CN111623106A

CN111623106A - Eccentrically swinging transmission

Info

Publication number: CN111623106A
Application number: CN202010114961.0A
Authority: CN
Inventors: 坪根太平
Original assignee: Nidec Shimpo Corp
Current assignee: Nidec Shimpo Corp
Priority date: 2019-02-27
Filing date: 2020-02-25
Publication date: 2020-09-04
Also published as: JP2020139535A

Abstract

Provided is an eccentric oscillating type transmission having an eccentric body, an external gear, a bearing, and an internal gear. The eccentric body is mounted on a rotating shaft that rotates about a central axis. The external gear is disposed radially outward of the eccentric body and has a plurality of external teeth on an outer peripheral portion. The bearing is arranged between the eccentric body and the external gear. The internal gear is disposed radially outward of the external gear on the same axis as the central axis, and has a plurality of internal teeth on an inner circumferential portion thereof that mesh with the external teeth. The number of teeth of the outer teeth is different from the number of teeth of the inner teeth. The eccentric body has a part of a cylindrical surface centered on an eccentric axis extending in parallel with the central axis at a position offset from the central axis. The eccentric body has a notch portion that opens to the opposite side of the eccentric axis with respect to the central axis.

Description

Eccentrically swinging transmission

Technical Field

The present invention relates to an eccentric oscillating type transmission.

Background

An eccentric oscillating type transmission having an input shaft and an eccentric body coupled to the input shaft is known. A conventional eccentric oscillating type transmission is disclosed in, for example, japanese patent application laid-open No. 5-44791. The eccentric oscillating type transmission disclosed in japanese patent application laid-open No. 5-44791 includes an input shaft (101) and an eccentric body (103). A part of the outer periphery of the input shaft (101) is cut parallel to the axial direction to form a cut part (140) having a substantially D-shaped cross section. The eccentric body (103) has a hole (141) having the same shape as the cross-sectional shape of the input shaft (101) including the shape of the cut-out portion (140), and the input shaft (101) and the eccentric body (103) are positioned in the circumferential direction by fitting the hole (141).

It is considered that the eccentric rocking type transmission as described in japanese patent application laid-open No. 5-44791 can be coupled in a state where the eccentric body is positioned with respect to the input shaft. However, in the eccentrically oscillating transmission described in japanese patent application laid-open No. 5-44791, the eccentric member can be attached only from one side or the other side in the axial direction of the input shaft. Specifically, the axial distal end portion of the input shaft can only be inserted into the hole of the eccentric body, and the eccentric body can be mounted at a predetermined position by sliding along the axial direction of the input shaft, and the degree of freedom of assembly is low. Further, in the eccentrically oscillating transmission described in japanese patent application laid-open No. 5-44791, it is necessary to provide a cut portion in the input shaft in a range from the axial distal end portion of the input shaft to the predetermined position. Therefore, the radial dimension of the input shaft is reduced in a wide range, and it is difficult to sufficiently maintain the strength of the input shaft.

Disclosure of Invention

The purpose of the present invention is to provide an eccentrically oscillating transmission that can improve the degree of freedom of assembly and can ensure the strength of an input shaft.

According to an exemplary embodiment of the present invention, an eccentrically oscillating transmission having the following structure is provided. That is, the eccentric rocking type transmission includes an eccentric body, an external gear, a bearing, and an internal gear. The eccentric body is mounted on a rotating shaft that rotates about a central axis. The external gear is disposed radially outward of the eccentric body and has a plurality of external teeth on an outer peripheral portion. The bearing is arranged between the eccentric body and the external gear. The internal gear is disposed radially outward of the external gear on the same axis as the central axis, and has a plurality of internal teeth on an inner circumferential portion thereof that mesh with the external teeth. The number of teeth of the outer teeth is different from the number of teeth of the inner teeth. The eccentric body has a part of a cylindrical surface centered on an eccentric axis extending in parallel with the central axis at a position offset from the central axis. The eccentric body has a notch portion that opens to the opposite side of the eccentric axis with respect to the central axis.

According to an exemplary embodiment of the present invention, an eccentrically rocking type transmission is provided that can improve the degree of freedom of assembly and can secure the strength of an input shaft.

The above and other features, elements, steps, features and advantages of the present invention will be more clearly understood from the following detailed description of the preferred embodiments of the present invention taken in conjunction with the accompanying drawings.

Drawings

Fig. 1 is a longitudinal sectional view of an eccentric oscillating type transmission according to the present embodiment.

Fig. 2 is a sectional view taken along line II-II in fig. 1.

Fig. 3 is a sectional view taken along line III-III of fig. 1.

Fig. 4 is a view of the rotating shaft and the eccentric body as viewed in the axial direction.

Detailed Description

Hereinafter, exemplary embodiments of the present application will be described with reference to the drawings. In the present application, a direction parallel to the central axis of the transmission is referred to as an "axial direction", a direction perpendicular to the central axis of the transmission is referred to as a "radial direction", and a direction along an arc centered on the central axis of the transmission is referred to as a "circumferential direction". One side in the axial direction is referred to as "front side", and the other side in the axial direction is referred to as "rear side". However, the "parallel direction" also includes a substantially parallel direction. The vertical direction also includes a substantially vertical direction. In addition, "circumferential direction" also includes a direction along a substantially circular arc.

< 1. embodiment >

< 1-1. integral structure of eccentric oscillation type transmission

The overall structure of the eccentrically oscillating transmission 100 according to the embodiment will be described below with reference to fig. 1 to 4. Fig. 1 is a longitudinal sectional view of an eccentric oscillating type transmission 100 according to embodiment 1 of the present invention. Fig. 2 is a cross-sectional view of transmission 100 as viewed from a position II-II of fig. 1. Fig. 3 is a cross-sectional view of transmission 100 as viewed from the III-III position of fig. 1. However, in fig. 1 to 3, hatching is omitted for the sake of simplicity of the drawings.

The eccentrically oscillating transmission 100 converts a rotational motion at a 1 st rotational speed (input rotational speed) into a rotational motion at a 2 nd rotational speed (output rotational speed) lower than the 1 st rotational speed by an internal planetary reduction mechanism. The eccentric swing type transmission 100 is used for a joint portion of a small robot such as a service robot that performs work in cooperation with a human being, for example. However, the transmission having the same structure may be used for other applications such as a large industrial robot, a machine tool, an X-Y table, a material cutting device, a conveyor line, a turntable, and a rolling roll.

As shown in fig. 1, an eccentrically oscillating transmission 100 according to the present embodiment mainly includes a housing 10, a rotary shaft 20, an eccentric body 30, an external gear 40, a bearing 50, an internal gear 60, a carrier pin 70, and an output rotary member 80.

The case 10 is a cylindrical member extending in the axial direction around the center axis C of the eccentric oscillating type transmission 100. The housing 10 covers the rotary shaft 20, the eccentric body 30, the external gear 40, the bearing 50, the internal gear 60, the carrier pin 70, and the output rotary part 80 from the outside in the radial direction.

The rotary shaft 20 is a substantially cylindrical member extending in the axial direction about the center axis C of the eccentric oscillating type transmission 100. The rotary shaft 20 is connected to a motor as a drive source directly or via another power transmission mechanism. Alternatively, the rotary shaft 20 may be an output shaft of a motor as a drive source. When the motor is driven, the rotary shaft 20 is rotated at the 1 st rotation speed centering on the central axis C by the power supplied from the motor. The rotating shaft 20 is disposed in the axial center portion of the eccentric oscillating type transmission 100.

The eccentric member 30 rotates together with the rotary shaft 20 at the same rotational speed as the rotary shaft 20. The eccentric body 30 is attached to an axial middle portion of the rotary shaft 20. The eccentric body 30 has a part of a cylindrical surface centered on an eccentric axis D extending in parallel with the central axis C at a position offset from the central axis C. Therefore, the distance from the center axis C to the outer peripheral surface of the eccentric body 30 differs depending on the position in the circumferential direction. When the rotary shaft 20 rotates about the center axis C, the position of the eccentric axis D of the eccentric body 30 rotates about the center axis C. At this time, the position of the eccentric body 30 also rotates about the center axis C.

As shown in fig. 1, in the present embodiment, 2 eccentric bodies 30 are attached to the middle portion in the axial direction of the rotary shaft 20. Here, the position of the eccentric axis D of one eccentric body 30 of the 2 eccentric bodies 30 and the position of the eccentric axis D of the other eccentric body 30 of the 2 eccentric bodies 30 are arranged rotationally symmetrically to each other as viewed in the axial direction. Thus, in the present embodiment, the center of gravity of the entire plurality of eccentric bodies 30 is always positioned on the center axis C. Therefore, the unbalance of the eccentric body 30 can be suppressed.

The external gear 40 is disposed radially outward of each eccentric body 30. That is, the transmission 100 of the present embodiment has 2 external-teeth gears 40. A bearing 50 is provided between the eccentric body 30 and the external gear 40. The external gear 40 is supported by a bearing 50 so as to be rotatable about the eccentric axis D. As shown in fig. 2, a plurality of external teeth 41 are provided on the outer peripheral portion of the external gear 40. Each outer tooth 41 extends radially outward. Further, an inter-outer-tooth groove 42 that is recessed radially inward is provided between the outer teeth 41 adjacent in the circumferential direction. The outer teeth 41 and the inter-outer-tooth grooves 42 are alternately arranged in the circumferential direction around the eccentric axis D.

As shown in fig. 2, the external gear 40 has a plurality of (10 in the present embodiment) through holes 43. Each through hole 43 axially penetrates the external gear 40. The plurality of through holes 43 are arranged at equal intervals in the circumferential direction around the eccentric axis D.

The internal gear 60 is an annular member surrounding the radially outer side of the external gear 40. The internal gear 60 is disposed on the same axis as the center axis C. In the present embodiment, the outer peripheral surface of the internal gear 60 is fixed to the inner peripheral surface of the housing 10. As shown in fig. 2, a plurality of internal teeth 61 are provided on an inner peripheral portion of the internal gear 60. Each internal tooth 61 extends radially inward. Further, inter-tooth grooves 62 that are recessed radially outward are provided between the inner teeth 61 adjacent in the circumferential direction. The internal teeth 61 and the inter-tooth grooves 62 are alternately arranged in the circumferential direction around the center axis C.

As shown in fig. 2, the external gear 40 and the internal gear 60 can partially mesh. Specifically, the external teeth 41 are partially fitted into the inter-internal-tooth grooves 62 of the internal gear 60, and the external teeth 41 mesh with the internal teeth 61, whereby the external gear 40 and the internal gear 60 rotate relative to each other.

When the rotary shaft 20 rotates about the center axis C, the external gear 40 revolves around the center axis C together with the eccentric axis D. At this time, the external gear 40 revolves while changing the meshing position of the external teeth 41 of the external gear 40 and the internal teeth 61 of the internal gear 60 in the circumferential direction. Here, the number of the internal teeth 61 is different from the number of the external teeth 41. Specifically, in the present embodiment, the number of internal teeth 61 of the internal gear 60 is larger than the number of external teeth 41 of the external gear 40. Therefore, every 1 revolution of the external gear 40, the positions of the external teeth 41 meshing with the internal teeth 61 at the same position of the internal gear 60 are shifted by the tooth number difference. Thereby, the external gear 40 rotates about the eccentric axis D at the 2 nd rotation speed lower than the 1 st rotation speed in the direction opposite to the rotation direction of the rotary shaft 20. Accordingly, the position of the through hole 43 of the external gear 40 also rotates at the 2 nd rotation speed. When the eccentric rocking type transmission 100 operates, the external gear 40 performs a rotational motion combining the revolution and the rotation.

The plurality of carrier pins 70 are substantially columnar members that penetrate the external gear 40 and extend in the axial direction. As shown in fig. 2 and 3, the plurality of carrier pins 70 are arranged in a ring shape around the center axis C. Each carrier pin 70 is inserted into the through hole 43 of the external gear 40. Thus, when the external gear 40 rotates at the 2 nd rotation speed after the reduction, the plurality of carrier pins 70 are pressed by the inner peripheral surface of the through-hole 43 of the external gear 40 and rotate at the 2 nd rotation speed around the center axis C.

Returning to fig. 1. The output rotation portion 80 includes an annular front bearing member 81 and an annular rear bearing member 82. The front receiving member 81 is disposed on the axially forward side of the external gear 40. The front bearing member 81 is supported to be rotatable with respect to the rotation shaft 20. A bearing may be provided between the front bearing member 81 and the rotary shaft 20. Further, a bearing may be provided between the front carrier member 81 and the internal gear 60.

The rear carrier member 82 is disposed on the axial rear side of the external gear 40. The rear bearing member 82 is rotatable with respect to the rotation shaft 20. A bearing may be provided between the rear bearing 82 and the rotary shaft 20. Further, a bearing may be provided between the rear carrier 82 and the internal gear 60.

The axial front end of each bearing pin 70 is fixed to the front bearing member 81. An axially rearward end of each carrier pin 70 is fixed to the rear carrier member 82. Therefore, when the plurality of carrier pins 70 rotate about the central axis C at the 2 nd rotation speed, the front carrier member 81 and the rear carrier member 82 also rotate about the central axis C at the 2 nd rotation speed. The fixing method of the carrier pin 70 to the front carrier member 81 and the rear carrier member 82 is, for example, press fitting.

The output rotating portion 80 is connected to a member to be driven directly or via another power transmission mechanism. With such a configuration, in the eccentrically rocking type transmission 100 according to the present embodiment, the rotation input to the rotary shaft 20 can be greatly decelerated by the internal planetary type deceleration mechanism, and the decelerated rotation can be output from the output rotating portion 80.

In the above-described eccentrically-swinging transmission, conventionally, when the eccentric body is assembled to the rotating shaft, only the distal end portion of the rotating shaft is inserted into the hole of the eccentric body, and the eccentric body is mounted at a predetermined position by sliding along the axial direction of the rotating shaft, and thus the degree of freedom of assembly is low. Further, conventionally, in order to position (stop) the position of the eccentric body with respect to the rotating shaft in the circumferential direction, a cut portion is provided in the rotating shaft, but in the case where only the eccentric body can be assembled to the rotating shaft in the above-described method, it is necessary to provide the cut portion in a range from the axial tip of the rotating shaft to the predetermined position. Therefore, the radial dimension of the rotating shaft is reduced in a wide range, and it is difficult to sufficiently maintain the strength of the rotating shaft.

In this regard, the eccentric rocking type transmission 100 of the present embodiment has a unique configuration for improving the degree of freedom in assembling the eccentric body 30 to the rotary shaft 20 and ensuring the strength of the rotary shaft 20. The specific structure will be described in detail below.

< 1-2. Structure of eccentric body

First, the structure of the eccentric body 30 will be described in detail mainly with reference to fig. 4. Fig. 4 is a view of rotating shaft 20 and eccentric body 30 as viewed in the axial direction.

The eccentric body 30 has a certain thickness in the axial direction (see fig. 1). Eccentric body 30 is made of a resin material. When viewed in the axial direction, the eccentric member 30 has a notch portion 30a, a 1 st pair of sides 30b, a 3 rd side 30c, and an arc surface 30 e.

The cutout portion 30a opens to the opposite side of the eccentric axis D with the center axis C therebetween when viewed in the axial direction. The inner surface of the cutout portion 30a is substantially rectangular when viewed in the axial direction. The 1 st pair of sides 30b is a pair (set) of opposing sides of the above-described rectangular shape of the cutout portion 30a when viewed in the axial direction. The pair of 1 st pair of sides 30b are parallel to each other.

The 3 rd side 30c is a side connecting the pair of 1 st pair of sides 30b to each other when viewed in the axial direction. The 3 rd side 30c is perpendicular to the 1 st opposite side 30b when viewed in the axial direction. As shown in fig. 4, the connecting portion between the 1 st pair of sides 30b and the 3 rd side 30c has an R-shape (circular arc shape) when viewed in the axial direction.

The arc surface 30e is a part of a cylindrical surface centered on the eccentric axis D. The arcuate surface 30e is a region of the outer peripheral surface of the eccentric member 30 on the opposite side of the opening with respect to the center axis C when viewed in the axial direction. The arcuate surface 30e has an arcuate shape (a part of a cylinder) continuous in the circumferential direction when viewed in the axial direction.

< 1-3. Structure of detail of rotating shaft

Next, the detailed structure of the rotary shaft 20 according to the present embodiment will be described with reference to fig. 4.

As shown in fig. 4, the rotating shaft 20 has a 2 nd pair of sides 20a at a portion of the outer circumferential surface where the eccentric body 30 is fixed. Specifically, 2 portions of the outer peripheral surface of the rotary shaft 20 are cut in a D-shape when viewed in the axial direction, and a pair of 2 nd opposite sides 20a are provided. The pair of 2 nd opposite sides 20a are respectively parallel to the central axis C. Thus, the pair of 2 nd pair edges 20a are parallel to each other. The pair of 2 nd opposite sides 20a are disposed line-symmetrically with respect to a virtual straight line L passing through the central axis C when viewed in the axial direction.

As shown in fig. 1, 2 eccentric bodies 30 are attached to the rotary shaft 20 in a posture of being inverted 180 ° from each other with respect to the center axis C when viewed in the axial direction. That is, the cutout portions 30a of the 2 eccentric bodies 30 are opened in directions opposite to each other when viewed in the axial direction. However, in the present embodiment, the 2 nd pair of sides 20a provided at the portion where the eccentric body 30 arranged on the axially forward side among the 2 eccentric bodies 30 is fixed and the 2 nd pair of sides 20a provided at the portion where the eccentric body 30 arranged on the axially rearward side is fixed are the same plane. As shown in fig. 4, the pair of 2 nd pairs 20a can be in surface contact with the pair of 1 st pairs 30 b.

In the eccentric rocking type transmission 100 having the above-described configuration, when the eccentric body 30 is assembled to the rotary shaft 20, first, the eccentric body 30 is disposed radially outward of the part of the rotary shaft 20 where the 2 nd opposite side 20a is provided. Then, the pair of 1 st facing sides 30b of the eccentric body 30 is brought into contact with the 2 nd facing side 20a of the rotating shaft 20 and slid radially inward so that the rotating shaft 20 is positioned between the pair of 1 st facing sides 30b of the eccentric body 30. Thus, the outer peripheral surface of the rotary shaft 20 is in contact with the 3 rd side 30c of the eccentric member 30. As described above, by fitting the notch portion 30a of the eccentric body 30 into the rotary shaft 20 from the radial outside, the eccentric body 30 can be easily attached to the rotary shaft 20 from the radial outside. Then, the bearing 50 is inserted from the distal end portion of the rotating shaft 20, and the bearing 50 is assembled to the radially outer side of the eccentric body 30, so that the eccentric body 30 cannot be detached from the rotating shaft 20.

Further, according to the above configuration, since the 2 nd pair of sides 20a are provided only at the axial portion of the outer peripheral surface of the rotary shaft 20 to which the eccentric body 30 is fixed, the radial dimension of the rotary shaft 20 can be secured in a large area, and as a result, the strength of the rotary shaft 20 can be maintained.

< 1-4. summary >

As described above, the eccentric rocking type transmission 100 of the present embodiment includes the eccentric body 30, the external gear 40, the bearing 50, and the internal gear 60. The eccentric body 30 has an arc surface 30e, and the arc surface 30e is a part of a cylindrical surface having an eccentric axis D as a center, and the eccentric axis D extends in parallel with the center axis C at a position offset from the center axis C. The eccentric body 30 has a notch 30a, and the notch 30a opens to the opposite side of the eccentric axis D with the center axis C therebetween. Thus, by fitting the notch 30a into the rotary shaft 20, the eccentric body 30 can be attached to the rotary shaft 20 from the radially outer side. Therefore, the degree of freedom in assembling the eccentric rocking type transmission 100 is improved. Further, when the eccentric body 30 is assembled to the rotary shaft 20, the strength of the rotary shaft 20 can be maintained without sacrificing the radial dimension of the rotary shaft 20.

In the eccentric rocking type transmission 100 according to the present embodiment, the notch portion 30a of the eccentric member 30 has a pair of the 1 st pair of sides 30 b. In addition, the rotating shaft 20 has a set of 2 nd pair of sides 20 a. Thus, the mounting accuracy of the eccentric body 30 to the rotary shaft 20 can be improved by bringing the 1 st pair of sides 30b into surface contact with the 2 nd pair of sides 20 a.

In the eccentric rocking type transmission 100 of the present embodiment, the pair of 1 st facing sides 30b are parallel to each other, and the pair of 2 nd facing sides 20a are parallel to each other. This facilitates the production of eccentric body 30 and the processing of rotary shaft 20.

In the eccentric rocking type transmission 100 according to the present embodiment, the eccentric member 30 has the 3 rd side 30 c. This allows eccentric body 30 to have a simple shape, and facilitates production of eccentric body 30.

In the eccentric rocking type transmission 100 according to the present embodiment, the 3 rd side 30c is perpendicular to the 1 st opposite side 30 b. Therefore, eccentric body 30 has a simpler shape, and manufacturing eccentric body 30 is facilitated.

In the eccentric rocking type transmission 100 according to the present embodiment, the connecting portion between the 1 st pair of sides 30b and the 3 rd side 30c has an R-shape. Thus, after the components of the eccentrically swinging transmission 100 are assembled, it is possible to reduce the stress from being locally concentrated on the connecting portion between the 1 st pair of sides 30b and the 3 rd side 30 c.

In the eccentric rocking type transmission 100 according to the present embodiment, the eccentric member 30 is made of a resin material. Thus, the eccentric body 30 can be molded by a pair of molds that open and close in the direction perpendicular to the axial direction. Therefore, it is not necessary to provide the outer peripheral surface of the eccentric body 30 with a draft inclined with respect to the axial direction. As a result, the tolerance can be kept small, and the components of the eccentric rocking type transmission 100 can be assembled with high accuracy.

In the eccentric rocking type transmission 100 according to the present embodiment, the 2 nd pair of sides 20a are provided only at the axial portion of the outer peripheral surface of the rotary shaft 20 to which the eccentric body 30 is fixed. This enables the position of the eccentric body 30 in the axial direction and the circumferential direction with respect to the rotary shaft 20 to be positioned by the 2 nd pair of sides 20 a.

In the eccentric rocking type transmission 100 according to the present embodiment, a region of the outer peripheral surface of the eccentric body 30 on the opposite side of the opening with the center axis C therebetween has a continuous arc shape (arc surface 30 e). This presses the outer peripheral surface of the arc surface 30e of the eccentric body 30, and the external teeth 41 of the external gear 40 and the internal teeth 61 of the internal gear 60 are thereby favorably meshed with each other. Conversely, since the side of the eccentric body 30 where the notch portion 30a is present is a region where a load is not easily applied, even if a gap is present between the inner surface of the notch portion 30a of the eccentric body 30 and the outer peripheral surface of the rotary shaft 20, the rotational performance of the eccentrically oscillating transmission 100 is not easily affected.

< 2. modification example >

In the above embodiment, the eccentric body 30 is attached to the rotary shaft 20 from the radially outer side, and then the bearing 50 is disposed on the radially outer side of the eccentric body 30, whereby the eccentric body 30 is attached to the rotary shaft 20 so as not to fall off. However, the present invention is not limited to this, and instead, for example, an adhesive may be applied to a contact portion between the eccentric body 30 and the rotating shaft 20, so that the eccentric body 30 cannot be detached from the rotating shaft 20.

In the above embodiment, the 2 nd pair of sides 20a provided at the portion where the eccentric body 30 arranged on the axially forward side is fixed and the 2 nd pair of sides 20a provided at the portion where the eccentric body 30 arranged on the axially rearward side is fixed in the outer peripheral surface of the rotary shaft 20 are the same plane. However, instead of this, the 2 nd pair of sides 20a provided at the portion where the eccentric body 30 arranged on the axially forward side is fixed and the 2 nd pair of sides 20a provided at the portion where the eccentric body 30 arranged on the axially rearward side is fixed may be formed as separate (discontinuous) planes on the outer peripheral surface of the rotary shaft 20.

The eccentric member may not have the 1 st pair of sides, the rotating shaft may not have the 2 nd pair of sides, and the eccentric member may be made of an elastically deformable material. In this case, the eccentric body may have a cut having a substantially circular shape when viewed in the axial direction. In this case, the vicinity of the opening of the notch of the eccentric body may be pushed open to fit the eccentric body into the outer peripheral portion of the rotating shaft from the radially outer side of the rotating shaft.

The eccentric body 30 may not necessarily be made of resin. Instead, the eccentric body 30 may be made of metal.

In the above embodiment, the internal gear 60 is an annular member, but is not limited thereto. Alternatively, the external shape of the internal gear when viewed in the axial direction may be rectangular. The internal teeth 61 provided on the inner peripheral portion of the internal gear 60 may not necessarily be a single member with the internal gear 60, but instead, a pin groove into which a pin is fitted may be provided on the inner peripheral portion of the internal gear, and a pin as internal teeth may be fitted into the pin groove.

The eccentric rocking type transmission 100 of the above embodiment has 2 eccentric bodies 30 at the front and rear in the axial direction. However, the present invention is not limited to this, and instead, the eccentric rocking type transmission 100 may have 1 or 3 or more eccentric bodies 30 arranged in the axial direction.

In addition, the respective elements appearing in the above-described embodiment and the modified examples may be appropriately combined within a range in which no contradiction occurs.

The present application can be applied to, for example, an eccentric oscillation type transmission.

Claims

1. An eccentrically oscillating transmission comprising:

an eccentric body mounted on a rotating shaft that rotates about a central axis;

an external gear disposed radially outward of the eccentric body and having a plurality of external teeth on an outer peripheral portion thereof;

a bearing interposed between the eccentric body and the external gear; and

an internal gear disposed radially outward of the external gear and on the same axis as the central axis, the internal gear having a plurality of internal teeth on an inner circumferential portion thereof that mesh with the external teeth,

the number of teeth of the outer teeth is different from the number of teeth of the inner teeth,

the eccentric body has a part of a cylindrical surface centered on an eccentric axis extending in parallel with the central axis at a position offset from the central axis,

it is characterized in that the preparation method is characterized in that,

the eccentric body has a cutout portion that opens to a side opposite to the eccentric axis with the central axis therebetween.

2. The eccentrically swinging transmission according to claim 1,

the cut-out portion has a set of opposite sides 1,

the rotating shaft has a set of 2 nd pairs of edges capable of contacting the 1 st pair of edges.

3. The eccentrically swinging transmission according to claim 2,

the set of 1 st pair of edges are parallel to each other and the set of 2 nd pair of edges are parallel to each other.

4. The eccentrically oscillating transmission according to claim 2 or 3,

the eccentric body has a 3 rd side connecting the set of 1 st pair of sides to each other.

5. The eccentrically swinging transmission according to claim 4,

the set of 1 st pair of edges are parallel to each other, the set of 2 nd pair of edges are parallel to each other,

the 3 rd side is perpendicular to the 1 st opposite side.

6. The eccentrically swinging transmission according to claim 4,

the connecting part of the 1 st opposite side and the 3 rd side is in an R shape.

7. The eccentrically swinging transmission according to any one of claims 1, 2, 3, 5, and 6,

the eccentric body is made of a resin material.

8. The eccentrically oscillating transmission according to any one of claims 2, 3, 5 and 6,

the 2 nd pair of sides are provided only at a portion of the outer peripheral surface of the rotating shaft to which the eccentric body is fixed.

9. The eccentrically swinging transmission according to any one of claims 1, 2, 3, 5, and 6,

an area of the outer peripheral surface of the eccentric body on the opposite side of the central axis to the opening side is continuous in a circular arc shape.