Internal gear planetary gear device and joint device for robots

Abstract

The present disclosure provides an internal meshing planetary gear device and a robot joint device that are easily downsized. An internal meshing planetary gear device (1A) includes a bearing member (6A), an internal tooth gear (2), a planetary gear (3), a plurality of internal pins (4), and a plurality of sets of rolling bearings (41, 42). The plurality of internal pins (4) relatively rotate with respect to the internal tooth gear (2) while orbiting within internal pin holes (32) in a state of being inserted into the plurality of internal pin holes (32) formed in the planetary gear (3). The plurality of sets of rolling bearings (41, 42) hold each of the plurality of internal pins (4) with respect to the planetary gear (3) at both sides in a direction parallel to a rotation axis Ax1. Each of the plurality of internal pins (4) is held in a state of being able to rotate on its own in each set of rolling bearings (41, 42).

Description

[0001] Cross-reference to related applications

[0002] This application is based on and claims priority to Japanese Patent Application No. 2021-030510, filed on February 26, 2021, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This disclosure generally relates to internal meshing planetary gear devices and robot joint devices, and more specifically, to internal meshing planetary gear devices and robot joint devices 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 oscillates eccentrically while meshing internally with an internal gear (for example, see Patent Document 1). In the gear device of the related technology, the eccentric body is integrally formed with the input shaft, and the 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 crossed roller bearings. This gear assembly can be used as a gear assembly that removes the planetary gear from the support by rotating the equivalent of its rotational component when the internal gear is fixed.

[0006] Existing technical documents

[0007] Patent documents

[0008] Patent Document 1: Japanese Patent Application Publication No. 2003-74646 Summary of the Invention

[0009] The technical problem that the invention aims to solve

[0010] 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.

[0011] The purpose of this disclosure is to provide an internally meshing planetary gear device and a joint device for robots that are easily miniaturized.

[0012] Solutions for solving technical problems

[0013] An embodiment of the internal meshing planetary gear device disclosed herein includes a bearing member, an internal gear, a planetary gear, a plurality of inner pins, and a plurality of rolling bearings. The bearing member has an outer ring and an inner ring disposed inside the outer ring, supporting the inner ring so that it can rotate relative to the outer ring about a rotation axis. 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, when respectively inserted into a plurality of inner pin holes formed in the planetary gear, revolve within the inner pin holes while rotating relative to the internal gear. The plurality of rolling bearings hold each of the plurality of inner pins on both sides of the planetary gear in a direction parallel to the rotation axis. Each of the plurality of inner pins is held in its respective rolling bearing in a rotatable state.

[0014] One embodiment of the present disclosure provides a robot joint device including the internally meshing planetary gear assembly, a first member fixed to the outer ring, and a second member fixed to the inner ring.

[0015] Invention Effects

[0016] According to embodiments of this disclosure, it is possible to provide an internally meshing planetary gear device and a joint device for robots that are easily miniaturized. Attached Figure Description

[0017] Figure 1 This is a perspective view showing the schematic structure of an actuator, including the internal meshing planetary gear mechanism with its basic structure.

[0018] 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.

[0019] Figure 3 This is a schematic cross-sectional view of the aforementioned internal meshing planetary gear assembly.

[0020] Figure 4 This illustrates the aforementioned internal meshing planetary gear mechanism. Figure 3 Sectional view along line A1-A1.

[0021] Figure 5A This is a perspective view of the planetary gears of the aforementioned internal meshing planetary gear assembly, shown as a single unit.

[0022] Figure 5B This is a front view of the planetary gears of the aforementioned internal meshing planetary gear assembly, shown as a single unit.

[0023] Figure 6AThis is a perspective view of the bearing component of the aforementioned internal meshing planetary gear assembly.

[0024] Figure 6B This is a front view showing the bearing component of the aforementioned internal meshing planetary gear assembly.

[0025] Figure 7A This is a perspective view of the eccentric shaft of the aforementioned internal meshing planetary gear device.

[0026] Figure 7B This is a front view of the eccentric shaft of the aforementioned internal meshing planetary gear assembly, shown as a single unit.

[0027] Figure 8A This is a perspective view of the support body of the aforementioned internal meshing planetary gear device.

[0028] Figure 8B This is a front view of the support body of the aforementioned internal meshing planetary gear device, shown as a single unit.

[0029] Figure 9 This illustrates the aforementioned internal meshing planetary gear mechanism. Figure 3 A magnified view of region Z1.

[0030] Figure 10 This illustrates the aforementioned internal meshing planetary gear mechanism. Figure 3 Sectional view along line B1-B1.

[0031] Figure 11 This is a schematic cross-sectional view of the internal meshing planetary gear device according to Embodiment 1.

[0032] Figure 12A This illustrates the aforementioned internal meshing planetary gear mechanism. Figure 11 A rough enlarged view of region Z1.

[0033] Figure 12B This illustrates the aforementioned internal meshing planetary gear mechanism. Figure 12A Sectional view along line A1-A1.

[0034] Figure 13 The aforementioned internal meshing planetary gear mechanism is shown schematically. Figure 12A A diagram illustrating the forces acting under certain conditions.

[0035] Figure 14 This is a side view of the aforementioned internal meshing planetary gear device, viewed from the output side of the rotating shaft.

[0036] Figure 15 This is a side view of the aforementioned internal meshing planetary gear device, viewed from the input side of the rotating shaft.

[0037] Figure 16 This illustrates the aforementioned internal meshing planetary gear mechanism. Figure 11 Sectional view along line A1-A1.

[0038] Figure 17 This illustrates the aforementioned internal meshing planetary gear mechanism. Figure 11 Sectional view along line B1-B1.

[0039] Figure 18 This is an explanatory diagram showing the arrangement of rolling bearings in the aforementioned internal meshing planetary gear assembly.

[0040] Figure 19 This is a schematic cross-sectional view of a robot joint device that uses the aforementioned internal meshing planetary gear mechanism. Detailed Implementation

[0041] (Basic Structure)

[0042] (1) Summary

[0043] The following is for reference Figures 1-3 A summary of the internal meshing planetary gear device 1 with respect to its basic structure is provided. The accompanying drawings, which are used in the embodiments of this disclosure, are schematic diagrams, and the proportions of the size and thickness of the structural elements shown may not reflect the actual dimensional proportions. 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.

[0044] The internal meshing planetary gear assembly 1 (hereinafter also simply referred to as "gear assembly 1") of this basic structure is a gear assembly including an internal gear 2, a planetary gear 3, and multiple 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). Figure 3 The rotation axis Ax1 is deviated (refer to) Figure 3 The 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, which has an outer ring 62 and an inner ring 61. The inner ring 61 is disposed inside the outer ring 62 and is supported so that it can rotate relative to the outer ring 62.

[0045] The internal gear 2 has internal teeth 21 and is fixed to the outer ring 62. Specifically, in this basic structure, the internal gear 2 has an annular gear body 22 and multiple pins 23. The multiple pins 23 are held in a rotatable state on the inner circumferential surface 221 of the gear body 22, thus forming the internal teeth 21. The planetary gear 3 has external teeth 31 that partially mesh with the internal teeth 21. That is, inside the internal gear 2, the planetary gear 3 is tangent to the internal gear 2, becoming a part of the external teeth 31 meshing with a part of the internal teeth 21. In this state, when 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 circumference 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 in speed at a relatively high reduction ratio is obtained from planetary gear 3, corresponding to the difference in the number of teeth between the two gears.

[0046] 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 this basic structure of the gear device 1, multiple inner pins 4 are used to connect the planetary gear 3 to the inner ring 61 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. The multiple inner pins 4, each inserted into a plurality of inner pin holes 32 formed in the planetary gear 3, rotate relative to the internal gear 2 while revolving within the inner pin holes 32. That is, the inner pin holes 32 have a diameter larger than the inner pins 4, allowing the inner pins 4 to move while revolving within the inner pin holes 32 while inserted. Furthermore, the oscillating component of the planetary gear 3, that is, the revolving component of the planetary gear 3, is absorbed by the interlocking of the inner pins 4 with the inner pin holes 32 of the planetary gear 3. In other words, the multiple inner pins 4 move by revolving 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.

[0047] However, in this gear device 1, the inner pin 4 revolves within the inner pin hole 32 of the planetary gear 3 while transmitting 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 and capable of rotating 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 integral 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 basic structure can provide an internal meshing planetary gear assembly 1 that is easily miniaturized through the following structure.

[0048] That is, such as Figures 1-3 As shown, the gear assembly 1 of this basic structure 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, while 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. Here, each of the plurality of inner pins 4 is held in a rotatable state within the inner ring 61. 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.

[0049] According to this configuration, each of the multiple inner pins 4 is held by the inner ring 61 in a rotatable state, so that the inner pins 4 can rotate on their own while revolving within the inner pin holes 32. Therefore, even without using inner rollers mounted on the inner pins 4 and capable of rotating 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, for the gear assembly 1 of this basic structure, inner rollers are not necessary, thus offering the advantage of easy miniaturization. Moreover, each of the multiple inner pins 4 is at least partially positioned in the same axial direction as the bearing member 6, thus reducing the size of the gear assembly 1 in the axial direction of the bearing member 6. In other words, compared to a structure in which the bearing member 6 and the inner pins 4 are arranged side-by-side (opposite) along the axial direction of the bearing member 6, the size of the gear assembly 1 in this basic structure can be reduced, thereby contributing to further miniaturization (thinning) of the gear assembly 1.

[0050] 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.

[0051] 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 correlation 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 correlation 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 while rotating 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 rotation axis of the multiple inner pins 4 deviates or tilts relative to the rotation axis of the inner ring 61 due to insufficient centering accuracy, 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 basic structure provides 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.

[0052] Right now, Figures 1-3As shown, the gear assembly 1 of this basic structure includes an internal gear 2, a planetary gear 3, multiple inner pins 4, and a support body 8. 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 to form internal teeth 21. The planetary gear 3 has external teeth 31 that partially mesh with the internal teeth 21. 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 while rotating relative to the gear body 22. The support body 8 is annular and supports the multiple inner pins 4. Here, the support body 8 is positionally restricted by contacting the multiple pins 23 with its outer circumferential surface 81.

[0053] 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, suppressing 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, 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. Therefore, the gear device 1 with this basic structure 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.

[0054] In addition, such as Figure 1 As shown, the gear assembly 1 and the drive source 101 together constitute the actuator 100 of this basic structure. In other words, the actuator 100 of this basic structure includes the gear assembly 1 and the drive source 101. The drive source 101 generates a driving force for oscillating the planetary gear 3. Specifically, the drive source 101 causes the eccentric shaft 7 to rotate about the rotation axis Ax1, thereby causing the planetary gear 3 to oscillate.

[0055] (2) Definition

[0056] In this embodiment of the disclosure, "ring-shaped" refers to a shape that forms a circle (ring) enclosing a space (region) on the inside, at least when viewed from above. It is not limited to a circular shape (ring-shaped) that is perfectly round when viewed from above; for example, it can also be an elliptical shape or a polygonal shape. Furthermore, for example, even a shape with a bottom, such as a cup, is included in "ring-shaped" as long as its peripheral wall is ring-shaped.

[0057] In this embodiment, "playing" refers to a state where the pin 4 is fitted with a clearance, and the inner pin hole 32 is a hole for the inner pin 4 to play. 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 the portion of the inner pin 4 that is inserted into the inner pin hole 32 is smaller (thinner) 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 in this clearance.

[0058] In this embodiment of the disclosure, "revolution" refers to an object revolving around an axis of rotation other than the central axis passing through the object's center (center of gravity). When an object revolves, its center moves along a revolution path centered on the axis of rotation. Therefore, for example, when an object rotates around an eccentric axis parallel to the central axis passing through its center (center of gravity), the object revolves around the eccentric axis. As an example, the inner pin 4 revolves within the inner pin hole 32, revolving around an axis of rotation passing through the center of the inner pin hole 32.

[0059] Additionally, in this embodiment of the disclosure, 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 referred to as 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.

[0060] In this embodiment, the term "rotation axis" refers to a virtual axis (straight line) that serves as the center of rotational motion of the rotating body. That is, rotation axis Ax1 is a virtual axis without a physical component. The inner ring 51 of the eccentric body rotates around rotation axis Ax1.

[0061] In the embodiments of this 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 disposed on the inner circumferential surface 221 of the internal gear 2 (gear body 22). Similarly, the external teeth 31 of the planetary gear 3 are composed of a collection of multiple teeth disposed on the outer circumferential surface of the planetary gear 3.

[0062] (3) Structure

[0063] The detailed structure of the internal meshing planetary gear device 1 of this basic structure is described below, referring to... Figures 1 to 8B Please provide an explanation.

[0064] 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, regarding 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 The perspective view and front view of planetary gear 3 are shown as a single unit. Figure 6A and Figure 6B The three-dimensional view and front view of bearing component 6 are shown as a single unit. Figure 7A and Figure 7B The diagram shows a three-dimensional view and a front view of the eccentric shaft 7 as a single unit. Figure 8A and Figure 8B The support body 8 is shown as a single unit, including a perspective view and a front view.

[0065] (3.1) Overall Structure

[0066] like Figures 1-3 As shown, the gear assembly 1 of this basic structure 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 basic structure, the gear assembly 1 also includes a first bearing 91, a second bearing 92, and a housing 10. In this basic structure, 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.

[0067] Furthermore, in this basic structure, as an example of gear device 1, an internally tangent planetary gear reduction device with cycloidal tooth profile is illustrated. That is, gear device 1 of this basic structure includes an internally tangent planetary gear 3 with cycloidal curved tooth profile.

[0068] Furthermore, in this basic structure, as an example, the gear device 1 is used with the gear body 22 of the internal gear 2 and the outer ring 62 of the bearing member 6 fixed to a fixed member such as the housing 10. Thus, as the internal gear 2 and the planetary gear 3 rotate relative to each other, the planetary gear 3 rotates relative to the fixed member (such as the housing 10).

[0069] Furthermore, in this basic structure, when the gear device 1 is used in the actuator 100, by applying a rotational force as input to the eccentric shaft 7, a rotational force as output is extracted from the output shaft integrated with the inner ring 61 of the bearing member 6. In other words, 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. Thus, in the gear device 1, an output rotation that is reduced in speed relative to the input rotation at a relatively high reduction ratio can be obtained.

[0070] The drive source 101 is a power source such as a motor (electric motor). The power generated by the drive source 101 is transmitted to the 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.

[0071] Furthermore, in the gear device 1 of this basic structure, 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 to say, in the gear device 1, it is possible to obtain an output rotation that is reduced in speed by a relatively high reduction ratio by rotating coaxially relative to the input.

[0072] like Figure 4 As shown, the internal gear 2 is an annular component with internal teeth 21. In this basic structure, the internal gear 2 has an annular shape, at least its inner circumferential surface being a perfect circle when viewed from above. Internal teeth 21 are formed along the circumferential direction of the annular internal gear 2 on its inner circumferential surface. All teeth constituting the internal teeth 21 are of the same shape and are evenly spaced throughout the entire circumferential region of the inner circumferential surface of the internal gear 2. That is, the pitch circle of the internal teeth 21 is a perfect circle when viewed from above. The center of the pitch circle of the internal teeth 21 is located on the rotation axis Ax1. Furthermore, the internal gear 2 has a predetermined thickness along the direction of the rotation axis Ax1. The tooth directions of the internal teeth 21 are all parallel to the rotation axis Ax1. The dimension of the internal teeth 21 in the tooth direction is slightly smaller than that in the thickness direction of the internal gear 2.

[0073] 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 to form internal teeth 21. In other words, the multiple pins 23 function as multiple teeth constituting the internal teeth 21. Specifically, as... Figure 2 As shown, multiple grooves are formed on the inner circumferential surface 221 of the gear body 22, covering the entire circumferential region. All grooves are of the same shape and are evenly spaced. Each groove is parallel to the rotation axis Ax1 and extends along the entire thickness of the gear body 22. Multiple pins 23 are attached to the gear body 22 by fitting into these grooves. 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.

[0074] like Figure 4 As shown, the planetary gear 3 is an annular component with external teeth 31. In this basic structure, the planetary gear 3 has an annular shape, at least its outer circumferential surface being a perfect circle when viewed from above. External teeth 31 are formed on the outer circumferential surface of the annular planetary gear 3 along the circumferential direction of the planetary gear 3. All the teeth constituting the external teeth 31 are of the same shape and are 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 from the rotation axis Ax1 (refer to...). Figure 4 The position of the planetary gear 3 is specified. Furthermore, 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.

[0075] Here, the planetary gear 3 is assembled with an eccentric bearing 5 and an eccentric shaft 7. That is, 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. When 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 in the opening 33 of the planetary gear 3. Furthermore, the eccentric bearing 5 and the eccentric shaft 7 are assembled into 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 assembled 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.

[0076] 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. At this time, external teeth 31 are formed on the outer circumferential surface of the planetary gear 3, and internal teeth 21 are formed on the inner circumferential surface of the internal gear 2. Therefore, with the planetary gear 3 positioned inside the internal gear 2, the external teeth 31 and the internal teeth 21 are opposite each other.

[0077] 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, at least a portion of the external teeth 31 and the internal teeth 21 are positioned opposite each other with a clearance, 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 mesh partially. That is, through 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 teeth 31 meshes with a portion of the teeth constituting the internal teeth 21. As a result, in the gear assembly 1, a portion of the external teeth 31 can mesh with a portion of the internal teeth 21.

[0078] Here, the number of teeth of the internal gear 21 in the internal gear 2 is N more than the number of teeth of the external gear 31 in the planetary gear 3 (N is a positive integer). In this basic structure, as an example, N is "1", and 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 relative to the input rotation in the gear unit 1.

[0079] Furthermore, in this basic structure, 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. Moreover, the dimension of the tooth direction of the external tooth 31 (the direction parallel to the rotation axis Ax1) is smaller than the dimension of the tooth direction of the internal tooth 21 (the 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.

[0080] In this basic structure, 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 basic structure, for example, there are 18 inner pin holes 32 and 18 inner pins 4. Each of the multiple inner pin holes 32 is a circular opening that penetrates 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.

[0081] 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 ).

[0082] 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 ).

[0083] 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, because the inner diameter of the outer ring 62 is larger than the outer diameter of the inner ring 61, a gap is created between the inner circumferential surface of the outer ring 62 and the outer circumferential surface of the inner ring 61.

[0084] The inner ring 61 has a plurality of retaining holes 611 for inserting a plurality of inner pins 4. The number of retaining holes 611 is the same as the number of inner pins 4; in this basic structure, 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 circular 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.

[0085] 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 basic structure, the plurality of output-side mounting holes 612 are located further inward than the plurality of retaining holes 611 and are arranged on a virtual circle concentric with the outer periphery of the inner ring 61.

[0086] 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, with the gear body 22 sandwiched between the outer ring 62 and the housing 10, it is fixed to the housing 10 by screws (bolts) 60 that pass through the through hole 621 and the fixing hole 222 of the gear body 22.

[0087] 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.

[0088] In this basic structure, 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 circumference of the inner ring 61. Further, a pair of adjacent rolling elements 63 in the circumferential direction of the inner ring 61 are arranged in an axially orthogonal orientation. In such a bearing member 6 constructed of crossed roller bearings, radial loads, thrust loads (along the direction of the rotation axis Ax1), and bending forces (bending moment loads) relative to the rotation axis Ax1 are easily withstood. Moreover, by means of a single bearing member 6, these three types of loads can be withstood, thereby ensuring the required rigidity.

[0089] 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 center of the central portion 71 along its entire circumference in the longitudinal direction (axial direction). According to the above structure, the eccentric portion 72 undergoes eccentric motion by rotating the central portion 71 around the rotation axis Ax1 with respect to the eccentric shaft 7.

[0090] In this basic structure, the central shaft 71 and the eccentric shaft 72 are integrally formed from a single metal component, thereby achieving a seamless eccentric shaft 7. This eccentric shaft 7, with its shape, is combined with the eccentric bearing 5 in the planetary gear 3. Therefore, when the eccentric shaft 7 rotates in the state where the planetary gear 3 is combined with the eccentric bearing 5 and the eccentric shaft 7, the planetary gear 3 oscillates around the rotation axis Ax1.

[0091] 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 two end faces of the through hole 73 in the axial direction of the shaft center portion 71 are circularly open. 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.

[0092] Furthermore, in this basic structure, 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 basic structure, 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.

[0093] 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 used to transmit only the oscillating component (revolutionary component) of the rotation of the eccentric shaft 7, excluding its rotational component, to the planetary gear 3. 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 ).

[0094] Both the outer eccentric ring 52 and the inner eccentric ring 51 are annular components. Both the outer eccentric ring 52 and the inner eccentric ring 51 are perfectly circular 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.

[0095] 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 arranged at equal intervals throughout the circumferential region of the outer ring 52. In this basic structure, as an example, the eccentric bearing 5 is constructed using a deep groove ball bearing that uses balls as rolling elements 53.

[0096] Here, the inner diameter of the inner ring 51 of the eccentric shaft 7 matches the outer diameter of the eccentric portion 72 in the eccentric shaft 7. The eccentric bearing 5 is assembled with the eccentric shaft 7 with the eccentric portion 72 of the eccentric shaft 7 inserted into the inner ring 51. Furthermore, the outer diameter of the outer ring 52 of the eccentric shaft 7 matches the inner diameter (diameter) of the opening 33 in 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. In other words, the eccentric bearing 5 is housed in the opening 33 of the planetary gear 3, where the eccentric portion 72 of the eccentric shaft 7 is assembled.

[0097] Furthermore, in this basic structure, as an example, the width direction (the direction parallel to the rotation axis Ax1) of the inner 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 (the direction parallel to the rotation axis Ax1) of the outer ring 52 of the eccentric bearing is slightly smaller than the width direction of the inner ring 51. Further, the width direction of the outer ring 52 of the eccentric bearing is larger than the thickness of the planetary gear 3. Therefore, the planetary gear 3 is housed within the area of ​​the eccentric bearing 5 in the direction parallel to the rotation axis Ax1. On the other hand, the width direction of the outer ring 52 of the eccentric bearing is smaller than the tooth direction (the direction parallel to the rotation axis Ax1) of the internal gear 21. Therefore, the eccentric bearing 5 is housed within the area of ​​the internal gear 2 in the direction parallel to the rotation axis Ax1.

[0098] 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 that deviates 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, the eccentric bearing 5 transmits only the rotational component of the eccentric shaft 7, that is, the oscillating component (revolutionary component), of the eccentric shaft 7 to the planetary gear 3. Thus, when the eccentric shaft 7 rotates in the state where the planetary gear 3 is combined with the eccentric bearing 5 and the eccentric shaft 7, the planetary gear 3 oscillates around the rotation axis Ax1.

[0099] 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 for the insertion of the inner pins 4. The number of support holes 82 is the same as the number of inner pins 4; in this basic structure, 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 basic structure, 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.

[0100] 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 by binding the multiple inner pins 4 together by inserting multiple inner pins 4 into multiple support holes 82. Further, the support body 8 is positionally constrained by contacting its outer peripheral surface 81 with multiple pins 23. Thus, the support body 8 is centered using the multiple pins 23, resulting in centering of the multiple inner pins 4 supported by the support body 8 using the multiple pins 23 as well. The support body 8 will be described in detail in the "(3.3) Support Body" section.

[0101] 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 in 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.

[0102] 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. Additionally, 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. A first bearing 91 is mounted to the housing 10 by inserting it into the bearing hole 12.

[0103] Furthermore, a plurality of threaded holes 13 are formed on the output side end face 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.

[0104] In addition, such as Figure 3 As shown, the gear assembly 1 of this basic structure 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 and fills 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 and fills 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 and fills 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. Furthermore, 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.

[0105] 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 used, 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 two phases, 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.

[0106] In the gear assembly 1 described above, a rotational force is applied as input to the eccentric shaft 7, causing the eccentric shaft 7 to rotate around the rotation axis Ax1. This causes the planetary gear 3 to oscillate (revolve) around the rotation axis Ax1. At this time, the planetary gear 3 oscillates in a state where it is internally tangent to the internal gear 2 and a portion of its external teeth 31 meshes with a portion of 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, through multiple inner pins 4, the rotational component (rotational component) of the planetary gear 3, excluding the oscillation component (revolutionary component), is transmitted to the inner ring 61 of the bearing member 6. 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.

[0107] However, as described above, in the gear device 1 of this embodiment, 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.

[0108] R1=V2 / (V1-V2)……(Formula 1)

[0109] 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 tooth difference (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, when the eccentric shaft 7 rotates clockwise around the rotating shaft Ax1 for one full revolution (360 degrees), the inner ring 61 rotates counterclockwise around the rotating shaft Ax1 by the amount of the tooth difference "1" (that is, approximately 7.06 degrees).

[0110] According to the gear device 1 of this basic structure, such a high reduction ratio R1 can be achieved by a combination of a primary gear (internal gear 2 and planetary gear 3).

[0111] 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. For example, it may also include spline bushings as structural elements.

[0112] However, in cases where the input rotation, such as in the gear device 1 of this basic structure, is accompanied by eccentric motion and is a high-speed rotating side, vibration or other issues may occur if the rotating body undergoing high-speed rotation is not balanced. 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 the component (eccentric shaft 7) that rotates together with the inner ring 51, 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 basic structure, 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.

[0113] In summary, in this basic structure, weight reduction is achieved by thinning a portion of the rotating body (here, the eccentric shaft 7) without adding counterweights, thereby achieving weight balance of the rotating body relative to the rotation axis Ax1. That is, the gear assembly 1 of this basic structure includes an eccentric bearing 5 housed in the opening 33 formed in the planetary gear 3, causing 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. Viewed from the rotation axis Ax1 of the inner eccentric ring 51, the rotating body, composed of at least one of the components that rotate together with the inner eccentric ring 51, has a gap 75 on the center C1 side of the outer eccentric ring 52. In this basic structure, 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.

[0114] 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 basic structure, 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.

[0115] (3.2) The self-rotation structure of domestic sales

[0116] Next, regarding the rotation structure of the inner pin 4 of the gear device 1 in this basic structure, refer to... Figure 9 To explain in more detail. Figure 9 yes Figure 3 A magnified view of region Z1.

[0117] 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 (the end on the input side of the rotating shaft Ax1 in this basic structure) 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 (the end on the output side of the rotating shaft Ax1 in this basic structure) is inserted into the retaining hole 611 of the inner ring 61.

[0118] 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, meaning 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 basic structure, 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 is held relative to the inner ring 61 in a state where it cannot revolve 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, and the rotation (rotation component) of planetary gear 3, other than the oscillation component (revolution component), is transmitted to the inner ring 61 through multiple inner pins 4.

[0119] However, in this basic structure, 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 into it, it can still rotate within the retaining hole 611. In other words, even when the inner pin 4 is inserted into the retaining hole 611, it can rotate within the retaining hole 611 because it is not pressed into it. Thus, in the gear device 1 of this basic structure, multiple inner pins 4 are each held by the inner ring 61 in a state where they can rotate, so that while the inner pin 4 revolves within the inner pin hole 32, it can also rotate on its own axis.

[0120] In summary, in this basic structure, 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 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 states (rotational states), 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 can rotate within the retaining hole 611. Therefore, while the inner pin 4 revolves within the inner pin hole 32, it 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 due to frictional resistance between the inner circumferential surface 321 of the inner pin hole 32 and the inner pin 4.

[0121] Thus, in this basic structure, 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 basic structure, 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 basic structure, the inner pin 4 without the inner roller is inserted into the inner pin hole 32, so that 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, the diameter of the inner pin hole 32 can be kept relatively small, and thus the planetary gear 3 can be miniaturized (especially reduced in diameter), 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 pins 4 can be thickened to increase strength. Furthermore, the number of components can be reduced by adjusting the amount of internal rollers, which also helps to reduce the cost of gear device 1.

[0122] Furthermore, in the gear assembly 1 of this basic structure, at least a portion of each of the plurality of inner pins 4 is arranged axially in the same position as the bearing member 6. That is, as Figure 9As shown, in a direction parallel to the rotation axis Ax1, the inner pin 4 positions at least a portion of itself in 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 positions at least a portion inside the outer ring 62 of the bearing member 6. In this basic structure, the output end of the inner pin 4 on the rotation axis Ax1 is positioned in 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 in the same location as the bearing member 6 in the axial direction.

[0123] In this way, at least a portion of each of the multiple inner pins 4 is positioned in the same axial direction as the bearing member 6, thereby reducing the size of the gear assembly 1 in the direction parallel to the rotation axis Ax1. That is, compared to a structure in which the bearing member 6 and the inner pins 4 are arranged side by side (opposite) along the axial direction of the bearing member 6, the gear assembly 1 in this basic structure can reduce the size of the gear assembly 1 in the direction parallel to the rotation axis Ax1, and can contribute to further miniaturization (thinning) of the gear assembly 1.

[0124] Here, the opening on the output side of the rotating shaft Ax1 in the retaining 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.

[0125] Furthermore, in this basic structure, the following structure is adopted to ensure smooth rotation of the inner pin 4 relative to the inner ring 61. That is, 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 basic structure, there is a lubricant retaining space 17 for lubricant injection between the inner ring 61 and the outer ring 62, so the smooth rotation of the inner pin 4 is achieved by utilizing the lubricant in the lubricant retaining space 17.

[0126] like Figure 9As shown, in this basic structure, 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 lubricant retaining space 17 side is positioned facing (opposite) to 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.

[0127] 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 rolls the rolling element 63, the rolling element 63 functions as a pump, which can deliver the lubricant in the lubricant holding space 17 to the holding hole 611 via 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.

[0128] (3.3) Support body

[0129] Next, regarding the structure of the support body 8 of the gear device 1 in this basic structure, refer to... Figure 10 To explain in more detail. 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. Additionally, in... Figure 10 The diagram only shows the internal gear 2 and the support body 8; 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 illustration.

[0130] First, as mentioned above, the support body 8 is a component that supports multiple inner pins 4. That is, by binding the multiple inner pins 4 together, the support body 8 distributes the load acting on the multiple inner pins 4 when transmitting the rotation (rotation component) of the planetary gear 3 to the inner ring 61. Specifically, it has multiple support holes 82 into which the multiple inner pins 4 are inserted respectively. In this basic structure, 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 multiple inner pins 4 in a state where each of the multiple inner pins 4 can rotate. That is, each of the multiple inner pins 4 is held in a state where it can rotate relative to both the inner ring 61 of the bearing member 6 and the support body 8.

[0131] 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 movement of the inner pins 4 in all directions within a plane orthogonal to the rotation axis Ax1 is restricted by inserting them into the support holes 82 of 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.

[0132] 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 (addition 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. Therefore, the support body 8 is centered, and as a result, the plurality of internal pins 4 supported by the support body 8 are also centered using the plurality of pins 23.

[0133] 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 using multiple pins 23, thus maintaining its center on the rotation axis Ax1, allowing the support body 8 to rotate smoothly. Moreover, the support body 8 rotates with its outer circumferential surface 81 in contact with the multiple pins 23, so that with the rotation of the support body 8, each of the multiple pins 23 rotates (rotates). Thus, the support body 8 and the internal gear 2 together constitute a needle roller bearing (needle roller bearing) and rotate smoothly.

[0134] 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 contact with 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.

[0135] Furthermore, since the support body 8 clamps multiple pins 23 between the gear bodies 22, the support body 8 also functions as a "limiting member" to inhibit the movement of the pins 23 in the direction of separation from the inner circumferential surface 221 of the gear body 22. That is, the multiple pins 23 are prevented from floating off the inner circumferential surface 221 of the gear body 22 by being clamped between the outer circumferential surface 81 of the support body 8 and the inner circumferential surface 221 of the gear body 22. In summary, in this basic structure, each of the multiple pins 23 is restricted from moving in the direction of separation from the gear body 22 by contacting the outer circumferential surface 81 of the support body 8.

[0136] However, as Figure 9 As shown, in this basic structure, the support 8 is located on the side of the bearing member 6 opposite to the inner ring 61, separated from the planetary gear 3. That is, the support 8, planetary gear 3, and inner ring 61 are arranged side-by-side in a direction parallel to the rotation axis Ax1. In this basic structure, as an example, the support 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 8 and the inner ring 61 together support both ends of the inner pin 4 in the length 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 basic structure includes a bearing member 6 having 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 axially between the support body 8 and the inner ring 61.

[0137] According to this structure, the support body 8 and the inner ring 61 support the two ends of the inner pin 4 along its length, thus making it difficult for the inner pin 4 to tilt. In particular, it easily withstands the bending force (bending moment load) acting on the multiple inner pins 4 relative to the rotating shaft Ax1. Furthermore, in this basic structure, the support body 8 is sandwiched between the planetary gear 3 and the housing 10 in a direction parallel to the rotating shaft Ax1. Therefore, the support body 8 is positioned 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.

[0138] In this basic structure, the support body 8 and the inner ring 61 also contact the two ends of a plurality of pins 23. That is, as 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.

[0139] 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 locally worn.

[0140] Furthermore, in this basic structure, the outer peripheral surface 81 of the support 8 has a smaller surface roughness than 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 an object's surface; the smaller the value, the less unevenness and smoother the surface. In this basic structure, as an example, the surface roughness is set to arithmetic equilibrium roughness (Ra). For example, through processes such as grinding, the outer peripheral surface 81 has a smaller surface roughness than the surfaces other than the outer peripheral surface 81 of the support 8. In this structure, the rotation of the support 8 becomes smoother.

[0141] Furthermore, in this basic structure, the hardness of the outer peripheral surface 81 of the support body 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 basic structure, as an example, the hardness of the outer peripheral surface 81 of the support body 8 is increased by treatments such as carburizing and quenching. In this structure, even due to the rotation of the support body 8, wear particles are unlikely to be generated, and the smooth rotation of the support body 8 can be easily maintained for a long time.

[0142] (4) Applicable examples

[0143] Next, an applicable example of the gear device 1 and actuator 100 of this basic structure will be described.

[0144] The gear device 1 and actuator 100 of this basic structure are applicable, for example, to horizontal multi-joint robots, such as robots with so-called Selective Compliance Assembly Robot Arms (SCARA).

[0145] Furthermore, the application examples of the gear device 1 and actuator 100 of this basic structure are not limited to horizontal articulated robots as described above. For example, they can also be industrial robots or robots used outside of industry, in addition to horizontal articulated robots. As an example, industrial robots other than horizontal articulated robots include vertical articulated robots or parallel linkage robots. Among robots used outside of industry, examples include home robots, nursing robots, or medical robots.

[0146] (Implementation Method 1)

[0147] <Outline>

[0148] The internal meshing planetary gear device 1A (hereinafter also simply referred to as "gear device 1A") of this embodiment is as follows: Figures 11-15 As shown, the main difference lies in the structure around the inner pin 4, which differs from the gear assembly 1 in the basic structure. Hereinafter, for structures identical to the basic structure, the same reference numerals will be used, and descriptions will be omitted as appropriate.

[0149] Figure 11 This is a schematic cross-sectional view of gear assembly 1A. Figure 12A yes Figure 11 A rough enlarged view of region Z1, Figure 12B yes Figure 12ASectional view along line A1-A1. Figure 13 It is a schematic representation in Figure 12A A diagram illustrating the forces acting under certain conditions. Figure 14 From the output side of rotating axis Ax1 ( Figure 11 A side view of the gear assembly 1A as observed from the right side. Figure 11 Equivalent to Figure 14 Sectional view along line A1-A1. Figure 15 It is from the input side of the rotation axis Ax1 ( Figure 11 (From the left side) Side view of gear assembly 1A.

[0150] As the first major difference from the basic structure, the gear device 1A of this embodiment is configured such that when the plurality of inner pins 4 are not rotating relative to the internal gear 2, a preload is applied from the planetary gear 3 to each inner pin 4. That is, in the gear device 1A, when the plurality of inner pins 4 are not rotating relative to the internal gear 2, the inner circumferential surfaces 321 of each of the plurality of inner pin holes 32 press against each inner pin of the plurality of inner pins 4, thereby applying a preload (forces F1, F2) to each inner pin of the plurality of inner pins 4. Here, the gear device 1A also includes a support structure 40 supporting each inner pin of the plurality of inner pins 4 to maintain the state of the applied preload. The support structure 40 supports each inner pin of the plurality of inner pins 4 to counteract the torque M1 generated on each inner pin of the plurality of inner pins 4 due to the preload (see reference). Figure 13 ).

[0151] Furthermore, as a second major difference between the gear device 1A of this embodiment and the basic structure, the structure supporting the multiple inner pins 4 (support structure 40) is a structure in which the two ends of the inner pins 4 are held by rolling bearings 41, 42. That is, the gear device 1A includes multiple sets of rolling bearings 41, 42 that hold each inner pin of the multiple inner pins 4 on both sides of the planetary gear 3 in a direction parallel to the rotation axis Ax1. Each inner pin of the multiple inner pins 4 is held by its respective set of rolling bearings 41, 42 in a state that allows it to rotate.

[0152] In summary, the main differences from the basic structure are the new structure around the inner pin 4 in this embodiment of the gear device 1A, particularly the study of the preload of the inner pin 4 and the support structure 40 (rolling bearings 41, 42) for the inner pin 4. Here, the rolling bearings 41, 42 are fixed to the inner ring 61 of the bearing member 6A, and the inner pin 4 is held by the inner ring 61 of the bearing member 6A via the rolling bearings 41, 42. Therefore, in this embodiment of the gear device 1A, the fact that each of the plurality of inner pins 4 is held by the inner ring 61 in a rotatable state is also the same as in the basic structure.

[0153] <Other differences>

[0154] In the gear device 1A of this embodiment, apart from the main differences mentioned above (the periphery structure of the inner pin 4), there are several differences in the basic structure as will be explained below.

[0155] As another first difference, the bearing member 6A of the gear device 1A in this embodiment includes a first bearing member 601A and a second bearing member 602A. The first bearing member 601A and the second bearing member 602A are each composed of a deep groove ball bearing and have an inner ring 61, an outer ring 62, and a plurality of rolling elements 63. The first bearing member 601A and the second bearing member 602A are arranged on opposite sides of the planetary gear 3 in a direction parallel to the rotation axis Ax1. The inner ring 61 of both the first bearing member 601A and the second bearing member 602A has an outer circumferential surface that, when viewed from above, is a perfect circle centered on the rotation axis Ax1. Specifically, as... Figure 11 As shown, viewed from planetary gear 3 on the input side of rotating shaft Ax1 ( Figure 11 The first bearing member 601A is arranged on the left side of the planetary gear 3, and is located on the output side of the rotating shaft Ax1. Figure 11 The right side of the bearing assembly 601A is provided with a second bearing member 602A. The bearing member 6A is configured to withstand radial loads, thrust loads (along the direction of the rotation axis Ax1), and bending forces (bending moment loads) on the rotation axis Ax1 by means of the first bearing member 601A and the second bearing member 602A.

[0156] As another second difference, such as Figure 11 As shown, the gear device 1A of this embodiment includes a support flange 18 and an output flange 19. The support flange 18 and the output flange 19 are fixed to the inner ring 61 of the bearing member 6A (each of the first bearing member 601A and the second bearing member 602A). The support flange 18 and the output flange 19 are arranged on both sides of the planetary gear 3 in a direction parallel to the rotation axis Ax1, and pass through the support hole 34 of the planetary gear 3 (see reference). Figure 16 And they combine with each other. Specifically, such as Figure 11 As shown, viewed from planetary gear 3 on the input side of rotating shaft Ax1 ( Figure 11 On the left side) is a bracket flange 18, which is located on the output side of the rotating shaft Ax1 when viewed from the planetary gear 3. Figure 11 The right side of the bracket flange 18 is provided with an output flange 19. The bracket flange 18 is fixed by being embedded in the inner ring 61 of the first bearing member 601A, and the output flange 19 is fixed by being embedded in the inner ring 61 of the second bearing member 602A.

[0157] The output flange 19 has a plurality of (in one example, 6) support pins 191 (see reference) protruding from one surface of the output flange 19 toward the input side of the rotation axis Ax1. Figure 16These multiple bracket pins 191 pass through multiple (in one example, six) bracket holes 34 formed in the planetary gear 3, and the front ends of the multiple bracket pins 191 are secured by bracket bolts 181 (see reference). Figure 15 The bracket pin 191 is fixed to the bracket flange 18. Here, the diameter of the bracket pin 191 is slightly smaller than the diameter of the bracket hole 34, and a gap is ensured between the bracket pin 191 and the inner circumferential surface of the bracket hole 34, allowing the bracket pin 191 to move within the bracket hole 34, that is, to move relative to the center of the bracket hole 34. Furthermore, the gap between the bracket pin 191 and the inner circumferential surface of the bracket hole 34 is larger than the gap between the inner pin 4 and the inner circumferential surface 321 of the inner pin hole 32, so that the bracket pin 191 does not contact the inner circumferential surface of the bracket hole 34 when the inner pin 4 revolves within the inner pin hole 32. Additionally, a plurality of flange bolt holes 192 (see reference 192) are formed on the surface of the output flange 19 opposite to the bracket pin 191 for fixing the output flange 19 itself. Figure 14 ).

[0158] Here, the two ends of the inner pin 4 are not directly held by the inner ring 61 of the bearing member 6A, but are held by the bracket flange 18 and the output flange 19 (via rolling bearings 41, 42) integrated with the inner ring 61. That is, the multiple inner pins 4 are indirectly held by the inner ring 61 of the bearing member 6A because they are held by the bracket flange 18 and the output flange 19.

[0159] Thus, the gear device 1A is used in such a way that the rotation of the planetary gear 3, corresponding to its rotational component, is taken out as the rotation of the support flange 18 and the output flange 19, which are integrated with the inner ring 61 of the bearing member 6A. That is, in the basic structure, the relative rotation between the planetary gear 3 and the internal gear 2 is taken out as the rotational component of the planetary gear 3 from the inner ring 61 of the planetary gear 3, which is connected by the inner pin 4. In this embodiment, the relative rotation between the planetary gear 3 and the internal gear 2 is taken out from the support flange 18 and the output flange 19, which are integrated with the inner ring 61. In this embodiment, as an example, the gear device 1A is used with the outer ring 62 of the bearing member 6A fixed to the housing, which is a fixed member. That is, the planetary gear 3 is connected to the support flange 18 and the output flange 19, which are rotating members, by means of multiple inner pins 4, and the gear body 22 is fixed to the fixed member, so the relative rotation between the planetary gear 3 and the internal gear 2 is taken out from the rotating members (support flange 18 and output flange 19). In other words, in this embodiment, when the plurality of inner pins 4 are configured to rotate relative to the gear body 22, the rotational force of the support flange 18 and the output flange 19 is taken out as the output.

[0160] As a third difference, in this embodiment, the housing 10 and the gear body 22 of the internal gear 2 are seamlessly integrated. That is, in the basic structure, the gear body 22 of the internal gear 2 is used together with the outer ring 62 of the bearing member 6 in a state of being fixed to the housing 10. In this embodiment, the gear body 22, as a fixing member, is seamlessly and continuously provided with the housing 10 in a direction parallel to the rotation axis Ax1.

[0161] More specifically, the housing 10 is cylindrical and forms the outer contour of the gear assembly 1A. In this embodiment, the central axis of the cylindrical housing 10 is aligned with the rotation axis Ax1. That is, at least the outer peripheral surface of the housing 10, when viewed from above (from the direction of rotation axis Ax1), is a perfect circle centered on rotation axis Ax1. The housing 10 is formed as a cylinder with openings at both ends in the direction of rotation axis Ax1. Here, the housing 10 is seamlessly integrated with the gear body 22 of the internal gear 2, so that the housing 10 and the gear body 22 are treated as a single component. Therefore, the inner peripheral surface of the housing 10 includes the inner peripheral surface 221 of the gear body 22. Furthermore, the outer ring 62 of the bearing member 6A is fixed to the housing 10. That is, when viewed from the gear body 22 in the inner peripheral surface of the housing 10, the outer ring 62 of the first bearing member 601A is fixed to the input side of the rotation axis Ax1 by embedding. Figure 11 (Left side). On the other hand, viewed from the gear body 22 on the inner circumferential surface of the housing 10, the outer ring 62 of the second bearing member 602A is fixed to the output side of the rotating shaft Ax1 by embedding. Figure 11 (Right side).

[0162] Furthermore, the input side of the rotation axis Ax1 of the housing 10 ( Figure 11 The left end face of the housing 10 is closed by the bracket flange 18, and the output side of the rotating shaft Ax1 of the housing 10 ( Figure 11 The right-side end face is closed by the output flange 19. Therefore, as Figure 11 , Figure 14 and Figure 15 As shown, within the space surrounded by the housing 10, the support flange 18, and the output flange 19, components such as the planetary gear 3, multiple inner pins 4, multiple pins 23, and the eccentric bearing 5 are housed. Here, oil seal 161 fills the gap between the support flange 18 and the housing 10, and oil seal 162 fills the gap between the output flange 19 and the housing 10. The space sealed by the multiple oil seals 14, 15, 161, and 162 constitutes the lubricant retention space 17 in the same manner as the basic structure (see reference). Figure 11 Multiple mounting holes 111 are formed on both ends of the housing 10 in a direction parallel to the rotation axis Ax1 for fixing the housing 10 itself.

[0163] As a fourth difference, the gear device 1A of this embodiment includes a plurality of planetary gears 3. Specifically, the gear device 1A includes two planetary gears 3: a first planetary gear 301 and a second planetary gear 302. The two planetary gears 3 are configured to face each other in a direction parallel to the rotation axis Ax1 (with the support ring 8A sandwiched between them). That is, the planetary gears 3 comprise a first planetary gear 301 and a second planetary gear 302 arranged side by side in a direction parallel to the rotation axis Ax1.

[0164] These two planetary gears 3 (first planetary gear 301 and second planetary gear 302) are arranged about the rotation axis Ax1 with a phase difference of 180 degrees. Figure 11 In the example, the first planetary gear 301 and the second planetary gear 302 located on the input side of the rotating shaft Ax1 ( Figure 11 The center C1 of the first planetary gear 301 (on the left side) is in a state that is offset (biased) from the top relative to the rotation axis Ax1. On the other hand, the output side of the rotation axis Ax1 ( Figure 11 The center C2 of the second planetary gear 302 (on the right side) is offset (biased) downward relative to the rotation axis Ax1. In this way, the multiple planetary gears 3 are evenly arranged circumferentially around the rotation axis Ax1, thereby achieving weight balance among the multiple planetary gears 3. In the gear device 1A of this embodiment, weight balance is achieved among the multiple planetary gears 3 in this way, thus omitting the clearance 75 of the eccentric shaft 7 (see reference). Figure 3 ).

[0165] More specifically, the eccentric shaft 7 has two eccentric portions 72 for a central portion 71. The centers (central axes) of these two eccentric portions 72 coincide with centers C1 and C2, respectively, that are offset from the rotation axis Ax1. Furthermore, the first planetary gear 301 and the second planetary gear 302 are identical in shape. An eccentric bearing 5 is housed in the opening 33 of the first planetary gear 301, fitted with the eccentric portion 72 centered on center C1. An eccentric bearing 5 is housed in the opening 33 of the second planetary gear 302, fitted with the eccentric portion 72 centered on center C2. Here, the distance ΔL1 between the rotation axis Ax1 and center C1 is the eccentricity of the first planetary gear 301 relative to the rotation axis Ax1, and the distance ΔL2 between the rotation axis Ax1 and center C2 is the eccentricity of the second planetary gear 302 relative to the rotation axis Ax1.

[0166] exist Figure 16 and Figure 17 The image shows the state of the first planetary gear 301 and the second planetary gear 302 at a certain moment. Figure 16 yes Figure 11 The A1-A1 sectional view shows the first planetary gear 301. Figure 17 yes Figure 11 The cross-sectional view along line B1-B1 shows the second planetary gear 302. Wherein... Figure 16 and Figure 17 In this diagram, the holder 54 is omitted, and even in cross-sections, the section lines are omitted. (See attached image.) Figure 16 and Figure 17 As shown, in the first planetary gear 301 and the second planetary gear 302, their centers C1 and C2 are rotationally symmetrical about the rotation axis Ax1 by 180 degrees. In this embodiment, although the orientations of the eccentricities ΔL1 and ΔL2 observed from the rotation axis Ax1 are opposite, their absolute values ​​are the same. According to the above structure, the shaft center 71 rotates (rotates) around the rotation axis Ax1, thereby causing the first planetary gear 301 and the second planetary gear 302 to rotate (eccentrically move) about the rotation axis Ax1 with a phase difference of 180 degrees.

[0167] As another fifth difference, such as Figure 11 As shown, in this embodiment, the eccentric bearing 5 is constructed of a roller bearing instead of the deep groove ball bearing described in the basic structure. That is, in the gear assembly 1A of this embodiment, the eccentric bearing 5 uses cylindrical rollers as rolling elements 53. Furthermore, in this embodiment, the inner ring 51 of the eccentric bearing (see reference...) is omitted. Figure 3 ) and eccentric outer ring 52 (refer to Figure 3 Therefore, the inner circumferential surface of the planetary gear 3 (opening 33) replaces the outer ring 52 of the eccentric shaft as the rolling surface of the plurality of rolling elements 53, and the outer circumferential surface of the eccentric portion 72 replaces the inner ring 51 of the eccentric shaft as the rolling surface of the plurality of rolling elements 53. In this embodiment, the eccentric bearing 5 has a retainer 54, and the plurality of rolling elements 53 are each held in the retainer 54 in a rotatable state. The retainer 54 holds the plurality of rolling elements 53 at equal intervals in the circumferential direction of the eccentric portion 72. Furthermore, the retainer 54 is not fixed relative to the planetary gear 3 and the eccentric shaft 7, but can rotate relative to each of the planetary gear 3 and the eccentric shaft 7. As a result, with the rotation of the retainer 54, the plurality of rolling elements 53 held by the retainer 54 move in the circumferential direction of the eccentric portion 72.

[0168] As another sixth difference, such as Figure 11As shown, the gear device 1A of this embodiment includes a support ring 8A instead of a support body 8. The support ring 8A is disposed between the two planetary gears 3, the first planetary gear 301 and the second planetary gear 302. The support ring 8A has an annular shape, at least its outer circumferential surface being a perfect circle when viewed from above. Furthermore, the support ring 8A is positionally constrained by contacting the outer circumferential surface with a plurality of pins 23 of 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 ring 8A is positionally constrained by contacting the internal teeth 21 with its outer circumferential surface. Here, the diameter of the outer circumferential surface of the support ring 8A 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 circumferential surface of the support ring 8A. Thus, with the support ring 8A positionally constrained by the plurality of pins 23, the center of the support ring 8A is positionally constrained in a manner that overlaps with the center (rotation axis Ax1) of the internal gear 2.

[0169] Here, the support ring 8A is held between the first planetary gear 301 and the second planetary gear 302, and rotates around the axis of rotation Ax1 as the planetary gear 3 rotates (rotates). At this time, the support ring 8A rotates with its outer circumference in contact with multiple pins 23, thus each pin 23 rotates (rotates) along with the support ring 8A. Therefore, the support ring 8A and the internal gear 2 together constitute a needle roller bearing (needle roller bearing) and rotate smoothly. That is, if the gear body 22 of the internal gear 2 is considered as the "outer ring" and the support ring 8A as the "inner ring," then the multiple pins 23 between them function as "rolling elements (rollers)." In this way, the support ring 8A and the internal gear 2 (gear body 22 and multiple pins 23) together constitute a needle roller bearing and can rotate smoothly. Furthermore, since the support ring 8A has multiple pins 23 sandwiched between it and the gear body 22, the support ring 8A also functions as a "limiting element" to inhibit the movement of the pins 23 in the direction of separation from the inner circumferential surface 221 of the gear body 22.

[0170] As another seventh difference, such as Figure 11 As shown, the gear device 1A of this embodiment includes a spacer 55. The spacer 55 is disposed between the first bearing 91 and the second bearing 92, which are inner bearing members, and the eccentric bearing 5. Specifically, the spacer 55 is disposed between the first bearing 91 and the eccentric bearing 5 on the side of the first planetary gear 301, and between the second bearing 92 and the eccentric bearing 5 on the side of the second planetary gear 302. The spacer 55 has an annular shape, at least the inner circumferential surface of which is a perfect circle when viewed from above. The spacer 55 functions as a "pressing member" of the eccentric bearing 5 and restricts the movement of the eccentric bearing 5 (especially the retainer 54) in a direction parallel to the rotation axis Ax1.

[0171] Here, the spacer 55 ensures a clearance between itself and the outer rings of the first bearing 91 and the second bearing 92. Therefore, in the first bearing 91 and the second bearing 92, their outer rings do not contact the spacer 55; only their inner rings contact the spacer 55. On the other hand, the first bearing member 601A and the second bearing member 602A, as bearing members 6A, ensure a clearance between themselves and the outer rings 62 of the planetary gear 3. Therefore, in the first bearing member 601A and the second bearing member 602A, their outer rings 62 do not contact the planetary gear 3; only their inner rings 61 contact the planetary gear 3. Furthermore, since the planetary gear 3 contacts the inner rings 61 of the first bearing member 601A and the second bearing member 602A, the movement of the planetary gear 3 in the direction parallel to the rotation axis Ax1 is restricted, thereby suppressing the tilting of the planetary gear 3.

[0172] In addition to the points mentioned above, for example, the number of teeth, reduction ratio, number of internal pin holes 32 and internal pins 4, and even the specific shape and size of each part of the internal gear 2 and planetary gear 3 are appropriately different from those in the basic structure. For example, in the basic structure, there are 18 internal pin holes 32 and internal pins 4, while in this embodiment, as an example, there are 6 of each.

[0173] <Structure surrounding domestic sales>

[0174] Next, regarding the structure around the inner pin 4 in the gear device 1A of this embodiment, refer to... Figures 11-18 To explain in more detail.

[0175] As described above, in this embodiment, when the plurality of inner pins 4 are not rotating relative to the internal gear 2, the inner circumferential surfaces 321 of the plurality of inner pin holes 32 press against each inner pin of the plurality of inner pins 4, thereby exerting a preload (force F1, F2) on each inner pin of the plurality of inner pins 4 from the planetary gear 3. Furthermore, the support structure 40 supports each inner pin 4 to counteract the torque generated on each inner pin 4 due to the preload.

[0176] The "preload" mentioned in this embodiment refers to a state in which internal stress is constantly applied due to the application of preload, which is called preload. That is, in the gear device 1A of this embodiment, when the plurality of inner pins 4 are not rotating relative to the internal gear 2, that is, when the gear device 1A is not driven, preload is applied from the planetary gear 3 to each inner pin 4. In short, in this embodiment, needless to say, when the plurality of inner pins 4 are rotating relative to the internal gear 2 (when the gear device 1A is driven), even when the plurality of inner pins 4 are not rotating relative to the internal gear 2 (when the gear device 1A is not driven), the inner circumferential surface 321 of the inner pin hole 32 presses against the inner pin 4.

[0177] According to the above structure, in the gear device 1A of this embodiment, the inner pin 4 is always in contact with the planetary gear 3 at a portion of the inner circumferential surface 321 of the inner pin hole 32, making it difficult for the inner pin 4 to separate from the planetary gear 3. Therefore, when the gear device 1A is driven, the inner pin 4 revolves within the inner pin hole 32 while pressing against the inner circumferential surface 321 of the inner pin hole 32. Generally, when assembling gear devices considering assembly tolerances, a gap is ensured between the inner circumferential surface of the inner pin hole and the inner pin when the gear device is not driven. However, the gear device 1A of this embodiment is designed to eliminate this gap. Therefore, according to the gear device 1A of this embodiment, backlash caused at least by the gap between the inner circumferential surface 321 of the inner pin hole 32 and the inner pin 4 can be reduced or eliminated, thereby easily minimizing angular transmission errors. Especially in gear devices 1A with high reduction ratios, even backlash caused by a slight clearance will increase the error of rotation of the output side (output flange 19) relative to rotation of the input side (eccentric shaft 7), that is, the angle transmission error. Therefore, the effect of reducing or eliminating backlash is significant.

[0178] Furthermore, according to the structure of this embodiment, the angular transmission error of the gear device 1A during startup from a stopped state to the start of rotation can be reduced. Therefore, the startup characteristics of the gear device 1A can be significantly improved, thereby greatly enhancing the responsiveness of the gear device 1A during startup or rotation direction switching. As a result, even in fields such as robotics where frequent stopping, starting, or rotation direction switching is required and where angular transmission error is critical, the gear device 1A can perform to its full potential.

[0179] Furthermore, in this embodiment, each of the multiple inner pins 4 is held by the inner ring 61 in a rotatable state. However, strictly speaking, each inner pin 4 is not directly held by the inner ring 61, but is held by the support flange 18 and the output flange 19 (via rolling bearings 41, 42) integrated with the inner ring 61, thereby being indirectly held by the inner ring 61 of the bearing member 6A. Thus, according to the structure in which the inner pins 4 are held in a rotatable state, even if the inner pins 4 revolve within the inner pin hole 32 while pressing against the inner circumferential surface 321 of the inner pin hole 32, the inner pins 4, being in a rotatable state, also roll relative to the inner circumferential surface 321 of the inner pin hole 32. In other words, the inner pins 4 revolve within the inner pin hole 32 by rolling on the inner circumferential surface 321 of the inner pin hole 32, thus minimizing losses caused by frictional resistance between the inner circumferential surface 321 of the inner pin hole 32 and the inner pins 4.

[0180] In addition, such as Figure 12AAs shown, in this embodiment, the support structure 40 includes multiple sets of retaining portions 410, 420 that hold each of the multiple inner pins 4 on both sides of the planetary gear 3 in a direction parallel to the rotation axis Ax1. In summary, the support structure 40 supporting each inner pin 4 includes multiple sets of retaining portions 410, 420 to eliminate the torque generated on each inner pin 4 due to the preload. Each set of retaining portions 410, 420 holds each inner pin 4 on both sides of the planetary gear 3 in a direction parallel to the rotation axis Ax1. The number of sets of retaining portions 410, 420 is the same as the number of inner pins 4; in this embodiment, as an example, six sets of retaining portions 410, 420 are provided corresponding to six inner pins 4.

[0181] Specifically, each retaining part 410, 420 retains both ends of the inner pin 4 along its length. Viewed from the planetary gear 3, on the input side of the rotating shaft Ax1 ( Figure 12A A retaining part 410 is arranged on the left side of the planetary gear 3, on the output side of the rotating shaft Ax1. Figure 12A The right side is equipped with a retaining part 420.

[0182] Here, each of the multiple sets of retaining portions 410, 420 includes a pair of rolling bearings 41, 42. In this embodiment, the retaining portion 410 is composed of rolling bearings 41. That is, each set of retaining portions 410, 42 is composed of a pair of rolling bearings 41, 42. Therefore, in this embodiment, as an example, the same number of sets of six pairs of rolling bearings 41, 42 as the retaining portions 410, 420 are provided. The rolling bearings 41 are fixed by pressing into the support flange 18, and the rolling bearings 42 are fixed by pressing into the output flange 19.

[0183] Specifically, a pair of rolling bearings 41 and 42 hold both ends of the inner pin 4 along its length in a state where the inner pin 4 can rotate. Here, as... Figure 12A and Figure 12B As shown, each rolling bearing 41, 42 has an outer ring 401 and multiple rolling elements 402. For example... Figure 12B As shown, the outer ring 401 is an annular component. The outer ring 401 is a perfect circle when viewed from above. Here, the inner diameter of the outer ring 401 is larger than the diameter (outer diameter) of the inner pin 4, thus creating a gap between the inner circumferential surface of the outer ring 401 and the outer circumferential surface of the inner pin 4. Multiple rolling elements 402 are disposed in the gap between the outer ring 401 and the inner pin 4. The multiple rolling elements 402 are arranged side-by-side along the circumferential direction of the outer ring 401. All of the multiple rolling elements 402 are metal components of the same shape, and are evenly spaced throughout the entire circumferential region of the outer ring 401.

[0184] In this embodiment, as an example, each rolling bearing 41 and 42 is a needle roller bearing. That is, each rolling bearing 41 and 42 has cylindrical rollers as rolling elements 402. Furthermore, the shafts of the cylindrical rolling elements 402 are all arranged parallel to the rotation axis Ax1. In this embodiment, each rolling bearing 41 and 42 does not have an inner ring, and the inner pin 4 functions as the inner ring. Therefore, according to each rolling bearing 41 and 42, the multiple rolling elements 402 roll, thereby causing the inner pin 4 to rotate relative to the outer ring 401, so that each rolling bearing 41 and 42 can hold the inner pin 4 in a position to rotate.

[0185] In summary, as described above, the gear device 1A of this embodiment includes multiple sets of rolling bearings 41, 42 holding multiple inner pins 4 on both sides of the planetary gear 3 in a direction parallel to the rotation axis Ax1. Each of the multiple inner pins 4 is held by the sets of rolling bearings 41, 42 in a rotatable state. According to this structure, the inner pins 4 can rotate, and since it is not easy 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 rollers can be omitted. Therefore, in this embodiment, the structure is such that the inner pins 4 without the inner rollers are inserted into the inner pin hole 32, so that the inner pins 4 directly contact the inner circumferential surface 321 of the inner pin hole 32. As a result, the inner rollers can be omitted, the diameter of the inner pin hole 32 can be kept relatively small, so the planetary gear 3 can be miniaturized (especially the diameter can be reduced), and the gear device 1A as a whole can also be easily miniaturized. Moreover, the holding parts 410, 420 holding each inner pin 4 include a pair of rolling bearings 41, 42. Therefore, when the inner pin 4 rotates, it is not easy to cause losses due to frictional resistance between the inner pin 4 and the retaining parts 410 and 420.

[0186] In particular, the inner pin 4 connects the planetary gear 3 to the rotating components (support flange 18 and output flange 19), and at least when the gear device 1A is driven, a bending force (bending moment load) is applied to the inner pin 4. Therefore, for example, when the inner pin 4 is held by a sliding bearing, the frictional resistance between the inner pin 4 and the holding portions 410, 420 increases due to this bending force, thereby increasing the loss caused by this frictional resistance. In this embodiment, the holding portions 410, 420 include rolling bearings 41, 42, so that even if a bending force is applied to the inner pin 4, it is difficult to affect the frictional resistance between the inner pin 4 and the holding portions 410, 420, thereby reducing the likelihood of loss caused by frictional resistance.

[0187] Furthermore, as described above, in the gear device 1A of this embodiment, when the plurality of inner pins 4 are not rotating relative to the internal gear 2, the inner circumferential surfaces 321 of the plurality of inner pin holes 32 are pressed against each inner pin of the plurality of inner pins 4, thereby applying a preload (force F1, F2) from the planetary gear 3 to each inner pin of the plurality of inner pins 4. When such a preload is applied to the inner pins 4, the bending force (bending moment load) acting on the inner pins 4 becomes larger. Therefore, as in the gear device 1A of this embodiment, by including rolling bearings 41, 42 in the retaining portions 410, 420, even if a large bending force is applied to the inner pins 4, it is particularly useful for structures that are unlikely to affect the frictional resistance between the inner pins 4 and the retaining portions 410, 420.

[0188] Next, refer to Figure 13 The force (preload) acting on the inner pins 4 when the multiple inner pins 4 are not rotating relative to the internal gear 2, that is, when the gear device 1A is not driven, will be explained in more detail.

[0189] Here, the two planetary gears 3 (first planetary gear 301 and second planetary gear 302) exert opposing forces on each inner pin 4. For example, in Figure 13 In the shown state, an upward force F1 acts on the inner pin 4 from the first planetary gear 301, and a downward force F2 acts on the inner pin 4 from the second planetary gear 302, thus creating a clockwise torque M1 on the inner pin 4. On the other hand, both ends of each inner pin 4 are held by retaining portions 410 and 420 (a pair of rolling bearings 41 and 42), so under the action of torque M1, reaction forces F3 and F4 from the retaining portions 410 and 420 act on both ends of the inner pin 4. Therefore, the surface of the inner pin 4 and the surface of the rolling elements 402 of the rolling bearings 41 and 42 make elastic contact by pressing against each other under the action of reaction forces F3 and F4. As a result, elastic deformation occurs in the inner pin 4 and the rolling elements 402 due to the Hertzian contact stress (stress or pressure applied to the elastic contact portion) acting between the surfaces of the inner pin 4 and the rolling elements 402.

[0190] Furthermore, when comparing force F1 (or F2) with reaction force F3 (or F4), reaction force F3 (or F4) is smaller than force F1 (or F2) (F3 < F1, or F4 < F2). That is, the ratio of reaction force F3 to force F1 is expressed as the ratio of the distance (L2) from the center of torque M1 to the point of application of force F1 to the distance (L1) to the point of application of reaction force F3 (F3:F1 = L2:L1). Therefore, the load applied to the rolling element 402 becomes smaller, and the deformation of the inner pin 4 and the rolling element 402 caused by Hertzian contact stress also becomes smaller.

[0191] In this state, the deformation of the inner pin 4 as a beam caused by elastic deformation is greater than the deformation caused by Hertzian contact stress. Therefore, even if elastic deformation occurs due to Hertzian contact stress, the force (reaction force) acting from the inner pin 4 on the planetary gears 3 (first planetary gear 301 and second planetary gear 302) can be maintained at or above a constant level through at least the elastic deformation of the inner pin 4 itself. In other words, the inner pin 4 is kept in a pressed state relative to the inner circumferential surface 321 of the inner pin hole 32 of the first planetary gear 301 and the inner circumferential surface 321 of the inner pin hole 32 of the second planetary gear 302. As a result, the "preload" acting from the planetary gears 3 on the inner pin 4 is maintained.

[0192] Thus, in the gear assembly 1A of this embodiment, preload is applied by the bending moments generated in each of the plurality of inner pins 4. That is, in this embodiment, the preload is maintained by utilizing the fact that the amount of deformation caused by the elastic deformation of the inner pins 4 due to the bending moments acting on them is greater than the amount of deformation caused by the contact stress of Hertz. In other words, by utilizing the elasticity of the inner pins 4 themselves, the inner circumferential surface 321 of the inner pin hole 32 is pressed against the inner pin 4, thereby causing the preload to be applied from the planetary gear 3 to the inner pins 4. Therefore, apart from the inner pins 4, no other components for generating preload are required, thus reducing the number of components and contributing to the miniaturization of the gear assembly 1A.

[0193] However, the aforementioned pre-pressure is achieved through a negative clearance (negative gap) between the inner pin 4 and the inner circumferential surface 321 of the inner pin hole 32. The "negative clearance" referred to in this embodiment is the so-called "interference fit," which, when assembled according to the design, results in a mutually overlapping (pressing) relationship. For example, if a negative clearance of "X" (-X) is provided between the inner pin 4 and the inner circumferential surface 321 of the inner pin hole 32, then theoretically, viewed from the rotation axis Ax1 direction, the inner pin 4 is in a state where it extends "X" from the inner circumferential surface 321 of the inner pin hole 32 outwards from the inner circumferential surface 321 of the inner pin hole 32. In other words, during the assembly of the inner pin 4 and the planetary gear 3, to avoid a positive clearance between the inner pin 4 and the inner circumferential surface 321 of the inner pin hole 32, the inner circumferential surface 321 of the inner pin hole 32 is made to press against the inner pin 4 by making this clearance 0 or less. As a result, even when the inner pins 4 are not rotating relative to the internal gear 2, the planetary gear 3 exerts a pre-pressure (force F1, F2) on the inner pins 4 when the inner pins 4 are combined with the planetary gear 3.

[0194] In this embodiment, as an example, a negative gap of less than 1 / 100th of the diameter of each of the plurality of inner pins 4 is provided between each of the plurality of inner pins 4 and the inner peripheral surface 321 of each of the plurality of inner pin holes 32. In summary, in this embodiment, the size of the negative gap used to achieve the preload is set to be 0 or more and less than 1 / 100th of the diameter of each of the inner pins 4. As an example, when the diameter of the pin 23 is about 5 mm, the negative gap between the inner pin 4 and the inner peripheral surface 321 of the inner pin hole 32 is preferably 0 mm or more and 0.05 mm or less. Furthermore, the size of the negative gap between the inner pin 4 and the inner peripheral surface 321 of the inner pin hole 32 is preferably 1 / 200th of the diameter of the inner pin 4, more preferably 1 / 300th or less.

[0195] In this embodiment, a negative clearance is set for all of the multiple (here, 6) inner pins 4. Therefore, when the multiple inner pins 4 are not rotating relative to the internal gear 2, a preload is applied from the planetary gear 3 by pressing the inner circumferential surfaces 321 of each of the multiple inner pin holes 32 against all of the multiple inner pins 4. However, this structure is not necessary for the gear assembly 1A, and a portion of the multiple inner pins 4 may not be subject to a preload.

[0196] Furthermore, in this embodiment, preload is applied to the inner pin 4 not only from the planetary gear 3 but also from the rolling bearings 41 and 42. That is, a negative clearance is set between the multiple rolling elements 402 and the inner pin 4 regarding the pair of rolling bearings 41 and 42 that hold the inner pin 4. Specifically, the difference between the inner diameter of the outer ring 401 and the diameter of the inner pin 4 is less than twice the diameter of the rolling element 402. Thus, a negative clearance (interference) of 0 or more is generated between the inner pin 4 and the rolling element 402. As an example, the fitting tolerance of the inner pin 4 relative to the rolling bearings 41 and 42 is preferably "k6" or more, and more preferably "p6". In summary, each of the multiple sets of rolling bearings 41 and 42 has multiple rolling elements 402. Preload is applied to the inner pin side of each of the multiple inner pins 4 by pressing against the multiple rolling elements 402.

[0197] According to this structure, reducing or eliminating the gap between the inner pin 4 and the rolling bearings 41 and 42, which serve as retaining parts 410 and 420, can suppress the wobble of the inner pin 4 caused by the gap. As a result, according to the gear device 1A of this embodiment, the backlash caused by the gap between the inner pin 4 and the rolling bearings 41 and 42 can be reduced or eliminated, thereby making it easier to suppress the angle transmission error to a small extent.

[0198] In this embodiment, for the multiple (here, 6) inner pins 4, a negative clearance is set for the rolling bearings 41 and 42. Therefore, the rolling bearings 41 and 42 apply an inner pin-side preload to all of the multiple inner pins 4. However, this structure is not necessary for the gear device 1A, and it is also possible to not apply an inner pin-side preload to a portion of the multiple inner pins 4.

[0199] The configuration of the rolling bearings 41 and 42 in this embodiment will be described in more detail below.

[0200] First, such as Figure 11 As shown, the arrangement of multiple sets of rolling bearings 41, 42 in the direction parallel to the rotation axis Ax1 overlaps at least partially with the first bearing 91 and the second bearing 92. That is, in the direction parallel to the rotation axis Ax1, at least a portion of the rolling bearing 41 is in the same position as the first bearing 91, and at least a portion of the rolling bearing 42 is in the same position as the second bearing 92. Particularly in this embodiment, the width dimension (in the direction parallel to the rotation axis Ax1) of each of the first bearing 91 and the second bearing 92 is smaller than the width dimension of each of the rolling bearings 41 and 42. Therefore, in the direction parallel to the rotation axis Ax1, each bearing of the first bearing 91 and the second bearing 92 is housed within the respective range of each of the rolling bearings 41 and 42. In other words, each bearing of the first bearing 91 and the second bearing 92 is arranged inside each of the rolling bearings 41 and 42.

[0201] Thus, the gear device 1A of this embodiment includes an inner bearing member (first bearing 91 and second bearing 92) that holds the eccentric shaft 7, which causes the planetary gear 3 to oscillate eccentrically, so that it can rotate relative to the inner ring 61. Here, in a direction parallel to the rotation axis Ax1, at least a portion of multiple sets of rolling bearings 41, 42 are located at the same position as the inner bearing member (first bearing 91 and second bearing 92). That is, the first bearing 91 and the second bearing 92 constitute an "inner bearing member" that holds the eccentric shaft 7, which causes the planetary gear 3 to oscillate eccentrically, so that it can rotate relative to the inner ring 61 (bearing member 6A) via the support flange 18 and the output flange 19. Thus, in this embodiment, the space originally provided outside the inner bearing member (first bearing 91 and second bearing 92) of the gear device 1A is used as the space for the rolling bearings 41, 42. Therefore, the increase in the size of the gear device 1A in the direction parallel to the rotation axis Ax1 caused by the provision of the rolling bearings 41, 42 can be suppressed.

[0202] Furthermore, such as Figure 11As shown, regarding the arrangement of multiple sets of rolling bearings 41, 42 in the direction parallel to the rotation axis Ax1, the first bearing member 601A and the second bearing member 602A are in positions that overlap at least partially. That is, in the direction parallel to the rotation axis Ax1, at least a portion of the rolling bearing 41 is in the same position as the first bearing member 601A, and at least a portion of the rolling bearing 42 is in the same position as the second bearing member 602A. Particularly in this embodiment, the width direction (direction parallel to the rotation axis Ax1) of each of the first bearing member 601A and the second bearing member 602A is approximately the same as the width direction of each of the rolling bearings 41, 42. Therefore, in the direction parallel to the rotation axis Ax1, within the respective range of the rolling bearings 41, 42, each bearing member of the first bearing member 601A and the second bearing member 602A is included. In other words, each bearing member of the first bearing member 601A and the second bearing member 602A is provided on the outer side of each of the rolling bearings 41, 42.

[0203] In this embodiment, at least a portion of the multiple sets of rolling bearings 41 and 42 are positioned in the same direction as the bearing members 6A (first bearing member 601A and second bearing member 602A) in the direction parallel to the rotation axis Ax1. Thus, in this embodiment, the space originally located inside the bearing members 6A (first bearing member 601A and second bearing member 602A) of the gear device 1A is used as the space for the rolling bearings 41 and 42. Therefore, the increase in the size of the gear device 1A in the direction parallel to the rotation axis Ax1 caused by the installation of the rolling bearings 41 and 42 can be suppressed.

[0204] In this embodiment, in particular, the rolling bearings 41 and 42 are disposed outside the inner bearing members (first bearing 91 and second bearing 92) and inside the bearing member 6A (first bearing member 601A and second bearing member 602A). In other words, the rolling bearings 41 and 42 are disposed using the space between the inner bearing members (first bearing 91 and second bearing 92) and the bearing member 6A (first bearing member 601A and second bearing member 602A). Therefore, the increase in the size of the gear device 1A in the radial direction (orthogonal to the rotation axis Ax1) caused by the installation of the rolling bearings 41 and 42 can be suppressed.

[0205] On the other hand, the arrangement of the multiple sets of rolling bearings 41, 42, as observed from a direction parallel to the rotation axis Ax1, is essentially the same as the arrangement of the multiple inner pins 4. That is, as... Figure 16 and Figure 17As shown, viewed from a direction parallel to the rotation axis Ax1, with a virtual circle VC1 passing through the centers of multiple inner pins 4, multiple sets of rolling bearings 41, 42 are arranged on the virtual circle VC1. In this embodiment, particularly as... Figure 18 As shown, viewed from a direction parallel to the rotation axis Ax1, multiple sets of rolling bearings 41 and 42 are arranged at equal intervals in the circumferential direction around the rotation axis Ax1. Figure 18 The configuration of rolling bearing 41 is shown, and the configuration of rolling bearing 42 is the same. Additionally, in Figure 18 In the text, even in cross-sections, section lines are omitted.

[0206] That is, multiple sets of rolling bearings 41, 42 are arranged at equal intervals along the circumference of the virtual circle VC1. In other words, when viewed from a direction parallel to the rotation axis Ax1, the virtual circle VC1 passes through the center of each of the multiple rolling bearings 41 (or 42), and the distance between two adjacent rolling bearings 41 (or 42) on the virtual circle VC1 is uniform for the multiple rolling bearings 41 (or 42). According to this arrangement, multiple inner pins 4 are held by the multiple sets of rolling bearings 41, 42, and when driven by the gear device 1A, the force applied to the multiple inner pins 4 can be evenly distributed.

[0207] Furthermore, such as Figure 18 As shown, in this embodiment, when viewed from a direction parallel to the rotation axis Ax1, the center of the virtual circle VC1, which passes through the centers of the multiple sets of rolling bearings 41, 42, coincides with the rotation axis Ax1. In other words, the center of the virtual circle VC1 is equal to the center of the gear body 22 of the internal gear 2, or the center of the pitch circle of the internal gear 21, and is located on the rotation axis Ax1. According to this structure, the center of the gear body 22 of the internal gear 2 and the rotation center of the multiple inner pins 4 relative to the internal gear 2 can be easily and accurately maintained on the rotation axis Ax1. As a result, in the gear device 1A, there is an advantage that it is less likely to generate vibrations due to poor centering and reduce transmission efficiency.

[0208] <Example>

[0209] like Figure 19 As shown, the gear device 1A of this embodiment, together with the first component 201 and the second component 202, constitutes a robot joint device 200. In other words, the robot joint device 200 of this embodiment includes the gear device 1A, the first component 201, and the second component 202. The first component 201 is fixed by the outer ring 62. The second component 202 is fixed by the inner ring 61. Figure 19 yes Figure 13 A schematic diagram of a robot articulation device 200, equivalent to a sectional view along line B1-B1. Figure 19 The first component 201 and the second component 202 are schematically shown in the figure.

[0210] In this embodiment, as an example, the first member 201 is fixed to a plurality of mounting holes 111 formed in the housing 10, thereby indirectly fixed relative to the outer ring 62 of the bearing member 6A. The second member 202 is fixed relative to a plurality of flange bolt holes 192 formed in the output flange 19, thereby indirectly fixed relative to the inner ring 61 of the bearing member 6A.

[0211] The robot joint device 200 configured in this way functions as a joint device by rotating the first component 201 and the second component 202 relative to each other about the rotation axis Ax1. Here, this is achieved by the drive source 101 (see reference 101). Figure 1 The eccentric shaft 7 of the drive gear device 1A causes the first component 201 and the second component 202 to rotate relative to each other. At this time, the rotation (input rotation) generated by the drive source 101 is reduced in the gear device 1A with a relatively high reduction ratio, and the first component 201 or the second component 202 is driven with a relatively high torque. That is to say, the first component 201 and the second component 202 connected by the gear device 1A can perform bending and stretching movements with the rotation axis Ax1 as the center.

[0212] The robot joint device 200 is used, for example, in robots such as horizontal articulated robots (jointed robots). Furthermore, the robot joint device 200 is not limited to horizontal articulated robots; for example, it can also be used in industrial robots other than horizontal articulated robots, or robots other than industrial robots. Additionally, the gear device 1A of this embodiment is not limited to the robot joint device 200; for example, as a wheel device such as a hub motor, it can also be used in vehicles such as Automated Guided Vehicles (AGVs).

[0213] <Variation Example>

[0214] Implementation method one is merely one of the various implementations of the embodiments of this disclosure. Implementation method one can be modified in various ways, such as by design, as long as it achieves the purpose of the embodiments of this disclosure. Furthermore, the accompanying drawings referenced in the embodiments of this disclosure are all schematic diagrams, and the ratios of the size and thickness of each structural element in the drawings are not necessarily limited to reflecting actual dimensional ratios. Hereinafter, variations of implementation method one are listed. The variations described below can be appropriately combined and applied.

[0215] In Embodiment 1, two types of gear devices 1A are illustrated with planetary gears 3, but gear device 1A may include three or more planetary gears 3. For example, when gear device 1A includes three planetary gears 3, it is preferable that these three planetary gears 3 are arranged about the rotation axis Ax1 with a phase difference of 120 degrees. Alternatively, gear device 1A may also include only one planetary gear 3. Or, when gear device 1A includes three planetary gears 3, two of these three planetary gears 3 may be in the same phase, and the remaining planetary gear 3 may be arranged about the rotation axis Ax1 with a phase difference of 180 degrees. In this case, the three planetary gears 3 themselves function as "support members" supporting the respective inner pins 4 to counteract the torque M1 (refer to) generated in the respective inner pins 4 due to preload. Figure 13 ).

[0216] In addition, regarding the inner pin 4, its two ends do not necessarily have to be held by the retaining parts 410 and 420 (rolling bearings 41 and 42), and only one end may be held by the retaining parts 410 and 420 (rolling bearings 41 and 42).

[0217] Furthermore, in the direction parallel to the rotation axis Ax1, the multiple sets of rolling bearings 41, 42 may not be positioned at the same location as the inner bearing members (first bearing 91 and second bearing 92). For example, the multiple sets of rolling bearings 41, 42 may also be configured to be arranged side-by-side with the inner bearing members (first bearing 91 and second bearing 92) in the direction parallel to the rotation axis Ax1. Similarly, in the direction parallel to the rotation axis Ax1, the multiple sets of rolling bearings 41, 42 may not be positioned at the same location as the bearing member 6A (first bearing member 601A and second bearing member 602A). For example, the multiple sets of rolling bearings 41, 42 may also be configured to be arranged side-by-side with the bearing member 6A (first bearing member 601A and second bearing member 602A) in the direction parallel to the rotation axis Ax1.

[0218] Furthermore, when viewed from a direction parallel to the rotation axis Ax1, the multiple sets of rolling bearings 41 and 42 may not be arranged at equal intervals in the circumferential direction around the rotation axis Ax1. Moreover, when viewed from a direction parallel to the rotation axis Ax1, the center of the virtual circle VC1 passing through the center of the multiple sets of rolling bearings 41 and 42 may not coincide with the rotation axis Ax1.

[0219] 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 Embodiment 1 are merely examples and can be appropriately modified.

[0220] Furthermore, the bearing component 6A, like the basic structure, can be either a crossed roller bearing or an angular contact ball bearing. However, the bearing component 6A is preferably a four-point contact ball bearing, which can withstand radial loads, thrust loads (along the direction of the rotation axis Ax1), and bending forces (bending moment loads) on the rotation axis Ax1.

[0221] Furthermore, the eccentric bearing 5 is not limited to roller ball bearings; for example, it can also be a deep groove ball bearing or an angular contact ball bearing.

[0222] Furthermore, the materials of the various structural elements of the gear device 1A are not limited to metal; for example, they can be resins such as engineering plastics.

[0223] Furthermore, the gear device 1A is only required to output the relative rotation between the inner ring 61 and the outer ring 62 of the bearing member 6, and is not limited to outputting the rotational force of the inner ring 61 (support flange 18 and output flange 19). For example, the rotational force of the outer ring 62 (housing 10) that rotates relative to the inner ring 61 can also be output.

[0224] 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.

[0225] Additionally, the gear assembly 1A may include internal rollers. That is, in the gear assembly 1A, each of the plurality of internal pins 4 does not necessarily have to be in direct contact with the inner circumferential surface 321 of the internal pin hole 32; internal rollers may be sandwiched between each of the plurality of 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.

[0226] Furthermore, it is not necessary for each of the multiple inner pins 4 to be held in a self-rotating state within the inner ring 61, and for each of the multiple inner pins 4 to be held by the rolling bearings 41 and 42. For example, each of the multiple inner pins 4 can be held directly by the inner ring 61, or by a bracket flange 18 or output flange 19 integrated with the inner ring 61.

[0227] In addition, the support ring 8A is not necessary in the gear device 1A. The support ring 8A can be omitted appropriately, or the support body 8 described in the basic structure can be used instead of the support ring 8A.

[0228] Furthermore, the gear device 1A only needs to employ at least one of the studies on the preload of the inner pin 4 and the studies on the support structure 40 of the inner pin 4; it is not necessary to employ both. That is, the gear device 1A can employ either the case where the preload is applied by pressing the inner circumferential surface 321 of the inner pin hole 32 against the inner pin 4 (study on the preload of the inner pin 4) or the case where rolling bearings 41 and 42 are provided to hold the inner pin 4 (study on the support structure 40 of the inner pin 4).

[0229] Furthermore, gear assembly 1A only needs to employ at least one of the studies on the preload of the inner pin 4 and the study on the support structure 40 of the inner pin 4; therefore, other structures can be appropriately omitted or modified based on the basic structure. For example, in gear assembly 1A, similar to the first related technology, the inner pin 4 can also be held in a pressed-in state relative to the inner ring 61 (or the bracket flange 18 or output flange 19 integrated with the inner ring 61). In this case, each of the multiple inner pins 4 is held in a non-rotating state relative to the inner ring 61. In addition, each of the multiple inner pins 4 only needs to be arranged in the same position as the bearing member 6A in the axial direction.

[0230] (Summarize)

[0231] As described above, the first-form internal meshing planetary gear assembly (1, 1A) includes bearing members (6, 6A), internal gears (2), planetary gears (3), multiple inner pins (4), and multiple sets of rolling bearings (41, 42). The bearing members (6, 6A) have an outer ring (62) and an inner ring (61) disposed inside the outer ring (62), supporting the inner ring (61) so that it can rotate relative to the outer ring (62) about a rotation axis (Ax1). 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 multiple inner pins (4), while being inserted into the multiple inner pin holes (32) formed in the planetary gear (3), rotate relative to the internal gear (2) while revolving within the inner pin holes (32). Multiple sets of rolling bearings (41, 42) hold the inner pins of multiple inner pins (4) on both sides of the planetary gear (3) in a direction parallel to the rotation axis (Ax1). The inner pins of the multiple inner pins (4) are held by the rolling bearings (41, 42) in a rotatable state.

[0232] According to this structure, the inner pin (4) can rotate on its own and is less prone to loss due to frictional resistance between the inner circumferential surface (321) of the inner pin hole (32) and the inner pin (4), thus the inner roller can be omitted. Therefore, since the inner roller can be omitted and the diameter of the inner pin hole (32) can be kept relatively small, the planetary gear (3) can be miniaturized, and the entire internal meshing planetary gear device (1, 1A) can also be easily miniaturized. Moreover, the inner pin (4) is held by rolling bearings (41, 42) on both sides of the planetary gear (3) in the direction parallel to the rotation axis (Ax1), so it is less prone to loss due to frictional resistance when the inner pin (4) rotates.

[0233] The second configuration of the internal meshing planetary gear assembly (1, 1A), based on the first configuration, further includes an inner bearing assembly (first bearing 91, second bearing 92). The inner bearing assembly (first bearing 91, second bearing 92) maintains the eccentric shaft (7) that causes the planetary gear (3) to oscillate eccentrically so that it can rotate relative to the inner ring (61). In a direction parallel to the rotation axis (Ax1), at least a portion of the plurality of rolling bearings (41, 42) are in the same position as the inner bearing assembly (first bearing 91, second bearing 92).

[0234] According to this configuration, it is possible to suppress the increase in size of the internal meshing planetary gear device (1, 1A) in the direction parallel to the rotating shaft (Ax1) caused by the installation of rolling bearings (41, 42).

[0235] In the third form of the internal meshing planetary gear device (1, 1A), based on the second form, at least a portion of multiple sets of rolling bearings (41, 42) are positioned in the same place as the bearing members (6, 6A) in a direction parallel to the rotating shaft (Ax1).

[0236] According to this configuration, it is possible to suppress the increase in size of the internal meshing planetary gear device (1, 1A) in the direction parallel to the rotating shaft (Ax1) caused by the installation of rolling bearings (41, 42).

[0237] In the fourth form of the internal meshing planetary gear device (1, 1A), based on any one of the first to third forms, when the multiple inner pins (4) are not rotating relative to the internal gear (2), they press against each of the multiple inner pins (4) through the inner circumferential surface (321) of each of the multiple inner pin holes (32), thereby exerting a pre-pressure on each of the multiple inner pins (4).

[0238] According to this configuration, it is possible to reduce or eliminate at least the backlash caused by the gap between the inner circumferential surface (321) of the inner pin hole (32) and the inner pin (4), thereby minimizing the angle transmission error. Moreover, even though a preload is applied to the inner pin (4), it is not easy for losses caused by frictional resistance to occur when the inner pin (4) rotates.

[0239] In the fifth form of the internal meshing planetary gear device (1, 1A), based on the fourth form, a preload is applied by the bending moment of each of the multiple inner pins (4).

[0240] According to this configuration, apart from the inner pin (4), no other components are needed to generate preload, thus reducing the number of components. As a result, it helps to miniaturize the internal meshing planetary gear assembly (1, 1A).

[0241] In the sixth form of the internal meshing planetary gear device (1, 1A), based on any one of the first to fifth forms, multiple sets of rolling bearings (41, 42) each have multiple rolling elements (402). By pressing the multiple rolling elements (402) against the individual inner pins of the multiple inner pins (4), an inner pin-side preload is applied to each of the multiple inner pins (4).

[0242] According to this structure, the tooth backlash caused by the gap between the inner pin (4) and the rolling bearings (41, 42) can be reduced or eliminated, thereby minimizing the angle transmission error.

[0243] In the seventh form of the internal meshing planetary gear device (1, 1A), based on any one of the first to sixth forms, when viewed from a direction parallel to the rotation axis (Ax1), multiple sets of rolling bearings (41, 42) are arranged at equal intervals in the circumferential direction around the rotation axis (Ax1).

[0244] According to this configuration, multiple sets of rolling bearings (41, 42) are used to hold multiple inner pins (4), and when driven by the internal meshing planetary gear device (1, 1A), the force applied to the multiple inner pins (4) can be evenly distributed.

[0245] In the eighth form of the internal meshing planetary gear device (1, 1A), based on any of the first to seventh forms, when viewed from a direction parallel to the rotation axis (Ax1), the center of the virtual circle (VC1) passing through the center of the multiple sets of rolling bearings (41, 42) coincides with the center of the rotation axis (Ax1).

[0246] Based on this design, it has the advantage of being less prone to adverse conditions such as vibration caused by poor centering and decreased transmission efficiency.

[0247] The ninth form of the robot joint device (200) includes: an internal meshing planetary gear device (1, 1A) of any one of the first to eighth forms; a first member (201) fixed by an outer ring (62); and a second member (202) fixed by an inner ring (61).

[0248] According to this configuration, the diameter of the inner pin hole (32) can be kept relatively small, thus enabling the miniaturization of the planetary gear (3) and the overall miniaturization of the robot joint device (200).

[0249] 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.

[0250] Explanation of reference numerals in the attached figures

[0251] 1.1A Internal Meshing Planetary Gear Assembly

[0252] 2. Internal gears

[0253] 3 Planetary gears

[0254] 4. Domestic sales

[0255] 6. 6A bearing components

[0256] 7 Eccentric Shaft

[0257] 21 Internal teeth

[0258] 31 External teeth

[0259] 32 Inner pin holes

[0260] 41, 42 Rolling bearings

[0261] 61 Inner Circle

[0262] 62 Outer ring

[0263] 91 First bearing (inner bearing component)

[0264] 92 Second bearing (inner bearing component)

[0265] 200 Robotic Joint Devices

[0266] 201 First Component

[0267] 202 Second Component

[0268] 321 Inner circumferential surface

[0269] 402 Rolling element

[0270] 410, 420 Holding Section

[0271] 601A (First) Bearing Component

[0272] 602A (Second) Bearing Component

[0273] Ax1 Rotation Axis

[0274] VC1 Virtual Circle

[0275] Industrial applicability

[0276] According to embodiments of this disclosure, it is possible to provide an internally meshing planetary gear device and a joint device for robots that are easily miniaturized.

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 so as to be able to rotate relative to the outer ring about a rotation axis; 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; Multiple inner pins, while being respectively inserted into the multiple inner pin holes formed by the planetary gear, revolve within the inner pin holes and rotate relative to the internal gear. and Multiple sets of rolling bearings, positioned relative to the planetary gear on both sides in a direction parallel to the axis of rotation, hold the individual inner pins of the plurality of inner pins. Each of the plurality of inner pins is held in its respective set of rolling bearings in a state that allows it to rotate on its own.

2. The internal meshing planetary gear device according to claim 1, wherein, The internal meshing planetary gear assembly also includes an inner bearing component that maintains the eccentric shaft of the planetary gear, which oscillates eccentrically, in a rotatable manner relative to the inner ring. In a direction parallel to the rotation axis, at least a portion of the plurality of rolling bearings are positioned in the same location as the inner bearing member.

3. The internal meshing planetary gear device according to claim 1 or 2, wherein, In a direction parallel to the rotation axis, at least a portion of the plurality of rolling bearings are positioned in the same location as the bearing member.

4. The internal meshing planetary gear device according to claim 1 or 2, wherein, When the plurality of inner pins are not rotating relative to the internal gear, they press against each inner pin through the inner circumference of their respective inner pin holes, thereby applying pre-pressure to each inner pin.

5. The internal meshing planetary gear device according to claim 4, wherein, The preload is applied by the bending moment generated in each of the plurality of inner pins.

6. The internal meshing planetary gear device according to claim 1 or 2, wherein, Each of the multiple sets of rolling bearings has multiple rolling elements. By pressing the multiple rolling elements against each of the multiple inner pins, a pre-pressure is applied to each of the multiple inner pins on the inner pin side.

7. The internal meshing planetary gear device according to claim 1 or 2, wherein, Viewed from a direction parallel to the axis of rotation, the multiple sets of rolling bearings are arranged at equal intervals in the circumferential direction around the axis of rotation.

8. The internal meshing planetary gear device according to claim 1 or 2, wherein, Viewed from a direction parallel to the axis of rotation, the center of the virtual circle passing through the center of the multiple sets of rolling bearings coincides with the axis of rotation.

9. A joint device for a robot, wherein, include: The internal meshing planetary gear device according to any one of claims 1 to 8; and The first component is fixed to the outer ring; and A second component fixed to the inner ring.

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