TWI715033B - Wave gear device - Google Patents

Abstract

The wave gear device has an internal rigid internal gear with internal teeth, a wave generator and a flexible external gear. The wave generator rotates around the central axis and has a different outer diameter according to the position in the circumferential direction. The flexible external gear has external teeth on the outer peripheral surface that are partially engaged with the internal teeth of the rigid internal gear. The inner peripheral surface is pushed along with the rotation of the wave generator, thereby making the position of the internal teeth and the external teeth meshed While moving in the circumferential direction, it rotates relative to the rigid internal gear according to the number of teeth of the internal teeth and external teeth. The wave generator is fixed to the input part that rotates around the central axis. The position where the internal teeth and external teeth of the flexible externally toothed gear engage in the circumferential direction is inclined in the direction of reducing the diameter toward the other end of the flexible externally toothed gear. The rigid internally toothed gear is arranged to be able to adjust the position relative to the input part. Axial position. There is no need to reduce the tooth height of the internal teeth and the external teeth, and the gap between the internal teeth and the external teeth can be adjusted.

Description

Wave gear device

The invention relates to a wave gear device.

In the past, a wave gear device is known, which includes a rigid internal gear and a flexible external gear. This wave gear device is mainly used as a reducer. The conventional wave gear device is disclosed in, for example, Japanese Patent Laid-Open No. 2011-7206. The wave gear device disclosed in Japanese Patent Laid-Open No. 2011-7206 has a wave generator in addition to a circular spline (rigid internal gear) and a flex spline (flexible external gear) (Wave generator) (wave generator). Internal teeth are formed on the inner peripheral surface of the rigid gear. External teeth are formed on the outer peripheral surface of the flexible gear. The wave generator deflects the flexible gear into an elliptical shape, so that the external teeth are partially engaged with the internal teeth, and the biting position is moved in the circumferential direction.

Furthermore, in the wave gear device disclosed in Japanese Patent Application Laid-Open No. 2011-7206, the amount of deflection in the radial direction at the position of the major axis of the elliptical flexible gear gradually increases toward the open end. Therefore, for the internal teeth of the rigid gear and the external teeth of the flexible gear, respectively, a tapered (taper) surface is formed in the tooth top surface portion in such a manner that the tooth height gradually decreases toward the open end. In this way, the gap between the internal teeth and the external teeth is adjusted, and the phenomenon that the internal teeth and the external teeth interfere with each other in the engaged state is suppressed. Patent Document 1: Japanese Patent Laid-Open No. 2011-7206

[The problem to be solved by the invention] In Japanese Patent Laid-Open No. 2011-7206, it is disclosed that in the manufacturing stage of rigid gears and flexible gears, taper processing is performed on the parts of the tooth surfaces that become internal and external teeth, and then gear cutting (linear processing) ) To form internal and external teeth with tapered surfaces. However, since the inner teeth and the outer teeth are tapered to gradually reduce the tooth height, the strength of the inner teeth and the outer teeth may decrease, and the efficiency of rotation transmission from the outer teeth to the inner teeth may decrease. In addition, it is difficult to ensure high accuracy in the gap between the internal teeth and the external teeth after assembling a wave gear device including a rigid gear and a flexible gear, and the cost may increase.

The purpose of the present invention is to provide a technology that does not need to reduce the tooth heights of the internal and external teeth, and can measure the gap between the internal and external teeth after assembling a wave gear device including a rigid internal gear and a flexible external gear. Adjustment.

[Technical means to solve the problem] The exemplary first invention of the present application is a wave gear device, which includes: a rigid internally toothed gear having internal teeth on the inner peripheral surface and expanding in an annular shape with a central axis as the center; a wave generator, in the The radially inner side of the rigid internally toothed gear rotates around the central axis and has different outer diameters according to the position in the circumferential direction; and the flexible externally toothed gear has an outer peripheral surface that is opposite to the rigid internally toothed gear The internal teeth of the external teeth partially mesh with each other, and the inner peripheral surface is pushed along with the rotation of the wave generator, thereby moving the biting position of the internal teeth and the external teeth in the circumferential direction while moving according to the The internal teeth and the external teeth have different numbers of teeth and rotate relative to the rigid internal gear, wherein the wave generator is fixed to an input portion that rotates around the central axis, and the flexible outer The toothed gear has: a flexible cylindrical body portion having the external teeth at one end portion and extending in a cylindrical shape in the axial direction with the central axis as the center; and a flat plate portion from the other end of the flexible cylindrical body portion The portion expands in the radial direction, and the position where the inner teeth and the outer teeth of the flexible cylindrical main body part in the circumferential direction are engaged with each other to decrease in diameter toward the other end of the flexible cylindrical main body The direction is inclined, and the rigid internally toothed gear is configured to be able to adjust an axial position relative to the input part.

[Effects of the invention] According to the viewpoint of the present invention, a rigid internal gear with internal teeth is arranged such that its axial position can be adjusted relative to the input portion to which the wave generator is fixed, and the wave generator pushes the inner portion of the flexible cylindrical body portion with external teeth. And rotate around the surface. Therefore, it is not necessary to reduce the tooth heights of the internal teeth and the external teeth, and the gap between the internal teeth and the external teeth can be adjusted after the wave gear device including the rigid internal gear and the flexible external gear is assembled.

Hereinafter, exemplary embodiments of the present application will be described with reference to the drawings. In addition, in this application, the direction parallel to the central axis of the wave gear device described later is referred to as the "axial direction", and the direction orthogonal to the central axis of the wave gear device is referred to as the "radial direction". The direction of the arc centered on the central axis of the wave gear device is called the "circumferential direction". In addition, in the present application, in Fig. 1, Fig. 3, Fig. 4, Fig. 5, Fig. 7, Fig. 8, and Fig. 9 described later, the axial direction is referred to as the left and right direction, and the right side (right end) is referred to as the “axial direction”. One side (one end) of ", the left side (left end) is referred to as "the other side in the axial direction (the other end)", and the shape or positional relationship of each part will be described. However, it is not intended to limit the direction when the wave gear device of the present invention is used by the definition of the left-right direction. In addition, in the present application, the term "parallel direction" also includes substantially parallel directions. In addition, in the present application, the "orthogonal direction" also includes a substantially orthogonal direction.

<1. The first embodiment> <1-1. Structure of wave gear device> Hereinafter, the structure of the wave gear device 100 according to the first embodiment of the present invention will be described. FIG. 1 is a longitudinal sectional view of a wave gear device 100 according to the first embodiment. Fig. 2 is a cross-sectional view of the wave gear device 100 when viewed from the position A-A in Fig. 1. In addition, in Fig. 1 and Figs. 3, 4, 8 and 9 described later, the inclination of the outer circumferential surface of the outer ring 323 of the wave bearing 32 described later is exaggeratedly shown.

The wave gear device 100 of the present embodiment is a device that uses differential motion between a rigid internally toothed gear 10 described later and a flexible externally toothed gear 20 described later to shift the input rotational motion. The wave gear device 100 is, for example, incorporated in a joint of a small robot (robot), and is used as a speed reducer for decelerating and outputting a rotational motion obtained from a motor. However, the wave gear device 100 of the present invention can also be incorporated into other equipment such as wearable robots (assist suites), turntables, index plates of machine tools, wheelchairs, unmanned guided vehicles, etc., to realize various rotational motions.

As shown in FIGS. 1 and 2, the wave gear device 100 includes a rigid internal gear 10, a flexible external gear 20, a wave generator 30 and a flange portion 40. Furthermore, in the wave gear device 100, an input unit 101 for obtaining power from the outside is provided. The input portion 101 extends in a cylindrical shape in the axial direction with the center axis 9 as the center. In addition, the input unit 101 rotates around the central axis 9. As described in detail later, the input unit 101 is axially supported by the wave gear device 100.

The rigid internal gear 10 is a member that expands in an annular shape with the center shaft 9 as the center. The rigidity of the rigid internally toothed gear 10 is much higher than the rigidity of the flexible cylindrical main body 25 described later. Therefore, the rigid internal gear 10 can be regarded as a rigid body substantially. As shown in FIG. 2, the rigid internally toothed gear 10 has a plurality of internal teeth 11 on the inner peripheral surface. The plurality of internal teeth 11 are arranged at a constant pitch along the circumferential direction. The plurality of internal teeth 11 of the present embodiment are formed with bevel gears inclined with respect to the central axis 9. The rigid internally toothed gear 10 is provided with a plurality of (eight in this embodiment) through holes 102 for inserting screws 13 described later. The plurality of through holes 102 are arranged at equal intervals in the circumferential direction with the center axis 9 as the center. Each through hole 102 penetrates the rigid internal gear 10 in the axial direction. Furthermore, the rigid internal gear 10 is indirectly fixed in the axial direction with respect to the flange part 40 mentioned later. The details will be described later.

The flexible external gear 20 has a flexible cylindrical main body portion 25 and a flat plate portion 26. The flexible cylindrical main body portion 25 is a portion that extends in a cylindrical shape in the axial direction with the center axis 9 as the center. Furthermore, the flexible cylindrical main body portion 25 is a cylindrical portion that has flexibility and can bend in the radial direction. The flat plate portion 26 is a portion that expands radially inward from the other end of the flexible cylindrical main body portion 25. Furthermore, the flat portion 26 is a flat portion that is harder to bend than the flexible cylindrical main body portion 25.

As shown in FIG. 1, one end of the flexible cylindrical main body portion 25 is arranged on the radially inner side of the rigid internally toothed gear 10. The flexible externally toothed gear 20 has a plurality of external teeth 21 on the outer peripheral surface near one end. The plurality of external teeth 21 are arranged at a constant pitch along the circumferential direction. At a position where the plurality of external teeth 21 mesh with the internal teeth 11 of the rigid internal gear 10 (hereinafter referred to as "occlusal portion 251", which will be described in detail later), the plurality of external teeth 21 are formed to be inclined with respect to the central axis 9 Bevel gear. The number of teeth of the internal teeth 11 of the rigid internal gear 10 and the number of teeth of the external teeth 21 of the flexible external gear 20 are slightly different. In the center of the flat plate portion 26, an output shaft (not shown) for deriving decelerated power is fixed.

The wave generator 30 is a mechanism for flexing and deforming the flexible externally toothed gear 20. The wave generator 30 has a non-circular cam 31 and a wave bearing 32 (second bearing).

The non-circular cam 31 is a member that expands in a ring shape with the center shaft 9 as the center. The inner peripheral surface of the non-circular cam 31 uses, for example, a fixing member 103 extending in the axial direction, and is fixed to the outer peripheral surface of the input portion 101 so as not to rotate relative to each other. As a result, the non-circular cam 31 rotates with the input unit 101 at the rotation speed before deceleration with the central shaft 9 as the center. However, the non-circular cam 31 may be fixed to the input portion 101 by other methods such as adhesion or press-fitting. The non-circular cam 31 of this embodiment has an elliptical cam profile. That is, the non-circular cam 31 has a different outer diameter according to the position in the circumferential direction.

The wave bearing 32 is a flexible bearing located on the radially inner side of the rigid internal gear 10. The wave bearing 32 has an inner wheel 321, a plurality of balls 322, and an outer wheel 323 that is elastically deformable. The inner ring 321 is fixed to the outer peripheral surface of the non-circular cam 31. A plurality of balls 322 are interposed between the inner wheel 321 and the outer wheel 323 and arranged in the circumferential direction. The outer wheel 323 is elastically deformed (deformed and deformed) via the inner wheel 321 and the balls 322 to reflect the cam profile of the rotating non-circular cam 31. Furthermore, the outer ring 323 is in contact with the inner peripheral surface of the portion of the flexible cylindrical main body portion 25 having the outer teeth 21. In this way, for the wave bearing 32 of this embodiment, a ball bearing is used. However, instead of ball bearings, other types of bearings such as roller bearings may be used. The wave generator 30 has a different outer diameter depending on the position in the circumferential direction, and rotates on the radially inner side of the rigid internally toothed gear 10 with the central shaft 9 as the center at the speed before deceleration.

The flange portion 40 is a member that expands in an annular shape around the center axis 9 around the input portion 101. The flange portion 40 is fixed to the housing of the device in which the wave gear device 100 is mounted. The flange portion 40 is arranged on the radially outer side of the input portion 101 via a support bearing 41 (first bearing). The support bearing 41 has an inner ring 411, a plurality of balls 412 and an outer ring 413. The inner ring 411 is fixed to the outer peripheral surface of the input unit 101. A plurality of balls 412 are interposed between the inner wheel 411 and the outer wheel 413 and arranged in the circumferential direction. The outer ring 413 is fixed to the inner peripheral surface of the flange portion 40. Thereby, the flange portion 40 axially supports the input portion 101 rotatably about the central shaft 9 via the support bearing 41. Thus, for the support bearing 41, a ball bearing is used. However, other types of bearings such as roller bearings may be used instead of ball bearings.

In the wave gear device 100 of such a structure, when the input part 101 rotates at the rotation speed before deceleration, the input part 101 and the non-circular cam 31 rotate integrally. Furthermore, with the rotation of the non-circular cam 31, the inner peripheral surface of the flexible cylindrical main body portion 25 of the flexible externally toothed gear 20 having the external teeth 21 is pushed via the wave bearing 32, whereby the flexible cylindrical main body portion 25 flex and deform into an ellipse. In addition, the flexible cylindrical main body portion 25 is located near the two ends of the long axis of the ellipse formed by the non-circular cam 31 on the radially outer side, in a direction that increases in diameter toward one end ( The direction of diameter reduction) is inclined. As a result, the outer teeth 21 mesh with the inner teeth 11 in the vicinity of the radially outer sides of the two ends of the major axis of the ellipse.

In addition, the flexible cylindrical main body portion 25 is located near the two ends of the short axis of the ellipse formed by the non-circular cam 31 in the radial direction outer side in the direction of decreasing diameter toward one end ( The direction of the diameter expansion) is inclined. Therefore, the outer teeth 21 and the inner teeth 11 do not mesh with each other in the vicinity of the radially outer sides of the two ends of the short axis of the ellipse. That is, in the present embodiment, the external teeth 21 and the internal teeth 11 mesh with each other partially (at the engaging portion 251) in the circumferential direction.

When the non-circular cam 31 rotates, the positions of both ends of the major axis of the ellipse formed by the non-circular cam 31 move in the circumferential direction, and therefore the engagement portion 251 of the external teeth 21 and the internal teeth 11 also moves in the circumferential direction. Here, as described above, the number of teeth of the internal teeth 11 of the rigid internal gear 10 and the number of teeth of the external teeth 21 of the flexible external gear 20 are slightly different. Therefore, every time the non-circular cam 31 rotates one revolution, the engagement portion 251 of the inner tooth 11 and the outer tooth 21 slightly changes. As a result, with respect to the rigid internal gear 10, the flexible external gear 20 and the output shaft rotate at a reduced rotational speed. That is, while the flexible external gear 20 and the output shaft move the engagement portion 251 between the external teeth 21 of the flexible external gear 20 and the internal teeth 11 of the rigid internal gear 10 in the circumferential direction, the gap between the external teeth 21 and the internal teeth 11 The number of teeth is different and relatively rotates with respect to the rigid internal gear 10.

＜1-2. Detailed structure of rigid internal gear, flexible external gear and wave bearing＞ Next, the detailed structure of the rigid internally toothed gear 10, the flexible externally toothed gear 20, and the wave bearing 32 will be described. 3 and 4 are partial longitudinal sectional views of the wave gear device 100 of the first embodiment. In addition, FIG. 3 illustrates the structure near the engagement portion 251 of the external teeth 21 of the flexible external gear 20 in the circumferential direction and the internal teeth 11 of the rigid internal gear 10 in the wave gear device 100. 4 illustrates a structure in the wave gear device 100 near a position 252 where the external teeth 21 of the flexible external gear 20 in the circumferential direction and the internal teeth 11 of the rigid internal gear 10 do not mesh. Hereinafter, in addition to FIGS. 3 and 4, FIG. 1 and FIG. 2 are appropriately referred to.

As shown in FIG. 3, in the circumferential direction of the flexible cylindrical main body portion 25, the engagement portion 251 of the external teeth 21 of the flexible external gear 20 and the internal teeth 11 of the rigid internal gear 10 increases toward the other end. The direction of diameter reduction (toward the radial inner side) is inclined. In addition, the inner peripheral surface of the rigid internally toothed gear 10 extends over the entire circumference in the circumferential direction, and is inclined toward the inside in the radial direction toward the other end. At the meshing portion 251 between the internal teeth 11 and the external teeth 21 in the circumferential direction, the straight line extending the tooth direction 111 of the internal teeth 11 of the rigid internal gear 10 and the line extending the external teeth 21 of the flexible external gear 20 The straight line extending the tooth direction 211 intersects at a point on the central axis 9.

Here, the rigid internal gear 10 is fixed to the flange portion 40 in the axial direction via the spacer 14. Specifically, first, in the middle of assembling the wave gear device 100 including the rigid internal gear 10 and the flexible external gear 20 or the adjustment stage after assembly, the spacer 14 is sandwiched between the rigid internal gear 10 and the flange Between the axial direction of the section 40. The gasket 14 is a resin or metal member that expands in an annular shape with the center axis 9 as the center. The inner diameter of the gasket 14 of this embodiment is slightly larger than the inner diameter of the rigid internal gear 10. The outer diameter of the spacer 14 is slightly smaller than the outer diameter of the rigid internal gear 10. The number of the spacers 14 to be sandwiched may be one piece or multiple pieces. In addition, the number of the spacers 14 to be sandwiched may be zero (that is, not to be sandwiched). Thereby, the axial position of the rigid internally toothed gear 10 with respect to the flange portion 40 can be adjusted. In addition, a through hole 140 is provided in each gasket 14. The through hole 140 penetrates the gasket 14 in the axial direction. After adjusting the axial position of the rigid internally toothed gear 10, the rigid internally toothed gear 10 and the through hole 140 of the spacer 14 are used to fix the rigid internally toothed gear 10 and the spacer 14 through the through hole 102. The piece 14 is fixed to the flange portion 40 in the axial direction. Thereby, the axial position of the rigid internal gear 10 with respect to the flange portion 40 is fixed.

Furthermore, as described above, the input portion 101 is axially supported on the radially inner side of the flange portion 40 via the support bearing 41. That is, the rigid internally toothed gear 10 is arranged such that the axial position relative to the input portion 101 can be adjusted. Furthermore, the wave generator 30 that rotates while pushing the inner peripheral surface of the flexible cylindrical main body portion 25 is fixed to the outer peripheral surface of the input portion 101. External teeth 21 are formed on the outer peripheral surface of the flexible cylindrical main body portion 25. On the inner peripheral surface of the rigid internal gear 10, internal teeth 11 are formed. As described above, in the occlusal portion 251 of the inner teeth 11 and the outer teeth 21 in the circumferential direction in the wave gear device 100, the tooth direction 111 of the inner tooth 11 and the tooth direction 211 of the outer tooth 21 are both toward the other end. The part is inclined toward the radial inner side. Therefore, by using the spacer 14 to adjust the axial position of the rigid internal gear 10, it is possible to adjust the internal teeth 11 and the external teeth at the engagement portion 251 between the internal teeth 11 and the external teeth 21 in the circumferential direction of the wave gear device 100. The axial and radial gaps between the teeth 21. Therefore, there is no need to reduce the tooth heights of the internal teeth 11 and the external teeth 21, and the axial and radial gaps between the internal teeth 11 and the external teeth 21 can be adjusted, so that the strength of the internal teeth 11 and the external teeth 21 can be suppressed from decreasing Therefore, it is possible to suppress a decrease in the efficiency of rotation transmission from the external teeth 21 to the internal teeth 11. Furthermore, it is possible to adjust the axial and radial gaps between the internal teeth 11 and the external teeth 21 using a simple structure, and therefore it is possible to suppress an increase in the cost of gap adjustment.

In addition, as shown in FIG. 3, the outer peripheral surface of the outer ring 323 of the wave bearing 32 is processed into a smooth convex curved surface near the other end. At the engagement portion 251 of the inner teeth 11 and the outer teeth 21 in the circumferential direction of the wave gear device 100, the inner peripheral surface of the flexible cylindrical main body portion 25 is in contact with the vicinity of the other end of the outer ring 323 of the wave bearing 32. In the vicinity of the contact portion, the outer peripheral surface of the outer ring 323 is formed in a curved shape, thereby suppressing abrasion or damage of the flexible cylindrical main body portion 25 and the outer ring 323.

Furthermore, as shown in FIG. 4, the outer peripheral surface of the outer ring 323 of the wave bearing 32 is processed into a smooth convex curved surface near one end. The flexible cylindrical main body portion 25 is in a circumferential direction at a position 252 where the external teeth 21 of the flexible externally toothed gear 20 and the internal teeth 11 of the rigid internally toothed gear 10 are not meshed, and the diameter decreases toward one end (toward Radially inside) tilt. In addition, at a position 252 in the circumferential direction of the wave gear device 100 where the inner teeth 11 and the outer teeth 21 are not engaged, the inner peripheral surface of the flexible cylindrical body portion 25 contacts the vicinity of one end of the outer ring 323 of the wave bearing 32. In the vicinity of the contact portion, the outer peripheral surface of the outer ring 323 is formed in a curved shape, thereby suppressing abrasion or damage of the flexible cylindrical main body portion 25 and the outer ring 323.

<2. The second embodiment> Next, the structure of the wave gear device 100B of the second embodiment of the present invention will be described. In addition, in the following, differences from the first embodiment will be mainly described, and overlapping descriptions of the parts equivalent to the first embodiment will be omitted.

Fig. 5 is a longitudinal sectional view of a wave gear device 100B of the second embodiment. Fig. 6 is a cross-sectional view of the wave gear device 100B when viewed from the position B-B in Fig. 5. As shown in FIGS. 5 and 6, the wave gear device 100B includes a rigid internal gear 10B, a flexible external gear 20B, a wave generator 30B, a flange portion 40B, and a housing 50B.

The rigid internally toothed gear 10B is a member that expands in an annular shape with the center shaft 9B as the center. As shown in Fig. 6, the rigid internal gear 10B has a plurality of internal teeth 11B on the inner peripheral surface. The plurality of internal teeth 11B are arranged at a constant pitch along the circumferential direction. The rigid internal gear 10B is provided with a plurality of (eight in this embodiment) through holes 102B for inserting screws (not shown). The plurality of through holes 102B are arranged at equal intervals in the circumferential direction with the central axis 9B as the center. Each through hole 102B penetrates the rigid internal gear 10B in the axial direction. The rigid internal gear 10B is screwed through the through hole 102B, thereby being fixed to the first connecting portion 151B adjacent to one side in the axial direction. On the other side of the rigid internally toothed gear 10B in the axial direction, an output shaft (not shown) for deriving decelerated power is fixed.

The first connecting portion 151B is a member that extends in a cylindrical shape in the axial direction with the center axis 9B as the center. In addition, a second connecting portion 152B is arranged on the radially outer side of the first connecting portion 151B. The second connecting portion 152B has an inner diameter slightly larger than the outer diameter of the first connecting portion 151B, and is a member that extends in a cylindrical shape in the axial direction with the central axis 9B as the center. Furthermore, both the first connecting portion 151B and the second connecting portion 152B have high rigidity. The second connecting portion 152B is provided with a plurality of through holes 153B for inserting screws (not shown). Each through hole 153B penetrates the second connecting portion 152B in the axial direction.

The first connecting portion 151B is rotatably connected to the second connecting portion 152B through a bearing 16B. For the bearing 16B of the present embodiment, a cross roll bearing (cross roll bearing) is used. As shown in FIG. 5, the bearing 16B has a plurality of cylindrical rollers 161B between the inner peripheral surface of the second connecting portion 152B and the outer peripheral surface of the first connecting portion 151B. The plurality of cylindrical rollers 161B are between the annular V groove provided on the inner peripheral surface of the second connecting portion 152B and the annular V groove provided on the outer peripheral surface of the first connecting portion 151B. Alternately change the direction and arrange one side. Thereby, while allowing the rotation of the first connecting portion 151B with respect to the second connecting portion 152B, they are connected to each other with high rigidity. Even if this kind of crossed roller bearing does not use a pair like a ball bearing, it can obtain the required rigidity in the axial and radial directions. That is, by using a cross roller bearing, the number of bearings (bearing) provided in the wave gear device 100B can be reduced. Thereby, the weight of the bearing 16B can be reduced, and the axial dimension of the bearing 16B can be suppressed.

The flexible external gear 20B has a flexible cylindrical body portion 25B and a flat plate portion 26B. The flexible cylindrical main body portion 25B is a portion that extends in a cylindrical shape in the axial direction with the center axis 9B as the center. The flat plate portion 26B is a portion that expands radially outward from one end of the flexible cylindrical main body portion 25B. A plurality of through holes 260B penetrating the flat plate portion 26B in the axial direction are provided at a portion on the radially outer side of the flat plate portion 26B. Each through hole 260B penetrates the flat plate portion 26B in the axial direction. The radially outer portion of the flat plate portion 26B is sandwiched between the second connecting portion 152B and the flange portion 40B described later in the axial direction, and passes through the through holes 153B of the second connecting portion 152B and the through holes of the flat plate portion 26B. 260B and screwed, thereby being fixed.

The wave generator 30B is a mechanism for flexing and deforming the flexible external gear 20B. The wave generator 30B has a bearing frame 33B, a plurality of pressing bearings 34B (third bearing), a plurality of rollers 35B, and a plurality of auxiliary bearings 36B (fourth bearing).

The bearing frame 33B is a member that extends in a cylindrical shape in the axial direction with the center shaft 9B as the center. The bearing frame 33B respectively holds a plurality of pressing bearings 34B described later and a plurality of auxiliary bearings 36B described later. The inner peripheral surface of the bearing frame 33B is an outer peripheral surface fixed to the input portion 101B so as not to rotate relative to each other. As a result, the bearing frame 33B, together with the input portion 101B, rotates at the rotation speed before deceleration around the central shaft 9B.

As shown in FIGS. 5 and 6, in the bearing frame 33B, four bearing support portions 331B are fixed. The four bearing support portions 331B are provided with an interval of 90 degrees in the circumferential direction from each other with the central axis 9B as the center. Each bearing support portion 331B has high rigidity. In two of the four bearing support portions 331B facing each other, the pressing bearing 34B is respectively fixed, and is inclined toward the radially outer side as it goes to the other end portion. Furthermore, in the remaining two of the four bearing support portions 331B, the auxiliary bearings 36B are respectively fixed, and the auxiliary bearings 36B are inclined toward the inner side in the radial direction toward the other end portion.

In this embodiment, the two pressing bearings 34B are arranged at a distance of 180 degrees from each other in the circumferential direction with the center axis 9B as the center. Each pressing bearing 34B has an inner ring 341B, a plurality of balls 342B, and an outer ring 343B. The inner ring 341B is fixed to the bearing support portion 331B along the inclination. A plurality of balls 342B are interposed between the inner wheel 341B and the outer wheel 343B. To the outer ring 343B, a roller 35B described later is fixed. Thus, for the pressing bearing 34B, a ball bearing is used. However, other types of bearings such as roller bearings may be used instead of ball bearings. In addition, the number of pressing bearings 34B may be plural, and is not limited to two.

The roller 35B is located on the radially inner side of the rigid internally toothed gear 10B. As described above, the roller 35B is fixed to the outer ring 343B of the pressing bearing 34B. The roller 35B is an annular disc having an outer diameter of one-third or more and one-half the inner diameter of the flexible cylindrical main body portion 25B. In addition, the roller 35B is made of metal or resin, and is in contact with the inner peripheral surface of the flexible cylindrical main body portion 25B at the engagement portion 251B of the inner tooth 11B and the outer tooth 21B, and receives frictional force. The pressing bearing 34B indirectly contacts the flexible external gear 20B via the roller 35B, and rotates by the friction force. Furthermore, the pressing bearing 34B, together with the roller 35B, revolves (rotates) at the speed before deceleration with the central shaft 9B as the center via the input portion 101B and the bearing frame 33B. That is, the pressing bearing 34B revolves and rotates around the central axis 9B. However, the pressing bearing 34B may directly contact the flexible external gear 20B without passing through the roller 35B.

Furthermore, in the present embodiment, the two auxiliary bearings 36B are centered on the central axis 9B, and are arranged at an interval of 90 degrees from the two pressing bearings 34B in the circumferential direction. Each auxiliary bearing 36B has an inner ring 361B, a plurality of balls 362B, and an outer ring 363B. The inner ring 361B is fixed to the bearing support portion 331B along the inclination. The plurality of balls 362B are interposed between the inner wheel 361B and the outer wheel 363B. Thus, for the auxiliary bearing 36B, a ball bearing is used. However, other types of bearings such as roller bearings may be used instead of ball bearings. Furthermore, the number of auxiliary bearings 36B is not limited to two.

As shown in FIG. 6, the inner peripheral surface of the flexible cylindrical main body portion 25B is enlarged in diameter in the vicinity of two locations in the circumferential direction that are in contact with the roller 35B. On the other hand, the inner peripheral surface of the flexible cylindrical main body portion 25B is at a position 252B in the circumferential direction that is separated from the two pressing bearings 34B by 90 degrees with the central axis 9B as the center, and the auxiliary bearing 36B The outer wheel 363B contacts. Thereby, the excessive diameter reduction of the flexible cylindrical main body portion 25B at this position is suppressed. In addition, the outer wheels 363B of the two auxiliary bearings 36B respectively directly contact the inner peripheral surface of the flexible cylindrical main body portion 25B and receive frictional force, thereby rotating automatically. Furthermore, the auxiliary bearing 36B revolves (rotates) at the speed before deceleration with the central shaft 9B as the center via the input portion 101B and the bearing frame 33B. That is, the auxiliary bearing 36B revolves and rotates around the central axis 9B. However, the auxiliary bearing 36B may indirectly contact the inner peripheral surface of the flexible cylindrical main body portion 25B via other members such as rollers.

The flange portion 40B is a member that expands in an annular shape around the center axis 9B around the input portion 101B and the housing 50B described later. As described above, at the radially outer portion of the flange portion 40B, the flat plate portion 26B and the second connecting portion 152B of the flexible external gear 20B are fixed by screwing. In addition, a through hole 400B that penetrates the flange portion 40B in the axial direction is provided at a radially inner portion of the flange portion 40B. The through hole 400B penetrates the flange portion 40B in the axial direction. The radially inner part of the flange portion 40B is indirectly fixed to the housing 50B described later in the axial direction. The details will be described later.

The housing 50B is arranged on the radially outer side of the input portion 101B via the support bearing 41B. The support bearing 41B has an inner ring 411B, a plurality of balls 412B, and an outer ring 413B. The inner ring 411B is fixed to the outer peripheral surface of the input portion 101B. The plurality of balls 412B are interposed between the inner wheel 411B and the outer wheel 413B, and are arranged in the circumferential direction. The outer ring 413B is fixed to the inner peripheral surface of the housing 50B. Thereby, the housing 50B axially supports the input portion 101B rotatably with the central shaft 9B as the center via the support bearing 41B. Furthermore, the housing 50B is directly or indirectly fixed to the housing of the device in which the wave gear device 100B is mounted.

In the wave gear device 100B of this structure, when the input portion 101B rotates at the speed before deceleration, the input portion 101B, the bearing frame 33B, the pressing bearing 34B, the roller 35B, and the auxiliary bearing 36B are centered on the central shaft 9B And rotate in one body. Furthermore, with the rotation (revolution) of the pressing bearing 34B centered on the central shaft 9B, the inner peripheral surface of the flexible cylindrical main body portion 25B of the flexible externally toothed gear 20B is pushed via the roller 35B, thereby making the flexible cylindrical The main body 25B flexes and deforms into an elliptical shape. In addition, the flexible cylindrical main body 25B is inclined in a direction in which the diameter increases toward the other end in the vicinity of the radially outer side of the two pressing bearings 34B. Thereby, in the vicinity of the radially outer side of the two pressing bearings 34B, the external teeth 21B of the flexible external gear 20B mesh with the internal teeth 11B of the rigid internal gear 10B.

In addition, the flexible cylindrical main body portion 25B is radially outward of a position 252B that is spaced 90 degrees from the two pressing bearings 34B in the circumferential direction with the central axis 9B as the center, and faces toward the other end. The direction of reduced diameter is inclined. Therefore, in the vicinity of the two points, the external teeth 21B of the flexible external gear 20B and the internal teeth 11B of the rigid internal gear 10B are not engaged. That is, in the present embodiment, the external teeth 21B of the flexible external gear 20B and the internal teeth 11B of the rigid internal gear 10B are partially meshed with each other in the circumferential direction (at the engaging portion 251B).

When the two pressing bearings 34B revolve, the engagement portion 251B of the external teeth 21B of the flexible external gear 20B and the internal teeth 11B of the rigid internal gear 10B also moves in the circumferential direction. Here, the number of teeth of the internal teeth 11B of the rigid internal gear 10B is slightly different from the number of teeth of the external teeth 21B of the flexible external gear 20B. Therefore, every time the two pressing bearings 34B revolve one revolution, the engagement portion 251B of the inner tooth 11B and the outer tooth 21B slightly changes in the circumferential direction. In this embodiment, the flexible externally toothed gear 20B is fixed to the flange portion 40B and therefore does not rotate in the circumferential direction. As a result, the rigid internally toothed gear 10B and the output shaft rotate at a reduced speed with respect to the flexible externally toothed gear 20B. That is, while the rigid internal gear 10B and the output shaft move the engagement portion 251B between the external teeth 21B of the flexible external gear 20B and the internal teeth 11B of the rigid internal gear 10B in the circumferential direction, they are caused by the gap between the external teeth 21B and the internal teeth 11B. The number of teeth is different and relatively rotates with respect to the flexible externally toothed gear 20B.

Fig. 7 is a partial longitudinal sectional view of a wave gear device 100B of the second embodiment. In addition, FIG. 7 illustrates the structure near the fixed position of the flange portion 40B and the housing 50B. The housing 50B has a housing cylindrical portion 501B and a housing flat plate portion 502B. The casing cylindrical portion 501B is a portion that extends cylindrically in the axial direction with the center axis 9B as the center. An outer ring 413B supporting the bearing 41B is fixed to the inner peripheral surface of the casing cylindrical portion 501B. The housing flat plate portion 502B is a portion that expands radially outward from the other end of the housing cylindrical portion 501B.

As shown in FIG. 7, the flange portion 40B is fixed to the housing flat plate portion 502B in the axial direction via the spacer 14B. Specifically, first, in the middle of assembling the wave gear device 100B or in the adjustment stage after assembly, the spacer 14B is sandwiched between the flange portion 40B and the housing flat plate portion 502B in the axial direction. The number of the spacers 14B sandwiched may be one or multiple. In addition, the number of pieces of the spacer 14B to be sandwiched may be zero (that is, not to be sandwiched). Thereby, the axial position of the flange portion 40B relative to the housing flat plate portion 502B can be adjusted. Moreover, each spacer 14B is provided with a through hole 140B. The through hole 140B penetrates the gasket 14B in the axial direction. After adjusting the axial position of the flange portion 40B, the flange portion 40B is fixed to the housing flat plate portion 502B with screws 13B through the through hole 400B of the flange portion 40B and the through hole 140B of the gasket 14B, thereby fixing the flange portion 40B and spacer 14B are fixed to housing 50B in the axial direction. Thereby, the axial position of the flange portion 40B relative to the housing 50B is fixed.

Furthermore, as described above, the input portion 101B is axially supported on the radially inner side of the housing 50B via the support bearing 41B. Furthermore, on the outer peripheral surface of the input portion 101B, a wave generator 30B that pushes and rotates the inner peripheral surface of the flexible cylindrical main body portion 25B is fixed. External teeth 21B are formed on the outer peripheral surface of the flexible cylindrical main body portion 25B. In addition, internal teeth 11B are formed on the inner peripheral surface of the rigid internally toothed gear 10B rotatably supported by the flange portion 40B. As shown in FIG. 5, in the wave gear device 100B, at the engagement portion 251B between the internal teeth 11B and the external teeth 21B in the circumferential direction, the tooth direction of the internal teeth 11B and the tooth direction of the external teeth 21B are both toward the other end The part is inclined toward the radially outer side. Therefore, by using the spacer 14B to adjust the axial position of the flange portion 40B that rotatably supports the rigid internal gear 10B with the internal teeth 11B, the internal teeth 11B and the external teeth in the circumferential direction of the wave gear device 100B can be adjusted. At the position of the biting portion 251B of the tooth 21B, the axial and radial gaps between the inner tooth 11B and the outer tooth 21B are adjusted. Therefore, there is no need to reduce the tooth heights of the inner teeth 11B and the outer teeth 21B, and the axial and radial gaps between the inner teeth 11B and the outer teeth 21B can be adjusted, so that the strength of the inner teeth 11B and the outer teeth 21B can be suppressed from decreasing Therefore, it is possible to suppress a decrease in the efficiency of rotation transmission from the external teeth 21B to the internal teeth 11B. Furthermore, it is possible to adjust the axial and radial gaps between the internal teeth 11B and the external teeth 21B using a simple structure, so that it is possible to suppress an increase in the cost of gap adjustment.

<3. The third embodiment> Next, the structure of the wave gear device 100C of the third embodiment of the present invention will be described. In addition, in the following, differences from the first embodiment and the second embodiment will be mainly described, and overlapping descriptions of the parts equivalent to the first embodiment and the second embodiment will be omitted.

Fig. 8 is a longitudinal sectional view of a wave gear device 100C of the third embodiment. As shown in FIG. 8, the wave gear device 100C has a rigid internal gear 10C, a flexible external gear 20C, a wave generator 30C, a flange portion 40C, a housing 50C, and a nut 60C. Regarding the rigid internally toothed gear 10C, the flexible externally toothed gear 20C, and the wave generator 30C, since they have the same structure as the rigid internally toothed gear 10, the flexible externally toothed gear 20, and the wave generator 30 of the first embodiment, repeated descriptions are omitted . However, the rigid internally toothed gear 10C of the present embodiment is directly fixed to the flange portion 40C in the axial direction without using a gasket.

The flange portion 40C is a member that expands in an annular shape around the center axis 9C around the input portion 101C and the housing 50C described later. As described above, the rigid internal gear 10C is fixed to the flange portion 40C in the axial direction by the screw 13C. In addition, a female screw 401C is formed on the inner peripheral surface of the flange portion 40C.

The housing 50C is a member that extends in a cylindrical shape in the axial direction with the central axis 9C as the center. The housing 50C is directly or indirectly fixed to the housing of the device on which the wave gear device 100C is mounted. The housing 50C is arranged on the radially outer side of the input portion 101C via the support bearing 41C. The housing 50C rotatably supports the input portion 101C with the central shaft 9C as the center via the support bearing 41C. In addition, a male screw 503C is formed on the outer peripheral surface of the housing 50C. The male thread 503C is screwed to the female thread 401C of the flange portion 40C. Thereby, the flange part 40C is arrange|positioned so that the axial position with respect to the housing 50C can be adjusted.

The nut 60C is a member that expands in an annular shape around the center axis 9C around the input portion 101C and the housing 50C described later. The nut 60C is located on one side of the flange portion 40C in the axial direction. Moreover, the nut 60C has the same inner diameter as the flange portion 40C. A female screw 601C is formed on the inner peripheral surface of the nut 60C. The male thread 503C of the housing 50C is screwed to the female thread 601C. Thereby, the nut 60C is arranged so that its axial position relative to the housing 50C can be adjusted. Furthermore, the nut 60C contacts the flange portion 40C in the axial direction, thereby fixing the axial position of the flange portion 40C with respect to the housing 50C.

This embodiment has the above-mentioned structure, so that, similar to the first and second embodiments, the internal teeth of the rigid internal gear 10C and the external teeth of the flexible external gear 20C in the circumferential direction of the wave gear device 100C can be At the biting portion 251C of the teeth, the axial and radial gaps between the internal teeth and the external teeth are adjusted.

<4. Fourth Embodiment> Next, the structure of the wave gear device 100D of the fourth embodiment of the present invention will be described. In addition, the following description focuses on differences from the first embodiment to the third embodiment, and repetitive descriptions of the parts equivalent to the first embodiment to the third embodiment are omitted.

Fig. 9 is a longitudinal sectional view of a wave gear device 100D of the fourth embodiment. As shown in FIG. 9, the input portion 101D has a friction coupling portion 202D frictionally coupled with the rotating shaft 201 of the electric motor 200 at one end. The friction coupling portion 202D includes a notch 203D cut in the direction of the central axis 9D, and a screw 13D screwed in the right-angle direction of the central axis 9D. The input portion 101D is connected to the rotating shaft 201 of the electric motor 200 in the axial direction via a friction coupling 202D. Specifically, the input portion 101D inserts the rotating shaft 201 into the friction coupling portion 202D and tightens the screw 13D, thereby rotating the center shaft 9D by the power obtained from the electric motor 200. Therefore, the wave gear device 100D does not need to use a general-purpose coupling separately, and the axial size can be reduced with a small number of parts to obtain an integrated structure of the electric motor 200 and the wave gear device 100D.

＜5. Modifications＞ As mentioned above, although the exemplary embodiment of the present invention has been described, the present invention is not limited to the above-mentioned embodiment.

In the first embodiment described above, the spacer 14 is sandwiched between the rigid internal gear 10 and the flange portion 40 in the axial direction. In the second embodiment, the flange portion 40B and the housing flat plate The part 502B has a structure in which the spacer 14B is sandwiched in the axial direction. However, in the wave gear device having a non-circular cam disclosed in the first embodiment, a shim may be sandwiched between the flange portion and the housing in the axial direction. Furthermore, in the wave gear device having a bearing frame that holds the pressing bearing disclosed in the second embodiment, it may also have a second connecting portion or a flat plate portion that rotatably supports the rigid internal gear via the first connecting portion and A structure in which a gasket is sandwiched between the flanges in the axial direction. In other words, it is only necessary to have a structure capable of adjusting the axial position of the rigid internally toothed gear or the flange portion directly or indirectly fixed to the rigid internally toothed gear.

In the described embodiment, a washer or nut is used to adjust the axial position of the rigid internal gear with respect to the input part. However, in addition to washers or nuts, springs, cams and other components can also be used to adjust the axial position of the rigid internal gear relative to the input portion.

For the material of each member constituting the wave gear device, for example, a high-strength metal is used. However, the material of each member should just be able to withstand the load during use, and it is not necessarily limited to metal.

In addition, the shape of the detailed part of the wave gear device may be different from the shape shown in each figure of the above-mentioned embodiment.

[Industrial availability] This application can be used for wave gear devices.

9, 9B, 9C, 9D‧‧‧Central axis 10, 10B, 10C‧‧‧Rigid internal gear 11, 11B‧‧‧Internal teeth 13, 13C, 13D‧‧‧Screw 14, 14B‧‧‧Gasket 16B‧‧‧Bearing 20, 20B, 20C‧‧‧Flexible external gear 21, 21B‧‧‧External gear 25, 25B‧‧‧Flexible cylindrical body 26, 26B‧‧‧Plate part 30, 30B, 30C‧‧‧wave generator 31‧‧‧Incorrect circular cam 32‧‧‧Wave Bearing (Second Bearing) 33B‧‧‧Bearing frame 34B‧‧‧Pressing bearing (third bearing) 35B‧‧‧roller 36B‧‧‧Auxiliary bearing (fourth bearing) 40, 40B, 40C‧‧‧Flange 41, 41B, 41C‧‧‧Support bearing (first bearing) 50B、50C‧‧‧Shell 60C‧‧‧Nut 100, 100B, 100C, 100D‧‧‧Wave gear device 101, 101B, 101C, 101D‧‧‧Input part 102, 102B, 140, 153B, 260B, 400B‧‧‧through hole 103‧‧‧Fixed member 111, 211‧‧‧ tooth direction 151B‧‧‧First connection part 152B‧‧‧Second connection part 161B‧‧‧Cylindrical roller 200‧‧‧Motor 201‧‧‧Rotation axis 202D‧‧‧Friction coupling part 203D‧‧‧Grooving 251, 251B, 251C‧‧‧occlusal part 252, 252B‧‧‧Location 321, 341B, 361B, 411, 411B‧‧‧Inner wheel 322, 342B, 362B, 412, 412B‧‧‧Ball 323, 343B, 363B, 413, 413B‧‧‧Outer wheel 331B‧‧‧Bearing support 401C、601C‧‧‧Female thread 501B‧‧‧Cylinder part of shell 502B‧‧‧Housing plate 503C‧‧‧Male thread

Fig. 1 is a longitudinal sectional view of a wave gear device of the first embodiment. Fig. 2 is a cross-sectional view of the wave gear device of the first embodiment. Fig. 3 is a partial longitudinal sectional view of the wave gear device of the first embodiment. Fig. 4 is a partial longitudinal sectional view of the wave gear device of the first embodiment. Fig. 5 is a longitudinal sectional view of a wave gear device according to a second embodiment. Fig. 6 is a cross-sectional view of the wave gear device of the second embodiment. Fig. 7 is a partial longitudinal sectional view of the wave gear device of the second embodiment. Fig. 8 is a longitudinal sectional view of a wave gear device according to a third embodiment. Fig. 9 is a longitudinal sectional view of a wave gear device and a motor according to a fourth embodiment.

9‧‧‧Central axis

10‧‧‧Rigid internal gear

13‧‧‧Screw

14‧‧‧Gasket

20‧‧‧Flexible external gear

25‧‧‧Flexible cylindrical body

26‧‧‧Plate Department

30‧‧‧Wave Generator

31‧‧‧Incorrect circular cam

32‧‧‧Wave Bearing (Second Bearing)

40‧‧‧Flange

41‧‧‧Support bearing (first bearing)

100‧‧‧Wave gear device

101‧‧‧Input part

102‧‧‧through hole

103‧‧‧Fixed member

251‧‧‧bite

321、411‧‧‧Inner wheel

322、412‧‧‧Ball

323、413‧‧‧Outer wheel

Claims (16)

A wave gear device comprising: a rigid internal toothed gear with internal teeth on the inner peripheral surface, which expands in an annular shape with a central axis as the center; a wave generator, on the radial inner side of the rigid internal toothed gear The central shaft rotates as a center and has different outer diameters according to the position in the circumferential direction; and a flexible external gear having external teeth that partially mesh with the internal teeth of the rigid internal gear on the outer peripheral surface, The inner peripheral surface is pushed along with the rotation of the wave generator, whereby the meshing position of the inner tooth and the outer tooth is moved in the circumferential direction, and according to the number of teeth of the inner tooth and the outer tooth In contrast to the relative rotation of the rigid internally toothed gear, the wave gear device is characterized in that the wave generator is fixed to an input portion that rotates around the central axis, and the flexible externally toothed gear has : A flexible cylindrical body portion having the external teeth at one end and extending in a cylindrical shape in the axial direction with the central axis as the center; and a flat plate portion along the diameter from the other end of the flexible cylindrical body portion The flexible cylindrical main body part has a circumferential position where the internal teeth and the external teeth engage with each other, and is inclined in a direction that decreases in diameter toward the other end of the flexible cylindrical main body, The rigid internally toothed gear is configured to be able to adjust an axial position relative to the input part. The wave gear device described in claim 1 further includes a flange portion arranged on the radially outer side of the input portion via a first bearing, and the flange portion and the rigid internal gear via One or more spacers are fixed in the axial direction. The wave gear device described in claim 1 further includes: a housing arranged on the radially outer side of the input portion via a first bearing; and a flange portion directly or indirectly fixed to the rigidity In the internal gear, the housing and the flange portion are fixed in the axial direction via one or more spacers. The wave gear device described in claim 1 further includes: a housing arranged on the radially outer side of the input part via a first bearing; and a flange part directly or indirectly fixed in the rigidity Toothed gear; and a nut having the same inner diameter as the flange portion, and male threads formed on the outer peripheral surface of the housing are respectively screwed to female threads formed on the inner peripheral surface of the flange portion and formed In the female thread on the inner peripheral surface of the nut, the nut contacts the flange portion in the axial direction. The wave gear device according to any one of items 1 to 4 in the scope of the patent application, wherein the position where the inner teeth and the outer teeth in the circumferential direction are engaged, so that the tooth direction of the inner teeth is extended The straight line that crosses the line extending the tooth direction of the external tooth at a point on the central axis. The wave gear device according to any one of items 1 to 4 of the scope of the patent application, wherein the position where the internal teeth and the external teeth of the flexible cylindrical main body part are not engaged in the circumferential direction is The direction in which the diameter increases toward the other end of the flexible cylindrical main body portion is inclined. The wave gear device according to any one of items 1 to 4 in the scope of the patent application, wherein the internal teeth and the external teeth respectively form bevel gears at positions where they mesh with each other. The wave gear device according to any one of items 1 to 4 of the scope of patent application, wherein the wave generator has: a non-circular cam, which rotates around the central axis, and depends on the position in the circumferential direction It has a different outer diameter; and a flexible second bearing. The non-circular cam is fixed to the inner wheel, and the outer wheel is in contact with the flexible outer gear. As the non-circular cam rotates, the inner The bite position of the tooth and the external tooth moves in the circumferential direction. The wave gear device according to any one of items 1 to 4 of the scope of patent application, wherein the wave generator has: a plurality of third bearings, which are spaced apart from each other in the circumferential direction with the central axis as the center Arranged at intervals; and A bearing frame is fixed to the input portion and holds a plurality of the third bearings respectively, and the plurality of third bearings directly or indirectly contact the flexible externally toothed gear, and pass from the input portion via the bearing As the frame rotates, it revolves and rotates around the central axis. The wave gear device according to claim 9, wherein the wave generator further has rollers that are fixed to the outer wheels of a plurality of the third bearings, and the plurality of third bearings pass The roller comes into contact with the flexible externally toothed gear, thereby rotating itself. In the wave gear device described in claim 10, the outer diameter of the roller is one-third or more and one-half the inner diameter of the flexible cylindrical main body. The wave gear device described in claim 9, wherein the wave generator has: two third bearings that are spaced apart from each other by 180 degrees in the circumferential direction with the central axis as the center Arrangement; and two fourth bearings, centered on the central axis and arranged at intervals of 90 degrees from the two third bearings in the circumferential direction, the bearing frames respectively holding the two third Bearing and the two fourth bearings, the two fourth bearings directly or indirectly contact the flexible externally toothed gear, and rotate from the input part via the bearing frame, thus, the The central axis revolves and rotates around the center. The wave gear device according to any one of the claims 1 to 4, wherein the input part is connected to a friction coupling via a rotating shaft of a motor. The wave gear device according to any one of claims 1 to 4, wherein the flat plate portion expands radially inward from the other end of the flexible cylindrical main body portion. The wave gear device according to any one of items 1 to 4 of the scope of patent application, wherein the flat plate portion expands radially outward from the other end of the flexible cylindrical main body portion. The wave gear device according to the first item of the patent application, wherein the wave generator has a wave bearing, and the outer peripheral surface of the outer wheel of the wave bearing is a convex curved surface.

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