DE102021120879A1 - BENDING-ENGAGEMENT TYPE GEAR DEVICE - Google Patents

Abstract

A device is configured compact in an axial direction. A flexural engagement type gear device (1, 1A) includes a wave generator (11, 11A), an external gear (12, 12A) flexed and deformed by the wave generator (11, 11A), a second internal gear (23) meshing with the external gear (12, 12A), and a main bearing (36) interposed between the second internal gear (23) and a second housing (34). A cover member (35) is provided, which is arranged adjacent to the second internal gear (23) in the axial direction and is connected to the second internal gear (23). Inner rings of the main bearing (36) are each formed from the second internal gear (23) and the cover member (35).

Description

BACKGROUND OF THE INVENTION

field of invention

The present invention relates to a flexural engagement type gear device.

Description of the prior art

In the prior art, there is known a gear device of the bending engagement type, which includes an external gear to be bent and deformed and an internal gear meshing with the external gear (see, for example, Japanese Patent No. 5337008 ) . The internal gear is supported by a housing via a main bearing.

SUMMARY OF THE INVENTION

In the prior art gear device of the flexural engagement type, when the internal gear is simply supported on the main bearing, the internal gear can be long in an axial direction, so that the entire device is enlarged in the axial direction.

The present invention has been made in view of the above circumstances, and an object of the present invention is to make an apparatus compact in an axial direction.

According to one aspect of the present invention, there is provided a flexural engagement type gear device including: a wave generator; an external gear flexed and deformed by the wave generator; an internal gear; and a main bearing interposed between the internal gear and a housing.

An adjacent member is provided, which is arranged adjacent to the internal gear in an axial direction and is connected to the internal gear.

Inner rings of the main bearing are each formed of the internal gear and the adjacent member.

According to the present invention, the device can be configured compact in the axial direction.

character list

• 1 Fig. 14 is a cross-sectional view showing a flexural engagement type gear device (1) according to a first embodiment.
• 2 Fig. 14 is a cross-sectional view showing the flexural engagement type gear device (1) in which a second internal gear (23) and a cover member (35) are integrated.
• 3 Fig. 14 is a cross-sectional view showing a flexural engagement type gear device (1A) according to a second embodiment.

DETAILED DESCRIPTION OF THE INVENTION

[First embodiment]

A first embodiment of the present invention will be described in detail below with reference to the drawings.

<Configuration of Bending Engagement Type Gear Device>

1 14 is a cross-sectional view illustrating a flexural engagement type gear device 1 according to the first embodiment.

As shown in the drawing, the flexural engagement type gear device 1 is a flexural engagement type gear device of the cylindrical type and includes a wave generator shaft 10, an external gear 12, a first internal gear 22, a second internal gear 23 and a wave generator bearing 15. Further, the gear device 1 includes the flexural engagement type a first housing 33, a second housing 34, a cover member 35 and a main bearing 36.

The wave generator shaft 10 is a hollow cylindrical shaft rotating around a rotation axis O1, and includes a wave generator 11 having a non-circular (e.g., elliptical) outer shape in a cross section perpendicular to the rotation axis O1. The elliptical shape is not limited to a geometrically exact ellipse and includes a substantially elliptical shape. Contact portions 10b, which protrude from the wave generator 11 in an axial direction to both sides to be in contact with restricting members 41 and 42 to be described later to position the restricting members 41 and 42 in the axial direction, are formed on respective inner diameter side (radially inner side) portions (inner peripheral edge portions) of the wave generator shaft 10 on both sides in the axial direction.

A tip portion 61 of an engine output shaft 60 of an engine (not shown), which is a drive source, is inserted into the shaft generator shaft 10 and connected to be able to transmit power via a spline 62 . The motor is arranged on one side (right side in the drawings) of the flexural engagement type gear device 1 and drives the motor output shaft 60 .

In the following description, a direction along the rotation axis O1 is referred to as the “axial direction”, a direction perpendicular to the rotation axis O1 as a “radial direction”, and a direction of rotation about the rotation axis O1 as a “circumferential direction”. Moreover, in the axial direction, a side to which a reduced rotary motion is output (left side in the drawings) is referred to as an “output side”, and a side opposite to the output side is referred to as a “counter-output side”.

The external gear 12 is a cylindrical member having flexibility and having the rotation axis O1 as a center, and teeth are provided on an outer periphery of the external gear 12 .

The first internal gear 22 and the second internal gear 23 respectively include teeth 22g and 23g in inner diameter portions thereof. The teeth 22g and 23g are aligned side by side in the axial direction. One of the teeth 22g and 23g meshes with teeth on one side of the external gear 12 with respect to a center of the external gear 12 in the axial direction, and the other meshes with teeth on another side of the external gear 12 with respect to the center the axial direction. The teeth 22g and 23g are cut by, for example, a gear shaper, a gear skiving machine, or the like.

Of inner rings of the main bearing 36 , the second internal gear 23 of the internal gears forms a counter-output side inner ring and has a first inner ring rolling surface 23 a in an end portion on the output side of an outer peripheral surface of the second internal gear 23 .

The wave generator bearing 15 is a roller bearing, for example, and is arranged between the wave generator 11 and the external gear 12 . The wave generator bearing 15 includes an outer ring 15a fitted to an inside of the external gear 12, a plurality of rolling elements (rollers) 15b, and a retainer 15c that holds the plurality of rolling elements 15b. The plurality of rolling elements 15b roll on an outer peripheral surface of the wave generator 11 and on an inner peripheral surface of the outer ring 15a, which serve as rolling contact surfaces (also referred to as trajectory surfaces). The shaft generator bearing 15 may include an inner race separate from the shaft generator 11 .

The limiting members 41 and 42, which contact the external gear 12 and the shaft generator bearing 15 and which limit the movement thereof in the axial direction, are provided on both sides of the external gear 12 and the shaft generator bearing 15 in the axial direction.

The restricting members 41 and 42 are fixed to the tip portion 61 of the engine output shaft 60 inserted into the shaft generator shaft 10 by C-rings 43 in a state where the restricting members 41 and 42 are in contact with the contact portions 10b on both sides of the shaft generator shaft 10 stand in the axial direction to insert the wave generator shaft 10 therebetween. Accordingly, the restricting members 41 and 42 are provided integrally with (rotate integrally with) the shaft generator shaft 10 connected to the engine output shaft 60 via the spline 62 .

The restricting members 41 and 42 have clearances C between axial end faces of the wave generator 11 and the restricting members 41 and 42, respectively. Grease (lubricant) is stored in the clearances C, so that lubrication of the shaft generator bearing 15 and the like can be improved.

The first housing 33 is arranged radially outside of the first internal gear 22 . A flange member 63 supporting the motor output shaft 60 is connected to the counter-output side of the first housing 33 by an unillustrated connector. The motor output shaft 60 is inserted into an inner diameter side of the flange member 63 and supported by the flange member 63 via a bearing 64 . The flange member 63 is connected to the first housing 33 in a state where the flange member 63 is centered (positioned in the radial direction) with respect to the first internal gear 22 .

When the flexural engagement type gear device 1 is connected to an external counter device (not shown), the first housing 33 and the flange member 63 are connected to the counter device by tightening together.

The second housing 34 is arranged radially outside of the second internal gear 23 and the cover member 35 and on the output side of the first housing 33 and is connected and integrated with the first housing 33 and the first internal gear 22 . Specifically, the second housing 34 is fitted and centered together with the first housing 33 on an outer peripheral surface 22a of the first internal gear 22 and is in contact in the axial direction via the first housing 33 with an extension portion on the counter-output side of the first internal gear 22 . Then, the second case 34, the first case 33, and the first internal gear 22 are connected by bolts 51 at portions contacting each other in the axial direction.

Furthermore, the second housing 34 includes an outer ring 34a of the main bearing 36 (namely, an outer ring-side rolling surface of a roller 36a of the main bearing 36) in an inner diameter portion of the second housing 34.

The cover member 35 is an example of an adjacent member according to the present invention, is arranged adjacent to the output side of the second internal gear 23 in the axial direction, and is connected to the second internal gear 23 . More specifically, the cover member 35 is fitted (preferably press-fitted) to an outer peripheral surface of a boss portion 23b protruding from an inner diameter portion on the output side of the second internal gear 23 and is centered with respect to the second internal gear 23 . The cover member 35 in this state is in contact with the second internal gear 23 in the axial direction and is connected thereto by bolts 52 in the contact portions. A contact surface between the cover member 35 and the second internal gear 23 is radially outside of the teeth 23g of the second internal gear 23 and radially inside of the main bearing 36.

Of the inner rings of the main bearing 36 , the cover member 35 forms an output-side inner ring and has a second inner ring rolling surface 35 a in an end portion on the opposite output side of an outer peripheral surface of the cover member 35 .

When the flexural engagement type gear device 1 is connected to the external counter device, the cover member 35 is connected to a driven member (not shown) of the counter device and outputs reduced rotation to the driven member.

Moreover, the cover member 35 is formed in a substantially disk-like shape and covers an inner space of the flexural engagement type gear device 1 from the output side in the axial direction. Namely, the cover member 35 does not take a hollow structure, and a bearing supporting the wave generator 11 and an oil seal sliding against the wave generator 11, which are arranged in the case of the hollow structure, are not arranged. For this reason, the device can be configured compact in the axial direction by omitting the bearing and the oil seal, and power loss due to the oil seal can be eliminated.

The main bearing 36 is a cross roller bearing in the present embodiment, and is disposed radially outside the teeth 23g of the second internal gear 23 . The main bearing 36 includes the outer ring 34a provided at the second housing 34, the inner rings each formed of the second internal gear 23 and the cover member 35, and the roller (rolling element) 36a arranged between the outer ring 34a and the Inner rings is arranged. The main bearing 36 supports the second internal gear 23 and the cover member 35 so as to be rotatable relative to the second housing 34 .

Further, the flexural engagement type gear device 1 includes an oil seal 45 and O-rings 46 and 47 for sealing.

The oil seal 45 is arranged between the cover member 35 and the second housing 34 in an end portion on the output side in the axial direction, and suppresses leakage of the lubricant to the output side.

The O-rings 46 and 47 are provided between the first housing 33 and the flange member 63 and between the first housing 33 and the second housing 34, respectively, and suppress movement of the lubricant therebetween.

<material of each element>

The material of each element is not particularly limited and is formed as follows in the present embodiment.

The wave generator shaft 10, the external gear 12, the first internal gear 22, the second internal gear 23, the second housing 34, the cover member 35 and the restricting members 41 and 42 are made of a metallic material such as a steel material. Specifically, although not particularly limited, the shaft generator shaft 10 is made of a steel material such as chromium-molybdenum steel or the like, the external gear 12 is made of a steel material such as nickel-chromium-molybdenum steel or the like, and the restricting members 41 and 42 are made of a steel material such as a high-carbon chromium bearing steel or the like. Moreover, since the second internal gear 23, the second housing 34 and the cover member 35 constitute the inner rings and the outer ring of the main bearing 36, the second internal gear 23, the second housing 34 and the cover member 35 are made of a steel material such as a high-carbon chromium bearing steel or the like , is made, and the first internal gear 22 is also made of a steel material such as high-carbon chromium bearing steel or the like.

The first housing 33 is made of a material different from that of at least one of the second housing 34 and the first internal gear 22, and is made of a different material than that of both the second housing 34 and the first internal gear 22 in the present embodiment. made of a steel material, and is made of, for example, a material having a lower specific gravity than that of the steel material, such as resin or aluminum. Since the first case 33 having a large outer diameter (large volume) is made of resin or aluminum, weight reduction of the device can be achieved.

<Operation of Gear Device>

When the wave generator shaft 10 is driven and rotated via the motor output shaft 60 by the motor, which is a drive source, the motion of the wave generator 11 is transmitted to the external gear 12 . At this time, the external gear 12 is limited to a shape along the outer peripheral surface of the wave generator 11 and, when viewed in the axial direction, is bent into an elliptical shape including a major axis portion and a minor axis portion. Further, the external gear 12 in the major axis portion meshes with the first internal gear 22 which is fixed. For this reason, the external gear 12 does not rotate at the same speed as the shaft generator 11, and the shaft generator 11 rotates relative to the external gear 12 inside thereof. Then, with the relative rotation, the external gear 12 is bent and deformed so that the major-axis position and the minor-axis position of the external gear 12 move in the circumferential direction. The period of deformation is proportional to the period of rotation of the shaft generator shaft 10.

When the external gear 12 is bent and deformed, the major axis position of the external gear 12 moves, so that the meshing position between the external gear 12 and the first internal gear 22 changes in the direction of rotation. Here, for example, if it is assumed that the number of teeth of the external gear 12 is 100 and the number of teeth of the first internal gear 22 is 102, whenever the meshing position makes one revolution, meshing teeth of the external gear 12 and the first internal gear become According to the above-described numbers of teeth, the rotation of the wave generator shaft 10 is reduced at a reduction ratio of 100:2 to be transmitted to the external gear 12.

Meanwhile, since the external gear 12 also meshes with the second internal gear 23, the meshing position between the external gear 12 and the second internal gear 23 is also changed by the rotation of the wave generator shaft 10 in the rotational direction. Here, when the number of teeth of the second internal gear 23 and the number of teeth of the external gear 12 are set to be the same, the external gear 12 and the second internal gear 23 do not rotate relative to each other, and the rotation of the external gear 12 is made with a Reduction ratio of 1: 1 transferred to the second internal gear 23. Therefore, the rotation of the wave generator shaft 10 is reduced at a reduction ratio of 100:2 to be transmitted to the second internal gear 23 and the cover member 35, and the rotation is output to the driven member connected to the cover member 35.

[Technical Effects of First Embodiment]

As described above, according to the present embodiment, the second internal gear 23 and the cover member 35 are arranged adjacent to and connected to each other in the axial direction, and the second internal gear 23 and the cover member 35 form the inner rings of the main bearing 36.

Since the inner rings of the main bearing 36 are thus divided in the axial direction, tool retraction can be eliminated when cutting the second internal gear 23, which is one of the internal gears, and the apparatus can be configured compact in the axial direction.

Namely, when the second internal gear 23 is to be supported on the main bearing 36 while reducing the number of components and integrating the second internal gear 23 and the cover member 35 as shown in FIG 2 As shown, the second internal gear 23 includes a portion on an inner diameter side of the teeth 23g. For this reason, when the teeth 23g are cut by, for example, a gear shaper, a skiving machine, or the like, the tool retraction in the axial direction is required, and as a result, the second internal gear 23 is long in the axial direction.

In this regard, in the present embodiment, since the inner ring of the main bearing 36 is divided into the second internal gear 23 and the cover member 35 which is adjacent to the second internal gear 23, the undercut width for the tool can be eliminated when the tool has an inner circumference of the second Internal gear 23 penetrates to cut the teeth 23g.

Therefore, the device can be configured more compactly in the axial direction than when the second internal gear 23 alone serves as the inner ring of the main bearing 36 as described above. In addition, the axial distance between a surface on the output side of the cover member 35 to which the driven member is to be fixed and the main bearing 36 can be shortened, and a load on the main bearing 36 caused by the load of the driven member can be reduced.

Moreover, according to the present embodiment, the cover member 35 covers the inside of the flexural engagement type gear device 1 in the axial direction, and a bearing that supports the wave generator 11 and an oil seal that slides against the wave generator 11 are not arranged at the cover member 35 .

For this reason, the flexural engagement type gear device 1 can be configured compact in the axial direction, and power loss due to the oil seal can be eliminated.

Moreover, according to the present embodiment, the first housing 33 is made of a material different from that of at least one of the second housing 34 and the first internal gear 22 connected to the first housing 33 .

Accordingly, the first housing 33 can be made of a light-weight material such as resin or aluminum, and weight reduction of the flexural engagement type gear device 1 can be achieved.

Moreover, according to the present embodiment, the restricting members 41 and 42, which restrict the movement of the wave generator bearing 15 in the axial direction, are provided integrally with the wave generator shaft 10 and have the respective clearances C between the axial end faces of the wave generator 11 and the restricting members 41 and 42 .

For this reason, the grease (lubricant) is stored in the clearances C, so that the lubrication of the shaft generator bearing 15 and the like can be improved.

[Second embodiment]

A flexural engagement type gear device according to a second embodiment of the present invention will be described below. Hereinafter, the same components as in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

3 14 is a cross-sectional view illustrating a flexural engagement type gear device 1A according to the second embodiment.

As shown in the drawing, the flexural engagement type gear device 1</b>A according to the second embodiment is a silk hat type flexural engagement type gear device 1 , which is different from the flexural engagement type gear device 1 of the first embodiment. Specifically, the flexural engagement type gear device 1A includes a wave generator shaft 10A, an external gear 12A, an internal gear 23A, and a wave generator bearing 15A. Further, the flexural engagement type gear device 1A includes the first housing 33, the second housing 34, the cover member 35, and the main bearing 36.

The wave generator shaft 10A is a hollow cylindrical shaft that rotates around the rotation axis O1, and includes a wave generator 11A having a non-circular (e.g., elliptical) outer shape in a cross section perpendicular to the rotation axis O1. The elliptical shape is not limited to a geometrically exact ellipse and includes a substantially elliptical shape.

A tip portion 61A of an engine output shaft 60A of an engine (not shown) which is a driving source is inserted into and connected to the shaft generator shaft 10A to be able to transmit power via a spline 62A.

The external gear 12A includes a cylindrical portion 121A having a predetermined length in the axial direction, a flange portion 122A, and a trunnion portion 123A.

The cylindrical portion 121A is a cylindrical member having flexibility and having the rotation axis O1 as a center, and teeth are provided on an outer circumference of a substantially half portion on the exit side of the cylindrical portion 121A.

The flange portion 122A extends from an end portion on the counter-exit side of the cylindrical portion 121A to an outer diameter side. A surface on the exit side of the flange portion 122A is in contact with the first case 33, and the first case 33 and the second case 34 are connected by the bolts 51 in the flange portion 122A.

The journal portion 123A is formed in a cylindrical shape extending from the surface on the exit side of the flange portion 122A to the exit side over the entire circumference at a radial position on the outer diameter side of the cylindrical portion 121A. An outer peripheral surface of the journal portion 123A is a journal surface to which the first housing 33 and the second housing 34 are fitted.

The cylindrical portion 121A, a portion extending from the end portion on the counter-exit side of the cylindrical portion 121A to the outer diameter side, and the trunnion portion 123A define a space S over the entire circumference, the space S having a substantially U-shaped cross section and is open to the exit side. The space S communicates with the main bearing 36, suppresses an increase in internal pressure, and functions as a lubricant reservoir to improve resistance to leakage of grease.

The internal gear 23A is configured similarly to the second internal gear 23 of the first embodiment, and includes the teeth 23g in an inner diameter portion of the internal gear 23A. The teeth 23 g mesh with the teeth on the outer periphery of the external gear 12 .

Of the inner rings of the main bearing 36, the inner gear 23A forms a counter-output side inner ring and has the first inner ring rolling surface 23A in an end portion on the output side of an outer peripheral surface of the inner gear 23A.

The wave generator bearing 15A is, for example, a ball bearing, and is arranged between the wave generator 11A and the external gear 12A.

A restricting member 42A that restricts the movement of the shaft generator bearing 15A in the axial direction is provided on the output side of the shaft generator bearing 15A. The outer diameter of the restricting member 42A corresponds to the radial position of an outer ring of the shaft generator bearing 15A. For this reason, grease sealed in the shaft generator bearing 15A can be suppressed from leaking to the output side by the restricting member 42A.

The first housing 33 is arranged radially outside of the flange portion 122A and the trunnion portion 123A of the internal gear 23A. The flange member 63 supporting the motor output shaft 60A is connected to the first housing 33 in a state where the flange member 63 is centered with respect to the flange portion 122A of the internal gear 23A. Furthermore, the first case 33 may be made of a material having a smaller specific gravity, such as aluminum alloy or resin, than the external gear 12A or the second case 34 made of a steel material.

The cover member 35 is arranged adjacent to the output side of the internal gear 23A in the axial direction, and is connected to the internal gear 23A. More specifically, the cover member 35 is fitted (preferably press-fitted) to the outer peripheral surface of the journal portion 23b protruding from an inner diameter portion on the output side of the internal gear 23A, is centered with respect to the internal gear 23A, and is connected thereto by the bolts 52.

The main bearing 36 includes the outer ring 34a provided at the second housing 34, the inner rings each formed of the internal gear 23A and the cover member 35, and the roller (rolling element) 36a arranged between the outer ring 34a and the inner rings is arranged. The main bearing 36 supports the internal gear 23A and the cover member 35 so as to be rotatable relative to the second housing 34 .

In the silk hat type flexural engagement type gear device 1</b>A having the above configuration, the same effects as the flexural engagement type cylindrical gear device 1 in the first embodiment can be obtained.

Namely, since the internal gear 23A and the cover member 35 are arranged adjacent to and connected to each other in the axial direction, and the inner rings of the main bearing 36 are formed of the internal gear 23A and the cover member 35, respectively, the device can be configured more compact in the axial direction than when the internal gear 23A alone forms the inner ring of the main bearing 36 (see Fig 2 ) .

[Additional]

The embodiments of the present invention have been described above; however, the present invention is not limited to the embodiments and modification examples thereof.

For example, in the first embodiment, the first inner ring rolling surface 23 a is provided on an outer periphery of the second internal gear 23 and the second inner ring rolling surface 35 a is provided on an outer periphery of the cover member 35 see. However, the second internal gear 23 and the cover member 35 may form the inner rings of the main bearing 36 and need not have a rolling surface of the roller 36a of the main bearing 36, respectively.

In addition, the main bearing 36 may be a four-point contact bearing of which the inner ring may be divided into an output side and a counter-output side, and is not limited to a cross roller bearing. For example, a four point contact ball bearing can be used.

Moreover, in the embodiments, the examples in which the flexural engagement type gear device according to the present invention is applied to a cylindrical type and a silk hat type have been described. However, the flexural engagement type gear device according to the present invention can be similarly applied to a pot type.

In addition, changes may be made to the detailed parts shown in the embodiments without departing from the spirit of the invention.

Reference List

1, 1A

Bending engagement type gear device

10, 10A

shaft generator shaft

10b

contact section

11, 11A

wave generator

12, 12A

external gear

15, 15A

shaft generator bearings

22

First internal gear

22g

teeth

23

Second internal gear

23a

First inner ring rolling surface

23A

internal gear

23b

spigot section

23g

teeth

33

First housing (intermediate element)

34

Second case

35

cover element (adjacent element)

35a

Second inner ring rolling surface

36

main camp

36a

roller

41, 42, 42A

boundary element

51, 52

screw

60, 60A

engine output shaft

63

flange element

121A

Cylindrical section

122A

flange section

123A

spigot section

C

space

O1

axis of rotation

S

space

QUOTES INCLUDED IN DESCRIPTION

This list of the documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• JP 5337008 [0002]

Claims (9)

A flexural engagement type gear device (1, 1A) comprising: a wave generator (11, 11A); an external gear (12, 12A) flexed and deformed by the wave generator (11, 11A); an internal gear (23A); and a main bearing (36) arranged between the internal gear (23A) and a housing, there being provided an adjacent member (35) arranged adjacent to the internal gear (23A) in an axial direction and connected to the internal gear (23A), and Inner rings of the main bearing (36) are each formed of the internal gear (23A) and the adjacent member (35). A flexural engagement type gear device (1, 1A). claim 1 wherein a first inner ring rolling surface (23a) is provided on an outer periphery of the internal gear (23A) and a second inner ring rolling surface (35a) is provided on an outer periphery of the adjacent member (35). A flexural engagement type gear device (1, 1A). claim 1 or 2 wherein the abutting member (35) covers an inner space of the flexural engagement type gear device (1, 1A) in the axial direction. A flexural engagement type gear device (1, 1A). claim 3 wherein a bearing that supports the wave generator (11, 11A) is not arranged at the adjacent member (35). A flexural engagement type gear device (1, 1A). claim 3 or 4 wherein an oil seal (45) sliding against the wave generator (11, 11A) is not arranged at the adjacent member (35). A flexural engagement type gear device (1, 1A) according to any one of Claims 1 until 5 wherein the device is a flexural engagement type gear device (1, 1A) of the cylindrical type including a first internal gear (22) and a second internal gear (23) as the internal gear (23A), the second internal gear (23) the inner ring of the main bearing (36), the first internal gear (22) is integrated with an outer ring of the main bearing (36), the first internal gear (22) and the outer ring of the main bearing (36) are connected via an intermediate element (33), and the intermediate element (33 ) is made of a material different from a material of at least one of the outer ring of the main bearing (36) and the first internal gear (22). A flexural engagement type gear device (1, 1A) according to any one of Claims 1 until 6 wherein a limiting member (41, 42, 42A) is provided which limits movement of a shaft generator bearing (15, 15A) arranged between the shaft generator (11, 11A) and the external gear (12, 12A) in the axial direction, and the restricting member (41, 42, 42A) is provided integrally with a wave generator shaft (10, 10A) containing the wave generator (11, 11A). A flexural engagement type gear device (1, 1A). claim 7 wherein the wave generator shaft (10, 10A) includes a contact portion (10b) protruding in the axial direction to be in contact with the restricting member (41, 42, 42A), and the wave generator (11, 11A) includes a clearance (C) between an axial end surface of the wave generator (11, 11A) and the restricting member (41, 42, 42A). A flexural engagement type gear device (1, 1A) according to any one of Claims 1 until 8th wherein a driven element is connected to the adjacent element (35).

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