CN219588040U

CN219588040U - Speed reducer and robot

Info

Publication number: CN219588040U
Application number: CN202320082435.XU
Authority: CN
Inventors: 吉田浩伸
Original assignee: Nidec Shimpo Corp
Current assignee: Nidec Drive Technology Corp
Priority date: 2022-01-27
Filing date: 2023-01-28
Publication date: 2023-08-25
Anticipated expiration: 2033-01-28
Also published as: JP2023109509A

Abstract

The utility model provides a speed reducer and a robot. The planetary gear mechanism of the speed reducer has a planetary input shaft, a sun gear, a plurality of planetary gears, a carrier, a planetary side internal gear, and a planetary output shaft. A carrier is fixed with a planetary shaft capable of autorotating and supporting each planetary gear. The planetary output shaft is connected to the carrier or the planetary side internal gear and is rotatable about the first rotation shaft at a first intermediate rotation speed. The wave gear mechanism of the speed reducer has a wave input shaft, a cam, a flexible externally toothed gear, a rigid internally toothed gear, and a wave output shaft. The wave input shaft extends in a hollow cylindrical shape, and rotates with the rotation of the planetary output shaft about the second rotation shaft at a second intermediate rotation speed. The wave output shaft is connected to a flexible externally toothed gear or a rigid internally toothed gear and is rotatable at an output rotational speed. The flexible externally toothed gear and the rigid internally toothed gear are meshed with each other and can rotate relatively by utilizing the difference of the number of teeth. A portion of the planetary output shaft overlaps a portion of the wave input shaft in a second radial direction.

Description

Speed reducer and robot

Technical Field

The present utility model relates to a speed reducer and a robot.

Background

Conventionally, a robot using a speed reducer is known. Such a speed reducer decelerates the rotational movement of the motor and transmits it to the arm of the robot. The arm rotates at a rotation speed reduced by the speed reducer (japanese patent application laid-open No. 2007-085530).

The hollow speed reducer of the above publication is a planetary gear device including a crank shaft, a pinion gear engaged with a crank portion of the crank shaft and eccentrically moved, and a housing having internal teeth formed on an inner peripheral surface thereof for meshing with external teeth of the pinion gear. A hollow hole is formed in the hollow speed reducer by a hollow circular tube. The sun gear is fitted in the outer periphery of the hollow circular tube with a clearance, and the sun gear is rotatably supported by a bearing. In addition, 8 motors are disposed in equal arrangement around the rotation axis of the sun gear in the outer peripheral portion of the hollow speed reducer.

Further, the rotation of each motor is transmitted from the pinion gear to the sun gear, the crank shaft is rotated by the rotation of the sun gear to generate a crank motion, and the housing is rotated at a reduced speed by the planetary motion of the pinion gear fitted to the crank shaft. Thereby, the output member of the robot fixed to the housing of the hollow speed reducer is decelerated. However, in order to obtain a larger reduction ratio, there is room for improvement in the positional relationship between the sun gear and each portion.

Disclosure of Invention

The present utility model aims to provide a technology capable of obtaining a larger reduction ratio by taking effort and effort on the position relation of each part in a speed reducer.

A first aspect is a speed reducer that includes a planetary gear mechanism and a wave gear mechanism, and is capable of decelerating rotation of a planetary input shaft that is an input portion of the planetary gear mechanism and rotating a wave output shaft that is an output portion of the wave gear mechanism, the planetary gear mechanism including: the planetary input shaft is rotatable about a first rotation axis at an input rotation speed; a sun gear fixed to the planetary input shaft and having external teeth formed on an outer surface thereof, the sun gear being rotatable about the first rotation axis at the input rotation speed; a plurality of planetary gears disposed around the sun gear and having external teeth that mesh with external teeth of the sun gear from a first radial outer side around the first rotation axis, the plurality of planetary gears being rotatable with rotation of the sun gear; a carrier to which a plurality of planetary shafts are fixed, the plurality of planetary shafts rotatably supporting the plurality of planetary gears, respectively; a planetary side internal gear which is ring-shaped with the first rotation shaft as a center, and has internal teeth on an inner side surface thereof which mesh with external teeth of the plurality of planetary gears from a first radial outside; and a planetary output shaft disposed along the first rotation axis and connected to either one of the carrier and the planetary side internal gear, the planetary output shaft being rotatable about the first rotation axis at a first intermediate rotation speed, the wave gear mechanism including: a wave input shaft extending in a hollow cylindrical shape along a second rotation shaft, and rotatable about the second rotation shaft at a second intermediate rotation speed in accordance with rotation of the planetary output shaft; a cam rotatable with the wave input shaft; a flexible externally toothed gear capable of deforming according to rotation of the cam; an annular rigid internally toothed gear centered on the second rotation axis; and the wave output shaft is disposed along the second rotation axis, is connected to either one of the flexible externally toothed gear and the rigid internally toothed gear, is rotatable about the second rotation axis at an output rotation speed, is meshed with each other, and is rotatable relative to the rigid internally toothed gear by a difference in number of teeth, wherein a part of the planetary output shaft and a part of the wave input shaft overlap each other in a second radial direction about the second rotation axis.

A second aspect is the speed reducer according to the first aspect, further comprising: a planetary-side transmission gear fixed to the planetary output shaft or integrally formed with the planetary output shaft, and having external teeth formed on an outer surface thereof, the planetary-side transmission gear being rotatable about the first rotation shaft at the first intermediate rotation speed; and a wave side transmission gear fixed to the wave input shaft or integrally formed with the wave input shaft, the wave side transmission gear having external teeth formed on an outer surface thereof and rotatable about the second rotation axis at the second intermediate rotation speed, the external teeth of the wave side transmission gear being connected to the external teeth of the planetary side transmission gear, the wave side transmission gear being rotatable about the wave input shaft at the second rotation axis at the second intermediate rotation speed.

A third aspect is the speed reducer according to the second aspect, wherein the planetary gear mechanism further includes a planetary side housing that houses at least a part of the plurality of planetary gears, the number of teeth of the external teeth of the wave side transmission gear is larger than the number of teeth of the external teeth of the planetary side transmission gear, and the external teeth of the planetary side transmission gear are closer to the first rotation axis than the meshing position of the external teeth of the wave side transmission gear.

A fourth aspect is the speed reducer according to the third aspect, wherein the planetary side internal gear and the planetary side housing are an integral component.

A fifth aspect is the speed reducer according to the first or second aspect, wherein the planetary gear mechanism further includes a planetary side housing that houses at least a part of the plurality of planetary gears, the planetary side internal gear is fixed to an inner side surface of the planetary side housing, and the planetary output shaft is connected to the carrier.

A sixth aspect is the speed reducer according to the first or second aspect, wherein the planetary gear mechanism further includes a planetary side housing that houses at least a part of the plurality of planetary gears, the carrier is fixed to the planetary side housing, and the planetary output shaft is connected to the planetary side internal gear.

A seventh aspect is the speed reducer according to the first or second aspect, wherein the planetary gear mechanism includes a front-stage planetary gear device disposed in a front stage and a rear-stage planetary gear device disposed in a rear stage from the front-stage planetary gear device, and the front-stage planetary gear device includes: a preceding stage planetary input shaft as the planetary input shaft; a front stage sun gear as the sun gear; a plurality of front stage planetary gears as the plurality of planetary gears; a front stage bracket as the bracket; a front-stage planetary side internal gear as the planetary side internal gear; and a front-stage planetary output shaft which is arranged along the first rotation axis, is connected to the front-stage carrier, and is rotatable about the first rotation axis, wherein the rear-stage planetary gear device includes: a rear-stage planetary input shaft fixed to the front-stage planetary output shaft and rotatable about the first rotation shaft; a rear-stage sun gear fixed to the rear-stage planetary input shaft and having external teeth formed on an outer surface thereof, the rear-stage sun gear being rotatable about the first rotation shaft; a plurality of rear-stage planetary gears disposed around the rear-stage sun gear and having external teeth that mesh with external teeth of the rear-stage sun gear from a first radial outer side, the plurality of rear-stage planetary gears rotating in accordance with rotation of the rear-stage sun gear; a rear carrier to which a plurality of rear planetary shafts are fixed, the plurality of rear planetary shafts supporting the plurality of rear planetary gears so as to be rotatable, respectively; a rear-stage planetary-side internal gear having an annular shape centered on the first rotation shaft and having internal teeth on an inner side surface thereof that mesh with external teeth of the plurality of rear-stage planetary gears from a first radial outside; and a rear-stage planetary output shaft disposed along the first rotation axis, connected to the rear-stage carrier, and connected to the planetary output shaft rotatable about the first rotation axis at the first intermediate rotation speed.

An eighth aspect is the speed reducer according to the seventh aspect, wherein the planetary output shaft and the rear-stage planetary output shaft are integral members.

A ninth aspect is the speed reducer according to any one of the second to fourth aspects, characterized in that the number of teeth of the external teeth of the wave side transmission gear is larger than the number of teeth of the external teeth of the planetary side transmission gear, and the external teeth of the planetary side transmission gear are further away from the second rotation shaft than the meshing position of the external teeth of the wave side transmission gear.

A tenth aspect is the speed reducer according to any one of the first to fourth aspects, wherein the wave gear mechanism further includes a wave side housing accommodating at least a part of the flexible externally toothed gear, and a second radial outer end of the wave side housing is further away from the second rotation axis than the first rotation axis.

An eleventh aspect is the speed reducer according to the tenth aspect, wherein the rigid internally toothed gear and the wave side housing are integrally formed.

A twelfth aspect is the speed reducer according to any one of the second to fourth aspects, characterized in that the meshing position of the flexible externally toothed gear and the rigid internally toothed gear is farther from the second rotation axis than the meshing position of the external teeth of the planetary side transmission gear and the external teeth of the wave side transmission gear.

A thirteenth aspect is the speed reducer according to the second aspect, wherein the planetary gear mechanism further includes a planetary side case accommodating at least a part of the plurality of planetary gears, the planetary side case includes a planetary case top surface portion surrounding the planetary output shaft from one axial side, and the planetary case top surface portion and the rigid internal gear are fixed to one axial side from an engagement position of the external teeth of the planetary side transmission gear and the external teeth of the wave side transmission gear, the engagement position being further away from the second rotation axis than an engagement position of the external teeth of the planetary side transmission gear and the external teeth of the wave side transmission gear.

A thirteenth aspect is the speed reducer according to the thirteenth aspect, wherein the planetary gear mechanism further includes a support bearing having an outer ring fixed to the planetary side case, and the wave input shaft is fixed to the inner ring of the support bearing on the other side in the axial direction than a meshing position of the outer teeth of the planetary side transmission gear and the outer teeth of the wave side transmission gear, the meshing position being closer to the second rotation axis than a meshing position of the outer teeth of the planetary side transmission gear and the outer teeth of the wave side transmission gear.

A fifteenth aspect is the speed reducer according to any one of the second to fourth aspects, characterized in that the wave side transmission gear and the wave input shaft are an integral part.

A sixteenth aspect is the speed reducer according to any one of the second to fourth aspects, wherein an outer diameter of the wave side transmission gear is substantially the same as an outer diameter of the wave input shaft.

A seventeenth aspect is the speed reducer according to any one of the first to fourth aspects, wherein the flexible externally toothed gear includes: a cylindrical portion extending in a hollow cylindrical shape along the second rotation axis; and a flange portion that extends outward in the second radial direction from an end portion on one side in the axial direction of the tube portion, the flange portion being fixed to the wave output shaft.

An eighteenth aspect is a robot having the speed reducer according to any one of the first to seventeenth aspects.

According to the present utility model, in a speed reducer or a speed reducer mounted on a robot, a planetary gear mechanism is arranged in a preceding stage, and a wave gear mechanism is arranged in a subsequent stage, whereby the reduction ratio can be increased.

The above and other features, elements, steps, features and advantages of the present utility model will be more clearly understood from the following detailed description of the preferred embodiments of the present utility model with reference to the accompanying drawings.

Drawings

Fig. 1 is a schematic view of a robot.

Fig. 2 is a longitudinal sectional view of the speed reducer.

Fig. 3 is a partial longitudinal sectional view of the speed reducer.

Fig. 4 is a cross-sectional view of a sun gear, a plurality of planet gears, a plurality of planet shafts, and a planet-side internal gear.

Fig. 5 is a cross-sectional view of the planetary side transmission gear and the wave side transmission gear.

Fig. 6 is a partial longitudinal sectional view of the speed reducer.

Fig. 7 is a cross-sectional view schematically showing the wave generator, the flexible externally toothed gear, and the rigid internally toothed gear.

Fig. 8 is a longitudinal sectional view of the motor and the speed reducer according to the second embodiment.

In the figure:

1. 1B, a speed reducer; 3. 3B-planetary gear mechanism; 4. 4b—wave gear mechanism; 7. 7B-planetary side housing; 8-wave side housing; 31. 31B-planetary input shaft; 32. 32B-sun gear; 33. 33B-planetary gear; 34. 34B-planetary shaft; 35. 35B-a bracket; 36. 36B-planetary side internal gear; 37. 37B-planetary output shaft; 38. 38B-planetary side drive gear; 41-a wave input shaft; 42-a wave generator; 43-flexible externally toothed gear; 44-rigid internal tooth gear; 45-wave output shaft; 46—wave side drive gear; 73. 73B-planet housing top portion; 91. 91B-a first rotation axis; 92-a second rotation axis; 93-a rotation shaft; 100-a robot; 103-an electric motor; 321- (sun gear) external teeth; 331- (planetary gear) external teeth; 361- (planetary side internal gear) internal teeth; 381- (planetary side drive gear); 396. 396B-support bearing; 421-cam; 431- (flexible externally toothed gear) barrel; 432- (flex-externally toothed gear) flange portion; 433- (flexible externally toothed gear); 441- (rigid internally toothed gear) internal teeth; 461- (wave side gear) external teeth; p1- (the meshing position of the external teeth of the planetary side transmission gear and the external teeth of the wave side transmission gear); p2- (the top surface of the planetary housing and the rigid internal gear); p3- (the flexible external gear and the rigid internal gear) engaged position; p4- (the fluctuation input shaft and the supporting bearing inner ring).

Detailed Description

Exemplary embodiments of the present application will be described below with reference to the accompanying drawings.

<1 > first embodiment

< 1-1 concerning robot >)

Fig. 1 is a schematic view of a robot 100 equipped with a speed reducer 1 according to an embodiment. The robot 100 is, for example, a so-called industrial robot that performs operations such as transportation, machining, and assembling of components on a manufacturing line of industrial products. As shown in fig. 1, a robot 100 has a speed reducer 1. In the present embodiment, the robot 100 includes a base frame 101, an arm 102, a motor 103, and a speed reducer 1.

The arm 102 is rotatably supported with respect to the base frame 101. The motor 103 and the speed reducer 1 are mounted on the joint portion between the base frame 101 and the arm 102. When a driving current is supplied to the motor 103, a rotational motion is output from the motor 103. The rotational motion output from the motor 103 is decelerated by the speed reducer 1, and transmitted to the arm 102. Thereby, the arm 102 rotates at a speed reduced with respect to the base frame 101. By providing the robot 100 with the speed reducer 1, the speed reducer 1 is provided with the planetary gear mechanism 3 at a front stage and the wave gear mechanism 4 at a rear stage, so that the reduction ratio can be increased. In addition, by making the input portion of the wave gear mechanism 4 a hollow shaft structure, the internal space can be effectively utilized. Further, by disposing a part of the planetary gear mechanism 3 and a part of the wave gear mechanism 4 so as to overlap in the radial direction, the axial length of the speed reducer 1 including them can be reduced.

<1-2 Structure of speed reducer >

Next, the overall structure of the speed reducer 1 will be described.

Hereinafter, a direction parallel to a first rotation axis, which is a central axis of the motor and planetary gear mechanism described later, will be referred to as a "first axial direction", a direction orthogonal to the first rotation axis will be referred to as a "first radial direction", and a direction along an arc centered on the first rotation axis will be referred to as a "first circumferential direction". The direction parallel to a second rotation axis, which is a central axis of the wave gear mechanism described later, is referred to as a "second axial direction", the direction orthogonal to the second rotation axis is referred to as a "second radial direction", and the direction along an arc centered on the second rotation axis is referred to as a "second circumferential direction".

In fig. 2, 3, 6 and 8 described below, the shape and positional relationship of the respective parts will be described below, with the direction of the central axes of the motor, the planetary gear mechanism and the wave gear mechanism being the left-right direction, the left side being the "one axial side", and the right side being the "other axial side". However, the directions of the speed reducer and the robot according to the present utility model are not limited by the definition of the left-right direction. In the present utility model, the "parallel direction" is not limited to the case of being strictly geometrically parallel. The effects of the utility model may be achieved in parallel. In the present utility model, the "orthogonal direction" is not limited to the case of being strictly geometrically orthogonal. The two components may be orthogonal to each other to the extent that the effects of the utility model are exhibited.

Fig. 2 is a longitudinal sectional view of the speed reducer 1. The motor 103 is disposed along a central axis extending in the horizontal direction (left-right direction in fig. 2). The center axis of the motor 103 and the first rotation axis 91, which is the center axis of the speed reducer 1, are aligned with each other. The motor 103 has a stationary portion including a stator and a rotating portion including a rotor. When a driving current is supplied to the stator, the rotating portion including the rotor rotates around the first rotation shaft 91 at the input rotation speed N1, which is the rotation speed before deceleration.

The speed reducer 1 reduces the rotational motion obtained from the motor 103 and transmits the rotational motion to the arm 102. The speed reducer 1 includes a planetary gear mechanism 3 and a wave gear mechanism 4. The speed reducer 1 can reduce the rotation of a planetary input shaft 31, which will be described later, as an input portion of the planetary gear mechanism 3, and can rotate a wave output shaft 45, which will be described later, as an output portion of the wave gear mechanism 4. As described later, the planetary input shaft 31 is connected to a rotating portion of the motor 103. Further, the wave output shaft 45 is connected to the arm 102.

First, the structure of the planetary gear mechanism 3 will be described. Fig. 3 is a partial longitudinal sectional view of the vicinity of the planetary gear mechanism 3 in the speed reducer 1. As shown in fig. 2 and 3, the planetary gear mechanism 3 includes a planetary input shaft 31, a sun gear 32, a plurality of planetary gears 33, a carrier 35, a planetary side internal gear 36, and a planetary output shaft 37. The planetary gear mechanism 3 further includes a planetary side housing 7. In the present embodiment, the planetary gear mechanism 3 has a planetary input shaft 31, a sun gear 32, a plurality of (3 in the present embodiment) planetary gears 33, a plurality of (3 in the present embodiment) planetary shafts 34, a carrier 35, a planetary side internal gear 36, a planetary output shaft 37, a planetary side transmission gear 38, a support bearing 396, and a planetary side housing 7.

The planetary-side housing 7 is a member that houses the planetary input shaft 31, the sun gear 32, the plurality of planetary gears 33, the plurality of planetary shafts 34, the carrier 35, the planetary-side internal gear 36, the planetary output shaft 37, the planetary-side transmission gear 38, and the support bearing 396. Here, the planetary side case 7 may house at least a part of the plurality of planetary gears 33. The planetary side case 7 is immovably and non-rotatably fixed with respect to the base frame 101 of the robot 100. The planetary side case 7 has a planetary first case tube portion 71, a planetary second case tube portion 72, and a planetary case top surface portion 73. That is, the planetary side case 7 has a planetary case top surface portion 73.

The planetary first housing tube 71 and the planetary second housing tube 72 are cylindrical members disposed substantially coaxially with the first rotation shaft 91, respectively. A coupling for connecting the rotating portion of the motor 103 and the planetary input shaft 31 is housed inside the planetary first housing tube 71 in the first radial direction. The planetary first housing tube 71 is located on the other axial side than the planetary second housing tube 72 and the planetary housing top surface 73. Further, a planetary case flange 711 that extends outward in the first radial direction is formed near one end portion of the planetary first case tube 71 in the axial direction.

The planetary second housing tube 72 is adjacent to one side in the axial direction of the planetary first housing tube 71. The planetary input shaft 31, the sun gear 32, the plurality of planetary gears 33, the plurality of planetary shafts 34, the carrier 35, and the planetary side internal gear 36 are housed inside the planetary second housing tube 72 in the first radial direction. The planetary second housing tube 72 is fixed to the first radially outer end of the planetary housing flange 711.

The planetary case top surface 73 is adjacent to one axial side of the planetary second case tube 72. The planetary housing top surface 73 has a planetary third housing barrel 731 and an end surface 732. The planetary third housing cylindrical portion 731 is a portion that extends along the first rotation shaft 91. The planetary output shaft 37 and the planetary side transmission gear 38 are housed inside the planetary third housing tube 731 in the first radial direction. The planetary third housing cylindrical portion 731 extends along the first rotation shaft 91 at the outermost side in the first radial direction in the planetary side housing 7. That is, the planetary third housing barrel 731 is located at the first radial outer end of the planetary side housing 7. The planetary third housing tube 731 is fixed to one axial end of the planetary second housing tube 72 via a first connecting member 723. The end surface portion 732 spreads in a plate shape in the first radial direction. The end surface portion 732 surrounds the planetary output shaft 37 and the planetary transmission gear 38 from one axial side. That is, the planetary housing top surface portion 73 surrounds the planetary output shaft 37 from one side in the axial direction.

The planetary input shaft 31 extends in the first axial direction around the first rotation shaft 91. The planetary input shaft 31 is fixed so as not to rotate relative to the rotating portion of the motor 103. In addition, a bearing 391 is provided between the planetary input shaft 31 and the first radial direction of the planetary first housing tube portion 71. The bearing 391 of the present embodiment uses a ball bearing. The inner ring of the bearing 391 is fixed to the outer side surface of the planetary input shaft 31. An outer ring of the bearing 391 is fixed to an inner side surface of the planetary first housing tube 71. Thereby, the planetary input shaft 31 is rotatably supported together with the rotating portion of the motor 103 via the bearing 391 with respect to the planetary side housing 7 including the planetary first housing tube portion 71. The planetary input shaft 31 is rotatable about the first rotation shaft 91 at the input rotation speed N1.

The sun gear 32 is a gear disposed substantially coaxially with the first rotation shaft 91. The sun gear 32 is fixed around the planetary input shaft 31 so as not to be relatively rotatable. That is, the sun gear 32 is fixed to the planetary input shaft 31. Thus, when the motor 103 is driven, the planetary input shaft 31 and the sun gear 32 rotate around the first rotation shaft 91 at the input rotation speed N1. That is, the sun gear 32 is rotatable about the first rotation shaft 91 at the input rotation speed N1. However, the sun gear 32 and the planetary input shaft 31 may be an integral member.

Fig. 4 is a cross-sectional view of the sun gear 32, the plurality of planetary gears 33, the plurality of planetary shafts 34, and the planetary side internal gear 36 as viewed from the A-A position of fig. 2. In order to avoid complicating the drawing, in fig. 4, hatching showing a cross section is omitted. As shown in fig. 4, a plurality of external teeth 321 are formed on the outer surface of the sun gear 32. That is, the sun gear 32 has external teeth 321 formed on the outer side surface. The plurality of external teeth 321 protrude outward in the first radial direction, respectively. The plurality of external teeth 321 are arranged at regular intervals along the first circumferential direction.

The planetary gear 33 is disposed around the sun gear 32. As shown in fig. 4, in the present embodiment, 3 planetary gears 33 are disposed at equal intervals around the sun gear 32. However, the number of the planetary gears 33 included in the speed reducer 1 may be 2 or 4 or more. The planetary gear 33 is disposed along the rotation shaft 93. The rotation shaft 93 is substantially parallel to the first rotation shaft 91. In addition, the diameter of the planetary gear 33 is substantially constant along the rotation shaft 93. Each planetary gear 33 has a plurality of external teeth 331 on the outer side surface. That is, the plurality of planetary gears 33 have external teeth 331, respectively. In addition, a plurality of external teeth 331 protrude outward, respectively.

In the present embodiment, the diameter of each planetary gear 33 is slightly larger than the diameter of the sun gear 32. In addition, the number of external teeth 331 of one planetary gear 33 is larger than the number of external teeth 321 of the sun gear 32. Then, outer teeth 331 mesh with outer teeth 321 of sun gear 32 from the first radial outside around first rotation shaft 91. As a result, when the sun gear 32 rotates about the first rotation shaft 91, each of the planetary gears 33 receives power from the sun gear 32 and rotates about the rotation shaft 93 in a direction opposite to the rotation direction of the sun gear 32. That is, the plurality of planetary gears 33 can rotate with rotation of the sun gear 32. Further, the 3 planetary gears 33 have through holes 330, respectively. Each through hole 330 penetrates the planetary gear 33 along the rotation shaft 93.

The planetary shaft 34 is a columnar member extending along the rotation shaft 93. In the present embodiment, 3 planetary shafts 34 are provided. Each of the planetary shafts 34 rotatably supports the planetary gear 33. That is, the plurality of planetary shafts 34 rotatably support the plurality of planetary gears 33, respectively. The planetary shaft 34 is inserted into the through hole 330 of the planetary gear 33 in the direction of the rotation shaft 93. In addition, a bearing 392 is interposed between the planetary shaft 34 and the planetary gear 33. The bearing 392 is, for example, a needle bearing. Thus, the planetary gear 33 is rotatably supported about the rotation shaft 93 with respect to the planetary shaft 34.

The bracket 35 has a first bracket portion 351, a second bracket portion 352, and a third bracket portion 353. The first bracket portion 351 extends in a columnar shape along the first rotation shaft 91 on one axial side of the bracket 35. The second bracket portion 352 extends outward in the first radial direction from the end portion on the other axial side of the first bracket portion 351. The third bracket portion 353 further extends from three portions of the second bracket portion 352 in the first circumferential direction on the end surface on the other axial side toward the other axial side. The third carrier portion 353 extends in the first axial direction at a position not overlapping the 3 planetary gears 33 and the 3 planetary shafts 34 in the first circumferential direction. The first bracket portion 351, the second bracket portion 352, and the third bracket portion 353 are integral members. In addition, the carrier 35 and the planetary output shaft 37 are an integral component. Thus, the carrier 35 and the planetary output shaft 37 are coupled to each other so as to be prevented from rotating relative to each other. Here, the carrier 35 and the planetary output shaft 37 may be different members as long as they are coupled so as to be unable to rotate relative to each other.

In addition, a bearing 393 is interposed between the first carrier portion 351 and the first radial direction of the planetary second housing tube portion 72. Ball bearings are used for bearings 393. The inner race of the bearing 393 is fixed to the outer side surface of the first bracket portion 351. The outer race of the bearing 393 is fixed to the inner side surface of the planetary second housing tube 72. In addition, a bearing 394 is interposed between the third carrier portion 353 and the first radial direction of the planetary second housing tube portion 72. Ball bearings are used for bearings 394. An inner ring of the bearing 394 is fixed to an outer side surface of the third bracket portion 353. The outer race of the bearing 394 is fixed to the inner side surface of the planetary second housing barrel 72. Thus, the carrier 35 and the planetary output shaft 37 are rotatably supported about the first rotation shaft 91 via the bearing 393 and the bearing 394 with respect to the planetary side case 7 including the planetary second case tube portion 72.

In addition, the bracket 35 has a plurality of through holes 350. In the present embodiment, the 3 through holes 350 are provided at intervals of approximately 120 degrees in the circumferential direction with respect to the first rotation shaft 91. Each through hole 350 penetrates a portion of the second bracket portion 352 on the first radial outer side along the first rotation shaft 91. Also, 3 planetary shafts 34 are respectively inserted into one through hole 350. In the present embodiment, each of the planetary shafts 34 is fixed to the carrier 35 by adhesion, press fitting, or the like in the through hole 350. That is, 3 planetary shafts 34 are fixed to the carrier 35. The planetary shafts 34 are fixed and supported so as not to rotate relative to the carrier 35. As a result, when the 3 planetary shafts 34 fixed to the carrier 35 and the planetary gears 33 supported by the planetary shafts 34 revolve around the first rotation shaft 91 in the first circumferential direction, the carrier 35 and the planetary output shaft 37 rotate around the first rotation shaft 91.

The planetary side internal gear 36 is disposed substantially coaxially with the first rotation shaft 91. The planetary side internal gear 36 is annular about the first rotation shaft 91. The planetary side internal gear 36 extends radially inward of the planetary second housing tube 72 in a circular ring shape around the first rotation shaft 91. The planetary side internal gear 36 is fixed to the inner surface of the planetary second housing tube 72. That is, the planetary side internal gear 36 is fixed to the inner side surface of the planetary side casing 7. As described above, in the present embodiment, the planetary side internal gear 36 and the planetary side housing 7 are members different from each other. However, the planetary side internal gear 36 and the planetary side housing 7 may be an integral member. This reduces the number of components in the speed reducer 1, and improves mass productivity.

Further, a plurality of internal teeth 361 are formed on the inner surface of the planetary side internal gear 36. That is, the planetary side internal gear 36 has internal teeth 361 on the inner side surface. The plurality of internal teeth 361 protrude inward in the first radial direction. The plurality of internal teeth 361 are arranged at regular intervals in the first circumferential direction. Further, the plurality of internal teeth 361 mesh with the external teeth 331 of each of the 3 planetary gears 33 from the first radial outside. That is, the internal teeth 361 mesh with the external teeth 331 of the plurality of planetary gears 33 from the first radial outside.

The planetary output shaft 37 is disposed along the first rotation shaft 91. The planetary output shaft 37 extends cylindrically along the first rotation shaft 91. As described above, the planetary output shaft 37 and the carrier 35 are an integral component. That is, the planetary output shaft 37 is connected to the carrier 35. The planetary gear mechanism 3 of the present embodiment is a so-called "planetary" reduction mechanism. This reduces the number of components in the speed reducer 1, and improves mass productivity.

When the motor 103 is driven, the planetary input shaft 31 and the sun gear 32 rotate together with the rotating portion of the motor 103 around the first rotation shaft 91 at the input rotation speed N1. The 3 planetary gears 33 engaged with both the sun gear 32 and the planetary side internal gear 36 rotate about the rotation shaft 93. The 3 planetary gears 33 rotate around the rotation shaft 93, and revolve around the first rotation shaft 91 together with the planetary shaft 34 at the first intermediate rotation speed N2 by meshing with the planetary-side internal gear 36. Thus, the carrier 35 to which the 3 planetary shafts 34 are fixed rotates together with the planetary output shaft 37 around the first rotation shaft 91 at the first intermediate rotation speed N2 after deceleration. That is, the planetary output shaft 37 is rotatable about the first rotation shaft 91 at the first intermediate rotation speed N2.

As described above, the speed reducer 1 also has the planetary side transmission gear 38. The planetary side transmission gear 38 is a cylindrical gear disposed substantially coaxially with the first rotation shaft 91. The planetary side transmission gear 38 is fixed to the outer side surface of the planetary output shaft 37 so as not to be rotatable relative to each other. That is, the planetary side transmission gear 38 is fixed to the planetary output shaft 37. Thereby, the planetary-side transmission gear 38 rotates together with the planetary output shaft 37 around the first rotation shaft 91 at the first intermediate rotation speed N2. That is, the planetary-side transmission gear 38 is rotatable about the first rotation shaft 91 at the first intermediate rotation speed N2. However, the planetary side transmission gear 38 and the planetary output shaft 37 may be an integral part.

Fig. 5 is a cross-sectional view of the planetary side transmission gear 38 and a wave side transmission gear 46 described later, as seen from the B-B position of fig. 2. In order to avoid complicating the drawing, in fig. 5, hatching showing a cross section is omitted. As shown in fig. 2 and 5, a plurality of external teeth 381 are formed on the outer surface of the planetary side transmission gear 38. That is, the planetary side transmission gear 38 has external teeth 381 formed on the outer side surface. The plurality of external teeth 381 protrude outward in the first radial direction, respectively. The plurality of external teeth 381 are arranged at a certain pitch in the first circumferential direction.

Next, the configuration of the wave gear mechanism 4 will be described. Fig. 6 is a partial longitudinal sectional view of the vicinity of the wave gear mechanism 4 in the speed reducer 1. As shown in fig. 2 and 6, the second rotation shaft 92, which is the central shaft of the wave gear mechanism 4, is separated from the first rotation shaft 91 and is substantially parallel to the first rotation shaft 91. Here, the first rotation shaft 91 and the second rotation shaft 92 may be in a twisted relationship. The wave gear mechanism 4 has a wave input shaft 41, a cam 421, a flexible externally toothed gear 43, a rigid internally toothed gear 44, and a wave output shaft 45. In addition, the wave gear mechanism 4 has a wave side housing 8. In the present embodiment, the wave gear mechanism 4 has a wave input shaft 41, a wave generator 42, a flexible externally toothed gear 43, a rigid internally toothed gear 44, a wave output shaft 45, an inner race 151, an outer race 152, a wave side transmission gear 46, and a wave side housing 8.

As described above, the speed reducer 1 also has the wave side transmission gear 46. The wave side transmission gear 46 is a cylindrical gear disposed substantially coaxially with the second rotation shaft 92. In the present embodiment, the wave side transmission gear 46 and the wave input shaft 41 are an integral member. Specifically, the wave side transmission gear 46 is formed by projecting a part of the second shaft of the wave input shaft 41 to the second radial outside. Further, the wave side transmission gear 46 protrudes from a part of the wave input shaft 41 in the second axial direction in the entire second circumferential direction to the second radial outside. This can reduce the number of components in the speed reducer 1. However, the wave side transmission gear 46 and the wave input shaft 41 may be different members as long as they are coupled so as not to be rotatable relative to each other. That is, the wave side transmission gear 46 may be fixed to the wave input shaft 41 or may be an integral part of the wave input shaft 41.

Further, the wave side transmission gear 46 may not protrude from the wave input shaft 41 to the second radial outside. That is, the outer diameter of the wave side transmission gear 46 may be substantially the same as the outer diameter of the wave input shaft 41. Thereby, the wave side transmission gear 46 and the wave input shaft 41 can be easily manufactured.

As shown in fig. 5 and 6, a plurality of external teeth 461 are formed on the outer side surface of the wave side transmission gear 46. That is, the wave side transmission gear 46 has external teeth 461 formed on the outer side surface. The plurality of external teeth 461 protrude outward in the second radial direction, respectively. The plurality of external teeth 461 are arranged at regular intervals along the second circumferential direction.

The wave side drive gear 46 is adjacent to the planetary side drive gear 38 in the second radial direction. Then, power is received by the external teeth 461 of the wave side transmission gear 46 meshing with the external teeth 381 of the planetary side transmission gear 38. Thus, when the planetary side transmission gear 38 rotates about the first rotation shaft 91 at the first intermediate rotation speed N2, the wave side transmission gear 46 rotates about the second rotation shaft 92.

Here, as shown in fig. 5, in the present embodiment, the diameter of the wave side transmission gear 46 is sufficiently larger than the diameter of the planetary side transmission gear 38. More specifically, as shown in fig. 2 and 6, the outer teeth 381 of the planetary side transmission gear 38 are closer to the first rotation shaft 91 than the outer side face of the planetary third housing barrel 731 in the planetary side housing 7 is to the meshing position P1 of the outer teeth 461 of the wave side transmission gear 46. That is, the meshing position P1 of the external teeth 381 of the planetary side transmission gear 38 and the external teeth 461 of the wave side transmission gear 46 is closer to the first rotation shaft 91 than the first radial outer end of the planetary side case 7. In addition, the outer teeth 381 of the planetary side transmission gear 38 are further away from the second rotation shaft 92 than the outer ends in the second radial direction of the cam 421 described later, with respect to the meshing position P1 of the outer teeth 461 of the wave side transmission gear 46. Further, the number of teeth of the outer teeth 461 of the wave side transmission gear 46 is larger than the number of teeth of the outer teeth 381 of the planetary side transmission gear 38. In this way, in the present embodiment, by forming the outer diameter of the wave side transmission gear 46 with respect to the outer diameter of the planetary side transmission gear 38 sufficiently large, the number of teeth of the outer teeth 461 of the wave side transmission gear 46 is made larger than the number of teeth of the outer teeth 381 of the planetary side transmission gear 38, and the first intermediate rotation speed N2 of the planetary side transmission gear 38 around the first rotation shaft 91 can be sufficiently reduced. That is, by increasing the outer diameter of the wave side transmission gear 46 with respect to the outer diameter of the planetary side transmission gear 38, a higher reduction ratio can be obtained. As a result, when the planetary side transmission gear 38 rotates at the first intermediate rotational speed N2, the wave side transmission gear 46 rotates at the second intermediate rotational speed N3, and the second intermediate rotational speed N3 is sufficiently decelerated than the first intermediate rotational speed N2. That is, the wave side transmission gear 46 is rotatable with the wave input shaft 41 about the second rotation shaft 92 at the second intermediate rotation speed N3.

The wave side transmission gear 46 and the planetary side transmission gear 38 may be engaged with each other via other power transmission members such as gears. Then, the power can be transmitted from the planetary side transmission gear 38 to the wave side transmission gear 46 through the power transmission member such as the other gear. That is, the external teeth 461 of the wave side transmission gear 46 may be connected to the external teeth 381 of the planetary side transmission gear 38. Thereby, the planetary gear mechanism 3 and the wave gear mechanism 4 can be combined to achieve a high reduction ratio.

The wave input shaft 41 extends in a hollow cylindrical shape along the second rotation shaft 92. As described above, the wave input shaft 41 and the wave side transmission gear 46 cannot relatively rotate. Therefore, when the planetary output shaft 37 and the planetary-side transmission gear 38 rotate about the first rotation shaft 91 at the first intermediate rotation speed N2, the wave input shaft 41 rotates together with the wave-side transmission gear 46 about the second rotation shaft 92 at the second intermediate rotation speed N3. That is, the wave input shaft 41 can rotate at the second intermediate rotation speed N3 around the second rotation shaft 92 as the planetary output shaft 37 rotates. Further, as described above, the wave input shaft 41 extends in a hollow cylindrical shape. Thus, wiring and the like can be provided on the second radial inner side of the wave input shaft 41. That is, in the wave gear mechanism 4, the internal space of the wave input shaft 41 (hollow shaft) can be effectively utilized.

The wave generator 42 is a mechanism for bending and deforming the flexible externally toothed gear 43. The wave generator 42 has a cam 421 and a flexible bearing 422. The cam 421 and the flexible bearing 422 are each expanded annularly about the second rotation shaft 92. Fig. 7 is a cross-sectional view schematically showing the wave generator 42, the flexible externally toothed gear 43, and the rigid internally toothed gear 44 as seen from the C-C position of fig. 2. In order to avoid complicating the drawing, in fig. 7, hatching showing a cross section is omitted.

In the present embodiment, the cam 421 and the wave input shaft 41 are an integral component. Specifically, the cam 421 is formed by a part of the second shaft of the wave input shaft 41 protruding outward in the second radial direction from the wave side transmission gear 46 in one axial direction. Further, the cam 421 protrudes from a part of the wave input shaft 41 in the second axial direction in the entire circumference of the second circumferential direction to the second radial outside. Thereby, the cam 421 and the wave input shaft 41 cannot rotate relative to each other. As a result, when the wave input shaft 41 rotates around the second rotation shaft 92 at the second intermediate rotation speed N3, the cam 421 also rotates around the second rotation shaft 92 at the second intermediate rotation speed N3. That is, the cam 421 can rotate together with the wave input shaft 41. However, the cam 421 and the wave input shaft 41 may be different members from each other as long as they are connected so as to be non-rotatable with respect to rotation.

As shown in fig. 7, the cam 421 has an elliptical cam profile. That is, the outer side surface of the cam 421 is elliptical when viewed in the second axial direction, and has a different outer diameter according to the position in the second circumferential direction. Compliant bearing 422 is a bendable bearing. The flexible bearing 422 is disposed between an outer surface of the cam 421 and an inner surface of a cylinder 431 of the flexible externally toothed gear 43, which will be described later. The cam 421 and the barrel 431 are rotatable at different rotational speeds from each other.

As shown in fig. 6, compliant bearing 422 has an inner race 96, a plurality of balls 97, and an elastically deformable outer race 98. The inner ring 96 contacts the outer side surface of the cam 421. A plurality of balls 97 are interposed between inner race 96 and outer race 98, and are arranged in the circumferential direction. The outer race 98 is elastically deformed (bent deformed) by the inner race 96 and the balls 97 along the cam profile of the rotating cam 421. As described above, the compliant bearing 422 of the present embodiment uses a ball bearing. Here, instead of the ball bearing, another type of bearing such as a roller bearing may be used.

The flexible externally toothed gear 43 is a ring gear that is bendable and deformable. As will be described later, the flexible externally toothed gear 43 is fixed to the arm 102 of the robot 100 via the wave output shaft 45 and the outer race 152. The flexible externally toothed gear 43 is disposed along the second rotation shaft 92. The flexible externally toothed gear 43 has a cylindrical portion 431 and a flange portion 432.

The cylindrical portion 431 extends in a hollow cylindrical shape along the second rotation shaft 92. The cylindrical portion 431 is flexible and is a cylindrical portion that can be bent in the second radial direction. A plurality of external teeth 433 are formed on the outer side surface near the end portion on the other side in the axial direction of the cylindrical portion 431. The plurality of external teeth 433 protrude to the second radial outside, respectively. Further, the plurality of external teeth 433 are arranged at regular intervals along the second circumferential direction. Further, outer race 98 of compliant bearing 422 contacts the inside surface of barrel 431. Thereby, the flexible externally toothed gear 43 can be deformed according to the rotation of the cam 421.

The flange 432 extends from one axial end of the cylindrical portion 431 to the second radial outside. The flange 432 extends in an annular shape around the second rotation shaft 92. In this way, the flange portion 432 expands outward in the second radial direction from the cylindrical portion 431, so that the flexible externally toothed gear 43 can be prevented from interfering with the wave input shaft 41. Further, by disposing the flange portion 432 in the space on the second radial direction outer side than the wave input shaft 41 in this way, the space can be effectively utilized.

The flange 432 is a flat plate-like portion that is more difficult to bend than the tube 431. Further, as shown in fig. 6, a protrusion 434 is formed at a position on the second radial outside of the flange 432. The protrusion 434 is a portion of the second axial wall thickness. A plurality of through holes 430 are formed in the protrusion 434. The plurality of through holes 430 respectively penetrate the protrusions 434 in the second axial direction.

The rigid internally toothed gear 44 is annular about the second rotation shaft 92. In the present embodiment, the rigid internally toothed gear 44 extends in a circular ring shape around the second rotation shaft 92. The other axial end of the tubular portion 431 is disposed on the second radially inner side of the rigid internally toothed gear 44. The rigidity of the rigid internally toothed gear 44 is much higher than that of the cylindrical portion 431. Therefore, the rigid internally toothed gear 44 can be regarded as a rigid body in practice. As shown in fig. 6 and 7, a plurality of internal teeth 441 are formed on the inner side surface of the rigid internal gear 44. The plurality of internal teeth 441 are arranged at regular intervals along the second circumferential direction. The number of teeth 441 of the rigid internally toothed gear 44 is slightly different from the number of teeth 433 of the flexible externally toothed gear 43.

Further, the rigid internally toothed gear 44 is provided with a plurality of through holes 440. The plurality of through holes 440 are arranged at equal intervals in the circumferential direction centering on the second rotation shaft 92. Further, each through hole 440 penetrates the rigid internally toothed gear 44 in the second axial direction. The rigid internally toothed gear 44 is fixed to an end face 732 of the planetary side case 7. Here, as described above, the planetary side case 7 is fixed immovably and unrotatably with respect to the base frame 101 of the robot 100 provided with the speed reducer 1. Thereby, the rigid internally toothed gear 44 is restricted from moving in the second circumferential direction, the second radial direction, and the second axial direction.

As shown in fig. 2, in the present embodiment, the fixed position P2 of the planetary case top surface portion 73 including the above-described end surface portion 732 and the rigid internal gear 44 is farther from the second rotation shaft 92 than the meshing position P1 of the external teeth 381 of the planetary side transmission gear 38 and the external teeth 461 of the wave side transmission gear 46. The fixed position P2 of the planetary case top surface portion 73 including the end surface portion 732 and the rigid internal gear 44 is located on one side in the axial direction than the meshing position P1 of the external teeth 381 of the planetary side transmission gear 38 and the external teeth 461 of the wave side transmission gear 46. That is, in the present embodiment, the planetary case top surface portion 73 and the rigid internal gear 44 are fixed on one side in the axial direction than the meshing position P1 between the external teeth 381 of the planetary side transmission gear 38 and the external teeth 461 of the wave side transmission gear 46, and further away from the second rotation shaft 92 than the meshing position P1 between the external teeth 381 of the planetary side transmission gear 38 and the external teeth 461 of the wave side transmission gear 46.

As described above, outer race 98 of flexible bearing 422 contacts the inner side surface of barrel portion 431 of flexible externally toothed gear 43. Accordingly, the cylindrical portion 431 is deformed into an elliptical shape along the outer side surface of the cam 421. As a result, the external teeth 433 of the flexible externally toothed gear 43 mesh with the internal teeth 441 of the rigid internally toothed gear 44 at 2 positions corresponding to both ends of the major axis of the ellipse. That is, the flexible externally toothed gear 43 and the rigid internally toothed gear 44 are meshed with each other. However, at other positions in the circumferential direction, the external teeth 433 of the flexible externally toothed gear 43 do not mesh with the internal teeth 441 of the rigid internally toothed gear 44.

When the wave input shaft 41 rotates together with the cam 421 about the second rotation shaft 92 at the second intermediate rotation speed N3, the major axis of the ellipse of the flexible externally toothed gear 43 also rotates at the second intermediate rotation speed N3. In this way, the meshing position of the external teeth 433 and the internal teeth 441 also changes in the second circumferential direction at the second intermediate rotational speed N3. In addition, as described above, the number of teeth of the external teeth 433 of the flexible externally toothed gear 43 is slightly different from the number of teeth of the internal teeth 441 of the rigid internally toothed gear 44. With this difference in the number of teeth, the combination of the engagement of the external teeth 433 and the internal teeth 441 slightly changes in the second circumferential direction every one revolution of the cam 421. Here, the rigid internally toothed gear 44 is fixed to the base frame 101 of the robot 100 so as not to rotate. As a result, the flexible externally toothed gear 43 rotates about the second rotation shaft 92 with respect to the rigid internally toothed gear 44 and the base frame 101 at an output rotation speed N4 that is slower than the second intermediate rotation speed N3. That is, the flexible externally toothed gear 43 and the rigid internally toothed gear 44 can rotate relatively due to the difference in the number of teeth.

In the present embodiment, the meshing position P3 between the flexible externally toothed gear 43 and the rigid internally toothed gear 44 is farther from the second rotation shaft 92 than the meshing position P1 between the external teeth 381 of the planetary side transmission gear 38 and the external teeth 461 of the wave side transmission gear 46. By increasing the outer diameter of the flexible externally toothed gear 43 and the inner diameter of the rigid internally toothed gear 44 in this way, the relative rotation between the flexible externally toothed gear 43 and the rigid internally toothed gear 44 can be stabilized.

The inner ring 151 is a member that expands in an annular shape around the second rotation shaft 92. Both the inner race 151 and the outer race 152 have high rigidity. Further, the inner ring 151 is provided with a plurality of screw holes 153. The plurality of screw holes 153 are formed from the end surface of the inner ring 151 on the other axial side toward one axial side. The inner race 151 is fixed to the rigid internally toothed gear 44 by fastening a plurality of screws 154 penetrating the plurality of through holes 440 of the rigid internally toothed gear 44 to a plurality of screw holes 153. Thereby, the inner race 151 is fixed to the base frame 101 of the robot 100 together with the rigid internally toothed gear 44.

An outer ring 152 is disposed radially outward of the second inner ring 151. The outer ring 152 is a member that expands in an annular shape around the second rotation shaft 92. The outer ring 152 is also a part of the surge-side casing 8. The outer race 152 has an inner diameter slightly larger than the outer diameter of the inner race 151. As shown in fig. 2, the outer ring 152 is provided with a plurality of screw holes 155. The plurality of screw holes 155 are formed from the end surface of the outer ring 152 on one side in the axial direction toward the other side in the axial direction.

The outer race 152 is rotatably coupled to the inner race 151 by a bearing 16. The bearing 16 of the present embodiment uses a cross roller bearing. The bearing 16 has a plurality of cylindrical rollers 161 between an outer side surface of the inner ring 151 and an inner side surface of the outer ring 152. The plurality of cylindrical rollers 161 are alternately arranged in a direction changing manner between an annular V-groove provided on the outer surface of the inner ring 151 and an annular V-groove provided on the inner surface of the outer ring 152. Thereby, the inner race 151 and the outer race 152 are connected with high rigidity while allowing the outer race 152 to rotate relative to the inner race 151. Such a crossed roller bearing can obtain sufficient rigidity in the second axial direction and the second radial direction even if a pair of crossed roller bearings is not used like a ball bearing. That is, by using the cross roller bearing, the number of bearings (bearings) provided in the speed reducer 1 can be reduced. Thereby, the weight of the bearing 16 can be reduced, and the axial dimension of the bearing 16 can be suppressed.

The wave output shaft 45 is a member for taking out the power of the speed reducer 1 after the speed reduction. The wave output shaft 45 is arranged along the second rotation axis 92. In the present embodiment, the wave output shaft 45 is substantially annular about the second rotation shaft 92. The wave output shaft 45 has an inner extension 451, a radial extension 452 and an outer extension 453.

The inner extension 451 and the outer extension 453 are cylindrical portions arranged substantially coaxially with the second rotation shaft 92. The inner extension 451 is located on one axial side of the radial extension 452 and the outer extension 453. A bearing 395 is provided between the inner extension 451 and the second radial direction of the wave input shaft 41. The bearing 395 of the present embodiment uses a ball bearing. The inner ring of the bearing 395 is fixed to the outer side surface of the wave input shaft 41. The outer race of bearing 395 is secured to the inner side of inner extension 451. Thereby, the wave output shaft 45 including the inner extension 451 is supported relative to the wave input shaft 41 via the bearing 395 so as to be rotatable about the second rotation shaft 92.

The radially extending portion 452 extends from the axially opposite end portion of the inner extending portion 451 to the second radially outer side. A plurality of through holes 450 are provided in the radial extension 452. Each through-hole 450 extends through the radial extension 452 in the second axial direction. The radially extending portion 452 is fixed to the flexible externally toothed gear 43 and the outer ring 152 by fastening a plurality of screws 156 penetrating the plurality of through holes 450 and the plurality of through holes 430 of the flexible externally toothed gear 43 to a plurality of screw holes 155 of the outer ring 152. Thus, the flange portion 432 of the flexible externally toothed gear 43 is fixed to the wave output shaft 45. As a result, the wave output shaft 45, the flexible externally toothed gear 43, and the outer race 152 are supported relative to the wave input shaft 41 so as to be rotatable about the second rotation shaft 92 via the bearing 395.

The outer extension 453 extends from the second radially outer end of the radial extension 452 toward the other axial side. The outer extension 453 is also a part of the wave side case 8.

The wave side housing 8 accommodates the wave input shaft 41, the wave generator 42, the flexible externally toothed gear 43, the rigid internally toothed gear 44, a part of the wave output shaft 45, the inner race 151, and the outer race 152. Here, the wave side case 8 may house at least a part of the flexible externally toothed gear 43. The surge-side casing 8 has the outer ring 152, the outer extending portion 453, the surge-casing tube portion 81, the first surge-casing fixing portion 82, and the second surge-casing fixing portion 83.

The outer extension 453 is expanded along the second rotation axis 92 at the second radially outermost side in the wave-side housing 8. That is, the outer extension 453 is located at the second radially outer end of the wave-side shell 8. Further, the outer side surface of the outer extension 453 is farther from the second rotation axis 92 than the first rotation axis 91 is from the second rotation axis 92. That is, the second radial outer end of the wave side housing 8 is farther from the second rotation shaft 92 than the first rotation shaft 91. In the present embodiment, by disposing the planetary gear mechanism 3 and the wave gear mechanism 4 close to each other in this way, space saving of the entire speed reducer 1 can be achieved.

The wave housing cylinder 81 extends along the second rotation axis 92. The wave housing barrel 81 is located between the first wave housing fixing part 82 and the second shaft of the second wave housing fixing part 83. The first surge housing fixing portion 82 extends outward in the second radial direction from one axial end portion of the surge housing tube portion 81. One or more through holes 820 are provided in the first wave housing fixing part 82. Each through hole 820 penetrates the first wave housing fixing part 82 in the second axis direction. The wave side case 8 including the first wave case fixing portion 82 is fixed to the rigid internally toothed gear 44 and the inner ring 151 by fastening the screw 84 penetrating the through hole 820 and the through hole 440 of the rigid internally toothed gear 44 to the screw hole 153 of the inner ring 151.

Thereby, the wave side case 8 is fixed to the base frame 101 of the robot 100 together with the rigid internally toothed gear 44 and the inner race 151. However, the rigid internally toothed gear 44 and the wave side case 8 may be an integral member. This reduces the number of components in the speed reducer 1, and improves mass productivity.

The second surge housing fixing portion 83 extends from the end portion on the other axial side of the surge housing tube portion 81 toward the second radial inner side. A support bearing 396 is provided between the second wave housing fixing portion 83 and the second radial direction of the wave input shaft 41. As described above, the support bearing 396 is also a constituent element of the planetary gear mechanism 3. The support bearing 396 of the present embodiment uses a ball bearing. The inner ring of the support bearing 396 is fixed to the outer side surface of the wave input shaft 41. A part of the outer ring of the support bearing 396 in the second circumferential direction is fixed to the inner side surface of the second wave housing fixing portion 83. As a result, the wave input shaft 41 is supported by the wave side housing 8 including the second wave housing fixing portion 83, the rigid internally toothed gear 44, and the inner ring 151 so as to be rotatable about the second rotation shaft 92 via the support bearing 396. The outer ring of the support bearing 396 is fixed to the planetary second housing tube 72 via the second coupling member 724 at the other portion in the second circumferential direction. That is, the outer ring of the support bearing 396 is fixed to the planetary side case 7.

As described above, the wave output shaft 45 is supported, together with the flexible externally toothed gear 43 and the outer race 152, so as to be rotatable relative to the wave input shaft 41 about the second rotation shaft 92 via the bearing 395. In addition, the flexible externally toothed gear 43 is fixed to the arm 102 of the robot 100. Thus, the wave output shaft 45, the flexible externally toothed gear 43, the outer race 152, and the arm 102 of the robot 100 can rotate about the second rotation shaft 92 with respect to the base frame 101 to which the rigid internally toothed gear 44 is fixed. As a result, when the wave input shaft 41 rotates together with the cam 421 about the second rotation shaft 92 at the second intermediate rotation speed N3, the wave output shaft 45, the flexible externally toothed gear 43, and the outer race 152 and the arm 102 of the robot 100 rotate about the second rotation shaft 92 at the output rotation speed N4.

As shown in fig. 2, in the present embodiment, the meshing position P1 of the external teeth 381 of the planetary side transmission gear 38 and the external teeth 461 of the wave side transmission gear 46 is closer to the second rotation shaft 92 than the fixed position P4 of the inner race of the support bearing 396. The meshing position P1 between the external teeth 381 of the planetary transmission gear 38 and the external teeth 461 of the wave transmission gear 46 is located on the other side in the axial direction than the fixed position P4 of the inner race of the support bearing 396. That is, in the present embodiment, the wave input shaft 41 is fixed to the inner ring of the support bearing 396 on the other side in the axial direction than the meshing position P1 between the outer teeth 381 of the planetary transmission gear 38 and the outer teeth 461 of the wave transmission gear 46, and the meshing position P1 between the outer teeth 381 of the planetary transmission gear 38 and the outer teeth 461 of the wave transmission gear 46.

That is, in the present embodiment, the planetary gear mechanism 3 and the wave gear mechanism 4 are fixed to the fixed position P2 on one side in the axial direction and the fixed position P4 on the other side in the axial direction, respectively, with respect to the meshing position P1 between the external teeth 381 of the planetary side transmission gear 38 and the external teeth 461 of the wave side transmission gear 46. In this way, by fixing the planetary gear mechanism 3 and the wave gear mechanism 4 to the one side and the other side in the axial direction with respect to the meshing position P1 of the external teeth 381 of the planetary side transmission gear 38 and the external teeth 461 of the wave side transmission gear 46, it is possible to fix them more firmly.

In the present embodiment, in the speed reducer 1, the planetary gear mechanism 3 and the wave gear mechanism 4 are disposed close to each other so that a part of the planetary output shaft 37 of the planetary gear mechanism 3 in the first axial direction overlaps a part of the wave input shaft 41 of the wave gear mechanism 4 in the first radial direction and the second radial direction. That is, in the present embodiment, a part of the planetary output shaft 37 and a part of the wave input shaft 41 overlap in the second radial direction centering on the second rotation shaft 92. In this way, by disposing a part of the planetary gear mechanism 3 and a part of the wave gear mechanism 4 so as to overlap in the radial direction, the axial length of the speed reducer 1 including them can be reduced.

In the present embodiment, the rotation of the input rotation speed N1 by the rotation portion of the motor 103 is decelerated by the planetary gear mechanism 3 of the preceding stage, and then further decelerated by the wave gear mechanism 4 of the subsequent stage in the speed reducer 1. In this way, in the present embodiment, by disposing the wave gear mechanism 4 at the rear stage, the reduction ratio can be increased.

<2 > second embodiment

Next, a configuration of a speed reducer 1B mounted on a robot according to a second embodiment of the present utility model will be described. Note that, the following description will be mainly made regarding differences from the speed reducer 1 of the first embodiment, and the same portions as those of the first embodiment will be omitted. Fig. 8 is a longitudinal sectional view of the speed reducer 1B according to the second embodiment.

The speed reducer 1B includes a planetary gear mechanism 3B and a wave gear mechanism 4B. The wave gear mechanism 4B of the present embodiment has the same structure as the wave gear mechanism 4 of the first embodiment.

As shown in fig. 8, the planetary gear mechanism 3B includes a planetary input shaft 31B, a sun gear 32B, a plurality of planetary gears 33B, a plurality of planetary shafts 34B, a carrier 35B, a planetary side internal gear 36B, a planetary output shaft 37B, a planetary side transmission gear 38B, a support bearing 396B, and a planetary side housing 7B. The planetary input shaft 31B, the sun gear 32B, the plurality of planetary gears 33B, the plurality of planetary shafts 34B, the planetary side transmission gear 38B, and the support bearing 396B of the present embodiment have the same configuration as the planetary input shaft 31, the sun gear 32, the plurality of planetary gears 33, the plurality of planetary shafts 34, the planetary side transmission gear 38, and the support bearing 396 of the first embodiment, and therefore, duplicate description is omitted.

Unlike the planetary side case 7 of the first embodiment, the planetary side case 7B of the present embodiment does not have a portion corresponding to the planetary second case tube 72. The plurality of planetary gears 33B of the present embodiment are arranged on the first radial inner side of the planetary case top surface portion 73B. The bracket 35B of the present embodiment is fixed to the planetary housing top surface 73B by screws. That is, the carrier 35B is fixed to the planetary side case 7B.

The planetary side internal gear 36B is disposed substantially coaxially with the first rotation shaft 91B. The inner teeth of the planetary side inner gear 36B mesh with the outer teeth of the plurality of planetary gears 33B from the first radial outside. The planetary output shaft 37B is a member extending cylindrically along the first rotation shaft 91B. In the present embodiment, the planetary output shaft 37B and the planetary side internal gear 36B are an integral member. That is, the planetary output shaft 37B is connected to the planetary side internal gear 36B. The planetary gear mechanism 3B of the present embodiment is a so-called "star". By adopting such a configuration, the axial length of the planetary gear mechanism 3B can be suppressed. That is, in the present utility model, the planetary output shaft 37B may be connected to either the carrier 35B or the planetary side internal gear 36B.

Between the carrier 35B and the first radial direction of the planetary output shaft 37B, 2 bearings 397B are interposed. The 2 bearings 397B are arranged adjacent to each other in the first axial direction. The ball bearing is used as the bearing 397B of the present embodiment. The inner race of the bearing 397B is fixed to the outer side surface of the bracket 35B. An outer ring of the bearing 397B is fixed to an inner side surface of the planetary output shaft 37B. Accordingly, the planetary output shaft 37B and the planetary side internal gear 36B are rotatably supported with respect to the carrier 35B and the planetary side casing 7B about the first rotation shaft 91B via the bearing 397B.

When the motor 103 is driven, the planetary input shaft 31B and the sun gear 32B rotate about the first rotation shaft 91B at the input rotation speed N1. The plurality of planetary gears 33B engaged with both the sun gear 32B and the planetary-side internal gear 36B rotate on their own axes. However, the plurality of planetary gears 33B are fixed to the carrier 35B via the planetary shafts 34B, and as described above, the carrier 35B is fixed to the planetary side case 7B, and therefore does not rotate. Therefore, the planetary-side internal gear 36B rotates with the planetary output shaft 37B at the first intermediate rotation speed N2 after deceleration about the first rotation shaft 91B by meshing with the plurality of planetary gears 33B.

<3 > modification example

The exemplary embodiments of the present utility model have been described above, but the present utility model is not limited to the above-described embodiments.

In the wave gear mechanism 4 described above, the flexible externally toothed gear 43 is fixed to the wave output shaft 45 and the arm 102 of the robot 100, and the rigid internally toothed gear 44 is fixed to the base frame 101 of the robot 100 so as not to be movable and rotatable. However, the flexible externally toothed gear 43 may be immovably and non-rotatably fixed with respect to the base frame 101 of the robot 100, and the rigid internally toothed gear 44 may be fixed with respect to the wave output shaft 45 and the arm 102 of the robot 100. Further, the rigid internally toothed gear 44 may be rotated with respect to the flexible externally toothed gear 43 by meshing the external teeth 433 of the flexible externally toothed gear 43 with the internal teeth 441 of the rigid internally toothed gear 44. That is, the wave output shaft 45 may be connected to either the flexible externally toothed gear 43 or the rigid internally toothed gear 44, and may rotate around the second rotation shaft 92 at the output rotation speed N4.

The planetary gear mechanism used in the speed reducer may be a multistage type. In this case, for example, the planetary gear mechanism may include a front-stage planetary gear device disposed in a front stage and a rear-stage planetary gear device disposed in a rear stage from the front-stage planetary gear device. The front-stage planetary gear device may include a front-stage planetary input shaft as the planetary input shaft of the above embodiment, a front-stage sun gear as the sun gear of the above embodiment, a plurality of front-stage planetary gears as the plurality of planetary gears of the above embodiment, a front-stage gear as the carrier of the above embodiment, a front-stage planetary side internal gear as the planetary side internal gear of the above embodiment, and a front-stage planetary output shaft. The front-stage planetary output shaft may be an output shaft which is disposed along the first rotation axis, is connected to the front-stage carrier, and is rotatable about the first rotation axis.

The rear-stage planetary gear device may include a rear-stage planetary input shaft, a rear-stage sun gear, a plurality of rear-stage planetary gears, a rear-stage carrier, rear-stage planetary side internal gear, and a rear-stage planetary output shaft. The rear-stage planetary input shaft may be fixed to the front-stage planetary output shaft and rotatable about the first rotation shaft. The rear sun gear may be fixed to the rear planetary input shaft, have external teeth formed on the outer surface, and be rotatable about the first rotation axis. The plurality of rear-stage planetary gears may be arranged around the rear-stage sun gear, have external teeth that mesh with external teeth of the rear-stage sun gear from the first radial outside, and rotate as the rear-stage sun gear rotates. Further, a plurality of rear stage planetary shafts that rotatably support a plurality of rear stage planetary gears, respectively, may be fixed to the rear stage carrier. The rear-stage planetary-side internal gear may be annular about the first rotation axis, and the inner surface may have internal teeth that mesh with external teeth of the plurality of rear-stage planetary gears from the first radial outside. The rear-stage planetary output shaft may be disposed along the first rotation axis, connected to the rear-stage carrier, and connected to the planetary output shaft of the above embodiment rotatable about the first rotation axis at the first intermediate rotation speed N2. In this way, by using a multistage planetary gear mechanism, a higher reduction ratio can be obtained.

In the multistage planetary gear mechanism, the planetary output shaft and the rear-stage planetary output shaft of the above embodiment may be an integral component. By integrating the planetary output shaft and the rear-stage planetary output shaft into an integral component, the number of components can be reduced, and mass productivity can be improved.

The shape of the specific portion of the speed reducer and the robot may be different from the shape shown in the drawings of the above embodiment.

The present application is applicable to, for example, a speed reducer and a robot.

Claims

1. A speed reducer comprising a planetary gear mechanism and a wave gear mechanism, capable of decelerating rotation of a planetary input shaft as an input part of the planetary gear mechanism and rotating a wave output shaft as an output part of the wave gear mechanism,

the planetary gear mechanism has:

the planetary input shaft is rotatable about a first rotation axis at an input rotation speed;

a sun gear fixed to the planetary input shaft and having external teeth formed on an outer surface thereof, the sun gear being rotatable about the first rotation axis at the input rotation speed;

a plurality of planetary gears disposed around the sun gear and having external teeth that mesh with external teeth of the sun gear from a first radial outer side around the first rotation axis, the plurality of planetary gears being rotatable with rotation of the sun gear;

A carrier to which a plurality of planetary shafts are fixed, the plurality of planetary shafts rotatably supporting the plurality of planetary gears, respectively;

a planetary side internal gear which is ring-shaped with the first rotation shaft as a center, and has internal teeth on an inner side surface thereof which mesh with external teeth of the plurality of planetary gears from a first radial outside; and

a planetary output shaft which is disposed along the first rotation axis and is connected to either one of the carrier and the planetary side internal gear and is rotatable about the first rotation axis at a first intermediate rotation speed,

the wave gear mechanism has:

a wave input shaft extending in a hollow cylindrical shape along a second rotation shaft, and rotatable about the second rotation shaft at a second intermediate rotation speed in accordance with rotation of the planetary output shaft;

a cam rotatable with the wave input shaft;

a flexible externally toothed gear capable of deforming according to rotation of the cam;

an annular rigid internally toothed gear centered on the second rotation axis; and

the wave output shaft is disposed along the second rotation axis, is connected to one of the flexible externally toothed gear and the rigid internally toothed gear, and is rotatable about the second rotation axis at an output rotation speed,

The flexible externally toothed gear and the rigid internally toothed gear are meshed with each other, the flexible externally toothed gear and the rigid internally toothed gear can relatively rotate by utilizing the difference of the number of teeth,

it is characterized in that the method comprises the steps of,

a portion of the planetary output shaft and a portion of the wave input shaft overlap in a second radial direction centered on the second rotation axis.

2. The speed reducer according to claim 1, wherein,

the device also comprises:

a planetary-side transmission gear fixed to the planetary output shaft or integrally formed with the planetary output shaft, and having external teeth formed on an outer surface thereof, the planetary-side transmission gear being rotatable about the first rotation shaft at the first intermediate rotation speed; and

a wave side transmission gear fixed to the wave input shaft or integrally formed with the wave input shaft, having external teeth formed on an outer surface thereof, rotatable about the second rotation axis at the second intermediate rotation speed,

the external teeth of the wave side transmission gear are connected to the external teeth of the planetary side transmission gear, and the wave side transmission gear is rotatable together with the wave input shaft about the second rotation shaft at the second intermediate rotation speed.

3. The speed reducer according to claim 2, wherein,

the planetary gear mechanism further has a planetary side housing accommodating at least a portion of the plurality of planetary gears,

the number of teeth of the external teeth of the wave side transmission gear is larger than that of the external teeth of the planetary side transmission gear,

the meshing position of the external teeth of the planetary side transmission gear and the external teeth of the wave side transmission gear is closer to the first rotation shaft than the first radial outer end of the planetary side housing.

4. The speed reducer according to claim 3, wherein,

the planetary side internal gear and the planetary side housing are an integral component.

5. The speed reducer according to claim 1 or 2, wherein,

the planetary side internal gear is fixed on the inner side surface of the planetary side shell,

the planetary output shaft is connected with the carrier.

6. The speed reducer according to claim 1 or 2, wherein,

the carrier is fixed to the planetary side housing,

The planetary output shaft is connected with the planetary side internal gear.

7. The speed reducer according to claim 1 or 2, wherein,

the planetary gear mechanism has a front stage planetary gear device arranged in a front stage and a rear stage planetary gear device arranged in a rear stage of the front stage planetary gear device,

the front stage planetary gear device has:

a preceding stage planetary input shaft as the planetary input shaft;

a front stage sun gear as the sun gear;

a plurality of front stage planetary gears as the plurality of planetary gears;

a front stage bracket as the bracket;

a front-stage planetary side internal gear as the planetary side internal gear; and

a front-stage planetary output shaft which is arranged along the first rotation axis, is connected to the front-stage carrier, is rotatable about the first rotation axis,

the rear-stage planetary gear device has:

a rear-stage planetary input shaft fixed to the front-stage planetary output shaft and rotatable about the first rotation shaft;

a rear-stage sun gear fixed to the rear-stage planetary input shaft and having external teeth formed on an outer surface thereof, the rear-stage sun gear being rotatable about the first rotation shaft;

A plurality of rear-stage planetary gears disposed around the rear-stage sun gear and having external teeth that mesh with external teeth of the rear-stage sun gear from a first radial outer side, the plurality of rear-stage planetary gears rotating in accordance with rotation of the rear-stage sun gear;

a rear carrier to which a plurality of rear planetary shafts are fixed, the plurality of rear planetary shafts supporting the plurality of rear planetary gears so as to be rotatable, respectively;

a rear-stage planetary-side internal gear having an annular shape centered on the first rotation shaft and having internal teeth on an inner side surface thereof that mesh with external teeth of the plurality of rear-stage planetary gears from a first radial outside; and

and a rear-stage planetary output shaft disposed along the first rotation axis, connected to the rear-stage carrier, and connected to the planetary output shaft rotatable about the first rotation axis at the first intermediate rotation speed.

8. The speed reducer according to claim 7, wherein,

the planetary output shaft and the rear stage planetary output shaft are an integral component.

9. The speed reducer according to any one of claims 2 to 4,

The meshing position of the external teeth of the planetary side transmission gear and the external teeth of the wave side transmission gear is farther from the second rotation shaft than the second radial outer end of the cam.

10. The speed reducer according to any one of claims 1 to 4,

the wave gear mechanism also has a wave side housing that houses at least a portion of the flexible externally toothed gear,

the second radially outer end of the wave side housing is further from the second rotational axis than the first rotational axis.

11. The speed reducer according to claim 10, wherein,

the rigid internally toothed gear and the wave side housing are an integral component.

12. The speed reducer according to any one of claims 2 to 4,

the meshing position of the flexible externally toothed gear and the rigid internally toothed gear is farther from the second rotation axis than the meshing position of the external teeth of the planetary side transmission gear and the external teeth of the wave side transmission gear.

13. The speed reducer according to claim 2, wherein,

the planetary side housing has a planetary housing top surface portion surrounding the planetary output shaft from one axial side,

The planetary case top surface portion and the rigid internal gear are fixed on one axial side than the meshing position of the external teeth of the planetary side transmission gear and the external teeth of the wave side transmission gear, which is farther from the second rotation shaft.

14. The speed reducer according to claim 13, wherein,

the planetary gear mechanism further has a support bearing whose outer ring is fixed to the planetary side housing,

the wave input shaft is fixed to the inner ring of the support bearing on the other side in the axial direction than the meshing position of the external teeth of the planetary side transmission gear and the external teeth of the wave side transmission gear, and the meshing position of the external teeth of the planetary side transmission gear and the external teeth of the wave side transmission gear is closer to the second rotation shaft.

15. The speed reducer according to any one of claims 2 to 4,

the wave side transmission gear and the wave input shaft are an integral component.

16. The speed reducer according to any one of claims 2 to 4,

the outside diameter of the wave side transmission gear is substantially the same as the outside diameter of the wave input shaft.

17. The speed reducer according to any one of claims 1 to 4,

the flexible externally toothed gear has:

a cylindrical portion extending in a hollow cylindrical shape along the second rotation axis; and

a flange portion extending from an end portion of one axial side of the tube portion toward a second radial outside,

the flange portion is fixed to the wave output shaft.

18. A robot is characterized in that,

a speed reducer according to any one of claims 1 to 17.