Bearing device and gear device

Abstract

Provided in the present invention are a bearing device capable of more appropriately retaining rolling elements by means of a retainer, and a gear device. The bearing device (6) comprises: an outer race (62), an inner race (61), a plurality of rolling elements (63) and an annular retainer (8). The inner race (61) is arranged on the inner side of the outer race (62). The plurality of rolling elements (63) are arranged between the outer race (62) and the inner race (61). Each of the plurality of rolling elements (63) has a first end face (631) and a second end face (632) on two sides in the direction of a rolling axis that serves as a central axis. The retainer (8) has a plurality of pockets (80) respectively accommodating the plurality of rolling elements (63). In each of the plurality of pockets (80), a first side wall (801) facing the first end face (631) can be in line contact or point contact with the first end face (631), and a second side wall (802) facing the second end face (632) can be in surface contact with the second end face (632).

Description

Bearing assembly and gear assembly Technical Field

[0001] This disclosure generally relates to a bearing assembly and a gear assembly, and more specifically, to a bearing assembly and a gear assembly used in a gear assembly. Background Technology

[0002] Patent document 1 discloses a gear device comprising: an outer cylinder, an inner component, a first main bearing, and a second main bearing.

[0003] In the gear assembly, internal components are partially (or entirely) housed within an outer cylinder. Each of the first and second main bearings is embedded in an annular space formed between the outer cylinder and the internal components. With the internal components fixed, the outer cylinder rotates about a rotation axis corresponding to the central axis of the outer cylinder, the first main bearing, and the second main bearing. The second main bearing is separated from the first main bearing by a predetermined distance along the extension direction of the rotation axis.

[0004] Each of the first and second main bearings has an inner race, an outer race, and multiple rolling elements. The rolling elements are arranged in a ring between the inner and outer races and roll between them. Each rolling element is approximately a truncated cone. Here, the distance between the first intersection point of the load line of the first main bearing and the rotational axis, and the second intersection point of the load line of the second main bearing and the rotational axis, is set within a predetermined range. Therefore, the value of the distance between the first and second intersection points is sufficiently large, and the gear mechanism exhibits high robustness to external forces acting in a manner that bends the rotational axis.

[0005] [Existing technical documents]

[0006] [Patent Literature]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 2021-1693 Summary of the Invention

[0008] [The problem the invention aims to solve]

[0009] Furthermore, in the bearing assembly (first main bearing or second main bearing) of such a gear device, a retainer is sometimes used to hold multiple rolling elements between the inner and outer rings. However, for example, in a bearing assembly using a resin retainer, when the rolling elements are pressed into the groove of the retainer and assembled, if the tightening allowance of the groove is too small, the rolling elements may easily fall off; if the tightening allowance is too large, the assemblability may decrease.

[0010] This disclosure is made in view of the aforementioned reasons, and the object is to provide a bearing device and gear device that can more appropriately retain the rolling elements by the retainer.

[0011] [Technical means to solve the problem]

[0012] One aspect of the bearing assembly disclosed herein includes: an outer ring, an inner ring, a plurality of conical or cylindrical rolling elements, and an annular retainer. 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 retainer holds the plurality of rolling elements between the outer ring and the inner ring. Each of the plurality of rolling elements has a first end face and a second end face on both sides along a rolling axis that serves as a central axis. The retainer has a plurality of grooves that respectively receive the plurality of rolling elements. In each of the plurality of grooves, a first sidewall facing the first end face is capable of line contact or point contact with the first end face, and a second sidewall facing the second end face is capable of surface contact with the second end face.

[0013] One aspect of the gear assembly disclosed herein includes: a first main bearing and a second main bearing, comprising the bearing assembly; a first component; and a second component. The second component is rotatably supported on the first component about a rotation axis via the first and second main bearings.

[0014] [The effects of the invention]

[0015] According to this disclosure, there are the following advantages: a bearing device and gear device that can more appropriately retain the rolling elements by the retainer can be provided. Attached Figure Description

[0016] Figure 1 is a perspective view showing the schematic structure of the actuator including the gear device of Embodiment 1.

[0017] Figure 2 is a schematic exploded perspective view of the gear device of Embodiment 1 as viewed from the input side of the rotating shaft.

[0018] Figure 3 is a schematic exploded perspective view of the gear device of Embodiment 1 as viewed from the output side of the rotating shaft.

[0019] Figure 4 is a schematic cross-sectional view of the gear device according to Embodiment 1.

[0020] Figure 5 is a cross-sectional view along line A1-A1 of Figure 4 showing the gear device of Embodiment 1.

[0021] Figure 6 is a cross-sectional view along line B1-B1 of Figure 4 showing the gear device of Embodiment 1.

[0022] Figure 7 is a schematic diagram of the bearing device used in the gear device of Embodiment 1 as viewed from the input side of the rotating shaft.

[0023] Figure 8 is a schematic perspective view of the bearing device according to Embodiment 1.

[0024] Figure 9 is a schematic exploded perspective view of the bearing device of Embodiment 1.

[0025] Figure 10 is a schematic perspective view showing the bearing device of Embodiment 1 broken at the cross section along line A1-A1 in Figure 7.

[0026] Figure 11 is a cross-sectional view along line A1-A1 of Figure 7 showing the bearing device of Embodiment 1.

[0027] Figure 12 is a schematic exploded view of the bearing device of Embodiment 1, showing the main part that is broken at the cross section along line A1-A1 in Figure 7.

[0028] Figure 13 is a schematic perspective view showing the main part of the retainer of the bearing device according to Embodiment 1.

[0029] Figure 14 is a schematic diagram showing the holding state of the rolling elements of the bearing device in Embodiment 1.

[0030] Figure 15 is a cross-sectional view along line A1-A1 of Figure 7 showing the bearing device used in the gear device of Embodiment 2. Detailed Implementation

[0031] (Implementation Method 1)

[0032] (1) Summary

[0033] Hereinafter, the gear device 1 of this embodiment will be described in general with reference to FIGS. 1 to 4. The accompanying drawings referred to in this disclosure are all schematic diagrams, and the size and thickness ratios of each structural component in the drawings are not necessarily limited to reflecting the actual size ratios. For example, the tooth shape, size, and number of teeth of the internal tooth 21 and the external tooth 31 in FIGS. 1 to 4 are only schematically shown for illustration and are not intended to limit the shape of the illustrations.

[0034] The gear device 1 of this embodiment is a gear device including an internal gear 2 and a planetary gear 3. In the gear device 1, it is an internal meshing planetary gear device in which the planetary gear 3 is disposed inside the annular internal gear 2, and by oscillating the planetary gear 3, the planetary gear 3 rotates relative to the internal gear 2. Furthermore, 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 disposed inside the outer ring 62 and is supported to be able to rotate relative to the outer ring 62. In particular, the gear device 1 of this embodiment is a type of eccentric oscillating internal meshing planetary gear device, referred to as a distribution type.

[0035] As shown in Figures 1 to 4, the gear device 1 of this embodiment includes multiple (three in this embodiment) crankshafts (eccentric shafts) 7A, 7B, and 7C disposed at positions offset from the axis (rotation shaft Ax1) of the internal gear 2. Furthermore, the gear device 1 includes an input shaft 500 disposed on the axis (rotation shaft Ax1) of the internal gear 2, centered on the rotation shaft Ax1, and an input gear 501 integrally formed with the input shaft 500. Crankshaft gears 502A, 502B, and 502C are splinedly 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 gear device 1 synchronously drives the crankshafts 7A, 7B, and 7C using the input gear 501, thereby causing the planetary gear 3 to oscillate.

[0036] The internal gear 2 has internal teeth 21 and is fixed to the outer ring 62. Specifically, in this embodiment, the internal gear 2 has an annular gear body 22 and multiple outer pins 23. The multiple outer pins 23 are held in a rotatable state on the inner circumferential surface 221 of the gear body 22 and constitute the internal teeth 21. The planetary gear 3 has external teeth 31 that partially mesh with the internal teeth 21. That is, it presents a state where, inside the internal gear 2, the planetary gear 3 is internally connected to the internal gear 2, and a portion of the external teeth 31 meshes with a portion 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 of the internal teeth 21 and external teeth 31 moves in the circumferential direction of the internal gear 2, generating a relative rotation between the two gears (internal gear 2 and planetary gear 3) corresponding 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 (self-rotates) as the two gears rotate relative to each other. As a result, based on the difference in the number of teeth between the two gears, a rotational output with a relatively high reduction ratio is obtained from planetary gear 3.

[0037] This gear device 1 is used in such a way that the rotation corresponding to the rotational component of the planetary gear 3 is taken out as the rotation of a pair of planetary carriers 18, 19 whose inner rings 61 of the bearing device 6 are fixed relative to each other by means of embedding or the like. Thus, 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 planetary carriers 18, 19 as the output side. Therefore, in the gear device 1 of this embodiment, in order to transmit the rotation corresponding to the rotational component of the planetary gear 3 to the pair of planetary carriers 18, 19, a pair of planetary carriers 18, 19 are used to support multiple crankshafts 7A, 7B, 7C. The pair of planetary carriers 18, 19 are arranged on both sides of the axial direction (along the direction of the rotation axis Ax1) of the planetary gear 3, supporting each crankshaft 7A, 7B, 7C so that it can rotate.

[0038] Here, multiple crankshafts 7A, 7B, and 7C, each inserted into a plurality of openings 33 formed in the planetary gear 3, rotate relative to the internal gear 2 as the planetary gear 3 rotates. Furthermore, each crankshaft 7A, 7B, and 7C has a central shaft portion 71 and an eccentric portion 72 eccentrically positioned relative to the central shaft portion 71. A pair of planetary carriers 18 and 19 support the central shaft portion 71 of each crankshaft 7A, 7B, and 7C so that it can rotate, and the eccentric portions 72 of each crankshaft 7A, 7B, and 7C are inserted into the openings 33 of the planetary gear 3. When each crankshaft 7A, 7B, and 7C rotates about its respective central shaft portion 71, each eccentric portion 72 rotates eccentrically relative to its respective central shaft portion 71 (eccentric motion). Accompanying this, the planetary gear 3 oscillates. Through the oscillation of the planetary gear 3, the planetary gear 3 partially meshes with the internal gear 2 and rotates relative to the internal gear 2. As a result, planetary gear 3 rotates on its own central axis while revolving within internal gear 2, rotating about axis Ax1. As planetary gear 3 rotates, crankshafts 7A, 7B, and 7C revolve about axis Ax1. Planet carriers 18 and 19, which support the central shafts 71 of crankshafts 7A, 7B, and 7C, rotate in tandem with the revolution of crankshafts 7A, 7B, and 7C. Thus, the rotation (rotational component) of planetary gear 3, excluding its oscillating component (revolutionary component), is transmitted to a pair of planet carriers 18 and 19 via multiple crankshafts 7A, 7B, and 7C.

[0039] Furthermore, as shown in FIG1, the gear assembly 1 and the drive source 101 together constitute the actuator 100 in this embodiment. In other words, the actuator 100 in this embodiment includes the gear assembly 1 and the drive source 101. The drive source 101 generates a driving force for oscillating the planetary gear 3. Specifically, the drive source 101 oscillates the planetary gear 3 by rotating the input shaft 500 around the rotation axis Ax1.

[0040] (2) Definition

[0041] The term "ring-shaped" as used in this disclosure refers to a circle-like shape that forms an enclosed space (region) when viewed from above, and is not limited to a perfect circle (ring-shaped) when viewed from above. For example, it can also be an elliptical shape or a polygonal shape. Furthermore, for example, even a shape with a bottom, such as a cup shape, is included in "ring-shaped" as long as its peripheral walls are ring-shaped.

[0042] The term "revolution" as used in this disclosure refers to the rotation of an object about an axis other than the central axis passing through the object's center (center of gravity). When an object revolves, its center moves along a revolution path centered on the rotation axis. Therefore, for example, when an object rotates about an eccentric axis parallel to the central axis passing through its center (center of gravity), the object revolves around the eccentric axis as its rotation axis. As an example, planetary gear 3 revolves within internal gear 2 by oscillating and rotating about the rotation axis Ax1.

[0043] Furthermore, in this disclosure, one side of the rotating shaft Ax1 (the left side of FIG4) is sometimes referred to as the "output side," and the other side of the rotating shaft Ax1 (the right side of FIG4) is referred to as the "input side." In the example of FIG4, the input shaft 500 is rotated from the "input side" of the rotating shaft Ax1, and the rotation of a pair of planetary carriers 18 and 19 is taken out from the "output side" of the rotating shaft Ax1. Here, "input side" and "output side" are labels used for illustrative purposes only and do not imply the essential meaning of limiting the positional relationship of the input and output when viewed from the gear device 1.

[0044] The term "rotation axis" as used in this disclosure refers to a virtual axis (line) that serves as the center of rotational motion of the rotating body. That is, rotation axis Ax1 is a virtual axis without a physical counterpart. Input axis 500 rotates around rotation axis Ax1.

[0045] The terms "internal teeth" and "external teeth" as used in this disclosure refer to a collection (group) of multiple "teeth," rather than a single "tooth." That is, the internal teeth 21 of the internal gear 2 comprise a collection of multiple teeth disposed on the inner circumferential surface 221 of the internal gear 2 (gear body 22). Similarly, the external teeth 31 of the planetary gear 3 comprise a collection of multiple teeth disposed on the outer circumferential surface of the planetary gear 3.

[0046] (3) Detailed structure of the gear mechanism

[0047] Hereinafter, the detailed structure of the gear device 1 of this embodiment will be described with reference to Figures 1 to 6.

[0048] Figure 1 is a perspective view showing the schematic structure of the actuator 100 including the gear assembly 1. In Figure 1, the drive source 101 is schematically shown. Figure 2 is a schematic exploded perspective view of the gear assembly 1 viewed from the input side of the rotating shaft Ax1. Figure 3 is a schematic exploded perspective view of the gear assembly 1 viewed from the output side of the rotating shaft Ax1. Figure 4 is a schematic cross-sectional view of the gear assembly 1. Figure 5 is a cross-sectional view along line A1-A1 of Figure 4. Figure 6 is a cross-sectional view along line B1-B1 of Figure 4. In Figures 5 and 6, for parts other than crankshafts 7A, 7B, and 7C, even in cross-sections, the shading lines are omitted.

[0049] (3.1) Overall Structure

[0050] As shown in Figures 1 to 4, the gear assembly 1 of this embodiment includes: an internal gear 2, a planetary gear 3, a bearing assembly 6, multiple crankshafts 7A, 7B, and 7C, a pair of planetary carriers 18 and 19, and an input shaft 500. Furthermore, in this embodiment, the gear assembly 1 also 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 housing 10. In this embodiment, the internal gear 2, planetary gear 3, multiple crankshafts 7A, 7B, and 7C, and the pair of planetary carriers 18 and 19, which are structural components of the gear assembly 1, are made of stainless steel, cast iron, carbon steel for mechanical structures, chromium-molybdenum steel, phosphor bronze, or aluminum bronze, or light metals such as aluminum or titanium. The metals mentioned here (including light metals) include metals that have undergone surface treatments such as nitriding.

[0051] Furthermore, in this embodiment, as an example of gear device 1, an internal planetary gear device with a subcycloid tooth profile is illustrated. That is, the gear device 1 of this embodiment includes an internal planetary gear 3 having a subcycloid curved tooth profile.

[0052] In this embodiment, as an example, the gear device 1 is used with the gear body 22 of the internal gear 2 and the outer ring 62 of the bearing device 6 fixed together on a fixed member such as the housing 10. Thus, 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 housing 10).

[0053] Furthermore, in this embodiment, when the gear device 1 is used in the actuator 100, a rotational force is applied to the input shaft 500 as input, thereby extracting a rotational force as output from the pair of planetary carriers 18, 19 on the inner ring 61 to which the bearing device 6 is fixed. That is, the gear device 1 operates by taking the rotation of the input shaft 500 as input rotation and the rotation of the pair of planetary carriers 18, 19 on which the inner ring 61 is fixed as output rotation. Thus, in the gear device 1, an output rotation that is reduced at a relatively high reduction ratio relative to the input rotation can be obtained.

[0054] The drive source 101 is a power source such as a motor (electric motor). The power generated by the drive source 101 is transmitted to the input shaft 500 of the gear device 1. Specifically, the drive source 101 is connected to the input shaft 500, and the power generated by the drive source 101 is transmitted to the input shaft 500. Thus, the drive source 101 can rotate the input shaft 500.

[0055] Furthermore, in the gear device 1 of this embodiment, as shown in FIG4, the input-side rotational shaft Ax1 and the output-side rotational shaft Ax1 are located on the same straight line. In other words, the input-side rotational shaft Ax1 and the output-side rotational shaft Ax1 are coaxial. Here, the input-side rotational shaft Ax1 is the rotation center of the input shaft 500 to which input rotation is given, and the output-side rotational shaft Ax1 is the rotation center of the inner ring 61 (and the pair of planetary carriers 18, 19) that generate output rotation. That is, in the gear device 1, output rotation after being reduced at a relatively high reduction ratio relative to input rotation can be obtained on the same axis.

[0056] As shown in Figures 5 and 6, the internal gear 2 is an annular part with internal teeth 21. In this embodiment, at least the inner circumferential surface of the internal gear 2 has an annular shape that is a perfect circle when viewed from above. Internal teeth 21 are formed along the circumferential direction of the internal gear 2 on the inner circumferential surface of the annular internal gear 2. All the teeth constituting the internal teeth 21 are of the same shape and are arranged at equal pitch throughout the entire circumferential region of the inner circumferential surface of the internal gear 2. That is, the pitch circle of the internal teeth 21 is a perfect circle when viewed from above. The center of the pitch circle of the internal teeth 21 is located on the rotation axis Ax1. In addition, the internal gear 2 has a predetermined thickness in the direction of the rotation axis Ax1. The tooth lines of the internal teeth 21 are all parallel to the rotation axis Ax1. The dimension of the internal teeth 21 in the tooth line direction is slightly smaller than the dimension in the thickness direction of the internal gear 2.

[0057] Here, as described above, the internal gear 2 has an annular (ring-shaped) gear body 22 and multiple outer pins 23. The multiple outer pins 23 are held in a rotatable state on the inner circumferential surface 221 of the gear body 22 and constitute the internal gear 21. In other words, the multiple outer pins 23 function as multiple teeth constituting the internal gear 21. Specifically, as shown in FIG2, multiple inner circumferential grooves 223 are formed on the entire circumferential area of ​​the inner circumferential surface 221 of the gear body 22. All of the multiple inner circumferential grooves 223 are of the same shape and are arranged with equal pitch. The multiple inner circumferential grooves 223 are all parallel to the rotation axis Ax1 and are formed along the total length of the gear body 22 in the thickness direction. The multiple outer pins 23 are combined with the gear body 22 by being embedded in the multiple inner circumferential grooves 223. Each of the multiple outer pins 23 is held in a rotatable state within the inner circumferential groove 223. Furthermore, the gear body 22 (together with the outer ring 62) is fixed to the housing 10. Furthermore, a plurality of fixing holes 222 for fixing are formed in the gear body 22 (see Figure 5).

[0058] As shown in Figures 5 and 6, the planetary gear 3 is an annular part with external teeth 31. In this embodiment, at least the outer circumferential surface of the planetary gear 3 has an annular shape that is a perfect circle when viewed from above. External teeth 31 are formed on the outer circumferential surface of the annular planetary gear 3 along the circumferential direction of the planetary gear 3. All the teeth constituting the external teeth 31 are of the same shape and are arranged at equal pitch over the entire circumferential area of ​​the outer circumferential surface of the planetary gear 3. That is, the pitch circle of the external teeth 31 is a perfect circle when viewed from above. In addition, the planetary gear 3 has a predetermined thickness in the direction of the rotation axis Ax1. The external teeth 31 are all formed along the total length in the thickness direction of the planetary gear 3. The tooth lines of the external teeth 31 are all parallel to the rotation axis Ax1. In the planetary gear 3, unlike the internal gear 2, the external teeth 31 and the main body of the planetary gear 3 are integrally formed by a single metal component.

[0059] Furthermore, the gear device 1 of this embodiment 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 facing each other in a direction parallel to the rotation axis Ax1. That is, the planetary gears 3 include a first planetary gear 301 and a second planetary gear 302 arranged in a direction (axial direction) parallel to the rotation axis Ax1. The first planetary gear 301 and the second planetary gear 302 share a common shape.

[0060] These two planetary gears 3 (first planetary gear 301 and second planetary gear 302) are arranged about the rotation axis Ax1 with a phase difference of 180 degrees. In the example of Figure 4, the center (center of the pitch circle of the external tooth 31) C1 of the first planetary gear 301, located on the input side of the rotation axis Ax1 (right side of Figure 4), is offset (biased) upward relative to the rotation axis Ax1. On the other hand, the center (center of the pitch circle of the external tooth 31) C2 of the second planetary gear 302, located on the output side of the rotation axis Ax1 (left side of Figure 4), is offset (biased) downward relative to the rotation axis Ax1. Here, the distance ΔL1 between the rotation axis Ax1 and the center C1 is the 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 eccentricity of the second planetary gear 302 relative to the rotation axis Ax1. In this way, by arranging multiple planetary gears 3 equally in the circumferential direction centered on the rotation axis Ax1, a balance of weight and load among the multiple planetary gears 3 can be achieved.

[0061] In the first planetary gear 301 and the second planetary gear 302, their centers C1 and C2 are located at positions symmetrically rotated 180 degrees relative to the rotation axis Ax1. In this embodiment, the eccentricities ΔL1 and ΔL2 have opposite orientations when viewed from the rotation axis Ax1, but their absolute values ​​are the same.

[0062] More specifically, each crankshaft 7A, 7B, and 7C has two eccentric portions 72 relative to a central shaft portion 71. The eccentricity ΔL0 of the center C0 of these two eccentric portions 72 from the center (shaft Ax2) of the central shaft portion 71 (refer to Figures 5 and 6) is the same as the eccentricity ΔL1 and eccentricity ΔL2 of the first planetary gear 301 and the second planetary gear 302 relative to the rotation axis Ax1, respectively. The shapes of the multiple crankshafts 7A, 7B, and 7C are common to each other. The shapes of the multiple crankshaft gears 502A, 502B, and 502C are also common to each other.

[0063] Furthermore, a pair of planetary carriers 18 and 19 are arranged 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). Distinguishing between the pair of planetary carriers 18 and 19, the planetary carrier 18 located on the input side of the rotation axis Ax1 (right side in Figure 4) is referred to as the "input-side planetary carrier 18," and the planetary carrier 19 located on the output side of the rotation axis Ax1 (left side in Figure 4) is referred to as the "output-side planetary carrier 19." The two ends of each crankshaft 7A, 7B, and 7C are held in place by the pair of planetary carriers 18 and 19 via rolling bearings 41 and 42. That is, each crankshaft 7A, 7B, and 7C is held on both sides of the planetary gear 3 in the direction parallel to the rotation axis Ax1 (axial direction) in a state capable of rotation.

[0064] An eccentric bearing 5 is installed in the eccentric portion 72 of each crankshaft 7A, 7B, and 7C. Each of the first planetary gear 301 and the second planetary gear 302 has three openings 33 corresponding to the three crankshafts 7A, 7B, and 7C. Furthermore, the eccentric bearing 5 is received in each opening 33. In other words, with the eccentric bearing 5 installed in the first planetary gear 301 and the second planetary gear 302, the eccentric bearing 5 and each crankshaft 7A, 7B, and 7C are combined into the planetary gear 3 by inserting each crankshaft 7A, 7B, and 7C into the eccentric bearing 5. With the eccentric bearing 5 and crankshafts 7A, 7B, and 7C combined in the planetary gear 3, when each crankshaft 7A, 7B, and 7C rotates, the planetary gear 3 oscillates around the rotation axis Ax1.

[0065] Based on the structure described above, a rotational force is applied as input to the input shaft 500, which rotates around the rotation axis Ax1. This rotational force is then distributed from the input gear 501 to multiple crankshafts 7A, 7B, and 7C. That is, when the input gear 501 rotates, the three crankshaft gears 502A, 502B, and 502C that mesh with the input gear 501 rotate in the same direction at the same speed. Since crankshafts 7A, 7B, and 7C are splinedly connected to each of the crankshaft gears 502A, 502B, and 502C, the three crankshafts 7A, 7B, and 7C rotate in the same direction at the same speed under reduced speed conditions due to 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 shaft Ax1 of 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 shaft Ax1 of the three crankshafts 7A, 7B, and 7C rotate synchronously, causing the second planetary gear 302 to oscillate.

[0066] Figures 5 and 6 show the states of the first planetary gear 301 and the second planetary gear 302 at a certain point in time. Figure 5 is a cross-sectional view along line A1-A1 of Figure 4, showing the first planetary gear 301. Figure 6 is a cross-sectional view along line B1-B1 of Figure 4, showing the second planetary gear 302. As shown in Figures 5 and 6, the centers C1 and C2 of the first planetary gear 301 and the second planetary gear 302 are located at positions approximately symmetrical about 180 degrees relative to the rotation axis Ax1. In this embodiment, the eccentricities ΔL1 and ΔL2 have opposite orientations when viewed from the rotation axis Ax1, but their absolute values ​​are approximately the same (both are eccentricities ΔL0). According to the structure described above, the shaft center 71 rotates (rotates) around the shaft center Ax2, thereby causing the first planetary gear 301 and the second planetary gear 302 to rotate (eccentrically move) about the rotation axis Ax1 with a phase difference of approximately 180 degrees. Furthermore, by arranging multiple planetary gears 3 approximately equally in the circumferential direction centered on the rotation axis Ax1, a balance of weight and load among the multiple planetary gears 3 can be achieved.

[0067] The planetary gears 3 (first planetary gear 301 and second planetary gear 302) configured in this way are positioned inside the internal gear 2. Viewed from above, the planetary gear 3 is one size smaller than the internal gear 2, allowing it to oscillate inside the internal gear 2 when combined with it. Here, external teeth 31 are formed on the outer circumferential surface of the planetary gear 3, and internal teeth 21 are formed on the inner circumferential surface of the internal gear 2. Therefore, when the planetary gear 3 is positioned inside the internal gear 2, the external teeth 31 and the internal teeth 21 face each other.

[0068] Furthermore, the pitch circle of the external tooth 31 is one rotation smaller than that of the internal tooth 21. Also, when the first planetary gear 301 is internally engaged with the internal gear 2, the center C1 of the pitch circle of the external tooth 31 of the first planetary gear 301 is located at a position offset by a distance ΔL1 from the center of the pitch circle of the internal tooth 21 (rotation axis Ax1). Similarly, when the second planetary gear 302 is internally engaged with the internal gear 2, the center C2 of the pitch circle of the external tooth 31 of the second planetary gear 302 is located at a position offset by a distance ΔL2 from the center of the pitch circle of the internal tooth 21 (rotation axis Ax1).

[0069] Therefore, in either the first planetary gear 301 or the second planetary gear 302, at least a portion of the external teeth 31 and the internal teeth 21 face each other with a gap. If the difference in the number of teeth between the external teeth 31 and the internal teeth 21 is 2 or more, they will not mesh together in the circumferential direction. 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. That is, by the oscillation of the planetary gears 3 (first planetary gear 301 and second planetary gear 302) around the rotation axis Ax1, as shown in Figures 5 and 6, a portion of the teeth constituting the external teeth 31 meshes with a portion of the teeth constituting the internal teeth 21. As a result, in the gear assembly 1, a portion of the external teeth 31 can mesh with a portion of the internal teeth 21.

[0070] Here, the number of teeth on the internal gear 21 of the internal gear 2 is N more than the number of teeth on the external gear 31 of the planetary gear 3 (N is a positive integer). In this embodiment, as an example, N is "2", and the number of teeth on the planetary gear 3 (external teeth 31) is "2" less than the number of teeth on the internal gear 2 (internal teeth 21). 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 of the gear unit 1 relative to the input rotation.

[0071] Furthermore, in this 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. Consequently, the dimension of the external teeth 31 of the combined first planetary gear 301 and the second planetary gear 302 in the tooth line direction (parallel to the rotation axis Ax1) is smaller than the dimension of the internal teeth 21 in the tooth line direction (parallel to the rotation axis Ax1). 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 converge within the range of the tooth line of the internal teeth 21.

[0072] Here, the first planetary gear 301 and the second planetary gear 302 are internally meshed with the internal gear 2. Therefore, with each oscillation, the first planetary gear 301 and the second planetary gear 302 generate a phase deviation in the circumferential direction relative to the internal gear 2, corresponding to the difference in the number of teeth (between the internal teeth 21 and the external teeth 31), and rotate. This rotation, as the revolution of each crankshaft 7A, 7B, 7C around the axis (rotation axis Ax1) of the internal gear 2, is transmitted to a pair of planet carriers 18 and 19. Thus, with rotation axis Ax1 as the center, the pair of planet carriers 18 and 19 can rotate relative to (and) the gear body (integrated housing 10).

[0073] In summary, the gear device 1 of this embodiment utilizes multiple crankshafts 7A, 7B, and 7C positioned offset from the rotation axis Ax1 to oscillate the planetary gear 3, and obtains rotational output through the oscillation of the planetary gear 3. Specifically, in the gear device 1, when the planetary gear 3 oscillates and the meshing position of the internal teeth 21 and external teeth 31 moves in the circumferential direction of the internal gear 2, a relative rotation is generated between the two gears (internal gear 2 and planetary gear 3) corresponding 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) as the two gears rotate relative to each other. As a result, a rotational output with a relatively high reduction ratio is obtained from the planetary gear 3 based on the difference in the number of teeth between the two gears.

[0074] The bearing assembly 6 is a component having an outer ring 62 and an inner ring 61, used to extract the output of the gear assembly 1 by rotating the inner ring 61 relative to the outer ring 62. In addition to the outer ring 62 and inner ring 61, the bearing assembly 6 also has multiple rolling elements 63 (see Figure 4). Both the outer ring 62 and the inner ring 61 are annular parts. Both the outer ring 62 and the inner ring 61 are circular rings that appear perfectly round when viewed from above. The inner ring 61 is smaller than the outer ring 62 and is positioned inside the outer ring 62. Here, since the inner diameter of the outer ring 62 is larger than the outer diameter of the inner ring 61, a gap is created between the inner circumferential surface of the outer ring 62 and the outer circumferential surface of the inner ring 61.

[0075] Multiple rolling elements 63 are disposed in the gap between the outer ring 62 and the inner ring 61. The multiple rolling elements 63 are arranged in the circumferential direction of the outer ring 62. All of the multiple rolling elements 63 are metal parts of the same shape and are arranged at equal pitch throughout the circumferential direction of the outer ring 62.

[0076] More specifically, the gear assembly 1 of this embodiment includes a first main bearing 601 and a second main bearing 602, which are bearing assemblies 6. That is, the gear assembly 1 includes a pair of bearing assemblies 6 comprising the first main bearing 601 and the second main bearing 602. Specifically, as shown in FIG4, when viewed from the planetary gear 3, the first main bearing 601 is arranged on the input side of the rotating shaft Ax1 (the right side of FIG4), and the second main bearing 602 is arranged on the output side of the rotating shaft Ax1 (the left side of FIG4). The pair of bearing assemblies 6 are configured such that, by means of the first main bearing 601 and the second main bearing 602, they can withstand any of the following: loads in the radial direction, loads in the thrust direction (along the direction of the rotating shaft Ax1), and bending forces (bending moment loads) on the rotating shaft Ax1.

[0077] Here, the first main bearing 601 and the second main bearing 602 are arranged on opposite sides of the planetary gear 3 in a direction parallel to the rotation axis Ax1 (axial direction), with opposing orientations in the same direction. As an example, the pair of bearing assemblies 6 are of a "back-end combination type" where the inner rings 61 of the first main bearing 601 and the second main bearing 602 bear loads in a mutually outward thrust direction (along the rotation axis Ax1). Furthermore, in the gear assembly 1, the first main bearing 601 and the second main bearing 602 are combined under appropriate preload by fastening their respective inner rings 61 toward each other.

[0078] Furthermore, in the gear assembly 1 of this embodiment, the input-side planetary carrier 18 and the output-side planetary carrier 19 are arranged on opposite sides of the planetary gear 3 in a direction parallel to the rotation axis Ax1, and are engaged with each other via the planetary carrier bore 34 of the planetary gear 3 (see Figure 4). Specifically, as shown in Figure 4, when viewed from the planetary gear 3, the input-side planetary carrier 18 is arranged on the input side of the rotation axis Ax1 (the right side of Figure 4), and the output-side planetary carrier 19 is arranged on the output side of the rotation axis Ax1 (the left side of Figure 4). The inner rings 61 of a pair of bearing assemblies 6 (the first main bearing 601 and the second main bearing 602) are fixed to the input-side planetary carrier 18 and the output-side planetary carrier 19, respectively. In this embodiment, as an example, the inner ring 61 of the first main bearing 601 is fixed to the input-side planetary carrier 18. Similarly, the inner ring 61 of the second main bearing 602 is fixed to the output-side planetary carrier 19.

[0079] The output-side planetary carrier 19 has a plurality of (three in one example) planetary carrier pins 191 (see Figure 2) protruding from one surface of the output-side planetary carrier 19 toward the input side of the rotation axis Ax1. These plurality of planetary carrier pins 191 pass through a plurality of (three in one example) planetary carrier bores 34 formed in the planetary gear 3, and their tips are fixed to the input-side planetary carrier 18 by planetary carrier bolts. Here, a clearance is ensured between the planetary carrier pins 191 and the inner circumferential surface of the planetary carrier bores 34, thereby allowing the planetary carrier pins 191 to move within the planetary carrier bores 34, i.e., to move relative to the center of the planetary carrier bores 34. Therefore, when the planetary gear 3 oscillates, the planetary carrier pins 191 do not contact the inner circumferential surface of the planetary carrier bores 34.

[0080] With the aforementioned structure, the gear assembly 1 is used in such a way that the rotation corresponding to the rotational component of the planetary gear 3 is taken out as the rotation of the input-side planetary carrier 18 and the output-side planetary carrier 19, on which the inner ring 61 of the pair of bearing assemblies 6 (first main bearing 601 and second main bearing 602) is fixed. That is, in this embodiment, the relative rotation between the planetary gear 3 and the internal gear 2 is taken out from the input-side planetary carrier 18 and the output-side planetary carrier 19. In this embodiment, as an example, the gear assembly 1 is used with the outer ring 62 (see Figure 4) of the pair of bearing assemblies 6 (first main bearing 601 and second main bearing 602) fixed in the housing 10, which serves as a fixed member. That is, the planetary gear 3 is connected to the input-side planetary carrier 18 and the output-side planetary carrier 19, which serve as rotating members, via multiple crankshafts 7A, 7B, and 7C, and the gear body 22 is fixed to the fixed member, so the relative rotation between the planetary gear 3 and the internal gear 2 is taken out from the rotating members (input-side planetary carrier 18 and output-side planetary carrier 19). In other words, in this embodiment, the configuration is such that when the planetary gear 3 rotates relative to the gear body 22, the rotational force of the input-side planetary carrier 18 and the output-side planetary carrier 19 is taken out as the output.

[0081] Furthermore, in this embodiment, the housing 10 and the gear body 22 of the internal gear 2 are seamlessly integrated. That is, in the direction parallel to the rotation axis Ax1, the gear body 22, as a fixing member, is seamlessly and continuously provided with the housing 10.

[0082] More specifically, the housing 10 is cylindrical and forms the outline of the gear assembly 1. In this embodiment, the central axis of the cylindrical housing 10 is aligned with the rotation axis Ax1. That is, at least the outer peripheral surface of the housing 10 is a perfect circle centered on the rotation axis Ax1 when viewed from above (viewed from one side of the axial direction). The housing 10 is formed as a cylinder with open ends in the axial direction. Here, the gear body 22 of the internal gear 2 is seamlessly integrated with the housing 10, and the housing 10 and the gear body 22 are treated as a single part. Therefore, the inner peripheral surface of the housing 10 includes the inner peripheral surface 221 of the gear body 22. Furthermore, the outer ring 62 of a pair of bearing assemblies 6 (first main bearing 601 and second main bearing 602) is fixed in the housing 10. That is, when viewed from the gear body 22 on the inner peripheral surface of the housing 10, the outer ring 62 of the first main bearing 601 is fixed by embedding on the input side of the rotation axis Ax1 (right side of FIG. 4). On the other hand, when viewed from the gear body 22 on the inner circumferential surface of the housing 10, the outer ring 62 of the second main bearing 602 is fixed by embedding on the output side of the rotating shaft Ax1 (left side of FIG4).

[0083] Furthermore, the input side (right side of Figure 4) end face of the rotation shaft Ax1 of the housing 10 is closed by the input side planetary carrier 18, and the output side (left side of Figure 4) end face of the rotation shaft Ax1 of the housing 10 is closed by the output side planetary carrier 19. Therefore, as shown in Figure 4, the space surrounded by the housing 10, the input side planetary carrier 18, and the output side planetary carrier 19 houses planetary gears 3 (first planetary gear 301 and second planetary gear 302), multiple outer pins 23, and eccentric bearings 5, among other components.

[0084] Multiple (three in this embodiment) crankshafts 7A, 7B, and 7C each have a central shaft portion 71 and two eccentric portions 72. At least the outer peripheral surface of the central shaft portion 71 has a cylindrical shape that is a perfect circle when viewed from above. The shaft center Ax2, which is the center of the central shaft portion 71, is parallel to the rotation axis Ax1. The shaft centers Ax2 of the multiple crankshafts 7A, 7B, and 7C are arranged at equal intervals along the circumferential direction on a virtual circle centered on the rotation axis Ax1. At least the outer peripheral surface of each eccentric portion 72 has a disk shape that is a perfect circle when viewed from above. The center (central axis) C0 of each eccentric portion 72 is parallel to the rotation axis Ax1 and is positioned radially offset from the rotation axis Ax1. Here, the distance ΔL0 between the shaft center Ax2 and the center C0 (refer to Figures 5 and 6) is the eccentricity of the eccentric portion 72 relative to the central shaft portion 71. The eccentric portion 72 has a flange shape at its central portion along the long side (axial direction) of the shaft portion 71, protruding from the outer circumference of the shaft portion 71. According to the structure described, each crankshaft 7A, 7B, 7C rotates (self-rotates) around the shaft center Ax2 via the shaft portion 71, thereby causing the eccentric portion 72 to perform eccentric motion.

[0085] In this embodiment, the central shaft 71 and the two eccentric shafts 72 are integrally formed from a single metal component, thereby achieving seamless crankshafts 7A, 7B, and 7C. These crankshafts 7A, 7B, and 7C, with their specific shapes, are combined with the eccentric bearing 5 and then integrated into the planetary gear 3. Therefore, with the planetary gear 3 assembled with the eccentric bearing 5 and the crankshafts 7A, 7B, and 7C, the planetary gear 3 oscillates around the rotation axis Ax1 when the crankshafts 7A, 7B, and 7C rotate.

[0086] The eccentric bearing 5 is a component having multiple rolling elements 51 (see Figure 4) for absorbing the rotational component of crankshafts 7A, 7B, and 7C, and transmitting the rotational component of crankshafts 7A, 7B, and 7C, after removing the rotational component of crankshafts 7A, 7B, and 7C, i.e., only the oscillating component (revolutionary component) of crankshafts 7A, 7B, and 7C, to the planetary gear 3. The multiple rolling elements 51 are arranged between the outer peripheral surface of the eccentric portion 72 of each crankshaft 7A, 7B, and 7C and the inner peripheral surface of each opening 33 of the planetary gear 3. That is, the eccentric portion 72 of each crankshaft 7A, 7B, and 7C functions as the inner ring of the eccentric bearing 5, and the inner peripheral surface of each opening 33 of the planetary gear 3 functions as the outer ring of the eccentric bearing 5.

[0087] With the eccentric bearing 5 and multiple crankshafts 7A, 7B, and 7C assembled into the planetary gear 3, when each crankshaft 7A, 7B, and 7C rotates (self-rotates), each eccentric part 72 rotates (eccentrically moves) around the axis Ax2. The planetary gear 3 is positioned in a direction parallel to the rotation axis Ax1 (axial direction) corresponding to each eccentric part 72. Therefore, the eccentric motion of each eccentric part 72 is transmitted to the planetary gear 3 via the eccentric bearing 5, and the planetary gear 3 oscillates around the rotation axis Ax1. That is, the eccentric motion of the eccentric parts 72 of crankshafts 7A, 7B, and 7C is transmitted to the planetary gear 3. The eccentric bearing 5 functions as follows: mitigating friction caused by the relative rotation due to the speed difference between the eccentric motion of the eccentric parts 72 of each crankshaft 7A, 7B, and 7C (i.e., the self-rotation of each crankshaft 7A, 7B, and 7C) and the revolution of the planetary gear 3, and also serving as a power transmission mechanism.

[0088] In the gear assembly 1 of the described structure, a rotational force is applied as input to the input shaft 500, which rotates around 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 internally engaged with the internal gear 2 on the inner side, and oscillates while a portion of the external teeth 31 meshes with a portion of the internal teeth 21. Therefore, as the input shaft 500 rotates, the meshing position of the internal teeth 21 and the external teeth 31 moves in the circumferential direction of the internal gear 2. This generates a relative rotation between the two gears (internal gear 2 and planetary gear 3) corresponding to the difference in the number of teeth between the planetary gear 3 and the internal gear 2. Furthermore, the rotation (rotational component) of the planetary gear 3, after the oscillation component (revolutionary component) has been removed, is transmitted to a pair of planetary carriers 18 and 19 via multiple crankshafts 7A, 7B, and 7C. As a result, a rotational output with a relatively high reduction ratio is obtained from the pair of planetary carriers 18 and 19, based on the difference in the number of teeth between the two gears.

[0089] Furthermore, in the gear device 1 of this embodiment, as described above, the difference in the number of teeth between the internal gear 2 and the planetary gear 3 defines the reduction ratio of the output rotation relative to the input rotation of the gear device 1. That is, when the number of teeth of the internal gear 2 is set to "V1" and the number of teeth of the planetary gear 3 is set to "V2", the reduction ratio R1 is expressed by the following formula 1: R1=V2 / (V1-V2) (Formula 1)

[0090] In summary, 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, since 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", the reduction ratio R1 is "35" according to Equation 1. In this case, when viewed from the input side of the rotating shaft Ax1, each crankshaft 7A, 7B, 7C rotates clockwise one revolution (360 degrees) around the axis Ax2 of the shaft center 71 (refer to Figures 5 and 6), the pair of planetary carriers 18, 19 rotate counterclockwise around the rotating shaft Ax1 by an amount corresponding to the difference in the number of teeth "2" (i.e., approximately 10.3 degrees).

[0091] According to the gear device 1 of this embodiment, such a high reduction ratio R1 can be achieved through the combination of the internal gear 2 and the planetary gear 3. Furthermore, between the input gear 501 and the plurality of crankshaft gears 502A, 502B, and 502C, a suitable reduction ratio can also be achieved based on the number of teeth of the input gear 501 and the crankshaft gears 502A, 502B, and 502C. As a result, the gear device 1 as a whole can achieve a high reduction ratio.

[0092] Alternatively, the gear assembly 1 may include at least an internal gear 2, planetary gears 3, crankshafts 7A, 7B, and 7C, and a pair of planet carriers 18 and 19. For example, as shown in FIG4, it may also include a spacer 11. The spacer 11 is arranged in the axial direction parallel to the rotation axis Ax1 between the pair of planetary gears 3 (first planetary gear 301 and second planetary gear 302).

[0093] As explained above, the gear device 1 of this embodiment includes: a first main bearing 601 and a second main bearing 602, comprising a bearing assembly 6; a housing (first component) 10; and a pair of planetary carriers (second components) 18, 19. The pair of planetary carriers (second components) 18, 19 are rotatably supported on the housing (first component) 10 about the rotation axis Ax1 via the first main bearing 601 and the second main bearing 602. In this embodiment, since the housing 10 and the pair of planetary carriers 18, 19 rotate relative to each other via the first main bearing 601 and the second main bearing 602, the housing 10 is an example of the first component, and the pair of planetary carriers 18, 19 is an example of the second component.

[0094] In this embodiment, the gear device 1, together with the first block and the second block, constitutes a robot joint device. The gear device 1 connects the first block and the second block. The robot joint device functions as a joint device by causing the first block and the second block to rotate relative to each other about the rotation axis Ax1. Here, the first block and the second block rotate relative to each other by driving the input shaft 500 of the gear device 1 using the drive source 101. At this time, the rotation generated by the drive source 101 (input rotation) is decelerated in the gear device 1 with a relatively high reduction ratio, and the first block or the second block is driven with a relatively high torque. That is, the first block and the second block connected by the gear device 1 can perform flexion and extension movements about the rotation axis Ax1.

[0095] Robot joint devices are used, for example, in robots such as SCARA (Selective Compliance Assembly Robot Arm) type robots. Furthermore, robot joint devices are not limited to use in SCARA robots; they can also be used in industrial robots other than SCARA robots, or robots for non-industrial applications. Additionally, the gear device 1 in this reference example is not limited to use in robot joint devices; it can also be used as a wheel device such as an in-wheel motor in vehicles such as Automated Guided Vehicles (AGVs).

[0096] (3.2) Structure of the bearing assembly

[0097] Next, the structure of the bearing device 6 (first main bearing 601 and second main bearing 602) used in the gear device 1 of this embodiment will be described with reference to Figures 7 to 14. Since the first main bearing 601 and the second main bearing 602 are bearing devices 6 with a common structure, the following description will take the bearing device 6 used as the first main bearing 601 of the first main bearing 601 and the second main bearing 602 as an example.

[0098] Figure 7 is a schematic view of the bearing assembly 6 as seen from the input side of the rotating shaft Ax1. Figure 8 is a schematic perspective view of the bearing assembly 6. Figure 9 is a schematic exploded perspective view of the bearing assembly 6. Figure 10 is a schematic perspective view of the bearing assembly 6 broken at the A1-A1 section in Figure 7. Figure 11 is a cross-sectional view along the A1-A1 line in Figure 7. Figure 12 is a schematic exploded view of the main part of the bearing assembly 6, with the outer ring 62 omitted, broken at the A1-A1 section in Figure 7. Figure 13 is a schematic perspective view showing the main part of the retainer 8 of the bearing assembly 6. Figure 14 is a schematic view showing the holding state of the rolling element 63 of the bearing assembly 6. In Figures 10 to 14, for parts other than the retainer 8, even in cross-sections, the shading lines are omitted.

[0099] As shown in Figures 7 to 9, the bearing assembly 6 includes an inner ring (inner race) 61, an outer ring (outer race) 62, a plurality of rolling elements 63, and a retainer 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 retainer 8 is an annular member that holds the plurality of rolling elements 63 between the outer ring 62 and the inner ring 61. That is, in addition to the inner ring 61, the outer ring 62, and the plurality of rolling elements 63, the bearing assembly 6 of this embodiment also includes an annular retainer 8 for holding the plurality of rolling elements 63.

[0100] Here, the inner ring 61 is formed into a perfect circle when viewed from one side of the rotation axis Ax1 (e.g., the input side). The inner ring 61 is embedded into and fixed to the planet carrier 18 such that its inner circumferential surface contacts the planet carrier 18. The outer ring 62 is formed into a perfect circle that is one circle larger than the inner ring 61 when viewed from one side of the rotation axis Ax1 (e.g., the input side). The outer ring 62 is embedded into and fixed to the housing 10 such that its outer circumferential surface contacts the housing 10.

[0101] Furthermore, as described above, since the inner diameter of the outer ring 62 is larger than the outer diameter of the inner ring 61, a gap is created between the inner circumferential surface of the outer ring 62 and the outer circumferential surface of the inner ring 61. Moreover, a plurality of rolling elements 63 are disposed in the gap between the inner circumferential surface of the outer ring 62 and the outer circumferential surface of the inner ring 61. The plurality of rolling elements 63 are arranged in the circumferential direction of the outer ring 62 and roll between the outer ring 62 and the inner ring 61.

[0102] Each of the plurality of rolling elements 63 is generally cylindrical. As shown in FIG9, each of the plurality of rolling elements 63 includes a first end face 631, a second end face 632, and an outer peripheral face 633. The first end face 631 and the second end face 632 are generally coaxial circular shapes. Each of the plurality of rolling elements 63 is arranged such that the first end face 631 is more inward (on the side of the rotation axis Ax1) than the second end face 632, so that the rolling axis (central axis) is inclined relative to the rotation axis Ax1. Each of the plurality of rolling elements 63 rolls by rotating about the rolling axis with the outer peripheral face 633 in contact with the inner peripheral face of the outer ring 62 and the outer peripheral face of the inner ring 61. The load line LL1 of each rolling element 63 (see FIG10) passes through the center of the rolling element 63 and extends in a direction orthogonal to the rolling axis.

[0103] Here, the outer circumferential surface of the inner ring 61 has a track surface 611 that is inclined relative to the rotation axis Ax1 in a manner orthogonal to the load line LL1 of the rolling element 63 (see Figure 10). The inner circumferential surface of the outer ring 62 has a track surface 621 that is inclined relative to the rotation axis Ax1 in a manner orthogonal to the load line LL1 of the rolling element 63 (see Figure 10). Each of the plurality of rolling elements 63 is held between the inner ring 61 and the outer ring 62 with its outer circumferential surface 633 in contact with the track surface 611 in the outer circumferential surface of the inner ring 61 and the track surface 621 in the inner circumferential surface of the outer ring 62. That is, each of the plurality of rolling elements 63 moves (rolls) by rolling on the track surface 611 of the inner ring 61 and the track surface 621 of the outer ring 62.

[0104] In this embodiment, the inner ring 61, outer ring 62, and multiple rolling elements 63, which are structural components of the bearing assembly 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 metals (including light metals) mentioned here include metals that have undergone surface treatments such as nitriding. Furthermore, surface treatments may also include ferromite treatment, which forms a black oxide film on the surface. Ferromite treatment is considered effective in preventing white layer peeling caused by hydrogen embrittlement due to hydrogen permeation and absorption from the metal surface, and in suppressing creep of the inner ring 61 and outer ring 62. That is, one of the causes of white layer peeling in the bearing assembly 6 is considered to be hydrogen embrittlement caused by hydrogen permeating into the metal due to the decomposition of the lubricant (lubricating oil) on the sliding surface. As a result, by performing ferromite treatment, hydrogen embrittlement is suppressed, and white layer peeling is prevented.

[0105] A retainer 8 is disposed between the outer ring 62 and the inner ring 61. The retainer 8 is formed into a circular ring when viewed from one side of the rotation shaft Ax1 (e.g., the input side). The retainer 8 has a plurality of grooves 80 in the circumferential direction (circumferential direction of the outer ring 62) (see Figure 9). Each of the plurality of grooves 80 is a rectangular through hole that penetrates the retainer 8 in the thickness direction. The plurality of grooves 80 are arranged at equal pitch in the circumferential direction. By accommodating rolling elements 63 in each of these plurality of grooves 80, the retainer 8 retains a plurality of rolling elements 63 at equal pitch between the outer ring 62 and the inner ring 61. The retainer 8 is a molded product of resin (synthetic resin) or the like.

[0106] In this embodiment, the retainer 8 is composed of a single, inseparable part. As shown in FIG9, the retainer 8 is a ring-shaped member that is continuously and integrally formed in the circumferential direction.

[0107] The retainer 8 has a plurality of grooves 80 for holding a plurality of rolling elements 63. More specifically, the retainer 8 has a plurality of rectangular grooves 80 that extend through the retainer 8 in the thickness direction (along the direction of the rotation axis Ax1).

[0108] Furthermore, as shown in Figures 10 to 12, the retainer 8 has a first sidewall 801 and a second sidewall 802 on both sides of the inner surface of each of the plurality of grooves 80 in the direction of the rolling axis (the central axis of the rolling element 63). The first sidewall 801 is the surface of the inner surface of the groove 80 facing the first end face 631 of the rolling element 63, and the second sidewall 802 is the surface of the inner surface of the groove 80 facing the second end face 632 of the rolling element 63.

[0109] More specifically, as shown in FIG12, the retainer 8 has a plurality of spacer walls 800 that divide a plurality of grooves 80 in the circumferential direction. That is, grooves 80 are formed between a pair of adjacent spacer walls 800 in the circumferential direction. Moreover, the space surrounded by these pairs of spacer walls 800, the first sidewall 801 and the second sidewall 802 constitutes a groove 80 for receiving the rolling element 63.

[0110] In this view, the rolling elements 63 within the grooves 80 have their circumferential movement relative to the retainer 8 defined by a pair of spacer walls 800, and their radial movement relative to the retainer 8 defined by the first sidewall 801 and the second sidewall 802. As a result, the plurality of rolling elements 63 are held within the plurality of grooves 80 of the retainer 8 in a state in which they are rotatable about the rolling axis.

[0111] Here, as shown in Figures 10-12, the first sidewall 801 facing the first end face 631 can make line contact or point contact with the first end face 631. On the other hand, the second sidewall 802 facing the second end face 632 can make surface contact with the second end face 632. In this embodiment, as an example, the first sidewall 801 can make line contact with the first end face 631.

[0112] The term "line contact" as used in this disclosure refers, for example, to the contact between two parallel cylindrical surfaces, a cylindrical surface and a plane, or a conical surface and a plane, where the contact is geometrically a line. The term "point contact" as used in this disclosure refers, for example, to the contact between two objects, such as spheres, spheres and planes, or two orthogonal cylinders, where the contact is geometrically a point. The term "surface contact" as used in this disclosure refers, for example, to the contact between two objects, such as planes, or a curved surface with a large radius of curvature and a plane, where the contact is geometrically a surface. In practice, due to the elastic deformation of the two objects, the contact surface of a line contact becomes a "line" with a certain width. Similarly, the contact surface of a point contact actually becomes a "circle" or "ellipse" with a certain area due to the elastic deformation of the two objects.

[0113] Specifically, the first sidewall 801 is formed in a quadrilateral cross-section. By arranging the rolling element 63 in an angled position relative to the rotation axis Ax1, one vertex (corner) of the quadrilateral cross-section of the first sidewall 801 faces the first end face 631 of the rolling element 63. Thus, the first sidewall 801 contacts the first end face 631 of the rolling element 63 at its corner, enabling line contact with the first end face 631.

[0114] On the other hand, the second sidewall 802 is formed in a pentagonal cross-sectional shape. By arranging the rolling element 63 in a posture that tilts the rolling axis (central axis) relative to the rotation axis Ax1, one side (plane) of the pentagonal cross-section of the second sidewall 802 faces the second end face 632 of the rolling element 63. Thus, the second sidewall 802 can contact the second end face 632 of the rolling element 63 on one side.

[0115] As explained above, the bearing assembly 6 (first main bearing 601 or second main bearing 602) of this embodiment includes: an outer ring 62, an inner ring 61 disposed inside the outer ring 62, a plurality of conical or cylindrical rolling elements 63 disposed between the outer ring 62 and the inner ring 61, and an annular retainer 8. The retainer 8 holds the plurality of rolling elements 63 between the outer ring 62 and the inner ring 61. Each of the plurality of rolling elements 63 has a first end face 631 and a second end face 632 on both sides along the direction of the rolling axis that serves as the central axis. The retainer 8 has a plurality of grooves 80 that respectively accommodate the plurality of rolling elements 63. Here, regarding the retainer 8, in each of the plurality of grooves 80, the first sidewall 801 facing the first end face 631 can make line contact or point contact with the first end face 631, and the second sidewall 802 facing the second end face 632 can make surface contact with the second end face 632.

[0116] According to the described structure, even when the rolling element 63 is pressed into the groove 80 of the retainer 8 and assembled, the rolling element 63 is easily held within the groove 80 through line or point contact between the first sidewall 801 and the first end face 631, and surface contact between the second sidewall 802 and the second end face 632, preventing the rolling element 63 from falling out. Furthermore, since the contact between the first sidewall 801 and the first end face 631 is line or point contact, the assemblability is not easily compromised even with a large tightening allowance in the groove 80. As a result, it has the advantage of providing a bearing device 6 that can more appropriately hold the rolling element 63 within the retainer 8.

[0117] To explain in more detail, the track forming member comprising at least one of the outer ring 62 and the inner ring 61 (inner ring 61 in this embodiment) has: a track surface 611 for each of the plurality of rolling elements 63 to roll, and an adjacent surface 612 adjacent to and intersecting the track surface 611. Specifically, the inner ring 61, as the track forming member, has a track surface 611 and an adjacent surface 612 adjacent to the track surface 611 on its outer peripheral surface. As described above, the track surface 611 is an inclined surface that is inclined relative to the rotation axis Ax1 in a manner orthogonal to the load line LL1 of the rolling element 63. In contrast, the adjacent surface 612 is a flat portion that is continuous with the end of the track surface 611 on the side near the rotation axis Ax1 and extends parallel to the rotation axis Ax1.

[0118] The retainer 8 is positioned such that the end face of at least the first sidewall 801 on the side of the rotation axis Ax1, when viewed from the line of action of the load LL1, faces the adjacent surface 612 of the inner ring 61. Therefore, the retainer 8 can contact the adjacent surface 612 of the track forming member (inner ring 61), and the movement of the retainer 8 toward the rotation axis Ax1 is restricted.

[0119] Furthermore, the track forming member (inner ring 61 in this embodiment), which includes at least one of the outer ring 62 and the inner ring 61, has a cutter 613 and a hook 614. The cutter 613 is disposed between the track surface 611 and the adjacent surface 612. The hook 614 is disposed at the end of the track surface 611 opposite to the adjacent surface 612. The track forming member (inner ring 61 in this embodiment) has the cutter 613 facing the first end face 631 of the rolling element 63, and the hook 614 facing the second end face 632 of the rolling element 63.

[0120] Thus, in this embodiment, the inner ring 61 has: a track surface 611 for each of the plurality of rolling elements 63 to roll, and a guard portion 613 adjacent to the track surface 611 and capable of contacting the first end face 631. By providing the guard portion 613, the movement of at least the rolling elements 63 toward the first end face 631 side (i.e., the rotation axis Ax1 side) is restricted. Moreover, similarly, the movement of the retainer 8 that holds the rolling elements 63 toward at least the first end face 631 side (i.e., the rotation axis Ax1 side) is also restricted.

[0121] In this embodiment, since the inner ring 61 also has a hook portion 614, the movement of the rolling element 63 toward the second end face 632 (i.e., the side opposite to the rotation axis Ax1) is also restricted. Similarly, the movement of the retainer 8 that holds the rolling element 63 toward the second end face 632 (i.e., the side opposite to the rotation axis Ax1) is also restricted.

[0122] Furthermore, the rolling axis (central axis) of the rolling element 63 is inclined relative to the rotation axis Ax1 such that the first end face 631 faces the central axis of the outer ring 62, i.e., the rotation axis Ax1 side. As a result, the bearing device 6 can be realized with a simpler structure, and the bearing device 6 can be easily made compact.

[0123] Additionally, as shown in Figure 12, the retainer 8 has a limiting protrusion 86 on its second sidewall 802. The limiting protrusion 86 restricts the multiple rolling elements 63 from falling out of the multiple grooves 80. That is, by having an anti-detachment structure for the rolling elements 63 on its second sidewall 802, the retainer 8 prevents the rolling elements 63 from falling out of the retainer 8 during assembly, thereby improving assemblability.

[0124] Here, the limiting protrusion 86 includes a pair of protrusions 861 located at both ends of the retainer 8 in the circumferential direction of each of the plurality of recesses 80. Specifically, each of the pair of protrusions 861 is disposed at the corner between the second sidewall 802 and the spacer wall 800. Furthermore, the pair of protrusions 861 is disposed at the end on the outer ring 62 side of the second sidewall 802.

[0125] Therefore, when the rolling element 63 is embedded into the groove 80, the pair of protrusions 861 are less likely to become an obstacle, thus improving assemblability.

[0126] Furthermore, the opposing surfaces of the limiting protrusion 86 and the first sidewall 801 are inclined relative to the second sidewall 802 along the first sidewall 801. Specifically, each of the pair of protrusions 861 is formed in a generally triangular pyramid shape. As a result, when the rolling element 63 is inserted into the groove 80, the limiting protrusion 86 (the pair of protrusions 861) is less likely to become an obstacle, improving assemblability. Moreover, in the retainer 8 of the molded article containing resin or the like, the limiting protrusion 86 can be molded without undercutting.

[0127] Next, referring to Figure 13, an example of the assembly sequence of the inner ring 61, the retainer 8, and the rolling element 63 will be described.

[0128] First, the retainer 8 is assembled from above onto the inner ring 61, which is placed on the worktable with the track surface 611 facing upwards. At this time, the retainer 8 is positioned relative to the inner ring 61 by contacting the inner circumferential surface of the retainer 8 with the adjacent surface 612.

[0129] Furthermore, the rolling element 63 is inserted from above (on the outer ring 62 side) into the groove 80 of the retainer 8. At this time, by utilizing the elastic deformation of the retainer 8, the rolling element 63 can be assembled by hand without the use of special clamps.

[0130] Here, with the first end face 631 in line contact with the first sidewall 801, the rolling element 63, using the contact portion of the first end face 631 with the first sidewall 801 as a fulcrum, rotates and inserts into the groove 80. At this time, the second sidewall 802 becomes a guide for the second end face 632, facilitating the insertion of the rolling element 63 into the groove 80. Furthermore, the rolling element 63 is guided into the groove 80 while avoiding the limiting protrusions 86 (a pair of protrusions 861).

[0131] With the rolling element 63 fully inserted into the groove 80, the limiting protrusions 86 (a pair of protrusions 861) prevent the rolling element 63 from falling out of the groove 80. That is, the rolling element 63 is positioned by three points: the contact area between the first end face 631 and the first side wall 801, and the pair of protrusions 861, thus preventing it from falling out of the groove 80.

[0132] Furthermore, since the inner ring 61 has a guard portion 613, the rolling element 63 is engaged with the guard portion 613 when the rolling element 63 is housed in the groove 80, thus preventing the rolling element 63 and the retainer 8 from falling off the inner ring 61.

[0133] Additionally, as shown in Figure 14, the retainer 8 also has a guide portion 803 at the end of the spacer wall 800 on the inner ring 61 side. The guide portion 803 guides the rotation of the rolling element 63 by reducing the gap between the groove 80 and the rolling element 63 when viewed from one side of the rolling shaft. The guide portion 803 is constructed by increasing the width dimension (circumferential dimension) of the spacer wall 800. Here, the guide portion 803 is formed into a cross-sectional triangular shape with a width that increases as it approaches the track surface 611 of the inner ring 61. By providing this guide portion 803, the posture of the rolling element 63 during rotation is stabilized.

[0134] In addition, in this embodiment, the molding method for the retainer 8 is, for example, axial draw. By setting a structure in which there is no forced pull-out part, more stable product precision can be maintained.

[0135] <Variation Example>

[0136] Embodiment 1 is merely one of the various examples of this disclosure. Embodiment 1 can be modified in various ways, such as by design, to achieve the intended purpose of this disclosure. Furthermore, the accompanying drawings referenced in this disclosure are schematic, and the proportions of the size and thickness of each structural component in the drawings are not necessarily limited to reflecting actual dimensions. Hereinafter, variations of Embodiment 1 are listed. The variations described below can be appropriately combined and applied.

[0137] The number of crankshafts 7A, 7B, and 7C is not limited to "3," and can also be 2 or more. Furthermore, if there is only one crankshaft, an eccentric oscillating type internal meshing planetary gear device, where the rotation axis Ax1 is aligned with the crankshaft axis Ax2, can be realized, rather than a distribution type. In this case, by driving the crankshaft, the planetary gear 3 oscillates, allowing a pair of planet carriers 18 and 19 to rotate relative to the gear body 22 with the rotation axis Ax1 as the center.

[0138] Furthermore, although two types of gear devices 1 with planetary gears 3 are illustrated in Embodiment 1, the gear device 1 may also include three or more planetary gears 3. For example, when the gear device 1 includes three planetary gears 3, these three planetary gears 3 are preferably arranged with a phase difference of 120 degrees around the rotation axis Ax1. Alternatively, the gear device 1 may include only one planetary gear 3. Or, when the gear device 1 includes three planetary gears 3, two of these three planetary gears 3 may be in the same phase, and the remaining planetary gear 3 may be arranged with a phase difference of 180 degrees around the rotation axis Ax1.

[0139] In addition, the bearing assembly 6 can be an angular contact ball bearing, a cross roller bearing, a deep groove ball bearing, or a four-point contact ball bearing, etc. The rolling element 63 is not limited to a generally cylindrical shape (generally cylindrical), for example, it can also be frustoconical.

[0140] Furthermore, the number of teeth of the input gear 501, crankshaft gear 502A, crankshaft gear 502B, crankshaft gear 502C, number of outer pins 23 (number of teeth of inner teeth 21), and number of teeth of outer teeth 31 described in Embodiment 1 are just examples and can be appropriately changed.

[0141] In addition, the eccentric bearing 5 is not limited to roller bearings; for example, it can also be a deep groove ball bearing or an angular contact ball bearing.

[0142] Furthermore, the materials of the structural components of the gear device 1 are not limited to metal; for example, they can be resins such as engineering plastics. Conversely, the material of the retainer 8 is not limited to resin; for example, it can be metal.

[0143] Furthermore, the gear device 1 can be used as long as the relative rotation between the inner ring 61 and the outer ring 62 of the bearing device 6 is taken out as the output, and is not limited to the structure that takes out the rotational force of the inner ring 61 (the input-side planetary carrier 18 and the output-side planetary carrier 19) as the output. For example, the rotational force of the outer ring 62 (the housing 10) that rotates relative to the inner ring 61 can also be taken out as the output.

[0144] In addition, in Embodiment 1, the output side end faces of the rotating shafts Ax1 of crankshafts 7A, 7B, and 7C are in direct contact with the output side cover. However, this is not limited to the aforementioned structure; a plate-shaped part, such as a gasket member, may also be arranged between the end faces and the output side cover. In this case, when installing the output side cover, the axial clearance between the end faces and the output side cover can be adjusted by adjusting the thickness (and / or number of plates) of the plate-shaped part, thereby adjusting the axial "clearance" of crankshafts 7A, 7B, and 7C. Furthermore, the plate-shaped part functions as a track wheel (track disc) to reduce friction between the end faces and the output side cover.

[0145] In addition, the retainer 8 can also be divided into multiple segmented components in the circumferential direction.

[0146] Furthermore, the retainer 8 does not necessarily have to be a single, inseparable part. The retainer 8 may also have a first block and a second block that can be separated in the direction of the central axis (rolling shaft) of the rolling element 63. That is, the retainer 8 may not be constructed as a single, inseparable part, but rather by combining the first block and the second block. In this case, the first block has a plurality of grooves 80 that are open toward the second end face 632 on the rolling shaft, and the second block is combined with the first block in such a way that these grooves 80 are blocked from the second end face 632 on the rolling shaft. The second block may be configured, for example, to be fixed to the first block by a suitable mounting structure such as a pin or a tongue-and-groove joint.

[0147] Furthermore, the retainer 8 only needs to be able to contact both the track surface 611 and the adjacent surface 612 of the track forming member, which includes at least one of the outer ring 62 and the inner ring 61. The track forming member is not limited to the inner ring 61. That is, the track forming member can be the outer ring 62, or both the outer ring 62 and the inner ring 61.

[0148] In addition, lubricants are not limited to liquid substances such as lubricating oil, but can also be gel-like substances such as lubricating grease.

[0149] (Implementation Method 2)

[0150] As shown in Figure 15, the shape of the retainer 8 of the bearing device in this embodiment is different from that of the bearing device 6 in Embodiment 1. Hereinafter, common symbols will be used for structures that are the same as those in Embodiment 1, and descriptions may be omitted as appropriate. In addition, the bearing device is also used as the first main bearing 601 and the second main bearing 602 in the gear device 1, just like the bearing device 6 in Embodiment 1.

[0151] Figure 15 is a cross-sectional view corresponding to the section along line A1-A1 in Figure 7. In Figure 15, for parts other than the retainer 8, the shading lines are omitted even in the cross-section.

[0152] That is, in the bearing device of this embodiment, the corner of the first sidewall 801 facing the first end face 631 of the rolling element 63 is chamfered and formed into a pentagonal cross-section. By arranging the rolling element 63 in an inclined position relative to the rotation axis Ax1, one side (plane) of the pentagonal cross-section of the first sidewall 801 faces the first end face 631 of the rolling element 63. Thus, the first sidewall 801 can contact the first end face 631 of the rolling element 63 on one side. That is, in this embodiment, both the first sidewall 801 and the second sidewall 802 are configured to be able to contact the surface of the rolling element 63.

[0153] In this example, the contact area between the first sidewall 801 and the first end face 631 is smaller than the contact area between the second sidewall 802 and the second end face 632. In summary, in the example of Figure 15, the length of the side of the pentagonal cross-section of the first sidewall 801 facing the first end face 631 is shorter than the length of the side of the pentagonal cross-section of the second sidewall 802 facing the second end face 632. Therefore, although the contact pattern between the first sidewall 801 and the rolling element 63 is surface contact rather than either line contact or point contact, the contact area between the first sidewall 801 and the first end face 631 is smaller than the contact area between the second sidewall 802 and the second end face 632.

[0154] Therefore, even with a large tightening allowance in the groove 80, the assemblability is not easily compromised. As a result, it has the advantage of providing a bearing device that can more appropriately retain the rolling elements 63 in the retainer 8.

[0155] The structure of Embodiment 2 can be appropriately combined with the various structures (including variations) described in Embodiment 1.

[0156] (Summarize)

[0157] As described above, the bearing assembly (6) of the first form includes: an outer ring (62), an inner ring (61), a plurality of conical or cylindrical rolling elements (63), and an annular retainer (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 retainer (8) holds the plurality of rolling elements (63) between the outer ring (62) and the inner ring (61). Each of the plurality of rolling elements (63) has a first end face (631) and a second end face (632) on both sides along the direction of the rolling axis that serves as the central axis. The retainer (8) has a plurality of grooves (80) that respectively accommodate the plurality of rolling elements (63). In each of the plurality of grooves (80), the contact area between the first sidewall (801) facing the first end face (631) and the first end face (631) is smaller than the contact area between the second sidewall (802) facing the second end face (632) and the second end face (632).

[0158] According to the described configuration, even when the rolling element (63) is pressed into the groove (80) of the retainer (8) and assembled, the rolling element (63) is easily held in the groove (80) by the line or point contact between the first sidewall (801) and the first end face (631) and the surface contact between the second sidewall (802) and the second end face (632), thus preventing the rolling element (63) from falling out. Furthermore, since the contact area between the first sidewall (801) and the first end face (631) is smaller than the contact area between the second sidewall (802) and the second end face (632), the assemblability is not easily reduced even when the fastening allowance of the groove (80) is large. As a result, it has the advantage that a bearing device (6) can be provided that can more appropriately hold the rolling element (63) in the retainer (8).

[0159] The second type of bearing device (6) is based on the first type, wherein the rolling shaft is inclined relative to the rotating shaft (Ax1) (i.e., the central axis of the outer ring (62)) so that the first end face (631) faces the rotating shaft (Ax1).

[0160] According to the described form, the bearing device (6) can be realized with a simpler structure, and the bearing device (6) can be easily made compact.

[0161] The bearing device (6) of the third form is based on the first or second form, wherein the retainer (8) has a limiting protrusion (86) on the second side wall (802) to limit the dislodgement of the multiple rolling elements (63) from the multiple grooves (80).

[0162] According to the described form, at least during assembly, the rolling element (63) is prevented from falling off the retainer (8), thus improving assemblability.

[0163] The bearing device (6) of the fourth form is based on the third form, wherein the opposing surface of the limiting protrusion (86) to the first sidewall (801) is inclined relative to the second sidewall (802) in a manner along the first sidewall (801).

[0164] According to the described shape, when the rolling element (63) is embedded into the groove (80), the limiting protrusion (86) is less likely to become an obstacle, and the assemblability is improved.

[0165] The fifth type of bearing device (6) is based on the third or fourth type, wherein the limiting protrusion (86) includes a pair of protrusions (861) located at both ends of the retainer (8) in the circumferential direction of each of the plurality of grooves (80).

[0166] According to the described shape, when the rolling element (63) is embedded into the groove (80), the pair of protrusions (861) are less likely to become an obstacle, thus improving assemblability.

[0167] The sixth type of bearing device (6) is based on any one of the first to fifth types, wherein the inner ring (61) has a track surface (611) for each of the plurality of rolling elements (63) to roll, and a shank (613) adjacent to the track surface (611) and capable of contacting the first end face (631).

[0168] According to the described configuration, by providing the guard portion (613), the movement of at least the rolling element (63) toward the first end face (631) is restricted. Similarly, the movement of the retainer (8) that holds the rolling element (63) toward the first end face (631) is also restricted.

[0169] The bearing device (6) of the seventh form is based on any one of the first to sixth forms, wherein the first sidewall (801) is able to make line contact or point contact with the first end face (631), and the second sidewall (802) is able to make surface contact with the second end face (632).

[0170] According to the aforementioned configuration, the contact between the first sidewall (801) and the first end face (631) is a line contact or a point contact, and the contact between the second sidewall (802) and the second end face (632) is a surface contact, which allows the contact area between the first sidewall (801) and the first end face (631) to be smaller than the contact area between the second sidewall (802) and the second end face (632).

[0171] The gear assembly (1) of the eighth form includes: a first main bearing (601) and a second main bearing (602), comprising a bearing assembly (6) of any of the first to seventh forms; a first member; and a second member. The second member is rotatably supported on the first member about a rotation axis (Ax1) via the first main bearing (601) and the second main bearing (602).

[0172] According to the described form, it has the following advantages: a bearing device (6) and a gear device (1) that can more appropriately retain the rolling element (63) by the retainer (8) can be provided.

[0173] The structures of the second to sixth forms are not necessary for the bearing device (6) and can be appropriately omitted.

[0174] [Symbol Explanation] 1: Gear assembly 2: Internal gear 3: Planetary gear 5: Eccentric bearing 6: Bearing assembly 7A, 7B, 7C: Crankshaft (eccentric shaft) 8: Retainer 10: Housing (first component) 11: Spacer 18: Planetary carrier (second component) / Input-side planetary carrier 19: Planetary carrier (second component) / Output-side planetary carrier 21: Internal gear 22: Gear body 23: Outer pin 31: External gear 33: Opening 34: Planetary carrier bore 41, 42: Rolling bearing 51, 63: Rolling element 61: Inner ring (inner seat ring) (track forming component) 62: Outer ring (outer seat ring) (track forming component) 71: Shaft core 72: Eccentric part 80: Groove 86: Limiting protrusion 100: Actuator 101: Drive source 191: Planetary carrier pin 221: Inner circumferential surface; 222: Fixing hole; 223: Inner circumferential groove; 301: First planetary gear; 302: Second planetary gear; 500: Input shaft; 501: Input gear; 502A, 502B, 502C: Crankshaft gear; 601: First main bearing; 602: Second main bearing; 611: Track surface; 612: Adjacent surface; 613: Edge; 614: Hook; 621: Track surface; 631: First end face; 632: Second end face; 633: Outer circumferential surface; 800: Spacer wall; 801: First side wall; 802: Second side wall; 803: Guide part; 861: Protrusion; Ax1: Rotation shaft; Ax2: Shaft center; C0: Center (central shaft); C1, C2: Center; LL1: Load line; ΔL0, ΔL1, ΔL2: Eccentricity / distance.

Claims

1. A bearing assembly, comprising: Outer ring; The inner ring is disposed inside the outer ring; A plurality of conical or cylindrical rolling elements are disposed between the outer ring and the inner ring; and An annular retainer holds the plurality of rolling elements between the outer ring and the inner ring; Each of the plurality of rolling elements has a first end face and a second end face on both sides along the direction of the rolling axis that forms the central axis. The retainer has a plurality of grooves that respectively accommodate the plurality of rolling elements, wherein the contact area between the first sidewall facing the first end face and the first end face is smaller than the contact area between the second sidewall facing the second end face and the second end face.

2. The bearing device according to claim 1, wherein, The rolling shaft is inclined relative to the rotating shaft so that the first end face faces the rotating shaft side, and the rotating shaft is the central axis of the outer ring.

3. The bearing device according to claim 1 or 2, wherein, The retainer has a limiting protrusion on the second sidewall to restrict the dislodgement of the plurality of rolling elements from the plurality of grooves.

4. The bearing device according to claim 3, wherein, The opposing surface of the limiting protrusion to the first sidewall is inclined relative to the second sidewall to run along the first sidewall.

5. The bearing device according to claim 3, wherein, The limiting protrusion includes, in each of the plurality of grooves, a pair of protruding tabs located at both ends of the retainer in the circumferential direction.

6. The bearing device according to claim 1 or 2, wherein, The inner ring has a track surface for each of the plurality of rolling elements to roll, and a cutter portion adjacent to the track surface and capable of contacting the first end face.

7. The bearing device according to claim 1 or 2, wherein, The first sidewall is in line contact or point contact with the first end face, and the second sidewall is in surface contact with the second end face.

8. A gear mechanism, comprising: The first main bearing and the second main bearing are the bearing devices as described in claim 1 or 2; First component; as well as The second component is rotatably supported on the first component via the first main bearing and the second main bearing about a rotation axis.

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