JP7463266B2 - Internally meshing planetary gear device and manufacturing method thereof - Google Patents

Description

This disclosure relates generally to an internally meshed planetary gear device and a manufacturing method thereof, and more specifically to an internally meshed planetary gear device in which a planetary gear having external teeth is arranged inside an internal gear having internal teeth, and a manufacturing method thereof.

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

The internal gear is constructed by rotatably assembling a number of outer pins (roller pins), each of which constitutes an internal tooth, into 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, into which the inner pins and inner rollers are inserted. The inner pins are connected to a carrier at one end 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.

JP 2003-74646 A

In the configuration of the related art described above, the gear body is sandwiched between the outer ring of the cross roller bearing and the casing (third casing) and fixed with bolts, making it difficult to improve the accuracy of centering between the internal gear and the cross roller bearing. Therefore, poor centering can lead to problems such as vibration generation and reduced transmission efficiency.

The objective of this disclosure is to provide an internally meshing planetary gear device that is less susceptible to defects caused by misalignment, and a method for manufacturing the same.

The 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 around a rotation axis. The internal gear has an annular gear body and a plurality of external pins that are held on the inner peripheral surface of the gear body in a rotatable state and form internal teeth. 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 formed in the planetary gear, respectively, in a state where they are inserted into the multiple loose fitting holes formed in the planetary gear. The outer ring is provided seamlessly and continuously with the gear body in a direction parallel to the rotation axis.

The manufacturing method of an internally meshed planetary gear device according to one aspect of the present disclosure is a manufacturing method of an internally meshed planetary gear device including a bearing member, an internal gear, a planetary gear, and a plurality of internal pins. The bearing member has an outer ring and an inner ring arranged inside the outer ring, and the inner ring is supported so as to be rotatable relative to the outer ring around a rotation axis. The internal gear has an annular gear body and a plurality of external pins that are held on the inner peripheral surface of the gear body in a rotatable state and form internal teeth. 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 formed in the planetary gear, respectively, in a state where they are inserted into multiple loose fitting holes formed in the planetary gear. The manufacturing method includes a step of integrally forming the outer ring and the gear body by processing one base material.

This disclosure provides an internally meshed planetary gear device that is less susceptible to defects caused by misalignment, and a method for manufacturing the same.

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. 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. FIG. 3 is a schematic cross-sectional view of the internal meshing planetary gear device. FIG. 4 is a cross-sectional view taken along line A1-A1 in FIG. 3, showing the internal meshing planetary gear device. FIG. 5A is a perspective view showing a planetary gear of the internal meshing planetary gear device alone. FIG. 5B is a front view showing a planetary gear of the internal meshing planetary gear device alone. FIG. 6A is a perspective view showing the bearing member of the internal meshing planetary gear device alone. FIG. 6B is a front view showing the bearing member of the internal meshing planetary gear device alone. FIG. 7A is a perspective view showing the eccentric shaft of the internal meshing planetary gear device alone. FIG. 7B is a front view showing the eccentric shaft of the internal meshing planetary gear set alone. FIG. 8A is a perspective view showing the support body of the internal meshing planetary gear device alone. FIG. 8B is a front view showing the support body of the internal meshing planetary gear set alone. FIG. 9 is an enlarged view of an area Z1 in FIG. 3, showing the internal meshing planetary gear device. FIG. 10 is a cross-sectional view taken along line B1-B1 in FIG. 3, showing the internal meshing planetary gear device. FIG. 11 is a schematic cross-sectional view of an internal meshing planetary gear device according to the first embodiment. FIG. 12 is a side view of the internal meshing planetary gear device as viewed from the output side of the rotary shaft. FIG. 13 is a cross-sectional view taken along line A1-A1 in FIG. 11, showing the internal meshing planetary gear device. 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. FIG. 15 is a schematic cross-sectional view of a main part of the internal meshing planetary gear device. FIG. 16 is a schematic cross-sectional view of a main part of the internal meshing planetary gear unit, and is a diagram showing a schematic view of a path of a lubricant. FIG. 17 is a schematic cross-sectional view of a wheel assembly using the above internal meshing planetary gear device. FIG. 18A is a schematic cross-sectional view of a main portion of an internal meshing planetary gear device according to a modified example of the first embodiment. FIG. 18B is a schematic cross-sectional view of a main portion of an internal meshing planetary gear device according to a modified example of the first embodiment. FIG. 19A is a schematic cross-sectional view of a main portion of an internal meshing planetary gear device according to embodiment 2. FIG. 19B is a cross-sectional view taken along line A1-A1 in FIG. 19A, showing a main portion of the internal meshing planetary gear device. FIG. 20 is a schematic cross-sectional view of a main part of the internal meshing planetary gear unit, and is a diagram showing a schematic diagram of a path of a lubricant.

(Basic configuration)
(1) Overview Below, an overview of the internally meshing planetary gear device 1 according to this basic configuration will be described with reference to Figures 1 to 3. All of the drawings referred to in this disclosure are schematic diagrams, 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.

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 internal pins 4. In this gear device 1, the planetary gear 3 is arranged inside the annular internal gear 2, and an eccentric bearing 5 is arranged inside the planetary gear 3. The eccentric bearing 5 has an 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) that is offset 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 the 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.

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 circumferential 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 in the internal gear 2 inside the internal gear 2, and a part of the external teeth 31 is meshed with a part of the internal teeth 21. In this state, when the eccentric shaft 7 rotates, the planetary gear 3 oscillates, and the meshing position 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 the two gears (the internal gear 2 and the planetary gear 3). If the internal gear 2 is fixed, the planetary gear 3 rotates (spins) in response to the relative rotation of the two gears. As a result, the planetary gear 3 produces a rotational output that is reduced at a relatively high reduction ratio according to the difference in the number of teeth between the two gears.

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. Therefore, in the gear device 1 according to this basic configuration, 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 planetary gear 3 and the inner ring 61 are connected by a plurality of inner pins 4. The plurality of inner pins 4 rotate relative to the internal gear 2 while revolving within the respective loose fitting holes 32, while being inserted into the respective 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 multiple inner pins 4 moving so as to revolve within the multiple 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 multiple inner pins 4.

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 within the loose fitting hole 32 of the planetary gear 3. Therefore, as a first related technology, 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 technology, the inner pin 4 is held in a pressed state against the inner ring 61 (or a carrier integrated with the inner ring 61), and when the inner pin 4 revolves within 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 technology, an inner roller is used to reduce losses due to friction 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 technology, the loose fitting hole 32 needs to have a diameter that allows the inner pin 4 with the inner roller to revolve, making it difficult to reduce the size of the loose fitting hole 32. If it is difficult to reduce the size of the loose fitting hole 32, this will hinder the miniaturization (particularly the diameter reduction) of the planetary gear 3, and ultimately hinder the miniaturization of the entire gear device 1. The gear device 1 according to this basic configuration can provide an internal meshing planetary gear device 1 that is easy to reduce in size by using the following configuration.

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 multiple internal 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 internal 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 internal pins 4 is held by the inner ring 61 in a rotatable state. Furthermore, at least a portion of each of the multiple internal pins 4 is arranged at the same position as the bearing member 6 in the axial direction of the bearing member 6.

According to this embodiment, 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 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 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 portion 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, the dimensions 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 lined up (opposed) in the axial direction of the bearing member 6, the gear device 1 according to this basic configuration can reduce the dimensions of the gear device 1 in the axial direction, which can contribute to further miniaturization (thinning) of the gear device 1.

Furthermore, if the dimensions of the planetary gear 3 are the same as those in the first related technology, it is possible to 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.

In addition, in this type of gear device 1, since the inner pin 4 needs to revolve within the loose fitting hole 32 of the planetary gear 3, as a second related technology, 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 technology, 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 relative to the internal gear 2 while revolving within 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 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 internally meshed planetary gear device 1 that is less likely to cause problems due to centering failure of the multiple inner pins 4 due to the following configuration.

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

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 the relative deviation and inclination of the multiple inner pins 4 is 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, according to the gear device 1 of this basic configuration, there is an 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.

As shown in FIG. 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 a driving source 101. The driving source 101 generates a driving force for oscillating the planetary gear 3. Specifically, the driving source 101 oscillates the planetary gear 3 by rotating the eccentric shaft 7 about the rotation axis Ax1.

(2) Definition In the present disclosure, "annular" means 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.

In this disclosure, "loose fit" means being fitted with 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 can move within the loose fit hole 32 when inserted into the loose fit hole 32, that is, it can move relatively to the center of the loose fit hole 32. Therefore, the inner pin 4 can revolve 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.

In this disclosure, "revolution" means that an object revolves around an axis of rotation other than the central axis that passes through the center (center of gravity) of the object, and when an object revolves, the center of the object moves along an orbital path centered on the axis of rotation. Therefore, for example, when an object rotates around an eccentric axis that is parallel to the central axis that passes through the center (center of gravity) of the object, the object revolves around the eccentric axis as the axis of rotation. As an example, the inner pin 4 revolves within the loose fitting hole 32, revolving around the axis of rotation that passes through the center of the loose fitting hole 32.

In addition, in this 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 the rotating body (eccentric inner ring 51) from the "input side" of the rotating shaft Ax1, and rotation of the 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.

In this 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 entity. The eccentric inner ring 51 rotates around the rotation axis Ax1.

In this disclosure, "internal teeth" and "external teeth" do not refer to individual "tooths," but rather to 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.

(3) Configuration Hereinafter, a 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.

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

(3.1) Overall Configuration As shown in Figures 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.

In addition, in this basic configuration, an internal planetary gear device using a trochoidal tooth profile is exemplified as an example of the gear device 1. In other words, the gear device 1 according to this basic configuration is equipped with an internal planetary gear 3 having a trochoidal curved tooth profile.

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

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 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 compared to the input rotation.

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 allows the driving source 101 to rotate the eccentric shaft 7.

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) that generates the output rotation. In other words, in the gear device 1, an output rotation that is reduced in speed at a relatively high reduction ratio compared to the input rotation is obtained on the same axis.

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 multiple teeth that make up the internal teeth 21 all have 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.

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 peripheral 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 peripheral surface 221 of the gear body 22 over the entire circumferential area. All of the plurality of grooves are of 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 is fixed to the case 10 (together with the outer ring 62). Therefore, the gear body 22 is formed with a plurality of fixing holes 222 for fixing.

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 peripheral surface is a perfect circle in a plan view. The outer peripheral surface of the annular planetary gear 3 is formed with external teeth 31 along the circumferential direction of the planetary gear 3. The multiple teeth constituting the external teeth 31 all have the same shape and are provided at equal pitch over the entire circumferential area of the outer peripheral surface of the planetary gear 3. In other words, the pitch circle of the external teeth 31 is a perfect circle 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 also 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 from a single metal member.

Here, the eccentric body bearing 5 and the eccentric shaft 7 are combined with the planetary gear 3. That is, the planetary gear 3 has 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 circumferential surface of the opening 33 (the inner circumferential 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 body bearing 5 (the eccentric inner ring 51), 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 with the eccentric body bearing 5 and the eccentric shaft 7 combined with the planetary gear 3, the planetary gear 3 oscillates around the rotation axis Ax1.

The planetary gear 3 configured in this manner is disposed inside the internal gear 2. In a plan view, the planetary gear 3 is formed to be one size smaller than the internal gear 2, and the planetary gear 3 can 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.

Furthermore, the pitch circle of the external teeth 31 is one size smaller than the pitch circle of the internal teeth 21. And, 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 located at a position shifted by a distance ΔL (see FIG. 4) from the center of the pitch circle of the internal teeth 21 (rotation axis Ax1). Therefore, the external teeth 31 and the internal teeth 21 face each other at least partially through a gap, and do not mesh with each other in the entire 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, by oscillating the planetary gear 3 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.

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. As an example of this basic configuration, 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 determines the reduction ratio of the output rotation to the input rotation in the gear device 1.

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 in 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, in the direction parallel to the rotation axis Ax1, the external teeth 31 are contained within the range of the tooth trace of the internal teeth 21.

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. Therefore, the planetary gear 3 is connected to the inner ring 61 by a plurality of inner pins 4. As shown in Figures 5A and 5B, the planetary gear 3 has a plurality of loose fitting holes 32 for inserting a plurality of inner pins 4. The loose fitting holes 32 are provided in the same number as the 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 multiple loose fitting holes 32 is a hole that opens in a circular shape and penetrates the planetary gear 3 along the thickness direction. The multiple (here, 18) loose fitting holes 32 are arranged at equal intervals in the circumferential direction on a virtual circle concentric with the opening 33.

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 diameter and length of the multiple inner pins 4 are the same for all of the multiple inner pins 4. 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 circumferential surface 321 of the loose fitting hole 32 (see FIG. 4).

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 also has a number of rolling elements 63 (see FIG. 3).

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.

The inner ring 61 has a number of retaining holes 611 into which the 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 Figures 6A and 6B, each of the multiple retaining holes 611 has a circular opening and is a hole that penetrates the inner ring 61 in the thickness direction. The multiple (here, 18) retaining holes 611 are arranged at equal intervals in the circumferential direction on a virtual circle concentric with the outer periphery of the inner ring 61. The diameter of the retaining hole 611 is equal to or greater than the diameter of the inner pin 4 and smaller than the diameter of the loose fitting hole 32.

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 retaining holes 611 and are arranged on a virtual circle concentric with the outer periphery of the inner ring 61.

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 that pass 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.

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 in a line in the circumferential direction of the outer ring 62. The multiple rolling elements 63 are all metal parts of the same shape, and are provided at equal pitches over the entire circumferential area of the outer ring 62.

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 able to withstand radial loads, thrust loads (direction along the rotation axis Ax1), and bending forces (bending moment loads) against the rotation axis Ax1. Moreover, a single bearing member 6 can withstand these three types of loads and ensure the necessary rigidity.

As shown in Figures 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 the outer peripheral 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 the outer peripheral surface being a perfect circle in a plan view. The center (central axis) of the eccentric portion 72 coincides with the center C1 shifted from the rotation axis Ax1. Here, the distance ΔL (see Figure 7B) between the rotation axis Ax1 and the center C1 is the 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 peripheral surface of the axial center portion 71 over the entire circumference at the center of the longitudinal direction (axial direction) of the axial center portion 71. According to the above-described configuration, the eccentric shaft 7 rotates (spins) the axial center portion 71 about the rotation axis Ax1, causing the eccentric portion 72 to perform eccentric motion.

In this basic configuration, the shaft center 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 this shape is combined with the planetary gear 3 together with the eccentric body bearing 5. Therefore, when the eccentric shaft 7 rotates with the eccentric body bearing 5 and eccentric shaft 7 combined with the planetary gear 3, the planetary gear 3 oscillates around the rotation axis Ax1.

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 faces of the shaft center portion 71. The center (central axis) of the through hole 73 coincides with the rotation axis Ax1. For example, cables such as power lines and signal lines can be passed through the through hole 73.

In addition, 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 Figures 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.

The eccentric bearing 5 has an eccentric outer ring 52 and an eccentric inner ring 51, and is a component that absorbs the rotational component of the rotation of the eccentric shaft 7 and transmits only the rotation of the eccentric shaft 7 excluding the rotational 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 multiple rolling elements 53 (see Figure 3).

The eccentric outer ring 52 and the eccentric inner ring 51 are both annular parts. The eccentric outer ring 52 and the eccentric inner ring 51 both 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.

The multiple rolling elements 53 are arranged in the gap between the eccentric outer ring 52 and the eccentric inner ring 51. The multiple rolling elements 53 are arranged in a line 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 area 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.

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 with the eccentric portion 72 of the eccentric shaft 7 inserted into the eccentric inner ring 51. 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 with the eccentric outer ring 52 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 attached to the eccentric portion 72 of the eccentric shaft 7.

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

When the eccentric shaft 7 rotates with the eccentric bearing 5 and the eccentric shaft 7 combined with the planetary gear 3, the eccentric inner ring 51 rotates (eccentrically moves) around the rotation axis Ax1 that is offset from the center C1 of the eccentric inner ring 51 in the eccentric bearing 5. At this time, the rotation component of the eccentric shaft 7 is absorbed by the eccentric bearing 5. Therefore, 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 is transmitted to the planetary gear 3 by the eccentric bearing 5. Therefore, when the eccentric shaft 7 rotates with the eccentric bearing 5 and the eccentric shaft 7 combined with the planetary gear 3, the planetary gear 3 oscillates around the rotation axis Ax1.

As shown in Figs. 8A and 8B, the support 8 is an annular component that supports multiple inner pins 4. The support 8 has multiple support holes 82 into which the multiple 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 multiple support holes 82 opens in a circular shape and penetrates the support 8 in the thickness direction. The multiple (here, 18) support holes 82 are arranged at equal intervals in the circumferential direction on a virtual circle concentric with the outer circumferential surface 81 of the support 8. The diameter of the support hole 82 is equal to or greater 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.

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, and the support 8 functions to bundle the inner pins 4. Furthermore, the position of the support 8 is restricted by contacting the outer peripheral 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 "(3.3) Support" section.

The first bearing 91 and the second bearing 92 are each 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 holds the eccentric shaft 7 rotatably relative to the case 10. The second bearing 92 holds the eccentric shaft 7 rotatably 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.

The case 10 is cylindrical and has a flange portion 11 on the output side of the rotating shaft Ax1. The flange portion 11 has a plurality of mounting holes 111 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. The first bearing 91 is attached to the case 10 by fitting it into the bearing hole 12.

In addition, multiple screw 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 multiple screw 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, the fixing screw 60 is passed through the through hole 621 of the outer ring 62 and the fixing hole 222 of the gear body 22 and tightened into the screw hole 13, thereby fixing the gear body 22 and the outer ring 62 to the case 10.

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 the input side end of the rotating shaft Ax1 of the eccentric shaft 7, and closes the gap between the case 10 and the eccentric shaft 7 (shaft center portion 71). The oil seal 15 is attached to the output side end of the rotating shaft Ax1 of the eccentric shaft 7, and closes the gap between the inner ring 61 and the eccentric shaft 7 (shaft center portion 71). The oil seal 16 is attached to the output side end face of the rotating shaft Ax1 of the bearing member 6, and closes the gap between the inner ring 61 and the outer ring 62. The space sealed by these plurality of oil seals 14, 15, 16 constitutes a lubricant retention space 17 (see FIG. 9). The lubricant retention space 17 includes the space between the inner ring 61 and the outer ring 62 of the bearing member 6. Furthermore, the lubricant retention space 17 contains multiple outer pins 23, planetary gears 3, eccentric bearings 5, support 8, first bearing 91, second bearing 92, etc.

The 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 in use, 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. In this disclosure, the term "liquid" 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" state 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" state 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).

In the gear device 1 having the above-mentioned configuration, a rotational force is applied to the eccentric shaft 7 as an input, and the eccentric shaft 7 rotates around the rotation axis Ax1, causing the planetary gear 3 to oscillate (revolve) around the rotation axis Ax1. At this time, the planetary gear 3 is inscribed in the internal gear 2 inside the internal gear 2, and oscillates with a part of the external teeth 31 meshing with a part of the internal teeth 21, so that the meshing position between 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.

As described above, in the gear device 1 according to this embodiment, the difference in the number of teeth between the internal gear 2 and the planetary gear 3 determines the reduction ratio of the output rotation to the input rotation in the gear device 1. In other words, if 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.

R1=V2/(V1-V2) (Equation 1)
In short, 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 one revolution (360 degrees) clockwise around the rotation axis Ax1, 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).

With the gear device 1 according to this basic configuration, such a high reduction ratio R1 can be achieved with a combination of one gear stage (internal gear 2 and planetary gear 3).

The gear device 1 must include at least an internal gear 2, a planetary gear 3, a number of internal pins 4, a bearing member 6, and a support 8, and may further include other components such as a spline bush.

However, 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. In other words, since the rotating body consisting of at least one of the eccentric inner ring 51 and the member (eccentric shaft 7) rotating with the eccentric inner ring 51 moves eccentrically 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 Figures 3 and 4, a gap 75 is provided in 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.

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 rotating axis Ax1. That is, the gear device 1 according to this basic configuration is provided with an eccentric bearing 5 that is housed in an opening 33 formed in the planetary gear 3 and swings the planetary gear 3. The eccentric bearing 5 has an eccentric outer ring 52 and an eccentric inner ring 51 arranged 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 with the eccentric inner ring 51 has a gap 75 in a part of the center C1 side of the eccentric outer ring 52 when 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 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 Figures 3 and 4, this gap 75 is located on the center C1 side when viewed from the rotation axis Ax1, so it acts to make the weight balance of the eccentric shaft 7 closer to even in the circumferential direction from the rotation axis Ax1.

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 an 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 balance the weight of the rotor without changing the appearance.

(3.2) Rotation Structure of 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 area Z1 in Fig. 3.

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.

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 can move within the loose fitting hole 32, that is, it can move relatively 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 movement relative 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 oscillation component of the planetary gear 3, i.e., the revolution 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 oscillation component (revolution component) of the planetary gear 3, is transmitted to the inner ring 61 by the multiple inner pins 4.

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 pressed 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 the inner pin 4 itself can rotate when it revolves within the loose fitting hole 32.

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 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 peripheral surface 321 of the loose fitting hole 32. In other words, the inner pin 4 revolves within the loose-fitting hole 32 by rolling on the inner circumferential surface 321 of the loose-fitting hole 32, so losses due to frictional resistance between the inner circumferential surface 321 of the loose-fitting hole 32 and the inner pin 4 are unlikely to occur.

In this way, 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 attached 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, making it possible to reduce the size of the planetary gear 3 (especially the diameter), and making it easier to reduce the size of the gear device 1 as a whole. If the dimensions of the planetary gear 3 are constant, it is possible to increase the number (number) of inner pins 4 to smooth the transmission of rotation, or to make the inner pins 4 thicker to improve their strength, compared to the first related technology. Furthermore, the number of parts can be reduced by the amount of the inner roller, which also leads to lower costs for the gear device 1.

In addition, in the gear device 1 according to this basic configuration, at least a portion 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. 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 multiple 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 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.

In this way, at least a portion of each of the multiple inner pins 4 is positioned at the same position as the bearing member 6 in the axial direction of the bearing member 6, so that the dimensions of the gear device 1 in the direction parallel to the rotation axis Ax1 can be kept 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 dimensions 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.

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 that is 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 restricted by the output shaft that is integrated with the inner ring 61.

In addition, 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 retention space 17 between the inner ring 61 and the outer ring 62 into which a lubricant is injected, the lubricant in the lubricant retention space 17 is used to smooth the rotation of the inner pin 4.

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 peripheral 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 peripheral 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 arranged 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.

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.

(3.3) Support Next, the configuration of the support 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 8, even in cross section. Also, Fig. 10 shows only the internal gear 2 and the support 8, and omits illustration of other parts (such as the inner pin 4). Furthermore, Fig. 10 omits illustration of the inner peripheral surface 221 of the gear body 22.

First, as a premise, the support 8 is a component that supports the multiple inner pins 4, as described above. In other words, the support 8 bundles the multiple inner pins 4 together, thereby dispersing the load on the multiple inner pins 4 when transmitting the rotation (rotation component) of the planetary gear 3 to the inner ring 61. Specifically, it has multiple support holes 82 into which the multiple inner pins 4 are inserted. 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 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. In other words, each of the multiple inner pins 4 is held in a state in which it can rotate on its own axis relative to both the inner ring 61 of the bearing member 6 and the support 8.

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 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.

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 regulated in position by contacting the outer peripheral surface 81 with the multiple outer pins 23 of the internal gear 2. The multiple outer pins 23 form the internal teeth 21 of the internal gear 2, so in other words, the support 8 is regulated in position by contacting the outer peripheral surface 81 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, when the support 8 is regulated in position by the multiple outer pins 23, the center of the support 8 is regulated in position so that it overlaps with the center (rotation axis Ax1) of the internal gear 2. This causes 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.

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, the support 8 is centered by the outer pins 23, so the support 8 rotates smoothly while the center of the support 8 is maintained on the rotation axis Ax1. Moreover, the support 8 rotates with its outer peripheral surface 81 in contact with the outer pins 23, so that 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.

In other words, 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 the two 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.

Furthermore, since the support 8 sandwiches the outer pins 23 between itself and the gear body 22, the support 8 also functions as a "stopper" that suppresses movement of the outer pins 23 away from the inner circumferential surface 221 of the gear body 22. In other words, the outer pins 23 are sandwiched between the outer circumferential surface 81 of the support 8 and the inner circumferential surface 221 of the gear body 22, suppressing lifting from the inner circumferential 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 circumferential surface 81 of the support 8, thereby restricting movement away from the gear body 22.

In this basic configuration, as shown in FIG. 9, the support 8 is located on the opposite side of the inner ring 61 of the bearing member 6 across the planetary gear 3. In other words, the support 8, planetary gear 3, and 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 has an outer ring 62 and an inner ring 61 arranged inside the outer ring 62, and is provided with 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.

According to this configuration, the support 8 and the inner ring 61 support both ends of the inner pin 4 in the longitudinal direction, 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. In addition, in this basic configuration, the support 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 8 toward the input side of the rotation axis Ax1 (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 8 and protrudes from the support 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 (left side in FIG. 9).

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 (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 (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 bending forces (bending moment loads) against the rotation axis Ax1.

The multiple outer pins 23 also have a length equal to or greater than the thickness of the support 8. In other words, in the direction parallel to the rotation axis Ax1, the support 8 fits within the range of the tooth trace of the internal teeth 21. This means that the outer peripheral surface 81 of the support 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, problems such as "uneven wear", in which the outer peripheral surface 81 of the support 8 is partially worn, are less likely to occur.

In addition, in this basic configuration, the outer peripheral surface 81 of the support 8 has a smaller surface roughness than the surface adjacent to the outer peripheral surface 81 of the support 8. 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 it is. In this basic configuration, as an example, the surface roughness is the arithmetic mean roughness (Ra). For example, by processing such as polishing, the outer peripheral surface 81 has a smaller surface roughness than the surfaces of the support 8 other than the outer peripheral surface 81. In this configuration, the support 8 rotates more smoothly.

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 or 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 less likely to be 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.

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

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

In addition, application examples of the gear device 1 and 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.

(Embodiment 1)
＜Overview＞
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 the bearing member 6A, as shown in Figures 11 to 14 etc. 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.

Figure 11 is a schematic cross-sectional view of gear device 1A. Figure 12 is a side view of gear device 1A as seen from the output side of rotation axis Ax1 (the right side of Figure 11), and Figure 11 corresponds to the cross-sectional view taken along line C1-C1 in Figure 12. Figure 13 is a cross-sectional view taken along line A1-A1 in Figure 11, and Figure 14 is a cross-sectional view taken along line B1-B1 in Figure 11 and an enlarged view of a portion thereof. However, in Figures 13 and 14, hatching has been omitted for parts other than eccentric shaft 7, even in cross-section.

In this embodiment, the bearing member 6A has an outer ring 62A, an inner ring 61A arranged inside the outer ring 62A, and a number 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 relative to the outer ring 62A around the rotation axis Ax1. This is the same as the basic configuration.

The first major difference between the gear device 1A according to this embodiment and the basic configuration is that the inner ring 61A of the bearing member 6A is not composed of one part, but is composed of two parts, a first inner ring 601 and a second inner ring 602. In other words, 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.

The second major difference from the basic configuration of the gear device 1A according to this embodiment is that the 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 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 short, the gear device 1A according to this embodiment differs from the basic configuration mainly in that it newly adopts a feature for the inner ring 61A of the bearing member 6A and a feature for the outer ring 62A of the bearing member 6A. The feature for 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 for the outer ring 62A includes that the outer ring 62 is provided seamlessly and continuously with the gear body 22.

<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 differences from the basic configuration, as described below.

As another difference, the gear device 1A according to this embodiment is used to extract the rotation equivalent to the rotation component of the planetary gear 3 as the rotation of the output shaft integrated with the 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 extracted as the rotation component of the planetary gear 3 from the inner ring 61 connected to the planetary gear 3 by multiple inner pins 4. In contrast, in this embodiment, the relative rotation between the planetary gear 3 and the internal gear 2 is extracted from the outer ring 62A integrated with the 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 multiple inner pins 4 is fixed to a fixed member (such as the hub member 104 described later) and the outer ring 62A is fixed to the case 10, which serves as a rotating member. That is, the planetary gear 3 is connected to a fixed member by multiple internal 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 internal pins 4 rotate relative to the gear body 22, the rotational force of the gear body 22 is taken as an output.

The gear device 1A, in which the rotational force of the gear body 22 is thus extracted as an output, is used, as an example, in the wheel device W1 (see FIG. 17). In this case, the rotating member (case 10) functions as the wheel body 102 (see FIG. 17), so that the wheel body 102 can be rotated in accordance with the relative rotation of 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 when the multiple inner pins 4 rotate relative 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, so that 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, the gear device 1A obtains output rotation that is reduced at a relatively high reduction ratio compared to the input rotation as the rotation of the wheel body 102.

The second difference is that the gear device 1A according to this embodiment includes multiple 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 arranged to face each other in a direction parallel to the rotation axis Ax1. In other words, the planetary gears 3 include a first planetary gear 301 and a second planetary gear 302 that face each other in a direction parallel to the rotation axis Ax1.

These two planetary gears 3 (the first planetary gear 301 and the second planetary gear 302) are arranged with a phase difference of 180 degrees around the rotation axis Ax1. In the example of FIG. 11, the center C1 of the first planetary gear 301 located on the input side of the rotation axis Ax1 (left side of FIG. 11) of the first planetary gear 301 and the second planetary gear 302 is shifted (biased) upward from the rotation axis Ax1. On the other hand, the center C2 of the second planetary gear 302 located on the output side of the rotation axis Ax1 (right side of FIG. 11) is shifted (biased) downward from 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.

More specifically, the eccentric shaft 7 has two eccentric parts 72 with respect to one axial center part 71. The centers (central axes) of these two eccentric parts 72 coincide with the centers C1 and C2, which are offset from the rotation axis Ax1. The shapes of the first planetary gear 301 and the second planetary gear 302 are the same. The opening 33 of the first planetary gear 301 accommodates 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 accommodates 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 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 eccentricity of the second planetary gear 302 with respect to the rotation axis Ax1. In this embodiment, the eccentricity amount ΔL1 and the eccentricity amount ΔL2 are in opposite directions when viewed from the rotation axis Ax1, but their absolute values are the same. According to the above-mentioned configuration, the shaft center portion 71 rotates (spins) around 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.

As another third difference, in this embodiment, as shown in Figures 13 and 14, the eccentric bearing 5 is a roller bearing instead of a deep groove ball bearing as 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 Figure 3) and the eccentric outer ring 52 (see Figure 3) are omitted. Therefore, the inner circumferential 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 circumferential 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. The retainer 54 holds the multiple rolling elements 53 at equal pitches in the circumferential direction of the eccentric portion 72. Furthermore, the retainer 54 is not fixed to the planetary gear 3 and the eccentric shaft 7, and can rotate relative to each of the planetary gear 3 and the eccentric shaft 7. As a result, as the retainer 54 rotates, the multiple rolling elements 53 held by the retainer 54 move in the circumferential direction of the eccentric portion 72.

The fourth difference is that 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. In other words, 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 the ingenuity of the outer ring 62A, the outer ring 62A, which is seamlessly connected to the gear body 22 in a direction parallel to the rotation axis Ax1, is also seamlessly connected to the case 10, which is a rotating member.

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 input side of the rotation axis Ax1 in the body 18 (left side in FIG. 11) and closes the open face of the input side of the rotation axis Ax1 in the body 18. 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 part (body 18). Therefore, the inner circumferential surface of the body 18 includes the inner circumferential surface 221 of the gear body 22 (see FIG. 14) and the inner circumferential surface 620 of the outer ring 62A (see FIG. 13).

In addition to the above, the number of teeth of the internal gear 2 and planetary gear 3, the reduction ratio, the number of loose fitting holes 32 and inner pins 4, and the specific shape and dimensions of each part are also appropriately different between this embodiment and the basic configuration. For example, while there are 18 loose fitting holes 32 and inner pins 4 in the basic configuration, there are 12 of each in this embodiment, as an example.

<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.

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 with their opposing surfaces 601A, 602A 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.

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 this embodiment, as an example, the dimension in the 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.

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 the 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.

Here, the first inner ring 601 and the second inner ring 602 are arranged so 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 so that the first inner ring 601 is on the input side of the rotation axis Ax1 (left side of FIG. 11) and the second inner ring 602 is on the output side of the rotation axis Ax1 (right side of FIG. 11). Therefore, the facing surface 601A of the first inner ring 601 with the second inner ring 602 consists of a surface of the first inner ring 601 facing the output side of the rotation axis Ax1 (right side of FIG. 11). On the other hand, the facing surface 602A of the second inner ring 602 with the first inner ring 601 consists of a surface of the second inner ring 602 facing the input side of the rotation axis Ax1 (left side of FIG. 11). The first inner ring 601 and the second inner ring 602 are combined with each other so that their opposing surfaces 601A and 602A are in contact with each other to form the inner ring 61A.

As shown in FIG. 12, the first inner ring 601 and the second inner ring 602 are joined together by a plurality of positioning pins 65 and a plurality of bolts 66 when assembled as described above. 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. 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 with their relative positions in a plane perpendicular to the rotation axis Ax1 being positioned by the plurality of positioning pins 65.

Here, in the bearing member 6A, the multiple rolling elements 63 are located on the dividing surface between 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 between 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 having an inclination of 45 degrees with respect to a plane perpendicular to the rotation axis Ax1. These multiple rolling elements 63 are located on the same plane as the opposing surface 601A of the first inner ring 601 that faces the second inner ring 602.

In this embodiment, in particular, the centers of the multiple 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 multiple 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 multiple rolling elements 63 set on 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.

In this embodiment, the oil seal 15 seals the gap between the second inner ring 602 and the eccentric shaft 7 (shaft center portion 71). Similarly, the oil seal 16 seals 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 retention space 17 (see FIG. 11) similar to the basic configuration.

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 formed between the first inner ring 601 and the second inner ring 602, even if it is small. The formation of such a gap makes it easier for the lubricant to circulate through the gap in the lubricant retention 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 retention space 17 is expected to spread through the gap, for example, by 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, even when the gear device 1A is used for a long period of time, the lubricant is more likely to spread 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.

In addition, because the inner ring 61A is divided 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 because the processing of the inner ring 61A is not complicated, 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 for a cross roller bearing.

In this embodiment, similar to the basic configuration, multiple inner pins 4 connect the planetary gear 3 and the inner ring 61A of the bearing member 6A. Specifically, one longitudinal end of the inner pin 4 (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 longitudinal end of the inner pin 4 (the end on the output side of the rotation axis Ax1) is inserted into the retaining hole 611 of the inner ring 61A.

And 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, it is prohibited from revolving within the retaining hole 611, but it 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 pressed into the retaining hole 611, and so it is 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, so that when the inner pin 4 revolves within the loose fitting hole 32, the inner pin 4 itself is able to rotate.

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. In other words, the first inner ring 601 has multiple retaining holes 611 through which multiple inner pins 4 respectively penetrate in a direction parallel to the rotation axis Ax1. The inner pins 4 are retained in 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.

In this embodiment, the inner pin 4 is not inserted into the second inner ring 602, so the second inner ring 602 does not have a retaining hole 611. Therefore, the end faces of each of the multiple inner pins 4 are 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 of 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 longitudinal end face of the inner pin 4 may be in light contact with the opposing surface 602A of the second inner ring 602 to the extent that the rotation of the inner pin 4 is not hindered, or may be separated from it. 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 prevented from leaking through the retaining hole 611.

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 multiple retaining holes 611 in the first inner ring 601 and the outer peripheral surface of each of the multiple 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 the inner pin 4 only needs to be able to 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 lubricant allows the inner pin 4 to rotate smoothly within the retaining hole 611.

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 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 multiple rolling elements 63, and each of the multiple retaining holes 611. In other words, 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. As a result, for example, the lubricant injected into the space that houses the rolling elements 63 can easily circulate along the circulation path RL1 through the gap between the first inner ring 601 and the second inner ring 602, the retaining hole 611 (the gap between the inner peripheral surface of the retaining hole 611 and the inner pin 4), and back 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.

In addition, the gear device 1A according to this embodiment satisfies the following conditions for the surface hardness of each component:

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. In other words, the surface hardness of the inner pin 4 is set to a range of ±3 in Rockwell hardness (HRC) based on the surface hardness of the first inner ring 601. Here, the difference between the surface hardness of the inner pin 4 and the surface hardness of the first inner ring 601 is preferably HRC2 or less, and more preferably HRC1 or less. The "surface hardness of the first inner ring 601" here refers to the hardness of at least the inner circumferential surface of the retaining hole 611 in the first inner ring 601. The first inner ring 601 holds the inner pin 4 in a rotatable state within the retaining hole 611, so by making the surface hardness of the inner pin 4 and the first inner ring 601 similar (difference of HRC 3 or less) as in this embodiment, it is expected that the wear of the inner pin 4 and the first inner ring 601 will be suppressed. As a result, wear powder 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.

Furthermore, the surface hardness of each of the multiple inner pins 4 is about HRC 60. More precisely, the surface hardness of each of the multiple inner pins 4 is within the range of HRC 60±3. In this embodiment, the surface hardness of the inner pin 4 and the first inner ring 601 are approximately the same (difference of HRC 3 or less), so the surface hardness of the first inner ring 601 is within the range of HRC 60±6. Here, the surface hardness of the inner pin 4 is preferably within the range of HRC 60±2, and more preferably within the range of HRC 60±1. 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, and it is easy to maintain smooth rotation of the inner pin 4 for a long period of time.

In this embodiment, the second inner ring 602 is also designed to have 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. Methods for increasing (hardening) the hardness of metal parts include, for example, alloying or heat treatment.

<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.

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 multiple parts (parts) are connected without seams, and refers to a state in which these multiple 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 adhesive, but the outer ring 62A and the gear body 22 are integrated so as to be continuous without seams.

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, 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 and continuously in a direction parallel to the rotation axis Ax1 with the gear body 22. In other words, the manufacturing method of the gear device 1A has a process of forming the outer ring 62A and the gear body 22 integrally by processing a single base material.

In this way, in the gear device 1A according to this embodiment, the outer ring 62A is provided seamlessly and continuously 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 precisely maintained on the rotation axis Ax1. As a result, the gear device 1A has the advantage that it is less susceptible to problems such as vibrations caused by poor centering and reduced transmission efficiency.

The gear body 22 and the outer ring 62A both have an annular shape that is a perfect circle in a plan view. In this embodiment, the gear body 22 and the outer ring 62A are seamlessly integrated into the body 18 of the case 10. In other words, a part of the body 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 inner diameters of the gear body 22 and the outer ring 62A are different.

Specifically, as shown in FIG. 14, a plurality of grooves are formed on the inner peripheral surface 221 of the gear body 22 in 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. The plurality of pin holding grooves 223 are all of the same shape and are provided at equal pitches. The plurality of pin holding grooves 223 are all 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 body 18 as described above, the plurality of pin holding grooves 223 are formed only in the portion of the body 18 corresponding to the gear body 22 (see FIG. 11). The plurality of outer pins 23 are combined with the gear body 22 (body 18) so as to fit into the plurality of pin holding grooves 223. Each of the multiple outer pins 23 is held in a rotatable state within the pin holding groove 223, and the pin holding groove 223 restricts movement of the gear body 22 in the circumferential direction.

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 the imaginary 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. And, 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 short, the inner diameter φ3 of the outer ring 62A is different from the diameter φ2 of the imaginary circle VC1 passing through the bottom of the plurality of pin retaining grooves 223 in which the plurality of outer pins 23 are held 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, 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.

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 virtual circle VC1 (φ3>φ2). In other words, the diameter φ2 of the virtual 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 18, a step of height D1 is generated between the bottom 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. It is preferable that the height D1 of the step is, 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, it is preferable that the height D1 of the step is 0.2 mm or more and 0.5 mm or less. This step helps prevent interference between the outer pin 23 held in the pin holding groove 223 and the inner circumferential surface 620 of the outer ring 62A.

In addition, 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).

16, a retaining recess 67 is disposed between the inner peripheral surface 620 of the outer ring 62A and the inner peripheral surface 221 of the gear body 22. The retaining recess 67 is a groove provided around the entire circumference of the outer ring 62A in the circumferential direction. The retaining recess 67 is formed to a size and shape that can retain 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 so that the gear body 22 is the input side of the rotation axis Ax1 (left side in FIG. 16), and the outer ring 62A is the output side of the rotation axis Ax1 (right side in FIG. 16). Therefore, the inner peripheral surface 221 of the gear body 22, the retaining recess 67, and the inner peripheral surface 620 of the outer ring 62A are arranged in the order of the inner peripheral surface 221 of the gear body 22, the retaining recess 67, and the inner peripheral surface 620 of the outer ring 62A from the input side of the rotation axis Ax1.

In this embodiment, as an example, as shown in FIG. 16, the retaining 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 retaining recess 67 and the width D3 of the retaining recess 67 are both greater than the height D1 of the step. It is preferable that the depth D2 and width D3 of the retaining recess 67 are at least one-tenth (φ10×1/10) and not more than 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, it is preferable that the depth D2 and width D3 of the retaining recess 67 are at least 0.25 mm and not more than 5.0 mm. In the example of FIG. 16, the depth D2 of the retaining recess 67 is greater than the width D3 of the retaining recess 67, but this is not limited to this example, and the depth D2 of the retaining 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, etc.

Here, the gear device 1A according to this embodiment further includes a lubricant path that connects from 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 bodies 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 bodies 63 through a 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 bodies 63, smoothing the movement of at least one of the inner pins 4, the outer pins 23, and the rolling bodies 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 bodies 63 through a part of the circulation path RL1 as a "lubricant" path. In particular, in this embodiment, as shown in FIG. 16, the inner pin 4, outer pin 23, and rolling element 63 are all located on the circulation path RL1, so the lubricant held in the holding recess 67 can be supplied to all of the inner pin 4, outer pin 23, and rolling element 63.

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, making it less likely that problems such as a decrease in transmission efficiency in the gear device 1A will occur.

<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 due to the rotation output generated when the multiple 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. In other words, 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.

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 uses a plurality of bolts 66 to fix the inner ring 61A (first inner ring 601 and second inner ring 602) to the hub member 104. At this time, it is preferable that the second inner ring 602 of the inner ring 61A is fixed to the hub member 104, etc.

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 eccentric body bearing 5 (the rolling body 53) and the second bearing 92, etc., around the eccentric shaft 7. In other words, a part of the lubricant circulating through the circulation path RL1 is easily supplied to the eccentric body bearing 5 and the second bearing 92, etc., through the gap between the planetary gear 3 (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 eccentric shaft 7 through the circulation path RL1, making it easier to maintain smooth rotation of the eccentric shaft 7.

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 attached to a hub member 104 provided on the vehicle body, and the wheel 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 attached to 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 around 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 body 102 is rotated with a relatively high torque.

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 on 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 to configure the outer peripheral surface 680 of the outer ring 62A so that a larger stress acts on the outer peripheral surface 680 than on 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 (oscillate) 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, compared to the gear body 22, the outer ring 62A has a structure closer to a solid structure with a filled inside, 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, which has high rigidity, can receive external stress, and the gear device 1A as a whole has high resistance to stress.

More specifically, the pressure-receiving surface (the outer peripheral surface 680 of the outer ring 62A) is subjected to stress from the outer body fitted to the outer peripheral surface of the outer ring 62A. Here, the tire 103 is an example of an outer body fitted to the outer peripheral surface of the outer ring 62A. That is, when the tire 103 is fitted 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 larger on the outer ring 62A than on the gear body 22. As a result, when the tire 103 as an outer body is fitted 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, this is not limited to the configuration in which the spacer 68 is provided. For example, the same effect can be achieved by reducing the outer diameter of the gear body 22 or by making the inner diameter of the exterior body (tire 103, etc.) smaller on the outer ring 62A side than on the gear body 22 side.

Alternatively, the gear device 1A may be configured so 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 a wheel device W1, the camber angle is adjusted so 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. In this case, the ground pressure from the ground contact surface acts on the pressure-receiving surface (the outer peripheral surface 680 of the outer ring 62A).

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.

<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 and the like, as long as the object of the present disclosure can be achieved. In addition, all 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. Below, modified examples of the first embodiment are listed. The modified examples described below can be applied in appropriate combination.

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 Figs. 18A and 18B, the inner pin 4 may be inserted into a part or all 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 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.

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, it is preferable that these three planetary gears 3 are 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.

In addition, it is not essential for the gear device 1A that at least a portion of each of the multiple inner pins 4 is positioned 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 that is positioned inside the outer ring 62A. The inner ring 61A is supported so as to be rotatable 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 positioned so as to be aligned (opposed) with the bearing member 6A in the axial direction of the bearing member 6A.

In addition, the number of inner pins 4, the number of outer pins 23 (the number of teeth of the inner teeth 21), and the number of teeth of the outer teeth 31 described in embodiment 1 are merely examples and can be changed as appropriate.

The bearing member 6A is not limited to a cross roller bearing, and may be a deep groove ball bearing or an angular ball bearing. However, it is preferable that the bearing member 6A be able to withstand radial loads, thrust loads (direction along the rotation axis Ax1), and bending forces (bending moment loads) against the rotation axis Ax1, such as a four-point contact ball bearing.

In addition, the eccentric bearing 5 is not limited to a roller bearing, but may be, for example, a deep groove ball bearing or an angular contact ball bearing.

In addition, 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.

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 it can extract the relative rotation between the inner ring 61A and the outer ring 62A of the bearing member 6A 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.

The lubricant is not limited to a liquid substance such as lubricating oil (oil), but may be a gel-like substance such as grease.

The gear device 1A may also include an inner roller. In other words, 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 can rotate around the inner pin 4 as an axis.

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 carrier that is integrated with the inner ring 61A.

In addition, 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.

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, but it is not necessary to adopt both. In other words, 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 (feature for the inner ring 61A) and that the outer ring 62A is provided seamlessly and continuously with the gear body 22 (feature for the outer ring 62A).

Furthermore, since the gear device 1A only requires the adoption 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 where it is pressed into the inner ring 61A (or a carrier integrated with the inner ring 61A) as in the first related technology, 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. In addition, 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 technology. In this case, the support body 8 can be omitted. Furthermore, even if a support 8 is provided to support (bind) multiple inner pins 4, it is not essential that the support 8 be positioned by contacting its outer circumferential surface 81 with the multiple outer pins 23, and the outer circumferential surface 81 of the support 8 may be separated from the multiple outer pins 23.

In addition, 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 for example, the inner ring 61A may be divided into three or more parts. In other words, as an 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.

The multiple holes into which the multiple positioning pins 65 are pressed 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 pressed 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, lubricant is prevented from leaking through the holes into which the positioning pins 65 are pressed.

In addition, with regard to 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. In other words, the manufacturing method of the gear device 1A only needs to include a process 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 or gluing, etc. 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.

(Embodiment 2)
As shown in Figures 19A and 19B, an internally 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. Figure 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 Figure 19A. Hereinafter, common reference numerals will be used to designate configurations similar to those of embodiment 1, and explanations thereof will be omitted as appropriate.

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, which enlarges the opening area of each of the multiple retaining holes 611. Specifically, as shown in FIG. 19A, the enlarged diameter portion 691 is formed by a chamfered portion formed on the opening periphery of the retaining hole 611 on the input side (left side of 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) 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), and may be, for example, a curved R-shaped surface or a stepped countersink shape.

By forming such an enlarged diameter portion 691, at least on the opening surface of each of the multiple retaining holes 611 opposite the second inner ring 602, the gap between the inner pin 4 is enlarged. As a result, the gap between the inner peripheral surface of the retaining hole 611 and the inner pin 4 created by the enlarged diameter portion 691 functions as an "oil reservoir" for storing lubricant (lubricating oil). Since the enlarged diameter portion 691 is continuous with the retaining hole 611, the lubricant stored in the enlarged 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.

Furthermore, the enlarged diameter portion 691 as an "oil reservoir" is located on the lubricant circulation path RL1 as shown in FIG. 20. Therefore, by using a portion 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 element 63 other than the inner pin 4. In particular, in this embodiment, as shown in FIG. 20, since both the outer pin 23 and the rolling element 63 are located on the circulation path RL1, the lubricant held in the enlarged diameter portion 691 can be supplied to both the outer pin 23 and the rolling element 63.

In this embodiment, as shown in FIG. 19A and FIG. 19B, a connecting groove 692 is formed on 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 the space that houses each of the multiple rolling elements 63 to each of the multiple retaining holes 611. That is, the connecting groove 692 is provided on at least one of the opposing surfaces 601A and 602A, which are the dividing surfaces of the first inner ring 601 and the second inner ring 602, and connects the 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, a connecting groove 692 is formed on 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 a connecting groove 692 is formed corresponding to all of the retaining holes 611.

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-sectional shape perpendicular to the radial direction of the inner ring 61A. It is preferable that the depth D4 (from the opposing surface 601A) of the connecting groove 692 and the width D5 of the connecting groove 692 are 1/10 (φ10×1/10) or more and 2 times (φ10×2) or less of 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, it is preferable that the depth D4 and width D5 of the connecting groove 692 are 0.25 mm or more and 5.0 mm or less. In the example of FIG. 20, the depth D4 of the connecting groove 692 is smaller than the width D5 of the connecting groove 692, but this is not limited to the example, and the depth D4 of the connecting groove 692 may be equal to or greater 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.

The provision of such a connecting groove 692 makes it easier for the lubricant to circulate through the lubricant retention space 17. In particular, the connecting groove 692 is connected to the space that houses the rolling element 63 between the inner ring 61A and the outer ring 62A. 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 more easily circulated, and even when the gear device 1B is used for a long period of time, the lubricant is more likely to permeate the entire lubricant retention space 17, making it less likely that problems such as a decrease in transmission efficiency in the gear device 1B will occur.

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 element 63. In other words, the space between the oil seal 16 and the rolling element 63 is connected to the retaining hole 611 by the connecting groove 692, and the space between the oil seal 16 and the rolling element 63 is expanded, which leads to suppression of an increase in internal pressure when the rolling element 63 functions as a pump. As a result of suppressing an increase in internal pressure in the lubricant retaining space 17, for example, leakage of the lubricant beyond the oil seal 16 is less likely to occur.

As a modification of the second embodiment, the connecting groove 692 may be formed on the opposing surfaces 601A, 602A of both the first inner ring 601 and the second inner ring 602. Also, the connecting groove 692 may be formed only on the opposing surface 602A of the second inner ring 602.

As another variation of the second embodiment, the enlarged diameter portion 691 and the connecting groove 692 may be employed separately. That is, the gear device 1B may have only the enlarged diameter portion 691 of the enlarged diameter portion 691 and the connecting groove 692, or, conversely, may have only the connecting groove 692.

The configuration of embodiment 2 (including modifications) can be applied in appropriate combination with the configuration described in embodiment 1 (including modifications).

(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) includes an annular gear body (22) and a plurality of outer pins (23) that are held on the inner peripheral surface (221) of the gear body (22) in a rotatable state and form the internal teeth (21). 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 relatively to the internal gear (2) while revolving within the loose fitting holes (32). The outer rings (62, 62A) are provided seamlessly continuous with the gear body (22) in a direction parallel to the rotation axis (Ax1).

According to this aspect, it becomes easier to improve the accuracy of centering between the internal gear (2) and the bearing member (6, 6A). In other words, the center of the gear body (22) of the internal gear (2) and the center of the outer ring (62, 62A) of the bearing member (6, 6A) are more likely to be accurately maintained on the rotation axis (Ax1). As a result, the internally meshing planetary gear device (1, 1A, 1B) has the advantage that it is less likely to suffer from problems such as vibrations caused by poor centering and reduced transmission efficiency.

In the internally meshing planetary gear device (1, 1A, 1B) according to the second aspect, in the first aspect, the inner diameter (φ3) of the outer ring (62, 62A) is different from the diameter (φ2) of the imaginary circle (VC1). The imaginary circle (VC1) is an imaginary circle that passes through the bottoms of the multiple pin retaining grooves (223) in which the multiple outer pins (23) are retained on the inner circumferential surface (221) of the gear body (22).

In this embodiment, the gear body (22) and the outer ring (62, 62A) are seamlessly connected, but the difference in their inner diameters makes it easier to clearly separate the functions of the gear body (22) and the outer ring (62, 62A).

In the internally meshing planetary gear device (1, 1A, 1B) according to the third aspect, in the second aspect, the inner diameter (φ3) of the outer ring (62, 62A) is larger than the diameter (φ2) of the imaginary circle (VC1).

According to this embodiment, interference between the outer pin (23) held on the inner peripheral surface (221) of the gear body (22) and the inner peripheral surface (620) of the outer ring (62, 62A) can be avoided.

In the internally meshing planetary gear device (1, 1A, 1B) according to the fourth aspect, in any of the first to third aspects, a retaining recess (67) is disposed between the inner peripheral surface (620) of the outer ring (62, 62A) and the inner peripheral surface (221) of the gear body (22).

According to this embodiment, the retaining recess (67) functions as an "oil reservoir" for storing the lubricant, making it difficult for the lubricant to run out.

The internally meshing planetary gear device (1, 1A, 1B) according to the fifth aspect 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).

According to this embodiment, the lubricant held in the holding recess (67) is supplied to at least one of the inner pin (4), the outer pin (23), and the rolling element (63), making their movement smooth.

In the sixth embodiment of the internally meshing planetary gear device (1, 1A, 1B), in any of the first to fifth embodiments, the outer peripheral surface (680) of the outer ring (62, 62A) constitutes a pressure-receiving surface that receives a large stress compared to the outer peripheral surface (224) of the gear body (22).

According to this embodiment, the outer ring (62, 62A) side, which has high rigidity, can bear external stress, and the internal meshing planetary gear device (1, 1A, 1B) as a whole has high resistance to stress.

In the seventh embodiment of the internally meshing planetary gear device (1, 1A, 1B), in the sixth embodiment, stress acts on the pressure-receiving surface from the exterior body that is fitted to the outer periphery of the outer ring (62, 62A).

According to this embodiment, when an exterior body is fitted to the outer periphery of the outer ring (62, 62A), the stress from the exterior body can be received by the outer ring (62, 62A) side, which has high rigidity, and the internal meshing planetary gear device (1, 1A, 1B) as a whole has high resistance to stress.

In the internally meshing planetary gear device (1, 1A, 1B) according to the eighth aspect, in any of the first to seventh aspects, each of the multiple inner pins (4) is held in the inner ring (61, 61A) in a rotatable state.

According to this embodiment, each of the multiple inner pins (4) is held in the inner ring (61, 61A) in a rotatable state, so that the inner pins (4) themselves can rotate when they revolve within the loose fitting hole (32). Therefore, even without using an inner roller that is attached to the inner pin (4) and can rotate around the inner pin (4), it is possible to reduce loss due to frictional resistance between the inner peripheral surface (321) of the loose fitting hole (32) and the inner pin (4). Therefore, there is an advantage that an inner roller is not required and it is easy to make the device smaller.

In the internally meshing planetary gear device (1, 1A, 1B) according to the ninth aspect, in any of the first to eighth aspects, the inner ring (61, 61A) includes a first inner ring (601) and a second inner ring (602) that face each other in a direction parallel to the rotation axis (Ax1). The first inner ring (601) has a plurality of retaining holes (611) through which the plurality of inner pins (4) respectively pass in a direction parallel to the rotation axis (Ax1).

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

The internally meshing planetary gear device (1, 1A, 1B) according to the tenth aspect is the same as the ninth aspect, but 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 space that houses each of the multiple rolling elements (63), and each of the multiple retaining holes (611).

This aspect makes it easier for the lubricant to circulate through the rolling elements (63) and the inner pin (4).

In the internally meshing planetary gear device (1, 1A, 1B) according to the eleventh aspect, in any of the first to tenth aspects, the planetary gear (3) includes a first planetary gear (301) and a second planetary gear (302) that face each other in a direction parallel to the rotation axis (Ax1).

According to this embodiment, by balancing the weight between the first planetary gear (301) and the second planetary gear (302), it is easy to suppress problems such as the generation of vibrations and a decrease in transmission efficiency.

The manufacturing method of the internally meshing planetary gear device (1, 1A, 1B) according to the twelfth aspect is a manufacturing method of the internally meshing planetary gear device (1, 1A, 1B) including a bearing member (6, 6A), an internal gear (2), a planetary gear, and a plurality of internal pins (4). The bearing member (6, 6A) has an outer ring (62, 62A) and an inner ring (61, 61A) arranged inside the outer ring (62, 62A), 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 an annular gear body (22) and a plurality of external pins (23) that are held on the inner peripheral surface of the gear body (22) in a rotatable state and form internal teeth. The planetary gear has external teeth that partially mesh with the internal teeth. The multiple inner pins (4) are inserted into multiple loose fitting holes (32) formed in the planetary gear, and rotate relative to the internal gear (2) while revolving within the loose fitting holes (32). The manufacturing method includes a process of integrally forming the outer ring (62, 62A) and the gear body (22) by processing a single base material.

According to this aspect, it becomes easier to improve the accuracy of centering between the internal gear (2) and the bearing member (6, 6A). In other words, the center of the gear body (22) of the internal gear (2) and the center of the outer ring (62, 62A) of the bearing member (6, 6A) are more likely to be accurately maintained on the rotation axis (Ax1). As a result, the internally meshing planetary gear device (1, 1A, 1B) has the advantage that it is less likely to suffer from problems such as vibrations caused by poor centering and reduced transmission efficiency.

Reference Signs List 1, 1A, 1B Internally meshing planetary gear device 2 Internal gear 3 Planetary gear 4 Inner pin 6, 6A Bearing member 21 Internal teeth 22 Gear body 23 External pin 31 External teeth 32 Loose fitting hole 61, 61A Inner ring 62, 62A Outer ring 63 Rolling element 67 Retaining recess 103 Tire (outer body)
221 Inner peripheral surface (of gear body) 223 Pin retaining groove 224 Outer peripheral surface (of gear body) 301 First planetary gear 302 Second planetary gear 601 First inner ring 602 Second inner ring 611 Retaining hole 620 Inner peripheral surface (of outer ring) 680 Outer peripheral surface (pressure receiving surface) (of outer ring)
Ax1 Rotating shaft RL1 Circulation path VC1 Virtual circle φ2 Diameter (of virtual circle) φ3 Inner diameter (of outer ring)

Claims (9)

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 including an annular gear body and a plurality of outer pins that are rotatably held on an inner peripheral surface of the gear body and form internal teeth;
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 outer ring is provided seamlessly continuous with the gear body in a direction parallel to the rotation shaft,
an inner diameter of the outer ring is different from a diameter of an imaginary circle passing through bottoms of a plurality of pin retaining grooves in which the plurality of outer pins are retained on the inner circumferential surface of the gear body,
The inner diameter of the outer ring is larger than the diameter of the imaginary circle.
Internally meshing planetary gear set. 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 including an annular gear body and a plurality of outer pins that are rotatably held on an inner peripheral surface of the gear body and form internal teeth;
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 relatively to the internal gear while revolving within the loose-fitting holes,
the outer ring is provided seamlessly continuous with the gear body in a direction parallel to the rotation shaft,
A retaining recess is disposed between the inner peripheral surface of the outer ring and the inner peripheral surface of the gear body.
Internally meshing planetary gear set. a lubricant path extending from the retaining recess to at least one of each of the inner pins, each of the outer pins, and each of the rolling elements;
3. The internal meshing planetary gear device according to claim 2 . 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 including an annular gear body and a plurality of outer pins that are rotatably held on an inner peripheral surface of the gear body and form internal teeth;
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 relatively to the internal gear while revolving within the loose-fitting holes,
the outer ring is provided seamlessly continuous with the gear body in a direction parallel to the rotation shaft,
The outer peripheral surface of the outer ring constitutes a pressure-receiving surface that receives a large stress compared to the outer peripheral surface of the gear body.
Internally meshing planetary gear set. A stress is applied to the pressure-receiving surface from an exterior body fitted onto an outer periphery of the outer ring.
5. The internal meshing planetary gear device according to claim 4 . Each of the plurality of inner pins is held by the inner ring in a rotatable state.
The internal meshing planetary gear device according to any one of claims 1 to 5 . 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 including an annular gear body and a plurality of outer pins that are rotatably held on an inner peripheral surface of the gear body and form internal teeth;
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 relatively to the internal gear while revolving within the loose-fitting holes,
the outer ring is provided seamlessly continuous with the gear body in a direction parallel to the rotation shaft,
The inner ring includes a first inner ring and a second inner ring opposed to each other in a direction parallel to the rotation shaft,
the first inner ring has a plurality of retaining holes through which the plurality of inner pins respectively pass in a direction parallel to the rotation shaft,
a circulation path for a lubricant passing through at least a gap between the first inner ring and the second inner ring, a space for accommodating each of the plurality of rolling elements, and each of the plurality of retaining holes,
Internally meshing planetary gear set. The planetary gears include a first planetary gear and a second planetary gear opposed to each other in a direction parallel to the rotation shaft.
The internal meshing planetary gear device according to any one of claims 1 to 7 . a bearing member having an outer ring and an inner ring disposed inside the outer ring, the inner ring being supported so as to be rotatable relative to the outer ring about a rotation axis;
an internal gear including an annular gear body and a plurality of outer pins that are rotatably held on an inner peripheral surface of the gear body and form internal teeth;
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 relatively to the internal gear while revolving within the loose-fitting holes ,
an inner diameter of the outer ring is different from a diameter of an imaginary circle passing through bottoms of a plurality of pin retaining grooves in which the plurality of outer pins are retained on the inner circumferential surface of the gear body,
An inner diameter of the outer ring is larger than a diameter of the imaginary circle,
The method includes a step of integrally forming the outer ring and the gear body by processing a single base material.
A method for manufacturing an internally meshing planetary gear device.