Robotic manipulator structure and internally meshing planetary gear device

Abstract

The present application provides a robot arm structure including a joint device for a robot, and an internal meshing planetary gear device, and relates to the technical field of robots. The internal meshing planetary gear device includes: an internal tooth gear having internal teeth; a planetary gear having external teeth that partially mesh with the internal teeth; a crankshaft; and an eccentric shaft bearing. The crankshaft oscillates the planetary gear by rotating around a shaft center. The eccentric shaft bearing supports the crankshaft. The internal meshing planetary gear device oscillates the planetary gear, thereby relatively rotating the planetary gear around a rotation axis with respect to the internal tooth gear. The eccentric shaft bearing is composed of a sliding bearing. Thus, when viewed from one axial direction, the range occupied by the eccentric shaft bearing can be easily suppressed to be small.

Description

Technical Field

[0001] This invention relates to the field of robotics, and more particularly to a robotic arm structure including a joint device for robots and an internal meshing planetary gear device, wherein the joint device for robots includes the internal meshing planetary gear device. Background Technology

[0002] In Japanese Patent Application Publication No. 2016-75354, a type of eccentric oscillating internal meshing planetary gear device, known as a distribution type, is described (for example, see Patent Document 1). In the related internal meshing planetary gear device, multiple (e.g., three) crankshafts are arranged at positions offset from the axis of the internal gear. By synchronously driving each crankshaft by crankshaft gears, the planetary gear (external gear) oscillates while meshing internally with the internal gear.

[0003] The planetary gear system comprises a first planetary gear and a second planetary gear. A pair of supports are arranged on either side of the first and second planetary gears along their axial direction. Each crankshaft is supported on the supports by a pair of tapered roller bearings. When the input gear rotates, the three crankshaft gears simultaneously meshing with the input gear rotate in the same direction at the same speed. Each crankshaft gear is splined to a crankshaft, so the three crankshafts, reduced to the gear ratio of the input gear and the crankshaft gears, rotate in the same direction at the same speed. As a result, three first eccentric portions formed at the same axial position on the three crankshafts rotate synchronously, causing the first planetary gear to oscillate, and three second eccentric portions formed at the same axial position on the three crankshafts rotate synchronously, causing the second planetary gear to oscillate.

[0004] The first and second planetary gears mesh internally with internal gears, respectively. The internal gear has a gear body and pins (outer pin members) that are rotatably inserted into the gear body and form the internal teeth of the internal gear. Here, the number of teeth on the internal gear (the number of pin roots) is slightly more than the number of teeth on each planetary gear. Therefore, with each oscillation of each planetary gear, the first and second planetary gears experience a circumferential phase shift (rotation) relative to the internal gear by the difference in the number of teeth. This rotation is transmitted to a pair of supports as a revolution around the rotation axis of the internal gears on each crankshaft. This allows the pair of supports to rotate relative to the gear body (and the integrated housing) about the rotation axis.

[0005] In the structure of the aforementioned patent document, the eccentric shaft bearings (tapered roller bearings) supporting each crankshaft have multiple rolling elements (tapered rollers) around the crankshaft. Therefore, when the internal meshing planetary gear device is viewed from the axial direction (the direction parallel to the rotation axis), the area occupied by the eccentric shaft bearings becomes larger, hindering the miniaturization of the internal meshing planetary gear device, etc. Summary of the Invention

[0006] The object of the present invention is to provide a robotic arm structure including a robotic joint device and an internal meshing planetary gear device, which, when viewed from the axial side, easily minimizes the area occupied by the bearing of the eccentric shaft.

[0007] One aspect of the invention relates to a robotic arm structure, comprising a robotic joint device, wherein the robotic joint device includes: an internal meshing planetary gear device, comprising: an internal gear having internal teeth; a planetary gear having external teeth partially meshing with the internal teeth; a crankshaft that oscillates the planetary gear by rotating about an axis; and an eccentric shaft bearing supporting the crankshaft, wherein oscillating the planetary gear causes the planetary gear to rotate relative to the internal gear about a rotation axis, the eccentric shaft bearing being a sliding bearing; a first member fixed to the internal gear; and a second member that rotates relative to the first member in conjunction with the relative rotation of the planetary gear relative to the internal gear.

[0008] One aspect of the present invention provides an internal meshing planetary gear assembly comprising: an internal gear having internal teeth; planetary gears having external teeth that partially mesh with the internal teeth; a crankshaft; and an eccentric shaft bearing. The crankshaft oscillates the planetary gears by rotating about its axis. The eccentric shaft bearing supports the crankshaft. The internal meshing planetary gear assembly oscillates the planetary gears, thereby causing them to rotate relative to the internal gear about a rotation axis. The eccentric shaft bearing is a sliding bearing.

[0009] One aspect of the present invention provides a robot joint device comprising: the internal meshing planetary gear assembly; a first member fixed to the internal gear; and a second member that rotates relative to the first member in conjunction with the relative rotation of the planetary gear relative to the internal gear.

[0010] According to the present invention, a robot arm structure including a robot joint device and an internal meshing planetary gear device are provided, which can easily minimize the area occupied by the bearing of the eccentric shaft when viewed from the axial side. Attached Figure Description

[0011] Figure 1 It is a perspective view of the schematic structure of the actuator of the internal meshing planetary gear device, which includes the basic structure;

[0012] Figure 2 This is a schematic exploded perspective view of the aforementioned internal meshing planetary gear device as seen from the input side of the rotating shaft;

[0013] Figure 3 This is a schematic exploded perspective view of the aforementioned internal meshing planetary gear device as seen from the output side of the rotating shaft;

[0014] Figure 4 This is a schematic cross-sectional view of the aforementioned internal meshing planetary gear assembly;

[0015] Figure 5 This illustrates the aforementioned internal meshing planetary gear mechanism. Figure 4 Sectional view along line A1-A1;

[0016] Figure 6 This illustrates the aforementioned internal meshing planetary gear mechanism. Figure 4 Sectional view along line B1-B1;

[0017] Figure 7 This is a schematic cross-sectional view of the internal meshing planetary gear device according to Embodiment 1;

[0018] Figure 8 This is a schematic cross-sectional view showing the crankshaft periphery of the aforementioned internal meshing planetary gear assembly;

[0019] Figure 9 This illustrates the aforementioned internal meshing planetary gear assembly. Figure 8 A1-A1 line view and Figure 8 View along line B1-B1;

[0020] Figure 10 This is a schematic diagram of a robot joint device that uses the aforementioned internal meshing planetary gear mechanism;

[0021] Figure 11 This is a schematic cross-sectional view of an internal meshing planetary gear device, a variation of Embodiment 1.

[0022] Figure 12 This is a schematic cross-sectional view of an internal meshing planetary gear device, which is another variation of Embodiment 1.

[0023] Figure 13 This is a schematic cross-sectional view of an internal meshing planetary gear device, a variation of Embodiment 2.

[0024] Figure 14 This is a schematic cross-sectional view showing the crankshaft periphery of the aforementioned internal meshing planetary gear assembly.

[0025] Explanation of reference numerals in the attached figures

[0026] 1. 1A, 1B Internal meshing planetary gear assembly; 2 Internal gear; 3 Planetary gear; 7A, 7B, 7C Crankshaft; 21 Internal gear; 22 Gear body; 23 Pin; 31 External gear (first external gear, second external gear); 40 Bearing hole; 200 Robot joint device (i.e., robot manipulator structure); 201 First component; 202 Second component; 221 Inner circumferential surface; 223 Inner circumferential groove; 501 Input gear; Ax1 Rotating shaft. Detailed Implementation

[0027] (Basic Structure)

[0028] (1) Summary

[0029] The following is a summary of the internal meshing planetary gear device 1 of this basic structure, referring to... Figures 1-4 The accompanying drawings, which are used in this invention, are schematic diagrams, and the size and thickness ratios of the structural elements shown may not reflect the actual dimensional ratios. For example, Figures 1-4 The tooth shape, size, and number of teeth of the inner tooth 21 and the outer tooth 31 are merely schematic representations for illustrative purposes, and their main purpose is not limited to the shape shown in the illustration.

[0030] The internal meshing planetary gear assembly 1 (hereinafter also simply referred to as "gear assembly 1") of this basic structure is a gear assembly including an internal gear 2 and a planetary gear 3. In this gear assembly 1, the planetary gear 3 is arranged inside the annular internal gear 2 and oscillated, thereby causing the planetary gear 3 to rotate relative to the internal gear 2. In addition, the internal meshing planetary gear assembly 1 also includes a bearing member 6, which has 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 able to rotate relative to the outer ring 62. In particular, the gear assembly 1 of this basic structure is a type of eccentric oscillating internal meshing planetary gear assembly called a distribution type.

[0031] like Figures 1-4 As shown, the gear assembly 1 of this basic structure includes multiple (three in the basic structure) crankshafts (eccentric shafts) 7A, 7B, and 7C disposed at positions offset from the axis (rotation shaft Ax1) of the internal gear 2. Further, the gear assembly 1 includes an input shaft 500 disposed on the axis (rotation shaft Ax1) of the internal gear 2, centered on the rotation shaft Ax1, and an input gear 501 integrally formed with the input shaft 500. Crankshaft gears 502A, 502B, and 502C are respectively splined to the multiple crankshafts 7A, 7B, and 7C. These multiple (three in the basic structure) crankshaft gears 502A, 502B, and 502C are arranged to mesh with the input gear 501. Therefore, when the input shaft 500 is driven, the gear assembly 1 synchronously drives the crankshafts 7A, 7B, and 7C using the input gear 501, thereby causing the planetary gear 3 to oscillate.

[0032] The internal gear 2 has internal teeth 21 and is fixed to the outer ring 62. Specifically, in this basic structure, the internal gear 2 has an annular gear body 22 and multiple pins 23. The multiple pins 23 are held in a rotatable state on the inner circumferential surface 221 of the gear body 22, thus forming the internal teeth 21. The planetary gear 3 has external teeth 31 that partially mesh with the internal teeth 21. That is, inside the internal gear 2, the planetary gear 3 is tangent to the internal gear 2, becoming a part of the external teeth 31 meshing with a part of the internal teeth 21. In this state, when multiple crankshafts 7A, 7B, and 7C are driven, the planetary gear 3 oscillates, and the meshing position of the internal teeth 21 and external teeth 31 moves along the circumferential direction of the internal gear 2, generating a relative rotation between the two gears (internal gear 2 and planetary gear 3) corresponding to the difference in the number of teeth between the planetary gear 3 and the internal gear 2. Here, if the internal gear 2 is fixed, the planetary gear 3 rotates (rotates) along with the relative rotation of the two gears. As a result, a rotational output that is reduced at a relatively high reduction ratio can be obtained from planetary gear 3, corresponding to the difference in the number of teeth between the two gears.

[0033] This gear device 1 is used in such a way that the rotation of the planetary gear 3, corresponding to its rotational component, is achieved by rotating a pair of supports 18 and 19 that are fixed relative to the inner ring 61 of the bearing member 6 through integration or embedding. Thus, the gear device 1 functions as a gear device with a relatively high reduction ratio, using the input shaft 500 as the input side and the pair of supports 18 and 19 as the output side. Therefore, in this basic structure of the gear device 1, multiple crankshafts 7A, 7B, and 7C are supported by a pair of supports 18 and 19 in order to transmit the rotation of the planetary gear 3, corresponding to its rotational component, to the pair of supports 18 and 19. The pair of supports 18 and 19 are arranged on both sides of the axial direction (along the direction of the rotation axis Ax1) of the planetary gear 3 and rotatably support each crankshaft 7A, 7B, and 7C.

[0034] Here, multiple crankshafts 7A, 7B, and 7C, each inserted into a plurality of openings 33 formed in the planetary gear 3, rotate relative to the internal gear 2 as the planetary gear 3 rotates. Furthermore, each crankshaft 7A, 7B, and 7C has a central shaft 71 and an eccentric portion 72 eccentric to the central shaft 71. A pair of supports 18 and 19 rotatably support the central shaft 71 of each crankshaft 7A, 7B, and 7C, and the eccentric portion 72 of each crankshaft 7A, 7B, and 7C is inserted into the openings 33 of the planetary gear 3. When each crankshaft 7A, 7B, and 7C rotates around its respective central shaft 71, each eccentric portion 72 rotates eccentrically relative to its respective central shaft 71 (eccentric motion). Accompanying this, the planetary gear 3 oscillates. Through the oscillation of the planetary gear 3, the planetary gear 3 partially meshes with the internal gear 2 and rotates relative to the internal gear 2. As a result, planetary gear 3 rotates on its own central axis while revolving within internal gear 2 in a manner revolving around the rotation axis Ax1. Along with the rotation of planetary gear 3, each crankshaft 7A, 7B, and 7C revolves around the rotation axis Ax1, and the supports 18 and 19 of the shaft center 71 supporting each crankshaft 7A, 7B, and 7C rotate on their own axes in accordance with the revolution of each crankshaft 7A, 7B, and 7C. In this way, through multiple crankshafts 7A, 7B, and 7C, the rotation component (rotation component) of planetary gear 3, excluding the oscillation component (revolution component), is transmitted to a pair of supports 18 and 19.

[0035] In addition, such as Figure 1 As shown, the gear assembly 1 and the drive source 101 together constitute the actuator 100 of this basic structure. In other words, the actuator 100 of this basic structure includes the gear assembly 1 and the drive source 101. The drive source 101 generates a driving force for oscillating the planetary gear 3. Specifically, the drive source 101 causes the input shaft 500 to rotate about the rotation axis Ax1, thereby causing the planetary gear 3 to oscillate.

[0036] (2) Definition

[0037] The term "ring-shaped" as used in this invention refers to a shape that forms a circle (ring) enclosing a space (region) on the inside when viewed from above, and is not limited to a circular shape (ring-shaped) that is perfectly round when viewed from above. For example, it can also be an elliptical shape or a polygonal shape. Furthermore, for example, even a shape with a bottom, such as a cup, is included in the term "ring-shaped" as long as its peripheral walls are ring-shaped.

[0038] In this invention, "revolution" refers to an object revolving 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 a revolution path centered on the axis of rotation. Therefore, for example, when an object rotates around an eccentric axis parallel to the central axis passing through its center (center of gravity), the object revolves around this eccentric axis. As an example, planetary gear 3 revolves within internal gear 2 by oscillating and rotating around the axis of rotation Ax1.

[0039] Additionally, in the disclosure, one side of the rotation axis Ax1 is ( Figure 4 The left side of the axis (Ax1) is called the "output side", and the other side of the axis (Ax1) is called the "output side". Figure 4 The right side (of the input side) is referred to as the "input side". Figure 4 In the example, rotation is imparted to the input shaft 500 from the "input side" of the rotation shaft Ax1, and rotation is taken out from the "output side" of the rotation shaft Ax1 for a pair of brackets 18 and 19. However, "input side" and "output side" are merely labels given for illustrative purposes, and their main purpose is not limited to the positional relationship of the input and output observed from the gear device 1.

[0040] In this invention, the term "rotation axis" refers to a virtual axis (straight line) that serves as the center of rotational motion of the rotating body. In other words, rotation axis Ax1 is a virtual axis without a physical form. The input axis 500 rotates around rotation axis Ax1.

[0041] In this invention, "internal teeth" and "external teeth" refer to a collection (group) of multiple "teeth" rather than a single "teeth". That is, the internal teeth 21 of the internal gear 2 are composed of a collection of multiple teeth disposed on the inner circumferential surface 221 of the internal gear 2 (gear body 22). Similarly, the external teeth 31 of the planetary gear 3 are composed of a collection of multiple teeth disposed on the outer circumferential surface of the planetary gear 3.

[0042] (3) Structure

[0043] The following detailed structure of the internal meshing planetary gear device 1 of this basic structure is described in reference to... Figures 1-6 Please provide an explanation.

[0044] Figure 1 This is a perspective view showing the schematic structure of the actuator 100, which includes the gear mechanism 1. Figure 1 The drive source 101 is schematically shown in the diagram. Figure 2 This is a schematic exploded perspective view of the gear device 1 as seen from the input side of the rotating shaft Ax1. Figure 3 This is a schematic exploded perspective view of the gear device 1 as seen from the output side of the rotating shaft Ax1. Figure 4 This is a schematic cross-sectional view of gear assembly 1. Figure 5 yes Figure 4 Sectional view along line A1-A1. Figure 6 yes Figure 4 The sectional view along line B1-B1. Wherein... Figure 5 and Figure 6 In the diagram, for components other than crankshafts 7A, 7B, and 7C, although they are also cross-sections, the cross-sectional lines are omitted.

[0045] (3.1) Overall Structure

[0046] like Figures 1-4 As shown, the gear assembly 1 of this basic structure includes an internal gear 2, a planetary gear 3, a bearing component 6, multiple crankshafts 7A, 7B, and 7C, a pair of supports 18 and 19, and an input shaft 500. Furthermore, in this basic structure, the gear assembly 1 also includes an input gear 501, multiple crankshaft gears 502A, 502B, and 502C, a pair of eccentric shaft bearings 41 and 42, an eccentric body bearing 5, and a housing 10. In this basic structure, the internal gear 2, planetary gear 3, multiple crankshafts 7A, 7B, and 7C, and the pair of supports 18 and 19, which are structural elements of the gear assembly 1, are made of stainless steel, cast iron, carbon steel for mechanical structures, chromium-molybdenum steel, phosphor bronze, or aluminum bronze, or light metals such as aluminum or titanium. The metals mentioned here include metals that have undergone surface treatments such as nitriding.

[0047] Furthermore, in this basic structure, as an example of gear device 1, an internally tangent planetary gear reduction device with cycloidal tooth profile is illustrated. That is, gear device 1 of this basic structure includes an internally tangent planetary gear 3 with cycloidal curved tooth profile.

[0048] Furthermore, in this basic structure, as an example, the gear device 1 is used with the gear body 22 of the internal gear 2 and the outer ring 62 of the bearing member 6 fixed to a fixed member such as the housing 10. Thus, as the internal gear 2 and the planetary gear 3 rotate relative to each other, the planetary gear 3 rotates relative to the fixed member (such as the housing 10).

[0049] Furthermore, in this basic structure, when the gear device 1 is used in the actuator 100, by applying a rotational force as input to the input shaft 500, a rotational force as output is extracted from a pair of supports 18, 19 integrated with the inner ring 61 of the bearing member 6. In other words, the gear device 1 operates with the rotation of the input shaft 500 as input rotation and the rotation of the pair of supports 18, 19 integrated with the inner ring 61 as output rotation. Thus, in the gear device 1, an output rotation that is reduced at a relatively high reduction ratio relative to the input rotation can be obtained.

[0050] The drive source 101 is a power source such as an electric motor. The power generated by the drive source 101 is transmitted to the input shaft 500 in the gear assembly 1. Specifically, the drive source 101 is connected to the input shaft 500, and the power generated by the drive source 101 is transmitted to the input shaft 500. Thus, the drive source 101 can rotate the input shaft 500.

[0051] Furthermore, in the gear device 1 of this basic structure, as... Figure 4 As shown, the input-side rotation axis Ax1 and the output-side rotation axis Ax1 are on the same straight line. In other words, the input-side rotation axis Ax1 and the output-side rotation axis Ax1 are coaxial. Here, the input-side rotation axis Ax1 is the rotation center of the input shaft 500, which is given input rotation, and the output-side rotation axis Ax1 is the rotation center of the inner ring 61 (and the pair of supports 18, 19) that generate output rotation. That is to say, in the gear device 1, it is possible to obtain an output rotation that is reduced in speed by a relatively high reduction ratio by rotating coaxially relative to the input.

[0052] like Figure 5 and Figure 6 As shown, the internal gear 2 is an annular component with internal teeth 21. In this basic structure, the internal gear 2 has an annular shape, at least its inner circumferential surface being a perfect circle when viewed from above. Internal teeth 21 are formed along the circumferential direction of the annular internal gear 2 on its inner circumferential surface. All teeth constituting the internal teeth 21 are of the same shape and are evenly spaced throughout the entire circumferential region of the inner circumferential surface of the internal gear 2. That is, the pitch circle of the internal teeth 21 is a perfect circle when viewed from above. The center of the pitch circle of the internal teeth 21 is located on the rotation axis Ax1. Furthermore, the internal gear 2 has a predetermined thickness along the direction of the rotation axis Ax1. The tooth directions of the internal teeth 21 are all parallel to the rotation axis Ax1. The dimension of the internal teeth 21 in the tooth direction is slightly smaller than that in the thickness direction of the internal gear 2.

[0053] Here, as described above, the internal gear 2 has an annular (ring-shaped) gear body 22 and multiple pins 23. The multiple pins 23 are held in a rotatable state on the inner circumferential surface 221 of the gear body 22, forming the internal gear 21. In other words, the multiple pins 23 function as multiple teeth constituting the internal gear 21. Specifically, as... Figure 2As shown, a plurality of inner circumferential grooves 223 are formed on the inner circumferential surface 221 of the gear body 22, covering the entire circumferential direction. All of the inner circumferential grooves 223 are of the same shape and are arranged at equal intervals. The inner circumferential grooves 223 are parallel to the rotation axis Ax1 and are formed along the entire thickness direction of the gear body 22. A plurality of pins 23 are assembled to the gear body 22 by being fitted into the inner circumferential grooves 223. Each pin 23 is held in a state where it can rotate within its inner circumferential groove 223. Furthermore, the gear body 22 (together with the outer ring 62) is fixed to the housing 10. Further, a plurality of fixing holes 222 for fixing are formed in the gear body 22 (see reference). Figure 5 ).

[0054] like Figure 5 and Figure 6 As shown, the planetary gear 3 is an annular component with external teeth 31. In this basic structure, the planetary gear 3 has an annular shape whose outer circumferential surface is a perfect circle when viewed from above. External teeth 31 are formed on the outer circumferential surface of the annular planetary gear 3 along the circumferential direction of the planetary gear 3. The multiple teeth constituting the external teeth 31 are all of the same shape and are evenly spaced throughout the entire circumferential region of the outer circumferential surface of the planetary gear 3. That is, the pitch circle of the external teeth 31 is a perfect circle when viewed from above. In addition, the planetary gear 3 has a predetermined thickness along the direction of the rotation axis Ax1. The external teeth 31 are formed along the entire length of the thickness direction of the planetary gear 3. The tooth direction of the external teeth 31 is parallel to the rotation axis Ax1. Unlike the internal gear 2, the external teeth 31 and the main body of the planetary gear 3 are integrally formed by a single metal component.

[0055] Furthermore, the gear assembly 1 of this basic structure includes a plurality of planetary gears 3. Specifically, the gear assembly 1 includes two planetary gears 3: a first planetary gear 301 and a second planetary gear 302. The two planetary gears 3 are arranged opposite each other in a direction parallel to the rotation axis Ax1. That is, the planetary gears 3 comprise a first planetary gear 301 and a second planetary gear 302 arranged in a direction (axial direction) parallel to the rotation axis Ax1. The shapes of the first planetary gear 301 and the second planetary gear 302 are themselves generic.

[0056] These two planetary gears 3 (first planetary gear 301 and second planetary gear 302) are arranged about the rotation axis Ax1 with a phase difference of 180 degrees. Figure 4 In the example, the first planetary gear 301 and the second planetary gear 302 located on the input side of the rotating shaft Ax1 ( Figure 4 The center of the first planetary gear 301 (the center of the pitch circle of the external tooth 31) C1 on the right side is offset (offset) relative to the rotation axis Ax1 upwards. On the other hand, the output side of the rotation axis Ax1 ( Figure 4The center (center of the pitch circle of the external tooth 31) C2 of the second planetary gear 302 (on the left side) is offset (offset) downwards relative to the rotation axis Ax1. Here, the distance ΔL1 between the rotation axis Ax1 and the center C1 is the eccentricity of the first planetary gear 301 relative to the rotation axis Ax1, and the distance ΔL2 between the rotation axis Ax1 and the center C2 is the eccentricity of the second planetary gear 302 relative to the rotation axis Ax1. In this way, the multiple planetary gears 3 are evenly arranged in the circumferential direction centered on the rotation axis Ax1, thereby achieving a balance of weight and load among the multiple planetary gears 3.

[0057] In the first planetary gear 301 and the second planetary gear 302, their centers C1 and C2 are rotationally symmetrical about 180 degrees relative to the rotation axis Ax1. In this basic structure, although the orientations of the eccentricities ΔL1 and ΔL2 observed from the rotation axis Ax1 are opposite, their absolute values ​​are the same.

[0058] More specifically, each crankshaft 7A, 7B, and 7C has two eccentric portions 72 relative to the central axis 71. The eccentricity ΔL0 of the center C0 of these two eccentric portions 72 from the center (axis Ax2) of the central axis 71 is (refer to...) Figure 5 and Figure 6 The eccentricities ΔL1 and ΔL2 of the first planetary gear 301 and the second planetary gear 302 relative to the rotation axis Ax1 are the same, respectively. The shapes of the multiple crankshafts 7A, 7B, and 7C are interchangeable. The shapes of the multiple crankshaft gears 502A, 502B, and 502C are also interchangeable.

[0059] Additionally, a pair of supports 18 and 19 are arranged on both sides of the first planetary gear 301 and the second planetary gear 302 in a direction parallel to the rotation axis Ax1 (axial direction). With the pair of supports 18 and 19 distinguished from each other, the input side of the rotation axis Ax1 (in...) Figure 4 The bracket 18 (located on the right side) is called the "input side bracket 18". It is positioned on the output side of the rotating shaft Ax1 (in... Figure 4 The bracket 19 (left side, in the middle) is called the "output side bracket 19". The two ends of each crankshaft 7A, 7B, and 7C are held in a pair of brackets 18 and 19, separated by eccentric shaft bearings 41 and 42. That is, each crankshaft 7A, 7B, and 7C is held in a rotatable state on both sides of the planetary gear 3 in a direction parallel to the rotation axis Ax1, on both sides, relative to the planetary gear 3 (axial direction). Here, the eccentric shaft bearings 41 and 42 are both rolling bearings such as cylindrical roller bearings (including needle roller bearings) or tapered roller bearings.

[0060] An eccentric bearing 5 is fitted to the eccentric portion 72 of each crankshaft 7A, 7B, and 7C. Three openings 33 corresponding to the three crankshafts 7A, 7B, and 7C are formed on the first planetary gear 301 and the second planetary gear 302, respectively. An eccentric bearing 5 is housed in each opening 33. In other words, with the eccentric bearing 5 mounted on the first planetary gear 301 and the second planetary gear 302, and each crankshaft 7A, 7B, and 7C inserted into the eccentric bearing 5, the eccentric bearing 5 and each crankshaft 7A, 7B, and 7C are combined with the planetary gear 3. With the eccentric bearing 5 and the crankshafts 7A, 7B, and 7C combined in this state, when each crankshaft 7A, 7B, and 7C rotates, the planetary gear 3 oscillates around the rotation axis Ax1.

[0061] Based on the structure described above, by applying a rotational force as input to the input shaft 500, the input shaft 500 rotates around the rotation axis Ax1. This rotational force is then distributed from the input gear 501 to 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 it rotate in the same direction at the same speed. Since crankshafts 7A, 7B, and 7C are splined to each of the crankshaft gears 502A, 502B, and 502C, the three crankshafts 7A, 7B, and 7C rotate in the same direction at the same speed while being reduced in speed by a gear ratio relative to the input gear 501 and the crankshaft gears 502A, 502B, and 502C. As a result, the three eccentric portions 72 of the three crankshafts 7A, 7B, and 7C, located at the same position on the input side of the rotating shaft Ax1, rotate synchronously, causing the first planetary gear 301 to oscillate. Furthermore, the three eccentric portions 72 of the three crankshafts 7A, 7B, and 7C, located at the same position on the output side of the rotating shaft Ax1, rotate synchronously, causing the second planetary gear 302 to oscillate.

[0062] exist Figure 5 and Figure 6 The image shows the state of the first planetary gear 301 and the second planetary gear 302 at a certain moment. Figure 5 yes Figure 4 The A1-A1 sectional view shows the first planetary gear 301. Figure 6 yes Figure 4 The cross-sectional view along line B1-B1 shows the second planetary gear 302. (See figure) Figure 5 and Figure 6As shown, in the first planetary gear 301 and the second planetary gear 302, their centers C1 and C2 are located at approximately 180 degrees rotationally symmetrical relative to the rotation axis Ax1. In this basic structure, although the orientations of the eccentricities ΔL1 and ΔL2 observed from the rotation axis Ax1 are opposite, their absolute values ​​are approximately the same (both are eccentricities ΔL0). According to the above structure, the shaft center 71 rotates (rotates) around the shaft center Ax2, thereby causing the first planetary gear 301 and the second planetary gear 302 to rotate (eccentrically move) around the rotation axis Ax1 with an approximately 180-degree phase difference. Furthermore, the plurality of planetary gears 3 are arranged approximately equally in the circumferential direction centered on the rotation axis Ax1, thereby achieving a balance of weight and load among the plurality of planetary gears 3.

[0063] The planetary gears 3 (first planetary gear 301 and second planetary gear 302) configured in this way are positioned inside the internal gear 2. Viewed from above, the planetary gear 3 is one size smaller than the internal gear 2, and when combined with the internal gear 2, the planetary gear 3 can oscillate inside the internal gear 2. At this time, 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, with the planetary gear 3 positioned inside the internal gear 2, the external teeth 31 and the internal teeth 21 are opposite each other.

[0064] Furthermore, the pitch circle of the external tooth 31 is one rotation smaller than that of the internal tooth 21. Also, when the first planetary gear 301 is internally tangent to the internal gear 2, the center C1 of the pitch circle of the external tooth 31 of the first planetary gear 301 is located at a distance ΔL1 from the center of the pitch circle of the internal tooth 21 (rotation axis Ax1). Similarly, when the second planetary gear 302 is internally tangent to the internal gear 2, the center C2 of the pitch circle of the external tooth 31 of the second planetary gear 302 is located at a distance ΔL2 from the center of the pitch circle of the internal tooth 21 (rotation axis Ax1).

[0065] Therefore, in either the first planetary gear 301 or the second planetary gear 302, at least a portion of the external tooth 31 and the internal tooth 21 are opposed with a clearance. If the difference in the number of teeth between the external tooth 31 and the internal tooth 21 is greater than "2", they will not mesh together in the circumferential direction. However, the planetary gear 3 oscillates (revolves) around the rotation axis Ax1 inside the internal gear 2, so the external tooth 31 and the internal tooth 21 mesh partially. That is, by the oscillation of the planetary gear 3 (first planetary gear 301 and second planetary gear 302) around the rotation axis Ax1, as... Figure 5 and Figure 6 As shown, a portion of the teeth constituting the external teeth 31 meshes with a portion of the teeth constituting the internal teeth 21. As a result, in the gear assembly 1, a portion of the external teeth 31 can mesh with a portion of the internal teeth 21.

[0066] Here, the number of teeth of the internal gear 21 in the internal gear 2 is N more than the number of teeth of the external gear 31 in the planetary gear 3 (N is a positive integer). In this basic structure, 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 relative to the input rotation in the gear unit 1.

[0067] Furthermore, in this basic structure, 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. Further, the dimension of the tooth direction (parallel to the rotation axis Ax1) of the external teeth 31 of the combined first planetary gear 301 and the second planetary gear 302 is smaller than the dimension of the tooth direction (parallel to the rotation axis Ax1) of the internal teeth 21. In other words, in the direction parallel to the rotation axis Ax1, the external teeth 31 of the first planetary gear 301 and the second planetary gear 302 are contained within the tooth direction of the internal teeth 21.

[0068] Here, the first planetary gear 301 and the second planetary gear 302 are internally meshed with the internal gear 2. Therefore, with each oscillation, the first planetary gear 301 and the second planetary gear 302 experience a circumferential phase shift relative to the internal gear 2 (the difference in the number of teeth between the internal teeth 21 and the external teeth 31), and rotate. Through this rotation, the first planetary gear 301 and the second planetary gear 302 partially mesh with the internal teeth 21 of the internal gear 2 while revolving around the inner circumference of the internal gear 2 (i.e., revolving around the rotation axis Ax1). Accompanying the revolution of the planetary gear 3, the crankshafts 7A, 7B, and 7C inserted into the opening 33 of the planetary gear 3 revolve around the rotation axis Ax1. Thus, the revolution of the planetary gear 3 is transmitted to a pair of supports 18 and 19 via the multiple crankshafts 7A, 7B, and 7C. Thus, a pair of supports 18 and 19 can rotate relative to the gear body (and the integrated housing 10) with the rotation axis Ax1 as the center.

[0069] In summary, the gear mechanism 1 of this basic structure uses multiple crankshafts 7A, 7B, and 7C, positioned offset from the pivot Ax1, to oscillate the planetary gear 3, and utilizes the oscillation of the planetary gear 3 to obtain rotational output. That is, in the gear mechanism 1, when the planetary gear 3 oscillates, the meshing position of the internal gear 21 and the external gear 31 moves along the circumferential direction of the internal gear 2, generating a relative rotation between the two gears (internal gear 2 and planetary gear 3) corresponding to the difference in the number of teeth between the planetary gear 3 and the internal gear 2. Here, if the internal gear 2 is fixed, the planetary gear 3 rotates (spins) along with the relative rotation of the two gears. As a result, a rotational output that is reduced in speed at a relatively high reduction ratio, corresponding to the difference in the number of teeth between the two gears, can be obtained from the planetary gear 3.

[0070] The bearing component 6 is a part having an outer ring 62 and an inner ring 61 and used to extract 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 the inner ring 61, the bearing component 6 also has a plurality of rolling elements 63 (see reference). 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 are perfectly circular when viewed from above. The inner ring 61 is smaller than the outer ring 62 and is positioned inside the outer ring 62. Here, the inner diameter of the outer ring 62 is larger than the outer diameter of the inner ring 61, thus creating a gap between the inner circumferential surface of the outer ring 62 and the outer circumferential surface of the inner ring 61.

[0071] Multiple rolling elements 63 are disposed in the gap between the outer ring 62 and the inner ring 61. The multiple rolling elements 63 are arranged along the circumferential direction of the outer ring 62. All of the multiple rolling elements 63 are metal parts of the same shape and are evenly spaced throughout the entire circumferential area of ​​the outer ring 62.

[0072] More specifically, the gear assembly 1 of this basic structure includes a first main bearing 601 and a second main bearing 602, which respectively serve as bearing members 6. That is, the gear assembly 1 includes a pair of bearing members 6 formed by the first main bearing 601 and the second main bearing 602. Specifically, as... Figure 4 As shown, viewed from planetary gear 3 on the input side of rotating shaft Ax1 ( Figure 4 The first main bearing 601 is located on the right side of the planetary gear 3, at the output side of the rotating shaft Ax1. Figure 4 A second main bearing 602 is arranged on the left side. A pair of bearing members 6 are configured to withstand radial loads, thrust loads (along the direction of the rotation axis Ax1), and bending forces (bending moment loads) on the rotation axis Ax1 via the first main bearing 601 and the second main bearing 602.

[0073] Here, the first bearing member 601 and the second bearing member 602 are positioned opposite each other in the direction parallel to the rotation axis Ax1 relative to the planetary gear 3 (axial direction). That is, the bearing member 6 is a "combined angular ball bearing" that combines multiple (here, two) angular ball bearings. Here, as an example, the first bearing member 601 and the second bearing member 602 are "back-side combined type" bearing loads in the thrust direction (along the rotation axis Ax1) with their respective inner rings 61 approaching each other. Furthermore, in the gear assembly 1, the first bearing member 601 and the second bearing member 602 are combined to apply appropriate preload to the inner rings 61 by fastening their respective inner rings 61 towards each other.

[0074] Furthermore, in the gear device 1 of this basic structure, the input side bracket 18 and the output side bracket 19 are arranged on both sides of the planetary gear 3 in a direction parallel to the rotation axis Ax1, and pass through the bracket hole 34 of the planetary gear 3 (see reference). Figure 4 And they combine with each other. Specifically, such as Figure 4 As shown, viewed from planetary gear 3 on the input side of rotating shaft Ax1 ( Figure 4 The input side bracket 18 is configured on the right side of the planetary gear 3, and is located on the output side of the rotating shaft Ax1. Figure 4 An output-side bracket 19 is disposed on the left side. The inner ring 61 of the bearing member 6 (each of the first bearing member 601 and the second bearing member 602) is fixed to the input-side bracket 18 and the output-side bracket 19. In this basic structure, as an example, the inner ring of the first bearing member 601 is seamlessly integrated with the input-side bracket 18. Similarly, the inner ring of the second bearing member 602 is seamlessly integrated with the output-side bracket 19.

[0075] The output side bracket 19 has a plurality of (three in one example) bracket pins 191 protruding from one surface of the output side bracket 19 toward the input side of the rotation axis Ax1 (see reference). Figure 2 These multiple support pins 191 pass through multiple (three in one example) support holes 34 formed in the planetary gear 3. The front ends of the multiple support pins 191 are connected to the input side support 18 by support bolts 192 (see reference). Figure 7 To fix it, a gap is ensured between the support pin 191 and the inner circumferential surface of the support hole 34, allowing the support pin 191 to move within the support hole 34, that is, to move relative to the center of the support hole 34. Thus, when the planetary gear 3 oscillates, the support pin 191 does not contact the inner circumferential surface of the support hole 34.

[0076] With the above structure, the gear device 1 is used in such a way that the rotation of the planetary gear 3, corresponding to its rotational component, is taken out as a rotation of the input-side bracket 18 and the output-side bracket 19, which are integrated with the inner ring 61 of the bearing member 6. That is, in this basic structure, the relative rotation between the planetary gear 3 and the internal gear 2 is taken out from the input-side bracket 18 and the output-side bracket 19. In this basic structure, as an example, the gear device 1 uses the outer ring 62 of the bearing member 6 (refer to...) Figure 4 The planetary gear 3 is used in a fixed state within the housing 10, which serves as a fixed member. Specifically, the planetary gear 3 is connected to the input-side support 18 and the output-side support 19, which serve as rotating members, via multiple crankshafts 7A, 7B, and 7C. The gear body 22 is fixed to the fixed members, thus the relative rotation between the planetary gear 3 and the internal gear 2 is extracted from the rotating members (input-side support 18 and output-side support 19). In other words, in this basic structure, when the planetary gear 3 rotates relative to the gear body 22, the rotational force of the input-side support 18 and the output-side support 19 is extracted as an output.

[0077] Furthermore, in this basic structure, the housing 10 and the gear body 22 of the internal gear 2 are seamlessly integrated. That is, in the direction parallel to the rotation axis Ax1, the gear body 22, as a fixing member, is seamlessly and continuously arranged with the housing 10.

[0078] More specifically, the housing 10 is cylindrical and forms the outer contour of the gear assembly 1. In this basic structure, the central axis of the cylindrical housing 10 is aligned with the rotation axis Ax1. That is, at least the outer circumferential surface of the housing 10, when viewed from above (from the axial direction), is a perfect circle centered on the rotation axis Ax1. The housing 10 is formed as a cylinder with openings at both axial ends. Here, the housing 10 is seamlessly integrated with the gear body 22 of the internal gear 2, so that the housing 10 and the gear body 22 are treated as a single component. Therefore, the inner circumferential surface of the housing 10 includes the inner circumferential surface 221 of the gear body 22. Furthermore, the outer ring 62 of the bearing member 6 is fixed to the housing 10. That is, when viewed from the gear body 22 in the inner circumferential surface of the housing 10, the outer ring 62 of the first bearing member 601 is fixed to the input side of the rotation axis Ax1 by embedding. Figure 4 On the other hand, viewed from the gear body 22 in the inner circumferential surface of the housing 10, the outer ring 62 of the second bearing member 602 is fixed to the output side of the rotating shaft Ax1 by embedding. Figure 4 (Left side).

[0079] Furthermore, the input side of the rotation axis Ax1 of the housing 10 ( Figure 4 The right side of the housing 10 is blocked by the input side bracket 18, and the output side of the rotating shaft Ax1 of the housing 10 is closed. Figure 4The left end face is blocked by the output side bracket 19. Therefore, as Figure 4 As shown, the space surrounded by the housing 10, the input side bracket 18 and the output side bracket 19 houses components such as planetary gear 3 (first planetary gear 301 and second planetary gear 302), multiple pins 23 and eccentric bearing 5.

[0080] Multiple crankshafts 7A, 7B, and 7C (in a basic structure of three) each have a central shaft portion 71 and two eccentric portions 72. The central shaft portion 71 is cylindrical, with at least its outer circumferential surface being perfectly circular when viewed from above. The shaft center Ax2, serving as the center of the central shaft portion 71, is parallel to the rotation axis Ax1. The shaft centers Ax2 of the multiple crankshafts 7A, 7B, and 7C are arranged at equal intervals in the circumferential direction on a virtual circle centered on the rotation axis Ax1. Each eccentric portion 72 is disc-shaped, with at least its outer circumferential surface being perfectly circular when viewed from below. The center (central axis) C0 of each eccentric portion 72 is parallel to the rotation axis Ax1 and is positioned radially offset from the rotation axis Ax1. Here, the distance ΔL0 between the shaft center Ax2 and the center C0 (refer to...) Figure 5 and Figure 6 The eccentricity of the eccentric portion 72 relative to the axis 71 is such that it becomes an eccentricity relative to the axis 71. The eccentric portion 72 is a flange shape that protrudes from the center of the axis 71 along its entire circumference. According to the above structure, for each crankshaft 7A, 7B, 7C, the eccentric portion 72 moves eccentrically by rotating the axis 71 around the axis Ax2.

[0081] In this basic structure, the central shaft 71 and the two eccentric shafts 72 are integrally formed from a single metal component, thereby achieving seamless crankshafts 7A, 7B, and 7C. These crankshafts 7A, 7B, and 7C, in this shape, are combined with the eccentric bearings 5 ​​in the planetary gear 3. Therefore, with the planetary gear 3 assembled with the eccentric bearings 5 ​​and the crankshafts 7A, 7B, and 7C, the planetary gear 3 oscillates around the rotation axis Ax1 when the crankshafts 7A, 7B, and 7C rotate.

[0082] The eccentric bearing 5 has multiple rolling elements 51 (see reference). Figure 4 This component absorbs the rotational components of crankshafts 7A, 7B, and 7C and transmits only the rotational components of crankshafts 7A, 7B, and 7C—that is, the oscillating components (revolutionary components)—to the planetary gear 3. Multiple rolling elements 51 are disposed between the outer peripheral surface of the eccentric portion 72 of each crankshaft 7A, 7B, and 7C and the inner peripheral surface of each opening 33 of the planetary gear 3. 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 peripheral surface of each opening 33 of the planetary gear 3 functions as the outer ring of the eccentric bearing 5.

[0083] With the planetary gear 3 assembled with the eccentric bearing 5 and multiple crankshafts 7A, 7B, and 7C, when each crankshaft 7A, 7B, and 7C rotates (self-rotates), each eccentric part 72 rotates (eccentrically moves) around the axis Ax2. The planetary gear 3 is positioned in a direction parallel to the rotation axis Ax1 (axial direction) corresponding to each eccentric part 72. Therefore, the eccentric motion of each eccentric part 72 is transmitted to the planetary gear 3 via the eccentric bearing 5, and the planetary gear 3 oscillates around the rotation axis Ax1. In other words, the eccentric motion of the eccentric parts 72 in crankshafts 7A, 7B, and 7C is transmitted to the planetary gear 3. The eccentric bearing 5 serves to mitigate friction and other actions caused by the relative rotation based on the speed difference between the eccentric motion of the eccentric parts 72 of each crankshaft 7A, 7B, and 7C (that is, the self-rotation of each crankshaft 7A, 7B, and 7C) and the revolution of the planetary gear 3, and also serves to transmit power.

[0084] In the gear assembly 1 described above, a rotational force is applied to the input shaft 500 as input, causing the input shaft 500 to rotate around the rotation axis Ax1. This causes the planetary gear 3 to oscillate (revolve) around the rotation axis Ax1. At this time, the planetary gear 3 oscillates in a state where it is internally tangent to the internal gear 2 and a portion of its external teeth 31 meshes with a portion of the internal teeth 21. Therefore, as the input shaft 500 rotates, the meshing position of the internal teeth 21 and external teeth 31 moves along the circumference of the internal gear 2. This generates a relative rotation between the two gears (internal gear 2 and planetary gear 3) corresponding to the difference in the number of teeth between the planetary gear 3 and the internal gear 2. Furthermore, the rotational component (rotational component) of the planetary gear 3, excluding the oscillation component (revolutionary component), is transmitted to a pair of supports 18 and 19 via multiple crankshafts 7A, 7B, and 7C. As a result, a rotational output that is reduced in speed at a relatively high reduction ratio is obtained from a pair of supports 18 and 19, corresponding to the difference in the number of teeth of the two gears.

[0085] However, as described above, in the gear device 1 of this basic structure, the difference in the number of teeth between the internal gear 2 and the planetary gear 3 defines the reduction ratio of the output rotation relative to the input rotation in the gear device 1. That is, when the number of teeth of the internal gear 2 is set to "V1" and the number of teeth of the planetary gear 3 is set to "V2", the reduction ratio R1 is expressed by the following formula 1.

[0086] R1=V2 / (V1-V2) (Formula 1)

[0087] In general, the smaller the difference in the number of teeth (V1-V2) between the internal gear 2 and the planetary gear 3, the larger the reduction ratio R1. 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". Therefore, according to Equation 1 above, the reduction ratio R1 is "35". In this case, viewed from the input side of the rotating shaft Ax1, when each crankshaft 7A, 7B, 7C is about the axis Ax2 of the shaft center 71 (refer to...) Figure 5 and Figure 6 When the axis Ax1 is rotated clockwise for one revolution (360 degrees), the pair of brackets 18 and 19 rotate counterclockwise around the axis Ax1 by a difference of "2" teeth (that is, about 10.3 degrees).

[0088] According to the gear assembly 1 of this basic structure, such a high reduction ratio R1 can be achieved through the combination of the internal gear 2 and the planetary gear 3. Furthermore, between the input gear 501 and the multiple crankshaft gears 502A, 502B, and 502C, an appropriate reduction ratio can also be achieved based on the number of teeth of the input gear 501 and the crankshaft gears 502A, 502B, and 502C. As a result, a high reduction ratio can be achieved as a whole as the gear assembly 1.

[0089] Furthermore, the gear assembly 1 only needs to include at least an internal gear 2, a planetary gear 3, crankshafts 7A, 7B, and 7C, and a pair of supports 18 and 19, for example, such as Figure 4 As shown, it may also include a spacer 11. The spacer 11 is disposed between a pair of planetary gears 3 (first planetary gear 301 and second planetary gear 302) in a direction (axial direction) parallel to the rotation axis Ax1.

[0090] (Implementation Method 1)

[0091] like Figures 7-9 As shown, the internal meshing planetary gear device 1A (hereinafter also simply referred to as "gear device 1A") of this embodiment differs from the gear device 1 of the basic structure mainly in the structure of the eccentric shaft bearings 41 and 42. Hereinafter, the same reference numerals will be used for structures that are the same as those in the basic structure, and descriptions will be omitted as appropriate.

[0092] In this embodiment, each pair of eccentric shaft bearings 41 and 42 supporting each crankshaft 7A, 7B, and 7C is composed of "sliding bearings". That is, the two ends of each crankshaft 7A, 7B, and 7C are held in place by a pair of supports 18 and 19, separated by the eccentric shaft bearings 41 and 42 composed of "sliding bearings".

[0093] The "sliding bearing" mentioned in this invention refers to a bearing device that supports loads through a combination of a shaft and a bearing bore, separated by a thin layer of lubricant (oil film, etc.). In other words, the bearings 41 and 42 for each eccentric shaft are composed of "sliding bearings," which do not contain rolling elements such as balls, cylindrical rollers, or tapered rollers, but only have bearing bores for the shafts (here, crankshafts 7A, 7B, and 7C) to be inserted as structural elements.

[0094] Specifically, such as Figure 7 As shown, a pair of eccentric shaft bearings 41 and 42 supporting the two ends of crankshafts 7A, 7B, and 7C respectively have bearing holes 40 formed in a pair of supports 18 and 19. The bearing holes 40 are through holes that pass through supports 18 and 19 along the axial direction (parallel to the rotation axis Ax1), and are circular (perfectly round) when viewed from the axial side. The bearing holes 40 of the eccentric shaft bearing 41 formed in the input-side support 18 and the bearing holes 40 of the eccentric shaft bearing 42 formed in the output-side support 19 are concentric and have the same shape when viewed from the axial side.

[0095] Here, the diameter (inner diameter) of the bearing bore 40 is approximately the same as the diameter (outer diameter) of the shaft center 71 of crankshafts 7A, 7B, and 7C. In this embodiment, as an example, the diameter of the bearing bore 40... The diameter is 15mm. Therefore, with the shaft center 71 at both ends of each crankshaft 7A, 7B, 7C inserted into the bearing holes 40 of a pair of eccentric shaft bearings 41, 42, both ends of each crankshaft 7A, 7B, 7C are rotatably supported by a pair of eccentric shaft bearings 41, 42.

[0096] exist Figure 7 Although only crankshaft 7A is shown in the diagram, each of crankshafts 7B and 7C is similarly provided with a pair of eccentric shaft bearings 41 and 42 supporting its two ends. That is, the gear device 1A of this embodiment is the same as the basic structure, and is a type of eccentric oscillating internal meshing planetary gear device called a distribution type. Therefore, there are multiple (3) crankshafts 7A, 7B, and 7C, which are arranged at positions offset from the rotation axis Ax1, which is the axis of the internal gear 2, and are synchronously driven by the input gear 501. Therefore, multiple pairs (3 pairs in this case) of eccentric shaft bearings 41 and 42 are provided to support multiple crankshafts 7A, 7B, and 7C respectively.

[0097] As described above, the gear device 1A of this embodiment includes: an internal gear 2 having internal teeth 21; a planetary gear 3 having external teeth 31 that partially mesh with the internal teeth 21; crankshafts 7A, 7B, and 7C; and eccentric shaft bearings 41 and 42. The planetary gear 3 oscillates by rotating the crankshafts 7A, 7B, and 7C around their axes. The eccentric shaft bearings 41 and 42 support the crankshafts 7A, 7B, and 7C. The gear device 1A is an internal meshing planetary gear device in which the planetary gear 3 oscillates by the crankshafts 7A, 7B, and 7C, thereby causing the planetary gear 3 to rotate relative to the internal gear 2 around the rotation axis Ax1. Here, the eccentric shaft bearings 41 and 42 are constructed of sliding bearings.

[0098] This structure offers the following advantages: when viewing the gear assembly 1A from the axial direction (parallel to the rotation axis Ax1), the area occupied by the eccentric shaft bearings 41 and 42 is easily minimized. Therefore, the radial dimension of the gear assembly 1A can be easily reduced, enabling miniaturization of the gear assembly 1A. Furthermore, if the radial dimension of the gear assembly 1A is constant, it is easier to enlarge the pitch circle diameters of the bearing components 6 (first main bearing 601 and second main bearing 602) and / or crankshafts 7A, 7B, and 7C.

[0099] In summary, bearing assemblies capable of rotatably supporting crankshaft components 7A, 7B, and 7C can be broadly classified into "rolling bearings" and "sliding bearings." Rolling bearings have rolling elements such as balls, cylindrical rollers, or tapered rollers, and rotatably support the shaft component by moving the rolling elements between the inner and outer rings (i.e., rolling). On the other hand, sliding bearings do not have rolling elements and rotatably support the shaft component by sliding the shaft component inserted into the bearing bore relative to the inner circumferential surface of the bearing bore.

[0100] In the gear assembly 1 of the basic structure, the eccentric shaft bearings 41 and 42 supporting crankshafts 7A, 7B, and 7C are all composed of "rolling bearings" such as cylindrical roller bearings or tapered roller bearings. Therefore, the eccentric shaft bearings 41 and 42 supporting each crankshaft 7A, 7B, and 7C have multiple rolling elements around each crankshaft 7A, 7B, and 7C. Consequently, when the gear assembly 1 of the basic structure is viewed from the axial direction (parallel to the rotation axis Ax1), the area occupied by the eccentric shaft bearings 41 and 42 becomes larger, hindering the miniaturization of the gear assembly 1, etc.

[0101] In this embodiment, the eccentric shaft bearings 41 and 42 supporting crankshafts 7A, 7B, and 7C are all constructed as "sliding bearings". Therefore, the eccentric shaft bearings 41 and 42 supporting each crankshaft 7A, 7B, and 7C do not have multiple rolling elements around each crankshaft 7A, 7B, and 7C, thus reducing the area occupied by the eccentric shaft bearings 41 and 42 when the gear device 1A is viewed from the axial direction.

[0102] Therefore, in the gear device 1A of this embodiment, the space created by reducing the area occupied by the eccentric shaft bearings 41, 42 can be used for, for example, to reduce the radial dimension of the gear device 1A and thus to miniaturize the gear device 1A, or to increase the pitch circle diameter of the bearing components 6 (first main bearing 601 and second main bearing 602) and / or crankshafts 7A, 7B, 7C.

[0103] As an example, regarding the gear device 1A of this embodiment, although the radial dimension is the same as that of the gear device 1 of the basic structure, the size of the bearing member 6 (first main bearing 601 and second main bearing 602) is increased by utilizing the space created by reducing the area occupied by the eccentric shaft bearings 41 and 42. Therefore, regarding the gear device 1A of this embodiment, compared with the gear device 1 of the basic structure, the load capacity of the bearing member 6 can be increased, and the rigidity of the bearing member 6 can be improved.

[0104] That is, such as Figure 7 As illustrated, with Figure 4 Compared to the basic structure shown, the size of the first bearing member 601 and the second bearing member 602, which are composed of ball bearings, is increased to improve their load capacity. Specifically, regarding the outer diameter of the outer ring 62, although this embodiment is the same as the basic structure, the diameter of the rolling element 63 is increased by utilizing the space created by using the eccentric shaft bearings 41 and 42 as sliding bearings, thereby increasing the load capacity.

[0105] However, in this embodiment, a pair of main bearings (first main bearing 601 and second main bearing 602) are included, which support the brackets 18 and 19, which rotate relative to the internal gear 2 as the planetary gear 3 rotates relative to the internal gear 2, in a manner that allows them to rotate relative to the internal gear 2. Furthermore, eccentric shaft bearings 41 and 42 are located between the outer ends of the pair of main bearings (first main bearing 601 and second main bearing 602) in the direction along the rotation axis Ax1.

[0106] In short, such as Figure 7As shown, in the axial direction (along the rotation axis Ax1), eccentric shaft bearings 41 and 42 are arranged such that they are housed between the outer ends (opposite to the planetary gear 3) of a pair of main bearings (first main bearing 601 and second main bearing 602). More specifically, the bearing bore 40 of the eccentric shaft bearing 41 is formed in the inner ring 61 (input-side bracket 18) of the first main bearing 601, thus the eccentric shaft bearing 41 is configured to be housed within the width dimension of the first main bearing 601 in the axial direction. Similarly, the bearing bore 40 of the eccentric shaft bearing 42 is formed in the inner ring 61 (output-side bracket 19) of the second main bearing 602, thus the eccentric shaft bearing 42 is configured to be housed within the width dimension of the second main bearing 602 in the axial direction.

[0107] Thus, the eccentric shaft bearings 41 and 42 are located between the outer ends of a pair of main bearings (first main bearing 601 and second main bearing 602) in the direction along the rotation axis Ax1, thereby suppressing the axial size of the gear assembly 1A. Furthermore, the eccentric shaft bearings 41 and 42 can either overflow axially from the inner ends of the pair of main bearings (towards the planetary gear 3 side) or be located between the inner ends of the pair of main bearings. Further, the eccentric shaft bearings 41 and 42 can either overflow axially from the outer ends of the pair of main bearings (towards the opposite side of the planetary gear 3) or be located further outward than the outer ends of the pair of main bearings.

[0108] In addition, such as Figure 8 and Figure 9 As shown, the axial positioning of crankshafts 7A, 7B, and 7C can be achieved by the inner ring 61 (a pair of supports 18 and 19) of bearing component 6 (first main bearing 601 and second main bearing 602). Figure 8 An enlarged view of the periphery of crankshaft 7A is shown. Figure 9 Show Figure 8 The A1-A1 line view and the B1-B1 line view.

[0109] Specifically, such as Figure 8 and Figure 9 As shown, the inner ring 61 (a pair of supports 18, 19) of the bearing component 6 (first main bearing 601 and second main bearing 602) forms an extension 400 extending toward the center side (planetary gear 3 side) of the bearing hole 40, which is inside the bearing hole 40.

[0110] Here, Figure 9 The “B1-B1 line towards the view” Figure 1 "This shows the state where the contact area between the eccentric portion 72 and the protruding portion 400 is minimized," with the B1-B1 line pointing towards the view. Figure 2 "This shows the state where the contact area between the eccentric portion 72 and the protruding portion 400 is at its maximum. Furthermore, Figure 9The “B1-B1 line towards the view” Figure 3 "This is the state where the contact area between the eccentric part 72 and the protruding part 400 is at its minimum, and the eccentric bearing 5 is shown with an imaginary line (double-dotted line). In" Figure 9 In the diagram, the diagonal lines indicate the contact area between the eccentric portion 72 or the eccentric bearing 5 and the protrusion 400.

[0111] In this way, crankshafts 7A, 7B, and 7C restrict axial outward movement (to the side opposite to planetary gear 3) by having their eccentric portions 72 contact the portion of the inner ring 61 that is closer to the bearing bore 40 (the protrusion 400). Similarly, the eccentric bearing 5 (especially its retainer) also restricts axial outward movement (to the side opposite to planetary gear 3) by having it contact the portion of the inner ring 61 that is closer to the bearing bore 40 (the protrusion 400). Therefore, the positioning of crankshafts 7A, 7B, and 7C does not require the use of retaining rings or other components, thus simplifying the structure.

[0112] Here, the portion of the inner ring 61 extending outward from the protrusion 400 (opposite to the rotation axis Ax1) is axially positioned between the eccentric portion 72 and the eccentric bearing 5 (especially its retainer), with a gap of approximately 1 mm as an example. Thus, a passage for lubricant (such as lubricant) is formed between the portion of the inner ring 61 extending outward from the protrusion 400 and the eccentric portion 72 and the eccentric bearing 5.

[0113] As a result, lubricant can be easily supplied to the eccentric shaft bearings 41 and 42. That is, in this embodiment, the eccentric shaft bearings 41 and 42 have bearing holes 40 for the crankshafts 7A, 7B, and 7C to be inserted, and lubricant is sandwiched between the outer circumferential surface of the crankshafts 7A, 7B, and 7C and the inner circumferential surface of the bearing holes 40. This reduces friction in the eccentric shaft bearings 41 and 42, which are constructed of sliding bearings, and also reduces losses at the eccentric shaft bearings 41 and 42.

[0114] Furthermore, in this embodiment, the gear device 1A is a type of eccentric oscillating internal meshing planetary gear device, referred to as a distribution type. That is, in the gear device 1A, multiple crankshafts 7A, 7B, and 7C are provided. The multiple crankshafts 7A, 7B, and 7C are arranged at positions offset from the rotation axis Ax1, which is the axis of the internal gear 2, and are synchronously driven by the input gear 501. Here, multiple pairs of eccentric shaft bearings 41 and 42 are provided to support the multiple crankshafts 7A, 7B, and 7C respectively.

[0115] In this way, in a structure with multiple pairs of eccentric shaft bearings 41 and 42, a relatively large space can be created by using the eccentric shaft bearings 41 and 42 as sliding bearings.

[0116] Furthermore, in the gear device 1A of this embodiment, the internal gear 2 has an annular gear body 22 and a plurality of pins 23 constituting the internal teeth 21. The plurality of pins 23 are held in a rotatable state in a plurality of inner circumferential grooves 223 formed on the inner circumferential surface 221 of the gear body 22.

[0117] Therefore, by utilizing the space created by reducing the area occupied by the bearings 41 and 42 of the eccentric shaft, it is easy to configure the multiple pins 23 that constitute the internal teeth 21.

[0118] However, as Figure 10 As shown, the gear device 1A of this embodiment, together with the first component 201 and the second component 202, constitutes a robot joint device 200 (i.e., a robot arm structure). In other words, the robot joint device 200 equipped with the robot arm structure of this embodiment includes the gear device 1A, the first component 201, and the second component 202. The first component 201 is fixed to the internal gear 2. The second component 202 rotates relative to the first component 201 as the planetary gear 3 rotates relative to the internal gear 2. Figure 10 This is a schematic cross-sectional view of the robot's articulation device 200. Additionally, in Figure 10 The diagram schematically shows the first component 201, the second component 202, and the drive source 101.

[0119] The robot joint device 200 configured in this way functions as a joint device by rotating the first member 201 and the second member 202 relative to each other about the rotation axis Ax1. Here, the first member 201 and the second member 202 rotate relative to each other by driving the input shaft 500 of the gear device 1A by the drive source 101. At this time, the rotation generated by the drive source 101 (input rotation) is reduced in the gear device 1A with a relatively high reduction ratio, and the first member 201 or the second member 202 is driven with a relatively high torque. That is to say, the first member 201 and the second member 202 connected by the gear device 1A can perform flexion and extension movements about the rotation axis Ax1.

[0120] The robot joint device 200 (i.e., the robot arm structure) is used, for example, in robots such as horizontal articulated robots (jointed robots). Furthermore, the robot joint device 200 is not limited to horizontal articulated robots; for example, it can also be used in industrial robots other than horizontal articulated robots, or robots other than industrial robots. Additionally, the gear device 1A of this embodiment is not limited to the robot joint device 200; for example, as a wheel device such as a hub motor, it can also be used in vehicles such as Automated Guided Vehicles (AGVs).

[0121] <Variation Example>

[0122] Embodiment 1 is merely one of the various embodiments of the present invention. Various modifications can be made to Embodiment 1 based on design, etc., as long as the objective of the present invention is achieved. Furthermore, the accompanying drawings referenced in this invention are schematic diagrams, and the ratios of the size and thickness of each structural element in the drawings are not necessarily limited to reflecting actual dimensional ratios. Below, variations of Embodiment 1 are listed. The variations described below can be appropriately combined and applied.

[0123] Bearing components 6 (first main bearing 601 and second main bearing 602) are not limited to angular ball bearings, for example, such as Figure 11 As shown, it can also be a tapered roller bearing that uses tapered rollers as rolling elements 63. In this structure, as... Figure 11 As shown, the load line LL1 of the bearing component 6 (first main bearing 601 and second main bearing 602) is located at a position passing through the eccentric shaft bearings 41 and 42, which are composed of sliding bearings.

[0124] Alternatively, the bearing components 6 (first main bearing 601 and second main bearing 602) may also be, for example, as shown in the example... Figure 12 As shown, this is a cylindrical roller bearing that uses cylindrical rollers as rolling elements 63. In this structure, as... Figure 12 As shown, the contact angle of the bearing components 6 (first main bearing 601 and second main bearing 602) is 45 degrees, and the inner ring 61 has flanges on both sides of the rolling element 63 in the axial direction to restrict movement. In this case, the load line LL2 of the bearing components 6 (first main bearing 601 and second main bearing 602) does not pass through the eccentric shaft bearings 41 and 42, which are composed of sliding bearings.

[0125] The number of crankshafts 7A, 7B, and 7C is not limited to "3" and can also be 2 or 4 or more. Furthermore, if there is only one crankshaft, it is not a distribution type, but an eccentric oscillating type internal meshing planetary gear device that achieves alignment between the rotation axis Ax1 and the crankshaft axis Ax2. In this case, by driving the crankshaft, the planetary gear 3 oscillates, and a pair of supports 18 and 19 can rotate relative to the gear body 22 about the rotation axis Ax1.

[0126] Furthermore, in Embodiment 1, a gear device 1A with two planetary gears 3 is illustrated; however, gear device 1A may also include three or more planetary gears 3. For example, when gear device 1A includes 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, gear device 1A may include only one planetary gear 3. Or, when gear device 1A includes three planetary gears 3, two of these three planetary gears 3 may be in the same phase, and the remaining planetary gear 3 may be arranged with a phase difference of 180 degrees around the rotation axis Ax1.

[0127] In addition, bearing component 6 can be a crossed roller bearing, a deep groove ball bearing, or a four-point contact ball bearing, etc.

[0128] 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 pins 23 (the number of teeth of the internal gear 21), and the number of teeth of the external gear 31 described in Embodiment 1 are merely examples and can be appropriately modified.

[0129] Furthermore, the materials of the various structural elements of the gear device 1A are not limited to metal; for example, they can be resins such as engineering plastics.

[0130] Furthermore, the gear device 1A is only required to output the relative rotation between the inner ring 61 and the outer ring 62 of the bearing member 6, and is not limited to outputting the rotational force of the inner ring 61 (input-side bracket 18 and output-side bracket 19). For example, the rotational force of the outer ring 62 (housing 10) that rotates relative to the inner ring 61 can also be output.

[0131] In addition, lubricants are not limited to liquid substances such as lubricating oil (oil), but can also be gel-like substances such as lubricating grease.

[0132] (Implementation Method Two)

[0133] like Figure 13 and Figure 14 As shown, the internal meshing planetary gear device 1B of this embodiment (hereinafter also simply referred to as "gear device 1B") differs from the gear device 1A of Embodiment 1 in that it employs a preload for applying preload to the bearings 41 and 42 for the eccentric shaft. Hereinafter, the same reference numerals will be used to refer to the same structure as in Embodiment 1, and descriptions will be omitted as appropriate.

[0134] That is, in this embodiment, the eccentric shaft bearings 41 and 42 have bearing holes 40 for the crankshafts 7A, 7B, and 7C to be inserted, and preload is applied in such a way as to fill the gap between the outer peripheral surface of the crankshafts 7A, 7B, and 7C and the inner peripheral surface of the bearing hole 40.

[0135] Specifically, the outer diameter of the core portion 71 of crankshafts 7A, 7B, and 7C is slightly larger than the inner diameter of the bearing bore 40. Furthermore, in crankshafts 7A, 7B, and 7C, the core portion 71 is a hollow cylindrical structure, and a portion in the circumferential direction has a slit 43 along the axial direction (parallel to the rotation axis Ax1). In other words, the core portion 71 is a front-end split structure with its axial front end divided into multiple segments. In this embodiment, as an example, four slits 43 are arranged at 90-degree intervals in the circumferential direction.

[0136] Therefore, with the shaft center 71 of crankshafts 7A, 7B, and 7C inserted into the bearing hole 40, a spring force generated by the elastic deformation of the shaft center 71 is applied as a preload. As a result, while the eccentric shaft bearings 41 and 42 are realized by sliding bearings, low backlash can also be achieved as a gear device 1B.

[0137] The specific method for applying preload is not limited to the structure described above; various methods can be applied.

[0138] The structure of Embodiment 2 can be appropriately combined with the basic structure or the various structures (including variations) described in Embodiment 1.

[0139] (Summarize)

[0140] As described above, the first-form internal meshing planetary gear assembly (1, 1A, 1B) includes: an internal gear (2) having internal teeth (21); a planetary gear (3) having external teeth (31) that partially mesh with the internal teeth (21); a crankshaft (7A, 7B, 7C); and eccentric shaft bearings (41, 42). The crankshaft (7A, 7B, 7C) causes the planetary gear (3) to oscillate by rotating about its axis. The eccentric shaft bearings (41, 42) support the crankshaft (7A, 7B, 7C). The internal meshing planetary gear assembly (1, 1A, 1B) causes the planetary gear (3) to oscillate, thereby causing the planetary gear (3) to rotate relative to the internal gear (2) about its axis of rotation (Ax1). The eccentric shaft bearings (41, 42) are constructed of sliding bearings.

[0141] According to this configuration, the following advantages are available: When viewing the internal meshing planetary gear unit (1, 1A, 1B) from the axial direction (the direction parallel to the rotation axis (Ax1), it is easy to minimize the area occupied by the eccentric shaft bearings (41, 42). Therefore, it is easy to minimize the radial dimension of the internal meshing planetary gear unit (1, 1A, 1B) and achieve miniaturization of the internal meshing planetary gear unit (1, 1A, 1B). Furthermore, if the radial dimension of the internal meshing planetary gear unit (1, 1A, 1B) is constant, it is easy to increase the pitch circle diameter of the bearing components 6 (first main bearing 601 and second main bearing 602) and / or the crankshaft (7A, 7B, 7C).

[0142] In the second form of the internal meshing planetary gear assembly (1, 1A, 1B), based on the first form, multiple crankshafts (7A, 7B, 7C) are provided. These multiple crankshafts (7A, 7B, 7C) are located offset from the rotational shaft (Ax1) which serves as the axis of the internal gear (2), and are synchronously driven by the input gear (501). Multiple pairs of eccentric shaft bearings (41, 42) are provided to support the multiple crankshafts (7A, 7B, 7C) respectively.

[0143] Based on this configuration, a relatively large space can be created by using multiple pairs of eccentric shaft bearings (41, 42) as sliding bearings.

[0144] In the third form of the internal meshing planetary gear device (1, 1A, 1B), based on the first or second form, the internal gear (2) has an annular gear body (22) and multiple pins (23) constituting the internal teeth (21). The multiple pins (23) are held in a rotatable state in multiple inner circumferential grooves (223) formed on the inner circumferential surface (221) of the gear body (22).

[0145] According to this configuration, the space created by reducing the area occupied by the bearings (41, 42) of the eccentric shaft can be easily configured to form multiple pins (23) constituting the internal teeth (21).

[0146] In the fourth form of the internal meshing planetary gear assembly (1, 1A, 1B), based on any of the first to third forms, the eccentric shaft bearings (41, 42) have bearing holes (40) for the crankshafts (7A, 7B, 7C). Preload is applied by filling the gap between the outer circumferential surface of the crankshafts (7A, 7B, 7C) and the inner circumferential surface of the bearing holes (40).

[0147] Based on this morphology, low tooth backlash can be achieved.

[0148] In the fifth form of the internal meshing planetary gear assembly (1, 1A, 1B), based on any of the first to fourth forms, the eccentric shaft bearings (41, 42) have bearing holes (40) for inserting crankshafts (7A, 7B, 7C). Lubricant is sandwiched between the outer circumferential surface of the crankshafts (7A, 7B, 7C) and the inner circumferential surface of the bearing holes (40).

[0149] According to this configuration, the friction of the eccentric shaft bearings (41, 42) which are made of sliding bearings can be reduced, and the loss at the eccentric shaft bearings (41, 42) can be reduced.

[0150] In the sixth embodiment of the internal meshing planetary gear assembly (1, 1A, 1B), based on any of the first to fifth embodiments, a pair of main bearings (first main bearing 601 and second main bearing 602) are also included. The pair of main bearings (first main bearing 601 and second main bearing 602) support a bracket (18, 19) that rotates relative to the internal gear (2) in a manner that allows it to rotate relative to the internal gear (2). Eccentric shaft bearings (41, 42) are located between the outer ends of the pair of main bearings (first main bearing 601 and second main bearing 602) in the direction along the rotation axis (Ax1).

[0151] According to this configuration, the size of the internal meshing planetary gear unit (1, 1A, 1B) in the axial direction (the direction parallel to the rotation axis (Ax1)) can be suppressed.

[0152] The seventh type of robot joint device (200) includes: an internal meshing planetary gear device (1, 1A, 1B) of any of the first to sixth types; a first component (201) fixed to the internal gear (2); and a second component (202) that rotates relative to the first component (201) as the planetary gear (3) rotates relative to the internal gear (2).

[0153] According to this configuration, it has the following advantages: when the internal meshing planetary gear device (1, 1A, 1B) is viewed from the axial direction (the direction parallel to the rotation axis (Ax1)), the robot joint device (200) can be made to minimize the area occupied by the eccentric shaft bearings (41, 42).

[0154] Regarding the structures of the second to fifth forms, these are not essential for the internal meshing planetary gear devices (1, 1A, 1B) and can be omitted appropriately.

Claims

1. A robotic arm structure, comprising a joint device for the robot, wherein, The robot joint device includes: An internal meshing planetary gear mechanism includes: an internal gear having internal teeth; and planetary gears having teeth that mesh with the internal gears. The crankshaft is described as having a partial meshing with the internal gear; the planetary gear is oscillating by rotating about its axis; and an eccentric shaft bearing supports the crankshaft, wherein the planetary gear is oscillating, thereby causing the planetary gear to rotate relative to the internal gear about its axis of rotation, and the eccentric shaft bearing is composed of a sliding bearing. The first component is fixed to the internal gear; and The second component rotates relative to the first component as the planetary gear rotates relative to the internal gear. The eccentric shaft bearing has a bearing bore for insertion into the crankshaft. Preload is applied in a manner that fills the gap between the outer circumferential surface of the crankshaft and the inner circumferential surface of the bearing bore; The outer diameter of the crankshaft's core portion is slightly larger than the inner diameter of the bearing bore. The core portion is a hollow cylindrical structure and has a slit along the axial direction in a circumferential part.

2. An internal meshing planetary gear device, wherein, include: Internal gear, having internal teeth; A planetary gear having external teeth that partially mesh with the internal teeth; The crankshaft, by rotating about its axis, causes the planetary gears to oscillate; and An eccentric shaft bearing supports the crankshaft. By oscillating the planetary gear, the planetary gear rotates relative to the internal gear about its axis of rotation. The bearing for the eccentric shaft is composed of a sliding bearing; The eccentric shaft bearing has a bearing bore for insertion into the crankshaft. Preload is applied in a manner that fills the gap between the outer circumferential surface of the crankshaft and the inner circumferential surface of the bearing bore; The outer diameter of the crankshaft's core portion is slightly larger than the inner diameter of the bearing bore. The core portion is a hollow cylindrical structure and has a slit along the axial direction in a circumferential part.

3. The internal meshing planetary gear device according to claim 2, wherein, The crankshaft is provided in multiple ways. The plurality of crankshafts are positioned offset from the rotational axis, which serves as the axis of the internal gear, and are synchronously driven by the input gear. The eccentric shaft bearings are provided in multiple pairs to support the plurality of crankshafts respectively.

4. The internal meshing planetary gear device according to claim 2 or 3, wherein, The internal gear has: an annular gear body; and a plurality of pins, which are held in a rotatable state in a plurality of inner circumferential grooves formed on the inner circumferential surface of the gear body, and constitute the internal teeth.

5. The internal meshing planetary gear device according to claim 2 or 3, wherein, The eccentric shaft bearing has a bearing bore for insertion into the crankshaft. A lubricant is sandwiched between the outer circumferential surface of the crankshaft and the inner circumferential surface of the bearing bore.

6. The internal meshing planetary gear device according to claim 2 or 3, wherein, The internal meshing planetary gear assembly further includes a pair of main bearings that support a bracket that rotates relative to the internal gear as the planetary gears rotate relative to the internal gear. The eccentric shaft bearing is located between the outer ends of the pair of main bearings in the direction along the rotation axis.

7. A joint device for a robot, wherein, include: The internal meshing planetary gear device according to any one of claims 2 to 6; The first component is fixed to the internal gear; and The second component rotates relative to the first component as the planetary gear rotates relative to the internal gear.

Images