WO2024124998A1 - 齿轮装置和齿轮装置的制造方法 - Google Patents

齿轮装置和齿轮装置的制造方法 Download PDF

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Publication number
WO2024124998A1
WO2024124998A1 PCT/CN2023/118148 CN2023118148W WO2024124998A1 WO 2024124998 A1 WO2024124998 A1 WO 2024124998A1 CN 2023118148 W CN2023118148 W CN 2023118148W WO 2024124998 A1 WO2024124998 A1 WO 2024124998A1
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Prior art keywords
gear
teeth
rotation axis
planetary gear
internal
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PCT/CN2023/118148
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English (en)
French (fr)
Inventor
其轮宪一
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美的集团股份有限公司
广东美的电气有限公司
广东极亚精机科技有限公司
广东美的制冷设备有限公司
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Application filed by 美的集团股份有限公司, 广东美的电气有限公司, 广东极亚精机科技有限公司, 广东美的制冷设备有限公司 filed Critical 美的集团股份有限公司
Publication of WO2024124998A1 publication Critical patent/WO2024124998A1/zh

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  • the present disclosure generally relates to a gear device and a method for manufacturing the gear device, and more particularly, to a gear device including a first gear and a second gear that rotates relatively with the first gear and a method for manufacturing the gear device.
  • a gear device power transmission device having a sliding portion in which a pair of sliding members slide against each other
  • the gear device is an inscribed swing meshing type planetary gear device, which has an input shaft, an eccentric body integrated with the input shaft, an external gear that swings and rotates through the eccentric body, an internal gear including internal teeth that mesh with the external gear, and a flange body that is arranged on the axial outer side of the external gear and connected to an inner pin that extracts the rotation component of the external gear.
  • At least one of two opposing sliding surfaces of a pair of sliding members such as the holding surfaces at both ends of an outer pin forming an internal tooth and the surfaces opposite to the holding surfaces at both ends of the outer pin, has a surface roughness formed by a predetermined roughness process and a carbon-based film.
  • the carbon-based film is added with a metal element and is formed on the surface roughness.
  • Patent Document 1 Japanese Patent Application Publication No. 2009-41747
  • the base material of the sliding member such as the first gear (internal gear) is made of metal, and a corresponding thickness is required for roughening, and the weight is relatively large, which may hinder the weight reduction of the entire wheel device.
  • An object of the present disclosure is to provide a gear device and a method for manufacturing the gear device that can easily achieve weight reduction while maintaining strength.
  • a gear device of one form of the present disclosure 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 part and a coating layer with a specific gravity greater than that of the skeleton part. At least a sliding contact part of the skeleton part that is in sliding contact with another component is covered by the coating layer.
  • a method for manufacturing a gear device is the method for manufacturing the gear device, comprising a thermal spraying step of forming the coating layer on at least a portion of the skeleton portion of the first gear by thermal spraying.
  • FIG. 1 is a perspective view showing a schematic structure of an actuator including an internally meshing planetary gear device according to a first embodiment.
  • FIG. 2 is a schematic exploded perspective view of the internally meshing planetary gear device as viewed from the output side of the rotating shaft.
  • FIG. 3 is a schematic cross-sectional view of the internally meshing planetary gear device described above.
  • FIG. 4 is a cross-sectional view taken along line A1 - A1 of FIG. 3 , showing the internally meshing planetary gear device described above.
  • FIG. 5A is a perspective view showing a planetary gear of the internally meshing planetary gear device as a single body.
  • FIG. 5B is a front view showing the planetary gear of the internally meshing planetary gear device as a single body.
  • FIG. 6A is a perspective view showing a bearing member of the internally meshing planetary gear device as a single body.
  • FIG. 6B is a front view showing the bearing member of the internally meshing planetary gear device as a single body.
  • FIG. 7A is a perspective view showing the eccentric shaft of the internally meshing planetary gear device as a single body.
  • FIG. 7B is a front view showing the eccentric shaft of the internally meshing planetary gear device as a single body.
  • FIG. 8A is a perspective view showing the support body of the internally meshing planetary gear device as a single body.
  • FIG. 8B is a front view showing the support body of the internally meshing planetary gear device as a single body.
  • FIG. 9 is an enlarged view of the region Z1 of FIG. 3 , showing the internally meshing planetary gear device described above.
  • FIG. 10 is a cross-sectional view taken along line B1 - B1 of FIG. 3 , showing the internally meshing planetary gear device described above.
  • FIG. 11 is an enlarged schematic cross-sectional view showing the meshing portion between the internal teeth 21 and the external teeth 31 of FIG. 9 , showing the internal meshing planetary gear device described above.
  • FIG. 12 is a schematic diagram showing a cross section of the internally meshing planetary gear device described above, taken along the line A1 - A1 of FIG. 11 .
  • FIG. 13A is a schematic perspective view showing an inner peripheral groove of an internal gear of the internally meshing planetary gear device.
  • FIG. 13B is a schematic perspective view showing an inner peripheral groove of an internal gear of the internally meshing planetary gear device.
  • FIG. 14 is a perspective view showing a schematic structure of an internally meshing planetary gear device according to a second embodiment.
  • FIG. 15 is an exploded perspective view of the internally meshing planetary gear device as viewed from the input side of the rotating shaft.
  • FIG. 16 is a schematic cross-sectional view of the internally meshing planetary gear device described above.
  • 17 is a cross-sectional view showing a schematic structure of a wave gear device according to a first comparative example of the third embodiment.
  • FIG. 18 is a schematic diagram of the above-mentioned wave gear device as viewed from the input side of the rotating shaft.
  • FIG. 19 is a schematic exploded perspective view of the above-mentioned wave gear device as viewed from the output side of the rotating shaft.
  • FIG. 20 is a schematic exploded perspective view of the above-mentioned harmonic gear device as viewed from the input side of the rotating shaft. Body diagram.
  • FIGS. 1 to 3 The drawings referred to in the embodiments of the present disclosure are all schematic drawings, and the size and thickness ratios of the structural elements in the drawings do not necessarily reflect the actual size ratios.
  • the tooth shape, size, and number of teeth of the internal teeth 21 and the external teeth 31 in FIGS. 1 to 3 are only schematically shown for the purpose of explanation, and the subject matter is not limited to the shapes shown in the drawings.
  • the internal meshing planetary gear device (hereinafter also referred to as "gear device 1") of the present embodiment is a gear device including an internal gear 2, planetary gears 3, and a plurality of inner pins 4.
  • the planetary gears 3 are arranged inside the annular internal gear 2, and the eccentric body bearing 5 is arranged inside the planetary gear 3.
  • the eccentric body bearing 5 includes an eccentric inner ring 51 and an eccentric outer ring 52.
  • the eccentric inner ring 51 rotates (eccentrically moves) around the rotation axis Ax1 (see FIG. 3) deviated from the center C1 (see FIG. 3) of the eccentric inner ring 51, thereby causing the planetary gear 3 to swing.
  • the eccentric inner ring 51 rotates (eccentrically moves) around the rotation axis Ax1 by, for example, the rotation of the eccentric shaft 7 inserted into the eccentric inner ring 51.
  • the internal meshing planetary gear device 1 further includes a bearing member 6, and the bearing member 6 includes an outer ring 62 and an inner ring 61.
  • the inner ring 61 is arranged inside the outer ring 62 and supported so as to be relatively rotatable relative to the outer ring 62.
  • the internal gear 2 has internal teeth 21 and is fixed to the outer ring 62.
  • the internal gear 2 has an annular gear body 22 and a plurality of pins 23.
  • the plurality of pins 23 are held on the inner circumferential surface 221 of the gear body 22 in a rotatable state to form the internal teeth 21.
  • the planetary gear 3 has external teeth 31 that partially mesh with the internal teeth 21. That is, on the inner side of the internal gear 2, the planetary gear 3 is inscribed in the internal gear 2, so that a portion of the external teeth 31 meshes with a portion of the internal teeth 21.
  • This gear device 1 is used in the following manner: the rotation corresponding to the self-rotation component of the planetary gear 3 is extracted as the rotation of the output shaft integrated with the inner ring 61 of the bearing member 6, for example.
  • the gear device 1 functions as a gear device with a relatively high reduction ratio, with the eccentric shaft 7 as the input side and the output shaft as the output side. Therefore, in the gear device 1 of the present embodiment, the planetary gear 3 and the inner ring 61 are connected by a plurality of inner pins 4 in order to transmit the rotation corresponding to the self-rotation component of the planetary gear 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 they rotate relative to the internal gear 2 while revolving in 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 can move in a manner of revolving in the inner pin hole 32 while being inserted in the inner pin hole 32.
  • the swing component of the planetary gear 3, that is, the orbital component of the planetary gear 3 is absorbed by the loose fit between the inner pin hole 32 of the planetary gear 3 and the inner pin 4.
  • the plurality of inner pins 4 move in a manner of revolving in the plurality of inner pin holes 32, respectively, thereby absorbing the swing component of the planetary gear 3. Therefore, the rotation (autorotation 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 through the plurality of inner pins 4.
  • the inner pin 4 revolves in the inner pin hole 32 of the planetary gear 3 while transmitting the rotation of the planetary gear 3 to the plurality of inner pins 4, so as a first related technology
  • a known technology that uses an inner roller that is mounted on the inner pin 4 and can rotate around the inner pin 4 as an axis. That is, in the first related technology, the inner pin 4 is kept in a state of being pressed into the inner ring 61 (or a bracket integrated with the inner ring 61), and when the inner pin 4 revolves in the inner pin hole 32, the inner pin 4 slides relative to the inner circumferential surface 321 of the inner pin hole 32.
  • an inner roller is used to reduce the loss caused by the friction resistance between the inner circumferential surface 321 of the inner pin hole 32 and the inner pin 4.
  • the inner pin hole 32 needs to have a diameter that allows the inner pin 4 with the inner roller to revolve, and it is difficult to miniaturize the inner pin hole 32. If it is difficult to miniaturize the inner pin hole 32, it will hinder the miniaturization of the planetary gear 3 (especially the reduction in diameter), and even hinder the miniaturization of the entire gear device 1.
  • the gear device 1 of this type can provide an internally meshing planetary gear device 1 that can be easily miniaturized by the following structure.
  • 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 inner pins 4.
  • the bearing member 6 has an outer ring 62 and an inner ring 61 disposed inside the outer ring 62.
  • the inner ring 61 is supported so as to be relatively rotatable relative to the outer ring 62.
  • the internal gear 2 has internal teeth 21 and is fixed to the outer ring 62.
  • the planetary gear 3 has external teeth 31 partially meshing 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, respectively, and rotate relative to the internal gear 2 while revolving in the inner pin holes 32.
  • each of the plurality of inner pins 4 is held in the inner ring 61 in a rotatable state. Furthermore, each of the plurality of inner pins 4 is at least partially disposed at the same position as the bearing member 6 in the axial direction of the bearing member 6.
  • each of the plurality of inner pins 4 is held by the inner ring 61 in a state in which it can rotate, so when the inner pin 4 revolves in the inner pin hole 32, the inner pin 4 itself can rotate. Therefore, even if an inner roller that is mounted on the inner pin 4 and can rotate with the inner pin 4 as an axis is not used, the loss caused by the friction resistance between the inner circumferential surface 321 of the inner pin hole 32 and the inner pin 4 can be reduced. Therefore, for the gear device 1 of this embodiment, the inner roller is not necessary, so there is an advantage of easy miniaturization.
  • each of the plurality of inner pins 4 is at least partially arranged at the same position as the bearing member 6 in the axial direction of the bearing member 6, so the size of the gear device 1 in the axial direction of the bearing member 6 can be suppressed to be small. That is, compared with a structure in which the bearing member 6 and the inner pin 4 are arranged side by side (opposite) in the axial direction of the bearing member 6, in the gear device 1 of this embodiment, the size of the gear device 1 in the axial direction can be reduced, thereby contributing to further miniaturization (thinning) of the gear device 1.
  • the number of inner pins 4 can be increased to smooth the transmission of rotation, or the inner pins 4 can be thickened to increase strength.
  • the inner pin 4 needs to revolve in the inner pin hole 32 of the planetary gear 3, so as a second related technology, there are cases where multiple inner pins 4 are only held by the inner ring 61 (or a bracket integrated with the inner ring 61). According to the second related technology, it is difficult to improve the centering accuracy of multiple inner pins 4, and poor centering may cause vibration and reduce transmission efficiency. In other words, the plurality of inner pins 4 rotate relative to the internal gear 2 while revolving in the inner pin hole 32, thereby transmitting the rotation component of the planetary gear 3 to the inner ring 61 of the bearing member 6.
  • the gear device 1 of this embodiment can provide an internal meshing planetary gear device 1 that is less likely to cause undesirable conditions caused by poor centering of the plurality of inner pins 4 through the following structure.
  • the gear device 1 of the present embodiment includes an internal gear 2, a planetary gear 3, a plurality of inner pins 4, and a support body 8.
  • the internal gear 2 has an annular gear body 22 and a plurality of pins 23.
  • the plurality of pins 23 are held on the inner circumferential surface 221 of the gear body 22 in a rotatable state to form the internal teeth 21.
  • the planetary gear 3 has external teeth 31 partially meshing 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, respectively, and rotate relative to the gear body 22 while revolving in 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 positionally restricted by bringing the outer circumferential surface 81 into contact with the plurality of pins 23.
  • the plurality of inner pins 4 are supported by the annular support body 8, so the plurality of inner pins 4 are bundled by the support body 8, and the relative deviation 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, thereby limiting the position of the support body 8.
  • 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 this embodiment, it is easy to improve the accuracy of centering of the plurality of inner pins 4, and it has the advantage that it is difficult to produce adverse conditions caused by poor centering of the plurality of inner pins 4.
  • the gear device 1 of the present embodiment together with the drive source 101 constitutes an actuator 100.
  • the actuator 100 of the present embodiment includes the gear device 1 and the drive source 101.
  • the drive source 101 generates a driving force for swinging the planetary gear 3. Specifically, the drive source 101 rotates the eccentric shaft 7 about the rotation axis Ax1, thereby swinging the planetary gear 3.
  • ring-shaped refers to a shape that forms a circle (ring) with a space (region) enclosed inside at least when viewed from above, and is not limited to a circular shape (ring-shaped) that is a perfect circle when viewed from above. For example, it may be an elliptical shape or a polygonal shape, etc. Furthermore, even if it is a shape having a bottom such as a cup shape, as long as its peripheral wall is annular, it is included in the "annular shape".
  • the "loose fitting” mentioned in the present disclosure refers to a state of being fitted with play (gap), and the inner pin hole 32 is a hole for the inner pin 4 to be loosely fitted. That is, the inner pin 4 is inserted into the inner pin hole 32 in a state where a margin of space (gap) is ensured between the inner circumferential surface 321 of the inner pin hole 32. In other words, the diameter of at least the portion of the inner pin 4 inserted into the inner pin hole 32 is smaller (thinner) than the diameter of the inner pin hole 32. Therefore, the inner pin 4 can move in the inner pin hole 32 while being inserted in the inner pin hole 32, that is, it can move relative to the center of the inner pin hole 32.
  • the inner pin 4 can revolve in the inner pin hole 32.
  • the gap can be filled with a fluid such as a liquid.
  • volution refers to the rotation of an object around a rotation axis other than the central axis passing through the center (center of gravity) of the object.
  • the center of the object moves along a revolution orbit centered on the rotation axis. Therefore, for example, when an object rotates around an eccentric axis parallel to the central axis passing through the center (center of gravity) of the object, the object revolves around the eccentric axis as the rotation axis.
  • the inner pin 4 revolves in the inner pin hole 32 around the rotation axis passing through the center of the inner pin hole 32.
  • one side of the rotation axis Ax1 (the left side of FIG. 3 ) is referred to as the “input side”, and the other side of the rotation axis Ax1 (the right side of FIG. 3 ) is referred to as the “output side”.
  • rotation is imparted to the rotating body (eccentric body inner ring 51) from the “input side” of the rotation axis Ax1, and rotation of the plurality of inner pins 4 (inner ring 61) is taken out from the “output side” of the rotation axis Ax1.
  • the “input side” and “output side” are merely labels given for the purpose of explanation, and their purpose does not limit the positional relationship between the input and the output as viewed from the gear device 1.
  • the "rotation axis" referred to in the present disclosure refers to a virtual axis (straight line) that is the center of rotation of a rotating body. That is, the rotation axis Ax1 is a virtual axis without a physical body.
  • the eccentric body inner ring 51 rotates around the rotation axis Ax1.
  • the "internal teeth” and “external teeth” respectively refer to a collection (group) of multiple “teeth” rather than a single “tooth”. That is, the internal teeth 21 of the internal gear 2 are composed of a collection of multiple teeth arranged on the inner circumferential surface 221 of the internal gear 2 (gear body 22). Similarly, the external teeth 31 of the planetary gear 3 are It is composed of a set of multiple teeth arranged on the outer peripheral surface of the planetary gear 3.
  • FIG. 1 is a perspective view showing a schematic structure of an actuator 100 including a gear device 1.
  • a driving source 101 is schematically shown.
  • FIG. 2 is a schematic exploded perspective view of the gear device 1 as viewed from the output side of the rotating shaft Ax1.
  • FIG. 3 is a schematic cross-sectional view of the gear device 1.
  • FIG. 4 is a cross-sectional view taken along the A1-A1 line of FIG. 3 .
  • the section lines are omitted.
  • the illustration of the inner circumferential surface 221 of the gear body 22 is omitted.
  • FIG. 5B are a perspective view and a front view showing the planetary gear 3 as a single body.
  • FIG. 6A and FIG. 6B are a perspective view and a front view showing the bearing member 6 as a single body.
  • FIG. 7A and FIG. 7B are a perspective view and a front view showing the eccentric shaft 7 as a single body.
  • FIG. 8A and FIG. 8B are a perspective view and a front view showing the support body 8 as a single body.
  • the gear device 1 of the present embodiment includes an internal gear 2, a planetary gear 3, a plurality of inner pins 4, an eccentric bearing 5, a bearing member 6, an eccentric shaft 7, and a support 8.
  • the gear device 1 further includes a first bearing 91, a second bearing 92, and a housing 10.
  • the internal gear 2, the planetary gear 3, the plurality of inner pins 4, the eccentric bearing 5, the bearing member 6, the eccentric shaft 7, and the support 8, which are structural elements of the gear device 1, are made of metals such as stainless steel, cast iron, carbon steel for mechanical structures, chrome-molybdenum steel, phosphor bronze or aluminum bronze, or light metals such as aluminum or titanium.
  • the metal (including light metal) mentioned here includes metals subjected to surface treatment such as nitriding treatment.
  • the gear body 22 of the internal gear 2 is made of aluminum.
  • an inscribed planetary gear reduction device using a cycloid tooth profile is exemplified as an example of the gear device 1. That is, the gear device 1 of the present embodiment includes an inscribed planetary gear 3 having a cycloid tooth profile.
  • the gear device 1 is used in a state where the gear body 22 of the internal gear 2 and the outer ring 62 of the bearing member 6 are fixed to a fixed member such as a housing 10.
  • a fixed member such as a housing 10.
  • the planetary gear 3 is moved relative to the fixed member (housing). body 10, etc.) rotates relative to each other.
  • the gear device 1 when the gear device 1 is used in the actuator 100, a rotational force as an input is applied to the eccentric shaft 7, thereby taking out a rotational force as an output from the output shaft integrated with the inner ring 61 of the bearing member 6. That is, the gear device 1 operates with the rotation of the eccentric shaft 7 as the input rotation and the rotation of the output shaft integrated with the inner ring 61 as the output rotation. As a result, in the gear device 1, an output rotation that is reduced in speed at a relatively high reduction ratio relative to the input rotation can be obtained.
  • the driving source 101 is a power generating source such as a motor (electric motor).
  • the power generated by the driving source 101 is transmitted to the eccentric shaft 7 in the gear device 1.
  • the driving source 101 is connected to the eccentric shaft 7 via an input shaft, and the power generated by the driving source 101 is transmitted to the eccentric shaft 7 via the input shaft.
  • the driving source 101 can rotate the eccentric shaft 7.
  • the rotation axis Ax1 on the input side and the rotation axis Ax1 on the output side are on the same straight line.
  • the rotation axis Ax1 on the input side and the rotation axis Ax1 on the output side are coaxial.
  • the rotation axis Ax1 on the input side is the rotation center of the eccentric shaft 7 to which the input rotation is given
  • the rotation axis Ax1 on the output side 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 reduced at a relatively high reduction ratio on the same axis relative to the input rotation.
  • the internal gear 2 is an annular component having internal teeth 21.
  • the internal gear 2 has an annular shape whose at least inner circumference is a perfect circle when viewed from above.
  • internal teeth 21 are formed along the circumferential direction of the internal gear 2.
  • the plurality of teeth constituting the internal teeth 21 are all of the same shape and are arranged at equal intervals over the entire area of the inner circumferential direction of the internal gear 2.
  • the pitch circle of the internal teeth 21 is a perfect circle when viewed from above.
  • the center of the pitch circle of the internal teeth 21 is on the rotation axis Ax1.
  • the internal gear 2 has a predetermined thickness along the direction of the rotation axis Ax1.
  • the tooth directions of the internal teeth 21 are all parallel to the rotation axis Ax1.
  • the dimension of the internal teeth 21 in the tooth direction is slightly smaller than that in the thickness direction of the internal gear 2.
  • the internal gear 2 has an annular (circular) gear body 22 and a plurality of pins 23.
  • the plurality of pins 23 are held on the inner circumferential surface 221 of the gear body 22 in a rotatable state to form the internal teeth 21.
  • the plurality of pins 23 function as a plurality of teeth constituting the internal teeth 21.
  • a plurality of inner circumferential grooves 223 are formed on the inner circumferential surface 221 of the gear body 22 over the entire area in the circumferential direction.
  • the plurality of inner circumferential grooves 223 are all of the same shape and are arranged at equal intervals.
  • the plurality of inner circumferential grooves 223 are all parallel to the rotation axis Ax1 and are formed over the entire length of the thickness direction of the gear body 22.
  • the plurality of pins 23 are combined with the gear body 22 in a manner embedded in the plurality of inner circumferential grooves 223.
  • Each of the plurality of pins 23 is maintained in a state capable of rotating within the inner circumferential grooves 223.
  • the gear body 22 (together with the outer ring 62) is fixed to the housing 10. Therefore, a plurality of fixing holes 222 for fixing are formed in the gear body 22.
  • the planetary gear 3 is an annular component having external teeth 31.
  • the planetary gear 3 has an annular shape in which at least the outer peripheral surface is a perfect circle when viewed from above.
  • the external teeth 31 are formed 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 arranged at equal intervals in the entire area of the circumferential direction of the outer peripheral surface of the external gear 3.
  • the pitch circle of the external teeth 31 is a perfect circle when viewed from above.
  • the center C1 of the pitch circle of the external teeth 31 is located at a position that is offset from the rotation axis Ax1 by a distance ⁇ L (refer to FIG. 4 ).
  • the planetary gear 3 has a predetermined thickness in the direction of the rotation axis Ax1.
  • 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 Ax1.
  • the external teeth 31 and the main body of the planetary gear 3 are formed integrally by a metal member.
  • the planetary gear 3 is combined with an eccentric body bearing 5 and an eccentric shaft 7. That is, an opening portion 33 opening in a circular shape is formed in the planetary gear 3.
  • the opening portion 33 is a hole that penetrates the planetary gear 3 in the thickness direction.
  • the center of the opening portion 33 coincides with the center of the planetary gear 3, and the inner circumferential surface of the opening portion 33 (the inner circumferential surface of the planetary gear 3) is concentric with the pitch circle of the external tooth 31.
  • the eccentric body bearing 5 is accommodated in the opening portion 33 of the planetary gear 3.
  • the eccentric body bearing 5 and the eccentric shaft 7 are combined with the planetary gear 3 by inserting the eccentric shaft 7 into the eccentric body bearing 5 (the eccentric body inner ring 51).
  • the planetary gear 3 swings around the rotation axis Ax1.
  • the planetary gear 3 thus constructed is arranged inside the internal gear 2.
  • the planetary gear 3 is formed to be one size smaller than the internal gear 2, and the planetary gear 3 can swing inside the internal gear 2 when combined with the internal gear 2.
  • the outer circumferential surface of the planetary gear 3 is formed with external teeth 31, and the inner circumferential surface of the internal gear 2 is formed with internal teeth 21. Therefore, the planetary gear 3 is arranged inside the internal gear 2. In the state of the gear 3, the external teeth 31 and the internal teeth 21 are opposed to each other.
  • the pitch circle of the external teeth 31 is one circle smaller than the pitch circle of the internal teeth 21.
  • the center C1 of the pitch circle of the external teeth 31 is located at a position offset by a distance ⁇ L (refer to FIG. 4 ) from the center of the pitch circle of the internal gear 21 (rotation axis Ax1). Therefore, the external teeth 31 and at least a portion of the internal teeth 21 are opposite to each other with a gap therebetween, and there is no overall mutual meshing in the circumferential direction.
  • the planetary gear 3 swings (revolves) around the rotation axis Ax1 inside the internal gear 2, so the external teeth 31 are partially meshed with the internal teeth 21.
  • 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.
  • N is "1”
  • the number of teeth (of the external teeth 31) of the planetary gear 3 is "1" greater than the number of teeth (of the internal teeth 21) of the internal gear 2.
  • Such a difference in the number of teeth between the planetary gear 3 and the internal gear 2 defines the reduction ratio of the output rotation relative to the input rotation in the gear device 1.
  • the thickness of the planetary gear 3 is smaller than the thickness of the gear body 22 in the internal gear 2. Furthermore, the dimension of the tooth direction (direction parallel to the rotation axis Ax1) of the external teeth 31 is smaller than the dimension of the tooth direction (direction parallel to the rotation axis Ax1) of the internal teeth 21. In other words, in the direction parallel to the rotation axis Ax1, the external teeth 31 are within the range of the tooth direction of the internal teeth 21.
  • the rotation of the planetary gear 3 corresponding to the self-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 connected to the inner ring 61 by means of a plurality of inner pins 4.
  • a plurality of inner pin holes 32 for inserting a plurality of inner pins 4 are formed in the planetary gear 3.
  • the same number of inner pin holes 32 as the number of inner pins 4 are provided.
  • 18 inner pin holes 32 and 18 inner pins 4 are provided respectively.
  • Each of the plurality of inner pin holes 32 is a hole that opens in a circular shape and penetrates the planetary gear 3 in the thickness direction.
  • a plurality of (here 18) 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 are components for connecting the planetary gear 3 and the inner ring 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 among the plurality of inner pins 4.
  • the diameter of the inner pin 4 is slightly smaller than the diameter of the inner pin hole 32.
  • the bearing member 6 has an outer ring 62 and an inner ring 61 and is used to extract the output of the gear device 1 as the rotation of the inner ring 61 relative to the outer ring 62.
  • the bearing member 6 has a plurality of rolling elements 63 in addition to the outer ring 62 and the inner ring 61 (see FIG. 3 ).
  • the outer ring 62 and the inner ring 61 are both annular components.
  • the outer ring 62 and the inner ring 61 both have an annular shape that is a perfect circle when viewed from above.
  • the inner ring 61 is one circle smaller than the outer ring 62 and is arranged on the inner side of the outer ring 62.
  • the inner diameter of the outer ring 62 is larger than the outer diameter of the inner ring 61, a gap is generated between the inner peripheral surface of the outer ring 62 and the outer peripheral surface of the inner ring 61.
  • the inner ring 61 has a plurality of retaining holes 611 into which the plurality of inner pins 4 are respectively inserted.
  • the retaining holes 611 are provided in the same number as the inner pins 4.
  • 18 retaining holes 611 are provided.
  • each of the plurality of retaining holes 611 is a hole that opens in a circular shape and penetrates the inner ring 61 in the thickness direction.
  • the plurality of (here 18) retaining holes 611 are arranged at equal intervals in the circumferential direction on a virtual circle concentric with the outer periphery of the inner ring 61.
  • the diameter of the retaining hole 611 is greater than the diameter of the inner pin 4 and smaller than the diameter of the inner pin hole 32.
  • the inner ring 61 is integrated with the output shaft, and the rotation of the inner ring 61 is taken as the rotation of the output shaft. Therefore, a plurality of output side mounting holes 612 (see FIG. 2 ) for mounting the output shaft are formed in the inner ring 61.
  • the plurality of output side mounting holes 612 are located further inward than the plurality of retaining holes 611, and are arranged on a virtual circle concentric with the outer circumference of the inner ring 61.
  • the outer ring 62 is fixed to a fixed member such as a housing 10 together with the gear body 22 of the internal gear 2. Therefore, 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 screws (bolts) 60 for fixing that pass through the through holes 621 and the fixing holes 222 of the gear body 22, with the gear body 22 sandwiched between the outer ring 62 and the housing 10.
  • the plurality of rolling elements 63 are arranged in the gap between the outer ring 62 and the inner ring 61.
  • the plurality of rolling elements 63 are arranged in parallel along the circumferential direction of the outer ring 62.
  • the plurality of rolling elements 63 are all metal parts of the same shape and are arranged at equal intervals over the entire circumferential area of the outer ring 62.
  • the bearing member 6 is a cross roller bearing.
  • the bearing member 6 has a cylindrical roller as a rolling element 63.
  • the axis of the cylindrical rolling element 63 is inclined at 45 degrees relative to a plane perpendicular to the rotation axis Ax1, and is perpendicular to the outer periphery of the inner ring 61.
  • a pair of rolling elements 63 adjacent to each other in the circumferential direction of the inner ring 61 are arranged in directions perpendicular to each other in the axial direction.
  • the eccentric shaft 7 is a cylindrical component.
  • the eccentric shaft 7 has an axial portion 71 and an eccentric portion 72.
  • the axial portion 71 has a cylindrical shape in which at least the outer peripheral surface is a perfect circle when viewed from above.
  • the center (central axis) of the axial portion 71 coincides with the rotation axis Ax1.
  • the eccentric portion 72 has a disc shape in which at least the outer peripheral surface is a perfect circle when viewed from above.
  • the center (central axis) of the eccentric portion 72 coincides with the center C1 deviated from the rotation axis Ax1.
  • the distance ⁇ L between the rotation axis Ax1 and the center C1 (refer to Fig.
  • the eccentric portion 72 becomes the eccentricity of the eccentric portion 72 relative to the axial portion 71.
  • the eccentric portion 72 is in the shape of a flange protruding from the outer peripheral surface of the axial portion 71 all around the central portion in the longitudinal direction (axial direction) of the axial portion 71. According to the above-described configuration, in the eccentric shaft 7 , the eccentric portion 72 performs eccentric motion as the shaft center portion 71 rotates (rotates) about the rotation axis Ax1 .
  • the axial portion 71 and the eccentric portion 72 are integrally formed by one metal member, thereby realizing a seamless eccentric shaft 7.
  • the eccentric shaft 7 of 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 where 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 axis Ax1.
  • the eccentric shaft 7 has a through hole 73 that penetrates the shaft core portion 71 in the axial direction (length direction).
  • the through hole 73 is open in a circular shape at both end surfaces in the axial direction of the shaft core portion 71.
  • the center (central axis) of the through hole 73 coincides with the rotation axis Ax1. Cables such as power lines and signal lines can be passed through the through hole 73.
  • a rotational force as an input is applied from the driving source 101 to the eccentric shaft 7. Therefore, a plurality of input side mounting holes 74 (see FIGS. 7A and 7B ) for mounting an input shaft connected to the driving source 101 are formed in the eccentric shaft 7.
  • the portion 71 is disposed around the through hole 73 on one axial end surface thereof and on a virtual circle concentric with the through hole 73 .
  • the eccentric body bearing 5 is a component that has an eccentric outer ring 52 and an eccentric inner ring 51, absorbs the rotation component of the eccentric shaft 7, and is used to transmit only the rotation of the eccentric shaft 7 other than the rotation component of the eccentric shaft 7, that is, the swing component (revolution component) of the eccentric shaft 7 to the planetary gear 3.
  • the eccentric body bearing 5 also has a plurality of rolling elements 53 (see FIG. 3 ).
  • the eccentric outer ring 52 and the eccentric inner ring 51 are both annular components.
  • the eccentric outer ring 52 and the eccentric inner ring 51 both have an annular shape that is a perfect circle when viewed from above.
  • the eccentric inner ring 51 is one circle smaller than the eccentric outer ring 52 and is arranged on the inner side of the eccentric outer ring 52.
  • the inner diameter of the eccentric outer ring 52 is larger than the outer diameter of the eccentric inner ring 51, so a gap is generated between the inner peripheral surface of the eccentric outer ring 52 and the outer peripheral surface of the eccentric inner ring 51.
  • a plurality of rolling elements 53 are arranged in the gap between the eccentric outer ring 52 and the eccentric inner ring 51.
  • the plurality of rolling elements 53 are arranged side by side along the circumferential direction of the eccentric outer ring 52.
  • the plurality of rolling elements 53 are all metal parts of the same shape and are arranged at equal intervals in the entire area of the eccentric outer ring 52 in the circumferential direction.
  • the eccentric body bearing 5 is composed of a deep groove ball bearing using balls as rolling elements 53.
  • the inner diameter of the eccentric body inner ring 51 is consistent 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 where 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 is consistent with the inner diameter (diameter) of the opening portion 33 in the planetary gear 3.
  • the eccentric body bearing 5 is combined with the planetary gear 3 in a state where the eccentric body outer ring 52 is embedded in the opening portion 33 of the planetary gear 3. In other words, the eccentric body bearing 5 in a state where the eccentric portion 72 of the eccentric shaft 7 is assembled is accommodated in the opening portion 33 of the planetary gear 3.
  • the dimension of the eccentric body inner ring 51 in the eccentric body bearing 5 in the width direction is substantially the same as the thickness of the eccentric portion 72 of the eccentric shaft 7.
  • the dimension of the eccentric body outer ring 52 in the width direction is slightly smaller than the dimension of the eccentric body inner ring 51 in the width direction.
  • the dimension of the eccentric body outer ring 52 in the width direction is The eccentric outer ring 52 has a width dimension that is smaller than the thickness of the planetary gear 3. Therefore, in the direction parallel to the rotation axis Ax1, the planetary gear 3 is contained within the range of the eccentric bearing 5.
  • the dimension in the width direction of the eccentric outer ring 52 is smaller than the dimension in the tooth direction (direction parallel to the rotation axis Ax1) of the internal teeth 21. Therefore, in the direction parallel to the rotation axis Ax1, the eccentric bearing 5 is contained within the range of the internal gear 2.
  • the support body 8 is a member formed in an annular shape and supporting a plurality of inner pins 4.
  • the support body 8 has a plurality of support holes 82 for inserting the plurality of inner pins 4.
  • the number of support holes 82 is the same as the number of inner pins 4, and in this embodiment, as an example, 18 support holes 82 are provided.
  • each of the plurality of support holes 82 is a hole that opens in a circular shape and penetrates the support body 8 in the thickness direction.
  • a 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 greater than the diameter of the inner pin 4 and smaller than the diameter of the inner pin hole 32.
  • the diameter of the support hole 82 is equal to the diameter of the retaining hole 611 formed in the inner ring 61.
  • the support body 8 is arranged in a manner opposite to the planetary gear 3 from one side (input side) of the rotation axis Ax1. Furthermore, by inserting a plurality of inner pins 4 into a plurality of support holes 82, the support body 8 functions in a manner of bundling the plurality of inner pins 4. Furthermore, the support body 8 is positionally restricted by bringing the outer peripheral surface 81 into contact with the plurality of pins 23. Thus, 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 supported body 8 are also centered by the plurality of pins 23.
  • the support body 8 is described in detail in the "(3.3) Support body” column.
  • the first bearing 91 and the second bearing 92 are respectively mounted on the axial center portion 71 of the eccentric shaft 7. Specifically, as shown in FIG. 3 , the first bearing 91 and the second bearing 92 sandwich the eccentric shaft 7 in a direction parallel to the rotation axis Ax1.
  • the eccentric portion 72 is assembled on both sides of the eccentric portion 72 in the shaft portion 71.
  • the first bearing 91 is arranged on the input side of the rotation axis Ax1.
  • the second bearing 92 is arranged on the output side of the rotation axis Ax1.
  • the first bearing 91 holds the eccentric shaft 7 so that it can rotate relative to the housing 10.
  • the second bearing 92 holds the eccentric shaft 7 so that it can rotate relative to the inner ring 61 of the bearing member 6.
  • the shaft portion 71 of the eccentric shaft 7 is held rotatably at two locations on both sides of the eccentric portion 72 in a direction parallel to the rotation axis Ax1.
  • the housing 10 is cylindrical and has a flange 11 on the output side of the rotation axis Ax1.
  • a plurality of setting holes 111 for fixing the housing 10 itself are formed in the flange 11.
  • a bearing hole 12 is formed on the end surface on the output side of the rotation axis Ax1 in the housing 10.
  • the bearing hole 12 opens in a circular shape.
  • the first bearing 91 is mounted on the housing 10 by inserting the first bearing 91 into the bearing hole 12.
  • a plurality of threaded holes 13 are formed on the end surface of the housing 10 on the output side of the rotation axis Ax1 and around the bearing hole 12.
  • the plurality of threaded holes 13 are used to fix the gear body 22 of the internal gear 2 and the outer ring 62 of the bearing member 6 to the housing 10.
  • the fixing screws 60 are passed through the through holes 621 of the outer ring 62 and the fixing holes 222 of the gear body 22 and are tightened into the threaded holes 13, thereby fixing the gear body 22 and the outer ring 62 to the housing 10.
  • the gear device 1 of the present embodiment further includes a plurality of oil seals 14, 15, 16, etc.
  • the oil seal 14 is mounted on the end of the input side of the rotation axis Ax1 of the eccentric shaft 7, and fills the gap between the housing 10 and the eccentric shaft 7 (axial center portion 71).
  • the oil seal 15 is mounted on the end of the output side of the rotation axis Ax1 of the eccentric shaft 7, and fills the gap between the inner ring 61 and the eccentric shaft 7 (axial center portion 71).
  • the oil seal 16 is mounted on the end surface of the output side of the rotation axis Ax1 of the bearing member 6, and fills the gap between the inner ring 61 and the outer ring 62.
  • the space sealed by these plurality of oil seals 14, 15, 16 constitutes a lubricant retaining space 17 (refer to FIG. 9 ).
  • the lubricant retaining space 17 includes the space between the inner ring 61 and the outer ring 62 of the bearing member 6. Furthermore, the lubricant retaining space 17 contains a 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, etc.
  • lubricant is sealed in the lubricant holding space 17.
  • the lubricant is a liquid and can flow in the lubricant holding space 17. Therefore, when the gear device 1 is used, for example, the lubricant enters the meshing portion between the internal teeth 21 formed by the plurality of pins 23 and the external teeth 31 of the planetary gear 3.
  • the "liquid The term "gel” refers to a state having properties intermediate between liquid and solid, including a colloid state consisting of two phases, a liquid phase and a solid phase.
  • an emulsion in which the dispersant is a liquid phase and the dispersed phase is a liquid phase, a suspension in which the dispersant is a solid phase, and the like are called gel or sol and are included in the "gel state".
  • a state in which the dispersant is a solid phase and the dispersed phase is a liquid phase is also included in the "gel state".
  • the lubricant is a liquid lubricating oil (oil).
  • a rotational force is applied as an input to the eccentric shaft 7, so that the eccentric shaft 7 rotates around the rotation axis Ax1, and the planetary gear 3 swings (revolves) around the rotation axis Ax1.
  • the planetary gear 3 swings in a state where it is inscribed in the inner side of the internal gear 2 and a part of the external teeth 31 meshes with a part of the internal teeth 21, so the meshing position of the internal teeth 21 and the external teeth 31 moves along the circumferential direction of the internal gear 2.
  • a relative rotation corresponding to the difference in the number of teeth between the planetary gear 3 and the internal gear 2 is generated between the two gears (the internal gear 2 and the planetary gear 3).
  • the rotation (autorotation 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 through the plurality of inner pins 4.
  • a rotation output reduced by a relatively high reduction ratio corresponding to the difference in the number of teeth between the two gears can be obtained from the output shaft integrated with the inner ring 61.
  • the number of teeth V1 of the internal gear 2 is "52”
  • the number of teeth V2 of the planetary gear 3 is "51”
  • the difference in the number of teeth (V1-V2) is "1”
  • the reduction ratio R1 is "51”.
  • the eccentric shaft 7 rotates clockwise around the rotation axis Ax1 for one circle (360 degrees)
  • the inner ring 61 rotates counterclockwise around the rotation axis Ax1 for the difference in the number of teeth "1" (that is, about 7.06 degrees).
  • such a high reduction ratio R1 can be achieved by the combination of the primary gears (the internal gear 2 and the planetary gears 3 ).
  • the gear device 1 only needs to include at least the internal gear 2 , the planetary gear 3 , the plurality of inner pins 4 , the bearing member 6 , and the support body 8 , and may further include, for example, a spline bushing as a component.
  • the rotating body composed of the eccentric body inner ring 51 and at least one of the components (eccentric shaft 7) rotating together with the eccentric body inner ring 51 performs eccentric motion at high speed, so it is preferable to achieve weight balance of the rotating body relative to the rotation axis Ax1.
  • a gap 75 is provided in a part of the eccentric portion 72 of the eccentric shaft 7 to achieve weight balance of the rotating body relative to the rotation axis Ax1.
  • the gear device 1 of the present embodiment includes an eccentric body bearing 5 that is accommodated in the opening portion 33 formed in the planetary gear 3 and causes the planetary gear 3 to swing.
  • the eccentric body bearing 5 has an eccentric outer ring 52 and an eccentric inner ring 51 disposed on the inner side of the eccentric outer ring 52.
  • the rotating body composed of the eccentric inner ring 51 and at least one of the components that rotate together with the eccentric inner ring 51 has a gap 75 at a portion on the center C1 side of the eccentric outer ring 52.
  • the eccentric shaft 7 is a "component that rotates together with the eccentric inner ring 51" and is equivalent to a “rotating body”. Therefore, the gap 75 formed in the eccentric portion 72 of the eccentric shaft 7 is equivalent to the gap 75 of the rotating body.
  • the gap 75 is located on the center C1 side when viewed from the rotation axis Ax1 , and thus functions to make the weight balance of the eccentric shaft 7 nearly uniform from the rotation axis Ax1 to the circumferential direction.
  • the gap 75 includes a recessed portion formed on the inner circumferential surface of the through hole 73 that penetrates the rotating body along the rotation axis Ax1 of the eccentric body inner ring 51. That is, in the present embodiment, the rotating body is the eccentric shaft 7, and therefore the recessed portion formed on the inner circumferential surface of the through hole 73 that penetrates the eccentric shaft 7 along the rotation axis Ax1 functions as the gap 75. In this way, by utilizing the recessed portion formed on the inner circumferential surface of the through hole 73 as the gap 75, the weight balance of the rotating body can be achieved without changing the appearance.
  • the internal gear 2 is an example of a "first gear”
  • the planetary gear 3 is an example of a "second gear”. That is, the first gear is an internal gear 2 having an annular gear body 22 and a plurality of pins 23. The plurality of pins 23 are held in a plurality of inner peripheral grooves 223 formed on the inner peripheral surface 221 of the gear body 22 in a rotatable state, and constitute the internal teeth 21.
  • the second gear is a planetary gear 3 having external teeth 31 partially meshing with the internal teeth 21.
  • the planetary gear 3 is caused to rotate relative to the internal gear 2 by swinging the planetary gear 3 around the rotation axis Ax1.
  • Fig. 9 is an enlarged view of the area Z1 of Fig. 3 .
  • the plurality of inner pins 4 are components that connect the planetary gear 3 to the inner ring 61 of the bearing member 6. Specifically, one end of the inner pin 4 in the longitudinal direction (in this embodiment, the end on the input side of the rotation axis Ax1) is inserted into the inner pin hole 32 of the planetary gear 3, and the other end of the inner pin 4 in the longitudinal direction (in this embodiment, the end on the output side of the rotation axis Ax1) is inserted into the retaining hole 611 of the inner ring 61.
  • the diameter of the inner pin 4 is smaller than the diameter of the inner pin hole 32 by one circle, so that a gap can be ensured between the inner pin 4 and the inner peripheral surface 321 of the inner pin hole 32, and the inner pin 4 can move in the inner pin hole 32, that is, the inner pin 4 can move relative to the center of the inner pin hole 32.
  • the diameter of the retaining hole 611 is larger than the diameter of the inner pin 4, it is smaller than the diameter of the inner pin hole 32.
  • the diameter of the retaining hole 611 is substantially the same as the diameter of the inner pin 4, and is slightly larger than the diameter of the inner pin 4.
  • the movement of the inner pin 4 in the retaining hole 611 is restricted, that is, the relative movement of the inner pin 4 relative to the center of the retaining hole 611 is prohibited. Therefore, the inner pin 4 is retained in the planetary gear 3 in a state in which it can revolve in the inner pin hole 32, and is retained in a state in which it cannot revolve in the retaining hole 611 relative to the inner ring 61.
  • the swing component of the planetary gear 3 that is, the revolution component of the planetary gear 3 is absorbed by the loose fit between the inner pin hole 32 and the inner pin 4, and 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 through multiple inner pins 4.
  • the diameter of the inner pin 4 is slightly larger than the retaining hole 611, so that when the inner pin 4 is inserted into the retaining hole 611, although the revolution in the retaining hole 611 is prohibited, the inner pin 4 can be moved. In other words, even when the inner pin 4 is inserted into the retaining hole 611, it can rotate in the retaining hole 611 because it is not pressed into the retaining hole 611. In this way, in the gear device 1 of this embodiment, each of the plurality of inner pins 4 is retained by the inner ring 61 in a state in which it can rotate, so when the inner pin 4 revolves in the inner pin hole 32, the inner pin 4 itself can rotate.
  • the inner pin 4 is held relative to the planetary gear 3 in a state in which it can both revolve and rotate within the inner pin hole 32, and is held relative to the inner ring 61 in a state in which it can only rotate within the retaining hole 611. That is, the plurality of inner pins 4 can rotate (revolve) around the rotation axis Ax1 in a state in which their respective rotations are not constrained (in a state in which they can rotate), and can revolve within the plurality of inner pin holes 32. Therefore, when the rotation (rotation component) of the planetary gear 3 is transmitted to the inner ring 61 by the plurality of inner pins 4, the inner pin 4 can revolve and rotate within the inner pin hole 32, and can rotate within the retaining hole 611.
  • the inner pin 4 revolves within the inner pin hole 32, the inner pin 4 is in a state in which it can rotate, and therefore rolls relative to the inner circumferential surface 321 of the inner pin hole 32.
  • the inner pin 4 revolves in the inner pin hole 32 by rolling on the inner circumferential surface 321 of the inner pin hole 32 , so that loss caused by friction resistance between the inner circumferential surface 321 of the inner pin hole 32 and the inner pin 4 is unlikely to occur.
  • each of the plurality of inner pins 4 is directly in contact with the inner circumferential 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 attached is inserted into the inner pin hole 32 so that the inner pin 4 is directly in contact with the inner circumferential surface 321 of the inner pin hole 32.
  • 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 (especially reduced in diameter), and the gear device 1 as a whole can also be easily miniaturized.
  • the size of the planetary gear 3 is set to be fixed, for example, the number of inner pins 4 can be increased to make the transmission of rotation smoother, or the inner pin 4 can be made thicker to improve the strength, compared with the first related art mentioned above.
  • the number of components can be suppressed to a small number according to the amount of inner rollers, which also contributes to the cost reduction of the gear device 1.
  • 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 , In a direction parallel to the rotation axis Ax1, the inner pin 4 is arranged at least a portion thereof at the same position as the bearing member 6. In other words, at least a portion of the inner pin 4 is located between the two end surfaces of the bearing member 6 in a direction parallel to the rotation axis Ax1. In other words, each of the plurality of inner pins 4 is arranged at least a portion thereof on the inner side of the outer ring 62 of the bearing member 6.
  • the end portion of the inner pin 4 on the output side of the rotation axis Ax1 is located at the same position as the bearing member 6 in a direction parallel to the rotation axis Ax1.
  • the end portion of the inner pin 4 on the output side of the rotation axis Ax1 is inserted into the retaining hole 611 formed in the inner ring 61 of the bearing member 6, and therefore at least the end portion is arranged at the same position as the bearing member 6 in the axial direction of the bearing member 6.
  • each of the plurality of inner pins 4 is arranged at the same position as the bearing member 6 in the axial direction of the bearing member 6, thereby making it possible to suppress the size of the gear device 1 in the direction parallel to the rotation axis Ax1 to be small. That is, compared with a structure in which the bearing member 6 and the inner pin 4 are arranged side by side (opposite) in the axial direction of the bearing member 6, in the gear device 1 of this embodiment, the size of the gear device 1 in the direction parallel to the rotation axis Ax1 can be reduced, and it is possible to contribute to further miniaturization (thinning) of the gear device 1.
  • the opening surface on the output side of the rotation axis Ax1 in the holding hole 611 is closed by, for example, the output shaft integrated with the inner ring 61.
  • the movement of the inner pin 4 to the output side (right side in FIG. 9) of the rotation axis Ax1 is restricted by the output shaft integrated with the inner ring 61.
  • the following structure is adopted to make the inner pin 4 rotate smoothly relative to the inner ring 61. That is, the inner pin 4 rotates smoothly by interposing a lubricant (lubricating oil) between the inner circumferential surface of the retaining hole 611 formed in the inner ring 61 and the inner pin 4.
  • a lubricant retaining space 17 for injecting lubricant between the inner ring 61 and the outer ring 62, so that the inner pin 4 rotates smoothly by utilizing the lubricant in the lubricant retaining space 17.
  • the inner ring 61 has: a plurality of retaining holes 611 for inserting a plurality of inner pins 4, respectively; and a plurality of connecting paths 64.
  • the plurality of connecting paths 64 connect the lubricant retaining space 17 between the inner ring 61 and the outer ring 62 to the plurality of retaining holes 611.
  • the inner ring 61 is provided with connecting paths 64 extending radially from a portion of the inner circumferential surface of the retaining holes 611, i.e., a portion corresponding to the rolling element 63.
  • the connecting paths 64 are recessed portions of the inner ring 61 on the surface opposite to the outer ring 62 for accommodating the rolling element 63.
  • the hole is a through hole between the bottom surface of the portion (groove) and the inner peripheral surface of the retaining hole 611.
  • the opening surface of the connecting path 64 on the lubricant retaining space 17 side is arranged at a position facing (opposite) to the rolling element 63 of the bearing member 6.
  • the lubricant retaining space 17 and the retaining hole 611 are spatially connected via such a connecting path 64.
  • the lubricant in the lubricant retaining space 17 passes through the connecting path 64 and is supplied to the retaining hole 611. That is, when the bearing member 6 moves and the rolling element 63 rolls, the rolling element 63 functions as a pump and can send the lubricant in the lubricant retaining space 17 to the retaining hole 611 via the connecting path 64.
  • the opening surface of the connecting path 64 on the lubricant retaining space 17 side is located in a position facing (opposite) to the rolling element 63 of the bearing member 6, so that the rolling element 63 effectively functions as a pump when the rolling element 63 rotates.
  • the lubricant is interposed between the inner circumferential surface of the retaining hole 611 and the inner pin 4, and the inner pin 4 can smoothly rotate relative to the inner ring 61.
  • FIG10 is a cross-sectional view taken along the line B1-B1 of FIG3.
  • the section lines are omitted even for the sections of the components other than the support body 8.
  • FIG10 only the internal gear 2 and the support body 8 are shown, and the illustration of other components (such as the inner pin 4) is omitted.
  • the illustration of the inner circumferential surface 221 of the gear body 22 is omitted.
  • the support body 8 is a component that supports the multiple inner pins 4. That is, the support body 8 bundles the multiple inner pins 4 to disperse the load acting on the multiple inner pins 4 when the rotation (rotation component) of the planetary gear 3 is transmitted to the inner ring 61.
  • the diameter of the support hole 82 is equal to the diameter of the retaining hole 611 formed in the inner ring 61. Therefore, the support body 8 supports the multiple inner pins 4 in a state where each of the multiple inner pins 4 can rotate. That is, each of the multiple inner pins 4 is retained in a state where both the inner ring 61 and the support body 8 relative to the bearing member 6 can rotate.
  • the support body 8 positions the plurality of inner pins 4 relative to the support body 8 in both the circumferential and radial directions. That is, the inner pins 4 are inserted into the support holes 82 of the support body 8, so that the movement in all directions within the plane orthogonal to the rotation axis Ax1 is restricted.
  • the support body 8 is positioned not only in the circumferential direction but also in the radial direction (radial direction).
  • the support body 8 has an annular shape in which at least the outer peripheral surface 81 is a perfect circle when viewed from above. And the support body 8 is positionally restricted by making the outer peripheral surface 81 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 positionally restricted by making the outer peripheral surface 81 contact with the internal teeth 21.
  • the diameter of the outer peripheral surface 81 of the support body 8 is the same as the diameter of the virtual circle (tooth tip circle) passing through the front end of the internal teeth 21 of the internal gear 2. Therefore, all of the plurality of pins 23 are in contact with the outer peripheral surface 81 of the support body 8.
  • the center of the support body 8 is positionally restricted in a manner overlapping with the center (rotation axis Ax1) of the internal gear 2.
  • the centering of the support body 8 is performed, and as a result, the centering of the plurality of inner pins 4 supported by the support body 8 is also performed by the plurality of pins 23.
  • the plurality of inner pins 4 rotate (revolve) around the rotation axis Ax1, thereby transmitting the rotation (autorotation component) of the planetary gear 3 to the inner ring 61. Therefore, the support body 8 that supports 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, the support body 8 is centered using the plurality of pins 23, so the support body 8 rotates smoothly with the center of the support body 8 maintained on the rotation axis Ax1.
  • the support body 8 rotates in a state where its outer peripheral surface 81 is in contact with the plurality of pins 23, so that as the support body 8 rotates, the plurality of pins 23 each rotate (autorotate).
  • the support body 8 and the internal gear 2 together form a needle roller bearing (needle roller bearing) and rotate smoothly.
  • the outer peripheral surface 81 of the support body 8 rotates relative to the gear body 22 together with the plurality of inner pins 4 in a state of being 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 between the two function as "rolling elements (rollers)". In this way, the support body 8 and the internal gear 2 (gear body 22 and plurality of pins 23) together constitute a needle bearing and can rotate smoothly.
  • the support body 8 sandwiches the plurality of pins 23 between the gear bodies 22, the support body 8 also functions as a "stopper" that suppresses the movement of the pins 23 in the direction of separation from the inner peripheral surface 221 of the gear body 22.
  • 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, thereby suppressing the floating of the plurality of pins 23 from the inner peripheral surface 221 of the gear body 22.
  • the plurality of pins 23 are each contacted with the outer peripheral surface 81 of the support body 8 to be Movement in a direction away from the gear body 22 is restricted.
  • the support body 8 is located on the opposite side of the bearing member 6 from the inner ring 61 across the planetary gear 3. That is, the support body 8, the planetary gear 3, and the inner ring 61 are arranged in parallel in a direction parallel to the rotation axis Ax1.
  • the support body 8 is located on the input side of the rotation axis Ax1 when viewed from the planetary gear 3, and the inner ring 61 is located on the output side of the rotation axis Ax1 when viewed from the planetary gear 3.
  • the support body 8 supports both ends of the inner pin 4 in the longitudinal direction (in the direction parallel to the rotation axis Ax1) together with the inner ring 61, and the central portion of the inner pin 4 in the longitudinal direction is inserted through the inner pin hole 32 of the planetary gear 3.
  • the gear device 1 of the present embodiment includes a bearing member 6 having an outer ring 62 and an inner ring 61 arranged inside the outer ring 62, and the inner ring 61 is supported so as to be relatively rotatable relative to the outer ring 62.
  • the gear body 22 is fixed to the outer ring 62.
  • the planetary gear 3 is located between the support body 8 and the inner ring 61 in the axial direction of the support body 8 .
  • the support body 8 and the inner ring 61 support the two ends of the inner pin 4 in the longitudinal direction, so it is difficult for the inner pin 4 to tilt. In particular, it is also easy to withstand the bending force (bending moment load) acting on the multiple inner pins 4 with respect to the rotation axis Ax1.
  • the support body 8 is clamped between the planetary gear 3 and the housing 10 in a direction parallel to the rotation axis Ax1. As a result, the movement of the support body 8 to the input side of the rotation axis Ax1 (the left side of Figure 9) is restricted by the housing 10.
  • the support body 8 and the inner ring 61 are also in contact with both ends of the plurality of pins 23. That is, as shown in FIG. 9 , the support body 8 is in contact with one end (the end on the input side of the rotation axis Ax1) of the pin 23 in the longitudinal direction (the direction parallel to the rotation axis Ax1).
  • the inner ring 61 is in contact with the other end (the end on the output side of the rotation axis Ax1) of the pin 23 in the longitudinal direction (the direction parallel to the rotation axis Ax1).
  • the support body 8 and the inner ring 61 are centered at both ends in the longitudinal direction of the pin 23, so that the inner pin 4 is less likely to tilt. In particular, it is also easy to withstand the bending force (bending moment load) with respect to the rotation axis Ax1 acting on the plurality of inner pins 4.
  • the plurality of pins 23 have a length greater than the thickness of the support body 8.
  • the support body 8 is within the range of the tooth direction of the internal teeth 21 in the direction parallel to the rotation axis Ax1.
  • the outer peripheral surface 81 contacts the plurality of pins 23 over the entire length of the inner teeth 21 in the tooth direction (direction parallel to the rotation axis Ax1). Therefore, the outer peripheral surface 81 of the support body 8 is less likely to suffer from "single-side wear" where the outer peripheral surface 81 is locally worn.
  • 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 the two end surfaces of the support body 8 in the axial direction (thickness direction).
  • the "surface roughness” mentioned in the present disclosed embodiment refers to the roughness of the surface of an object. The smaller the value, the smaller (the fewer) the surface bumps are and the smoother the surface is.
  • the surface roughness is set to the arithmetic balance roughness (Ra).
  • Ra arithmetic balance roughness
  • the outer peripheral surface 81 is smaller than the surface roughness of the surface other than the outer peripheral surface 81 of the support body 8. In this structure, the rotation of the support body 8 becomes smoother.
  • the hardness of the outer peripheral surface 81 of the support body 8 is lower than the peripheral surface of the plurality of pins 23 and higher than the inner peripheral surface 221 of the gear body 22.
  • the "hardness” mentioned in the present disclosed embodiment refers to the hardness of an object, and the hardness of a metal is represented by the size of an indentation formed by pushing a steel ball with a certain pressure, for example.
  • the hardness of a metal there are Rockwell hardness (HRC), Brinell hardness (HB), Vickers hardness (HV) or Shore hardness (Hs), etc.
  • HRC Rockwell hardness
  • HB Brinell hardness
  • HV Vickers hardness
  • Hs Shore hardness
  • As a means of increasing the hardness (hardening) of a metal part there are, for example, alloying or heat treatment.
  • the hardness of the outer peripheral surface 81 of the support body 8 is increased by carburizing and quenching and other treatments. In this structure, even if the support body 8 rotates, it is difficult to generate wear powder, etc., and it is easy to maintain the smooth rotation of the support body 8 for a long time.
  • the gear device 1 and the actuator 100 of this embodiment are suitable for, for example, a horizontal multi-joint robot, that is, a robot such as a so-called selective compliance assembly robot arm (SCARA: Selective Compliance Assembly Robot Arm) type robot.
  • SCARA Selective Compliance Assembly Robot Arm
  • the gear device 1 and the actuator 100 of the present embodiment are not limited to the horizontal multi-joint robot as described above, and may be, for example, an industrial robot other than a horizontal multi-joint robot or a non-industrial robot.
  • industrial robots other than horizontal multi-joint robots include vertical multi-joint robots or parallel linkage robots.
  • non-industrial robots As an example, there are household robots, nursing robots, medical robots, and the like.
  • FIG. 11 is an enlarged schematic cross-sectional view of the meshing portion of the internal gear 21 (pin 23) and the external gear 31 in FIG. 9, and the illustration of components other than the internal gear 2 (gear body 22 and pin 23) and the planetary gear 3 is omitted.
  • FIG. 12 is a schematic cross-sectional view of the A1-A1 line of FIG. 11, and the illustration of components other than the internal gear 2 and the planetary gear 3 is omitted as in FIG. 11.
  • FIGS. 11 and 12 the schematic enlarged views of the main parts are shown in the white boxes.
  • a gear device 1 including a first gear (internal gear 2) and a second gear (planetary gear 3) that rotates relative to the first gear by meshing with the first gear
  • “sliding contact” is generated between the gear body 22 of the first gear (internal gear 2) and the pin 23 that forms the internal teeth 21.
  • the “sliding contact” mentioned in the present disclosure refers to a contact state between two objects that produces a macroscopic slip compared to the microslip (Microslip) in rolling contact (or fixed contact).
  • “sliding contact” is one of the motion forms of two solid surfaces that are in contact and move relative to each other, and unlike rolling contact, it is a form of relative motion that produces a macroscopic slip between the two objects.
  • a coating layer 224 is formed on a "sliding contact portion" such as the inner surface of a plurality of inner peripheral grooves 223 that make sliding contact with another member (here, the pin 23).
  • the coating layer 224 is a layer that covers at least a portion of the skeleton portion 225 that serves as a base material. That is, in the present embodiment, in the skeleton portion 225 that serves as a base material of the gear body 22 of the internal gear 2, at least the inner surface of the plurality of inner peripheral grooves 223 that serve as sliding contact portions is covered by the coating layer 224.
  • the coating layer 224 is made of a material having a higher specific gravity than the frame portion 225.
  • the coating layer 224 and the frame portion 225 are both made of metal, and the coating layer 224 is made of a metal having a higher specific gravity than the frame portion 225.
  • the frame portion 225 serving as the base material of the gear body 22 is made of aluminum (Al), and the coating layer 224 is made of iron (Fe).
  • the gear device 1 of the present embodiment includes a first gear (an 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 with a specific gravity greater than that of the skeleton portion 225. At least a sliding contact portion of the skeleton portion 225 that is in sliding contact with another component is covered by the coating layer 224.
  • the skeleton part 225 of the first gear (internal gear 2) itself is made of a material with a low specific gravity, and even if it has a corresponding thickness, the weight can be suppressed to be relatively small.
  • the sliding contact part (with another component) in the skeleton part 225 is covered by the coating layer 224 with a larger specific gravity than the skeleton part 225, so the sliding contact part can improve the wear resistance and maintain the strength as the first gear (internal gear 2).
  • the gear device 1 of this embodiment it is possible to realize a gear device 1 that is easy to achieve lightweight while maintaining strength.
  • the first gear is the internal gear 2 and the second gear is the planetary gear 3, so the inner surfaces of the plurality of inner peripheral grooves 223 in the skeleton portion 225 of the internal gear 2 that are in sliding contact with the plurality of pins 23 as another component are the sliding contact portions. Therefore, at least the inner surfaces (sliding contact portions) of the plurality of inner peripheral grooves 223 are covered by the coating layer 224.
  • the coating layer 224 is formed over the entire circumference of the inner peripheral surface 221 of the gear body 22 in a manner covering the entire area of the inner surface of the inner peripheral groove 223. Therefore, the skeleton portion 225 is not exposed on the inner surface of the inner peripheral groove 223 that is in sliding contact with the pin 23.
  • the coating layer 224 is not formed at both end portions of the inner peripheral surface 221 of the gear body 22 in the tooth direction of the internal teeth 21 (a direction parallel to the rotation axis Ax1), and the skeleton portion 225 is exposed.
  • the portion constituting the inner peripheral groove 223 protrudes toward the inside (the rotation axis Ax1 side), and the coating layer 224 is formed in a manner covering only the protruding portion.
  • the corners of the inner circumferential groove 223 that are the two ends of the tooth direction of the internal teeth 21, that is, the portions that are convex angles in the cross section shown in FIG. 11, are formed with the coating layer 224 in such a manner as to completely cover the skeleton portion 225.
  • the coating layer 224 is formed from the inner surface of the inner circumferential groove 223 to the step portion adjacent thereto. In this way, by covering the corners with the coating layer 224, even if the corners are in contact with the pin 23, direct contact between the pin 23 and the skeleton portion 225 can be avoided, and wear of the skeleton portion 225 can be easily suppressed.
  • the coating layer 224 is formed by spraying.
  • spraying refers to a processing technique in which a coating is formed on the surface of a processing object by spraying particles of a spraying material such as metal that is melted and softened by various heat sources onto the surface of the processing object.
  • a spraying material such as metal that is melted and softened by various heat sources onto the surface of the processing object.
  • the molten particles sprayed by spraying adhere to a base material such as a metal of the processing object, they are instantly cooled and solidified to form a coating.
  • the coating formed on the skeleton portion 225 by spraying constitutes the coating layer 224.
  • the manufacturing method of the gear device 1 of the present embodiment includes a spraying step of forming a coating layer 224 by spraying on at least a portion of the skeleton portion 225 of the first gear (internal gear 2).
  • the coating layer 224 formed by spraying can have a greater film thickness than a film formed by a method such as plating or vapor deposition.
  • the manufacturing method of the gear device 1 of the present embodiment has a surface finishing process such as grinding after the spraying process. According to the surface finishing process, although the film thickness of the film formed by spraying is reduced, a film with a sufficient film thickness is formed by spraying, so that a film with a sufficient film thickness (coating layer 224) can be achieved even after the surface finishing process.
  • the thermal conductivity of the skeleton portion 225 is higher than that of the coating layer 224.
  • the coating layer 224 is made of iron (Fe), and therefore the thermal conductivity of the coating layer 224 is 80.3 (W/m ⁇ K).
  • the skeleton portion 225 is made of aluminum (Al), and therefore the thermal conductivity of the skeleton portion 225 is 237 (W/m ⁇ K).
  • the skeleton portion 225 has a thermal conductivity that is nearly three times that of the coating layer 224.
  • the majority of the gear body 22 of the first gear can be constituted by the skeleton portion 225 having high thermal conductivity, thereby improving the heat dissipation of the first gear (internal gear 2).
  • the gear device 1 operates, the first gear (internal gear 2) and the second gear
  • the generated heat can be effectively dissipated.
  • the gear body 22 together with the housing 10 forms a part of the outer contour of the gear device 1, and the heat generated inside the gear device 1 can be effectively dissipated to the outside of the gear device 1.
  • the coating layer 224 is a sprayed film having a different composition from the skeleton part 225. That is, as described above, the coating layer 224 is a sprayed film formed by spraying.
  • a sprayed film having the same composition as the skeleton part 225 can be formed on the surface of the skeleton part 225, a sprayed film having a different composition from the skeleton part 225 is formed in the present embodiment.
  • the skeleton part 225 is aluminum (Al)
  • the coating layer 224 is iron (Fe).
  • the linear expansion coefficients of the skeleton 225 and the coating layer 224 are close. Specifically, in a temperature environment below 93°C (200°F), it is preferred that the linear expansion coefficients of the two be close to each other to such an extent that the skeleton 225 will not peel off from the coating layer 224 due to the difference in linear expansion coefficients.
  • the coating layer 224 has a thickness of 50 ⁇ m or more. That is, as a characteristic of the coating layer 224 formed by spraying, it can have a larger film thickness than a film formed by a method such as plating or evaporation, and the specific film thickness of the coating layer 224 is preferably 50 ⁇ m or more.
  • the spraying process a 150 ⁇ m film is formed on the surface of the skeleton part 225, and 100 ⁇ m is ground off in the surface finishing process, thereby forming a 50 ⁇ m coating layer 224.
  • the first gear (internal gear 2) has a base layer 226 on the surface of the skeleton 225, and the coating layer 224 is stacked on the base layer 226. That is, as shown in the white boxes of Figures 11 and 12, the base layer 226 and the coating layer 224 are sequentially stacked on the surface of the skeleton 225.
  • the coating layer 224 is not directly stacked on the surface of the skeleton 225, but is stacked via the base layer 226, so that the adhesion of the coating layer 224 to the skeleton 225 can be improved.
  • the base layer 226 is formed on the surface of the skeleton portion 225 by, for example, processing to increase the surface roughness (arithmetic mean roughness (Ra)) of the skeleton portion 225.
  • the base layer 226 is formed by laser peening the surface of the skeleton part 225.
  • the "laser peening" described in the present disclosure is a surface modification technology that irradiates a processing object with laser pulses to impart compressive residual stress to the surface of the processing object and improve the surface hardness. That is, the manufacturing method of the gear device 1 of the present embodiment has a base forming step for forming the base layer 226 such as laser peening before the spraying step.
  • the grid direction of the base layer 226 is preferably based on the sliding direction of another component at the sliding contact site. That is, as shown in Figures 13A and 13B, the inner surface of the inner peripheral groove 223 that becomes the sliding contact site of another component (pin 23) in the skeleton part 225 determines the sliding direction of the other component. In other words, the pin 23 rotates (rotates) in the inner peripheral groove 223 with its central axis as the center, so 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 grid direction of the base layer 226 based on this sliding direction, the adhesion of the coating layer 224 is improved, and it is easy to suppress the peeling of the coating layer 224.
  • the grid direction of the base layer 226 formed by laser peening or the like a direction intersecting with the sliding direction of the other component (pin 23) at the sliding contact portion.
  • the grid direction of the base layer 226 is orthogonal to the sliding direction of the other component. According to such a structure, even if the other component (pin 23) is in sliding contact with the coating layer 224 formed on the base layer 226, the coating layer 224 will be caught on the processing mark of the base layer 226 and it will be difficult to peel off from the skeleton part 225.
  • the base layer 226 formed by laser shot peening or the like is configured in a grid shape based on the sliding direction of another component (pin 23) at the sliding contact position.
  • discrete processing marks that are roughly evenly dispersed are formed in the long side direction and the circumferential direction of the inner circumferential groove 223.
  • Each processing mark can be in an appropriate shape such as a circular ring, a polygonal shape, or a dot shape.
  • Embodiment 1 is only one of various embodiments of the present disclosure. Embodiment 1 can be modified in various ways according to design, etc. as long as it can achieve the purpose of the present disclosure.
  • the drawings referred to in the present disclosure are all schematic diagrams, and the size and thickness ratio of each structural element in the drawings are not necessarily limited to reflect the Actual size ratio. The following lists modifications of the first embodiment. The modifications described below can be combined as appropriate and applied.
  • the gear body 22 of the internal gear 2 may be seamlessly integrated with the housing 10.
  • the housing 10 is made of the same material as the gear body 22 (e.g., aluminum), and the housing 10 and the gear body 22 are treated as one component.
  • the volume and surface area of the aluminum component are increased, and it is expected that the gear device 1 as a whole will be lighter and the heat dissipation will be improved.
  • the outer ring 62 of the bearing member 6 may be seamlessly integrated with the gear body 22 of the internal gear 2.
  • the first gear is the internal gear 2 and the second gear is the planetary gear 3.
  • the first gear may be the planetary gear 3 and the second gear may be the internal gear 2.
  • the base material of the planetary gear 3 constitutes the skeleton part, and, for example, the sliding contact part of the planetary gear 3 that is in sliding contact with another component (internal pin 4) is covered with a coating layer.
  • the skeleton 225 is not limited to iron (Fe), and the coating layer 224 is not limited to aluminum (Al).
  • the coating layer 224 can be made of any material as long as its specific gravity is greater than that of the skeleton 225, and at least one of the coating layer 224 and the skeleton 225 can be non-metallic. Even in this case, it is preferred that the thermal conductivity of the skeleton 225 is higher than that of the coating layer 224.
  • the coating layer 224 is not limited to being formed by thermal spraying, and may be formed by a method other than thermal spraying.
  • the base layer 226 is not limited to laser peening, and can be formed by, for example, shot peening of a projection material onto the object to be processed.
  • the grid direction of the base layer 226 is not limited to the examples shown in FIG. 13A and FIG. 13B, and can be, for example, a direction along the sliding direction of another component (pin 23) or a direction inclined relative to the sliding direction of another component (pin 23).
  • a gear device 1 of a type having one planetary gear 3 is illustrated, but the gear device 1 may include two or more planetary gears 3.
  • the gear device 1 may include two or more planetary gears 3.
  • the gear device 1 may include three planetary gears 3, it is preferred that the three planetary gears 3 are arranged with a phase difference of 120 degrees around the rotation axis Ax1.
  • two of the three planetary gears 3 may be in the same phase, and the remaining planetary gear 3 may be arranged with a phase difference of 180 degrees around the rotation axis Ax1.
  • the number of pins 23 (the number of teeth of the internal teeth 21) and the number of external teeth 31 described in the first embodiment are The number of teeth and the like are merely examples and may be changed as appropriate.
  • each component of the gear device 1 is not limited to metal, and may be, for example, resin such as engineering plastic.
  • the gear device 1 is not limited to a structure in which the rotational force of the inner ring 61 is taken out as an output.
  • the rotational force of the outer ring 62 (housing 10) rotating relative to the inner ring 61 can also be taken out as an output.
  • the lubricant is not limited to liquid substances such as lubricating oil (oil), and may be a gel-like substance such as grease.
  • FIGS. 14 to 16 the gear device 1A of this embodiment is different from the gear device 1 of the first embodiment in that it is an eccentric oscillating type internal meshing planetary gear device called a distribution type.
  • FIG. 14 is a perspective view showing the schematic structure of the gear device 1A.
  • FIG. 15 is a schematic exploded perspective view of the gear device 1A as viewed from the input side of the rotation axis Ax1.
  • FIG. 16 is a schematic cross-sectional view of the gear device 1A.
  • the gear device 1A of the present embodiment includes a plurality of (three in the present embodiment) eccentric shafts (crankshafts) 7A, 7B, 7C arranged at positions offset from the axis (rotation axis Ax1) of the internal gear 2. Further, the gear device 1A includes an input shaft 500 arranged on the axis (rotation axis Ax1) of the internal gear 2 and centered on the rotation axis Ax1, and an input gear 501 formed integrally with the input shaft 500. Crankshaft gears 502A, 502B, 502C are connected to the plurality of eccentric shafts 7A, 7B, 7C by splines, respectively.
  • crankshaft 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 synchronously drives the eccentric shafts 7A, 7B, 7C by using the input gear 501, so that the planetary gear 3 meshes with the internal gear 2 while swinging.
  • the gear device 1A of the present embodiment includes a plurality of planetary gears 3.
  • the gear device 1A includes two planetary gears 3, namely, a first planetary gear 301 and a second planetary gear 302.
  • the gears 3 are arranged to face each other in a direction parallel to the rotation axis Ax1. That is, the planetary gears 3 include a first planetary gear 301 and a second planetary gear 302 arranged in parallel to the rotation axis Ax1.
  • the first planetary gear 301 and the second planetary gear 302 have the same shape.
  • These two planetary gears 3 are arranged with a phase difference of 180 degrees around the rotation axis Ax1.
  • the center C1 of the first planetary gear 301 located on the input side of the rotation axis Ax1 (the right side of FIG. 16) of the first planetary gear 301 and the second planetary gear 302 is in a state of being deviated (shifted) upward in the figure relative to the rotation axis Ax1.
  • the center C2 of the second planetary gear 302 located on the output side of the rotation axis Ax1 (the left side of FIG.
  • the distance ⁇ L1 between the rotation axis Ax1 and the center C1 is the eccentricity of the first planetary gear 301 relative to the rotation axis Ax1
  • the distance ⁇ L2 between the rotation axis Ax1 and the center C2 is the eccentricity of the second planetary gear 302 relative to the rotation axis Ax1.
  • the plurality of planetary gears 3 are evenly arranged in the circumferential direction centered on the rotation axis Ax1, thereby achieving a weight balance between the plurality of planetary gears 3.
  • the centers C1 and C2 of the first planetary gear 301 and the second planetary gear 302 are 180 degrees rotationally symmetrical with respect to the rotation axis Ax1.
  • the eccentricity ⁇ L1 and the eccentricity ⁇ L2 have opposite directions when viewed from the rotation axis Ax1, but have the same absolute values.
  • each eccentric shaft 7A, 7B, 7C has two eccentric parts 72 with respect to one shaft center part 71.
  • the eccentricity of the center of these two eccentric parts 72 from the center of the shaft center part 71 is the same as the eccentricity ⁇ L1 and ⁇ L2 of the first planetary gear 301 and the second planetary gear 302 with respect to the rotation axis Ax1.
  • the shapes of the plurality of eccentric shafts 7A, 7B, 7C are the same.
  • the shapes of the plurality of crankshaft gears 502A, 502B, 502C are the same.
  • a support flange 18 and an output flange 19 are arranged on both sides of the first planetary gear 301 and the second planetary gear 302 in a direction parallel to the rotation axis Ax1. Both ends of each eccentric shaft 7A, 7B, 7C are held by the support flange 18 and the output flange 19 via rolling bearings 41, 42. That is, each eccentric shaft 7A, 7B, 7C is held by the support flange 18 and the output flange 19 in a rotatable state at both sides of the direction parallel to the rotation axis Ax1 with respect to the planetary gear 3.
  • the eccentric body bearing 5 is mounted on the eccentric portion 72 of each eccentric shaft 7A, 7B, 7C.
  • the wheel 301 and the second planetary gear 302 are respectively formed with three openings 33 corresponding to the three eccentric shafts 7A, 7B, and 7C. And, an eccentric body bearing 5 is accommodated in each opening 33.
  • the eccentric body bearing 5 is respectively installed on the first planetary gear 301 and the second planetary gear 302, and each eccentric shaft 7A, 7B, and 7C is inserted into the eccentric body bearing 5, thereby the eccentric body bearing 5 and each eccentric shaft 7A, 7B, and 7C are combined with the planetary gear 3.
  • the inner pin 4 is omitted, and the inner pin 4 is replaced by a plurality of eccentric shafts 7A, 7B, and 7C, so that the rotation (autorotation component) of the planetary gear 3 can be extracted in addition to the swing component (revolution component) of the planetary gear 3.
  • the input shaft 500 is rotated around the rotation axis Ax1 by applying a rotation force as an input to the input shaft 500, so that 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 three crankshaft gears 502A, 502B, and 502C that are simultaneously meshed with the input gear 501 rotate in the same direction at the same rotation speed.
  • the eccentric shafts 7A, 7B, and 7C are spline-connected to each crankshaft gear 502A, 502B, and 502C, so the three eccentric shafts 7A, 7B, and 7C rotate in the same direction at the same rotation speed in a state where the number of teeth is reduced compared to the input gear 501 and the crankshaft gears 502A, 502B, and 502C.
  • the three eccentric parts 72 formed at the same position on the input side of the rotation axis Ax1 among the three eccentric shafts 7A, 7B, and 7C rotate synchronously, causing the first planetary gear 301 to oscillate.
  • the three eccentric parts 72 formed at the same position on the output side of the rotation axis Ax1 among the three eccentric shafts 7A, 7B, and 7C rotate synchronously, causing the second planetary gear 302 to oscillate.
  • the shafts 71 of the eccentric shafts 7A, 7B, and 7C rotate (rotate) about the rotation axis Ax1, so that the first planetary gears 301 and the second planetary gears 302 rotate (eccentric motion) about the rotation axis Ax1 with a phase difference of 180 degrees.
  • the first planetary gear 301 and the second planetary gear 302 are respectively meshed with the internal gear 2. Therefore, every time the first planetary gear 301 and the second planetary gear 302 swing, the first planetary gear 301 and the second planetary gear 302 produce a circumferential phase deviation of the difference in the number of teeth (internal teeth 21 and external teeth 31) relative to the internal gear 2, and rotate. This rotation is transmitted to the support flange 18 and the output flange 19 as a revolution around the axis (rotation axis Ax1) of the internal gear 2 of each eccentric shaft 7A, 7B, 7C. As a result, the support flange 18 and the output flange 19 can be centered on the rotation axis Ax1 relative to the gear body. (With the integrated housing 10) rotates relatively.
  • the gear device 1A of this embodiment is different from the first embodiment in that the planetary gear 3 is swung by using a plurality of eccentric shafts 7A, 7B, and 7C arranged at positions offset from the rotation axis Ax1, but is the same as the first embodiment in that a rotation output is obtained by using the swung planetary gear 3. That is, in the gear device 1A, when the planetary gear 3 oscillates and the meshing position of the internal teeth 21 and the external teeth 31 moves along the circumferential direction of the internal gear 2, a relative rotation corresponding to the difference in the number of teeth between the planetary gear 3 and the internal gear 2 is generated between the two gears (the internal gear 2 and the planetary gear 3).
  • the planetary gear 3 rotates (rotates) with the relative rotation of the two gears.
  • a rotation output that is reduced by a relatively high reduction ratio corresponding to the difference in the number of teeth between the two gears can be obtained from the planetary gear 3.
  • 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 respectively composed of angular ball bearings. Specifically, as shown in FIG16 , the first bearing member 601A is arranged on the input side (right side of FIG16 ) of the rotation axis Ax1 when viewed from the planetary gear 3, and the second bearing member 602A is arranged on the output side (left side of FIG16 ) of the rotation axis Ax1 when viewed from the planetary gear 3.
  • the bearing member 6A is configured to withstand radial loads, loads in the thrust direction (along the direction of the rotation axis Ax1), and bending forces (bending moment loads) to the rotation axis Ax1 by using the first bearing member 601A and the second bearing member 602A.
  • the first bearing member 601A and the second bearing member 602A are arranged in opposite directions in the direction parallel to the rotation axis Ax1 relative to the planetary gear 3 on both sides thereof.
  • the bearing member 6A is a "combined angular ball bearing” in which a plurality of (here, two) angular ball bearings are combined.
  • the first bearing member 601A and the second bearing member 602A are "back-to-back combination type" that bear the load in the thrust direction (in the direction along the rotation axis Ax1) in which the inner rings of the respective inner rings approach each other.
  • the gear device 1A the first bearing member 601A and the second bearing member 602A are combined in a state where appropriate preload is applied to the inner rings by tightening the respective inner rings 61 in the direction in which they approach each other.
  • the gear device 1A of the present embodiment includes a support flange 18 and an output flange 19.
  • the flange 18 and the output flange 19 are arranged on both sides of the planetary gear 3 in a direction parallel to the rotation axis Ax1, and are connected to each other by passing through the bracket hole 34 (refer to FIG. 16) of the planetary gear 3.
  • the bracket flange 18 is arranged on the input side (right side of FIG. 16) of the rotation axis Ax1 as viewed from the planetary gear 3
  • the output flange 19 is arranged on the output side (left side of FIG. 16) of the rotation axis Ax1 as viewed from the planetary gear 3.
  • the inner ring of the bearing member 6A (the first bearing member 601A and the second bearing member 602A) is fixed to the bracket flange 18 and the output flange 19.
  • the inner ring of the first bearing member 601A is seamlessly integrated with the bracket flange 18.
  • the inner ring of the second bearing member 602A is seamlessly integrated with the output flange 19.
  • the output flange 19 has a plurality of (three as an example) bracket pins 191 (see FIG. 15 ) protruding from one surface of the output flange 19 toward the input side of the rotation axis Ax1.
  • These plurality of bracket pins 191 respectively penetrate through a plurality of (three as an example) bracket holes 34 formed in the planetary gear 3, and the front ends of the plurality of bracket pins 191 are fixed to the bracket flange 18 by bracket bolts.
  • a gap is ensured between the bracket pin 191 and the inner peripheral surface of the bracket hole 34, and the bracket pin 191 can move in the bracket hole 34, that is, can move relatively to the center of the bracket hole 34.
  • the bracket pin 191 does not contact the inner peripheral surface of the bracket hole 34.
  • the gear device 1A is used in such a manner that the rotation corresponding to the self-rotation component of the planetary gear 3 is extracted 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 extracted as the self-rotation component of the planetary gear 3 from the inner ring 61 connected to the planetary gear 3 by the inner pin 4. In contrast, in the present embodiment, the relative rotation between the planetary gear 3 and the internal gear 2 is extracted from the carrier flange 18 and the output flange 19 integrated with the inner ring.
  • the gear device 1A is used in a state where the outer ring 62 (see FIG. 16 ) of the bearing member 6A is fixed to the housing 10 as a fixed member. That is, the planetary gear 3 is connected to the carrier flange 18 and the output flange 19 as the rotating member by the plurality of eccentric shafts 7A, 7B, and 7C, and the gear body 22 is fixed to the fixed member, so the relative rotation between the planetary gear 3 and the internal gear 2 is extracted from the rotating member (the carrier flange 18 and the output flange 19). In other words, in the present embodiment, when the planetary gear 3 rotates relative to the gear body 22 , the rotational force of the carrier flange 18 and the output flange 19 is extracted as output.
  • 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 fixed to the housing 10. In contrast, in the present embodiment, the gear body 22 as a fixed member is seamlessly and continuously provided with the housing 10 in a direction parallel to the rotation axis Ax1.
  • the housing 10 is cylindrical and constitutes the outer contour of the gear device 1A.
  • the central axis of the cylindrical housing 10 is configured to coincide with the rotation axis Ax1. That is, at least the outer peripheral surface of the housing 10 is a perfect circle centered on the rotation axis Ax1 when viewed from above (viewed from one side in the direction of the rotation axis Ax1).
  • the housing 10 is formed into a cylindrical shape with both end surfaces opened in the direction of the rotation axis Ax1.
  • the housing 10 is seamlessly integrated with the gear body 22 of the internal gear 2, so that the housing 10 and the gear body 22 are treated as one component. Therefore, the inner peripheral surface of the housing 10 includes the inner peripheral surface 221 of the gear body 22.
  • the outer ring 62 of the bearing member 6A is fixed to the housing 10. That is, when viewed from the gear body 22 in the inner peripheral surface of the housing 10, the outer ring 62 of the first bearing member 601A is fixed to the input side (right side of Figure 16) of the rotation axis Ax1 by embedding. On the other hand, the outer ring 62 of the second bearing member 602A is fitted and fixed to the output side (left side in FIG. 16 ) of the rotation axis Ax1 when viewed from the gear body 22 on the inner peripheral surface of the housing 10 .
  • the gear device 1A of the present embodiment further includes a retaining member 80, which is arranged on the inner side of the gear body 22 and retains a plurality of pins 23 between the gear body 22 and the gear body 22 in the radial direction (radial direction of the gear body 22).
  • the retaining member 80 is arranged between the two planetary gears 3, namely the first planetary gear 301 and the second planetary gear 302.
  • the retaining member 80 has a plurality of peripheral grooves 801 on the outer peripheral surface for retaining the plurality of pins 23.
  • the retaining member 80 provided instead of the support body 8 of the first embodiment serves as a means for inhibiting the pins 23 from moving from the gear body 22 by sandwiching the plurality of pins 23 between the gear body 22.
  • the "slit" functions as a direction for movement away from the inner circumferential surface 221 of the gear body 22.
  • the movement of the plurality of pins 23 away from the gear body 22 is regulated by the contact between each of the plurality of pins 23 and the outer circumferential 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 inserting the plurality of pins 23 into the outer circumferential groove 801.
  • the pins 23 are 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.
  • the pin 23 is not easy to be loosened between the retaining member 80 and the gear body 22, and when the internal teeth 21 (pin 23) are meshed with the external teeth 31, even if the force in the direction of pulling the external teeth 31 from the inner peripheral groove 223 acts on the pin 23, the meshing of the internal teeth 21 and the external teeth 31 is not easy to become unstable. Therefore, according to the gear device 1A of this embodiment, there is an advantage that the meshing of the internal teeth 21 and the external teeth 31 is easily stabilized.
  • the internal gear 2 is also an example of the "first gear”
  • 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 held in a state of being able to rotate in the plurality of inner peripheral grooves 223 formed on the inner peripheral surface 221 of the gear body 22, and constitute the internal teeth 21.
  • the second gear is the planetary gear 3 having the external teeth 31 partially meshing with the internal teeth 21.
  • the planetary gear 3 is relatively rotated with respect to the internal gear 2 by swinging the planetary gear 3 around the rotation axis Ax1.
  • the inner surfaces of the plurality of inner peripheral grooves 223 in the skeleton part 225 of the internal gear 2 that are in sliding contact with at least the plurality of pins 23 as another component become the sliding contact parts. Therefore, at least the inner surfaces (sliding contact parts) of the plurality of inner peripheral grooves 223 are covered with the coating layer 224.
  • 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.
  • an annular flexible external gear 3C is arranged inside an annular rigid internal gear 2C, and a wave generator 4C is further arranged inside the flexible external gear 3C.
  • the wave generator 4C causes the flexible external gear 3C to bend into a non-circular shape, thereby causing the external teeth 31C of the flexible external gear 3C to partially mesh with the internal teeth 21C of the rigid internal gear 2C.
  • the wave generator 4C that causes the flexible external gear 3C to bend has a non-circular cam 41C and a bearing 42C that are driven to rotate around the rotation axis Ax1 on the input side.
  • the bearing 42C is arranged between the outer peripheral surface of the cam 41C and the inner peripheral surface 301C of the flexible external 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 through the ball-shaped rolling element 423C.
  • the outer ring 421C can rotate relative to the inner ring 422C by the rolling of the rolling element 423C.
  • the wave generator 4C having the bearing 42C realizes power transmission through the meshing of the internal teeth 21C and the external teeth 31C while bending the flexible externally-toothed gear 3C.
  • a cup-type harmonic gear device is exemplified as an example of the gear device 1C. That is, in the gear device 1C of this embodiment, a cup-shaped flexible external gear 3C is used. The wave generator 4C is combined with the cup-shaped flexible external gear 3C in a manner of being accommodated in the cup-shaped flexible external gear 3C.
  • the rotation axis Ax1 on the input side and the rotation axis Ax2 on the output side are on the same straight line.
  • the rotation axis Ax1 on the input side and the rotation axis Ax2 on the output side are coaxial.
  • the rotation axis Ax1 on the input side is the rotation center of the wave generator 4C to which the input rotation is applied
  • the rotation axis Ax1 on the output side is the rotation center of the flexible external gear 3C that generates the output rotation. That is, in the gear device 1C, it is possible to obtain a relatively high rotation relative to the input rotation on the same axis. The output rotation is reduced in speed ratio.
  • the rigid internal gear 2C is also called a circular spline, which is an annular component having internal teeth 21C.
  • the rigid internal gear 2C has an annular shape whose at least inner circumference is a perfect circle when viewed from above.
  • internal teeth 21C are formed along the circumferential direction of the rigid internal gear 2C.
  • the multiple teeth constituting the internal teeth 21C are all of the same shape and are arranged at equal intervals over the entire area of the inner circumferential direction of the rigid internal gear 2C.
  • the pitch circle of the internal teeth 21C is a perfect circle when viewed from above.
  • the rigid internal gear 2C has a predetermined thickness in the direction of the rotation axis Ax1.
  • the internal teeth 21C are formed over the entire length of the rigid internal gear 2C in the thickness direction.
  • the tooth directions of the internal teeth 21C are all parallel to the rotation axis Ax1.
  • the flexible external gear 3C is also called a flex spline, and is an annular component having external teeth 31C.
  • the flexible external gear 3C is a component formed into a cup shape using a relatively thin-walled metal elastomer (metal plate). That is, the flexible external gear 3C is flexible due to its relatively small (thin) thickness.
  • the flexible external gear 3C has a cup-shaped main body 32C.
  • the main body 32C has a body 321C and a bottom 322C.
  • at least the inner circumferential surface 301C of the body 321C has a cylindrical shape that is a perfect circle when viewed from above.
  • the central axis of the body 321C coincides with the rotation axis Ax1.
  • the bottom 322C is arranged on an opening surface on one side of the body 321C, and has a disc shape that is a perfect circle when viewed from above.
  • the bottom 322C is arranged on the opening surface on the output side of the rotation axis Ax1 among a pair of opening surfaces of the body 321C.
  • the main body 32C realizes a bottomed cylindrical, i.e., cup-shaped shape that is open to the input side of the rotation axis Ax1 through the body 321C and the bottom 322C as a whole.
  • an opening surface 35C is formed on the end surface on the opposite side of the bottom 322C in the direction of the rotation axis Ax1 of the flexible external gear 3C. That is, the flexible external gear 3C is cylindrical with an opening surface 35C on one side of the tooth direction D1 (here, the input side of the rotation axis Ax1).
  • the body 321C and the bottom 322C are integrally formed by one metal member, thereby realizing a seamless main body 32C.
  • the wave generator 4C is combined with the flexible external gear 3C in such a way that the non-circular wave generator 4C is embedded inside the body 321C.
  • the flexible external gear 3C receives an external force in the radial direction (a direction orthogonal to the rotation axis Ax1) from the wave generator 4C from the inside to the outside, thereby elastically Deformed into a non-circular shape.
  • the body portion 321C of the flexible external gear 3C is elastically deformed into an elliptical shape by combining the elliptical wave generator 4C with the flexible external gear 3C (refer to FIG. 18 ).
  • the state in which the flexible external gear 3C is elastically deformed refers to the state in which the wave generator 4C is not combined with the flexible external gear 3C.
  • the state in which the flexible external gear 3C is elastically deformed refers to the state in which the wave generator 4C is combined with the flexible external gear 3C.
  • the wave generator 4C is embedded in the end portion of the inner circumferential surface 301C of the body portion 321C on the side opposite to the bottom portion 322C (the input side of the rotation axis Ax1).
  • the wave generator 4C is embedded in the end portion of the body portion 321C of the flexible externally toothed gear 3C on the side of the opening surface 35C in the direction of the rotation axis Ax1.
  • the end portion of the flexible externally toothed gear 3C on the side of the opening surface 35C in the direction of the rotation axis Ax1 is deformed more than the end portion on the side of the bottom portion 322C, and becomes a shape closer to an elliptical shape. Due to the difference in the amount of deformation in the direction of the rotation axis Ax1, when the flexible externally toothed gear 3C is elastically deformed, the inner circumferential surface 301C of the body portion 321C of the flexible externally toothed gear 3C includes a tapered surface inclined with respect to the rotation axis Ax1.
  • external teeth 31C are formed along the circumferential direction of the body portion 321C at least at the end portion on the side opposite to the bottom portion 322C (the input side of the rotation axis Ax1) of the outer peripheral surface of the body portion 321C.
  • the external teeth 31C are provided at the end portion on the side of the opening surface 35C in the direction of at least the rotation axis Ax1 in the body portion 321C of the flexible external gear 3C.
  • the plurality of teeth constituting the external teeth 31C are all of the same shape and are provided at equal intervals over the entire area in the circumferential direction of the outer peripheral surface of the flexible external gear 3C.
  • the pitch circle of the external teeth 31C is a perfect circle when viewed from above when the flexible external gear 3C is not elastically deformed.
  • the external teeth 31C are formed only within a certain width from the end edge on the side of the opening surface 35C (the input side of the rotation axis Ax1) of the body portion 321C.
  • external teeth 31C are formed on the outer peripheral surface of at least a portion (end portion on the opening surface 35C side) of the body 321C in which the wave generator 4C is inserted in the direction of the rotation axis Ax1.
  • the tooth directions of the external teeth 31C are parallel to the rotation axis Ax1.
  • the flexible external gear 3C thus constructed is arranged inside the rigid internal gear 2C.
  • the flexible external gear 3C is combined with the rigid internal gear 2C in such a way that only the end of the outer peripheral surface of the body portion 321C on the side opposite to the bottom portion 322C (the input side of the rotation axis Ax1) is inserted into the inner side of the rigid internal gear 2C. That is, in the body portion 321C of the flexible external gear 3C, in the direction of the rotation axis Ax1, The portion (the end portion on the opening surface 35C side) where the wave generator 4C is embedded is inserted into the inner side of the rigid internal gear 2C.
  • the outer teeth 31C are formed on the outer peripheral surface of the flexible external gear 3C, and the inner teeth 21C are formed on the inner peripheral surface of the rigid internal gear 2C. Therefore, when the flexible external gear 3C is arranged on the inner side of the rigid internal gear 2C, the outer teeth 31C and the inner teeth 21C are opposite to each other.
  • the number of teeth of the internal teeth 21C in the rigid internal gear 2C is 2N (N is a positive integer) greater than the number of teeth of the external teeth 31C of the flexible external gear 3C.
  • N is "1”
  • the number of teeth of the flexible external gear 3C (external teeth 31C) is "2" greater than the number of teeth of the rigid internal gear 2C (internal teeth 21C).
  • Such a difference in the number of teeth between the flexible external gear 3C and the rigid internal gear 2C defines the reduction ratio of the output rotation relative to the input rotation in the gear device 1C.
  • the relative positions of the flexible external gear 3C and the rigid internal gear 2C in the direction of the rotation axis Ax1 are set in such a way that the center of the tooth direction D1 of the external teeth 31C is opposite to the center of the tooth direction D1 of the internal teeth 21C. That is, the positions of the centers of the tooth direction D1 of the external teeth 31C of the flexible external gear 3C and the internal teeth 21C of the rigid internal gear 2C are aligned with the same position in the direction of the rotation axis Ax1.
  • the size (tooth width) of the tooth direction D1 of the external teeth 31C is larger than the size (tooth width) of the tooth direction D1 of the internal teeth 21C.
  • the internal teeth 21C converge within the range of the tooth direction of the external teeth 31C.
  • the external teeth 31C protrude to at least one side of the tooth direction D1 relative to the internal teeth 21C.
  • the external teeth 31C protrude to both sides of the tooth direction D1 (the input side and the output side of the rotation axis Ax1) relative to the internal teeth 21C.
  • 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 also 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 meshed with each other.
  • the body portion 321C is bent into a non-circular shape, the external teeth 31C of the flexible externally toothed gear 3C are partially meshed 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 (at least The outer teeth 31C at both ends of the ellipse in the long axis direction are meshed with the inner teeth 21C.
  • the major diameter of the pitch circle of the outer teeth 31C that describes the ellipse is consistent with the diameter of the pitch circle of the inner teeth 21C that describes the perfect circle, and the minor diameter of the pitch circle of the outer teeth 31C that describes the ellipse is smaller than the diameter of the pitch circle of the inner teeth 21C that describes the perfect circle.
  • the flexible external-tooth gear 3C is elastically deformed, a part of the multiple teeth constituting the outer teeth 31C mesh with a part of the multiple teeth constituting the inner teeth 21C.
  • a part of the outer teeth 31C can be meshed with a part of the inner teeth 21C.
  • the wave generator 4C is also called a waveform generator, and is a component that causes the flexible external gear 3C to bend, thereby causing the external teeth 31C of the flexible external gear 3C to generate harmonic motion.
  • the wave generator 4C is a component whose outer peripheral shape is a non-circular shape, specifically an elliptical shape, when viewed from above.
  • the rigid internal gear 2C is an example of a "first gear” and the flexible external gear 3C is an example of a "second gear”. That is, the first gear is an annular rigid internal gear 2C having internal teeth 21C.
  • the second gear is an annular flexible external gear 3C having external teeth 31C and arranged on the inner side of the rigid internal gear 2C.
  • the gear device 1C also includes a wave generator 4C arranged on the inner side of the flexible external gear 3C and causing the flexible external gear 3C to bend.
  • the gear device 1C deforms the flexible external gear 3C as the wave generator 4C rotates around the rotation axis Ax1 as a center, causing a portion of the external teeth 31C to mesh with a portion of the internal teeth 21C, thereby causing the flexible external gear 3C to rotate relative to the rigid internal gear 2C according to the difference in the number of teeth with the rigid internal gear 2C. Furthermore, in the framework portion 225 of the rigid internally toothed gear 2C (first gear), at least the surface of the internal teeth 21C with which the external teeth 31C as another member come into sliding contact is covered with the coating layer 224 .
  • the rigid internal gear 2C is an example of a "first gear", for example, a skeleton portion 225 made of aluminum (Al) is used as a base material of the rigid internal gear 2C.
  • the flexible external gear 3C is elastically deformed into an elliptical shape, the external teeth 31C mesh with the internal teeth 21C at two locations on both end sides of the major axis direction of the elliptical shape. In this way, at multiple meshing locations of the internal teeth 21C with the external teeth 31C, sliding contact is generated between the internal teeth 21C and the external teeth 31C.
  • the surface of the internal teeth 21C thereof becomes in contact with the other Since the inner teeth 21C are in sliding contact with the component (the outer teeth 31C of the flexible externally-toothed gear 3C), the surface of the inner teeth 21C is covered with a coating layer 224 made of, for example, iron (Fe).
  • the first gear is a rigid internal gear 2C and the second gear is a flexible external gear 3C.
  • the first gear may be a flexible external gear 3C and the second gear may be a rigid internal gear 2C.
  • the base material of the flexible external gear 3C constitutes the skeleton part, and, for example, the sliding contact part of the flexible external gear 3C with another component (wave generator 4C) is covered with a coating layer.
  • the structure of the third embodiment (including modified examples) can be appropriately combined with the various structures (including modified examples) described in the first embodiment or the second embodiment.
  • the first form of the gear device (1, 1A, 1C) 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 part (225) and a coating layer (224) with a larger specific gravity than the skeleton part (225). At least a portion of the skeleton part (225) that is in sliding contact with another component is covered by the coating layer (224).
  • the skeleton part (225) of the first gear itself is made of a material with a low specific gravity, and thus, even if it has a corresponding thickness, the weight can be kept relatively low.
  • the sliding contact part (with another component) in the skeleton part (225) is covered with a coating layer (224) with a higher specific gravity than the skeleton part (225), the sliding contact part can improve the wear resistance and maintain the strength as the first gear. As a result, a gear device (1, 1A, 1C) that can easily achieve lightness while maintaining strength can be realized.
  • the thermal conductivity of the skeleton portion (225) is higher than that of the coating layer (224).
  • most of the first gear can be formed by the skeleton portion (225) having high thermal conductivity, and the heat dissipation of the first gear can be improved.
  • the coating layer (224) is a sprayed film having a composition different from that of the frame portion (225).
  • the first gear has a base layer (226) on the surface of the skeleton part (225), and the coating layer (224) is stacked on the base layer (226).
  • the adhesion of the coating layer (224) to the skeleton portion (225) can be improved.
  • the grid direction of the base layer (226) is based on the sliding direction of another member in the sliding contact portion.
  • the adhesion of the coating layer (224) to the skeleton portion (225) can be improved.
  • the coating layer (224) has a thickness of 50 ⁇ m or more.
  • 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) held in a state of being able to rotate in a plurality of inner peripheral grooves (223) formed on an inner peripheral surface (221) of the gear body (22) to form internal teeth (21).
  • the planetary gear (3) has external teeth (31) partially meshing with the internal teeth (21).
  • the gear device (1, 1A, 1C) causes the planetary gear (3) to rotate relative to the internal gear (2) by swinging around a rotation axis (Ax1).
  • the inner surface of the plurality of inner peripheral grooves (223) in the skeleton portion (225) of the internal gear (2) with which at least the plurality of pins (23) as another component slide in contact is covered with a coating layer (224).
  • a gear device (1, 1A, 1C) that can be easily reduced in weight while maintaining strength can be realized.
  • the first gear is an annular rigid internal gear (2C) having internal teeth (21C)
  • the second gear is an annular flexible external gear (3C) having external teeth (31C) and arranged on the inner side of the rigid internal gear (2C).
  • the gear device (1, 1A, 1C) also includes a wave generator (4C) arranged on the inner side of the flexible external gear (3C) and causing the flexible external gear (3C) to bend.
  • the gear device (1, 1A, 1C) deforms the flexible external gear (3C) as the wave generator (4C) rotates around the rotation axis (Ax1), causing a portion of the external teeth (31C) to mesh with a portion of the internal teeth (21C), thereby causing the flexible external gear (3C) to bend.
  • the surface of the internal teeth (21C) in the skeleton portion (225) of the rigid internal gear, which is in sliding contact with at least the external teeth (31C) of another component, is covered with a coating layer (224).
  • the wave gear device it is possible to realize a gear device (1, 1A, 1C) that can be easily reduced in weight while maintaining strength.
  • a ninth aspect of the method for manufacturing a gear device is the method for manufacturing a gear device according to any one of the first to eighth aspects, comprising a thermal spraying step of forming a coating layer (224) on at least a portion of a skeleton portion (225) of a first gear by thermal spraying.
  • the skeleton part (225) of the first gear itself is made of a material with a low specific gravity, and thus, even if it has a corresponding thickness, the weight can be kept relatively low.
  • the sliding contact part (with another component) in the skeleton part (225) is covered by the coating layer (224) formed by spraying and having a higher specific gravity than the skeleton part (225), the sliding contact part can improve the wear resistance and maintain the strength as the first gear.
  • a method for manufacturing a gear device (1, 1A, 1C) that can easily achieve lightness while maintaining strength can be achieved.
  • the structures of the second to eighth aspects are not necessary for the gear device (1, 1A, 1C) and can be omitted as appropriate.

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Abstract

一种在维持强度的同时容易实现轻量化的齿轮装置和齿轮装置的制造方法，齿轮装置包括第一齿轮（2）和第二齿轮（3），第二齿轮（3）通过与第一齿轮（2）啮合而相对于第一齿轮（2）旋转，第一齿轮具有骨架部（225）和比重比骨架部（225）大的被覆层（224）。骨架部（225）中的至少与另一部件的滑动接触部位被被覆层（224）覆盖。

Description

齿轮装置和齿轮装置的制造方法
相关申请的交叉引用
本申请基于申请号为申请号202211627601.6、申请日为2022年12月16日的中国专利申请提出，并要求该中国专利申请的优先权，该中国专利申请的全部内容在此引入本申请作为参考。
技术领域
本公开一般涉及齿轮装置和齿轮装置的制造方法，更详细地说，涉及包括第一齿轮和相对于第一齿轮相对旋转的第二齿轮的齿轮装置和齿轮装置的制造方法。
背景技术
作为关联技术，已知一种具有一对滑动构件相互滑动的滑动部的齿轮装置(动力传递装置)(例如，参见专利文献1)。该齿轮装置为内切摆动啮合型的行星齿轮装置，其具有输入轴、与该输入轴一体化的偏心体、通过该偏心体而摆动旋转的外齿齿轮、包括与该外齿齿轮内啮合的内齿的内齿齿轮、配设于该外齿齿轮的轴向外侧且与取出外齿齿轮的自转分量的内销连结的凸缘体。
在上述齿轮装置中，例如形成内齿的外销的两端保持面和与该外销的两端保持面相对的面等的、一对滑动构件的相对的2个滑动表面中的至少一者具有通过通过规定的粗糙度加工而形成的表面粗糙处和碳系被膜。碳系被膜添加有金属元素且形成于该表面粗糙处上。
现有技术文献
专利文献
专利文献1：日本特开2009-41747号公报
发明内容
在上述关联技术中，例如，第一齿轮(内齿齿轮)那样的滑动构件的基材为金属制，为了实施粗糙度加工，需要相应的厚度，且重量比较变大。因此，存在成为作为轮装置整体的轻量化的妨碍的情况。
本公开的目的在于提供在维持强度的同时容易实现轻量化的齿轮装置和齿轮装置的制造方法。
用于解决技术问题的方案
本公开的一形态的齿轮装置包括第一齿轮和第二齿轮。所述第二齿轮通过与所述第一齿轮啮合从而相对于所述第一齿轮相对旋转。所述第一齿轮具有骨架部和比重比所述骨架部大的被覆层。所述骨架部中的至少与另一部件滑动接触的滑动接触部位被所述被覆层覆盖。
本公开的一形态的齿轮装置的制造方法为所述齿轮装置的制造方法，具有通过喷镀在所述第一齿轮的所述骨架部的至少一部分形成所述被覆层的喷镀工序。
发明效果
根据本公开，能够提供在维持强度的同时容易实现轻量化的齿轮装置和齿轮装置的制造方法。
附图说明
图1示出包含实施方式一的内啮合行星齿轮装置在内的执行器的概略结构的立体图。
图2是上述的内啮合行星齿轮装置的从旋转轴的输出侧观察到的概略的分解立体图。
图3是上述的内啮合行星齿轮装置的概略剖视图。
图4是示出上述的内啮合行星齿轮装置的、图3的A1-A1线剖视图。
图5A是以单体示出上述的内啮合行星齿轮装置的行星齿轮的立体图。
图5B是以单体示出上述的内啮合行星齿轮装置的行星齿轮的主视图。
图6A是以单体示出上述的内啮合行星齿轮装置的轴承构件的立体图。
图6B是以单体示出上述的内啮合行星齿轮装置的轴承构件的主视图。
图7A是以单体示出上述的内啮合行星齿轮装置的偏心轴的立体图。
图7B是以单体示出上述的内啮合行星齿轮装置的偏心轴的主视图。
图8A是以单体示出上述的内啮合行星齿轮装置的支承体的立体图。
图8B是以单体示出上述的内啮合行星齿轮装置的支承体的主视图。
图9是示出上述的内啮合行星齿轮装置的、图3的区域Z1的放大图。
图10是示出上述的内啮合行星齿轮装置的、图3的B1-B1线剖视图。
图11是将示出上述的内啮合行星齿轮装置的、图9的内齿21与外齿31的啮合部位放大的概略剖视图。
图12是示出上述的内啮合行星齿轮装置的、图11的A1-A1线截面的概略图。
图13A是示出上述的内啮合行星齿轮装置的内齿齿轮的内周槽的概略立体图。
图13B是示出上述的内啮合行星齿轮装置的内齿齿轮的内周槽的概略立体图。
图14是示出实施方式二的内啮合行星齿轮装置的概略结构的立体图。
图15是上述的内啮合行星齿轮装置的从旋转轴的输入侧观察到的分解立体图。
图16是上述的内啮合行星齿轮装置的概略剖视图。
图17是示出实施方式三的第一比较例的谐波齿轮装置的概略结构的剖视图。
图18是上述的谐波齿轮装置的从旋转轴的输入侧观察到的概略图。
图19是上述的谐波齿轮装置的从旋转轴的输出侧观察到的概略的分解立体图。
图20是上述的谐波齿轮装置的从旋转轴的输入侧观察到的概略的分解立 体图。
具体实施方式
(实施方式一)
(1)概要
以下，参照图1～图3说明关于本实施方式的内啮合行星齿轮装置1的概要。本公开实施例参照的附图都是示意性的图，图中的各结构要素的大小及厚度各自的比未必反映实际的尺寸比。例如，图1～图3中的内齿21及外齿31的齿形、尺寸及齿数等都不过是为了说明而示意性地表示的，其主旨并不限定为图示的形状。
本实施方式的内啮合行星齿轮装置(以下，也简称为“齿轮装置1”)是包括内齿齿轮2、行星齿轮3和多个内销4的齿轮装置。在该齿轮装置1中，在环状内齿齿轮2的内侧配置有行星齿轮3，而且，在行星齿轮3的内侧配置有偏心体轴承5。偏心体轴承5具有偏心体内圈51及偏心体外圈52，偏心体内圈51绕着从偏心体内圈51的中心C1(参照图3)偏离的旋转轴Ax1(参照图3)进行旋转(偏心运动)，由此使行星齿轮3摆动。偏心体内圈51例如通过***于偏心体内圈51的偏心轴7的旋转而绕着旋转轴Ax1进行旋转(偏心运动)。另外，内啮合行星齿轮装置1还包括轴承构件6，轴承构件6具有外圈62及内圈61。内圈61配置于外圈62的内侧，并被支承为能够相对于外圈62相对旋转。
内齿齿轮2具有内齿21且固定于外圈62。特别是在本实施方式中，内齿齿轮2具有环状的齿轮主体22和多个销23。多个销23以能够自转的状态保持于齿轮主体22的内周面221而构成内齿21。行星齿轮3具有与内齿21局部性地啮合的外齿31。也就是说，在内齿齿轮2的内侧，行星齿轮3内切于内齿齿轮2，成为外齿31的一部分与内齿21的一部分啮合的状态。在该状态下，当偏心轴7旋转时行星齿轮3摆动，内齿21与外齿31的啮合位置沿内齿齿轮2的圆周方向移动，在两齿轮(内齿齿轮2及行星齿轮3)之间产生与行星齿轮3 和内齿齿轮2的齿数差对应的相对旋转。此处，如果将内齿齿轮2固定，则伴随着两齿轮的相对旋转而行星齿轮3旋转(自转)。其结果是，从行星齿轮3获得与两齿轮的齿数差相应地以比较高的减速比被减速了的旋转输出。
这种齿轮装置1以下述方式使用：将行星齿轮3的相当于自转分量的旋转作为例如与轴承构件6的内圈61一体化的输出轴的旋转而取出。由此，齿轮装置1以偏心轴7为输入侧，以输出轴为输出侧，作为比较高的减速比的齿轮装置发挥功能。因此，在本实施方式的齿轮装置1中，为了将行星齿轮3的相当于自转分量的旋转向轴承构件6的内圈61传递而利用多个内销4将行星齿轮3与内圈61连结。多个内销4在分别***到形成于行星齿轮3的多个内销孔32的状态下，分别一边在内销孔32内公转一边相对于内齿齿轮2相对旋转。也就是说，内销孔32具有比内销4大的直径，内销4能够以***于内销孔32的状态在内销孔32内公转的方式进行移动。并且，行星齿轮3的摆动分量、也就是说行星齿轮3的公转分量通过行星齿轮3的内销孔32与内销4的游嵌而被吸收。换言之，多个内销4以分别在多个内销孔32内公转的方式进行移动，由此吸收行星齿轮3的摆动分量。因此，通过多个内销4，将除了行星齿轮3的摆动分量(公转分量)之外的、行星齿轮3的旋转(自转分量)向轴承构件6的内圈61传递。
然而，在这种齿轮装置1中，内销4在行星齿轮3的内销孔32内一边公转，一边向多个内销4传递行星齿轮3的旋转，因此作为第一关联技术，已知有使用装配于内销4而能够以内销4为轴进行旋转的内滚子的技术。也就是说，在第一关联技术中，内销4保持为以被压入于内圈61(或与内圈61一体的支架)的状态，当内销4在内销孔32内公转之际，内销4相对于内销孔32的内周面321滑动。因此，作为第一关联技术，为了减少因内销孔32的内周面321与内销4之间的摩擦阻力而引起的损失而使用内滚子。但是，如果是第一关联技术那样包括内滚子的结构，则内销孔32需要具有使带内滚子的内销4能够公转的直径，内销孔32的小型化困难。当内销孔32的小型化困难时，会妨碍行星齿轮3的小型化(特别是小径化)，甚至妨碍齿轮装置1整体的小型化。本实施方 式的齿轮装置1通过以下的结构而能够提供容易小型化的内啮合行星齿轮装置1。
即，如图1～图3所示，本实施方式的齿轮装置1包括轴承构件6、内齿齿轮2、行星齿轮3和多个内销4。轴承构件6具有外圈62及配置于外圈62的内侧的内圈61。内圈61被支承为相对于外圈62能够相对旋转。内齿齿轮2具有内齿21且固定于外圈62。行星齿轮3具有与内齿21局部性地啮合的外齿31。多个内销4在分别***到形成于行星齿轮3的多个内销孔32的状态下，一边在内销孔32内公转一边相对于内齿齿轮2相对旋转。此处，多个内销4各自以能够旋转的状态保持于内圈61。进一步，多个内销4各自将至少一部分配置于在轴承构件6的轴向上与轴承构件6相同的位置。
根据该形态，多个内销4各自以能够自转的状态由内圈61保持，因此内销4在内销孔32内公转之际，内销4自身能够自转。因此，即使不使用装配于内销4而能够以内销4为轴进行旋转的内滚子，也能够减少因内销孔32的内周面321与内销4之间的摩擦阻力而引起的损失。因此，对于本实施方式的齿轮装置1而言，内滚子并非必须，故而有容易小型化的优点。而且，多个内销4各自将至少一部分配置于在轴承构件6的轴向上与轴承构件6相同的位置，因此能够将轴承构件6的轴向上的齿轮装置1的尺寸抑制得小。也就是说，与轴承构件6和内销4沿轴承构件6的轴向并列(相对)的结构相比，在本实施方式的齿轮装置1中，能够减小轴向上的齿轮装置1的尺寸，从而能够对齿轮装置1的进一步小型化(薄型化)作出贡献。
进一步，如果行星齿轮3的尺寸与上述第一关联技术相同，则与上述第一关联技术相比，例如，还能够增加内销4的个数(根数)从而使旋转的传递顺畅，或者使内销4***从而提高强度。
另外，在这种齿轮装置1中，内销4需要在行星齿轮3的内销孔32内公转，因此作为第二关联技术，存在多个内销4仅由内圈61(或与内圈61一体的支架)保持的情况。根据第二关联技术，多个内销4的定芯的精度难以提高，由于定芯不佳而可能会导致振动的产生、及传递效率的下降等不良状况。也就是 说，多个内销4分别一边在内销孔32内公转一边相对于内齿齿轮2相对旋转，由此将行星齿轮3的自转分量向轴承构件6的内圈61传递。此时，如果因多个内销4的定芯的精度不够而多个内销4的旋转轴相对于内圈61的旋转轴偏离或倾斜，则成为定芯不佳的状态，可能导致振动的产生及传递效率的下降等不良状况。本实施方式的齿轮装置1通过以下的结构，能够提供难以产生因多个内销4的定芯不佳而引起的不良状况的内啮合行星齿轮装置1。
即，图1～图3所示，本实施方式的齿轮装置1包括内齿齿轮2、行星齿轮3、多个内销4和支承体8。内齿齿轮2具有环状的齿轮主体22和多个销23。多个销23以能够自转的状态保持于齿轮主体22的内周面221而构成内齿21。行星齿轮3具有与内齿21局部性地啮合的外齿31。多个内销4在分别***到在行星齿轮3形成的多个内销孔32的状态下，一边在内销孔32内公转一边相对于齿轮主体22相对旋转。支承体8为环状并支承多个内销4。此处，支承体8通过使外周面81与多个销23接触而被进行位置限制。
根据该形态，多个内销4由环状的支承体8支承，因此多个内销4由支承体8捆束，可抑制多个内销4的相对的偏离及倾斜。而且，支承体8的外周面81与多个销23接触，由此进行支承体8的位置限制。总之，通过多个销23进行支承体8的定芯，结果是，关于被支承体8支承的多个内销4也利用多个销23进行定芯。因此，根据本实施方式的齿轮装置1，容易实现多个内销4的定芯的精度提高，并具有难以产生因多个内销4的定芯不佳而引起的不良状况这样的优点。
另外，如图1所示，本实施方式的齿轮装置1与驱动源101一起构成执行器100。换言之，本实施方式的执行器100包括齿轮装置1和驱动源101。驱动源101产生用于使行星齿轮3摆动的驱动力。具体而言，驱动源101使偏心轴7以旋转轴Ax1为中心旋转，由此使行星齿轮3摆动。
(2)定义
本公开所说的“环状”是指至少在俯视时如在内侧形成包围而成的空间(区域)的圈(环)那样的形状，并不限于在俯视时为正圆的圆形状(圆环状)，例 如也可以是椭圆形状和多边形状等。进一步，例如，即使是杯状那样具有底部的形状，只要其周壁为环状，就包含在“环状”内。
本公开所说的“游嵌”是指嵌成具有游隙(间隙)的状态，内销孔32是供内销4游嵌的孔。也就是说，内销4以在与内销孔32的内周面321之间确保了空间的富余度(间隙)的状态***于内销孔32。换言之，内销4中的、至少***于内销孔32的部位的直径比内销孔32的直径小(细)。因此，内销4在***于内销孔32的状态下，能够在内销孔32内移动，也就是说能够相对于内销孔32的中心相对地移动。由此，内销4能够在内销孔32内公转。但是，在内销孔32的内周面321与内销4之间，无需确保作为空洞的间隙，例如，也可以在该间隙填充液体等流体。
本公开所说的“公转”是指某物体环绕通过该物体的中心(重心)的中心轴以外的旋转轴转圈，当某物体公转时，该物体的中心沿着以旋转轴为中心的公转轨道移动。因此，例如，在某物体以与通过该物体的中心(重心)的中心轴平行的偏心轴为中心旋转的情况下，该物体以偏心轴为旋转轴公转。作为一例，内销4环绕通过内销孔32的中心的旋转轴转圈地在内销孔32内公转。
另外，在本公开中，有将旋转轴Ax1的一方侧(图3的左侧)称为“输入侧”，将旋转轴Ax1的另一方侧(图3的右侧)称为“输出侧”的情况。在图3的例中，从旋转轴Ax1的“输入侧”向旋转体(偏心体内圈51)赋予旋转，从旋转轴Ax1的“输出侧”取出多个内销4(内圈61)的旋转。但是，“输入侧”及“输出侧”只不过是为了说明而赋予的标签，其主旨并不限定从齿轮装置1观察到的、输入及输出的位置关系。
在本公开所说的“旋转轴”是指成为旋转体的旋转运动的中心的虚拟性的轴(直线)。也就是说，旋转轴Ax1是不伴有实体的虚拟轴。偏心体内圈51以旋转轴Ax1为中心进行旋转运动。
在本公开实施例中所说的“内齿”和“外齿”分别指多个“齿”的集合(组)而不是单体的“齿”。也就是说，内齿齿轮2的内齿21由配置于内齿齿轮2(齿轮主体22)的内周面221的多个齿的集合构成。同样，行星齿轮3的外齿31 由配置于行星齿轮3的外周面的多个齿的集合构成。
(3)结构
以下，关于本实施方式的内啮合行星齿轮装置1的详细结构，参照图1～图8B进行说明。
图1是示出包含齿轮装置1的执行器100的概略结构的立体图。在图1中，示意性地示出驱动源101。图2是齿轮装置1的从旋转轴Ax1的输出侧观察到的概略的分解立体图。图3是齿轮装置1的概略剖视图。图4是图3的A1-A1线剖视图。其中，在图4中，关于偏心轴7以外的部件，虽然也是剖面但是省略了剖面线。进一步，在图4中，省略了齿轮主体22的内周面221的图示。图5A及图5B是以单体示出行星齿轮3的立体图及主视图。图6A及图6B是以单体示出轴承构件6的立体图及主视图。图7A及图7B是以单体示出偏心轴7的立体图及主视图。图8A及图8B是以单体示出支承体8的立体图及主视图。
(3.1)整体结构
如图1～图3所示，本实施方式的齿轮装置1包括内齿齿轮2、行星齿轮3、多个内销4、偏心体轴承5、轴承构件6、偏心轴7和支承体8。另外，在本实施方式中，齿轮装置1还包括第一轴承91、第二轴承92及壳体10。在本实施方式中，作为齿轮装置1的结构要素的内齿齿轮2、行星齿轮3、多个内销4、偏心体轴承5、轴承构件6、偏心轴7及支承体8等的材质是不锈钢、铸铁、机械结构用碳素钢、铬钼钢、磷青铜或铝青铜等金属、或者铝或钛等轻金属。此处所说的金属(包含轻金属在内)包括实施了氮化处理等表面处理的金属。在本实施方式中，特别作为一例，使得内齿齿轮2的齿轮主体22由铝制成。
另外，在本实施方式中，作为齿轮装置1的一例，例示使用了摆线类齿形的内切式行星齿轮减速装置。也就是说，本实施方式的齿轮装置1包括具有摆线类曲线齿形的内切式的行星齿轮3。
另外，在本实施方式中，作为一例，齿轮装置1在内齿齿轮2的齿轮主体22与轴承构件6的外圈62一起固定于壳体10等固定构件的状态下使用。由此，伴随着内齿齿轮2与行星齿轮3的相对旋转，行星齿轮3相对于固定构件(壳 体10等)相对旋转。
进一步，在本实施方式中，在将齿轮装置1用于执行器100的情况下，通过向偏心轴7施加作为输入的旋转力，从而从与轴承构件6的内圈61一体化的输出轴取出作为输出的旋转力。也就是说，齿轮装置1以偏心轴7的旋转为输入旋转，以与内圈61一体化的输出轴的旋转为输出旋转进行动作。由此，在齿轮装置1中，可得到相对于输入旋转以比较高的减速比被减速了的输出旋转。
驱动源101是马达(电动机)等动力的产生源。由驱动源101产生的动力向齿轮装置1中的偏心轴7传递。具体而言，驱动源101经由输入轴与偏心轴7相连，由驱动源101产生的动力经由输入轴向偏心轴7传递。由此，驱动源101能够使偏心轴7旋转。
进一步，在本实施方式的齿轮装置1中，如图3所示，输入侧的旋转轴Ax1与输出侧的旋转轴Ax1处于同一直线上。换言之，输入侧的旋转轴Ax1与输出侧的旋转轴Ax1为同轴。此处，输入侧的旋转轴Ax1是被赋予输入旋转的偏心轴7的旋转中心，输出侧的旋转轴Ax1是产生输出旋转的内圈61(及输出轴)的旋转中心。也就是说，在齿轮装置1中，能够在同轴上相对于输入旋转而得到以比较高的减速比被减速了的输出旋转。
如图4所示，内齿齿轮2是具有内齿21的环状的部件。在本实施方式中，内齿齿轮2具有至少内周面在俯视观察下为正圆的圆环状。在圆环状的内齿齿轮2的内周面，沿着内齿齿轮2的圆周方向形成有内齿21。构成内齿21的多个齿全部为同一形状，且以等间距地设置于内齿齿轮2的内周面的圆周方向的整个区域。也就是说，内齿21的节圆在俯视时为正圆。内齿21的节圆的中心处于旋转轴Ax1上。另外，内齿齿轮2沿旋转轴Ax1的方向具有规定的厚度。内齿21的齿向均与旋转轴Ax1平行。内齿21的齿向方向的尺寸比内齿齿轮2的厚度方向稍小。
此处，如上所述，内齿齿轮2具有环状(圆环状)的齿轮主体22和多个销23。多个销23以能够自转的状态保持于齿轮主体22的内周面221而构成内齿21。换言之，多个销23分别作为构成内齿21的多个齿发挥功能。具体而言， 如图2所示，在齿轮主体22的内周面221在圆周方向的整个区域形成有多个内周槽223。多个内周槽223全部为同一形状，且以等间距地设置。多个内周槽223均与旋转轴Ax1平行，并遍及齿轮主体22的厚度方向的全长地形成。多个销23以嵌于多个内周槽223的方式组合于齿轮主体22。多个销23各自被保持为能够在内周槽223内自转的状态。另外，齿轮主体22(与外圈62一起)固定于壳体10。因此，在齿轮主体22形成有固定用的多个固定孔222。
如图4所示，行星齿轮3是具有外齿31的环状的部件。在本实施方式中，行星齿轮3具有至少外周面在俯视观察下成为正圆的圆环状。在圆环状的行星齿轮3的外周面，沿着行星齿轮3的圆周方向形成有外齿31。构成外齿31的多个齿全部为同一形状，且等间距地设置于外齿齿轮3的外周面的圆周方向的整个区域。也就是说，外齿31的节圆在俯视观察下为正圆。外齿31的节圆的中心C1处于距旋转轴Ax1偏离了距离ΔL(参照图4)的位置。另外，行星齿轮3沿旋转轴Ax1的方向具有规定的厚度。外齿31均遍及行星齿轮3的厚度方向的全长地形成。外齿31的齿向均与旋转轴Ax1平行。在行星齿轮3中，与内齿齿轮2不同，外齿31与行星齿轮3的主体由一个金属构件一体形成。
此处，对于行星齿轮3组合有偏心体轴承5及偏心轴7。也就是说，在行星齿轮3形成有呈圆形状地开口的开口部33。开口部33是沿着厚度方向贯通行星齿轮3的孔。在俯视观察下，开口部33的中心与行星齿轮3的中心一致，开口部33的内周面(行星齿轮3的内周面)与外齿31的节圆为同心圆。在行星齿轮3的开口部33收容有偏心体轴承5。进一步，通过将偏心轴7***于偏心体轴承5(的偏心体内圈51)，来将偏心体轴承5及偏心轴7组合于行星齿轮3。在行星齿轮3组合有偏心体轴承5及偏心轴7的状态下，当偏心轴7旋转时，行星齿轮3绕着旋转轴Ax1摆动。
这样构成的行星齿轮3配置于内齿齿轮2的内侧。在俯视观察下，行星齿轮3形成得比内齿齿轮2小一圈，行星齿轮3在与内齿齿轮2组合的状态下，能够在内齿齿轮2的内侧摆动。此时，在行星齿轮3的外周面形成有外齿31，在内齿齿轮2的内周面形成有内齿21。因此，在内齿齿轮2的内侧配置有行星 齿轮3的状态下，外齿31与内齿21相互相对。
进一步，外齿31的节圆比内齿21的节圆小一圈。并且，在行星齿轮3内切于内齿齿轮2的状态下，外齿31的节圆的中心C1处于从内齿21的节圆的中心(旋转轴Ax1)偏离了距离ΔL(参照图4)的位置。因此，外齿31与内齿21的至少一部分隔着间隙相对，不存在圆周方向的整体相互啮合的情况。但是，行星齿轮3在内齿齿轮2的内侧绕着旋转轴Ax1摆动(公转)，因此外齿31与内齿21局部性地啮合。也就是说，通过行星齿轮3绕着旋转轴Ax1摆动，如图4所示，构成外齿31的多个齿中的一部分的齿与构成内齿21的多个齿中的一部分的齿啮合。结果是，在齿轮装置1中，能够使外齿31的一部分与内齿21的一部分啮合。
此处，内齿齿轮2中的内齿21的齿数比行星齿轮3的外齿31的齿数多N(N为正整数)。在本实施方式中，作为一例，N为“1”，行星齿轮3的(外齿31的)齿数比内齿齿轮2的(内齿21的)齿数多“1”。这样的行星齿轮3与内齿齿轮2的齿数差规定了齿轮装置1中的输出旋转相对于输入旋转的减速比。
另外，在本实施方式中，作为一例，行星齿轮3的厚度比内齿齿轮2中的齿轮主体22的厚度小。进一步，外齿31的齿向方向(与旋转轴Ax1平行的方向)的尺寸比内齿21的齿向方向(与旋转轴Ax1平行的方向)的尺寸小。换言之，在与旋转轴Ax1平行的方向上，外齿31收于内齿21的齿向的范围内。
在本实施方式中，如上所述，行星齿轮3的相当于自转分量的旋转作为与轴承构件6的内圈61一体化了的输出轴的旋转(输出旋转)而取出。因此，行星齿轮3利用多个内销4与内圈61连结。如图5A及图5B所示，在行星齿轮3形成有用于供多个内销4***的多个内销孔32。内销孔32设置与内销4相同的个数，在本实施方式中，作为一例，内销孔32及内销4各设置18个。多个内销孔32各自是呈圆形状地开口并沿着厚度方向贯穿行星齿轮3的孔。多个(此处为18个)内销孔32在与开口部33同心的虚拟圆上沿圆周方向等间隔地配置。
多个内销4是将行星齿轮3与轴承构件6的内圈61连结的部件。多个内销4各自形成为圆柱状。多个内销4的直径及长度在多个内销4中相同。内销4 的直径比内销孔32的直径小一圈。由此，内销4以在与内销孔32的内周面321之间确保有空间的富余度(间隙)的状态***于内销孔32(参照图4)。
轴承构件6是具有外圈62及内圈61并用于取出齿轮装置1的输出作为内圈61相对于外圈62的旋转的部件。轴承构件6除了外圈62及内圈61之外，还具有多个滚动体63(参照图3)。
如图6A及图6B所示，外圈62及内圈61均为环状的部件。外圈62及内圈61均具有在俯视观察下为正圆的圆环状。内圈61比外圈62小一圈并配置于外圈62的内侧。此处，外圈62的内径由于比内圈61的外径大，所以在外圈62的内周面与内圈61的外周面之间产生间隙。
内圈61具有供多个内销4分别***的多个保持孔611。保持孔611设置与内销4相同的个数，在本实施方式中，作为一例，保持孔611设置18个。如图6A及图6B所示，多个保持孔611各自是呈圆形状地开口并沿着厚度方向贯穿内圈61的孔。多个(此处为18个)保持孔611在与内圈61的外周同心的虚拟圆上沿圆周方向等间隔地配置。保持孔611的直径为内销4的直径以上，且比内销孔32的直径小。
进一步，内圈61与输出轴一体化，且取出内圈61的旋转作为输出轴的旋转。因此，在内圈61形成有用于安装输出轴的多个输出侧安装孔612(参照图2)。在本实施方式中，多个输出侧安装孔612比多个保持孔611更靠内侧，且配置于与内圈61的外周同心的虚拟圆上。
外圈62与内齿齿轮2的齿轮主体22一起固定于壳体10等固定构件。因此，在外圈62形成有固定用的多个透孔621。具体而言，如图3所示，外圈62在与壳体10之间夹有齿轮主体22的状态下，利用穿过透孔621及齿轮主体22的固定孔222的固定用的螺钉(螺栓)60而固定于壳体10。
多个滚动体63配置于外圈62与内圈61之间的间隙。多个滚动体63沿外圈62的圆周方向并列配置。多个滚动体63全部为同一形状的金属部件，在外圈62的圆周方向的整个区域等间距地设置。
在本实施方式中，作为一例，轴承构件6为交叉滚子轴承。也就是说，轴 承构件6具有圆筒状的滚子作为滚动体63。并且，圆筒状的滚动体63的轴相对于与旋转轴Ax1正交的平面具有45度的倾斜，并且与内圈61的外周正交。进一步，在内圈61的圆周方向上相互相邻的一对滚动体63配置成轴向相互正交的朝向。在这样的由交叉滚子轴承构成的轴承构件6中，径向的载荷、推力方向(沿着旋转轴Ax1的方向)的载荷、及对于旋转轴Ax1的弯曲力(弯曲力矩载荷)均容易承受。而且，通过一个轴承构件6，能够耐受这三种载荷，从而能够确保所需的刚性。
如图7A及图7B所示，偏心轴7是圆筒状的部件。偏心轴7具有轴心部71和偏心部72。轴心部71具有至少外周面在俯视观察下为正圆的圆筒状。轴心部71的中心(中心轴)与旋转轴Ax1一致。偏心部72具有至少外周面在俯视观察下为正圆的圆盘状。偏心部72的中心(中心轴)与从旋转轴Ax1偏离的中心C1一致。此处，旋转轴Ax1与中心C1之间的距离ΔL(参照图7B)成为偏心部72相对于轴心部71的偏心量。偏心部72呈在轴心部71的长度方向(轴向)的中央部从轴心部71的外周面遍及整周地突出的凸缘形状。根据上述的结构，对于偏心轴7而言，通过轴心部71以旋转轴Ax1为中心旋转(自转)，从而使得偏心部72进行偏心运动。
在本实施方式中，轴心部71及偏心部72由一个金属构件一体形成，由此，实现无缝的偏心轴7。这样的形状的偏心轴7与偏心体轴承5一起组合于行星齿轮3。因此，当偏心轴7以在行星齿轮3组合有偏心体轴承5及偏心轴7的状态进行旋转时，行星齿轮3绕着旋转轴Ax1摆动。
进一步，偏心轴7具有沿轴向(长度方向)贯通轴心部71的贯通孔73。贯通孔73在轴心部71中的轴向的两端面呈圆形状地开口。贯通孔73的中心(中心轴)与旋转轴Ax1一致。能够在贯通孔73穿过例如电源线及信号线等线缆类。
另外，在本实施方式中，从驱动源101向偏心轴7施加作为输入的旋转力。因此，在偏心轴7形成有用于安装与驱动源101相连的输入轴的多个输入侧安装孔74(参照图7A及图7B)。在本实施方式中，多个输入侧安装孔74在轴心 部71的轴向的一端面的贯通孔73的周围，并配置在与贯通孔73同心的虚拟圆上。
偏心体轴承5是具有偏心体外圈52及偏心体内圈51、并吸收偏心轴7的旋转中的自转分量、并用于仅将除了偏心轴7的自转分量之外的偏心轴7的旋转也就是说偏心轴7的摆动分量(公转分量)向行星齿轮3传递的部件。偏心体轴承5除了偏心体外圈52及偏心体内圈51以外，还具有多个滚动体53(参照图3)。
偏心体外圈52及偏心体内圈51均为环状的部件。偏心体外圈52及偏心体内圈51均具有在俯视观察下为正圆的圆环状。偏心体内圈51比偏心体外圈52小一圈，且配置于偏心体外圈52的内侧。此处，偏心体外圈52的内径比偏心体内圈51的外径大，因此在偏心体外圈52的内周面与偏心体内圈51的外周面之间产生间隙。
多个滚动体53配置于偏心体外圈52与偏心体内圈51之间的间隙。多个滚动体53沿偏心体外圈52的圆周方向并列配置。多个滚动体53全部为同一形状的金属部件，并等间距地配置于偏心体外圈52的圆周方向的整个区域。在本实施方式中，作为一例，偏心体轴承5由使用滚珠作为滚动体53的深沟球轴承构成。
此处，偏心体内圈51的内径与偏心轴7中的偏心部72的外径一致。偏心体轴承5以在偏心体内圈51***有偏心轴7的偏心部72的状态与偏心轴7组合。另外，偏心体外圈52的外径与行星齿轮3中的开口部33的内径(直径)一致。偏心体轴承5以在行星齿轮3的开口部33嵌入有偏心体外圈52的状态与行星齿轮3组合。换言之，在行星齿轮3的开口部33收容有装配于偏心轴7的偏心部72的状态的偏心体轴承5。
另外，在本实施方式中，作为一例，偏心体轴承5中的偏心体内圈51的宽度方向(与旋转轴Ax1平行的方向)的尺寸与偏心轴7的偏心部72的厚度大体相同。偏心体外圈52的宽度方向(与旋转轴Ax1平行的方向)的尺寸比偏心体内圈51的宽度方向的尺寸稍小。进一步，偏心体外圈52的宽度方向的尺 寸比行星齿轮3的厚度大。因此，在与旋转轴Ax1平行的方向上，在偏心体轴承5的范围内收有行星齿轮3。另一方面，偏心体外圈52的宽度方向的尺寸比内齿21的齿向方向(与旋转轴Ax1平行的方向)的尺寸小。因此，在与旋转轴Ax1平行的方向上，在内齿齿轮2的范围内收有偏心体轴承5。
在偏心体轴承5及偏心轴7组合于行星齿轮3的状态下，当偏心轴7旋转时，在偏心体轴承5中，偏心体内圈51绕着从偏心体内圈51的中心C1偏离的旋转轴Ax1旋转(偏心运动)。此时，偏心轴7的自转分量由偏心体轴承5吸收。因此，通过偏心体轴承5仅将除了偏心轴7的自转分量之外的偏心轴7的旋转、也就是说偏心轴7的摆动分量(公转分量)向行星齿轮3传递。由此，当偏心轴7以在行星齿轮3组合有偏心体轴承5及偏心轴7的状态进行旋转时，行星齿轮3绕着旋转轴Ax1摆动。
如图8A及图8B所示，支承体8是形成为环状并支承多个内销4的部件。支承体8具有供多个内销4***的多个支承孔82。支承孔82设置与内销4相同的个数，在本实施方式中作为一例，支承孔82设置18个。如图8A及图8B所示，多个支承孔82各自是呈圆形状地开口并沿着厚度方向贯通支承体8的孔。多个(此处为18个)支承孔82在与支承体8的外周面81同心的虚拟圆上沿圆周方向等间隔地配置。支承孔82的直径为内销4的直径以上，且比内销孔32的直径小。在本实施方式中，作为一例，支承孔82的直径与形成于内圈61的保持孔611的直径相等。
如图3所示，支承体8以从旋转轴Ax1的一方侧(输入侧)与行星齿轮3相对的方式配置。并且，通过向多个支承孔82***多个内销4，支承体8以捆束多个内销4的方式发挥功能。进一步，支承体8通过使外周面81与多个销23接触而被进行位置限制。由此，通过多个销23来进行支承体8的定芯，结果是，关于被支承体8支承多个内销4，也利用多个销23进行定芯。关于支承体8，在“(3.3)支承体”一栏中进行详细说明。
第一轴承91及第二轴承92分别装配于偏心轴7的轴心部71。具体而言，如图3所示，第一轴承91及第二轴承92以在与旋转轴Ax1平行的方向上夹着 偏心部72的方式装配于轴心部71中的偏心部72的两侧。从偏心部72观察时，第一轴承91配置于旋转轴Ax1的输入侧。从偏心部72观察时，第二轴承92配置于旋转轴Ax1的输出侧。第一轴承91将偏心轴7保持为相对于壳体10能够旋转。第二轴承92将偏心轴7保持为相对于轴承构件6的内圈61能够旋转。由此，偏心轴7的轴心部71在与旋转轴Ax1平行的方向上的偏心部72的两侧的两个部位处被保持为能够旋转。
壳体10为圆筒状，并在旋转轴Ax1的输出侧具有凸缘部11。在凸缘部11形成有用于将壳体10自身固定的多个设置孔111。另外，在壳体10中的旋转轴Ax1的输出侧的端面形成有轴承孔12。轴承孔12呈圆形状地开口。通过向轴承孔12内嵌入第一轴承91，从而将第一轴承91安装于壳体10。
另外，在壳体10的旋转轴Ax1的输出侧的端面且在轴承孔12的周围形成有多个螺纹孔13。多个螺纹孔13用于将内齿齿轮2的齿轮主体22及轴承构件6的外圈62固定于壳体10而使用。具体而言，固定用的螺钉60穿过外圈62的透孔621及齿轮主体22的固定孔222而拧紧到螺纹孔13，由此将齿轮主体22及外圈62固定于壳体10。
另外，如图3所示，本实施方式的齿轮装置1还包括多个油封14、15、16等。油封14装配于偏心轴7的旋转轴Ax1的输入侧的端部，并填塞壳体10与偏心轴7(轴心部71)之间的间隙。油封15装配于偏心轴7的旋转轴Ax1的输出侧的端部，并填塞内圈61与偏心轴7(轴心部71)之间的间隙。油封16装配于轴承构件6的旋转轴Ax1的输出侧的端面，并填塞内圈61与外圈62之间的间隙。由这些多个油封14、15、16密闭的空间构成润滑剂保持空间17(参照图9)。润滑剂保持空间17包含轴承构件6的内圈61与外圈62之间的空间。进一步，在润滑剂保持空间17内收容有多个销23、行星齿轮3、偏心体轴承5、支承体8、第一轴承91及第二轴承92等。
并且，在润滑剂保持空间17封入有润滑剂。润滑剂为液体，能够在润滑剂保持空间17内流动。因此，在齿轮装置1的使用时，例如润滑剂进入由多个销23构成的内齿21与行星齿轮3的外齿31的啮合部位。本公开实施例所说的“液 体”包括液状或凝胶状的物质。在此所说的“凝胶状”是指具有液体与固体的中间性质的状态，包括由液相和固相这两个相构成的胶质(colloid)的状态。例如，分散剂为液相且分散质为液相的乳剂(emulsion)，分散质为固相的悬浮液(suspension)等称为凝胶(gel)或溶胶(sol)的状态包含于“凝胶状”。而且，分散剂为固相且分散质为液相的状态也包含于“凝胶状”。在本实施方式中，作为一例，润滑剂为液状的润滑油(油液)。
在上述的结构的齿轮装置1中，向偏心轴7施加作为输入的旋转力，从而偏心轴7以旋转轴Ax1为中心进行旋转，由此行星齿轮3绕着旋转轴Ax1摆动(公转)。此时，行星齿轮3以在内齿齿轮2的内侧内切于内齿齿轮2且外齿31的一部分啮合于内齿21的一部分的状态摆动，因此内齿21与外齿31的啮合位置沿内齿齿轮2的圆周方向移动。由此，在两齿轮(内齿齿轮2及行星齿轮3)之间产生与行星齿轮3与内齿齿轮2的齿数差对应的相对旋转。并且，通过多个内销4，将除了行星齿轮3的摆动分量(公转分量)之外的、行星齿轮3的旋转(自转分量)向轴承构件6的内圈61传递。其结果是，从一体化于内圈61的输出轴，可得到与两齿轮的齿数差相应地以比较高的减速比被减速了的旋转输出。
然而，如上所述，在本实施方式的齿轮装置1中，内齿齿轮2与行星齿轮3的齿数差规定了齿轮装置1中的输出旋转相对于输入旋转的减速比。也就是说，在将内齿齿轮2的齿数设为“V1”并将行星齿轮3的齿数设为“V2”的情况下，减速比R1由下述式1表示。
R1＝V2/(V1-V2)……(式1)
总之，内齿齿轮2与行星齿轮3的齿数差(V1-V2)越小，则减速比R1越大。作为一例，内齿齿轮2的齿数V1为“52”，行星齿轮3的齿数V2为“51”，其齿数差(V1-V2)为“1”，因此根据上述式1，减速比R1为“51”。在这样的情况下，从旋转轴Ax1的输入侧观察时，当偏心轴7以旋转轴Ax1为中心顺时针旋转一周(360度)，则内圈61以旋转轴Ax1为中心逆时针旋转齿数差”1”的量(也就是说约7.06度)。
根据本实施方式的齿轮装置1，这样高的减速比R1能够通过一级齿轮(内齿齿轮2及行星齿轮3)的组合来实现。
另外，齿轮装置1只要至少包括内齿齿轮2、行星齿轮3、多个内销4、轴承构件6和支承体8即可，例如，还可以包括花键衬套等作为结构要素。
然而，在如本实施方式的齿轮装置1那样成为高速旋转侧的输入旋转伴有偏心运动的情况下，如果未取得进行高速旋转的旋转体的平衡，则可能会导致振动等，因此有时使用平衡配重等来取得重量平衡。即，由偏心体内圈51及偏心体内圈51一起旋转的构件(偏心轴7)中的至少一者构成的旋转体以高速进行偏心运动，因此优选取得该旋转体的相对于旋转轴Ax1的重量平衡。在本实施方式中，如图3及图4所示，通过在偏心轴7的偏心部72的一部分设置空隙75来取得旋转体相对于旋转轴Ax1的重量平衡。
总之，在本实施方式中，不附加平衡配重等而通过减薄旋转体(此处为偏心轴7)的一部分进行轻量化，由此取得旋转体相对于旋转轴Ax1的重量平衡。即，本实施方式的齿轮装置1包括收容于形成在行星齿轮3的开口部33并使行星齿轮3摆动的偏心体轴承5。偏心体轴承5具有偏心体外圈52及配置于偏心体外圈52的内侧的偏心体内圈51。从偏心体内圈51的旋转轴Ax1观察，由偏心体内圈51及偏心体内圈51一起旋转的构件的至少一者构成的旋转体在偏心体外圈52的中心C1侧的一部具有空隙75。在本实施方式中，偏心轴7是“与偏心体内圈51一起旋转的构件”，相当于“旋转体”。因此，在偏心轴7的偏心部72形成的空隙75相当于旋转体的空隙75。如图3及图4所示，该空隙75在从旋转轴Ax1观察下处于中心C1侧的位置，因此发挥作用以使偏心轴7的重量平衡从旋转轴Ax1至周向接近均等。
更详细而言，空隙75包含形成在沿着偏心体内圈51的旋转轴Ax1贯通旋转体的贯通孔73的内周面上的凹部。也就是说，在本实施方式中，旋转体为偏心轴7，因此在沿着旋转轴Ax1贯通偏心轴7的贯通孔73的内周面上形成的凹部作为空隙75发挥功能。如此，通过将形成于贯通孔73的内周面的凹部作为空隙75来利用，能够在不伴有外观上的变更的情况下取得旋转体的重量平衡。
在本实施方式中，内齿齿轮2为“第一齿轮”的一例，行星齿轮3为“第二齿轮”的一例。即，第一齿轮是具有环状的齿轮主体22和多个销23的内齿齿轮2。多个销23以能够自转的状态保持于在齿轮主体22的内周面221形成的多个内周槽223，并构成内齿21。第二齿轮是具有与内齿21局部性地啮合的外齿31的行星齿轮3。在该齿轮装置1中，通过使行星齿轮3以旋转轴Ax1为中心摆动，从而使行星齿轮3相对于内齿齿轮2相对旋转。
(3.2)内销的自转结构
接下来，关于本实施方式的齿轮装置1的内销4的自转结构，参照图9更详细地进行说明。图9是图3的区域Z1的放大图。
首先作为前提，如上所述，多个内销4是将行星齿轮3与轴承构件6的内圈61连结的部件。具体而言，内销4的长度方向的一端部(在本实施方式中为旋转轴Ax1的输入侧的端部)***于行星齿轮3的内销孔32，内销4的长度方向的另一端部(在本实施方式中为旋转轴Ax1的输出侧的端部)***于内圈61的保持孔611。
此处，内销4的直径比内销孔32的直径小一圈，因此能够在内销4与内销孔32的内周面321之间确保间隙，内销4能够在内销孔32内移动，也就是说内销4能够相对于内销孔32的中心相对地移动。另一方面，保持孔611的直径虽然为内销4的直径以上，但是比内销孔32的直径小。在本实施方式中，保持孔611的直径与内销4的直径大致相同，比内销4的直径稍大。因此，内销4在保持孔611内的移动被限制，也就是说内销4相对于保持孔611的中心的相对移动被禁止。因此，对于内销4而言，在行星齿轮3中以在内销孔32内能够公转的状态被保持，且相对于内圈61以在保持孔611内不能公转的状态被保持。由此，行星齿轮3的摆动分量、也就是说行星齿轮3的公转分量被内销孔32与内销4的游嵌吸收，并通过多个内销4将除了行星齿轮3的摆动分量(公转分量)之外的、行星齿轮3的旋转(自转分量)向内圈61传递。
然而，在本实施方式中，内销4的直径比保持孔611稍大，由此内销4在***于保持孔611的状态下，虽然在保持孔611内的公转被禁止，但是能够进 行在保持孔611内的自转。也就是说，内销4即使是***于保持孔611的状态，也因为不是被压入于保持孔611而能够在保持孔611内自转。这样，在本实施方式的齿轮装置1中，多个内销4各自以能够自转的状态由内圈61保持，因此在内销4在内销孔32内公转之际，内销4自身能够自转。
总之，在本实施方式中，内销4相对于行星齿轮3以能够进行在内销孔32内的公转及自转这两者的状态被保持，且相对于内圈61以仅能够进行在保持孔611内的自转的状态被保持。也就是说，多个内销4以各自的自转未被约束的状态(能够自转的状态)，能够以旋转轴Ax1为中心旋转(公转)，并且能够在多个内销孔32内公转。因此，在利用多个内销4将行星齿轮3的旋转(自转分量)向内圈61传递之际，内销4能够在内销孔32内进行公转及自转，且能够在保持孔611内进行自转。因此，内销4在内销孔32内公转之际，内销4处于能够自转的状态，因此相对于内销孔32的内周面321进行滚动。换言之，内销4以在内销孔32的内周面321上滚转的方式在内销孔32内公转，因此难以产生因内销孔32的内周面321与内销4之间的摩擦阻力而引起的损失。
这样，在本实施方式的结构中，由于原本就难以产生因内销孔32的内周面321与内销4之间的摩擦阻力而引起的损失，因此能够省略内滚子。因此，在本实施方式中，多个内销4各自采用直接与内销孔32的内周面321接触的结构。也就是说，在本实施方式中，成为将未装配内滚子的状态的内销4***于内销孔32从而使得内销4直接与内销孔32的内周面321接触的结构。由此，能够省略内滚子，能够将内销孔32的直径抑制得比较小，因此能够进行行星齿轮3的小型化(特别是小径化)，且作为齿轮装置1整体也容易实现小型化。如果将行星齿轮3的尺寸设为固定，则与上述第一关联技术相比，例如，还可以增加内销4的个数(根数)来使旋转的传递顺畅，或者使内销4***而提高强度。进一步，能够根据内滚子相应的量将部件个数抑制得少，从而也有助于齿轮装置1的低成本化。
另外，在本实施方式的齿轮装置1中，多个内销4各自的至少一部分在轴承构件6的轴向上配置于与轴承构件6相同的位置。也就是说，如图9所示， 在与旋转轴Ax1平行的方向上，内销4将其至少一部分配置于与轴承构件6相同的位置。换言之，内销4的至少一部分位于与旋转轴Ax1平行的方向上的轴承构件6的两端面之间。再换言之，多个内销4各自将至少一部分配置于轴承构件6的外圈62的内侧。在本实施方式中，内销4中的旋转轴Ax1的输出侧的端部在与旋转轴Ax1平行的方向上处于与轴承构件6相同的位置。总之，内销4中的旋转轴Ax1的输出侧的端部***于在轴承构件6的内圈61形成的保持孔611，因此至少该端部在轴承构件6的轴向上配置于与轴承构件6相同的位置。
这样，多个内销4各自的至少一部分在轴承构件6的轴向上配置与轴承构件6相同的位置，由此能够将与旋转轴Ax1平行的方向上的齿轮装置1的尺寸抑制得小。也就是说，与轴承构件6和内销4沿轴承构件6的轴向并列(相对)的结构相比，在本实施方式的齿轮装置1中，能够减小与旋转轴Ax1平行的方向上的齿轮装置1的尺寸，并能够对齿轮装置1的进一步的小型化(薄型化)作出贡献。
此处，保持孔611中的旋转轴Ax1的输出侧的开口面例如由与内圈61一体化的输出轴等闭塞。由此，关于内销4向旋转轴Ax1的输出侧(图9的右侧)的移动，被与内圈61一体化的输出轴等限制。
另外，在本实施方式中，为了使得内销4相对于内圈61的自转顺畅地进行而采用以下的结构。即，通过使润滑剂(润滑油)介于在内圈61形成的保持孔611的内周面与内销4之间而使内销4的自转顺畅。特别是在本实施方式中，在内圈61与外圈62之间存在供润滑剂注入的润滑剂保持空间17，因此利用润滑剂保持空间17内的润滑剂实现内销4的自转的顺畅化。
如图9所示，在本实施方式中，内圈61具有：供多个内销4分别***的多个保持孔611；和多个连结路64。多个连结路64使内圈61和外圈62之间的润滑剂保持空间17与多个保持孔611之间相连。具体而言，在内圈61形成有从保持孔611的内周面的一部分即与滚动体63对应的部位沿径向延伸的连结路64。连结路64是将内圈61的与外圈62相对的相对面中的收容滚动体63的凹 部(槽)的底面与保持孔611的内周面之间贯通的孔。换言之，连结路64的润滑剂保持空间17侧的开口面配置于与轴承构件6的滚动体63面对(相对)的位置。润滑剂保持空间17与保持孔611经由这样的连结路64而在空间上相连。
根据上述结构，由于利用连结路64将润滑剂保持空间17与保持孔611连结，因此润滑剂保持空间17内的润滑剂穿过连结路64而被供给至保持孔611。也就是说，当轴承构件6动作而滚动滚动体63时，滚动体63作为泵发挥功能，能够将润滑剂保持空间17内的润滑剂经由连结路64送入至保持孔611。特别是连结路64的润滑剂保持空间17侧的开口面处于与轴承构件6的滚动体63面对(相对)的位置，由此在滚动体63旋转时滚动体63作为泵有效地发挥作用。其结果是，润滑剂介于保持孔611的内周面与内销4之间，能够实现内销4相对于内圈61的自转的顺畅化。
(3.3)支承体
接下来，关于本实施方式的齿轮装置1的支承体8的结构，参照图10更详细地进行说明。图10是图3的B1-B1线剖视图。但是，在图10中，关于支承体8以外的部件，即使是剖面也省略剖面线。另外，在图10中，仅图示内齿齿轮2及支承体8，省略了其他的部件(内销4等)的图示。进一步，在图10中，省略了齿轮主体22的内周面221的图示。
首先作为前提，如上所述，支承体8是支承多个内销4的部件。也就是说，支承体8通过捆束多个内销4，从而分散将行星齿轮3的旋转(自转分量)向内圈61传递之际的、作用于多个内销4的载荷。具体而言，具有供多个内销4分别***的多个支承孔82。在本实施方式中，作为一例，支承孔82的直径与形成于内圈61的保持孔611的直径相等。因此，支承体8以多个内销4各自能够自转的状态支承多个内销4。也就是说，多个内销4各自以相对于轴承构件6的内圈61与支承体8均能够自转的状态被保持。
这样，支承体8关于周向及径向这两个方向上，进行多个内销4的相对于支承体8的定位。也就是说，内销4通过***于支承体8的支承孔82，从而与旋转轴Ax1正交的平面内的相对于全部方向的移动被限制。因此，内销4利用 支承体8不仅在周向而且在径向(径向)也被定位。
此处，支承体8具有至少外周面81在俯视观察下为正圆的圆环状。并且，支承体8通过使外周面81与内齿齿轮2中的多个销23接触而被进行位置限制。多个销23由于构成内齿齿轮2的内齿21，所以换言之，支承体8通过使外周面81与内齿21接触而被进行位置限制。此处，支承体8的外周面81的直径与穿过内齿齿轮2的内齿21的前端的虚拟圆(齿顶圆)的直径相同。因此，多个销23全部与支承体8的外周面81接触。由此，在支承体8由多个销23进行了位置限制的状态下，支承体8的中心以与内齿齿轮2的中心(旋转轴Ax1)重叠的方式被进行位置限制。由此，进行支承体8的定芯，结果是，关于由支承体8支承的多个内销4，也利用多个销23进行定芯。
另外，多个内销4以旋转轴Ax1为中心旋转(公转)，由此将行星齿轮3的旋转(自转分量)向内圈61传递。因此，对多个内销4进行支承的支承体8与多个内销4及内圈61一起以旋转轴Ax1为中心旋转。此时，支承体8利用多个销23进行定芯，因此以支承体8的中心被维持在旋转轴Ax1上的状态，支承体8顺畅地旋转。而且，支承体8以其外周面81与多个销23接触的状态旋转，因此伴随着支承体8的旋转，多个销23各自旋转(自转)。由此，支承体8与内齿齿轮2一起构成滚针轴承(针状滚子轴承)，并顺畅地旋转。
即，支承体8的外周面81以与多个销23相接的状态与多个内销4一起相对于齿轮主体22相对旋转。因此，如果将内齿齿轮2的齿轮主体22看作“外圈”，将支承体8看做“内圈”，则介于两者之间的多个销23作为“滚动体(滚子)”发挥功能。这样，支承体8与内齿齿轮2(齿轮主体22及多个销23)一起构成滚针轴承，并能够进行顺畅的旋转。
进一步，由于支承体8在齿轮主体22之间夹着多个销23，因此支承体8也作为抑制销23从齿轮主体22的内周面221分离的方向的移动的“限动件”发挥功能。也就是说，多个销23通过夹在支承体8的外周面81与齿轮主体22的内周面221之间，从而抑制多个销23从齿轮主体22的内周面221的浮起。总之，在本实施方式中，多个销23各自通过与支承体8的外周面81接触而被 限制从齿轮主体22分离的方向的移动。
然而，如图9所示，在本实施方式中，支承体8隔着行星齿轮3而位于轴承构件6的与内圈61相反的一侧。也就是说，支承体8、行星齿轮3及内圈61沿与旋转轴Ax1平行的方向并列配置。在本实施方式中，作为一例，支承体8在从行星齿轮3观察下位于旋转轴Ax1的输入侧，内圈61在从行星齿轮3观察下位于旋转轴Ax1的输出侧。并且，支承体8与内圈61一起支承内销4的长度方向(与旋转轴Ax1平行的方向)的两端部，内销4的长度方向的中央部贯通***行星齿轮3的内销孔32。总之，本实施方式的齿轮装置1包括轴承构件6，该轴承构件6具有外圈62及配置于外圈62的内侧的内圈61，且内圈61被支承为能够相对于外圈62相对旋转。并且，齿轮主体22固定于外圈62。此处，行星齿轮3在支承体8的轴向上位于支承体8与内圈61之间。
根据该结构，支承体8及内圈61支承内销4的长度方向的两端部，因此难以产生内销4的倾斜。特别是也容易承受作用于多个内销4的对于旋转轴Ax1的弯曲力(弯曲力矩载荷)。另外，在本实施方式中，在与旋转轴Ax1平行的方向上，支承体8被夹在行星齿轮3与壳体10之间。由此，支承体8向旋转轴Ax1的输入侧(图9的左侧)的移动被壳体10限制。关于贯通支承体8的支承孔82而从支承体8向旋转轴Ax1的输入侧突出的内销4，向旋转轴Ax1的输入侧(图9的左侧)的移动也被壳体10限制。
在本实施方式中，支承体8及内圈61还与多个销23的两端部接触。也就是说，如图9所示，支承体8与销23的长度方向(与旋转轴Ax1平行的方向)的一端部(旋转轴Ax1的输入侧的端部)接触。内圈61与销23的长度方向(与旋转轴Ax1平行的方向)的另一端部(旋转轴Ax1的输出侧的端部)接触。根据该结构，支承体8及内圈61在销23的长度方向的两端部被定芯，因此难以产生内销4的倾斜。特别是也容易承受作用于多个内销4的对于旋转轴Ax1的弯曲力(弯曲力矩载荷)。
另外，多个销23具有支承体8的厚度以上的长度。换言之，在与旋转轴Ax1平行的方向上，支承体8收于内齿21的齿向的范围内。由此，支承体8的 外周面81遍及内齿21的齿向方向(与旋转轴Ax1平行的方向)的全长地与多个销23接触。因此，难以产生支承体8的外周面81局部性地磨损的“单边磨损”那样的不良状况。
另外，在本实施方式中，支承体8的外周面81比支承体8的与外周面81相邻的一表面表面粗糙度小。也就是说，外周面81的表面粗糙度比支承体8的轴向(厚度方向)的两端面小。本公开实施例所说的“表面粗糙度”是指物体的表面的粗糙程度，值越小则表面的凹凸越小(越少)越光滑。在本实施方式中，作为一例，将表面粗糙度设为算数平衡粗糙度(Ra)。例如，通过研磨等处理，外周面81比支承体8的外周面81以外的面的表面粗糙度小。在该结构中，支承体8的旋转变得更加顺畅。
另外，在本实施方式中，支承体8的外周面81的硬度比多个销23的周面低且比齿轮主体22的内周面221高。本公开实施例所说的“硬度”是指物体的坚硬程度，金属的硬度例如由以一定的压力推压钢球而形成的压痕的大小来表示。具体而言，作为金属的硬度的一例，有洛氏硬度(HRC)、布氏硬度(HB)、维氏硬度(HV)或肖氏硬度(Hs)等。作为提高金属部件的硬度(***)的手段，例如有合金化或热处理等。在本实施方式中，作为一例，通过渗碳淬火等处理来提高支承体8的外周面81的硬度。在该结构中，即使由于支承体8的旋转也难以产生磨损粉等，容易长期地维持支承体8的顺畅的旋转。
(4)适用例
接下来，说明本实施方式的齿轮装置1及执行器100的适用例。
本实施方式的齿轮装置1及执行器100例如适用于水平多关节机器人、即所谓的选择柔性组合机器人臂(SCARA：Selective Compliance Assembly Robot Arm)型机器人那样的机器人。
另外，本实施方式的齿轮装置1及执行器100的适用例并不限于上述那样的水平多关节机器人，例如，也可以是除了水平多关节机器人以外的产业用机器人或产业以外的机器人等。作为一例，水平多关节机器人以外的产业用机器人有垂直多关节型机器人或平行连杆型机器人等。在产业用以外的机器人中， 作为一例，有家庭用机器人、护理用机器人或医疗用机器人等。
(5)内齿齿轮的详情
接下来，关于本实施方式的齿轮装置1中的内齿齿轮2的详情，参照图11～图13进行说明。图11放大了图9中的内齿21(销23)与外齿31的啮合部位的概略剖视图，关于除内齿齿轮2(齿轮主体22和销23)和行星齿轮3以外的部件省略图示。图12是图11的A1-A1线剖面的概略图，与图11同样关于除内齿齿轮2和行星齿轮3以外的部件省略图示。另外，在图11和图12中，将要部的概略放大图示出于对白框内。
如本实施方式那样，在包括第一齿轮(内齿齿轮2)和通过与第一齿轮啮合而相对于第一齿轮相对旋转的第二齿轮(行星齿轮3)的齿轮装置1中，例如，在第一齿轮(内齿齿轮2)的齿轮主体22与形成内齿21的销23之间产生“滑动接触”。本公开所说的“滑动接触”是指与滚动接触(或者固定接触)等中的微小滑动(Microslip)相比，产生宏观的滑动(Grossslip)的二者间的接触状态。也就是说，“滑动接触”(sliding contact)是接触而相对运动的2个固体表面的运动形态之一，与滚动接触(rolling contact)不同，是在两者间产生宏观的滑动的相对运动的形态。
如此，如图11和图12所示，在第一齿轮(内齿齿轮2)中，在与另一部件(此处为销23)之间产生滑动接触的多个内周槽223的内表面那样的“滑动接触部位”形成被覆层224。此处，被覆层224是覆盖成为基材的骨架部225的至少一部分的层。也就是说，在本实施方式中，在内齿齿轮2的齿轮主体22的作为基材的骨架部225中，至少成为滑动接触部位的多个内周槽223的内表面被被覆层224覆盖。
被覆层224为比重比骨架部225大的材质。在本实施方式中，被覆层224和骨架部225均为金属制，被覆层224由比重比骨架部225大的金属构成。作为一例，成为齿轮主体22的基材的骨架部225为铝(Al)制，被覆层224为铁(Fe)制。
总之，本实施方式的齿轮装置1包括第一齿轮(内齿齿轮2)和第二齿轮 (行星齿轮3)。第二齿轮通过与第一齿轮啮合而相对于第一齿轮相对旋转。第一齿轮具有骨架部225和比重比骨架部225大的被覆层224。骨架部225中的至少与另一部件滑动接触的滑动接触部位被被覆层224覆盖。
根据以上说明的结构，第一齿轮(内齿齿轮2)的骨架部225自身由于为比重小的材质，例如即使具有相应的厚度，也能够将重量抑制得比较小。另一方面，关于骨架部225中的(与另一部件的)滑动接触部位，由于被比重比骨架部225大的被覆层224覆盖，因此滑动接触部位能够提高耐磨损性并维持作为第一齿轮(内齿齿轮2)的强度。其结果是，根据本实施方式的齿轮装置1，能够实现在维持强度的同时容易实现轻量化的齿轮装置1。
并且，在本实施方式中，第一齿轮为内齿齿轮2，第二齿轮为行星齿轮3，因此内齿齿轮2的骨架部225中的、至少与作为另一部件的多个销23滑动接触的多个内周槽223的内表面成为滑动接触部位。因此，至少多个内周槽223的内表面(滑动接触部位)被被覆层224覆盖。
就是说，如图11和图12所示，由于利用被覆层224覆盖齿轮主体22中的、保持多个销23的多个内周槽223的内表面，因此即使各销23旋转(自转)而相对于内周槽223的内面滑动接触，也能够抑制内周槽223的内表面的磨损。总之，关于与销23滑动接触的内周槽223的内表面，通过利用被覆层224覆盖骨架部225，从而成为保护骨架部225的形态，能够提高耐磨损性并维持强度。由此，在行星齿轮3相对于内齿齿轮2相对旋转的情况下，抑制齿轮主体22因销23的滑动接触而磨损。
在本实施方式中，被覆层224以覆盖内周槽223的内表面的整个区域的方式遍及齿轮主体22的内周面221的周向的整周形成。因此，在与销23滑动接触的内周槽223的内表面不露出骨架部225。但是，如图11所示，在齿轮主体22的内周面221中的、内齿21的齿向方向(与旋转轴Ax1平行的方向)上的两端部没有形成被覆层224而露出骨架部225。具体而言，在齿轮主体22的内周面221处，构成内周槽223的部位朝向内侧(旋转轴Ax1侧)突出，以只覆盖该突出了的部分的方式形成有被覆层224。
在本实施方式中，特别是在内周槽223中成为内齿21的齿向方向的两端的角部、也就是说在图11所示的截面中，关于成为凸角形状的部分，以完全覆盖骨架部225的方式形成有被覆层224。换言之，从内周槽223的内表面到与其邻接的台阶部形成有被覆层224。这样，通过利用被覆层224覆盖角部，即使该角部与销23接触，也能够避免销23与骨架部225直接接触，容易抑制骨架部225的磨损。
然而，在本实施方式中，被覆层224通过喷镀形成。本公开所说的“喷镀”是指通过将利用各种热源使金属等的喷镀材料熔融软化的颗粒喷出到加工对象物的表面，从而在加工对象物的表面形成被膜的加工技术。通过喷镀喷出的溶融颗粒附着于作为加工对象物的金属等的基材时，瞬间冷却固化而形成被膜。通过喷镀而形成于骨架部225的被膜构成被覆层224。
即，本实施方式的齿轮装置1的制造方法具有通过喷镀在第一齿轮(内齿齿轮2)的骨架部225的至少一部分形成被覆层224的喷镀工序。通过喷镀形成的被覆层224例如与通过镀覆或蒸镀等的方法形成的被膜相比，可以具有大的膜厚。
但是，在通过喷镀形成的被膜的表面会产生多孔质膜(多孔膜)，因此优选对该表面进行精加工。因此，本实施方式的齿轮装置1的制造方法在喷镀工序后，具有研磨加工等的表面精加工工序。根据表面精加工工序，虽然通过喷镀形成的被膜的膜厚减少，但是通过喷镀形成足够的膜厚的被膜，从而即使在表面精加工工序后也能够实现足够的膜厚的被膜(被覆层224)。
另外，骨架部225的导热率比被覆层224高。如上所述，在本实施方式中，被覆层224为铁(Fe)，因此被覆层224的导热率为80.3(W/m·K)。对此，骨架部225为铝(Al)制，因此骨架部225的导热率为237(W/m·K)。也就是说，骨架部225具有接近被覆层224三倍的导热率。由此，能够由导热率高的骨架部225构成第一齿轮(内齿齿轮2)的齿轮主体22的大部分，从而能够提高第一齿轮(内齿齿轮2)的散热性。
例如，伴随着齿轮装置1的动作，在第一齿轮(内齿齿轮2)与第二齿轮 (行星齿轮3)的啮合部分、或者齿轮主体22中的销23的滑动接触部位处产生通过摩擦等而引起的发热的情况下，能够有效地对所产生的热进行散热。特别是，齿轮主体22与壳体10一起成为齿轮装置1的外轮廓的一部分，能够将在齿轮装置1的内部产生的热有效地散发到齿轮装置1的外部。
另外，在本实施方式中，被覆层224是与骨架部225不同组成的喷镀膜。即，如上所述，被覆层224是通过喷镀形成的喷镀膜。此处，虽然可以在骨架部225的表面上形成与骨架部225相同组成的喷镀膜，但是在本实施方式中形成有与骨架部225不同组成的喷镀膜。具体而言，骨架部225为铝(Al)，相对于此，被覆层224为铁(Fe)。
但是，考虑到被覆层224相对于骨架部225的密合性，优选骨架部225与被覆层224的线膨胀系数接近。具体而言，若为93℃(200°F)以下的温度环境，则优选两者的线膨胀系数接近到不会因线膨胀系数不同而使骨架部225从被覆层224剥离的程度。
另外，在本实施方式中，被覆层224具有50μm以上的厚度。也就是说，作为通过喷镀形成的被覆层224的特性，与通过镀覆或蒸镀等的方法形成的被膜相比，可以具有大的膜厚，作为被覆层224的具体的膜厚优选为50μm以上。作为一例，在喷镀工序中，在骨架部225的表面上形成150μm的被膜，在表面精加工工序中研磨掉100μm，由此形成50μm的被覆层224。通过被覆层224具有这样的足够的膜厚，能够避免销23与骨架部225直接接触，容易抑制骨架部225的磨损。
在此处，第一齿轮(内齿齿轮2)在骨架部225的表面具有基底层226，被覆层224层叠于基底层226。即，如图11和图12的对白框内所示，在骨架部225的表面依次层叠有基底层226、被覆层224。由此，被覆层224不直接层叠于骨架部225的表面上，而是隔着基底层226层叠，因此能够提高被覆层224相对于骨架部225的密合性。
基底层226例如通过增大骨架部225的表面粗糙度(算数平均粗糙度(Ra))的加工而形成于骨架部225的表面上。具体而言，在本实施方式中，作为一例， 通过对骨架部225的表面实施激光喷丸形成基底层226。本公开所述的“激光喷丸”是对加工对象物照射激光脉冲，对加工对象物的表面赋予压缩残留应力并且提高表面硬度的表面改性技术。即，本实施方式的齿轮装置1的制造方法在喷镀工序之前具有用于形成激光喷丸等的基底层226的基底形成工序。
此处，基底层226的格方向优选以滑动接触部位处的另一部件的滑动方向为基准的方向。即，如图13A和图13B所示，在骨架部225中的成为另一部件(销23)的滑动接触部位的内周槽223的内表面，确定另一部件的滑动方向。也就是说，销23以其中心轴为中心，在内周槽223内旋转(自转)，因此在内周槽223的内表面产生沿着销23的周向的滑动方向。因此，通过以该滑动方向为基准，决定基底层226的格方向，从而提高被覆层224的密合性，容易抑制被覆层224的剥离等。
作为一例，如图13A所示，优选使由激光喷丸等形成的基底层226的格方向为在滑动接触部位处与另一部件(销23)的滑动方向交叉的方向。例如，通过将沿着内周槽223的长边方向的方向作为基底层226的格方向，基底层226的格方向与另一部件的滑动方向正交。根据这样的结构，即使另一部件(销23)与在基底层226上形成的被覆层224滑动接触，被覆层224也会卡挂于基底层226的加工痕，而难以从骨架部225剥离。
作为另一例，如图13B所示，也考虑将由激光喷丸等形成的基底层226在滑动接触部位处配置为以另一部件(销23)的滑动方向为基准的格子状。例如，在内周槽223的长边方向和周向上，形成大致均等分散那样的离散的加工痕。各个加工痕例如可以采用圆环状、多边形状或点状等适当的形状。根据这样的结构，即使另一部件(销23)与在基底层226上形成的被覆层224滑动接触，被覆层224也会卡挂于基底层226的加工痕，而难以从骨架部225剥离。
(6)变形例
实施方式一只不过是本公开的各种实施方式的一个。实施方式一只要能够实现本公开的目的，就可以根据设计等进行各种变更。另外，本公开中所参照的附图均为示意图，图中的各结构要素的大小和厚度各自的比不一定限于反映 实际的尺寸比。以下，列举实施方式一的变形例。以下说明的变形例可以适当组合适用。
内齿齿轮2的齿轮主体22也可以与壳体10无缝地一体化。在该情况下，壳体10由与齿轮主体22相同的材料(例如铝)构成，壳体10和齿轮主体22作为一个部件进行处理。在该结构中，相较于齿轮主体22和壳体10为分体的结构，铝制的部件的体积和表面积变大，可期待作为齿轮装置1整体的轻量化和散热性的提高。同样，也可以是轴承构件6的外圈62与内齿齿轮2的齿轮主体22无缝地一体化。
也不是必须第一齿轮为内齿齿轮2，第二齿轮为行星齿轮3。例如，也可以是第一齿轮为行星齿轮3，第二齿轮为内齿齿轮2。在该情况下，行星齿轮3的基材构成骨架部，例如，利用被覆层覆盖行星齿轮3中的与另一部件(内销4)滑动接触的滑动接触部位。
另外，骨架部225不限于铁(Fe)，被覆层224不限于铝(Al)。被覆层224只要是比重比骨架部225大的材质即可，被覆层224和骨架部225的至少一者可以为非金属。即使在该情况下，也优选骨架部225的导热率比被覆层224高。
被覆层224不限于通过喷镀形成，也可以通过除喷镀以外的方法形成。
基底层226不限于激光喷丸，例如，也可以通过对加工对象物投射投射材料的喷丸硬化等的加工形成。另外，基底层226的格方向不限于图13A和图13B所示的例子，例如，还可以是沿着另一部件(销23)的滑动方向的方向或者相对于另一部件(销23)的滑动方向倾斜的方向等。
在实施方式一中，例示了行星齿轮3为1个的类型的齿轮装置1，但是齿轮装置1可以包括2个以上的行星齿轮3。例如，在齿轮装置1包括3个行星齿轮3的情况下，优选这3个行星齿轮3绕着旋转轴Ax1以120度的相位差配置。或者，在齿轮装置1包括三个行星齿轮3的情况下，也可以这些3个行星齿轮3钟的2个行星齿轮3为相同位相，剩余的一个行星齿轮3绕着旋转轴Ax1以180度的位相差配置。
另外，实施方式一所说明的销23的数量(内齿21的齿数)、及外齿31的 齿数等只不过是一例，可以适当变更。
另外，齿轮装置1的各结构要素的材质并不限于金属，例如，可以为工程塑料等树脂。
另外，作为齿轮装置1，只要能够将轴承构件6的内圈61与外圈62之间的相对旋转作为输出取出即可，不限于将内圈61的旋转力作为输出取出的结构。例如，也可以将相对于内圈61相对地旋转的外圈62(壳体10)的旋转力作为输出取出。
另外，润滑剂并不限于润滑油(油液)等液状的物质，可以是润滑脂等凝胶状的物质。
(实施方式二)
＜概要＞
如图14～图16所示，本实施方式的齿轮装置1A在为称作分配型的偏心摆动型的内啮合行星齿轮装置的方面与实施方式一的齿轮装置1不同。以下，关于与实施方式1同样的结构，标注相同的附图标记而适当省略说明。图14是示出齿轮装置1A的概略结构的立体图。图15是齿轮装置1A的从旋转轴Ax1的输入侧观察到的概略的分解立体图。图16是齿轮装置1A的概略剖视图。
如图14～图16所示，本实施方式的齿轮装置1A包括配置于从内齿齿轮2的轴心(旋转轴Ax1)偏移的位置的多个(在本实施方式中为3个)的偏心轴(曲轴)7A、7B、7C。进一步，齿轮装置1A包括配置于内齿齿轮2的轴心(旋转轴Ax1)上的、以旋转轴Ax1为中心的输入轴500和与输入轴500一体形成的输入齿轮501。曲轴齿轮502A、502B、502C分别通过花键连接于多个偏心轴7A、7B、7C。这些多个(在本实施方式为3个)曲轴齿轮502A、502B、502C以与输入齿轮501啮合的方式配置。因此，当驱动输入轴500时，齿轮装置1A通过利用输入齿轮501来同步驱动偏心轴7A、7B、7C，从而使行星齿轮3一边摆动一边与内齿齿轮2内啮合。
另外，本实施方式的齿轮装置1A包括多个行星齿轮3。具体而言，齿轮装置1A包括第一行星齿轮301和第二行星齿轮302这两个行星齿轮3。2个行星 齿轮3以在与旋转轴Ax1平行的方向上相对的方式配置。也就是说，行星齿轮3包含沿与旋转轴Ax1平行的方向并列的第一行星齿轮301及第二行星齿轮302。第一行星齿轮301和第二行星齿轮302的形状自身通用。
这些两个行星齿轮3(第一行星齿轮301及第二行星齿轮302)绕着旋转轴Ax1以180度的位相差配置。在图16的例子中，第一行星齿轮301和第二行星齿轮302中的、位于旋转轴Ax1的输入侧(图16的右侧)的第一行星齿轮301的中心C1处于相对于旋转轴Ax1向图的上方偏离(偏移)的状态。另一方面，位于旋转轴Ax1的输出侧(图16的左侧)的第二行星齿轮302的中心C2处于相对于旋转轴Ax1向图的下方偏离(偏移)的状态。此处，旋转轴Ax1与中心C1之间的距离ΔL1为第一行星齿轮301相对于旋转轴Ax1的偏心量，旋转轴Ax1与中心C2之间的距离ΔL2为第二行星齿轮302相对于旋转轴Ax1的偏心量。这样，多个行星齿轮3在以旋转轴Ax1为中心的周向上均等地配置，由此能够取得多个行星齿轮3之间的重量平衡。
在第一行星齿轮301与第二行星齿轮302中，它们的中心C1、C2相对于旋转轴Ax1位于180度旋转对称。在本实施方式中，对于偏心量ΔL1和偏心量ΔL2而言，从旋转轴Ax1观察到的朝向虽然相反，但是它们的绝对值相同。
更详细地说，各偏心轴7A、7B、7C分别相对于1个轴心部71具有2个偏心部72。这些2个偏心部72的中心的距轴心部71的中心的偏心量分别与第一行星齿轮301和第二行星齿轮302相对于旋转轴Ax1的偏心量ΔL1、ΔL2相同。多个偏心轴7A、7B、7C的形状自身通用。关于多个曲轴齿轮502A、502B、502C，它们的形状自身通用。
另外，在第一行星齿轮301和第二行星齿轮302的与旋转轴Ax1平行的方向的两侧配置有支架凸缘18和输出凸缘19。各偏心轴7A、7B、7C的两端部隔着滚动轴承41、42被保持于支架凸缘18和输出凸缘19。也就是说，各偏心轴7A、7B、7C相对于行星齿轮3在与旋转轴Ax1平行的方向的两侧处以能够自转的状态被保持于支架凸缘18和输出凸缘19。
在各偏心轴7A、7B、7C的偏心部72装配有偏心体轴承5。在第一行星齿 轮301和第二行星齿轮302分别形成有与3个偏心轴7A、7B、7C对应的3个开口部33。并且，在各开口部33收容有偏心体轴承5。换言之，在第一行星齿轮301和第二行星齿轮302分别安装有偏心体轴承5，并将各偏心轴7A、7B、7C***偏心体轴承5，由此偏心体轴承5和各偏心轴7A、7B、7C与行星齿轮3组合。在本实施方式的齿轮装置1A中，省略内销4，通过多个偏心轴7A、7B、7C来代替内销4，能够取出除了行星齿轮3的摆动分量(公转分量)的、行星齿轮3的旋转(自转分量)。
根据以上说明的结构，通过对输入轴500施加作为输入的旋转力来使输入轴500以旋转轴Ax1为中心进行旋转，从而该旋转力从输入齿轮501被分配至多个偏心轴7A、7B、7C。也就是说，当输入齿轮501旋转时，与该输入齿轮501同时啮合的3个曲轴齿轮502A、502B、502C向相同的方向以相同的旋转速度进行旋转。在各曲轴齿轮502A、502B、502C花键连结有偏心轴7A、7B、7C，因此3个偏心轴7A、7B、7C在以与输入齿轮501和曲轴齿轮502A、502B、502C的齿数相比被减速了的状态下，向相同的方向以相同的旋转速度进行旋转。其结果，3个偏心轴7A、7B、7C中的形成于旋转轴Ax1的输入侧的相同位置的3个偏心部72同步旋转，使第一行星齿轮301摆动。进一步，3个偏心轴7A、7B、7C中的形成于旋转轴Ax1的输出侧的相同位置的3个偏心部72同步旋转，使第二行星齿轮302摆动。
其结果，多个偏心轴7A、7B、7C的轴心部71分别以旋转轴Ax1为中心旋转(自转)，由此第一行星齿轮301和第二行星齿轮302绕着旋转轴Ax1以180度的位相差绕着旋转轴Ax1旋转(偏心运动)。
此处，第一行星齿轮301和第二行星齿轮302分别与内齿齿轮2内啮合。因此，第一行星齿轮301及第二行星齿轮302每摆动一次，第一行星齿轮301和第二行星齿轮302相对于内齿齿轮2产生(内齿21与外齿31的)齿数差量的圆周方向的位相偏离，并进行自转。该自转作为绕各偏心轴7A、7B、7C的内齿齿轮2的轴心(旋转轴Ax1)的公转传递至支架凸缘18和输出凸缘19。由此，能够使支架凸缘18和输出凸缘19以旋转轴Ax1为中心相对于齿轮主体 (与一体化了的壳体10)相对旋转。
总之，本实施方式的齿轮装置1A虽然在利用配置于从旋转轴Ax1偏移的位置的多个偏心轴7A、7B、7C使行星齿轮3摆动的方面与实施方式一不同，但是在利用行星齿轮3的摆动得到旋转输出的方面与实施方式一通用。也就是说，在齿轮装置1A中，当行星齿轮3摆动，内齿21与外齿31的啮合位置沿内齿齿轮2的圆周方向移动时，在两个齿轮(内齿齿轮2及行星齿轮3)之间产生与行星齿轮3和内齿齿轮2的齿数差对应的相对旋转。此处，如果将内齿齿轮2固定，则伴随着两齿轮的相对旋转，行星齿轮3旋转(自转)。其结果，从行星齿轮3能够得到与两齿轮的齿数差相应地以比较高的减速比被减速了的旋转输出。
更详细地说，本实施方式的齿轮装置1A的轴承构件6A包含第一轴承构件601A和第二轴承构件602A。第一轴承构件601A和第二轴承构件602A分别由角球轴承构成。具体而言，如图16所示，从行星齿轮3观察在旋转轴Ax1的输入侧(图16的右侧)配置有第一轴承构件601A，从行星齿轮3观察在旋转轴Ax1的输出侧(图16的左侧)配置有第二轴承构件602A。轴承构件6A利用第一轴承构件601A及第二轴承构件602A构成为径向的载荷、推力方向(沿着旋转轴Ax1的方向)的载荷、及对于旋转轴Ax1的弯曲力(弯曲力矩载荷)都能耐受。
此处，第一轴承构件601A及第二轴承构件602A相对于行星齿轮3在与旋转轴Ax1平行的方向的两侧，在与旋转轴Ax1平行的方向上配置为相互相反的朝向。也就是说，轴承构件6A是组合了多个(此处为2个)角球轴承的“组合角球轴承”。此处，作为一例，第一轴承构件601A及第二轴承构件602A是承受各自的内圈相互靠近的朝向的推力方向(沿着旋转轴Ax1的方向)的负载的“背面组合型”。进一步，在齿轮装置1A中，第一轴承构件601A及第二轴承构件602A通过将各自的内圈61向相互靠近的方向紧固，从而对内圈以作用适当的预压力的状态组合。
另外，本实施方式的齿轮装置1A包括支架凸缘18和输出凸缘19。支架凸 缘18及输出凸缘19相对于行星齿轮3配置于与旋转轴Ax1平行的方向两侧，并穿过行星齿轮3的支架孔34(参照图16)而相互结合。具体而言，如图16所示，从行星齿轮3观察在旋转轴Ax1的输入侧(图16的右侧)配置有支架凸缘18，从行星齿轮3观察在旋转轴Ax1的输出侧(图16的左侧)配置有输出凸缘19。轴承构件6A(第一轴承构件601A和第二轴承构件602A各自)的内圈固定于支架凸缘18和输出凸缘19。在本实施方式中，作为一例，第一轴承构件601A的内圈与支架凸缘18无缝地一体化。同样，第二轴承构件602A的内圈与输出凸缘19无缝地一体化。
输出凸缘19具有从输出凸缘19的一表面朝向旋转轴Ax1的输入侧突出的多个(作为一例为3个)的支架销191(参照图15)。这些多个支架销191分别贯通在行星齿轮3形成的多个(作为一例为3个)的支架孔34，多个支架销191的前端相对于支架凸缘18利用支架螺栓来固定。此处，在支架销191与支架孔34的内周面之间确保间隙，支架销191能够在支架孔34内移动，也就是说能够相对于支架孔34的中心相对地移动。由此，在行星齿轮3摆动时，支架销191不与支架孔34的内周面接触。
由此，齿轮装置1A以下述方式使用：将行星齿轮3的相当于自转分量的旋转作为与轴承构件6A的内圈61一体化的支架凸缘18及输出凸缘19的旋转而取出。即，在实施方式一中，行星齿轮3与内齿齿轮2之间的相对的旋转从利用内销4连结于行星齿轮3的内圈61作为行星齿轮3的自转分量取出。对此，在本实施方式中，行星齿轮3与内齿齿轮2之间的相对的旋转从与内圈一体化的支架凸缘18及输出凸缘19取出。在本实施方式中，作为一例，齿轮装置1A以轴承构件6A的外圈62(参照图16)固定于作为固定构件的壳体10的状态进行使用。即，行星齿轮3利用多个偏心轴7A、7B、7C与作为旋转构件的支架凸缘18及输出凸缘19连结，齿轮主体22固定于固定构件，因此行星齿轮3与内齿齿轮2之间的相对的旋转从旋转构件(支架凸缘18及输出凸缘19)取出。换言之，在本实施方式中，构成为行星齿轮3相对于齿轮主体22相对旋转时，将支架凸缘18和输出凸缘19的旋转力作为输出取出。
进一步，在本实施方式中，壳体10与内齿齿轮2的齿轮主体22无缝地一体化。也就是说，在实施方式一中，内齿齿轮2的齿轮主体22与轴承构件6的外圈62一起以固定于壳体10的状态使用。对此，在本实施方式中，在与旋转轴Ax1平行的方向上，作为固定构件的齿轮主体22与壳体10无缝地连续设置。
更详细而言，壳体10为圆筒状，且构成齿轮装置1A的外轮廓。在本实施方式中，圆筒状的壳体10的中心轴构成为与旋转轴Ax1一致。也就是说，壳体10的至少外周面在俯视观察下(从旋转轴Ax1方向的一方观察)是以旋转轴Ax1为中心的正圆。壳体10形成为在旋转轴Ax1方向的两端面开口的圆筒状。此处，壳体10与内齿齿轮2的齿轮主体22无缝地一体化，从而壳体10及齿轮主体22作为一个部件来处理。因此，壳体10的内周面包含齿轮主体22的内周面221。进一步，在壳体10固定有轴承构件6A的外圈62。也就是说，从壳体10的内周面中的齿轮主体22观察，第一轴承构件601A的外圈62通过嵌入而固定于旋转轴Ax1的输入侧(图16的右侧)。另一方面，从壳体10的内周面的齿轮主体22观察，第二轴承构件602A的外圈62通过嵌入而固定于旋转轴Ax1的输出侧(图16的左侧)。
进一步，壳体10的旋转轴Ax1的输入侧(图16的右侧)的端面由支架凸缘18来闭塞，壳体10的旋转轴Ax1的输出侧(图16的左侧)的端面由输出凸缘19来闭塞。因此，如图16所示，在被壳体10、支架凸缘18和输出凸缘19包围的空间内，收容有行星齿轮3(第一行星齿轮301和第二行星齿轮302)、多个销23、及偏心体轴承5等部件。
另外，本实施方式的齿轮装置1A还包括保持构件80，该保持构件80配置于齿轮主体22的内侧，在径向(齿轮主体22的径方向)上在与齿轮主体22之间保持多个销23。保持构件80配置于第一行星齿轮301和第二行星齿轮302这2个行星齿轮3之间。并且，保持构件80在外周面具有保持多个销23的多个外周槽801。即，在本实施方式中，代替实施方式一的支持体8而设置的保持构件80通过在与齿轮主体22之间夹着多个销23，从而作为抑制销23向从 齿轮主体22的内周面221离开的朝向移动的“狭缝”发挥功能。总之，通过多个销23的各个销与保持构件80的外周面接触，从而规制多个销23从齿轮主体22离开的朝向的移动，并且通过将多个销23嵌入外周槽801，从而也规制多个销23以旋转轴Ax1为中心的向周向的移动。也就是说，销23利用保持构件80和齿轮主体22，不仅在径向(径向方向)而且在周向也被定位。
因此，销23在保持构件80和齿轮主体22之间不易产生松动，在内齿21(销23)与外齿31啮合时，即使由外齿31从内周槽223拉出的朝向的力作用于销23，内齿21与外齿31的啮合也不易变得不稳定。由此，根据本实施方式的齿轮装置1A，具有容易使内齿21与外齿31的啮合稳定这样的优点。
然而，在本实施方式的齿轮装置1A中，内齿齿轮2也是“第一齿轮”的一例，行星齿轮3也是“第二齿轮”的一例。即，第一齿轮是具有环状的齿轮主体22和多个销23的内齿齿轮2。多个销23以能够自转的状态保持于在齿轮主体22的内周面221形成的多个内周槽223，并构成内齿21。第二齿轮是具有与内齿21局部性地啮合的外齿31的行星齿轮3。在该齿轮装置1中，通过使行星齿轮3以旋转轴Ax1为中心摆动，从而使行星齿轮3相对于内齿齿轮2相对旋转。并且，在本实施方式中，内齿齿轮2的骨架部225中的、至少与作为另一部件的多个销23滑动接触的多个内周槽223的内表面成为滑动接触部位。因此，至少多个内周槽223的内表面(滑动接触部位)被被覆层224覆盖。
实施方式二的结构(包含变形例在内)可以采用与实施方式一所说明的各种结构(包含变形例在内)适当组合。
(实施方式三)
如图17～图20所示，本实施方式的齿轮装置1C在包括刚性内齿齿轮2C、挠性外齿齿轮3C和波发生器4C的方面与实施方式一的齿轮装置1不同。
本实施方式的齿轮装置1C中，在环状的刚性内齿齿轮2C的内侧配置有环状的挠性外齿齿轮3C，进一步，在挠性外齿齿轮3C的内侧配置有波发生器4C。波发生器4C通过使挠性外齿齿轮3C挠曲为非圆形状，从而使挠性外齿齿轮3C的外齿31C局部性地与刚性内齿齿轮2C的内齿21C啮合。当波发生器4C旋 转时，内齿21C与外齿31C的啮合位置沿刚性内齿齿轮2C的圆周方向移动，并在两个齿轮(刚性内齿齿轮2C及挠性外齿齿轮3C)之间产生使挠性外齿齿轮3C根据与刚性内齿齿轮2C的齿数差进行的相对旋转。此处，如果刚性内齿齿轮2C被固定，则挠性外齿齿轮3C伴随着两个齿轮的相对旋转而旋转。其结果，可从挠性外齿齿轮3C获得与两个齿轮的齿轮差相应地、按照比较高的减速比进行了减速的旋转输出。
另外，使挠性外齿齿轮3C产生挠曲的波发生器4C具有以输入侧的旋转轴Ax1为中心被驱动旋转的非圆形状的凸轮41C和轴承42C。轴承42C配置于凸轮41C的外周面与挠性外齿齿轮3C的内周面301C之间。轴承42C的内圈422C固定于凸轮41C的外周面，轴承42C的外圈421C通过滚珠状的滚动体423C被凸轮41C按压而弹性变形。此处，通过滚动体423C滚动，外圈421C能够相对于内圈422C相对旋转，因此当非圆形状的凸轮41C旋转时，内圈422C的旋转部传递至外圈421C，而是在被凸轮41C按压的挠性外齿齿轮3C的外齿31C发生谐波运动。由于发生外齿31C的谐波运动，所以如上所述内齿21C与外齿31C的啮合位置沿刚性内齿齿轮2C的圆周方向移动，从而在挠性外齿齿轮3C与刚性内齿齿轮2C之间发生相对旋转。
总之，在这种齿轮装置1C中，具有轴承42C的波发生器4C一边使挠性外齿齿轮3C挠曲一边实现通过内齿21C与外齿31C的啮合而进行的动力传递。
更详细地说，作为齿轮装置1C的一例，例示杯型的谐波齿轮装置。也就是说，在本实施方式的齿轮装置1C中，使用形成为杯状的挠性外齿齿轮3C。波发生器4C以被收容于杯状的挠性外齿齿轮3C内的方式与挠性外齿齿轮3C组合。
在本实施方式的齿轮装置1C中，输入侧的旋转轴Ax1与输出侧的旋转轴Ax2处于同一直线上。换言之，输入侧的旋转轴Ax1和输出侧的旋转轴Ax2为同轴。此处，输入侧的旋转轴Ax1是施加有输入旋转的波发生器4C的旋转中心，输出侧的旋转轴Ax1是产生输出旋转的挠性外齿齿轮3C的旋转中心。也就是说，在齿轮装置1C中，能够在同轴上相对于输入旋转而得到以比较高的 减速比被减速了的输出旋转。
刚性内齿齿轮2C也称为刚轮(circular spline)，其为具有内齿21C的环状的部件。在本实施方式中，刚性内齿齿轮2C具有至少内周面在俯视时为正圆的圆环状。在圆环状的刚性内齿齿轮2C的内周面，沿着刚性内齿齿轮2C的圆周方向形成有内齿21C。构成内齿21C的多个齿为全部相同的形状，且等间距地设置在刚性内齿齿轮2C的内周面的圆周方向的整个区域。也就是说，内齿21C的节圆在俯视观察下为正圆。另外，刚性内齿齿轮2C在旋转轴Ax1的方向上具有规定的厚度。内齿21C均遍及刚性内齿齿轮2C的厚度方向的全长地形成。内齿21C的齿向均与旋转轴Ax1平行。
挠性外齿齿轮3C也称为柔轮(flex spline)，其为具有外齿31C的环状的部件。在本实施方式中，挠性外齿齿轮3C是利用比较薄壁的金属弹性体(金属板)形成为杯状的部件。也就是说，挠性外齿齿轮3C由于其厚度比较小(薄)而具有挠性。挠性外齿齿轮3C具有杯状的主体部32C。主体部32C具有躯体部321C及底部322C。在挠性外齿齿轮3C未产生弹性变形的状态下，躯体部321C的至少内周面301C具有在俯视时为正圆的圆筒状。躯体部321C的中心轴与旋转轴Ax1一致。底部322C配置于躯体部321C的一方的开口面，并具有在俯视时为正圆的圆盘状。底部322C配置于躯体部321C的一对开口面中的、靠旋转轴Ax1的输出侧的开口面。根据上述内容，主体部32C通过躯体部321C及底部322C的整体实现向旋转轴Ax1的输入侧敞开的、有底的圆筒状即杯状的形状。换言之，在挠性外齿齿轮3C的旋转轴Ax1的方向上的与底部322C相反一侧的端面形成有开口面35C。也就是说，挠性外齿齿轮3C是在齿向方向D1的一侧(此处为旋转轴Ax1的输入侧)具有开口面35C的筒状。在本实施方式中，躯体部321C及底部322C由1个金属构件一体形成，由此能够实现无缝的主体部32C。
此处，以在躯体部321C的内侧嵌入非圆形状的波发生器4C的方式使波发生器4C与挠性外齿齿轮3C组合。由此，挠性外齿齿轮3C从内侧朝向外侧地、从波发生器4C受到径向方向(与旋转轴Ax1正交的方向)的外力，由此弹性 变形为非圆形状。在本实施方式的第一比较例中，通过椭圆形状的波发生器4C与挠性外齿齿轮3C组合，从而挠性外齿齿轮3C的躯体部321C弹性变形为椭圆形状(参照图18)。也就是说，挠性外齿齿轮3C为产生弹性变形的状态是指波发生器4C未与挠性外齿齿轮3C组合的状态。相反，挠性外齿齿轮3C产生弹性变形的状态是指波发生器4C与挠性外齿齿轮3C组合的状态。
更详细地说，波发生器4C嵌入躯体部321C的内周面301C中的与底部322C相反一侧(旋转轴Ax1的输入侧)的端部。换言之，波发生器4C嵌入挠性外齿齿轮3C的躯体部321C中的、旋转轴Ax1的方向上的开口面35C侧的端部。因此，在挠性外齿齿轮3C产生弹性变形的状态下，挠性外齿齿轮3C在旋转轴Ax1的方向上的开口面35C侧的端部处变形得比底部322C侧的端部大，成为更接近椭圆形状的形状。根据这样的旋转轴Ax1的方向上的变形量的不同，在挠性外齿齿轮3C产生弹性变形的状态下，挠性外齿齿轮3C的躯体部321C的内周面301C包含相对于旋转轴Ax1倾斜的渐缩面。
另外，在躯体部321C的外周面中的至少与底部322C相反一侧(旋转轴Ax1的输入侧)的端部沿着躯体部321C的圆周方向形成有外齿31C。换言之，外齿31C设置于挠性外齿齿轮3C的躯体部321C中的、至少旋转轴Ax1的方向上的开口面35C侧的端部。构成外齿31C的多个齿为全部相同的形状，且等间距地设置于挠性外齿齿轮3C的外周面的圆周方向的整个区域。也就是说，外齿31C的节圆在挠性外齿齿轮3C未产生弹性变形的状态下，在俯视时为正圆。外齿31C仅形成于从躯体部321C的开口面35C侧(旋转轴Ax1的输入侧)的端缘起的一定宽度的范围内。具体而言，在躯体部321C中的、在旋转轴Ax1的方向上至少供波发生器4C嵌入的部分(开口面35C侧的端部)且在外周面形成有外齿31C。外齿31C的齿向均与旋转轴Ax1平行。
如此构成的挠性外齿齿轮3C配置于刚性内齿齿轮2C的内侧。此处，挠性外齿齿轮3C以仅仅躯体部321C的外周面中的与底部322C相反一侧(旋转轴Ax1的输入侧)的端部***刚性内齿齿轮2C的内侧的方式与刚性内齿齿轮2C组合。也就是说，挠性外齿齿轮3C的躯体部321C中的、旋转轴Ax1的方向上， 供波发生器4C嵌入的部分(开口面35C侧的端部)***刚性内齿齿轮2C的内侧。此处，在挠性外齿齿轮3C的外周面形成有外齿31C，在刚性内齿齿轮2C的内周面形成有内齿21C。因此，在挠性外齿齿轮3C配置于刚性内齿齿轮2C的内侧的状态下，外齿31C与内齿21C彼此相对。
此处，刚性内齿齿轮2C中的内齿21C的齿数比挠性外齿齿轮3C的外齿31C的齿数多2N(N为正整数)。在本实施方式中，作为一例，N为“1”，挠性外齿齿轮3C的(外齿31C的)齿数比刚性内齿齿轮2C的(内齿21C的)齿数多“2”。这样的挠性外齿齿轮3C与刚性内齿齿轮2C的齿数差规定了齿轮装置1C中的输出旋转相对于输入旋转的减速比。
在此处，在本实施方式中作为一例，以外齿31C的齿向方向D1的中心与内齿21C的齿向方向D1的中心相对的方式设定旋转轴Ax1的方向上的挠性外齿齿轮3C与刚性内齿齿轮2C的相对位置。也就是说，在挠性外齿齿轮3C的外齿31C与刚性内齿齿轮2C的内齿21C中，齿向方向D1的中心的位置对准旋转轴Ax1的方向的同一位置。另外，在本实施方式中，外齿31C的齿向方向D1的尺寸(齿宽)比内齿21C的齿向方向D1的尺寸(齿宽)大。因此，在与旋转轴Ax1平行的方向上，内齿21C收敛于外齿31C的齿向的范围内。换言之，外齿31C相对于内齿21C向齿向方向D1的至少一侧突出。在本实施方式中，外齿31C相对于内齿21C向齿向方向D1的两侧(旋转轴Ax1的输入侧及输出侧)突出。
此处，在挠性外齿齿轮3C未产生弹性变形的状态(波发生器4C未与挠性外齿齿轮3C组合的状态)下，描绘正圆的外齿31C的节圆设定为与同样描绘正圆的内齿21C的节圆相比小一圈。也就是说，在挠性外齿齿轮3C未产生弹性变形的状态下，外齿31C与内齿21C隔着间隙相对，而彼此未啮合。
另一方面，在挠性外齿齿轮3C产生弹性变形的状态(波发生器4C与挠性外齿齿轮3C组合的状态)下，由于躯体部321C挠曲为非圆形状，所以挠性外齿齿轮3C的外齿31C与刚性内齿齿轮2C的内齿21C局部性地啮合。也就是说，在第一比较例中，如图18所示，挠性外齿齿轮3C的躯体部321C(的至少 开口面35C侧的端部)弹性变形为椭圆形状，由此位于椭圆形状的长轴方向的两端的外齿31C与内齿21C啮合。换言之，描绘椭圆的外齿31C的节圆的长径与描绘正圆的内齿21C的节圆的直径一致，描绘椭圆的外齿31C的节圆的短径比描绘正圆的内齿21C的节圆的直径小。如此，当挠性外齿齿轮3C弹性变形时，构成外齿31C的多个齿中的一部分齿与构成内齿21C的多个齿中的一部分齿啮合。结果是，在齿轮装置1C中，能够使外齿31C的一部分与内齿21C的一部分啮合。
波发生器4C也称为波形发生器(wave generator)，其是使挠性外齿齿轮3C产生挠曲，从而使挠性外齿齿轮3C的外齿31C产生谐波运动的部件。在本实施方式的第一比较例中，波发生器4C是俯视时外周形状为非圆形状、具体而言为椭圆形状的部件。
然而，在本实施方式的齿轮装置1C中，刚性内齿齿轮2C为“第一齿轮”的一例，挠性外齿齿轮3C为“第二齿轮”的一例。即，第一齿轮是具有内齿21C的环状的刚性内齿齿轮2C。第二齿轮是具有外齿31C且配置于刚性内齿齿轮2C的内侧的环状的挠性外齿齿轮3C。该齿轮装置1C还包括配置于挠性外齿齿轮3C的内侧、并使挠性外齿齿轮3C产生挠曲的波发生器4C。齿轮装置1C伴随着以旋转轴Ax1为中心的波发生器4C的旋转而使挠性外齿齿轮3C变形，使外齿31C的一部分与内齿21C的一部分啮合，从而使挠性外齿齿轮3C根据与刚性内齿齿轮2C的齿数差而相对于刚性内齿齿轮2C进行相对旋转。并且，刚性内齿齿轮2C(第一齿轮)的骨架部225中的、至少作为另一部件的外齿31C滑动接触的内齿21C的表面被被覆层224覆盖。
总之，在本实施方式中，由于刚性内齿齿轮2C为“第一齿轮”的一例，所以例如将铝(Al)制的骨架部225作为刚性内齿齿轮2C的基材。并且，如上所述，在挠性外齿齿轮3C弹性变形为椭圆形状的情况下，在椭圆形状的长轴方向的两端侧的2个部位，外齿31C与内齿21C啮合。这样，在内齿21C中的与外齿31C的多个啮合部位处，在内齿21C与外齿31C之间产生滑动接触。因此，在作为第一齿轮的刚性内齿齿轮2C中，其内齿21C的表面成为与另一 部件(挠性外齿齿轮3C的外齿31C)的滑动接触部位，因此该内齿21C的表面例如被铁(Fe)制的被覆层224覆盖。
作为实施方式三的变形例，也不是必须第一齿轮为刚性内齿齿轮2C，第二齿轮为挠性外齿齿轮3C。例如，也可以是第一齿轮为挠性外齿齿轮3C，第二齿轮为刚性内齿齿轮2C。在该情况下，挠性外齿齿轮3C的基材构成骨架部，例如，利用被覆层覆盖挠性外齿齿轮3C中的与另一部件(波发生器4C)的滑动接触部位。
实施方式三(包含变形例在内)的结构可以采用与实施方式一或实施方式二所说明的各种结构(包含变形例在内)适当组合。
(总结)
如以上说明那样，第一形态的齿轮装置(1、1A、1C)包括第一齿轮和第二齿轮。第二齿轮通过与第一齿轮啮合而相对于第一齿轮相对旋转。第一齿轮具有骨架部(225)和比重比骨架部(225)大的被覆层(224)。骨架部(225)中的至少与另一部件的滑动接触部位被被覆层(224)覆盖。
根据该形态，第一齿轮的骨架部(225)自身由于为比重小的材质，例如即使具有相应的厚度，也能够将重量抑制得比较小。另一方面，关于骨架部(225)中的(与另一部件的)滑动接触部位，由于被比重比骨架部(225)大的被覆层(224)覆盖，因此滑动接触部位能够提高耐磨损性并维持作为第一齿轮的强度。结果是，能够实现在维持强度的同时容易实现轻量化的齿轮装置(1、1A、1C)。
在第二形态的齿轮装置(1、1A、1C)中，在第一形态的基础上，骨架部(225)的导热率比被覆层(224)高。
根据该形态，能够由导热率高的骨架部(225)构成第一齿轮的大部分，且能够提高第一齿轮的散热性。
在第三形态的齿轮装置(1、1A、1C)中，在第一或第二形态的基础上，被覆层(224)是与骨架部(225)不同组成的喷镀膜。
根据该形态，容易形成比较大的膜厚的被覆层(224)。
在第四形态的齿轮装置(1、1A、1C)中，在第一～三中任一形态的基础 上，第一齿轮在骨架部(225)的表面具有基底层(226)，被覆层(224)层叠于基底层(226)。
根据该形态，能够提高被覆层(224)相对于骨架部(225)的密合性。
在第五形态的齿轮装置(1、1A、1C)中，在第四形态的基础上，基底层(226)的格方向是以滑动接触部位中的另一部件的滑动方向为基准的方向。
根据该形态，能够提高被覆层(224)相对于骨架部(225)的密合性。
在第六形态的齿轮装置(1、1A、1C)中，在第一～五中任一形态的基础上，被覆层(224)具有50μm以上的厚度。
根据该形态，在滑动接触部位处，能够避免另一部件与骨架部(225)直接接触，容易抑制骨架部(225)的磨损。
在第七形态的齿轮装置(1、1A、1C)中，在第一～六中任一形态的基础行，第一齿轮为内齿齿轮(2)，第二齿轮为行星齿轮(3)。内齿齿轮(2)具有：环状的齿轮主体(22)；和多个销(23)，以能够自转的状态保持于在齿轮主体(22)的内周面(221)形成的多个内周槽(223)，并构成内齿(21)。行星齿轮(3)具有与内齿(21)局部性地啮合的外齿(31)。齿轮装置(1、1A、1C)通过使以旋转轴(Ax1)为中心摆动，从而使行星齿轮(3)相对于内齿齿轮(2)相对旋转。内齿齿轮(2)的骨架部(225)中的、至少作为另一部件的多个销(23)滑动接触的多个内周槽(223)的内表面被被覆层(224)覆盖。
根据该形态，在内啮合行星齿轮装置中，能够实现在维持强度的同时容易实现轻量化的齿轮装置(1、1A、1C)。
在第八形态的齿轮装置(1、1A、1C)中，在第一～六中任一形态的基础上，第一齿轮为具有内齿(21C)的环状的刚性内齿齿轮(2C)第二齿轮为具有外齿(31C)且配置于刚性内齿齿轮(2C)的内侧的环状的挠性外齿齿轮(3C)。齿轮装置(1、1A、1C)还包括配置于挠性外齿齿轮(3C)的内侧，并使挠性外齿齿轮(3C)产生挠曲的波发生器(4C)。齿轮装置(1、1A、1C)是伴随着以旋转轴(Ax1)为中心的波发生器(4C)的旋转而使挠性外齿齿轮(3C)变形，使外齿(31C)的一部分与内齿(21C)的一部啮合，从而使挠性外齿齿 轮(3C)根据与刚性内齿齿轮(2C)的齿数差而相对于刚性内齿齿轮(2C)进行相对旋转的齿轮装置。刚性内齿齿轮的骨架部(225)中的、至少作为另一部件的外齿(31C)滑动接触的内齿(21C)的表面被被覆层(224)覆盖。
根据该形态，在谐波齿轮装置中，能够实现在维持强度的同时容易实现轻量化的齿轮装置(1、1A、1C)。
第九形态的齿轮装置的制造方法为第一～八中任一形态的齿轮装置的制造方法，具有通过喷镀在第一齿轮的骨架部(225)的至少一部分形成被覆层(224)的喷镀工序。
根据该形态，第一齿轮的骨架部(225)自身由于为比重小的材质，例如即使具有相应的厚度，也能够将重量抑制得比较小。另一方面，关于骨架部(225)中的(与另一部件的)滑动接触部位，由于被利用喷镀形成且比重比骨架部(225)大的被覆层(224)覆盖，因此滑动接触部位能够提高耐磨损性并维持作为第一齿轮的强度。结果是，能够实现在维持强度的同时容易实现轻量化的齿轮装置(1、1A、1C)的制造方法。
关于第二～八形态的结构，不是齿轮装置(1、1A、1C)所需的结构，能够适当省略。
附图标记说明
1、1A(内啮合行星)齿轮装置
1C(谐波)齿轮装置
2内齿齿轮(第一齿轮)
2C刚性内齿齿轮(第一齿轮)
3行星齿轮(第二齿轮)
3C挠性外齿齿轮(第二齿轮)
4C波发生器
21、21C内齿
22齿轮主体
23销(另一部件)
31、31C外齿(另一部件)
221(齿轮主体的)内周面
223内周槽
224被覆层
225骨架部
226基底层
Ax1旋转轴
工业实用性
根据本公开实施例，能够提供在维持强度的同时容易实现轻量化的齿轮装置和齿轮装置的制造方法。

Claims (9)

  1. 一种齿轮装置，其中，包括：
    第一齿轮；
    第二齿轮，通过与所述第一齿轮啮合而相对于所述第一齿轮相对旋转，
    所述第一齿轮具有骨架部和比重比所述骨架部大的被覆层，
    所述骨架部中的至少与另一部件滑动接触的滑动接触部位被所述被覆层覆盖。
  2. 根据权利要求1所述的齿轮装置，其中，
    所述骨架部的导热率比所述被覆层高。
  3. 根据权利要求1或2所述的齿轮装置，其中，
    所述被覆层为与所述骨架部不同组成的喷镀膜。
  4. 根据权利要求1或2所述的齿轮装置，其中，
    所述第一齿轮在所述骨架部的表面具有基底层，所述被覆层层叠于所述基底层。
  5. 根据权利要求4所述的齿轮装置，其中，
    所述基底层的格方向为以所述滑动接触部位处的所述另一部件的滑动方向为基准的方向。
  6. 根据权利要求1或2所述的齿轮装置，其中，
    所述被覆层具有50μm以上的厚度。
  7. 根据权利要求1或2所述的齿轮装置，其中，
    所述第一齿轮是具有环状的齿轮主体和以能够自转的状态保持于在所述齿轮主体的内周面形成的多个内周槽并构成内齿的多个销的内齿齿轮，
    所述第二齿轮是具有与所述内齿局部性地啮合的外齿的行星齿轮，
    通过使所述行星齿轮以旋转轴为中心摆动，使所述行星齿轮相对于所述内齿齿轮相对旋转，
    所述内齿齿轮的所述骨架部中的、至少作为所述另一部件的所述多个销所滑动接触的所述多个内周槽的内表面被所述被覆层覆盖。
  8. 根据权利要求1或2所述的齿轮装置，其中，
    所述第一齿轮是具有内齿的环状的刚性内齿齿轮，
    所述第二齿轮是具有外齿且配置于所述刚性内齿齿轮的内侧的环状的挠性外齿齿轮，
    所述齿轮装置还包括波发生器，所述波发生器配置于所述挠性外齿齿轮的内侧，并使所述挠性外齿齿轮产生挠曲，
    在所述齿轮装置中，伴随着以旋转轴为中心的所述波发生器的旋转而使所述挠性外齿齿轮变形，使所述外齿的一部分与所述内齿的一部分啮合，从而使所述挠性外齿齿轮根据与所述刚性内齿齿轮的齿数差而相对于所述刚性内齿齿轮相对旋转，
    所述刚性内齿齿轮的所述骨架部中的、至少作为所述另一部件的所述外齿所滑动接触的所述内齿的表面被所述被覆层覆盖。
  9. 一种齿轮装置的制造方法，是权利要求1～8中任一项所述的齿轮装置的制造方法，其中，
    具有通过喷镀在所述第一齿轮的所述骨架部的至少一部分形成所述被覆层的喷镀工序。
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