Speed reduction device

Abstract

To provide a speed reducer capable of achieving reduction in weight and compactification, and capable of suppressing an increase in surface pressure occurring in components of a bearing.SOLUTION: A speed reducer (1) comprises a reduction mechanism having internal gears (21g, 22g) and an external gear (15), an output member (22) that outputs rotation reduced by the reduction mechanism; and a bearing (28) supporting the output member. The bearing (28) has: an inner ring (28i) having an inner ring-side convex surface (Si) that is convex as a whole toward a first radial side, which is one side in a radial direction; an outer ring (28o) having an outer ring-side convex surface (So) that is convex as a whole toward the first radial direction and faces the inner ring-side convex surface (Si); and an intervening member (28k) arranged between the inner ring-side convex surface and the outer ring-side convex surface.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a speed reduction device.

Background Art

[0002] Patent Document 1 shows a speed reduction device including a sliding bearing capable of receiving a radial load and a thrust load. By adopting a sliding bearing, weight reduction and compactification can be achieved.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] A speed reduction device adopting a sliding bearing as in Patent Document 1 has a problem that the surface pressure becomes high at the edge of the sliding surface of the bearing.

[0005] An object of the present invention is to provide a speed reduction device that can achieve weight reduction and compactification and suppress an increase in surface pressure generated in a constituent member of a bearing.

Means for Solving the Problems

[0006] The speed reduction device according to the present invention is a speed reduction device including a speed reduction mechanism having an internal gear and an external gear, an output member that outputs rotation decelerated by the speed reduction mechanism, and a bearing that supports the output member, wherein the bearing has an inner ring having an inner ring side convex surface that is convex as a whole on a first radial side that is one side in the radial direction, has an outer ring that is convex as a whole on the first radial side and has an outer ring side convex surface facing the inner ring side convex surface, An intervening member disposed between the inner ring side convex surface and the outer ring side convex surface; having and further comprising a first member that supports the output member via the bearing and is connected to an external member, the first member being tiltable with respect to the rotation axis of the output member with the bearing as a fulcrum . [Advantages of the Invention]

[0007] According to the present invention, it is possible to provide a lightweight and compact speed reduction device while suppressing an increase in surface pressure generated in the inner ring and outer ring of the bearing. [Brief Description of the Drawings]

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

[0009] Hereinafter, each embodiment of the present invention will be described in detail with reference to the drawings.

[0010] (Embodiment 1) FIG. 1 is a cross-sectional view showing a speed reduction device according to Embodiment 1 of the present invention. In this specification, the direction along the rotation axis O1 is referred to as the axial direction, the rotation direction centered on the rotation axis O1 is referred to as the circumferential direction, and the direction orthogonal to the rotation axis O1 is referred to as the radial direction. Further, the arrangement side of the member where the rotational motion decelerated in the axial direction is output is referred to as the output side, and the opposite side is referred to as the anti-output side.

[0011] The speed reducer 1 of Embodiment 1 is a flexure engagement type gear device, and includes an oscillation body shaft 10, an oscillation body bearing 11, an external gear 15, a first gear member 21 including an internal gear 21g, a second gear member 22 including an internal gear 22g, a casing member 23, a first cover 24, a second cover 25, bearings 26 and 27, a main bearing 28, and stopper rings 16 and 17. Among these, the main bearing 28 corresponds to an example of the bearing according to the present invention. The second gear member 22 corresponds to an example of the output member according to the present invention. The oscillation body shaft 10, the oscillation body bearing 11, the external gear 15, and the internal gears 21g and 22g correspond to an example of the speed reduction mechanism according to the present invention.

[0012] The oscillation body shaft 10 is a hollow cylindrical shaft that rotates about the rotation axis O1, and has an oscillation body 10a whose outer shape in a cross section perpendicular to the rotation axis O1 is non-circular (for example, elliptical), and shaft portions 10b and 10c provided on both axial sides of the oscillation body 10a. The elliptical shape does not necessarily have to be a geometrically exact ellipse, and includes a substantially elliptical shape. The shaft portions 10b and 10c are shafts whose outer shape in a cross section perpendicular to the rotation axis O1 is circular.

[0013] The external gear 15 is a flexible cylindrical member, and teeth are provided on the outer periphery.

[0014] The two internal gears 21g and 22g are arranged side by side in the axial direction and mesh with the external gear 15. One internal gear 21g is configured by providing teeth on a part of the inner periphery of the first gear member 21. The other internal gear 22g is configured by providing teeth on a part of the inner periphery of the second gear member 22.

[0015] The oscillation body bearing 11 is, for example, a roller bearing, and is disposed between the oscillation body 10a and the external gear 15. The oscillation body bearing 11 includes an outer ring 11a and rolling elements 11b. The oscillation body bearing 11 does not have a dedicated inner ring, and the outer peripheral portion of the oscillation body 10a also serves as the inner ring of the oscillation body bearing 11. Note that the oscillation body bearing 11 may separately have an inner ring, or may be configured such that the inner peripheral portion of the external gear 15 also serves as the outer ring without having the outer ring 11a. The oscillation body 10a and the external gear 15 are relatively rotatable via the oscillation body bearing 11. The rolling elements 11b are made of metal.

[0016] The stopper rings 16 and 17 are arranged on both axial sides of the external gear 15 and the vibration body bearing 11, and restrict the axial movement of the external gear 15 and the vibration body bearing 11. The stopper rings 16 and 17 are made of a metal such as a steel material.

[0017] The first cover 24 is connected to the first gear member 21 and covers the outer peripheral portion on the reaction output side of the vibration body shaft 10. The second cover 25 is connected to the second gear member 22 and covers the outer peripheral portion on the output side of the vibration body shaft 10.

[0018] The bearing 26 is, for example, a ball bearing and is interposed between the first cover 24 and the vibration body shaft 10. Through the bearing 26, the first cover 24 rotatably supports the vibration body shaft 10. The bearing 27 is, for example, a ball bearing and is interposed between the second cover 25 and the vibration body shaft 10. Through the bearing 27, the second cover 25 rotatably supports the vibration body shaft 10.

[0019] The casing member 23 is connected to the first gear member 21 and covers the radially outer side of the second gear member 22. The casing member 23 has an output side member 23a and a reaction output side member 23b that are axially separable. The output side member 23a and the reaction output side member 23b are configured to be connectable by a connecting member B1 such as a bolt through connecting holes h1 and h2. The connecting hole h1 is, for example, a through hole having a seating surface for accommodating and supporting the head of a bolt, and the connecting hole h2 is a threaded hole into which the bolt is screwed. Further, the casing member 23 and the first gear member 21 have connecting holes h3, h4, and h21 that communicate with each other and are connectable to an external support member 81. By being connected to the support member 81 by a connecting member B2 such as a bolt through the connecting holes h3, h4, and h21, the output side member 23a and the reaction output side member 23b are connected by co-tightening. The connecting holes h3, h4, and h21 are, for example, through holes through which a connecting member B2 such as a bolt can be inserted.

[0020] The main bearing 28 is interposed between the casing member 23 and the second gear member 22, and the casing member 23 rotatably supports the second gear member 22 via the main bearing 28. The second gear member 22 is rotatably supported via one main bearing 28.

[0021] The main bearing 28 has an inner ring portion 28i provided on the inner peripheral portion of the casing member 23, an outer ring portion 28o provided on the outer peripheral portion of the second gear member 22, and an intervening member 28k interposed between the inner ring portion 28i and the outer ring portion 28o. The casing member 23 and the second gear member 22 are made of a metal such as a steel material, and thus, the inner ring portion 28i and the outer ring portion 28o are also made of a metal such as a steel material. The inner ring portion 28i corresponds to an example of the inner ring according to the present invention. The outer ring portion 28o corresponds to an example of the outer ring according to the present invention.

[0022] The inner ring portion 28i has an inner ring side convex surface Si that is convex as a whole in the radial direction outward. The outer ring portion 28o has an outer ring side convex surface So that is convex as a whole in the radial direction outward. The outer ring side convex surface So and the inner ring side convex surface Si are curved surfaces and face each other.

[0023] The intervening member 28k is a sliding member (bush) that contacts and slides on the outer ring side convex surface So and the inner ring side convex surface Si. As such a sliding member, various materials such as resin, rubber, ceramic, or metal may be applied. The intervening member 28k has a ring-shaped configuration that is continuous in the circumferential direction, but may have a configuration in which one or more locations in the circumferential direction are divided. The outer peripheral surface of the intervening member 28k has a curved surface (a curved surface that is convex as a whole in the radial direction outward) corresponding to the outer ring side convex surface So, and the inner peripheral surface of the intervening member 28k has a curved surface (a curved surface that is convex as a whole in the radial direction outward) corresponding to the inner ring side convex surface Si.

[0024] Note that the distance between the inner ring side convex surface Si and the outer ring side convex surface So may be reduced, and grease (lubricant) may be applied as the intervening member instead of the bush-like intervening member 28k.

[0025] Due to the above-described shapes of the inner ring portion 28i and the outer ring portion 28o, even when a thrust load and a radial load are applied to the main bearing 28, the main bearing 28 can receive the load and support the second gear member 22 rotatably. Further, due to the above-described shapes of the inner ring portion 28i and the outer ring portion 28o, concentration of surface pressure in a part is suppressed, and the maximum surface pressure applied to the inner ring portion 28i and the outer ring portion 28o can be reduced.

[0026] The portion where the casing member 23 is divided into the output-side member 23a and the non-output-side member 23b is positioned so as to intersect the outer ring portion 28o over the entire circumference in the circumferential direction. By dividing the output-side member 23a and the non-output-side member 23b in the middle in the axial direction of the outer ring portion 28o, the intervening member 28k can be easily incorporated between the outer ring portion 28o and the inner ring portion 28i. For example, after incorporating the intervening member 28k outside the inner ring portion 28i of the second gear member 22, the output-side member 23a of the casing member 23 is incorporated into the configuration from the non-output side, and the non-output-side member 23b of the casing member 23 is incorporated from the output side. Then, by connecting the output-side member 23a and the non-output-side member 23b, the casing member 23, the second gear member 22, and the main bearing 28 can be assembled.

[0027] A seal 31 that suppresses movement of the lubricant and dust is provided on the non-output side of the bearing 26 between the first cover 24 and the vibration body shaft 10. A seal 32 that suppresses movement of the lubricant and dust is provided on the output side of the bearing 27 between the second cover 25 and the vibration body shaft 10.

[0028] A seal 33 that suppresses movement of the lubricant and dust is provided on the output side of the main bearing 28 between the casing member 23 and the second gear member 22. The seal 33 is composed of a flexible member such as rubber.

[0029] <Deceleration operation> The speed reducer 1 of Embodiment 1 is supported by a support member 81, for example, when an external support member 81 is connected to a casing member 23 and a first gear member 21. Further, a mating member 82 that transmits the decelerated rotational motion is connected to a second cover 25 and a second gear member 22, and the rotational motion before deceleration is input to the oscillator shaft 10.

[0030] When a rotational motion is input via the oscillator shaft 10, the rotational motion of the oscillator 10a is transmitted to the external gear 15. At this time, the external gear 15 is regulated to a shape along the outer peripheral surface of the oscillator 10a, and when viewed from the axial direction, it is bent into an elliptical shape having a major axis portion and a minor axis portion. Further, the external gear 15 meshes with the internal gear 21g of the first gear member 21 supported by the support member 81 at the major axis portion. For this reason, the external gear 15 does not rotate at the same rotational speed as the oscillator 10a, and the oscillator 10a rotates relatively inside the external gear 15. Along with this relative rotation, the external gear 15 is elastically deformed so that the major axis position and the minor axis position move in the circumferential direction. The period of this deformation is proportional to the rotational period of the oscillator shaft 10.

[0031] When the external gear 15 is elastically deformed, the position where the external gear 15 meshes with the internal gear 21g changes in the rotational direction as the major axis position moves. Here, assuming that the number of teeth of the external gear 15 is 100 and the number of teeth of the internal gear 21g is 102, each time the meshing position makes one revolution, the teeth meshing between the external gear 15 and the internal gear 21g are displaced, and thereby the external gear 15 rotates (spins). With the above number of teeth, the rotational motion of the oscillator shaft 10 is decelerated at a reduction ratio of 100:2 and transmitted to the external gear 15.

[0032] On the one hand, since the external gear 15 also meshes with the other internal gear 22g, the meshing position between the external gear 15 and the internal gear 22g changes in the rotational direction due to the rotation of the vibration generating body shaft 10. On the other hand, since the number of teeth of the internal gear 22g is the same as that of the external gear 15, the external gear 15 and the internal gear 22g do not rotate relative to each other, and the rotational movement of the external gear 15 is transmitted to the internal gear 22g at a reduction ratio of 1:1. By these means, the rotational movement of the vibration generating body shaft 10 is decelerated at a reduction ratio of 100:2 and transmitted to the second gear member 22. Then, this decelerated rotational movement is output to the mating member 82 connected to the second gear member 22.

[0033] During the operation of the reduction device 1, when a thrust load and a radial load occur between the mating member 82 connected to the second gear member 22 and the support member 81 connected to the casing member 23, the main bearing 28 receives the load, and the rotational movement of the reduction device 1 is not inhibited. Further, at this time, it is suppressed that surface pressure concentrates on a part of the inner ring portion 28i and the outer ring portion 28o of the main bearing 28, and high durability performance of the inner ring portion 28i and the outer ring portion 28o is obtained.

[0034] As described above, according to the reduction device 1 of Embodiment 1, the main bearing 28 that supports the second gear member 22 that outputs the decelerated rotation has an inner ring portion 28i having an inner ring side convex surface Si that is convex as a whole toward the radially outer side. Further, the main bearing 28 has an outer ring portion 28o having an outer ring side convex surface So that is convex as a whole toward the radially outer side. And an intervening member 28k is disposed between the inner ring portion 28i and the outer ring portion 28o. Therefore, it is possible for one main bearing 28 to receive the thrust load and the radial load caused by the load generated between the mating member 82 and the support member 81, and it is possible to reduce the weight and size of the main bearing 28. Further, the number of parts of the main bearing 28 can be reduced. Also, due to the outer ring side convex surface So and the inner ring side convex surface Si having the above-described shapes and the intervening member 28k disposed between them, it is suppressed that surface pressure concentrates on a part of the outer ring portion 28o and the inner ring portion 28i, the load-bearing capacity of the main bearing 28 can be increased, and the life of the main bearing 28 can be extended.

[0035] Furthermore, according to the speed reducer 1 of Embodiment 1, the intervening member 28k disposed between the inner ring portion 28i and the outer ring portion 28o of the main bearing 28 is a ring-shaped sliding member. Therefore, compared with a rolling bearing, the main bearing 28 can be configured to be more compact and lighter, and the number of components can be further reduced.

[0036] Furthermore, according to the speed reducer 1 of Embodiment 1, the outer ring side convex surface So and the inner ring side convex surface Si are curved surfaces. Therefore, it is possible to further suppress the concentration of surface pressure on a part of the outer ring side convex surface So and the inner ring side convex surface Si, and the life of the main bearing 28 can be further extended.

[0037] (Embodiment 2) FIG. 2 is a cross-sectional view showing a speed reducer according to Embodiment 2 of the present invention. The speed reducer 1A of Embodiment 2 is configured in the same manner as Embodiment 1 except that the configuration of the main bearing 28A is different. For the components having the same configuration as those in Embodiment 1, the same reference numerals as those in Embodiment 1 are given, and detailed description thereof is omitted. The main bearing 28A corresponds to an example of the bearing according to the present invention.

[0038] The main bearing 28A includes an inner ring portion 28i provided on the inner peripheral portion of the casing member 23, an outer ring portion 28o provided on the outer peripheral portion of the second gear member 22, and an intervening member 28kA intervening between the inner ring portion 28i and the outer ring portion 28o. The outer ring portion 28o and the inner ring portion 28i are as described in Embodiment 1.

[0039] The intervening member 28kA is a group of rolling elements arranged in a plurality of rows in the axial direction. Each rolling element t of the intervening member 28kA is a spherical ball, but it may be a roller. The plurality of rolling elements t are arranged in a row at intervals in the circumferential direction via a retainer, and are arranged in a plurality of rows in the axial direction.

[0040] FIG. 3 is a diagram showing Modification 1 (A) and Modification 2 (B) of the outer ring side convex surface and the inner ring side convex surface. In Embodiment 2, the outer ring side convex surface So of the outer ring portion 28o and the inner ring side convex surface Si of the inner ring portion 28i may be surfaces in which a plurality of curved surfaces Sou and Siu are connected by sides e extending in the circumferential direction, as shown in FIG. 3(A). By arranging the side e at a position shifted from the center of a plurality of rows of rolling elements t where the rolling elements t do not contact, the contact surface pressure is not concentrated in the outer ring portion 28o and the inner ring portion 28i.

[0041] Also, as shown in FIG. 3(B), the outer ring side convex surface So of the outer ring portion 28o and the inner ring side convex surface Si of the inner ring portion 28i are surfaces in which a plurality of curved surfaces Sov and Siv are connected by sides e extending in the circumferential direction. The plurality of curved surfaces Sov and Siv are curved surfaces having curvature in the circumferential direction (surfaces in which the cross-sectional outer shape perpendicular to the rotation axis O1 has curvature), but do not have curvature in the axial direction (the cross-sectional outer shape passing through the rotation axis O1 is a straight line). Further, the intervening member 28kA2 is a group of rolling elements arranged in a plurality of rows in the axial direction, and the plurality of rolling elements t may be rollers. The rolling element t that is a roller may have a diameter corresponding to the distance L between a set of curved surfaces Sov and Siv that face each other among the individual curved surfaces Sov and Siv.

[0042] Since the intervening member 28kA, which is a group of rolling elements, can be integrally handled with the individual rolling elements t held by the retainer, it can be assembled in the same manner as the assembling method of the main bearing 28 described in Embodiment 1.

[0043] <Deceleration operation> The speed reduction device 1A decelerates the rotational motion input to the oscillator shaft 10 by the same operation as the deceleration operation described in Embodiment 1, and outputs the decelerated rotational motion to the mating member 82 via the second gear member 22.

[0044] Also in the speed reducer 1A of Embodiment 2, when a load is generated between the support member 81 and the mating member 82, a thrust load and a radial load may be applied to the main bearing 28A. Even in such a case, due to the shape that is convex as a whole for the outer ring side convex surface So and the inner ring side convex surface Si, the main bearing 28A can receive the load and support the second gear member 22 rotatably. Further, since a large number of rolling elements t come into contact with the inner ring portion 28i and the outer ring portion 28o, concentration of surface pressure at one location is suppressed, and the maximum surface pressure applied to the inner ring portion 28i and the outer ring portion 28o does not increase.

[0045] As described above, according to the speed reducer 1A of Embodiment 2, the main bearing 28A that supports the second gear member 22 that outputs the decelerated rotation has an inner ring portion 28i having an inner ring side convex surface Si that is convex as a whole toward the radially outer side. Further, the main bearing 28A has an outer ring portion 28o having an outer ring side convex surface So that is convex as a whole toward the radially outer side. And an intervening member 28kA is disposed between the inner ring portion 28i and the outer ring portion 28o. Therefore, it is possible to receive the thrust load and the radial load caused by the load generated between the mating member 82 and the support member 81 with one main bearing 28A, and it is possible to reduce the weight and size of the main bearing 28A. Further, the number of parts of the main bearing 28A can be reduced. Also, due to the outer ring side convex surface So and the inner ring side convex surface Si having the above-described shape and the intervening member 28kA disposed therebetween, concentration of surface pressure at one location of the outer ring portion 28o and the inner ring portion 28i is suppressed, the load capacity of the main bearing 28A can be increased, and the life of the main bearing 28A can be extended.

[0046] Furthermore, according to the speed reducer 1A of Embodiment 2, the intervening member 28kA is a group of rolling elements arranged in a plurality of rows in the axial direction. Therefore, the main bearing 28A can be made to have low friction, and the mechanical loss during the rotational operation of the speed reducer 1A can be reduced.

[0047] (Embodiment 3) FIG. 4 is a cross-sectional view showing a speed reducer according to Embodiment 3 of the present invention. The speed reducer 1B of Embodiment 3 is a flexure engagement type gear device, and includes a first gear member 21B including an oscillation body shaft 10B, an oscillation body bearing 11, an external gear 15, and an internal gear 21g, a second gear member 22B including an internal gear 22g, a casing member 23B, a first cover 24, a bearing 26, a main bearing 28B, and stopper rings 16 and 17. Further, the speed reducer 1B includes a seal member 34B for sealing a gap G1 between the first gear member 21B and the casing member 23B in addition to seals 31 to 33. Components similar to those in Embodiment 1 are denoted by the same reference numerals as in Embodiment 1, and detailed description thereof is omitted. Among the above components, the main bearing 28B corresponds to an example of the bearing according to the present invention, the second gear member 22 corresponds to an example of the output member according to the present invention, the oscillation body shaft 10B corresponds to an example of the input shaft according to the present invention, and the oscillation body shaft 10B, the oscillation body bearing 11, the external gear 15, and the internal gears 21g and 22g correspond to an example of the speed reduction mechanism according to the present invention. Further, the casing member 23B corresponds to an example of the first member according to the present invention, and the first gear member 21B corresponds to an example of the second member according to the present invention. The first gear member 21B as the second member is arranged axially corresponding to the casing member 23B as the first member and is a member that synchronizes with the casing member 23B as the first member. That the first member and the second member are synchronized means that if the first member is non-rotating, the second member is non-rotating, and if the first member rotates at a certain rotational speed, the second member also rotates at the same rotational speed.

[0048] The oscillation body shaft 10B is a hollow cylindrical shaft that rotates about the rotation axis O1, and has an oscillation body 10a whose outer shape in a cross section perpendicular to the rotation axis O1 is non-circular (for example, elliptical), and a shaft portion 10b provided on the anti-output side in the axial direction of the oscillation body 10a. The oscillation body shaft 10B is rotatably supported via the bearing 26 and the oscillation body bearing 11.

[0049] The first gear member 21B has a flange portion f21 that can be connected to an external support member, and a connection hole (for example, a through hole) h21B provided in the flange portion f21. Further, the first gear member 21B has a seal seating surface p21 on the output side of the flange portion f21 for disposing the seal member 34B. The seal seating surface p21 is a circumferentially continuous cylindrical surface. The internal gear 21g is the same as that in the first embodiment.

[0050] The second gear member 22B is not particularly limited, but has a central portion that extends radially inward on the output side of the internal gear 22g and covers the output side of the oscillation body shaft 10B. The second gear member 22B has a connection hole (for example, a threaded hole) h22B on the output side, and is connected to an external mating member 82 that outputs a decelerated rotational motion via the connection hole h22B by a connecting member B5 such as a bolt. The internal gear 22g is the same as that in the first embodiment.

[0051] The casing member 23B is a cylindrical member that covers the radially outer side of the second gear member 22B. The casing member 23B has a seal seating surface p23 for disposing the seal member 34B on the non-output side of the outer peripheral surface. The seal seating surface p23 is a circumferentially continuous cylindrical surface. The seal seating surface p23 and the seal seating surface p21 of the first gear member 21B may be cylindrical surfaces having the same radius. The two seal seating surfaces p21 and p23 are arranged adjacent to each other with a gap therebetween. The casing member 23B has a connection hole (for example, a threaded hole) h23 that can be connected to an external support member (corresponding to an external member) 83, and is connected to the support member 83 via a connecting member B6 such as a bolt. The casing member 23B can be inclined with respect to the rotation axis of the second gear member 22B (output member) with the main bearing 28B as a fulcrum.

[0052] The casing member 23B and the first gear member 21B are assembled with a gap in the axial direction therebetween. That is, a gap G1 is provided between the casing member 23B and the first gear member 21B.

[0053] The seal member 34B is a flexible member such as a bellows, covers the gap G1 from the radially outer side, suppresses the discharge of the lubricant from the gap G1, and the entry of dust from the outside into the gap G1. The seal member 34B is ring-shaped, with the output side in contact with the seal seating surface p23 of the casing member 23B and the non-output side in contact with the seal seating surface p21 of the first gear member 21B, and is fixed by the fixtures n1, n2. The seal member 34B can be deformed following the relative displacement between the casing member 23B and the first gear member 21B due to the bellows structure. Note that the seal member 34B is not limited to the bellows structure and may be deformable following the relative displacement between the casing member 23B and the first gear member 21B by elastic deformation or expansion and contraction.

[0054] The seal 33 disposed between the casing member 23B and the second gear member 22 and on the output side of the main bearing 28B has flexibility as described in Embodiment 1. The seal 33 can be deformed following the relative displacement between the casing member 23B and the second gear member 22B by elastic deformation.

[0055] The main bearing 28B has an inner ring portion 28iB provided on the inner peripheral portion of the casing member 23B, an outer ring portion 28oB provided on the outer peripheral portion of the second gear member 22B, and an intervening member 28kB interposed between the inner ring portion 28iB and the outer ring portion 28oB. The casing member 23B and the second gear member 22B are made of a metal such as a steel material, and thus the inner ring portion 28iB and the outer ring portion 28oB are also made of a metal such as a steel material. The inner ring portion 28iB corresponds to an example of the inner ring according to the present invention. The outer ring portion 28oB corresponds to an example of the outer ring according to the present invention.

[0056] The inner ring portion 28iB has an inner ring side convex surface SiB that is convex as a whole toward the radially outer side. The outer ring portion 28oB has an outer ring side convex surface SoB that is convex as a whole toward the radially outer side. The outer ring side convex surface SoB and the inner ring side convex surface SiB are spherical surfaces where the centers of the curvature circles of the outer contour lines in a cross-section perpendicular to the rotation axis O1 and the centers of the curvature circles of the outer contour lines in a cross-section including the rotation axis O1 overlap with a common center point P1 (a single point overlapping with the rotation axis O1). In FIG. 4, the radii of curvature at multiple locations of the inner ring side convex surface SiB and the outer ring side convex surface SoB are indicated by dashed-dotted lines.

[0057] The intervening member 28kB is, as in Embodiment 2, a group of rolling elements arranged in a plurality of rows in the axial direction. Note that the intervening member 28kB may be a sliding member (bush) having curved surfaces where the inner peripheral surface and the outer peripheral surface respectively correspond to the inner ring side convex surface SiB and the outer ring side convex surface SoB, or the inner ring side convex surface SiB and the outer ring side convex surface SoB may be configured to be separated with a slight gap therebetween, and grease may be interposed as an intervening member between them.

[0058] Due to the above-described shapes of the outer ring side convex surface SoB and the inner ring side convex surface SiB, and the configuration in which the casing member 23 and the first gear member 21B are arranged with a gap G1 therebetween, as shown in FIG. 4, the casing member 23 can be arranged to be angle-variable with respect to the first gear member 21B about the center point P1. In other words, the rotation axis O1 of the second gear member 22 that outputs a decelerated rotational motion can be arranged to be angle-variable about the center point P1 with respect to the casing member 23B connected to the support member 83.

[0059] In the speed reduction device 1B of Embodiment 3, when the intervening member 28kB is a group of rolling elements arranged in a plurality of rows, the outer ring side convex surface SoB, the inner ring side convex surface SiB, or both of them are not limited to continuous spherical surfaces, and may include peaks or grooves that extend in the circumferential direction and have angular cross-sections at portions where the rolling elements t do not contact. The same applies to the speed reduction device 1A of Embodiment 2.

[0060] <Deceleration operation> The speed reduction device 1B can reduce the rotational motion input to the oscillating body shaft 10B by the same operation as the speed reduction operation described in the first embodiment, and output the reduced rotational motion to the mating member 82 via the second gear member 22B.

[0061] Also in the speed reduction device 1B of the third embodiment, when a load is generated between the support member 83 and the mating member 82, a thrust load and a radial load may be applied to the main bearing 28B. Even in such a case, due to the shape that is convex as a whole for the outer ring side convex surface SoB and the inner ring side convex surface SiB, the main bearing 28B can receive the load with one bearing and support the second gear member 22B rotatably. Further, since a large number of rolling elements t come into contact with the inner ring portion 28iB and the outer ring portion 28oB, concentration of surface pressure at one location is suppressed, and the maximum surface pressure applied to the inner ring portion 28iB and the outer ring portion 28oB does not increase. Therefore, the load capacity of the main bearing 28B can be increased, and the life of the main bearing 28B can be extended. Further, with the main bearing 28B having the above configuration, it is possible to receive the thrust load and the radial load caused by the load generated between the mating member 82 and the support member 83, while reducing the weight and size of the main bearing 28B. Further, the number of parts of the main bearing 28B can be reduced.

[0062] Furthermore, according to the speed reduction device 1B of the third embodiment, since the outer ring side convex surface SoB and the inner ring side convex surface SiB are spherical surfaces centered on the center point P1, freedom in the rotational direction (including the rotational direction in a direction other than the circumferential direction) centered on the center point P1 can be imparted to the relative arrangement between the outer ring portion 28oB and the inner ring portion 28iB. Therefore, the allowable error in the relative angular arrangement between the outer ring portion 28oB and the inner ring portion 28iB can be increased by the amount of this freedom.

[0063] Furthermore, according to the speed reducer 1B of Embodiment 3, a gap G1 is provided between a casing member 23B that supports the second gear member 22B via a main bearing 28B and a first gear member 21B that supports the vibrator shaft 10B via a bearing 26. Therefore, due to the degree of freedom in the relative arrangement of the outer ring portion 28oB and the inner ring portion 28iB described above and the gap G1, the relative arrangement of the casing member 23B and the second gear member 22B has a degree of freedom in the rotational direction centered on the center point P1 by the amount of the gap G1. Accordingly, a degree of freedom in angular arrangement occurs between the rotation axis O1 of the mating member 82 to which the decelerated rotation is output and an external support member 83 connected to the casing member 23B, and the allowable error in these arrangements can be increased. By increasing the allowable error, the mountability of the speed reducer 1B to an external mechanism is improved.

[0064] Although the first cover 24 directly supports the vibrator shaft 10B via the bearing 26, since the first cover 24 and the first gear member 21B are connected, it can be regarded that the first gear member 21B supports the vibrator shaft 10B via the bearing 26, and it is described as such in the above paragraph.

[0065] Furthermore, according to the speed reducer 1B of Embodiment 3, it has a seal member 34B that seals the gap G1, and the seal member 34B is deformable following the relative displacement between the casing member 23B and the first gear member 21B. Therefore, the seal member 34B can suppress the movement of the lubricant or dust between the inside and outside of the device through the gap G1 without inhibiting the degree of freedom in the relative arrangement of the casing member 23B and the first gear member 21B.

[0066] The above describes each embodiment of the present invention. However, the present invention is not limited to the above embodiments. For example, in the above embodiment, the output members that output the decelerated rotation are the second gear members 22 and 22B, and an example is shown in which the support members that support the output members via the main bearings are the casing members 23 and 23B. However, the present invention is not limited thereto, and other members may be applied as the output member and the support member. For example, if different types of speed reduction mechanisms are employed, other members may be applied as the output member and the support member. Further, even when the same speed reduction mechanism is employed, other members connected to the second gear member may be applied as the output member, or another casing member may cover the outer periphery of the device, so that the internal member located inside the casing member may be applied as the support member.

[0067] In the above embodiment, an example is shown in which the outer ring and the inner ring of the main bearing are formed as the outer ring portion and the inner ring portion on other members. However, the outer ring, the inner ring, or both of them may be separately provided, and the outer ring, the inner ring, or both of them may be fitted to the members located radially outward, radially inward, or both of the main bearing.

[0068] In the above embodiment, an example is shown in which the inner ring side convex surface Si and the outer ring side convex surface So are surfaces that are convex as a whole in the radial direction outward. However, the inner ring side convex surface Si and the outer ring side convex surface So may be surfaces that are convex as a whole in the radial direction inward. Even in this case, one main bearing can receive the thrust load and the radial load, and it is possible to suppress the concentration of surface pressure on a part of the inner ring portion and the outer ring portion of the main bearing, and high durability performance of the inner ring portion and the outer ring portion can be obtained.

[0069] In the above-described Embodiment 3, a component having a gap G1 between a first member (casing member 23B) that supports an output member (second gear member 22B) and a second member (first gear member 21B) that supports an input shaft (oscillator shaft 10B), and a component in which the inner ring side convex surface SiB and the outer ring side convex surface SoB are spherical surfaces were shown in combination. However, a configuration in which a component in which the inner ring side convex surface and the outer ring side convex surface are surfaces other than spherical surfaces and a component having the above-described gap are combined may be applied. When the inner ring side convex surface and the outer ring side convex surface are different from spherical surfaces and are surfaces that provide freedom in the angular arrangement of the inner ring and the outer ring (for example, surfaces having peak portions or groove portions in a range where the rolling element group does not contact), the effects based on the freedom in angular arrangement described in Embodiment 3 can be similarly achieved.

[0070] In the above-described Embodiments 1 to 3, a configuration in which the casing members 23 and 23B are fixed and the second gear members 22 and 22B and the second cover 25 rotate was described as an example. However, the present invention can be similarly applied to a speed reduction device in which the second gear members 22 and 22B and the second cover 25 are fixed and the casing members 23 and 23B rotate. In such a speed reduction device, the casing members 23 and 23B correspond to an example of an output member according to the present invention, and the main bearings 28, 28A, and 28B correspond to an example of bearings that rotatably support the output member.

[0071] In the above-described embodiment, an example in which the speed reduction device is a flexure engagement type gear device was shown. However, the speed reduction device according to the present invention may be any type of speed reduction device as long as it has a speed reduction mechanism including an internal gear and an external gear. For example, the speed reduction device according to the present invention may be a center crank type eccentric swing type speed reduction device, a so-called distribution type eccentric swing type speed reduction device in which two or more shafts having eccentric bodies are arranged offset from the axis of the speed reduction device, or a simple planetary gear device. In the above-described embodiment, an example in which the speed reduction device is a so-called cylindrical flexure engagement type gear device was shown. However, the speed reduction device according to the present invention may be a so-called cup type or silk hat type flexure engagement type gear device. Other details shown in the embodiments can be appropriately changed without departing from the spirit of the invention.

Explanation of Symbols

[0072] 1, 1A, 1B Reduction Gear 10 Oscillator Shaft 15 External Gear 21, 21B First Gear Member 21g Internal Gear 22, 22B Second Gear Member 22g Internal Gear 23, 23B Casing Member 23a Output Side Member 23b Reverse Output Side Member 28, 28A, 28B Main Bearing 28i, 28iB Inner Ring Portion 28o, 28oB Outer Ring Portion 28k, 28kA, 28kB Intervening Member Si, SiB Inner Ring Side Convex Surface So, SoB Outer Ring Side Convex Surface 33 Seal 34B Seal Member G1 Gap

Claims

1. A speed reduction device comprising a speed reduction mechanism having an internal gear and an external gear, an output member that outputs the rotation reduced by the speed reduction mechanism, and a bearing that rotatably supports the output member, wherein the bearing, has an inner ring having an inner ring side convex surface that is convex as a whole on a first radial side which is one side in the radial direction, has an outer ring that is convex as a whole on the first radial side and has an outer ring side convex surface facing the inner ring side convex surface, has an intervening member disposed between the inner ring side convex surface and the outer ring side convex surface, and further comprises a first member that supports the output member via the bearing and is connected to an external member, wherein the first member is tiltable with respect to the rotation axis of the output member with the bearing as a fulcrum, a speed reduction device.

2. The intervening member is a ring-shaped sliding member, The speed reduction device according to claim 1.

3. The intervening member is a group of rolling elements arranged in a plurality of rows in the axial direction, The speed reduction device according to claim 1.

4. The inner ring side convex surface and the outer ring side convex surface include curved surfaces, The speed reduction device according to any one of claims 1 to 3.

5. The curved surface is a spherical surface, The speed reduction device according to claim 4.

6. A second member is provided which is arranged axially opposite to the first member and synchronizes with the first member, wherein there is a gap between the first member and the second member, and a sealing member for sealing the gap is provided, wherein the sealing member is deformable following the relative displacement between the first member and the second member, The speed reduction device according to any one of claims 1 to 5. ​

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