WO2019188673A1

WO2019188673A1 - Transmission

Info

Publication number: WO2019188673A1
Application number: PCT/JP2019/011744
Authority: WO
Inventors: 太平坪根; 浩司杉本
Original assignee: 日本電産シンポ株式会社
Priority date: 2018-03-30
Filing date: 2019-03-20
Publication date: 2019-10-03
Also published as: JP7283683B2; JPWO2019188673A1

Abstract

This transmission has: an external gear having a plurality of outer teeth on the outer circumference thereof; and a plurality of carrier pins. The carrier pins extend in the axial direction, through through-holes provided in the external gear. The external gear has an external gear main body and a protective film that covers at least part of the inner circumferential surface of the through-holes. The protective film has a higher abrasion resistance than the external gear main body. During transmission drive, the through-holes and the carrier pins have repeated relative movement. During this time, the carrier pins are in contact with the protective film having high abrasion resistance. As a result, the inner circumferential surface of the through-holes can suppress abrasion resulting from contact with the carrier pins.

Description

transmission

The present invention relates to a transmission.

Conventionally, an eccentric rocking type (inscribed planetary type) speed reducer is known. The eccentric oscillating type speed reducer has an internal gear and an external gear disposed inside the internal gear. The external gear swings along the inner surface of the internal gear while meshing with the internal gear. Such an eccentric oscillating speed reducer is small and can provide a high reduction ratio. A conventional eccentric oscillating speed reducer is described in, for example, Japanese Patent Application Laid-Open No. 2018-17362.

JP 2018-17362 A

In the transmission of Japanese Patent Application Laid-Open No. 2018-17362, a plurality of pin holes are provided in the external gear. A carrier pin is inserted into each pin hole. When driving the speed reducer, the pin hole and the carrier pin repeat relative movement while the carrier pin is in contact with the inner peripheral surface of the pin hole. For this reason, when the wear resistance of the external gear is insufficient, the inner peripheral surface of the pin hole is worn by contact with the carrier pin when the reduction gear is used for a long time.

An object of the present invention is to provide a structure capable of suppressing wear of an inner peripheral surface of a through hole of an external gear due to contact with a carrier pin in an eccentric oscillation type transmission.

In order to solve the above problems, the present invention is an eccentric rocking type transmission, wherein a first rotating portion that rotates at a first rotation speed about a central axis, and rotates together with the first rotating portion, A disc-shaped eccentric body in which the distance from the central axis to the outer peripheral surface varies depending on the position in the circumferential direction, a disc-shaped external gear having a circular hole into which the eccentric body fits in the center, and the diameter of the external gear A cylindrical internal gear positioned on the outer side in the direction and coaxially with the central axis, a plurality of carrier pins extending in the axial direction through a plurality of through holes provided in the external gear, and the plurality of the plurality of carrier pins A second rotating part fixed to a carrier pin, the external gear has a plurality of external teeth on the outer peripheral part, and the internal gear has a plurality of internal teeth on the inner peripheral part, On the extended line of the long diameter of the eccentric body, a part of the plurality of external teeth and a part of the plurality of internal teeth, The external gear has an external gear main body and a protective film covering at least a part of the inner peripheral surface of the through hole, and the protective film is more resistant than the external gear main body. It is a transmission with high wear resistance.

According to the present invention, it is possible to prevent the inner peripheral surface of the through hole of the external gear from being worn by contact with the carrier pin.

FIG. 1 is a longitudinal sectional view of the speed reducer. FIG. 2 is an exploded perspective view of the speed reducer. FIG. 3 is a cross-sectional view of the speed reducer. FIG. 4 is a partial cross-sectional view of the external gear and the carrier pin. FIG. 5 is a partial cross-sectional view of the external gear and the carrier pin.

Hereinafter, exemplary embodiments of the present invention will be described with reference to the drawings. In the present invention, a direction parallel to the central axis of the transmission is referred to as an “axial direction”, a direction orthogonal to the central axis is referred to as a “radial direction”, and a direction along an arc centered on the central axis is referred to as a “circumferential direction”. Each is called. However, the above “parallel direction” includes a substantially parallel direction. In addition, the above-mentioned “orthogonal direction” includes a substantially orthogonal direction.

<1. Overall configuration of transmission>
FIG. 1 is a longitudinal sectional view of a reduction gear 1 that is an example of a transmission. FIG. 2 is an exploded perspective view of the speed reducer 1. FIG. 3 is a cross-sectional view of the speed reducer 1 viewed from the position III-III in FIG. In FIG. 3, hatching is omitted to avoid complication of the drawing.

The speed reducer 1 is an eccentric oscillating type (inscribed) that converts rotational motion at a first rotational speed (input rotational speed) into rotational motion at a second rotational speed (output rotational speed) that is lower than the first rotational speed. It is a planetary gear reducer. The speed reducer 1 is used, for example, in a joint of a small robot such as a service robot that works in cooperation with a person. However, a speed reducer having an equivalent structure may be used for other uses such as a large industrial robot, a machine tool, an XY table, a material cutting device, a conveyor line, a turntable, and a rolling roller.

As shown in FIG. 1, the speed reducer 1 of the present embodiment includes a first rotating unit 10, two eccentric bodies 20, two external gears 30, an internal gear 40, a plurality of carrier pins 50, and a second. A rotating unit 60 is provided.

The first rotating unit 10 is a columnar member extending along the central axis 9. As conceptually shown in FIG. 1, the first rotating unit 10 is connected to a motor, which is a drive source, directly or via another power transmission mechanism. When the motor is driven, the first rotating part 10 rotates at the first rotation speed around the central axis 9 by the power supplied from the motor. That is, in this embodiment, the 1st rotation part 10 becomes an input part.

The eccentric body 20 is a member that rotates together with the first rotating unit 10. The two eccentric bodies 20 are each fixed to the outer peripheral surface of the first rotating unit 10. However, the 1st rotation part 10 and the two eccentric bodies 20 may be a single member. Each of the two eccentric bodies 20 has a cylindrical outer peripheral surface centering on an eccentric shaft 91 extending parallel to the central axis 9 at a position deviated from the central axis 9. Therefore, the distance from the central axis 9 to the outer peripheral surface of the eccentric body 20 differs depending on the position in the circumferential direction. When the first rotating unit 10 rotates about the central axis 9, the positions of the two eccentric bodies 20 rotate about the central axis 9. At this time, the eccentric shaft 91 of each eccentric body 20 also rotates about the central axis 9.

In the present embodiment, the position of the eccentric shaft 91 of one eccentric body 20 and the position of the eccentric shaft 91 of the other eccentric body 20 are separated from each other by 180 ° with respect to the central axis 9. In this way, the position of the center of gravity as a whole of the two eccentric bodies 20 is always located on the central axis 9. Therefore, the fluctuation of the center of gravity due to the rotation of the eccentric body 20 can be suppressed.

The two external gears 30 are each arranged on the radially outer side of the eccentric body 20. The external gear 30 is a disk-shaped member and has a circular hole 34 in the center thereof. The eccentric body 20 is fitted in the circular hole 34. The external gear 30 is supported so as to be rotatable around the eccentric shaft 91 around the eccentric body 20. Lubricating oil (not shown) is interposed between the outer peripheral surface of the eccentric body 20 and the inner peripheral surface of the external gear 30. As a result, the eccentric body 20 and the external gear 30 rotate relative to each other without using a mechanical element such as a roller bearing. Thus, by omitting the mechanical element between the eccentric body 20 and the external gear 30, the reduction gear 1 can be easily downsized. For example, grease is used as the lubricating oil. However, a bearing such as a roller bearing may be interposed between the eccentric body 20 and the external gear 30.

As shown in FIG. 3, a plurality of external teeth 31 are provided on the outer peripheral portion of the external gear 30. Each of the plurality of external teeth 31 protrudes outward in the radial direction. In addition, an inter-external tooth groove 32 that is recessed radially inward is provided between adjacent external teeth 31. The external teeth 31 and the inter-external teeth grooves 32 are alternately arranged in the circumferential direction around the eccentric shaft 91.

Further, as shown in FIGS. 1 and 3, each of the two external gears 30 has a plurality of (10 in the example of FIG. 3) through-holes 33. Each through-hole 33 penetrates the external gear 30 in the axial direction. The plurality of through holes 33 are arranged at equal intervals in the circumferential direction around the eccentric shaft 91.

The internal gear 40 is a cylindrical member that surrounds the radially outer side of the two external gears 30. The internal gear 40 is arranged coaxially with the central shaft 9. As shown in FIG. 3, a plurality of internal teeth 41 are provided on the inner peripheral portion of the internal gear 40. Each of the plurality of internal teeth 41 protrudes radially inward. Further, between the adjacent internal teeth 41, an internal tooth groove 42 that is recessed outward in the radial direction is provided. The inner teeth 41 and the inner inter-tooth grooves 42 are alternately arranged in the circumferential direction around the central axis 9.

Part of the plurality of external teeth 31 of the external gear 30 and part of the plurality of internal teeth 41 of the internal gear 40 mesh with each other. Specifically, a part of the plurality of external teeth 31 and a part of the plurality of internal teeth 41 mesh with each other on the extended line of the long diameter of the eccentric body 20. At the meshing position, the external teeth 31 of the external gear 30 are fitted into the inter-tooth grooves 42 of the internal gear 40 or the internal teeth 41 of the internal gear 40 are external teeth of the external gear 30. It fits in the inter-groove 32.

When the first rotating unit 10 rotates about the central axis 9, the external gear 30 revolves around the central axis 9 together with the eccentric shaft 91. Further, when the external teeth 31 of the external gear 30 and the internal teeth 41 of the internal gear 40 mesh with each other, the external gear 30 rotates. Here, the number of internal teeth 41 included in the internal gear 40 is larger than the number of external teeth 31 included in the external gear 30. For this reason, for each revolution of the external gear 30, the position of the external teeth 31 that mesh with the internal teeth 41 at the same position of the internal gear 40 is shifted. Thereby, the external gear 30 rotates in the direction opposite to the rotation direction of the first rotation unit 10 at the second rotation speed lower than the first rotation speed. Therefore, the position of the through hole 33 of the external gear 30 also rotates at the second rotational speed. During the operation of the speed reducer 1, the two external gears 30 each perform a rotational motion combining such revolution and rotation.

When the number of external teeth 31 of the external gear 30 is N and the number of internal teeth 41 of the internal gear 40 is M, the reduction ratio P of the reduction gear 1 is P = (first rotation speed) / ( Second rotation speed) = N / (MN). In the example of FIG. 3, since N = 29 and M = 30, the reduction ratio P in this example is P = 29. That is, the second rotational speed is 1/29 times the first rotational speed. However, the number N of the outer teeth 31 and the number M of the inner teeth 41 may be other values. Further, the number N of outer teeth 31 may be larger than the number M of inner teeth 41.

In the present embodiment, the internal gear 40 also serves as a casing that forms the outer wall of the speed reducer 1. In this way, it is not necessary to provide the internal gear 40 separately from the casing. Thereby, the reduction gear 1 can be more easily downsized.

The plurality of carrier pins 50 are columnar members that penetrate the two external gears 30 and extend in the axial direction. As a material of the carrier pin 50, for example, a metal such as iron or stainless steel is used. The plurality of carrier pins 50 are arranged in an annular shape around the central axis 9. Each carrier pin 50 is inserted into the through hole 33 of the two external gears 30. As shown in FIG. 3, a gap is interposed between the annular surface constituting the through hole 33 of the external gear 30 and the outer peripheral surface of the carrier pin 50. When the two external gears 30 rotate at the second rotational speed after deceleration, the plurality of carrier pins 50 are also rotated at the second rotational speed around the central axis 9 by being pushed by the external gear 30. To do.

The second rotating unit 60 includes an annular front carrier member 61 and an annular rear carrier member 62. The front carrier member 61 is disposed on one side in the axial direction with respect to the two external gears 30. A first bearing 72 is interposed between the first rotating part 10 and the front carrier member 61.
Further, a second bearing 73 is interposed between the front carrier member 61 and the internal gear 40. The rear carrier member 62 is disposed on the other side in the axial direction from the two external gears 30. A third bearing 74 is interposed between the first rotating unit 10 and the rear carrier member 62. A fourth bearing 75 is interposed between the rear carrier member 62 and the internal gear 40. As the first bearing 72 and the third bearing 74, for example, ball bearings are used. For the second bearing 73 and the fourth bearing 75, for example, a sliding bearing made of a resin such as polyacetal is used.

One end of each carrier pin 50 in the axial direction is fixed to the front carrier member 61. The other end of each carrier pin 50 in the axial direction is fixed to the rear carrier member 62. For this reason, when the plurality of carrier pins 50 rotate at the second rotational speed around the central axis 9, the front carrier member 61 and the rear carrier member 62 also rotate at the second rotational speed around the central axis 9.

The second rotating unit 60 is connected to a member to be driven directly or via another power transmission mechanism. That is, in this embodiment, the 2nd rotation part 60 becomes an output part.

<2. About measures to wear through holes>
Next, a measure against wear of the through hole 33 of the external gear 30 described above will be described. FIG. 4 is a partial cross-sectional view of the external gear 30 and the carrier pin 50. As shown in FIG. 4, the external gear 30 includes an external gear main body 70 and a protective film 80 provided on the inner peripheral surface of the through hole 33.

The external gear main body 70 is a member constituting most of the external gear 30. The external gear main body 70 has a disk-shaped outer shape including the plurality of external teeth 31, the plurality of inter-tooth spaces 32, the plurality of through holes 33, and the circular holes 34 described above. As the material of the external gear main body 70, for example, a resin having lower wear resistance than the carrier pin 50 is used. By using resin, the speed reducer 1 can be reduced in weight compared to the case of using metal. Further, the use of the resin facilitates the reduction of the speed reducer 1 and reduces the manufacturing cost.

The protective film 80 is provided on the inner peripheral surface of each of the plurality of through holes 33. As the material of the protective film 80, a metal having higher wear resistance than that of the external gear body 70 is used. For example, the protective film 80 is formed on the inner peripheral surface of the through hole 33 by metal plating. However, instead of metal plating, a cylindrical protective member may be press-fitted into the through-hole 33, and the protective member after press-fitting may be used as the protective film 80. Further, instead of press-fitting, a cylindrical protective member may be fixed to the inner peripheral surface of the through hole 33 with an adhesive.

When driving the speed reducer 1, the carrier pin 50 repeatedly moves relative to the inner peripheral surface of the through hole 33. However, in the structure of the present embodiment, the carrier pin 50 contacts the protective film 80 with high wear resistance, not the external gear body 70. Therefore, the inner peripheral surface of the through hole 33 can be prevented from being worn by contact with the carrier pin 50. That is, by using resin as the material of the external gear main body 70, the reduction gear 1 can be reduced in weight, reduced in size, and reduced in cost while suppressing wear on the inner peripheral surface of the through hole 33. The service life of the machine 1 can also be improved.

The protective film 80 covers the entire axial direction of the inner peripheral surface of the through hole 33. For this reason, wear is suppressed in the entire axial direction of the inner peripheral surface of the through hole 33. In the present embodiment, the entire circumference of the inner peripheral surface of the through hole 33 is covered with the protective film 80. For this reason, wear can be suppressed on the entire circumference of the inner peripheral surface of the through-hole 33.

However, the protective film 80 only needs to cover at least part of the inner peripheral surface of the through-hole 33. For example, in the inner peripheral surface of the through hole 33, the carrier pin 50 is in strong contact with two locations (portions surrounded by a broken line in FIG. 4) 331 facing each other in the circumferential direction with respect to the central axis 9, and therefore wear occurs. Cheap. Therefore, only the two places 331 may be covered with the protective film 80. Further, as shown in FIG. 5, the protective film 80 is relatively thick at two locations 331 facing the central axis 9 in the circumferential direction while covering the entire inner peripheral surface of the through-hole 33 with the protective film 80. May be.

<3. Modification>
As mentioned above, although exemplary embodiment of this invention was described, this invention is not limited to said embodiment.

In the above embodiment, the material of the external gear main body 70 is resin, and the material of the protective film 80 is metal. However, a resin may be used for the material of the protective film 80. In this case, a resin having higher mechanical strength (rigidity) than the second resin constituting the protective film 80 may be used as the first resin constituting the external gear main body 70. Thereby, power transmission by meshing of the external gear 30 and the internal gear 40 can be performed with high accuracy. On the other hand, a material having higher wear resistance (sliding property) than the first resin constituting the external gear main body 70 may be used for the second resin constituting the protective film 80. Thereby, abrasion of the inner peripheral surface of the through-hole 33 can be suppressed, and the service life of the speed reducer 1 can be improved.

Alternatively, the material of the external gear main body 70 may be a metal, and the material of the protective film 80 may be a metal having higher wear resistance than the external gear main body 70.

In the above embodiment, the speed reducer 1 has the two external gears 30. However, the number of external gears 30 included in the speed reducer 1 may be one or three or more.

In the above embodiment, a reduction gear that is an example of a transmission has been described. However, an equivalent structure may be used as the speed increaser. In that case, what is necessary is just to let a 2nd rotation part be an input part and a 1st rotation part be an output part. That is, the rotational motion at the second rotational speed before the speed increase may be input to the second rotational portion, and the rotational motion at the first rotational speed after the speed increase may be output from the first rotational portion.

Further, the detailed shape of the transmission may be different from the shape shown in each drawing of the present invention. Moreover, you may combine suitably each element which appeared in said embodiment and modification in the range which does not produce inconsistency.

This application claims priority based on Japanese Patent Application No. 2018-66372, a Japanese application filed on March 30, 2018, and uses all the contents described in the Japanese application.

The present invention can be used for a transmission.

DESCRIPTION OF SYMBOLS 1 Reduction gear 9 Center shaft 10 1st rotation part 20 Eccentric body 30 External gear 31 External tooth 32 External tooth groove 33 Through hole 34 Circular hole 40 Internal gear 41 Internal tooth 42 Internal tooth groove 50 Carrier pin 60 2nd Rotating part 61 Front carrier member 62 Rear carrier member 70 External gear body 72 First bearing 73 Second bearing 74 Third bearing 75 Fourth bearing 80 Protective film 91 Eccentric shaft

Claims

An eccentric rocking type transmission,
A first rotating portion that rotates at a first rotation speed about a central axis;
A disc-shaped eccentric body that rotates together with the first rotating portion, and whose distance from the central axis to the outer peripheral surface varies depending on the position in the circumferential direction;
A disk-shaped external gear having a circular hole into which the eccentric body fits in the center;
A cylindrical internal gear that is located radially outside the external gear and is arranged coaxially with the central axis;
A plurality of carrier pins extending in the axial direction through a plurality of through holes provided in the external gear;
A second rotating part fixed to the plurality of carrier pins;
With
The external gear has a plurality of external teeth on the outer periphery,
The internal gear has a plurality of internal teeth on the inner periphery,
On the extended line of the long diameter of the eccentric body, a part of the plurality of external teeth and a part of the plurality of internal teeth mesh with each other,
The external gear is
An external gear body;
A protective film covering at least a part of the inner peripheral surface of the through hole;
Have
The protective film has a higher wear resistance than the external gear main body.
The transmission according to claim 1,
The said protective film is a transmission which covers at least 2 places which oppose the circumferential direction with respect to the said central axis among the internal peripheral surfaces of the said through-hole.
The transmission according to claim 2,
The said protective film is a transmission which covers the perimeter of the internal peripheral surface of the said through-hole.
The transmission according to any one of claims 1 to 3, wherein
The said protective film is a transmission which covers the whole axial direction of the internal peripheral surface of the said through-hole.
The transmission according to any one of claims 1 to 4, wherein
The material of the external gear body is resin,
The material for the protective film is a transmission.
The transmission according to claim 5, wherein
The transmission, wherein the protective film is metal plating.
The transmission according to any one of claims 1 to 5, wherein
The transmission is a transmission, wherein the protective film is a protective member fixed to an inner peripheral surface of the through hole.
The transmission according to claim 7, wherein
The transmission is a transmission in which the protective member is press-fitted into the through hole.
The transmission according to any one of claims 1 to 4, wherein
The material of the external gear main body is a first resin,
The transmission is a transmission in which a material of the protective film is a second resin having higher wear resistance than the first resin.
The transmission according to any one of claims 1 to 9, wherein
The external gear main body is a transmission made of a material having lower wear resistance than the carrier pin.
The transmission according to any one of claims 1 to 10, wherein
The first rotating unit is an input unit that rotates at the first rotation speed by power supplied from a motor;
The transmission, wherein the second rotation unit is an output unit that rotates at a second rotation speed lower than the first rotation speed.