Internal meshing planetary gear device and joint device for robot

Abstract

The invention provides an internal meshing planetary gear device and a joint device for a robot, which can realize improvement of a lubrication state. An internally engaged planetary gear device (1A) is provided with an internally toothed gear (2), a planetary gear (3), crankshafts (7A, 7B, 7C), and a pair of carriers (18, 19). The crankshafts (7A, 7B, 7C) have stepped portions in at least two locations in the axial direction along the axial center (Ax2), and swing the planetary gear (3) by rotating about the axial center (Ax2). The pair of gear carriers (18, 19) are disposed on both axial sides of the planetary gear (3) and rotatably support the crankshafts (7A, 7B, 7C). Lubricating passages (S1) through which a lubricant passes are respectively formed between the stepped part and the pair of gear carriers (18, 19).

Description

Technical Field

[0001] This disclosure generally relates to an internal meshing planetary gear device and a joint device for robots, and more specifically, to an internal meshing planetary gear device and a joint device for robots in which a planetary gear with external teeth is disposed inside an internal gear with internal teeth. Background Art

[0002] As a related technology, there is a known eccentric oscillating internal meshing planetary gear device called a split type (see, for example, Patent Document 1). In the internal meshing planetary gear device of the related technology, there are multiple (e.g., 3) crankshafts arranged at positions offset from the axis of the internal gear, and each crankshaft is driven synchronously by a crankshaft gear, thereby causing the planetary gear (external gear) to oscillate while internally meshing with the internal gear.

[0003] The planetary gear system comprises a first planetary gear and a second planetary gear. A pair of gear carriers are arranged on both sides of the first and second planetary gears along their axial direction. Each crankshaft is supported on the gear carriers via 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. Since the crankshafts are splined to each crankshaft gear, the three crankshafts rotate in the same direction at the same speed while being decelerated by the gear ratio of the input gear to the crankshaft gears. 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. The internal gears have a gear body and an outer pin (pin member), which is rotatably fitted into the gear body to form the internal teeth of the internal gear. Here, the number of teeth on the internal gear (the number of pin roots) is slightly greater than the number of teeth on each planetary gear. Therefore, each time each planetary gear oscillates once, the circumferential phase deviation (rotation) of the first and second planetary gears relative to the internal gear corresponds to the difference in the number of teeth. This rotation is transmitted to a pair of gear carriers as the revolution of each crankshaft around the axis (rotation axis) of the internal gear. Thus, the pair of gear carriers can rotate relative to the gear body (with its integrated housing) about the rotation axis.

[0005] [Prior art literature]

[0006] [Patent Document]

[0007] Patent Document 1: Japanese Patent Application Publication No. 2016-75354 Summary of the Invention

[0008] [Problems to be solved by the invention]

[0009] In the structure of the aforementioned technology, each crankshaft is supported by a pair of gear carriers via a pair of tapered roller bearings. However, friction is generated everywhere during the rotation of the crankshafts, which may cause losses in power transmission. Especially in the case of long-term use of internal meshing planetary gear devices, for example, the loss caused by friction may increase due to lubricant deterioration, thereby hindering the longevity of the internal meshing planetary gear device.

[0010] The purpose of this disclosure is to provide an internal meshing planetary gear device and a joint device for robots that can achieve improved lubrication.

[0011] [Technical means to solve the problem]

[0012] One aspect of the disclosed internal meshing planetary gear device includes an internal gear, planetary gears, a crankshaft, and a pair of gear carriers. The planetary gears rotate relative to the internal gear by oscillating. The internal gear has an annular gear body and multiple outer pins, which are rotatably held in multiple inner circumferential grooves formed on the inner circumferential surface of the gear body and constitute internal teeth. The planetary gears have outer teeth that partially mesh with the internal teeth. The crankshaft has stepped portions at at least two locations along its axial direction, and the planetary gears oscillate by rotating about the shaft center. The pair of gear carriers are disposed on both sides of the planetary gears along the axial direction and rotatably support the crankshaft. Lubrication passages for lubricant are formed between the stepped portions and the pair of gear carriers.

[0013] One aspect of the robot joint device disclosed herein includes: the internal meshing planetary gear assembly; a first member fixed to the gear body; 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.

[0014] [Effects of the Invention]

[0015] According to this disclosure, an internal meshing planetary gear device and a joint device for robots that can achieve improved lubrication conditions can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a perspective view showing the schematic structure of an actuator containing a basic internal meshing planetary gear mechanism.

[0017] 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.

[0018] Figure 3This is a schematic exploded perspective view of the aforementioned internal meshing planetary gear device viewed from the output side of the rotating shaft.

[0019] Figure 4 This is a schematic cross-sectional view of the aforementioned internal meshing planetary gear assembly.

[0020] Figure 5 This refers to the aforementioned internal meshing planetary gear mechanism. Figure 4 Sectional view along line A1-A1.

[0021] Figure 6 This refers to the aforementioned internal meshing planetary gear mechanism. Figure 4 Sectional view along line B1-B1.

[0022] Figure 7 This is a schematic cross-sectional view of the internal meshing planetary gear device of Embodiment 1.

[0023] Figure 8 This is a schematic diagram of the aforementioned internal meshing planetary gear device viewed from the output side of the rotating shaft.

[0024] Figure 9 This is a schematic perspective view showing the structure around the crankshaft of the aforementioned internal meshing planetary gear device.

[0025] Figure 10 This is a schematic exploded perspective view showing the structure around the crankshaft of the aforementioned internal meshing planetary gear device.

[0026] Figure 11 This is a schematic perspective view of the crankshaft representing the aforementioned internal meshing planetary gear system.

[0027] Figure 12 The main part of the aforementioned internal meshing planetary gear mechanism is... Figure 7 A rough enlarged view of region Z1.

[0028] Figure 13 The main part of the aforementioned internal meshing planetary gear mechanism is... Figure 7 A rough enlarged view of region Z2.

[0029] Figure 14 The main part of the aforementioned internal meshing planetary gear mechanism is... Figure 13 A rough enlarged view of region Z1.

[0030] Figure 15 This is a schematic diagram of a robot joint device that uses the aforementioned internal meshing planetary gear mechanism.

[0031] Figure 16 This is a schematic cross-sectional view of the internal meshing planetary gear device of Embodiment 2.

[0032] Figure 17The main part of the aforementioned internal meshing planetary gear mechanism is... Figure 16 A rough enlarged view of region Z1. DETAILED DESCRIPTION

[0033] (Basic Structure)

[0034] (1) Summary

[0035] The following is a summary of the internal meshing planetary gear device 1 of this basic structure, referring to... Figures 1 to 4 The accompanying drawings referenced in this disclosure are schematic diagrams, and the size and thickness ratios of the constituent elements shown may not necessarily reflect actual dimensions. For example, Figures 1 to 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 are not intended to limit the shape shown in the figure.

[0036] The internal meshing planetary gear device 1 (hereinafter also referred to as "gear device 1") of this basic structure is a gear device having an internal gear 2 and a planetary gear 3. In this gear device 1, the planetary gear 3 is arranged inside the annular internal gear 2, and the planetary gear 3 rotates relative to the internal gear 2 by oscillating. Furthermore, the internal meshing planetary gear device 1 also has a bearing member 6 having an outer gear 62 and an inner gear 61. The inner gear 61 is arranged inside the outer gear 62 and is supported relative to the outer gear 62 in a way that allows it to rotate. In particular, the gear device 1 of this basic structure is called a split-type eccentric oscillating internal meshing planetary gear device.

[0037] The gear device 1 of this basic structure is as follows: Figures 1 to 4 As shown, the gear assembly 1 includes multiple (three in the basic structure) crankshafts (eccentric shafts) 7A, 7B, and 7C positioned offset from the axis (rotation axis Ax1) of the internal gear 2. Furthermore, the gear assembly 1 includes an input shaft 500, positioned on the axis (rotation axis Ax1) of the internal gear 2 and centered on the rotation axis Ax1; and an input gear 501 integrally formed with the input shaft 500. Crankshaft gears 502A, 502B, and 502C are splinedly connected to the multiple crankshafts 7A, 7B, and 7C, respectively. These multiple (three in 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 via the input gear 501, thereby causing the planetary gear 3 to oscillate.

[0038] The internal gear 2 has internal teeth 21 and is fixed to the outer gear 62. Specifically, in this basic structure, the internal gear 2 has an annular gear body 22 and multiple outer pins 23. The multiple outer pins 23 are held in a rotatable state on the inner circumferential surface 221 of the gear body 22 and constitute the internal teeth 21. The planetary gear 3 has external teeth 31 that partially mesh with the internal teeth 21. That is, inside the internal gear 2, the planetary gear 3 is internally tangent to the internal gear 2, becoming part of the external teeth 31 meshing with a part of the internal teeth 21. In this state, when the multiple crankshafts 7A, 7B, and 7C are driven, the planetary gear 3 oscillates, and the meshing position of the internal teeth 21 and external teeth 31 moves 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 will rotate (self-rotate) along with the relative rotation of the two gears. As a result, the rotational output is reduced by a relatively high reduction ratio, corresponding to the difference in the number of teeth between the two gears, obtained from planetary gear 3.

[0039] This type of gear device 1 is used to transmit the rotation of the rotational component corresponding to the planetary gear 3 as the rotation of a pair of gear carriers 18 and 19 integrated with the inner wheel 61 of the bearing member 6. 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 gear carriers 18 and 19 as the output side. Therefore, in this basic structure of the gear device 1, in order to transmit the rotation of the rotational component corresponding to the planetary gear 3 to the pair of gear carriers 18 and 19, multiple crankshafts 7A, 7B, and 7C are supported by the pair of gear carriers 18 and 19. The pair of gear carriers 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, rotatably supporting each crankshaft 7A, 7B, and 7C.

[0040] 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 gear carriers 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. Therefore, the oscillation component of the planetary gear 3, i.e., the revolution component of the planetary gear 3, is absorbed by the revolution component of the eccentric portion 72 relative to the central shaft 71. In other words, the eccentric portion 72 of the central shaft 71 of each crankshaft 7A, 7B, and 7C rotates in a manner that revolves relative to the central shaft 71, thereby absorbing the oscillation component of the planetary gear 3. Therefore, through multiple crankshafts 7A, 7B, and 7C, the rotation (rotation component) of planetary gear 3, excluding the oscillating component (revolution component), is transmitted to a pair of gear carriers 18 and 19.

[0041] Furthermore, the gear device 1 of this basic structure, as shown... Figure 1 As shown, the actuator 100 is formed together with the drive source 101. In other words, the actuator 100 of this basic structure includes a gear assembly 1 and a drive source 101. The drive source 101 generates a driving force for oscillating the planetary gear 3. Specifically, the drive source 101 oscillates the planetary gear 3 by rotating the input shaft 500 around the rotation axis Ax1.

[0042] (2) Definition

[0043] The term "ring-shaped" as used in this disclosure refers to a circular shape that forms a space (region) enclosed on the inside when viewed from above, and is not limited to a perfect circle (ring-shaped) when viewed from above. For example, it can also be an elliptical shape or a polygonal shape. Furthermore, even a shape with a bottom, such as a cup shape, is included in "ring-shaped" as long as its peripheral walls are ring-shaped.

[0044] The term "revolution" as used in this disclosure refers to the rotation of an object around an axis other than the central axis passing through the object's center (center of gravity). When an object revolves, its center moves along a revolution path centered on the 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 will revolve around the eccentric axis. As an example, planetary gear 3 revolves within internal gear 2 by oscillating and rotating around the axis of rotation Ax1.

[0045] Furthermore, in this disclosure, sometimes 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 4The right side of the input is called the "input side". Figure 4 In the example, the input shaft 500 is rotated from the "input side" of the rotation shaft Ax1, and the rotation of a pair of gear carriers 18 and 19 is derived from the "output side" of the rotation shaft Ax1. However, "input side" and "output side" are merely labels for illustrative purposes and are not intended to define the positional relationship between the input and output as observed from the gear assembly 1.

[0046] The term "rotation axis" as used in this disclosure refers to an imaginary axis (line) that serves as the center of rotation of the rotating body. That is, rotation axis Ax1 is an imaginary axis without an accompanying entity. The input axis 500 rotates around rotation axis Ax1.

[0047] The terms "internal teeth" and "external teeth" as used in this disclosure do not refer to a single "tooth," but rather to a collection (group) of multiple "teeth." That is, the internal teeth 21 of the internal gear 2 comprise a collection of multiple teeth disposed on the inner circumferential surface 221 of the internal gear 2 (gear body 22). Similarly, the external teeth 31 of the planetary gear 3 comprise a collection of multiple teeth disposed on the outer circumferential surface of the planetary gear 3.

[0048] (3) Structure

[0049] The detailed structure of the internal meshing planetary gear device 1 of this basic structure is described below, referring to... Figures 1 to 6 Let me explain.

[0050] Figure 1 This is a perspective view showing the schematic structure of the actuator 100 including the gear mechanism 1. Figure 1 The diagram schematically represents driver source 101. Figure 2 This is a schematic exploded perspective view of the gear device 1 viewed 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. However, Figure 5 and Figure 6 In the diagram, for parts other than crankshafts 7A, 7B, and 7C, the shading lines are omitted even though it is a cross-section.

[0051] (3.1) Overall Structure

[0052] The gear device 1 of this basic structure is as follows: Figures 1 to 4As shown, the gear assembly 1 includes an internal gear 2, a planetary gear 3, a bearing assembly 6, multiple crankshafts 7A, 7B, and 7C, a pair of gear carriers 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 roller bearings 41 and 42, an eccentric 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 gear carriers 18 and 19, which are constituent 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 (including light metals) include metals that have undergone surface treatments such as nitriding.

[0053] Furthermore, in this basic structure, as an example of gear device 1, an internally tangent planetary gear device using a subcycloidal tooth profile is illustrated. That is, the gear device 1 of this basic structure includes an internally tangent planetary gear 3 having a subcycloidal curved tooth profile.

[0054] 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 wheel 62 of the bearing member 6 fixed together to a fixed member such as the housing 10. As a result, with the relative rotation of the internal gear 2 and the planetary gear 3, the planetary gear 3 will rotate relative to the fixed member (such as the housing 10).

[0055] Furthermore, in this basic structure, when the gear device 1 is used in the actuator 100, a rotational force is applied to the input shaft 500 as input, and a rotational force is derived as output from a pair of gear carriers 18, 19 integrated with the inner gear 61 of the bearing member 6. That is, the gear device 1 operates by taking the rotation of the input shaft 500 as input rotation and the rotation of the pair of gear carriers 18, 19 integrated with the inner gear 61 as output rotation. Thus, in the gear device 1, an output rotation that is decelerated relative to the input rotation at a relatively high reduction ratio is obtained.

[0056] The drive source 101 is a power source such as a motor (electric motor). The power generated by the drive source 101 is transmitted to the input shaft 500 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 enables the input shaft 500 to rotate.

[0057] Furthermore, in the gear device 1 of this basic structure, such as Figure 4As shown, the input-side rotation axis Ax1 and the output-side rotation axis Ax1 are located 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 gear 61 (and a pair of gear carriers 18, 19) that generate output rotation. That is, in the gear device 1, an output rotation that is rotated coaxially relative to the input and is decelerated at a relatively high reduction ratio will be obtained.

[0058] Internal gear 2, as shown Figure 5 and Figure 6 As shown, this is an annular part 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 the teeth constituting the internal teeth 21 are of the same shape and are equally pitched 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 in the direction of the rotation axis Ax1. The tooth lines of the internal teeth 21 are all parallel to the rotation axis Ax1. The dimension in the tooth line direction of the internal teeth 21 is slightly smaller than the thickness direction of the internal gear 2.

[0059] Here, as described above, the internal gear 2 has an annular (ring-shaped) gear body 22 and a plurality of outer pins 23. The plurality of outer pins 23 are held in a rotatable state on the inner circumferential surface 221 of the gear body 22 and constitute the internal teeth 21. In other words, the plurality of outer pins 23 function as a plurality of teeth constituting the internal teeth 21. Specifically, on the inner circumferential surface 221 of the gear body 22, as... Figure 2 As shown, multiple inner circumferential grooves 223 are formed over the entire circumferential region. All inner circumferential grooves 223 are of the same shape and are arranged at equal pitch. Each inner circumferential groove 223 is parallel to the rotation axis Ax1 and extends along the entire thickness of the gear body 22. Multiple outer pins 23 are attached to the gear body 22 by being inserted into the multiple inner circumferential grooves 223. Each outer pin 23 is held within its inner circumferential groove 223 in a rotatable state. Furthermore, the gear body 22 (along with the outer wheel 62) is fixed to the housing 10. Furthermore, multiple fixing holes 222 for fixing are formed in the gear body 22 (see reference). Figure 5 ).

[0060] Planetary Gear 3 Figure 5 and Figure 6As shown, this is an annular part with external teeth 31. In this basic structure, the planetary gear 3 has an annular shape, at least its outer circumferential surface being a perfect circle when viewed from above. External teeth 31 are formed on the outer circumferential surface of the annular planetary gear 3 along the circumferential direction of the planetary gear 3. All the teeth constituting the external teeth 31 are of the same shape and are provided at equal pitch 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. Moreover, the planetary gear 3 has a predetermined thickness in the direction of the rotation axis Ax1. The external teeth 31 are all formed along the entire length of the thickness direction of the planetary gear 3. The tooth lines of the external teeth 31 are all parallel to the rotation axis Ax1. In the planetary gear 3, unlike the internal gear 2, the external teeth 31 are integrally formed by a metal component that is one with the body of the planetary gear 3.

[0061] Furthermore, the gear assembly 1 of this basic structure includes multiple 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 facing each other in a direction parallel to the rotation axis Ax1. That is, the planetary gears 3 include a first planetary gear 301 and a second planetary gear 302 arranged in a direction (axial direction) parallel to the rotation axis Ax1. The first planetary gear 301 and the second planetary gear 302 have the same shape.

[0062] The two planetary gears 3 (the first planetary gear 301 and the 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 rotation axis 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 (biased) towards the top of the figure relative to the rotation axis Ax1. On the other hand, the output side located on the rotation axis Ax1 ( Figure 4 The center (center of the pitch circle of the external tooth 31) C2 of the second planetary gear 302 (on the left side) is offset (biased) 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.

[0063] In the first planetary gear 301 and the second planetary gear 302, their centers C1 and C2 are located at positions that are 180 degrees rotationally symmetrical with respect to the rotation axis Ax1. In this basic structure, the eccentricities ΔL1 and ΔL2 are viewed from the rotation axis Ax1 in opposite directions, but their absolute values ​​are the same.

[0064] More specifically, each crankshaft 7A, 7B, and 7C has two eccentric portions 72 relative to one central portion 71. The center C0 of these two eccentric portions 72 is eccentrically ΔL0 measured from the center of the central portion 71 (central portion Ax2) (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 multiple crankshafts 7A, 7B, and 7C are identical in shape. The multiple crankshaft gears 502A, 502B, and 502C are also identical in shape.

[0065] Furthermore, a pair of gear carriers 18 and 19 are arranged on both sides in a direction (axial direction) parallel to the rotation axis Ax1 of the first planetary gear 301 and the second planetary gear 302. With the pair of gear carriers 18 and 19 separated from each other, the input side located on the rotation axis Ax1 ( Figure 4 The gear carrier 18 (located on the right side) is called the "input-side gear carrier 18", which connects the output side of the rotating shaft Ax1 ( Figure 4 The gear carrier 19 (left side, in the middle) is called the "output side gear carrier 19". The two ends of each crankshaft 7A, 7B, 7C are held in a pair of gear carriers 18 and 19 via roller bearings 41 and 42. That is, each crankshaft 7A, 7B, 7C is held in a rotatable state on both sides of the input side gear carrier 18 and the output side gear carrier 19 in a direction (axial direction) parallel to the rotation axis Ax1 relative to the planetary gear 3.

[0066] An eccentric bearing 5 is installed in 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 in the first planetary gear 301 and the second planetary gear 302, respectively. The eccentric bearing 5 is housed in each opening 33. In other words, by installing the eccentric bearing 5 in the first planetary gear 301 and the second planetary gear 302, and by inserting each crankshaft 7A, 7B, and 7C into the eccentric bearing 5, the eccentric bearing 5 and each crankshaft 7A, 7B, and 7C are assembled into the planetary gear 3. With the eccentric bearing 5 and the crankshafts 7A, 7B, and 7C assembled into the planetary gear 3, when each crankshaft 7A, 7B, and 7C rotates, the planetary gear 3 oscillates around the rotation axis Ax1.

[0067] 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, thereby distributing this rotational force from the input gear 501 to multiple crankshafts 7A, 7B, and 7C. That is, when the input gear 501 rotates, the three crankshaft gears 502A, 502B, and 502C that mesh with the input gear 501 rotate in the same direction at the same speed. Since crankshafts 7A, 7B, and 7C are 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 decelerated by the gear ratio of the input gear 501 to the crankshaft gears 502A, 502B, and 502C. As a result, the three eccentric portions 72 at the same position on the input side of the rotating shaft Ax1 formed in the three crankshafts 7A, 7B, and 7C rotate synchronously, causing the first planetary gear 301 to oscillate. Furthermore, the three eccentric portions 72 at the same position on the output side of the rotating shaft Ax1 formed in the three crankshafts 7A, 7B, and 7C rotate synchronously, causing the second planetary gear 302 to oscillate.

[0068] Figure 5 and Figure 6 This indicates the state of the first planetary gear 301 and the second planetary gear 302 at a certain point in time. Figure 5 yes Figure 4 The sectional view along line A1-A1 shows the first planetary gear 301. Figure 6 yes Figure 4 The sectional view along line B1-B1 shows the second planetary gear 302. (See image.) Figure 5 and Figure 6 As shown, in the first planetary gear 301 and the second planetary gear 302, their centers C1 and C2 are located at positions approximately 180 degrees rotationally symmetrical with respect to the rotation axis Ax1. In this basic structure, the eccentricities ΔL1 and ΔL2 are in opposite directions when viewed from the rotation axis Ax1, but their absolute values ​​are approximately the same (both are eccentricities ΔL0). According to the structure described above, by rotating the shaft center 71 around the axis Ax2 (rotation), the first planetary gear 301 and the second planetary gear 302 rotate around the rotation axis Ax1 with an approximately 180-degree phase difference (eccentric motion). Furthermore, the multiple 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 multiple planetary gears 3.

[0069] 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. Here, external teeth 31 are formed on the outer circumferential surface of the planetary gear 3, and internal teeth 21 are formed on the inner circumferential surface of the internal gear 2. Therefore, with the planetary gear 3 positioned inside the internal gear 2, the external teeth 31 and the internal teeth 21 face each other.

[0070] 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 in the first planetary gear 301 is located at a position offset by a distance ΔL1 from the center of the pitch circle of the internal tooth 21 (rotation axis Ax1). Similarly, when the second planetary gear 302 is internally tangent to the internal gear 2, the center C2 of the pitch circle of the external tooth 31 in the second planetary gear 302 is located at a position offset by a distance ΔL2 from the center of the pitch circle of the internal tooth 21 (rotation axis Ax1).

[0071] Therefore, in either the first planetary gear 301 or the second planetary gear 302, the external teeth 31 and the internal teeth 21 face each other with at least a portion of a gap. If the difference in the number of teeth between the external teeth 31 and the internal teeth 21 is greater than "2", then the entire circumferential direction will not mesh with each other. However, the planetary gear 3 oscillates (revolves) around the rotation axis Ax1 inside the internal gear 2, so the external teeth 31 and the internal teeth 21 will partially mesh. That is, by the oscillation of the planetary gear 3 (the first planetary gear 301 and the second planetary gear 302) around the rotation axis Ax1, thus... Figure 5 and Figure 6 As shown, a portion of the teeth constituting the external tooth 31 will mesh with a portion of the teeth constituting the internal tooth 21. As a result, in the gear device 1, a portion of the external tooth 31 can mesh with a portion of the internal tooth 21.

[0072] 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 gear 31) is "2" less than the number of teeth of the internal gear 2 (internal gear 21). This difference in the number of teeth between the planetary gear 3 and the internal gear 2 defines the reduction ratio of the output rotation to the input rotation in the gear unit 1.

[0073] Furthermore, in this basic structure, as an example, the combined thickness of the first planetary gear 301 and the second planetary gear 302 is less than the thickness of the gear body 22 in the internal gear 2. Furthermore, the dimension of the tooth line 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 less than the dimension of the tooth line 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 converge within the tooth line range of the internal teeth 21.

[0074] Here, the first planetary gear 301 and the second planetary gear 302 are internally meshed with the internal gear 2. Therefore, each time the first planetary gear 301 and the second planetary gear 302 oscillate once, they will rotate relative to the internal gear 2 with a circumferential phase deviation corresponding to the difference in the number of teeth (between the internal teeth 21 and the external teeth 31). This rotation is transmitted to a pair of gear carriers 18 and 19 as the revolution of each crankshaft 7A, 7B, and 7C around the axis (rotation axis Ax1) of the internal gear 2. Thus, the pair of gear carriers 18 and 19 can rotate relative to the gear body (the housing 10 integrated with it) with respect to the rotation axis Ax1.

[0075] In summary, the gear assembly 1 of this basic structure uses multiple crankshafts 7A, 7B, and 7C, positioned offset from the rotation axis Ax1, to oscillate the planetary gear 3, thereby obtaining rotational output. Specifically, in the gear assembly 1, when 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, 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 (internal gear 2 and planetary gear 3). Here, if the internal gear 2 is fixed, the planetary gear 3 will rotate (spin) along with the relative rotation of the two gears. As a result, a rotational output with a relatively high reduction ratio corresponding to the difference in the number of teeth between the two gears is obtained from the planetary gear 3.

[0076] The bearing component 6 has an outer wheel 62 and an inner wheel 61, and is a part used to guide the output of the gear device 1 as the rotation of the inner wheel 61 relative to the outer wheel 62. In addition to the outer wheel 62 and the inner wheel 61, the bearing component 6 also has multiple rotating bodies 63 (see reference). Figure 4 Both the outer wheel 62 and the inner wheel 61 are annular parts. Both the outer wheel 62 and the inner wheel 61 are circular rings when viewed from above. The inner wheel 61 is smaller than the outer wheel 62 and is located inside the outer wheel 62. Here, because the inner diameter of the outer wheel 62 is larger than the outer diameter of the inner wheel 61, a gap is created between the inner circumferential surface of the outer wheel 62 and the outer circumferential surface of the inner wheel 61.

[0077] Multiple rotating bodies 63 are disposed within the gap between the outer wheel 62 and the inner wheel 61. The multiple rotating bodies 63 are arranged along the circumferential direction of the outer wheel 62. All of the multiple rotating bodies 63 are metal parts of the same shape and are disposed at equal pitch throughout the entire circumferential region of the outer wheel 62.

[0078] More specifically, in the gear assembly 1 of this basic structure, the bearing member 6 includes a first bearing member 601 and a second bearing member 602. The first bearing member 601 and the second bearing member 602 each include an angular contact ball bearing. Specifically, as... Figure 4 As shown, when viewed from planetary gear 3, this is the input side of the rotation axis Ax1 ( Figure 4 The first bearing member 601 is configured on the right side, which is the output side of the rotating shaft Ax1 when viewed from the planetary gear 3. Figure 4 The second bearing member 602 is arranged on the left side. The bearing member 6 is configured such that, with the help of the first bearing member 601 and the second bearing member 602, it can withstand loads in the radial direction, loads in the thrust direction (along the direction of the rotation axis Ax1), and bending forces (bending moment loads) relative to the rotation axis Ax1.

[0079] Here, the first bearing member 601 and the second bearing member 602 are arranged opposite to each other in the direction parallel to the rotation axis Ax1, relative to the planetary gear 3. That is, the bearing member 6 is a "combined angular contact ball bearing" composed of multiple (here, two) angular contact ball bearings. Here, as an example, the first bearing member 601 and the second bearing member 602 are "back-side combination type" bearing the load in the thrust direction (along the direction of the rotation axis Ax1) in which their respective inner gears 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 in which an appropriate preload is applied to the inner gears 61 by fastening them in the direction that brings their respective inner gears 61 closer to each other.

[0080] Furthermore, in the gear device 1 of this basic structure, the input-side gear carrier 18 and the output-side gear carrier 19 are arranged on both sides of the planetary gear 3 in a direction parallel to the rotation axis Ax1, and pass through the gear carrier hole 34 of the planetary gear 3 (see reference). Figure 4 ) combine with each other. Specifically, such as Figure 4 As shown, on the input side, which is the rotation axis Ax1 as viewed from planetary gear 3 ( Figure 4 The input-side gear carrier 18 is configured on the right side, while the output side, which is the rotation axis Ax1 as viewed from the planetary gear 3, is on the right side. Figure 4The output-side gear carrier 19 is configured on the left side. The inner wheel 61 of the bearing member 6 (each of the first bearing member 601 and the second bearing member 602) is fixed relative to the input-side gear carrier 18 and the output-side gear carrier 19. In this basic structure, as an example, the inner wheel of the first bearing member 601 is seamlessly integrated with the input-side gear carrier 18. Similarly, the inner wheel of the second bearing member 602 is seamlessly integrated with the output-side gear carrier 19.

[0081] The output-side gear carrier 19 has a plurality of (three in one example) gear carrier pins 191 (see reference) protruding from one surface of the output-side gear carrier 19 toward the input side of the rotation shaft Ax1. Figure 2 These multiple gear carrier pins 191 pass through multiple (three in one example) gear carrier holes 34 formed in the planetary gear 3, and their front ends are connected by gear carrier bolts 192 (see reference). Figure 7 It is fixed to the input side gear carrier 18. Here, a clearance is ensured between the gear carrier pin 191 and the inner circumferential surface of the gear carrier hole 34, allowing the gear carrier pin 191 to move within the gear carrier hole 34, that is, to move relative to the center of the gear carrier hole 34. Thus, when the planetary gear 3 oscillates, the gear carrier pin 191 will not contact the inner circumferential surface of the gear carrier hole 34.

[0082] With this structure, the gear mechanism 1 is used to derive the rotational component of the planetary gear 3 as the rotation of the input-side gear carrier 18 and the output-side gear carrier 19, which are integrated with the inner gear 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 derived from the input-side gear carrier 18 and the output-side gear carrier 19. In this basic structure, as an example, the gear mechanism 1 is located on the outer gear 62 of the bearing member 6 (refer to...). Figure 4 The planetary gear 3 is used while fixed to the housing 10, which serves as a fixed member. Specifically, the planetary gear 3 is connected to the input-side gear carrier 18 and the output-side gear carrier 19, which serve as rotating members, via multiple crankshafts 7A, 7B, and 7C. The gear body 22 is fixed to the fixed member, thus the relative rotation between the planetary gear 3 and the internal gear 2 is derived from the rotating members (input-side gear carrier 18 and output-side gear carrier 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 gear carrier 18 and the output-side gear carrier 19 is derived as an output.

[0083] 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 fixed member, is seamlessly continuous with the housing 10.

[0084] More specifically, the housing 10 is cylindrical, forming the outline 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 peripheral surface of the housing 10, when viewed from above (from one side of 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 ends in the axial direction. Here, the gear body 22 of the internal gear 2 is seamlessly integrated with the housing 10, and the housing 10 and the gear body 22 are treated as a single part. Therefore, the inner peripheral surface of the housing 10 includes the inner peripheral surface 221 of the gear body 22. Furthermore, the outer wheel 62 of the bearing member 6 is fixed to the housing 10. That is, the outer wheel 62 of the first bearing member 601 is fixed to the inner peripheral surface of the housing 10 by embedding, on the input side of the rotation axis Ax1 as viewed from the gear body 22. Figure 4 On the other hand, the outer wheel 62 of the second bearing member 602 is fixed to the output side of the rotation shaft Ax1 as viewed from the gear body 22 by being embedded in the inner circumferential surface of the housing 10. Figure 4 (Left side).

[0085] Furthermore, the input side of the rotating shaft Ax1 in the housing 10 ( Figure 4 The right side of the shaft is closed by the input-side gear carrier 18, and the output side of the rotating shaft Ax1 in the housing 10 is closed by the input-side gear carrier 18. Figure 4 The left end face is closed by the output side gear carrier 19. Therefore, as Figure 4 As shown, the space enclosed by the housing 10, the input side gear carrier 18 and the output side gear carrier 19 houses the planetary gear 3 (the first planetary gear 301 and the second planetary gear 302), multiple outer pins 23 and eccentric bearings 5, etc.

[0086] Multiple crankshafts 7A, 7B, and 7C (three in the basic structure) 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 a perfect circle when viewed from above. The center of the central shaft portion 71, i.e., the shaft center Ax2, is parallel to the rotation axis Ax1. The shaft centers Ax2 of the multiple crankshafts 7A, 7B, and 7C are arranged at equal intervals along the circumferential direction on an imaginary circle centered on the rotation axis Ax1. Each eccentric portion 72 is disk-shaped, with at least its outer circumferential surface being a perfect circle when viewed from above. The center (central axis) C0 of each eccentric portion 72 is positioned parallel to the rotation axis Ax1 and radially offset from it. Here, the distance ΔL0 between the shaft center Ax2 and the center C0 (refer to...) Figure 5 and Figure 6The eccentricity of the eccentric portion 72 relative to the central portion 71 is defined as the amount of eccentricity. The eccentric portion 72 is a flange shape that protrudes from the center of the central portion 71 along its long side (axial direction) and extends throughout the entire circumference of the outer peripheral surface of the central portion 71. According to the structure described above, each crankshaft 7A, 7B, and 7C rotates (self-rotates) around the central axis Ax2 via the central portion 71, thereby causing the eccentric portion 72 to undergo eccentric motion.

[0087] 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, along with the eccentric bearings 5, are assembled into the planetary gear 3. Therefore, with the eccentric bearings 5 ​​and the crankshafts 7A, 7B, and 7C assembled into the planetary gear 3, when the crankshafts 7A, 7B, and 7C rotate, the planetary gear 3 oscillates around the rotation axis Ax1.

[0088] The eccentric bearing 5 has multiple rotating bodies 51 (see reference). Figure 4 The planetary gear 3 is a component used to absorb the rotational component of the crankshafts 7A, 7B, and 7C and transmit only the rotational component of the crankshafts 7A, 7B, and 7C, i.e., the oscillating component (revolutionary component), to the planetary gear 3. Multiple rotating bodies 51 are arranged between the outer peripheral surface of the eccentric portion 72 of each crankshaft 7A, 7B, and 7C and the inner peripheral surface of each opening 33 of the planetary gear 3. That is, the eccentric portion 72 of each crankshaft 7A, 7B, and 7C functions as the inner wheel of the eccentric bearing 5, and the inner peripheral surface of each opening 33 of the planetary gear 3 functions as the outer wheel of the eccentric bearing 5.

[0089] With the eccentric bearing 5 and multiple crankshafts 7A, 7B, and 7C assembled into the planetary gear 3, when each crankshaft 7A, 7B, and 7C rotates, the eccentric bearing 5 rotates around its axis Ax2 (eccentric motion). At this time, the rotational components of crankshafts 7A, 7B, and 7C are absorbed by the eccentric bearing 5. Therefore, only the rotational components of crankshafts 7A, 7B, and 7C other than their rotational components—that is, the oscillating components (revolutionary components)—are transmitted to the planetary gear 3 through the eccentric bearing 5. Thus, with the eccentric bearing 5 and crankshafts 7A, 7B, and 7C assembled into the planetary gear 3, when crankshafts 7A, 7B, and 7C rotate, the planetary gear 3 oscillates around its axis of rotation Ax1.

[0090] In the gear assembly 1 of the described structure, a rotational force is applied to the input shaft 500 as input, causing the input shaft 500 to rotate around the rotation axis Ax1. As a result, the planetary gear 3 oscillates (revolves) around the rotation axis Ax1. At this time, the planetary gear 3 oscillates internally relative to the internal gear 2, with a portion of its external teeth 31 meshing with a portion 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. This generates a relative rotation between the two gears (internal gear 2 and planetary gear 3) corresponding to the difference in the number of teeth between the planetary gear 3 and the internal gear 2. Furthermore, the rotation (rotational component) of the planetary gear 3, excluding the oscillation component (revolutionary component), is transmitted to a pair of gear carriers 18 and 19 via multiple crankshafts 7A, 7B, and 7C. As a result, a rotational output with a relatively high reduction ratio corresponding to the difference in the number of teeth between the two gears is obtained from the pair of gear carriers 18 and 19.

[0091] Furthermore, in the gear device 1 of this basic structure, as described above, the difference in the number of teeth between the internal gear 2 and the planetary gear 3 defines the reduction ratio of the output rotation relative to the input rotation in the gear device 1. That is, when the number of teeth of the internal gear 2 is "V1" and the number of teeth of the planetary gear 3 is "V2", the reduction ratio R1 is expressed by the following formula 1.

[0092] R1=V2 / (V1-V2) (Formula 1)

[0093] In summary, the smaller the difference in the number of teeth (V1-V2) between the internal gear 2 and the planetary gear 3, the larger the reduction ratio R1. For example, the number of teeth V1 of the internal gear 2 is "72", and the number of teeth V2 of the planetary gear 3 is "70", with a difference in the number of teeth (V1-V2) of "2". Therefore, according to Equation 1, the reduction ratio R1 is "35". At this time, when viewed from the input side of the rotating shaft Ax1, each crankshaft 7A, 7B, and 7C has its axis 71 centered at axis Ax2 (refer to...). Figure 5 and Figure 6 When the gear carriers 18 and 19 rotate clockwise for one revolution (360 degrees) around the center, they rotate counterclockwise around the rotation axis Ax1 by an amount corresponding to the tooth difference "2" (i.e., about 10.3 degrees).

[0094] According to the gear assembly 1 of this basic structure, such a high reduction ratio R1 can be achieved using a combination of internal gear 2 and planetary gear 3. Furthermore, between the input gear 501 and the plurality of crankshaft gears 502A, 502B, and 502C, an appropriate reduction ratio can also be achieved corresponding to 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.

[0095] Furthermore, gear assembly 1 only needs to include at least internal gear 2, planetary gear 3, crankshafts 7A, 7B, 7C, and a pair of gear carriers 18, 19; for example, it can also be as follows: Figure 4 The diagram further shows that a spacer 11 is provided. The spacer 11 is arranged in a direction (axial direction) parallel to the rotation axis Ax1 between a pair of planetary gears 3 (first planetary gear 301 and second planetary gear 302).

[0096] (Implementation Method 1)

[0097] The internal meshing planetary gear device 1A (hereinafter also referred to as "gear device 1A") of this embodiment is as follows: Figures 7-14 As shown, the structures around the main crankshafts 7A, 7B, and 7C differ from the gear assembly 1 in the basic structure. Hereinafter, structures identical to the basic structure will be labeled with the same symbols and descriptions will be omitted as appropriate. Figure 7 This is a schematic cross-sectional view of gear assembly 1A. Figure 8 This is a schematic diagram of the gear assembly 1A viewed from the output side of the rotating shaft Ax1. Figure 9 It is a schematic three-dimensional view of the peripheral components of a crankshaft 7A. Figure 10 It is a schematic exploded perspective view of the peripheral components of a crankshaft 7A. Figure 11 It is a schematic three-dimensional diagram of a crankshaft 7A. Figure 12 yes Figure 7 A magnified view of region Z1. Figure 13 yes Figure 7 A magnified view of region Z2. Figure 14 yes Figure 13 A magnified view of region Z1.

[0098] The gear device 1A of this embodiment is as follows: Figure 7 As shown, it also includes multiple oil seals 121, 122, etc. Oil seal 121 seals the gap between the housing 10 and the outer peripheral surface of the output-side gear carrier 19. Oil seal 122 seals the central hole 193 formed in the central part of the output-side gear carrier 19. The space sealed by these multiple oil seals 121, 122, etc. constitutes a lubricant retention space 17. The lubricant retention space 17 includes the space between the inner wheel 61 and the outer wheel 62 of the bearing member 6. Furthermore, multiple outer pins 23, planetary gears 3, a pair of roller bearings 41, 42, and an eccentric bearing 5 are housed within the lubricant retention space 17.

[0099] Furthermore, lubricant is injected into the lubricant holding space 17. The lubricant is liquid and can flow within the lubricant holding space 17. Therefore, when the gear device 1 is in use, the lubricant enters, for example, the meshing part of the internal teeth 21, which includes a plurality of external pins 23, and the external teeth 31 of the planetary gear 3. The term "liquid" as used in this disclosure includes liquid or gel-like substances. The term "gel-like" as used here refers to a state having intermediate properties between liquid and solid, including a colloid state containing both a liquid phase and a solid phase. For example, states such as emulsions where the dispersant is a liquid phase and the dispersion is a liquid phase, and suspensions where the dispersion is a solid phase, are referred to as gels or sols and are included in the term "gel-like". Moreover, states where the dispersant is a solid phase and the dispersion is a liquid phase are also included in the term "gel-like". In this basic structure, as an example, the lubricant is a liquid lubricating oil.

[0100] The gear device 1A of this embodiment also includes a pair of covers 13, 14 mounted on both axial sides of a pair of gear carriers 18, 19. With the pair of covers 13, 14 separated from each other, the input side located on the rotation shaft Ax1 ( Figure 7 The cover 13 (right side in the middle) is called the "input side cover 13", which is located on the output side of the rotating axis Ax1. Figure 7 The cover 14 (left side, in the middle) is called the "output side cover 14". In this embodiment, the material of the pair of covers 13 and 14 is stainless steel, cast iron, carbon steel or chromium-molybdenum steel for mechanical structures, or metals that have undergone heat treatment.

[0101] The input side cover 13 is formed in the shape of a disk centered on the rotation axis Ax1. Here, at least the outer peripheral surface of the input side cover 13 is a perfect circle centered on the rotation axis Ax1 when viewed from above (from one side along the axial direction). The outer diameter of the input side cover 13 is smaller than the outer diameter of the input side gear carrier 18. The input side cover 13 is on the opposite side to the planetary gear 3 when viewed from the outside, i.e., from the input side gear carrier 18. Figure 7 (The middle one is on the right) is installed on the input side gear carrier 18.

[0102] The output side cover 14 is formed in the shape of a disk centered on the rotation axis Ax1. Here, at least the outer peripheral surface of the output side cover 14 is a perfect circle centered on the rotation axis Ax1 when viewed from above (from one side along the axial direction). The outer diameter of the output side cover 14 is smaller than the outer diameter of the output side gear carrier 19. The output side cover 14 is on the opposite side to the planetary gear 3 when viewed from the outside, i.e., from the output side gear carrier 19. Figure 7 (The middle one is on the left) is installed on the output side gear carrier 19.

[0103] Here, a pair of covers 13 and 14 are detachably mounted to a pair of gear carriers 18 and 19. That is, the input-side cover 13 is detachably mounted to the input-side gear carrier 18, and the output-side cover 14 is detachably mounted to the output-side gear carrier 19. In this embodiment, as an example, each cover 13 and 14 is secured by multiple fixing bolts 142 (see reference). Figure 8 The covers 13 and 14 are installed on each gear carrier 18 and 19. Therefore, each cover 13 and 14 can be removed from each gear carrier 18 and 19 by removing multiple fixing bolts 142.

[0104] Here, in the output side cover 14 of the pair of covers 13, 14, as Figure 8 As shown, there are multiple mounting holes 194 provided on the output side gear carrier 19 (refer to...). Figure 7 A plurality of through holes 141 are provided. That is, the output-side gear carrier 19 has a plurality of mounting holes 194 (female threads) for fixing the target component. Therefore, in the output-side cover 14 which is mounted on the outside of the output-side gear carrier 19, a plurality of through holes 141 are also formed at positions corresponding to these plurality of mounting holes 194. In particular, when high torque is transmitted from the output-side gear carrier 19 to the target component, the number of mounting holes 194 and through holes 141 increases. Moreover, the arrangement and number of mounting holes 194 and through holes 141 must be consistent with the target component.

[0105] On the other hand, the shaft holes 131 through which each crankshaft 7A, 7B, and 7C passes (see reference) Figure 7 The input side cover 13 is provided only in one of the pair of covers 13 and 14. That is, multiple shaft holes 131 are provided in the input side cover 13, corresponding to the multiple crankshafts 7A, 7B, and 7C. The shaft center portion 71 of each crankshaft 7A, 7B, and 7C is inserted into the respective shaft hole 131. Here, the inner diameter of each shaft hole 131 is set to be one size larger than the outer diameter of the shaft center portion 71, so as to prevent the shaft center portion 71 from contacting the inner circumferential surface of the shaft hole 131.

[0106] Furthermore, regarding the peripheral structures of each crankshaft 7A, 7B, and 7C, if further detailed explanation is provided, the gear device 1A of this embodiment employs... Figures 9-11 The structure is shown below. Here, crankshaft 7A is used as an example for explanation, but the same structure is used for crankshafts 7B and 7C.

[0107] That is, the crankshaft 7A has a flange 73 between two eccentric portions 72 along the axial direction of the shaft center Ax2. The flange 73 is disc-shaped centered on the shaft center Ax2, and at least its outer peripheral surface is a perfect circle when viewed from above. The outer diameter of the flange 73 is set to be one size larger than the outer diameter of the eccentric portions 72, and the flange 73 has a flange shape that protrudes from the outer peripheral surface of the eccentric portions 72 throughout the entire circumference. In this embodiment, as an example, the shaft center 71, the two eccentric portions 72, and the flange 73 are seamlessly integrated.

[0108] Here, the crankshaft 7A has two eccentric portions 72 relative to one central portion 71, thus having stepped portions 70 at at least two locations along the axial direction. That is, the diameter of the crankshaft 7A is not uniform throughout its entire length; the diameter changes at least between the central portion 71 and each eccentric portion 72, thus creating two stepped portions 70 in this section. In other words, the end faces of each eccentric portion 72 facing outward along the axial direction (i.e., opposite to the flange portion 73) are stepped portions 70.

[0109] In this embodiment, the diameter of the central portion 71 of the crankshaft 7A at both ends in the axial direction is smaller than that at the central portion in the axial direction. Therefore, step portions 70 are also generated at the locations where the diameter of the central portion 71 changes. As a result, the crankshaft 7A has step portions 70 at four locations in the axial direction. Here, when distinguishing each step portion 70, from the input side of the rotating shaft Ax1 ( Figure 7 Starting from the right side (center), the components are sequentially designated as the first-order differential section 701, the second-order differential section 702, the third-order differential section 703, and the fourth-order differential section 704. Specifically, the first-order differential section 701 and the second-order differential section 702 are end faces facing the input side of the rotating shaft Ax1, while the third-order differential section 703 and the fourth-order differential section 704 are end faces facing the output side of the rotating shaft Ax1. The end portion of the shaft core 71 that is closer to the input side of the rotating shaft Ax1 than the first-order differential section 701 constitutes a mounting portion 74 for mounting the crankshaft gear 502A.

[0110] A pair of roller bearings 41 and 42, a pair of eccentric bearings 5, washers 81 to 85, and a retaining ring 86 are assembled into this crankshaft 7A. Specifically, eccentric bearings 5 ​​are installed on each of the two eccentric portions 72 of the crankshaft 7A. Furthermore, a pair of roller bearings 41 and 42 are installed on either side of the two eccentric portions 72 in the axial direction of the crankshaft 7A's central portion 71. Moreover, on the output side of the crankshaft 7A's central portion 71, which is closer to the rotating shaft Ax1 than the fourth differential portion 704 (… Figure 7 The left end of the shaft (center) has a groove 75 for inserting the retaining ring 86. Therefore, the retaining ring 86 is installed at the output end of the rotating shaft Ax1 in the shaft center 71.

[0111] Here, on the input side of the rotation axis Ax1 as viewed from the flange portion 73 ( Figure 7 (The middle section is on the right side), with washer 81, eccentric bearing 5, washer 82, and roller bearing 41 installed in sequence from the flange 73 side. On the other hand, on the output side of the rotating shaft Ax1 as viewed from the flange 73 (…),… Figure 7(From left to right) Washers 83, eccentric bearing 5, 84, roller bearing 42, 85, and retaining ring 86 are installed in sequence from the flange 73 side. Therefore, on the input side of the rotating shaft Ax1 as viewed from the flange 73, washer 81 is positioned between the flange 73 and the eccentric bearing 5, and washer 82 is positioned between the eccentric bearing 5 and the roller bearing 41. On the output side of the rotating shaft Ax1 as viewed from the flange 73, washer 83 is positioned between the flange 73 and the eccentric bearing 5, and washer 84 is positioned between the eccentric bearing 5 and the roller bearing 42. Furthermore, the roller bearing 42 contacts the retaining ring 86 via washer 85, thereby restricting its movement toward the output side of the rotating shaft Ax1.

[0112] More specifically, the eccentric portion 72 is inserted into washers 81 and 83, respectively, and the axial portion 71 is inserted into washers 82 and 84, respectively. Here, washer 82 is positioned between the second differential portion 702 of crankshaft 7A and roller bearing 41. On the other hand, washer 84 is positioned between the third differential portion 703 of crankshaft 7A and roller bearing 42. Furthermore, washer 85 is positioned between the fourth differential portion 704 of crankshaft 7A and retaining ring 86. These washers 81 to 85 are, for example, made of metal and function as track wheels (track discs) to reduce friction between the two components.

[0113] Furthermore, the gear device 1A of this embodiment is as follows: Figure 12 As shown, a limiting structure 9 is provided to restrict the axial movement of each crankshaft 7A, 7B, and 7C. That is, in the gear device 1A of this embodiment, the limiting structure 9 restricts the axial movement of the crankshafts 7A, 7B, and 7C. In this disclosure, "axial" refers to the direction along the axis Ax2 of the crankshafts 7A, 7B, and 7C, especially the direction parallel to the axis Ax2 of the crankshafts 7A, 7B, and 7C (thrust direction). Furthermore, in this disclosure, "restricting movement" means imposing certain restrictions on movement, including not only completely prohibiting movement but also limiting the range of movement or making it difficult to move. That is, in this embodiment, the limiting structure 9 is provided, thereby restricting the movement of the crankshafts 7A, 7B, and 7C in the axial direction along the axis Ax2 of the crankshafts 7A, 7B, and 7C.

[0114] In this embodiment, as an example, the movement of crankshafts 7A, 7B, and 7C is prohibited on both sides of the axial direction of the restriction structure 9, namely, on one side (the input side of the rotation shaft Ax1) and the other side (the output side of the rotation shaft Ax1). That is, in Figure 8 In the example, the limiting structure prohibits movement of crankshafts 7A, 7B, and 7C to the right and to the left of the figure relative to a pair of gear carriers 18 and 19. Thus, the axial positions of crankshafts 7A, 7B, and 7C (relative to the pair of gear carriers 18 and 19) are fixed.

[0115] Specifically, in this embodiment, the limiting structure 9 includes a pair of covers 13 and 14 mounted on both axial sides of a pair of gear carriers 18 and 19. In summary, the gear assembly 1A uses the aforementioned input-side cover 13 and output-side cover 14 to limit the axial movement of each crankshaft 7A, 7B, and 7C. In particular, the gear assembly 1A of this embodiment includes features that limit the crankshafts 7A, 7B, and 7C to one side of the axial direction (…). Figure 8 The first limiting structure 91 (center to right) restricts the movement of crankshafts 7A, 7B, and 7C to the other side of the axial direction. Figure 8 The second constraint structure 92 (left side) is used as constraint structure 9 to move.

[0116] Here, the input side cover 13 is included in the first limiting structure 91, by bearing the axial force from the crankshafts 7A, 7B, 7C toward one side ( Figure 8 The force F1 acting on the right side (center to right) restricts the movement of crankshafts 7A, 7B, and 7C toward one side of the axial direction. On the other hand, the output side cover 14, included in the second limiting structure 92, withstands the force F1 acting on the right side (center to right) of the crankshafts 7A, 7B, and 7C, thereby restricting their movement toward the other side of the axial direction (center to right). Figure 8 The force F2 acting on the left side restricts the movement of crankshafts 7A, 7B, and 7C toward the other side of the axial direction.

[0117] More specifically, the first limiting structure 91 includes a first-order difference 701 between the input side cover 13 and the crankshafts 7A, 7B, 7C. According to this first limiting structure 91, the input side of the crankshafts 7A, 7B, 7C facing the rotation axis Ax1 (… Figure 8 The first-order differential section 701 (right side) contacts the output side of the input side cover 13 facing the rotation axis Ax1. Figure 8 Around the shaft hole 131 on the surface (left side), the crankshafts 7A, 7B, and 7C are axially oriented towards one side ( Figure 8 The movement of the crankshafts 7A, 7B, and 7C (to the right) is restricted. Specifically, the first differential portion 701 of the crankshafts 7A, 7B, and 7C contacts the input side cover 13 mounted on the input side gear carrier 18, thereby prohibiting the axial movement of the crankshafts 7A, 7B, and 7C to one side.

[0118] The second limiting structure 92 includes the output side cover 14 and the output side end face 76 of the rotation shaft Ax1 of the crankshafts 7A, 7B, and 7C. According to this second limiting structure 92, the output side of the crankshafts 7A, 7B, and 7C facing the rotation shaft Ax1 ( Figure 8 The end face 76 (left side) contacts the input side of the output side cover 14 facing the rotation axis Ax1. Figure 8 The middle section is the right side, thus, crankshafts 7A, 7B, and 7C face the other side of the axial direction ( Figure 8The movement of the crankshafts (7A, 7B, 7C to the left) is restricted. That is, the end faces 76 of the crankshafts 7A, 7B, 7C contact the output side cover 14 mounted on the output side gear carrier 19, thereby prohibiting the movement of the crankshafts 7A, 7B, 7C to the other side of the axial direction.

[0119] Here, in the limiting structure 9, the parts of the crankshafts 7A, 7B, and 7C that come into contact with the pair of covers 13 and 14 are those other than the end faces (second step difference portion 702 and third step difference portion 703) of the eccentric portion 72. That is, the limiting structure 9 is located further outward in the axial direction than the step difference portions 702 and 703 of the crankshafts 7A, 7B, and 7C that include the end faces of the eccentric portion 72, and restricts the axial movement of the crankshafts 7A, 7B, and 7C by contacting the end faces (first step difference portion 701 or end face 76) facing outward in the axial direction. Therefore, friction is not generated in the step difference portions 702 and 703 that include the end faces of the eccentric portion 72 due to contact with the pair of covers 13 and 14, etc., and wear on the step difference portions 702 and 703 can be reduced.

[0120] Furthermore, the gear device 1A of this embodiment includes an internal gear 2, a planetary gear 3, crankshafts 7A, 7B, and 7C, and a pair of gear carriers 18 and 19. By oscillating the planetary gear 3, the planetary gear 3 rotates relative to the internal gear 2. The internal gear 2 has an annular gear body 22 and a plurality of outer pins 23, which 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 and constitute internal teeth 21. The planetary gear 3 has outer teeth 31 that partially mesh with the internal teeth 21. The crankshafts 7A, 7B, and 7C have stepped portions 70 at at least two locations along the axial direction of the axis Ax2, and the planetary gear 3 oscillates by rotating about the axis Ax2. A pair of gear carriers 18 and 19 are arranged on both sides of the planetary gear 3 in the axial direction and rotatably support the crankshafts 7A, 7B, and 7C. Here, as Figure 13 As shown, lubrication passages S1 for lubricant to pass through are formed between the step portion 70 and a pair of gear carriers 18 and 19.

[0121] That is, in this embodiment, a lubrication passage S1 is ensured between the step portion 70 and the pair of gear carriers 18, 19. By ensuring this lubrication passage S1, lubricant can circulate through the lubrication passage S1 in the gear assembly 1A, thereby improving the lubrication condition of the pair of roller bearings 41, 42 and the pair of eccentric bearings 5. Figure 13 In the diagram, the dashed arrows conceptually represent the flow (circulation) of lubricant in the lubrication passage S1.

[0122] In this embodiment, the lubrication passage S1 is formed within the lubricant holding space 17 where the injected lubricant is stored. By forming this lubrication passage S1, it is difficult for "lubricant shortage" or "lubricant depletion" to occur around the crankshafts 7A, 7B, and 7C, thereby ensuring a constant supply of a certain amount of lubricant. Furthermore, compared to a structure where the lubricant remains in a fixed position, the lubricant circulates through the lubrication passage S1, thus allowing for continuous lubricant replacement around the crankshafts 7A, 7B, and 7C, thereby suppressing lubricant deterioration.

[0123] Therefore, the lubrication of the pair of roller bearings 41 and 42 and the pair of eccentric bearings 5 ​​is improved, making it difficult for poor lubrication to occur. Thus, even with long-term use of the gear assembly 1A, losses due to friction can be reduced, easily extending the lifespan of the gear assembly 1A. In summary, the gear assembly 1A of this embodiment is particularly unlikely to experience a decline in reliability during long-term use, and therefore also contributes to improving the transmission efficiency, extending the lifespan, and increasing the performance of the gear assembly 1A.

[0124] Here, in this embodiment, the lubrication passage S1 includes a radial passage S11 through which the lubricant passes in a radial direction orthogonal to the axial direction. That is, as shown in the example... Figure 13 A rough enlarged view of region Z1 Figure 14 As shown, the lubrication passage S1 formed between the step portion 70 and the pair of gear carriers 18, 19 includes at least a radial passage S11 through which the lubricant passes radially. Thus, when the crankshafts 7A, 7B, 7C rotate, the lubricant passes radially by centrifugal force, thereby enabling efficient circulation of the lubricant through the lubrication passage S1.

[0125] Furthermore, in this embodiment, in the axial direction, there is a gap between the step portions 702, 703 and at least one of the gear carriers 18, 19, and the lubrication passage S1 includes said gap. In this embodiment, as described above, the step portions 702, 703, which at least include the end face of the eccentric portion 72, are not used as the limiting structure 9. Therefore, a gap can be provided between the step portions 702, 703 and the pair of gear carriers 18, 19, and this gap can be part of the lubrication passage S1. In this embodiment, as an example, the gaps generated between the step portions 702, 703 and the pair of gear carriers 18, 19 respectively constitute part of the lubrication passage S1.

[0126] Furthermore, in this embodiment, a plate-shaped component (washers 82, 84) is disposed between the step portion 70 and a pair of gear carriers 18, 19. The lubrication passage S1 includes a groove 80 formed in the plate-shaped component (washers 82, 84) on the facing surface of the gear carriers 18, 19 (see reference). Figure 10 That is, such as Figure 10As shown, in washers 81-84, radially extending grooves 80 are formed on the surface facing axially outward (towards gear carriers 18 and 19). Preferably, multiple grooves 80 are formed for each washer 81-84; in this embodiment, as an example, four grooves 80 are formed for each washer 81-84. The four grooves 80 are equally spaced in the circumferential direction of each washer 81-84. By providing these grooves 80, lubricant flows through the grooves 80, which are contained within the lubrication passage S1. As a result, compared to the case without grooves 80, the cross-sectional area of ​​the lubrication passage S1 can be increased, making lubricant circulation easier.

[0127] Furthermore, in the case where multiple crankshafts 7A, 7B, and 7C are provided as in this embodiment, it is preferable to provide a connecting passage S2 that connects the multiple lubrication passages S1 formed around the periphery of these multiple crankshafts 7A, 7B, and 7C respectively. This allows lubricant to circulate among the multiple crankshafts 7A, 7B, and 7C, thereby circulating the lubricant throughout the entire gear assembly 1A, and thus further improvement in lubrication conditions can be expected.

[0128] Specifically, such as Figure 7 As shown, in each of the pair of covers 13 and 14, grooves 133 and 143 are formed on the surface facing the axially inward side (the surface facing the planetary gear 3). Grooves 133 and 143 are annular grooves centered on the rotating shaft Ax1, formed in a top view to allow the roller bearings 41 and 42 supporting multiple crankshafts 7A, 7B, and 7C to pass through (see reference). Figure 8 Therefore, the lubrication passage S1 containing multiple (here, 3) roller bearings 41 is connected by a connecting passage S2 containing a groove 133 of the input side cover 13. Similarly, the lubrication passage S1 containing multiple (here, 3) roller bearings 42 is connected by a connecting passage S2 containing a groove 143 of the output side cover 14.

[0129] Furthermore, the gear device 1A of this embodiment includes an input gear 501 that rotates around a rotation axis Ax1 and a plurality of crankshaft gears 502A, 502B, and 502C. The plurality of crankshaft gears 502A, 502B, and 502C are arranged around the input gear 501 in a manner that meshes with it, and rotate synchronously with each other when the input gear 501 rotates. Multiple crankshafts 7A, 7B, and 7C are provided in a manner that corresponds one-to-one with the plurality of crankshaft gears 502A, 502B, and 502C. The plurality of crankshafts 7A, 7B, and 7C rotate together with the plurality of crankshaft gears 502A, 502B, and 502C, causing the planetary gear 3 to oscillate around the rotation axis Ax1.

[0130] In this way, in the separate gear device 1A having multiple crankshafts 7A, 7B, and 7C, the axial movement of the multiple crankshafts 7A, 7B, and 7C can be restricted. Furthermore, by circulating lubricant around the multiple crankshafts 7A, 7B, and 7C, the lubrication condition can be improved.

[0131] The gear device 1A of this embodiment is as follows: Figure 15 As shown, the first component 201 and the second component 202 together constitute a robot joint device 200. In other words, the robot joint device 200 of this embodiment includes a gear device 1A, a first component 201, and a second component 202. The first component 201 is fixed to the gear body 22. The second component 202 rotates relative to the first component 201 as the planetary gear 3 rotates relative to the internal gear 2. Figure 15 This is a schematic cross-sectional view of a robot articulation device 200. Furthermore, Figure 15 The diagram schematically illustrates the first component 201, the second component 202, and the driving source 101.

[0132] The robot configured in this way functions as a joint device by having a first member 201 and a second member 202 rotate relative to each other around a 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 using a drive source 101. At this time, the rotation generated by the drive source 101 (input rotation) is slowed down in the gear device 1A with a relatively high reduction ratio, thereby driving the first member 201 or the second member 202 with 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.

[0133] The robot joint device 200 is used, for example, in robots such as horizontal articulated robots (SCARA type robots). Furthermore, the robot joint device 200 is not limited to horizontal articulated robots; for example, it can also be used in industrial robots or robots other than horizontal articulated robots. Moreover, the gear device 1A of this embodiment is not limited to the robot joint device 200; for example, it can also be used as a wheel device such as an in-wheel motor in vehicles such as Automated Guided Vehicles (AGVs).

[0134] <Variation Example>

[0135] Embodiment 1 is merely one of the various embodiments of this disclosure. Embodiment 1 can be modified in various ways, such as by design, to achieve the purpose of this disclosure. Furthermore, the accompanying drawings referenced in this disclosure are schematic diagrams, and the size and thickness ratios of the constituent elements shown may not necessarily reflect actual dimensional ratios. The following are examples of variations of Embodiment 1. The variations described below can be appropriately combined and applied.

[0136] The number of crankshafts 7A, 7B, and 7C is not limited to "3" and can also be 2 or more. Furthermore, if there is only one crankshaft, an eccentric oscillating type internal meshing planetary gear device can be realized, where the rotating shaft Ax1 is aligned with the crankshaft axis Ax2, rather than a separate type. In this case, by driving the crankshaft, the planetary gear 3 oscillates, thereby enabling a pair of gear carriers 18 and 19 to rotate relative to the gear body 22 with the rotating shaft Ax1 as the center.

[0137] Furthermore, in Embodiment 1, a gear device 1A with two planetary gears 3 is illustrated, but the gear device 1A may also have three or more planetary gears 3. For example, when the gear device 1A has three planetary gears 3, it is preferable that these three planetary gears 3 are arranged around the rotation axis Ax1 with a phase difference of 120 degrees. Moreover, the gear device 1A may also have only one planetary gear 3. Alternatively, when the gear device 1A has three planetary gears 3, two of the three planetary gears 3 may be in phase, and the remaining one planetary gear 3 may be arranged around the rotation axis Ax1 with a phase difference of 180 degrees.

[0138] Furthermore, bearing component 6 can also be a crossed roller bearing, a deep groove ball bearing, or a four-point contact ball bearing, etc.

[0139] Furthermore, the number of teeth of the input gear 501, the number of teeth of the crankshaft gears 502A, 502B, and 502C, the number of outer pins 23 (the number of teeth of the inner teeth 21), and the number of teeth of the outer teeth 31 described in Embodiment 1 are just one example and can be changed appropriately.

[0140] Furthermore, the eccentric bearing 5 is not limited to roller bearings; for example, it can also be a deep groove ball bearing or an angular contact ball bearing.

[0141] Furthermore, the materials of the components of the gear device 1A are not limited to metal; for example, they can also be resins such as engineering plastics.

[0142] Furthermore, the gear device 1A is only required to output the relative rotation between the inner wheel 61 and the outer wheel 62 of the bearing member 6, and is not limited to outputting the rotational force of the inner wheel 61 (input-side gear carrier 18 and output-side gear carrier 19). For example, the rotational force of the outer wheel 62 (housing 10) that rotates relative to the inner wheel 61 may also be output.

[0143] Furthermore, in Embodiment 1, the output side end face 76 of the rotating shaft Ax1 of crankshafts 7A, 7B, and 7C directly contacts the output side cover 14. However, this structure is not limited to this; a plate-shaped part, such as a gasket member, may also be arranged between the end face 76 and the output side cover 14. In this case, when installing the output side cover 14, the gap between the end face 76 and the output side cover 14 can be adjusted axially by adjusting the thickness (and / or number of plates) of the plate-shaped part, thereby adjusting the axial "clearance" of crankshafts 7A, 7B, and 7C. Furthermore, the plate-shaped part functions as a track wheel (track disc) to reduce friction between the end face 76 and the output side cover 14.

[0144] Moreover, lubricants are not limited to liquid substances such as lubricating oil, but can also be gel-like substances such as lubricating grease.

[0145] (Implementation Method 2)

[0146] like Figure 16 As shown, the difference between the internal meshing planetary gear device 1B (hereinafter also referred to as "gear device 1B") of this embodiment and the gear device 1A of Embodiment 1 is that the output side cover 14 (see reference) is omitted. Figure 7 Hereinafter, the same symbols will be used for structures that are the same as in Embodiment 1, and descriptions will be omitted as appropriate. Figure 16 This is a schematic cross-sectional view of gear assembly 1B.

[0147] In the gear assembly 1B of this embodiment, a spacer 15 is installed on the output side gear carrier 19 instead of the output side cover 14. The spacer 15 is disposed within a bearing hole 195 in the output side gear carrier 19 into which a roller bearing 42 is inserted. The spacer 15 is disc-shaped with an outer diameter less than the inner diameter of the bearing hole 195, and is disposed to close the bearing hole 195. Inside the bearing hole 195, on the opposite side from the crankshafts 7A, 7B, and 7C when viewed from the spacer 15, a retaining ring 151 is installed. Thus, the spacer 15 is positioned axially in a configuration where it is clamped between the retaining ring 151 and the crankshafts 7A, 7B, and 7C. Figure 16 The following explanation uses crankshaft 7A as an example, but the same structure is used for crankshafts 7B and 7C. That is, the same number (3 in this case) of spacers 15 are installed on the output side gear carrier 19 as on crankshafts 7A, 7B, and 7C.

[0148] In this embodiment, if Figure 17 As shown, the second limiting structure 92 includes the spacer 15 and the end face 76 of the output side of the rotation axis Ax1 of the crankshafts 7A, 7B, and 7C. According to this second limiting structure 92, the output side of the crankshafts 7A, 7B, and 7C facing the rotation axis Ax1 ( Figure 17The end face 76 (left side) contacts the input side of the spacer 15 facing the rotation axis Ax1. Figure 17 The middle section is the right side, thus, crankshafts 7A, 7B, and 7C face the other side of the axial direction ( Figure 17 The movement of the crankshafts 7A, 7B, and 7C (to the left) is restricted. That is, the end faces 76 of the crankshafts 7A, 7B, and 7C contact the spacer 15 mounted on the output side gear carrier 19, thereby prohibiting the movement of the crankshafts 7A, 7B, and 7C toward the other side of the axial direction.

[0149] Compared to the gear device 1A of Embodiment 1, the gear device 1B of this embodiment has the following advantages. Specifically, corresponding to the thickness of the output side cover 14, the depth of the plurality of mounting holes 194 provided on the output side gear carrier 19 can be ensured to be deep, easily improving the mounting strength of the target component relative to the output side gear carrier 19. Furthermore, unlike the output side cover 14, the spacer plate 15 does not need to have a plurality of through holes 141 corresponding to the plurality of mounting holes 194, and the arrangement and number of through holes 141 do not need to be adjusted according to the target component. Moreover, the fixing bolts 142 (see reference 144) are not required. Figure 8 The spacer plate 15 is installed to the output side gear carrier 19, so that the mounting hole 194 can be provided without interfering with the fixing bolt 142.

[0150] The structure of Embodiment 2 can be appropriately combined with the various structures (including variations) described in Embodiment 1.

[0151] (Summarize)

[0152] As explained above, the first embodiment of the internal meshing planetary gear assembly (1, 1A, 1B) includes an internal gear (2), a planetary gear (3), a crankshaft (7A, 7B, 7C), and a pair of gear carriers (18, 19). By oscillating the planetary gear (3), the planetary gear (3) rotates relative to the internal gear (2). The internal gear (2) has an annular gear body (22) and a plurality of outer pins (23) which 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) and constitute internal teeth (21). The planetary gear (3) has outer teeth (31) that partially mesh with the internal teeth (21). The crankshaft (7A, 7B, 7C) has stepped portions (70) at at least two locations along the axial direction of the shaft (Ax2), and the planetary gear (3) oscillates by rotating about the shaft (Ax2). A pair of gear carriers (18, 19) are arranged on both sides of the planetary gear (3) and rotatably support the crankshaft (7A, 7B, 7C). Lubrication passages (S1) for lubricant to pass through are formed between the step portion (70) and the pair of gear carriers (18, 19).

[0153] According to this configuration, by ensuring a lubrication passage (S1) between the step section (70) and the pair of gear carriers (18, 19), lubricant can circulate through the lubrication passage (S1), thereby improving the lubrication condition around the crankshafts (7A, 7B, 7C). Therefore, it is difficult for "lubricant shortage" or "lubricant depletion" to occur around the crankshafts (7A, 7B, 7C), thus ensuring a constant supply of a sufficient amount of lubricant. Furthermore, compared to a structure where the lubricant remains in a fixed position, the lubricant circulates through the lubrication passage (S1), thereby constantly rotating the lubricant around the crankshafts (7A, 7B, 7C), thus suppressing lubricant deterioration. Therefore, even in the long term, losses caused by friction can be reduced, easily achieving a long service life for the internal meshing planetary gear system (1, 1A, 1B).

[0154] The second type of internal meshing planetary gear device (1, 1A, 1B) is the same as the first type, where the lubrication passage (S1) includes a radial passage (S11) that allows the lubricant to pass through in a radial direction orthogonal to the axial direction.

[0155] Based on this configuration, the lubricant can be circulated efficiently by allowing it to pass radially.

[0156] The third type of internal meshing planetary gear device (1, 1A, 1B) is, in the first or second type, also equipped with a limiting structure (9) that restricts the axial movement of the crankshaft (7A, 7B, 7C).

[0157] Based on this configuration, it is possible to reduce loosening and transmission losses caused by axial movement of the crankshafts (7A, 7B, 7C).

[0158] The fourth type of internal meshing planetary gear assembly (1, 1A, 1B) is the third type, in which the crankshaft (7A, 7B, 7C) has an eccentric portion (72) that is eccentric relative to the axis (Ax2). The step portions (702, 703) are the end faces of the eccentric portion (72). The limiting structure (9) is located in the crankshaft (7A, 7B, 7C) at a position further axially outward than the step portions (702, 703), and restricts the axial movement of the crankshaft (7A, 7B, 7C) by contacting the end face (76) facing axially outward.

[0159] According to this configuration, by utilizing the end face (76) of the non-eccentric portion (72) end face (step portion 702, 703) in the crankshaft (7A, 7B, 7C), the axial movement of the crankshaft (7A, 7B, 7C) is restricted, thereby reducing the wear of the eccentric portion (72).

[0160] The fifth type of internal meshing planetary gear assembly (1, 1A, 1B) is in the third or fourth type, where the limiting structure (9) includes a pair of covers (13, 14) mounted on both sides of a pair of gear carriers (18, 19).

[0161] Based on this configuration, the axial movement of the crankshaft (7A, 7B, 7C) can be restricted by a pair of covers (13, 14), thus limiting the design changes of the pair of gear carriers (18, 19) to a small scale.

[0162] The sixth type of internal meshing planetary gear device (1, 1A, 1B) is in any of the types 1 to 5, in which, in the axial direction, there is a gap between the step portion (70) and at least one of the gear carriers (18, 19) of a pair of gear carriers (18, 19), and the lubrication passage (S1) includes the gap.

[0163] According to this configuration, the lubricant can be circulated by utilizing the axial gap between the stepped portion (70) and at least one gear carrier (18, 19).

[0164] The seventh type of internal meshing planetary gear assembly (1, 1A, 1B) is, in any of the types 1 to 6, further comprising a plate-shaped part (washers 82, 84) disposed between the stepped portion and a pair of gear carriers (18, 19). The lubrication passage (S1) includes a groove (80) formed in the plate-shaped part (washers 82, 84) on the facing surface of the gear carriers (18, 19).

[0165] According to this configuration, compared with the case without groove (80), the cross-sectional area of ​​the lubrication passage (S1) can be increased, thereby enabling the lubricant to circulate more efficiently.

[0166] The eighth form of the internal meshing planetary gear device (1, 1A, 1B) is in any of the forms from 1 to 7, and further includes: an input gear (501) that rotates around a rotating shaft (Ax1); and multiple crankshaft gears (502A, 502B, 502C) arranged around the input gear (501) in a meshing manner, rotating synchronously with each other when the input gear (501) rotates. Multiple crankshafts (7A, 7B, 7C) are provided in a manner corresponding one-to-one with the multiple crankshaft gears (502A, 502B, 502C). The multiple crankshafts (7A, 7B, 7C) rotate together with the multiple crankshaft gears (502A, 502B, 502C), causing the planetary gear (3) to oscillate around the rotating shaft (Ax1).

[0167] Based on this configuration, in the split-type internal meshing planetary gear unit (1, 1A, 1B), it is possible to improve the lubrication condition around multiple crankshafts (7A, 7B, 7C).

[0168] The robot joint device (200) of the ninth form includes: an internal meshing planetary gear device (1, 1A, 1B) of any of the first to eighth forms; a first member (201) fixed to the gear body (22); and a second member (202) that rotates relative to the first member (201) as the planetary gear (3) rotates relative to the internal gear (2).

[0169] Based on this configuration, the lubrication condition can be improved.

[0170] The structures of forms 2 to 8 are not essential for the internal meshing planetary gear system (1, 1A, 1B) and can be omitted appropriately.

[0171] [Explanation of Symbols]

[0172] 1, 1A, 1B: Internal meshing planetary gear system

[0173] 2: Internal gears

[0174] 3: Planetary Gears

[0175] 7A, 7B, 7C: Crankshaft

[0176] 9: Restricted Structure

[0177] 13: Input side cover (mask)

[0178] 14: Output side cover (cover)

[0179] 18: Input side gear carrier (gear carrier)

[0180] 19: Output side gear carrier (gear holder)

[0181] 21: Internal teeth

[0182] 22: Gear body

[0183] 23: Export

[0184] 31: External teeth

[0185] 70, 701, 702, 703, 704: Step difference part

[0186] 72: Eccentric part

[0187] 76: End face

[0188] 80: Groove

[0189] 82, 84: Washers (plate-shaped parts)

[0190] 200: Robotic Joint Devices

[0191] 201: Component 1

[0192] 202: Component 2

[0193] 221: (The inner circumferential surface of the gear body)

[0194] 223: Inner circumferential groove

[0195] 501: Input gear

[0196] 502A, 502B, 502C: Crankshaft gears

[0197] Ax1: Rotation axis

[0198] Ax2: Axis

[0199] S1: Lubrication passage

[0200] S11: Radial path.

Claims

1. An internally meshing planetary gear device, comprising: An internal gear having an annular gear body and a plurality of outer pins, wherein the plurality of outer pins are held in a plurality of inner peripheral grooves formed on the inner peripheral surface of the gear body in a rotatable state and constitute internal teeth; a planetary gear having external teeth partially meshing with the internal teeth; a crankshaft having step portions at at least two locations along the axial direction of the axis, and causing the planetary gear to oscillate by rotating about the axis; and a pair of gear carriers, arranged on both sides of the axial direction of the planetary gear, rotatably supporting the crankshaft, By swinging the planetary gear, the planetary gear is rotated relative to the internal gear. Lubrication passages for passing lubricant are respectively formed between the step portion and the pair of gear carriers.

2. The internally meshing planetary gear device according to claim 1, wherein The lubrication passage includes a radial passage through which lubricant passes in a radial direction orthogonal to the axial direction.

3. The internally meshing planetary gear device according to claim 1 or 2, further comprising: A limiting structure limits the axial movement of the crankshaft.

4. The internally meshing planetary gear device according to claim 3, wherein The crankshaft has an eccentric portion that is eccentric with respect to the axis. The step difference portion is an end surface of the eccentric portion, The restriction structure is located on the crankshaft at an outer side in the axial direction than the step portion, and restricts movement of the crankshaft in the axial direction by contacting an end surface facing the outer side in the axial direction.

5. The internally meshing planetary gear device according to claim 3, wherein The restricting structure includes a pair of covers mounted on both sides of the pair of gear carriers in the axial direction.

6. The internally meshing planetary gear device according to claim 1 or 2, wherein In the axial direction, a gap exists between the step portion and at least one of the pair of carriers, and the lubrication passage includes the gap.

7. The internally meshing planetary gear device according to claim 1 or 2, further comprising: The plate-shaped component is arranged between the step portion and the pair of gear racks. The lubrication passage includes a groove portion formed on a surface of the plate-shaped component facing the gear carrier.

8. The internally meshing planetary gear device according to claim 1 or 2, further comprising: An input gear, which rotates around the rotation axis; and A plurality of crankshaft gears are arranged around the input gear in a manner meshing with the input gear and rotate synchronously with each other when the input gear rotates. The crankshaft is provided with a plurality of gears in a one-to-one correspondence with the plurality of crankshaft gears. The plurality of crankshafts rotate together with the plurality of crankshaft gears, and the planetary gears oscillate around the rotation shaft.

9. A robot joint device, comprising: The internal meshing planetary gear device according to claim 1 or 2; a first member fixed to the gear body; 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.

Images