Internal meshing planetary gear mechanism and actuator

Abstract

A miniaturized internal meshing planetary gear device and actuator. The internal meshing planetary gear device (1) includes a bearing member (6), an internal gear (2), a planetary gear (3), and a plurality of inner pins (4). The bearing member (6) has an outer ring (62) and an inner ring (61) disposed inside the outer ring (62). The inner ring (61) is supported so as to be rotatable relative to the outer ring (62). The internal gear (2) has internal teeth (21) and is fixed to the outer ring (62). The planetary gear (3) has external teeth that partially mesh with the internal teeth (21). The plurality of inner pins (4) revolve within the inner pin holes (32) and rotate relative to the internal gear (2) while being respectively inserted into the inner pin holes (32) formed in the planetary gear (3). Here, each of the plurality of inner pins (4) is held in the inner ring (61) in a state that allows it to rotate on its own axis. Furthermore, each of the multiple inner pins (4) will have at least a portion of itself positioned axially in the same location as the bearing member (6).

Description

[0001] Cross-reference to related applications

[0002] This application is based on and claims priority to Japanese Patent Application No. 2020-128086, filed on July 29, 2020, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This disclosure generally relates to internal meshing planetary gear devices and actuators, and more specifically, to internal meshing planetary gear devices and actuators in which a planetary gear with external teeth is disposed inside an internal gear with internal teeth. Background Technology

[0004] As a related technology, there are known gear devices of the so-called eccentric oscillation type, in which a planetary gear engages with an internal gear while eccentrically oscillating (for example, see Patent Document 1). In the gear device of this related technology, an eccentric body is integrally formed with the input shaft, and a planetary gear is mounted on the eccentric body via an eccentric body bearing. External teeth, such as arc-shaped teeth, are formed on the outer periphery of the planetary gear.

[0005] An internal gear is constructed by rotatably fitting multiple pins (roller pins) that form the internal teeth into the inner circumferential surface of a gear body (internal gear body), which also serves as the housing. In a planetary gear, multiple inner pin holes (inner roller holes) are formed at appropriate intervals along the circumferential direction, into which inner pins and inner rollers are inserted. The inner pins are connected to a support at one axial end, and the support is rotatably supported in the housing via bearing members (crossed rollers). This gear assembly can be used as a gear assembly that removes the planetary gear from the support by rotating the internal gear relative to its rotational component. Summary of the Invention

[0006] In the structure of the aforementioned related technology, since an inner roller is necessary to reduce the loss caused by the frictional resistance between the inner circumferential surface of the inner pin hole of the planetary gear and the inner pin, it is difficult to miniaturize the inner pin hole, thus hindering the miniaturization of the planetary gear.

[0007] The purpose of this disclosure is to provide an internal meshing planetary gear device and actuator that are easily miniaturized.

[0008] An embodiment of the internal meshing planetary gear device disclosed herein includes a bearing member, an internal gear, a planetary gear, and a plurality of inner pins. The bearing member has an outer ring and an inner ring disposed inside the outer ring, the inner ring being supported to be rotatable relative to the outer ring. The internal gear has internal teeth and is fixed to the outer ring. The planetary gear has external teeth that partially mesh with the internal teeth. The plurality of inner pins, respectively inserted into a plurality of inner pin holes formed in the planetary gear, revolve within the inner pin holes and rotate relative to the internal gear. Each of the plurality of inner pins is held in the inner ring in a rotatable state, and each of the plurality of inner pins has at least a portion disposed axially in the same position as the bearing member.

[0009] One embodiment of the actuator disclosed herein includes: the internal meshing planetary gear assembly; and a drive source that generates a driving force for oscillating the planetary gears.

[0010] According to embodiments of this disclosure, an internal meshing planetary gear device and actuator that are easily miniaturized can be provided. Attached Figure Description

[0011] Figure 1 This is a perspective view showing the schematic structure of an actuator including an internal meshing planetary gear device of one embodiment.

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

[0013] Figure 3 This is a schematic cross-sectional view of the aforementioned internal meshing planetary gear assembly.

[0014] Figure 4 This illustrates the aforementioned internal meshing planetary gear mechanism. Figure 3 Sectional view along line A1-A1.

[0015] Figure 5A This is a perspective view of the planetary gears of the aforementioned internal meshing planetary gear assembly, shown as a single unit.

[0016] Figure 5B This is a front view of the planetary gears of the aforementioned internal meshing planetary gear assembly, shown as a single unit.

[0017] Figure 6A This is a perspective view of the bearing component of the aforementioned internal meshing planetary gear assembly.

[0018] Figure 6B This is a front view showing the bearing component of the aforementioned internal meshing planetary gear assembly.

[0019] Figure 7A This is a perspective view of the eccentric shaft of the aforementioned internal meshing planetary gear device.

[0020] Figure 7B This is a front view of the eccentric shaft of the aforementioned internal meshing planetary gear assembly, shown as a single unit.

[0021] Figure 8A This is a perspective view of the support body of the aforementioned internal meshing planetary gear device.

[0022] Figure 8B This is a front view of the support body of the aforementioned internal meshing planetary gear device, shown as a single unit.

[0023] Figure 9 This illustrates the aforementioned internal meshing planetary gear mechanism. Figure 3 A magnified view of region Z1.

[0024] Figure 10 This illustrates the aforementioned internal meshing planetary gear mechanism. Figure 3 Sectional view along line B1-B1.

[0025] Figure 11 This is a schematic cross-sectional view showing the main parts of an internal meshing planetary gear device according to another embodiment. Detailed Implementation

[0026] (1) Summary

[0027] The following is a summary of the internal meshing planetary gear device 1 of this embodiment, referring to... Figures 1-3 The accompanying drawings, which are used in the embodiments of this disclosure, are schematic diagrams, and the size and thickness ratios of the structural elements shown may not reflect the actual dimensional ratios. For example, Figures 1-3 The tooth shape, size, and number of teeth of the inner tooth 21 and the outer tooth 31 are merely schematic representations for illustrative purposes, and their main purpose is not limited to the shape shown in the illustration.

[0028] The internal meshing planetary gear assembly 1 (hereinafter also simply referred to as "gear assembly 1") of this embodiment is a gear assembly including an internal gear 2, a planetary gear 3, and a plurality of inner pins 4. In this gear assembly 1, the planetary gear 3 is arranged inside the annular internal gear 2, and an eccentric bearing 5 is arranged inside the planetary gear 3. The eccentric bearing 5 has an inner eccentric ring 51 and an outer eccentric ring 52, the inner eccentric ring 51 surrounding a ring from the center C1 of the inner eccentric ring 51 (see reference φ1). Figure 3 The offset rotation axis Ax1 (refer to) Figure 3The planetary gear 3 oscillates due to the rotation (eccentric motion) of the eccentric inner ring 51. The inner ring 51 of the eccentric gear rotates about the rotation axis Ax1, for example, by the rotation of the eccentric shaft 7 inserted into the inner ring 51. Furthermore, the internal meshing planetary gear device 1 also includes a bearing member 6 having an outer ring 62 and an inner ring 61. The inner ring 61 is disposed inside the outer ring 62 and is supported so as to be able to rotate relative to the outer ring 62.

[0029] The internal gear 2 has internal teeth 21 and is fixed to the outer ring 62. Specifically, in this embodiment, the internal gear 2 has an annular gear body 22 and multiple pins 23. The multiple pins 23 are held in a rotatable state on the inner circumferential surface 221 of the gear body 22, forming the internal teeth 21. The planetary gear 3 has external teeth 31 that partially mesh with the internal teeth 21. That is, inside the internal gear 2, the planetary gear 3 is tangent to the internal gear 2, and a portion of the external teeth 31 meshes with a portion of the internal teeth 21. In this state, when the eccentric shaft 7 rotates, the planetary gear 3 oscillates, and the meshing position of the internal teeth 21 and the external teeth 31 moves along the circumferential direction of the internal gear 2, generating a relative rotation between the two gears (internal gear 2 and planetary gear 3) corresponding to the difference in the number of teeth between the planetary gear 3 and the internal gear 2. Here, if the internal gear 2 is fixed, the planetary gear 3 rotates (rotates) along with the relative rotation of the two gears. As a result, a rotational output that is reduced at a relatively high reduction ratio can be obtained from the planetary gear 3, corresponding to the difference in the number of teeth between the two gears.

[0030] This gear device 1 is used in such a way that the rotation of the planetary gear 3, corresponding to its rotational component, is taken out as, for example, the rotation of an output shaft integrated with the inner ring 61 of the bearing member 6. Thus, the gear device 1 functions as a gear device with a relatively high reduction ratio, using the eccentric shaft 7 as the input side and the output shaft as the output side. Therefore, in the gear device 1 of this embodiment, in order to transmit the rotation of the planetary gear 3, corresponding to its rotational component, to the inner ring 61 of the bearing member 6, multiple inner pins 4 are used to connect the planetary gear 3 to the inner ring 61. The multiple inner pins 4, when respectively inserted into multiple inner pin holes 32 formed in the planetary gear 3, revolve within the inner pin holes 32 and rotate relative to the internal gear 2. That is, the inner pin holes 32 have a diameter larger than the inner pins 4, and the inner pins 4 can move revolve within the inner pin holes 32 while inserted into them. Furthermore, the oscillating component of the planetary gear 3, i.e., the revolving component of the planetary gear 3, is absorbed by the interlocking of the inner pin holes 32 of the planetary gear 3 and the inner pins 4. In other words, the multiple inner pins 4 revolve within the multiple inner pin holes 32, thereby absorbing the oscillation component of the planetary gear 3. Therefore, through the multiple inner pins 4, the rotation (rotation component) of the planetary gear 3, excluding the oscillation component (revolution component), is transmitted to the inner ring 61 of the bearing member 6.

[0031] However, in this gear device 1, the inner pin 4 revolves within the inner pin hole 32 of the planetary gear 3, and simultaneously transmits the rotation of the planetary gear 3 to multiple inner pins 4. Therefore, as a first linking technique, it is known to use an inner roller mounted on the inner pin 4 so that it can rotate around the inner pin 4 as an axis. That is, in the first linking technique, the inner pin 4 is held in a state where it is pressed into the inner ring 61 (or a bracket integrated with the inner ring 61), and when the inner pin 4 revolves within the inner pin hole 32, the inner pin 4 slides relative to the inner circumferential surface 321 of the inner pin hole 32. Therefore, as a first linking technique, an inner roller is used to reduce the loss caused by the frictional resistance between the inner circumferential surface 321 of the inner pin hole 32 and the inner pin 4. However, if the structure includes an inner roller as in the first linking technique, the inner pin hole 32 needs to have a diameter that allows the inner pin 4 with the inner roller to revolve, making miniaturization of the inner pin hole 32 difficult. When miniaturization of the inner pin hole 32 is difficult, it hinders the miniaturization of the planetary gear 3 (especially the reduction of its diameter), and even hinders the miniaturization of the gear assembly 1 as a whole. The gear assembly 1 of this embodiment can provide an internal meshing planetary gear assembly 1 that is easily miniaturized through the following structure.

[0032] That is, such as Figures 1-3 As shown, the gear device 1 of this embodiment includes a bearing member 6, an internal gear 2, a planetary gear 3, and a plurality of inner pins 4. The bearing member 6 has an outer ring 62 and an inner ring 61 disposed inside the outer ring 62. The inner ring 61 is supported so as to be rotatable relative to the outer ring 62. The internal gear 2 has internal teeth 21 and is fixed to the outer ring 62. The planetary gear 3 has external teeth 31 that partially mesh with the internal teeth 21. The plurality of inner pins 4, when respectively inserted into a plurality of inner pin holes 32 formed in the planetary gear 3, revolve within the inner pin holes 32 and rotate relative to the internal gear 2. Here, each of the plurality of inner pins 4 is held in the inner ring 61 in a state that allows it to rotate on its own axis. Furthermore, each of the plurality of inner pins 4 has at least a portion disposed at the same position as the bearing member 6 in the axial direction.

[0033] According to this configuration, each of the multiple inner pins 4 is held in the inner ring 61 in a rotatable state, so that when the inner pins 4 revolve within the inner pin holes 32, the inner pins 4 themselves can rotate. Therefore, even without using inner rollers mounted on the inner pins 4 and rotatable around the inner pins 4, losses caused by frictional resistance between the inner circumferential surface 321 of the inner pin holes 32 and the inner pins 4 can be reduced. Therefore, in the gear device 1 of this embodiment, it is not necessary to provide inner rollers, thus having the advantage of easy miniaturization. Moreover, each of the multiple inner pins 4 is at least partially arranged in the same position as the bearing member 6 in the axial direction, thus the size of the gear device 1 in the axial direction of the bearing member 6 can be reduced. That is, compared with the structure in which the bearing member 6 and the inner pins 4 are arranged side by side (opposite) in the axial direction of the bearing member 6, in the gear device 1 of this embodiment, the size of the gear device 1 in the axial direction can be reduced, thereby contributing to further miniaturization (thinning) of the gear device 1.

[0034] Furthermore, if the size of the planetary gear 3 is the same as that of the first associated technology described above, then compared with the first associated technology described above, for example, it is possible to increase the number of inner pins 4 to make the rotation transmission smoother, or to make the inner pins 4 thicker to increase strength.

[0035] Furthermore, in this gear assembly 1, the inner pins 4 need to revolve within the inner pin holes 32 of the planetary gear 3. Therefore, as a second related technique, there is a situation where multiple inner pins 4 are held only by the inner ring 61 (or a bracket integrated with the inner ring 61). According to the second related technique, it is difficult to improve the centering accuracy of the multiple inner pins 4. Poor centering may lead to adverse conditions such as vibration and decreased transmission efficiency. That is, the multiple inner pins 4 revolve within the inner pin holes 32 and rotate relative to the internal gear 2, thereby transmitting the rotational component of the planetary gear 3 to the inner ring 61 of the bearing member 6. At this time, if the centering accuracy of the multiple inner pins 4 is insufficient and the rotation axis of the multiple inner pins 4 deviates or tilts relative to the rotation axis of the inner ring 61, it becomes a state of poor centering, which may lead to adverse conditions such as vibration and decreased transmission efficiency. The gear assembly 1 of this embodiment can provide an internal meshing planetary gear assembly 1 that is less prone to adverse conditions caused by poor centering of the multiple inner pins 4 through the following structure.

[0036] That is, such as Figures 1-3As shown, the gear device 1 of this embodiment includes an internal gear 2, a planetary gear 3, a plurality of inner pins 4, and a support body 8. The internal gear 2 has an annular gear body 22 and a plurality of pins 23. The plurality of pins 23 are held in a rotatable state on the inner circumferential surface 221 of the gear body 22 to form internal teeth 21. The planetary gear 3 has external teeth 31 that partially mesh with the internal teeth 21. The plurality of inner pins 4, when respectively inserted into a plurality of inner pin holes 32 formed in the planetary gear 3, revolve within the inner pin holes 32 and rotate relative to the gear body 22. The support body 8 is annular and supports the plurality of inner pins 4. Here, the support body 8 is positionally restricted by contacting the plurality of pins 23 with its outer circumferential surface 81.

[0037] According to this configuration, the multiple inner pins 4 are supported by an annular support body 8. Therefore, the multiple inner pins 4 are bound together by the support body 8, which suppresses relative deviation and tilting of the multiple inner pins 4. Furthermore, the outer peripheral surface 81 of the support body 8 contacts the multiple pins 23, thereby restricting the position of the support body 8. In short, by centering the support body 8 using the multiple pins 23, it is also possible to center the multiple inner pins 4 supported by the support body 8 using the multiple pins 23. Therefore, the gear device 1 according to this embodiment easily achieves improved centering accuracy of the multiple inner pins 4, and has the advantage of minimizing adverse conditions caused by poor centering of the multiple inner pins 4.

[0038] In addition, such as Figure 1 As shown, the gear assembly 1 and the drive source 101 together constitute the actuator 100 in this embodiment. In other words, the actuator 100 in this embodiment includes the gear assembly 1 and the drive source 101. The drive source 101 generates a driving force for oscillating the planetary gear 3. Specifically, the drive source 101 causes the eccentric shaft 7 to rotate about the rotation axis Ax1, thereby causing the planetary gear 3 to oscillate.

[0039] (2) Definition

[0040] The term "annular" as used in this disclosure refers to a shape that forms a ring (circle) of enclosed space (area) on the inside, at least when viewed from above. It is not limited to a circular shape (annular) that is perfectly round when viewed from above; for example, it can also be an elliptical shape or a polygonal shape. Furthermore, even shapes with a bottom, such as a cup shape, are included in the term "annular" as long as their peripheral walls are annular.

[0041] In this embodiment of the disclosure, "fitting" refers to a state in which the inner pin 4 is fitted with a clearance, and the inner pin hole 32 is a hole for the inner pin 4 to fit into. That is, the inner pin 4 is inserted into the inner pin hole 32 with sufficient space (clearance) between it and the inner circumferential surface 321 of the inner pin hole 32. In other words, the diameter of at least the portion of the inner pin 4 inserted into the inner pin hole 32 is smaller (fineer) than the diameter of the inner pin hole 32. Therefore, the inner pin 4, when inserted into the inner pin hole 32, can move within the inner pin hole 32, that is, it can move relative to the center of the inner pin hole 32. Thus, the inner pin 4 can revolve within the inner pin hole 32. However, it is not necessary to ensure a clearance as a void between the inner circumferential surface 321 of the inner pin hole 32 and the inner pin 4; for example, a fluid such as liquid can be filled into the clearance.

[0042] In this embodiment of the disclosure, "revolution" refers to an object rotating 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 rotation axis. Therefore, for example, when an object rotates around an eccentric axis parallel to the central axis passing through its center (center of gravity), the object revolves around the eccentric axis. As an example, the inner pin 4 revolves around an axis of rotation passing through the center of the inner pin hole 32, and revolves within the inner pin hole 32.

[0043] Additionally, in embodiments of this disclosure, sometimes one side of the rotating shaft Ax1 ( Figure 3 The left side of the axis (Ax1) is called the "input side", and the other side of the axis (Ax1) is called the "input side". Figure 3 The right side of the output is called the "output side". Figure 3 In the example, rotation is imparted to the rotating body (eccentric inner ring 51) from the "input side" of the rotating shaft Ax1, and rotation of multiple inner pins 4 (inner ring 61) is taken out from the "output side" of the rotating shaft Ax1. However, "input side" and "output side" are merely labels given for illustrative purposes, and their purpose is not to limit the positional relationship of input and output as observed from the gear device 1.

[0044] In this embodiment of the disclosure, the "rotation axis" refers to a virtual axis (straight line) that serves as the center of rotational motion of the rotating body. That is, the rotation axis Ax1 is a virtual axis without a physical component. The inner ring 51 of the eccentric body rotates around the rotation axis Ax1.

[0045] In this embodiment of the disclosure, "internal teeth" and "external teeth" refer to a collection (group) of multiple "teeth" rather than a single "tooth". That is, the internal teeth 21 of the internal gear 2 are composed of a collection of multiple teeth arranged on the inner circumferential surface 221 of the internal gear 2 (gear body 22). Similarly, the external teeth 31 of the planetary gear 3 are composed of a collection of multiple teeth arranged on the outer circumferential surface of the planetary gear 3.

[0046] (3) Structure

[0047] The following detailed structure of the internal meshing planetary gear device 1 according to this embodiment will be provided with reference to... Figures 1 to 8B Please provide an explanation.

[0048] Figure 1 This is a perspective view showing the schematic structure of the actuator 100, which includes the gear mechanism 1. Figure 1 The drive source 101 is schematically shown in the diagram. Figure 2 This is a schematic exploded perspective view of the gear device 1 as seen from the output side of the rotating shaft Ax1. Figure 3 This is a schematic cross-sectional view of gear assembly 1. Figure 4 yes Figure 3 A sectional view along line A1-A1. Wherein... Figure 4 In the section, for components other than the eccentric shaft 7, although it is also a cross-section, the section lines are omitted. Furthermore, in... Figure 4 The inner circumferential surface 221 of the gear body 22 is omitted from the illustration. Figure 5A and Figure 5B This is a perspective view and front view showing planetary gear 3 as a single unit. Figure 6A and Figure 6B This is a perspective view and front view showing the bearing component 6 as a single unit. Figure 7A and Figure 7B It is a three-dimensional view and a front view showing the eccentric shaft 7 as a single unit. Figure 8A and Figure 8B This is a perspective view and front view showing the support body 8 as a single unit.

[0049] (3.1) Overall Structure

[0050] like Figures 1-3 As shown, the gear assembly 1 of this embodiment includes an internal gear 2, a planetary gear 3, multiple inner pins 4, an eccentric bearing 5, a bearing component 6, an eccentric shaft 7, and a support body 8. Furthermore, in this embodiment, the gear assembly 1 also includes a first bearing 91, a second bearing 92, and a housing 10. In this embodiment, the internal gear 2, planetary gear 3, multiple inner pins 4, eccentric bearing 5, bearing component 6, eccentric shaft 7, and support body 8, which are structural elements of the gear assembly 1, are made of metals such as stainless steel, cast iron, carbon steel for mechanical structures, chromium-molybdenum steel, phosphor bronze, or aluminum bronze. The metals mentioned here include metals that have undergone surface treatments such as nitriding.

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

[0052] In this embodiment, as an example, the gear device 1 is used with the gear body 22 of the internal gear 2 and the outer ring 62 of the bearing member 6 fixed to a fixed member such as the housing 10. Thus, as the internal gear 2 and the planetary gear 3 rotate relative to each other, the planetary gear 3 rotates relative to the fixed member (housing 10, etc.).

[0053] Furthermore, in this embodiment, when the gear device 1 is used in the actuator 100, a rotational force is applied to the eccentric shaft 7 as input and taken out as output rotational force from the output shaft integrated with the inner ring 61 of the bearing member 6. That is, the gear device 1 operates with the rotation of the eccentric shaft 7 as input rotation and the rotation of the output shaft integrated with the inner ring 61 as output rotation. As a result, in the gear device 1, an output rotation that is reduced at a relatively high reduction ratio relative to the input rotation can be obtained.

[0054] The drive source 101 is a power source such as an electric motor. The power generated by the drive source 101 is transmitted to the eccentric shaft 7 in the gear assembly 1. Specifically, the drive source 101 is connected to the eccentric shaft 7 via an input shaft, and the power generated by the drive source 101 is transmitted to the eccentric shaft 7 via the input shaft. Thus, the drive source 101 can rotate the eccentric shaft 7.

[0055] Furthermore, in the gear device 1 of this embodiment, such as Figure 3 As shown, the input-side rotation axis Ax1 and the output-side rotation axis Ax1 are on the same straight line. In other words, the input-side rotation axis Ax1 and the output-side rotation axis Ax1 are coaxial. Here, the input-side rotation axis Ax1 is the rotation center of the eccentric shaft 7, which is given input rotation, and the output-side rotation axis Ax1 is the rotation center of the inner ring 61 (and output shaft), which generates output rotation. That is, in the gear device 1, it is possible to obtain output rotation that is reduced in speed by a relatively high reduction ratio by rotating coaxially relative to the input.

[0056] like Figure 4 As shown, the internal gear 2 is an annular component with internal teeth 21. In this embodiment, the internal gear 2 has an annular shape, at least its inner circumferential surface being a perfect circle when viewed from above. Internal teeth 21 are formed along the circumferential direction of the annular internal gear 2 on its inner circumferential surface. All teeth constituting the internal teeth 21 are of the same shape and are evenly spaced throughout the entire circumferential region of the inner circumferential surface of the internal gear 2. That is, the pitch circle of the internal teeth 21 is a perfect circle when viewed from above. The center of the pitch circle of the internal teeth 21 is located on the rotation axis Ax1. Furthermore, the internal gear 2 has a predetermined thickness along the direction of the rotation axis Ax1. The tooth directions of the internal teeth 21 are all parallel to the rotation axis Ax1. The dimension of the internal teeth 21 in the tooth direction is slightly smaller than that in the thickness direction of the internal gear 2.

[0057] Here, as described above, the internal gear 2 has an annular (ring-shaped) gear body 22 and multiple pins 23. The multiple pins 23 are held in a rotatable state on the inner circumferential surface 221 of the gear body 22, forming the internal teeth 21. In other words, the multiple pins 23 function as multiple teeth constituting the internal teeth 21. Specifically, on the inner circumferential surface 221 of the gear body 22, as... Figure 2 Multiple grooves are formed throughout the circumferential region. All grooves are of the same shape and are equally spaced. All grooves are parallel to the rotation axis Ax1 and extend along the entire thickness of the gear body 22. Multiple pins 23 are fitted into the multiple grooves and assembled to the gear body 22. Each pin 23 is held in a position where it can rotate within its groove. Furthermore, the gear body 22 (together with the outer ring 62) is fixed to the housing 10. Therefore, multiple fixing holes 222 for fixing are formed in the gear body 22.

[0058] like Figure 4 As shown, the planetary gear 3 is an annular component with external teeth 31. In this embodiment, 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 teeth constituting the external teeth 31 are of the same shape and are evenly spaced throughout the entire circumferential region of the outer circumferential surface of the planetary gear 3. That is, the pitch circle of the external teeth 31 is a perfect circle when viewed from above. The center C1 of the pitch circle of the external teeth 31 is located at a distance ΔL offset from the rotation axis Ax1 (see reference). Figure 4 The planetary gear 3 has a defined thickness along the direction of the rotation axis Ax1. The external teeth 31 are formed along the entire length of the planetary gear 3 in the thickness direction. The tooth direction of the external teeth 31 is parallel to the rotation axis Ax1. Unlike the internal gear 2, the external teeth 31 and the main body of the planetary gear 3 are integrally formed from a single metal component.

[0059] Here, the planetary gear 3 is combined with the eccentric bearing 5 and the eccentric shaft 7. Specifically, the planetary gear 3 has a circular opening 33. The opening 33 is a hole that passes through the planetary gear 3 along its thickness direction. Viewed from above, the center of the opening 33 coincides with the center of the planetary gear 3, and the inner circumferential surface of the opening 33 (the inner circumferential surface of the planetary gear 3) is concentric with the pitch circle of the external tooth 31. The eccentric bearing 5 is housed within the opening 33 of the planetary gear 3. Furthermore, the eccentric bearing 5 and the eccentric shaft 7 are combined with the planetary gear 3 by inserting the eccentric shaft 7 into the inner ring 51 of the eccentric bearing 5. With the planetary gear 3 combined with the eccentric bearing 5 and the eccentric shaft 7, when the eccentric shaft 7 rotates, the planetary gear 3 oscillates around the rotation axis Ax1.

[0060] The planetary gear 3, thus configured, is positioned inside the internal gear 2. Viewed from above, the planetary gear 3 is one size smaller than the internal gear 2, allowing it to oscillate inside the internal gear 2 when combined with it. External teeth 31 are formed on the outer circumferential surface of the planetary gear 3, and internal teeth 21 are formed on the inner circumferential surface of the internal gear 2. Therefore, with the planetary gear 3 positioned inside the internal gear 2, the external teeth 31 and the internal teeth 21 are opposite each other.

[0061] Furthermore, the pitch circle of the external tooth 31 is one rotation smaller than that of the internal tooth 21. Also, when the planetary gear 3 is internally tangent to the internal gear 2, the center C1 of the pitch circle of the external tooth 31 is offset by a distance ΔL (refer to the reference point) from the center of the pitch circle of the internal tooth 21 (rotation axis Ax1). Figure 4 Therefore, the external teeth 31 and the internal teeth 21 are at least partially opposed with a gap, and there is no overall meshing in the circumferential direction. 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 partially mesh. That is, by the oscillation of the planetary gear 3 around the rotation axis Ax1, as... Figure 4 As shown, a portion of the teeth constituting the external tooth 31 meshes with a portion of the teeth constituting the internal tooth 21. As a result, in the gear assembly 1, a portion of the external tooth 31 can mesh with a portion of the internal tooth 21.

[0062] 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 embodiment, as an example, N is "1", so the number of teeth of the planetary gear 3 (external teeth 31) is "1" more than the number of teeth of the internal gear 2 (internal teeth 21). This difference in the number of teeth between the planetary gear 3 and the internal gear 2 defines the reduction ratio of the output rotation to the input rotation in the gear unit 1.

[0063] Furthermore, in this embodiment, as an example, the thickness of the planetary gear 3 is smaller than the thickness of the gear body 22 in the internal gear 2. Additionally, the dimension of the external tooth 31 in the tooth direction (parallel to the rotation axis Ax1) is smaller than the dimension of the internal tooth 21 in the tooth direction (parallel to the rotation axis Ax1). In other words, in the direction parallel to the rotation axis Ax1, the external tooth 31 is contained within the tooth direction of the internal tooth 21.

[0064] In this embodiment, as described above, the rotation of the planetary gear 3, corresponding to its rotational component, is taken as the rotation (output rotation) of the output shaft integrated with the inner ring 61 of the bearing member 6. Therefore, the planetary gear 3 is connected to the inner ring 61 using multiple inner pins 4. Figure 5A and Figure 5BAs shown, the planetary gear 3 has multiple inner pin holes 32 for inserting multiple inner pins 4. The number of inner pin holes 32 is the same as the number of inner pins 4; in this embodiment, for example, there are 18 inner pin holes 32 and 18 inner pins 4. Each inner pin hole 32 is a hole that opens in a circular shape and passes through the planetary gear 3 along its thickness direction. The multiple (here, 18) inner pin holes 32 are arranged at equal intervals along the circumferential direction on a virtual circle concentric with the opening 33.

[0065] Multiple inner pins 4 are components that connect the planetary gear 3 to the inner ring 61 of the bearing component 6. Each of the multiple inner pins 4 is cylindrical. The diameter and length of the multiple inner pins 4 are the same. The diameter of the inner pin 4 is one size smaller than the diameter of the inner pin hole 32. Thus, the inner pin 4 is inserted into the inner pin hole 32 (see reference) with sufficient clearance between it and the inner circumferential surface 321 of the inner pin hole 32. Figure 4 ).

[0066] The bearing component 6 is a part having an outer ring 62 and an inner ring 61 and used to extract the output of the gear device 1 as the rotation of the inner ring 61 relative to the outer ring 62. In addition to the outer ring 62 and the inner ring 61, the bearing component 6 also has a plurality of rolling elements 63 (see reference). Figure 3 ).

[0067] like Figure 6A and Figure 6B As shown, both the outer ring 62 and the inner ring 61 are annular components. Both the outer ring 62 and the inner ring 61 are perfectly circular when viewed from above. The inner ring 61 is smaller than the outer ring 62 and is positioned inside the outer ring 62. Here, the inner diameter of the outer ring 62 is larger than the outer diameter of the inner ring 61, thus creating a gap between the inner circumferential surface of the outer ring 62 and the outer circumferential surface of the inner ring 61.

[0068] The inner ring 61 has a plurality of retaining holes 611 for inserting a plurality of inner pins 4 respectively. The number of retaining holes 611 is the same as the number of inner pins 4; in this embodiment, for example, 18 retaining holes 611 are provided. Figure 6A and Figure 6B As shown, each of the plurality of retaining holes 611 is a circularly shaped opening that penetrates the inner ring 61 along the thickness direction. The plurality of (here, 18) retaining holes 611 are arranged at equal intervals along the circumferential direction on a virtual circle concentric with the outer periphery of the inner ring 61. The diameter of the retaining hole 611 is greater than or equal to the diameter of the inner pin 4 but smaller than the diameter of the inner pin hole 32.

[0069] Furthermore, the inner ring 61 is integrated with the output shaft, and the rotation of the inner ring 61 is taken as the rotation of the output shaft. Therefore, a plurality of output-side mounting holes 612 for mounting the output shaft are formed in the inner ring 61 (see reference). Figure 2In this embodiment, a plurality of output-side mounting holes 612 are disposed on a virtual circle that is inside the plurality of retaining holes 611 and concentric with the outer periphery of the inner ring 61.

[0070] The outer ring 62 is fixed together with the gear body 22 of the internal gear 2 to the housing 10 and other fixing components. Therefore, multiple through holes 621 for fixing are formed in the outer ring 62. Specifically, as shown... Figure 3 As shown, the outer ring 62 is fixed to the housing 10 with the gear body 22 sandwiched between it and the housing 10 by screws (bolts) 60 that pass through the through hole 621 and the fixing hole 222 of the gear body 22.

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

[0072] In this embodiment, as an example, the bearing member 6 is a crossed roller bearing. That is, the bearing member 6 has cylindrical rollers as rolling elements 63. Furthermore, the axis of the cylindrical rolling element 63 is inclined at 45 degrees with respect to a plane orthogonal to the rotation axis Ax1, and is orthogonal to the outer periphery of the inner ring 61. In addition, a pair of rolling elements 63 adjacent to each other in the circumferential direction of the inner ring 61 are arranged in an axially orthogonal orientation. In such a bearing member 6 composed of crossed roller bearings, radial loads, thrust loads (in the direction along the rotation axis Ax1), and bending forces (bending moment loads) relative to the rotation axis Ax1 can all be easily borne. Moreover, by means of a single bearing member 6, these three types of loads can be withstood, thereby ensuring the required rigidity.

[0073] like Figure 7A and Figure 7B As shown, the eccentric shaft 7 is a cylindrical component. The eccentric shaft 7 has a central portion 71 and an eccentric portion 72. The central portion 71 is cylindrical, with at least its outer circumferential surface being perfectly circular when viewed from above. The center (central axis) of the central portion 71 coincides with the rotation axis Ax1. The eccentric portion 72 is disk-shaped, with at least its outer circumferential surface being perfectly circular when viewed from above. The center (central axis) of the eccentric portion 72 coincides with a center C1 offset from the rotation axis Ax1. Here, the distance ΔL between the rotation axis Ax1 and the center C1 (refer to...) Figure 7B The eccentricity of the eccentric portion 72 relative to the central portion 71 is defined as the amount of eccentricity. The eccentric portion 72 has a flange shape that protrudes from the outer circumference of the central portion 71 at its center in the longitudinal direction (axial direction). According to the above structure, for the eccentric shaft 7, the eccentric portion 72 performs eccentric motion by rotating the central portion 71 around the rotation axis Ax1.

[0074] In this embodiment, the central portion 71 and the eccentric portion 72 are integrally formed from a single metal component, thereby achieving a seamless eccentric shaft 7. This eccentric shaft 7, with such a shape, is combined with the eccentric bearing 5 in the planetary gear 3. Therefore, when the eccentric shaft 7 rotates, the planetary gear 3 oscillates around the rotation axis Ax1, with the planetary gear 3 having the eccentric bearing 5 and the eccentric shaft 7 combined.

[0075] Furthermore, the eccentric shaft 7 has a through hole 73 that extends through the shaft center portion 71 along the axial direction (length direction). The through hole 73 opens in a circular shape at both end faces of the shaft center portion 71 in the axial direction. The center (central axis) of the through hole 73 coincides with the rotation axis Ax1. Cables such as power lines and signal lines can pass through the through hole 73.

[0076] Furthermore, in this embodiment, a rotational force is applied as an input from the drive source 101 to the eccentric shaft 7. Therefore, a plurality of input-side mounting holes 74 are formed on the eccentric shaft 7 for mounting an input shaft connected to the drive source 101 (see reference). Figure 7A and Figure 7B In this embodiment, a plurality of input-side mounting holes 74 are arranged around the through hole 73 on one end face of the axial part 71 and on a virtual circle concentric with the through hole 73.

[0077] The eccentric bearing 5 is a component having an outer eccentric ring 52 and an inner eccentric ring 51, absorbing the rotational component of the eccentric shaft 7, and transmitting only the oscillating component (revolutionary component) of the eccentric shaft 7 to the planetary gear 3, excluding the rotational component of the eccentric shaft 7. In addition to the outer eccentric ring 52 and the inner eccentric ring 51, the eccentric bearing 5 also has multiple rolling elements 53 (see reference). Figure 3 ).

[0078] Both the outer eccentric ring 52 and the inner eccentric ring 51 are annular components. Both are perfectly circular rings when viewed from above. The inner eccentric ring 51 is smaller than the outer eccentric ring 52 and is positioned inside the outer eccentric ring 52. Here, the inner diameter of the outer eccentric ring 52 is larger than the outer diameter of the inner eccentric ring 51, thus creating a gap between the inner circumferential surface of the outer eccentric ring 52 and the outer circumferential surface of the inner eccentric ring 51.

[0079] Multiple rolling elements 53 are disposed in the gap between the outer ring 52 and the inner ring 51 of the eccentric outer ring. The multiple rolling elements 53 are arranged side-by-side along the circumferential direction of the outer ring 52. All of the multiple rolling elements 53 are metal parts of the same shape and are evenly spaced throughout the entire circumferential region of the outer ring 52. In this embodiment, as an example, the eccentric bearing 5 is constructed of a deep groove ball bearing using balls as rolling elements 53.

[0080] Here, the inner diameter of the inner ring 51 of the eccentric shaft 7 matches the outer diameter of the eccentric portion 72 of the eccentric shaft 7. The eccentric bearing 5 is assembled with the eccentric shaft 7 with the eccentric portion 72 inserted into the inner ring 51 of the eccentric shaft 7. Furthermore, the outer diameter of the outer ring 52 of the eccentric shaft 7 matches the inner diameter (diameter) of the opening 33 of the planetary gear 3. The eccentric bearing 5 is assembled with the planetary gear 3 with the outer ring 52 of the eccentric shaft 7 embedded in the opening 33 of the planetary gear 3. In other words, the eccentric bearing 5, which is mounted on the eccentric portion 72 of the eccentric shaft 7, is housed in the opening 33 of the planetary gear 3.

[0081] In this embodiment, as an example, the width direction (parallel to the rotation axis Ax1) of the inner eccentric ring 51 of the eccentric bearing 5 is approximately the same as the thickness of the eccentric portion 72 of the eccentric shaft 7. The width direction (parallel to the rotation axis Ax1) of the outer eccentric ring 52 is slightly smaller than the width direction of the inner eccentric ring 51. Furthermore, the width direction of the outer eccentric ring 52 is larger than the thickness of the planetary gear 3. Therefore, in the direction parallel to the rotation axis Ax1, the planetary gear 3 is contained within the area of ​​the eccentric bearing 5. On the other hand, the width direction of the outer eccentric ring 52 is smaller than the tooth direction (parallel to the rotation axis Ax1) of the internal gear 21. Therefore, in the direction parallel to the rotation axis Ax1, the eccentric bearing 5 is contained within the area of ​​the internal gear 2.

[0082] With the eccentric bearing 5 and eccentric shaft 7 combined in the planetary gear 3, when the eccentric shaft 7 rotates, the inner ring 51 of the eccentric bearing 5 rotates around a rotation axis Ax1 offset from the center C1 of the inner ring 51 (eccentric motion). At this time, the rotational component of the eccentric shaft 7 is absorbed by the eccentric bearing 5. Therefore, through the eccentric bearing 5, the rotation of the eccentric shaft 7, except for its rotational component, i.e., only the oscillating component (revolutionary component) of the eccentric shaft 7, is transmitted to the planetary gear 3. Thus, with the planetary gear 3 combined with the eccentric bearing 5 and eccentric shaft 7, when the eccentric shaft 7 rotates, the planetary gear 3 oscillates around the rotation axis Ax1.

[0083] like Figure 8A and Figure 8B As shown, the support body 8 is a component formed in a ring shape that supports a plurality of inner pins 4. The support body 8 has a plurality of support holes 82 into which the plurality of inner pins 4 are respectively inserted. The number of support holes 82 is the same as the number of inner pins 4; in this embodiment, for example, 18 support holes 82 are provided. Figure 8A and Figure 8BAs shown, each of the plurality of support holes 82 is a circular opening that penetrates the support body 8 along the thickness direction. The plurality of (here, 18) support holes 82 are arranged at equal intervals along the circumferential direction on a virtual circle concentric with the outer peripheral surface 81 of the support body 8. The diameter of the support hole 82 is greater than or equal to the diameter of the inner pin 4 but smaller than the diameter of the inner pin hole 32. In this embodiment, as an example, the diameter of the support hole 82 is equal to the diameter of the retaining hole 611 formed in the inner ring 61.

[0084] like Figure 3 As shown, the support body 8 is arranged opposite the planetary gear 3 from one side (input side) of the rotation axis Ax1. Furthermore, the support body 8 functions to bind the multiple inner pins 4 by inserting them into the multiple support holes 82. In addition, the support body 8 is positionally restricted by contacting the outer peripheral surface 81 with the multiple pins 23. Thus, the support body 8 is centered using the multiple pins 23, resulting in the multiple inner pins 4 supported by the support body 8 also being centered using the multiple pins 23. The support body 8 will be described in detail in the "(3.3) Support Body" section.

[0085] The first bearing 91 and the second bearing 92 are respectively mounted on the central portion 71 of the eccentric shaft 7. Specifically, as shown in the figure... Figure 3 As shown, the first bearing 91 and the second bearing 92 are mounted on both sides of the eccentric portion 72 of the shaft center portion 71 in a direction parallel to the rotation axis Ax1, sandwiching the eccentric portion 72. When viewed from the eccentric portion 72, the first bearing 91 is positioned on the input side of the rotation axis Ax1. When viewed from the eccentric portion 72, the second bearing 92 is positioned on the output side of the rotation axis Ax1. The first bearing 91 holds the eccentric shaft 7 so that it can rotate relative to the housing 10. The second bearing 92 holds the eccentric shaft 7 so that it can rotate relative to the inner ring 61 of the bearing member 6. Thus, the shaft center portion 71 of the eccentric shaft 7 is held rotatable at two locations on both sides of the eccentric portion 72 in a direction parallel to the rotation axis Ax1.

[0086] The housing 10 is cylindrical and has a flange 11 on the output side of the rotating shaft Ax1. Multiple mounting holes 111 are formed in the flange 11 for securing the housing 10 itself. Furthermore, a bearing hole 12 is formed on the end face of the rotating shaft Ax1 on the output side of the housing 10. The bearing hole 12 has a circular opening. The first bearing 91 is mounted to the housing 10 by inserting it into the bearing hole 12.

[0087] Furthermore, a plurality of threaded holes 13 are formed on the end face of the output side of the rotating shaft Ax1 of the housing 10 and around the bearing hole 12. The plurality of threaded holes 13 are used to fix the gear body 22 of the internal gear 2 and the outer ring 62 of the bearing member 6 to the housing 10. Specifically, the fixing screws 60 pass through the through hole 621 of the outer ring 62 and the fixing hole 222 of the gear body 22 and are tightened into the threaded holes 13, thereby fixing the gear body 22 and the outer ring 62 to the housing 10.

[0088] In addition, such as Figure 3 As shown, the gear device 1 of this embodiment also includes multiple oil seals 14, 15, 16, etc. Oil seal 14 is mounted on the input end of the rotating shaft Ax1 of the eccentric shaft 7, filling the gap between the housing 10 and the eccentric shaft 7 (core portion 71). Oil seal 15 is mounted on the output end of the rotating shaft Ax1 of the eccentric shaft 7, filling the gap between the inner ring 61 and the eccentric shaft 7 (core portion 71). Oil seal 16 is mounted on the output end face of the rotating shaft Ax1 of the bearing member 6, filling the gap between the inner ring 61 and the outer ring 62. The space sealed by these multiple oil seals 14, 15, 16 constitutes a lubricant retention space 17 (see reference). Figure 9 The lubricant retention space 17 includes the space between the inner ring 61 and the outer ring 62 of the bearing component 6. In addition, the lubricant retention space 17 houses a plurality of pins 23, a planetary gear 3, an eccentric bearing 5, a support body 8, a first bearing 91, and a second bearing 92, etc.

[0089] Furthermore, a lubricant is sealed in 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, for example, the lubricant enters the meshing part between the internal teeth 21, which is composed of multiple pins 23, and the external teeth 31 of the planetary gear 3. The term "liquid" as used in this embodiment includes liquid or gel-like substances. The term "gel-like" as used herein refers to a state having intermediate properties between liquid and solid, including a colloid state composed of both a liquid phase and a solid phase. For example, emulsions in which the dispersant is a liquid phase and the dispersed substance is a liquid phase, and suspensions in which the dispersed substance is a solid phase, are states referred to as gels or sols, which are included in the term "gel-like". Moreover, states in which the dispersant is a solid phase and the dispersed substance is a liquid phase are also included in the term "gel-like". In this embodiment, as an example, the lubricant is a liquid lubricating oil.

[0090] In the gear assembly 1 described above, a rotational force is applied as input to the eccentric shaft 7, which rotates around the rotation axis Ax1, causing the planetary gear 3 to oscillate (revolve) around the rotation axis Ax1. At this time, the planetary gear 3 oscillates internally to the internal gear 2, with a portion of its external teeth 31 meshing with a portion of its internal teeth 21. Therefore, the meshing position of the internal teeth 21 and 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 of the planetary gear 3 (its rotational component, excluding the oscillation component, of the planetary gear 3) is transmitted to the inner ring 61 of the bearing member 6 via multiple inner pins 4. As a result, a rotational output, reduced at a relatively high reduction ratio corresponding to the difference in the number of teeth between the two gears, can be obtained from the output shaft integrated into the inner ring 61.

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

[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 "52", and the number of teeth V2 of the planetary gear 3 is "51", with a difference in the number of teeth (V1-V2) of "1". Therefore, according to Equation 1 above, the reduction ratio R1 is "51". In this case, when viewed from the input side of the rotating shaft Ax1, if the eccentric shaft 7 rotates clockwise around the rotating shaft Ax1 for one full turn (360 degrees), then the inner ring 61 rotates counterclockwise around the rotating shaft Ax1 by the amount of the tooth difference "1" (approximately 7.06 degrees).

[0094] According to the gear device 1 of this embodiment, such a high reduction ratio R1 can be achieved by a combination of a primary gear (internal gear 2 and planetary gear 3).

[0095] In addition, the gear device 1 only needs to include at least an internal gear 2, a planetary gear 3, multiple internal pins 4, a bearing component 6, and a support body 8, and may also include, for example, a spline bushing as a structural element.

[0096] However, in cases where the input rotation, as in the gear device 1 of this embodiment, is accompanied by eccentric motion and is a high-speed rotating side, vibration or other issues may occur if the weight balance of the rotating body undergoing high-speed rotation is not achieved. Therefore, a counterweight or similar device is sometimes used to achieve weight balance. That is, since the rotating body, composed of at least one of the inner ring 51 of the eccentric body and a component (eccentric shaft 7) that rotates together with the inner ring 51 of the eccentric body, undergoes eccentric motion at high speed, it is preferable to achieve weight balance of this rotating body relative to the rotation axis Ax1. In this embodiment, as... Figure 3 and Figure 4 As shown, the weight balance of the rotating body relative to the rotation axis Ax1 is achieved by providing a gap 75 in a part of the eccentric portion 72 of the eccentric shaft 7.

[0097] In summary, in this embodiment, weight reduction is achieved by thinning a portion of the rotating body (here, the eccentric shaft 7) without adding a counterweight, thereby achieving weight balance of the rotating body relative to the rotation axis Ax1. That is, the gear device 1 of this embodiment includes an eccentric bearing 5 that is housed in the opening 33 formed in the planetary gear 3 and causes the planetary gear 3 to oscillate. The eccentric bearing 5 has an outer eccentric ring 52 and an inner eccentric ring 51 disposed inside the outer eccentric ring 52. The rotating body, composed of at least one of the inner eccentric ring 51 and a component that rotates together with the inner eccentric ring 51, has a gap 75 on a portion of the outer eccentric ring 52 at the center C1 side when viewed from the rotation axis Ax1 of the inner eccentric ring 51. In this embodiment, the eccentric shaft 7 is a "component that rotates together with the inner eccentric ring 51," equivalent to a "rotating body." Therefore, the gap 75 formed in the eccentric portion 72 of the eccentric shaft 7 is equivalent to the gap 75 of the rotating body. Figure 3 and Figure 4 As shown, the gap 75 is located on the side of the center C1 when viewed from the rotation axis Ax1, and thus plays a role in making the weight balance of the eccentric shaft 7 nearly equal from the rotation axis Ax1 to the circumferential direction.

[0098] More specifically, the gap 75 includes a recess formed on the inner circumferential surface of the through hole 73 that passes through the rotating body along the rotation axis Ax1 of the inner ring 51. That is, in this embodiment, the rotating body is the eccentric shaft 7, so the recess formed on the inner circumferential surface of the through hole 73 that passes through the eccentric shaft 7 along the rotation axis Ax1 functions as the gap 75. In this way, by utilizing the recess formed on the inner circumferential surface of the through hole 73 as the gap 75, the weight balance of the rotating body can be achieved without any change in appearance.

[0099] (3.2) The self-rotation structure of domestic sales

[0100] Next, regarding the rotation structure of the inner pin 4 of the gear device 1 in this embodiment, refer to... Figure 9 To explain in more detail. Figure 9 yes Figure 3 A magnified view of region Z1.

[0101] First, as mentioned above, the multiple inner pins 4 are components that connect the planetary gear 3 to the inner ring 61 of the bearing member 6. Specifically, one end of the inner pin 4 in the longitudinal direction (in this embodiment, the end on the input side of the rotating shaft Ax1) is inserted into the inner pin hole 32 of the planetary gear 3, and the other end of the inner pin 4 in the longitudinal direction (in this embodiment, the end on the output side of the rotating shaft Ax1) is inserted into the retaining hole 611 of the inner ring 61.

[0102] Here, the diameter of the inner pin 4 is slightly smaller than the diameter of the inner pin hole 32, thus ensuring a clearance between the inner pin 4 and the inner circumferential surface 321 of the inner pin hole 32. The inner pin 4 can move within the inner pin hole 32, that is, it can move relative to the center of the inner pin hole 32. On the other hand, the diameter of the retaining hole 611 is larger than the diameter of the inner pin 4, but smaller than the diameter of the inner pin hole 32. In this embodiment, the diameter of the retaining hole 611 is approximately the same as the diameter of the inner pin 4, but slightly larger. Therefore, the movement of the inner pin 4 within the retaining hole 611 is restricted; that is, relative movement of the inner pin 4 relative to the center of the retaining hole 611 is prohibited. Therefore, the inner pin 4 is held in the planetary gear 3 in a state where it can revolve within the inner pin hole 32, and in a state where it cannot revolve relative to the inner ring 61 within the retaining hole 611. Thus, the oscillation component of planetary gear 3, that is, the revolution component of planetary gear 3, is absorbed by the inner pin hole 32 and the inner pin 4. Through multiple inner pins 4, the rotation (rotation component) of planetary gear 3, other than the oscillation component (revolution component), is transmitted to the inner ring 61.

[0103] However, in this embodiment, the diameter of the inner pin 4 is slightly larger than that of the retaining hole 611. Therefore, while the inner pin 4 is prohibited from revolving within the retaining hole 611 when inserted, it can rotate within the retaining hole 611. That is, although the inner pin 4 is inserted into the retaining hole 611, it is not pressed into it, and thus it can rotate within the retaining hole 611. In this way, in the gear device 1 of this embodiment, each of the multiple inner pins 4 is held by the inner ring 61 in a state where it can rotate, so when the inner pin 4 revolves within the inner pin hole 32, the inner pin 4 itself can rotate.

[0104] In summary, in this embodiment, the inner pin 4 is maintained in a state where it can both revolve and rotate within the inner pin hole 32 relative to the planetary gear 3, and is maintained in a state where it can only rotate within the retaining hole 611 relative to the inner ring 61. That is, the multiple inner pins 4, in their respective unconstrained rotational state (rotational state), can rotate (revolve) around the rotation axis Ax1, and can revolve within the multiple inner pin holes 32. Therefore, when the rotation (rotational component) of the planetary gear 3 is transmitted to the inner ring 61 using the multiple inner pins 4, the inner pin 4 can revolve and rotate within the inner pin hole 32, and simultaneously rotate within the retaining hole 611. Therefore, when the inner pin 4 revolves within the inner pin hole 32, the inner pin 4 is in a state where it can rotate, and thus rolls relative to the inner circumferential surface 321 of the inner pin hole 32. In other words, the inner pin 4 revolves within the inner pin hole 32 by rolling on the inner circumferential surface 321 of the inner pin hole 32, thus making it difficult to generate losses caused by frictional resistance between the inner circumferential surface 321 of the inner pin hole 32 and the inner pin 4.

[0105] Thus, in this embodiment, since it is inherently difficult to generate losses due to frictional resistance between the inner circumferential surface 321 of the inner pin hole 32 and the inner pin 4, the inner roller can be omitted. Therefore, in this embodiment, each of the multiple inner pins 4 adopts a structure that directly contacts the inner circumferential surface 321 of the inner pin hole 32. That is, in this embodiment, the inner pin 4 without the inner roller is inserted into the inner pin hole 32, and the inner pin 4 directly contacts the inner circumferential surface 321 of the inner pin hole 32. As a result, the inner roller can be omitted, and the diameter of the inner pin hole 32 can be kept relatively small. Therefore, the planetary gear 3 can be miniaturized (especially the diameter can be reduced), and the gear assembly 1 as a whole can also be easily miniaturized. If the size of the planetary gear 3 is fixed, compared with the first related technology described above, for example, the number of inner pins 4 can be increased to make the rotational transmission smoother, or the inner pin 4 can be thickened to increase strength. In addition, the number of components can be reduced to a amount corresponding to the number of inner rollers, which also helps to reduce the cost of the gear assembly 1.

[0106] Furthermore, in the gear assembly 1 of this embodiment, each of the plurality of inner pins 4 has at least a portion disposed in the same position as the bearing member 6 in the axial direction. That is, as shown... Figure 9As shown, in a direction parallel to the rotation axis Ax1, the inner pin 4 has at least a portion positioned at the same location as the bearing member 6. In other words, at least a portion of the inner pin 4 is located between the two end faces of the bearing member 6 in a direction parallel to the rotation axis Ax1. Furthermore, each of the plurality of inner pins 4 has at least a portion positioned inside the outer ring 62 of the bearing member 6. In this embodiment, the output end of the inner pin 4 on the rotation axis Ax1 is positioned at the same location as the bearing member 6 in a direction parallel to the rotation axis Ax1. In summary, the output end of the inner pin 4 on the rotation axis Ax1 is inserted into the retaining hole 611 formed in the inner ring 61 of the bearing member 6, thus at least this end is positioned at the same location as the bearing member 6 in the axial direction.

[0107] In this way, at least a portion of each of the plurality of inner pins 4 is arranged in the same position as the bearing member 6 in the axial direction, thereby reducing the size of the gear device 1 in the direction parallel to the rotation axis Ax1. That is, compared with the structure in which the bearing member 6 and the inner pins 4 are arranged side by side (opposite) in the axial direction of the bearing member 6, the gear device 1 in this embodiment can reduce the size of the gear device 1 in the direction parallel to the rotation axis Ax1, and can contribute to further miniaturization (thinning) of the gear device 1.

[0108] Here, the opening surface of the output side of the rotating shaft Ax1 in the hole 611 is closed, for example, by an output shaft integrated with the inner ring 61. Thus, regarding the output side of the rotating shaft Ax1 via the inner pin 4 ( Figure 9 The movement of the right side is restricted by the output shaft integrated with the inner ring 61.

[0109] Furthermore, in this embodiment, the following structure is adopted to ensure smooth rotation of the inner pin 4 relative to the inner ring 61. Specifically, the rotation of the inner pin 4 is smoothed by placing lubricant (lubricating oil) between the inner circumferential surface of the retaining hole 611 formed in the inner ring 61 and the inner pin 4. In particular, in this embodiment, a lubricant retaining space 17 for lubricant injection exists between the inner ring 61 and the outer ring 62; therefore, the smooth rotation of the inner pin 4 is achieved by utilizing the lubricant within the lubricant retaining space 17.

[0110] In this embodiment, such as Figure 9As shown, the inner ring 61 has: a plurality of retaining holes 611 into which a plurality of inner pins 4 are respectively inserted; and a plurality of connecting paths 64. The plurality of connecting paths 64 connect the lubricant retaining space 17 between the inner ring 61 and the outer ring 62 to the plurality of retaining holes 611. Specifically, a connecting path 64 is formed in the inner ring 61 extending radially from a portion of the inner circumferential surface of the retaining hole 611, i.e., the portion corresponding to the rolling element 63. The connecting path 64 is a hole that passes through the bottom surface of the recess (groove) accommodating the rolling element 63 in the opposing surface of the inner ring 61 opposite to the outer ring 62 and the inner circumferential surface of the retaining hole 611. In other words, the opening surface of the connecting path 64 on the side of the lubricant retaining space 17 is arranged in a position facing (opposing) the rolling element 63 of the bearing member 6. The lubricant retaining space 17 and the retaining hole 611 are spatially connected via such a connecting path 64.

[0111] According to the above structure, since the lubricant holding space 17 is connected to the holding hole 611 by the connecting passage 64, the lubricant in the lubricant holding space 17 is supplied to the holding hole 611 through the connecting passage 64. That is, when the bearing member 6 moves and the rolling element 63 rotates, the rolling element 63 functions as a pump, which can deliver the lubricant in the lubricant holding space 17 to the holding hole 611 through the connecting passage 64. In particular, the opening surface of the connecting passage 64 on the lubricant holding space 17 side is in a position facing (opposite) to the rolling element 63 of the bearing member 6, so that the rolling element 63 effectively functions as a pump when it rotates. As a result, the lubricant is between the inner circumferential surface of the holding hole 611 and the inner pin 4, which enables smooth rotation of the inner pin 4 relative to the inner ring 61.

[0112] (3.3) Support body

[0113] Next, regarding the structure of the support body 8 of the gear device 1 in this embodiment, refer to... Figure 10 To provide a more detailed explanation. Figure 10 yes Figure 3 The sectional view along line B1-B1. However, in Figure 10 In the text, for components other than support body 8, even in cross-sections, section lines are omitted. Furthermore, in... Figure 10 Only the internal gear 2 and the support body 8 are shown in the diagram; other components (such as the inner pin 4) are omitted. Furthermore, in... Figure 10 The inner circumferential surface 221 of the gear body 22 is omitted from the diagram.

[0114] First, as mentioned above, the support body 8 is a component that supports the plurality of inner pins 4. That is, the support body 8 distributes the load acting on the plurality of inner pins 4 when transmitting the rotation (rotation component) of the planetary gear 3 to the inner ring 61 by binding the plurality of inner pins 4. Specifically, it has a plurality of support holes 82 into which the plurality of inner pins 4 are inserted respectively. In this embodiment, as an example, the diameter of the support hole 82 is equal to the diameter of the retaining hole 611 formed in the inner ring 61. Therefore, the support body 8 supports the plurality of inner pins 4 in a state in which each of the plurality of inner pins 4 can rotate on its own axis. That is, each of the plurality of inner pins 4 is held in a state in which it can rotate relative to both the inner ring 61 of the bearing member 6 and the support body 8.

[0115] In this way, multiple inner pins 4 are positioned relative to the support body 8 in both the circumferential and radial directions. That is, the inner pins 4 are restricted from moving in all directions within a plane orthogonal to the rotation axis Ax1 by means of the support holes 82 inserted into the support body 8. Therefore, the inner pins 4 are positioned by the support body 8 not only in the circumferential direction but also in the radial direction.

[0116] Here, the support body 8 has an annular shape with at least its outer peripheral surface 81 being a perfect circle when viewed from above. Furthermore, the support body 8 is positionally constrained by contacting its outer peripheral surface 81 with a plurality of pins 23 in the internal gear 2. Since the plurality of pins 23 constitute the internal teeth 21 of the internal gear 2, in other words, the support body 8 is positionally constrained by contacting its outer peripheral surface 81 with the internal teeth 21. Here, the diameter of the outer peripheral surface 81 of the support body 8 is the same as the diameter of the virtual circle (tip circle) passing through the tip of the internal teeth 21 of the internal gear 2. Therefore, all of the plurality of pins 23 are in contact with the outer peripheral surface 81 of the support body 8. Thus, with the support body 8 positionally constrained by the plurality of pins 23, the center of the support body 8 is positionally constrained in a manner that overlaps with the center (rotation axis Ax1) of the internal gear 2. As a result, the support body 8 is centered, and consequently, the plurality of internal pins 4 supported by the support body 8 are also centered using the plurality of pins 23.

[0117] Furthermore, the multiple inner pins 4 rotate (revolve) around the rotation axis Ax1, thereby transmitting the rotation (rotation component) of the planetary gear 3 to the inner ring 61. Therefore, the support body 8, which supports the multiple inner pins 4, rotates together with the multiple inner pins 4 and the inner ring 61 around the rotation axis Ax1. At this time, the support body 8 is centered by the multiple pins 23, so the support body 8 rotates smoothly with its center maintained on the rotation axis Ax1. Moreover, the support body 8 rotates with its outer circumferential surface 81 in contact with the multiple pins 23, so the multiple pins 23 rotate (rotate) along with the rotation of the support body 8. Thus, the support body 8 and the internal gear 2 together constitute a needle roller bearing (needle roller bearing) and rotate smoothly.

[0118] That is, the outer peripheral surface 81 of the support body 8 rotates relative to the gear body 22 together with the multiple inner pins 4 in a state of tangency to the multiple pins 23. Therefore, if the gear body 22 of the internal gear 2 is regarded as the "outer ring" and the support body 8 as the "inner ring", then the multiple pins 23 between the two function as "rolling elements (rollers)". In this way, the support body 8 and the internal gear 2 (gear body 22 and multiple pins 23) together constitute a needle roller bearing and can rotate smoothly.

[0119] Furthermore, since the support body 8 has multiple pins 23 sandwiched between it and the gear body 22, the support body 8 also functions as a "movement limiter" to inhibit the movement of the pins 23 in the direction of separation from the inner peripheral surface 221 of the gear body 22. That is, the multiple pins 23 are sandwiched between the outer peripheral surface 81 of the support body 8 and the inner peripheral surface 221 of the gear body 22, thereby inhibiting the multiple pins 23 from floating off the inner peripheral surface 221 of the gear body 22. In summary, in this embodiment, each of the multiple pins 23 is restricted from moving in the direction of separation from the gear body 22 by contacting the outer peripheral surface 81 of the support body 8.

[0120] However, in this embodiment, such as Figure 9 As shown, the support body 8 is located on the opposite side of the inner ring 61 of the bearing member 6, separated from the planetary gear 3. That is, the support body 8, the planetary gear 3, and the inner ring 61 are arranged side by side along a direction parallel to the rotation axis Ax1. In this embodiment, as an example, the support body 8 is located on the input side of the rotation axis Ax1 when viewed from the planetary gear 3, and the inner ring 61 is located on the output side of the rotation axis Ax1 when viewed from the planetary gear 3. Furthermore, the support body 8 and the inner ring 61 together support the two ends of the inner pin 4 in the length direction (the direction parallel to the rotation axis Ax1), and the central portion of the inner pin 4 in the length direction is inserted through the inner pin hole 32 of the planetary gear 3. In summary, the gear device 1 of this embodiment includes a bearing member 6, which has an outer ring 62 and an inner ring 61 disposed inside the outer ring 62, and the inner ring 61 is supported so as to be able to rotate relative to the outer ring 62. Furthermore, the gear body 22 is fixed to the outer ring 62. Here, the planetary gear 3 is located between the support body 8 and the inner ring 61 in the axial direction of the support body 8.

[0121] According to this structure, the support body 8 and the inner ring 61 support the two ends of the inner pin 4 in the longitudinal direction, thus making it difficult for the inner pin 4 to tilt. In particular, it is also easy to withstand the bending force (bending moment load) acting on the multiple inner pins 4 relative to the rotating shaft Ax1. Moreover, in this embodiment, the support body 8 is sandwiched between the planetary gear 3 and the housing 10 in a direction parallel to the rotating shaft Ax1. As a result, the support body 8 is directed towards the input side of the rotating shaft Ax1 ( Figure 9The movement of the left side is restricted by the housing 10. Regarding the support hole 82 penetrating the support body 8 and the inner pin 4 protruding from the support body 8 towards the input side of the rotating shaft Ax1, the movement of the inner pin 4 towards the input side of the rotating shaft Ax1 is restricted. Figure 9 The movement of the left side is also restricted by the housing 10.

[0122] In this embodiment, the support body 8 and the inner ring 61 also contact the two ends of the plurality of pins 23. That is, as shown in the figure Figure 9 As shown, the support body 8 contacts one end of the pin 23 along its length (parallel to the rotation axis Ax1) (the input end of the rotation axis Ax1). The inner ring 61 contacts the other end of the pin 23 along its length (parallel to the rotation axis Ax1) (the output end of the rotation axis Ax1). With this structure, the support body 8 and the inner ring 61 are centered at both ends along the length of the pin 23, thus preventing tilting of the inner pin 4. In particular, it easily withstands bending forces (bending moment loads) acting on the rotation axis Ax1 from the multiple inner pins 4.

[0123] Furthermore, the multiple pins 23 have a length exceeding the thickness of the support body 8. In other words, the support body 8 is contained within the tooth direction of the internal teeth 21 in the direction parallel to the rotation axis Ax1. As a result, the outer peripheral surface 81 of the support body 8 contacts the multiple pins 23 along the entire length of the tooth direction of the internal teeth 21 (the direction parallel to the rotation axis Ax1). Therefore, it is difficult to produce an undesirable condition such as "unilateral wear" where the outer peripheral surface 81 of the support body 8 is partially worn.

[0124] Furthermore, in this embodiment, the surface roughness of the outer peripheral surface 81 of the support 8 is smaller than that of the surface adjacent to the outer peripheral surface 81 of the support 8. That is, the surface roughness of the outer peripheral surface 81 is smaller than that of the two end faces of the support 8 in the axial (thickness direction). The term "surface roughness" as used in this embodiment refers to the roughness of the surface of an object; the smaller the value, the less unevenness (roughness) the surface, and the smoother it is. In this embodiment, as an example, the surface roughness is set to the arithmetic mean roughness (Ra). For example, through processes such as grinding, the surface roughness of the outer peripheral surface 81 is smaller than that of the surfaces other than the outer peripheral surface 81 in the support 8. In this structure, the rotation of the support 8 becomes smoother.

[0125] Furthermore, in this embodiment, the hardness of the outer peripheral surface 81 of the support 8 is lower than that of the peripheral surfaces of the plurality of pins 23 and higher than that of the inner peripheral surface 221 of the gear body 22. The term "hardness" as used in this embodiment refers to the degree of hardness of an object; the hardness of a metal is, for example, expressed by the size of the indentation formed when a steel ball is pressed under a certain pressure. Specifically, examples of metal hardness include Rockwell hardness (HRC), Brinell hardness (HB), Vickers hardness (HV), or Shore hardness (Hs). Methods for increasing the hardness (hardening) of metal parts include, for example, alloying or heat treatment. In this embodiment, as an example, the hardness of the outer peripheral surface 81 of the support 8 is increased by treatments such as carburizing and quenching. In this structure, even due to the rotation of the support 8, wear particles are unlikely to be generated, and the smooth rotation of the support 8 can be easily maintained for a long period.

[0126] (4) Applicable examples

[0127] Next, an applicable example of the gear device 1 and actuator 100 of this embodiment will be described.

[0128] The gear device 1 and actuator 100 of this embodiment are applicable, for example, to horizontal multi-joint robots, such as robots with a so-called Selective Compliance Assembly Robot Arm (SCARA) type.

[0129] Furthermore, the application examples of the gear device 1 and actuator 100 in this embodiment are not limited to horizontal articulated robots as described above. For example, they can also be industrial robots or robots other than horizontal articulated robots. Among industrial robots other than horizontal articulated robots, examples include vertical articulated robots or parallel link robots. Among robots other than industrial robots, examples include home robots, nursing robots, or medical robots.

[0130] (5) Variations

[0131] The above-described embodiments are merely one example of various implementations of the present disclosure. Various modifications can be made to the above-described embodiments based on design, etc., as long as the objectives of the present invention are achieved. Furthermore, the accompanying drawings referenced in the embodiments of this disclosure are schematic diagrams, and the size and thickness ratios of the structural elements in the drawings may not necessarily reflect the actual dimensional ratios. Hereinafter, variations of the above-described embodiments are listed. The variations described below can be appropriately combined and applied.

[0132] In the above embodiment, a gear device 1 of the type with one planetary gear 3 is illustrated; however, the gear device 1 may include multiple planetary gears 3. For example, when the gear device 1 includes two planetary gears 3, it is preferable that these two planetary gears 3 are arranged with a phase difference of 180 degrees around the rotation axis Ax1. Furthermore, when the gear device 1 includes three planetary gears 3, it is preferable that these three planetary gears 3 are arranged with a phase difference of 120 degrees around the rotation axis Ax1. In this way, when the multiple planetary gears 3 are evenly arranged circumferentially around the rotation axis Ax1, weight balance among the multiple planetary gears 3 can be achieved.

[0133] Furthermore, the plurality of inner pins 4 are each configured, at least a portion of which is axially aligned with the bearing member 6 at the same position as the bearing member 6; this is not a necessary feature in the gear assembly 1. That is, the gear assembly 1 only needs to include the bearing member 6, the internal gear 2, the planetary gear 3, and the plurality of inner pins 4. The bearing member 6 has an outer ring 62 and an inner ring 61 disposed inside the outer ring 62. The inner ring 61 is supported so as to be rotatable relative to the outer ring 62. The gear body 22 of the internal gear 2 is fixed to the outer ring 62. The plurality of inner pins 4 are each held in a rotatable state within the inner ring 61. Here, the plurality of inner pins 4 may be arranged side-by-side (opposite) to the bearing member 6 axially.

[0134] Furthermore, the number of internal pins 4, the number of pins 23 (the number of teeth of internal teeth 21), and the number of teeth of external teeth 31 described in the above embodiments are merely examples and can be appropriately changed.

[0135] Furthermore, the bearing component 6 is not limited to crossed roller bearings, but can be a deep groove ball bearing or an angular contact ball bearing, etc. However, the bearing component 6 is preferably a four-point contact ball bearing, etc., which can withstand radial loads, thrust loads (in the direction along the rotation axis Ax1), and bending forces (bending moment loads) on the rotation axis Ax1.

[0136] Furthermore, the eccentric bearing 5 is not limited to deep groove ball bearings; for example, it can be an angular contact ball bearing. Moreover, the eccentric bearing 5 is not limited to ball bearings; for example, it can be a roller bearing such as a cylindrical roller bearing, a needle roller bearing, or a tapered roller bearing, where the rolling elements 53 are composed of non-spherical "rollers".

[0137] Furthermore, the materials of the various structural elements of the gear device 1 are not limited to metal; for example, they can be resins such as engineering plastics.

[0138] Furthermore, the gear device 1 is not limited to a structure that can output the relative rotation between the inner ring 61 and the outer ring 62 of the bearing member 6, or output the rotational force of the inner ring 61. For example, the rotational force of the outer ring 62, which rotates relative to the inner ring 61, can also be output.

[0139] In addition, lubricants are not limited to liquid substances such as lubricating oil (oil), but can also be gel-like substances such as lubricating grease.

[0140] Alternatively, the gear assembly 1 may include internal rollers. That is, in the gear assembly 1, it is not necessary for each of the multiple internal pins 4 to be in direct contact with the inner circumferential surface 321 of the internal pin hole 32; internal rollers may also be sandwiched between each of the multiple internal pins 4 and the internal pin hole 32. In this case, the internal rollers are assembled to the internal pins 4 and can rotate about the internal pins 4 as an axis.

[0141] Furthermore, each of the plurality of inner pins 4 only needs to have at least a portion disposed in the same position as the bearing member 6 in the axial direction. Therefore, as in the embodiment described above, each of the plurality of inner pins 4 may have only one end in the longitudinal direction disposed in the same position as the bearing member 6 in the axial direction, while the other end in the longitudinal direction protrudes from the bearing member 6. Alternatively, each of the plurality of inner pins 4 may be entirely contained within the bearing member 6 in the axial direction.

[0142] Furthermore, each of the multiple inner pins 4 only needs to be held in a self-rotating state within the inner ring 61; it is not necessary for the multiple inner pins 4 to be directly held by the inner ring 61. For example, each of the multiple inner pins 4 can be indirectly held by the inner ring 61 by inserting into a holding hole formed on an output shaft or bracket integrated with the inner ring 61.

[0143] Furthermore, the means to ensure smooth rotation of the inner pin 4 relative to the inner ring 61 are not limited to a structure in which lubricant in the lubricant retention space 17 between the inner ring 61 and the outer ring 62 is supplied to the retaining hole 611 via the connecting passage 64. For example, even if the lubricant retention space 17 between the inner ring 61 and the outer ring 62 is not connected to the retaining hole 611, smooth rotation of the inner pin 4 can be achieved by injecting lubricant into the retaining hole 611. Alternatively, smooth rotation of the inner pin 4 can be achieved by using a bearing fitted within the retaining hole 611.

[0144] Furthermore, the positioning of multiple inner pins 4 relative to the support body 8 in both the circumferential and radial directions is not necessarily required in the gear device 1. For example, the support body 8 may have a slit-shaped support hole 82 extending radially, with the multiple inner pins 4 positioned relative to the support body 8 only in the circumferential direction. Conversely, the support body 8 may also have multiple inner pins 4 positioned relative to the support body 8 only in the radial direction.

[0145] Furthermore, in the above embodiment, as a structure for achieving weight balance of the rotating body undergoing eccentric motion relative to the rotation axis Ax1, a recessed cavity 75 formed in the rotating body (eccentric shaft 7) is exemplified; however, the shape of the cavity 75 is not limited to this. For example, the cavity 75 can be formed in the inner ring 51 of the eccentric body, or in both the inner ring 51 and the eccentric shaft 7. The cavity 75 may include a recess formed outside the inner circumferential surface of the through hole 73. Additionally, the cavity 75 may also include a hole.

[0146] Another embodiment of the internal meshing planetary gear device 1A (hereinafter also simply referred to as "gear device 1A") is as follows: Figure 11 As shown, the shape of the inner pin 4 differs from that of the gear device 1 in the above embodiment. Hereinafter, for structures identical to those in the above embodiment, the same reference numerals will be used, and descriptions will be omitted as appropriate.

[0147] In the gear device 1A of this embodiment, each of the plurality of inner pins 4 has a narrow diameter portion 41 in a portion thereof. The narrow diameter portion 41 is a portion (neck) with a smaller diameter than other portions of the inner pin 4, i.e., portions other than the narrow diameter portion 41. In this embodiment, such a narrow diameter portion 41 is particularly provided at a position facing (opposite) to the opening surface on the side of the retaining hole 611 of the connecting passage 64. In short, each of the plurality of inner pins 4 has a narrow diameter portion 41 with a smaller diameter than other portions at a position corresponding to the connecting passage 64.

[0148] According to this structure, the lubricant in the lubricant holding space 17 can be easily fed into the holding hole 611 via the connecting path 64. That is, by providing the narrow diameter portion 41, the gap between the outer peripheral surface of the inner pin 4 (narrow diameter portion 41) and the inner peripheral surface of the holding hole 611 is widened, ensuring space on the outlet side of the connecting path 64, i.e., the holding hole 611 side. As a result, when the path from the lubricant holding space 17 to the holding hole 611 via the connecting path 64 is considered as a hydraulic circuit, the resistance in the hydraulic circuit is reduced, and when the rolling element 63 functions as a pump, it is easy to feed the lubricant into the holding hole 611. Furthermore, the lubricant fed into the holding hole 611 can be expected to expand along the length direction of the holding hole 611 (the direction parallel to the rotation axis Ax), for example, through capillary action. Therefore, the lubricant between the inner peripheral surface of the holding hole 611 and the inner pin 4 is unlikely to be insufficient, and the smooth rotation of the inner pin 4 relative to the inner ring 61 is easily achieved.

[0149] As a variation of this embodiment, the narrow diameter portion 41 can be formed at multiple locations along the length of the inner pin 4. Furthermore, the inner pin 4 can have, for example, a tapered or stepped narrow diameter portion 41 whose diameter gradually increases along the length of the inner pin 4.

[0150] The structure of this embodiment (including modifications) can be appropriately combined with the structure (including modifications) described in the above embodiments.

[0151] (Summarize)

[0152] As described above, the first-type internal meshing planetary gear assembly (1, 1A) includes a bearing member (6), an internal gear (2), a planetary gear (3), and a plurality of inner pins (4). The bearing member (6) has an outer ring (62) and an inner ring (61) disposed inside the outer ring (62), the inner ring (61) being supported so as to be able to rotate relative to the outer ring (62). The internal gear (2) has internal teeth (21) and is fixed to the outer ring (62). The planetary gear (3) has external teeth (31) that partially mesh with the internal teeth (21). The plurality of inner pins (4), in a state of being respectively inserted into a plurality of inner pin holes (32) formed in the planetary gear (3), revolve within the inner pin holes (32) and rotate relative to the internal gear (2). Multiple inner pins (4) are each held in the inner ring (61) in a rotatable state, and each of the multiple inner pins (4) is at least a portion of itself arranged in the same position as the bearing member (6) in the axial direction.

[0153] According to this configuration, each of the multiple inner pins (4) is held in the inner ring (61) in a state where it can rotate on its own axis. Therefore, when the inner pins (4) revolve within the inner pin holes (32), the inner pins (4) themselves can rotate. Thus, even without using inner rollers that are mounted on the inner pins (4) and can rotate around the inner pins (4), losses caused by frictional resistance between the inner circumferential surface (321) of the inner pin holes (32) and the inner pins (4) can be reduced. Therefore, it is not necessary to provide inner rollers, which has the advantage of easy miniaturization.

[0154] In the second form of the internal meshing planetary gear device (1, 1A), based on the first form, multiple inner pins (4) are in direct contact with the inner circumferential surface (321) of the inner pin hole (32).

[0155] Based on this configuration, it is easy to miniaturize the material without the corresponding amount of internal rollers.

[0156] In the third form of the internal meshing planetary gear assembly (1, 1A), based on the first or second form, the inner ring (61) has: a plurality of retaining holes (611) for inserting a plurality of inner pins (4); and a plurality of connecting paths (64). The plurality of connecting paths (64) connect the lubricant retention space (17) between the inner ring (61) and the outer ring (62) to the plurality of retaining holes (611).

[0157] According to this configuration, the lubricant in the lubricant holding space (17) can be supplied to the holding hole (611) via the connecting path (64).

[0158] In the fourth form of the internal meshing planetary gear device (1, 1A), based on the third form, each of the multiple internal pins (4) has a smaller diameter portion (41) at a position corresponding to the connecting path (64) compared to other parts.

[0159] According to this method, the lubricant in the lubricant holding space (17) can be easily supplied to the holding hole (611) via the connecting path (64).

[0160] The fifth type of internal meshing planetary gear assembly (1, 1A), based on any one of the first to fourth types, further includes a support body (8), which is annular and supports multiple internal pins (4). The internal gear (2) has: an annular gear body (22); and multiple pins (23) that are held in a rotatable state on the inner circumferential surface (221) of the gear body (22) and form internal teeth (21). The support body (8) is positionally restricted by contacting the multiple pins (23) with its outer circumferential surface (81).

[0161] According to this configuration, the multiple inner pins (4) are bound together by the support body (8), which can suppress the relative displacement and tilting of the multiple inner pins (4). Moreover, the outer peripheral surface (81) of the support body (8) contacts the multiple pins (23), thereby restricting the position of the support body (8). In summary, by centering the support body (8) with the multiple pins (23), it is possible to center the multiple inner pins (4) supported by the support body (8) using the multiple pins (23). Therefore, there are advantages such as: it is easy to improve the centering accuracy of the multiple inner pins (4), and it is difficult to produce adverse conditions caused by poor centering of the multiple inner pins (4).

[0162] The sixth form of the internal meshing planetary gear device (1, 1A), based on any one of the first to fifth forms, further includes an eccentric bearing (5), which is received in the opening (33) formed in the planetary gear (3) and causes the planetary gear (3) to oscillate. The eccentric bearing (5) has an eccentric outer ring (52) and an eccentric inner ring (51) disposed inside the eccentric outer ring (52). The rotating body, consisting of at least one of the eccentric inner ring (51) and a component that rotates together with the eccentric inner ring (51), has a gap (75) on a portion of the side of the center (C1) of the eccentric outer ring (52) when viewed from the rotation axis (Ax1) of the eccentric inner ring (51).

[0163] Based on this configuration, it is easy to achieve weight balance around the rotation axis (Ax1) of the rotating body.

[0164] In the seventh form of the internal meshing planetary gear device (1, 1A), based on the sixth form, the gap (75) is contained in the recess formed on the inner circumferential surface of the through hole (73) of the rotating body through the rotation axis (Ax1) along the inner ring (51) of the eccentric body.

[0165] Based on this configuration, it is easy to achieve weight balance around the rotation axis (Ax1) of the rotating body.

[0166] In the eighth form of the internal meshing planetary gear device (1, 1A), based on any one of the first to seventh forms, the bearing component (6) is a crossed roller bearing.

[0167] According to this configuration, the bearing component (6) can easily withstand any of the radial load, the thrust load, and the bending force relative to the rotating shaft (Ax1).

[0168] The actuator (100) of the ninth form includes: an internal meshing planetary gear device (1, 1A) of any one of the first to eighth forms; and a drive source (101) that generates a driving force for oscillating the planetary gear (3).

[0169] Based on this form, it has the advantage of being easy to miniaturize.

[0170] Regarding the structures of the second to eighth forms, these are not essential for the internal meshing planetary gear devices (1, 1A) and can be omitted appropriately.

[0171] Explanation of reference numerals in the attached figures

[0172] 1.1A Internal Meshing Planetary Gear Assembly

[0173] 2 Internal gears

[0174] 3 planetary gears

[0175] 4. Domestic sales

[0176] 5 Eccentric Bearings

[0177] 6 bearing components

[0178] 8 Support bodies

[0179] 21 internal teeth

[0180] 22 Gear Body

[0181] 23 sales

[0182] 31 external teeth

[0183] 32-hole inner pin

[0184] 33 opening

[0185] 51 eccentric inner circle

[0186] 52 eccentric outer circle

[0187] 61 Inner Circle

[0188] 62 outer ring

[0189] 73 through holes

[0190] 75 gap

[0191] 81 outer perimeter

[0192] 100 actuators

[0193] 101 driver source

[0194] 221 (inner circumferential surface of the gear body)

[0195] Ax1 Rotational Axis

[0196] C1 Center

[0197] Industrial applicability

[0198] According to embodiments of this disclosure, an internal meshing planetary gear device and actuator that are easily miniaturized can be provided.

Claims

1. An internal meshing planetary gear device, wherein, include: A bearing component having an outer ring and an inner ring disposed inside the outer ring, the inner ring being supported to be rotatable relative to the outer ring; An internal gear having internal teeth and fixed to the outer ring; A planetary gear having external teeth that partially mesh with the internal teeth; and Multiple inner pins, respectively inserted into multiple inner pin holes formed in the planetary gear, revolve within the inner pin holes and rotate relative to the internal gear. Each of the plurality of inner pins is held in the inner ring in a rotatable state, so that the inner pins revolve within the inner pin hole by rolling on the inner circumferential surface of the inner pin hole, and Each of the plurality of inner pins is configured, at least a portion thereof, in the axial direction of the bearing member at the same position as the bearing member.

2. The internal meshing planetary gear device according to claim 1, wherein, Each of the plurality of inner pins is in direct contact with the inner circumferential surface of the inner pin hole.

3. The internal meshing planetary gear device according to claim 1 or 2, wherein, The inner ring has: Multiple retaining holes for the insertion of the multiple inner pins; and Multiple connecting paths connect the lubricant retention space between the inner ring and the outer ring to the multiple retaining holes.

4. The internal meshing planetary gear device according to claim 3, wherein, Each of the plurality of inner pins has a smaller diameter portion at a position corresponding to the connecting path, compared to other parts.

5. The internal meshing planetary gear device according to claim 1 or 2, wherein, The internal meshing planetary gear assembly also includes a support body, which is annular and supports the plurality of internal pins. The internal gear has: an annular gear body; and a plurality of pins that are held on the inner circumferential surface of the gear body in a rotatable state and form the internal teeth. The support body is positioned by contacting its outer peripheral surface with the plurality of pins.

6. The internal meshing planetary gear device according to claim 1 or 2, wherein, The internal meshing planetary gear assembly also includes an eccentric bearing, which is received in an opening formed in the planetary gear and causes the planetary gear to oscillate. The eccentric bearing has an eccentric outer ring and an eccentric inner ring disposed inside the eccentric outer ring. A rotating body consisting of at least one of the inner ring of the eccentric body and a component that rotates together with the inner ring of the eccentric body has a gap on a portion of the central side of the outer ring of the eccentric body when viewed from the axis of rotation of the inner ring of the eccentric body.

7. The internal meshing planetary gear device according to claim 6, wherein, The gap is contained in a recess formed on the inner circumferential surface of a through hole that passes through the rotating body along the rotation axis of the inner ring of the eccentric body.

8. The internal meshing planetary gear device according to claim 1 or 2, wherein, The bearing component is a crossed roller bearing.

9. An actuator, wherein, include: The internal meshing planetary gear device according to any one of claims 1 to 8; and A drive source that generates the driving force to make the planetary gears oscillate.

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