JP6767804B2 - Gear transmission - Google Patents

Description

The present invention relates to a gear transmission.

Conventionally, an eccentric swing type gear transmission using a planetary gear mechanism has been known. In such a gear reducer, the external gear is inscribed in the internal gear and meshed with the internal gear, and the external gear is swung by an input shaft which is an eccentric body rotatably supported by the external gear. As a result, the external gear rotates on its axis while revolving around the input shaft. Then, the rotation motion of the external gear is transmitted to the output shaft, so that the rotation of the input shaft is changed and output to the output shaft. Such a gear transmission is described in, for example, Japanese Patent Application Laid-Open No. 5-272598.

The gear transmission described in the document includes a main rotary shaft, a pinion provided on the main rotary shaft, a first gear having a plurality of transmission gears that mesh with the pinions, and a plurality of eccentric bodies that rotate together with the transmission gear. The shaft, the eccentric body provided on the eccentric body shaft, the external gear that is supported by the eccentric body via the eccentric body bearing and swings and rotates with respect to the main rotating shaft, and the internal gear that meshes with the external gear. , It is provided with a pair of support blocks that rotatably support both ends of the eccentric body shaft and rotate the rotation component of the external gear, and a second shift stage having a carrier body that connects the pair of support blocks to each other. ..

Then, two or more gear ratios of the first gear are set, the distance between the axes of the pinion and the transmission gear is equal, two or more gear ratios of the second gear are set, and the cross-sectional shape of the carrier body is the first. The shape of the fitting hole of the external gear through which the carrier body penetrates is equal in at least two or more gear ratios of the two gears, and the internal gear is equal in at least two or more gear ratios of the second gear. It is common to at least two or more gear ratios of the second gear. Further, the number of teeth of the external gear in each gear ratio of the second gear is set to an integral multiple of the number of each external gear, and the difference in the number of teeth between the internal gear and the external gear is set to that of the external gear. It is set to an integral multiple of the number of sheets. As a result, it is described that a wide reduction ratio can be secured and the assembly accuracy can be improved without increasing the processing man-hours and the number of parts.
JP-A-5-272598

By the way, in recent years, application of gear transmissions to small robots and the like has been studied. Here, a technique for miniaturizing a gear transmission is important. However, rolling bearings are generally used for bearings that rotatably support the rotating shaft of a gear transmission. The rolling bearing is composed of a rolling element and a raceway ring, and can stably rotate the rotating shaft. However, when a rolling bearing is used for a gear transmission, the width in the radial direction becomes large due to its configuration, and it becomes difficult to miniaturize the gear transmission.

On the other hand, if a plain bearing can be used as the bearing of the gear transmission, the size of the gear transmission can be reduced. However, plain bearings have lower life, assembly accuracy, rigidity, etc. than rolling bearings. For this reason, when a slide bearing is used for the gear transmission, there is a problem that rattling or the like occurs during driving, and it is difficult to drive the gear in a stable manner.

An object of the present invention is to provide a technique capable of stably driving a gear transmission while applying a slide bearing to the bearing of the gear transmission.

An exemplary first invention of the present application is an eccentric swing type gear transmission, in which a first rotating portion that rotates at a first rotation speed around a rotating shaft extending forward and backward, and the first rotating portion. The second rotating portion, which is arranged behind the rotation axis and rotates at a second rotation speed smaller than the first rotation speed, and the outer peripheral portion of the first rotating portion, are arranged around the rotation axis. An eccentric body that rotates together with one rotating portion, an external tooth gear that is arranged on the radial outer side of the eccentric body and has a plurality of external teeth on the outer periphery, and a plurality of external gears that are interposed between the eccentric body and the external tooth gear. An eccentric bearing, a cylindrical housing arranged on the radial outer side of the external gear, an internal gear provided on the inner peripheral portion of the housing and having a plurality of internal teeth that mesh with the external teeth, and the above. A plurality of carrier pins that penetrate the external gear and extend axially, and at least a part of the carriers that are arranged radially inside the housing and support the plurality of carrier pins by connecting them, and at least a part of the carrier pins. It has a sliding bearing which is arranged between the carrier and the housing in the radial direction and rotatably supports the carrier with respect to the housing, and the sliding bearing has an axial direction with the external gear. It has a first end portion facing the carrier and a second end portion facing the carrier in the axial direction, and the radial width of the second end portion is larger than the radial width of the first end portion. Is also big.

According to the first exemplary invention of the present application, the area of the surface of the slide bearing that receives the axial load can be increased. Therefore, the gear transmission can be miniaturized by using the slide bearing, and the gear transmission can be stably driven by suppressing rattling during driving.

FIG. 1 is a vertical cross-sectional view of the gear reducer according to the first embodiment. FIG. 2 is a cross-sectional view of the gear reducer according to the first embodiment. FIG. 3 is an enlarged cross-sectional view of the gear reducer according to the first embodiment. FIG. 4 is a vertical cross-sectional view of the gear reducer according to the modified example. FIG. 5 is a vertical cross-sectional view of the gear reducer according to the modified example.

Hereinafter, exemplary embodiments of the present invention will be described with reference to the drawings. In the present application, the direction parallel to the rotation axis is referred to as "axial direction", the direction orthogonal to the rotation axis is referred to as "diameter direction", and the direction along the arc centered on the rotation axis is referred to as "circumferential direction". However, the above-mentioned "parallel direction" also includes a substantially parallel direction. Further, the above-mentioned "orthogonal direction" includes a direction substantially orthogonal to each other. In the following, the input shaft side of FIG. 1 will be referred to as “axially forward”, and the output shaft side of FIG. 1 will be referred to as “axially rearward”. However, the definitions of these directions are not intended to limit the directions when the gear reducer according to the present invention is used.

<1. First Embodiment>
FIG. 1 is a vertical cross-sectional view of a gear reducer 1 which is a gear transmission according to a first embodiment of the present invention, cut by a plane including a rotating shaft 90. FIG. 2 is a cross-sectional view of the gear reducer 1 as viewed from the AA position in FIG.

This gear reducer 1 is an inscribed planetary speed reducer, and has a rotational motion of a second rotational speed (output rotational speed) whose rotational motion of the first rotation speed (input rotation speed) is lower than that of the first rotation speed. It is an eccentric swing type gear reducer that converts to. The gear reducer 1 is used, for example, in the joints of a small robot such as a service robot. However, the gear reducer 1 may be incorporated and used in a drive mechanism such as a large robot, a machine tool, an XY table, a material cutting device, a conveyor line, a turntable, or a rolling roller. Further, the gear reducer 1 may be used for other purposes.

As shown in FIG. 1, the gear reducer 1 of the present embodiment includes a first rotating portion 11, a second rotating portion 12, an eccentric body 13, an external gear 20, an eccentric bearing 30, a housing 40, and an internal gear 50. It has a carrier 60, a carrier pin 70, and a sliding bearing 80.

The first rotation unit 11 of the present embodiment is a columnar member that rotates at the first rotation speed, which is the rotation speed input from the outside. The first rotating portion 11 is arranged along the rotating shaft 90. The axially forward end of the first rotating portion 11 is connected to the motor, which is the drive source, either directly or via another power transmission mechanism. When the motor is driven, the first rotation unit 11 rotates at the first rotation speed around the rotation shaft 90.

An eccentric body 13 is fixed to the outer peripheral portion of the first rotating portion 11. The eccentric body 13 has a first eccentric portion 131 and a second eccentric portion 132 located axially rearward of the first eccentric portion 131. The first eccentric portion 131 has a cylindrical outer peripheral surface centered on the first rotating shaft 91 extending in parallel with the rotating shaft 90 at a position deviated from the rotating shaft 90. The second eccentric portion 132 also has a cylindrical outer peripheral surface centered on the second rotating shaft 92 extending in parallel with the rotating shaft 90 at a position deviated from the rotating shaft 90. When the first rotating portion 11 rotates, the positions of the first rotating shaft 91 and the second rotating shaft 92 also rotate about the rotating shaft 90.

The second rotation unit 12 is an output unit that rotates around the rotation shaft 90 at the second rotation speed. The second rotating portion 12 is a columnar member arranged axially rearward from the first rotating portion 11 along the rotating shaft 90.

The external gear 20 is arranged on the outer side in the radial direction of the first rotating portion 11. In the present embodiment, the gear reducer 1 has two external gears 20 of a first external gear 21 and a second external gear 22.

The eccentric bearing 30 is fixed to the outer peripheral portion of the eccentric body 13 and rotatably supports the external gear 20 with respect to the first rotating portion 11. In the eccentric bearing 30 of the present embodiment, a rolling bearing that rotates the external gear 20 and the eccentric body 13 via a sphere is used.

The first external gear 21 is attached to the outer peripheral surface of the first eccentric portion 131 via an eccentric bearing 30. Therefore, the first external gear 21 is rotatably supported around the first rotation shaft 91 of the first eccentric portion 131. The second external gear 22 is attached to the outer peripheral surface of the second eccentric portion 132 axially rearward of the first external gear 21 via an eccentric bearing 30. Therefore, the second external gear 22 is rotatably supported around the second rotating shaft 92 of the second eccentric portion 132.

As shown enlarged in FIG. 2, the second external tooth gear 22 has a plurality of external teeth 23 protruding outward in the radial direction on the outer peripheral portion thereof. Further, an interdental groove 24 that is recessed inward in the radial direction is provided between the adjacent external teeth 23. The external teeth 23 and the external interdental grooves 24 are alternately arranged in the circumferential direction with the second rotation shaft 92 as the center. Further, the first external tooth gear 21 also has a plurality of external teeth 23 and a plurality of external interdental grooves 24 on the outer peripheral portion, similarly to the second external tooth gear 22.

Further, as shown in FIGS. 1 and 2, the second external gear 22 has a plurality of (10 in the example of FIG. 2) pin holes 25. The plurality of pin holes 25 are arranged at equal intervals in the circumferential direction with the second rotation shaft 92 as the center. Each pin hole 25 penetrates the second external tooth gear 22 in the axial direction in the radial direction inside the external tooth 23 and the external interdental groove 24. Further, the first external gear 21 also has a plurality of pin holes 25 like the second external gear 22.

The housing 40 is a cylindrical member arranged on the outer side in the radial direction of the external gear 20. The housing 40 has an internal gear 50 on the inner peripheral portion. As shown enlarged in FIG. 2, the internal gear 50 has a plurality of internal teeth 51 projecting inward in the radial direction at the inner peripheral portion thereof. Further, an internal interdental groove 52 recessed outward in the radial direction is provided between the adjacent internal teeth 51. The internal teeth 51 and the internal interdental grooves 52 are alternately arranged in the circumferential direction with the rotation axis 90 as the center.

The plurality of external teeth 23 of the external gears 21 and 22 and the plurality of internal teeth 51 of the internal gear 50 mesh with each other. That is, when the gear reducer 1 is operating, the external teeth 23 of the external gears 21 and 22 are fitted into the internal interdental grooves 52 of the internal gear 50, and the external teeth 23 of the external gears 21 and 22 are fitted into the external interdental grooves 24 of the external gears 21 and 22. While the internal teeth 51 of the tooth gear 50 are fitted, the external gears 21 and 22 rotate. In the present embodiment, the internal gear 50 and the housing 40 are composed of a single member. As a result, the internal gear 50 can be formed on the inner peripheral portion of the housing 40 even when the housing 40 is miniaturized. However, the internal gear 50 and the housing 40 may be separate members. For example, the internal gear 50 may be configured by providing internal teeth of another member on the inner peripheral portion of the housing 40.

The first external gear 21 and the second external gear 22 revolve around the rotating shaft 90 by the power of the first rotating portion 11 and rotate by engaging with the internal teeth 51 of the internal gear 50. Here, the number of internal teeth 51 of the internal gear 50 is larger than the number of external teeth 23 of each of the first external gear 21 and the second external gear 22. Therefore, the position of the external tooth 23 that meshes with the internal tooth 51 at the same position of the internal tooth gear 50 shifts for each revolution of each external tooth gear 21 and 22. As a result, the first external gear 21 and the second external gear 22 rotate in the direction opposite to the rotation direction of the first rotating portion 11 at a second rotation speed lower than the first rotation speed. Therefore, the positions of the pin holes 25 of the external gears 21 and 22 also rotate at the second rotation speed.

Assuming that the number of external teeth 23 of each of the first external gear 21 and the second external gear 22 is N and the number of internal teeth 51 of the internal gear 50 is M, the reduction ratio P of the gear reducer 1 is P. Is P = (first rotation speed) / (second rotation speed) = N / (MN). In the example of FIG. 2, since N = 29 and M = 30, the reduction ratio in this example is P = 29. That is, the second rotation speed is 1/29 of the first rotation speed. However, the reduction ratio of the reduction mechanism in the present invention may be another value.

The carrier 60 is an annular portion arranged perpendicular to the rotation axis 90. At least a portion of the carrier 60 is arranged radially inside the housing 40. The carrier 60 of the present embodiment is composed of a first carrier 61 and a second carrier 62. The first carrier 61 and the second carrier 62 have a plurality of press-fitting holes 64 for fixing the carrier pin 70.

The first carrier 61 is arranged axially forward of the first external gear 21. A first bearing 141 is arranged between the first carrier 61 and the first rotating portion 11 in the radial direction. The first bearing 141 is fixed to the outer peripheral portion of the first rotating portion 11 and supports the first carrier 61 so as to be relatively rotatably relative to the first rotating portion 11. In the first bearing 141 of the present embodiment, a rolling bearing that rotates the first carrier 61 and the first rotating portion 11 via a sphere is used.

As shown in FIG. 1, in the present embodiment, the axially forward end face of the first carrier 61 and the axially front end face of the housing 40 are arranged on the same plane perpendicular to the rotation axis 90. .. As a result, positioning when assembling the gear reducer 1 can be performed with reference to the axially forward end surface of the housing 40, which is a fixing member. As a result, the assembly accuracy of the gear reducer 1 can be improved.

The second carrier 62 is arranged axially rearward of the second external gear 22. A second bearing 142 is arranged between the second carrier 62 and the first rotating portion 11 in the radial direction. The second bearing 142 is fixed to the outer peripheral portion of the first rotating portion 11 and supports the second carrier 62 so as to be relatively rotatably relative to the first rotating portion 11. In the second bearing 142 of the present embodiment, a rolling bearing that rotates the second carrier 62 and the first rotating portion 11 via a sphere is used.

A through hole 63 penetrating in the axial direction is provided near the center of the second carrier 62. The second rotating portion 12 is arranged in the through hole 63 and fixed to the second rotating portion 12. As a result, the second carrier 62 rotates about the rotation shaft 90 together with the second rotating portion 12.

The plurality of carrier pins 70 are columnar members extending in the axial direction through the plurality of pin holes 25 of the first external gear 21 and the second external gear 22. As shown in FIG. 2, a gap 26 is interposed between the surface forming each pin hole 25 and the outer peripheral surface of the carrier pin 70. When the first external gear 21 and the second external gear 22 rotate at the second rotation speed after deceleration, the power is transmitted to each carrier pin 70 through the gap 26.

Axial front ends of the plurality of carrier pins 70 are inserted into the press-fitting holes 64 of the first carrier 61. Further, the axially rear end portions of the plurality of carrier pins 70 are inserted into the press-fitting holes 64 of the second carrier 62. As a result, the plurality of carrier pins 70 are fixed to the first carrier 61 and the second carrier 62. Then, the plurality of carrier pins 70, the first carrier 61, the second carrier 62, and the second rotating portion 12 rotate at the second rotation speed around the rotation shaft 90.

The plain bearing 80 rotatably supports the carrier 60 relative to the housing 40. The plain bearing 80 is an annular member arranged between the housing 40 and the carrier 60 in the radial direction. The slide bearing 80 of the present embodiment is made of, for example, a resin such as polyacetal. However, the slide bearing 80 may be made of a material other than resin.

The gear reducer 1 of the present embodiment has two slide bearings 80, that is, a first slide bearing 81 and a second slide bearing 82. As shown in FIG. 1, the first slide bearing 81 is arranged axially forward of the first external gear 21. The axially front end of the first slide bearing 81 is located axially rearward of the axially front end of the housing 40. Further, the axially forward end portion of the first slide bearing 81 faces a part of the first carrier 61 in the axial direction.

The second slide bearing 82 is arranged rearward in the axial direction of the second external gear 22. Further, the second slide bearing 82 has a first end portion 801 and a second end portion 802. The first end portion 801 is an axially forward end portion of the second slide bearing 82 and faces the second external gear 22 in the axial direction. The second end portion 802 is an axially rear end portion of the second slide bearing 82 and faces a part of the second carrier 62 in the axial direction. The radial width of the second end 802 is larger than the radial width of the first end 801. As a result, the area of the surface of the second slide bearing 82 that receives the load in the axial direction can be increased. As a result, even when the slide bearing 80 is used, it is possible to receive a load in the axial direction, suppress rattling during driving, and stably drive the gear reducer.

Further, in the present embodiment, the first slide bearing 81 and the second slide bearing 82 are arranged axially forward of the first external gear 21 and rearward of the second external gear 22 in the axial direction, respectively. Therefore, the external gear 20 is supported from both sides in the axial direction by the slide bearing 80. Therefore, even when the slide bearing 80 is used, the carrier 60 can be stably rotated while suppressing rattling during driving of the gear transmission.

Further, the second slide bearing 82 of the present embodiment has a cylindrical portion 83 extending in the axial direction and a flange portion 84 extending radially outward from the axially rear end portion of the cylindrical portion 83. The first end portion 801 is an axially forward end portion of the cylindrical portion 83, and the second end portion 802 is a flange portion 84.

The flange portion 84 faces the housing 40 in the axial direction. Further, the outer peripheral surface of the flange portion 84 is exposed when viewed from the outside in the radial direction. Therefore, the gap between the second slide bearing 82 and the second carrier 62 can be confirmed from the outside. Then, it is easy to adjust the gap between the second slide bearing 82 and the second carrier 62 to an appropriate width. As a result, the contact at high temperature due to the gap between the second slide bearing 82 and the second carrier 62 being too narrow, and the relative backlash due to the gap between the second slide bearing 82 and the second carrier 62 being too wide. The bearing can be suppressed.

Further, in the present embodiment, at least a part of the flange portion 84, the second carrier 62, and the housing 40 overlap in the axial direction. As a result, the assembly position accuracy of the second slide bearing 82 with respect to the housing 40 and the second carrier 62 can be improved.

FIG. 3 is a partial cross-sectional view of the vicinity of the flange portion 84. As shown in FIG. 3, in the present embodiment, the first gap 841 is interposed between the housing 40 and the flange portion 84. Further, a second gap 842 is interposed between the second carrier 62 and the housing 40. The axial width d2 of the second gap 842 is larger than the axial width d1 of the first gap 841. As a result, the second carrier 62 can be slid more stably with respect to the second slide bearing 82. The housing 40 and the flange portion 84 may come into contact with each other. That is, the first gap 841 does not have to exist.

As described above, conventionally, a rolling bearing has been used between the carrier and the housing. Therefore, it has been difficult to reduce the size of the gear transmission. However, in the gear reducer 1 of the present embodiment, the slide bearing 80 is interposed between the carrier 60 and the housing 40. Therefore, in the gear reducer 1 of the present embodiment, it is possible to realize a small gear reducer 1 having an outer diameter of the housing 40 of 50 mm or less. Further, since the slide bearing 80 of the present embodiment has a wide radial width of the second end portion 802, the area of the surface of the slide bearing 80 that receives the axial load can be increased. Therefore, it is possible to stably drive the gear reducer 1 while suppressing rattling during driving.

<2. Modification example>
Although the exemplary embodiments of the present invention have been described above, the present invention is not limited to the above embodiments. Hereinafter, various modifications will be described focusing on the differences from the above embodiments.

FIG. 4 is a vertical cross-sectional view of the gear reducer 1A according to the modified example cut by a plane including the rotating shaft 90A. The gear reducer 1A has a different structure in the vicinity of the slide bearing 80A from the gear reducer 1 according to the first embodiment. Since other configurations are the same as those of the gear reducer 1 according to the first embodiment, the description thereof will be omitted.

The gear transmission of FIG. 4 has two slide bearings 80A, that is, a first slide bearing 81A and a second slide bearing 82A. The second slide bearing 82A is arranged axially rearward of the second external gear 22A. Then, the second slide bearing 82A overlaps the housing 40A in the radial direction. Further, the end portion of the second slide bearing 82A at the rear in the axial direction faces a part of the second carrier 62A in the axial direction.

The first slide bearing 81A is arranged axially forward of the first external gear 21A. Further, the first slide bearing 81A has a first end portion 801A and a second end portion 802A. The first end portion 801A is an axially rear end portion of the first slide bearing 81A and faces the first external gear 21A in the axial direction. The second end portion 802A is an axially forward end portion of the first slide bearing 81A and faces the first carrier 61A in the axial direction. The radial width of the second end portion 802A is larger than the radial width of the first end portion 801A. As a result, the area of the surface of the second slide bearing 82A that receives the load in the axial direction can be increased. Even with such a configuration, it is possible to stably drive the gear reducer by suppressing rattling during driving while using the slide bearing 80A.

FIG. 5 is a vertical cross-sectional view of the gear reducer 1B according to another modification, which is cut by a plane including the rotating shaft 90B. The gear reducer 1B has a structure in the vicinity of the slide bearing 80B different from that of the gear reducer 1 according to the first embodiment. Since other configurations are the same as those of the gear reducer 1 according to the first embodiment, the description thereof will be omitted.

The gear transmission of FIG. 5 has two slide bearings 80B, that is, a first slide bearing 81B and a second slide bearing 82B. The first slide bearing 81B is arranged axially forward of the first external gear 21B. Further, the first slide bearing 81B has a first end portion 801B and a second end portion 802B. The first end portion 801B of the first slide bearing 81B is an axially rear end portion of the first slide bearing 81B and faces the first external gear 21B in the axial direction. The second end portion 802B of the first slide bearing 81B is an axially forward end portion of the first slide bearing 81B and faces the first carrier 61B in the axial direction. The radial width of the second end portion 802B is larger than the radial width of the first end portion 801B.

The second slide bearing 82B is arranged axially rearward of the second external gear 22B. Further, the second slide bearing 82B has a first end portion 801B and a second end portion 802B. The first end portion 801B of the second slide bearing 82B is an axially front end portion of the second slide bearing 82B and faces the second external gear 22B in the axial direction. The second end portion 802B of the second slide bearing 82B is an axially rear end portion of the second slide bearing 82B and faces the second carrier 62 in the axial direction. The radial width of the second end portion 802B is larger than the radial width of the first end portion 801B.

As described above, in the gear reducer 1B, the area of the surface of the first slide bearing 81B and the second slide bearing 82B that receives the load in the axial direction is large. Therefore, in the gear reducer 1B, the gear reducer can be driven more stably while using the slide bearing 80B.

Further, in the above embodiment, rolling bearings are used for the first bearing, the second bearing and the eccentric bearing. However, for each bearing, other types of bearings such as slide bearings and fluid bearings may be used instead of the rolling bearings.

Further, in the above embodiment, a speed reducer is shown as an example of a gear transmission. However, the gear transmission may be a gear speed increaser that increases the rotation speed. In this case, for example, power may be supplied to the second rotation unit of the speed reducer according to the above embodiment to output the rotation speed of the first rotation unit.

Further, in the above embodiment, the slide bearing is a separate member from the housing and the carrier. However, the sliding bearing may be a single member with the housing or carrier by making the housing or carrier made of resin.

Further, in the above embodiment, the number of external gears was two. However, the number of external gears may be one or three or more.

Further, the detailed shape of the gear reducer may be different from the shape shown in each figure of the present application. In addition, each element appearing in the above-described embodiment or modification may be appropriately combined as long as there is no contradiction.

The present invention can be used for gear transmissions.

1,1A, 1B Gear reducer 11 1st rotating part 12 2nd rotating part 13 Eccentric body 20 External gears 21,21A, 21B 1st external gears 22, 22A, 22B 2nd external gears 23 External teeth 24 External Interdental groove 25 Pin hole 26 Gap 30 Eccentric bearing 40, 40A, 40B Housing 50 Internal gear 51 Internal tooth 52 Internal interdental groove 60 Carrier 61, 61A, 61B 1st carrier 62, 62A, 62B 2nd carrier 63 Through hole 64 Press-fit hole 70 Carrier pin 80, 80A, 80B Sliding bearing 81, 81A, 81B 1st sliding bearing 82, 82A, 82B 2nd sliding bearing 83 Cylindrical part 84 Flange part 90 Rotating shaft 91 1st rotating shaft 92 2nd rotation Shaft 131 1st eccentric part 132 2nd eccentric part 141 1st bearing 142 2nd bearing 801,801A, 801B 1st end part 802,802A, 802B 2nd end part 841 1st gap 842 2nd gap

Claims (11)

An eccentric swing type gear transmission
The first rotating part that rotates at the first rotation speed around the rotating axis extending back and forth, and
A second rotating portion that is arranged behind the first rotating portion and rotates around the rotating shaft at a second rotating speed that is smaller than the first rotating speed.
An eccentric body arranged on the outer peripheral portion of the first rotating portion and rotating together with the first rotating portion,
An external gear that is arranged radially outside the eccentric body and has a plurality of external teeth on the outer circumference.
A plurality of eccentric bearings interposed between the eccentric body and the external gear,
A cylindrical housing arranged on the radial outer side of the external gear and
An internal gear that is arranged on the inner peripheral portion of the housing and has a plurality of internal teeth that mesh with the external teeth.
A plurality of carrier pins penetrating the external gear and extending in the axial direction,
With a carrier, at least a portion of which is arranged radially inside the housing and which connects and supports the plurality of carrier pins.
A plain bearing that is located between the carrier and the housing in the radial direction and rotatably supports the carrier with respect to the housing, at least in part.
Have,
The plain bearing is
A first end portion axially opposed to the external gear and
The second end that faces the carrier in the axial direction and
Have,
Width in the radial direction of the second end portion is much larger than the radial width of said first end,
The second end is axially opposed to the housing and
A gear transmission in which the outer peripheral surface of the second end portion is exposed when viewed from the outside in the radial direction . An eccentric swing type gear transmission
The first rotating part that rotates at the first rotation speed around the rotating axis extending back and forth, and
A second rotating portion that is arranged behind the first rotating portion and rotates around the rotating shaft at a second rotating speed that is smaller than the first rotating speed.
An eccentric body arranged on the outer peripheral portion of the first rotating portion and rotating together with the first rotating portion,
An external gear that is arranged radially outside the eccentric body and has a plurality of external teeth on the outer circumference.
A plurality of eccentric bearings interposed between the eccentric body and the external gear,
A cylindrical housing arranged on the radial outer side of the external gear and
An internal gear that is arranged on the inner peripheral portion of the housing and has a plurality of internal teeth that mesh with the external teeth.
A plurality of carrier pins penetrating the external gear and extending in the axial direction,
With a carrier, at least a portion of which is arranged radially inside the housing and which connects and supports the plurality of carrier pins.
A plain bearing that is located between the carrier and the housing in the radial direction and rotatably supports the carrier with respect to the housing, at least in part.
Have,
The plain bearing is
A first end portion axially opposed to the external gear and
The second end that faces the carrier in the axial direction and
Have,
The radial width of the second end is larger than the radial width of the first end.
The plain bearing is
A cylindrical part that extends in the axial direction and
A flange portion extending radially outward from the cylindrical portion and
Have,
The cylindrical portion has the first end portion and has the first end portion.
The second end is a gear transmission which is the flange. The gear transmission according to claim 1 or 2 .
A gear transmission in which at least a part of the second end portion, the carrier, and the housing overlap in the axial direction. The gear transmission according to claim 3 .
A first gap is interposed between the carrier and the second end portion.
A second gap is interposed between the second end portion and the housing.
A gear transmission in which the axial width of the first gap is larger than the axial width of the second gap. The gear transmission according to any one of claims 1 to 4 .
The plain bearing is a gear transmission arranged axially forward and axially rearward of the external gear. The gear transmission according to any one of claims 1 to 5 .
A gear transmission in which one end face in the axial direction of the housing and one end face in the axial direction of the carrier are arranged on the same plane. The gear transmission according to any one of claims 1 to 6 .
The internal gear and the housing are gear transmissions that are a single member. The gear transmission according to any one of claims 1 to 7 .
The plain bearing is a gear transmission made of resin. The gear transmission according to any one of claims 1 to 8 .
A gear transmission having an outer diameter of 50 mm or less. The gear transmission according to any one of claims 1 to 9 .
The plain bearing is a gear transmission that is a separate member from the housing and the carrier. The gear transmission according to any one of claims 1 to 10 .
The first rotation unit is an input unit that rotates at an input rotation speed.
The second rotation unit is a gear transmission which is an output unit that rotates at an output rotation speed smaller than the input rotation speed.

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