CN113280082A - Wave gear device - Google Patents

Abstract

The invention provides a wave gear device. The wave generator has: a first member having a first inner peripheral surface surrounding a central axis; a second member having an outer peripheral surface facing the first inner peripheral surface, the second member being coupled to the input member; a slider that rotates the first member together with the second member while being slidable in a radial direction with respect to the second member; and a rolling bearing located radially outward of the first member and radially inward of the flexible externally toothed gear, one of two members selected from the first member, the second member, and the slider having a first opposing surface, the other having a second opposing surface opposing the first opposing surface, the first opposing surface having a contact surface contactable with the second opposing surface and a separation surface located farther from the second opposing surface than the contact surface.

Description

Wave gear device

Technical Field

The present invention relates to a wave gear device.

Background

Conventionally, a wave gear device having a rigid internally-toothed gear and a flexible externally-toothed gear is known. Such a wave gear device is mainly used as a speed reducer. For example, japanese utility model registration No. 2535495 discloses a conventional reduction gear. The reduction gear disclosed in japanese utility model registration No. 2535495 includes: an annular rigid member; an annular flexible member disposed inside the rigid member; and a wave generator that is fitted inside the flexible member, flexes the flexible member in a radial direction to engage with the rigid member at a plurality of locations, and moves these engagement positions in a circumferential direction.

The wave generator described in japanese utility model registration No. 2535495 has a cam member. The cam member includes an outer cylindrical member, an intermediate cylindrical member fitted slidably in the axial direction inside the outer cylindrical member, and an inner cylindrical member fitted slidably in the axial direction inside the intermediate cylindrical member. These outer cylindrical member, intermediate cylindrical member, and inner cylindrical member are combined in a state in which a so-called oldham structure is formed by three members. In the reduction gear disclosed in japanese utility model registration No. 2535495, the provision of the oldham coupling structure enables the eccentricity of the power input portion to be absorbed.

Patent document 1: japanese utility model registration No. 2535495

However, in the conventional technique, a lubricant is applied to suppress friction between the members constituting the cam member. When the parts are in contact with each other via the lubricant, viscous resistance is generated between the parts. Therefore, due to the viscous resistance between the opposed surfaces of the lubricant, the separation of the opposed surfaces may be suppressed. If the viscous resistance becomes large, separation between the facing surfaces does not occur smoothly, and therefore, it may be difficult to absorb eccentricity.

Disclosure of Invention

The purpose of the present invention is to provide a technique for absorbing eccentricity on the input side in a wave generator.

In order to solve the above problem, a wave gear device includes: a wave generator that rotates about a central axis; a flexible externally toothed gear which is in a cylindrical shape surrounding a central axis, is located radially outside the wave generator, and is deflected into a non-perfect circular shape by the wave generator; and an internal gear disposed radially outward of the flexible externally toothed gear and partially meshing with the flexible externally toothed gear. The flexible externally toothed gear and the internally toothed gear rotate relative to each other due to the difference in the number of teeth. The length of the flexible externally toothed gear in the radial direction changes by the rotation of the wave generator, and the meshing position between the flexible externally toothed gear and the internal gear changes in the circumferential direction around the central axis. The wave generator has: a first member having a first inner peripheral surface surrounding a central axis; a second member having an outer peripheral surface facing the first inner peripheral surface, the second member being coupled to the input member; a slider that rotates the first member together with the second member while being slidable in a radial direction with respect to the second member; and a rolling bearing located radially outward of the first member and radially inward of the flexible externally toothed gear. One of two members selected from the first member, the second member, and the slider has a first opposing surface, and the other has a second opposing surface opposing the first opposing surface. The first opposing surface has a contact surface contactable with the second opposing surface and a separation surface located farther from the second opposing surface than the contact surface.

According to the wave gear device of the first aspect, the first member, the second member, or the slider has the first opposing surface and the second opposing surface that are opposed to each other, and the first opposing surface has the separating surface that is distant from the second opposing surface. Therefore, in the case where the lubricant is interposed between the first opposing surface and the second opposing surface to bring them into contact, the viscous resistance between the two surfaces caused by the lubricant is reduced by the separating surface. Therefore, the second member can be smoothly slid in the radial direction with respect to the first member. Therefore, eccentricity on the input side can be absorbed well.

Drawings

Fig. 1 is a longitudinal sectional view of a wave gear device of a first embodiment.

Fig. 2 is a perspective view (upper stage) and an exploded perspective view (lower stage) showing the oldham coupling as viewed from the axial side.

Fig. 3 is a perspective view showing the oldham coupling viewed from the other side in the axial direction.

Fig. 4 is a perspective view showing the cam viewed from the other side in the axial direction.

Fig. 5 is a perspective view showing a cam of the second embodiment.

Fig. 6 is a perspective view (upper stage) and an exploded view (lower stage) showing a cam of the third embodiment.

Fig. 7 is a longitudinal sectional view showing an enlarged inner portion of the cam of the third embodiment.

Fig. 8 is a longitudinal sectional view showing an enlarged inner portion of a cam of the fourth embodiment.

Fig. 9 is a perspective view showing a cam of the fifth embodiment.

Fig. 10 is a perspective view showing a cam of the sixth embodiment.

Fig. 11 is a perspective view showing a cam of the seventh embodiment.

Fig. 12 is a perspective view showing a cam of the eighth embodiment.

Fig. 13 is a diagram showing a cam of the ninth embodiment.

Fig. 14 is a side view showing a hub of the tenth embodiment.

Fig. 15 is a perspective view showing a plurality of modifications of the slider.

Detailed Description

Hereinafter, embodiments of the present invention will be described with reference to the drawings. The constituent elements described in the embodiment are merely examples, and the scope of the present invention is not limited thereto. In the drawings, the size and number of each part may be exaggerated or simplified as necessary for easy understanding.

In the following description, a direction parallel to the central axis of the wave gear device is referred to as an "axial direction", a direction perpendicular to the central axis of the wave gear device is referred to as a "radial direction", and a direction along an arc centered on the central axis of the wave gear device is referred to as a "circumferential direction". However, the "parallel direction" also includes a substantially parallel direction. The "vertical direction" also includes a substantially vertical direction.

< 1. first embodiment >

Fig. 1 is a longitudinal sectional view of a wave gear device 1 of a first embodiment. The wave gear device 1 has a rigid internally-toothed gear 11, a flexible externally-toothed gear 13, and a wave generator 20.

The wave gear device 1 is a device that shifts an input rotational power by a differential motion (relative rotation) between a rigid internally-toothed gear 11 and a flexible externally-toothed gear 13. The wave gear device 1 is assembled to a joint of a small robot, for example. The wave gear device 1 serves as a speed reduction device that reduces the power obtained from the motor.

The rigid internally toothed gear 11 is an annular member centered on the central axis C shown in fig. 1. The rigidity of the rigid internally-toothed gear 11 is higher than the rigidity of the flexible teeth 133 of the flexible externally-toothed gear 13 described later. Therefore, the rigid internally-toothed gear 11 is substantially rigid. The rigid internally-toothed gear 11 has a plurality of internal teeth 111 on the inner peripheral surface. The plurality of internal teeth 111 are provided at a constant pitch in the circumferential direction. The rigid internally toothed gear 11 is fixed to, for example, a frame of an apparatus on which the wave gear device 1 is mounted.

The flexible externally toothed gear 13 has a cup shape having a flat plate portion 141 and a cylindrical barrel portion 131. The body 131 has a flexible tooth 133 on the outer peripheral surface of one end in the axial direction. The flexible teeth 133 have external teeth 135 (flexible external teeth) on the outer peripheral surface. The flexible teeth 133 are located radially inward of the rigid internally-toothed gear 11. A flat plate portion 141 is connected to the other axial end of the body portion 131.

The flat plate portion 141 is a portion that expands in a radial direction perpendicular to the center axis C. The flat plate portion 141 includes a diaphragm portion 143 and a circular plate portion 145 having an annular plate shape. The diaphragm portion 143 is located closer to the body portion 131 than the disk portion 145, and is located radially outward of the disk portion 145. The axial wall thickness of the diaphragm portion 143 is thinner than the disc portion 145. The diaphragm portion 143 has an annular shape. The disc portion 145 is located radially inward of the diaphragm portion 143 and has a constant thickness. An output shaft for taking out the decelerated power is fixed to the center of the disk portion 145.

The wave generator 20 has a ball bearing 21 and an oldham coupling 23. The ball bearing 21 is fitted inside the flexible tooth portion 133 of the flexible externally toothed gear 13. An oldham coupling 23 is attached to an inner ring of the ball bearing 21. The ball bearing 21 is an example of a rolling bearing located radially outward of the oldham ring 23 (specifically, the cam 30 described later) and radially inward of the flexible externally toothed gear 13 (specifically, the flexible tooth portion 133).

The oldham coupling 23 of the wave generator 20 is connected to the input member 90. The input member 90 rotates about the center axis C. The wave generator 20 rotates about the central axis C at the rotational speed of the input member 90. The flexible tooth portion 133 of the flexible externally toothed gear 13 is cylindrical surrounding the center axis C, is disposed radially outward of the wave generator 20, and is deflected into a non-perfect circle by the rotating wave generator 20. The rigid internally-toothed gear 11 is disposed radially outward of the flexible externally-toothed gear 13, and meshes with the flexible tooth portion 133 portion of the flexible externally-toothed gear 13. The rigid internally-toothed gear 11 and the flexible externally-toothed gear 13 rotate relative to each other due to the difference in the number of teeth. By the rotation of the wave generator 20, the length of the flexible externally toothed gear 13 in the radial direction changes, and the meshing position between the flexible externally toothed gear 13 and the rigid internally toothed gear 11 changes in the circumferential direction around the center axis C.

< Structure of crosshead coupling >

Fig. 2 is a perspective view (upper stage) and an exploded perspective view (lower stage) showing the oldham coupling 23 as viewed from the axial side. Fig. 3 is a perspective view showing the oldham coupling 23 viewed from the other side in the axial direction. Fig. 4 is a perspective view showing the cam 30 viewed from the other side in the axial direction.

The oldham coupling 23 has a cam 30, a hub 40, and a slider 50. The cam 30 is annular. As shown in fig. 1, the cam 30 is embedded in the inner race of the ball bearing 21. The cam 30 has a first inner peripheral surface 31 surrounding the center axis C. The first inner circumferential surface 31 is formed with a through hole 311 that penetrates the cam 30 in the axial direction. As shown in fig. 1 and 4, the cam 30 has a side surface 33 (third side surface) facing the other side in the axial direction.

As shown in fig. 1 and 2, the hub 40 has a cylindrical portion 41 and an opposing portion 43. The cylindrical portion 41 is cylindrical and surrounds the central axis C. An input member 90 is inserted inside the cylindrical portion 41. The cylindrical portion 41 is coupled to the input member 90 via keys. That is, the wave generator 20 is coupled to the input member 90 via the hub 40. When the input member 90 rotates, the hub 40 rotates about the center axis C.

The cylindrical portion 41 of the hub 40 has an outer circumferential surface 411 facing radially outward. The cylindrical portion 41 is inserted into the through hole 311 of the cam 30. Thereby, the outer peripheral surface 411 faces the first inner peripheral surface 31 of the cam 30. The outer diameter of the cylindrical portion 41 is slightly smaller than the inner diameter of the through hole 311 of the cam 30. Therefore, a radial small gap is formed between the first inner circumferential surface 31 and the outer circumferential surface 411.

The facing portion 43 of the hub 40 is a flange-like portion extending radially outward from the other axial end of the cylindrical portion 41. As shown in fig. 1 and 2, the facing portion 43 of the hub 40 has a side surface 45 (fourth side surface) facing one axial side.

The slider 50 is a member for rotating the cam 30 together with the hub 40 about the center axis C while being slidable in the radial direction with respect to the hub 40. The slider 50 has an annular slider main body 51. The slider main body portion 51 is located between the cam 30 and the facing portion 43 of the boss 40 in the axial direction. The slider main body portion 51 has a second inner peripheral surface 511 surrounding the center axis C. The second inner peripheral surface 511 is formed with a through hole 513 penetrating the slider main body 51 in the axial direction. The cylindrical portion 41 of the hub 40 is inserted into the through hole 513. Thereby, the second inner circumferential surface 511 and the outer circumferential surface 411 of the cylindrical portion 41 radially face each other.

The outer diameter of the cylindrical portion 41 of the hub 40 is slightly smaller than the inner diameter of the through hole 513 of the slider 50. Therefore, a radial small gap is formed between the outer circumferential surface 411 and the second inner circumferential surface 511.

The slider body 51 has a side surface 53 (first side surface) facing one axial side. The side surface 53 is provided with a pair of first protrusions 54, 54 protruding to one axial side. The pair of first protrusions 54, 54 are located radially outward of the center axis C and are provided at positions facing each other across the center axis C.

The side surface 53 (first side surface) of the slider body 51 faces the side surface 33 (third side surface) of the cam 30. The side surface 33 is provided with a pair of slide grooves 55, 55 (first slide grooves) recessed toward one axial side. The pair of slide grooves 55, 55 are provided at positions facing each other across the center axis C, and extend in mutually parallel radial directions. The slide grooves 55 are provided in a one-to-one correspondence relationship with the first protrusions 54. The width of the first projection 54 in the circumferential direction is slightly smaller than the groove width of the corresponding slide groove 55.

As shown in fig. 1, the slider main body portion 51 has a side surface 57 (second side surface) facing the other side in the axial direction. The side surface 57 is provided with a pair of second protrusions 58, 58 protruding toward the other side in the axial direction. The pair of second protrusions 58, 58 are located radially outward of the center axis C and are provided at positions facing each other across the center axis C.

The side surface 57 (second side surface) of the slider body 51 faces the side surface 45 (fourth side surface) of the facing portion 43 of the boss 40. The side surface 45 is provided with a pair of slide grooves 59 and 59 (second slide grooves) recessed toward the other axial side. In the example shown in fig. 2, the slide groove 59 is a notch that penetrates the opposing portion 43 in the axial direction. The pair of slide grooves 59, 59 are provided at positions facing each other across the center axis C, and extend in mutually parallel radial directions. The slide grooves 59 are provided in a one-to-one correspondence relationship with the second protrusions 58. The width of the second projection 58 in the circumferential direction is slightly smaller than the groove width of the corresponding slide groove 59.

The first protrusion 54 of the slider 50 is inserted into the corresponding sliding groove 55 of the cam 30. Thereby, the cam 30 is engaged with the slider 50 in the circumferential direction, and the cam 30 rotates together with the slider 50. The first convex portion 54 slightly slides in the radial direction inside the slide groove 55 while being guided by the slide groove 55. Therefore, the cam 30 can slightly slide relative to the slider 50 in the direction in which the slide groove 55 extends. The axial length of the first projection 54 is shorter than the axial depth of the corresponding slide groove 55. When the first protrusion 54 of the slider 50 is inserted into the sliding groove 55 of the cam 30, the side surface 53 of the slider 50 contacts the side surface 33 of the cam 30.

In addition, the second convex portion 58 of the slider 50 is inserted into the corresponding slide groove 59. Then, the boss 40 and the slider 50 are engaged in the circumferential direction. That is, when the hub 40 rotates about the central axis C, the slider 50 also rotates about the central axis C. The second projection 58 slightly slides in the radial direction inside the slide groove 55 while being guided by the slide groove 59. Therefore, the cam 30 can slightly slide relative to the slider 50 in the direction in which the slide groove 59 extends. The axial length of the second projection 58 is shorter than the axial depth of the corresponding slide groove 59. When the second protrusion 58 of the slider 50 is inserted into the sliding groove 59 of the hub 40, the side surface 57 of the slider 50 contacts the side surface 45 of the hub 40.

The direction in which the pair of slide grooves 59, 59 extend is perpendicular to the direction in which the pair of slide grooves 55, 55 extend. Therefore, the cam 30 can slightly slide in all radial directions relative to the hub 40 by the slider 50. The first convex portion 54 may be provided on the side surface 33 of the cam 30, and the slide groove 55 may be provided on the side surface 53 of the slider 50. The second projection 58 may be provided on the side surface 45 of the boss 40, and the slide groove 59 may be provided on the side surface 57 of the slider 50.

The first inner peripheral surface 31 of the cam 30 is provided with three inner grooves 35 recessed radially outward. The number of the inner slots 35 is not limited to three, and may be 1, two, or four or more. The inner groove 35 has a ring shape extending in the circumferential direction. The three inner slots 35 are provided at axially spaced intervals.

As shown in fig. 4, a pair of slide grooves 55 are provided so as to radially cross the side surface 33. Therefore, each of the slide grooves 55 is connected to the inner groove 35 on the other axial side of the three inner grooves 35.

A lubricant is present between the mutually facing surfaces of the cam 30, the hub 40 and the slider 50. For example, a lubricant is present between the first inner circumferential surface 31 of the cam 30 and the outer circumferential surface 411 of the hub 40. Therefore, the surfaces of the first inner peripheral surface 31 other than the inner grooves 35 serve as contact surfaces that contact the outer peripheral surface 411 of the hub 40 via the lubricant. On the other hand, the inner surface of the inner groove 35 is a separating surface located at a position farther from the outer peripheral surface 411 than the contact surface. The first inner peripheral surface 31 is an example of a first opposing surface, and the outer peripheral surface 411 is an example of a second opposing surface.

By providing the inner groove 35, the contact between the first inner peripheral surface 31 and the outer peripheral surface 411 is divided. Therefore, the viscous resistance between the first inner peripheral surface 31 and the outer peripheral surface 411 caused by the lubricant is mitigated. Accordingly, the first inner peripheral surface 31 can be easily separated from the outer peripheral surface 411 in the radial direction, and therefore the hub 40 can be smoothly slid in the radial direction with respect to the cam 30.

As shown in fig. 2, four protrusions 531 slightly protruding toward one axial side are provided on the side surface 53 of the slider 50. Each convex portion 531 has a flat contact surface 533 facing one axial side. The contact surface 533 is located on the other axial side than the axial end of the first projection 54. The four contact surfaces 533 are located on the same plane perpendicular to the axial direction, and are arranged at equal intervals in the circumferential direction around the central axis C. That is, the four contact surfaces 533 are separated in the circumferential direction.

The side 53 of the slider 50 has a parting surface 535. The separating surface 535 is located on the periphery of the contact surface 533 of the side surface 53, and is located at a position separated from the side surface 33 of the cam 30 toward the other axial side than the contact surface 533. In this way, by providing the contact surfaces 533 on the side surface 53 to be separated from each other, the separation surface 535 is provided between the contact surfaces 533, 533 adjacent in the circumferential direction. The side surface 53 is an example of a first opposing surface. The side surface 33 of the cam 30 facing the side surface 53 is an example of the second facing surface.

The side 53 of the slider 50 contacts the side 33 of the cam 30 at four contact surfaces 533. In addition, the separating surface 535 is separated from the side surface 33 in a state where the four contact surfaces 533 are in contact with the side surface 33. Therefore, in the case where the lubricant exists between the side surface 53 and the side surface 33, the contact between the side surface 53 and the side surface 33 via the lubricant is divided by the dividing surface 535. Accordingly, since the viscous resistance between the side surface 53 and the side surface 33 due to the lubricant is reduced, the slider 50 can be smoothly slid in the radial direction with respect to the cam 30. Therefore, the oldham coupling 23 can absorb the eccentricity of the input member 90 well.

The side 53 of the slider 50 contacts the side 33 of the cam 30 at four separate contact surfaces 533. This can suppress the side surface 53 from inclining in the axial direction while contacting the side surface 33.

Although not shown, a plurality of protrusions 531 may be provided on the other side surface 57 in the axial direction of the slider 50, similarly to the side surface 53. By providing the plurality of protrusions 531 on the side surface 57, a parting surface distant from the side surface 45 of the hub 40 can be provided on the side surface 57. Thus, the viscous resistance between the side surface 57 and the side surface 45 caused by the lubricant is alleviated. This enables smooth sliding of the hub 40 in the radial direction with respect to the slider 50.

< 2. second embodiment >

Next, a second embodiment will be explained. In the following description, elements having the same functions as those of the elements already described are denoted by the same reference numerals or reference numerals with alphabetical characters added thereto, and detailed description thereof may be omitted.

Fig. 5 is a perspective view showing a cam 30a of the second embodiment. The slide groove 55a provided on the side surface 33 of the cam 30a of the second embodiment differs from the cam 30 shown in fig. 4 in that it has a wall portion 551 on the radially inner side. The cam 30a has three inner grooves 35, similarly to the cam 30. Of the three inner grooves 35, the inner groove 35 located on the other side in the axial direction is annular in shape like the other inner grooves 35, and is not connected to the slide groove 55 a.

When the cam 30a is applied to the oldham coupling 23, the inner groove 35 reduces viscous resistance between the first inner peripheral surface 31 and the outer peripheral surface 411 of the hub 40 due to the lubricant, as in the case of applying the cam 30. Therefore, the hub 40 can be smoothly slid in the radial direction with respect to the cam 30.

< 3. third embodiment >

Fig. 6 is a perspective view (upper stage) and an exploded view (lower stage) showing the cam 30b of the third embodiment. Fig. 7 is a longitudinal sectional view showing an enlarged inner portion of the cam 30b of the third embodiment. As shown in fig. 6, the cam 30b has a ring member 37 and a cam main body portion 39. The ring member 37 is annular and has a third inner peripheral surface 371 surrounding the central axis C. The cam body 39 is annular and has an annular recess 391 recessed toward one axial side at the center on the other axial side. The annular recess 391 is a portion to which the ring member 37 is attached.

The cam main body portion 39 has a side surface 392 facing the other axial side. The side surface 392 constitutes the side surface 33 of the cam 30b opposed to the side surface 53 of the slider 50. The outer diameter of the ring member 37 is slightly larger than the inner diameter of the annular recess 391, for example. The ring member 37 is held by the cam main body 39 by being pressed into the annular recess 391, for example. The ring member 37 may be fixed to the cam body 39 by using another member.

The inner diameter of the ring member 37 is substantially the same as the inner diameter of the cam main body 39 on the one axial side of the annular recess 391. As shown in fig. 6 and 7, the third inner peripheral surface 371 of the ring member 37 and the inner peripheral surface 393 of the cam body 39 together constitute the first inner peripheral surface 31 of the cam 30 b.

As shown in fig. 6, the cam 30b has an inner slot 35. The inner groove 35 has an annular shape extending in the circumferential direction. As shown in fig. 7, the shape of the inner groove 35 when cut along a plane perpendicular to the axial direction (hereinafter referred to as "sectional shape") is a triangular shape whose width gradually decreases outward in the radial direction. Specifically, the inner groove 35 is formed by the inclined surface 373 of the ring member 37 and the inclined surface 395 of the cam main body 39. The inclined surface 373 is provided at an end portion of the third inner peripheral surface 371 of the ring member 37 on one axial side, and is inclined radially outward toward the one axial side. The inclined surface 395 of the cam main body 39 is provided at the other end in the axial direction of the inner circumferential surface 393 and is inclined radially outward toward the other end in the axial direction.

The ring member 37 has an inclined surface 375. The inclined surface 375 is provided at the other axial end of the third inner circumferential surface 371 and is inclined radially outward toward the other axial end. The inclined surfaces 373, 375 have a shape symmetrical with respect to a plane passing through the axial center of the ring member 37 and perpendicular to the central axis C. Therefore, when the ring member 37 is attached to the cam body 39, either one of the inclined surfaces 373 and 375 may face the cam body 39.

Even when the cam 30b is applied to the oldham coupling 23, the inner groove 35 reduces viscous resistance between the first inner peripheral surface 31 and the outer peripheral surface 411 of the hub 40 due to the lubricant, as in the case of applying the cam 30. Therefore, the hub 40 can be smoothly slid in the radial direction with respect to the cam 30 b.

As shown in fig. 7, the width of the ring member 37 in the axial direction is smaller than the width of the annular recess 391 of the cam main body portion 39. Therefore, when the ring member 37 is mounted in the annular recess 391, the end surface of the other axial side of the ring member 37 is positioned on one radial side of the side surface 392 of the cam main body 39. Therefore, in the oldham coupling 23, the end surface of the ring member 37 is away from the side surface 53 of the slider 50. By thus separating the end surface of the ring member 37 from the slider 50, the contact area between the cam 30b and the slider 50 is reduced. Thus, the viscous resistance of the lubricant interposed between the cam 30b and the slider 50 is alleviated. Therefore, the hub 40 can be smoothly slid in the radial direction with respect to the cam 30 b.

< 4. fourth embodiment >

Fig. 8 is a longitudinal sectional view showing an enlarged inner portion of the cam 30c of the fourth embodiment.

The cam 30c of the fourth embodiment has a ring member 37 and a cam main body 39, similarly to the cam 30b of the third embodiment. However, the ring member 37 has the inner groove 35 on the third inner peripheral surface 371. The cam main body 39 has an inner groove 35 in the inner circumferential surface 393. Thus, as shown in fig. 8, the cam 30c has three inner slots 35. In the case of the cam 30c, since the plurality of inner grooves 35 are provided, the viscous resistance of the lubricant between the cam 30 and the hub 40 is further reduced as compared with the cam 30 b.

< 5. fifth embodiment >

Fig. 9 is a perspective view showing a cam 30d of the fifth embodiment. The cam 30d has the same structure as the cam 30 shown in fig. 4. However, the cam 30d is different from the cam 30 in that four inner grooves 35a extending in the axial direction are provided in the first inner peripheral surface 31. The four inner grooves 35a are arranged at equal intervals in the circumferential direction. The width of the inner groove 35a is the same as the width of the slide groove 55. The cross-sectional shape of the inner groove 35a is a substantially quadrangular shape with rounded bottom sides.

When the cam 30d is applied to the oldham coupling 23, the viscosity resistance of the lubricant interposed between the cam 30d and the hub 40 is reduced by the plurality of inner grooves 35a, as in the case of the cam 30. Therefore, the hub 40 can be smoothly slid in the radial direction with respect to the cam 30 d.

< 6. sixth embodiment >

Fig. 10 is a perspective view showing a cam 30e of the sixth embodiment. The cam 30e has an axially extending inner groove 35b on the first inner peripheral surface 31, similar to the cam 30d shown in fig. 9 in this regard. However, the cam 30e has eight inner grooves 35b arranged at equal intervals in the circumferential direction. The cross-sectional shape of the inner groove 35b is a quadrangle.

When the cam 30e is applied to the oldham coupling 23, the viscosity resistance of the lubricant interposed between the cam 30e and the hub 40 is reduced by the plurality of inner grooves 35b, as in the case of the cam 30 d. Therefore, the hub 40 can be smoothly slid in the radial direction with respect to the cam 30 e.

< 7. seventh embodiment >

Fig. 11 is a perspective view showing a cam 30f of the seventh embodiment. The cam 30f has an axially extending inner groove 35c on the first inner peripheral surface 31, similarly to the cam 30d shown in fig. 9. However, the cam 30f has 16 inner grooves 35c arranged at equal intervals in the circumferential direction. The cross-sectional shape of the inner groove 35c is triangular. The inner slots 35c are shallower than the inner slots 35a shown in fig. 9 or the inner slots 35b shown in fig. 10.

When the cam 30f is applied to the oldham coupling 23, the plurality of inner grooves 35b reduce the viscous resistance between the cam 30f and the hub 40 due to the lubricant, as in the case of the cam 30 d. Therefore, the hub 40 can be smoothly slid in the radial direction with respect to the cam 30 f.

< 8 > eighth embodiment

Fig. 12 is a perspective view showing a cam 30g of the eighth embodiment. The cam 30g has a plurality of inner grooves 35d having a triangular sectional shape on the first inner peripheral surface 31, similarly to the cam 30f shown in fig. 11. However, the direction in which the inner groove 35d of the cam 30g extends has both circumferential and axial components. That is, the inner slot 35d extends in both the circumferential direction and the axial direction.

When the cam 30g is applied to the oldham coupling 23, the plurality of inner grooves 35c reduce the viscous resistance between the cam 30g and the hub 40 due to the lubricant, as in the case of the cam 30 f. Therefore, the hub 40 can be smoothly slid in the radial direction with respect to the cam 30 g.

< 9. ninth embodiment >

Fig. 13 is a diagram showing a cam 30h of the ninth embodiment. The cam 30h is similar to the cam 30b shown in fig. 6. Specifically, the cam 30h has two ring members 37, 37 and a cam main body portion 39 a. The ring member 37 is the same as the ring member 37 shown in fig. 6 and 7. The cam body 39a is an annular member. Two ring members 37, 37 are attached to the inside of the cam body 39 a. The cam 30h has an annular inner groove 35 extending in the circumferential direction on the first inner circumferential surface 31. The inner groove 35 is a portion formed by two ring members 37, 37 being adjacent to each other in the axial direction, and is located at the boundary between the ring members 37, 37. Specifically, the inner groove 35 is formed by the inclined surface 375 of the ring member 37 on one axial side and the inclined surface 373 of the ring member 37 on the other axial side.

In the case where the cam 30h is applied to the oldham coupling 23, the inner groove 35 reduces the viscous resistance between the cam 30h and the hub 40 due to the lubricant, as in the case of the cam 30 b. Therefore, the hub 40 can be smoothly slid in the radial direction with respect to the cam 30 h.

< 10. tenth embodiment >

Fig. 14 is a side view showing a hub 40a of the tenth embodiment.

The hub 40a has three outer slots 47 in the outer circumferential surface 411. The three outer slots 47 are provided at axially spaced intervals. The outer groove 47 is an annular circumferential groove extending in the circumferential direction.

In the oldham coupling 23, two outer grooves 47 on one axial side of the three outer grooves 47 are positioned to face the first inner peripheral surface 31 of the cam 30. That is, the inner surfaces of the two outer side grooves 47 are the parting surfaces of the oldham coupling 23 away from the first inner peripheral surface 31. Therefore, similarly to the inner grooves 35, the two outer grooves 47 on one axial side can reduce the viscous resistance between the outer peripheral surface 411 and the first inner peripheral surface 31 due to the lubricant.

In the oldham coupling 23, the outer groove 47 located on the other side in the axial direction of the three outer grooves 47 faces the second inner peripheral surface 511 of the slider 50. That is, the inner surface of the outer groove 47 on the other side in the axial direction is a parting surface of the oldham coupling 23 which is distant from the second inner peripheral surface 511. Therefore, the outer groove 47 on the other side in the axial direction reduces the viscous resistance between the outer circumferential surface 411 and the second inner circumferential surface 511 due to the lubricant.

< 11. modification example >

Fig. 15 is a perspective view showing a plurality of modifications of the slider 50. The five sliders 50a to 50e shown in fig. 15 have convex portions having different shapes from the convex portions 531 of the slider 50.

Specifically, the slider 50a has four convex portions 531 a. Each convex portion 531a has a contact surface 533a having a constant circumferential width. The slider 50b has four convex portions 531b arranged at equal intervals in the circumferential direction. The convex portion 531b has a substantially circular contact surface 533 b. The slider 50c has six protrusions 531 c. The convex portion 531c has a rectangular contact surface 533 c. The contact surfaces 533b, 533c are much smaller than the contact surface 533 and smaller than the surface of the first projection 54 facing the other axial side. By reducing the size of the contact surface 533 in this way, the contact area between the side surface 53 and the side surface 33 of the cam 30 can be reduced. Therefore, the viscous resistance between the side surface 53 and the side surface 33 caused by the lubricant can be reduced.

The slider 50d has six protrusions 531 d. The contact surface 533d of the convex portion 531d has an elongated shape extending in the circumferential direction. The slider 50e has one convex portion 531e and two convex portions 531 f. The contact surface 533e of the projection 531e is longer in the circumferential direction and larger in area than the contact surface 533f of the projection 531 f.

In any of the sliders 50a to 50e, the side surfaces 53 are provided with the convex portions 531a to 531f to form the separating surfaces 535. Therefore, even when any of the sliders 50a to 50e is applied to the oldham coupling 23, the parting surface 535 reduces the viscous resistance between the side surface 53 and the side surface 33 due to the lubricant, as in the case of the slider 50.

The present invention has been described in detail, but the above description is illustrative in all aspects, and the present invention is not limited thereto. It is understood that numerous modifications, not illustrated, may be devised without departing from the scope of the invention. The respective configurations described in the embodiments and the modifications may be appropriately combined or omitted as long as they are not contradictory to each other.

Industrial applicability

The present invention can be used for a wave gear device.

Claims (13)

1. A wave gear device having:

a wave generator that rotates about a central axis;

a flexible externally toothed gear which is in a cylindrical shape surrounding a central axis, is located radially outside the wave generator, and is deflected into a non-perfect circular shape by the wave generator; and

an internal gear disposed radially outward of the flexible externally toothed gear and meshing with the flexible externally toothed gear,

the flexible externally toothed gear and the internally toothed gear relatively rotate due to the difference in the number of teeth,

the length of the flexible externally toothed gear in the radial direction changes by the rotation of the wave generator, the meshing position of the flexible externally toothed gear and the internal gear changes in the circumferential direction around the central axis,

the wave generator has:

a first member having a first inner peripheral surface surrounding a central axis;

a second member having an outer peripheral surface facing the first inner peripheral surface, the second member being coupled to the input member;

a slider that rotates the first member together with the second member while being slidable in a radial direction with respect to the second member; and

a rolling bearing located radially outward of the first member and radially inward of the flexible externally-toothed gear,

one of two members selected from the first member, the second member, and the slider has a first opposing surface, and the other has a second opposing surface opposing the first opposing surface,

the first opposing surface has a contact surface contactable with the second opposing surface and a separation surface located farther from the second opposing surface than the contact surface.

2. The wave gear device according to claim 1,

at least one of the first inner peripheral surface and the outer peripheral surface has the contact surface and the separation surface.

3. The wave gear device according to claim 2,

the separating surface includes an inner surface of a groove provided in at least one of the first inner peripheral surface and the outer peripheral surface.

4. The wave gear device according to claim 3,

one or more of the slots comprise a circumferentially extending annular slot.

5. The wave gear device according to claim 4,

one or more of the grooves comprise a plurality of the annular grooves.

6. The wave gear device according to any one of claims 3 to 5,

the first member has:

one or more ring members having an annular shape with a third inner peripheral surface surrounding the central axis; and

a cam body portion that retains the one or more ring members,

the first inner peripheral surface includes the third inner peripheral surface of the one or more ring members.

7. The wave gear device according to claim 6,

the one or more grooves include an axially or circumferentially extending groove provided on the third inner peripheral surface.

8. The wave gear device according to claim 6 or 7,

the one or more ring members comprise two ring members that are axially adjacent,

the one or more slots include a slot at a boundary of the two ring members.

9. The wave gear device according to any one of claims 1 to 8,

the slider has:

a slider body portion that is positioned between the first member and the second member in the axial direction, and that has a second inner peripheral surface that surrounds a central axis and that faces the outer peripheral surface of the second member;

a first protrusion that protrudes to one side in the axial direction from a position away from the central axis on a first side surface on one side in the axial direction of the slider main body; and

a second convex portion that protrudes from a position distant from the central axis toward the other side in the axial direction on a second side surface on the other side in the axial direction of the slider main body portion,

the first member has a first slide groove extending in the radial direction and into which the first projection is inserted,

the second member has:

an opposing portion that opposes the slider main body portion on the other side in the axial direction of the slider main body portion; and

and a second sliding groove provided in the opposing portion, extending in a radial direction intersecting the first sliding groove, and into which the second projection is inserted.

10. The wave gear device according to claim 9,

the first member has a third side surface axially opposed to the first side surface of the slider, and at least one of the first side surface and the third side surface has the contact surface and the separation surface.

11. The wave gear device according to claim 9 or 10,

the second member has a fourth side surface axially opposed to the second side surface of the slider, and at least one of the second side surface and the fourth side surface has the contact surface and the separation surface.

12. The wave gear device according to claim 10 or 11,

the contact surface comprises at least three surfaces separated from each other.

13. The wave gear device according to any one of claims 9 to 12,

the first inner peripheral surface of the first member has a width in the axial direction larger than a width in the axial direction of the second inner peripheral surface of the slider main body portion, and at least one of the first inner peripheral surface and the outer peripheral surface has the contact surface and the separation surface.

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