Bearing device and gear device

Abstract

To provide a bearing device and a gear device which can be realized with a simpler structure.SOLUTION: The bearing device 6 includes an outer ring 62, an inner ring 61, a plurality of rolling elements 63, and an annular cage 8. The inner ring 61 is disposed inside the outer ring 62. The plurality of rolling elements 63 are disposed between the outer ring 62 and the inner ring 61. The cage 8 holds the plurality of rolling elements 63 between the outer ring 62 and the inner ring 61. A raceway forming member composed of at least one of the outer ring 62 and the inner ring 61 has a raceway surface 611 on which each of the plurality of rolling elements 63 rolls, and an adjacent surface 612 adjacent to the raceway surface 611 and intersecting the raceway surface 611. The cage 8 can come into contact with both the raceway surface 611 and the adjacent surface 612 of the raceway forming member.SELECTED DRAWING: Figure 12

Description

[Technical Field]

[0001] The present disclosure relates generally to bearings and gearing, and more particularly to bearings and gearing used in gearing. [Background technology]

[0002] Patent Document 1 discloses a gear device including an outer cylinder, an internal member, a first main bearing, and a second main bearing.

[0003] In this gear device, the internal member is partially (or entirely) housed within the external cylinder. The first main bearing and the second main bearing are each fitted into an annular space formed between the external cylinder and the internal member. With the internal member fixed, the external cylinder rotates around a rotation axis corresponding to the central axis of the external cylinder, the first main bearing, and the second main bearing. The second main bearing is spaced a predetermined distance from the first main bearing in the extension direction of the rotation axis.

[0004] Each of the first main bearing and the second main bearing has an inner race, an outer race, and multiple rolling elements. The multiple rolling elements are annularly arranged between the inner race and the outer race, and roll between the inner race and the outer race. Each of the multiple rolling elements is approximately truncated cone. Here, the distance between a first intersection where the load action line of the first main bearing intersects with the rotation shaft and a second intersection where the load action line of the second main bearing intersects with the rotation shaft is set within a predetermined range. This makes the value of the distance between the first intersection and the second intersection sufficiently large, and the gear device has high robustness against external forces that act to bend the rotation shaft. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent Publication No. 2021-1693 Summary of the Invention [Problem to be solved by the invention]

[0006] Incidentally, a bearing device (first main bearing or second main bearing) of a gear device configured as described above may use a cage that holds multiple rolling elements between the inner ring and the outer ring. However, if a separate snap ring or the like is provided to maintain the cage between the inner ring and the outer ring, the structure of the bearing device becomes complicated, which may hinder efforts to make the bearing device more compact and may increase the manufacturing cost of the bearing device, leading to concerns about an increase in the cost of the gear device.

[0007] The present disclosure has been made in view of the above-mentioned circumstances, and aims to provide a bearing device and a gear device that can be realized with a simpler structure. [Means for solving the problem]

[0008] A bearing device according to one aspect of the present disclosure includes an outer ring, an inner ring, a plurality of rolling elements, and an annular cage. The inner ring is disposed inside the outer ring. The plurality of rolling elements are disposed between the outer ring and the inner ring. The cage holds the plurality of rolling elements between the outer ring and the inner ring. A track-forming member consisting of at least one of the outer ring and the inner ring has a raceway surface on which each of the plurality of rolling elements rolls, and an adjacent surface that is adjacent to and intersects with the raceway surface. The cage is capable of contacting both the raceway surface and the adjacent surface of the track-forming member.

[0009] A gear device according to one aspect of the present disclosure includes a first main bearing and a second main bearing comprising the bearing device, a first member, and a second member. The second member is supported relative to the first member via the first main bearing and the second main bearing so as to be rotatable about a rotation axis. [Effects of the Invention]

[0010] The present disclosure has the advantage of being able to provide a bearing device and a gear device that can be realized with a simpler structure. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a perspective view showing a schematic configuration of an actuator including a gear device according to a first embodiment. [Figure 2] FIG. 2 is a schematic exploded perspective view of the gear device as viewed from the input side of the rotary shaft. [Figure 3] FIG. 3 is a schematic exploded perspective view of the gear device as viewed from the output side of the rotary shaft. [Figure 4] FIG. 4 is a schematic cross-sectional view of the gear device. [Figure 5] FIG. 5 is a cross-sectional view taken along line A1-A1 in FIG. 4, showing the gear device. [Figure 6] FIG. 6 is a cross-sectional view taken along line B1-B1 in FIG. 4, showing the gear device. [Figure 7] FIG. 7 is a schematic view of a bearing device used in the gear device, as viewed from the input side of the rotary shaft. [Figure 8] FIG. 8 is a schematic perspective view of the bearing device. [Figure 9] FIG. 9 is a schematic exploded perspective view of the bearing device. [Figure 10] FIG. 10 is a schematic perspective view of the bearing device, with the inner and outer rings omitted. [Figure 11] FIG. 11 is a schematic exploded perspective view of the bearing device, omitting the inner and outer rings. [Figure 12] 12 is a schematic perspective view showing the bearing device taken along the line A1-A1 in FIG. [Figure 13] 13 is a schematic exploded perspective view showing the bearing device taken along the line A1-A1 in FIG. 7. FIG. [Figure 14] FIG. 14 is a schematic exploded view showing the bearing device taken along the line A1-A1 in FIG. [Figure 15] 15 is a cross-sectional view taken along the line A1-A1 in FIG. 7, showing the bearing device. [Figure 16] FIG. 16 is a schematic perspective view of a bearing device according to the second embodiment. [Figure 17]FIG. 17 is a schematic exploded perspective view of the bearing device. [Figure 18] FIG. 18 is a schematic perspective view of the bearing device, omitting the inner and outer rings. [Figure 19] FIG. 19 is a schematic exploded perspective view of the bearing device, omitting the inner and outer rings. [Figure 20] 20 is a schematic perspective view showing the bearing device, taken along a plane corresponding to the cross section along line A1-A1 in FIG. [Figure 21] 21 is a schematic exploded perspective view showing the bearing device, taken along a plane corresponding to the cross section along line A1-A1 in FIG. [Figure 22] 22 is a cross-sectional view showing the bearing device, taken along line A1-A1 in FIG. [Figure 23] FIG. 23 is a schematic perspective view of a bearing device according to the third embodiment. [Figure 24] FIG. 24 is a schematic exploded perspective view of the bearing device. [Figure 25] 25 is a schematic perspective view showing the bearing device, taken along a plane corresponding to the cross section along line A1-A1 in FIG. [Figure 26] 26 is a cross-sectional view showing the bearing device of the same as above, taken along line A1-A1 in FIG. [Figure 27] FIG. 27 is a cross-sectional view showing the bearing device according to the fourth embodiment, taken along line A1-A1 in FIG. [Figure 28] 28 is a cross-sectional view showing the bearing device according to the fifth embodiment, which corresponds to the cross section taken along the line A1-A1 in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0012] (Embodiment 1) (1) Overview An overview of a gear device 1 according to this embodiment will be described below with reference to Figures 1 to 4. All of the drawings referred to in this disclosure are schematic, and the ratios of size and thickness of each component in the drawings do not necessarily reflect the actual dimensional ratios. For example, the tooth shapes, dimensions, number of teeth, etc. of the internal teeth 21 and external teeth 31 in Figures 1 to 4 are merely shown schematically for the purpose of explanation, and are not intended to be limited to the shapes shown in the drawings.

[0013] The gear device 1 according to this embodiment is a gear device including an internal gear 2 and planetary gears 3. In this gear device 1, the planetary gears 3 are arranged inside the annular internal gear 2, and are an internally meshing planetary gear device in which the planetary gears 3 are rotated relative to the internal gear 2 by oscillating the planetary gears 3. The gear device 1 also includes a bearing device 6 having an outer ring 62 and an inner ring 61. The inner ring 61 is arranged inside the outer ring 62 and is supported so as to be rotatable relative to the outer ring 62. In particular, the gear device 1 according to this embodiment is an eccentric oscillating internally meshing planetary gear device known as a distribution type.

[0014] As shown in FIGS. 1 to 4, the gear device 1 according to this embodiment includes multiple (three in this embodiment) crankshafts (eccentric shafts) 7A, 7B, and 7C arranged at positions offset from the axis (rotation axis Ax1) of the internal gear 2. The gear device 1 also includes an input shaft 500 arranged on the axis (rotation axis Ax1) of the internal gear 2 and centered on the rotation axis Ax1, and an input gear 501 formed integrally with the input shaft 500. Crankshaft gears 502A, 502B, and 502C are spline-connected to the multiple crankshafts 7A, 7B, and 7C, respectively. These multiple (three in this embodiment) crankshaft gears 502A, 502B, and 502C are arranged to mesh with the input gear 501. Therefore, when the input shaft 500 is driven, the input gear 501 synchronously drives the crankshafts 7A, 7B, and 7C, thereby oscillating the planetary gear 3.

[0015] The internal gear 2 has internal teeth 21 and is fixed to the outer ring 62. Particularly in this embodiment, the internal gear 2 has an annular gear main body 22 and multiple outer pins 23. The multiple outer pins 23 are rotatably held on an inner circumferential surface 221 of the gear main body 22 and form the internal teeth 21. The planetary gear 3 has external teeth 31 that partially mesh with the internal teeth 21. In other words, the planetary gear 3 is inscribed inside the internal gear 2, and some of the external teeth 31 mesh with some of the internal teeth 21. In this state, when the multiple crankshafts 7A, 7B, and 7C are driven, the planetary gear 3 oscillates, and the meshing position between the internal teeth 21 and the external teeth 31 moves in the circumferential direction of the internal gear 2, and a relative rotation corresponding to the difference in the number of teeth between the planetary gear 3 and the internal gear 2 occurs between the two gears (the internal gear 2 and the planetary gear 3). If the internal gear 2 is fixed, the planetary gear 3 rotates (spins) in accordance with the relative rotation of the two gears. As a result, the planetary gear 3 produces a rotational output that is reduced at a relatively high reduction ratio according to the difference in the number of teeth between the two gears.

[0016] This type of gear device 1 is used so that rotation equivalent to the rotation component of the planetary gear 3 is extracted as rotation of a pair of carriers 18, 19, which are relatively fixed by means such as fitting, to the inner ring 61 of the bearing device 6. As a result, the gear device 1 functions as a gear device with a relatively high reduction ratio, with the input shaft 500 as the input side and the pair of carriers 18, 19 as the output side. Therefore, in the gear device 1 according to this embodiment, the pair of carriers 18, 19 supports multiple crankshafts 7A, 7B, 7C to transmit rotation equivalent to the rotation component of the planetary gear 3 to the pair of carriers 18, 19. The pair of carriers 18, 19 are arranged on both sides of the planetary gear 3 in the axial direction (the direction along the rotation axis Ax1) and rotatably support the crankshafts 7A, 7B, 7C.

[0017] Here, the multiple crankshafts 7A, 7B, and 7C are inserted into multiple openings 33 formed in the planetary gear 3, respectively, and rotate relative to the internal gear 2 as the planetary gear 3 rotates. Each of the crankshafts 7A, 7B, and 7C has an axial portion 71 and an eccentric portion 72 that is eccentric with respect to the axial portion 71. A pair of carriers 18 and 19 rotatably support the axial portions 71 of the crankshafts 7A, 7B, and 7C, and the eccentric portions 72 of the crankshafts 7A, 7B, and 7C are inserted into the openings 33 of the planetary gear 3. When each of the crankshafts 7A, 7B, and 7C rotates around its respective axial portion 71, each eccentric portion 72 rotates eccentrically (moves eccentrically) with respect to its respective axial portion 71. Accordingly, the planetary gear 3 oscillates. As the planetary gear 3 oscillates, the planetary gear 3 partially meshes with the internal gear 2 and rotates relative to the internal gear 2. As a result, the planetary gear 3 rotates about its own central axis while revolving within the internal gear 2 so as to orbit around the rotation axis Ax1. As the planetary gear 3 rotates, the crankshafts 7A, 7B, and 7C revolve around the rotation axis Ax1, and the carriers 18 and 19 supporting the axial centers 71 of the crankshafts 7A, 7B, and 7C rotate in conjunction with the revolution of the crankshafts 7A, 7B, and 7C. In this way, the rotation (rotation component) of the planetary gear 3, excluding the oscillation component (revolution component) of the planetary gear 3, is transmitted to the pair of carriers 18 and 19 by the multiple crankshafts 7A, 7B, and 7C.

[0018] 1, the gear device 1 according to this embodiment, together with a driving source 101, constitutes an actuator 100. In other words, the actuator 100 according to this embodiment includes the gear device 1 and the driving source 101. The driving source 101 generates a driving force for oscillating the planetary gear 3. Specifically, the driving source 101 rotates the input shaft 500 about the rotation axis Ax1, thereby oscillating the planetary gear 3.

[0019] (2) Definition In the present disclosure, "annular" refers to a ring-like shape that forms an enclosed space (region) at least in a plan view, and is not limited to a circular shape (annular ring) such as a perfect circle in a plan view, but may also be, for example, an elliptical shape, a polygonal shape, etc. Furthermore, even if a shape has a bottom, such as a cup-like shape, it is included in the "annular" category as long as the peripheral wall is annular.

[0020] In this disclosure, "revolution" means that an object revolves around an axis of rotation other than the central axis passing through the center (center of gravity) of the object. When an object revolves, the center of the object moves along an orbital path centered on the axis of rotation. Therefore, for example, when an object rotates around an eccentric axis parallel to the central axis passing through the center (center of gravity) of the object, the object revolves around the eccentric axis as the axis of rotation. As an example, the planetary gear 3 revolves within the internal gear 2 by oscillating, so as to revolve around the rotation axis Ax1.

[0021] In addition, in the present disclosure, one side of the rotation axis Ax1 (the left side in FIG. 4) may be referred to as the "output side," and the other side of the rotation axis Ax1 (the right side in FIG. 4) may be referred to as the "input side." In the example of FIG. 4, rotation is imparted to the input shaft 500 from the "input side" of the rotation axis Ax1, and rotation of the pair of carriers 18, 19 is extracted from the "output side" of the rotation axis Ax1. However, the terms "input side" and "output side" are merely labels used for the purpose of explanation and are not intended to limit the positional relationship between the input and output from the perspective of the gear device 1.

[0022] In this disclosure, the term "rotation axis" refers to a virtual axis (straight line) that is the center of rotational motion of a rotating body. In other words, the rotation axis Ax1 is a virtual axis that does not have a physical entity. The input shaft 500 performs rotational motion around the rotation axis Ax1.

[0023] In this disclosure, "internal teeth" and "external teeth" do not refer to a single "tooth," but rather to a set (group) of multiple "teeth." In other words, the internal teeth 21 of the internal gear 2 are made up of a set of multiple teeth arranged on the inner circumferential surface 221 of the internal gear 2 (gear body 22). Similarly, the external teeth 31 of the planetary gear 3 are made up of a set of multiple teeth arranged on the outer circumferential surface of the planetary gear 3.

[0024] (3) Detailed configuration of the gear device The detailed configuration of the gear device 1 according to this embodiment will be described below with reference to FIGS.

[0025] FIG. 1 is a perspective view showing the general configuration of an actuator 100 including a gear device 1. FIG. 1 schematically shows a drive source 101. FIG. 2 is a general exploded perspective view of the gear device 1 as seen from the input side of the rotation axis Ax1. FIG. 3 is a general exploded perspective view of the gear device 1 as seen from the output side of the rotation axis Ax1. FIG. 4 is a general cross-sectional view of the gear device 1. FIG. 5 is a cross-sectional view taken along line A1-A1 in FIG. 4. FIG. 6 is a cross-sectional view taken along line B1-B1 in FIG. 4. However, in FIGS. 5 and 6, hatching is omitted for parts other than crankshafts 7A, 7B, and 7C, even in cross sections.

[0026] (3.1) Overall structure As shown in FIGS. 1 to 4 , the gear device 1 according to this embodiment includes an internal gear 2, a planetary gear 3, a bearing device 6, multiple crankshafts 7A, 7B, and 7C, a pair of carriers 18 and 19, and an input shaft 500. In this embodiment, the gear device 1 further includes an input gear 501, multiple crankshaft gears 502A, 502B, and 502C, a pair of rolling bearings 41 and 42, an eccentric bearing 5, and a case 10. In this embodiment, the components of the gear device 1, such as the internal gear 2, the planetary gear 3, the multiple crankshafts 7A, 7B, and 7C, and the pair of carriers 18 and 19, are made of metals such as stainless steel, cast iron, carbon steel for machine construction, chromium-molybdenum steel, phosphor bronze, or aluminum bronze, or light metals such as aluminum or titanium. The term "metal" (including light metals) used here includes metals that have been subjected to surface treatments such as nitriding.

[0027] In this embodiment, an internal planetary gear device using a trochoidal tooth profile is illustrated as an example of the gear device 1. That is, the gear device 1 according to this embodiment includes an internal planetary gear 3 having a trochoidal curved tooth profile.

[0028] In addition, in this embodiment, as an example, the gear device 1 is used in a state in which the gear body 22 of the internal gear 2, together with the outer ring 62 of the bearing device 6, is fixed to a fixed member such as the case 10. As a result, as the internal gear 2 and the planetary gear 3 rotate relative to each other, the planetary gear 3 rotates relative to the fixed member (such as the case 10).

[0029] Furthermore, in this embodiment, when the gear device 1 is used in the actuator 100, a rotational force is applied as an input to the input shaft 500, and a rotational force is extracted as an output from the pair of carriers 18, 19 to which the inner ring 61 of the bearing device 6 is fixed. In other words, the gear device 1 operates with the rotation of the input shaft 500 as the input rotation and the rotation of the pair of carriers 18, 19 to which the inner ring 61 is fixed as the output rotation. As a result, the gear device 1 can obtain an output rotation that is reduced in speed by a relatively high reduction ratio relative to the input rotation.

[0030] The driving source 101 is a power generating source such as a motor (electric motor). The power generated by the driving source 101 is transmitted to an input shaft 500 in the gear device 1. Specifically, the driving source 101 is connected to the input shaft 500, and the power generated by the driving source 101 is transmitted to the input shaft 500. This enables the driving source 101 to rotate the input shaft 500.

[0031] Furthermore, in the gear device 1 according to this embodiment, as shown in FIG. 4, the input-side rotation axis Ax1 and the output-side rotation axis Ax1 are on the same straight line. In other words, the input-side rotation axis Ax1 and the output-side rotation axis Ax1 are coaxial. Here, the input-side rotation axis Ax1 is the rotation center of the input shaft 500 to which the input rotation is applied, and the output-side rotation axis Ax1 is the rotation center of the inner ring 61 (and the pair of carriers 18, 19) that generates the output rotation. In other words, in the gear device 1, output rotation is obtained that is reduced in speed at a relatively high reduction ratio relative to the input rotation on the same axis.

[0032] As shown in Figures 5 and 6, the internal gear 2 is an annular component having internal teeth 21. In this embodiment, the internal gear 2 has an annular shape, with at least the inner circumferential surface being a perfect circle in a plan view. The internal teeth 21 are formed on the inner circumferential surface of the annular internal gear 2 along the circumferential direction of the internal gear 2. The multiple teeth constituting the internal teeth 21 all have the same shape and are arranged at equal pitches over the entire circumferential area of ​​the inner circumferential surface of the internal gear 2. In other words, the pitch circle of the internal teeth 21 is a perfect circle in a plan view. The center of the pitch circle of the internal teeth 21 is on the rotation axis Ax1. The internal gear 2 has a predetermined thickness in the direction of the rotation axis Ax1. The tooth traces of the internal teeth 21 are all parallel to the rotation axis Ax1. The dimension of the internal teeth 21 in the tooth trace direction is slightly smaller than the dimension in the thickness direction of the internal gear 2.

[0033] As described above, the internal gear 2 has an annular (circular) gear body 22 and a plurality of outer pins 23. The plurality of outer pins 23 are rotatably held on the inner circumferential surface 221 of the gear body 22 and form the internal teeth 21. In other words, the plurality of outer pins 23 function as a plurality of teeth that form the internal teeth 21. Specifically, as shown in FIG. 2 , a plurality of inner circumferential grooves 223 are formed on the inner circumferential surface 221 of the gear body 22 over the entire circumferential area. All of the inner circumferential grooves 223 have the same shape and are arranged at equal pitches. All of the inner circumferential grooves 223 are parallel to the rotation axis Ax1 and are formed over the entire length of the gear body 22 in the thickness direction. The plurality of outer pins 23 are fitted into the plurality of inner circumferential grooves 223 and are combined with the gear body 22. Each of the plurality of outer pins 23 is rotatably held within the inner circumferential groove 223. The gear body 22 is fixed (together with the outer ring 62) to the case 10. Furthermore, the gear body 22 is formed with a plurality of fixing holes 222 (see FIG. 5) for fixing.

[0034] As shown in FIGS. 5 and 6 , the planetary gear 3 is an annular component having external teeth 31. In this embodiment, the planetary gear 3 has an annular shape, with at least the outer circumferential surface being a perfect circle in a plan view. The outer circumferential surface of the annular planetary gear 3 is formed with external teeth 31 along the circumferential direction of the planetary gear 3. The multiple teeth constituting the external teeth 31 all have the same shape and are provided at equal pitches over the entire circumferential area of ​​the outer circumferential surface of the planetary gear 3. In other words, the pitch circle of the external teeth 31 is a perfect circle in a plan view. The planetary gear 3 has a predetermined thickness in the direction of the rotation axis Ax1. All of the external teeth 31 are formed over the entire length of the planetary gear 3 in the thickness direction. The tooth traces of the external teeth 31 are all parallel to the rotation axis Ax1. Unlike the internal gear 2, the planetary gear 3 has the external teeth 31 formed integrally with the main body of the planetary gear 3 using a single metal member.

[0035] The gear device 1 according to this embodiment also includes a plurality of planetary gears 3. Specifically, the gear device 1 includes two planetary gears 3: a first planetary gear 301 and a second planetary gear 302. The two planetary gears 3 are arranged to face each other in a direction parallel to the rotation axis Ax1. In other words, the planetary gears 3 include the first planetary gear 301 and the second planetary gear 302 that are aligned in a direction parallel to the rotation axis Ax1 (axial direction). The first planetary gear 301 and the second planetary gear 302 have the same shape.

[0036] These two planetary gears 3 (first planetary gear 301 and second planetary gear 302) are arranged with a phase difference of 180 degrees around the rotation axis Ax1. In the example of FIG. 4, of the first planetary gear 301 and the second planetary gear 302, the center C1 (center of the pitch circle of the external teeth 31) of the first planetary gear 301 located on the input side of the rotation axis Ax1 (right side in FIG. 4) is shifted (biased) upward in the figure with respect to the rotation axis Ax1. On the other hand, the center C2 (center of the pitch circle of the external teeth 31) of the second planetary gear 302 located on the output side of the rotation axis Ax1 (left side in FIG. 4) is shifted (biased) downward in the figure with respect to the rotation axis Ax1. Here, the distance ΔL1 between the rotation axis Ax1 and the center C1 is the amount of eccentricity of the first planetary gear 301 relative to the rotation axis Ax1, and the distance ΔL2 between the rotation axis Ax1 and the center C2 is the amount of eccentricity of the second planetary gear 302 relative to the rotation axis Ax1. In this way, by arranging the multiple planetary gears 3 evenly in the circumferential direction around the rotation axis Ax1, it is possible to balance the weight and load among the multiple planetary gears 3.

[0037] The centers C1 and C2 of the first planetary gear 301 and the second planetary gear 302 are located at 180-degree rotational symmetry with respect to the rotation axis Ax1. In this embodiment, the eccentricity ΔL1 and the eccentricity ΔL2 are oriented in opposite directions as viewed from the rotation axis Ax1, but their absolute values ​​are the same.

[0038] More specifically, each of the crankshafts 7A, 7B, and 7C has two eccentric portions 72 with respect to one axial portion 71. The eccentricity ΔL0 (see FIGS. 5 and 6) of the center C0 of these two eccentric portions 72 from the center (axial center Ax2) of the axial portion 71 is the same as the eccentricity ΔL1 and ΔL2 of the first planetary gear 301 and the second planetary gear 302 with respect to the rotation axis Ax1, respectively. The multiple crankshafts 7A, 7B, and 7C have a common shape. The multiple crankshaft gears 502A, 502B, and 502C also have a common shape.

[0039] A pair of carriers 18, 19 are disposed on both sides of the first planetary gear 301 and the second planetary gear 302 in the direction parallel to the rotation axis Ax1 (axial direction). When distinguishing between the pair of carriers 18, 19, the carrier 18 located on the input side of the rotation axis Ax1 (right side in FIG. 4) is referred to as the "input side carrier 18," and the carrier 19 located on the output side of the rotation axis Ax1 (left side in FIG. 4) is referred to as the "output side carrier 19." Both ends of each crankshaft 7A, 7B, 7C are held by the pair of carriers 18, 19 via rolling bearings 41, 42. In other words, each crankshaft 7A, 7B, 7C is held by the input side carrier 18 and the output side carrier 19 on both sides of the planetary gear 3 in the direction parallel to the rotation axis Ax1 (axial direction) in a rotatable state.

[0040] An eccentric body bearing 5 is attached to the eccentric portion 72 of each of the crankshafts 7A, 7B, and 7C. Three openings 33 corresponding to the three crankshafts 7A, 7B, and 7C are formed in each of the first planetary gear 301 and the second planetary gear 302. An eccentric body bearing 5 is housed in each of the openings 33. In other words, the first planetary gear 301 and the second planetary gear 302 are each fitted with an eccentric body bearing 5, and the crankshafts 7A, 7B, and 7C are inserted into the eccentric body bearings 5, thereby combining the eccentric body bearings 5 ​​and the crankshafts 7A, 7B, and 7C with the planetary gear 3. When the crankshafts 7A, 7B, and 7C rotate with the eccentric body bearings 5 ​​and the crankshafts 7A, 7B, and 7C combined with the planetary gear 3, the planetary gear 3 oscillates around the rotation axis Ax1.

[0041] According to the configuration described above, when a rotational force is applied as an input to the input shaft 500 and the input shaft 500 rotates about the rotation axis Ax1, the rotational force is distributed from the input gear 501 to the multiple crankshafts 7A, 7B, and 7C. In other words, when the input gear 501 rotates, the three crankshaft gears 502A, 502B, and 502C that are simultaneously meshed with the input gear 501 rotate in the same direction at the same rotational speed. Because the crankshafts 7A, 7B, and 7C are spline-connected to the crankshaft gears 502A, 502B, and 502C, the three crankshafts 7A, 7B, and 7C rotate in the same direction at the same rotational speed, reduced in speed by the gear ratio between the input gear 501 and the crankshaft gears 502A, 502B, and 502C. As a result, the three eccentric portions 72 formed at the same position on the input side of the rotation axis Ax1 on the three crankshafts 7A, 7B, and 7C rotate synchronously, causing the first planetary gear 301 to oscillate. Furthermore, the three eccentric portions 72 formed at the same position on the output side of the rotation axis Ax1 on the three crankshafts 7A, 7B, and 7C rotate synchronously, causing the second planetary gear 302 to oscillate.

[0042] 5 and 6 show the states of the first planetary gear 301 and the second planetary gear 302 at a certain point in time. FIG. 5 is a cross-sectional view taken along line A1-A1 in FIG. 4, showing the first planetary gear 301. FIG. 6 is a cross-sectional view taken along line B1-B1 in FIG. 4, showing the second planetary gear 302. As shown in FIGS. 5 and 6, the centers C1 and C2 of the first planetary gear 301 and the second planetary gear 302 are positioned at approximately 180 degrees rotational symmetry with respect to the rotation axis Ax1. In this embodiment, the eccentricity ΔL1 and the eccentricity ΔL2 are oriented in opposite directions as viewed from the rotation axis Ax1, but their absolute values ​​are approximately the same (both are the eccentricity ΔL0). According to the above-described configuration, the shaft center portion 71 rotates (spins) around the axis Ax2, causing the first planetary gear 301 and the second planetary gear 302 to rotate (execute eccentric motion) around the rotation axis Ax1 with a phase difference of approximately 180 degrees around the rotation axis Ax1. Furthermore, by arranging the multiple planetary gears 3 approximately evenly in the circumferential direction around the rotation axis Ax1, it is possible to balance the weight and load among the multiple planetary gears 3.

[0043] The planetary gear 3 (first planetary gear 301 and second planetary gear 302) configured in this manner is disposed inside the internal gear 2. In a plan view, the planetary gear 3 is formed to be one size smaller than the internal gear 2, and the planetary gear 3 is able to oscillate inside the internal gear 2 when combined with the internal gear 2. Here, external teeth 31 are formed on the outer peripheral surface of the planetary gear 3, and internal teeth 21 are formed on the inner peripheral surface of the internal gear 2. Therefore, when the planetary gear 3 is disposed inside the internal gear 2, the external teeth 31 and the internal teeth 21 face each other.

[0044] Furthermore, the pitch circle of the external teeth 31 is slightly smaller than the pitch circle of the internal teeth 21. When the first planetary gear 301 is inscribed in the internal gear 2, the center C1 of the pitch circle of the external teeth 31 of the first planetary gear 301 is shifted by a distance ΔL1 from the center of the pitch circle of the internal teeth 21 (the rotation axis Ax1). Similarly, when the second planetary gear 302 is inscribed in the internal gear 2, the center C2 of the pitch circle of the external teeth 31 of the second planetary gear 302 is shifted by a distance ΔL2 from the center of the pitch circle of the internal teeth 21 (the rotation axis Ax1).

[0045] Therefore, in both the first planetary gear 301 and the second planetary gear 302, the external teeth 31 and the internal teeth 21 at least partially face each other with a gap therebetween, and if the difference in the number of teeth between the external teeth 31 and the internal teeth 21 is two or more, they do not mesh with each other over the entire circumferential direction. However, since the planetary gear 3 oscillates (revolves) around the rotation axis Ax1 inside the internal gear 2, the external teeth 31 and the internal teeth 21 partially mesh with each other. In other words, as the planetary gears 3 (first planetary gear 301 and second planetary gear 302) oscillate around the rotation axis Ax1, some of the multiple teeth that make up the external teeth 31 mesh with some of the multiple teeth that make up the internal teeth 21, as shown in FIGS. 5 and 6 . As a result, in the gear device 1, it is possible to mesh some of the external teeth 31 with some of the internal teeth 21.

[0046] Here, the number of teeth of the internal teeth 21 of the internal gear 2 is N (N is a positive integer) more than the number of teeth of the external teeth 31 of the planetary gear 3. In this embodiment, as an example, N is "2", and the number of teeth (of the external teeth 31) of the planetary gear 3 is "2" less than the number of teeth (of the internal teeth 21) of the internal gear 2. This difference in the number of teeth between the planetary gear 3 and the internal gear 2 defines the reduction ratio of the output rotation to the input rotation in the gear device 1.

[0047] In addition, in the present embodiment, as an example, the combined thickness of the first planetary gear 301 and the second planetary gear 302 is smaller than the thickness of the gear body 22 of the internal gear 2. Furthermore, the dimension in the tooth trace direction (direction parallel to the rotation axis Ax1) of the combined external teeth 31 of the first planetary gear 301 and the second planetary gear 302 is smaller than the dimension in the tooth trace direction (direction parallel to the rotation axis Ax1) of the internal teeth 21. In other words, in the direction parallel to the rotation axis Ax1, the external teeth 31 of the first planetary gear 301 and the second planetary gear 302 are contained within the range of the tooth trace of the internal teeth 21.

[0048] Here, the first planetary gear 301 and the second planetary gear 302 are internally meshed with the internal gear 2. Therefore, each time the first planetary gear 301 and the second planetary gear 302 oscillate once, a phase shift in the circumferential direction occurs in the first planetary gear 301 and the second planetary gear 302 relative to the internal gear 2 by the difference in the number of teeth (between the internal teeth 21 and the external teeth 31), causing the first planetary gear 301 and the second planetary gear 302 to rotate. This rotation is transmitted to the pair of carriers 18 and 19 as revolutions around the axis (rotation axis Ax1) of the internal gear 2 of each crankshaft 7A, 7B, and 7C. This allows the pair of carriers 18 and 19 to rotate relative to the gear main body (case 10 integrated therewith) about the rotation axis Ax1.

[0049] In short, the gear device 1 according to this embodiment oscillates the planetary gear 3 using multiple crankshafts 7A, 7B, and 7C that are positioned offset from the rotation axis Ax1, and generates rotational output using the oscillation of the planetary gear 3. That is, in the gear device 1, when the planetary gear 3 oscillates and the meshing position between the internal teeth 21 and the external teeth 31 moves in the circumferential direction of the internal gear 2, a relative rotation occurs between the two gears (the internal gear 2 and the planetary gear 3) according to the difference in the number of teeth between the planetary gear 3 and the internal gear 2. Here, if the internal gear 2 is fixed, the planetary gear 3 rotates (spins) in accordance with the relative rotation between the two gears. As a result, a rotational output reduced at a relatively high reduction ratio is obtained from the planetary gear 3 according to the difference in the number of teeth between the two gears.

[0050] The bearing device 6 has an outer ring 62 and an inner ring 61, and is a component for extracting the output of the gear device 1 as rotation of the inner ring 61 relative to the outer ring 62. In addition to the outer ring 62 and the inner ring 61, the bearing device 6 also has a plurality of rolling elements 63 (see FIG. 4). The outer ring 62 and the inner ring 61 are both annular components. The outer ring 62 and the inner ring 61 both have an annular shape that is a perfect circle in a plan view. The inner ring 61 is one size smaller than the outer ring 62 and is disposed inside the outer ring 62. Here, the inner diameter of the outer ring 62 is larger than the outer diameter of the inner ring 61, so a gap is generated between the inner peripheral surface of the outer ring 62 and the outer peripheral surface of the inner ring 61.

[0051] The plurality of rolling elements 63 are arranged in the gap between the outer ring 62 and the inner ring 61. The plurality of rolling elements 63 are arranged side by side in the circumferential direction of the outer ring 62. The plurality of rolling elements 63 are all metal parts of the same shape, and are provided at equal pitches over the entire circumferential area of ​​the outer ring 62.

[0052] More specifically, the gear device 1 according to this embodiment includes a first main bearing 601 and a second main bearing 602, each of which serves as a bearing device 6. That is, the gear device 1 includes a pair of bearing devices 6, each of which includes the first main bearing 601 and the second main bearing 602. Specifically, as shown in FIG. 4, the first main bearing 601 is disposed on the input side (right side in FIG. 4) of the rotation axis Ax1 as viewed from the planetary gear 3, and the second main bearing 602 is disposed on the output side (left side in FIG. 4) of the rotation axis Ax1 as viewed from the planetary gear 3. The pair of bearing devices 6 is configured so that the first main bearing 601 and the second main bearing 602 can withstand any of a radial load, a thrust load (direction along the rotation axis Ax1), and a bending force (bending moment load) against the rotation axis Ax1.

[0053] Here, the first main bearing 601 and the second main bearing 602 are arranged on either side of the planetary gear 3 in a direction parallel to the rotation axis Ax1 (axial direction), facing opposite directions in the direction parallel to the rotation axis Ax1. Here, as an example, the pair of bearing devices 6 are of a "back-to-back combination type" in which the inner rings 61 of the first main bearing 601 and the second main bearing 602 bear loads in the outward thrust direction (direction along the rotation axis Ax1) toward each other. Furthermore, in the gear device 1, the first main bearing 601 and the second main bearing 602 are combined in a state in which an appropriate preload acts on the inner rings 61 by tightening the inner rings 61 in a direction bringing them closer to each other.

[0054] In the gear device 1 according to this embodiment, the input carrier 18 and the output carrier 19 are disposed on either side of the planetary gear 3 in a direction parallel to the rotation axis Ax1, and are coupled to each other through a carrier hole 34 of the planetary gear 3 (see FIG. 4). Specifically, as shown in FIG. 4, the input carrier 18 is disposed on the input side (right side in FIG. 4) of the rotation axis Ax1 as viewed from the planetary gear 3, and the output carrier 19 is disposed on the output side (left side in FIG. 4) of the rotation axis Ax1 as viewed from the planetary gear 3. Inner rings 61 of a pair of bearing devices 6 (first main bearing 601 and second main bearing 602) are fixed to the input carrier 18 and the output carrier 19, respectively. In this embodiment, as an example, the inner ring 61 of the first main bearing 601 is fixed to the input carrier 18. Similarly, the inner ring 61 of the second main bearing 602 is fixed to the output carrier 19.

[0055] The output-side carrier 19 has a plurality of (three, for example) carrier pins 191 (see FIG. 2) that protrude from one surface of the output-side carrier 19 toward the input side of the rotation axis Ax1. These carrier pins 191 respectively pass through a plurality of (three, for example) carrier holes 34 formed in the planetary gear 3, and their tips are fixed to the input-side carrier 18 by carrier bolts 192 (see FIG. 7). A gap is secured between the carrier pins 191 and the inner circumferential surface of the carrier hole 34, and the carrier pins 191 are movable within the carrier hole 34, that is, movable relative to the center of the carrier hole 34. This prevents the carrier pins 191 from coming into contact with the inner circumferential surface of the carrier hole 34 when the planetary gear 3 oscillates.

[0056] With the above configuration, the gear device 1 is used so that rotation equivalent to the rotation component of the planetary gear 3 is extracted as rotation of the input side carrier 18 and the output side carrier 19 to which the inner rings 61 of the pair of bearing devices 6 (first main bearing 601 and second main bearing 602) are fixed. That is, in this embodiment, the relative rotation between the planetary gear 3 and the internal gear 2 is extracted from the input side carrier 18 and the output side carrier 19. In this embodiment, as an example, the gear device 1 is used in a state where the outer rings 62 (see FIG. 4 ) of the pair of bearing devices 6 (first main bearing 601 and second main bearing 602) are fixed to the case 10, which is a fixed member. That is, the planetary gear 3 is connected to the input side carrier 18 and the output side carrier 19, which are rotating members, by multiple crankshafts 7A, 7B, and 7C, and the gear main body 22 is fixed to a fixed member, so that the relative rotation between the planetary gear 3 and the internal gear 2 is extracted from the rotating members (the input side carrier 18 and the output side carrier 19). In other words, in this embodiment, when the planetary gear 3 rotates relative to the gear body 22, the rotational forces of the input side carrier 18 and the output side carrier 19 are extracted as outputs.

[0057] Furthermore, in this embodiment, the case 10 is seamlessly integrated with the gear body 22 of the internal gear 2. In other words, the gear body 22, which is a fixed member, and the case 10 are provided seamlessly and continuously in the direction parallel to the rotation axis Ax1.

[0058] More specifically, the case 10 is cylindrical and forms the outer shell of the gear device 1. In this embodiment, the central axis of the cylindrical case 10 is configured to coincide with the rotation axis Ax1. That is, at least the outer peripheral surface of the case 10 is a perfect circle centered on the rotation axis Ax1 in a plan view (seen from one axial direction). The case 10 is formed into a cylindrical shape with both axial end faces open. The gear body 22 of the internal gear 2 is seamlessly integrated with the case 10, and the case 10 and the gear body 22 are treated as a single component. Therefore, the inner peripheral surface of the case 10 includes the inner peripheral surface 221 of the gear body 22. Furthermore, outer rings 62 of a pair of bearing devices 6 (first main bearing 601 and second main bearing 602) are fixed to the case 10. That is, the outer ring 62 of the first main bearing 601 is fitted and fixed to the inner peripheral surface of the case 10 on the input side of the rotation axis Ax1 (the right side in FIG. 4 ) of the gear body 22. Meanwhile, an outer ring 62 of a second main bearing 602 is fitted and fixed to the inner circumferential surface of the case 10 on the output side (left side in FIG. 4) of the rotation axis Ax1 as viewed from the gear body 22.

[0059] Furthermore, the end face of the case 10 on the input side (right side in FIG. 4) of the rotation shaft Ax1 is closed by the input side carrier 18, and the end face of the case 10 on the output side (left side in FIG. 4) of the rotation shaft Ax1 is closed by the output side carrier 19. Therefore, as shown in FIG. 4, parts such as the planetary gear 3 (first planetary gear 301 and second planetary gear 302), the plurality of outer pins 23, and the eccentric bearing 5 are housed in the space surrounded by the case 10, the input side carrier 18, and the output side carrier 19.

[0060] Each of the multiple (three in this embodiment) crankshafts 7A, 7B, and 7C has an axial portion 71 and two eccentric portions 72. The axial portion 71 has a cylindrical shape, with at least the outer circumferential surface being a perfect circle in a plan view. An axial center Ax2, which is the center of the axial portion 71, is parallel to the rotational axis Ax1. The axial centers Ax2 of the multiple crankshafts 7A, 7B, and 7C are arranged at equal intervals in the circumferential direction on a virtual circle centered on the rotational axis Ax1. Each eccentric portion 72 has a disk shape, with at least the outer circumferential surface being a perfect circle in a plan view. The center (center axis) C0 of each eccentric portion 72 is parallel to the rotational axis Ax1 and is positioned radially offset from the rotational axis Ax1. Here, the distance ΔL0 (see FIGS. 5 and 6) between the axial center Ax2 and the center C0 represents the eccentricity of the eccentric portion 72 relative to the axial portion 71. The eccentric portion 72 has a flange shape that protrudes from the outer circumferential surface of the axial portion 71 at the center in the longitudinal direction (axial direction) of the axial portion 71 over the entire circumference. According to the above-described configuration, the axial portion 71 of each of the crankshafts 7A, 7B, 7C rotates (spins) about the axis Ax2, causing the eccentric portion 72 to perform eccentric motion.

[0061] In this embodiment, the axial portion 71 and the two eccentric portions 72 are integrally formed from a single metal member, thereby realizing seamless crankshafts 7A, 7B, and 7C. The crankshafts 7A, 7B, and 7C having such a shape are combined with the planetary gear 3 together with the eccentric bearing 5. Therefore, when the crankshafts 7A, 7B, and 7C rotate in a state where the eccentric bearing 5 and the crankshafts 7A, 7B, and 7C are combined with the planetary gear 3, the planetary gear 3 oscillates around the rotation axis Ax1.

[0062] The eccentric body bearing 5 has a plurality of rolling elements 51 (see FIG. 4 ) and is a component that absorbs the rotational component of the rotation of the crankshafts 7A, 7B, 7C and transmits only the rotation of the crankshafts 7A, 7B, 7C excluding the rotational component of the crankshafts 7A, 7B, 7C, i.e., only the oscillation component (revolution component) of the crankshafts 7A, 7B, 7C, to the planetary gear 3. The plurality of rolling elements 51 are disposed between the outer peripheral surface of the eccentric portion 72 of each crankshaft 7A, 7B, 7C and the inner peripheral surface of each opening 33 of the planetary gear 3. In other words, the eccentric portion 72 of each crankshaft 7A, 7B, 7C functions as the inner ring of the eccentric body bearing 5, and the inner peripheral surface of each opening 33 of the planetary gear 3 functions as the outer ring of the eccentric body bearing 5.

[0063] When the eccentric bearing 5 and the multiple crankshafts 7A, 7B, and 7C are combined with the planetary gear 3, and each of the crankshafts 7A, 7B, and 7C rotates (spins on its axis), each of the eccentric portions 72 rotates (executes eccentric motion) around the axis Ax2. The planetary gear 3 is installed at a position corresponding to each of the eccentric portions 72 in the direction parallel to the rotation axis Ax1 (axial direction). Therefore, the eccentric motion of each eccentric portion 72 is transmitted to the planetary gear 3 via the eccentric bearing 5, and the planetary gear 3 oscillates around the rotation axis Ax1. In other words, the eccentric motion of the eccentric portions 72 of the crankshafts 7A, 7B, and 7C is transmitted to the planetary gear 3. The eccentric bearing 5 plays a role in mitigating friction and the like that occurs due to the relative rotation caused by the speed difference between the eccentric motion of the eccentric portion 72 of each crankshaft 7A, 7B, 7C (i.e., the rotation of each crankshaft 7A, 7B, 7C) and the revolution of the planetary gear 3, and also plays a role in transmitting power.

[0064] In the gear device 1 configured as described above, a rotational force is applied as an input to the input shaft 500, and the input shaft 500 rotates about the rotation axis Ax1, causing the planetary gear 3 to oscillate (revolve) around the rotation axis Ax1. At this time, the planetary gear 3 is inscribed with the internal gear 2 on the inside of the internal gear 2 and oscillates with some of the external teeth 31 meshing with some of the internal teeth 21. As a result, as the input shaft 500 rotates, the meshing position between the internal teeth 21 and the external teeth 31 moves in the circumferential direction of the internal gear 2. As a result, a relative rotation corresponding to the difference in the number of teeth between the planetary gear 3 and the internal gear 2 occurs between the two gears (the internal gear 2 and the planetary gear 3). The rotation (rotation component) of the planetary gear 3, excluding the oscillation component (revolution component) of the planetary gear 3, is transmitted to the pair of carriers 18 and 19 by the multiple crankshafts 7A, 7B, and 7C. As a result, a rotation output is obtained from the pair of carriers 18, 19, which is reduced in speed at a relatively high reduction ratio in accordance with the difference in the number of teeth between the two gears.

[0065] In the gear device 1 according to this embodiment, as described above, the difference in the number of teeth between the internal gear 2 and the planetary gear 3 determines the reduction ratio of the output rotation to the input rotation in the gear device 1. In other words, if the number of teeth of the internal gear 2 is "V1" and the number of teeth of the planetary gear 3 is "V2," the reduction ratio R1 is expressed by the following formula 1.

[0066] R1=V2 / (V1-V2) (Equation 1) In other words, the smaller the difference in the number of teeth (V1-V2) between the internal gear 2 and the planetary gear 3, the larger the reduction ratio R1. As an example, the number of teeth V1 of the internal gear 2 is 72, the number of teeth V2 of the planetary gear 3 is 70, and the difference in the number of teeth (V1-V2) is 2. Therefore, according to the above formula 1, the reduction ratio R1 is 35. In this case, when viewed from the input side of the rotation axis Ax1, when each of the crankshafts 7A, 7B, and 7C rotates clockwise one revolution (360 degrees) around the axis Ax2 of the shaft center 71 (see FIGS. 5 and 6), the pair of carriers 18 and 19 rotate counterclockwise around the rotation axis Ax1 by the amount of the difference in the number of teeth of 2 (i.e., approximately 10.3 degrees).

[0067] According to the gear device 1 of this embodiment, such a high reduction ratio R1 can be achieved by combining the internal gear 2 and the planetary gears 3. Furthermore, an appropriate reduction ratio can be achieved between the input gear 501 and the multiple crankshaft gears 502A, 502B, 502C depending on the number of teeth of the input gear 501 and the crankshaft gears 502A, 502B, 502C. As a result, the gear device 1 as a whole can achieve a high reduction ratio.

[0068] The gear device 1 only needs to include at least the internal gear 2, the planetary gear 3, the crankshafts 7A, 7B, and 7C, and a pair of carriers 18 and 19, and may further include a spacer 11, for example, as shown in Fig. 4. The spacer 11 is disposed between the pair of planetary gears 3 (first planetary gear 301 and second planetary gear 302) in a direction parallel to the rotation axis Ax1 (axial direction).

[0069] As described above, the gear device 1 according to this embodiment includes the first main bearing 601 and the second main bearing 602 that constitute the bearing device 6, the case (first member) 10, and a pair of carriers (second members) 18, 19. The pair of carriers (second members) 18, 19 are supported relative to the case (first member) 10 via the first main bearing 601 and the second main bearing 602 so as to be rotatable about the rotation axis Ax1. In this embodiment, the case 10 and the pair of carriers 18, 19 rotate relatively via the first main bearing 601 and the second main bearing 602, so the case 10 is an example of a first member, and the pair of carriers 18, 19 are an example of a second member.

[0070] The gear device 1 according to this embodiment, together with the first and second blocks, constitutes a robot joint device. The gear device 1 connects the first and second blocks. The robot joint device functions as a joint device when the first and second blocks rotate relatively around the rotation axis Ax1. Here, the input shaft 500 of the gear device 1 is driven by the drive source 101, causing the first and second blocks to rotate relatively. At this time, the rotation (input rotation) generated by the drive source 101 is reduced in speed at a relatively high reduction ratio in the gear device 1, driving the first or second block with relatively high torque. In other words, the first and second blocks connected by the gear device 1 can perform bending and stretching movements around the rotation axis Ax1.

[0071] The robot joint device is used in a robot such as a horizontal articulated robot (SCARA robot), for example. Furthermore, the robot joint device is not limited to a horizontal articulated robot, but may also be used in, for example, an industrial robot other than a horizontal articulated robot, or a non-industrial robot. Furthermore, the gear device 1 according to this reference example is not limited to a robot joint device, but may also be used in, for example, a wheel device such as an in-wheel motor in a vehicle such as an automated guided vehicle (AGV).

[0072] (3.2) Bearing device configuration Next, the configuration of the bearing device 6 (first main bearing 601 and second main bearing 602) used in the gear device 1 according to this embodiment will be described with reference to Figures 7 to 15. The first main bearing 601 and the second main bearing 602 are bearing devices 6 having a common configuration, so the following description will take as an example the bearing device 6 used as the first main bearing 601 of the first main bearing 601 and the second main bearing 602.

[0073] FIG. 7 is a schematic view of the bearing device 6 as seen from the input side of the rotating shaft Ax1. FIG. 8 is a schematic perspective view of the bearing device 6. FIG. 9 is a schematic exploded perspective view of the bearing device 6. FIG. 10 is a schematic perspective view of the bearing device 6 omitting the inner ring 61 and the outer ring 62. FIG. 11 is a schematic exploded perspective view of the bearing device 6 omitting the inner ring 61 and the outer ring 62. FIG. 12 is a schematic perspective view of the bearing device 6 taken along the line A1-A1 in FIG. 7. FIG. 13 is a schematic exploded perspective view of the bearing device 6 taken along the line A1-A1 in FIG. 7. FIG. 14 is a schematic exploded view of the bearing device 6 taken along the line A1-A1 in FIG. 7. FIG. 15 is a cross-sectional view taken along the line A1-A1 in FIG. 7. However, hatching is omitted even in cross sections in FIGS. 12 to 15.

[0074] As shown in FIGS. 7 to 9 , the bearing device 6 includes an inner race 61, an outer race 62, a plurality of rolling elements 63, and a cage 8. The inner race 61 is disposed inside the outer race 62. The plurality of rolling elements 63 are disposed between the outer race 62 and the inner race 61. The cage 8 is an annular member that holds the plurality of rolling elements 63 between the outer race 62 and the inner race 61. That is, the bearing device 6 according to this embodiment includes the inner race 61, the outer race 62, and the plurality of rolling elements 63, as well as the annular cage 8 for holding the plurality of rolling elements 63.

[0075] Here, the inner ring 61 is formed in an annular shape that forms a perfect circle when viewed from one side (e.g., the input side) of the rotation axis Ax1. The inner ring 61 is fitted into the carrier 18 so that its inner peripheral surface contacts the carrier 18, and is fixed to the carrier 18. The outer ring 62 is formed in an annular shape that forms a perfect circle that is one size larger than the inner ring 61 when viewed from one side (e.g., the input side) of the rotation axis Ax1. The outer ring 62 is fitted into the case 10 so that its outer peripheral surface contacts the case 10, and is fixed to the case 10.

[0076] Furthermore, as described above, the inner diameter of the outer ring 62 is larger than the outer diameter of the inner ring 61, so a gap is generated between the inner peripheral surface of the outer ring 62 and the outer peripheral surface of the inner ring 61. The plurality of rolling elements 63 are arranged in the gap between the inner peripheral surface of the outer ring 62 and the outer peripheral surface of the inner ring 61. The plurality of rolling elements 63 are arranged side by side in the circumferential direction of the outer ring 62, and roll between the outer ring 62 and the inner ring 61.

[0077] Each of the rolling elements 63 is substantially cylindrical (columnar). As shown in FIG. 9, each of the rolling elements 63 includes a first end face 631, a second end face 632, and an outer circumferential surface 633. The first end face 631 and the second end face 632 are substantially coaxial and circular. Each of the rolling elements 63 is disposed with its rolling axis (center axis) tilted relative to the rotation axis Ax1 so that the second end face 632 is located inward (closer to the rotation axis Ax1) than the first end face 631. Each of the rolling elements 63 rolls by rotating about its rolling axis with its outer circumferential surface 633 in contact with the inner circumferential surface of the outer ring 62 and the outer circumferential surface of the inner ring 61. A load action line LL1 (see FIG. 12) of each rolling element 63 passes through the center of the rolling element 63 and extends in a direction perpendicular to the rolling axis.

[0078] Here, the outer peripheral surface of the inner ring 61 has a raceway surface 611 (see FIG. 12) that is inclined with respect to the rotation axis Ax1 so as to be perpendicular to the load action line LL1 of the rolling elements 63. The inner peripheral surface of the outer ring 62 has a raceway surface 621 (see FIG. 12) that is inclined with respect to the rotation axis Ax1 so as to be perpendicular to the load action line LL1 of the rolling elements 63. Each of the multiple rolling elements 63 is held between the inner ring 61 and the outer ring 62 with its outer peripheral surface 633 in contact with the raceway surface 611 of the outer peripheral surface of the inner ring 61 and the raceway surface 621 of the inner peripheral surface of the outer ring 62. In other words, each of the multiple rolling elements 63 moves (rolls) on the raceway surface 611 of the inner ring 61 and the raceway surface 621 of the outer ring 62.

[0079] In this embodiment, the inner ring 61, the outer ring 62, and the rolling elements 63, which are components of the bearing device 6, are made of metals such as stainless steel, bearing steel, carbon steel for mechanical structures, chromium-molybdenum steel, phosphor bronze, or aluminum bronze, or light metals such as aluminum or titanium. The term "metal" (including light metals) used here includes metals that have undergone surface treatments such as nitriding. Furthermore, the surface treatment may include a black oxide treatment (fermite treatment) that forms a black oxide film on the surface. The black oxide treatment is effective in preventing white layer peeling caused by hydrogen embrittlement, which occurs when hydrogen penetrates and is absorbed through the metal surface, and in suppressing creep of the inner ring 61 and the outer ring 62. In other words, one cause of white layer peeling in the bearing device 6 is thought to be hydrogen embrittlement caused by the penetration of hydrogen generated by the decomposition of lubricant (lubricating oil) on the sliding surface into the metal. The black oxide treatment suppresses hydrogen embrittlement and thus prevents white layer peeling.

[0080] The cage 8 is disposed between the outer ring 62 and the inner ring 61. The cage 8 has a plurality of pockets 80 (see FIG. 9 ) in the circumferential direction (the circumferential direction of the outer ring 62). Each of the plurality of pockets 80 is a rectangular through-hole that penetrates the cage 8 in the thickness direction. The plurality of pockets 80 are disposed at equal pitches in the circumferential direction. The cage 8 holds the plurality of rolling elements 63 by accommodating the rolling elements 63 in each of the plurality of pockets 80. The cage 8 holds the plurality of rolling elements 63 in a rollable state, thereby holding the plurality of rolling elements 63 at equal pitches between the outer ring 62 and the inner ring 61. The cage 8 is a molded product made of resin (synthetic resin) or the like.

[0081] 9 to 11, the cage 8 has a plurality of divided members 810 that are divided in the circumferential direction. In other words, the cage 8 is not made up of a single, inseparable part, but is made up of a plurality of divided members 810 that are connected together in the circumferential direction (the circumferential direction of the outer ring 62).

[0082] As described above, the bearing device 6 (first main bearing 601 or second main bearing 602) according to this embodiment includes a cage 8 that holds multiple rolling elements 63 between the inner ring 61 and the outer ring 62. For example, depending on the size of the gear device 1, the main bearing (first main bearing 601 or second main bearing 602) may become larger, and the cage 8 may also become larger. In this embodiment, the cage 8 is not formed as a single unit (a single, inseparable part) but is formed of multiple divided members 810. This makes it possible to maintain high manufacturing precision for the individual divided members 810, which are molded products, and to prevent a decrease in the efficiency of the gear device 1. Furthermore, compared to manufacturing a single-unit cage 8, mold costs and the like can be significantly reduced, and the manufacturing costs of the cage 8 can also be reduced, making it possible to reduce the cost of the gear device 1.

[0083] More specifically, in this embodiment, as an example, the cage 8 has six divided members 810 consisting of first to sixth divided members 811 to 816. The six divided members 810 constitute the retaining member 81. These six divided members 810 are arranged clockwise as viewed from the input side of the rotation axis Ax1 in the following order: first divided member 811, second divided member 812, third divided member 813, fourth divided member 814, fifth divided member 815, and sixth divided member 816. The six divided members 810 are identical parts having a common configuration (shape). Each divided member 810 has a plurality of pockets 80, each of which holds a plurality of rolling elements 63.

[0084] Here, the outer ring 62 and the inner ring 61 are each annular members formed as a continuous unit in the circumferential direction. In other words, while the cage 8 can be divided into multiple parts (divided members 810) in the circumferential direction, the outer ring 62 and the inner ring 61 are each a single unit (one inseparable part) formed as a continuous unit in the circumferential direction. As a result, when the cage 8 is combined with the inner ring 61 and the outer ring 62, the positions of the multiple divided members 810 are stable.

[0085] Moreover, in this embodiment, the cage 8 further includes fastening members 82 that fasten the plurality of divided members 810 together. That is, the plurality of divided members 810 are not arranged separately between the inner ring 61 and the outer ring 62, but are arranged between the inner ring 61 and the outer ring 62 while fastened together by the fastening members 82. This makes it easier to prevent misalignment between the plurality of divided members 810, and also allows the plurality of divided members 810 to be handled as a single member, improving the ease of assembly of the bearing device 6. In this embodiment, as an example, the fastening member 82 is formed in an annular shape.

[0086] Here, the fastening members 82 include embedded portions that are embedded in the plurality of divided members 810. Specifically, as shown in FIGS. 9 and 11 , embedded grooves 83 are formed on the surfaces of the plurality of divided members 810 that face the inner ring 61, over the entire circumferential direction of the cage 8. The fastening members 82 are attached to the plurality of divided members 810 by being embedded (fitted) in the embedded grooves 83. As an example in this embodiment, the fastening members 82 are entirely contained within the embedded grooves 83, thereby forming "embedded portions" in which the fastening members 82 are entirely embedded in the plurality of divided members 810. With this configuration, the amount by which the fastening members 82 protrude from the plurality of divided members 810 can be reduced, and the cage 8 can have a compact appearance.

[0087] Furthermore, at least a portion of the fastening member 82 faces the outer ring 62 or the inner ring 61. In this embodiment, as described above, the entire fastening member 82 serves as an embedded portion and is fitted into the embedding groove 83 formed in the surface of each of the multiple divided members 810 facing the inner ring 61. Here, the fastening member 82 has an exposed surface 84 (see FIG. 12 ) that is exposed from the opening of the embedding groove 83 when fitted into the embedding groove 83, and this exposed surface 84 faces the raceway surface 611 on the outer peripheral surface of the inner ring 61. The exposed surface 84 is inclined with respect to the rotation axis Ax1 so as to be approximately parallel to the raceway surface 611. As a result, the cross-sectional shape of the fastening member 82 forms a rectangular shape (i.e., a pentagonal shape) with corners cut out by the exposed surface 84. The exposed surface 84 facing the raceway surface 611 may come into contact with the raceway surface 611.

[0088] According to this configuration, at least a portion of the fastening member 82 faces the outer ring 62 or the inner ring 61 (the inner ring 61 in this embodiment), and thus the fastening member 82 comes into contact with the outer ring 62 or the inner ring 61, preventing misalignment of the fastening member 82. As a result, it is possible to prevent the fastening of the multiple segment members 810 from being released due to misalignment of the fastening member 82.

[0089] 9 to 11, fastening member 82 has a plurality of small pieces 820 that are divided in the circumferential direction. The division surfaces between the plurality of divided members 810 and the division surfaces of the plurality of small pieces 820 are arranged alternately in the circumferential direction. In other words, the plurality of small pieces 820 and the plurality of divided members 810 are arranged in a staggered pattern in the circumferential direction (the circumferential direction of outer ring 62).

[0090] In this way, in this embodiment, by configuring the fastening member 82 not as a single piece (one integral, inseparable part) but as a plurality of small pieces 820, it is possible to maintain high manufacturing precision for the individual small pieces 820, which are molded products, and suppress a decrease in efficiency of the gear device 1. Furthermore, compared to manufacturing a single fastening member 82, mold costs and the like can be significantly reduced, and the manufacturing costs of the cage 8 can also be reduced, making it possible to reduce the cost of the gear device 1.

[0091] More specifically, in this embodiment, as an example, the cage 8 has six small pieces 820 consisting of first to sixth small pieces 821 to 826. The six small pieces 820 constitute the fastening member 82. These six small pieces 820 are arranged clockwise as viewed from the input side of the rotation axis Ax1 in the order of the first small piece 821, the second small piece 822, the third small piece 823, the fourth small piece 824, the fifth small piece 825, and the sixth small piece 826. The six small pieces 820 are identical parts having a common configuration (shape).

[0092] Specifically, the first small piece 821 is combined so as to straddle the sixth divided member 816 and the first divided member 811, fastening (connecting) the sixth divided member 816 and the first divided member 811. The second small piece 822 is combined so as to straddle the first divided member 811 and the second divided member 812, fastening the first divided member 811 and the second divided member 812. The third small piece 823 is combined so as to straddle the second divided member 812 and the third divided member 813, fastening the second divided member 812 and the third divided member 813. The fourth small piece 824 is combined so as to straddle the third divided member 813 and the fourth divided member 814, fastening the third divided member 813 and the fourth divided member 814. The fifth small piece 825 is combined so as to straddle the fourth divided member 814 and the fifth divided member 815, and fastens the fourth divided member 814 and the fifth divided member 815. The sixth small piece 826 is combined so as to straddle the fifth divided member 815 and the sixth divided member 816, and fastens the fifth divided member 815 and the sixth divided member 816.

[0093] Here, fastening member 82 (plurality of small pieces 820) is configured to be able to be fixed to divided member 810 by an attachment structure such as a pin or a concave-convex fit. However, the attachment structure of fastening member 82 is not limited to these structures, and any appropriate structure that can attach fastening member 82 (plurality of small pieces 820) to divided member 810 can be used.

[0094] Furthermore, fastening member 82 is softer than each of the divided members 810. In other words, each of the divided members 810 is harder than fastening member 82. This allows fastening member 82, which fastens (connects) the divided members 810 together, to absorb slight misalignment between the divided members 810.

[0095] 13, the cage 8 has retaining claws 85 in the pockets 80 that prevent the rolling elements 63 from falling out of the pockets 80. Two retaining claws 85 are provided on each of a pair of inner surfaces that face each other in the circumferential direction (the circumferential direction of the outer ring 62) on the inner surface of the pocket 80. The rolling elements 63 accommodated in the pockets 80 are prevented from falling out of the pockets 80 by the four retaining claws 85.

[0096] 12 to 15, the cage 8 can come into contact with both a raceway surface 611 and an adjacent surface 612 of a raceway forming member that is made up of at least one of an outer ring 62 and an inner ring 61. In this embodiment, as an example, the inner ring 61 of the outer ring 62 and the inner ring 61 constitutes the raceway forming member, and the cage 8 comes into contact with both the raceway surface 611 and the adjacent surface 612 of the inner ring 61.

[0097] In short, a track-forming member (inner ring 61 in this embodiment) composed of at least one of outer ring 62 and inner ring 61 has raceway surfaces 611 on which the plurality of rolling elements 63 roll, and adjacent surfaces 612 that are adjacent to and intersect with raceway surface 611. Specifically, inner ring 61 as a track-forming member has, on its outer circumferential surface, raceway surface 611 and adjacent surfaces 612 that are adjacent to raceway surface 611. As described above, raceway surface 611 is an inclined surface that is inclined with respect to rotation axis Ax1 so as to be perpendicular to line of action LL1 of load on rolling elements 63. In contrast, adjacent surface 612 is a flat portion that is continuous with the end of raceway surface 611 closer to rotation axis Ax1 and extends parallel to rotation axis Ax1.

[0098] More specifically, the retainer 8 faces at least the exposed surface 84 of the fastening member 82 to the raceway surface 611 of the inner ring 61, and faces the end face of the divided member 810 on the rotation axis Ax1 side as viewed from the load action line LL1 to the adjacent surface 612 of the inner ring 61. Therefore, the retainer 8 can come into contact with the raceway forming member (inner ring 61) from two directions, and movement of the retainer 8 is restricted.

[0099] As described above, in the bearing device 6 (first main bearing 601 or second main bearing 602) according to this embodiment, the cage 8 that holds the multiple rolling elements 63 between the inner ring 61 and the outer ring 62 can come into contact with both the raceway surface 611 and the adjacent surface 612 of the raceway forming member that is made up of at least one of the outer ring 62 and the inner ring 61. As a result, the cage 8 comes into contact with the raceway forming member (the outer ring 62 and / or the inner ring 61) from two directions, thereby restricting movement of the cage 8. Therefore, without providing a separate snap ring or the like, the structure is simpler, yet the movement of the cage 8 is restricted and the cage 8 can be maintained between the inner ring 61 and the outer ring 62. As a result, the bearing device 6 can be realized with a simpler structure, making it easier to make the bearing device 6 more compact, and reducing the manufacturing costs of the bearing device 6.

[0100] Furthermore, since the retainer 8 can contact both the track surface 611 and the adjacent surface 612 of the track forming member, it becomes easier to determine the position of the retainer 8 relative to the track forming member when assembling the gear device 1, which also improves the ease of assembly of the gear device 1.

[0101] Here, it is sufficient for the cage 8 to be able to contact both the raceway surface 611 and the adjacent surface 612 of the track-forming member, and it is not essential that the cage 8 always contact both the raceway surface 611 and the adjacent surface 612. For example, there may be a situation in which the cage 8 moves away from the raceway surface 611 while the bearing device 6 is in operation. In this embodiment, the cage 8 holds the multiple rolling elements 63 in the multiple pockets 80 so that the rolling elements 63 can move relative to the cage 8 by an amount corresponding to "play" in a direction perpendicular to the raceway surface 611. Then, when the rolling elements 63 move to the maximum extent in a direction perpendicular to the raceway surface 611 away from the raceway surface 611, the cage 8 comes into contact with the raceway surface 611. In other words, "play" is provided between the rolling elements 63 and the cage 8 so that the cage 8 can contact the raceway surface 611.

[0102] 12 and other figures, when the cage 8 is in contact with the raceway surface 611 of the raceway forming member, a gap is created between the cage 8 and the outer ring 61, ensuring a path for the lubricant between the cage 8 and the outer ring 61. Furthermore, when the positional relationship between the rolling elements 63 and the cage 8 causes the cage 8 to move away from the raceway surface 611, a gap is created between the cage 8 and the inner ring 62, ensuring a path for the lubricant between the cage 8 and the inner ring 62 as well, allowing the lubricant to pass more efficiently.

[0103] To explain in more detail, in this embodiment, as described above, the raceway surface 611 is inclined with respect to the rotation axis Ax1, which is the central axis of the inner ring 61 and the outer ring 62. When the cage 8 comes into contact with such a raceway surface 611, movement of the cage 8 in a direction along the rotation axis Ax1, for example, is restricted. In other words, when the cage 8 comes into contact with the raceway surface 611, movement of the cage 8 outward (to the right in FIG. 15 ) in a direction along the rotation axis Ax1 is restricted.

[0104] On the other hand, the adjacent surface 612 is parallel to the rotation axis Ax1, which is the central axis of the inner ring 61 and the outer ring 62. When the retainer 8 comes into contact with such an adjacent surface 612, movement of the retainer 8 in a direction intersecting the rotation axis Ax1, for example, is restricted. In other words, when the retainer 8 comes into contact with the adjacent surface 612, movement of the retainer 8 in a direction intersecting the rotation axis Ax1 is restricted, and for example, tilt of the retainer 8 with respect to the rotation axis Ax1 is restricted.

[0105] Furthermore, in this embodiment, an inner circumferential surface 801 (see FIG. 13 ) of the cage 8 that faces the adjacent surface 612 is formed parallel to the rotation axis Ax1, which is the central axis of the inner ring 61 and the outer ring 62, just like the adjacent surface 612. Therefore, the inner circumferential surface 801 of the cage 8 can come into surface contact with the adjacent surface 612, and the inclination of the cage 8 with respect to the rotation axis Ax1 can be reliably restricted. Moreover, because such an inner circumferential surface 801 is inclined with respect to the raceway surface 611, the opening width of the pocket 80 on the outer ring 62 side is enlarged, making it easier to assemble the rolling elements 63 to the cage 8, etc.

[0106] Furthermore, in this embodiment, the cage 8 is in surface contact with both the raceway surface 611 and the adjacent surface 612 of the raceway forming member (the inner ring 61 in this embodiment). In other words, the cage 8 has a surface formed flush with the raceway surface 611 and the adjacent surface 612, and is in surface contact (surface contact) with the raceway surface 611 and the adjacent surface 612. As a result, the cage 8 comes into contact with the raceway surface 611 and the adjacent surface 612, and tilting of the cage 8, etc., is reliably restricted.

[0107] However, it is not essential that the cage 8 be in surface contact with both the raceway surface 611 and the adjacent surface 612, and the cage 8 may be in partial contact with at least one of the raceway surface 611 and the adjacent surface 612 of the raceway forming member (the inner ring 61 in this embodiment). In other words, the cage 8 may be configured to be in point contact or line contact, for example, rather than in surface contact, with at least one of the raceway surface 611 and the adjacent surface 612. This makes it possible to reduce loss due to contact between the cage 8 and the raceway surface 611 and the adjacent surface 612.

[0108] Furthermore, in this embodiment, as described above, each of the plurality of rolling elements 63 has a cylindrical shape. That is, each rolling element 63 is formed in a substantially cylindrical shape. While a cylindrical rolling element 63 can easily move along the raceway surface 611, the movement of the rolling element 63 along the raceway surface 611 is restricted by the cage 8 contacting the adjacent surface 612 that intersects with the raceway surface 611.

[0109] <Modification> Embodiment 1 is merely one of various reference examples of the present disclosure. Various modifications of Embodiment 1 are possible depending on the design, etc., as long as the object of the present disclosure can be achieved. Furthermore, all drawings referred to in this disclosure are schematic diagrams, and the ratios of the sizes and thicknesses of the components in the drawings do not necessarily reflect the actual dimensional ratios. Modifications of Embodiment 1 are listed below. The modifications described below can be applied in appropriate combinations.

[0110] The number of crankshafts 7A, 7B, 7C is not limited to three and may be two or four or more. Furthermore, if there is only one crankshaft, an internal meshing planetary gear device of an eccentric oscillating type in which the rotation axis Ax1 and the axis center Ax2 of the crankshaft coincide with each other, rather than a distributed type, is realized. In this case, when the crankshaft is driven, the planetary gear 3 oscillates, and the pair of carriers 18, 19 can be rotated relative to the gear body 22 around the rotation axis Ax1.

[0111] Furthermore, although the first embodiment exemplifies a gear device 1 having two types of planetary gears 3, the gear device 1 may have three or more planetary gears 3. For example, if the gear device 1 has three planetary gears 3, these three planetary gears 3 are preferably arranged with a phase difference of 120 degrees around the rotation axis Ax1. The gear device 1 may also have only one planetary gear 3. Alternatively, if the gear device 1 has three planetary gears 3, two of these three planetary gears 3 may be in phase, and the remaining planetary gear 3 may be arranged with a phase difference of 180 degrees around the rotation axis Ax1.

[0112] Furthermore, the bearing device 6 may be an angular contact ball bearing, a cross roller bearing, a deep groove ball bearing, a four-point contact ball bearing, etc. The rolling elements 63 are not limited to being substantially cylindrical (columnar) and may be, for example, truncated cone-shaped.

[0113] Furthermore, the number of teeth of the input gear 501, the number of teeth of the crankshaft gears 502A, 502B, and 502C, the number of outer pins 23 (the number of teeth of the internal teeth 21), and the number of teeth of the external teeth 31 described in embodiment 1 are merely examples and can be changed as appropriate.

[0114] Furthermore, the eccentric bearing 5 is not limited to a roller bearing, but may be, for example, a deep groove ball bearing, an angular contact ball bearing, or the like.

[0115] Furthermore, the material of each component of the gear device 1 is not limited to metal, but may be, for example, a resin such as engineering plastic. Conversely, the material of the cage 8 is not limited to resin, but may be, for example, a metal.

[0116] Furthermore, the gear device 1 is not limited to a configuration in which the rotational force of the inner ring 61 (input side carrier 18 and output side carrier 19) is extracted as an output, as long as it can extract the relative rotation between the inner ring 61 and the outer ring 62 of the bearing device 6 as an output. For example, the rotational force of the outer ring 62 (case 10) rotating relative to the inner ring 61 may be extracted as an output.

[0117] In addition, in the first embodiment, the output-side end faces 76 of the rotation axis Ax1 of the crankshafts 7A, 7B, and 7C are in direct contact with the output-side cover 14. However, this configuration is not limiting, and a plate-like component such as a shim member may be disposed between the end faces 76 and the output-side cover 14. In this case, by adjusting the thickness (and / or number) of the plate-like component when attaching the output-side cover 14, the gap between the end faces 76 and the output-side cover 14 in the axial direction can be adjusted, and the "play" of the crankshafts 7A, 7B, and 7C in the axial direction can be adjusted. Furthermore, the plate-like component functions as a raceway (washer) that reduces friction between the end faces 76 and the output-side cover 14.

[0118] Furthermore, the cage 8 only needs to have a plurality of divided members 810, and the number of divided members 810 is not limited to six, but may be five or less, or seven or more.

[0119] Similarly, the number of small pieces 820 constituting fastening member 82 is not limited to six, but may be five or less, or seven or more. Furthermore, it is not essential that fastening member 82 be divisible into multiple small pieces 820, and fastening member 82 may be formed as a single, inseparable part.

[0120] Furthermore, it is not essential that the retainer 8 has the fastening members 82, and the fastening members 82 can be omitted as appropriate.

[0121] Furthermore, the cage 8 need only be able to contact both the raceway surface 611 and the adjacent surface 612 of a raceway forming member made up of at least one of the outer ring 62 and the inner ring 61, and the raceway forming member is not limited to the inner ring 61. In other words, the raceway forming member may be the outer ring 62, or both the outer ring 62 and the inner ring 61.

[0122] Furthermore, the lubricant is not limited to a liquid substance such as lubricating oil (oil), but may be a gel substance such as grease.

[0123] (Embodiment 2) As shown in Figures 16 to 22, the bearing device 6A according to this embodiment differs from the bearing device 6 according to embodiment 1 in that it includes a support ring 9. Hereinafter, the same components as those in embodiment 1 will be denoted by the same reference numerals and descriptions thereof will be omitted as appropriate. Like the bearing device 6 of embodiment 1, the bearing device 6A is also used as the first main bearing 601 and the second main bearing 602 in the gear device 1.

[0124] FIG. 16 is a schematic perspective view of the bearing device 6A. FIG. 17 is a schematic exploded perspective view of the bearing device 6A. FIG. 18 is a schematic perspective view of the bearing device 6A omitting the inner ring 61 and the outer ring 62. FIG. 19 is a schematic exploded perspective view of the bearing device 6A omitting the inner ring 61 and the outer ring 62. FIG. 20 is a schematic perspective view of the bearing device 6A cut along a plane corresponding to the cross section along line A1-A1 in FIG. 7. FIG. 21 is a schematic exploded perspective view of the bearing device 6A cut along a plane corresponding to the cross section along line A1-A1 in FIG. 7. FIG. 22 is a cross-sectional view corresponding to the cross section along line A1-A1 in FIG. 7. However, hatching is omitted in FIGS. 20 to 22 even in the cross sections.

[0125] The bearing device 6A includes an inner race 61, an outer race 62, a plurality of rolling elements 63, and a support ring 9. The inner race 61 is disposed inside the outer race 62. The plurality of rolling elements 63 are disposed between the outer race 62 and the inner race 61. The support ring 9 is attached to the end of the raceway surface 611 of the raceway forming member that is farther from the rotation axis Ax1, and restricts movement of the plurality of rolling elements 63 along the raceway surface 611 in a direction away from the rotation axis Ax1. That is, the bearing device 6A according to this embodiment includes the inner race 61, the outer race 62, and the plurality of rolling elements 63, as well as the support ring 9 for restricting movement of the plurality of rolling elements 63.

[0126] That is, a raceway forming member made up of at least one of the outer ring 62 and the inner ring 61 has a raceway surface 611 on which the outer peripheral surfaces 633 of the plurality of rolling elements 63 roll. In this embodiment, as an example, the inner ring 61 of the outer ring 62 and the inner ring 61 constitutes the raceway forming member, and a support ring 9 is attached to the raceway surface 611 of the inner ring 61.

[0127] The raceway surface 611 is an inclined surface that is inclined with respect to the rotation axis Ax1 so as to be perpendicular to the load action line LL1 of the rolling elements 63. In contrast, the adjacent surface 612 is a flat portion that is continuous with the end of the raceway surface 611 closer to the rotation axis Ax1 and extends parallel to the rotation axis Ax1. The support ring 9 is attached to the end of the raceway surface 611 farther from the rotation axis Ax1 (the end on the right in FIG. 20) and restricts movement of the multiple rolling elements 63 along the raceway surface 611 in a direction away from the rotation axis Ax1 (to the right in FIG. 20).

[0128] As described above, in the bearing device 6A (first main bearing 601 or second main bearing 602) according to this embodiment, the support ring 9 that restricts movement of the multiple rolling elements 63 is attached to the end of the raceway surface 611 on the side farther from the rotation axis Ax1. As a result, the multiple rolling elements 63 come into contact with the support ring 9, and are restricted from moving along the raceway surface 611 in a direction away from the rotation axis Ax1. Therefore, without providing a separate retaining ring or the like, the structure is simpler, yet the movement of the multiple rolling elements 63 is restricted, and the multiple rolling elements 63 can be maintained between the inner ring 61 and the outer ring 62. As a result, the bearing device 6A can be realized with a simpler structure, making it easier to make the bearing device 6A more compact.

[0129] Furthermore, similar to the first embodiment, the bearing device 6A according to the present embodiment includes an annular cage 8 that holds multiple rolling elements 63 between the outer ring 62 and the inner ring 61. The support ring 9 restricts movement of the cage 8 along the raceway surface 611 in a direction away from the rotation axis Ax1. In other words, the support ring 9 restricts movement of the multiple rolling elements 63 by restricting movement of the cage 8, which holds the multiple rolling elements 63, in a direction away from the rotation axis Ax1. This restricts positional deviation of the cage 8, and reliably restricts tilt, etc., of the cage 8.

[0130] In particular, in this embodiment, the cage 8 has a plurality of divided members 810 divided in the circumferential direction. The plurality of divided members 810 are fastened (connected) by fastening members 82 consisting of a plurality of small pieces 820. Here, unlike the first embodiment, the cage 8 is divided into two members, an inner circumferential side and an outer circumferential side, with the pocket 80 sandwiched between them, and the inner circumferential side is composed of the holding member 81 (the plurality of divided members 810), and the outer circumferential side is composed of the fastening member 82. In other words, in the cage 8, the side wall on one side (the first end face 631 side) in the rolling axis direction of the rolling elements 63 in the pocket 80 is composed of the fastening member 82.

[0131] In this way, when the retainer 8 is configured from a plurality of divided members 810 rather than as a single unit (one integral, inseparable part), the support ring 9 attached to the end of the raceway surface 611 of the raceway forming member (inner ring 61) on the side farther from the rotation axis Ax1 (i.e., the larger diameter side) also contributes to improving the assembly of the retainer 8. In other words, when assembling the retainer 8, by arranging the plurality of divided members 810 so that they are lined up on the support ring 9, the plurality of divided members 810 are supported by the support ring 9, and the plurality of divided members 810 are less likely to come apart.

[0132] In short, the cage 8 further includes positioning members that position the multiple divided members 810. In this embodiment, the support ring 9 is an example of a positioning member. As described above, the support ring 9 is used to position the multiple divided members 810, particularly when assembling the cage 8. Therefore, a large load is not applied to the support ring 9 during operation of the bearing device 6A. Therefore, the material of the support ring 9 is not limited to metal, and may be a relatively soft material such as resin or rubber. Furthermore, the support ring 9 may be removed after the cage 8 is assembled.

[0133] Furthermore, of the raceway surface 611 and the adjacent surface 612 of the raceway forming member (the inner ring 61 in this embodiment), the cage 8 can only come into contact with the adjacent surface 612 and does not come into contact with the raceway surface 611. In other words, by bringing the cage 8 into contact with the adjacent surface 612 that is parallel to the rotation axis Ax1, movement of the cage 8 along the raceway surface 611 in a direction toward the rotation axis Ax1 (leftward in FIG. 20 ) can be restricted, while the support ring 9 can restrict movement of the cage 8 along the raceway surface 611 in a direction away from the rotation axis Ax1.

[0134] 19 to 22, the support ring 9 has a large diameter portion 91 that is parallel to the rotation axis Ax1 and a small diameter portion 92 that is inclined relative to the rotation axis Ax1. The small diameter portion 92 is continuous with the large diameter portion 91 and protrudes from one end of the large diameter portion 91 in the direction along the rotation axis Ax1 toward the rotation axis Ax1 so as to reduce the inner diameter of the support ring 9. The large diameter portion 91 and the small diameter portion 92 form a substantially V-shaped cross section of the support ring 9. The support ring 9 is fitted into the inner ring 61 in a state in which the small diameter portion 92 contacts the end of the raceway surface 611 of the inner ring 61 that is farther from the rotation axis Ax1.

[0135] Here, the end face of the support ring 9 closer to the rotation axis Ax1 faces the multiple rolling elements 63. In other words, the end face of the small diameter portion 92 of the support ring 9 opposite to the large diameter portion 91 faces the multiple rolling elements 63. This causes the end face of the small diameter portion 92 to come into contact with the multiple rolling elements 63, thereby restricting movement of the multiple rolling elements 63 along the raceway surface 611 in a direction away from the rotation axis Ax1 (toward the right in FIG. 20 ).

[0136] Furthermore, the support ring 9 is softer than the raceway forming member (the inner ring 61 in this embodiment). In other words, the raceway forming member (the inner ring 61 in this embodiment) is harder than the support ring 9. This prevents the support ring 9 from scratching the raceway forming member (the inner ring 61 in this embodiment), particularly the raceway surface 611.

[0137] In this embodiment, each of the plurality of rolling elements has a cylindrical shape. That is, each rolling element 63 is formed in a substantially cylindrical shape. While a cylindrical rolling element 63 can easily move along the raceway surface 611, the support ring 9 restricts the movement of the rolling element 63 along the raceway surface 611.

[0138] As a modification of the second embodiment, the cage 8 may be capable of contacting both the raceway surface 611 and the adjacent surface 612 of a raceway forming member made up of at least one of the outer ring 62 and the inner ring 61.

[0139] The configuration of the second embodiment (including the modified examples) can be adopted in appropriate combination with the various configurations (including the modified examples) described in the first embodiment.

[0140] (Embodiment 3) 23 to 26, the bearing device 6B according to this embodiment differs from the bearing device 6A according to the second embodiment in that the cage 8 is configured as a single inseparable part in the circumferential direction. Hereinafter, the same components as those in the second embodiment will be assigned the same reference numerals and explanations thereof will be omitted as appropriate. Like the bearing device 6A of the second embodiment, the bearing device 6B is also used as the first main bearing 601 and the second main bearing 602 in the gear device 1.

[0141] Fig. 23 is a schematic perspective view of the bearing device 6B. Fig. 24 is a schematic exploded perspective view of the bearing device 6B. Fig. 25 is a schematic perspective view of the bearing device 6B broken along a plane corresponding to the cross section along line A1-A1 in Fig. 7. Fig. 26 is a cross-sectional view corresponding to the cross section along line A1-A1 in Fig. 7. However, hatching is omitted in Figs. 25 and 26 even in the cross sections.

[0142] That is, in the bearing device 6B according to this embodiment, the retaining member 81 and the fastening member 82 are each configured as an annular member that is integral and inseparable in the circumferential direction. Therefore, the parts that configure the retaining member 81 (plurality of divided members 810) do not come apart, improving the ease of assembly of the cage 8.

[0143] As a modification of the third embodiment, the support ring 9 may be omitted.

[0144] The configuration of the third embodiment (including modifications) can be adopted in appropriate combination with the various configurations (including modifications) described in the first or second embodiment.

[0145] (Embodiment 4) As shown in Fig. 27, the bearing device 6C according to this embodiment differs from the bearing device 6 according to embodiment 1 in the shape of the cage 8. Hereinafter, the same components as those in embodiment 1 will be denoted by the same reference numerals and descriptions thereof will be omitted as appropriate. Like the bearing device 6 of embodiment 1, the bearing device 6C is also used as the first main bearing 601 and the second main bearing 602 in the gear device 1.

[0146] Figure 27 is a cross-sectional view showing bearing device 6C, corresponding to the cross section taken along line A1-A1 in Figure 7. However, in the enlarged view in the speech bubble in Figure 27, rolling element 63 is shown by an imaginary line (two-dot chain line), and retaining claws 85 and the like located behind rolling element 63 are also shown.

[0147] In the bearing device 6C according to this embodiment, the cage 8 can come into contact with both the outer ring 62 and the inner ring 61. This makes it possible to more stably regulate the position of the cage 8. Specifically, the outer ring 62 has, on its inner circumferential surface, a raceway surface 621 and an adjacent surface 622 adjacent to the raceway surface 621. As described above, the raceway surface 621 is an inclined surface that is inclined with respect to the rotation axis Ax1 so as to be perpendicular to the load action line LL1 of the rolling elements 63. In contrast, the adjacent surface 622 is a flat portion that is continuous with the end of the raceway surface 621 on the side farther from the rotation axis Ax1 and extends parallel to the rotation axis Ax1.

[0148] In this embodiment, the cage 8 can come into contact with both the raceway surface 611 and the adjacent surface 612 of the inner ring 61. On the other hand, of the raceway surface 621 and the adjacent surface 622 of the outer ring 62, the cage 8 can come into contact only with the adjacent surface 622, but does not come into contact with the raceway surface 621. In other words, by bringing the cage 8 into contact with the adjacent surface 622 that is parallel to the rotation axis Ax1, movement of the cage 8 along the raceway surface 621 in a direction away from the rotation axis Ax1 (toward the right in FIG. 27 ) can be restricted.

[0149] Here, an inner peripheral surface 801 of the retainer 8 that faces the adjacent surface 612 of the inner ring 61 is formed parallel to the rotation axis Ax1, which is the central axis of the inner ring 61 and the outer ring 62, similar to the adjacent surface 612. Furthermore, an outer peripheral surface 802 of the retainer 8 that faces the adjacent surface 622 of the outer ring 62 is formed parallel to the rotation axis Ax1, which is the central axis of the inner ring 61 and the outer ring 62, similar to the adjacent surface 622. Therefore, the inner peripheral surface 801 of the retainer 8 can come into surface contact with the adjacent surface 612 of the inner ring 61, and the outer peripheral surface 802 can come into surface contact with the adjacent surface 622 of the outer ring 62, making it possible to reliably regulate the inclination of the retainer 8 with respect to the rotation axis Ax1.

[0150] Here, the cage 8 does not contact both the inner ring 61 and the outer ring 62 at the same time, but rather has a "play" between the inner ring 61 and the outer ring 62 that allows the cage 8 to move in a direction perpendicular to the raceway surface 611 (the direction of the load action line LL1 of the rolling elements 63). Therefore, when the cage 8 is in contact with the inner ring 61, a gap is formed between the cage 8 and the outer ring 62, and when the cage 8 is in contact with the outer ring 62, a gap is formed between the cage 8 and the inner ring 61. As a result, the relative rotation between the inner ring 61 and the outer ring 62 is less likely to be affected by the cage 8, and the position of the cage 8 can be suitably regulated.

[0151] As a modification of the fourth embodiment, the cage 8 may be configured as a single inseparable part in the circumferential direction. Also, a support ring 9 may be provided.

[0152] The configuration of the fourth embodiment (including modifications) can be adopted in appropriate combination with the various configurations (including modifications) described in the first, second, or third embodiment.

[0153] (Embodiment 5) As shown in Fig. 28, the bearing device 6D according to this embodiment differs from the bearing device 6C according to the fourth embodiment in the shape of the cage 8. Hereinafter, the same components as those in the fourth embodiment will be denoted by the same reference numerals and descriptions thereof will be omitted as appropriate. Like the bearing device 6C of the fourth embodiment, the bearing device 6D is also used as the first main bearing 601 and the second main bearing 602 in the gear device 1.

[0154] Figure 28 is a cross-sectional view showing bearing device 6D, corresponding to the cross section taken along line A1-A1 in Figure 7. However, in the enlarged view in the speech bubble in Figure 28, rolling elements 63 are shown by imaginary lines (two-dot chain lines), and retaining claws 85 and the like located behind rolling elements 63 are also shown.

[0155] In this embodiment, the cage 8 can come into contact with both the raceway surface 611 and the adjacent surface 612 of the inner ring 61, and can come into contact with both the raceway surface 621 and the adjacent surface 622 of the outer ring 62. In other words, the outer ring 62 and the inner ring 61 are both raceway-forming members having the raceway surfaces 611, 621 and the adjacent surfaces 612, 622 that can come into contact with the cage 8.

[0156] Furthermore, the cage 8 is in partial (i.e., only a part of) contact with each of the raceway surfaces 611, 621 of the inner ring 61 and the outer ring 62. As shown in Fig. 28, the cage 8 can contact the raceway surface 611 of the inner ring 61 only at an end of the raceway surface 611 that is closer to the rotation axis Ax1 (i.e., the adjacent surface 612 side). On the other hand, the cage 8 can contact the raceway surface 621 of the outer ring 62 only at an end of the raceway surface 621 that is farther from the rotation axis Ax1 (i.e., the adjacent surface 622 side).

[0157] 28, at the end of the raceway surface 611 of the inner ring 61 on the side farther from the rotation axis Ax1 (i.e., the side opposite the adjacent surface 612), a gap (cavity) is formed between the raceway surface 611 and the cage 8. Similarly, at the end of the raceway surface 621 of the outer ring 62 on the side closer to the rotation axis Ax1 (i.e., the side opposite the adjacent surface 622), a gap (cavity) is formed between the raceway surface 621 and the cage 8. Therefore, these gaps can be used as passages for lubricant.

[0158] Here, the cage 8 does not contact both the inner ring 61 and the outer ring 62 at the same time, but rather has a "play" between the inner ring 61 and the outer ring 62 that allows the cage 8 to move in a direction perpendicular to the raceway surface 611 (the direction of the load action line LL1 of the rolling elements 63). Therefore, when the cage 8 is in contact with the inner ring 61, a gap is formed between the cage 8 and the outer ring 62, and when the cage 8 is in contact with the outer ring 62, a gap is formed between the cage 8 and the inner ring 61. As a result, the relative rotation between the inner ring 61 and the outer ring 62 is less likely to be affected by the cage 8, and the position of the cage 8 can be suitably regulated.

[0159] In addition, in this embodiment, the fastening members 82 that fasten the multiple segment members 810 are provided on the outer ring 62 side of the cage 8. Specifically, embedded grooves 83 are formed around the entire circumferential direction of the cage 8 on the surfaces of the multiple segment members 810 that face the adjacent surface 622 of the outer ring 62. The fastening members 82 are attached to the multiple segment members 810 by being embedded (fitted) into the embedded grooves 83. In this embodiment, as an example, the fastening members 82 fit entirely within the embedded grooves 83, thereby forming "embedded portions" where the fastening members 82 are entirely embedded in the multiple segment members 810.

[0160] As a modification of the fifth embodiment, the cage 8 may be configured as a single inseparable part in the circumferential direction. Also, a support ring 9 may be provided.

[0161] The configuration of the fifth embodiment (including modifications) can be adopted in appropriate combination with the various configurations (including modifications) described in the first, second, third, or fourth embodiment.

[0162] (summary) As described above, the bearing device (6, 6A, 6B, 6C, 6D) according to the first aspect includes an outer ring (62), an inner ring (61), a plurality of rolling elements (63), and an annular cage (8). The inner ring (61) is disposed inside the outer ring (62). The plurality of rolling elements (63) are disposed between the outer ring (62) and the inner ring (61). The cage (8) holds the plurality of rolling elements (63) between the outer ring (62) and the inner ring (61). A raceway-forming member formed of at least one of the outer ring (62) and the inner ring (61) has a raceway surface (611) on which each of the plurality of rolling elements (63) rolls, and an adjacent surface (612) adjacent to and intersecting with the raceway surface (611). The cage (8) is capable of contacting both the raceway surface (611) and the adjacent surface (612) of the track-forming member.

[0163] According to this aspect, the retainer 8 comes into contact with the raceway forming members (the outer ring 62 and / or the inner ring 61) from two directions, thereby restricting movement of the retainer 8. Therefore, without providing a separate retaining ring or the like, the structure is simpler, and the retainer 8 can be maintained between the inner ring 61 and the outer ring 62. As a result, the bearing devices 6, 6A, 6B, 6C, 6D can be realized with a simpler structure, which makes it easier to make the bearing devices 6, 6A, 6B, 6C, 6D more compact, and also reduces the manufacturing costs of the bearing devices 6, 6A, 6B, 6C, 6D.

[0164] In the bearing device (6, 6A, 6B, 6C, 6D) according to the second embodiment, in the first embodiment, the retainer (8) is in surface contact with both the raceway surface (611) and the adjacent surface (612) of the raceway-forming member.

[0165] According to this embodiment, the cage (8) comes into contact with the raceway surface (611) and the adjacent surface (612), thereby reliably restricting tilting of the cage (8).

[0166] In the bearing device (6, 6A, 6B, 6C, 6D) according to the third aspect, in the first aspect, the retainer (8) is in partial contact with at least one of the raceway surface (611) and the adjacent surface (612) of the raceway forming member.

[0167] According to this embodiment, it is possible to reduce loss due to contact between the cage (8) and the raceway surface (611) and the adjacent surface (612).

[0168] In the bearing device (6, 6A, 6B, 6C, 6D) according to the fourth aspect, in any one of the first to third aspects, the raceway surface (611) is inclined with respect to the rotation axis (Ax1) which is the central axis of the inner ring (61) and the outer ring (62).

[0169] According to this embodiment, the movement of the cage (8) in the direction along the rotation axis (Ax1) is restricted.

[0170] In the bearing device (6, 6A, 6B, 6C, 6D) according to the fifth aspect, in any one of the first to fourth aspects, the adjacent surface (612) is parallel to the rotation axis (Ax1) which is the central axis of the inner ring (61) and the outer ring (62).

[0171] According to this embodiment, the movement of the cage (8) in a direction intersecting the rotation axis (Ax1) is restricted.

[0172] In the bearing device (6, 6A, 6B, 6C, 6D) according to a sixth aspect, in any one of the first to fifth aspects, each of the plurality of rolling elements (63) has a cylindrical shape.

[0173] According to this embodiment, the cage (8) comes into contact with the adjacent surface (612) that intersects with the raceway surface (611), thereby restricting the movement of the rolling elements (63) along the raceway surface (611).

[0174] In the bearing device (6, 6A, 6B, 6C, 6D) according to the seventh aspect, in any one of the first to sixth aspects, the cage (8) is capable of contacting both the outer ring (62) and the inner ring (61).

[0175] According to this embodiment, the position of the cage (8) can be more stably regulated.

[0176] In the bearing device (6, 6A, 6B, 6C, 6D) according to the eighth aspect, in the seventh aspect, the outer ring (62) and the inner ring (61) are both raceway forming members having raceway surfaces (611, 621) and adjacent surfaces (612, 622) that can contact the retainer (8).

[0177] According to this embodiment, the position of the cage (8) can be more stably regulated.

[0178] In the bearing device (6, 6A, 6B, 6C, 6D) according to the ninth aspect, in the eighth aspect, the retainer (8) is in partial contact with the respective raceway surfaces (611, 621) of the inner ring (61) and the outer ring (62).

[0179] According to this embodiment, for the portions of the raceway surfaces (611, 621) of the inner ring (61) and the outer ring (62) that do not come into contact with the retainer (8), the gap between the retainer (8) and the raceway surfaces (611, 621) can be used as a path for the lubricant.

[0180] A gear device (1) according to a tenth aspect includes a first main bearing (601) and a second main bearing (602) that are the bearing device (6, 6A, 6B, 6C, 6D) according to any one of the first to ninth aspects, a first member, and a second member. The second member is supported relative to the first member via the first main bearing (601) and the second main bearing (602) so as to be rotatable around a rotation axis (Ax1).

[0181] This embodiment has the advantage of being able to provide a bearing device (6, 6A, 6B, 6C, 6D) and a gear device (1) that can be realized with a simpler structure.

[0182] The configurations according to the second to ninth aspects are not essential for the bearing device (6, 6A, 6B, 6C, 6D) and can be omitted as appropriate. [Explanation of symbols]

[0183] 1 Gearing 6, 6A, 6B, 6C, 6D Bearing device 10 Case (first component) 18, 19 Carrier (second member) 601 First main bearing 602 Second main bearing 8 Cage 61 Inner ring (raceway forming member) 62 Outer ring (raceway forming member) 63 Rolling elements 611 Raceway surface 612 Adjacent Surface Ax1 Rotation axis

Claims

1. The outer ring and an inner ring disposed inside the outer ring; a plurality of rolling elements disposed between the outer ring and the inner ring; an annular cage that holds the plurality of rolling elements between the outer ring and the inner ring, a raceway-forming member comprising at least one of the outer ring and the inner ring has a raceway surface on which each of the plurality of rolling elements rolls, and an adjacent surface that is adjacent to the raceway surface and intersects with the raceway surface, the retainer is capable of contacting both the raceway surface and the adjacent surface of the track-forming member; Bearing device.

2. the cage is in surface contact with both the raceway surface and the adjacent surface of the track-forming member; 2. The bearing device according to claim 1.

3. the cage is in partial contact with at least one of the raceway surface and the adjacent surface of the track-forming member; 2. The bearing device according to claim 1.

4. the raceway surface is inclined with respect to a rotation axis which is a central axis of the inner ring and the outer ring; The bearing device according to any one of claims 1 to 3.

5. the adjacent surfaces are parallel to a rotation axis that is a central axis of the inner ring and the outer ring; The bearing device according to any one of claims 1 to 3.

6. Each of the plurality of rolling elements has a cylindrical shape. The bearing device according to any one of claims 1 to 3.

7. The cage is capable of contacting both the outer ring and the inner ring. The bearing device according to any one of claims 1 to 6.

8. the outer ring and the inner ring are both raceway-forming members having the raceway surface and the adjacent surface that can come into contact with the cage, 8. The bearing device according to claim 7.

9. The cage is in partial contact with the raceway surfaces of the inner ring and the outer ring.

9. The bearing device according to claim 8.

10. a first main bearing and a second main bearing comprising the bearing device according to any one of claims 1 to 3; A first member; a second member supported relative to the first member via the first main bearing and the second main bearing so as to be rotatable around a rotation axis, Gearing.

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