CN118208527A

CN118208527A - Gear device and method for manufacturing gear device

Info

Publication number: CN118208527A
Application number: CN202211627601.6A
Authority: CN
Inventors: 其轮宪一
Original assignee: Guangdong Jiya Jingji Technology Co ltd; Midea Group Co Ltd; GD Midea Air Conditioning Equipment Co Ltd
Current assignee: Guangdong Jiya Jingji Technology Co ltd; Midea Group Co Ltd; GD Midea Air Conditioning Equipment Co Ltd
Priority date: 2022-12-16
Filing date: 2022-12-16
Publication date: 2024-06-18
Also published as: WO2024124998A1; JP2024086522A

Abstract

The invention provides a gear device and a manufacturing method of the gear device, which can easily realize light weight while maintaining strength. The gear arrangement includes a first gear and a second gear. The second gear rotates relative to the first gear by meshing with the first gear. The first gear has a skeleton portion (225) and a coating layer (224) having a specific gravity greater than that of the skeleton portion (225). At least the sliding contact portion with the other member in the skeleton portion (225) is covered with a coating layer (224).

Description

Gear device and method for manufacturing gear device

Technical Field

The present disclosure relates generally to a gear device and a method of manufacturing a gear device, and more particularly, to a gear device including a first gear and a second gear that rotates relative to the first gear, and a method of manufacturing a gear device.

Background

As a related art, a gear device (power transmission device) having a sliding portion in which a pair of sliding members slide each other is known (for example, see patent document 1). The gear device is an internally-tangent swing-meshing planetary gear device, and includes an input shaft, an eccentric body integrated with the input shaft, an external gear that swings and rotates by the eccentric body, an internal gear that includes internal teeth that are internally meshed with the external gear, and a flange body that is disposed axially outside the external gear and is coupled to an internal pin that takes out a rotation component of the external gear.

In the gear device, for example, at least one of the two end holding surfaces of the outer pin forming the internal teeth and the 2 opposed sliding surfaces of the pair of sliding members, such as the surfaces opposed to the two end holding surfaces of the outer pin, has a surface roughness formed by a predetermined roughness processing and a carbon-based coating film. The carbon-based coating film is formed on the surface roughness with a metal element added thereto.

Prior art literature

Patent literature

Patent document 1: japanese patent laid-open No. 2009-41747

Disclosure of Invention

Technical problem to be solved by the invention

In the related art, for example, a base material of a sliding member such as a first gear (internal gear) is made of metal, and in order to perform roughness processing, a corresponding thickness is required, and a weight ratio is relatively large. Therefore, the weight reduction of the entire wheel device may be hindered.

The purpose of the present disclosure is to provide a gear device and a method for manufacturing a gear device, which can easily achieve weight reduction while maintaining strength.

Solution for solving the technical problems

A gear device of an aspect of the present disclosure includes a first gear and a second gear. The second gear is engaged with the first gear to rotate relative to the first gear. The first gear has a skeleton portion and a coating layer having a larger specific gravity than the skeleton portion. At least a sliding contact portion of the skeleton portion, which is in sliding contact with the other member, is covered with the coating layer.

A method of manufacturing a gear device according to an aspect of the present disclosure is a method of manufacturing a gear device, including a plating step of forming the coating layer by plating at least a part of the skeleton portion of the first gear.

Effects of the invention

According to the present disclosure, it is possible to provide a gear device and a method of manufacturing the gear device that can easily achieve weight reduction while maintaining strength.

Drawings

Fig. 1 is a perspective view showing a schematic configuration of an actuator including a ring gear device according to the first embodiment.

Fig. 2 is a schematic exploded perspective view of the ring gear device as described above, as seen from the output side of the rotary shaft.

Fig. 3 is a schematic cross-sectional view of the ring gear device.

Fig. 4 is a sectional view taken along line A1-A1 of fig. 3 showing the ring gear apparatus described above.

Fig. 5A is a perspective view of a planetary gear of the ring gear device described above, shown as a single body.

Fig. 5B is a front view of the planetary gear showing the ring gear device in a single body.

Fig. 6A is a perspective view showing the bearing member of the ring gear device described above in a single body.

Fig. 6B is a front view showing the bearing member of the ring gear apparatus described above in a single body.

Fig. 7A is a perspective view showing the eccentric shaft of the ring gear device described above in a single body.

Fig. 7B is a front view showing the eccentric shaft of the ring gear device described above in a single body.

Fig. 8A is a perspective view showing the carrier of the ring gear device in a single body.

Fig. 8B is a front view of the carrier of the ring gear device shown in a single body.

Fig. 9 is an enlarged view of a region Z1 of fig. 3 showing the ring gear device described above.

Fig. 10 is a sectional view taken along line B1-B1 of fig. 3 showing the ring gear apparatus described above.

Fig. 11 is a schematic cross-sectional view showing the meshing portion between the internal teeth 21 and the external teeth 31 of fig. 9 in an enlarged manner in the ring gear device.

Fig. 12 is a schematic view of the line A1-A1 of fig. 11 showing the ring gear device.

Fig. 13A is a schematic perspective view showing an inner peripheral groove of the internal gear of the ring gear device.

Fig. 13B is a schematic perspective view showing the inner peripheral groove of the internal gear of the ring gear device.

Fig. 14 is a perspective view showing a schematic configuration of a ring gear planetary gear device according to the second embodiment.

Fig. 15 is an exploded perspective view of the ring gear device as described above, as seen from the input side of the rotary shaft.

Fig. 16 is a schematic cross-sectional view of the ring gear device.

Fig. 17 is a cross-sectional view showing a schematic configuration of a harmonic gear device according to a first comparative example of the third embodiment.

Fig. 18 is a schematic view of the harmonic gear device as described above, as viewed from the input side of the rotary shaft.

Fig. 19 is a schematic exploded perspective view of the harmonic gear device as described above, as seen from the output side of the rotary shaft.

Fig. 20 is a schematic exploded perspective view of the harmonic gear device as described above, as seen from the input side of the rotary shaft.

Detailed Description

Embodiment one

(1) Summary of the inventionsummary

The outline of the ring gear planetary gear device 1 according to the present embodiment will be described below with reference to fig. 1 to 3. The drawings to which the embodiments of the present disclosure refer are schematic drawings, and the respective ratios of the sizes and thicknesses of the respective constituent elements in the drawings do not necessarily reflect actual dimensional ratios. For example, the tooth shapes, sizes, and numbers of teeth of the internal teeth 21 and the external teeth 31 in fig. 1 to 3 are shown schematically for the sake of illustration, and the gist thereof is not limited to the illustrated shape.

The ring gear planetary gear device (hereinafter, also simply referred to as "gear device 1") of the present embodiment is a gear device including an internal gear 2, a planetary gear 3, and a plurality of internal pins 4. In the gear device 1, the planetary gear 3 is disposed inside the ring-shaped internal gear 2, and the eccentric body bearing 5 is disposed inside the planetary gear 3. The eccentric body bearing 5 includes an eccentric body inner ring 51 and an eccentric body outer ring 52, and the eccentric body inner ring 51 swings by rotating (eccentrically moving) about a rotation axis Ax1 (see fig. 3) that is offset from a center C1 (see fig. 3) of the eccentric body inner ring 51. The eccentric body inner ring 51 rotates (eccentric motion) around the rotation axis Ax1 by, for example, rotation of the eccentric shaft 7 inserted into the eccentric body inner ring 51. The ring gear device 1 further includes a bearing member 6, and the bearing member 6 has an outer ring 62 and an inner ring 61. The inner race 61 is disposed inside the outer race 62 and is supported so as to be rotatable relative to the outer race 62.

The internally toothed gear 2 has internal teeth 21 and is fixed to the outer ring 62. In particular, in the present embodiment, the internal gear 2 has an annular gear body 22 and a plurality of pins 23. The plurality of pins 23 are rotatably held by the inner peripheral surface 221 of the gear body 22 to constitute the internal teeth 21. The planetary gear 3 has external teeth 31 that partially mesh with the internal teeth 21. That is, the planetary gear 3 is inscribed in the internal gear 2 inside the internal gear 2, and a part of the external teeth 31 meshes with a part of the internal teeth 21. In this state, when the eccentric shaft 7 rotates, the planetary gear 3 swings, the meshing position of the internal teeth 21 and the external teeth 31 moves in the circumferential direction of the internal gear 2, and relative rotation corresponding to the difference in the number of teeth of the planetary gear 3 and the internal gear 2 occurs between the two gears (the internal gear 2 and the planetary gear 3). Here, if the internal gear 2 is fixed, the planetary gear 3 rotates (rotates) with the relative rotation of the two gears. As a result, a rotational output is obtained from the planetary gear 3, which is decelerated at a relatively high reduction ratio in accordance with the difference in the number of teeth between the two gears.

This gear device 1 is used in the following manner: the rotation of the planetary gear 3 corresponding to the rotation component is taken out as, for example, the rotation of the output shaft integrated with the inner ring 61 of the bearing member 6. Thus, the gear device 1 functions as a gear device having a relatively high reduction ratio, with the eccentric shaft 7 as an input side and the output shaft as an output side. Therefore, in the gear device 1 of the present embodiment, the planetary gears 3 and the inner ring 61 are coupled by the plurality of inner pins 4 in order to transmit the rotation corresponding to the rotation component of the planetary gears 3 to the inner ring 61 of the bearing member 6. The plurality of inner pins 4 are inserted into the plurality of inner pin holes 32 formed in the planetary gear 3, and rotate relative to the internal gear 2 while revolving around the inner pin holes 32. That is, the inner pin hole 32 has a larger diameter than the inner pin 4, and the inner pin 4 is movable so as to revolve in the inner pin hole 32 while being inserted into the inner pin hole 32. The swinging component of the pinion 3, that is, the revolution component of the pinion 3 is absorbed by the loose fitting of the inner pin hole 32 of the pinion 3 and the inner pin 4. In other words, the plurality of inner pins 4 move so as to revolve within the plurality of inner pin holes 32, respectively, thereby absorbing the swinging component of the planetary gear 3. Therefore, the rotation (rotation component) of the pinion gear 3, in addition to the swing component (revolution component) of the pinion gear 3, is transmitted to the inner race 61 of the bearing member 6 by the plurality of inner pins 4.

However, in this gear device 1, since the rotation of the planetary gear 3 is transmitted to the plurality of inner pins 4 while the inner pins 4 revolve in the inner pin holes 32 of the planetary gear 3, a technique using an inner roller that is attached to the inner pins 4 and is rotatable about the inner pins 4 is known as a first related technique. That is, in the first related art, the inner pin 4 is held in a state of being pressed into the inner ring 61 (or a bracket integral with the inner ring 61), and when the inner pin 4 revolves in the inner pin hole 32, the inner pin 4 slides with respect to the inner peripheral surface 321 of the inner pin hole 32. Therefore, as the first related art, an inner roller is used in order to reduce the loss due to the frictional resistance between the inner peripheral surface 321 of the inner pin hole 32 and the inner pin 4. However, in the case of the first related art including the inner roller, the inner pin hole 32 needs to have a diameter that enables the inner pin 4 with the inner roller to revolve, and downsizing of the inner pin hole 32 is difficult. When the miniaturization of the inner pin hole 32 is difficult, the miniaturization (particularly, the reduction in diameter) of the planetary gear 3 is hindered, and even the miniaturization of the entire gear device 1 is hindered. The gear device 1 of the present embodiment can provide the ring gear planetary gear device 1 that is easily miniaturized by the following configuration.

That is, as shown in fig. 1 to 3, the gear device 1 of the present embodiment includes a bearing member 6, an internal gear 2, a planetary gear 3, and a plurality of internal pins 4. The bearing member 6 has an outer ring 62 and an inner ring 61 disposed inside the outer ring 62. The inner race 61 is supported rotatably relative to the outer race 62. The internally toothed gear 2 has internal teeth 21 and is fixed to the outer ring 62. The planetary gear 3 has external teeth 31 that partially mesh with the internal teeth 21. The plurality of inner pins 4 are inserted into the plurality of inner pin holes 32 formed in the planetary gear 3, and rotate relative to the internal gear 2 while revolving around the inside of the inner pin holes 32. Here, each of the plurality of inner pins 4 is rotatably held by the inner ring 61. Further, each of the plurality of inner pins 4 positions at least a part at the same position as the bearing member 6 in the axial direction of the bearing member 6.

According to this embodiment, since each of the plurality of inner pins 4 is held by the inner ring 61 in a rotatable state, the inner pin 4 itself can rotate when revolving in the inner pin hole 32. Therefore, even if an inner roller that is attached to the inner pin 4 and is rotatable about the inner pin 4 is not used, loss due to frictional resistance between the inner peripheral surface 321 of the inner pin hole 32 and the inner pin 4 can be reduced. Therefore, the gear device 1 of the present embodiment has an advantage that the inner roller is not necessary, and thus the size can be easily reduced. Further, since the plurality of inner pins 4 each have at least a part thereof disposed at the same position as the bearing member 6 in the axial direction of the bearing member 6, the size of the gear device 1 in the axial direction of the bearing member 6 can be suppressed to be small. That is, in the gear device 1 of the present embodiment, the size of the gear device 1 in the axial direction can be reduced, and further downsizing (thinning) of the gear device 1 can be contributed to, as compared with a structure in which the bearing member 6 and the inner pin 4 are juxtaposed (opposed) in the axial direction of the bearing member 6.

Further, if the size of the planetary gear 3 is the same as the first related art, the number (number) of the inner pins 4 may be increased, for example, to smooth the transmission of rotation or the inner pins 4 may be thickened to increase the strength, as compared with the first related art.

In this gear device 1, since the inner pins 4 need to revolve in the inner pin holes 32 of the planetary gears 3, there is a case where a plurality of inner pins 4 are held only by the inner ring 61 (or a bracket integral with the inner ring 61) as a second related art. According to the second related art, it is difficult to improve the accuracy of centering the plurality of inner pins 4, and there is a possibility that occurrence of vibration, degradation of transmission efficiency, and the like may occur due to poor centering. That is, the plurality of inner pins 4 rotate relative to the internal gear 2 while revolving around the inner pin holes 32, respectively, thereby transmitting the rotation component of the planetary gear 3 to the inner ring 61 of the bearing member 6. At this time, if the rotation axes of the plurality of inner pins 4 are deviated or inclined with respect to the rotation axis of the inner ring 61 due to insufficient accuracy of centering of the plurality of inner pins 4, the centering becomes poor, and thus, there is a possibility that defects such as occurrence of vibration and degradation of transmission efficiency may occur. The gear device 1 of the present embodiment can provide the ring gear planetary gear device 1 in which a problem caused by a poor centering of the plurality of inner pins 4 is less likely to occur, by the following configuration.

That is, as shown in fig. 1 to 3, the gear device 1 of the present embodiment includes an internal gear 2, a planetary gear 3, a plurality of internal pins 4, and a support body 8. The internal gear 2 has an annular gear body 22 and a plurality of pins 23. The plurality of pins 23 are rotatably held by the inner peripheral surface 221 of the gear body 22 to constitute the internal teeth 21. The planetary gear 3 has external teeth 31 that partially mesh with the internal teeth 21. The plurality of inner pins 4 are inserted into the plurality of inner pin holes 32 formed in the planetary gear 3, and rotate relative to the gear body 22 while revolving around the inside of the inner pin holes 32. The support body 8 is annular and supports the plurality of inner pins 4. Here, the support body 8 is position-restricted by bringing the outer peripheral surface 81 into contact with the plurality of pins 23.

According to this aspect, since the plurality of inner pins 4 are supported by the annular support body 8, the plurality of inner pins 4 are bundled by the support body 8, and relative displacement and inclination of the plurality of inner pins 4 can be suppressed. The outer peripheral surface 81 of the support body 8 is in contact with the plurality of pins 23, and thereby the position of the support body 8 is restricted. In short, the support body 8 is centered by the plurality of pins 23, and as a result, the plurality of inner pins 4 supported by the support body 8 are also centered by the plurality of pins 23. Therefore, according to the gear device 1 of the present embodiment, it is easy to improve the accuracy of centering the plurality of inner pins 4, and there is an advantage that it is difficult to generate a problem caused by poor centering of the plurality of inner pins 4.

As shown in fig. 1, the gear device 1 of the present embodiment forms an actuator 100 together with a drive source 101. In other words, the actuator 100 of the present embodiment includes the gear device 1 and the drive source 101. The drive source 101 generates a drive force for swinging the planetary gear 3. Specifically, the driving source 101 rotates the eccentric shaft 7 around the rotation axis Ax1, thereby swinging the planetary gear 3.

(2) Definition of the definition

The "annular shape" in the present disclosure means a shape such as a ring (loop) forming a space (region) surrounded on the inside at least in a plan view, and is not limited to a circular shape (annular shape) which is a perfect circle in a plan view, and may be, for example, an elliptical shape, a polygonal shape, or the like. Further, for example, even if the cup-like shape has a bottom, the ring-like shape is included in the "ring-like shape" as long as the peripheral wall thereof is annular.

The term "fitting" as used in the present disclosure means a state in which the pin is fitted with play (clearance), and the inner pin hole 32 is a hole in which the inner pin 4 is fitted. That is, the inner pin 4 is inserted into the inner pin hole 32 in a state where a margin (gap) of space is secured between the inner pin and the inner peripheral surface 321 of the inner pin hole 32. In other words, the diameter of at least the portion of the inner pin 4 inserted into the inner pin hole 32 is smaller (thinner) than the diameter of the inner pin hole 32. Therefore, the inner pin 4 is movable within the inner pin hole 32 in a state of being inserted into the inner pin hole 32, that is, is movable relatively with respect to the center of the inner pin hole 32. Thereby, the inner pin 4 can revolve in the inner pin hole 32. However, a gap as a cavity is not necessarily secured between the inner peripheral surface 321 of the inner pin hole 32 and the inner pin 4, and for example, a fluid such as a liquid may be filled in the gap.

The term "revolution" as used in the present disclosure means a rotation of an object around a rotation axis other than a central axis passing through the center (center of gravity) of the object, and when the object revolves, the center of the object moves along a revolution orbit centered on the rotation axis. Therefore, for example, when a certain object rotates around an eccentric shaft parallel to a central axis passing through the center (center of gravity) of the object, the object revolves around the eccentric shaft as a rotation axis. As an example, the inner pin 4 revolves around the inner pin hole 32 around a rotation shaft passing through the center of the inner pin hole 32.

In the present disclosure, one side (left side in fig. 3) of the rotation shaft Ax1 is referred to as an "input side", and the other side (right side in fig. 3) of the rotation shaft Ax1 is referred to as an "output side". In the example of fig. 3, rotation is imparted to the rotating body (eccentric body inner ring 51) from the "input side" of the rotating shaft Ax1, and rotation of the plurality of inner pins 4 (inner ring 61) is extracted from the "output side" of the rotating shaft Ax 1. However, the "input side" and the "output side" are labels given for the sake of explanation, and the gist of the labels is not limited to the positional relationship between input and output as seen from the gear device 1.

The term "rotation axis" as used in the present disclosure means an axis (straight line) which becomes a virtual center of a rotational motion of a rotating body. That is, the rotation axis Ax1 is a virtual axis not accompanied with an entity. The eccentric body inner ring 51 rotates around the rotation axis Ax 1.

The "internal teeth" and "external teeth" referred to in the embodiments of the present disclosure refer to a set (group) of a plurality of "teeth" rather than individual "teeth", respectively. That is, the internal teeth 21 of the internal gear 2 are formed of a collection of a plurality of teeth arranged on the inner peripheral surface 221 of the internal gear 2 (the gear body 22). Similarly, the external teeth 31 of the planetary gear 3 are formed by a plurality of teeth arranged on the outer peripheral surface of the planetary gear 3.

(3) Structure of the

The following describes the detailed configuration of the ring gear planetary gear device 1 according to the present embodiment with reference to fig. 1 to 8B.

Fig. 1 is a perspective view showing a schematic configuration of an actuator 100 including a gear device 1. In fig. 1, a driving source 101 is schematically shown. Fig. 2 is a schematic exploded perspective view of the gear device 1 as seen from the output side of the rotation shaft Ax 1. Fig. 3 is a schematic cross-sectional view of the gear device 1. Fig. 4 is a sectional view taken along line A1-A1 of fig. 3. In fig. 4, the parts other than the eccentric shaft 7 are also cross-sectioned but cross-sectioned. Further, in fig. 4, the inner peripheral surface 221 of the gear main body 22 is omitted from illustration. Fig. 5A and 5B are a perspective view and a front view showing the planetary gear 3 in a single body. Fig. 6A and 6B are a perspective view and a front view showing the bearing member 6 in a single body. Fig. 7A and 7B are a perspective view and a front view showing the eccentric shaft 7 in a single body. Fig. 8A and 8B are a perspective view and a front view of the support body 8 shown in a single body.

(3.1) Integral Structure

As shown in fig. 1 to 3, the gear device 1 of the present embodiment includes an internal gear 2, a planetary gear 3, a plurality of internal pins 4, an eccentric body bearing 5, a bearing member 6, an eccentric shaft 7, and a support body 8. In the present embodiment, the gear device 1 further includes a first bearing 91, a second bearing 92, and a housing 10. In the present embodiment, the internal gear 2, the planetary gear 3, the plurality of internal pins 4, the eccentric body bearing 5, the bearing member 6, the eccentric shaft 7, the support body 8, and the like, which are constituent elements of the gear device 1, are made of stainless steel, cast iron, carbon steel for machine construction, chrome molybdenum steel, phosphor bronze, aluminum bronze, or other metal, or aluminum, titanium, or other light metal. The metal (including light metal) herein includes a metal subjected to surface treatment such as nitriding treatment. In the present embodiment, the gear body 22 of the internal gear 2 is made of aluminum, as an example in particular.

In the present embodiment, an internally toothed planetary gear reducer using cycloid tooth profiles is exemplified as an example of the gear device 1. That is, the gear device 1 of the present embodiment includes the internal-contact type planetary gear 3 having a cycloid-like curve tooth form.

In the present embodiment, the gear device 1 is used in a state where the gear body 22 of the ring gear 2 is fixed to a fixing member such as the housing 10 together with the outer ring 62 of the bearing member 6, as an example. As a result, the planetary gear 3 rotates relative to the fixed member (the case 10, etc.) with the relative rotation of the internal gear 2 and the planetary gear 3.

Further, in the present embodiment, when the gear device 1 is used for the actuator 100, the rotational force as an input is applied to the eccentric shaft 7, whereby the rotational force as an output is taken out from the output shaft integrated with the inner race 61 of the bearing member 6. That is, the gear device 1 operates with the rotation of the eccentric shaft 7 as an input rotation and the rotation of the output shaft integrated with the inner race 61 as an output rotation. Thus, in the gear device 1, an output rotation that is decelerated at a relatively high reduction ratio with respect to an input rotation can be obtained.

The drive source 101 is a power generation source such as a motor (electric motor). The power generated by the drive source 101 is transmitted to the eccentric shaft 7 in the gear device 1. Specifically, the drive source 101 is connected to the eccentric shaft 7 via an input shaft, and power generated by the drive source 101 is transmitted to the eccentric shaft 7 via the input shaft. Thereby, the driving source 101 can rotate the eccentric shaft 7.

Further, in the gear device 1 of the present embodiment, as shown in fig. 3, the rotation axis Ax1 on the input side and the rotation axis Ax1 on the output side are on the same line. In other words, the input-side rotation axis Ax1 is coaxial with the output-side rotation axis Ax 1. Here, the input-side rotation shaft Ax1 is the rotation center of the eccentric shaft 7to which the input rotation is given, and the output-side rotation shaft Ax1 is the rotation center of the inner ring 61 (and the output shaft) that generates the output rotation. That is, in the gear device 1, it is possible to obtain an output rotation that is decelerated at a relatively high reduction ratio with respect to an input rotation on the same axis.

As shown in fig. 4, the internal gear 2 is an annular member having internal teeth 21. In the present embodiment, the internal gear 2 has an annular shape with at least an inner peripheral surface that is perfectly circular in plan view. An inner tooth 21 is formed along the circumferential direction of the internal gear 2 on the inner circumferential surface of the annular internal gear 2. The plurality of teeth constituting the internal teeth 21 are all of the same shape and are provided at equal intervals over the entire circumferential direction of the inner circumferential surface of the internal gear 2. That is, the pitch circle of the internal teeth 21 is a perfect circle in plan view. The center of the pitch circle of the internal teeth 21 is on the rotation axis Ax 1. The internal gear 2 has a predetermined thickness along the direction of the rotation axis Ax 1. The tooth directions of the internal teeth 21 are all parallel to the rotation axis Ax 1. The dimension of the internal teeth 21 in the tooth direction is slightly smaller than the thickness direction of the internal gear 2.

Here, as described above, the internal gear 2 has the annular (circular ring-shaped) gear body 22 and the plurality of pins 23. The plurality of pins 23 are rotatably held by the inner peripheral surface 221 of the gear body 22 to constitute the internal teeth 21. In other words, the plurality of pins 23 function as a plurality of teeth constituting the internal teeth 21, respectively. Specifically, as shown in fig. 2, a plurality of inner peripheral grooves 223 are formed in the entire circumferential direction of the inner peripheral surface 221 of the gear body 22. The plurality of inner peripheral grooves 223 are all of the same shape and are disposed at equal intervals. The plurality of inner peripheral grooves 223 are each formed parallel to the rotation axis Ax1 over the entire length of the gear body 22 in the thickness direction. The plurality of pins 23 are assembled to the gear body 22 so as to be fitted into the plurality of inner peripheral grooves 223. Each of the plurality of pins 23 is held in a state capable of rotating in the inner peripheral groove 223. In addition, the gear main body 22 (together with the outer race 62) is fixed to the housing 10. Accordingly, a plurality of fixing holes 222 for fixing are formed in the gear body 22.

As shown in fig. 4, the planetary gear 3 is an annular member having external teeth 31. In the present embodiment, the planetary gear 3 has an annular shape in which at least the outer peripheral surface is a perfect circle in a plan view. An outer tooth 31 is formed on the outer peripheral surface of the annular planetary gear 3 along the circumferential direction of the planetary gear 3. The plurality of teeth constituting the external teeth 31 are all of the same shape and are provided at equal intervals over the entire circumferential direction of the outer peripheral surface of the external gear 3. That is, 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 located at a position offset from the rotation axis Ax1 by a distance Δl (see fig. 4). The planetary gear 3 has a predetermined thickness along the direction of the rotation axis Ax 1. The external teeth 31 are formed over the entire length of the planetary gear 3 in the thickness direction. The tooth directions of the external teeth 31 are all parallel to the rotation axis Ax 1. In the planetary gear 3, unlike the internal gear 2, the external teeth 31 are integrally formed with the body of the planetary gear 3 from one 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 is formed with an opening 33 that opens in a circular shape. The opening 33 is a hole penetrating the planetary gear 3 in the thickness direction. The center of the opening 33 coincides with the center of the planetary gear 3 in plan view, and the inner peripheral surface of the opening 33 (the inner peripheral surface of the planetary gear 3) and the pitch circle of the external teeth 31 are concentric. An eccentric body bearing 5 is accommodated in the opening 33 of the planetary gear 3. Further, by inserting the eccentric shaft 7 into (the eccentric body inner ring 51 of) the eccentric body bearing 5, the eccentric body bearing 5 and the eccentric shaft 7 are combined with the planetary gear 3. In a state where the planetary gear 3 is combined with the eccentric body bearing 5 and the eccentric shaft 7, the planetary gear 3 swings around the rotation axis Ax1 when the eccentric shaft 7 rotates.

The planetary gear 3 configured as described above is disposed inside the internal gear 2. The planetary gear 3 is formed to be smaller than the internal gear 2 by one turn in plan view, and the planetary gear 3 can swing inside the internal gear 2 in a state of being combined with the internal gear 2. At this time, the outer peripheral surface of the planetary gear 3 is formed with the outer teeth 31, and the inner peripheral surface of the inner gear 2 is formed with the inner teeth 21. Therefore, in a state where the planetary gear 3 is disposed inside the internal gear 2, the external teeth 31 and the internal teeth 21 face each other.

Further, the pitch circle of the external teeth 31 is one turn smaller than the pitch circle of the internal teeth 21. In a state where 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 offset from the center (rotation axis Ax 1) of the pitch circle of the internal teeth 21 by a distance Δl (see fig. 4). Therefore, the external teeth 31 and at least a part of the internal teeth 21 are opposed to each other with a gap therebetween, and the entire circumferential direction does not mesh with each other. However, the planetary gear 3 swings (revolves) around the rotation axis Ax1 inside the inner gear 2, and therefore the outer teeth 31 mesh with the inner teeth 21 locally. That is, by the planetary gear 3 swinging about the rotation axis Ax1, as shown in fig. 4, the teeth constituting part of the plurality of teeth of the external teeth 31 mesh with the teeth constituting part of the plurality of teeth of the internal teeth 21. As a result, in the gear device 1, a part of the external teeth 31 can be meshed with a part of the internal teeth 21.

Here, the number of teeth of the internal teeth 21 in the internal gear 2 is N (N is a positive integer) greater than the number of teeth of the external teeth 31 of the planetary gear 3. In the present embodiment, N is "1", for example, 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. The difference in the number of teeth between the planetary gear 3 and the internal gear 2 defines the reduction ratio of the output rotation to the input rotation in the gear device 1.

In the present embodiment, the thickness of the planetary gear 3 is smaller than the thickness of the gear body 22 of the internal gear 2, as an example. Further, the size of the external teeth 31 in the tooth direction (direction parallel to the rotation axis Ax 1) is smaller than the size of the internal teeth 21 in the tooth direction (direction parallel to the rotation axis Ax 1). In other words, the external teeth 31 are received in the range of the tooth direction of the internal teeth 21 in the direction parallel to the rotation axis Ax 1.

In the present embodiment, as described above, the rotation of the planetary gear 3 corresponding to the rotation component 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 coupled to the inner race 61 by the plurality of inner pins 4. As shown in fig. 5A and 5B, the planetary gear 3 is formed with a plurality of inner pin holes 32 into which the plurality of inner pins 4 are inserted. The number of the inner pin holes 32 is the same as that of the inner pins 4, and in the present embodiment, 18 inner pin holes 32 and 18 inner pins 4 are provided, respectively, as an example. Each of the plurality of inner pin holes 32 is a hole that is circular and penetrates the planetary gear 3 in the thickness direction. The plurality (here, 18) of inner pin holes 32 are arranged at equal intervals in the circumferential direction on a virtual circle concentric with the opening 33.

The plurality of inner pins 4 connect the planetary gear 3 and the inner race 61 of the bearing member 6. The plurality of inner pins 4 are each formed in a cylindrical shape. The diameter and length of the plurality of inner pins 4 are the same in the plurality of inner pins 4. The diameter of the inner pin 4 is one turn smaller than the diameter of the inner pin hole 32. Thus, the inner pin 4 is inserted into the inner pin hole 32 in a state where a margin (gap) of a space is secured between the inner pin 4 and the inner peripheral surface 321 of the inner pin hole 32 (see fig. 4).

The bearing member 6 has an outer ring 62 and an inner ring 61, and is used to take out the output of the gear device 1 as rotation of the inner ring 61 relative to the outer ring 62. The bearing member 6 includes a plurality of rolling elements 63 (see fig. 3) in addition to the outer ring 62 and the inner ring 61.

As shown in fig. 6A and 6B, the outer ring 62 and the inner ring 61 are annular members. The outer ring 62 and the inner ring 61 each have a circular shape that is a perfect circle in plan view. The inner ring 61 is smaller than the outer ring 62 by one turn 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 race 61 has a plurality of holding holes 611 into which the plurality of inner pins 4 are inserted, respectively. The number of the holding holes 611 is the same as that of the inner pins 4, and in the present embodiment, 18 holding holes 611 are provided as an example. As shown in fig. 6A and 6B, each of the plurality of holding holes 611 is a hole that is circular and penetrates the inner ring 61 in the thickness direction. The plurality of (here, 18) holding 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 holding hole 611 is equal to or larger than the diameter of the inner pin 4 and smaller than the diameter of the inner pin hole 32.

Further, the inner race 61 is integrated with the output shaft, and the rotation of the inner race 61 is taken out as the rotation of the output shaft. Accordingly, a plurality of output side mounting holes 612 (see fig. 2) for mounting the output shaft are formed in the inner race 61. In the present embodiment, the plurality of output side mounting holes 612 are disposed on a virtual circle concentric with the outer periphery of the inner ring 61, and are located further inside than the plurality of holding holes 611.

The outer ring 62 is fixed to a fixing member such as the housing 10 together with the gear main body 22 of the internal gear 2. Accordingly, a plurality of through holes 621 for fixing are formed in the outer ring 62. Specifically, as shown in fig. 3, the outer ring 62 is fixed to the housing 10 by a screw (bolt) 60 for fixing, which passes through the through hole 621 and the fixing hole 222 of the gear body 22, in a state where the gear body 22 is interposed between the outer ring and the housing 10.

The plurality of rolling elements 63 are disposed in a gap between the outer ring 62 and the inner ring 61. The plurality of rolling elements 63 are arranged in parallel in the circumferential direction of the outer ring 62. The plurality of rolling elements 63 are all metal members of the same shape, and are disposed at equal intervals over the entire circumferential direction of the outer ring 62.

In the present embodiment, the bearing member 6 is a cross roller bearing, as an example. That is, the bearing member 6 has cylindrical rollers as the rolling elements 63. The axis of the cylindrical rolling element 63 is inclined at 45 degrees with respect to a plane orthogonal to the rotation axis Ax1, and is also inclined from the outer part Zhou Zhengjiao of the inner ring 61. Further, a pair of rolling elements 63 adjacent to each other in the circumferential direction of the inner ring 61 are arranged in an orientation orthogonal to each other in the axial direction. In the bearing member 6 formed of such a crossed roller bearing, a load in the radial direction, a load in the thrust direction (direction along the rotation axis Ax 1), and a bending force (bending moment load) to the rotation axis Ax1 are easily received. Further, by one bearing member 6, these three loads can be tolerated, and thus the required rigidity can be ensured.

As shown in fig. 7A and 7B, the eccentric shaft 7 is a cylindrical member. The eccentric shaft 7 has a shaft portion 71 and an eccentric portion 72. The shaft portion 71 has a cylindrical shape with at least an outer peripheral surface thereof being substantially circular in plan view. The center (central axis) of the shaft portion 71 coincides with the rotation axis Ax 1. The eccentric portion 72 has a circular disk shape with at least an outer peripheral surface thereof being a perfect circle in plan view. The center (central axis) of the eccentric portion 72 coincides with the center C1 offset from the rotation axis Ax 1. Here, the distance Δl (see fig. 7B) between the rotation axis Ax1 and the center C1 becomes the eccentric amount of the eccentric portion 72 with respect to the shaft portion 71. The eccentric portion 72 has a flange shape protruding from the outer peripheral surface of the shaft portion 71 over the entire circumference at the center portion in the longitudinal direction (axial direction) of the shaft portion 71. According to the above configuration, the eccentric shaft 7 rotates (rotates) about the rotation axis Ax1 by the shaft portion 71, and thereby the eccentric portion 72 performs an eccentric motion.

In the present embodiment, the shaft portion 71 and the eccentric portion 72 are integrally formed of one metal member, thereby realizing the seamless eccentric shaft 7. The eccentric shaft 7 having such a shape is combined with the eccentric body bearing 5 to the planetary gear 3. Therefore, when the eccentric shaft 7 rotates in a state in which the eccentric body bearing 5 and the eccentric shaft 7 are combined with the planetary gear 3, the planetary gear 3 swings around the rotation shaft Ax 1.

Further, the eccentric shaft 7 has a through hole 73 penetrating the shaft portion 71 in the axial direction (longitudinal direction). The through hole 73 is opened in a circular shape at both axial ends of the shaft center portion 71. The center (central axis) of the through hole 73 coincides with the rotation axis Ax 1. A cable such as a power supply line or a signal line can be inserted through the through hole 73.

In the present embodiment, a rotational force is applied as an input from the driving source 101 to the eccentric shaft 7. Accordingly, a plurality of input side mounting holes 74 for mounting an input shaft connected to the drive source 101 are formed in the eccentric shaft 7 (see fig. 7A and 7B). In the present embodiment, the plurality of input side mounting holes 74 are arranged around the through hole 73 in one end surface in the axial direction of the shaft center portion 71, and are arranged on a virtual circle concentric with the through hole 73.

The eccentric body bearing 5 is a member that has an eccentric body outer ring 52 and an eccentric body inner ring 51, absorbs a rotation component in rotation of the eccentric shaft 7, and transmits only rotation of the eccentric shaft 7, that is, a swing component (revolution component) of the eccentric shaft 7, other than the rotation component of the eccentric shaft 7, to the planetary gear 3. The eccentric body bearing 5 includes a plurality of rolling elements 53 (see fig. 3) in addition to the eccentric body outer ring 52 and the eccentric body inner ring 51.

The eccentric body outer ring 52 and the eccentric body inner ring 51 are both annular members. The eccentric body outer ring 52 and the eccentric body inner ring 51 each have a circular shape that is a perfect circle in a plan view. The eccentric body inner ring 51 is smaller than the eccentric body outer ring 52 by one turn, and is disposed inside the eccentric body outer ring 52. Here, since the inner diameter of the eccentric body outer ring 52 is larger than the outer diameter of the eccentric body inner ring 51, a gap is generated between the inner peripheral surface of the eccentric body outer ring 52 and the outer peripheral surface of the eccentric body inner ring 51.

The plurality of rolling elements 53 are disposed in a gap between the eccentric body outer ring 52 and the eccentric body inner ring 51. The plurality of rolling elements 53 are arranged in parallel in the circumferential direction of the eccentric body outer ring 52. The plurality of rolling elements 53 are all metal members of the same shape, and are arranged at equal intervals over the entire circumferential direction of the eccentric body outer ring 52. In the present embodiment, the eccentric body bearing 5 is constituted by a deep groove ball bearing using balls as the rolling elements 53, as an example.

Here, the inner diameter of the eccentric body inner ring 51 coincides with the outer diameter of the eccentric portion 72 in the eccentric shaft 7. The eccentric body bearing 5 is combined with the eccentric shaft 7 in a state that the eccentric portion 72 of the eccentric shaft 7 is inserted into the eccentric body inner ring 51. The outer diameter of the eccentric body outer ring 52 matches the inner diameter (diameter) of the opening 33 in the planetary gear 3. The eccentric body bearing 5 is combined with the planetary gear 3 in a state in which the eccentric body outer ring 52 is fitted into the opening 33 of the planetary gear 3. In other words, the eccentric body bearing 5 in a state of being fitted to the eccentric portion 72 of the eccentric shaft 7 is accommodated in the opening 33 of the planetary gear 3.

In the present embodiment, as an example, the dimension of the eccentric body bearing 5 in the width direction (the direction parallel to the rotation axis Ax 1) of the eccentric body inner ring 51 is substantially the same as the thickness of the eccentric portion 72 of the eccentric shaft 7. The width direction (the direction parallel to the rotation axis Ax 1) of the eccentric body outer ring 52 is slightly smaller than the width direction of the eccentric body inner ring 51. Further, the width direction dimension of the eccentric body outer ring 52 is larger than the thickness of the planetary gear 3. Accordingly, the planetary gear 3 is housed in the range of the eccentric body bearing 5 in the direction parallel to the rotation axis Ax 1. On the other hand, the width direction dimension of the eccentric body outer ring 52 is smaller than the tooth direction dimension (direction parallel to the rotation axis Ax 1) of the internal teeth 21. Accordingly, the eccentric body bearing 5 is housed in the range of the ring gear 2 in the direction parallel to the rotation axis Ax 1.

When the eccentric shaft 7 rotates in a state where the eccentric body bearing 5 and the eccentric shaft 7 are combined with the planetary gear 3, the eccentric body inner ring 51 rotates (eccentric motion) around the rotation axis Ax1 that is offset from the center C1 of the eccentric body inner ring 51 in the eccentric body bearing 5. At this time, the rotation component of the eccentric shaft 7 is absorbed by the eccentric body bearing 5. Therefore, only the rotation of the eccentric shaft 7, that is, the swinging component (revolution component) of the eccentric shaft 7 other than the rotation component of the eccentric shaft 7 is transmitted to the planetary gear 3 through the eccentric body bearing 5. Thus, when the eccentric shaft 7 rotates in a state in which the eccentric body bearing 5 and the eccentric shaft 7 are combined with the planetary gear 3, the planetary gear 3 swings around the rotation shaft Ax 1.

As shown in fig. 8A and 8B, the support body 8 is formed in a ring shape and supports the plurality of inner pins 4. The support body 8 has a plurality of support holes 82 into which the plurality of inner pins 4 are inserted. The number of the support holes 82 is the same as that of the inner pins 4, and in the present embodiment, 18 support holes 82 are provided as an example. As shown in fig. 8A and 8B, each of the plurality of support holes 82 is a hole that is circular and penetrates the support body 8 in the thickness direction. The plurality of (here, 18) support holes 82 are arranged at equal intervals in the circumferential direction on a virtual circle concentric with the outer peripheral surface 81 of the support body 8. The diameter of the support hole 82 is equal to or larger than the diameter of the inner pin 4 and smaller than the diameter of the inner pin hole 32. In the present embodiment, the diameter of the support hole 82 is equal to the diameter of the holding hole 611 formed in the inner ring 61, as an example.

As shown in fig. 3, the support body 8 is disposed so as to face the planetary gear 3 from one side (input side) of the rotation shaft Ax 1. The support body 8 functions to bind the plurality of inner pins 4 by inserting the plurality of inner pins 4 into the plurality of support holes 82. Further, the support body 8 is position-restricted by bringing the outer peripheral surface 81 into contact with the plurality of pins 23. As a result, the support body 8 is centered by the plurality of pins 23, and as a result, the plurality of inner pins 4 are supported by the support body 8, and centering is also performed by the plurality of pins 23. The support 8 is described in detail in the column "(3.3) support".

The first bearing 91 and the second bearing 92 are respectively mounted on the shaft 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 shaft center portion 71 so as to sandwich the eccentric portion 72 in a direction parallel to the rotation axis Ax 1. The first bearing 91 is disposed on the input side of the rotation shaft Ax1 when viewed from the eccentric portion 72. The second bearing 92 is disposed on the output side of the rotation shaft Ax1 when viewed from the eccentric portion 72. The first bearing 91 holds the eccentric shaft 7 rotatably with respect to the housing 10. The second bearing 92 holds the eccentric shaft 7 rotatably with respect to the inner race 61 of the bearing member 6. Thereby, the shaft portion 71 of the eccentric shaft 7 is rotatably held at two locations on both sides of the eccentric portion 72 in the direction parallel to the rotation axis Ax 1.

The housing 10 is cylindrical and has a flange 11 on the output side of the rotation shaft Ax 1. The flange 11 has a plurality of mounting holes 111 for fixing the housing 10 itself. In addition, a bearing hole 12 is formed in an end surface of the housing 10 on the output side of the rotation shaft Ax 1. The bearing hole 12 is opened in a circular shape. The first bearing 91 is fitted into the bearing hole 12, whereby the first bearing 91 is attached to the housing 10.

Further, a plurality of screw holes 13 are formed around the bearing hole 12 on the output side end surface of the rotation shaft Ax1 of the housing 10. The plurality of 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 housing 10. Specifically, the fixing screw 60 passes through the through hole 621 of the outer ring 62 and the fixing hole 222 of the gear body 22, and is screwed to the screw hole 13, thereby fixing the gear body 22 and the outer ring 62 to the housing 10.

As shown in fig. 3, the gear device 1 of the present embodiment further includes a plurality of oil seals 14, 15, 16, and the like. The oil seal 14 is fitted to the input-side end of the rotation shaft Ax1 of the eccentric shaft 7, and closes the gap between the housing 10 and the eccentric shaft 7 (shaft center portion 71). The oil seal 15 is fitted to the output-side end of the rotation shaft Ax1 of the eccentric shaft 7, and closes the gap between the inner race 61 and the eccentric shaft 7 (shaft center portion 71). The oil seal 16 is fitted to the output-side end face of the rotation shaft Ax1 of the bearing member 6, and fills the gap between the inner ring 61 and the outer ring 62. The space enclosed by the plurality of oil seals 14, 15, 16 constitutes a lubricant holding space 17 (see fig. 9). The lubricant retaining space 17 contains a space between the inner ring 61 and the outer ring 62 of the bearing member 6. Further, the plurality of pins 23, the planetary gear 3, the eccentric body bearing 5, the support body 8, the first bearing 91, the second bearing 92, and the like are accommodated in the lubricant holding space 17.

A lubricant is enclosed in the lubricant holding space 17. The lubricant is liquid and can flow in the lubricant holding space 17. Therefore, at the time of use of the gear device 1, for example, a lubricant enters the meshing portion of the internal teeth 21 constituted by the plurality of pins 23 and the external teeth 31 of the planetary gear 3. The term "liquid" in the embodiments of the present disclosure includes liquid or gel-like substances. The term "gel-like" as used herein means a state having intermediate properties between liquid and solid, and includes a state of a gel (colloid) composed of two phases, i.e., a liquid phase and a solid phase. For example, an emulsion (emulsion) in which a dispersing agent is a liquid phase and a dispersoid is a liquid phase, and a suspension (suspension) in which a dispersoid is a solid phase, or the like, is included in a state called gel (gel) or sol (sol). The state in which the dispersant is in a solid phase and the dispersoid is in a liquid phase is also included in "gel-like". In the present embodiment, the lubricant is a liquid lubricating oil (oil liquid), for example.

In the gear device 1 having the above-described configuration, the rotational force is applied as an input to the eccentric shaft 7, so that the eccentric shaft 7 rotates about the rotational axis Ax1, and the planetary gear 3 swings (revolves) about the rotational axis Ax 1. At this time, the planetary gear 3 swings in a state of being inscribed inside the internal gear 2 in the internal gear 2 and a part of the external teeth 31 being meshed with a part of the internal teeth 21, so that the meshing position of the internal teeth 21 and the external teeth 31 moves in the circumferential direction of the internal gear 2. Thus, relative rotation is generated between the two gears (the internal gear 2 and the planetary gear 3) according to the difference in the number of teeth between the planetary gear 3 and the internal gear 2. The rotation (rotation component) of the planetary gear 3, in addition to the swing component (revolution component) of the planetary gear 3, is transmitted to the inner ring 61 of the bearing member 6 by the plurality of inner pins 4. As a result, from the output shaft integrated with the inner race 61, a rotational output can be obtained that is decelerated at a relatively high reduction ratio in accordance with the difference in the number of teeth between the two gears.

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

R1=v2/(V1-V2) … … (formula 1)

In short, the smaller the tooth number difference (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 of the number of teeth (V1-V2) is "1", so that the reduction ratio R1 is "51" according to the above formula 1. In this case, when the eccentric shaft 7 rotates clockwise (360 degrees) around the rotation axis Ax1 as viewed from the input side of the rotation axis Ax1, the inner race 61 rotates counterclockwise (that is, about 7.06 degrees) around the rotation axis Ax1 by the amount of the tooth difference "1".

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

The gear device 1 may include at least the internal gear 2, the planetary gear 3, the plurality of internal pins 4, the bearing member 6, and the support body 8, and may include, for example, a spline bush or the like as a component.

However, in the case where the input rotation on the high-speed rotation side is accompanied by the eccentric motion as in the gear device 1 of the present embodiment, if the balance of the rotating body that rotates at the high speed is not obtained, vibration or the like may be caused, and therefore, the weight balance may be obtained by using the balance weight or the like. That is, since the rotating body composed of at least one of the eccentric body inner ring 51 and the member (eccentric shaft 7) rotating together with the eccentric body inner ring 51 performs the eccentric motion at high speed, it is preferable to obtain the weight balance of the rotating body with respect to the rotation shaft Ax 1. In the present embodiment, as shown in fig. 3 and 4, the weight balance of the rotating body with respect to the rotation shaft Ax1 is obtained by providing the clearance 75 in a part of the eccentric portion 72 of the eccentric shaft 7.

In short, in the present embodiment, the weight balance of the rotating body with respect to the rotation shaft Ax1 is obtained by reducing the weight of a part of the rotating body (here, the eccentric shaft 7) without adding a balance weight or the like. That is, the gear device 1 of the present embodiment includes the eccentric body bearing 5 which is accommodated in the opening 33 formed in the planetary gear 3 and swings the planetary gear 3. The eccentric body bearing 5 has an eccentric body outer ring 52 and an eccentric body inner ring 51 disposed inside the eccentric body outer ring 52. The rotating body constituted by at least one of the eccentric body inner ring 51 and the member rotating together with the eccentric body inner ring 51 has a gap 75 at a portion on the center C1 side of the eccentric body outer ring 52 as viewed from the rotation axis Ax1 of the eccentric body inner ring 51. In the present embodiment, the eccentric shaft 7 is a "member that rotates together with the eccentric body inner ring 51", and corresponds to a "rotating body". Therefore, the clearance 75 formed in the eccentric portion 72 of the eccentric shaft 7 corresponds to the clearance 75 of the rotating body. As shown in fig. 3 and 4, the gap 75 is located on the center C1 side when viewed from the rotation axis Ax1, and therefore functions to make the weight balance of the eccentric shaft 7 nearly uniform from the rotation axis Ax1 to the circumferential direction.

More specifically, the space 75 includes a recess formed in an inner peripheral surface of the through hole 73 penetrating the rotating body along the rotation axis Ax1 of the eccentric body inner ring 51. That is, in the present embodiment, since the rotating body is the eccentric shaft 7, the recess formed in the inner peripheral surface of the through hole 73 penetrating the eccentric shaft 7 along the rotation shaft Ax1 functions as the clearance 75. In this way, by using the recess formed in the inner peripheral surface of the through hole 73 as the void 75, the weight balance of the rotating body can be obtained without accompanying change in appearance.

In the present embodiment, the internal gear 2 is an example of a "first gear", and the planetary gear 3 is an example of a "second gear". That is, the first gear is the internal gear 2 having the annular gear body 22 and the plurality of pins 23. The plurality of pins 23 are rotatably held in a plurality of inner peripheral grooves 223 formed in the inner peripheral surface 221 of the gear main body 22, and constitute the internal teeth 21. The second gear is a planetary gear 3 having external teeth 31 that partially mesh with the internal teeth 21. In the gear device 1, the planetary gear 3 is rotated relative to the internal gear 2 by swinging the planetary gear 3 about the rotation axis Ax 1.

(3.2) Rotation Structure of inner Pin

Next, the rotation structure of the inner pin 4 of the gear device 1 according to the present embodiment will be described in more detail with reference to fig. 9. Fig. 9 is an enlarged view of the region Z1 of fig. 3.

First, as described above, the plurality of inner pins 4 are members that connect the planetary gear 3 and the inner ring 61 of the bearing member 6. Specifically, one end portion in the longitudinal direction of the inner pin 4 (in the present embodiment, the end portion on the input side of the rotation shaft Ax 1) is inserted into the inner pin hole 32 of the planetary gear 3, and the other end portion in the longitudinal direction of the inner pin 4 (in the present embodiment, the end portion on the output side of the rotation shaft Ax 1) is inserted into the holding hole 611 of the inner ring 61.

Here, since the diameter of the inner pin 4 is smaller than the diameter of the inner pin hole 32 by one turn, a gap can be secured between the inner pin 4 and the inner peripheral surface 321 of the inner pin hole 32, and the inner pin 4 can move within the inner pin hole 32, that is, the inner pin 4 can relatively move with respect to the center of the inner pin hole 32. On the other hand, the diameter of the holding hole 611 is not smaller than the diameter of the inner pin 4 but smaller than the diameter of the inner pin hole 32. In the present embodiment, the diameter of the holding hole 611 is substantially the same as the diameter of the inner pin 4, and slightly larger than the diameter of the inner pin 4. Therefore, the movement of the inner pin 4 within the holding hole 611 is restricted, that is, the relative movement of the inner pin 4 with respect to the center of the holding hole 611 is prohibited. Accordingly, the inner pin 4 is held in a state in which the planetary gear 3 can revolve in the inner pin hole 32, and is held in a state in which the planetary gear cannot revolve in the holding hole 611 with respect to the inner ring 61. Thereby, the swinging component of the pinion 3, that is, the revolution component of the pinion 3 is absorbed by the running fit of the inner pin holes 32 and the inner pins 4, and the rotation (rotation component) of the pinion 3 other than the swinging component (revolution component) of the pinion 3 is transmitted to the inner ring 61 by the plurality of inner pins 4.

However, in the present embodiment, the diameter of the inner pin 4 is slightly larger than the holding hole 611, and thus the inner pin 4 can rotate in the holding hole 611 while being inserted into the holding hole 611, although the revolution in the holding hole 611 is inhibited. That is, even when the inner pin 4 is inserted into the holding hole 611, it is not pressed into the holding hole 611 but can rotate in the holding hole 611. As described above, in the gear device 1 of the present embodiment, since the plurality of inner pins 4 are each held by the inner ring 61 in the rotatable state, the inner pins 4 themselves can rotate when the inner pins 4 revolve in the inner pin holes 32.

In other words, in the present embodiment, the inner pin 4 is held in a state where both the revolution and the rotation in the inner pin hole 32 are possible with respect to the planetary gear 3, and is held in a state where only the rotation in the holding hole 611 is possible with respect to the inner ring 61. That is, the plurality of inner pins 4 are rotatable (revolvable) about the rotation axis Ax1 in a state where their respective rotation is not constrained (rotatable state), and are revolvable in the plurality of inner pin holes 32. Therefore, when the rotation (rotation component) of the planetary gear 3 is transmitted to the inner race 61 by the plurality of inner pins 4, the inner pins 4 can revolve and rotate in the inner pin holes 32 and can rotate in the holding holes 611. Therefore, when the inner pin 4 revolves in the inner pin hole 32, the inner pin 4 is in a rotatable state, and thus rolls against the inner peripheral surface 321 of the inner pin hole 32. In other words, the inner pin 4 revolves in the inner pin hole 32 so as to roll on the inner peripheral surface 321 of the inner pin hole 32, and therefore, loss due to frictional resistance between the inner peripheral surface 321 of the inner pin hole 32 and the inner pin 4 is less likely to occur.

As described above, in the structure of the present embodiment, the inner roller can be omitted because it is originally difficult to generate a loss due to frictional resistance between the inner peripheral surface 321 of the inner pin hole 32 and the inner pin 4. Therefore, in the present embodiment, each of the plurality of inner pins 4 is configured to directly contact the inner peripheral surface 321 of the inner pin hole 32. That is, in the present embodiment, the inner pin 4 in a state where the inner roller is not mounted is inserted into the inner pin hole 32 so that the inner pin 4 directly contacts the inner peripheral surface 321 of the inner pin hole 32. As a result, the inner roller can be omitted, and the diameter of the inner pin hole 32 can be suppressed to be relatively small, so that the planetary gear 3 can be miniaturized (particularly, the diameter can be reduced), and the entire gear device 1 can be easily miniaturized. If the size of the planetary gear 3 is fixed, the number (number) of the inner pins 4 may be increased to smooth the transmission of rotation or the inner pins 4 may be thickened to increase the strength, for example, as compared with the first related art. Further, the number of components can be reduced by the amount corresponding to the inner roller, and the reduction in cost of the gear device 1 can be facilitated.

In the gear device 1 of the present embodiment, at least a part of each of the plurality of 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, the inner pin 4 is disposed at least a part thereof in the same position as the bearing member 6 in the direction parallel to the rotation axis Ax 1. In other words, at least a part of the inner pin 4 is located between both end surfaces of the bearing member 6 in the direction parallel to the rotation axis Ax 1. In other words, each of the plurality of inner pins 4 is disposed at least partially inside the outer ring 62 of the bearing member 6. In the present embodiment, the output-side end of the rotation shaft Ax1 in the inner pin 4 is located at the same position as the bearing member 6 in the direction parallel to the rotation shaft Ax 1. In short, since the output-side end portion of the rotation shaft Ax1 in the inner pin 4 is inserted into the holding hole 611 formed in the inner ring 61 of the bearing member 6, at least the end portion thereof 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 part of each of the plurality of inner pins 4 is disposed at the same position as the bearing member 6 in the axial direction of the bearing member 6, and thus the size of the gear device 1 in the direction parallel to the rotation axis Ax1 can be suppressed to be small. That is, in the gear device 1 of the present embodiment, the size of the gear device 1 in the direction parallel to the rotation axis Ax1 can be reduced, and further downsizing (thinning) of the gear device 1 can be contributed to, as compared with a structure in which the bearing member 6 and the inner pin 4 are juxtaposed (opposed) in the axial direction of the bearing member 6.

Here, the opening surface of the holding hole 611 on the output side of the rotation shaft Ax1 is closed by, for example, an output shaft integrated with the inner ring 61. Thus, the movement of the inner pin 4 to the output side (right side in fig. 9) of the rotation shaft Ax1 is restricted by the output shaft integrated with the inner ring 61 and the like.

In the present embodiment, the following configuration is adopted in order to smoothly rotate the inner pin 4 with respect to the inner ring 61. That is, the rotation of the inner pin 4 is smoothed by interposing a lubricant (lubricating oil) between the inner peripheral surface of the holding hole 611 formed in the inner ring 61 and the inner pin 4. In particular, in the present embodiment, since the lubricant holding space 17 into which the lubricant is injected is provided between the inner ring 61 and the outer ring 62, the rotation of the inner pin 4 is smoothed by the lubricant in the lubricant holding space 17.

As shown in fig. 9, in the present embodiment, the inner ring 61 includes: a plurality of holding holes 611 into which the plurality of inner pins 4 are inserted, respectively; and a plurality of links 64. The plurality of connecting passages 64 connect the lubricant retaining space 17 between the inner ring 61 and the outer ring 62 with the plurality of retaining holes 611. Specifically, the inner ring 61 is formed with a connecting passage 64 extending in the radial direction from a portion of the inner peripheral surface of the holding hole 611, that is, a portion corresponding to the rolling elements 63. The connecting passage 64 is a hole that penetrates between the bottom surface of a recess (groove) that accommodates the rolling element 63 in the facing surface of the inner ring 61 that faces the outer ring 62 and the inner peripheral surface of the holding hole 611. In other words, the opening surface of the connecting passage 64 on the lubricant retaining space 17 side is disposed at a position facing (opposing) the rolling elements 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 configuration, since the lubricant retaining space 17 is connected to the retaining hole 611 by the connecting passage 64, the lubricant in the lubricant retaining space 17 is supplied to the retaining hole 611 through the connecting passage 64. That is, when the bearing member 6 is operated to roll the rolling elements 63, the rolling elements 63 function as a pump, and the lubricant in the lubricant holding space 17 can be fed to the holding hole 611 via the connecting passage 64. In particular, the opening surface of the connecting passage 64 on the lubricant retaining space 17 side is located at a position facing (opposing) the rolling elements 63 of the bearing member 6, whereby the rolling elements 63 effectively function as a pump when the rolling elements 63 rotate. As a result, the lubricant is interposed between the inner peripheral surface of the holding hole 611 and the inner pin 4, and the rotation of the inner pin 4 with respect to the inner ring 61 can be smoothed.

(3.3) Support body

Next, the structure of the support body 8 of the gear device 1 according to the present embodiment will be described in more detail with reference to fig. 10. Fig. 10 is a sectional view taken along line B1-B1 of fig. 3. However, in fig. 10, cross-sectional lines are omitted for members other than the support body 8. In fig. 10, only the internal gear 2 and the support body 8 are shown, and other members (the inner pin 4 and the like) are not shown. Further, in fig. 10, the inner peripheral surface 221 of the gear main body 22 is omitted from illustration.

First, as described above, the support body 8 is a member for supporting the plurality of inner pins 4. That is, the support body 8 bundles the plurality of inner pins 4, thereby dispersing the load acting on the plurality of inner pins 4 when transmitting the rotation (rotation component) of the planetary gear 3 to the inner ring 61. Specifically, the pin holder has a plurality of support holes 82 into which the plurality of inner pins 4 are inserted, respectively. In the present embodiment, the diameter of the support hole 82 is equal to the diameter of the holding hole 611 formed in the inner ring 61, as an example. Therefore, the support body 8 supports the plurality of inner pins 4 in a state where the plurality of inner pins 4 are each rotatable. That is, the plurality of inner pins 4 are each held in a state of being rotatable relative to both the inner ring 61 of the bearing member 6 and the support body 8.

In this way, the support body 8 positions the plurality of inner pins 4 with respect to the support body 8 in both the circumferential direction and the radial direction. That is, the inner pin 4 is inserted into the support hole 82 of the support body 8, and thereby movement in all directions in a plane orthogonal to the rotation axis Ax1 is restricted. The inner pin 4 is thus positioned with the support body 8 not only in the circumferential direction but also in the radial direction (radial direction).

Here, the support body 8 has at least an outer peripheral surface 81 in the shape of a circular ring that is perfectly circular in plan view. The support body 8 is restricted in position by bringing the outer peripheral surface 81 into contact with the plurality of pins 23 in the internal gear 2. Since the plurality of pins 23 constitute the internal teeth 21 of the internal gear 2, in other words, the support body 8 is position-restricted by bringing the outer peripheral surface 81 into contact with the internal teeth 21. Here, the diameter of the outer peripheral surface 81 of the support body 8 is the same as the diameter of a virtual circle (addendum circle) passing through the front ends of the internal teeth 21 of the internal tooth gear 2. Therefore, all of the plurality of pins 23 are in contact with the outer peripheral surface 81 of the support body 8. Thus, in a state where the support body 8 is position-regulated by the plurality of pins 23, the center of the support body 8 is position-regulated so as to overlap with the center (rotation axis Ax 1) of the internal gear 2. As a result of this, the support body 8 is centered, and as a result, the plurality of pins 23 are also used to center the plurality of inner pins 4 supported by the support body 8.

In addition, the plurality of inner pins 4 rotate (revolve) around the rotation axis Ax1, thereby transmitting the rotation (rotation component) of the planetary gear 3 to the inner ring 61. Therefore, the support body 8 supporting the plurality of inner pins 4 rotates around the rotation axis Ax1 together with the plurality of inner pins 4 and the inner ring 61. At this time, since the support body 8 is centered by the plurality of pins 23, the support body 8 smoothly rotates with the center of the support body 8 maintained on the rotation axis Ax 1. Further, since the support body 8 rotates in a state where the outer peripheral surface 81 thereof is in contact with the plurality of pins 23, the plurality of pins 23 rotate (spin) in association with the rotation of the support body 8. Thus, the support body 8 constitutes a needle bearing (needle roller bearing) together with the internal gear 2, and rotates smoothly.

That is, the outer peripheral surface 81 of the support body 8 rotates relative to the gear main body 22 together with the plurality of inner pins 4 in contact with the plurality of pins 23. Therefore, if the gear body 22 of the internal gear 2 is regarded as the "outer ring" and the support body 8 is regarded as the "inner ring", the plurality of pins 23 interposed therebetween function as "rolling bodies (rollers)". In this way, the support body 8 constitutes a needle bearing together with the internal gear 2 (the gear main body 22 and the plurality of pins 23), and can smoothly rotate.

Further, since the support body 8 sandwiches the plurality of pins 23 between the gear main bodies 22, the support body 8 also functions as a "stopper" that suppresses movement of the pins 23 in the direction separating from the inner peripheral surface 221 of the gear main body 22. That is, the plurality of pins 23 are sandwiched between the outer peripheral surface 81 of the support body 8 and the inner peripheral surface 221 of the gear body 22, whereby the plurality of pins 23 are prevented from floating from the inner peripheral surface 221 of the gear body 22. In short, in the present embodiment, the plurality of pins 23 are each restricted from moving in the direction of separating from the gear main body 22 by contact with the outer peripheral surface 81 of the support body 8.

However, as shown in fig. 9, in the present embodiment, the support body 8 is located on the opposite side of the bearing member 6 from the inner race 61 via the planetary gear 3. That is, the support body 8, the planetary gears 3, and the inner race 61 are arranged in parallel to the rotation axis Ax 1. In the present embodiment, the support body 8 is located on the input side of the rotation shaft Ax1 as viewed from the planetary gear 3, and the inner ring 61 is located on the output side of the rotation shaft Ax1 as viewed from the planetary gear 3, as an example. The support body 8 supports both ends of the inner pin 4 in the longitudinal direction (the direction parallel to the rotation axis Ax 1) together with the inner ring 61, and the center of the inner pin 4 in the longitudinal direction penetrates the inner pin hole 32 of the planetary gear 3. In summary, the gear device 1 of the present embodiment includes the bearing member 6, and the bearing member 6 includes the outer ring 62 and the inner ring 61 disposed inside the outer ring 62, and 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 body 8 and the inner race 61 in the axial direction of the support body 8.

According to this structure, since the support body 8 and the inner ring 61 support both ends in the longitudinal direction of the inner pin 4, the inner pin 4 is less likely to be inclined. In particular, bending force (bending moment load) applied to the plurality of inner pins 4 with respect to the rotation shaft Ax1 is also easily received. In the present embodiment, the support body 8 is sandwiched between the planetary gear 3 and the housing 10 in the direction parallel to the rotation axis Ax 1. Thereby, the movement of the support body 8 to the input side (left side in fig. 9) of the rotation shaft Ax1 is restricted by the housing 10. The movement of the inner pin 4 penetrating the support hole 82 of the support body 8 and protruding from the support body 8 to the input side of the rotation shaft Ax1 to the input side (left side in fig. 9) of the rotation shaft Ax1 is also restricted by the housing 10.

In the present embodiment, the support body 8 and the inner ring 61 are also in contact with both end portions of the plurality of pins 23. That is, as shown in fig. 9, the support body 8 is in contact with one end (the input side end of the rotation shaft Ax 1) of the pin 23 in the longitudinal direction (the direction parallel to the rotation shaft Ax 1). The inner ring 61 is in contact with the other end portion (the output side end portion of the rotation shaft Ax 1) of the pin 23 in the longitudinal direction (the direction parallel to the rotation shaft Ax 1). According to this structure, since the support body 8 and the inner ring 61 are cored at both ends in the longitudinal direction of the pin 23, the inclination of the inner pin 4 is less likely to occur. In particular, bending force (bending moment load) applied to the plurality of inner pins 4 with respect to the rotation shaft Ax1 is also easily received.

The plurality of pins 23 have a length equal to or greater than the thickness of the support body 8. In other words, the support body 8 is housed within the range of the tooth direction of the internal teeth 21 in the direction parallel to the rotation axis Ax 1. Thus, the outer peripheral surface 81 of the support body 8 contacts the plurality of pins 23 over the entire length in the tooth direction (direction parallel to the rotation axis Ax 1) of the internal teeth 21. Therefore, the outer peripheral surface 81 of the support body 8 is less likely to be worn out locally, which is a problem of "single-side wear".

In the present embodiment, the outer peripheral surface 81 of the support body 8 has a smaller surface roughness than a surface of the support body 8 adjacent to the outer peripheral surface 81. That is, the surface roughness of the outer peripheral surface 81 is smaller than both end surfaces in the axial direction (thickness direction) of the support body 8. The "surface roughness" referred to in the embodiments of the present disclosure refers to the roughness of the surface of an object, and the smaller the value, the smaller (fewer) the roughness of the surface becomes. In the present embodiment, the surface roughness is defined as an arithmetic balance roughness (Ra), as an example. For example, the outer peripheral surface 81 is smaller in surface roughness than the surface other than the outer peripheral surface 81 of the support body 8 by a treatment such as polishing. In this structure, the rotation of the support body 8 becomes smoother.

In the present embodiment, the outer peripheral surface 81 of the support body 8 has a lower hardness than the peripheral surfaces of the plurality of pins 23 and a higher hardness than the inner peripheral surface 221 of the gear body 22. The term "hardness" as used in the embodiments of the present disclosure refers to the degree of hardness of an object, and the hardness of a metal is represented by, for example, the size of an indentation formed by pushing a steel ball under a certain pressure. Specifically, examples of the hardness of the metal include rockwell Hardness (HRC), brinell Hardness (HB), vickers Hardness (HV), and shore hardness (Hs). As means for improving the hardness (hardening) of the metal member, there are, for example, alloying, heat treatment, and the like. In the present embodiment, as an example, the hardness of the outer peripheral surface 81 of the support body 8 is increased by a treatment such as carburizing and quenching. In this configuration, even if abrasion powder or the like is hardly generated due to the rotation of the support body 8, smooth rotation of the support body 8 is easily maintained for a long period of time.

(4) Application example

Next, an application example of the gear device 1 and the actuator 100 according to the present embodiment will be described.

The gear device 1 and the actuator 100 according to the present embodiment are applied to, for example, a horizontal multi-joint robot, that is, a robot such as a so-called selective flexible combined robot arm (SCARA: SELECTIVE COMPLIANCE ASSEMBLY ROBOT ARM).

The gear device 1 and the actuator 100 according to the present embodiment are not limited to the horizontal articulated robot described above, and may be, for example, an industrial robot other than a horizontal articulated robot, a robot other than an industry, or the like. As an example, industrial robots other than the horizontal articulated robot include a vertical articulated robot, a parallel link robot, and the like. As robots other than industrial robots, there are, for example, home robots, nursing robots, medical robots, and the like.

(5) Details of internal gears

Next, details of the internal gear 2 in the gear device 1 of the present embodiment will be described with reference to fig. 11 to 13. Fig. 11 is an enlarged schematic cross-sectional view of the meshing portion between the internal teeth 21 (pin 23) and the external teeth 31 in fig. 9, and the components other than the internal gear 2 (gear body 22 and pin 23) and the planetary gears 3 are not shown. Fig. 12 is a schematic view of a section taken along line A1-A1 in fig. 11, and the components other than the internal gear 2 and the planetary gears 3 are omitted from the drawings as in fig. 11. In fig. 11 and 12, the outline of the portion to be enlarged is shown in the right frame.

As in the present embodiment, in the gear device 1 including the first gear (the internal gear 2) and the second gear (the planetary gear 3) that rotates relative to the first gear by meshing with the first gear, for example, a "sliding contact" is generated between the gear main body 22 of the first gear (the internal gear 2) and the pin 23 forming the internal teeth 21. The term "sliding contact" as used in the present disclosure means a contact state between the two which causes macroscopic sliding (Grossslip) as compared with a minute sliding (Microslip) in rolling contact (or fixed contact) or the like. That is, a "sliding contact" is one of the motion patterns of 2 solid surfaces that are in contact and relatively move, and is a pattern of relative motion that causes macroscopic sliding between the two, unlike a rolling contact.

As described above, as shown in fig. 11 and 12, in the first gear (internal gear 2), the coating layer 224 is formed at "sliding contact portions" such as the inner surfaces of the plurality of inner peripheral grooves 223 that make sliding contact with the other member (here, the pins 23). Here, the coating layer 224 is a layer that covers at least a part of the skeleton portion 225 that becomes a base material. That is, in the present embodiment, at least the inner surfaces of the plurality of inner peripheral grooves 223, which are sliding contact portions, in the skeleton portion 225 as a base material of the gear body 22 of the ring gear 2 are covered with the coating layer 224.

The coating layer 224 is made of a material having a specific gravity greater than that of the skeleton portion 225. In the present embodiment, the coating layer 224 and the skeleton portion 225 are both made of metal, and the coating layer 224 is made of metal having a specific gravity greater than that of the skeleton portion 225. As an example, the skeleton portion 225 serving as a base material of the gear body 22 is made of aluminum (Al), and the coating layer 224 is made of iron (Fe).

In summary, the gear device 1 of the present embodiment includes a first gear (internal gear 2) and a second gear (planetary gear 3). The second gear rotates relative to the first gear by meshing with the first gear. The first gear has a skeleton portion 225 and a coating layer 224 having a larger specific gravity than the skeleton portion 225. At least a sliding contact portion of the skeleton portion 225, which is in sliding contact with the other member, is covered with the coating layer 224.

According to the above-described configuration, since the skeleton portion 225 of the first gear (internal gear 2) itself is made of a material having a small specific gravity, for example, even if it has a corresponding thickness, the weight can be suppressed to be relatively small. On the other hand, since the sliding contact portion (with another member) in the skeleton portion 225 is covered with the coating layer 224 having a specific gravity greater than that of the skeleton portion 225, the sliding contact portion can improve wear resistance and maintain strength as the first gear (internal gear 2). As a result, according to the gear device 1 of the present embodiment, the gear device 1 can be easily reduced in weight while maintaining strength.

In the present embodiment, since the first gear is the internal gear 2 and the second gear is the planetary gear 3, at least the inner surfaces of the plurality of inner peripheral grooves 223 in sliding contact with the plurality of pins 23 as another member in the skeleton portion 225 of the internal gear 2 become sliding contact portions. Therefore, at least the inner surfaces (sliding contact portions) of the plurality of inner peripheral grooves 223 are covered with the coating layer 224.

That is, as shown in fig. 11 and 12, since the inner surfaces of the plurality of inner peripheral grooves 223 holding the plurality of pins 23 in the gear main body 22 are covered with the coating layer 224, even if each pin 23 rotates (rotates) to make sliding contact with the inner surfaces of the inner peripheral grooves 223, abrasion of the inner surfaces of the inner peripheral grooves 223 can be suppressed. In short, the inner surface of the inner peripheral groove 223 in sliding contact with the pin 23 is covered with the coating layer 224 to protect the skeleton 225, thereby improving wear resistance and maintaining strength. In this way, when the planetary gear 3 rotates relative to the internal gear 2, abrasion of the gear body 22 due to sliding contact of the pin 23 is suppressed.

In the present embodiment, the coating layer 224 is formed over the entire circumference of the circumferential direction of the inner circumferential surface 221 of the gear main body 22 so as to cover the entire area of the inner surface of the inner circumferential groove 223. Therefore, the skeleton portion 225 is not exposed to the inner surface of the inner peripheral groove 223 in sliding contact with the pin 23. However, as shown in fig. 11, the coating layer 224 is not formed at both end portions in the tooth direction (the direction parallel to the rotation axis Ax 1) of the internal teeth 21 in the inner peripheral surface 221 of the gear main body 22, and the skeleton portion 225 is exposed. Specifically, at the inner peripheral surface 221 of the gear main body 22, a portion constituting the inner peripheral groove 223 protrudes inward (the rotation axis Ax1 side), and a coating layer 224 is formed so as to cover only the protruding portion.

In the present embodiment, in particular, the coating layer 224 is formed so as to entirely cover the skeleton portion 225 in the corner portions of the inner peripheral groove 223 which are both ends of the inner teeth 21 in the tooth direction, that is, in the cross section shown in fig. 11, with respect to the portion which is formed in the shape of a lobe. In other words, the coating layer 224 is formed from the inner surface of the inner peripheral groove 223 to the step portion adjacent thereto. By covering the corner portions with the coating layer 224 in this manner, even if the corner portions are in contact with the pins 23, the pins 23 can be prevented from directly contacting the skeleton portion 225, and abrasion of the skeleton portion 225 can be easily suppressed.

However, in this embodiment, the coating layer 224 is formed by thermal spraying. The term "thermal spraying" as used in the present disclosure refers to a processing technique of forming a coating film on the surface of a processing object by ejecting particles, which melt-soften a thermal spraying material such as a metal, onto the surface of the processing object by various heat sources. When the molten particles sprayed by the spraying are adhered to a substrate such as a metal as a processing object, the molten particles are instantaneously cooled and solidified to form a film. The coating formed on the skeleton portion 225 by thermal spraying constitutes the coating layer 224.

That is, the method of manufacturing the gear device 1 of the present embodiment includes a plating step of forming the coating layer 224 by plating at least a part of the skeleton portion 225 of the first gear (internal gear 2). The coating layer 224 formed by sputtering may have a larger film thickness than a coating film formed by plating, vapor deposition, or the like.

However, since a porous film (porous film) is formed on the surface of the film formed by sputtering, it is preferable to finish the surface. Therefore, the method for manufacturing the gear device 1 according to the present embodiment includes a surface finishing step such as polishing after the sputtering step. According to the surface finishing step, although the film thickness of the film formed by the sputtering is reduced, the film having a sufficient film thickness is formed by the sputtering, so that the film (the coating layer 224) having a sufficient film thickness can be obtained even after the surface finishing step.

The skeleton portion 225 has a higher thermal conductivity than the coating layer 224. As described above, in the present embodiment, the coating layer 224 is iron (Fe), and thus the thermal conductivity of the coating layer 224 is 80.3 (W/m·k). In contrast, since the skeleton portion 225 is made of aluminum (Al), the heat conductivity of the skeleton portion 225 is 237 (W/m·k). That is, the skeleton portion 225 has a thermal conductivity approximately three times that of the coating layer 224. As a result, most of the gear body 22 of the first gear (internal gear 2) can be constituted by the skeleton portion 225 having high thermal conductivity, and the heat radiation performance of the first gear (internal gear 2) can be improved.

For example, when heat is generated at the meshing portion of the first gear (internal gear 2) and the second gear (planetary gear 3) or at the sliding contact portion of the pin 23 in the gear body 22 due to friction or the like with the operation of the gear device 1, the generated heat can be efficiently dissipated. In particular, the gear body 22 forms a part of the outer contour of the gear device 1 together with the housing 10, and can efficiently radiate heat generated inside the gear device 1 to the outside of the gear device 1.

In the present embodiment, the coating layer 224 is a spray coating film having a composition different from that of the skeleton portion 225. That is, as described above, the coating layer 224 is a spray coating film formed by spray coating. Here, although a sprayed film having the same composition as the skeleton portion 225 may be formed on the surface of the skeleton portion 225, a sprayed film having a composition different from that of the skeleton portion 225 is formed in the present embodiment. Specifically, the skeleton portion 225 is aluminum (Al), whereas the coating layer 224 is iron (Fe).

However, in view of the adhesion of the coating layer 224 to the skeleton portion 225, it is preferable that the linear expansion coefficient of the skeleton portion 225 is close to that of the coating layer 224. Specifically, in the case of a temperature environment of 93 ℃ (200°f) or less, the coefficients of linear expansion of both are preferably close to such a degree that the skeleton portion 225 is not peeled from the coating layer 224 due to the difference in the coefficients of linear expansion.

In the present embodiment, the coating layer 224 has a thickness of 50 μm or more. That is, the coating layer 224 formed by thermal spraying may have a larger film thickness than a coating film formed by plating, vapor deposition, or the like, and the specific film thickness of the coating layer 224 is preferably 50 μm or more. As an example, in the sputtering step, a coating film of 150 μm is formed on the surface of the skeleton portion 225, and in the surface finishing step, 100 μm is polished off, whereby a coating layer 224 of 50 μm is formed. By providing the coating layer 224 with such a sufficient film thickness, the pin 23 can be prevented from directly contacting the skeleton portion 225, and abrasion of the skeleton portion 225 can be easily suppressed.

Here, the first gear (internal gear 2) has a base layer 226 on the surface of the skeleton portion 225, and the coating layer 224 is laminated on the base layer 226. That is, as shown in the white boxes of fig. 11 and 12, a base layer 226 and a coating layer 224 are laminated in this order on the surface of the skeleton portion 225. Thus, the coating layer 224 is not directly laminated on the surface of the skeleton portion 225, but is laminated via the base layer 226, and thus the adhesion of the coating layer 224 to the skeleton portion 225 can be improved.

The underlayer 226 is formed on the surface of the skeleton portion 225 by, for example, processing to increase the surface roughness (arithmetic average roughness (Ra)) of the skeleton portion 225. Specifically, in the present embodiment, the underlayer 226 is formed by laser peening the surface of the skeleton portion 225, as an example. The "laser peening" described in the present disclosure is a surface modification technique that irradiates a processing object with a laser pulse, imparts compressive residual stress to the surface of the processing object, and increases the surface hardness. That is, the method for manufacturing the gear device 1 of the present embodiment includes a substrate forming step for forming the substrate layer 226 such as laser peening before the sputtering step.

Here, the lattice direction of the base layer 226 is preferably a direction based on the sliding direction of the other member at the sliding contact portion. That is, as shown in fig. 13A and 13B, the sliding direction of the other member (pin 23) is determined on the inner surface of the inner peripheral groove 223 which becomes the sliding contact portion of the other member in the skeleton portion 225. That is, since the pin 23 rotates (rotates) around its center line in the inner peripheral groove 223, a sliding direction along the circumferential direction of the pin 23 is generated on the inner surface of the inner peripheral groove 223. Therefore, by determining the lattice direction of the base layer 226 based on the sliding direction, the adhesion of the coating layer 224 is improved, and peeling of the coating layer 224 and the like are easily suppressed.

As an example, as shown in fig. 13A, the lattice direction of the base layer 226 formed by laser peening or the like is preferably a direction intersecting the sliding direction of the other member (pin 23) at the sliding contact portion. For example, the direction along the longitudinal direction of the inner peripheral groove 223 is defined as the cell direction of the base layer 226, and the cell direction of the base layer 226 is orthogonal to the sliding direction of the other member. According to such a configuration, even if the other member (pin 23) is in sliding contact with the coating layer 224 formed on the base layer 226, the coating layer 224 is caught by the processing mark of the base layer 226, and is difficult to separate from the skeleton portion 225.

As another example, as shown in fig. 13B, it is also conceivable to arrange the base layer 226 formed by laser peening or the like in a lattice shape with respect to the sliding direction of the other member (pin 23) at the sliding contact portion. For example, discrete processing marks are formed so as to be approximately uniformly dispersed in the longitudinal direction and the circumferential direction of the inner peripheral groove 223. The processing marks may be, for example, circular, polygonal, or dot-like. According to such a configuration, even if the other member (pin 23) is in sliding contact with the coating layer 224 formed on the base layer 226, the coating layer 224 is caught by the processing mark of the base layer 226, and is difficult to separate from the skeleton portion 225.

(6) Modification examples

The first embodiment is merely one of various embodiments of the present invention. As long as the object of the present invention can be achieved, various modifications can be made according to the design and the like. In the present invention, the drawings referred to are schematic, and the ratio of the size and thickness of each component in the drawings is not necessarily limited to reflect the actual dimensional ratio. A modification of the first embodiment will be described below. The modifications described below can be applied in any suitable combination.

The gear body 22 of the internal gear 2 may be seamlessly integrated with the housing 10. In this case, the housing 10 is made of the same material (for example, aluminum) as the gear body 22, and the housing 10 and the gear body 22 are handled as one piece. In this structure, the volume and surface area of the aluminum member become larger than those of the gear main body 22 and the case 10 which are separate, and weight reduction and improvement of heat dissipation performance of the entire gear device 1 can be expected. Similarly, the outer ring 62 of the bearing member 6 may be seamlessly integrated with the gear body 22 of the internal gear 2.

It is also not necessary that the first gear is an internal gear 2 and the second gear is a planetary gear 3. For example, the first gear may be the planetary gear 3, and the second gear may be the internal gear 2. In this case, the base material of the planetary gear 3 constitutes a skeleton portion, and for example, a sliding contact portion of the planetary gear 3 that is in sliding contact with another member (the inner pin 4) is covered with a coating layer.

The skeleton portion 225 is not limited to iron (Fe), and the coating layer 224 is not limited to aluminum (Al). The coating layer 224 may be made of a material having a specific gravity greater than that of the skeleton portion 225, and at least one of the coating layer 224 and the skeleton portion 225 may be a nonmetal. Even in this case, the skeleton portion 225 preferably has a higher thermal conductivity than the coating layer 224.

The coating layer 224 is not limited to being formed by sputtering, and may be formed by a method other than sputtering.

The underlayer 226 is not limited to laser peening, and may be formed by processing such as peening by projecting a projection material onto a processing target. The lattice direction of the base layer 226 is not limited to the examples shown in fig. 13A and 13B, and may be, for example, a direction along the sliding direction of the other member (pin 23) or a direction inclined with respect to the sliding direction of the other member (pin 23).

In the first embodiment, the gear device 1 of the type in which the number of the planetary gears 3 is 1 is exemplified, but the gear device 1 may include 2 or more planetary gears 3. For example, in the case where the gear device 1 includes 3 planetary gears 3, it is preferable that the 3 planetary gears 3 are arranged with a phase difference of 120 degrees around the rotation axis Ax 1. Alternatively, in the case where the gear device 1 includes three planetary gears 3, 2 planetary gears 3 of the 3 planetary gears 3 may be identical in phase, and the remaining one planetary gear 3 may be disposed 180 degrees apart around the rotation axis Ax 1.

The number of pins 23 (the number of teeth of the internal teeth 21) and the number of teeth of the external teeth 31 described in the first embodiment are merely examples, and may be appropriately changed.

The material of each component of the gear device 1 is not limited to metal, and may be, for example, a resin such as engineering plastic.

In addition, the gear device 1 is not limited to a configuration in which the rotational force of the inner ring 61 is taken out as an output, as long as the relative rotation between the inner ring 61 and the outer ring 62 of the bearing member 6 can be taken out as an output. For example, the rotational force of the outer ring 62 (the case 10) that rotates relative to the inner ring 61 may be taken out as an output.

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

Embodiment II

< Summary >

As shown in fig. 14 to 16, the gear device 1A of the present embodiment is different from the gear device 1 of the first embodiment in that it is a distributed eccentric oscillating type ring gear device. Hereinafter, the same components as those of embodiment 1 are denoted by the same reference numerals, and description thereof is omitted as appropriate. Fig. 14 is a perspective view showing a schematic configuration of the gear device 1A. Fig. 15 is a schematic exploded perspective view of the gear device 1A as seen from the input side of the rotation shaft Ax 1. Fig. 16 is a schematic cross-sectional view of the gear device 1A.

As shown in fig. 14 to 16, the gear device 1A of the present embodiment includes a plurality of (3 in the present embodiment) eccentric shafts (crankshafts) 7A, 7B, 7C disposed at positions offset from the axial center (rotation axis Ax 1) of the internal gear 2. Further, the gear device 1A includes an input shaft 500 disposed on the shaft center (rotation axis Ax 1) of the internal gear 2 and centered on the rotation axis Ax1, and an input gear 501 integrally formed with the input shaft 500. The crank gears 502A, 502B, 502C are respectively spline-connected to the plurality of eccentric shafts 7A, 7B, 7C. These plurality (3 in the present embodiment) of crank gears 502A, 502B, 502C are arranged so as to mesh with the input gear 501. Therefore, when the input shaft 500 is driven, the gear device 1A drives the eccentric shafts 7A, 7B, 7C synchronously by using the input gear 501, thereby causing the planetary gear 3 to oscillate while being internally engaged with the internal gear 2.

The gear device 1A of the present embodiment includes a plurality of planetary gears 3. Specifically, the gear device 1A includes two planetary gears 3, that is, a first planetary gear 301 and a second planetary gear 302. The 2 planetary gears 3 are arranged so as to face each other in a direction parallel to the rotation axis Ax 1. That is, the planetary gear 3 includes a first planetary gear 301 and a second planetary gear 302 that are juxtaposed in a direction parallel to the rotation axis Ax 1. The shapes of the first planetary gear 301 and the second planetary gear 302 are common to themselves.

These two planetary gears 3 (first planetary gear 301 and second planetary gear 302) are arranged 180 degrees apart around the rotation axis Ax 1. In the example of fig. 16, the center C1 of the first planetary gear 301 located on the input side (right side in fig. 16) of the rotation axis Ax1 among the first planetary gear 301 and the second planetary gear 302 is in a state of being deviated (offset) upward in the drawing with respect to the rotation axis Ax 1. On the other hand, the center C2 of the second planetary gear 302 located on the output side (left side in fig. 16) of the rotation shaft Ax1 is in a state of being deviated (offset) downward in the drawing with respect to the rotation shaft Ax 1. Here, the distance Δl1 between the rotation axis Ax1 and the center C1 is an eccentric amount 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 an eccentric amount of the second planetary gear 302 with respect to the rotation axis Ax 1. In this way, the plurality of planetary gears 3 are equally arranged in the circumferential direction around the rotation axis Ax1, and thus weight balance between the plurality of planetary gears 3 can be achieved.

In the first planetary gear 301 and the second planetary gear 302, their centers C1, C2 are located at 180 degrees of rotational symmetry with respect to the rotation axis Ax 1. In the present embodiment, the directions of the eccentric amounts Δl1 and Δl2 as viewed from the rotation axis Ax1 are opposite, but the absolute values thereof are the same.

More specifically, each of the eccentric shafts 7A, 7B, and 7C has 2 eccentric portions 72 with respect to 1 shaft portion 71. The amounts of eccentricity of the centers of the 2 eccentric portions 72 from the center of the shaft center portion 71 are the same as the amounts of eccentricity Δl1, Δl2 of the first planetary gear 301 and the second planetary gear 302 with respect to the rotation shaft Ax1, respectively. The shape of the plurality of eccentric shafts 7A, 7B, 7C is itself common. Regarding the plurality of crank gears 502A, 502B, 502C, their shapes are themselves common.

Further, the carrier flange 18 and the output flange 19 are disposed on both sides of the first planetary gear 301 and the second planetary gear 302 in the direction parallel to the rotation axis Ax 1. Both ends of the eccentric shafts 7A, 7B, 7C are held by the bracket flange 18 and the output flange 19 via rolling bearings 41, 42. That is, the eccentric shafts 7A, 7B, 7C are rotatably held by the carrier flange 18 and the output flange 19 on both sides of the planetary gear 3 in the direction parallel to the rotation axis Ax 1.

Eccentric body bearings 5 are mounted on eccentric portions 72 of the eccentric shafts 7A, 7B, and 7C. The first planetary gear 301 and the second planetary gear 302 are formed with 3 openings 33 corresponding to the 3 eccentric shafts 7A, 7B, and 7C, respectively. Further, the eccentric body bearing 5 is accommodated in each opening 33. In other words, the eccentric body bearings 5 are mounted on the first planetary gear 301 and the second planetary gear 302, respectively, and the eccentric shafts 7A, 7B, 7C are inserted into the eccentric body bearings 5, whereby the eccentric body bearings 5 and the eccentric shafts 7A, 7B, 7C are combined with the planetary gear 3. In the gear device 1A of the present embodiment, the inner pin 4 is omitted, and the rotation (rotation component) of the planetary gear 3 other than the swing component (revolution component) of the planetary gear 3 can be extracted by replacing the inner pin 4 with a plurality of eccentric shafts 7A, 7B, 7C.

According to the configuration described above, the input shaft 500 is rotated about the rotation axis Ax1 by applying the rotation force as the input to the input shaft 500, and the rotation force is distributed from the input gear 501 to the plurality of eccentric shafts 7A, 7B, and 7C. That is, when the input gear 501 rotates, the 3 crank gears 502A, 502B, 502C that are simultaneously engaged with the input gear 501 rotate in the same direction and at the same rotational speed. Since the eccentric shafts 7A, 7B, and 7C are spline-coupled to the respective crank gears 502A, 502B, and 502C, the 3 eccentric shafts 7A, 7B, and 7C rotate in the same direction and at the same rotational speed in a state of being decelerated compared to the number of teeth of the input gear 501 and the crank gears 502A, 502B, and 502C. As a result, the 3 eccentric portions 72 formed at the same position on the input side of the rotation shaft Ax1 among the 3 eccentric shafts 7A, 7B, 7C are rotated in synchronization, and the first planetary gear 301 is oscillated. Further, out of the 3 eccentric shafts 7A, 7B, 7C, the 3 eccentric portions 72 formed at the same position on the output side of the rotation shaft Ax1 are rotated in synchronization, so that the second planetary gear 302 is oscillated.

As a result, the shaft center portions 71 of the plurality of eccentric shafts 7A, 7B, and 7C rotate (spin) around the rotation axis Ax1, respectively, whereby the first planetary gear 301 and the second planetary gear 302 rotate (eccentrically move) around the rotation axis Ax1 with a 180 degree phase difference around the rotation axis Ax 1.

Here, the first planetary gear 301 and the second planetary gear 302 are respectively in internal mesh with the internal gear 2. Therefore, each time the first planetary gear 301 and the second planetary gear 302 oscillate, the first planetary gear 301 and the second planetary gear 302 rotate with respect to the internal gear 2 by generating a phase shift in the circumferential direction of the difference in number of teeth (of the internal teeth 21 and the external teeth 31). This rotation is transmitted to the bracket flange 18 and the output flange 19 as revolution around the axis (rotation axis Ax 1) of the internal gear 2 of each eccentric shaft 7A, 7B, 7C. Thus, the bracket flange 18 and the output flange 19 can be rotated relative to the gear main body (with the integrated housing 10) about the rotation axis Ax 1.

In short, the gear device 1A of the present embodiment is different from the first embodiment in that the planetary gear 3 is oscillated by the plurality of eccentric shafts 7A, 7B, 7C arranged at positions offset from the rotation axis Ax1, but is common to the first embodiment in that the rotational output is obtained by the oscillation of the planetary gear 3. That is, in the gear device 1A, when the planetary gear 3 oscillates, the meshing position of the internal teeth 21 and the external teeth 31 moves in the circumferential direction of the internal gear 2, a relative rotation corresponding to the difference in the number of teeth of the planetary gear 3 and the internal gear 2 occurs between the two gears (the internal gear 2 and the planetary gear 3). Here, if the internal gear 2 is fixed, the planetary gear 3 rotates (rotates) with the relative rotation of the two gears. As a result, a rotational output can be obtained from the planetary gear 3, which is decelerated at a relatively high reduction ratio according to the difference in the number of teeth between the two gears.

More specifically, the bearing member 6A of the gear device 1A of the present embodiment includes a first bearing member 601A and a second bearing member 602A. The first bearing member 601A and the second bearing member 602A are each constituted by an angular ball bearing. Specifically, as shown in fig. 16, a first bearing member 601A is disposed on the input side (right side in fig. 16) of the rotation shaft Ax1 as viewed from the planetary gear 3, and a second bearing member 602A is disposed on the output side (left side in fig. 16) of the rotation shaft Ax1 as viewed from the planetary gear 3. The bearing member 6A is configured to be resistant to a radial load, a thrust load (a direction along the rotation axis Ax 1), and a bending force (bending moment load) to the rotation axis Ax1 by the first bearing member 601A and the second bearing member 602A.

Here, the first bearing member 601A and the second bearing member 602A are disposed opposite to each other in the direction parallel to the rotation axis Ax1 on both sides of the planetary gear 3 in the direction parallel to the rotation axis Ax 1. That is, the bearing member 6A is a "combined angular ball bearing" in which a plurality of (here, 2) angular ball bearings are combined. Here, as an example, the first bearing member 601A and the second bearing member 602A are "back surface combined type" that receive a load in a thrust direction (a direction along the rotation axis Ax 1) in which the respective inner rings approach each other. Further, in the gear device 1A, the first bearing member 601A and the second bearing member 602A are combined in a state where appropriate pre-pressing force acts on the inner rings by fastening the respective inner rings 61 in the directions approaching each other.

In addition, the gear device 1A of the present embodiment includes a bracket flange 18 and an output flange 19. The carrier flange 18 and the output flange 19 are disposed on both sides of the planetary gear 3 in a direction parallel to the rotation axis Ax1, and pass through carrier holes 34 (see fig. 16) of the planetary gear 3 to be coupled to each other. Specifically, as shown in fig. 16, a carrier flange 18 is disposed on the input side (right side in fig. 16) of the rotation shaft Ax1 as viewed from the planetary gear 3, and an output flange 19 is disposed on the output side (left side in fig. 16) of the rotation shaft Ax1 as viewed from the planetary gear 3. The inner race of the bearing member 6A (each of the first bearing member 601A and the second bearing member 602A) is fixed to the bracket flange 18 and the output flange 19. In the present embodiment, as an example, the inner ring of the first bearing member 601A is seamlessly integrated with the bracket flange 18. Likewise, the inner ring of the second bearing member 602A is seamlessly integrated with the output flange 19.

The output flange 19 has a plurality (for example, 3) of holder pins 191 (see fig. 15) protruding from one surface of the output flange 19 toward the input side of the rotation shaft Ax 1. The plurality of carrier pins 191 pass through a plurality of (for example, 3) carrier holes 34 formed in the planetary gear 3, and distal ends of the plurality of carrier pins 191 are fixed to the carrier flange 18 by carrier bolts. Here, a gap is secured between the holder pin 191 and the inner peripheral surface of the holder hole 34, and the holder pin 191 is movable within the holder hole 34, that is, relatively movable with respect to the center of the holder hole 34. Thus, the carrier pin 191 does not contact the inner peripheral surface of the carrier hole 34 when the planetary gear 3 swings.

Thus, the gear device 1A is used in the following manner: the rotation of the planetary gear 3 corresponding to the rotation component is taken out as the rotation of the carrier flange 18 and the output flange 19 integrated with the inner ring 61 of the bearing member 6A. That is, in the first embodiment, the relative rotation between the planetary gear 3 and the internal gear 2 is taken out from the inner ring 61 coupled to the planetary gear 3 by the internal pin 4 as the rotation component of the planetary gear 3. In contrast, in the present embodiment, the relative rotation between the planetary gear 3 and the internal gear 2 is taken out from the carrier flange 18 and the output flange 19 integrated with the inner race. In the present embodiment, as an example, the gear device 1A is used in a state in which the outer ring 62 (see fig. 16) of the bearing member 6A is fixed to the housing 10 as a fixing member. That is, the planetary gear 3 is coupled to the carrier flange 18 and the output flange 19, which are rotation members, by the plurality of eccentric shafts 7A, 7B, and 7C, and the gear body 22 is fixed to the fixed member, so that the relative rotation between the planetary gear 3 and the internal gear 2 is taken out from the rotation members (the carrier flange 18 and the output flange 19). In other words, in the present embodiment, the rotation force of the carrier flange 18 and the output flange 19 is extracted as output when the planetary gear 3 rotates relative to the gear body 22.

Further, in the present embodiment, the housing 10 is seamlessly integrated with the gear body 22 of the internal gear 2. That is, in the first embodiment, the gear body 22 of the internal gear 2 is used together with the outer ring 62 of the bearing member 6 in a state of being fixed to the housing 10. In contrast, in the present embodiment, the gear main body 22 as the fixing member is continuously provided with the housing 10 in a seamless manner in the direction parallel to the rotation axis Ax 1.

More specifically, the housing 10 is cylindrical and forms the outer contour of the gear device 1A. In the present embodiment, the center axis of the cylindrical housing 10 is configured to coincide with the rotation axis Ax 1. That is, at least the outer peripheral surface of the housing 10 is a perfect circle centered on the rotation axis Ax1 in a plan view (as viewed from one of the rotation axis Ax1 directions). The housing 10 is formed in a cylindrical shape that is open at both end surfaces in the direction of the rotation axis Ax 1. Here, the housing 10 is seamlessly integrated with the gear body 22 of the internal gear 2, so that the housing 10 and the gear body 22 are handled as one piece. Accordingly, the inner peripheral surface of the housing 10 includes the inner peripheral surface 221 of the gear main body 22. Further, an outer ring 62 of the bearing member 6A is fixed to the housing 10. That is, the outer ring 62 of the first bearing member 601A is fixed to the input side (right side in fig. 16) of the rotation shaft Ax1 by fitting, as viewed from the gear main body 22 in the inner peripheral surface of the housing 10. On the other hand, the outer ring 62 of the second bearing member 602A is fixed to the output side (left side in fig. 16) of the rotation shaft Ax1 by fitting, as viewed from the gear main body 22 of the inner peripheral surface of the housing 10.

Further, an end surface of the rotation shaft Ax1 of the housing 10 on the input side (right side in fig. 16) is closed by a bracket flange 18, and an end surface of the rotation shaft Ax1 of the housing 10 on the output side (left side in fig. 16) is closed by an output flange 19. Accordingly, as shown in fig. 16, the planetary gear 3 (the first planetary gear 301 and the second planetary gear 302), the plurality of pins 23, the eccentric body bearing 5, and other members are housed in the space surrounded by the housing 10, the carrier flange 18, and the output flange 19.

The gear device 1A of the present embodiment further includes a holding member 80, and the holding member 80 is disposed inside the gear body 22 and holds the plurality of pins 23 between the gear body 22 in the radial direction (radial direction of the gear body 22). The holding member 80 is disposed between 2 planetary gears 3, i.e., the first planetary gear 301 and the second planetary gear 302. The holding member 80 has a plurality of outer circumferential grooves 801 on the outer circumferential surface for holding the plurality of pins 23. That is, in the present embodiment, the holding member 80 provided in place of the support body 8 according to the first embodiment functions as a "slit" for restraining the pins 23 from moving in a direction away from the inner peripheral surface 221 of the gear body 22 by sandwiching the plurality of pins 23 between the holding member and the gear body 22. In short, the movement of the plurality of pins 23 in the direction away from the gear body 22 is regulated by the contact of the respective pins of the plurality of pins 23 with the outer peripheral surface of the holding member 80, and the movement of the plurality of pins 23 in the circumferential direction around the rotation axis Ax1 is also regulated by the fitting of the plurality of pins 23 into the outer peripheral groove 801. That is, the pin 23 is positioned not only in the radial direction (radial direction) but also in the circumferential direction by the holding member 80 and the gear body 22.

Therefore, the pin 23 is less likely to come loose between the holding member 80 and the gear main body 22, and when the internal teeth 21 (pin 23) are engaged with the external teeth 31, even if a force directed by the external teeth 31 pulled out from the inner peripheral groove 223 acts on the pin 23, the engagement between the internal teeth 21 and the external teeth 31 is less likely to become unstable. As a result, the gear device 1A according to the present embodiment has an advantage that the engagement between the internal teeth 21 and the external teeth 31 is easily stabilized.

However, in the gear device 1A of the present embodiment, the internal gear 2 is also an example of the "first gear", and the planetary gear 3 is also an example of the "second gear". That is, the first gear is the internal gear 2 having the annular gear body 22 and the plurality of pins 23. The plurality of pins 23 are rotatably held in a plurality of inner peripheral grooves 223 formed in the inner peripheral surface 221 of the gear main body 22, and constitute the internal teeth 21. The second gear is a planetary gear 3 having external teeth 31 that partially mesh with the internal teeth 21. In the gear device 1, the planetary gear 3 is rotated relative to the internal gear 2 by swinging the planetary gear 3 about the rotation axis Ax 1. In the present embodiment, at least the inner surfaces of the plurality of inner peripheral grooves 223 in sliding contact with the plurality of pins 23 as another member in the skeleton portion 225 of the internal gear 2 become sliding contact portions. Therefore, at least the inner surfaces (sliding contact portions) of the plurality of inner peripheral grooves 223 are covered with the coating layer 224.

The configuration of the second embodiment (including the modification) can be appropriately combined with the various configurations described in the first embodiment (including the modification).

(Third embodiment)

As shown in fig. 17 to 20, the gear device 1C of the present embodiment is different from the gear device 1 of the first embodiment in that it includes a rigid internally toothed gear 2C, a flexible externally toothed gear 3C, and a wave generator 4C.

In the gear device 1C of the present embodiment, an annular flexible externally toothed gear 3C is disposed inside an annular rigid internally toothed gear 2C, and a wave generator 4C is disposed inside the flexible externally toothed gear 3C. The wave generator 4C flexes the flexible externally toothed gear 3C into a non-circular shape, thereby locally meshing the external teeth 31C of the flexible externally toothed gear 3C with the internal teeth 21C of the rigid internally toothed gear 2C. When the wave generator 4C rotates, the meshing position of the internal teeth 21C and the external teeth 31C moves in the circumferential direction of the rigid internally toothed gear 2C, and relative rotation occurs between the two gears (the rigid internally toothed gear 2C and the flexible externally toothed gear 3C) to cause the flexible externally toothed gear 3C to perform relative rotation according to the difference in number of teeth with the rigid internally toothed gear 2C. Here, if the rigid internally toothed gear 2C is fixed, the flexible externally toothed gear 3C rotates with the relative rotation of the two gears. As a result, a rotational output, which is decelerated at a relatively high reduction ratio according to the gear difference between the two gears, can be obtained from the flexible externally toothed gear 3C.

The wave generator 4C for generating deflection of the flexible externally toothed gear 3C includes a non-circular cam 41C and a bearing 42C which are driven to rotate around the input-side rotation axis Ax 1. The bearing 42C is disposed between the outer peripheral surface of the cam 41C and the inner peripheral surface 301C of the flexible externally toothed gear 3C. The inner ring 422C of the bearing 42C is fixed to the outer peripheral surface of the cam 41C, and the outer ring 421C of the bearing 42C is elastically deformed by being pressed by the cam 41C by the rolling elements 423C in the form of balls. Here, since the outer ring 421C is rotatable relative to the inner ring 422C by the rolling elements 423C, when the non-circular cam 41C rotates, the rotating portion of the inner ring 422C is transmitted to the outer ring 421C, and harmonic motion occurs in the outer teeth 31C of the flexible externally toothed gear 3C pressed by the cam 41C. Since harmonic motion of the external teeth 31C occurs, the meshing positions of the internal teeth 21C and the external teeth 31C move in the circumferential direction of the rigid internally toothed gear 2C as described above, and relative rotation occurs between the flexible externally toothed gear 3C and the rigid internally toothed gear 2C.

In short, in this gear device 1C, the wave generator 4C having the bearing 42C transmits power by meshing the internal teeth 21C with the external teeth 31C while flexing the flexible externally toothed gear 3C.

More specifically, as an example of the gear device 1C, a cup-shaped harmonic gear device is exemplified. That is, in the gear device 1C of the present embodiment, the flexible externally toothed gear 3C formed in a cup shape is used. The wave generator 4C is combined with the flexible externally toothed gear 3C so as to be housed in the cup-shaped flexible externally toothed gear 3C.

In the gear device 1C of the present embodiment, the rotation axis Ax1 on the input side and the rotation axis Ax2 on the output side are on the same line. In other words, the input-side rotation axis Ax1 and the output-side rotation axis Ax2 are coaxial. Here, the input-side rotation axis Ax1 is the rotation center of the wave generator 4C to which the input rotation is applied, and the output-side rotation axis Ax1 is the rotation center of the flexible externally toothed gear 3C to which the output rotation is generated. That is, in the gear device 1C, the output rotation that is decelerated at a relatively high reduction ratio can be obtained by coaxially rotating with respect to the input rotation.

The rigid internally toothed gear 2C is also called a rigid gear (circular spline), and is an annular member having internal teeth 21C. In the present embodiment, the rigid internally toothed gear 2C has a circular ring shape with at least an inner peripheral surface being a perfect circle in a plan view. An inner tooth 21C is formed on the inner peripheral surface of the circular rigid internally toothed gear 2C along the circumferential direction of the rigid internally toothed gear 2C. The plurality of teeth constituting the internal teeth 21C are all the same shape, and are provided at equal intervals over the entire circumferential direction of the inner circumferential surface of the rigid internally toothed gear 2C. That is, the pitch circles of the internal teeth 21C are perfect circles in a plan view. The rigid internally toothed gear 2C has a predetermined thickness in the direction of the rotation axis Ax 1. The internal teeth 21C are formed over the entire length of the rigid internally toothed gear 2C in the thickness direction. The tooth directions of the internal teeth 21C are all parallel to the rotation axis Ax 1.

The flexible externally toothed gear 3C is also called a flex spline (flex spline), and is an annular member having external teeth 31C. In the present embodiment, the flexible externally toothed gear 3C is a cup-shaped member formed of a relatively thin metal elastic body (metal plate). That is, the flexible externally toothed gear 3C has flexibility due to its relatively small thickness (thinness). The flexible externally toothed gear 3C has a cup-shaped body portion 32C. The body 32C has a trunk 321C and a bottom 322C. In a state where the flexible externally toothed gear 3C is not elastically deformed, at least the inner peripheral surface 301C of the body 321C has a cylindrical shape that is perfectly circular in a plan view. The central axis of the body 321C coincides with the rotation axis Ax 1. The bottom portion 322C is disposed on one opening surface of the body 321C, and has a circular disk shape in plan view. The bottom portion 322C is disposed on an opening surface on the output side of the rotation shaft Ax1, out of the pair of opening surfaces of the body 321C. According to the above, the body portion 32C has a cylindrical shape with a bottom, i.e., a cup shape, which is opened to the input side of the rotation axis Ax1, by the body portion 321C and the bottom portion 322C as a whole. In other words, the opening surface 35C is formed on the end surface of the flexible externally toothed gear 3C on the opposite side of the bottom portion 322C in the direction of the rotation axis Ax 1. That is, the flexible externally toothed gear 3C is cylindrical having an opening surface 35C on one side in the tooth direction D1 (here, the input side of the rotation shaft Ax 1). In the present embodiment, the trunk portion 321C and the bottom portion 322C are integrally formed of 1 metal member, whereby the seamless main body portion 32C can be realized.

Here, the wave generator 4C is combined with the flexible externally toothed gear 3C so that the non-circular wave generator 4C is embedded inside the body 321C. As a result, the flexible externally toothed gear 3C receives an external force in the radial direction (direction orthogonal to the rotation axis Ax 1) from the wave generator 4C from inside to outside, and is thereby elastically deformed into a non-circular shape. In the first comparative example of the present embodiment, the body 321C of the flexible externally toothed gear 3C is elastically deformed into an elliptical shape by the combination of the elliptical-shaped wave generator 4C and the flexible externally toothed gear 3C (see fig. 18). That is, the state in which flexible externally toothed gear 3C is elastically deformed means a state in which wave generator 4C is not combined with flexible externally toothed gear 3C. In contrast, the state in which flexible externally toothed gear 3C is elastically deformed means a state in which wave generator 4C is combined with flexible externally toothed gear 3C.

More specifically, the wave generator 4C is fitted into an end portion of the inner peripheral surface 301C of the body 321C on the opposite side (input side of the rotation axis Ax 1) to the bottom portion 322C. In other words, the wave generator 4C is fitted into the end portion of the body 321C of the flexible externally toothed gear 3C on the opening surface 35C side in the direction of the rotation axis Ax 1. Accordingly, in a state where the flexible externally toothed gear 3C is elastically deformed, the end portion of the flexible externally toothed gear 3C on the opening surface 35C side in the direction of the rotation axis Ax1 is deformed larger than the end portion on the bottom portion 322C side, and is formed in a shape closer to an elliptical shape. Depending on the amount of deformation in the direction of the rotation axis Ax1, the inner peripheral surface 301C of the body 321C of the flexible externally toothed gear 3C includes a tapered surface inclined with respect to the rotation axis Ax1 in a state where the flexible externally toothed gear 3C is elastically deformed.

Further, external teeth 31C are formed along the circumferential direction of the body 321C at least at an end portion of the outer circumferential surface of the body 321C on the opposite side (input side of the rotation axis Ax 1) to the bottom portion 322C. In other words, the external teeth 31C are provided at least at the end portion on the opening surface 35C side in the direction of the rotation axis Ax1 in the body portion 321C of the flexible externally toothed gear 3C. The plurality of teeth constituting the external teeth 31C are all the same in shape and are provided at equal intervals over the entire circumferential direction of the outer peripheral surface of the flexible externally toothed gear 3C. That is, the pitch circle of the external teeth 31C is a perfect circle in a plan view in a state where the flexible externally toothed gear 3C is not elastically deformed. The external teeth 31C are formed only within a range of a certain width from the end edge of the body 321C on the opening surface 35C side (the input side of the rotation axis Ax 1). Specifically, external teeth 31C are formed on the outer peripheral surface of the body 321C at least in a portion (end portion on the opening surface 35C side) into which the wave generator 4C is fitted in the direction of the rotation axis Ax 1. The external teeth 31C each have a tooth direction parallel to the rotation axis Ax 1.

The flexible externally toothed gear 3C thus configured is disposed inside the rigid internally toothed gear 2C. Here, the flexible externally toothed gear 3C is combined with the rigid internally toothed gear 2C such that only an end portion on the opposite side (input side of the rotation axis Ax 1) of the bottom portion 322C in the outer peripheral surface of the body portion 321C is inserted inside the rigid internally toothed gear 2C. That is, in the body 321C of the flexible externally toothed gear 3C, a portion (end portion on the opening surface 35C side) into which the wave generator 4C is fitted is inserted inside the rigid internally toothed gear 2C in the direction of the rotation axis Ax 1. Here, external teeth 31C are formed on the outer peripheral surface of the flexible externally toothed gear 3C, and internal teeth 21C are formed on the inner peripheral surface of the rigid internally toothed gear 2C. Therefore, in a state where the flexible externally toothed gear 3C is disposed inside the rigid internally toothed gear 2C, the external teeth 31C and the internal teeth 21C face each other.

Here, the number of teeth 21C in the rigid internally toothed gear 2C is 2N (N is a positive integer) greater than the number of teeth 31C of the flexible externally toothed gear 3C. In the present embodiment, N is "1", and the number of teeth (of the external teeth 31C) of the flexible externally toothed gear 3C is greater than the number of teeth (of the internal teeth 21C) of the rigid internally toothed gear 2C by "2", as an example. The difference in the number of teeth between the flexible externally toothed gear 3C and the rigid internally toothed gear 2C defines the reduction ratio of the output rotation to the input rotation in the gear device 1C.

Here, as an example in the present embodiment, the relative positions of the flexible externally toothed gear 3C and the rigid internally toothed gear 2C in the direction of the rotation axis Ax1 are set so that the center of the external teeth 31C in the tooth direction D1 and the center of the internal teeth 21C in the tooth direction D1 face each other. That is, in the external teeth 31C of the flexible externally toothed gear 3C and the internal teeth 21C of the rigid internally toothed gear 2C, the position of the center in the tooth direction D1 is aligned with the same position in the direction of the rotation axis Ax 1. In the present embodiment, the size (tooth width) of the external teeth 31C in the tooth direction D1 is larger than the size (tooth width) of the internal teeth 21C in the tooth direction D1. Therefore, the internal teeth 21C are converged within the range of the tooth direction of the external teeth 31C in the direction parallel to the rotation axis Ax 1. In other words, the external teeth 31C protrude toward at least one side in the tooth direction D1 with respect to the internal teeth 21C. In the present embodiment, the external teeth 31C protrude to both sides (input side and output side of the rotation shaft Ax 1) in the tooth direction D1 with respect to the internal teeth 21C.

Here, in a state where elastic deformation is not generated in the flexible externally toothed gear 3C (a state where the wave generator 4C is not combined with the flexible externally toothed gear 3C), the pitch circle of the external teeth 31C describing a perfect circle is set to be one circle smaller than the pitch circle of the internal teeth 21C similarly describing a perfect circle. That is, in a state where the flexible externally toothed gear 3C is not elastically deformed, the external teeth 31C and the internal teeth 21C face each other with a gap therebetween, and are not engaged with each other.

On the other hand, in a state where the flexible externally toothed gear 3C is elastically deformed (a state where the wave generator 4C is combined with the flexible externally toothed gear 3C), the body 321C is deflected into a non-circular shape, so that the external teeth 31C of the flexible externally toothed gear 3C are partially engaged with the internal teeth 21C of the rigid internally toothed gear 2C. That is, in the first comparative example, as shown in fig. 18, the body portion 321C of the flexible externally toothed gear 3C (at least the end portion on the opening surface 35C side) is elastically deformed into an elliptical shape, whereby the external teeth 31C located at both ends in the major axis direction of the elliptical shape mesh with the internal teeth 21C. In other words, the major diameter of the pitch circle of the external teeth 31C drawing an ellipse coincides with the diameter of the pitch circle of the internal teeth 21C drawing a perfect circle, and the minor diameter of the pitch circle of the external teeth 31C drawing an ellipse is smaller than the diameter of the pitch circle of the internal teeth 21C drawing a perfect circle. In this way, when flexible externally toothed gear 3C is elastically deformed, a part of the plurality of teeth constituting external teeth 31C meshes with a part of the plurality of teeth constituting internal teeth 21C. As a result, in the gear device 1C, a part of the external teeth 31C can be meshed with a part of the internal teeth 21C.

Wave generator 4C, also referred to as a wave generator, is a component that flexes flexible externally toothed gear 3C, thereby producing harmonic motion of external teeth 31C of flexible externally toothed gear 3C. In the first comparative example of the present embodiment, the wave generator 4C is a member whose outer peripheral shape is a non-circular shape, specifically, an elliptical shape in plan view.

However, in the gear device 1C of the present embodiment, the rigid internally toothed gear 2C is an example of "a first gear", and the flexible externally toothed gear 3C is an example of "a second gear". That is, the first gear is an annular rigid internally toothed gear 2C having internal teeth 21C. The second gear is an annular flexible externally toothed gear 3C having external teeth 31C and disposed inside the rigid internally toothed gear 2C. The gear device 1C further includes a wave generator 4C disposed inside the flexible externally toothed gear 3C and configured to flex the flexible externally toothed gear 3C. The gear device 1C deforms the flexible externally toothed gear 3C in accordance with the rotation of the wave generator 4C about the rotation axis Ax1, and causes a part of the external teeth 31C to mesh with a part of the internal teeth 21C, thereby causing the flexible externally toothed gear 3C to rotate relative to the rigid internally toothed gear 2C according to the difference in number of teeth from the rigid internally toothed gear 2C. Further, in the skeleton portion 225 of the rigid internally toothed gear 2C (first gear), at least the surface of the internal teeth 21C, which is the external teeth 31C of the other member, that is in sliding contact is covered with the coating layer 224.

In short, in the present embodiment, the rigid internally toothed gear 2C is an example of the "first gear", and therefore, for example, the skeleton portion 225 made of aluminum (Al) is used as a base material of the rigid internally toothed gear 2C. When the flexible externally toothed gear 3C is elastically deformed into an elliptical shape as described above, the external teeth 31C mesh with the internal teeth 21C at 2 portions on both ends of the elliptical shape in the major axis direction. In this way, sliding contact is generated between the inner teeth 21C and the outer teeth 31C at a plurality of meshing sites with the outer teeth 31C in the inner teeth 21C. Therefore, in the rigid internally toothed gear 2C as the first gear, the surface of the internal teeth 21C thereof becomes a sliding contact portion with another member (the external teeth 31C of the flexible externally toothed gear 3C), and thus the surface of the internal teeth 21C is covered with the coating layer 224 made of iron (Fe), for example.

As a modification of the third embodiment, the first gear is not necessarily the rigid internally toothed gear 2C, and the second gear is the flexible externally toothed gear 3C. For example, the first gear may be a flexible externally toothed gear 3C, and the second gear may be a rigid internally toothed gear 2C. In this case, the base material of the flexible externally toothed gear 3C constitutes a skeleton portion, and for example, a sliding contact portion with another member (wave generator 4C) in the flexible externally toothed gear 3C is covered with a coating layer.

The configuration of the third embodiment (including the modification) can be appropriately combined with the various configurations (including the modification) described in the first embodiment or the second embodiment.

(Summary)

As described above, the gear device (1, 1A, 1C) of the first aspect includes the first gear and the second gear. The second gear rotates relative to the first gear by meshing with the first gear. The first gear has a skeleton portion (225) and a coating layer (224) having a specific gravity greater than that of the skeleton portion (225). At least the sliding contact portion with the other member in the skeleton portion (225) is covered with a coating layer (224).

According to this aspect, the skeleton portion (225) of the first gear itself is made of a material having a small specific gravity, and thus, for example, even if it has a corresponding thickness, the weight can be suppressed to be relatively small. On the other hand, since the sliding contact portion (with another member) in the skeleton portion (225) is covered with the coating layer (224) having a specific gravity greater than that of the skeleton portion (225), the sliding contact portion can improve wear resistance and maintain strength as the first gear. As a result, the gear device (1, 1A, 1C) can be realized which is easy to realize light weight while maintaining strength.

In the gear device (1, 1A, 1C) of the second embodiment, the thermal conductivity of the skeleton portion (225) is higher than that of the coating layer (224) in addition to the first embodiment.

According to this aspect, most of the first gear can be constituted by the skeleton portion (225) having high thermal conductivity, and the heat dissipation performance of the first gear can be improved.

In the gear device (1, 1A, 1C) of the third aspect, the coating layer (224) is a sprayed film having a composition different from that of the skeleton portion (225) in addition to the first or second aspect.

According to this aspect, a coating layer 224 having a relatively large film thickness is easily formed.

In the gear device (1, 1A, 1C) according to the fourth aspect, in addition to any one of the first to third aspects, the first gear has a base layer (226) on the surface of the skeleton portion (225), and the coating layer (224) is laminated on the base layer (226).

According to this aspect, the adhesion of the coating layer (224) to the skeleton portion (225) can be improved.

In the gear device (1, 1A, 1C) according to the fifth aspect, in addition to the fourth aspect, the lattice direction of the base layer (226) is a direction based on the sliding direction of the other member in the sliding contact portion.

In the gear device (1, 1A, 1C) of the sixth aspect, the coating layer (224) has a thickness of 50 μm or more in addition to any one of the first to fifth aspects.

According to this aspect, the other member can be prevented from directly contacting the skeleton portion (225) at the sliding contact portion, and abrasion of the skeleton portion (225) can be easily suppressed.

In the gear device (1, 1A, 1C) of the seventh aspect, in the basic row of any one of the first to sixth aspects, the first gear is an internal gear (2), and the second gear is a planetary gear (3). The internal gear (2) has: an annular gear body (22); and a plurality of pins (23) which are rotatably held in a plurality of inner peripheral grooves (223) formed in the inner peripheral surface (221) of the gear body (22) and constitute the internal teeth (21). The planetary gear (3) has external teeth (31) that mesh with the internal teeth (21) locally. The gear devices (1, 1A, 1C) oscillate about a rotation axis (Ax 1) to rotate the planetary gear (3) relative to the internal gear (2). An inner surface of a plurality of inner peripheral grooves (223) in a skeleton portion (225) of an internal gear (2), which are in sliding contact with at least a plurality of pins (23) as another member, is covered with a coating layer (224).

According to this aspect, in the ring gear planetary gear device, it is possible to realize the gear device (1, 1A, 1C) that can be easily reduced in weight while maintaining strength.

In the gear device (1, 1A, 1C) according to the eighth aspect, in addition to any one of the first to sixth aspects, the first gear is an annular rigid internally toothed gear (2C) having internal teeth (21C), and the second gear is an annular flexible externally toothed gear (3C) having external teeth (31C) and disposed inside the rigid internally toothed gear (2C). The gear device (1, 1A, 1C) further includes a wave generator (4C) that is disposed inside the flexible externally toothed gear (3C) and deflects the flexible externally toothed gear (3C). The gear device (1, 1A, 1C) deforms the flexible externally toothed gear (3C) with rotation of the wave generator (4C) centered on the rotation axis (Ax 1), and meshes a part of the external teeth (31C) with a part of the internal teeth (21C), thereby causing the flexible externally toothed gear (3C) to rotate relative to the rigid internally toothed gear (2C) according to the difference in number of teeth with the rigid internally toothed gear (2C). A surface of internal teeth (21C) of a skeleton portion (225) of a rigid internal tooth gear, which is in sliding contact with at least external teeth (31C) of another member, is covered with a coating layer (224).

According to this aspect, in the harmonic gear device, the gear device (1, 1A, 1C) can be easily reduced in weight while maintaining strength.

The ninth aspect of the method for manufacturing a gear device according to any one of the first to eighth aspects includes a plating step of forming a coating layer (224) by plating at least a part of a skeleton portion (225) of the first gear.

According to this aspect, the skeleton portion (225) of the first gear itself is made of a material having a small specific gravity, and thus, for example, even if it has a corresponding thickness, the weight can be suppressed to be relatively small. On the other hand, the sliding contact portion (with another member) in the skeleton portion (225) is covered with a coating layer (224) formed by thermal spraying and having a specific gravity greater than that of the skeleton portion (225), and therefore the sliding contact portion can improve wear resistance and maintain strength as the first gear. As a result, a method for manufacturing a gear device (1, 1A, 1C) that can be easily reduced in weight while maintaining strength can be realized.

The structures of the second to eighth aspects are not required for the gear devices (1, 1A, 1C), and can be omitted appropriately.

Description of the reference numerals

1. 1A (inner gearing planetary) gear device

1C (harmonic) gear device

2 Internal tooth gear (first gear)

2C rigid internal gear (first gear)

3 Planetary gear (second gear)

3C flexible external gear (second gear)

4C wave generator

21. 21C internal teeth

22 Gear body

23 Pin (another component)

31. 31C external teeth (another part)

221 Inner peripheral surface (of gear body)

223. Inner peripheral groove

224. Coating layer

225. Skeleton part

226. Substrate layer

Ax1 rotation shaft

Claims

1. A gear arrangement, comprising:

a first gear;

a second gear which rotates relative to the first gear by meshing with the first gear,

The first gear has a skeleton portion and a coating layer having a larger specific gravity than the skeleton portion,

At least a sliding contact portion of the skeleton portion, which is in sliding contact with the other member, is covered with the coating layer.

2. The gear device according to claim 1, wherein,

The skeleton portion has a higher thermal conductivity than the coating layer.

3. The gear device according to claim 1 or 2, wherein,

The coating layer is a spray coating film having a composition different from that of the skeleton portion.

4. The gear device according to claim 1 or 2, wherein,

The first gear has a base layer on the surface of the skeleton portion, and the coating layer is laminated on the base layer.

5. The gear device according to claim 4, wherein,

The lattice direction of the base layer is a direction based on a sliding direction of the other member at the sliding contact portion.

6. The gear device according to claim 1 or 2, wherein,

The coating layer has a thickness of 50 μm or more.

7. The gear device according to claim 1 or 2, wherein,

The first gear is an internal gear having an annular gear body and a plurality of pins which are rotatably held in a plurality of inner peripheral grooves formed in an inner peripheral surface of the gear body and constitute internal teeth,

The second gear is a planetary gear having external teeth that partially mesh with the internal teeth,

By swinging the planetary gear around a rotation axis, the planetary gear is rotated relative to the internal gear,

The inner surfaces of the plurality of inner peripheral grooves in the skeleton portion of the internal gear, at least as the plurality of pins of the other member, which are in sliding contact, are covered with the coating layer.

8. The gear device according to claim 1 or 2, wherein,

The first gear is a ring-shaped rigid internally toothed gear having internal teeth,

The second gear is an annular flexible externally toothed gear having external teeth and disposed inside the rigid internally toothed gear,

The gear device further includes a wave generator disposed inside the flexible externally toothed gear and configured to flex the flexible externally toothed gear,

In the gear device, the flexible externally toothed gear is deformed in accordance with rotation of the wave generator about a rotation axis, and a part of the external teeth is meshed with a part of the internal teeth, so that the flexible externally toothed gear is rotated relative to the rigid internally toothed gear according to a difference in number of teeth from the rigid internally toothed gear,

At least the surface of the internal teeth in the skeleton portion of the rigid internally toothed gear, which is in sliding contact with the external teeth of the other member, is covered with the coating layer.

9. A method for manufacturing a gear device according to any one of claims 1 to 8, wherein,

The method includes a plating step of forming the coating layer by plating at least a part of the skeleton portion of the first gear.