Robot mechanical arm structure and internal meshing planetary gear device

Abstract

The invention provides a robot mechanical arm structure comprising a joint device for a robot and an internal meshing planetary gear device, and relates to the technical field of robots. The internally engaged planetary gear device includes: an internally toothed gear having internal teeth; a planetary gear having outer teeth locally meshing with the inner teeth; a crankshaft; and a bearing for the eccentric shaft. The crankshaft swings the planetary gear by rotating about the axis. The eccentric shaft supports the crankshaft through a bearing. The internally engaged planetary gear device causes a planetary gear to rotate relative to an internally toothed gear about a rotation axis by swinging the planetary gear. The bearing for the eccentric shaft is composed of a sliding bearing. As a result, the range occupied by the bearing for the eccentric shaft can be easily suppressed to be small when viewed from one side in the axial direction.

Description

Technical Field

[0001] The present invention relates to the field of robot technology, and in particular to a robot arm structure including a robot joint device and an internal meshing planetary gear device, wherein the robot joint device includes the internal meshing planetary gear device. Background Art

[0002] In the patent document Japanese Patent Publication No. 2016-75354, an eccentric oscillating type internal meshing planetary gear device called a distributed type is known (for example, refer to Patent Document 1). In the internal meshing planetary gear device of the related art, a plurality of (for example, three) crankshafts are arranged at positions offset from the axis of the internal gear, and the crankshaft gears are synchronously driven to make the planetary gears (external gears) mesh with the internal gear while oscillating.

[0003] The planetary gear includes a first planetary gear and a second planetary gear. A pair of brackets are arranged on both axial sides of the first planetary gear and the second planetary gear. Each crankshaft is supported by a pair of brackets through a pair of tapered roller bearings. When the input gear rotates, the three crankshaft gears that are simultaneously meshed with the input gear rotate in the same direction at the same rotation speed. The crankshafts are spline-connected to each crankshaft gear, so the three crankshafts rotate in the same direction at the same rotation speed in a state where they are reduced to the gear ratio of the input gear and the crankshaft gear. As a result, the three first eccentric portions formed at the same axial position of the three crankshafts rotate synchronously to cause the first planetary gear to swing, and the three second eccentric portions formed at the same axial position of the three crankshafts rotate synchronously to cause the second planetary gear to swing.

[0004] The first planetary gear and the second planetary gear are respectively meshed with the internal gear. The internal gear has: a gear body; and a pin (external pin member), which is rotatably assembled into the gear body and constitutes the internal teeth of the internal gear. Here, the number of teeth of the internal gear (the number of pins) is slightly greater than the number of teeth of each planetary gear. Therefore, every time each planetary gear swings, the first planetary gear and the second planetary gear produce a circumferential phase deviation (rotation) in the amount of the difference in the number of teeth relative to the internal gear, and the rotation is transmitted to a pair of brackets as a revolution around the rotation axis of the internal gear of each crankshaft. Thereby, a pair of brackets can be relatively rotated relative to the gear body (and the integrated housing) around the rotation axis.

[0005] In the structure of the above patent document, the eccentric shaft bearing (tapered roller bearing) supporting each crankshaft has a plurality of 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 bearing becomes larger, which hinders the miniaturization of the internal meshing planetary gear device. Summary of the invention

[0006] The object of the present invention is to provide a robot arm structure including a robot joint device and an internal meshing planetary gear device, which can easily suppress the range occupied by the eccentric shaft bearing when viewed from one axial direction, and the robot joint device includes the internal meshing planetary gear device.

[0007] A robot arm structure of one form of the invention includes a joint device for a robot, wherein the joint device for the robot includes: an internally meshing planetary gear device, including: an internally toothed gear having internal teeth; a planetary gear having external teeth partially meshing with the internal teeth; a crankshaft, which causes the planetary gear to swing by rotating around an axis; and an eccentric shaft bearing, which supports the crankshaft, wherein the planetary gear is caused to rotate relative to the internally toothed gear around a rotating axis by swinging the planetary gear, and the eccentric shaft bearing is composed of a sliding bearing; a first member, which is fixed to the internally toothed gear; and a second member, which rotates relative to the first member as the planetary gear rotates relative to the internally toothed gear.

[0008] An internally meshing planetary gear device according to one aspect of the present invention comprises: an internally meshing gear having internal teeth; a planetary gear having external teeth partially meshing with the internal teeth; a crankshaft; and an eccentric shaft bearing. The crankshaft causes the planetary gear to oscillate by rotating about the axis. The eccentric shaft bearing supports the crankshaft. The internally meshing planetary gear device causes the planetary gear to oscillate, thereby causing the planetary gear to rotate relative to the internally meshing gear about the rotation axis. The eccentric shaft bearing is composed of a sliding bearing.

[0009] A robot joint device according to one embodiment of the present invention includes: the internally meshing planetary gear device; a first member fixed to the internal gear; and a second member that rotates relative to the first member as the planetary gear rotates 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 can be provided, which can easily suppress the range occupied by the eccentric shaft bearing to be small when viewed from one axial direction. The robot joint device includes the internal meshing planetary gear device. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 This is a perspective view of the schematic structure of an actuator including an internal meshing planetary gear device of a basic structure;

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

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

[0014] Figure 4 is a schematic cross-sectional view of the internal meshing planetary gear device described above;

[0015] Figure 5 The internal meshing planetary gear device is shown in FIG. Figure 4 A1-A1 line sectional view;

[0016] Figure 6 The internal meshing planetary gear device is shown in FIG. Figure 4 B1-B1 line cross-sectional view;

[0017] Figure 7 is a schematic cross-sectional view of an internally meshing planetary gear device according to a first embodiment;

[0018] Figure 8 is a schematic cross-sectional view showing the crankshaft and the periphery of the internal meshing planetary gear device described above;

[0019] Fig. 9 The internal meshing planetary gear device is shown in FIG. Figure 8 A1-A1 line view and Figure 8 B1-B1 line view;

[0020] Fig.10 is a schematic diagram showing a robot joint device using the above-mentioned internal meshing planetary gear device;

[0021] Fig.11 is a schematic cross-sectional view of an internally meshing planetary gear device according to a modified example of the first embodiment;

[0022] Fig.12 is a schematic cross-sectional view of an internally meshing planetary gear device according to yet another modified example of the first embodiment;

[0023] Fig.13 is a schematic cross-sectional view of an internally meshing planetary gear device according to a modified example of the second embodiment;

[0024] Fig.14 This is a schematic cross-sectional view showing the periphery of a crankshaft of the internally meshing planetary gear device.

[0025] Description of Reference Numerals

[0026] 1, 1A, 1B internal meshing planetary gear device; 2 internal gear; 3 planetary gear; 7A, 7B, 7C crankshaft; 21 internal teeth; 22 gear body; 23 pin; 31 external teeth (first external teeth, second external teeth); 40 bearing hole; 200 robot joint device (i.e., robot arm structure); 201 first component; 202 second component; 221 inner peripheral surface; 223 inner peripheral groove; 501 input gear; Ax1 rotating axis. DETAILED DESCRIPTION

[0027] (Basic structure)

[0028] (1) Summary

[0029] For an overview of the internally meshing planetary gear device 1 of the basic structure, refer to Figure 1 to Figure 4 The drawings referred to in the present invention are schematic drawings, and the size and thickness ratios of the various structural elements in the drawings do not necessarily reflect the actual size ratios. For example, Figure 1 to Figure 4 The tooth shapes, sizes, and number of teeth of the inner teeth 21 and the outer teeth 31 are schematically shown for the purpose of explanation only, and the subject matter is not limited to the shapes shown in the drawings.

[0030] The internal meshing planetary gear device 1 (hereinafter, also referred to as "gear device 1") of this basic structure is a gear device including an internal gear 2 and a planetary gear 3. In the gear device 1, the planetary gear 3 is arranged on the inner side of the annular internal gear 2 and the planetary gear 3 is swung, so that the planetary gear 3 rotates relative to the internal gear 2. In addition, the internal meshing planetary gear device 1 also includes a bearing component 6, and the bearing component 6 has an outer ring 62 and an inner ring 61. The inner ring 61 is arranged on the inner side of the outer ring 62 and is supported so as to be relatively rotatable relative to the outer ring 62. In particular, the gear device 1 of this basic structure is an internal meshing planetary gear device of an eccentric swing type called a distribution type.

[0031] like Figure 1 to Figure 4 As shown, the gear device 1 of this basic structure includes a plurality of (three in the basic structure) 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 arranged on the axis (rotation axis Ax1) of the internal gear 2 and centered on the rotation axis Ax1, and an input gear 501 formed integrally with the input shaft 500. Crankshaft gears 502A, 502B, 502C are respectively connected to the plurality of crankshafts 7A, 7B, 7C by splines. These plurality of (three in the basic structure) crankshaft gears 502A, 502B, 502C are arranged in a manner meshing with the input gear 501. Therefore, when the input shaft 500 is driven, the gear device 1 drives the crankshafts 7A, 7B, 7C synchronously by 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. In particular, in this basic structure, the internal gear 2 has an annular gear body 22 and a plurality of pins 23. The plurality of pins 23 are held on the inner circumferential surface 221 of the gear body 22 in a state capable of self-rotation to form the internal teeth 21. The planetary gear 3 has external teeth 31 partially meshed with the internal teeth 21. That is, on the inner side of the internal gear 2, the planetary gear 3 is inscribed in the internal gear 2, and a part of the external teeth 31 is in meshed with a part of the internal teeth 21. In this state, when the plurality of crankshafts 7A, 7B, and 7C are driven, the planetary gear 3 swings, and the meshing position of 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 is generated 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 (rotates) with the relative rotation of the two gears. As a result, the planetary gear 3 can obtain a rotation output that is reduced in speed at a relatively high speed reduction ratio in accordance with the difference in the number of teeth between the two gears.

[0033] This gear device 1 is used in the following manner: the rotation of the planetary gear 3 corresponding to the self-rotation component is extracted as the rotation of a pair of brackets 18 and 19 that are relatively fixed by means of integration or embedding with the inner ring 61 of the bearing member 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 brackets 18 and 19 as the output side. Therefore, in the gear device 1 of this basic structure, in order to transmit the rotation of the planetary gear 3 corresponding to the self-rotation component to the pair of brackets 18 and 19, a plurality of crankshafts 7A, 7B, and 7C are supported by a pair of brackets 18 and 19. The pair of brackets 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 support each crankshaft 7A, 7B, and 7C in a rotatable manner.

[0034] Here, the plurality of crankshafts 7A, 7B, 7C are inserted into the plurality of openings 33 formed in the planetary gear 3, and rotate relative to the internal gear 2 as the planetary gear 3 rotates. In addition, each crankshaft 7A, 7B, 7C has an axial portion 71 and an eccentric portion 72 eccentric to the axial portion 71. A pair of brackets 18, 19 rotatably supports the axial portion 71 of each crankshaft 7A, 7B, 7C, and the eccentric portion 72 of each crankshaft 7A, 7B, 7C is inserted into the opening 33 of the planetary gear 3. When each crankshaft 7A, 7B, 7C rotates around its own axial portion 71, each eccentric portion 72 rotates eccentrically (eccentric motion) relative to its own axial portion 71. In association with this, the planetary gear 3 swings. As the planetary gear 3 swings, the planetary gear 3 partially meshes with the internal gear 2 and rotates relative to the internal gear 2. As a result, the planetary gear 3 rotates about its own central axis and revolves in the internal gear 2 in a circle around the rotation axis Ax1. As the planetary gear 3 rotates, the crankshafts 7A, 7B, 7C revolve around the rotation axis Ax1, and the brackets 18, 19 supporting the axial center 71 of the crankshafts 7A, 7B, 7C rotate as the crankshafts 7A, 7B, 7C revolve. In this way, the rotation (rotation component) of the planetary gear 3 in addition to the swing component (revolution component) of the planetary gear 3 is transmitted to the pair of brackets 18, 19 through the plurality of crankshafts 7A, 7B, 7C.

[0035] In addition, if Figure 1 As shown, the gear device 1 of this basic structure and the drive source 101 together constitute the actuator 100. In other words, the actuator 100 of this basic structure includes the gear device 1 and the drive source 101. The drive source 101 generates a driving force for swinging the planetary gear 3. Specifically, the drive source 101 rotates the input shaft 500 around the rotation axis Ax1, thereby swinging the planetary gear 3.

[0036] (2) Definition

[0037] The "ring-shaped" in the present invention refers to a shape that forms a circle (ring) with a space (region) surrounded inside at least when viewed from above, and is not limited to a circular shape (ring-shaped) that is a perfect circle when viewed from above, and may be, for example, an elliptical shape or a polygonal shape, etc. Furthermore, even a shape having a bottom such as a cup-shaped shape is included in the "ring-shaped" as long as its peripheral wall is ring-shaped.

[0038] The term "revolution" as used in the present invention refers to the rotation of an object around a rotation axis other than the central axis passing through the center (center of gravity) of the object. When an object revolves, the center of the object moves along a revolving orbit centered on the rotation axis. Therefore, for example, when an object revolves around an eccentric axis parallel to the central axis passing through the center (center of gravity) of the object, the object revolves around the eccentric axis as the rotation axis. As an example, the planetary gear 3 revolves around the rotation axis Ax1 in the internal gear 2 by swinging.

[0039] In addition, in the disclosure, there is a method of rotating the axis Ax1 on one side ( Figure 4 The left side of the rotation axis Ax1 is called the "output side", and the other side of the rotation axis Ax1 ( Figure 4 The right side of the input is called the "input side". Figure 4 In the example, rotation is imparted to the input shaft 500 from the "input side" of the rotation axis Ax1, and rotation of a pair of brackets 18 and 19 is taken out from the "output side" of the rotation axis Ax1. However, "input side" and "output side" are merely labels given for the purpose of explanation, and their purpose does not limit the positional relationship between input and output as viewed from the gear device 1.

[0040] The "rotation axis" in the present invention refers to a virtual axis (straight line) that is the center of rotation of a rotating body. That is, the rotation axis Ax1 is a virtual axis without a physical body. The input shaft 500 rotates around the rotation axis Ax1.

[0041] In the present invention, the "internal teeth" and "external teeth" refer to a collection (group) of multiple "teeth" rather than a single "tooth". That is, the internal teeth 21 of the internal gear 2 are composed of a collection of multiple teeth arranged on the inner peripheral 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 arranged on the outer peripheral surface of the planetary gear 3.

[0042] (3) Structure

[0043] For the detailed structure of the internal meshing planetary gear device 1 of the basic structure, refer to Figure 1 to Figure 6 Provide explanation.

[0044] Figure 1 1 is a perspective view showing a schematic structure of an actuator 100 including a gear device 1. Figure 1 , a driving source 101 is schematically shown. Figure 2 It is a schematic exploded perspective view of the gear device 1 as viewed from the input side of the rotation axis Ax1. Figure 3 It is a schematic exploded perspective view of the gear device 1 as viewed from the output side of the rotation axis Ax1. Figure 4 It is a schematic cross-sectional view of the gear device 1 . Figure 5 yes Figure 4 A1-A1 line cross-sectional view. Figure 6 yes Figure 4 B1-B1 line cross-sectional view. Figure 5 and Figure 6 In the figure, although the parts other than the crankshafts 7A, 7B, and 7C are also cross-sectioned, the hatching is omitted.

[0045] (3.1) Overall structure

[0046] like Figure 1 to Figure 4 As shown, the gear device 1 of this basic structure includes an internal gear 2, a planetary gear 3, a bearing member 6, a plurality of crankshafts 7A, 7B, 7C, a pair of brackets 18, 19 and an input shaft 500. In addition, in this basic structure, the gear device 1 also includes an input gear 501, a plurality of crankshaft gears 502A, 502B, 502C, a pair of eccentric shaft bearings 41, 42, an eccentric body bearing 5 and a housing 10. In this basic structure, the internal gear 2, the planetary gear 3, the plurality of crankshafts 7A, 7B, 7C and a pair of brackets 18, 19, etc., which are structural elements of the gear device 1, are made of metals such as stainless steel, cast iron, carbon steel for mechanical structures, chrome-molybdenum steel, phosphor bronze or aluminum bronze, or light metals such as aluminum or titanium. The metal mentioned here includes metals subjected to surface treatment such as nitriding treatment.

[0047] In the present basic structure, an inscribed planetary gear reduction device using a cycloid tooth profile is exemplified as an example of the gear device 1. That is, the gear device 1 of the present basic structure includes an inscribed planetary gear 3 having a cycloid tooth profile.

[0048] In addition, in this basic structure, as an example, the gear device 1 is used in a state where the gear body 22 of the internal gear 2 is fixed to a fixed member such as a housing 10 together with the outer ring 62 of the bearing member 6. As a result, along with the relative rotation of the internal gear 2 and the planetary gear 3, the planetary gear 3 rotates relative to the fixed member (housing 10, etc.).

[0049] Furthermore, in this basic structure, when the gear device 1 is used for the actuator 100, by applying a rotational force as an input to the input shaft 500, a rotational force as an output is taken out from the pair of brackets 18 and 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 the input rotation and the rotation of the pair of brackets 18 and 19 integrated with the inner ring 61 as the output rotation. As a result, in the gear device 1, an output rotation that is reduced by a relatively high reduction ratio relative to the input rotation can be obtained.

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

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

[0052] like Figure 5 and Figure 6 As shown, the internal gear 2 is an annular component having internal teeth 21. In this basic structure, the internal gear 2 has an annular shape whose at least inner circumference is a perfect circle when viewed from above. On the inner circumference of the annular internal gear 2, internal teeth 21 are formed along the circumferential direction of the internal gear 2. The multiple teeth constituting the internal teeth 21 are all of the same shape and are arranged at equal intervals over the entire area of ​​the inner circumferential direction of the internal gear 2. In other words, 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 on the rotation axis Ax1. In addition, the internal gear 2 has a specified 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 a plurality of pins 23. The plurality of 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. In other words, the plurality of pins 23 function as a plurality of teeth constituting the internal teeth 21. Specifically, Figure 2As shown, a plurality of inner circumferential grooves 223 are formed on the inner circumferential surface 221 of the gear body 22 over the entire area in the circumferential direction. The plurality of inner circumferential grooves 223 are all of the same shape and are arranged at equal intervals. The plurality of inner circumferential grooves 223 are all parallel to the rotation axis Ax1 and are formed over the entire length of the thickness direction of the gear body 22. The plurality of pins 23 are assembled to the gear body 22 in a manner embedded in the plurality of inner circumferential grooves 223. Each of the plurality of pins 23 is maintained in a state where it can rotate within the inner circumferential grooves 223. In addition, the gear body 22 (together with the outer ring 62) is fixed to the housing 10. Furthermore, a plurality of fixing holes 222 for fixing are formed in the gear body 22 (see Figure 5 ).

[0054] like Figure 5 and Figure 6 As shown, the planetary gear 3 is an annular component having external teeth 31. In this basic structure, the planetary gear 3 has an annular shape whose outer peripheral surface is a perfect circle when viewed from above. On the outer peripheral surface of the annular planetary gear 3, external teeth 31 are formed 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 arranged at equal intervals in the entire area of ​​the circumferential direction of the outer peripheral surface of the planetary gear 3. In other words, the pitch circle of the external teeth 31 is a perfect circle when viewed from above. In addition, the planetary gear 3 has a specified thickness along the direction of the rotation axis Ax1. The external teeth 31 are formed over the entire length of the planetary gear 3 in the thickness direction. The tooth directions of the external teeth 31 are parallel to the rotation axis Ax1. In the planetary gear 3, unlike the internal gear 2, the external teeth 31 and the main body of the planetary gear 3 are formed integrally by a metal component.

[0055] In addition, the gear device 1 of this basic structure includes a plurality of planetary gears 3. Specifically, the gear device 1 includes two planetary gears 3, namely, a first planetary gear 301 and a second planetary gear 302. The two planetary gears 3 are arranged in a manner opposite to each other in a direction parallel to the rotation axis Ax1. That is, the planetary gear 3 includes 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 common in themselves.

[0056] These two planetary gears 3 (the first planetary gear 301 and the second planetary gear 302) are arranged with a phase difference of 180 degrees around the rotation axis Ax1. Figure 4 In the example of FIG. 1 , the first planetary gear 301 and the second planetary gear 302 located on the input side of the rotation axis Ax1 ( Figure 4 The center C1 of the first planetary gear 301 (the center of the pitch circle of the external tooth 31) is offset (shifted) upward relative to the rotation axis Ax1. Figure 4The center C2 of the second planetary gear 302 (on the left side of the figure) (the center of the pitch circle of the external teeth 31) is in a state of being deviated (offset) downward in the figure 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 plurality of planetary gears 3 are evenly arranged in the circumferential direction centered on the rotation axis Ax1, thereby achieving a balance between the weight and load of the plurality of planetary gears 3.

[0057] The centers C1 and C2 of the first planetary gear 301 and the second planetary gear 302 are 180 degrees rotationally symmetrical with respect to the rotation axis Ax1. In this basic structure, the eccentricity ΔL1 and the eccentricity ΔL2 have opposite directions when viewed from the rotation axis Ax1, but have the same absolute values.

[0058] More specifically, each of the crankshafts 7A, 7B, and 7C has two eccentric portions 72 with respect to one axial portion 71. The eccentricity ΔL0 (see Figure 5 and Figure 6 ) are respectively the same as the eccentricities ΔL1 and ΔL2 of the first planetary gear 301 and the second planetary gear 302 with respect to the rotation axis Ax1. The shapes of the plurality of crankshafts 7A, 7B, 7C are the same. The shapes of the plurality of crankshaft gears 502A, 502B, 502C are the same.

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

[0060] The eccentric body bearing 5 is mounted on the eccentric portion 72 of each crankshaft 7A, 7B, 7C. Three openings 33 corresponding to the three crankshafts 7A, 7B, 7C are formed in the first planetary gear 301 and the second planetary gear 302, respectively. And the eccentric body bearing 5 is accommodated in each opening 33. In other words, the eccentric body bearing 5 is mounted on the first planetary gear 301 and the second planetary gear 302, respectively, and the crankshafts 7A, 7B, 7C are inserted into the eccentric body bearing 5, thereby combining the eccentric body bearing 5 and the crankshafts 7A, 7B, 7C with the planetary gear 3. In the state where the planetary gear 3 is combined with the eccentric body bearing 5 and the crankshafts 7A, 7B, 7C, when the crankshafts 7A, 7B, 7C rotate, the planetary gear 3 swings around the rotation axis Ax1.

[0061] According to the structure described above, the input shaft 500 is rotated around the rotation axis Ax1 by applying a rotation force as an input to the input shaft 500, so that the rotation force is distributed from the input gear 501 to the plurality of crankshafts 7A, 7B, and 7C. That is, when the input gear 501 rotates, the three crankshaft gears 502A, 502B, and 502C that are simultaneously meshed with the input gear 501 rotate in the same direction at the same rotation speed. The crankshafts 7A, 7B, and 7C are spline-connected to the crankshaft gears 502A, 502B, and 502C, so the three crankshafts 7A, 7B, and 7C rotate in the same direction at the same rotation speed in a state where the gear ratio of the input gear 501 and the crankshaft gears 502A, 502B, and 502C is reduced. As a result, the three eccentric portions 72 formed at the same position on the input side of the rotation axis Ax1 in 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 in the three crankshafts 7A, 7B, and 7C rotate synchronously, causing the second planetary gear 302 to oscillate.

[0062] exist Figure 5 and Figure 6 , the states of the first planetary gear 301 and the second planetary gear 302 at a certain time are shown. Figure 5 yes Figure 4 The A1 - A1 line sectional view shows the first planetary gear 301 . Figure 6 yes Figure 4 The B1-B1 line cross-sectional view shows the second planetary gear 302. 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 positions that are approximately 180 degrees rotationally symmetrical with respect to the rotation axis Ax1. In this basic structure, although the directions of the eccentricity ΔL1 and the eccentricity ΔL2 observed from the rotation axis Ax1 are opposite, their absolute values ​​are approximately the same (both are eccentricity ΔL0). According to the above structure, the axial portion 71 rotates (rotates) around the axis Ax2, whereby the first planetary gear 301 and the second planetary gear 302 rotate around the rotation axis Ax1 with a phase difference of approximately 180 degrees (eccentric motion). In addition, the plurality of planetary gears 3 are arranged approximately evenly in the circumferential direction centered on the rotation axis Ax1, thereby achieving a balance between the weight and load of the plurality of planetary gears 3.

[0063] The planetary gears 3 (first planetary gears 301 and second planetary gears 302) thus configured are arranged on the inner side of the internal gear 2. In a plan view, the planetary gears 3 are formed to be one size smaller than the internal gear 2, and the planetary gears 3 can swing on the inner side of the internal gear 2 when combined with the internal gear 2. At this time, the outer teeth 31 are formed on the outer peripheral surface of the planetary gears 3, and the inner teeth 21 are formed on the inner peripheral surface of the internal gear 2. Therefore, when the planetary gears 3 are arranged on the inner side of the internal gear 2, the outer teeth 31 and the inner teeth 21 are opposite to each other.

[0064] Furthermore, the pitch circle of the external teeth 31 is one circle smaller than the pitch circle of the internal teeth 21. Furthermore, when the first planetary gear 301 is inscribed in the internal gear 2, the center C1 of the pitch circle of the external teeth 31 of the first planetary gear 301 is located at a position offset by a distance ΔL1 from the center (rotation axis Ax1) of the pitch circle of the internal teeth 21. Similarly, when the second planetary gear 302 is inscribed in the internal gear 2, the center C2 of the pitch circle of the external teeth 31 of the second planetary gear 302 is located at a position offset by a distance ΔL2 from the center (rotation axis Ax1) of the pitch circle of the internal teeth 21.

[0065] Therefore, in either the first planetary gear 301 or the second planetary gear 302, the outer teeth 31 and at least a portion of the inner teeth 21 are opposite to each other with a gap therebetween. If the difference in the number of teeth between the outer teeth 31 and the inner teeth 21 is greater than "2", the outer teeth 31 and the inner teeth 21 will not mesh with each other as a whole in the circumferential direction. However, the planetary gear 3 swings (revolves) around the rotation axis Ax1 inside the inner gear 2, so that the outer teeth 31 and the inner teeth 21 are partially meshed. That is, by the planetary gear 3 (the first planetary gear 301 and the second planetary gear 302) swinging around the rotation axis Ax1, as shown in FIG. Figure 5 and Figure 6 As shown, some of the teeth constituting the external teeth 31 mesh with some of the teeth constituting the internal teeth 21. As a result, in the gear device 1, a part of the external teeth 31 can mesh with a part of the internal teeth 21.

[0066] Here, the number of teeth of the internal teeth 21 in the internal gear 2 is N (N is a positive integer) greater than the number of teeth of the external teeth 31 of the planetary gear 3. In this basic structure, as an example, N is "2", and the number of teeth (of the external teeth 31) of the planetary gear 3 is "2" less than the number of teeth (of the internal teeth 21) of the internal gear 2. Such a 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 device 1.

[0067] In addition, in this basic structure, as an example, the thickness of the first planetary gear 301 and the second planetary gear 302 combined is smaller than the thickness of the gear body 22 in the internal gear 2. Furthermore, the dimension of the tooth direction (direction parallel to the rotation axis Ax1) of the external teeth 31 combined with the first planetary gear 301 and the second planetary gear 302 is smaller than the dimension of the tooth direction (direction parallel to the rotation axis Ax1) of the internal teeth 21. In other words, in the direction parallel to the rotation axis Ax1, the external teeth 31 of the first planetary gear 301 and the second planetary gear 302 are within the range of the tooth direction of the internal teeth 21.

[0068] Here, the first planetary gear 301 and the second planetary gear 302 are respectively meshed with the internal gear 2. Therefore, each time the first planetary gear 301 and the second planetary gear 302 swing, the first planetary gear 301 and the second planetary gear 302 produce a phase deviation in the circumferential direction of the difference in the number of teeth (internal teeth 21 and external teeth 31) relative to the internal gear 2, and rotate. By rotating, the first planetary gear 301 and the second planetary gear 302 rotate around the inner circumference of the internal gear 2 (that is, revolve around the rotation axis Ax1) while partially meshing with the internal teeth 21 of the internal gear 2. With 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. In this way, the revolution of the planetary gear 3 is transmitted to the pair of brackets 18 and 19 via the plurality of crankshafts 7A, 7B, and 7C. This allows the pair of brackets 18 and 19 to rotate relative to the gear body (integrated with the housing 10 ) about the rotation axis Ax1 .

[0069] In summary, the gear device 1 of this basic structure causes the planetary gear 3 to oscillate by means of a plurality of crankshafts 7A, 7B, and 7C disposed at positions offset from the rotation axis Ax1, and obtains a rotation output by utilizing the oscillation of the planetary gear 3. That is, in the gear device 1, when the planetary gear 3 oscillates and the meshing position of the internal teeth 21 and the external teeth 31 moves along the circumferential direction of the internal gear 2, a relative rotation corresponding to the difference in the number of teeth between the planetary gear 3 and the internal gear 2 is generated 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 (rotates) along with the relative rotation of the two gears. As a result, a rotation 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 member 6 is a component having an outer ring 62 and an inner ring 61 and is used to extract the output of the gear device 1 as the rotation of the inner ring 61 relative to the outer ring 62. The bearing member 6 has a plurality of rolling elements 63 (see Figure 4 ). The outer ring 62 and the inner ring 61 are both annular components. The outer ring 62 and the inner ring 61 both have an annular shape that is a perfect circle when viewed from above. The inner ring 61 is one circle smaller than the outer ring 62 and is arranged on the inner side of the outer ring 62. Here, the inner diameter of the outer ring 62 is larger than the outer diameter of the inner ring 61, so a gap is generated between the inner peripheral surface of the outer ring 62 and the outer peripheral surface of the inner ring 61.

[0071] The plurality of rolling elements 63 are arranged in the gap between the outer ring 62 and the inner ring 61. The plurality of rolling elements 63 are arranged in a row along the circumferential direction of the outer ring 62. The plurality of rolling elements 63 are all metal parts of the same shape and are arranged at equal intervals over the entire circumferential area of ​​the outer ring 62.

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

[0073] Here, the first bearing member 601 and the second bearing member 602 are arranged in opposite directions in a direction parallel to the rotation axis Ax1 on both sides of the planetary gear 3 in a direction parallel to the rotation axis Ax1 (axial direction). That is, the bearing member 6 is a "combined angular ball bearing" in which a plurality of (here, 2) angular ball bearings are combined. Here, as an example, the first bearing member 601 and the second bearing member 602 are "back-to-back combination type" that bears a load in a thrust direction (in the direction along the rotation axis Ax1) in which the respective inner rings 61 approach each other. Furthermore, in the gear device 1, the first bearing member 601 and the second bearing member 602 are combined in a state where appropriate preload is applied to the inner ring 61 by tightening the respective inner rings 61 in a direction in which they approach each other.

[0074] In the gear device 1 of the 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 Figure 4 ) and are combined with each other. Specifically, Figure 4 As shown, when viewed from the planetary gear 3, the input side of the rotation axis Ax1 ( Figure 4 An input side bracket 18 is arranged on the right side of the planetary gear 3, and an output side ( Figure 4 The output side bracket 19 is arranged on the left side of the bearing member 6 (the first bearing member 601 and the second bearing member 602). The inner ring 61 of the bearing member 6 (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, for example) bracket pins 191 (see FIG. 1 ) protruding from one surface of the output side bracket 19 toward the input side of the rotation axis Ax1. Figure 2 ). These multiple bracket pins 191 are respectively passed through multiple (three, for example) bracket holes 34 formed in the planetary gear 3, and the front ends of the multiple bracket pins 191 are connected to the input side bracket 18 by bracket bolts 192 (see Figure 7 Here, a gap is ensured between the bracket pin 191 and the inner circumference of the bracket hole 34, and the bracket pin 191 can move in the bracket hole 34, that is, can move relatively with respect to the center of the bracket hole 34. Therefore, when the planetary gear 3 swings, the bracket pin 191 does not contact the inner circumference of the bracket hole 34.

[0076] With the above structure, the gear device 1 is used in the following manner: the rotation of the planetary gear 3 corresponding to the self-rotation component is extracted as the rotation of the input side bracket 18 and the output side bracket 19 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 extracted from the input side bracket 18 and the output side bracket 19. In this basic structure, as an example, the gear device 1 is based on the outer ring 62 of the bearing member 6 (see Figure 4 ) is used in a state fixed to the housing 10 as a fixed member. That is, the planetary gear 3 is connected to the input side bracket 18 and the output side bracket 19 as the rotating member by using a plurality of crankshafts 7A, 7B, 7C, and the gear body 22 is fixed to the fixed member, so the relative rotation between the planetary gear 3 and the internal gear 2 is taken out from the rotating member (the input side bracket 18 and the output side bracket 19). In other words, in this basic structure, it is configured so that when the planetary gear 3 rotates relative to the gear body 22, the rotational force of the input side bracket 18 and the output side bracket 19 is taken out as output.

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

[0078] In more detail, the housing 10 is cylindrical and constitutes the outer contour of the gear device 1. In this basic structure, the central axis of the cylindrical housing 10 is configured to be consistent with the rotation axis Ax1. That is, at least the outer peripheral surface of the housing 10 is a perfect circle centered on the rotation axis Ax1 when viewed from above (viewed from one axial direction). The housing 10 is formed into a cylindrical shape with both end surfaces open in the axial direction. 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 one component. Therefore, the inner peripheral surface of the housing 10 includes the inner peripheral surface 221 of the gear body 22. Furthermore, the outer ring 62 of the bearing member 6 is fixed to the housing 10. That is, when viewed from the gear body 22 in the inner peripheral surface of the housing 10, the outer ring 62 of the first bearing member 601 is fixed to the input side ( Figure 4 On the other hand, when 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 on the left side of the ).

[0079] Furthermore, the input side ( Figure 4 The end face of the housing 10 (on the right side) is blocked by the input side bracket 18, and the output side (on the right side) of the rotation axis Ax1 of the housing 10 Figure 4The end face of the left side of the output side bracket 19 is blocked. Figure 4 As shown, in a space surrounded by the housing 10 , the input side bracket 18 and the output side bracket 19 , components such as the planetary gears 3 (the first planetary gears 301 and the second planetary gears 302 ), a plurality of pins 23 and the eccentric bearing 5 are accommodated.

[0080] Multiple (3 in the basic structure) crankshafts 7A, 7B, and 7C respectively have an axial portion 71 and two eccentric portions 72. The axial portion 71 has a cylindrical shape in which at least the outer peripheral surface is a perfect circle when viewed from above. 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 in which at least the outer peripheral surface is a perfect circle when viewed from above. The center (center axis) C0 of each eccentric portion 72 is parallel to the rotation axis Ax1, and is arranged at a position radially deviated from the rotation axis Ax1. Here, the distance ΔL0 (refer to Figure 5 and Figure 6 ) becomes the eccentricity relative to the shaft portion 71. The eccentric portion 72 is in the shape of a flange that protrudes from the outer peripheral surface of the shaft portion 71 all around the central portion in the length direction (axial direction) of the shaft portion 71. According to the above-mentioned structure, for each crankshaft 7A, 7B, 7C, the shaft portion 71 rotates (rotates) around the axis Ax2, so that the eccentric portion 72 performs eccentric motion.

[0081] In this basic structure, the axial portion 71 and the two eccentric portions 72 are integrally formed by one metal member, thereby realizing a seamless crankshaft 7A, 7B, 7C. The crankshaft 7A, 7B, 7C of such a shape is combined with the eccentric body bearing 5 to the planetary gear 3. Therefore, in a state where the planetary gear 3 is combined with the eccentric body bearing 5 and the crankshaft 7A, 7B, 7C, when the crankshaft 7A, 7B, 7C rotates, the planetary gear 3 swings around the rotation axis Ax1.

[0082] The eccentric bearing 5 has a plurality of rolling elements 51 (see Figure 4 ), and absorbs the rotational component of the crankshafts 7A, 7B, 7C, and transmits only the rotation of the crankshafts 7A, 7B, 7C other than the rotational component of the crankshafts 7A, 7B, 7C, that is, the swing component (revolution component) of the crankshafts 7A, 7B, 7C to the planetary gear 3. A plurality of rolling elements 51 are arranged between the outer peripheral surface of the eccentric portion 72 of each crankshaft 7A, 7B, 7C and the inner peripheral surface of each opening portion 33 of the planetary gear 3. That is, the eccentric portion 72 of each crankshaft 7A, 7B, 7C functions as the inner ring of the eccentric body bearing 5, and the inner peripheral surface of each opening portion 33 of the planetary gear 3 functions as the outer ring of the eccentric body bearing 5.

[0083] In the state where the planetary gear 3 is combined with the eccentric body bearing 5 and the plurality of crankshafts 7A, 7B, 7C, when each crankshaft 7A, 7B, 7C rotates (rotates on its own axis), each eccentric portion 72 rotates (eccentrically moves) around the axis Ax2. The planetary gear 3 is provided at a position corresponding to each eccentric portion 72 in a direction (axial direction) parallel to the rotation axis Ax1, so the eccentric motion of each eccentric portion 72 is transmitted to the planetary gear 3 via the eccentric body bearing 5, and the planetary gear 3 swings around the rotation axis Ax1. That is, the eccentric motion of the eccentric portion 72 in the crankshaft 7A, 7B, 7C is transmitted to the planetary gear 3. The eccentric body bearing 5 plays a role in relieving the friction caused by the relative rotation caused by the speed difference between the eccentric motion of the eccentric portion 72 of each crankshaft 7A, 7B, 7C (that is, the rotation of each crankshaft 7A, 7B, 7C) and the revolution of the planetary gear 3, and plays a role in power transmission.

[0084] In the gear device 1 of the above-described structure, a rotational force is applied as an input to the input shaft 500, so that the input shaft 500 rotates around the rotation axis Ax1, and the planetary gear 3 swings (revolves) around the rotation axis Ax1. At this time, the planetary gear 3 swings in a state where it is inscribed in the inner side of the internal gear 2 and a part of the external teeth 31 meshes with a part of the internal teeth 21. Therefore, the meshing position of the internal teeth 21 and the external teeth 31 moves along the circumferential direction of the internal gear 2 as the input shaft 500 rotates. As a result, a relative rotation corresponding to the difference in the number of teeth between the planetary gear 3 and the internal gear 2 occurs between the two gears (the internal gear 2 and the planetary gear 3). In addition, the rotation (autorotation component) of the planetary gear 3 in addition to the swing component (revolution component) of the planetary gear 3 is transmitted to the pair of carriers 18 and 19 through the plurality of crankshafts 7A, 7B, and 7C. As a result, a rotation output reduced in speed at a relatively high reduction ratio according to the difference in the number of teeth between the two gears is obtained from the pair of carriers 18 and 19 .

[0085] However, as described above, in the gear device 1 of the present 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] The smaller the difference (V1-V2) in the number of teeth between the internal gear 2 and the planetary gear 3 is, the larger the reduction ratio R1 is. 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 (V1-V2) between the numbers of teeth is "2", so according to the above formula 1, the reduction ratio R1 is "35". In this case, when each crankshaft 7A, 7B, 7C is viewed from the input side of the rotating shaft Ax1 with the axis Ax2 (refer to Figure 5 and Figure 6 ) is rotated clockwise for one circle (360 degrees) around the rotation axis Ax1, the pair of brackets 18 and 19 rotate counterclockwise around the rotation axis Ax1 by the difference in the number of teeth "2" (that is, about 10.3 degrees).

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

[0089] In addition, the gear device 1 only needs to include at least the internal gear 2, the planetary gear 3, the crankshafts 7A, 7B, 7C and a pair of brackets 18, 19, for example. Figure 4 As shown, a spacer 11 may be further included. The spacer 11 is disposed between the pair of planetary gears 3 (the first planetary gear 301 and the second planetary gear 302) in a direction (axial direction) parallel to the rotation axis Ax1.

[0090] (Implementation Method 1)

[0091] like Figure 7 to Figure 9 As shown, the internal meshing planetary gear device 1A of this embodiment (hereinafter, also simply referred to as "gear device 1A") is mainly different from the basic gear device 1 in the structure of the eccentric shaft bearings 41 and 42. Hereinafter, the same reference numerals are attached to the same structure as the basic structure and the description is omitted as appropriate.

[0092] In this embodiment, each pair of eccentric shaft bearings 41, 42 supporting each crankshaft 7A, 7B, 7C is composed of "sliding bearings". That is, both ends of each crankshaft 7A, 7B, 7C are held by a pair of brackets 18, 19 via the eccentric shaft bearings 41, 42 composed of "sliding bearings".

[0093] The "sliding bearing" mentioned in the present invention is a bearing device that supports a load through a thin lubricant layer (oil film, etc.) by combining a shaft and a bearing hole. In other words, each eccentric shaft bearing 41, 42 is composed of a "sliding bearing" that does not contain rolling elements such as balls, cylindrical rollers, or tapered rollers, but only has a bearing hole as a structure for inserting a shaft (here, the crankshafts 7A, 7B, 7C).

[0094] Specifically, if Figure 7 As shown, a pair of eccentric shaft bearings 41 and 42 supporting both ends of the crankshafts 7A, 7B, and 7C respectively have bearing holes 40 formed in a pair of brackets 18 and 19. The bearing holes 40 are through holes that penetrate the brackets 18 and 19 in the axial direction (in a direction parallel to the rotation axis Ax1), and are formed in a circular (perfect circle) shape when viewed from one side in the axial direction. The bearing hole 40 of the eccentric shaft bearing 41 formed in the input side bracket 18 and the bearing hole 40 of the eccentric shaft bearing 42 formed in the output side bracket 19 are concentric and have the same shape when viewed from one side in the axial direction.

[0095] Here, the diameter (inner diameter) of the bearing hole 40 is substantially the same as the diameter (outer diameter) of the axial center portion 71 of the crankshaft 7A, 7B, 7C. Therefore, when the axial center portions 71 at both ends of the crankshafts 7A, 7B, and 7C are inserted into the bearing holes 40 of the pair of eccentric shaft bearings 41 and 42, both ends of the crankshafts 7A, 7B, and 7C are supported by the pair of eccentric shaft bearings 41 and 42 so as to be rotatable.

[0096] exist Figure 7 In the figure, although only the crankshaft 7A is shown, each crankshaft 7B, 7C is similarly provided with a pair of eccentric shaft bearings 41, 42 supporting both end portions thereof. That is, the gear device 1A of the present embodiment is the same as the basic structure, and is an internal meshing planetary gear device of an eccentric oscillating type called a distributed type. Therefore, a plurality (3) of crankshafts 7A, 7B, 7C are provided, and these plurality of crankshafts 7A, 7B, 7C are arranged at positions offset from the rotation axis Ax1 which is the axis center of the internal gear 2, and are synchronously driven by the input gear 501. Therefore, a plurality of pairs (here, 3 pairs) of eccentric shaft bearings 41, 42 are provided in a manner that supports the plurality of crankshafts 7A, 7B, 7C, respectively.

[0097] As described above, the gear device 1A of the present embodiment includes: an internal gear 2 having internal teeth 21; a planetary gear 3 having external teeth 31 partially meshing with the internal teeth 21; crankshafts 7A, 7B, 7C; and eccentric shaft bearings 41, 42. The crankshafts 7A, 7B, 7C cause the planetary gears 3 to oscillate by rotating around the axis. The eccentric shaft bearings 41, 42 support the crankshafts 7A, 7B, 7C. The gear device 1A is an internal meshing planetary gear device that causes the planetary gears 3 to rotate relative to the internal gear 2 around the rotation axis Ax1 by causing the planetary gears 3 to oscillate using the crankshafts 7A, 7B, 7C. Here, the eccentric shaft bearings 41, 42 are composed of sliding bearings.

[0098] According to this structure, there is an advantage that when the gear device 1A is viewed from the axial direction (the direction parallel to the rotation axis Ax1), it is easy to suppress the range occupied by the eccentric shaft bearings 41 and 42. Therefore, it is easy to suppress the radial dimension of the gear device 1A to achieve miniaturization of the gear device 1A. In addition, if the radial dimension of the gear device 1A is constant, it is easy to enlarge the pitch circle diameter of the bearing member 6 (the first main bearing 601 and the second main bearing 602) and / or the crankshafts 7A, 7B, 7C.

[0099] In summary, the bearing devices that can rotatably support the shaft members such as the crankshafts 7A, 7B, and 7C are roughly divided into "rolling bearings" and "sliding bearings". Rolling bearings have rolling elements such as balls, cylindrical rollers, or tapered rollers, and can rotatably support the shaft members by moving (that is, rolling) the rolling elements in a rolling manner between the inner ring and the outer ring. On the other hand, sliding bearings do not have rolling elements, and can rotatably support the shaft members by sliding the shaft members inserted into the bearing holes relative to the inner circumferential surface of the bearing holes.

[0100] In the gear device 1 of the basic structure, the eccentric shaft bearings 41 and 42 supporting the crankshafts 7A, 7B, and 7C are both composed of "rolling bearings" such as cylindrical roller bearings or tapered roller bearings. Therefore, the eccentric shaft bearings 41 and 42 supporting the crankshafts 7A, 7B, and 7C have a plurality of rolling elements around the crankshafts 7A, 7B, and 7C, respectively. As a result, when the gear device 1 of the basic structure is viewed from the axial direction (the direction parallel to the rotation axis Ax1), the range occupied by the eccentric shaft bearings 41 and 42 becomes larger, which hinders the miniaturization of the gear device 1.

[0101] In contrast, in the gear device 1A of the present embodiment, the eccentric shaft bearings 41 and 42 supporting the crankshafts 7A, 7B, and 7C are both formed of "sliding bearings". Therefore, the eccentric shaft bearings 41 and 42 supporting the crankshafts 7A, 7B, and 7C do not have a plurality of rolling elements around the crankshafts 7A, 7B, and 7C, respectively, so that when the gear device 1A is viewed from one axial direction, the range occupied by the eccentric shaft bearings 41 and 42 can be reduced.

[0102] Thus, in the gear device 1A of the present embodiment, the space created by reducing the range occupied by the eccentric shaft bearings 41 and 42 can be used, for example, to suppress the radial dimension of the gear device 1A and thereby miniaturize the gear device 1A, or to expand the pitch circle diameter of the bearing assembly 6 (the first main bearing 601 and the second main bearing 602) and / or the crankshafts 7A, 7B, 7C.

[0103] As an example, the gear device 1A of the present embodiment has the same radial dimensions as the gear device 1A compared to the gear device 1 of the basic structure, but the size of the bearing member 6 (the first main bearing 601 and the second main bearing 602) is increased by utilizing the space created by reducing the range occupied by the eccentric shaft bearings 41 and 42. Thus, the gear device 1A of the present embodiment can achieve an increase in the load capacity of the bearing member 6 and improve the rigidity of the bearing member 6 compared to the gear device 1 of the basic structure.

[0104] That is, Figure 7 As shown in the example, Figure 4 Compared with the basic structure shown in the figure, the size of the first bearing member 601 and the second bearing member 602 composed of angular ball bearings is enlarged 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 space created by using the eccentric shaft bearings 41 and 42 as sliding bearings is used to enlarge the diameter of the rolling element 63 to improve the load capacity.

[0105] However, in the present embodiment, a pair of main bearings (first main bearing 601 and second main bearing 602) are provided to support the carriers 18 and 19 that rotate relative to the internal gear 2 as the planetary gears 3 rotate relative to the internal gear 2 in a manner rotatable relative to the internal gear 2. Furthermore, the 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, if Figure 7As shown, in the axial direction (the direction along the rotation axis Ax1), the eccentric shaft bearings 41 and 42 are arranged so as to be accommodated between the ends of the outer sides (the side opposite to the planetary gear 3) of a pair of main bearings (the first main bearing 601 and the second main bearing 602). More specifically, the bearing hole 40 of the eccentric shaft bearing 41 is formed in the inner ring 61 (the input side bracket 18) of the first main bearing 601, so the eccentric shaft bearing 41 is arranged to be accommodated within the width dimension of the first main bearing 601 in the axial direction. Similarly, the bearing hole 40 of the eccentric shaft bearing 42 is formed in the inner ring 61 (the output side bracket 19) of the second main bearing 602, so the eccentric shaft bearing 42 is arranged to be accommodated within the width dimension of the second main bearing 602 in the axial direction.

[0107] In this way, the eccentric shaft bearings 41 and 42 are located between the outer ends of a pair of main bearings (the first main bearing 601 and the second main bearing 602) in the direction along the rotation axis Ax1, thereby suppressing the size of the gear device 1A in the axial direction. In addition, the eccentric shaft bearings 41 and 42 may overflow from the inner ends of the pair of main bearings to the inner side (the planetary gear 3 side) in the axial direction, or may be located between the inner ends of the pair of main bearings. Furthermore, the eccentric shaft bearings 41 and 42 may overflow from the outer ends of the pair of main bearings to the outer side (the side opposite to the planetary gear 3) in the axial direction, or may be located at a position closer to the outside than the outer ends of the pair of main bearings.

[0108] In addition, if Figure 8 and Fig. 9 As shown, the axial positioning of the crankshafts 7A, 7B, 7C can be performed by the inner ring 61 (a pair of brackets 18, 19) of the bearing member 6 (the first main bearing 601 and the second main bearing 602). Figure 8 An enlarged view showing the periphery of the crankshaft 7A, Fig. 9 Show Figure 8 A1-A1 line view and B1-B1 line view.

[0109] Specifically, if Figure 8 and Fig. 9 As shown, the portion of the inner ring 61 (a pair of brackets 18, 19) of the bearing member 6 (the first main bearing 601 and the second main bearing 602) that is closer to the inside (the rotation axis Ax1 side) than the bearing hole 40 constitutes an extension portion 400 that extends toward the axial center side (the planetary gear 3 side).

[0110] Here, Fig. 9 The "B1-B1 line view" Figure 1 ” shows the state where the contact area between the eccentric portion 72 and the extension portion 400 is the smallest, and “B1-B1 line Figure 2 ” shows the state where the contact area between the eccentric portion 72 and the extension portion 400 is the largest. Further, Fig. 9The "B1-B1 line view" Figure 3 "" is a state in which the contact area between the eccentric portion 72 and the extension portion 400 is the smallest, and the eccentric body bearing 5 is shown by an imaginary line (two-dot chain line). Fig. 9 In FIG. 1 , the oblique line portion shows the contact area between the eccentric portion 72 or the eccentric body bearing 5 and the protruding portion 400 .

[0111] Thus, the crankshafts 7A, 7B, and 7C are restricted from moving outward in the axial direction (opposite to the planetary gear 3) by making the eccentric portion 72 contact the portion (protruding portion 400) of the inner ring 61 that is on the inner side of the bearing hole 40. Similarly, the eccentric body bearing 5 (particularly its retainer) is also restricted from moving outward in the axial direction (opposite to the planetary gear 3) by making it contact the portion (protruding portion 400) of the inner ring 61 that is on the inner side of the bearing hole 40. Therefore, it is not necessary to use other components such as retaining rings for positioning the crankshafts 7A, 7B, and 7C, and the structure can be simplified.

[0112] Here, the portion of the inner ring 61 that is outside the extension portion 400 (on the opposite side to the rotation axis Ax1) is axially opposed to the eccentric portion 72 and the eccentric body bearing 5 (especially its retainer) with a gap of about 1 mm as an example. Thus, a passage for lubricant (lubrication, etc.) to pass is formed between the portion of the inner ring 61 that is outside the extension portion 400 and the eccentric portion 72 and the eccentric body bearing 5.

[0113] As a result, it is easy to supply lubricant to the eccentric shaft bearings 41 and 42. That is, in the present embodiment, the eccentric shaft bearings 41 and 42 have bearing holes 40 into which the crankshafts 7A, 7B and 7C are inserted, and lubricant is sandwiched between the outer peripheral surfaces of the crankshafts 7A, 7B and 7C and the inner peripheral surfaces of the bearing holes 40. As a result, the friction of the eccentric shaft bearings 41 and 42, which are formed of sliding bearings, can be reduced, and the loss at the eccentric shaft bearings 41 and 42 can be reduced.

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

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

[0116] In the gear device 1A of the present 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 rotatably held in a plurality of inner peripheral grooves 223 formed on the inner peripheral surface 221 of the gear body 22.

[0117] Thus, the plurality of pins 23 constituting the internal teeth 21 can be easily arranged by utilizing the space created by reducing the range occupied by the eccentric shaft bearings 41 and 42 .

[0118] However, if Fig.10 As shown, the gear device 1A of this embodiment constitutes a robot joint device 200 (i.e., a robot arm structure) together with the first member 201 and the second member 202. In other words, the robot joint device 200 equipped with the robot arm structure of this embodiment includes the gear device 1A, the first member 201, and the second member 202. The first member 201 is fixed to the internal gear 2. The second member 202 rotates relative to the first member 201 as the planetary gear 3 rotates relative to the internal gear 2. Fig.10 2 is a schematic cross-sectional view of the robot joint device 200. Fig.10 , a first member 201, a second member 202, and a driving source 101 are schematically shown.

[0119] The robot joint device 200 thus constructed functions as a joint device by rotating the first member 201 and the second member 202 relative to each other around 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 (input rotation) generated by the drive source 101 is decelerated at a relatively high reduction ratio in the gear device 1A, and the first member 201 or the second member 202 is driven at a relatively high torque. That is, the first member 201 and the second member 202 connected by the gear device 1A can perform flexion and extension movements around the rotation axis Ax1.

[0120] The robot joint device 200 (i.e., the robot mechanical arm structure) is used for a robot such as a horizontal multi-joint robot (articulated robot). Furthermore, the robot joint device 200 is not limited to a horizontal multi-joint robot, and can be used for an industrial robot other than a horizontal multi-joint robot, or a robot other than an industrial robot. In addition, the gear device 1A of this embodiment is not limited to the robot joint device 200, and can be used for a vehicle such as an unmanned guided vehicle (AGV) as a wheel device such as a wheel hub motor.

[0121] <Modification>

[0122] Embodiment 1 is only one of various embodiments of the present invention. Embodiment 1 can be modified in various ways according to design, etc., as long as it can achieve the purpose of the present invention. In addition, the drawings referred to in the present invention are all schematic diagrams, and the size and thickness ratios of the various structural elements in the drawings are not necessarily limited to reflect the actual dimensional ratios. The following lists the modified examples of embodiment 1. The modified examples described below can be appropriately combined and applied.

[0123] The bearing member 6 (the first main bearing 601 and the second main bearing 602) is not limited to an angular ball bearing, for example, Fig.11 As shown in FIG. 1 , a tapered roller bearing may be used that uses tapered rollers as rolling elements 63. In this structure, Fig.11 As shown, the load action line LL1 of the bearing member 6 (the first main bearing 601 and the second main bearing 602) is located at a position passing through the eccentric shaft bearings 41 and 42 constituted by sliding bearings.

[0124] In addition, the bearing member 6 (the first main bearing 601 and the second main bearing 602) may also be, for example, Fig.12 As shown in FIG. 1 , a cylindrical roller bearing is shown that uses cylindrical rollers as rolling elements 63. In this structure, Fig.12 As shown, the contact angles of the bearing member 6 (the first main bearing 601 and the second main bearing 602) are both 45 degrees, and the inner ring 61 has flanges for limiting the movement on both sides of the axial direction of the rolling element 63. In this case, the load action line LL2 of the bearing member 6 (the first main bearing 601 and the second main bearing 602) does not pass through the eccentric shaft bearings 41 and 42 constituted by sliding bearings.

[0125] The number of crankshafts 7A, 7B, and 7C is not limited to "3", and may be 2 or 4 or more. Furthermore, if there is only one crankshaft, it is not a distributed type, but an eccentric swing type internal meshing planetary gear device that realizes the coincidence of the rotation axis Ax1 and the axis center Ax2 of the crankshaft. In this case, the planetary gear 3 is swung by driving the crankshaft, and the pair of brackets 18 and 19 can be relatively rotated with respect to the gear body 22 around the rotation axis Ax1.

[0126] In addition, in the first embodiment, a gear device 1A of the type having two planetary gears 3 is illustrated, but the gear device 1A may include more than three planetary gears 3. For example, when the gear device 1A includes three planetary gears 3, it is preferred that the three planetary gears 3 are arranged with a phase difference of 120 degrees around the rotation axis Ax1. In addition, the gear device 1A may include only one planetary gear 3. Alternatively, when the gear device 1A includes three planetary gears 3, two of the three planetary gears 3 may be in the same phase, and the remaining one planetary gear 3 may be arranged with a phase difference of 180 degrees around the rotation axis Ax1.

[0127] In addition, the bearing member 6 may be a crossed roller bearing, a deep groove ball bearing, a four-point contact ball bearing, or the like.

[0128] The number of teeth of the input gear 501, the number of teeth of the crank gears 502A, 502B, 502C, the number of pins 23 (the number of teeth of the internal teeth 21), and the number of teeth of the external teeth 31 described in the first embodiment are merely examples and may be changed as appropriate.

[0129] In addition, the material of each component of the gear device 1A is not limited to metal, and may be, for example, resin such as engineering plastic.

[0130] In addition, the gear device 1A is not limited to a structure that takes out the rotational force of the inner ring 61 (input side bracket 18 and output side bracket 19) as output, as long as it can take out the relative rotation between the inner ring 61 and the outer ring 62 of the bearing member 6 as output. For example, the rotational force of the outer ring 62 (housing 10) that rotates relative to the inner ring 61 can also be taken out as output.

[0131] The lubricant is not limited to liquid substances such as lubricating oil (oil), and may be a gel-like substance such as grease.

[0132] (Implementation Method 2)

[0133] like Fig.13 and Fig.14 As shown, the internal meshing planetary gear device 1B of this embodiment (hereinafter, also referred to as "gear device 1B") is different from the gear device 1A of the first embodiment in that a preload is applied to the eccentric shaft bearings 41 and 42. Hereinafter, the same reference numerals are attached to the same structures as those of the first embodiment, and the description is omitted as appropriate.

[0134] That is, in this embodiment, the eccentric shaft bearings 41 and 42 have bearing holes 40 into which the crankshafts 7A, 7B, and 7C are inserted, and preload is applied so 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 axial portion 71 of the crankshaft 7A, 7B, 7C is slightly larger than the inner diameter of the bearing hole 40. In addition, in the crankshaft 7A, 7B, 7C, the axial portion 71 is set to a hollow cylindrical structure, and has a slit 43 along the axial direction (a direction parallel to the rotation axis Ax1) in a part of the circumferential direction. In other words, the axial portion 71 is a front end split structure in which the front end portion in the axial direction is separated into a plurality of parts. In this embodiment, as an example, four slits 43 are arranged at 90 degree intervals in the circumferential direction.

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

[0137] The specific method of applying the preload is not limited to the above-mentioned structure, and various methods can be applied.

[0138] The structure of the second embodiment can be appropriately combined with the basic structure or various structures (including modified examples) described in the first embodiment.

[0139] (Summarize)

[0140] As described above, the first form of the internally meshing planetary gear device (1, 1A, 1B) includes: an internal gear (2) having internal teeth (21); a planetary gear (3) having external teeth (31) partially meshing with the internal teeth (21); a crankshaft (7A, 7B, 7C); and an eccentric shaft bearing (41, 42). The crankshaft (7A, 7B, 7C) causes the planetary gear (3) to oscillate by rotating around the axis. The eccentric shaft bearing (41, 42) supports the crankshaft (7A, 7B, 7C). The internally meshing planetary gear device (1, 1A, 1B) causes the planetary gear (3) to rotate relative to the internal gear (2) around the rotation axis (Ax1). The eccentric shaft bearing (41, 42) is composed of a sliding bearing.

[0141] According to this aspect, there is an advantage that when the inner meshing planetary gear device (1, 1A, 1B) is viewed from the axial direction (direction parallel to the rotation axis (Ax1)), the range occupied by the eccentric shaft bearing (41, 42) can be easily suppressed. Therefore, the radial dimension of the inner meshing planetary gear device (1, 1A, 1B) can be easily suppressed to achieve miniaturization of the inner meshing planetary gear device (1, 1A, 1B). In addition, if the radial dimension of the inner meshing planetary gear device (1, 1A, 1B) is constant, it is easy to achieve an increase in the pitch diameter of the bearing member 6 (the first main bearing 601 and the second main bearing 602) and / or the crankshaft (7A, 7B, 7C).

[0142] In a second embodiment of an internally meshing planetary gear device (1, 1A, 1B), based on the first embodiment, a plurality of crankshafts (7A, 7B, 7C) are provided, the plurality of crankshafts (7A, 7B, 7C) are located at positions offset from a rotation axis (Ax1) serving as the axis of an internal gear (2), and are synchronously driven by an input gear (501). A plurality of pairs of eccentric shaft bearings (41, 42) are provided in a manner that supports the plurality of crankshafts (7A, 7B, 7C) respectively.

[0143] According to this aspect, a relatively large space can be created by using a plurality of pairs of eccentric shaft bearings (41, 42) as sliding bearings.

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

[0145] According to this aspect, the plurality of pins (23) constituting the internal teeth (21) can be easily arranged by utilizing the space created by reducing the range occupied by the eccentric shaft bearings (41, 42).

[0146] In a fourth embodiment of an internally meshing planetary gear device (1, 1A, 1B), in addition to any one of the first to third embodiments, an eccentric shaft bearing (41, 42) has a bearing hole (40) for a crankshaft (7A, 7B, 7C), and a preload is applied in a manner that fills a gap between an outer peripheral surface of the crankshaft (7A, 7B, 7C) and an inner peripheral surface of the bearing hole (40).

[0147] According to this aspect, low backlash can be achieved.

[0148] In a fifth embodiment of an internally meshing planetary gear device (1, 1A, 1B), based on any one of the first to fourth embodiments, an eccentric shaft bearing (41, 42) has a bearing hole (40) for inserting a crankshaft (7A, 7B, 7C), and a lubricant is sandwiched between an outer peripheral surface of the crankshaft (7A, 7B, 7C) and an inner peripheral surface of the bearing hole (40).

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

[0150] In the sixth form of the internally meshing planetary gear device (1, 1A, 1B), in addition to any one of the first to fifth forms, it also includes a pair of main bearings (first main bearing 601 and second main bearing 602). The pair of main bearings (first main bearing 601 and second main bearing 602) support the bracket (18, 19) that rotates relative to the internal gear (2) in a manner that can rotate relative to the internal gear (2) as the planetary gear (3) rotates relative to the internal gear (2). The eccentric shaft bearing (41, 42) is 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 aspect, the size of the internally meshing planetary gear device (1, 1A, 1B) in the axial direction (direction parallel to the rotation axis (Ax1)) can be suppressed.

[0152] The seventh form of the robot joint device (200) includes: an internal meshing planetary gear device (1, 1A, 1B) of any one of the first to sixth forms; 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 form, there is the following advantage: when the internal meshing planetary gear device (1, 1A, 1B) is observed from one side of the axial direction (the direction parallel to the rotation axis (Ax1)), it is possible to realize a robot joint device (200) in which the range occupied by the eccentric shaft bearings (41, 42) is easily suppressed.

[0154] The structures of the second to fifth forms are not essential for the internally meshing planetary gear device (1, 1A, 1B) and can be omitted as appropriate.

Claims

1. A robot arm structure, comprising a robot joint device, wherein: The robot joint device comprises: An internally meshing planetary gear device, comprising: an internally toothed gear having internal teeth; a planetary gear having external teeth partially meshing with the internal teeth; a crankshaft that rotates about an axis to cause the planetary gear to oscillate; and an eccentric shaft bearing that supports the crankshaft, wherein the planetary gear is caused to rotate relative to the internally toothed gear about a rotation axis by causing the planetary gear to oscillate, and the eccentric shaft bearing is composed of a sliding bearing; A first member fixed to the internal gear; and The second member rotates relative to the first member in accordance with the relative rotation of the planetary gear with respect to the internal gear.

2. An internally meshing planetary gear device, wherein: include: Internal gears, having internal teeth; a planetary gear having external teeth partially meshing with the internal teeth; a crankshaft that rotates about an axis to cause the planetary gear to oscillate; and An eccentric shaft bearing supports the crankshaft. By swinging the planetary gear, the planetary gear is rotated relative to the internal gear about the rotation axis. The eccentric shaft bearing is composed of a sliding bearing.

3. The internally meshing planetary gear device according to claim 2, wherein: The crankshaft is provided with a plurality of The plurality of crankshafts are arranged at positions offset from the rotation axis, which is the axis center of the internal gear, and are synchronously driven by an input gear. A plurality of pairs of the eccentric shaft bearings are provided so as to respectively support the plurality of crankshafts.

4. The internally meshing planetary gear device according to claim 2 or 3, wherein: The internal gear includes: an annular gear body; and a plurality of pins rotatably held in a plurality of inner peripheral grooves formed on an inner peripheral surface of the gear body, constituting the internal teeth.

5. The internally meshing planetary gear device according to claim 2 or 3, wherein: The eccentric shaft bearing has a bearing hole for inserting the crankshaft. A preload is applied so as to fill a gap between the outer peripheral surface of the crankshaft and the inner peripheral surface of the bearing hole.

6. The internally meshing planetary gear device according to claim 2 or 3, wherein: The eccentric shaft bearing has a bearing hole for inserting the crankshaft. A lubricant is interposed between the outer peripheral surface of the crankshaft and the inner peripheral surface of the bearing hole.

7. The internally meshing planetary gear device according to claim 2 or 3, wherein: The internally meshing planetary gear device further includes a pair of main bearings, the pair of main bearings supporting a carrier that rotates relative to the internal gear as the planetary gear rotates relative to the internal gear in a manner rotatable relative to the internal gear. The eccentric shaft bearing is located between outer side ends of the pair of main bearings in a direction along the rotation axis.

8. A joint device for a robot, wherein: include: The internal meshing planetary gear device according to any one of claims 2 to 7; A first member fixed to the internal gear; and The second member rotates relative to the first member in accordance with the relative rotation of the planetary gear with respect to the internal gear.

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