2023210114A1
Application number: PCT/JP2023/005188
Authority: WO
Inventors: 雄一浅川; 諒太川内
Original assignee: ナブテスコ株式会社
Priority date: 2022-04-28
Filing date: 2023-02-15
Publication date: 2023-11-02
Also published as: JP2023163832A

Abstract

This strain-wave gearing is provided with an inner spline (3), an outer spline (5), and a wave generator (6). The wave generator (6) is provided with: a cam (31) having a non-circular outer peripheral surface (31a); and a fourth bearing (32) disposed between the inner peripheral surface (21a) of the outer spline (5) and the outer peripheral surface (31a) of the cam (31). The fourth bearing (32) is provided with an outer ring (33), an inner ring (34), a plurality of spheres (35), and a retainer (36). Also provided is a limiter (37) that abuts on the inner ring (34) so as to avoid contact with the retainer (36), and that limits movement of the fourth bearing (32) in the direction of the rotational axis (C). The limiter (37) is formed so that the radial projection length of the cam (31) from the outer peripheral surface (31a) is uniform over the entire periphery of the outer peripheral surface (31a).

Description

Wave gearing and industrial robots

The present invention relates to a wave gear device and an industrial robot.
This application claims priority based on Japanese Patent Application No. 2022-075005 filed in Japan on April 28, 2022, the contents of which are incorporated herein.

The wave gear device includes an internal gear, an elastic external gear that partially meshes with the internal gear, and a wave generator that contacts the inner peripheral surface of the external gear. The wave generator moves the meshing position between the internal gear and the external gear in the circumferential direction around the rotation axis. The wave generator includes: a cam having an elliptical outer circumferential surface having a long axis and a short axis when viewed from the rotational axis direction; a bearing disposed between the inner circumferential surface of the external gear and the outer circumferential surface of the cam; Equipped with
As the bearing, for example, a deep groove ball bearing is used. Such a bearing has an elliptical shape when viewed from the rotational axis direction, corresponding to the shape of the outer peripheral surface of the cam. A bearing includes, for example, an outer ring, an inner ring, rolling elements arranged between the outer ring and the inner ring, and a retainer that holds the rolling elements.

When the above-mentioned wave gear device is driven, a thrust force is generated in the wave generator due to the elastic deformation of the external gear. If the wave generator moves in the direction of the rotational axis due to this thrust force, there is a possibility that the internal gear and the external gear will not mesh properly. The load on the bearing may become excessive and the bearing may be damaged. If, for example, the movement of the cam in the direction of the rotation axis is restricted in order to prevent movement of the wave generator in the direction of the rotation axis, the bearing will move relative to the cam. For this reason, a technique has been disclosed in which an adhesive is applied between the cam and the bearing to increase the adhesive strength between the cam and the bearing. A technique is disclosed in which a collar is provided to prevent the retainer from jumping out of the bearing when a thrust force is generated.

International Publication No. 2020/044524

However, the above-mentioned conventional technology has a problem in that it is difficult to satisfy the adhesive strength between the cam and the bearing due to the intrusion of oil, foreign matter, etc.
If a collar is provided to prevent the retainer from coming out from the bearing, it not only impedes the lubricity of the bearing, but also crushes the retainer, potentially damaging the bearing.

For example, when the flange is formed in a perfect circle shape when viewed from the rotation axis direction, the bearing has an elliptical shape when viewed from the rotation axis direction. For this reason, the range of contact of the flange with the bearing is not uniform over the entire circumference. That is, for example, on the short shaft side of the bearing, the flange contacts the inner ring of the bearing. On the other hand, on the long axis side of the bearing, the flange may not come into contact with the inner ring of the bearing. Therefore, when the inner ring of the bearing is strongly pressed against the flange, there is a possibility that the inner ring of the bearing will be bent.

The present invention provides a wave gear device and an industrial robot that can restrict the movement of a bearing in the rotational axis direction and prevent damage to the bearing.

A wave gear device according to one aspect of the present invention includes an internal gear, an elastic external gear disposed inside the internal gear in a radial direction, and a wave gear that contacts an inner circumferential surface of the external gear. a generator, the external gear partially meshes with the internal gear and rotates relative to the internal gear around a rotation axis, and the wave generator and the external gear are moved in the circumferential direction around the rotation axis, and the wave generator includes a cam having a non-circular outer circumferential surface, and a meshing position between the inner circumferential surface of the external gear and the cam. a bearing arranged between the outer circumferential surface of the external gear, an outer ring that contacts the inner circumferential surface of the external gear, an inner ring that contacts the outer circumferential surface of the cam, and an outer ring that contacts the outer circumferential surface of the cam. A regulation comprising: a plurality of rolling elements disposed between the inner ring and a retainer holding the plurality of rolling elements, and contacts the inner ring of the bearing to avoid contact with the retainer. The regulating portion is formed such that a radial protrusion length of the cam from the outer circumferential surface of the cam is uniform over the entire circumference of the outer circumferential surface of the cam; The movement of the bearing in the direction of the rotation axis is restricted.

With this configuration, the restriction portion can restrict movement of the bearing in the rotational axis direction while avoiding contact with the retainer. Therefore, movement of the bearing in the direction of the rotational axis can be restricted and damage to the bearing retainer can be prevented.
The restricting portion is formed so that the radial protrusion length from the outer circumferential surface of the cam is uniform over the entire circumference of the outer circumferential surface. Therefore, the regulating portion is uniformly contacted over the entire circumference of the inner ring of the bearing. Therefore, even if the inner ring of the bearing is strongly pressed against the restriction portion, the inner ring of the bearing can be prevented from being bent, and damage to the bearing can be prevented.

In the above configuration, the regulating portion is formed in a flange shape projecting radially outward from the outer circumferential surface of the cam, and the outer circumferential surface of the regulating portion faces the retainer in the radial direction with a gap therebetween. You may.

In the above configuration, the outer circumferential surface of the cam and the outer circumferential surface of the regulating portion are respectively formed in an elliptical shape or an oval shape having a long axis and a short axis when viewed from the rotational axis direction, and the length of the cam is The shaft and the long axis of the restriction part may be located on the same straight line, and the short axis of the cam and the short axis of the restriction part may be located on the same straight line.

In the above configuration, the outer diameter of an arbitrary part of the cam is defined as D1, the outer diameter of the same part of the regulating part as the arbitrary part of the cam is defined as D2, and the radial thickness of the inner ring is defined as D2. When defined as T, the outer diameters D1 and D2 and the thickness T may satisfy (D2-D1)/2≦T.

In the above configuration, the regulating portion may be provided on both sides of the inner ring in the direction of the rotation axis.

In the above configuration, the restriction portion may be integrally molded with the cam.

A wave gear device according to another aspect of the present invention includes an internal gear, an elastic external gear disposed inside the internal gear in the radial direction, and an external gear that contacts an inner circumferential surface of the external gear. a wave generator, wherein the external gear partially meshes with the internal gear and rotates relative to the internal gear around a rotation axis; The meshing position between the gear and the external gear is moved in the circumferential direction around the rotation axis, and the wave generator includes a cam having an outer circumferential surface, the inner circumferential surface of the external gear, and the outer circumference of the cam. a bearing disposed between the cam and the cam, the outer circumferential surface of the cam being formed in either an elliptical shape or an oval shape having a major axis and a minor axis when viewed from the rotational axis direction; The bearing includes an outer ring that contacts the inner circumferential surface of the external gear, an inner ring that contacts the outer circumferential surface of the cam, a plurality of rolling elements arranged between the outer ring and the inner ring, and the plurality of rolling elements. a retainer for holding a rolling element of the cam, and a restriction portion formed in a flange shape extending radially outward from the outer circumferential surface of the cam, the restriction portion having a length when viewed from the rotational axis direction. having an outer circumferential surface formed in either an elliptical shape or an elliptical shape having an axis and a short axis, the long axis of the cam and the long axis of the regulating part are located in the same straight line, The short axis of the cam and the short axis of the regulating portion are located on the same straight line, and the radial protrusion length of the cam from the outer circumferential surface extends over the entire circumference of the outer circumferential surface of the cam. The outer circumferential surface of the regulating part is radially opposed to the retainer with a gap therebetween, and the regulating part contacts the inner ring of the bearing and prevents the bearing. movement in the direction of the rotation axis.

With this configuration, the restriction part can have a simple structure and can restrict movement of the bearing in the rotational axis direction while avoiding contact with the retainer. Therefore, movement of the bearing in the direction of the rotational axis can be restricted and damage to the bearing retainer can be prevented.
The regulating portion can be easily formed so that the radial protrusion length from the outer circumferential surface of the cam is uniform over the entire circumference of the outer circumferential surface. Therefore, the regulating portion is uniformly contacted over the entire circumference of the inner ring of the bearing. Therefore, even if the inner ring of the bearing is strongly pressed against the restriction portion, the inner ring of the bearing can be prevented from being bent, and damage to the bearing can be prevented.

An industrial robot according to another aspect of the present invention includes: a wave gear device having a power generating section that generates rotational force, an input section, and an output section; a counterpart member attached to the output section of the wave gear device; The input section receives the rotational force of the power generation section, the output section changes the speed of the rotation of the input section and outputs the same, and the wave gear device includes an internal gear and the internal gear. an elastic external gear disposed radially inside the gear, and a wave generator in contact with an inner circumferential surface of the external gear; The wave generator meshes with the internal gear to rotate relative to the internal gear around the rotation axis, and functions as one of the input section and the output section, and the wave generator The wave generator moves the meshing position with the cam in the circumferential direction around the rotation axis, and the wave generator includes a cam having a non-circular outer circumferential surface, the inner circumferential surface of the external gear, and the outer circumferential surface of the cam. a bearing disposed between the cam and the cam, the cam functioning as the other of the input section and the output section, and the bearing disposed between the outer ring and the cam. An inner ring that contacts the outer peripheral surface, a plurality of rolling elements arranged between the outer ring and the inner ring, and a cage that holds the plurality of rolling elements, and avoids contact with the cage. a regulating portion that contacts the inner ring of the bearing, and the regulating portion has a radial protrusion length from the outer circumferential surface of the cam that is uniform over the entire circumference of the outer circumferential surface of the cam. The bearing is formed so as to restrict movement of the bearing in the direction of the rotation axis.

With this configuration, it is possible to provide an industrial robot that restricts movement of the bearing in the direction of the rotational axis and prevents damage to the bearing.

The wave gear device and industrial robot described above can prevent damage to the bearing by regulating the movement of the bearing in the direction of the rotation axis.

1 is a schematic configuration diagram of an industrial robot in an embodiment of the present invention. FIG. 2 is a cross-sectional view along the rotational axis of the strain wave gear device according to the embodiment of the present invention. 3 is a plan view of the cam according to the embodiment of the present invention viewed from above, and corresponds to a sectional view taken along line III-III in FIG. 2. FIG. FIG. 7 is a cross-sectional view along the rotation axis showing a modification of the regulating portion in the embodiment of the present invention.

Next, embodiments of the present invention will be described based on the drawings.

<Industrial robot>
FIG. 1 is a schematic configuration diagram of an industrial robot 100.
As shown in FIG. 1, the industrial robot 100 includes a traveling rail 101, a base unit (an example of a counterpart member in the claims) 102 movably provided on the traveling rail 101, and a base unit 102 provided on the base unit 102. A robot body 103 is provided. Motors with

reduction gears

106, 113a-113f are provided at the

joints

111, 112a-112e of the arms 115a-115d (an example of a mating member in the claims) of the base unit 102 and the robot body 103, respectively.

Each of the speed reducer-equipped

motors

106, 113a to 113f has a similar configuration. Among the motors with a

reduction gear

106, 113a to 113f, the motor with a reduction gear 106 provided in the base unit 102 will be described as an example. This motor 106 with a speed reducer includes a wave gear device 1 and an electric motor 110 (an example of a power generation unit in the claims) that provides power to the wave gear device 1.

In FIG. 1, the illustrations of the other motors 113a to 113f with reduction gears are simplified, and the symbols of the wave gear device and the electric motor are omitted. In the following description, only the motor with a reduction gear 106 of the base unit 102 will be explained, and the description of the other motors with reduction gears 113a to 113f will be omitted.
In the industrial robot 100, the robot main body 103 travels on the traveling rail 101 and each of the arms 115a to 115d assumes various postures by driving the

motors

106 and 113a to 113f with reduction gears.

<Wave gearing>
Next, the strain wave gear device 1 will be explained based on FIGS. 2 to 3.
FIG. 2 is a cross-sectional view of the wave gear device 1 along the rotation axis C. In FIG. 2, illustration of the lower half around the rotation axis C is omitted. In the following description, the direction of the rotational axis C will be simply referred to as the axial direction, the circumferential direction around the rotational axis C will be referred to as the circumferential direction, and the radial direction of the wave gear device 1 perpendicular to the axial direction and the circumferential direction will be simply referred to as the radial direction. In the following description, the upward direction and the downward direction will be referred to when the motor 106 with a reduction gear is fixed on the base unit 102.

As shown in FIG. 2, the wave gear device 1 includes a housing 2, an internal gear 3 and a first bearing 4 fixed to the housing 2, and an external gear provided inside the internal gear 3 in the radial direction. 5, a wave generator 6 provided inside the external gear 5 in the radial direction, an output plate 7 (an example of an output part in the claims) fixed to the external gear 5 together with the first bearing 4, and an electric A reduction gear shaft 8 is connected to the motor shaft 110a of the motor 110 and applies rotational force to the wave generator 6. A motor shaft 110a of an electric motor 110 is connected to the upper end of the reducer shaft 8 (on the right side in FIG. 2). The output plate 7 is arranged at the lower end of the reducer shaft 8 (on the left side in FIG. 2).

<Housing>
The housing 2 is fixed to the base unit 102 by bolts (not shown). The housing 2 is formed into a disk shape. However, the shape of the housing 2 is not limited to a disk shape. A cylindrical boss portion 2c is integrally formed in the radial center of the housing 2. By fitting this boss portion 2c into, for example, a through hole 102a formed in the base unit 102, the position of the reduction gear motor 106 with respect to the base unit 102 is determined.

A stepped through hole 9 is formed in most of the radial center of the boss portion 2c. A speed reducer shaft 8 is inserted into the stepped through hole 9 .
The stepped through hole 9 has a small diameter hole 9a formed in the upper part (on the electric motor 110 side) and a large diameter hole 9b formed in the lower part of the small diameter hole 9a (on the opposite side to the electric motor 110). . The large diameter hole 9b is connected to the small diameter hole 9a via a stepped portion 9c. The inner diameter of the large diameter hole 9b is larger than that of the small diameter hole 9a.

A seal portion 10 that ensures sealing between the boss portion 2c and the reduction gear shaft 8 is attached to the small diameter hole 9a. As the seal portion 10, various seal members such as a rubber oil seal can be used.
A second bearing 11 is fitted into the large diameter hole 9b. The second bearing 11 rotatably supports the upper end of the reducer shaft 8 on the boss portion 2c. As the second bearing 11, for example, a deep groove ball bearing is used. However, the bearing is not limited to this, and various bearings can be used. In this embodiment, the outer ring 11a of the second bearing 11 abuts against the stepped portion 9c of the stepped through hole 9, thereby positioning the second bearing 11 in the axial direction with respect to the boss portion 2c.

A gear storage recess 12 is formed in the lower surface 2a of the housing 2 in most of the radial center. The gear storage recess 12 is open on the lower side and on the inside in the radial direction. The internal gear 3 is housed in the gear housing recess 12. A plurality of through holes 2b are formed in the outer circumferential portion of the bottom surface 12a of the gear storage recess 12, which penetrate in the axial direction. The plurality of through holes 2b are arranged at equal intervals in the circumferential direction. The plurality of through holes 2b are for fixing the housing 2 to the base unit 102 together with the internal gear 3 and the first bearing 4. A bolt (not shown) is inserted into each through hole 2b from above.

<Internal gear>
The internal gear 3 is formed of a rigid body into an annular shape. The axis of the internal gear 3 coincides with the rotation axis C. The outer peripheral surface of the internal gear 3 is fitted into the inner peripheral surface of the gear storage recess 12 of the housing 2. By abutting the top surface 3a of the internal gear 3 against the bottom surface 12a of the gear storage recess 12, the internal gear 3 is positioned with respect to the housing 2 in the axial direction. The internal gear 3 is formed with a through hole 3f that penetrates in the axial direction. The through holes 3f are formed coaxially with the through holes 2b of the housing 2, respectively. These through holes 3f communicate with corresponding through holes 2b of the housing 2, respectively.

An O-ring groove 3b is formed in the inner circumference of the upper surface 3a of the internal gear 3. An O-ring 13 is attached to the O-ring groove 3b. The O-ring 13 seals between the internal gear 3 and the housing 2.
Internal teeth 3c are formed on the inner peripheral surface of the internal gear 3 over the entire circumference. External teeth 5a, which will be described later, of the external gear 5 mesh with the internal teeth 3c.

On the lower surface 3d of the internal gear 3, a bearing housing recess 14 is formed in most of the outer circumference. The bearing storage recess 14 is open at the bottom and the outside in the radial direction. The first bearing 4 is housed in the bearing housing recess 14 . An O-ring groove 3e is formed in the inner circumference of the bottom surface 14a of the bearing storage recess 14. An O-ring 15 is attached to the O-ring groove 3e. The O-ring 15 seals between the internal gear 3 and the first bearing 4.

<First bearing>
The first bearing 4 includes an outer ring 16 , an inner ring 17 , and spheres 18 that are a plurality of rolling elements arranged between the outer ring 16 and the inner ring 17 . The inner circumferential surface of the inner ring 17 is fitted into the outer circumferential surface of the bearing housing recess 14 . By abutting the top surface 17a of the inner ring 17 against the bottom surface 14a of the bearing storage recess 14, the first bearing 4 is positioned relative to the internal gear 3 in the axial direction.

On the upper surface 17a of the inner ring 17, female threaded portions 17b are formed coaxially with the through hole 3f of the internal gear 3. These female screw portions 17b communicate with corresponding through holes 3f of the internal gear 3, respectively. A bolt (not shown) inserted into each through hole 2b of the housing 2 from above is tightened to the female threaded portion 17b of the inner ring 17 through the through hole 3f of the internal gear 3. Thereby, the housing 2, the internal gear 3, and the inner ring 17 of the first bearing 4 are integrally fixed to the base unit 102 by bolts (not shown).

The outer ring 16 of the first bearing 4 has a plurality of through holes 16a formed in the outer circumferential portion thereof that penetrate in the axial direction. The plurality of through holes 16a are arranged at equal intervals in the circumferential direction. The plurality of through holes 16a are for integrating the outer ring 16 of the first bearing 4, the external gear 5, and the output plate 7 with bolts (not shown).

A seal storage recess 19 is formed in the inner peripheral portion of the upper surface 16b of the outer ring 16. A seal portion 20 is provided in the seal storage recess 19. The seal portion 20 seals between the outer ring 16 and the inner ring 17 above the first bearing 4 . As the seal portion 20, various seal members such as a rubber oil seal can be used.
The lower surface 16c of the outer ring 16 projects slightly further downward than the lower surface 17c of the inner ring 17. An O-ring groove 16d is formed in the inner peripheral portion of the lower surface 16c of the outer ring 16. An O-ring 40 is attached to the O-ring groove 16d. O-ring 40 seals between outer ring 16 and external gear 5.

<External gear>
The external gear 5 is made of an elastic member. For example, the external gear 5 is formed of a thin metal plate or the like. The external gear 5 has a cylindrical portion 21 concentric with the internal gear 3, and an outer flange portion 22 that bends and projects radially outward from the lower end of the cylindrical portion 21. The cylindrical portion 21 extends from the upper surface 3a of the internal gear 3 to the lower surface 16c of the outer ring 16 of the first bearing 4. External teeth 5a are formed on the outer peripheral surface of the cylindrical portion 21. The external teeth 5a are formed at positions facing the internal teeth 3c of the internal gear 3 in the radial direction. The external teeth 5a mesh with the internal teeth 3c of the internal gear 3. The number of external teeth 5a is smaller than the number of internal teeth 3c. For example, the number of external teeth 5a is two fewer than the number of internal teeth 3c.

The outer flange portion 22 extends from the lower end of the cylindrical portion 21 to the outer peripheral surface of the outer ring 16 of the first bearing 4. The outer periphery of the outer flange portion 22 overlaps the lower surface 16c of the outer ring 16 in the axial direction. A thick wall portion 22a, which is thicker than other portions, is formed on the outer periphery of the outer flange portion 22. The thick portion 22a is formed at a location that overlaps the outer ring 16 in the axial direction. A through hole 22b is formed in the thick portion 22a. The through hole 22b is formed coaxially with the through hole 16a of the outer ring 16. These through holes 22b communicate with corresponding through holes 16a of the outer ring 16, respectively.

<Output plate>
The output plate 7 is arranged so as to overlap the thick portion 22a of the outer flange portion 22 in the axial direction. The output plate 7 is formed into a disk shape. A pinion gear 107 is attached to the lower surface 7a of the output plate 7, for example, for transmitting the power of the motor 106 with a speed reducer to the base unit 102.
A fitting cylindrical portion 23 is formed on the outer peripheral portion of the output plate 7 and projects toward the first bearing 4 side. The outer circumferential surface of the thick portion 22 a and a portion of the outer circumferential surface of the outer ring 16 of the first bearing 4 are fitted into the inner circumferential surface of the fitting cylindrical portion 23 . This determines the relative positions of the housing 2, internal gear 3, first bearing 4, external gear 5, and output plate 7 in the radial and axial directions.

A through hole 7b is formed in the outer peripheral portion of the output plate 7, radially inside the fitting cylindrical portion 23. The through hole 7b is formed coaxially with the through hole 22b of the thick portion 22a. These through holes 7b each communicate with the corresponding through hole 22b of the thick portion 22a. Under such a configuration, bolts (not shown) are inserted from above the outer ring 16 into the through hole 16a, the through hole 22b of the thick portion 22a, and the through hole 7b of the output plate 7 in this order, for example, to form the pinion gear 107. Tighten the bolt to the female thread (not shown). As a result, the outer ring 16 of the first bearing 4, the external gear 5, and the output plate 7 are integrally fixed to the pinion gear 107 by bolts (not shown). When the pinion gear 107 is removed, the outer ring 16 of the first bearing 4, the external gear 5, and the output plate 7 can be integrated with bolts and nuts (not shown), for example.

An O-ring groove 7d is formed in the upper surface 7c of the output plate 7. The O-ring groove 7d is formed radially inside the through hole 7b. An O-ring 25 is attached to the O-ring groove 7d. The O-ring 25 seals between the thick portion 22a and the output plate 7.
A shaft insertion hole 24 is formed in the radial center of the output plate 7 and extends through the output plate 7 in the axial direction. The reducer shaft 8 is inserted into the shaft insertion hole 24 . An O-ring 25 is attached to the shaft insertion hole 24 of the output plate 7 to ensure sealing between the output plate 7 and the reduction gear shaft 8.

A cylindrical bearing boss 27 that projects upward is integrally formed on the upper surface 7c of the output plate 7. The bearing boss 27 is formed outside the shaft insertion hole 24 in the radial direction. The outer circumferential surface of the third bearing 28 is fitted into the inner circumferential surface of the bearing boss 27 . The third bearing 28 rotatably supports the lower end of the reducer shaft 8 on the output plate 7 . As the third bearing 28, for example, a deep groove ball bearing is used. However, the bearing is not limited to this, and various bearings can be used.

<Reduction gear shaft>
The reducer shaft 8, which is rotatably supported at both ends by two

bearings

11 and 28, is formed in a hollow shape. The outer peripheral surface of the reducer shaft 8 is formed in a stepped shape. That is, the outer circumferential surface of the reducer shaft 8 has a seal outer circumferential surface 8a formed at both ends, a bearing outer circumferential surface 8b formed on the axially inner side of each seal outer circumferential surface 8a, and a gap between the two bearing outer circumferential surfaces 8b. The shaft main body outer peripheral surface 8c is formed.

Seal portions

10 and 26 are attached to each seal outer peripheral surface 8a, respectively. A second bearing 11 and a third bearing 28 are attached to each bearing outer peripheral surface 8b, respectively. The bearing outer circumferential surface 8b is formed so that its diameter is larger than the seal outer circumferential surface 8a via the stepped portion 8d. The shaft main body outer circumferential surface 8c is formed so that its diameter is larger than the bearing outer circumferential surface 8b via the stepped portion 8e. Each bearing 11, 28 is positioned in the axial direction with respect to the reducer shaft 8 by abutting against the corresponding

step portion

8d, 8e.

<Wave generator>
The wave generator 6 is provided between the shaft body outer peripheral surface 8c of the reducer shaft 8 and the external teeth 5a of the external gear 5 (internal teeth 3c of the internal gear 3) in the radial direction. The wave generator 6 includes a cam 31 integrally molded on the outer peripheral surface 8c of the shaft main body, and a fourth cam 31 disposed between the outer peripheral surface 31a of the cam 31 and the inner peripheral surface 21a of the cylindrical portion 21 of the external gear 5. A bearing (an example of a bearing in the claims) 32.

<Cam>
FIG. 3 is a plan view of the cam 31 viewed from above, and corresponds to a sectional view taken along line III--III in FIG.
As shown in FIGS. 2 and 3, the cam 31 is formed to protrude radially outward from the shaft main body outer peripheral surface 8c. The outer peripheral surface 31a of the cam 31 is formed into an elliptical shape when viewed from the axial direction.

<4th bearing>
The fourth bearing 32 is, for example, a deep groove ball bearing. The fourth bearing 32 includes an outer ring 33, an inner ring 34, a plurality of balls 35 that are rolling elements arranged between the outer ring 33 and the inner ring 34, and a cage 36 that holds the plurality of balls 35 in a rollable manner. and. The outer circumferential surface of the outer ring 33 is in contact with the inner circumferential surface 21a of the cylindrical portion 21 of the external gear 5. The inner peripheral surface of the inner ring 34 is fitted into the outer peripheral surface 31a of the cam 31. The axial length L1 of the inner ring 34 is shorter than the axial length L2 of the outer ring 33. The axial length L3 of the cam 31 roughly matches the axial length L1 of the inner ring 34.

<Cage>
The retainer 36 is an annular member that retains a plurality of spheres 35 at equal intervals in the circumferential direction. The retainer 36 has gripping portions 36a that rollably grip the spheres 35 from the outside in the axial direction, and a connecting portion (not shown) that connects the gripping portions 36a adjacent in the circumferential direction. The grip portion 36a protrudes slightly downward from the axial lower end of the inner ring 34 when viewed from the radial direction.

<Regulatory Department>
A regulating portion 37 is integrally formed at the lower end of the cam 31 on the shaft main body outer peripheral surface 8c. The regulating portion 37 is formed in the shape of a flange that protrudes radially outward from the outer circumferential surface 31a of the cam 31. The outer circumferential surface 37a of the regulating portion 37 is formed in an elliptical shape when viewed from the axial direction so as to correspond to the shape of the outer circumferential surface 31a of the cam 31. The long axis RLa of the regulating portion 37 and the long axis CLa of the cam 31 are located on the same straight line. The short axis RSa of the regulating portion 37 and the short axis CSa of the cam 31 are located on the same straight line. Therefore, the regulating portion 37 is formed so that the length of the radial protrusion from the outer circumferential surface 31a of the cam 31 is uniform over the entire circumference of the outer circumferential surface 31a.

The outer diameter of an arbitrary location on the cam 31 is defined as D1, the outer diameter of the regulating portion 37 at the same location as the arbitrary location on the cam 31 is defined as D2, and the wall thickness of the inner ring 34 of the fourth bearing 32 is defined as T. When defined, the outer diameters D1, D2 and the thickness T are
(D2-D1)/2≦T...(1)
satisfy.

In addition to the above formula (1), since the regulating portion 37 is integrally molded on the lower end of the cam 31, it faces the retainer 36 (gripping portion 36a) of the fourth bearing 32 in the radial direction. Contact of the regulating portion 37 with the retainer 36 is reliably avoided.
The lower end of the inner ring 34 of the fourth bearing 32 abuts against the upper surface 37b of the regulating portion 37. This restricts the movement of the fourth bearing 32 in the axial direction.

The regulating portion 37 is formed so that the radial protrusion length of the cam 31 from the outer circumferential surface 31a is uniform over the entire circumference of the outer circumferential surface 31a. Therefore, the regulating portion 37 uniformly abuts against the entire circumference of the inner ring 34 of the fourth bearing 32 . The retainer 36 (grip portion 36a) and the restriction portion 37 of the fourth bearing 32 face each other in the radial direction across the entire circumference of the outer circumferential surface 31a of the cam 31 with a constant gap G therebetween. The regulating portion 37 reliably protrudes in the radial direction from the outer circumferential surface 31a of the cam 31. Therefore, the restriction portion 37 reliably restricts movement of the fourth bearing 32 in the axial direction.

<Operation of wave gear device>
Next, the operation of the wave gear device 1 of the motor 106 with a reduction gear will be explained. The wave gear devices of the other speed reducer motors 113a to 113f provided on the robot body 103 operate in the same manner as the wave gear device 1 of the speed reducer motor 106 provided on the base unit 102.

First, the outer peripheral surface 31a of the cam 31 of the wave generator 6 is formed into an elliptical shape when viewed from the axial direction. Therefore, the external gear 5 is elastically deformed via the fourth bearing 32, and the external teeth 5a and the internal teeth 3c of the internal gear 3 are partially meshed. In this state, when the motor shaft 110a is rotated by driving the electric motor 110, the reducer shaft 8 is rotated integrally with the motor shaft 110a. The cam 31 is rotated together with the reducer shaft 8. That is, the cam 31 of the wave generator 6 functions as an input section into which the rotational force of the motor shaft 110a of the electric motor 110 is input.

The external teeth 5a and the internal teeth 3c have different numbers of teeth. Therefore, while their mutual meshing positions move in the circumferential direction, they rotate relative to each other around the rotation axis C due to the difference in the number of teeth. In this embodiment, the number of external teeth 5a is smaller than the number of internal teeth 3c. Therefore, the external gear 5 is rotated at a rotation speed lower than that of the reducer shaft 8. The external gear 5 is rotated while being elastically deformed.

The outer flange portion 22 of the external gear 5 is integrated with the outer ring 16 of the first bearing 4 and the output plate 7. Therefore, the outer ring 16 of the first bearing 4 and the output plate 7 are outputted while being decelerated relative to the rotation of the motor shaft 110a (reducer shaft 8). That is, the external gear 5 functions as an output section that changes the speed (in this embodiment, decelerates) the rotation of the cam 31, which is an input section, and outputs the same.
The rotation of the output plate 7 causes the pinion gear 107 to rotate. Then, the base unit 102 is slid along the running rail 101 (see FIG. 1).

By the way, when the wave gear device 1 is driven, a downward thrust force is generated in the wave generator 6 due to the elastic deformation of the external gear 5. The cam 31 of the wave generator 6 is integrally molded with the reduction gear shaft 8. Movement of the reducer shaft 8 in the axial direction is restricted by the second bearing 11 and the third bearing 28 arranged on both sides in the axial direction. Therefore, a downward thrust force is applied to the fourth bearing 32 of the wave generator 6.

A regulating portion 37 is integrally formed on the outer circumferential surface 8c of the shaft main body of the reducer shaft 8 at the lower end of the cam 31. The regulating portion 37 is formed in the shape of a flange that protrudes radially outward from the outer circumferential surface 31a of the cam 31. The lower end of the inner ring 34 of the fourth bearing 32 abuts against such a restriction portion 37 . Therefore, the restriction portion 37 restricts movement of the fourth bearing 32 in the axial direction.

In this way, in the wave gear device 1 described above, the movement of the fourth bearing 32 in the axial direction can be restricted by the restriction portion 37. Therefore, the internal teeth 3c of the internal gear 3 and the external teeth 5a of the external gear 5 can be continuously and properly meshed. Therefore, the wave gear device 1 can be operated stably.

The regulating portion 37 is formed so as to avoid contact between the fourth bearing 32 and the retainer 36. Therefore, damage to the fourth bearing 32 caused by the regulating portion 37 can be prevented. Furthermore, the restricting portion 37 is formed so that the length of the radial protrusion from the outer circumferential surface 31a of the cam 31 is uniform over the entire circumference of the outer circumferential surface 31a. Therefore, the upper surface 37b of the regulating portion 37 is uniformly contacted over the entire circumference of the inner ring 34 of the fourth bearing 32. Therefore, even if the inner ring 34 of the fourth bearing 32 is strongly pressed against the regulating portion 37, stress will not be locally applied to the inner ring 34. As a result, the inner ring 34 can be prevented from being bent, and the fourth bearing 32 can be prevented from being damaged.

The regulating portion 37 faces the retainer 36 (grip portion 36a) in the radial direction with a gap G in between so as to avoid contact between the fourth bearing 32 and the retainer 36. With this configuration, contact with the retainer 36 can be avoided while the restricting part 37 has a simple structure.
The outer circumferential surface 31a of the cam 31 and the outer circumferential surface 37a of the regulating portion 37 are each formed in an elliptical shape when viewed from the axial direction. The long axis RLa of the regulating portion 37 and the long axis CLa of the cam 31 are located on the same straight line. The short axis RSa of the regulating portion 37 and the short axis CSa of the cam 31 are located on the same straight line. Therefore, the radial protrusion length of the restricting portion 37 from the outer circumferential surface 31a of the cam 31 can be reliably made uniform over the entire circumference of the outer circumferential surface 31a.

The outer diameter D1 of an arbitrary part of the cam 31, the outer diameter D2 of the regulating part 37 at the same part as the arbitrary part of the cam 31, and the wall thickness T of the inner ring 34 of the fourth bearing 32 satisfy the above formula (1). . Therefore, the movement of the fourth bearing 32 in the axial direction can be more reliably regulated while preventing the regulating portion 37 from coming into contact with the retainer 36 more reliably.
The regulating portion 37 is integrally formed on the shaft main body outer peripheral surface 8c and the lower end of the cam 31. Therefore, the regulating portion 37 can be easily provided.

Motors with

reduction gears

106, 113a to 113f using the wave generator 6 as described above are employed in the industrial robot 100. Thereby, damage to the fourth bearing 32 can be prevented, and the industrial robot 100 with stable operation and high reliability can be provided.

The present invention is not limited to the above-described embodiments, but includes various modifications to the above-described embodiments without departing from the spirit of the present invention.
For example, in the above-described embodiment, a case has been described in which the industrial robot 100 uses the reducer-equipped

motors

106, 113a to 113f equipped with the wave gear device 1. However, the present invention is not limited to this, and the wave gear device 1 can be employed in the drive unit of various industrial robots other than the industrial robot 100. The industrial robots herein include various processing machines such as electric wheelchairs, traveling devices, and multi-tasking machines. For example, the wave gear device 1 can be employed in a drive unit (traveling unit) of an electric wheelchair, a traveling device, or a processing machine.

In the above-described embodiment, a case has been described in which the electric motor 110 is used as a power generating section that generates rotational force in the cam 31 as an input section. However, the present invention is not limited to this, and any power generating section may be used as long as it generates rotational force in the cam 31. For example, instead of the electric motor 110, a hydraulic motor, an engine, etc. can be used.

In the above embodiment, the fourth bearing 32 is, for example, a deep groove ball bearing. However, the present invention is not limited to this, and any bearing may be used as long as it includes an outer ring, an inner ring, rolling elements, and a cage. The rolling elements may not be spherical bodies 35. For example, cylindrical rollers may be used as the rolling elements instead of the spheres 35.

In the above-described embodiment, the cam 31 of the wave generator 6 functions as an input section into which the rotational force of the motor shaft 110a of the electric motor 110 is input. A case has been described in which the external gear 5 functions as an output section that changes the speed of the rotation of the cam 31 and outputs the same. However, the present invention is not limited to this, and the external gear 5 may function as an input section, and the cam 31 (reducer shaft 8) may function as an output section.

In the above-described embodiment, the case where the outer circumferential surface 31a of the cam 31 is formed in an elliptical shape when viewed from the axial direction has been described. The case has been described in which the outer circumferential surface 37a of the regulating portion 37 is formed in an elliptical shape when viewed from the axial direction so as to correspond to the shape of the outer circumferential surface 31a of the cam 31. However, the present invention is not limited to this, and the outer circumferential surface 31a of the cam 31 and the outer circumferential surface 37a of the regulating portion 37 may be non-circular. For example, the outer circumferential surface 31a of the cam 31 and the outer circumferential surface 37a of the regulating portion 37 may have a polygonal shape when viewed from the axial direction. The regulating portion 37 may be formed such that the length of the radial protrusion from the outer circumferential surface 31a of the cam 31 is uniform over the entire circumference of the outer circumferential surface 31a. Desirably, the outer circumferential surface 31a of the cam 31 has an elliptical shape or an oval shape having a major axis and a minor axis when viewed from the axial direction.

In the above-described embodiment, a case was described in which the O-ring 13 was provided to seal between the internal gear 3 and the housing 2. A case has been described in which the O-ring 15 is provided to seal between the internal gear 3 and the first bearing 4. A case has been described in which the O-ring 25 is provided to seal between the thick portion 22a and the output plate 7. A case has been described in which the O-ring 40 is provided to seal between the outer ring 16 and the external gear 5. However, the present invention is not limited thereto, and various sealing members can be used instead of the O-

rings

13, 15, 25, and 40.

In the above-described embodiment, the case where the wave gear device 1 includes the housing 2 has been described. However, the present invention is not limited to this, and the housing 2 may not be provided. For example, the internal gear 3 may be directly attached to the base unit 102 or the like, or the reducer shaft 8 may be rotatably supported directly by the base unit 102 or the like.
In the above-described embodiment, the case where the wave gear device 1 includes the output plate 7 has been described. The case where the rotation of the motor shaft 110a (reducer shaft 8) is outputted via the output plate 7 has been described. However, the present invention is not limited to this, and the rotation of the motor shaft 110a (reducer shaft 8) may be directly output from the external gear 5.

In the above-described embodiment, a case has been described in which the housing 2, the internal gear 3, and the inner ring 17 of the first bearing 4 are integrally fixed to the base unit 102 by bolts (not shown). However, the present invention is not limited to this, and various methods can be used to fix the internal gear 3 and the inner ring 17 of the first bearing 4. For example, the internal gear 3 and the inner ring 17 of one bearing 4 may be fixed in advance. The housing 2, the internal gear 3, and the inner ring 17 of the first bearing 4 may be fixed in advance and fixed to a mating member (for example, the base unit 102, etc.).

In the above-described embodiment, the reduction gear shaft 8 has been described as being formed in a hollow shape. However, the present invention is not limited to this, and the reducer shaft 8 may be solid. For example, the reduction gear shaft 8 may be provided with a spur gear, and the rotation of the motor shaft 110a may be transmitted to the reduction gear shaft 8 via this spur gear.

In the embodiment described above, the case where the regulating portion 37 is integrally molded on the lower end of the cam 31 has been described. The case where the lower end of the inner ring 34 of the fourth bearing 32 abuts against the upper surface 37b of the regulating portion 37 has been described. However, the present invention is not limited to this, and the regulating portions 37 may be provided on both sides of the inner ring 34 in the axial direction. With this configuration, the movement of the fourth bearing 32 in the axial direction can be reliably restricted regardless of the direction of the thrust force acting on the fourth bearing 32. The regulating portion 37 may be formed separately from the reducer shaft 8 and the cam 31 instead of being integrally formed therewith. For example, the regulating section 37 may be configured as follows.

[Modified example of regulation section]
FIG. 4 is a cross-sectional view along the rotation axis C showing a modified example of the regulating portion 37. As shown in FIG. FIG. 4 corresponds to FIG. 2 described above.
As shown in FIG. 4, the regulation part 37 includes a regulation support part 41 extending from the upper end of the bearing boss 27 toward the fourth bearing 32, and a regulation part main body 42 provided in the regulation support part 41. It's okay. The regulating portion main body 42 is fixed to the regulating support portion 41 by bolts, welding, or the like (not shown).

The regulating portion main body 42 extends from the regulating support portion 41 along the axial direction, and is formed such that its tip 42a abuts against the inner ring 34 of the fourth bearing 32. That is, the regulating portion main body 42 is provided so as to avoid contact with the retainer 36 of the fourth bearing 32. The regulating portion main body 42 regulates movement of the fourth bearing 32 in the axial direction. The regulating portion main body 42 is formed so that the radial protrusion length from the outer circumferential surface 31a of the cam 31 is uniform over the entire circumference of the outer circumferential surface 31a. Even with this configuration, the same effects as in the above-described embodiment can be achieved.

Among the embodiments disclosed in this specification, those that are composed of a plurality of objects may be integrated, and conversely, those that are composed of one object may be divided into multiple objects. be able to. Regardless of whether they are integrated or not, it is sufficient that the structure is such that the object of the invention can be achieved.

DESCRIPTION OF SYMBOLS 1... Wave gear device, 3... Internal gear, 5... External gear, 6... Wave generator, 21... Cylindrical part, 21a... Inner circumferential surface, 31... Cam, 31a... Outer circumferential surface, 32... Fourth bearing ( bearing), 33...outer ring, 34...inner ring, 35...sphere (rolling element), 36...retainer, 37...regulating section, 37a...outer circumferential surface, 42... regulating section main body (regulating section), 100...industrial robot, 107 ...Pinion gear (mate member), 115a, 115b, 115c, 115d...Arm (mate member), C...rotation axis, CLa...long axis of cam, CSa...short axis of cam, D1...arbitrary outer diameter of cam, D2...outer diameter on D1 in the regulating part, G...gap, RLa...long axis of the regulating part, RSa...short axis of the regulating part

Claims

internal gear,
an elastic external gear disposed radially inside the internal gear;
a wave generator that contacts the inner circumferential surface of the external gear;
Equipped with
The external gear partially meshes with the internal gear and rotates relative to the internal gear around a rotation axis,
The wave generator moves the meshing position of the internal gear and the external gear in a circumferential direction around the rotation axis,
The wave generator is
a cam having a non-circular outer peripheral surface;
a bearing disposed between the inner circumferential surface of the external gear and the outer circumferential surface of the cam;
Equipped with
The bearing is
an outer ring that contacts the inner peripheral surface of the external gear;
an inner ring that contacts the outer peripheral surface of the cam;
a plurality of rolling elements disposed between the outer ring and the inner ring;
a cage that holds the plurality of rolling elements;
Equipped with
a regulating portion that contacts the inner ring of the bearing to avoid contact with the retainer;
The regulating portion is formed such that a radial protrusion length from the outer circumferential surface of the cam is uniform over the entire circumference of the outer circumferential surface of the cam,
The regulating portion regulates movement of the bearing in the direction of the rotation axis.
Wave gear device.
The regulating portion is formed in the shape of a flange extending radially outward from the outer circumferential surface of the cam,
The outer circumferential surface of the regulating portion faces the retainer in the radial direction with a gap therebetween.
The wave gear device according to claim 1.
The outer circumferential surface of the cam and the outer circumferential surface of the regulating portion are each formed in an elliptical shape or an oval shape having a major axis and a minor axis when viewed from the rotation axis direction,
The long axis of the cam and the long axis of the restriction part are located in the same straight line, and the short axis of the cam and the short axis of the restriction part are located in the same straight line,
The wave gear device according to claim 2.
The outer diameter of any part of the cam is defined as D1,
The outer diameter of the regulating portion at the same location as any location on the cam is defined as D2;
When the radial thickness of the inner ring is defined as T,
The outer diameters D1, D2 and the thickness T are
(D2-D1)/2≦T
satisfy,
The wave gear device according to any one of claims 1 to 3.
The regulating portion is provided on both sides of the inner ring in the direction of the rotation axis,
The wave gear device according to any one of claims 1 to 3.
The regulating portion is integrally molded with the cam.
The wave gear device according to any one of claims 1 to 3.
internal gear,
an elastic external gear disposed radially inside the internal gear;
a wave generator that contacts the inner circumferential surface of the external gear;
Equipped with
The external gear partially meshes with the internal gear and rotates relative to the internal gear around a rotation axis,
The wave generator moves the meshing position of the internal gear and the external gear in a circumferential direction around the rotation axis,
The wave generator is
a cam having an outer peripheral surface;
a bearing disposed between the inner circumferential surface of the external gear and the outer circumferential surface of the cam;
Equipped with
The outer circumferential surface of the cam is formed in either an elliptical shape or an oval shape having a major axis and a minor axis when viewed from the rotational axis direction,
The bearing is
an outer ring that contacts the inner peripheral surface of the external gear;
an inner ring that contacts the outer peripheral surface of the cam;
a plurality of rolling elements disposed between the outer ring and the inner ring;
a cage that holds the plurality of rolling elements;
Equipped with
a restriction portion formed in a flange shape extending radially outward from the outer circumferential surface of the cam;
The regulation department is
having an outer circumferential surface formed in either an elliptical shape or an oval shape having a major axis and a minor axis when viewed from the rotation axis direction,
The long axis of the cam and the long axis of the restriction portion are located on the same straight line, and the short axis of the cam and the short axis of the restriction portion are located on the same straight line,
The cam is formed such that a radial protrusion length from the outer circumferential surface of the cam is uniform over the entire circumference of the outer circumferential surface of the cam,
The outer circumferential surface of the regulating portion faces the retainer in the radial direction with a gap therebetween,
The regulating portion contacts the inner ring of the bearing and regulates movement of the bearing in the direction of the rotation axis.
Wave gear device.
a power generation section that generates rotational force;
A wave gear device having an input section and an output section;
a mating member attached to the output section of the wave gear device;
Equipped with
The input unit receives the rotational force of the power generation unit,
The output section changes the speed of the rotation of the input section and outputs the same;
The wave gear device includes:
internal gear,
an elastic external gear disposed radially inside the internal gear;
a wave generator that contacts the inner circumferential surface of the external gear;
Equipped with
The external gear partially meshes with the internal gear to rotate relative to the internal gear around a rotation axis, and functions as one of the input section and the output section,
The wave generator moves the meshing position of the internal gear and the external gear in a circumferential direction around the rotation axis,
The wave generator is
a cam having a non-circular outer peripheral surface;
a bearing disposed between the inner circumferential surface of the external gear and the outer circumferential surface of the cam;
Equipped with
The cam functions as the other of the input section and the output section,
The bearing is
an outer ring that contacts the inner peripheral surface of the external gear;
an inner ring that contacts the outer peripheral surface of the cam;
a plurality of rolling elements disposed between the outer ring and the inner ring;
a cage that holds the plurality of rolling elements;
Equipped with
a regulating portion that contacts the inner ring of the bearing to avoid contact with the retainer;
The regulating portion is formed such that a radial protrusion length from the outer circumferential surface of the cam is uniform over the entire circumference of the outer circumferential surface of the cam, and the regulating portion is formed such that a protruding length in a radial direction from the outer circumferential surface of the cam is uniform over the entire circumference of the outer circumferential surface of the cam, and the length of the regulating portion is uniform in the radial direction of the outer circumferential surface of the cam. regulating movement to,
industrial robot.