Bearing devices and gear systems

Abstract

To provide a bearing device and a gear device that can more appropriately hold rolling elements in a cage. [Solution] The bearing device 6 comprises an outer ring 62, an inner ring 61, a plurality of rolling elements 63, and an annular cage 8. The inner ring 61 is positioned inside the outer ring 62. The plurality of rolling elements 63 are positioned 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 in the direction along the rolling axis which is the central axis. The cage 8 has a plurality of pockets 80 that each house one of the plurality of rolling elements 63. In each of the plurality of pockets 80, the first side wall 801 facing the first end face 631 can make line contact or point contact with the first end face 631, and the second side wall 802 facing the second end face 632 can make surface contact with the second end face 632.

Description

Technical Field

[0001] The present disclosure generally relates to a bearing device and a gear device, and more particularly to a bearing device and a gear device used in a gear device.

Background Art

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

[0003] In this gear device, the internal member is partially (or entirely) accommodated within the outer cylinder. Each of the first main bearing and the second main bearing is fitted into an annular space formed between the outer cylinder and the internal member. When the internal member is fixed, the outer cylinder rotates around a rotation axis corresponding to the central axes 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 in the extension direction of the rotation axis.

[0004] Each of the first main bearing and the second main bearing has an inner ring (inner race), an outer ring (outer race), and a plurality of rolling elements. The plurality of rolling elements are annularly arranged between the inner ring and the outer ring and roll between the inner ring and the outer ring respectively. Each of the plurality of rolling elements is substantially a truncated cone. Here, the distance between a first intersection point where the load action line of the first main bearing intersects the rotation axis and a second intersection point where the load action line of the second main bearing intersects the rotation axis is set within a predetermined range. Thereby, the value of the distance between the first intersection point and the second intersection point becomes sufficiently large, and the gear device has high robustness against an external force acting to bend the rotation axis.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] Incidentally, in the bearing device (first main bearing or second main bearing) of a gear system with the configuration described above, a cage is sometimes used to hold multiple rolling elements between the inner ring and the outer ring. However, in bearing devices using a resin cage, for example, assembly is performed by press-fitting the rolling elements into the cage's pockets. If the interference fit of the pockets is too small, the rolling elements are prone to falling out, and if the interference fit is too large, the ease of assembly may decrease.

[0007] This disclosure is made in view of the above-mentioned reasons and aims to provide a bearing device and a gear device that can more appropriately hold rolling elements in a cage. [Means for solving the problem]

[0008] A bearing device according to one aspect of the present disclosure comprises an outer ring, an inner ring, a plurality of conical or cylindrical rolling elements, and an annular cage. The inner ring is disposed inside the outer ring. The plurality of rolling elements are disposed between the outer ring and the inner ring. The cage holds the plurality of rolling elements between the outer ring and the inner ring. Each of the plurality of rolling elements has a first end face and a second end face on both sides in the direction along the rolling axis which is the central axis. The cage has a plurality of pockets for housing each of the plurality of rolling elements. In each of the plurality of pockets, a first side wall facing the first end face can make line contact or point contact with the first end face, and a second side wall facing the second end face can make surface contact with the second end face.

[0009] A gear apparatus according to one aspect of the present disclosure comprises a first main bearing and a second main bearing, which constitute the bearing apparatus, a first member, and a second member. The second member is supported by the first member so as to be rotatable about a rotation axis via the first main bearing and the second main bearing. [Effects of the Invention]

[0010] According to this disclosure, there is an advantage in that it is possible to provide bearing devices and gear devices that can more appropriately hold rolling elements in a retainer. [Brief explanation of the drawing]

[0011] [Figure 1] Figure 1 is a perspective view showing the schematic configuration of an actuator including a gear device according to Embodiment 1. [Figure 2] Figure 2 is a schematic exploded perspective view of the same gear mechanism as seen from the input side of the rotating shaft. [Figure 3] Figure 3 is a schematic exploded perspective view of the same gear mechanism as seen from the output side of the rotating shaft. [Figure 4] Figure 4 is a schematic cross-sectional view of the gear mechanism shown above. [Figure 5] Figure 5 is a cross-sectional view taken along line A1-A1 in Figure 4, showing the gear mechanism described above. [Figure 6] Figure 6 is a cross-sectional view taken along line B1-B1 in Figure 4, showing the gear mechanism described above. [Figure 7] Figure 7 is a schematic diagram of the bearing device used in the gear system described above, viewed from the input side of the rotating shaft. [Figure 8] Figure 8 is a schematic perspective view of the bearing device shown above. [Figure 9] Figure 9 is a schematic exploded perspective view of the bearing device shown above. [Figure 10] Figure 10 is a schematic perspective view of the bearing device shown above, broken along the line A1-A1 in Figure 7. [Figure 11] Figure 11 is a cross-sectional view taken along line A1-A1 in Figure 7, showing the bearing device described above. [Figure 12] Figure 12 shows the bearing device described above, and is a schematic exploded view of the main part broken along the line A1-A1 in Figure 7. [Figure 13] Figure 13 is a schematic perspective view showing the main parts of the retainer of the bearing device described above. [Figure 14] Figure 14 is a schematic diagram showing the holding state of the rolling elements in the bearing device described above. [Figure 15] Figure 15 is a cross-sectional view taken along line A1-A1 in Figure 7, showing a bearing device used in the gear apparatus according to Embodiment 2.

Best Mode for Carrying Out the Invention

[0012] (Embodiment 1) (1) Overview Hereinafter, the overview of the gear device 1 according to this embodiment will be described with reference to FIGS. 1 to 4. All the drawings referred to in the present disclosure are schematic drawings, and the ratios of the sizes and thicknesses of each component in the drawings do not necessarily reflect the actual dimensional ratios. For example, in FIGS. 1 to 4, the tooth profiles, dimensions, and number of teeth of the internal teeth 21 and the external teeth 31 are all merely schematically represented for the purpose of explanation, and are not intended to be limited to the illustrated shapes.

[0013] The gear device 1 according to this embodiment is a gear device including an internal gear 2 and a planetary gear 3. In this gear device 1, the planetary gear 3 is arranged inside the annular internal gear 2, and by swinging the planetary gear 3, the planetary gear 3 is relatively rotated with respect to the internal gear 2, which is an internal meshing planetary gear device. Further, the gear device 1 further includes a bearing device 6 having an outer ring 62 and an inner ring 61. The inner ring 61 is arranged inside the outer ring 62 and is supported so as to be relatively rotatable with respect to the outer ring 62. In particular, the gear device 1 according to this embodiment is an eccentric swing type internal meshing planetary gear device called a distribution type.

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

[0015] The internal gear 2 has internal teeth 21 and is fixed to the outer ring 62. In particular, in the present embodiment, the internal gear 2 has an annular gear body 22 and a plurality of outer pins 23. The plurality of outer pins 23 are held on the inner peripheral surface 221 of the gear body 22 in a rotatable state and constitute the internal teeth 21. The planetary gear 3 has external teeth 31 that partially mesh with the internal teeth 21. That is, the planetary gear 3 is inscribed in the internal gear 2 inside the internal gear 2, and a part of the external teeth 31 meshes with a part of the internal teeth 21. In this state, when the plurality of crankshafts 7A, 7B, 7C are driven, the planetary gear 3 swings, and the meshing position between the internal teeth 21 and the external teeth 31 moves in the circumferential direction of the internal gear 2, and a relative rotation corresponding to the difference in the number of teeth between the planetary gear 3 and the internal gear 2 occurs between the two gears (the internal gear 2 and the planetary gear 3). Here, if the internal gear 2 is fixed, the planetary gear 3 rotates (revolves) with the relative rotation of the two gears. As a result, a rotational output decelerated at a relatively high reduction ratio can be obtained from the planetary gear 3 according to the difference in the number of teeth between the two gears.

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

[0017] Here, the multiple crankshafts 7A, 7B, and 7C are inserted into multiple openings 33 formed in the planetary gear 3, and rotate relative to the internal gear 2 as the planetary gear 3 rotates. Each crankshaft 7A, 7B, and 7C has an axial portion 71 and an eccentric portion 72 that is eccentric to the axial portion 71. A pair of carriers 18 and 19 rotatably support the axial portion 71 of each crankshaft 7A, 7B, and 7C, and the eccentric portions 72 of each crankshaft 7A, 7B, and 7C are inserted into the openings 33 of the planetary gear 3. As each crankshaft 7A, 7B, and 7C rotates around its respective axial portion 71, each eccentric portion 72 rotates eccentrically (eccentric motion) relative to its respective axial portion 71. Consequently, the planetary gear 3 oscillates. As the planetary gear 3 oscillates, it partially meshes with the internal gear 2 and rotates relative to the internal gear 2. As a result, the planetary gear 3 rotates on its own central axis while revolving within the internal gear 2 around the rotation axis Ax1. As the planetary gear 3 rotates, each crankshaft 7A, 7B, and 7C revolves around the rotation axis Ax1, and the carriers 18 and 19 that support the axial center 71 of each crankshaft 7A, 7B, and 7C rotate in accordance with the revolution of each crankshaft 7A, 7B, and 7C. In this way, the rotation (rotation component) of the planetary gear 3, excluding the oscillating component (revolution component), is transmitted to the pair of carriers 18 and 19 by multiple crankshafts 7A, 7B, and 7C.

[0018] Furthermore, as shown in Figure 1, the gear device 1 according to this embodiment, together with the drive source 101, constitutes an actuator 100. In other words, the actuator 100 according to this embodiment comprises the gear device 1 and the drive source 101. The drive source 101 generates a driving force to oscillate 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.

[0019] (2) Definition As used in this disclosure, "ring-shaped" means a ring-like shape that forms an enclosed space (region) at least in a plan view, and is not limited to a circular shape (ring-shaped) that is a perfect circle in a plan view, but may also be an elliptical shape, a polygonal shape, etc. Furthermore, even a shape with a bottom, such as a cup shape, is included in "ring-shaped" if its peripheral wall is ring-shaped.

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

[0021] Furthermore, in this disclosure, one side of the rotating shaft Ax1 (the left side in Figure 4) may be referred to as the "output side," and the other side of the rotating shaft Ax1 (the right side in Figure 4) may be referred to as the "input side." In the example in Figure 4, rotation is applied to the input shaft 500 from the "input side" of the rotating shaft Ax1, and the rotation of the pair of carriers 18 and 19 is extracted from the "output side" of the rotating shaft Ax1. However, "input side" and "output side" are merely labels used for explanatory purposes and are not intended to limit the positional relationship between the input and output as seen from the gear device 1.

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

[0023] In this disclosure, "internal teeth" and "external teeth" refer not to individual "teeth," but to a collection (group) of multiple "teeth." In other words, the internal teeth 21 of the internal gear 2 consist of a collection of multiple teeth arranged on the inner circumferential surface 221 of the internal gear 2 (gear body 22). Similarly, the external teeth 31 of the planetary gear 3 consist of a collection of multiple teeth arranged on the outer circumferential surface of the planetary gear 3.

[0024] (3) Detailed configuration of the gear system The detailed configuration of the gear apparatus 1 according to this embodiment will be described below with reference to Figures 1 to 6.

[0025] Figure 1 is a perspective view showing the schematic configuration of the actuator 100 including the gear unit 1. In Figure 1, the drive source 101 is schematically shown. Figure 2 is a schematic exploded perspective view of the gear unit 1 as seen from the input side of the rotating shaft Ax1. Figure 3 is a schematic exploded perspective view of the gear unit 1 as seen from the output side of the rotating shaft Ax1. Figure 4 is a schematic cross-sectional view of the gear unit 1. Figure 5 is a cross-sectional view taken along line A1-A1 in Figure 4. Figure 6 is a cross-sectional view taken along line B1-B1 in Figure 4. However, in Figures 5 and 6, hatching is omitted for parts other than the crankshafts 7A, 7B, and 7C, even in cross-sections.

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

[0027] Furthermore, in this embodiment, an internal planetary gear system using a trochoidal tooth profile is presented as an example of the gear system 1. In other words, the gear system 1 according to this embodiment includes an internal planetary gear 3 having a trochoidal curved tooth profile.

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

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

[0030] The drive source 101 is a power source such as a motor. The power generated by the drive source 101 is transmitted to the input shaft 500 in the gear unit 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. This allows the drive source 101 to rotate the input shaft 500.

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

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

[0033] Here, the internal gear 2, as described above, has an annular (circular) gear body 22 and a plurality of external pins 23. The plurality of external pins 23 are held on the inner circumferential surface 221 of the gear body 22 in a state in which they can rotate, and constitute the internal teeth 21. In other words, the plurality of external pins 23 each function as a plurality of teeth that constitute the internal teeth 21. Specifically, as shown in Figure 2, a plurality of internal grooves 223 are formed on the inner circumferential surface 221 of the gear body 22 over the entire circumference. The plurality of internal grooves 223 are all the same shape and are provided at equal pitches. The plurality of internal grooves 223 are all parallel to the rotation axis Ax1 and are formed over the entire length of the gear body 22 in the thickness direction. The plurality of external pins 23 are assembled to the gear body 22 so as to fit into the plurality of internal grooves 223. Each of the plurality of external pins 23 is held in a state in which it can rotate within the internal groove 223. Furthermore, the gear body 22 is fixed to the case 10 (together with the outer ring 62). In addition, the gear body 22 has multiple fixing holes 222 (see Figure 5) for fixing.

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

[0035] Furthermore, the gear device 1 according to 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 to face each other in a direction parallel to the rotation axis Ax1. In other words, the planetary gear 3 includes a first planetary gear 301 and a second planetary gear 302 that are aligned in a direction parallel to the rotation axis Ax1 (axial direction). The shapes of the first planetary gear 301 and the second planetary gear 302 are the same.

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

[0037] The first planetary gear 301 and the second planetary gear 302 have centers C1 and C2 positioned 180 degrees rotationally symmetric with respect to the axis of rotation Ax1. In this embodiment, the eccentricity ΔL1 and eccentricity ΔL2 are in opposite directions when viewed from the axis of rotation Ax1, but their absolute values ​​are the same.

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

[0039] Furthermore, a pair of carriers 18 and 19 are positioned 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). To distinguish between the pair of carriers 18 and 19, the carrier 18 located on the input side of the rotation axis Ax1 (right side in Figure 4) is called the "input side carrier 18," and the carrier 19 located on the output side of the rotation axis Ax1 (left side in Figure 4) is called the "output side carrier 19." Each crankshaft 7A, 7B, and 7C is held at both ends by the pair of carriers 18 and 19 via rolling bearings 41 and 42. In other words, each crankshaft 7A, 7B, and 7C is held by the input side carrier 18 and the output side carrier 19 in a state that allows it to rotate on both sides of the planetary gear 3 in the direction parallel to the rotation axis Ax1 (axial direction).

[0040] Eccentric bearings 5 ​​are mounted on the eccentric portions 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. Eccentric bearings 5 ​​are housed in each of the openings 33. In other words, eccentric bearings 5 ​​are attached to the first planetary gear 301 and the second planetary gear 302, and each crankshaft 7A, 7B, and 7C is inserted into the eccentric bearings 5, thereby assembling the eccentric bearings 5 ​​and each crankshaft 7A, 7B, and 7C into the planetary gear 3. When each crankshaft 7A, 7B, and 7C rotates in the state as the eccentric bearings 5 ​​and crankshafts 7A, 7B, and 7C are assembled into the planetary gear 3, the planetary gear 3 oscillates around the rotation axis Ax1.

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

[0042] Figures 5 and 6 show the state 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 taken along line A1-A1 in Figure 4, showing the first planetary gear 301. Figure 6 is a cross-sectional view taken along line B1-B1 in 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 positioned approximately 180 degrees rotationally symmetric with respect to the rotation axis Ax1. In this embodiment, the eccentricity ΔL1 and eccentricity ΔL2 are in opposite directions when viewed from the rotation axis Ax1, but their absolute values ​​are approximately the same (both are eccentricity ΔL0). According to the above configuration, as the axial core 71 rotates (rotates) around the axis Ax2, the first planetary gear 301 and the second planetary gear 302 rotate (eccentrically) around the rotation axis Ax1 with a phase difference of approximately 180 degrees around the rotation axis Ax1. Furthermore, by arranging the multiple planetary gears 3 almost evenly in the circumferential direction around the rotation axis Ax1, it is possible to balance the weight and load among the multiple planetary gears 3.

[0043] The planetary gear 3 (first planetary gear 301 and second planetary gear 302) configured in this way is positioned inside the internal gear 2. In plan view, the planetary gear 3 is formed to be slightly smaller than the internal gear 2, and when combined with the internal gear 2, the planetary gear 3 is able to oscillate inside the internal gear 2. 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.

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

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

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

[0047] 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 in the internal gear 2. Moreover, the dimension of the external teeth 31 of the combined first planetary gear 301 and the second planetary gear 302 in the tooth trace direction (direction parallel to the rotation axis Ax1) is smaller than the dimension of the internal teeth 21 in the tooth trace direction (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 are contained within the range of the tooth trace of the internal teeth 21.

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

[0049] In short, the gear device 1 according to this embodiment oscillates a planetary gear 3 using a plurality of crankshafts 7A, 7B, and 7C positioned offset from the rotation axis Ax1, and obtains rotational output by utilizing the oscillation of the planetary gear 3. That is, in the gear device 1, as the planetary gear 3 oscillates and the meshing position between the internal teeth 21 and the external teeth 31 moves in the circumferential direction of the internal gear 2, relative rotation occurs between the two gears (internal gear 2 and planetary gear 3) according to the difference in the number of teeth between the planetary gear 3 and the internal gear 2. If the internal gear 2 is fixed, the planetary gear 3 will rotate (rotate on its own axis) in conjunction with the relative rotation of the two gears. As a result, rotational output reduced at a relatively high reduction ratio according to the difference in the number of teeth between the two gears can be obtained from the planetary gear 3.

[0050] The bearing device 6 has an outer ring 62 and an inner ring 61, and is a component for extracting the output of the gear device 1 as the rotation of the inner ring 61 relative to the outer ring 62. In addition to the outer ring 62 and inner ring 61, the bearing device 6 has a plurality of rolling elements 63 (see Figure 4). Both the outer ring 62 and the inner ring 61 are annular components. Both the outer ring 62 and the inner ring 61 have annular shapes that are perfect circles in plan view. The inner ring 61 is slightly 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.

[0051] Multiple rolling elements 63 are arranged in the gap between the outer ring 62 and the inner ring 61. Multiple rolling elements 63 are arranged in a line along the circumference of the outer ring 62. All of the multiple rolling elements 63 are metal parts of the same shape and are provided at equal pitches over the entire circumference of the outer ring 62.

[0052] More specifically, the gear assembly 1 according to this embodiment includes a first main bearing 601 and a second main bearing 602, which are bearing devices 6, respectively. In other words, the gear assembly 1 includes a pair of bearing devices 6 consisting of a first main bearing 601 and a second main bearing 602. Specifically, as shown in Figure 4, the first main bearing 601 is located on the input side of the rotation axis Ax1 as viewed from the planetary gear 3 (right side in Figure 4), and the second main bearing 602 is located on the output side of the rotation axis Ax1 as viewed from the planetary gear 3 (left side in Figure 4). The pair of bearing devices 6 are configured such that the first main bearing 601 and the second main bearing 602 can withstand radial loads, thrust loads (in the direction along the rotation axis Ax1), and bending forces (bending moment loads) on the rotation axis Ax1.

[0053] Here, the first main bearing 601 and the second main bearing 602 are positioned on both sides of the planetary gear 3 in a direction parallel to the rotation axis Ax1 (axial direction), and are facing opposite directions in a direction parallel to the rotation axis Ax1. As an example, the pair of bearing devices 6 are of a "back-to-back combination type" in which the inner rings 61 of the first main bearing 601 and the second main bearing 602 are subjected to outward thrust loads (directions along the rotation axis Ax1). Furthermore, in the gear device 1, the first main bearing 601 and the second main bearing 602 are assembled in a state in which appropriate preload is applied to the inner rings 61 by tightening them in a direction that brings their respective inner rings 61 closer together.

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

[0055] The output carrier 19 has multiple (for example, three) carrier pins 191 (see Figure 2) that protrude from one surface of the output carrier 19 toward the input side of the rotation axis Ax1. These multiple carrier pins 191 each pass through multiple (for example, three) carrier holes 34 formed in the planetary gear 3, and their tips are fixed to the input carrier 18 by carrier bolts. Here, a gap is ensured between the carrier pins 191 and the inner circumferential surface of the carrier holes 34, and the carrier pins 191 are movable within the carrier holes 34, that is, they are movable relative to the center of the carrier holes 34. As a result, the carrier pins 191 do not come into contact with the inner circumferential surface of the carrier holes 34 when the planetary gear 3 oscillates.

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

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

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

[0059] Furthermore, the input side (right side in Figure 4) end face of the rotating shaft Ax1 in case 10 is closed by the input side carrier 18, and the output side (left side in Figure 4) end face of the rotating shaft Ax1 in case 10 is closed by the output side carrier 19. As a result, as shown in Figure 4, components such as the planetary gear 3 (first planetary gear 301 and second planetary gear 302), multiple external pins 23, and eccentric bearing 5 are housed in the space enclosed by case 10, the input side carrier 18, and the output side carrier 19.

[0060] Each of the multiple (three in the embodiment) crankshafts 7A, 7B, and 7C has an axial portion 71 and two eccentric portions 72. The axial portion 71 has a cylindrical shape, with at least its outer surface being a perfect circle in plan view. The axis Ax2, which is the center of the axial portion 71, is parallel to the rotation axis Ax1. The axis Ax2 of the multiple crankshafts 7A, 7B, and 7C are arranged at equal intervals in the circumferential direction on a virtual circle centered on the rotation axis Ax1. Each eccentric portion 72 has a disc shape, with at least its outer surface being a perfect circle in plan view. 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 axis Ax2 and the center C0 (see Figures 5 and 6) is the amount of eccentricity of the eccentric portion 72 relative to the axial portion 71. The eccentric portion 72 has a flange shape that protrudes from the outer circumferential surface of the shaft portion 71 around its entire circumference at the center of the shaft portion 71 in the longitudinal direction (axial direction). With the above configuration, each crankshaft 7A, 7B, and 7C will undergo eccentric motion as the shaft portion 71 rotates around the shaft Ax2.

[0061] In this embodiment, the central shaft 71 and the two eccentric shafts 72 are integrally formed from a single metal member, thereby realizing seamless crankshafts 7A, 7B, and 7C. Crankshafts 7A, 7B, and 7C of this shape are combined with the planetary gear 3 together with the eccentric bearing 5. Therefore, when the crankshafts 7A, 7B, and 7C rotate with the eccentric bearing 5 and the planetary gear 3 combined, the planetary gear 3 oscillates around the rotation axis Ax1.

[0062] The eccentric bearing 5 has multiple rolling elements 51 (see Figure 4) and is a component that absorbs the rotational component of the rotation of the crankshafts 7A, 7B, and 7C, and transmits only the rotational component (orbital component) of the crankshafts 7A, 7B, and 7C to the planetary gear 3. The multiple rolling elements 51 are arranged between the outer circumferential surface of the eccentric portion 72 of each crankshaft 7A, 7B, and 7C and the inner circumferential surface of each opening 33 of the planetary gear 3. In other words, the eccentric portion 72 of each crankshaft 7A, 7B, and 7C functions as the inner ring of the eccentric bearing 5, and the inner circumferential surface of each opening 33 of the planetary gear 3 functions as the outer ring of the eccentric bearing 5.

[0063] With the eccentric bearing 5 and multiple crankshafts 7A, 7B, and 7C assembled to the planetary gear 3, when each crankshaft 7A, 7B, and 7C rotates (rotates), each eccentric part 72 rotates (performs eccentric motion) around the axis Ax2. Since the planetary gear 3 is installed in a direction parallel to the rotation axis Ax1 (axial direction) corresponding to each eccentric part 72, 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. In other words, the eccentric motion of the eccentric parts 72 on the crankshafts 7A, 7B, and 7C is transmitted to the planetary gear 3. The eccentric bearing 5 plays a role in mitigating friction and other issues caused by relative rotation resulting from the speed difference between the eccentric motion of the eccentric portion 72 of each crankshaft 7A, 7B, and 7C (i.e., the rotation of each crankshaft 7A, 7B, and 7C) and the revolution of the planetary gear 3, as well as in power transmission.

[0064] In the gear device 1 with the configuration described above, a rotational force is applied as input to the input shaft 500, causing the input shaft 500 to rotate around the rotation axis Ax1, and the planetary gear 3 oscillates (revolves) around the rotation axis Ax1. At this time, the planetary gear 3 oscillates inside the internal gear 2, with a portion of the external teeth 31 meshing with a portion of the internal teeth 21. As the input shaft 500 rotates, the meshing position between the internal teeth 21 and the external teeth 31 moves in the circumferential direction of the internal gear 2. 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. The rotation (rotation component) of the planetary gear 3, excluding the oscillating component (revolution component), is transmitted to the pair of carriers 18 and 19 by multiple crankshafts 7A, 7B, and 7C. As a result, the pair of carriers 18 and 19 will produce rotational output that is reduced at a relatively high reduction ratio, depending on the difference in the number of teeth of the two gears.

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

[0066] R1 = V2 / (V1 - V2) (Equation 1) In short, the smaller the difference in the number of teeth between the internal gear 2 and the planetary gear 3 (V1-V2), the larger the reduction ratio R1. For example, the number of teeth V1 of the internal gear 2 is "72", the number of teeth V2 of the planetary gear 3 is "70", and the difference in the number of teeth (V1-V2) is "2", so from equation 1 above, the reduction ratio R1 is "35". In this case, when viewed from the input side of the rotation axis Ax1, each crankshaft 7A, 7B, 7C rotates clockwise one full turn (360 degrees) around the axis Ax2 of the shaft center 71 (see Figures 5 and 6), the pair of carriers 18, 19 rotate counterclockwise around the rotation axis Ax1 by the amount of the difference in the number of teeth "2" (i.e., about 10.3 degrees).

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

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

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

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

[0071] The robot joint device is used in robots such as horizontal articulated robots (SCARA type robots). Furthermore, the robot joint device is not limited to horizontal articulated robots, but may also be used in industrial robots other than horizontal articulated robots, or in robots other than industrial robots. In addition, the gear device 1 in this reference example is not limited to robot joint devices, but may also be used in vehicles such as automated guided vehicles (AGVs) as a wheel device such as an in-wheel motor.

[0072] (3.2) Configuration of the bearing device Next, the configuration of the bearing device 6 (first main bearing 601 and second main bearing 602) used in the gear apparatus 1 according to 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 having a common configuration, the following description will use the bearing device 6 used as the first main bearing 601 as an example.

[0073] Figure 7 is a schematic diagram of the bearing device 6 as seen from the input side of the rotating shaft Ax1. Figure 8 is a schematic perspective view of the bearing device 6. Figure 9 is a schematic exploded perspective view of the bearing device 6. Figure 10 is a schematic perspective view of the bearing device 6 broken along the line A1-A1 in Figure 7. Figure 11 is a cross-sectional view of Figure 7 along the line A1-A1. Figure 12 is a schematic exploded view of the main parts of the bearing device 6, with the outer ring 62 omitted, broken along the line A1-A1 in Figure 7. Figure 13 is a schematic perspective view showing the main parts of the cage 8 of the bearing device 6. Figure 14 is a schematic diagram showing the holding state of the rolling elements 63 of the bearing device 6. However, in Figures 10 to 14, hatching is omitted for parts other than the cage 8, even in cross-sections.

[0074] As shown in Figures 7 to 9, the bearing device 6 comprises an inner ring 61, an outer ring 62, a plurality of rolling elements 63, and a cage 8. The inner ring 61 is positioned inside the outer ring 62. The plurality of rolling elements 63 are positioned between the outer ring 62 and the inner ring 61. The cage 8 is an annular member that holds the plurality of rolling elements 63 between the outer ring 62 and the inner ring 61. In other words, the bearing device 6 according to this embodiment comprises an inner ring 61, an outer ring 62, and a plurality of rolling elements 63, in addition to an annular cage 8 for holding the plurality of rolling elements 63.

[0075] Here, the inner ring 61 is formed in an annular shape that forms a perfect circle when viewed from one side of the rotating shaft Ax1 (for example, the input side). The inner ring 61 is fitted onto the carrier 18 so that its inner circumferential surface contacts the carrier 18, and is fixed to the carrier 18. The outer ring 62 is formed in an annular shape that forms a perfect circle slightly larger than the inner ring 61 when viewed from one side of the rotating shaft Ax1 (for example, the input side). The outer ring 62 is fitted onto the case 10 so that its outer circumferential surface contacts the case 10, and is fixed to the case 10.

[0076] 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. The multiple rolling elements 63 are arranged in the gap between the inner circumferential surface of the outer ring 62 and the outer circumferential surface of the inner ring 61. The multiple rolling elements 63 are arranged in a line in the circumferential direction of the outer ring 62 and roll between the outer ring 62 and the inner ring 61.

[0077] Each of the multiple rolling elements 63 is substantially cylindrical. Each of the multiple rolling elements 63 includes a first end face 631, a second end face 632, and an outer circumferential surface 633, as shown in Figure 9. The first end face 631 and the second end face 632 are substantially coaxial circles. Each of the multiple rolling elements 63 is positioned with its rolling axis (central axis) inclined with respect to the rotation axis Ax1 such that the first end face 631 is inward (towards the rotation axis Ax1) compared to the second end face 632. Each of the multiple rolling elements 63 rolls by rotating around its rolling axis with its outer circumferential surface 633 in contact with the inner circumferential surface of the outer ring 62 and the outer circumferential surface of the inner ring 61. The line of action of the load LL1 (see Figure 10) of each rolling element 63 passes through the center of the rolling element 63 and extends in a direction perpendicular to the rolling axis.

[0078] Here, the outer circumferential surface of the inner ring 61 has a raceway surface 611 (see Figure 10) that is inclined with respect to the axis of rotation Ax1 so as to be perpendicular to the line of action LL1 of the rolling element 63. The inner circumferential surface of the outer ring 62 has a raceway surface 621 (see Figure 10) that is inclined with respect to the axis of rotation Ax1 so as to be perpendicular to the line of action LL1 of the rolling element 63. Each of the multiple 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 raceway surface 611 of the outer circumferential surface of the inner ring 61 and the raceway surface 621 of the inner circumferential surface of the outer ring 62. In other words, each of the multiple rolling elements 63 moves (rolls) by rolling on the raceway surface 611 of the inner ring 61 and the raceway surface 621 of the outer ring 62.

[0079] In this embodiment, the materials of the inner ring 61, outer ring 62, and multiple rolling elements 63, which are components of the bearing device 6, are metals such as stainless steel, bearing steel, carbon steel for machine structural use, chromium-molybdenum steel, phosphor bronze, or aluminum bronze, or light metals such as aluminum or titanium. The term "metal" (including light metals) here includes metals that have undergone surface treatment such as nitriding. Furthermore, the surface treatment may include blackening treatment (fermite treatment) that forms a black oxide film on the surface. Blackening treatment is effective in preventing white layer peeling due to hydrogen embrittlement, where hydrogen penetrates and is absorbed from the metal surface, and in suppressing creep of the inner ring 61 and outer ring 62. In other words, it is believed that one of the causes of white layer peeling in the bearing device 6 is hydrogen embrittlement, which occurs when hydrogen generated by the decomposition of lubricant (lubricating oil) on the sliding surface penetrates into the metal. By applying blackening treatment, hydrogen embrittlement is suppressed, leading to the prevention of white layer peeling.

[0080] The retainer 8 is positioned between the outer ring 62 and the inner ring 61. The retainer 8 is formed in an annular shape that forms a perfect circle when viewed from one side of the rotating shaft Ax1 (for example, the input side). The retainer 8 has a plurality of pockets 80 (see Figure 9) in the circumferential direction (circumferential direction of the outer ring 62). Each of the plurality of pockets 80 is a rectangular through-hole that penetrates the retainer 8 in the thickness direction. The plurality of pockets 80 are arranged at equal pitches in the circumferential direction. The retainer 8 holds the plurality of rolling elements 63 by housing them in each of these plurality of pockets 80. The retainer 8 then holds the plurality of rolling elements 63 at equal pitches between the outer ring 62 and the inner ring 61 by holding the plurality of rolling elements 63 in a state that allows them to roll. The retainer 8 is a molded product of resin (synthetic resin) or the like.

[0081] In this embodiment, the retainer 8 is composed of a single, indivisible component. As shown in Figure 9, the retainer 8 is an annular member that is continuously and integrally constructed in the circumferential direction.

[0082] The retainer 8 has multiple pockets 80, each holding multiple rolling elements 63. More specifically, the retainer 8 has multiple rectangular pockets 80 that penetrate the retainer 8 in the thickness direction (along the direction of the rotation axis Ax1).

[0083] Incidentally, as shown in Figures 10 to 12, the retainer 8 has a first side wall 801 and a second side wall 802 on both sides in the direction of the rolling axis (central axis of the rolling element 63) on the inner surface of each of the multiple pockets 80. The first side wall 801 is the inner surface of the pocket 80 that faces the first end face 631 of the rolling element 63, and the second side wall 802 is the inner surface of the pocket 80 that faces the second end face 632 of the rolling element 63.

[0084] More specifically, as shown in Figure 12, the retainer 8 has multiple partition walls 800 that divide the multiple pockets 80 in the circumferential direction. In other words, a pocket 80 is formed between each pair of adjacent partition walls 800 in the circumferential direction. The space enclosed by these pairs of partition walls 800, the first side wall 801, and the second side wall 802 constitutes a pocket 80 for housing the rolling elements 63.

[0085] Thus, the rolling elements 63 within the pocket 80 have their circumferential movement relative to the retainer 8 restricted by a pair of partition walls 800, and their radial movement relative to the retainer 8 restricted by the first side wall 801 and the second side wall 802. As a result, the multiple rolling elements 63 are held within the multiple pockets 80 of the retainer 8, each capable of rotating around its rolling axis.

[0086] Here, as shown in Figures 10 to 12, the first side wall 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 side wall 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 side wall 801 can make line contact with the first end face 631.

[0087] As used in this disclosure, "line contact" refers to contact between two objects that geometrically form a single line, such as two parallel cylindrical surfaces, a cylindrical surface and a plane, or a conical surface and a plane. As used in this disclosure, "point contact" refers to contact between two objects that geometrically form a single point, such as two spheres, a sphere and a plane, or two orthogonal cylinders. As used in this disclosure, "surface contact" refers to contact between two objects that geometrically form a surface, such as two planes, or a curved surface with a large radius of curvature and a plane. However, in reality, due to the elastic deformation of the two objects, the contact surface in line contact becomes a "line" with a certain width. Similarly, the contact surface in point contact actually becomes a "circle" or "ellipse" with a certain area due to the elastic deformation of the two objects.

[0088] Specifically, the first side wall 801 is formed in a square cross-section. By arranging the rolling element 63 with its rolling axis (central axis) inclined with respect to the rotation axis Ax1, the first side wall 801 faces the first end face 631 of the rolling element 63 at one vertex (corner) of its square cross-section. As a result, the first side wall 801 comes into contact with the first end face 631 of the rolling element 63 at its corner, enabling line contact with the first end face 631.

[0089] On the other hand, the second side wall 802 is formed in a pentagonal cross-section. By arranging the rolling element 63 with its rolling axis (central axis) inclined with respect to the rotation axis Ax1, the second side wall 802 faces the second end face 632 of the rolling element 63 with one side (plane) of its pentagonal cross-section. As a result, the second side wall 802 comes into contact with the second end face 632 of the rolling element 63 on one of its surfaces, enabling surface contact with the second end face 632.

[0090] As described above, the bearing device 6 (first main bearing 601 or second main bearing 602) according to this embodiment comprises 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 cage 8. The cage 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 in the direction along the rolling axis which is the central axis. The cage 8 has a plurality of pockets 80 that each accommodate the plurality of rolling elements 63. Here, in each of the plurality of pockets 80, the retainer 8 has a first side wall 801 facing the first end face 631 that can make line contact or point contact with the first end face 631, and a second side wall 802 facing the second end face 632 that can make surface contact with the second end face 632.

[0091] With this configuration, even when assembly is performed by press-fitting the rolling elements 63 into the pockets 80 of the retainer 8, the first side wall 801 makes line or point contact with the first end face 631, and the second side wall 802 makes surface contact with the second end face 632, making it easier to hold the rolling elements 63 in the pockets 80 and preventing them from falling out. Moreover, since the contact between the first side wall 801 and the first end face 631 is line or point contact, assembly ease is not easily reduced even when the tightening allowance of the pockets 80 is large. As a result, there is an advantage in that a bearing device 6 can be provided that can hold the rolling elements 63 in the retainer 8 more appropriately.

[0092] More specifically, the raceway forming member (in this embodiment, the inner ring 61), which consists of at least one of the outer ring 62 and the inner ring 61, has a raceway surface 611 on which each of the plurality of rolling elements 63 rolls, and an adjacent surface 612 that is adjacent to and intersects with the raceway surface 611. Specifically, the inner ring 61 as a raceway forming member has a raceway surface 611 and an adjacent surface 612 adjacent to the raceway surface 611 on its outer circumferential surface. As described above, the raceway surface 611 is an inclined surface that is inclined with respect to the rotation axis Ax1 so as to be perpendicular to the line of action LL1 of the load of the rolling elements 63. In contrast, the adjacent surface 612 is a flat portion that is continuous with the end of the raceway surface 611 on the side closer to the rotation axis Ax1 and extends parallel to the rotation axis Ax1.

[0093] The retainer 8 has at least one end face on the rotation axis Ax1 side, viewed from the load action line LL1 on the first side wall 801, facing the adjacent surface 612 of the inner ring 61. As a result, the retainer 8 can come into contact with the adjacent surface 612 of the raceway forming member (inner ring 61), and the movement of the retainer 8 toward the rotation axis Ax1 is restricted.

[0094] Furthermore, the raceway forming member (in this embodiment, the inner ring 61), which consists of at least one of the outer ring 62 and the inner ring 61, has a flange portion 613 and a hook portion 614. The flange portion 613 is positioned between the raceway surface 611 and the adjacent surface 612. The hook portion 614 is positioned at the end of the raceway surface 611 opposite to the adjacent surface 612. The raceway forming member (in this embodiment, the inner ring 61) has the flange portion 613 facing the first end surface 631 of the rolling element 63 and the hook portion 614 facing the second end surface 632 of the rolling element 63.

[0095] Thus, in this embodiment, the inner ring 61 has a raceway surface 611 on which each of the multiple rolling elements 63 rolls, and a flange portion 613 adjacent to the raceway surface 611 and capable of contacting the first end surface 631. The presence of the flange portion 613 restricts the movement of the rolling elements 63 at least toward the first end surface 631 side (i.e., the rotation axis Ax1 side). Similarly, the retainer 8 that holds the rolling elements 63 is also restricted from moving at least toward the first end surface 631 side (i.e., the rotation axis Ax1 side).

[0096] 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.

[0097] Furthermore, the rolling axis (central axis) of the rolling element 63 is inclined with respect to the rotation axis Ax1 such that its first end face 631 faces the rotation axis Ax1, which is the central axis of the outer ring 62. This allows the bearing device 6 to be realized with a simpler structure and makes it easier to make the bearing device 6 more compact.

[0098] Furthermore, as shown in Figure 12, the retainer 8 has a regulating projection 86 on its second side wall 802. The regulating projection 86 prevents the rolling elements 63 from falling out of the multiple pockets 80. In other words, the retainer 8 has a structure on its second side wall 802 that prevents the rolling elements 63 from falling out of the retainer 8 during assembly, which leads to improved ease of assembly.

[0099] Here, the regulating projection 86 includes a pair of projection pieces 861 located at both circumferential ends of the retainer 8 in each of the plurality of pockets 80. Specifically, each of the pair of projection pieces 861 is positioned at the corner between the second side wall 802 and the partition wall 800. Furthermore, the pair of projection pieces 861 are positioned at the end of the second side wall 802 on the outer ring 62 side.

[0100] This makes it easier to insert the rolling element 63 into the pocket 80, as the pair of protruding pieces 861 are less likely to get in the way, leading to improved assembly.

[0101] Furthermore, the surface of the restricting projection 86 facing the first side wall 801 is inclined with respect to the second side wall 802 so as to follow the first side wall 801. Specifically, each of the pair of projection pieces 861 is formed in a roughly triangular pyramidal shape. As a result, when fitting the rolling element 63 into the pocket 80, the restricting projection 86 (the pair of projection pieces 861) is less likely to get in the way, leading to improved assembly. Moreover, in a retainer 8 made of molded resin or the like, the restricting projection 86 can be molded while avoiding an undercut shape.

[0102] Next, with reference to Figure 13, an example of the assembly procedure for the inner ring 61, the cage 8, and the rolling elements 63 will be described.

[0103] First, the retainer 8 is attached from above to the inner ring 61, which is placed on the workbench with the raceway surface 611 facing upwards. At this time, the inner circumferential surface of the retainer 8 comes into contact with the adjacent surface 612, thereby positioning the retainer 8 relative to the inner ring 61.

[0104] Then, the rolling elements 63 are inserted into the pockets 80 of the retainer 8 from above (the outer ring 62 side). At this time, by utilizing the elastic deformation of the retainer 8, the rolling elements 63 can be assembled by hand without the need for any special tools.

[0105] Here, the rolling element 63 is inserted into the pocket 80 with rotation, using the contact point between the first end face 631 and the first side wall 801 as a pivot point, with its first end face 631 in line contact with the first side wall 801. At this time, the second side wall 802 acts as a guide for the second end face 632, making it easier to insert the rolling element 63 into the pocket 80. Furthermore, the rolling element 63 is guided into the pocket 80 while avoiding the restricting projection 86 (a pair of projection pieces 861).

[0106] When the rolling element 63 is fully inserted into the pocket 80, the restricting projection 86 (a pair of projection pieces 861) prevents the rolling element 63 from falling out of the pocket 80. In other words, the rolling element 63 is positioned at three points: the contact area between the first end face 631 and the first side wall 801, and the pair of projection pieces 861, thus preventing it from falling out of the pocket 80.

[0107] In addition, because the inner ring 61 has a flange portion 613, when the rolling element 63 is housed in the pocket 80, the rolling element 63 catches on the flange portion 613, thus preventing the rolling element 63 and the retainer 8 from falling out of the inner ring 61.

[0108] Furthermore, as shown in Figure 14, the retainer 8 has a guide portion 803 at the inner ring 61 side end of the bulkhead 800. The guide portion 803 guides the rotation of the rolling element 63 by reducing the gap between the pocket 80 and the rolling element 63 when viewed from one side of the rolling axis. The guide portion 803 is formed by increasing the width dimension (circumferential dimension) of the bulkhead 800. Here, the guide portion 803 is formed in a triangular cross-section that widens as it approaches the raceway surface 611 of the inner ring 61. The presence of such a guide portion 803 stabilizes the orientation of the rolling element 63 during rotation.

[0109] Furthermore, in this embodiment, by employing, for example, an axial draw method as the molding method for the retainer 8, and creating a structure without forced removal areas, more stable product accuracy can be maintained.

[0110] <Variation> Embodiment 1 is merely one of many reference examples provided in this disclosure. Embodiment 1 can be modified in various ways depending on the design, etc., as long as it achieves the objectives of this disclosure. Furthermore, the drawings referenced in this disclosure are all schematic diagrams, and the ratios of the size and thickness of each component shown in the drawings do not necessarily reflect the actual dimensional ratios. The following lists some modifications of Embodiment 1. The modifications described below can be combined and applied as appropriate.

[0111] The number of crankshafts 7A, 7B, and 7C is not limited to "3"; it may be 2 or 4 or more. Furthermore, if there is only one crankshaft, an eccentric oscillating internal meshing planetary gear system can be realized where the rotation axis Ax1 and the axis Ax2 of the crankshaft coincide, rather than a distribution type. In this case, the planetary gear 3 oscillates when the crankshaft is driven, and the pair of carriers 18 and 19 can be rotated relative to the gear body 22 around the rotation axis Ax1.

[0112] Furthermore, while Embodiment 1 illustrates two types of gear systems 1 with planetary gears 3, the gear system 1 may have three or more planetary gears 3. For example, if the gear system 1 has three planetary gears 3, it is preferable that these three planetary gears 3 are arranged with a phase difference of 120 degrees around the rotation axis Ax1. Alternatively, the gear system 1 may have only one planetary gear 3. Or, if the gear system 1 has three planetary gears 3, two of these three planetary gears 3 may be in phase, and the remaining planetary gear 3 may be arranged with a phase difference of 180 degrees around the rotation axis Ax1.

[0113] Furthermore, the bearing device 6 may 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 elements 63 are not limited to being substantially cylindrical (approximately cylindrical), but may also be, for example, frustoconical.

[0114] Furthermore, the number of teeth of the input gear 501, the number of teeth of the crankshaft gears 502A, 502B, and 502C, the number of external pins 23 (number of teeth of internal teeth 21), and the number of teeth of external teeth 31 described in Embodiment 1 are merely examples and can be changed as appropriate.

[0115] Furthermore, the eccentric bearing 5 is not limited to a roller bearing; for example, it may be a deep groove ball bearing or an angular contact ball bearing.

[0116] Furthermore, the material of each component of the gear mechanism 1 is not limited to metal; for example, it may be a resin such as engineering plastic. Conversely, the material of the retainer 8 is not limited to resin; for example, it may be a metal or the like.

[0117] Furthermore, the gear unit 1 only needs to be able to output the relative rotation between the inner ring 61 and the outer ring 62 of the bearing unit 6, and is not limited to a configuration in which the rotational force of the inner ring 61 (input carrier 18 and output carrier 19) is output. For example, the rotational force of the outer ring 62 (case 10) that rotates relative to the inner ring 61 may be output.

[0118] Furthermore, in Embodiment 1, the output end face 76 of the rotation axis Ax1 of the crankshafts 7A, 7B, and 7C is in direct contact with the output side cover 14. However, the configuration is not limited to this, and a plate-shaped component, such as a shim, may be placed between the end face 76 and the output side cover 14. In this case, when attaching the output side cover 14, the gap between the end face 76 and the output side cover 14 can be adjusted in the axial direction by adjusting the thickness (and / or number) of the plate-shaped component, thereby adjusting the "play" in the axial direction of the crankshafts 7A, 7B, and 7C. Moreover, the plate-shaped component functions as a raceway (raceway disc) that reduces friction between the end face 76 and the output side cover 14.

[0119] Furthermore, the retainer 8 may be divided into a plurality of segmented members in the circumferential direction.

[0120] Furthermore, it is not essential that the retainer 8 be a single, indivisible part; the retainer 8 may have a first block and a second block that are separable in the direction of the central axis (rolling axis) of the rolling element 63. In other words, the retainer 8 may not be composed of a single, indivisible part, but rather by joining a first block and a second block. In this case, the first block has a plurality of pockets 80 that are open to the second end face 632 side of the rolling axis, and the second block is combined with the first block so as to close these plurality of pockets 80 from the second end face 632 side of the rolling axis. The second block is configured to be fixable to the first block by, for example, an appropriate mounting structure such as a pin or a groove-and-groove fitting.

[0121] Furthermore, the retainer 8 only needs to be able to contact both the raceway surface 611 and the adjacent surface 612 of the raceway forming member, which consists of at least one of the outer ring 62 and the inner ring 61, and the raceway forming member is not limited to the inner ring 61. In other words, the raceway forming member may be the outer ring 62, or it may be both the outer ring 62 and the inner ring 61.

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

[0123] (Embodiment 2) As shown in Figure 15, the shape of the retainer 8 in the bearing device 6A according to this embodiment differs from that of the bearing device 6 according to Embodiment 1. Hereinafter, components similar to those in Embodiment 1 will be denoted by the same reference numerals and their descriptions will be omitted as appropriate. The bearing device 6A, like the bearing device 6 in Embodiment 1, is also used in the gear device 1 as the first main bearing 601 and the second main bearing 602.

[0124] Figure 15 is a cross-sectional view corresponding to the section along line A1-A1 in Figure 7. However, in Figure 15, hatching is omitted for parts other than the retainer 8, even in the cross-sectional view.

[0125] In other words, in the bearing device 6A according to this embodiment, the first side wall 801 has a chamfered corner facing the first end face 631 of the rolling element 63, and is formed in a pentagonal cross-section. When the rolling element 63 is arranged with its rolling axis (central axis) inclined with respect to the rotation axis Ax1, one side (plane) of the pentagonal cross-section of the first side wall 801 faces the first end face 631 of the rolling element 63. As a result, the first side wall 801 comes into contact with the first end face 631 of the rolling element 63 on one of its surfaces, enabling surface contact with the first end face 631. In other words, in this embodiment, both the first side wall 801 and the second side wall 802 are configured to be able to make surface contact with the rolling element 63.

[0126] However, the contact area between the first side wall 801 and the first end face 631 is smaller than the contact area between the second side wall 802 and the second end face 632. In short, in the example of Figure 15, the length of one side of the pentagonal cross-section of the first side wall 801 that faces the first end face 631 is shorter than the length of one side of the pentagonal cross-section of the second side wall 802 that faces the second end face 632. As a result, the contact between the first side wall 801 and the rolling element 63 is neither line contact nor point contact, but surface contact, and the contact area between the first side wall 801 and the first end face 631 is smaller than the contact area between the second side wall 802 and the second end face 632.

[0127] This makes it less likely for assembly to be affected, even when the tightening allowance of the pocket 80 is large. As a result, there is an advantage in that a bearing device 6A can be provided that can more properly hold the rolling elements 63 in the retainer 8.

[0128] The configuration of Embodiment 2 can be adopted in appropriate combination with the various configurations (including modified versions) described in Embodiment 1.

[0129] (summary) As described above, the bearing device (6,6A) according to the first embodiment comprises an outer ring (62), an inner ring (61), a plurality of conical or cylindrical rolling elements (63), and an annular cage (8). The inner ring (61) is positioned inside the outer ring (62). The plurality of rolling elements (63) are positioned between the outer ring (62) and the inner ring (61). The cage (8) holds the plurality of rolling elements (63) between the outer ring (62) and the inner ring (61). Each of the plurality of rolling elements (63) has a first end face (631) and a second end face (632) on both sides in the direction along the rolling axis which is the central axis. The cage (8) has a plurality of pockets (80) that accommodate each of the plurality of rolling elements (63). In each of the multiple pockets (80), the contact area between the first end face (631) and the first side wall (801) facing the first end face (631) is smaller than the contact area between the second end face (632) and the second side wall (802) facing the second end face (632).

[0130] According to this embodiment, even when assembly is performed by press-fitting the rolling elements (63) into the pockets (80) of the retainer (8), the first side wall (801) makes line or point contact with the first end face (631), and the second side wall (802) makes surface contact with the second end face (632), making it easier to hold the rolling elements (63) in the pockets (80) and preventing them from falling out. Moreover, since the contact area of ​​the first side wall (801) with the first end face (631) is smaller than the contact area of ​​the second side wall (802) with the second end face (632), assembly is not easily reduced even when the tightening allowance of the pockets (80) is large. As a result, there is an advantage in that a bearing device (6,6A) can be provided that can more appropriately hold the rolling elements (63) in the retainer (8).

[0131] In the bearing device (6,6A) according to the second embodiment, in the first embodiment, the rolling shaft (63) is inclined with respect to the rotation axis (Ax1) such that its first end face (631) faces the rotation axis (Ax1), which is the central axis of the outer ring (62).

[0132] According to this embodiment, the bearing device (6,6A) can be realized with a simpler structure, and it becomes easier to make the bearing device (6,6A) more compact.

[0133] In the bearing device (6,6A) according to the third embodiment, in the first or second embodiment, the retainer (8) has a regulating projection (86) on the second side wall (802) that restricts the multiple rolling elements (63) from falling out of the multiple pockets (80).

[0134] According to this embodiment, the rolling elements (63) are prevented from falling out of the retainer (8) at least during assembly, leading to improved ease of assembly.

[0135] In the bearing device (6,6A) according to the fourth embodiment, in the third embodiment, the surface of the regulating projection (86) facing the first side wall (801) is inclined with respect to the second side wall (802) so as to be along the first side wall (801).

[0136] According to this embodiment, when fitting the rolling element (63) into the pocket (80), the restricting projection (86) is less likely to get in the way, leading to improved ease of assembly.

[0137] In the fifth embodiment of the bearing device (6,6A), in the third or fourth embodiment, the regulating projection (86) includes a pair of projections (861) located at both circumferential ends of the retainer (8) in each of the plurality of pockets (80).

[0138] According to this embodiment, when fitting the rolling element (63) into the pocket (80), the pair of protruding pieces (861) are less likely to get in the way, leading to improved ease of assembly.

[0139] In the bearing device according to the sixth embodiment (6,6A), in any of the first to fifth embodiments, the inner ring (61) has a raceway surface (611) on which each of the plurality of rolling elements (63) rolls, and a flange portion (613) adjacent to the raceway surface (611) and capable of contacting the first end surface (631).

[0140] In this embodiment, the flange portion (613) restricts the movement of the rolling element (63) at least toward the first end face (631). Similarly, the retainer (8) that holds the rolling element (63) is also restricted from moving at least toward the first end face (631).

[0141] In the bearing device (6,6A) according to the seventh embodiment, in any of the first to sixth embodiments, the first side wall (801) can make line contact or point contact with the first end face (631), and the second side wall (802) can make surface contact with the second end face (632).

[0142] According to this embodiment, the contact with the first end face (631) of the first side wall (801) is line contact or point contact, and the contact with the second end face (632) of the second side wall (802) is surface contact, thereby making the contact area with the first end face (631) of the first side wall (801) smaller than the contact area with the second end face (632) of the second side wall (802).

[0143] The gear device (1) according to the eighth embodiment comprises a first main bearing (601) and a second main bearing (602) consisting of bearing devices (6, 6A) according to any of the first to seventh embodiments, a first member and a second member. The second member is supported by the first member so as to be rotatable around a rotation axis (Ax1) via the first main bearing (601) and the second main bearing (602).

[0144] This embodiment has the advantage of providing a bearing device (6, 6A) and a gear device (1) that can more appropriately hold the rolling elements (63) in the retainer (8).

[0145] The configurations relating to the second to sixth aspects are not essential to the bearing device (6, 6A) and can be omitted as appropriate. [Explanation of Symbols]

[0146] 1. Gear system 6,6A Bearing Device 10 Case (First component) 18,19 Carrier (Second component) 601 First main bearing 602 Second main bearing 8 Cage 61 Inner ring (raceway forming member) 62 Outer ring (raceway forming member) 63 Rolling element 86 Regulating protrusions 611 Raceway surface 613 Tsuba (guard) 631 1st end face 632 Second end face 801 First side wall 802 Second side wall 861 Projection piece Ax1 Rotation axis

Claims

1. Outer ring and, An inner ring positioned inside the outer ring, A plurality of conical or cylindrical rolling elements are arranged between the outer ring and the inner ring, The system comprises an annular retainer that holds the plurality of rolling elements between the outer ring and the inner ring, Each of the aforementioned plurality of rolling elements has a first end face and a second end face on both sides in the direction along the rolling axis which serves as the central axis. The aforementioned retainer is, It has multiple pockets, each accommodating the multiple rolling elements, In each of the plurality of pockets, the contact area of ​​the first side wall facing the first end face with the first end face is smaller than the contact area of ​​the second side wall facing the second end face with the second end face. Bearing device.

2. The rolling shaft is inclined with respect to the rotation axis such that its first end face faces the rotation axis, which is the central axis of the outer ring. The bearing device according to claim 1.

3. The retainer has a regulating projection on its second side wall that restricts the rolling elements from falling out of the multiple pockets. The bearing device according to claim 1 or 2.

4. The surface of the restricting projection facing the first side wall is inclined with respect to the second side wall so as to be along the first side wall. The bearing device according to claim 3.

5. The restricting projection includes a pair of protruding pieces located at both ends in the circumferential direction of the retainer in each of the plurality of pockets. The bearing device according to claim 3.

6. The inner ring has a raceway surface on which each of the plurality of rolling elements rolls, and a flange portion adjacent to the raceway surface and capable of contacting the first end face. The bearing device according to claim 1 or 2.

7. The first side wall is capable of line contact or point contact with the first end face, and the second side wall is capable of surface contact with the second end face. The bearing device according to claim 1 or 2.

8. A first main bearing and a second main bearing comprising the bearing device according to claim 1 or 2, First member and The device comprises a second member supported by the first member so as to be rotatable around a rotation axis via the first and second main bearings, Gear mechanism.

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