Internally meshing planetary gear unit

Abstract

To provide an inscribed meshing planetary gear device which makes troubles, such as deterioration of transfer efficiency, less likely to occur.SOLUTION: An internal gear 2 has internal teeth 21 and is fixed to an outer ring 62A. A planetary gear 3 has external teeth which partially mesh with the internal teeth 21. Multiple inner pins 4 are respectively inserted in multiple loose holes 32 formed at the planetary gear 3 and rotate relative to the internal gear 2 in the state while revolving in the loose holes 32. An inner ring 61A includes a first inner ring 601 and a second inner ring 602 which face each other in a direction parallel to a rotation axis Ax1 and their facing surfaces 601A, 602A contact with each other.SELECTED DRAWING: Figure 11

Description

[Technical field]

[0001] The present disclosure relates generally to an internally meshing planetary gear device, and more particularly to an internally meshing planetary gear device in which a planetary gear having external teeth is disposed inside an internal gear having internal teeth. [Background technology]

[0002] As a related art, a so-called eccentric oscillating type gear device is known in which a planetary gear internally meshes with an internal gear while eccentrically oscillating (for example, see Patent Document 1). In the gear device according to the related art, an eccentric body is formed integrally with an input shaft, and a planetary gear is attached to the eccentric body via an eccentric body bearing. External teeth such as a circular arc tooth shape are formed on the outer periphery of the planetary gear.

[0003] An internal gear is configured by rotatably mounting a number of outer pins (roller pins), each of which constitutes an internal tooth, on the inner peripheral surface of a gear body (internal gear body) that also serves as a casing. A number of loose fitting holes (inner roller holes) are formed in the planetary gear at appropriate intervals in the circumferential direction, and the inner pins and inner rollers are inserted into the loose fitting holes. The inner pins are connected to a carrier at one end side in the axial direction, and the carrier is rotatably supported by the casing via a cross roller bearing. This gear device can be used as a gear device that extracts from the carrier a rotation equivalent to the rotation component of the planetary gear when the internal gear is fixed. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2003-74646 A Summary of the Invention [Problem to be solved by the invention]

[0005] In the configuration of the related art described above, for example, with long-term use of the gear device, the lubricant may not reach all parts sufficiently, which may lead to problems such as a decrease in the transmission efficiency of the gear device.

[0006] An object of the present disclosure is to provide an internal meshing planetary gear device that is less susceptible to problems such as reduced transmission efficiency. [Means for solving the problem]

[0007] An internally meshing planetary gear device according to one aspect of the present disclosure includes a bearing member, an internal gear, a planetary gear, and a plurality of inner pins. The bearing member has an outer ring, an inner ring disposed inside the outer ring, and a plurality of rolling elements disposed between the outer ring and the inner ring, and the inner ring is supported so as to be rotatable 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, while being inserted into a plurality of loose fitting holes formed in the planetary gear, rotate relative to the internal gear while revolving within the loose fitting holes. The inner ring includes a first inner ring and a second inner ring that face each other in a direction parallel to the rotation axis and whose facing surfaces are in contact with each other.

[0008] An internally meshing planetary gear device according to one aspect of the present disclosure includes a bearing member, an internal gear, a planetary gear, and a plurality of internal pins. The bearing member has an outer ring, an inner ring disposed inside the outer ring, and a plurality of rolling elements disposed between the outer ring and the inner ring, and the inner ring is supported so as to be rotatable 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 multiple internal pins rotate relative to the internal gear while revolving within the multiple loose fitting holes, while being inserted into multiple loose fitting holes formed in the planetary gear. In the inner ring, a portion of the planetary gear side in a direction parallel to the rotation axis has multiple retaining holes into which the multiple internal pins are respectively inserted in a direction parallel to the rotation axis. Each of the multiple internal pins is retained by the inner ring in a rotatable state. Effect of the Invention

[0009] According to the present disclosure, it is possible to provide an internal meshing planetary gear device that is less susceptible to problems such as reduced transmission efficiency. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a perspective view showing a schematic configuration of an actuator including an internal meshing planetary gear device according to a basic configuration. [Diagram 2] FIG. 2 is a schematic exploded perspective view of the internal meshing planetary gear device as viewed from the output side of the rotary shaft. [Diagram 3] FIG. 3 is a schematic cross-sectional view of the internal meshing planetary gear device. [Figure 4] FIG. 4 is a cross-sectional view taken along line A1-A1 in FIG. 3, showing the internal meshing planetary gear device. [Figure 5A] FIG. 5A is a perspective view showing a planetary gear of the internal meshing planetary gear device alone. [Figure 5B] FIG. 5B is a front view showing a planetary gear of the internal meshing planetary gear device alone. [Figure 6A] FIG. 6A is a perspective view showing the bearing member of the internal meshing planetary gear device alone. [Figure 6B] FIG. 6B is a front view showing the bearing member of the internal meshing planetary gear device alone. [Figure 7A] FIG. 7A is a perspective view showing the eccentric shaft of the internal meshing planetary gear device alone. [Figure 7B] FIG. 7B is a front view showing the eccentric shaft of the internal meshing planetary gear unit alone. [Figure 8A] FIG. 8A is a perspective view showing the support body of the internal meshing planetary gear device alone. [Figure 8B] FIG. 8B is a front view showing the support body of the internal meshing planetary gear unit alone. [Figure 9] FIG. 9 is an enlarged view of an area Z1 in FIG. 3, showing the internal meshing planetary gear device. [Figure 10] FIG. 10 is a cross-sectional view taken along line B1-B1 in FIG. 3, showing the internal meshing planetary gear device. [Figure 11] FIG. 11 is a schematic cross-sectional view of an internal meshing planetary gear device according to the first embodiment. [Figure 12] FIG. 12 is a side view of the internal meshing planetary gear device as viewed from the output side of the rotary shaft. [Figure 13] FIG. 13 is a cross-sectional view taken along line A1-A1 in FIG. 11, showing the internal meshing planetary gear device. [Figure 14] FIG. 14 is a cross-sectional view taken along line B1-B1 in FIG. 11, showing the internal meshing planetary gear device, and a partially enlarged view thereof. [Figure 15] FIG. 15 is a schematic cross-sectional view of a main part of the internal meshing planetary gear device. [Figure 16] FIG. 16 is a schematic cross-sectional view of a main part of the internal meshing planetary gear device, and is a diagram showing a schematic view of a path of a lubricant. [Figure 17] FIG. 17 is a schematic cross-sectional view of a wheel assembly using the above internal meshing planetary gear device. [Figure 18A] FIG. 18A is a schematic cross-sectional view of a main part of an internal meshing planetary gear device according to a modified example of the first embodiment. [Figure 18B] FIG. 18B is a schematic cross-sectional view of a main part of an internal meshing planetary gear device according to a modified example of the first embodiment. [Figure 19A] FIG. 19A is a schematic cross-sectional view of a main part of an internal meshing planetary gear device according to the second embodiment. [Figure 19B] FIG. 19B is a cross-sectional view taken along line A1-A1 in FIG. 19A, showing a main part of the internal meshing planetary gear device. [Figure 20] FIG. 20 is a schematic cross-sectional view of a main part of the internal meshing planetary gear device, and is a diagram showing a schematic view of a path of a lubricant. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] (Basic configuration) (1) Overview An overview of the internally meshing planetary gear device 1 according to this basic configuration will be described below with reference to Figures 1 to 3. All of the drawings referred to in this disclosure are schematic drawings, and the ratios of sizes and thicknesses of the components in the drawings do not necessarily reflect the actual dimensional ratios. For example, the tooth shapes, dimensions, number of teeth, etc. of the internal teeth 21 and external teeth 31 in Figures 1 to 3 are merely shown schematically for the purpose of explanation, and are not intended to be limited to the shapes shown in the drawings.

[0012] The internally meshing planetary gear device 1 (hereinafter, simply referred to as "gear device 1") according to this basic configuration is a gear device including an internal gear 2, a planetary gear 3, and a plurality of inner pins 4. In this gear device 1, the planetary gear 3 is disposed inside the annular internal gear 2, and further, an eccentric bearing 5 is disposed inside the planetary gear 3. The eccentric bearing 5 has an eccentric inner ring 51 and an eccentric outer ring 52, and the planetary gear 3 is oscillated by the eccentric inner ring 51 rotating (eccentric motion) around a rotation axis Ax1 (see FIG. 3) shifted from the center C1 (see FIG. 3) of the eccentric inner ring 51. The eccentric inner ring 51 rotates (eccentric motion) around the rotation axis Ax1, for example, by the rotation of an eccentric shaft 7 inserted into the eccentric inner ring 51. The internally meshing planetary gear device 1 further includes a bearing member 6 having an outer ring 62 and an inner ring 61. The inner ring 61 is disposed inside the outer ring 62 and is supported so as to be rotatable relative to the outer ring 62 .

[0013] The internal gear 2 has internal teeth 21 and is fixed to the outer ring 62. In particular, in this basic configuration, the internal gear 2 has an annular gear body 22 and multiple external pins 23. The multiple external pins 23 are held on the inner peripheral surface 221 of the gear body 22 in a rotatable state, forming the internal teeth 21. The planetary gear 3 has external teeth 31 that partially mesh with the internal teeth 21. In other words, the planetary gear 3 is inscribed with the internal gear 2 inside the internal gear 2, and a part of the external teeth 31 meshes with a part of the internal teeth 21. In this state, when the eccentric shaft 7 rotates, the planetary gear 3 swings, and the meshing position between the internal teeth 21 and the external teeth 31 moves in the circumferential direction of the internal gear 2, and a relative rotation according to the difference in the number of teeth between the planetary gear 3 and the internal gear 2 occurs between both gears (the internal gear 2 and the planetary gear 3). If the internal gear 2 is fixed, the planetary gear 3 rotates (spins) in accordance with the relative rotation of the two gears. As a result, the planetary gear 3 produces a rotation output that is reduced at a relatively high reduction ratio according to the difference in the number of teeth between the two gears.

[0014] This type of gear device 1 is used to extract the rotation equivalent to the rotation component of the planetary gear 3 as the rotation of an output shaft integrated with the inner ring 61 of the bearing member 6, for example. As a result, the gear device 1 functions as a gear device with a relatively high reduction ratio, with the eccentric shaft 7 as the input side and the output shaft as the output side. In the gear device 1 according to this basic configuration, the planetary gear 3 and the inner ring 61 are connected by the inner pins 4 in order to transmit the rotation equivalent to the rotation component of the planetary gear 3 to the inner ring 61 of the bearing member 6. The inner pins 4 are inserted into the loose fitting holes 32 formed in the planetary gear 3, respectively, and rotate relative to the internal gear 2 while revolving within the loose fitting holes 32. In other words, the loose fitting holes 32 have a larger diameter than the inner pins 4, and the inner pins 4 are movable so as to revolve within the loose fitting holes 32 while being inserted into the loose fitting holes 32. The oscillation component of the planetary gear 3, that is, the orbital component of the planetary gear 3, is absorbed by the loose fit between the loose fit holes 32 of the planetary gear 3 and the inner pin 4. In other words, the oscillation component of the planetary gear 3 is absorbed by the inner pins 4 moving so as to revolve within the respective loose fit holes 32. Therefore, the rotation (rotation component) of the planetary gear 3 excluding the oscillation component (orbital component) of the planetary gear 3 is transmitted to the inner ring 61 of the bearing member 6 by the inner pins 4.

[0015] In this type of gear device 1, the rotation of the planetary gear 3 is transmitted to the multiple inner pins 4 while the inner pin 4 revolves in the loose fitting hole 32 of the planetary gear 3. Therefore, as a first related technique, it is known to use an inner roller that is attached to the inner pin 4 and can rotate around the inner pin 4. That is, in the first related technique, the inner pin 4 is held in a state of being pressed into the inner ring 61 (or a carrier integrated with the inner ring 61), and when the inner pin 4 revolves in the loose fitting hole 32, the inner pin 4 slides against the inner circumferential surface 321 of the loose fitting hole 32. Therefore, as the first related technique, an inner roller is used to reduce loss due to frictional resistance between the inner circumferential surface 321 of the loose fitting hole 32 and the inner pin 4. However, if an inner roller is provided as in the first related technique, the loose fitting hole 32 needs to have a diameter that allows the inner pin 4 with the inner roller to revolve, and it is difficult to reduce the size of the loose fitting hole 32. If it is difficult to reduce the size of the loose fitting holes 32, this will hinder the size reduction (particularly the diameter reduction) of the planetary gears 3, and ultimately hinder the size reduction of the entire gear device 1. The gear device 1 according to this basic configuration makes it possible to provide an internal meshing planetary gear device 1 that is easy to reduce in size due to the following configuration.

[0016] That is, the gear device 1 according to this basic configuration includes a bearing member 6, an internal gear 2, a planetary gear 3, and a plurality of inner pins 4, as shown in Figs. 1 to 3. The bearing member 6 has an outer ring 62 and an inner ring 61 arranged 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 multiple inner pins 4 are inserted into multiple loose fitting holes 32 formed in the planetary gear 3, respectively, and rotate relative to the internal gear 2 while revolving within the loose fitting holes 32. Here, each of the multiple inner pins 4 is held by the inner ring 61 in a rotatable state. Furthermore, at least a part of each of the multiple inner pins 4 is arranged at the same position as the bearing member 6 in the axial direction of the bearing member 6.

[0017] According to this embodiment, each of the inner pins 4 is held by the inner ring 61 in a rotatable state, so that when the inner pin 4 revolves around the loose fitting hole 32, the inner pin 4 itself can rotate. Therefore, even if an inner roller that is attached to the inner pin 4 and can rotate around the inner pin 4 is not used, the loss due to the friction resistance between the inner peripheral surface 321 of the loose fitting hole 32 and the inner pin 4 can be reduced. Therefore, the gear device 1 according to this basic configuration has the advantage that the inner roller is not essential and it is easy to make it compact. Moreover, since at least a part of each of the inner pins 4 is disposed at the same position as the bearing member 6 in the axial direction of the bearing member 6, the dimension of the gear device 1 in the axial direction of the bearing member 6 can be kept small. In other words, compared to a configuration in which the bearing member 6 and the inner pin 4 are arranged (opposed) in the axial direction of the bearing member 6, the gear device 1 according to this basic configuration can reduce the dimension of the gear device 1 in the axial direction, which can contribute to further miniaturization (thinning) of the gear device 1.

[0018] Furthermore, if the dimensions of the planetary gear 3 are the same as those in the first related technology, it is possible to, for example, increase the number of inner pins 4 to smooth the transmission of rotation or to make the inner pins 4 thicker to improve strength, compared to the first related technology.

[0019] In addition, in this type of gear device 1, since the inner pin 4 needs to revolve in the loose fitting hole 32 of the planetary gear 3, as a second related technique, the multiple inner pins 4 may be held only by the inner ring 61 (or a carrier integrated with the inner ring 61). According to the second related technique, it is difficult to improve the accuracy of centering the multiple inner pins 4, and centering failure may lead to problems such as vibration generation and reduced transmission efficiency. In other words, the multiple inner pins 4 transmit the rotation component of the planetary gear 3 to the inner ring 61 of the bearing member 6 by rotating relatively to the internal gear 2 while revolving in the loose fitting hole 32. At this time, if the centering accuracy of the multiple inner pins 4 is insufficient and the rotation axis of the multiple inner pins 4 is misaligned or inclined with respect to the rotation axis of the inner ring 61, a centering failure state will occur, which may lead to problems such as vibration generation and reduced transmission efficiency. The gear device 1 according to this basic configuration can provide an internal meshing planetary gear device 1 that is less susceptible to problems caused by misalignment of the multiple inner pins 4 due to the following configuration.

[0020] That is, the gear device 1 according to this basic configuration includes an internal gear 2, a planetary gear 3, a plurality of inner pins 4, and a support 8, as shown in Figs. 1 to 3. The internal gear 2 has an annular gear body 22 and a plurality of outer pins 23. The outer pins 23 are held on an inner peripheral surface 221 of the gear body 22 in a rotatable state to form the internal teeth 21. The planetary gear 3 has outer teeth 31 that partially mesh with the internal teeth 21. The inner pins 4 are inserted into a plurality of loose fitting holes 32 formed in the planetary gear 3, respectively, and rotate relative to the gear body 22 while revolving within the loose fitting holes 32. The support 8 is annular and supports the plurality of inner pins 4. Here, the position of the support 8 is restricted by bringing an outer peripheral surface 81 into contact with the plurality of outer pins 23.

[0021] According to this embodiment, the multiple inner pins 4 are supported by the annular support 8, so that the multiple inner pins 4 are bundled by the support 8, and relative deviation and inclination of the multiple inner pins 4 are suppressed. Moreover, the outer peripheral surface 81 of the support 8 contacts the multiple outer pins 23, thereby regulating the position of the support 8. In short, the support 8 is centered by the multiple outer pins 23, and as a result, the multiple inner pins 4 supported by the support 8 are also centered by the multiple outer pins 23. Therefore, the gear device 1 according to this basic configuration has the advantage that it is easy to improve the accuracy of centering the multiple inner pins 4, and malfunctions caused by poor centering of the multiple inner pins 4 are less likely to occur.

[0022] 1, the gear device 1 according to this basic configuration constitutes an actuator 100 together with a driving source 101. In other words, the actuator 100 according to this basic configuration includes the gear device 1 and the driving source 101. The driving source 101 generates a driving force for oscillating the planetary gear 3. Specifically, the driving source 101 rotates the eccentric shaft 7 about the rotation axis Ax1, thereby oscillating the planetary gear 3.

[0023] (2) Definition In the present disclosure, "annular" refers to a ring-like shape that forms an enclosed space (region) at least in a plan view, and is not limited to a circular shape (annular shape) such as a perfect circle in a plan view, but may be, for example, an elliptical shape, a polygonal shape, etc. Furthermore, even if the shape has a bottom, such as a cup shape, it is included in the "annular" shape as long as the peripheral wall is annular.

[0024] In the present disclosure, "loose fit" means being fitted with a play (gap), and the loose fit hole 32 is a hole into which the inner pin 4 is loosely fitted. In other words, the inner pin 4 is inserted into the loose fit hole 32 with a spatial margin (gap) secured between the inner circumferential surface 321 of the loose fit hole 32. In other words, the diameter of at least the portion of the inner pin 4 inserted into the loose fit hole 32 is smaller (thinner) than the diameter of the loose fit hole 32. Therefore, the inner pin 4 is movable within the loose fit hole 32 in a state where it is inserted into the loose fit hole 32, that is, it is movable relative to the center of the loose fit hole 32. Therefore, the inner pin 4 is capable of revolving within the loose fit hole 32. However, it is not essential that a gap as a cavity is secured between the inner circumferential surface 321 of the loose fit hole 32 and the inner pin 4, and for example, this gap may be filled with a fluid such as a liquid.

[0025] In the present disclosure, "revolution" means that an object revolves around a rotation axis other than the central axis passing through the center (center of gravity) of the object, and when an object revolves, the center of the object moves along an orbit around the rotation axis. Therefore, for example, when an object rotates around an eccentric axis parallel to the central axis passing through the center (center of gravity) of the object, the object revolves around the eccentric axis as the rotation axis. As an example, the inner pin 4 revolves within the loose fitting hole 32 so as to revolve around the rotation axis passing through the center of the loose fitting hole 32.

[0026] In addition, in the present disclosure, one side of the rotating shaft Ax1 (left side in FIG. 3) may be referred to as the "input side," and the other side of the rotating shaft Ax1 (right side in FIG. 3) may be referred to as the "output side." In the example of FIG. 3, rotation is imparted to a 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 extracted from the "output side" of the rotating shaft Ax1. However, the "input side" and "output side" are merely labels added for the purpose of explanation, and are not intended to limit the positional relationship between the input and output as viewed from the gear device 1.

[0027] In the present disclosure, the term "rotation axis" refers to a virtual axis (straight line) that is the center of rotational motion of a rotating body. In other words, the rotation axis Ax1 is a virtual axis that does not have a physical body. The eccentric inner ring 51 rotates around the rotation axis Ax1.

[0028] In this disclosure, "internal teeth" and "external teeth" do not mean individual "tooth" but a collection (group) of multiple "teeth." In other words, the internal teeth 21 of the internal gear 2 are made up of a collection of multiple teeth arranged on the inner circumferential surface 221 of the internal gear 2 (gear body 22). Similarly, the external teeth 31 of the planetary gear 3 are made up of a collection of multiple teeth arranged on the outer circumferential surface of the planetary gear 3.

[0029] (3) Composition Hereinafter, the detailed configuration of the internal meshing planetary gear device 1 according to this basic configuration will be described with reference to Figs. 1 to 8B.

[0030] FIG. 1 is a perspective view showing a schematic configuration of an actuator 100 including a gear device 1. FIG. 1 shows a drive source 101 in a schematic manner. FIG. 2 is a schematic exploded perspective view of the gear device 1 as viewed from the output side of the rotation axis Ax1. FIG. 3 is a schematic cross-sectional view of the gear device 1. FIG. 4 is a cross-sectional view taken along the line A1-A1 in FIG. 3. However, in FIG. 4, hatching is omitted for components other than the eccentric shaft 7 even in the cross section. Furthermore, in FIG. 4, the inner peripheral surface 221 of the gear body 22 is omitted. FIG. 5A and FIG. 5B are a perspective view and a front view showing the planetary gear 3 alone. FIG. 6A and FIG. 6B are a perspective view and a front view showing the bearing member 6 alone. FIG. 7A and FIG. 7B are a perspective view and a front view showing the eccentric shaft 7 alone. FIG. 8A and FIG. 8B are a perspective view and a front view showing the support 8 alone.

[0031] (3.1) Overall Structure As shown in Figs. 1 to 3, the gear device 1 according to this basic configuration includes an internal gear 2, a planetary gear 3, a plurality of inner pins 4, an eccentric bearing 5, a bearing member 6, an eccentric shaft 7, and a support 8. In this basic configuration, the gear device 1 further includes a first bearing 91, a second bearing 92, and a case 10. In this basic configuration, the materials of the components of the gear device 1, such as the internal gear 2, the planetary gear 3, the plurality of inner pins 4, the eccentric bearing 5, the bearing member 6, the eccentric shaft 7, and the support 8, are metals such as stainless steel, cast iron, carbon steel for machine construction, chromium molybdenum steel, phosphor bronze, or aluminum bronze. The metals referred to here include metals that have been subjected to surface treatment such as nitriding.

[0032] In this basic configuration, an internal planetary gear device using a trochoidal tooth profile is illustrated as an example of the gear device 1. That is, the gear device 1 according to this basic configuration includes an internal planetary gear 3 having a trochoidal curved tooth profile.

[0033] In addition, as an example of this basic configuration, the gear device 1 is used in a state in which the gear body 22 of the internal gear 2, together with the outer ring 62 of the bearing member 6, is fixed to a fixed member such as the case 10. As a result, in accordance with the relative rotation between the internal gear 2 and the planetary gear 3, the planetary gear 3 rotates relative to the fixed member (such as the case 10).

[0034] Furthermore, in this basic configuration, when the gear device 1 is used in the actuator 100, a rotational force is applied as an input to the eccentric shaft 7, and a rotational force is taken out as an output 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 the input rotation and the rotation of the output shaft integrated with the inner ring 61 as the output rotation. As a result, the gear device 1 can obtain an output rotation that is reduced at a relatively high reduction ratio relative to the input rotation.

[0035] The driving source 101 is a power generating source such as a motor (electric motor). The power generated by the driving source 101 is transmitted to the eccentric shaft 7 in the gear device 1. Specifically, the driving source 101 is connected to the eccentric shaft 7 via an input shaft, and the power generated by the driving source 101 is transmitted to the eccentric shaft 7 via the input shaft. This enables the driving source 101 to rotate the eccentric shaft 7.

[0036] Furthermore, in the gear device 1 according to this basic configuration, as shown in Fig. 3, 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 to which the input rotation is applied, and the output side rotation axis Ax1 is the rotation center of the inner ring 61 (and the output shaft) which generates the output rotation. In other words, in the gear device 1, an output rotation that is reduced at a relatively high reduction ratio with respect to the input rotation on the same axis is obtained.

[0037] The internal gear 2 is an annular part having internal teeth 21, as shown in FIG. 4. In this basic configuration, the internal gear 2 has an annular shape, with at least the inner peripheral surface being a perfect circle in a plan view. The internal teeth 21 are formed along the circumferential direction of the internal gear 2 on the inner peripheral surface of the annular internal gear 2. The teeth constituting the internal teeth 21 are all of the same shape, and are provided at equal pitch over the entire circumferential area of ​​the inner peripheral surface of the internal gear 2. In other words, the pitch circle of the internal teeth 21 is a perfect circle in a plan view. The center of the pitch circle of the internal teeth 21 is on the rotation axis Ax1. The internal gear 2 has a predetermined thickness in the direction of the rotation axis Ax1. The tooth traces of the internal teeth 21 are all parallel to the rotation axis Ax1. The dimension of the internal teeth 21 in the tooth trace direction is slightly smaller than the thickness direction of the internal gear 2.

[0038] Here, as described above, the internal gear 2 has an annular (circular) gear body 22 and a plurality of outer pins 23. The plurality of outer pins 23 are held on the inner circumferential surface 221 of the gear body 22 in a rotatable state, and constitute the internal teeth 21. In other words, the plurality of outer pins 23 function as a plurality of teeth that constitute the internal teeth 21. Specifically, as shown in FIG. 2, a plurality of grooves are formed on the inner circumferential surface 221 of the gear body 22 over the entire circumferential area. All of the plurality of grooves have the same shape and are provided at equal pitches. All of the plurality of grooves are parallel to the rotation axis Ax1, and are formed over the entire length of the gear body 22 in the thickness direction. The plurality of outer pins 23 are combined with the gear body 22 so as to fit into the plurality of grooves. Each of the plurality of outer pins 23 is held in a rotatable state within the groove. In addition, the gear body 22 (together with the outer ring 62) is fixed to the case 10. For this purpose, the gear body 22 is formed with a plurality of fixing holes 222 for fixing.

[0039] As shown in FIG. 4, the planetary gear 3 is an annular part having external teeth 31. In this basic configuration, the planetary gear 3 has a shape in which at least the outer circumferential surface is a perfect circle in a plan view. The outer circumferential surface of the annular planetary gear 3 has external teeth 31 formed along the circumferential direction of the planetary gear 3. The teeth constituting the external teeth 31 all have the same shape and are provided at equal pitches over the entire circumferential area of ​​the outer circumferential surface of the planetary gear 3. In other words, the pitch circle of the external teeth 31 is a perfect circle in a plan view. The center C1 of the pitch circle of the external teeth 31 is shifted from the rotation axis Ax1 by a distance ΔL (see FIG. 4). The planetary gear 3 has a predetermined thickness in the direction of the rotation axis Ax1. All of the external teeth 31 are formed over the entire length of the planetary gear 3 in the thickness direction. All of the tooth traces of the external teeth 31 are parallel to the rotation axis Ax1. In the planetary gear 3, unlike the internal gear 2, the external teeth 31 are formed integrally with the main body of the planetary gear 3 by a single metal member.

[0040] Here, the eccentric body bearing 5 and the eccentric shaft 7 are combined with the planetary gear 3. That is, the planetary gear 3 is formed with an opening 33 that opens in a circular shape. The opening 33 is a hole that penetrates the planetary gear 3 along the thickness direction. In a plan view, the center of the opening 33 and the center of the planetary gear 3 coincide with each other, and the inner peripheral surface of the opening 33 (the inner peripheral surface of the planetary gear 3) and the pitch circle of the external teeth 31 are concentric. The opening 33 of the planetary gear 3 accommodates the eccentric body bearing 5. Furthermore, the eccentric shaft 7 is inserted into (the eccentric inner ring 51 of) the eccentric body bearing 5, so that the eccentric body bearing 5 and the eccentric shaft 7 are combined with the planetary gear 3. When the eccentric shaft 7 rotates in a state where the eccentric body bearing 5 and the eccentric shaft 7 are combined with the planetary gear 3, the planetary gear 3 oscillates around the rotation axis Ax1.

[0041] The planetary gear 3 thus configured is disposed inside the internal gear 2. In plan view, the planetary gear 3 is formed to be one size smaller than the internal gear 2, and the planetary gear 3 is able to oscillate inside the internal gear 2 when combined with the internal gear 2. Here, external teeth 31 are formed on the outer peripheral surface of the planetary gear 3, and internal teeth 21 are formed on the inner peripheral surface of the internal gear 2. Therefore, when the planetary gear 3 is disposed inside the internal gear 2, the external teeth 31 and the internal teeth 21 face each other.

[0042] Furthermore, the pitch circle of the external teeth 31 is one size smaller than the pitch circle of the internal teeth 21. When the planetary gear 3 is inscribed in the internal gear 2, the center C1 of the pitch circle of the external teeth 31 is shifted from the center of the pitch circle of the internal teeth 21 (the rotation axis Ax1) by a distance ΔL (see FIG. 4). Therefore, the external teeth 31 and the internal teeth 21 face each other at least partially with a gap therebetween, and do not mesh with each other entirely in the circumferential direction. However, since the planetary gear 3 oscillates (revolves) around the rotation axis Ax1 inside the internal gear 2, the external teeth 31 and the internal teeth 21 partially mesh with each other. In other words, as the planetary gear 3 oscillates around the rotation axis Ax1, some of the teeth that make up the external teeth 31 mesh with some of the teeth that make up the internal teeth 21, as shown in FIG. 4. As a result, in the gear device 1, it is possible to mesh some of the external teeth 31 with some of the internal teeth 21.

[0043] Here, the number of teeth of the internal teeth 21 of the internal gear 2 is N (N is a positive integer) more than the number of teeth of the external teeth 31 of the planetary gear 3. In this basic configuration, as an example, N is "1", and the number of teeth (of the external teeth 31) of the planetary gear 3 is "1" more than the number of teeth (of the internal teeth 21) of the internal gear 2. Such a difference in the number of teeth between the planetary gear 3 and the internal gear 2 defines the reduction ratio of the output rotation to the input rotation in the gear device 1.

[0044] In addition, in this basic configuration, as an example, the thickness of the planetary gear 3 is smaller than the thickness of the gear body 22 of the internal gear 2. Furthermore, the dimension of the external teeth 31 in the tooth trace direction (direction parallel to the rotation axis Ax1) is smaller than the dimension of the internal teeth 21 in the tooth trace direction (direction parallel to the rotation axis Ax1). In other words, the external teeth 31 are contained within the range of the tooth trace of the internal teeth 21 in the direction parallel to the rotation axis Ax1.

[0045] In this basic configuration, as described above, the rotation equivalent to the rotation component of the planetary gear 3 is taken out as the rotation (output rotation) of the output shaft integrated with the inner ring 61 of the bearing member 6. For this purpose, the planetary gear 3 is connected to the inner ring 61 by a plurality of inner pins 4. As shown in FIG. 5A and FIG. 5B, the planetary gear 3 is formed with a plurality of loose fitting holes 32 for inserting a plurality of inner pins 4. The number of loose fitting holes 32 is the same as the number of inner pins 4, and in this basic configuration, as an example, 18 loose fitting holes 32 and 18 inner pins 4 are provided. Each of the plurality of loose fitting holes 32 is a hole that opens in a circular shape and penetrates the planetary gear 3 along the thickness direction. The plurality of loose fitting holes 32 (here, 18) are arranged at equal intervals in the circumferential direction on a virtual circle concentric with the opening 33.

[0046] The multiple inner pins 4 are components that connect the planetary gear 3 and the inner ring 61 of the bearing member 6. Each of the multiple inner pins 4 is formed in a cylindrical shape. The multiple inner pins 4 have the same diameter and length. The diameter of the inner pin 4 is one size smaller than the diameter of the loose-fitting hole 32. As a result, the inner pin 4 is inserted into the loose-fitting hole 32 with a spatial margin (gap) secured between the inner pin 4 and the inner circumferential surface 321 of the loose-fitting hole 32 (see FIG. 4).

[0047] The bearing member 6 has an outer ring 62 and an inner ring 61, and is a component for extracting 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 member 6 has a plurality of rolling elements 63 (see FIG. 3).

[0048] As shown in Figures 6A and 6B, the outer ring 62 and the inner ring 61 are both annular components. The outer ring 62 and the inner ring 61 both have an annular shape that is a perfect circle in a plan view. The inner ring 61 is one size smaller than the outer ring 62 and is disposed inside the outer ring 62. Here, since the inner diameter of the outer ring 62 is larger than the outer diameter of the inner ring 61, a gap is generated between the inner peripheral surface of the outer ring 62 and the outer peripheral surface of the inner ring 61.

[0049] The inner ring 61 has a plurality of retaining holes 611 into which the plurality of inner pins 4 are respectively inserted. The number of retaining holes 611 is the same as the number of inner pins 4, and in this basic configuration, as an example, 18 retaining holes 611 are provided. As shown in Figs. 6A and 6B, each of the plurality of retaining holes 611 opens in a circular shape and is a hole that penetrates the inner ring 61 along the thickness direction. The plurality of retaining holes 611 (here, 18) are arranged at equal intervals in the circumferential direction on a virtual circle that is concentric with the outer periphery of the inner ring 61. The diameter of the retaining hole 611 is equal to or larger than the diameter of the inner pin 4 and smaller than the diameter of the loose-fitting hole 32.

[0050] Furthermore, the inner ring 61 is integrated with the output shaft, and the rotation of the inner ring 61 is taken out as the rotation of the output shaft. Therefore, the inner ring 61 is formed with a plurality of output side mounting holes 612 (see FIG. 2) for mounting the output shaft. In this basic configuration, the plurality of output side mounting holes 612 are located inside the plurality of holding holes 611 and are arranged on an imaginary circle concentric with the outer periphery of the inner ring 61.

[0051] The outer ring 62 is fixed to a fixed member such as the case 10 together with the gear body 22 of the internal gear 2. For this reason, the outer ring 62 is formed with a plurality of through holes 621 for fixing. Specifically, as shown in Fig. 3, the outer ring 62 is fixed to the case 10 by fixing screws (bolts) 60 passing through the through holes 621 and the fixing holes 222 of the gear body 22 with the gear body 22 sandwiched between the outer ring 62 and the case 10.

[0052] The 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 in the circumferential direction of the outer ring 62. The multiple rolling elements 63 are all metal components of the same shape, and are provided at equal pitch over the entire area of ​​the outer ring 62 in the circumferential direction.

[0053] In this basic configuration, as an example, the bearing member 6 is a cross roller bearing. That is, the bearing member 6 has cylindrical rollers as rolling elements 63. The axis of the cylindrical rolling elements 63 is inclined at 45 degrees with respect to a plane perpendicular to the rotation axis Ax1 and perpendicular to the outer periphery of the inner ring 61. Furthermore, a pair of rolling elements 63 adjacent to each other in the circumferential direction of the inner ring 61 are arranged so that their axial directions are perpendicular to each other. The bearing member 6 made of such a cross roller bearing is easily subjected to a radial load, a thrust load (direction along the rotation axis Ax1), and a bending force (bending moment load) against the rotation axis Ax1. Moreover, a single bearing member 6 can withstand these three types of loads and ensure the necessary rigidity.

[0054] As shown in Figs. 7A and 7B, the eccentric shaft 7 is a cylindrical part. The eccentric shaft 7 has an axial center portion 71 and an eccentric portion 72. The axial center portion 71 has a cylindrical shape with at least an outer circumferential surface being a perfect circle in a plan view. The center (central axis) of the axial center portion 71 coincides with the rotation axis Ax1. The eccentric portion 72 has a disk shape with at least an outer circumferential surface being a perfect circle in a plan view. The center (central axis) of the eccentric portion 72 coincides with a center C1 that is offset from the rotation axis Ax1. Here, the distance ΔL (see Fig. 7B) between the rotation axis Ax1 and the center C1 is the amount of eccentricity of the eccentric portion 72 with respect to the axial center portion 71. The eccentric portion 72 has a flange shape that protrudes from the outer circumferential surface of the axial center portion 71 over the entire circumference at the center of the axial center portion 71 in the longitudinal direction (axial direction). According to the above-mentioned configuration, in the eccentric shaft 7, the axial center portion 71 rotates (turns) about the rotation axis Ax1, so that the eccentric portion 72 performs eccentric motion.

[0055] In this basic configuration, the shaft portion 71 and the eccentric portion 72 are integrally formed from a single metal member, thereby realizing a seamless eccentric shaft 7. The eccentric shaft 7 having such a shape is combined with the planetary gear 3 together with the eccentric bearing 5. Therefore, when the eccentric shaft 7 rotates in a state where the eccentric bearing 5 and the eccentric shaft 7 are combined with the planetary gear 3, the planetary gear 3 oscillates around the rotation axis Ax1.

[0056] Furthermore, the eccentric shaft 7 has a through hole 73 that passes through the shaft center portion 71 in the axial direction (longitudinal direction). The through hole 73 opens in a circular shape on both axial end surfaces of the shaft center portion 71. The center (central axis) of the through hole 73 coincides with the rotation axis Ax1. Cables such as a power line and a signal line can be passed through the through hole 73.

[0057] In this basic configuration, a rotational force is applied as an input from the driving source 101 to the eccentric shaft 7. Therefore, the eccentric shaft 7 is formed with a plurality of input side mounting holes 74 (see Figs. 7A and 7B) for mounting an input shaft connected to the driving source 101. In this basic configuration, the plurality of input side mounting holes 74 are arranged on a virtual circle concentric with the through hole 73 around the through hole 73 on one end face in the axial direction of the shaft center portion 71.

[0058] The eccentric bearing 5 has an eccentric outer ring 52 and an eccentric inner ring 51, and is a component for absorbing the rotation component of the rotation of the eccentric shaft 7 and transmitting only the rotation of the eccentric shaft 7 excluding the rotation component of the eccentric shaft 7, that is, only the oscillation component (revolution component) of the eccentric shaft 7, to the planetary gear 3. In addition to the eccentric outer ring 52 and the eccentric inner ring 51, the eccentric bearing 5 has a plurality of rolling elements 53 (see FIG. 3).

[0059] Both the eccentric outer ring 52 and the eccentric inner ring 51 are annular parts. Both the eccentric outer ring 52 and the eccentric inner ring 51 have an annular shape that is a perfect circle in a plan view. The eccentric inner ring 51 is one size smaller than the eccentric outer ring 52 and is disposed inside the eccentric outer ring 52. Here, since the inner diameter of the eccentric outer ring 52 is larger than the outer diameter of the eccentric inner ring 51, a gap is generated between the inner peripheral surface of the eccentric outer ring 52 and the outer peripheral surface of the eccentric inner ring 51.

[0060] The multiple rolling elements 53 are disposed in the gap between the eccentric outer ring 52 and the eccentric inner ring 51. The multiple rolling elements 53 are arranged side by side in the circumferential direction of the eccentric outer ring 52. The multiple rolling elements 53 are all metal parts of the same shape, and are provided at equal pitches over the entire circumferential direction of the eccentric outer ring 52. In this basic configuration, as an example, the eccentric bearing 5 is a deep groove ball bearing that uses balls as the rolling elements 53.

[0061] Here, the inner diameter of the eccentric inner ring 51 is equal to the outer diameter of the eccentric portion 72 of the eccentric shaft 7. The eccentric bearing 5 is combined with the eccentric shaft 7 in a state where the eccentric portion 72 of the eccentric shaft 7 is inserted into the eccentric inner ring 51. Moreover, the outer diameter of the eccentric outer ring 52 is equal to the inner diameter (diameter) of the opening 33 of the planetary gear 3. The eccentric bearing 5 is combined with the planetary gear 3 in a state where the eccentric outer ring 52 is fitted into the opening 33 of the planetary gear 3. In other words, the opening 33 of the planetary gear 3 accommodates the eccentric bearing 5 in a state where it is attached to the eccentric portion 72 of the eccentric shaft 7.

[0062] In addition, in this basic configuration, as an example, the dimension of the eccentric inner ring 51 in the eccentric bearing 5 in the width direction (direction parallel to the rotation axis Ax1) is approximately the same as the thickness of the eccentric part 72 of the eccentric shaft 7. The dimension of the eccentric outer ring 52 in the width direction (direction parallel to the rotation axis Ax1) is slightly smaller than the dimension of the eccentric inner ring 51 in the width direction. Furthermore, the dimension of the eccentric outer ring 52 in the width direction is larger than the thickness of the planetary gear 3. Therefore, in the direction parallel to the rotation axis Ax1, the planetary gear 3 is contained within the range of the eccentric bearing 5. On the other hand, the dimension of the eccentric outer ring 52 in the width direction is smaller than the dimension of the tooth trace direction of the internal teeth 21 (direction parallel to the rotation axis Ax1). Therefore, in the direction parallel to the rotation axis Ax1, the eccentric bearing 5 is contained within the range of the internal gear 2.

[0063] When the eccentric shaft 7 rotates in a state where the eccentric bearing 5 and the eccentric shaft 7 are combined with the planetary gear 3, the eccentric inner ring 51 rotates (eccentrically moves) in the eccentric bearing 5 around a rotation axis Ax1 that is shifted from the center C1 of the eccentric inner ring 51. At this time, the rotation component of the eccentric shaft 7 is absorbed by the eccentric bearing 5. Therefore, the rotation of the eccentric shaft 7 excluding the rotation component of the eccentric shaft 7, that is, only the oscillation component (revolution component) of the eccentric shaft 7 is transmitted to the planetary gear 3 by the eccentric bearing 5. Therefore, when the eccentric shaft 7 rotates in a state where the eccentric bearing 5 and the eccentric shaft 7 are combined with the planetary gear 3, the planetary gear 3 oscillates around the rotation axis Ax1.

[0064] As shown in Figs. 8A and 8B, the support 8 is an annular component that supports a plurality of inner pins 4. The support 8 has a plurality of support holes 82 into which the plurality of inner pins 4 are inserted. The support holes 82 are provided in the same number as the inner pins 4, and in this basic configuration, as an example, 18 support holes 82 are provided. As shown in Figs. 8A and 8B, each of the support holes 82 opens in a circular shape and is a hole that penetrates the support 8 along the thickness direction. The plurality of support holes 82 (here, 18) are arranged at equal intervals in the circumferential direction on a virtual circle that is concentric with the outer circumferential surface 81 of the support 8. The diameter of the support hole 82 is equal to or larger than the diameter of the inner pin 4 and smaller than the diameter of the loose fitting hole 32. In this basic configuration, 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.

[0065] As shown in FIG. 3, the support 8 is disposed so as to face the planetary gear 3 from one side (input side) of the rotation axis Ax1. The inner pins 4 are inserted into the support holes 82, so that the support 8 functions to bundle the inner pins 4. Furthermore, the position of the support 8 is restricted by contacting the outer circumferential surface 81 with the outer pins 23. This allows the support 8 to be centered by the outer pins 23, and as a result, the inner pins 4 supported by the support 8 are also centered by the outer pins 23. The support 8 will be described in detail in the section "(3.3) Support".

[0066] The first bearing 91 and the second bearing 92 are respectively mounted on the axial center portion 71 of the eccentric shaft 7. Specifically, as shown in FIG. 3, the first bearing 91 and the second bearing 92 are mounted on both sides of the eccentric portion 72 in the axial center portion 71 so as to sandwich the eccentric portion 72 in a direction parallel to the rotation axis Ax1. The first bearing 91 is disposed on the input side of the rotation axis Ax1 as viewed from the eccentric portion 72. The second bearing 92 is disposed on the output side of the rotation axis Ax1 as viewed from the eccentric portion 72. The first bearing 91 rotatably holds the eccentric shaft 7 relative to the case 10. The second bearing 92 rotatably holds the eccentric shaft 7 relative to the inner ring 61 of the bearing member 6. As a result, the axial center portion 71 of the eccentric shaft 7 is rotatably held at two locations on both sides of the eccentric portion 72 in a direction parallel to the rotation axis Ax1.

[0067] The case 10 is cylindrical and has a flange portion 11 on the output side of the rotating shaft Ax1. A plurality of installation holes 111 are formed in the flange portion 11 for fixing the case 10 itself. A bearing hole 12 is formed in the end face of the case 10 on the output side of the rotating shaft Ax1. The bearing hole 12 has a circular opening. A first bearing 91 is fitted into the bearing hole 12, whereby the first bearing 91 is attached to the case 10.

[0068] Furthermore, a plurality of threaded holes 13 are formed around the bearing hole 12 on the output side end face of the rotation axis Ax1 in the case 10. 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 case 10. Specifically, a fixing screw 60 is passed through a through hole 621 of the outer ring 62 and a fixing hole 222 of the gear body 22 and tightened into the threaded hole 13, thereby fixing the gear body 22 and the outer ring 62 to the case 10.

[0069] The gear device 1 according to this basic configuration further includes a plurality of oil seals 14, 15, 16, etc., as shown in FIG. 3. The oil seal 14 is attached to an input side end of the rotating shaft Ax1 of the eccentric shaft 7, and closes a gap between the case 10 and the eccentric shaft 7 (shaft center portion 71). The oil seal 15 is attached to an output side end of the rotating shaft Ax1 of the eccentric shaft 7, and closes a gap between the inner ring 61 and the eccentric shaft 7 (shaft center portion 71). The oil seal 16 is attached to an output side end face of the rotating shaft Ax1 of the bearing member 6, and closes a gap between the inner ring 61 and the outer ring 62. The space sealed by the plurality of oil seals 14, 15, 16 constitutes a lubricant retaining space 17 (see FIG. 9). The lubricant retaining space 17 includes a space between the inner ring 61 and the outer ring 62 of the bearing member 6. Furthermore, the lubricant retaining space 17 accommodates a plurality of outer pins 23, the planetary gear 3, the eccentric bearing 5, the support 8, a first bearing 91, a second bearing 92, and the like.

[0070] A lubricant is injected into the lubricant retaining space 17. The lubricant is liquid and can flow in the lubricant retaining space 17. Therefore, when the gear device 1 is used, the lubricant enters, for example, the meshing portion between the internal teeth 21 consisting of the multiple outer pins 23 and the external teeth 31 of the planetary gear 3. The term "liquid" in this disclosure includes liquid or gel-like substances. The term "gel-like" here means a state having intermediate properties between liquid and solid, and includes a colloidal state consisting of two phases, a liquid phase and a solid phase. For example, the "gel-like" includes a state called a gel or sol, such as an emulsion in which the dispersion medium is in a liquid phase and the dispersoid is in a liquid phase, and a suspension in which the dispersoid is in a solid phase. The "gel-like" also includes a state in which the dispersion medium is in a solid phase and the dispersoid is in a liquid phase. In this basic configuration, as an example, the lubricant is a liquid lubricating oil (oil).

[0071] In the gear device 1 configured as described above, a rotational force is applied to the eccentric shaft 7 as an input, and the eccentric shaft 7 rotates about the rotation axis Ax1, causing the planetary gear 3 to oscillate (revolve) around the rotation axis Ax1. At this time, the planetary gear 3 is inscribed in the internal gear 2 inside the internal gear 2, and oscillates with a part of the external teeth 31 meshed with a part of the internal teeth 21, so that the meshing position of the internal teeth 21 and the external teeth 31 moves in the circumferential direction of the internal gear 2. As a result, a relative rotation according to the difference in the number of teeth between the planetary gear 3 and the internal gear 2 occurs between the two gears (the internal gear 2 and the planetary gear 3). The rotation (rotation component) of the planetary gear 3, excluding the oscillation component (revolution component) of the planetary gear 3, is transmitted to the inner ring 61 of the bearing member 6 by the multiple inner pins 4. As a result, a rotation output reduced at a relatively high reduction ratio according to the difference in the number of teeth between the two gears is obtained from the output shaft integrated with the inner ring 61.

[0072] Incidentally, in the gear device 1 according to this embodiment, as described above, the difference in the number of teeth between the internal gear 2 and the planetary gear 3 defines the reduction ratio of the output rotation to the input rotation in the gear device 1. In other words, when the number of teeth of the internal gear 2 is "V1" and the number of teeth of the planetary gear 3 is "V2," the reduction ratio R1 is expressed by the following formula 1.

[0073] R1 = V2 / (V1-V2) (Equation 1) In other words, 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. As an example, the number of teeth V1 of the internal gear 2 is "52", the number of teeth V2 of the planetary gear 3 is "51", and the difference in the number of teeth (V1-V2) is "1", so from the above formula 1, the reduction ratio R1 is "51". In this case, when viewed from the input side of the rotation axis Ax1, when the eccentric shaft 7 rotates clockwise around the rotation axis Ax1 one revolution (360 degrees), the inner ring 61 rotates counterclockwise around the rotation axis Ax1 by the difference in the number of teeth of "1" (i.e., approximately 7.06 degrees).

[0074] According to the gear device 1 according to this basic configuration, such a high reduction ratio R1 can be realized by a combination of one gear stage (the internal gear 2 and the planetary gear 3).

[0075] Furthermore, the gear device 1 only needs to include at least an internal gear 2, a planetary gear 3, a plurality of inner pins 4, a bearing member 6, and a support body 8, and may further include, for example, a spline bush or the like as a component.

[0076] Incidentally, when the input rotation on the high-speed rotating side is accompanied by eccentric motion, as in the gear device 1 according to this basic configuration, if the weight balance of the rotating body rotating at high speed is not maintained, it may lead to vibration, etc., so the weight balance may be achieved using a counterweight or the like. That is, since a rotating body consisting of at least one of the eccentric inner ring 51 and a member (eccentric shaft 7) rotating together with the eccentric inner ring 51 performs eccentric motion at high speed, it is preferable to balance the weight of the rotating body with respect to the rotation axis Ax1. In this basic configuration, as shown in Figs. 3 and 4, a gap 75 is provided in a part of the eccentric portion 72 of the eccentric shaft 7, thereby balancing the weight of the rotating body with respect to the rotation axis Ax1.

[0077] In short, in this basic configuration, instead of adding a counterweight or the like, a part of the rotating body (here, the eccentric shaft 7) is hollowed out to reduce its weight, thereby balancing the weight of the rotating body with respect to the rotation axis Ax1. That is, the gear device 1 according to this basic configuration includes an eccentric bearing 5 that is housed in an opening 33 formed in the planetary gear 3 and oscillates the planetary gear 3. The eccentric bearing 5 has an eccentric outer ring 52 and an eccentric inner ring 51 that is disposed inside the eccentric outer ring 52. A rotating body consisting of at least one of the eccentric inner ring 51 and a member that rotates together with the eccentric inner ring 51 has a gap 75 in a part of the center C1 side of the eccentric outer ring 52 as viewed from the rotation axis Ax1 of the eccentric inner ring 51. In this basic configuration, the eccentric shaft 7 is a "member that rotates together with the eccentric inner ring 51" and corresponds to a "rotating body". Therefore, the gap 75 formed in the eccentric part 72 of the eccentric shaft 7 corresponds to the gap 75 of the rotating body. As shown in FIGS. 3 and 4, this gap 75 is located on the center C1 side when viewed from the rotation axis Ax1, and therefore acts to make the weight balance of the eccentric shaft 7 closer to uniform in the circumferential direction from the rotation axis Ax1.

[0078] More specifically, the gap 75 includes a recess formed on the inner circumferential surface of a through hole 73 that penetrates the rotor along the rotation axis Ax1 of the eccentric inner ring 51. That is, in this basic configuration, since the rotor is the eccentric shaft 7, the recess formed on the inner circumferential surface of the through hole 73 that penetrates the eccentric shaft 7 along the rotation axis Ax1 functions as the gap 75. In this way, by using the recess formed on the inner circumferential surface of the through hole 73 as the gap 75, it is possible to achieve weight balance of the rotor without changing the external appearance.

[0079] (3.2) Rotational structure of the inner pin Next, the rotation structure of the inner pin 4 of the gear device 1 according to this basic configuration will be described in more detail with reference to Fig. 9. Fig. 9 is an enlarged view of an area Z1 in Fig. 3.

[0080] First, as a premise, as described above, the multiple inner pins 4 are components that connect the planetary gear 3 and 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 rotation axis Ax1 in this basic configuration) is inserted into the loose fitting 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 rotation axis Ax1 in this basic configuration) is inserted into the retaining hole 611 of the inner ring 61.

[0081] Here, since the diameter of the inner pin 4 is slightly smaller than the diameter of the loose-fitting hole 32, a gap is secured between the inner pin 4 and the inner peripheral surface 321 of the loose-fitting hole 32, and the inner pin 4 is movable within the loose-fitting hole 32, that is, is movable relative to the center of the loose-fitting hole 32. On the other hand, the diameter of the retaining hole 611 is equal to or larger than the diameter of the inner pin 4, but is smaller than the diameter of the loose-fitting hole 32. In this basic configuration, the diameter of the retaining hole 611 is approximately the same as the diameter of the inner pin 4, and is slightly larger than the diameter of the inner pin 4. Therefore, the movement of the inner pin 4 within the retaining hole 611 is restricted, that is, the relative movement with respect to the center of the retaining hole 611 is prohibited. Therefore, the inner pin 4 is held in a state in which it can revolve within the loose-fitting hole 32 in the planetary gear 3, and is held in a state in which it cannot revolve within the retaining hole 611 relative to the inner ring 61. As a result, the oscillating component of the planetary gear 3, i.e., the orbital component of the planetary gear 3, is absorbed by the loose fit between the loose fit hole 32 and the inner pin 4, and the rotation (rotation component) of the planetary gear 3 excluding the oscillating component (orbital component) of the planetary gear 3 is transmitted to the inner ring 61 by the multiple inner pins 4.

[0082] Incidentally, in this basic configuration, the diameter of the inner pin 4 is slightly larger than the retaining hole 611, so that while the inner pin 4 is inserted into the retaining hole 611, it is prohibited from revolving within the retaining hole 611, but is able to rotate within the retaining hole 611. In other words, even when the inner pin 4 is inserted into the retaining hole 611, it is not press-fitted into the retaining hole 611, and is therefore able to rotate within the retaining hole 611. In this way, in the gear device 1 according to this basic configuration, each of the multiple inner pins 4 is held by the inner ring 61 in a rotatable state, so that when the inner pin 4 revolves within the loose-fitting hole 32, the inner pin 4 itself is able to rotate on its own axis.

[0083] In short, in this basic configuration, the inner pin 4 is held in a state in which it can both revolve and rotate within the loose fitting hole 32 relative to the planetary gear 3, and is held in a state in which it can only rotate within the retaining hole 611 relative to the inner ring 61. In other words, the multiple inner pins 4 can rotate (revolve) around the rotation axis Ax1 and can revolve within the multiple loose fitting holes 32 in a state in which their respective rotations are not restricted (a state in which they can rotate). Therefore, when the multiple inner pins 4 transmit the rotation (rotation component) of the planetary gear 3 to the inner ring 61, the inner pin 4 can rotate within the retaining hole 611 while revolving and rotating within the loose fitting hole 32. Therefore, when the inner pin 4 revolves within the loose fitting hole 32, the inner pin 4 is in a state in which it can rotate, and therefore rolls against the inner circumferential surface 321 of the loose fitting hole 32. In other words, the inner pin 4 revolves within the loose-fit hole 32 by rolling on the inner surface 321 of the loose-fit hole 32, so that losses due to frictional resistance between the inner surface 321 of the loose-fit hole 32 and the inner pin 4 are less likely to occur.

[0084] In this manner, in the configuration according to this basic configuration, since loss due to frictional resistance between the inner peripheral surface 321 of the loose fitting hole 32 and the inner pin 4 is unlikely to occur in the first place, it is possible to omit the inner roller. Therefore, in this basic configuration, a configuration is adopted in which each of the multiple inner pins 4 directly contacts the inner peripheral surface 321 of the loose fitting hole 32. In other words, in this basic configuration, the inner pin 4 without the inner roller is inserted into the loose fitting hole 32, and the inner pin 4 directly contacts the inner peripheral surface 321 of the loose fitting hole 32. As a result, the inner roller can be omitted and the diameter of the loose fitting hole 32 can be kept relatively small, so that the planetary gear 3 can be made smaller (especially the diameter can be made smaller), and the gear device 1 as a whole can be made smaller. If the dimensions of the planetary gear 3 are constant, it is possible to increase the number (number) of the inner pins 4 to make the transmission of rotation smoother, or to make the inner pins 4 thicker to improve their strength, as compared to the first related art. Furthermore, the number of parts can be reduced by the number of inner rollers, which leads to a reduction in the cost of the gear device 1.

[0085] In addition, in the gear device 1 according to the present basic configuration, at least a portion of each of the inner pins 4 is disposed at the same position as the bearing member 6 in the axial direction of the bearing member 6. That is, as shown in FIG. 9, at least a portion of the inner pin 4 is disposed at the same position as the bearing member 6 in the direction parallel to the rotation axis Ax1. In other words, at least a portion of the inner pin 4 is located between both end faces of the bearing member 6 in the direction parallel to the rotation axis Ax1. In other words, at least a portion of each of the inner pins 4 is disposed inside the outer ring 62 of the bearing member 6. In this basic configuration, the end of the inner pin 4 on the output side of the rotation axis Ax1 is disposed at the same position as the bearing member 6 in the direction parallel to the rotation axis Ax1. In short, the end of the inner pin 4 on the output side of the rotation axis Ax1 is inserted into the retaining hole 611 formed in the inner ring 61 of the bearing member 6, so that at least the end is disposed at the same position as the bearing member 6 in the axial direction of the bearing member 6.

[0086] In this way, at least a part of each of the multiple inner pins 4 is disposed at the same position as the bearing member 6 in the axial direction of the bearing member 6, thereby making it possible to keep the dimension of the gear device 1 in the direction parallel to the rotation axis Ax1 small. In other words, compared to a configuration in which the bearing member 6 and the inner pins 4 are lined up (opposing) in the axial direction of the bearing member 6, the gear device 1 of this basic configuration can reduce the dimension of the gear device 1 in the direction parallel to the rotation axis Ax1, which can contribute to further miniaturization (thinning) of the gear device 1.

[0087] Here, the open surface of the retaining hole 611 on the output side of the rotating shaft Ax1 is closed by, for example, an output shaft integrated with the inner ring 61. As a result, movement of the inner pin 4 toward the output side of the rotating shaft Ax1 (the right side in FIG. 9 ) is regulated by the output shaft integrated with the inner ring 61.

[0088] Furthermore, in this basic configuration, the following configuration 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 made smooth by interposing a lubricant (lubricating oil) between the inner peripheral surface of the retaining hole 611 formed in the inner ring 61 and the inner pin 4. In particular, in this basic configuration, since there is a lubricant retaining space 17 between the inner ring 61 and the outer ring 62, into which a lubricant is injected, the lubricant in the lubricant retaining space 17 is used to smooth the rotation of the inner pin 4.

[0089] In this basic configuration, as shown in FIG. 9, the inner ring 61 has a plurality of retaining holes 611 into which the plurality of inner pins 4 are respectively inserted, and a plurality of connecting passages 64. The plurality of connecting passages 64 connect the lubricant retaining space 17 between the inner ring 61 and the outer ring 62 and the plurality of retaining holes 611. Specifically, the inner ring 61 has a connecting passage 64 extending in the radial direction from a portion of the inner circumferential surface of the retaining hole 611 that corresponds to the rolling element 63. The connecting passage 64 is a hole that penetrates between the bottom surface of a recess (groove) that accommodates the rolling element 63 on the surface of the inner ring 61 facing the outer ring 62 and the inner circumferential surface of the retaining hole 611. In other words, the opening surface of the connecting passage 64 on the lubricant retaining space 17 side is disposed at a position facing (opposing) the rolling element 63 of the bearing member 6. The lubricant retaining space 17 and the retaining hole 611 are spatially connected via such a connecting passage 64.

[0090] According to the above-mentioned configuration, the lubricant retaining space 17 and the retaining hole 611 are connected by the connecting passage 64, so that the lubricant in the lubricant retaining space 17 is supplied to the retaining hole 611 through the connecting passage 64. In other words, when the bearing member 6 operates and the rolling body 63 rotates, the rolling body 63 functions as a pump and can send the lubricant in the lubricant retaining space 17 to the retaining hole 611 via the connecting passage 64. In particular, since the opening surface of the connecting passage 64 on the lubricant retaining space 17 side is located in a position facing (opposing) the rolling body 63 of the bearing member 6, the rolling body 63 efficiently acts as a pump when the rolling body 63 rotates. As a result, the lubricant is interposed between the inner peripheral surface of the retaining hole 611 and the inner pin 4, and the rotation of the inner pin 4 relative to the inner ring 61 can be smoothed.

[0091] (3.3) Support Next, the configuration of the support body 8 of the gear device 1 according to this basic configuration will be described in more detail with reference to Fig. 10. Fig. 10 is a cross-sectional view taken along line B1-B1 in Fig. 3. However, in Fig. 10, hatching is omitted for parts other than the support body 8 even in the cross section. Also, in Fig. 10, only the internal gear 2 and the support body 8 are shown, and other parts (such as the inner pin 4) are omitted. Furthermore, in Fig. 10, the inner peripheral surface 221 of the gear body 22 is omitted from illustration.

[0092] First, as a premise, the support body 8 is a component that supports the multiple inner pins 4 as described above. That is, 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 by bundling the multiple inner pins 4. Specifically, the support body 8 has multiple support holes 82 into which the multiple inner pins 4 are respectively inserted. In this basic configuration, 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 in which each of the multiple inner pins 4 can rotate on its own axis. That is, each of the multiple inner pins 4 is held in a state in which it can rotate on its own axis with respect to both the inner ring 61 of the bearing member 6 and the support body 8.

[0093] In this way, the support body 8 positions the multiple inner pins 4 relative to the support body 8 in both the circumferential and radial directions. In other words, by inserting the inner pins 4 into the support holes 82 of the support body 8, movement of the inner pins 4 in all directions within a plane perpendicular to the rotation axis Ax1 is restricted. Therefore, the inner pins 4 are positioned by the support body 8 not only in the circumferential direction but also in the radial direction.

[0094] Here, the support 8 has an annular shape in which at least the outer peripheral surface 81 is a perfect circle in a plan view. The outer peripheral surface 81 of the support 8 is brought into contact with the multiple outer pins 23 of the internal gear 2, and thus the position of the support 8 is restricted by bringing the outer peripheral surface 81 into contact with the internal teeth 21. The multiple outer pins 23 constitute the internal teeth 21 of the internal gear 2, and therefore, in other words, the position of the support 8 is restricted by bringing the outer peripheral surface 81 into contact with the internal teeth 21. Here, the diameter of the outer peripheral surface 81 of the support 8 is the same as the diameter of a virtual circle (tooth tip circle) passing through the tips of the internal teeth 21 of the internal gear 2. Therefore, all of the multiple outer pins 23 are in contact with the outer peripheral surface 81 of the support 8. Therefore, in a state in which the position of the support 8 is restricted by the multiple outer pins 23, the center of the support 8 is restricted to overlap with the center (rotation axis Ax1) of the internal gear 2. This allows the support 8 to be centered, and as a result, the multiple inner pins 4 supported by the support 8 are also centered by the multiple outer pins 23.

[0095] Moreover, the inner pins 4 rotate (revolve) around the rotation axis Ax1 to transmit the rotation (rotation component) of the planetary gear 3 to the inner ring 61. Therefore, the support 8 supporting the inner pins 4 rotates around the rotation axis Ax1 together with the inner pins 4 and the inner ring 61. At this time, since the support 8 is centered by the outer pins 23, the support 8 rotates smoothly while the center of the support 8 is maintained on the rotation axis Ax1. Moreover, since the support 8 rotates with its outer peripheral surface 81 in contact with the outer pins 23, each of the outer pins 23 rotates (rotates) with the rotation of the support 8. Therefore, the support 8 forms a needle bearing together with the internal gear 2, and rotates smoothly.

[0096] That is, the outer peripheral surface 81 of the support 8 rotates together with the multiple inner pins 4 relative to the gear body 22 while in contact with the multiple outer pins 23. Therefore, if the gear body 22 of the internal gear 2 is considered to be the "outer ring" and the support 8 is considered to be the "inner ring", the multiple outer pins 23 interposed between them function as "rolling elements (rollers)". In this way, the support 8, together with the internal gear 2 (gear body 22 and multiple outer pins 23), constitutes a needle bearing, enabling smooth rotation.

[0097] Furthermore, since the support body 8 sandwiches the outer pins 23 between itself and the gear body 22, the support body 8 also functions as a "stopper" that suppresses movement of the outer pins 23 in a direction away from the inner peripheral surface 221 of the gear body 22. In other words, the outer pins 23 are sandwiched between the outer peripheral surface 81 of the support body 8 and the inner peripheral surface 221 of the gear body 22, and are suppressed from floating from the inner peripheral surface 221 of the gear body 22. In short, in this basic configuration, each of the outer pins 23 comes into contact with the outer peripheral surface 81 of the support body 8, thereby restricting movement in a direction away from the gear body 22.

[0098] In this basic configuration, as shown in FIG. 9, the support 8 is located on the opposite side of the bearing member 6 to the inner ring 61 across the planetary gear 3. That is, the support 8, the planetary gear 3, and the inner ring 61 are arranged in a direction parallel to the rotation axis Ax1. In this basic configuration, as an example, the support 8 is located on the input side of the rotation axis Ax1 as viewed from the planetary gear 3, and the inner ring 61 is located on the output side of the rotation axis Ax1 as viewed from the planetary gear 3. The support 8 supports both ends of the inner pin 4 in the longitudinal direction (direction parallel to the rotation axis Ax1) together with the inner ring 61, and the central portion of the inner pin 4 in the longitudinal direction is inserted into the loose fitting hole 32 of the planetary gear 3. In short, the gear device 1 according to this basic configuration includes an outer ring 62 and the inner ring 61 arranged inside the outer ring 62, and includes a bearing member 6 in which the inner ring 61 is supported so as to be rotatable relative to the outer ring 62. The gear body 22 is fixed to the outer ring 62. Here, the planetary gear 3 is located between the support 8 and the inner ring 61 in the axial direction of the support 8 .

[0099] According to this configuration, the support body 8 and the inner ring 61 support both longitudinal ends of the inner pin 4, so that the inner pin 4 is less likely to tilt. In particular, the inner pins 4 are more likely to receive bending forces (bending moment loads) with respect to the rotation axis Ax1. Furthermore, in this basic configuration, the support body 8 is sandwiched between the planetary gear 3 and the case 10 in a direction parallel to the rotation axis Ax1. As a result, the movement of the support body 8 toward the input side of the rotation axis Ax1 (the left side in FIG. 9) is restricted by the case 10. The movement of the inner pin 4 that penetrates the support hole 82 of the support body 8 and protrudes from the support body 8 toward the input side of the rotation axis Ax1 is also restricted by the case 10 toward the input side of the rotation axis Ax1 (the left side in FIG. 9).

[0100] In this basic configuration, the support 8 and the inner ring 61 are in contact with both ends of the outer pins 23. That is, as shown in FIG. 9, the support 8 is in contact with one end (the end on the input side of the rotation axis Ax1) of the outer pins 23 in the longitudinal direction (direction parallel to the rotation axis Ax1). The inner ring 61 is in contact with the other end (the end on the output side of the rotation axis Ax1) of the outer pins 23 in the longitudinal direction (direction parallel to the rotation axis Ax1). With this configuration, the support 8 and the inner ring 61 are centered at both ends of the outer pins 23 in the longitudinal direction, so that the inner pins 4 are less likely to tilt. In particular, the inner pins 4 are more likely to receive a bending force (bending moment load) with respect to the rotation axis Ax1 acting on them.

[0101] Further, the multiple outer pins 23 have a length equal to or greater than the thickness of the support body 8. In other words, in the direction parallel to the rotation axis Ax1, the support body 8 is contained within the range of the tooth trace of the internal teeth 21. As a result, the outer peripheral surface 81 of the support body 8 comes into contact with the multiple outer pins 23 over the entire length in the tooth trace direction of the internal teeth 21 (direction parallel to the rotation axis Ax1). Therefore, defects such as "uneven wear" in which the outer peripheral surface 81 of the support body 8 is partially worn away are unlikely to occur.

[0102] In addition, in this basic configuration, the outer peripheral surface 81 of the support 8 has a smaller surface roughness than one surface adjacent to the outer peripheral surface 81 of the support 8. In other words, the surface roughness of the outer peripheral surface 81 is smaller than both end surfaces of the support 8 in the axial direction (thickness direction). In this disclosure, "surface roughness" refers to the degree of roughness of the surface of an object, and the smaller the value, the smaller (fewer) the surface irregularities are, and the smoother the surface is. In this basic configuration, as an example, the surface roughness is the arithmetic mean roughness (Ra). For example, the outer peripheral surface 81 has a smaller surface roughness than the surfaces of the support 8 other than the outer peripheral surface 81, through processing such as polishing. In this configuration, the support 8 rotates more smoothly.

[0103] In addition, in this basic configuration, the hardness of the outer peripheral surface 81 of the support 8 is lower than that of the peripheral surfaces of the outer pins 23 and higher than that of the inner peripheral surface 221 of the gear body 22. In this disclosure, "hardness" means the degree of hardness of an object, and the hardness of a metal is expressed, for example, by the size of a depression made by pressing a steel ball with a certain pressure. Specifically, examples of metal hardness include Rockwell hardness (HRC), Brinell hardness (HB), Vickers hardness (HV), and Shore hardness (Hs). Means for increasing (hardening) the hardness of metal parts include, for example, alloying and heat treatment. In this basic configuration, as an example, the hardness of the outer peripheral surface 81 of the support 8 is increased by a process such as carburizing and quenching. In this configuration, wear powder and the like is not easily generated even when the support 8 rotates, and it is easy to maintain smooth rotation of the support 8 for a long period of time.

[0104] (4) Application Examples Next, application examples of the gear device 1 and the actuator 100 according to this basic configuration will be described.

[0105] The gear device 1 and the actuator 100 according to this basic configuration are applied to a robot such as a horizontal articulated robot, a so-called SCARA (Selective Compliance Assembly Robot Arm) type robot.

[0106] Furthermore, application examples of the gear device 1 and the actuator 100 according to this basic configuration are not limited to the horizontal articulated robot described above, but may be, for example, industrial robots other than horizontal articulated robots, or non-industrial robots. Examples of industrial robots other than horizontal articulated robots include vertical articulated robots and parallel link robots. Examples of non-industrial robots include domestic robots, nursing care robots, and medical robots.

[0107] (Embodiment 1) <Summary> An internal meshing planetary gear device 1A according to this embodiment (hereinafter also simply referred to as "gear device 1A") differs from the gear device 1 according to the basic configuration mainly in the structure around a bearing member 6A, as shown in Figures 11 to 14. Hereinafter, components similar to those in the basic configuration will be denoted by the same reference numerals and descriptions thereof will be omitted as appropriate.

[0108] Fig. 11 is a schematic cross-sectional view of the gear device 1A. Fig. 12 is a side view of the gear device 1A as seen from the output side of the rotation shaft Ax1 (the right side in Fig. 11), and Fig. 11 corresponds to the cross-sectional view taken along line C1-C1 in Fig. 12. Fig. 13 is a cross-sectional view taken along line A1-A1 in Fig. 11, and Fig. 14 is a cross-sectional view taken along line B1-B1 in Fig. 11 and a partially enlarged view thereof. However, in Figs. 13 and 14, hatching is omitted for parts other than the eccentric shaft 7, even in cross sections.

[0109] In this embodiment, the bearing member 6A has an outer ring 62A, an inner ring 61A arranged inside the outer ring 62A, and a plurality of rolling elements 63 arranged between the outer ring 62A and the inner ring 61A. The inner ring 61A is supported so as to be rotatable relatively to the outer ring 62A about the rotation axis Ax1. This point is the same as the basic configuration.

[0110] The gear device 1A according to this embodiment has a first main difference from the basic configuration in that the inner ring 61A of the bearing member 6A is not configured as a single part, but is configured to include two parts, a first inner ring 601 and a second inner ring 602. That is, as shown in Fig. 11, in the gear device 1A, the inner ring 61A includes the first inner ring 601 and the second inner ring 602 that face each other in a direction parallel to the rotation axis Ax1 and whose facing surfaces 601A, 602A (see Fig. 15) are in contact with each other.

[0111] A second major difference from the basic configuration of the gear device 1A according to this embodiment is that an outer ring 62A of the bearing member 6A is not configured separately from the gear body 22 of the internal gear 2, but is configured seamlessly and integrally with the gear body 22. In other words, as shown in Fig. 11, in the gear device 1A, the outer ring 62A is provided seamlessly continuous with the gear body 22 in a direction parallel to the rotation axis Ax1 (the tooth trace direction of the internal teeth 21).

[0112] In short, the gear device 1A according to this embodiment mainly differs from the basic configuration in that it newly adopts a feature regarding the inner ring 61A of the bearing member 6A and a feature regarding the outer ring 62A of the bearing member 6A. The feature regarding the inner ring 61A includes that the inner ring 61A has a first inner ring 601 and a second inner ring 602, and the feature regarding the outer ring 62A includes that the outer ring 62 is provided seamlessly continuous with the gear body 22.

[0113] <Other differences> In the gear device 1A according to this embodiment, in addition to the main differences described above (the improvements on the inner ring 61A and the improvements on the outer ring 62A), there are several other differences from the basic configuration, as described below.

[0114] As another difference, the gear device 1A according to this embodiment is used so that the rotation equivalent to the rotation component of the planetary gear 3 is taken out as the rotation of an output shaft integrated with an outer ring 62A of the bearing member 6A. That is, in the basic configuration, the relative rotation between the planetary gear 3 and the internal gear 2 is taken out as the rotation component of the planetary gear 3 from an inner ring 61 connected to the planetary gear 3 by a plurality of inner pins 4. In contrast, in this embodiment, the relative rotation between the planetary gear 3 and the internal gear 2 is taken out from an outer ring 62A integrated with a gear body 22 of the internal gear 2. In this embodiment, as an example, the gear device 1A is used in a state in which the inner ring 61A holding the plurality of inner pins 4 is fixed to a fixed member (such as a hub member 104 described later) and the outer ring 62A is fixed to a case 10 serving as a rotating member. That is, the planetary gear 3 is connected to a fixed member by the multiple inner pins 4, and the gear body 22 is fixed to a rotating member, so that the relative rotation between the planetary gear 3 and the internal gear 2 is taken from the internal gear 2 (gear body 22). In other words, in this embodiment, when the multiple inner pins 4 rotate relatively to the gear body 22, the rotational force of the gear body 22 is taken as an output.

[0115] The gear device 1A, in which the rotational force of the gear body 22 is thus extracted as an output, is used in a wheel device W1 (see FIG. 17), as an example. In this case, the rotating member (case 10) functions as the wheel body 102 (see FIG. 17), and the wheel body 102 can be rotated in accordance with the relative rotation between the internal gear 2 and the planetary gear 3. In this way, in this embodiment, by using the gear device 1A in the wheel device W1, the wheel body 102 can be driven so as to roll on the running surface by the rotational output generated when the multiple inner pins 4 rotate relatively to the gear body 22. In short, when the gear device 1A is used as the wheel device W1, a rotational force as an input is applied to the eccentric shaft 7, and a rotational force as an output is extracted from the rotating member as the wheel body 102. In other words, the gear device 1A operates with the rotation of the eccentric shaft 7 as the input rotation and the rotation of the rotating member to which the gear body 22 is fixed as the output rotation. As a result, in the gear device 1A, an output rotation that is reduced at a relatively high reduction ratio with respect to the input rotation is obtained as the rotation of the wheel main body 102.

[0116] A second other difference is that the gear device 1A according to 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 disposed to face each other in a direction parallel to the rotation axis Ax1. In other words, the planetary gears 3 include the first planetary gear 301 and the second planetary gear 302 that face each other in a direction parallel to the rotation axis Ax1.

[0117] These two planetary gears 3 (first planetary gear 301 and second planetary gear 302) are arranged with a phase difference of 180 degrees around the rotation axis Ax1. In the example of FIG. 11, the center C1 of the first planetary gear 301 located on the input side (left side of FIG. 11) of the rotation axis Ax1 among the first planetary gear 301 and the second planetary gear 302 is shifted (biased) upward in the figure with respect to the rotation axis Ax1. On the other hand, the center C2 of the second planetary gear 302 located on the output side (right side of FIG. 11) of the rotation axis Ax1 is shifted (biased) downward in the figure with respect to the rotation axis Ax1. In this way, the multiple planetary gears 3 are evenly arranged in the circumferential direction centered on the rotation axis Ax1, so that it is possible to balance the weight between the multiple planetary gears 3. In the gear device 1A according to this embodiment, the weight balance is achieved between the multiple planetary gears 3 in this way, so that the gap 75 (see FIG. 3) of the eccentric shaft 7 is omitted.

[0118] More specifically, the eccentric shaft 7 has two eccentric parts 72 with respect to one shaft center part 71. The centers (central axes) of these two eccentric parts 72 coincide with centers C1 and C2 that are offset from the rotation axis Ax1. The first planetary gear 301 and the second planetary gear 302 have the same shape. The opening 33 of the first planetary gear 301 houses the eccentric body bearing 5 attached to the eccentric part 72 centered on the center C1. The opening 33 of the second planetary gear 302 houses the eccentric body bearing 5 attached to the eccentric part 72 centered on the center C2. Here, the distance ΔL1 between the rotation axis Ax1 and the center C1 is the amount of eccentricity of the first planetary gear 301 with respect to the rotation axis Ax1, and the distance ΔL2 between the rotation axis Ax1 and the center C2 is the amount of eccentricity of the second planetary gear 302 with respect to the rotation axis Ax1. In this embodiment, the eccentricity ΔL1 and the eccentricity ΔL2 are oriented in opposite directions as viewed from the rotation axis Ax1, but have the same absolute value. According to the above-described configuration, the shaft center portion 71 rotates (spins) about the rotation axis Ax1, so that the first planetary gear 301 and the second planetary gear 302 rotate (perform eccentric motion) around the rotation axis Ax1 with a phase difference of 180 degrees around the rotation axis Ax1.

[0119] As another third difference, in this embodiment, as shown in Figs. 13 and 14, the eccentric bearing 5 is a roller bearing instead of the deep groove ball bearing described in the basic configuration. That is, in the gear device 1A according to this embodiment, the eccentric bearing 5 uses a cylindrical roller as the rolling body 53. Furthermore, in this embodiment, the eccentric inner ring 51 (see Fig. 3) and the eccentric outer ring 52 (see Fig. 3) are omitted. Therefore, the inner peripheral surface of the planetary gear 3 (opening 33) becomes the rolling surface of the multiple rolling bodies 53 instead of the eccentric outer ring 52, and the outer peripheral surface of the eccentric part 72 becomes the rolling surface of the multiple rolling bodies 53 instead of the eccentric inner ring 51. In this embodiment, the eccentric bearing 5 has a retainer 54, and the multiple rolling bodies 53 are held by the retainer 54 in a state in which they can rotate about their own axes. The cage 54 holds the multiple rolling elements 53 at equal pitch in the circumferential direction of the eccentric portion 72. Furthermore, the cage 54 is not fixed to the planetary gear 3 and the eccentric shaft 7, and is rotatable relatively to each of the planetary gear 3 and the eccentric shaft 7. As a result, the multiple rolling elements 53 held by the cage 54 move in the circumferential direction of the eccentric portion 72 as the cage 54 rotates.

[0120] As a fourth difference, in this embodiment, the case 10 is seamlessly integrated with the gear body 22 of the internal gear 2 and the outer ring 62A of the bearing member 6A. That is, in the basic configuration, the gear body 22 of the internal gear 2 is used in a state where it is fixed to the case 10 together with the outer ring 62 of the bearing member 6. In contrast, in this embodiment, due to an innovation regarding the outer ring 62A, the outer ring 62A, which is provided seamlessly and continuously with the gear body 22 in a direction parallel to the rotation axis Ax1, is also provided seamlessly and continuously with the case 10, which is a rotating member.

[0121] More specifically, the case 10 is cylindrical and constitutes the outer shell of the gear device 1A. In this embodiment, the case 10, which is a rotating member, functions as, for example, the wheel body 102, so that the central axis of the cylindrical case 10 is configured to coincide with the rotation axis Ax1. In other words, at least the outer peripheral surface of the case 10 is a perfect circle centered on the rotation axis Ax1 in a plan view (as seen from one side in the direction of the rotation axis Ax1). As shown in FIG. 11, the case 10 has a body 18 and a cap 19. The body 18 is a cylindrical part with both end faces in the direction of the rotation axis Ax1 open. The cap 19 is a disk-shaped part that is attached to the end face of the body 18 on the input side of the rotation axis Ax1 (the left side in FIG. 11) and closes the open face of the body 18 on the input side of the rotation axis Ax1. In this embodiment, the gear body 22 of the internal gear 2 and the outer ring 62A of the bearing member 6A are seamlessly integrated with the body 18 of the case 10. As a result, the gear body 22 and the outer ring 62A are treated as one component (body portion 18). Therefore, the inner circumferential surface of the body portion 18 includes the inner circumferential surface 221 (see FIG. 14) of the gear body 22 and the inner circumferential surface 620 (see FIG. 13) of the outer ring 62A.

[0122] In addition to the above, the present embodiment and the basic configuration also differ as appropriate in terms of, for example, the number of teeth of the internal gear 2 and the planetary gear 3, the reduction ratio, the number of loose fit holes 32 and inner pins 4, and the specific shape and dimensions of each part. For example, while the basic configuration provides 18 loose fit holes 32 and inner pins 4, the present embodiment provides 12 of each, as an example.

[0123] <Ingenuity regarding internal relationships> Next, the innovation regarding the inner ring 61A of the bearing member 6A in the gear device 1A according to this embodiment will be described in detail with reference to FIGS.

[0124] In this embodiment, as described above, the inner ring 61A of the bearing member 6A is configured to include two parts, the first inner ring 601 and the second inner ring 602, which face each other in a direction parallel to the rotation axis Ax1. The first inner ring 601 and the second inner ring 602 are assembled in a state in which the facing surfaces 601A, 602A are in contact with each other. In other words, the inner ring 61A is divided into two parts, the first inner ring 601 and the second inner ring 602, which are aligned in a direction parallel to the rotation axis Ax1.

[0125] The first inner ring 601 and the second inner ring 602 are both annular components. The first inner ring 601 and the second inner ring 602 both have an annular shape that is a perfect circle in a plan view. The first inner ring 601 and the second inner ring 602 have the same outer diameter φ1 (see FIG. 15 ) and approximately the same inner diameter. In the present embodiment, as an example, the dimension in a direction parallel to the rotation axis Ax1 is larger for the second inner ring 602 than for the first inner ring 601, but this dimensional relationship is not intended to be limiting.

[0126] The first inner ring 601 and the second inner ring 602 are both one size smaller than the outer ring 62A and are disposed inside the outer ring 62A. Here, since the inner diameter φ3 (see FIG. 15) of the outer ring 62A is larger than the outer diameter φ1 of the first inner ring 601 and the second inner ring 602, a gap is generated between the inner peripheral surface 620 of the outer ring 62A and the outer peripheral surfaces of the first inner ring 601 and the second inner ring 602. Furthermore, as will be described in detail later, the outer diameter φ1 of the first inner ring 601 and the second inner ring 602 is even smaller than the diameter φ2 (see FIG. 15) of an imaginary circle VC1 (see FIG. 14) passing through the bottoms of the multiple pin retaining grooves 223 (see FIG. 14) in the inner peripheral surface 221 of the gear body 22.

[0127] Here, the first inner ring 601 and the second inner ring 602 are arranged such that the first inner ring 601 is on the planetary gear 3 side and the second inner ring 602 is on the opposite side to the planetary gear 3 in the direction parallel to the rotation axis Ax1. In other words, the first inner ring 601 and the second inner ring 602 are arranged such that the first inner ring 601 is on the input side of the rotation axis Ax1 (left side in FIG. 11) and the second inner ring 602 is on the output side of the rotation axis Ax1 (right side in FIG. 11). Therefore, the facing surface 601A of the first inner ring 601 facing the second inner ring 602 is made of a surface of the first inner ring 601 facing the output side of the rotation axis Ax1 (right side in FIG. 11). Conversely, the facing surface 602A of the second inner ring 602 facing the first inner ring 601 is made of a surface of the second inner ring 602 facing the input side of the rotation axis Ax1 (left side in FIG. 11). The first inner ring 601 and the second inner ring 602 are combined with each other so that their opposing surfaces 601A, 602A are in contact with each other to form the inner ring 61A.

[0128] The first inner ring 601 and the second inner ring 602, in the combined state as described above, are joined by a plurality of positioning pins 65 and a plurality of bolts 66, as shown in Fig. 12. The plurality of positioning pins 65 are press-fitted into a plurality of holes that penetrate the inner ring 61A in a direction parallel to the rotation axis Ax1 from the first inner ring 601 to the second inner ring 602. In addition, the plurality of bolts 66 are fastened to the first inner ring 601 through the second inner ring 602. Therefore, the first inner ring 601 and the second inner ring 602 are joined by the plurality of bolts 66 in a state in which their relative positions in a plane perpendicular to the rotation axis Ax1 are positioned by the plurality of positioning pins 65.

[0129] Here, in the bearing member 6A, the multiple rolling elements 63 are located on the dividing surface of the first inner ring 601 and the second inner ring 602 in the inner ring 61A, as shown in FIG. 15. In this embodiment, the opposing surface 601A of the first inner ring 601 with the second inner ring 602 is the dividing surface of the first inner ring 601 and the second inner ring 602, so the multiple rolling elements 63 are located on a plane including the opposing surface 601A of the first inner ring 601 with the second inner ring 602. In this embodiment, the bearing member 6A is a cross roller bearing that receives a radial load, a thrust load (direction along the rotation axis Ax1), and a bending force (bending moment load) against the rotation axis Ax1. Therefore, the multiple rolling elements 63 of the bearing member 6 are each made of a cylindrical roller inclined at 45 degrees with respect to a plane perpendicular to the rotation axis Ax1. Such a plurality of rolling elements 63 are positioned on the same plane as an opposing surface 601A of the first inner ring 601 facing the second inner ring 602.

[0130] Particularly in this embodiment, the centers of the plurality of rolling elements 63 in the direction parallel to the rotation axis Ax1 are located on the same plane as the opposing surface 601A of the first inner ring 601 with the second inner ring 602. In other words, the inner ring 61A is divided into the first inner ring 601 and the second inner ring 602 with a plane including the centers of the plurality of rolling elements 63 in the direction parallel to the rotation axis Ax1 as a dividing plane. With this configuration, when assembling the bearing member 6A, the plurality of rolling elements 63 set in the outer ring 62A are sandwiched between the first inner ring 601 and the second inner ring 602 from both sides in the direction parallel to the rotation axis Ax1, making it possible to assemble the bearing member 6A relatively easily.

[0131] In this embodiment, the oil seal 15 closes the gap between the second inner ring 602 and the eccentric shaft 7 (shaft center portion 71). Similarly, the oil seal 16 closes the gap between the second inner ring 602 and the outer ring 62. The space sealed by the multiple oil seals 14, 15, and 16 forms a lubricant retaining space 17 (see FIG. 11) similarly to the basic configuration.

[0132] In this way, since the inner ring 61A is divided into two parts, the first inner ring 601 and the second inner ring 602, a gap may be generated between the first inner ring 601 and the second inner ring 602, even if it is small. The generation of such a gap makes it easier for the lubricant to circulate through the gap in the lubricant retaining space 17. In particular, if the gap between the first inner ring 601 and the second inner ring 602 is small, the lubricant in the lubricant retaining space 17 is expected to spread through the gap by, for example, capillary action. Therefore, compared to a case in which the inner ring 61A is not divided into two parts, the first inner ring 601 and the second inner ring 602, for example, the lubricant is more likely to spread throughout the lubricant retaining space 17 even when the gear device 1A is used for a long period of time, and problems such as a decrease in transmission efficiency in the gear device 1A are less likely to occur.

[0133] Furthermore, by dividing the inner ring 61A into two parts, the first inner ring 601 and the second inner ring 602, assembly of the bearing member 6A can be facilitated without significantly complicating the processing of the inner ring 61A. And, by not complicating the processing of the inner ring 61A, the size of the inner ring 61 can be kept relatively small, making it possible to realize a bearing member 6A that is relatively compact as a cross roller bearing.

[0134] In this embodiment, similarly to the basic configuration, a plurality of inner pins 4 connect the planetary gear 3 and the inner ring 61A of the bearing member 6A. Specifically, one end of the inner pin 4 in the longitudinal direction (the end on the input side of the rotation axis Ax1) is inserted into the loose fitting hole 32 of the planetary gear 3 (the first planetary gear 301 and the second planetary gear 302), and the other end of the inner pin 4 in the longitudinal direction (the end on the output side of the rotation axis Ax1) is inserted into the retaining hole 611 of the inner ring 61A.

[0135] Furthermore, because the diameter of the inner pin 4 is slightly larger than the retaining hole 611, when the inner pin 4 is inserted into the retaining hole 611 of the bearing member 6A, the inner pin 4 is prohibited from revolving within the retaining hole 611, but is able to rotate within the retaining hole 611. In other words, even when the inner pin 4 is inserted into the retaining hole 611, it is not press-fitted into the retaining hole 611, and is therefore able to rotate within the retaining hole 611. In this way, in the gear device 1A according to this embodiment, each of the multiple inner pins 4 is held by the inner ring 61A in a rotatable state, and therefore the inner pin 4 itself is able to rotate when the inner pin 4 revolves within the loose-fitting hole 32.

[0136] Here, in this embodiment, unlike the basic configuration, each of the multiple retaining holes 611 is configured to penetrate only the first inner ring 601 of the inner ring 61A, rather than penetrating the entire inner ring 61A. That is, the first inner ring 601 has multiple retaining holes 611 through which the multiple inner pins 4 respectively penetrate in a direction parallel to the rotation axis Ax1. The inner pins 4 are retained by the inner ring 61A by inserting the other end in the longitudinal direction (the end on the output side of the rotation axis Ax1) into the retaining hole 611.

[0137] In this embodiment, since the inner pin 4 is not inserted into the second inner ring 602, the second inner ring 602 is not provided with a retaining hole 611. Therefore, the end face of each of the multiple inner pins 4 is abutted against the opposing surface 602A of the second inner ring 602 that faces the first inner ring 601. In other words, the end face of the inner pin 4 on the opposite side to the planetary gear 3 in the longitudinal direction (the output side of the rotation axis Ax1) is abutted against the surface (opposing surface 602A) of the second inner ring 602. The end face of the inner pin 4 in the longitudinal direction may be in light contact with the opposing surface 602A of the second inner ring 602 to an extent that the rotation of the inner pin 4 is not hindered, or may be separated from the opposing surface 602A of the second inner ring 602. Therefore, the movement of the inner pin 4 toward the output side of the rotation axis Ax1 is restricted by the second inner ring 602, and the lubricant in the lubricant retaining space 17 is suppressed from leaking through the retaining hole 611.

[0138] In addition, since the diameter of the inner pin 4 is slightly larger than the retaining hole 611, a gap is formed between the inner peripheral surface of each of the plurality of retaining holes 611 in the first inner ring 601 and the outer peripheral surface of each of the plurality of inner pins 4. In other words, the retaining hole 611 is a hole into which the inner pin 4 is loosely fitted, and the inner pin 4 is inserted into the retaining hole 611 with a spatial margin (gap) secured between the inner peripheral surface of the retaining hole 611. However, since it is sufficient that the inner pin 4 can rotate within the retaining hole 611, the gap between the inner peripheral surface of the retaining hole 611 and the inner pin 4 is smaller than the gap between the inner peripheral surface 321 of the loose fitting hole 32 and the inner pin 4. Furthermore, it is not essential that a gap as a cavity is secured between the inner peripheral surface of the retaining hole 611 and the inner pin 4, and for example, this gap may be filled with a fluid such as a liquid. Specifically, the gap between the inner peripheral surface of the retaining hole 611 and the inner pin 4 is filled with a lubricant. Therefore, the rotation of the inner pin 4 within the holding hole 611 becomes smoother due to the lubricant.

[0139] Furthermore, the gear device 1A according to this embodiment further includes a lubricant circulation path RL1 as shown in FIG. 16. In FIG. 16, the flow of the lubricant through the circulation path RL1 is diagrammatically shown by dashed arrows. The circulation path RL1 is a path (circulation path) that circulates the lubricant through at least the gap between the first inner ring 601 and the second inner ring 602, the space that houses each of the plurality of rolling elements 63, and each of the plurality of retaining holes 611. That is, the circulation path RL1 includes the gap between the first inner ring 601 and the second inner ring 602, the space that houses the rolling elements 63, and the retaining hole 611, and is formed in a loop shape as shown in FIG. 16. This makes it easier for the lubricant injected into the space that houses the rolling elements 63 to circulate again along the circulation path RL1, through the gap between the first inner ring 601 and the second inner ring 602, and the retaining hole 611 (the gap between the inner circumferential surface of the retaining hole 611 and the inner pin 4), to the space that houses the rolling elements 63. However, the direction in which the lubricant moves through the circulation path RL1 is not limited to the direction shown by the arrow in FIG. 16, and may be the opposite direction.

[0140] Moreover, the gear device 1A according to this embodiment satisfies the following conditions regarding the surface hardness of each component.

[0141] That is, the same degree of surface hardness is adopted for each of the multiple inner pins 4 and the first inner ring 601. Specifically, the difference between the surface hardness of each of the multiple inner pins 4 and the surface hardness of the first inner ring 601 is HRC3 or less. That is, the surface hardness of the inner pins 4 is set within a range of ±3 in Rockwell hardness (HRC) with the surface hardness of the first inner ring 601 as the reference. Here, the difference between the surface hardness of the inner pins 4 and the surface hardness of the first inner ring 601 is preferably HRC2 or less, and more preferably HRC1 or less. Here, the "surface hardness of the first inner ring 601" refers to the hardness of at least the inner circumferential surface of the retaining hole 611 in the first inner ring 601. Since the first inner ring 601 holds the inner pin 4 in a rotatable state within the retaining hole 611, by making the surface hardness of the inner pin 4 and the first inner ring 601 approximately the same (difference of HRC3 or less) as in this embodiment, it is expected to have the effect of suppressing wear of the inner pin 4 and the first inner ring 601. As a result, wear powder and the like is less likely to be generated even when the inner pin 4 rotates within the retaining hole 611, making it easier to maintain smooth rotation of the inner pin 4 over a long period of time.

[0142] Furthermore, the surface hardness of each of the multiple inner pins 4 is about HRC60. More strictly, the surface hardness of each of the multiple inner pins 4 is within the range of HRC60±3. In this embodiment, the surface hardness of the inner pin 4 and the first inner ring 601 are approximately the same (the difference is HRC3 or less), so the surface hardness of the first inner ring 601 is within the range of HRC60±6. Here, the surface hardness of the inner pin 4 is preferably within the range of HRC60±2, and more preferably within the range of HRC60±1. As a result, wear powder and the like is unlikely to be generated even when the inner pin 4 rotates within the retaining hole 611, and the smooth rotation of the inner pin 4 can be easily maintained for a long period of time.

[0143] In this embodiment, the second inner ring 602 has a surface hardness similar to that of the first inner ring 601 (and the inner pin 4). Specifically, the difference between the surface hardness of the second inner ring 602 and the surface hardness of the first inner ring 601 is HRC3 or less. Means for increasing (hardening) the hardness of a metal component include, for example, alloying or heat treatment.

[0144] <Ingenuity regarding the outer ring> Next, the innovation regarding the outer ring 62A of the bearing member 6A in the gear device 1A according to this embodiment will be described in detail with reference to FIGS.

[0145] In this embodiment, as described above, the outer ring 62A of the bearing member 6A is provided seamlessly and continuously with the gear body 22 in a direction parallel to the rotation axis Ax1 (the tooth trace direction of the internal teeth 21). In this disclosure, "seamless" refers to a structure in which a plurality of parts (parts) are connected seamlessly, and refers to a state in which these plurality of parts (parts) cannot be separated without destruction. In other words, in this embodiment, the outer ring 62A and the gear body 22, which are prepared as separate parts, are not joined by, for example, a fastener (bolt, etc.) or an adhesive, but the outer ring 62A and the gear body 22 are integrated so as to be continuous without any seams.

[0146] Specifically, the outer ring 62A and the gear body 22 are formed integrally by, for example, cutting a single base material made of a metal lump, thereby realizing the seamlessly continuous outer ring 62A and the gear body 22. Alternatively, in the case of casting or the like, the outer ring 62A and the gear body 22 are formed integrally by pouring a single base material made of molten metal into a molding die, thereby realizing the seamlessly continuous outer ring 62A and the gear body 22. In this way, in the gear device 1A according to this embodiment, the outer ring 62A and the gear body 22 are formed integrally by, for example, processing a single base material, thereby realizing the outer ring 62A that is provided seamlessly continuous with the gear body 22 in a direction parallel to the rotation axis Ax1. In other words, the manufacturing method of the gear device 1A includes a process of forming the outer ring 62A and the gear body 22 integrally by processing a single base material.

[0147] Thus, in the gear device 1A according to this embodiment, the outer ring 62A is provided seamlessly in continuity with the gear body 22 in a direction parallel to the rotation axis Ax1, which makes it easier to improve the accuracy of centering between the internal gear 2 and the bearing member 6A. In other words, the center of the gear body 22 of the internal gear 2 and the center of the outer ring 62A of the bearing member 6A are more likely to be accurately maintained on the rotation axis Ax1. As a result, the gear device 1A has the advantage that problems such as vibration generation and reduced transmission efficiency due to poor centering are less likely to occur.

[0148] Both the gear body 22 and the outer ring 62A have an annular shape that is a perfect circle in a plan view. In this embodiment in particular, the gear body 22 and the outer ring 62A are seamlessly integrated with the body portion 18 of the case 10. In other words, a part of the body portion 18 of the case 10 functions as the gear body 22 and the outer ring 62A. Therefore, as shown in Fig. 15, the gear body 22 and the outer ring 62A have the same outer diameter. On the other hand, the gear body 22 and the outer ring 62A have different inner diameters.

[0149] Specifically, as shown in FIG. 14, a plurality of grooves are formed on the inner peripheral surface 221 of the gear body 22 over the entire circumferential direction. These grooves are a plurality of pin holding grooves 223 as a holding structure for a plurality of outer pins 23. In other words, the holding structure for the plurality of outer pins 23 includes a plurality of pin holding grooves 223 formed on the inner peripheral surface 221 of the gear body 22. All of the plurality of pin holding grooves 223 have the same shape and are provided at equal pitches. All of the plurality of pin holding grooves 223 are parallel to the rotation axis Ax1 and are formed over the entire width of the gear body 22. However, in this embodiment, since the gear body 22 is a part of the trunk 18 as described above, the plurality of pin holding grooves 223 are formed only in the portion of the trunk 18 corresponding to the gear body 22 (see FIG. 11). The plurality of outer pins 23 are combined with the gear body 22 (trunk 18) so as to fit into the plurality of pin holding grooves 223. Each of the multiple outer pins 23 is held in the pin holding groove 223 in a rotatable state, and the pin holding groove 223 restricts movement in the circumferential direction of the gear body 22.

[0150] By forming such a plurality of pin retaining grooves 223, the inner diameter of the gear body 22 is maximum at the bottom of the pin retaining groove 223 and is minimum outside the pin retaining groove 223. In this embodiment, the diameter φ2 of a virtual circle VC1 passing through the bottom of the plurality of pin retaining grooves 223, that is, the maximum value of the inner diameter of the gear body 22, is defined as the inner diameter of the gear body 22. As shown in FIG. 15, the inner diameter (φ2) of the gear body 22 is different from the inner diameter φ3 of the outer ring 62A of the bearing member 6A. In other words, the inner diameter φ3 of the outer ring 62A is different from the diameter φ2 of the virtual circle VC1 passing through the bottom of the plurality of pin retaining grooves 223 in which the plurality of outer pins 23 are retained on the inner circumferential surface 221 of the gear body 22. As a result, while the gear body 22 and the outer ring 62A are seamlessly connected to each other, the difference in the inner diameters of the two makes it easier to clearly separate the functions of the gear body 22 and the outer ring 62A.

[0151] Furthermore, in this embodiment, as shown in FIG. 15, the inner diameter φ3 of the outer ring 62A is larger than the diameter φ2 of the imaginary circle VC1 (φ3>φ2). In other words, the diameter φ2 of the imaginary circle VC1, which is the inner diameter (maximum value) of the gear body 22, is smaller than the inner diameter φ3 of the outer ring 62A. As a result, on the inner circumferential surface of the trunk portion 18, a step of height D1 is generated between the bottoms of the multiple pin holding grooves 223 on the inner circumferential surface 221 of the gear body 22 and the outer ring 62A, as shown in FIG. 16. The height D1 of the step is preferably, for example, 1 / 12 (φ10×1 / 12) or more and 2 / 10 (φ10×0.2) or less of the diameter φ10 of the outer pin 23 (see FIG. 14). As an example, when the diameter φ10 of the outer pin 23 is about 2.5 mm, the height D1 of the step is preferably 0.2 mm or more and 0.5 mm or less. This step makes it possible to avoid interference between the outer pin 23 held in the pin holding groove 223 and the inner peripheral surface 620 of the outer ring 62A.

[0152] In this embodiment, the outer diameter φ1 of the inner ring 61A (first inner ring 601 and second inner ring 602) is smaller than the diameter φ2 of the imaginary circle VC1. In other words, the diameter φ2 of the imaginary circle VC1 is larger than the outer diameter φ1 of the inner ring 61A, and the inner diameter φ3 of the outer ring 62A is larger than the diameter φ2 of the imaginary circle VC1. In other words, the diameter φ2 of the imaginary circle VC1 is a value between the outer diameter φ1 of the inner ring 61A and the inner diameter φ3 of the outer ring 62A (φ1<φ2<φ3).

[0153] As shown in FIG. 16, a retaining recess 67 is disposed between an inner peripheral surface 620 of the outer ring 62A and an inner peripheral surface 221 of the gear body 22. The retaining recess 67 is a groove provided over the entire circumference of the outer ring 62A in the circumferential direction. The retaining recess 67 is formed to a size and shape capable of retaining a lubricant by surface tension, for example. In other words, the retaining recess 67 functions as an "oil reservoir" for retaining the lubricant (lubricating oil). In this embodiment, the gear body 22 and the outer ring 62A are disposed such that the gear body 22 is on the input side (left side in FIG. 16) of the rotation axis Ax1, and the outer ring 62A is on the output side (right side in FIG. 16) of the rotation axis Ax1. Therefore, the inner circumferential surface 221 of the gear body 22, the retaining recess 67, and the inner circumferential surface 620 of the outer ring 62A are arranged in the following order from the input side of the rotation axis Ax1: the inner circumferential surface 221 of the gear body 22, the retaining recess 67, and the inner circumferential surface 620 of the outer ring 62A.

[0154] In the present embodiment, as an example, as shown in FIG. 16, the holding recess 67 has a rectangular cross-sectional shape perpendicular to the circumferential direction of the outer ring 62A. The depth D2 (from the inner peripheral surface 620 of the outer ring 62A) of the holding recess 67 and the width D3 of the holding recess 67 are both greater than the height D1 of the step. The depth D2 and the width D3 of the holding recess 67 are preferably equal to or greater than one-tenth (φ10×1 / 10) and equal to or less than two times (φ10×2) the diameter φ10 of the outer pin 23. As an example, when the diameter φ10 of the outer pin 23 is about 2.5 mm, the depth D2 and the width D3 of the holding recess 67 are preferably equal to or greater than 0.25 mm and equal to or less than 5.0 mm. In the example of FIG. 16, the depth D2 of the holding recess 67 is greater than the width D3 of the holding recess 67, but this is not limiting, and the depth D2 of the holding recess 67 may be equal to or less than the width D3. Furthermore, the cross-sectional shape of the holding recess 67 is not limited to a rectangular shape, but may be a semicircular shape, a triangular shape, or another polygonal shape.

[0155] Here, the gear device 1A according to this embodiment further includes a lubricant path that connects the retaining recess 67 to each of the multiple inner pins 4, each of the multiple outer pins 23, and at least one of the multiple rolling elements 63. That is, the retaining recess 67 as an "oil reservoir" is connected to each of the multiple inner pins 4, each of the multiple outer pins 23, and at least one of the multiple rolling elements 63 through the lubricant path. As a result, the lubricant held in the retaining recess 67 is supplied to each of the multiple inner pins 4, each of the multiple outer pins 23, and at least one of the multiple rolling elements 63, smoothing the movement of at least one of the inner pins 4, the outer pins 23, and the rolling elements 63. In this embodiment, the retaining recess 67 is located on the lubricant circulation path RL1, and the lubricant in the retaining recess 67 is supplied to at least one of the inner pins 4, the outer pins 23, and the rolling elements 63 through a part of the circulation path RL1 as a "lubricant" path. In particular, in this embodiment, as shown in Figure 16, the inner pin 4, outer pin 23 and rolling body 63 are all located on the circulation path RL1, so that the lubricant held in the retaining recess 67 can be supplied to all of the inner pin 4, outer pin 23 and rolling body 63.

[0156] In particular, in this embodiment, the rolling element 63 is located on the circulation path RL1. Therefore, when the bearing member 6A operates and the rolling element 63 rotates, the rolling element 63 functions as a pump, and the lubricant in the lubricant retention space 17 can be actively circulated via the circulation path RL1. In particular, since the dividing surface between the first inner ring 601 and the second inner ring 602 is located facing (opposing) the rolling element 63, the rolling element 63 efficiently acts as a pump when the rolling element 63 rotates. As a result, the lubricant in the lubricant retention space 17 is easily circulated, and even when the gear device 1A is used for a long period of time, the lubricant is easily distributed throughout the lubricant retention space 17, and problems such as a decrease in transmission efficiency in the gear device 1A are less likely to occur.

[0157] <Application Examples> As shown in FIG. 17, the gear device 1A according to this embodiment constitutes the wheel device W1 together with the wheel body 102. In other words, the wheel device W1 according to this embodiment includes the gear device 1A and the wheel body 102. The wheel body 102 rolls on the running surface by the rotation output generated when the inner pins 4 rotate relatively to the gear body 22. In this embodiment, the body 18 and the cap 19 as "rotating members" of the case 10 constituting the outer shell of the gear device 1 constitute the wheel body 102. That is, in the wheel device W1 according to this embodiment, the gear device 1A operates with the rotation of the eccentric shaft 7 as the input rotation and the rotation of the rotating member (body 18, etc.) to which the gear body 22 is fixed as the output rotation, so that the wheel body 102 rotates and rolls on the running surface. Here, a tire 103 made of rubber, for example, is attached to the outer peripheral surface of the body 18, which is the contact surface of the wheel body 102 with the running surface, i.e., the ground contact surface.

[0158] The wheel device W1 configured in this manner is used with the inner ring 61A fixed to the hub member 104, which is a fixed member. As a result, when the eccentric shaft 7 rotates, the wheel body 102 rotates due to the relative rotation of the rotating member (wheel body 102) with respect to the fixed member (hub member 104). In this embodiment, as an example, the wheel device W1 has the inner ring 61A (first inner ring 601 and second inner ring 602) fixed to the hub member 104 using a plurality of bolts 66. At this time, it is preferably the second inner ring 602 of the inner ring 61A that is fixed to the hub member 104 or the like.

[0159] Here, when the gear device 1A is used in the wheel device W1, the gear device 1A is basically used with the rotation axis Ax1 in a position along a horizontal plane. Therefore, the lubricant circulating through the circulation path RL1 (see FIG. 16) is easily supplied to the periphery of the eccentric shaft 7, such as the eccentric bearing 5 (the rolling body 53) and the second bearing 92. In other words, a part of the lubricant circulating through the circulation path RL1 is easily supplied to the eccentric bearing 5 and the second bearing 92 through the gap between the planetary gear 3 (the second planetary gear 302) and the first inner ring 601 by gravity. As a result, even if the lubricant is blown outward by centrifugal force when the eccentric shaft 7 rotates at high speed, the lubricant can be supplied to the periphery of the eccentric shaft 7 through the circulation path RL1, making it easier to maintain smooth rotation of the eccentric shaft 7.

[0160] The wheel device W1 using the gear device 1A is applied to a vehicle such as an automated guided vehicle (AGV). That is, the wheel device W1 is mounted on a hub member 104 provided on the vehicle body, and the wheel main body 102 rotates and rolls on the running surface, so that the vehicle runs on a flat running surface such as a floor surface. As an example, a plurality of gear devices 1A (for example, four) are mounted on the vehicle body, and the eccentric shaft 7 of each gear device 1A is driven by an individual driving source, thereby adopting an "in-wheel motor" layout. As a result, the driving source rotates the eccentric shaft 7 of the wheel device W1 about the rotation axis Ax1, thereby oscillating the planetary gear 3. As a result, the rotation (input rotation) generated by the driving source is decelerated at a relatively high reduction ratio in the gear device 1A, and the wheel main body 102 is rotated with a relatively high torque.

[0161] In this embodiment, the outer peripheral surface 680 of the outer ring 62A constitutes a pressure receiving surface that receives a larger stress than the outer peripheral surface 224 of the gear body 22. In other words, a larger stress acts on the outer peripheral surface 680 (pressure receiving surface) of the outer ring 62A from the outside than the outer peripheral surface 224 of the gear body 22. In particular, when the gear device 1A is used in a wheel device W1 or the like, it is preferable that the outer peripheral surface 680 of the outer ring 62A is configured to receive a larger stress than the outer peripheral surface 224 of the gear body 22. The gear body 22 has a relatively large gap between it and the planetary gear 3 so that the planetary gear 3 can revolve (swing) on ​​the inside. In contrast, the outer ring 62A has a relatively small gap between it and the inner ring 61A as long as the inner ring 61A can rotate on its inside. In other words, the outer ring 62A has a structure closer to a solid structure with a filled inside compared to the gear body 22, and therefore has high rigidity against external forces acting in the radial direction. Therefore, by making the outer peripheral surface 680 of the outer ring 62A the pressure-receiving surface, the outer ring 62A side with high rigidity can receive external stress, and the gear device 1A as a whole has high resistance to stress.

[0162] More specifically, the pressure receiving surface (the outer peripheral surface 680 of the outer ring 62A) is subjected to stress from an exterior body fitted to the outer peripheral surface of the outer ring 62A. Here, the tire 103 is an example of an exterior body fitted to the outer peripheral surface of the outer ring 62A. That is, when the tire 103 is mounted so as to fit to the outer peripheral surface of the body 18, the stress (fitting pressure) acting from the tire 103 to the body 18 is larger on the outer ring 62A than on the gear body 22. Specifically, for example, as shown in FIG. 17, a spacer 68 is provided at a portion corresponding to the outer ring 62A on the outer peripheral surface of the body 18, so that the outer diameter of the body 18 is made larger on the outer ring 62A than on the gear body 22. As a result, when the tire 103 as an exterior body is mounted to the body 18, the stress from the tire 103 is larger on the outer ring 62A side than on the gear body 22 side. However, the same effect can be achieved by, for example, reducing the outer diameter of the gear body 22 or reducing the inner diameter of the exterior body (tire 103, etc.) on the outer wheel 62A side compared to the gear body 22 side, without being limited to the configuration in which the spacer 68 is provided.

[0163] Alternatively, the gear device 1A may be configured such that the reaction force from the ground, such as the running surface, is greater on the outer peripheral surface 680 of the outer ring 62A as the pressure-receiving surface, even if the stress from the exterior body is the same on the outer peripheral surface 680 of the outer ring 62A and the outer peripheral surface 224 of the gear body 22. Specifically, for example, when the gear device 1A is used as the wheel device W1, the gear device 1A is configured such that the reaction force from the ground, such as the running surface, is greater on the outer ring 62A side than on the gear body 22 side by adjusting the camber angle. In this case, ground pressure from the ground contact surface acts on the pressure-receiving surface (the outer peripheral surface 680 of the outer ring 62A).

[0164] Furthermore, the gear device 1A according to this embodiment is not limited to the wheel device W1, but can also be applied to robots such as horizontal articulated robots (SCARA robots) as described in the basic configuration.

[0165] <Modification> The first embodiment is merely one of various embodiments of the present disclosure. Various modifications of the first embodiment are possible depending on the design, etc., as long as the object of the present disclosure can be achieved. In addition, all of the drawings referred to in this disclosure are schematic drawings, and the ratio of the size and thickness of each component in the drawings does not necessarily reflect the actual dimensional ratio. Modifications of the first embodiment are listed below. The modifications described below can be applied in appropriate combination.

[0166] The inner pin 4 only needs to penetrate the first inner ring 601 of the first inner ring 601 and the second inner ring 602 constituting the inner ring 61A, and as shown in Fig. 18A and Fig. 18B, the inner pin 4 may be inserted into a part or the whole of the second inner ring 602. In the example of Fig. 18A, the retaining hole 611 extends to a part of the second inner ring 602 in a direction parallel to the rotation axis Ax1, and the end of the inner pin 4 that penetrates the first inner ring 601 is inserted halfway into the second inner ring 602. In the example of Fig. 18B, the retaining hole 611 is formed so as to penetrate both the first inner ring 601 and the second inner ring 602 in a direction parallel to the rotation axis Ax1, and the inner pin 4 that penetrates the first inner ring 601 also penetrates the second inner ring 602.

[0167] In the first embodiment, the gear device 1A having two types of planetary gears 3 is exemplified, but the gear device 1A may have three or more planetary gears 3. For example, when the gear device 1A has three planetary gears 3, these three planetary gears 3 are preferably arranged with a phase difference of 120 degrees around the rotation axis Ax1. Also, the gear device 1A may have only one planetary gear 3.

[0168] Moreover, it is not essential for the gear device 1A that at least a portion of each of the multiple inner pins 4 is disposed at the same position as the bearing member 6A in the axial direction of the bearing member 6A. That is, the gear device 1A only needs to include the bearing member 6A, the internal gear 2, the planetary gear 3, and the multiple inner pins 4. The bearing member 6A has an outer ring 62A and an inner ring 61A disposed inside the outer ring 62A. The inner ring 61A is supported rotatably relative to the outer ring 62A. The gear body 22 of the internal gear 2 is fixed to the outer ring 62A. Each of the multiple inner pins 4 is held by the inner ring 61A in a rotatable state. Here, each of the multiple inner pins 4 may be disposed so as to be aligned (opposed) with the bearing member 6A in the axial direction of the bearing member 6A.

[0169] Furthermore, the numbers of the inner pins 4, the outer pins 23 (the number of teeth of the inner teeth 21), and the outer teeth 31 described in the first embodiment are merely examples and can be changed as appropriate.

[0170] Furthermore, the bearing member 6A is not limited to a cross roller bearing, and may be a deep groove ball bearing, an angular contact ball bearing, etc. However, it is preferable that the bearing member 6A be capable of withstanding any of a radial load, a thrust load (direction along the rotation axis Ax1), and a bending force (bending moment load) against the rotation axis Ax1, such as a four-point contact ball bearing.

[0171] Moreover, the eccentric bearing 5 is not limited to a roller bearing, but may be, for example, a deep groove ball bearing, an angular contact ball bearing, or the like.

[0172] Furthermore, the material of each component of the gear device 1A is not limited to metal, but may be, for example, a resin such as engineering plastic.

[0173] In addition, the gear device 1A is not limited to a configuration in which the rotational force of the outer ring 62A is output as long as the relative rotation between the inner ring 61A and the outer ring 62A of the bearing member 6A can be output as an output. For example, the rotational force of the inner ring 61A rotating relative to the outer ring 62A may be output as an output.

[0174] Furthermore, the lubricant is not limited to a liquid substance such as lubricating oil (oil), and may be a gel-like substance such as grease.

[0175] The gear device 1A may also include an inner roller. That is, in the gear device 1A, it is not essential that each of the multiple inner pins 4 directly contacts the inner circumferential surface 321 of the loose-fitting hole 32, and an inner roller may be interposed between each of the multiple inner pins 4 and the loose-fitting hole 32. In this case, the inner roller is attached to the inner pin 4 and is rotatable around the inner pin 4 as an axis.

[0176] Furthermore, it is sufficient that each of the multiple inner pins 4 is held by the inner ring 61A in a rotatable state, and it is not essential for the gear device 1A that each of the multiple inner pins 4 is directly held by the inner ring 61A. For example, each of the multiple inner pins 4 may be indirectly held by the inner ring 61A by being inserted into a holding hole formed in an output shaft or a carrier that is integrated with the inner ring 61A.

[0177] Furthermore, it is not essential for the gear device 1A that the support body 8 positions the multiple inner pins 4 relative to the support body 8 in both the circumferential and radial directions. For example, the support body 8 may have a slit-shaped support hole 82 extending in the radial direction, and position the multiple inner pins 4 relative to the support body 8 only in the circumferential direction. Conversely, the support body 8 may position the multiple inner pins 4 relative to the support body 8 only in the radial direction.

[0178] Furthermore, the gear device 1A may adopt at least one of the features for the inner ring 61A of the bearing member 6A and the features for the outer ring 62A, and it is not essential to adopt both of them. That is, the gear device 1A may adopt only one of the features that the inner ring 61A has the first inner ring 601 and the second inner ring 602 (the feature for the inner ring 61A) and that the outer ring 62A is provided seamlessly and continuously with the gear body 22 (the feature for the outer ring 62A).

[0179] Furthermore, since the gear device 1A only requires the use of at least one of the device for the inner ring 61A and the device for the outer ring 62A, other configurations can be omitted or changed as appropriate from the basic configuration. For example, in the gear device 1A, the inner pin 4 may be held in a state of being pressed into the inner ring 61A (or a carrier integrated with the inner ring 61A) as in the first related technique, and in this case, each of the multiple inner pins 4 is held in a state where it cannot rotate with respect to the inner ring 61A. Also, each of the multiple inner pins 4 does not have to be disposed at the same position as the bearing member 6A in the axial direction of the bearing member 6A. Alternatively, in the gear device 1A, the multiple inner pins 4 may be held only by the inner ring 61A (or a carrier integrated with the inner ring 61A) as in the second related technique. In this case, the support body 8 can be omitted. Furthermore, even if a support body 8 is provided to support (bundle) multiple inner pins 4, it is not necessary for the support body 8 to be positionally regulated by contacting its outer peripheral surface 81 with the multiple outer pins 23, and the outer peripheral surface 81 of the support body 8 may be separated from the multiple outer pins 23.

[0180] Also, with regard to the innovation regarding the inner ring 61A, the gear device 1A only needs to have the first inner ring 601 and the second inner ring 602, and the inner ring 61A may be divided into, for example, three or more parts. That is, as one example, the inner ring 61A may be divided into three parts by having a third inner ring in addition to the first inner ring 601 and the second inner ring 602.

[0181] Furthermore, the multiple holes into which the multiple positioning pins 65 are press-fitted need only be formed from the first inner ring 601 to the second inner ring 602, and do not have to penetrate the inner ring 61A in a direction parallel to the rotation axis Ax1. For example, the positioning pins 65 may be press-fitted into holes formed from the opposing surface 602A side of the second inner ring 602 facing the first inner ring 601 to partway through the thickness of the second inner ring 602. In this case, leakage of lubricant through the holes into which the positioning pins 65 are press-fitted is prevented.

[0182] Regarding the innovation regarding the outer ring 62A, the outer ring 62A of the bearing member 6A does not have to be completely seamless in the direction parallel to the gear body 22 and the rotation axis Ax1. That is, the manufacturing method of the gear device 1A only needs to include a step of integrally forming the outer ring 62A and the gear body 22 by processing one base material. Specifically, for example, the outer ring 62A and the gear body 22 may be integrally formed by processing one base material in which two types of metal blocks are joined (integrated) by crimping, bonding, or the like. In this case, since a seam is generated at the joint portion of the two types of metal blocks, it is not completely seamless, but the same effect as that of the outer ring 62A and the gear body 22 that are seamlessly continuous can be expected.

[0183] (Embodiment 2) As shown in Fig. 19A and Fig. 19B, an internal meshing planetary gear device 1B according to this embodiment (hereinafter also simply referred to as "gear device 1B") differs from the gear device 1A according to embodiment 1 in the detailed shape of an inner ring 61A of a bearing member 6A. Fig. 19B is a diagram showing only the main parts of a first inner ring 601 in a cross section taken along line A1-A1 in Fig. 19A. Hereinafter, common reference numerals will be used to designate configurations similar to those of embodiment 1, and descriptions thereof will be omitted as appropriate.

[0184] In the gear device 1B according to this embodiment, an enlarged diameter portion 691 is formed on the surface of the first inner ring 601 opposite to the second inner ring 602, to enlarge the opening area of ​​each of the multiple retaining holes 611. Specifically, as shown in FIG. 19A, the enlarged diameter portion 691 is configured by a chamfered portion formed on the opening periphery of the retaining hole 611 on the input side (left side in FIG. 19A) surface of the rotation axis Ax1 of the first inner ring 601. Here, the enlarged diameter portion 691 is formed in a tapered shape (C-shaped surface) so that the opening area of ​​the retaining hole 611 increases as it moves away from the second inner ring 602. In this embodiment, such an enlarged diameter portion 691 is formed corresponding to each of all the retaining holes 611. The enlarged diameter portion 691 is not limited to a tapered shape (C-shaped surface), and may be, for example, a curved R-shaped surface, a stepped countersink shape, or the like.

[0185] By forming such an expanded diameter portion 691, at least in the opening surface of each of the multiple retaining holes 611 on the side opposite to the second inner ring 602, the gap between the inner pin 4 and the retaining hole 611 is expanded. As a result, the gap between the inner peripheral surface of the retaining hole 611 and the inner pin 4 created by the expanded diameter portion 691 functions as an "oil reservoir" for storing lubricant (lubricating oil). Since the expanded diameter portion 691 is continuous with the retaining hole 611, the lubricant stored in the expanded diameter portion 691 is drawn into the gap between the inner peripheral surface of the retaining hole 611 and the inner pin 4 by capillary action, for example, and acts to smooth the rotation (spinning) of the inner pin 4.

[0186] Furthermore, the enlarged diameter portion 691 as an "oil reservoir" is located on the circulation path RL1 of the lubricant, as shown in Fig. 20. Therefore, by using a part of the circulation path RL1 as a path for the "lubricant", the lubricant in the enlarged diameter portion 691 can be supplied to at least one of the outer pin 23 and the rolling elements 63 other than the inner pin 4. In particular, in this embodiment, since both the outer pin 23 and the rolling elements 63 are located on the circulation path RL1 as shown in Fig. 20, the lubricant held in the enlarged diameter portion 691 can be supplied to both the outer pin 23 and the rolling elements 63.

[0187] In this embodiment, as shown in Figs. 19A and 19B, a connecting groove 692 is formed in the opposing surface 601A, 602A of at least one of the first inner ring 601 and the second inner ring 602 facing the other. The connecting groove 692 connects a space that houses each of the plurality of rolling elements 63 to each of the plurality of retaining holes 611. That is, the connecting groove 692 is provided in at least one of the opposing surfaces 601A and 602A that are dividing surfaces of the first inner ring 601 and the second inner ring 602, and connects a space that houses each of the rolling elements 63 between the inner ring 61A and the outer ring 62A to the retaining hole 611. As an example, in this embodiment, the connecting groove 692 is formed in the opposing surface 601A of the first inner ring 601 facing the second inner ring 602 along the radial direction of the inner ring 61A. In this embodiment, such connecting grooves 692 are formed corresponding to all of the holding holes 611, respectively.

[0188] The connecting groove 692 functions as a path for passing the lubricant (lubricating oil). In this embodiment, as shown in FIG. 20, the connecting groove 692 constitutes a part of the circulation path RL1 of the lubricant. In this embodiment, as shown in FIG. 19B, as an example, the connecting groove 692 has a rectangular cross section perpendicular to the radial direction of the inner ring 61A. The depth D4 (from the opposing surface 601A) of the connecting groove 692 and the width D5 of the connecting groove 692 are preferably 1 / 10 (φ10×1 / 10) or more and twice (φ10×2) the diameter φ10 of the outer pin 23. As an example, when the diameter φ10 of the outer pin 23 is about 2.5 mm, the depth D4 and the width D5 of the connecting groove 692 are preferably 0.25 mm or more and 5.0 mm or less. 20, the depth D4 of the connecting groove 692 is smaller than the width D5 of the connecting groove 692, but this is not limiting, and the depth D4 of the connecting groove 692 may be equal to or larger than the width D5. Furthermore, the cross-sectional shape of the connecting groove 692 is not limited to a rectangular shape, and may be a semicircular shape, a triangular shape, or another polygonal shape, etc.

[0189] The provision of such a connecting groove 692 allows the lubricant to circulate easily through the connecting groove 692 in the lubricant retention space 17. In particular, the connecting groove 692 is connected to a space between the inner ring 61A and the outer ring 62A that accommodates the rolling element 63. Therefore, when the bearing member 6A operates and the rolling element 63 rotates, the rolling element 63 functions as a pump, and it is possible to actively circulate the lubricant in the lubricant retention space 17 via the connecting groove 692. As a result, the lubricant in the lubricant retention space 17 is easily circulated, and even when the gear device 1B is used for a long period of time, the lubricant is easily distributed throughout the lubricant retention space 17, and problems such as a decrease in transmission efficiency in the gear device 1B are less likely to occur.

[0190] Furthermore, the provision of the connecting groove 692 is expected to have the effect of lowering the internal pressure in the space between the oil seal 16 and the rolling elements 63. In other words, the space between the oil seal 16 and the rolling elements 63 is connected to the retaining hole 611 by the connecting groove 692, and the space between the oil seal 16 and the rolling elements 63 is expanded, which leads to suppression of an increase in internal pressure when the rolling elements 63 function as a pump. As a result of suppressing an increase in the internal pressure of the lubricant retaining space 17, for example, leakage of the lubricant beyond the oil seal 16 is less likely to occur.

[0191] As a modification of the second embodiment, the connecting groove 692 may be formed in the opposing surfaces 601A, 602A of both the first inner ring 601 and the second inner ring 602. Moreover, the connecting groove 692 may be formed only in the opposing surface 602A of the second inner ring 602.

[0192] As another modification of the second embodiment, the large diameter portion 691 and the connecting groove 692 may be employed separately. That is, the gear device 1B may have only the large diameter portion 691 out of the large diameter portion 691 and the connecting groove 692, or may have only the connecting groove 692.

[0193] The configuration of the second embodiment (including the modified examples) can be applied in appropriate combination with the configuration described in the first embodiment (including the modified examples).

[0194] (summary) As described above, the internally meshing planetary gear device (1, 1A, 1B) according to the first aspect includes a bearing member (6, 6A), an internal gear (2), a planetary gear (3), and a plurality of inner pins (4). The bearing member (6, 6A) includes an outer ring (62, 62A), an inner ring (61, 61A) disposed inside the outer ring (62, 62A), and a plurality of rolling elements (63) disposed between the outer ring (62, 62A) and the inner ring (61, 61A), and the inner ring (61, 61A) is supported so as to be rotatable relative to the outer ring (62, 62A) about a rotation axis (Ax1). The internal gear (2) has internal teeth (21) and is fixed to the outer ring (62, 62A). The planetary gear (3) has external teeth (31) that partially mesh with the internal teeth (21). The multiple inner pins (4) are inserted into multiple loose fitting holes (32) formed in the planetary gear (3) and rotate relative to the internal gear (2) while revolving within the loose fitting holes (32). The inner rings (61, 61A) include a first inner ring (601) and a second inner ring (602) that face each other in a direction parallel to the rotation axis (Ax1) and whose facing surfaces (601A, 602A) are in contact with each other. The first inner ring (601) has multiple retaining holes (611) through which the multiple inner pins (4) respectively pass in a direction parallel to the rotation axis (Ax1). Each of the multiple inner pins (4) is retained by the inner rings (61, 61A) in a rotatable state.

[0195] According to this embodiment, a gap, even if small, may be formed between the first inner ring (601) and the second inner ring (602). The formation of such a gap makes it easier for a lubricant to be supplied to the inner pin (4) or the like through the gap. Therefore, for example, compared with a case in which the inner ring (61, 61A) is not divided into the first inner ring (601) and the second inner ring (602), the lubricant is more likely to spread throughout the entire inner ring even when the internal meshing planetary gear device (1, 1A, 1B) is used for a long period of time, and defects such as a decrease in transmission efficiency in the internal meshing planetary gear device (1, 1A, 1B) are less likely to occur.

[0196] In the internal meshing planetary gear device (1, 1A, 1B) according to the second aspect, in the first aspect, the end face of each of the multiple inner pins (4) is abutted against the opposing surface (602A) of the second inner ring (602) that faces the first inner ring (601).

[0197] According to this embodiment, the movement of the inner pin (4) in a direction parallel to the rotation axis (Ax1) is restricted by the second inner ring (602), and leakage of the lubricant through the retaining hole (611) is suppressed.

[0198] In the internal meshing planetary gear device (1, 1A, 1B) according to the third aspect, in the first or second aspect, a gap is formed between the inner circumferential surface of each of the multiple retaining holes (611) in the first inner ring (601) and the outer circumferential surface of each of the multiple inner pins (4).

[0199] According to this embodiment, the rotation of the inner pin (4) within the retaining hole (611) becomes smoother due to the lubricant.

[0200] In the internal meshing planetary gear device (1, 1A, 1B) according to the fourth aspect, in any one of the first to third aspects, an enlarged diameter portion (691) that enlarges the opening area of ​​each of the multiple retaining holes (611) is formed on the surface of the first inner ring (601) opposite the second inner ring (602).

[0201] According to this embodiment, the gap between the inner surface of the retaining hole (611) created by the enlarged diameter portion (691) and the inner pin (4) functions as an “oil reservoir” for retaining lubricant, and acts to facilitate the rotation (spinning) of the inner pin (4).

[0202] In the internal meshing planetary gear device (1, 1A, 1B) according to the fifth aspect, in any one of the first to fourth aspects, a connecting groove (692) is formed in a facing surface (601A, 602A) of at least one of the first inner ring (601) and the second inner ring (602) that faces the other. The connecting groove (692) connects a space that houses each of the plurality of rolling elements (63) to each of the plurality of retaining holes (611).

[0203] According to this embodiment, the lubricant can easily circulate through the connecting groove 692. In particular, when the rolling elements 63 rotate, the rolling elements 63 function as a pump, and the lubricant can be actively circulated through the connecting groove 692.

[0204] In the internal meshing planetary gear device (1, 1A, 1B) according to the sixth aspect, in any one of the first to fifth aspects, the difference between the surface hardness of each of the plurality of inner pins (4) and the surface hardness of the first inner ring (601) is HRC3 or less.

[0205] According to this embodiment, wear powder and the like is less likely to be generated even when the inner pin (4) rotates within the retaining hole (611), making it easier to maintain smooth rotation of the inner pin (4) for a long period of time.

[0206] In the internal meshing planetary gear device (1, 1A, 1B) according to the seventh aspect, in any one of the first to sixth aspects, the surface hardness of each of the plurality of inner pins (4) is within the range of HRC60±3.

[0207] According to this embodiment, wear powder and the like is less likely to be generated even when the inner pin (4) rotates within the retaining hole (611), making it easier to maintain smooth rotation of the inner pin (4) for a long period of time.

[0208] In the internal meshing planetary gear device (1, 1A, 1B) according to the eighth aspect, in any one of the first to seventh aspects, a plurality of rolling elements (63) are located on a plane including a surface (601A) of the first inner ring (601) facing the second inner ring (602).

[0209] According to this embodiment, when the rolling elements (63) rotate, the rolling elements (63) efficiently function as a pump, and the lubricant is easily circulated.

[0210] In the ninth aspect of the internal meshing planetary gear device (1, 1A, 1B), in the eighth aspect, the center of each of the multiple rolling elements (63) in a direction parallel to the rotation axis (Ax1) is located on the same plane as the opposing surface (601A) of the first inner ring (601) with the second inner ring (602).

[0211] According to this embodiment, when the rolling elements (63) rotate, the rolling elements (63) efficiently function as a pump, and the lubricant is easily circulated.

[0212] The internal meshing planetary gear unit (1, 1A, 1B) according to a tenth aspect is in any one of the first to ninth aspects, and further includes a lubricant circulation path (RL1). The lubricant circulation path (RL1) passes through at least the gap between the first inner ring (601) and the second inner ring (602), the spaces that house each of the plurality of rolling elements (63), and each of the plurality of retaining holes (611).

[0213] According to this embodiment, the lubricant can easily circulate through the rolling elements (63) and the inner pins (4).

[0214] The configurations according to the second to tenth aspects are not essential configurations for the internal meshing planetary gear device (1, 1A, 1B) and can be omitted as appropriate. [Explanation of symbols]

[0215] 1,1A,1B Internal meshing planetary gear device 2 Internal gear 3 Planetary Gears 4 Inner pin 6,6A Bearing materials 21 Inner teeth 31 Outer teeth 32 Free fit hole 61,61A Inner ring 62,62A Outer ring 63 Rolling elements 601 First Inner Ring 601A (First inner ring) facing surface 602 Second Inner Ring 602A (of the second inner ring) facing surface 611 Retaining hole 691 Expanded diameter part 692 Connection groove Ax1 Rotation axis RL1 circulation path

Claims

1. a bearing member including an outer ring, an inner ring disposed inside the outer ring, and a plurality of rolling elements disposed between the outer ring and the inner ring, the inner ring being supported so as to be rotatable 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; a plurality of inner pins that are inserted into a plurality of loose-fitting holes formed in the planetary gear and rotate relative to the internal gear while revolving within the loose-fitting holes, the inner ring includes a first inner ring and a second inner ring that face each other in a direction parallel to the rotation shaft and have facing surfaces in contact with each other, an end surface of each of the plurality of inner pins abuts against a surface of the second inner ring that faces the first inner ring; Internally meshing planetary gear set.

2. A bearing member having an outer ring, an inner ring disposed inside the outer ring, and a plurality of rolling elements disposed between the outer ring and the inner ring, the inner ring being supported so as to be rotatable 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; a plurality of inner pins that are inserted into a plurality of loose-fitting holes formed in the planetary gear and rotate relative to the internal gear while revolving within the loose-fitting holes, the inner ring includes a first inner ring and a second inner ring that face each other in a direction parallel to the rotation shaft and have facing surfaces in contact with each other, the first inner ring is provided with a plurality of retaining holes through which the plurality of inner pins respectively pass, a connecting groove is formed on a surface of at least one of the first inner ring and the second inner ring facing the other, the connecting groove connecting a space for accommodating each of the plurality of rolling elements to each of the plurality of retaining holes; Internally meshing planetary gear set.

3. the plurality of rolling elements are located on a plane including a surface of the first inner ring facing the second inner ring, 3. The internal meshing planetary gear device according to claim 1 or 2.

4. a center of each of the plurality of rolling elements in a direction parallel to the rotation axis is located on the same plane as a surface of the first inner ring facing the second inner ring, 4. The internal meshing planetary gear device according to claim 3.

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