JP7532726B2 - Planetary Gear Unit - Google Patents

Description

The present invention relates to a planetary gear device.

Conventionally, a planetary gear device is known that has a sun gear, a plurality of planetary gears arranged around the sun gear, and an internal gear that surrounds the plurality of planetary gears. The planetary gear device is a device that rotates and revolves the planetary gears by the rotational motion input to the sun gear, and outputs the orbital motion of the planetary gears, thereby decelerating the rotational motion. A conventional planetary gear device is described in, for example, JP 2017-53461 A.
JP 2017-53461 A

In the planetary gear device of JP 2017-53461 A, needle bearings made of multiple rollers are used for the planetary gear bearings. The publication also describes that a grease retaining groove is provided on the inner peripheral surface of the planetary gear to lubricate the needle bearings.

The needle rollers used in needle bearings are inscribed against the inner circumferential surface of the planetary gear and are in circumferential contact with the carrier pin that supports the planetary gear. For this reason, the needle rollers are subjected to stronger contact pressure between them and the carrier pin, which is in an circumferential relationship, than between them and the planetary gear, which is in an inscribed relationship. However, in the structure of JP 2017-53461 A, grease is supplied to the needle bearing from the planetary gear side. For this reason, it is difficult to sufficiently lubricate the area between the needle rollers and the carrier pin, where strong contact pressure occurs.

The objective of the present invention is to provide a technology that can effectively lubricate the area between the needle rollers and carrier pins, where strong contact pressure occurs, in a planetary gear device.

The present invention is a planetary gear device including a sun gear that rotates around a central axis, planetary gears that mesh with the sun gear on the radial outside of the sun gear, and an annular internal gear that meshes with the planetary gear on the radial outside of the planetary gear, in which the planetary gears revolve around the central axis while rotating around a planetary axis that is parallel to the central axis, and the planetary gear device further includes a carrier pin that extends along the planetary axis and supports the planetary gear, a plurality of needle rollers that are interposed between the carrier pin and the planetary gear, and a carrier that rotates around the central axis together with the carrier pin, and the carrier pin has a grease retaining portion that retains semi-solid grease for lubricating the needle roller.

According to the present invention, grease can be supplied to the needle roller from the carrier pin side, not from the planetary gear side. This allows for good lubrication between the needle roller and the carrier pin, where strong contact pressure occurs.

FIG. 1 is a vertical sectional view of a planetary gear device according to a first embodiment. FIG. 2 is a plan view of the sun gear, the plurality of planetary gears, and the planetary support portion according to the first embodiment, as viewed from the input side. FIG. 3 is a partial vertical sectional view of the planetary gear device according to the first embodiment. FIG. 4 is a partial vertical sectional view of a planetary gear device according to the second embodiment. FIG. 5 is a partial vertical sectional view of a planetary gear device according to a modified example.

Below, exemplary embodiments of the present invention will be described with reference to the drawings. In this application, the direction parallel to the central axis of the sun gear is referred to as the "axial direction", the direction perpendicular to the central axis is referred to as the "radial direction", and the direction along the arc centered on the central axis is referred to as the "circumferential direction". However, the above "parallel direction" also includes directions that are approximately parallel. Furthermore, the above "orthogonal direction" also includes directions that are approximately orthogonal.

In the following explanation, the right side in FIG. 1 is referred to as the "input side," and the left side in FIG. 1 is referred to as the "output side."

<1. First embodiment>
<1-1. Overall configuration of planetary reducer>
1 is a vertical cross-sectional view of a planetary gear device 1 according to a first embodiment. The planetary gear device 1 is a device that reduces a rotational motion of a first rotation speed input from a motor to a rotational motion of a second rotation speed lower than the first rotation speed and outputs the reduced rotational motion. The planetary gear device 1 is incorporated into various industrial devices such as industrial robots and packaging machines for use. However, the planetary gear device 1 may also be used in other devices such as robot joints, assisted suits, and unmanned transport vehicles.

As shown in FIG. 1, the planetary gear device 1 of this embodiment includes one sun gear 10, multiple planetary gears 20, a planetary support portion 30, an internal gear 40, a casing 50, and an output shaft 60.

The sun gear 10 is a gear arranged along the central axis 91. The sun gear 10 is connected to a motor, which is a driving source, via an input shaft 11. The input shaft 11 is rotatably supported by the casing 50 via a bearing (not shown). The input shaft 11 and the sun gear 10 rotate around the central axis 91 at a first rotation speed before deceleration by the driving force input from the motor. A plurality of external teeth 12 are provided on the outer circumferential surface of the sun gear 10. The plurality of external teeth 12 are provided at a constant angular pitch around the central axis 91. Each external tooth 12 protrudes radially outward on the outer circumferential surface of the sun gear 10.

The planetary gear 20 is a gear arranged radially outward of the sun gear 10. FIG. 2 is a plan view of the sun gear 10, the multiple planetary gears 20, and the planetary support portion 30, as viewed from the input side. However, in FIG. 2, the teeth of each gear are omitted from illustration to avoid cluttering the drawing. As shown in FIG. 2, in this embodiment, three planetary gears 20 are arranged at equal intervals around the sun gear 10. However, the number of planetary gears 20 in the planetary gear device 1 may be one or two, or may be four or more.

Each planetary gear 20 has a pin hole 22 in the center. A carrier pin 32 and a needle bearing 34, described below, are inserted into the pin hole 22. Each planetary gear 20 is supported by the carrier pin 32 and the needle bearing 34 so that it can rotate around a planetary shaft 92 that is parallel to the central axis 91.

The planetary gear 20 has a number of external teeth 21 on its outer circumferential surface. The multiple external teeth 21 are arranged at a constant angular pitch centered on the planetary shaft 92. Each external tooth 21 protrudes outward from the outer circumferential surface of the planetary gear 20. The external teeth 12 of the sun gear 10 and the external teeth 21 of the planetary gear 20 mesh with each other.

The planetary support unit 30 is a unit that supports multiple planetary gears 20. The planetary support unit 30 has a carrier 31 and multiple carrier pins 32. The carrier 31 is arranged coaxially with the central axis 91. A bearing 37 is interposed between the inner peripheral surface of the casing 50 and the carrier 31. The carrier 31 is supported by the bearing 37 so that it can rotate around the central axis 91.

The carrier 31 has a plurality of through holes 33. The through holes 33 are holes that penetrate the carrier 31 in the radial direction. The plurality of through holes 33 are provided at equal intervals around the central axis 91. The plurality of carrier pins 32 are arranged at intervals in the circumferential direction. Each carrier pin 32 extends in the axial direction along the planetary shaft 92 within the through hole 33. Both axial ends of the carrier pin 32 are fixed to the carrier 31. The carrier pin 32 is fixed to the carrier 31 by, for example, press fitting.

The planetary gear 20 is disposed in the through hole 33 of the carrier 31. The planetary gear 20 is rotatably supported on the carrier pin 32 via a needle bearing 34. Therefore, the planetary gear 20 can rotate about the planetary shaft 92 while being supported by the carrier pin 32 and the needle bearing 34. The planetary gear 20 can revolve around the central shaft 91 together with the carrier 31, the carrier pin 32, and the needle bearing 34.

The internal gear 40 is an annular gear that meshes with the planetary gears 20 on the radially outer side of the planetary gears 20. The internal gear 40 is arranged coaxially with the central axis 91. The internal gear 40 has a plurality of internal teeth 41. The multiple internal teeth 41 are arranged at a constant angular pitch centered on the central axis 91. Each internal tooth 41 protrudes radially inward on the inner peripheral surface of the internal gear 40. The external teeth 21 of the planetary gear 20 described above mesh with the internal teeth 41 of the internal gear 40.

The casing 50 is a housing that houses the sun gear 10, the multiple planetary gears 20, and the planetary support portion 30 described above. The casing 50 has a generally cylindrical outer shape centered on the central axis 91. In this embodiment, the internal gear 40 and the casing 50 are formed from a single member. However, the internal gear 40 and the casing 50 may be separate parts. The casing 50 is fixed to the frame of the device to be driven. Therefore, even when the planetary gear device 1 is driven, the casing 50 and the internal gear 40 are kept stationary.

The output shaft 60 is a cylindrical member arranged along the central axis 91. The output shaft 60 rotates around the central axis 91 together with the carrier 31. In this embodiment, the carrier 31 and the output shaft 60 are formed from a single member. However, the carrier 31 and the output shaft 60 may be separate parts.

When the sun gear 10 rotates at a first rotation speed, the planetary gears 20 rotate about the planetary shaft 92 due to meshing with the sun gear 10. Furthermore, the planetary gears 20 revolve around the sun gear 10 along the internal gear 40 due to meshing with the internal gear 40. That is, the multiple planetary gears 20 revolve around the central shaft 91 while rotating about the planetary shaft 92. At this time, the rotation speed of the planetary gears 20 revolving around the central shaft 91 becomes a second rotation speed that is lower than the first rotation speed.

In addition, when the planetary gear 20 revolves at the second rotation speed, the multiple carrier pins 32, the carrier 31, and the output shaft 60 also rotate at the second rotation speed around the central axis 91. Therefore, a rotational motion at the second rotation speed after deceleration can be obtained from the output shaft 60.

<1-2. Grease retention structure>
Next, a description will be given of a grease holding structure in the planetary gear 20. Fig. 3 is a partial vertical cross-sectional view of the planetary gear device 1 in the vicinity of the planetary gear 20 (area A in Fig. 1).

As shown in FIG. 3, a needle bearing 34 is interposed between the carrier pin 32 and the planetary gear 20. The needle bearing 34 has a plurality of needle rollers 70. The needle rollers 70 are cylindrical metal parts extending in the axial direction. The plurality of needle rollers 70 are arranged in an annular shape centered on the planetary shaft 91. When the planetary gear device 1 is driven, the plurality of needle rollers 70 need to be sufficiently lubricated. Therefore, in this embodiment, grease is held in a grease holding portion 80 provided on the carrier pin 32. The grease is a semi-solid oil.

The grease holding portion 80 is a hole extending from a first opening 811 provided on the outer peripheral surface of the carrier pin 32 toward the inside of the carrier pin 32. Specifically, the grease holding portion 80 has a first hole 81 and a second hole 82. The first hole 81 extends from the first opening 811 toward the planetary shaft 92. The second hole 82 extends in the axial direction from the first hole 81 to a second opening 821 provided on the axial end surface of the carrier pin 32. In other words, the first hole 81 and the second hole 82 form a substantially L-shaped through hole. The grease is held inside the first hole 81 and the second hole 82.

When the planetary gear device 1 is driven, the grease held in the grease holding portion 80 is supplied to the needle rollers 70 through the first opening 811. The grease is supplied from the grease holding portion 80 to the needle rollers 70 by centrifugal force caused by the revolution of the carrier pin 32 around the central axis 91, or by negative pressure generated near the needle rollers 70 as the needle rollers 70 roll. The grease supplied to the needle rollers 70 spreads in the circumferential and axial directions as the needle rollers 70 roll. This lubricates the needle rollers 70. As a result, the planetary gear 20 rotates smoothly around the carrier pin 32.

In this planetary gear device 1, semi-solid grease is used instead of liquid oil. In this way, the grease can be held without flowing out of the grease holding portion 80. This eliminates the need for an oil seal, and reduces the number of parts in the planetary gear device 1. Specifically, it is preferable to use grease with a consistency of 340 or less in the JIS K 2220 test method.

The needle roller 70 is inscribed with the planetary gear 20. That is, the outer peripheral surface of the needle roller 70 contacts the inner peripheral surface of the planetary gear 20. The needle roller 70 is also inscribed with the carrier pin 32. That is, the outer peripheral surface of the needle roller 70 contacts the outer peripheral surface of the carrier pin 32. A stronger contact pressure is generated at the circumscribed point than at the inscribed point. Therefore, when the planetary gear device 1 is driven, a stronger contact pressure is generated between the needle roller 70 and the carrier pin 32 than between the needle roller 70 and the planetary gear 20.

Therefore, in this planetary gear device 1, grease is supplied to the needle roller 70 from the grease retaining portion 80 provided on the carrier pin 32, rather than from the planetary gear 20. In this way, it is possible to better lubricate the area between the needle roller 70 and the carrier pin 32, where strong contact pressure occurs.

In addition, in the structure of this embodiment, no holes or grooves are formed on the outer peripheral surface of the carrier pin 32 other than the first opening 811. This ensures a large area of the outer peripheral surface of the carrier pin 32 that can come into contact with the needle roller 70. This prevents the support force of the carrier pin 32 for the needle roller 70 from decreasing.

When the planetary gear device 1 is driven, a particularly strong support force is generated between the needle rollers 70 and both end faces (portions indicated by reference numeral 321 in FIG. 2) of the outer circumferential surface of the carrier pin 32 in the circumferential direction relative to the central axis 91 of the carrier pin 32. In other words, these end faces 321 are particularly important support surfaces for supporting the multiple needle rollers 70. Therefore, it is preferable to provide the first opening 811 at a position on the outer circumferential surface of the carrier pin 32 that avoids the end faces 321. In this way, it is possible to prevent a decrease in the support force at the end faces 321 of the carrier pin 32.

In this embodiment, a first opening 811 is provided on the outer peripheral surface of the carrier pin 32 at the end face radially outward relative to the central axis 91. In this way, when the planetary gear device 1 is driven, grease can be supplied from the first opening 811 to the needle roller 70 by centrifugal force generated by the revolution of the carrier pin 32 around the central axis 91. This can further promote the supply of grease from the grease retaining portion 80 to the needle roller 70.

As shown in FIG. 3, the multiple needle rollers 70 of this embodiment include multiple first needle rollers 71 and multiple second needle rollers 72. The multiple first needle rollers 71 are arranged in a circular shape around the planetary shaft 92. The multiple second needle rollers 72 are also arranged in a circular shape around the planetary shaft 92. The multiple first needle rollers 71 and the multiple second needle rollers 72 are adjacent to each other in the axial direction. In this way, by arranging the needle rollers 70 in two rows, the amount of inclination of each needle roller 70 with respect to the axial direction can be suppressed. Therefore, poor lubrication caused by the inclination of the needle rollers 70 can be suppressed.

In addition, in the structure of this embodiment, the first opening 811 opens toward the boundary between the first needle roller 71 and the second needle roller 72. In other words, the first opening 811 is provided in a portion of the outer circumferential surface of the carrier pin 32 where the first needle roller 71 and the second needle roller 72 do not originally come into contact. In this way, the first opening 811 is provided on the outer circumferential surface of the carrier pin 32, and the reduction in the contact area between the first needle roller 71 and the second needle roller 72 and the carrier pin 32 can be minimized.

In addition, the grease holding portion 80 of this embodiment has not only the first hole 81 but also the second hole 82. Therefore, more grease can be held in the grease holding portion 80 compared to when the grease holding portion 80 is composed of only the first hole 81.

As shown in FIG. 3, the second hole 82 is inclined with respect to the planetary shaft 92. The radial position of the second hole 82 gradually moves radially outward as it approaches the first hole 81. In this way, the grease held in the second hole 82 moves toward the first hole 81 due to the centrifugal force caused by the revolution of the carrier pin 32 about the central shaft 91. Therefore, when the planetary gear device 1 is driven, grease can be more effectively supplied from the second hole 82 through the first hole 81 to the multiple needle rollers 70.

The centrifugal force acting on the grease held in the first hole 81 and the second hole 82 changes according to the driving speed of the planetary gear device 1. Therefore, the amount of grease supplied from the grease holding portion 80 to the needle roller 70 can be adjusted according to the driving speed of the planetary gear device 1. Specifically, the amount of grease supplied can be reduced during low-speed driving and increased during high-speed driving. In other words, the supply of grease can be promoted more as the need to lubricate the needle roller 70 increases.

In addition, in the structure of this embodiment, the second hole 82 of the grease retaining portion 80 extends to the second opening 821 provided on the end face of the input side (one axial side) of the carrier pin 32. Therefore, grease can be replenished from the second opening 821 to the second hole 82. In particular, as shown in Figures 1 to 3, the second hole 82 is exposed on the end face of the input side of the carrier 31. Therefore, grease can be replenished from the second opening 821 to the second hole 82 without disassembling the carrier 31, the carrier pin 32, the needle bearing 34, and the planetary gear 20. This reduces the burden on the user in the task of replenishing grease.

In addition, in the structure of this embodiment, the end face of the output side (the other axial side) of the carrier pin 32 faces the bearing 37 in the axial direction. The second opening 821 is provided on the end face of the input side of the carrier pin 32, not on the end face of the output side. Therefore, grease can be replenished from the second opening 821 to the second hole 82 without disassembling the carrier 31 and the bearing 37.

<2. Second embodiment>
Next, a second embodiment of the present invention will be described. In the following, differences from the first embodiment will be mainly described, and duplicated descriptions of portions similar to those of the first embodiment will be omitted. Fig. 4 is a partial vertical cross-sectional view of the planetary gear device 1 according to the second embodiment.

The planetary gear device 1 of this embodiment differs from the first embodiment in the structure of the grease retaining portion 80. As shown in FIG. 4, the grease retaining portion 80 of this embodiment is a groove provided on the outer circumferential surface of the carrier pin 32.

The grease retaining portion 80 of this embodiment has a first groove 83 and a second groove 84. The first groove 83 is a spiral groove provided on the outer peripheral surface of the carrier pin 32. The second groove 84 is an annular groove provided on the outer peripheral surface of the carrier pin 32. The second groove 84 is provided at a position facing the boundary between the first needle roller 71 and the second needle roller 72. The first groove 83 extends spirally from the second groove 84 to both sides in the axial direction.

When forming the grease retaining portion 80 on the outer peripheral surface of the carrier pin 32, first, a circular second groove 84 is cut into the outer peripheral surface of the carrier pin 32. Then, starting from the second groove 84, a spiral first groove 83 is cut in both axial directions. This makes it easy to form the spiral first groove 83. Furthermore, by making the first groove 83 spiral, it is possible to provide grooves over a wide range of the outer peripheral surface of the carrier pin 32 while minimizing the number of groove processes.

The grease is held inside the first groove 83 and the second groove 84. Therefore, when the planetary gear device 1 is driven, the grease is supplied to the needle roller 70 from the first groove 83 and the second groove 84. By adopting the structure of this embodiment, grease can be supplied to the needle roller 70 from a wider area of the outer circumferential surface of the carrier pin 32 than in the first embodiment. However, in this embodiment, since the first groove 83 and the second groove 84 are provided on the outer circumferential surface of the carrier pin 32, the contact area between the carrier pin 32 and the needle roller 70 is smaller. Therefore, from the viewpoint of ensuring the support force between the carrier pin 32 and the needle roller 70, the structure of the first embodiment is preferable.

In this embodiment, the annular second groove 84 faces the boundary between the first needle roller 71 and the second needle roller 72. That is, the second groove 84 is provided in a portion of the outer circumferential surface of the carrier pin 32 where the first needle roller 71 and the second needle roller 72 do not originally come into contact. In this way, the second groove 84 is provided and the reduction in the contact area between the first needle roller 71 and the second needle roller 72 and the carrier pin 32 can be minimized.

As shown in FIG. 4, the planetary gear device 1 has a pair of washers 35 for each planetary gear 20. One of the pair of washers 35 is interposed between the input side end (one axial end) of the first needle roller 71 and the carrier 31. The other of the pair of washers 35 is interposed between the output side end (the other axial end) of the second needle roller 72 and the carrier 31. Each washer 35 has an annular outer shape centered on the planetary shaft 92. The hardness of the washer 35 is greater than the hardness of the carrier 31.

By providing such a washer 35, it is possible to prevent the planetary gear 20 and the carrier 31 from sliding directly against each other. It is also possible to prevent the carrier 31 from being worn down by the pressing force from the needle roller 70.

As shown in FIG. 4, in this embodiment, the first spiral groove 83 extends from the same axial position as one washer 35 to the same axial position as the other washer 35. Therefore, grease is supplied not only to the needle roller 70 but also to the pair of washers 35. This can further improve the sliding properties of the planetary gear 20, the washer 35, and the carrier 31.

3. Modifications
Although the first and second embodiments of the present invention have been described above, the present invention is not limited to the above-mentioned embodiments.

Figure 5 is a partial vertical cross-sectional view of a planetary gear device according to a modified example of the first embodiment. In the example of Figure 5, the grease retaining portion 80 of the carrier pin 32 has a first hole 81 and a pair of second holes 82. One of the pair of second holes 82 extends from the end of the first hole 81 toward the input side (one axial side), as in the first embodiment described above. The other of the pair of second holes 82 extends from the end of the first hole 81 toward the output side (the other axial side). In this way, by expanding the range of the second holes 82, more grease can be retained in the grease retaining portion 80.

In any of the above first and second embodiments, and the modified example of FIG. 5, the grease holding portion 80 is provided at least in the range from the axial center of the planetary gear 20 to the end of the input side (one axial side) of the planetary gear 20. In this way, by ensuring the axial range of the grease holding portion 80, a large amount of grease can be held in the grease holding portion 80.

However, the grease retaining portion of the present invention does not necessarily have to be provided over such a range. For example, in the structure of the first embodiment, the second hole 82 may be omitted, and the grease retaining portion 80 may be formed only by the first hole 81.

The detailed shape of the planetary gear device may differ from the shapes shown in the drawings of this application. Furthermore, the elements that appear in the above embodiments and variations may be selected as appropriate to the extent that no contradictions arise.

This invention can be used in planetary gear devices.

REFERENCE SIGNS LIST 1 Planetary gear device 10 Sun gear 11 Input shaft 12 External teeth 20 Planet gear 21 External teeth 22 Pin hole 30 Planet support portion 31 Carrier 32 Carrier pin 33 Through hole 34 Needle bearing 35 Washer 37 Bearing 40 Internal gear 41 Internal teeth 50 Casing 60 Output shaft 70 Needle roller 71 First needle roller 72 Second needle roller 80 Grease retaining portion 81 First hole 82 Second hole 83 First groove 84 Second groove 91 Central shaft 92 Planet shaft 811 First opening 821 Second opening

Claims (11)

A sun gear that rotates around a central axis;
a planetary gear that meshes with the sun gear on the radially outer side of the sun gear;
an annular internal gear that meshes with the planetary gear on the radially outer side of the planetary gear;
A planetary gear device comprising:
The planetary gear rotates about a planetary axis parallel to the central axis while revolving around the central axis,
The planetary gear device is
A carrier pin extending along the planetary shaft and supporting the planetary gear;
a plurality of needle rollers interposed between the carrier pin and the planetary gear;
a carrier that rotates about the central axis together with the carrier pin;
Further equipped with
The carrier pin is
a grease retaining portion for retaining semi-solid grease for lubricating the needle roller ;
The grease retaining portion is
a first hole extending from a first opening provided on an outer peripheral surface of the carrier pin toward the planetary shaft;
a second hole extending axially from the first hole;
having
The second hole is a hole inclined with respect to the planetary shaft,
A planetary gear device , wherein the radial position of the second hole gradually moves radially outward as it approaches the first hole . A sun gear that rotates around a central axis;
a planetary gear that meshes with the sun gear on the radially outer side of the sun gear;
an annular internal gear that meshes with the planetary gear on the radially outer side of the planetary gear;
A planetary gear device comprising:
The planetary gear rotates about a planetary axis parallel to the central axis while revolving around the central axis,
The planetary gear device is
A carrier pin extending along the planetary shaft and supporting the planetary gear;
a plurality of needle rollers interposed between the carrier pin and the planetary gear;
a carrier that rotates about the central axis together with the carrier pin;
a bearing that rotatably supports the carrier;
Further equipped with
The carrier pin is
a grease retaining portion for retaining semi-solid grease for lubricating the needle roller;
The grease retaining portion is
a first hole extending from a first opening provided on an outer peripheral surface of the carrier pin toward the planetary shaft;
a second hole extending axially from the first hole;
having
The second hole extends to a second opening provided and exposed on one axial end surface of the carrier pin,
The bearing faces the other axial end surface of the carrier pin in the axial direction.
Planetary gear set. A sun gear that rotates around a central axis;
a planetary gear that meshes with the sun gear on the radially outer side of the sun gear;
an annular internal gear that meshes with the planetary gear on the radially outer side of the planetary gear;
A planetary gear device comprising:
The planetary gear rotates about a planetary axis parallel to the central axis while revolving around the central axis,
The planetary gear device is
A carrier pin extending along the planetary shaft and supporting the planetary gear;
a plurality of needle rollers interposed between the carrier pin and the planetary gear;
a carrier that rotates about the central axis together with the carrier pin;
Further equipped with
The plurality of needle rollers include
A plurality of first needle rollers arranged in an annular shape around the planetary shaft;
a plurality of second needle rollers that are adjacent to the plurality of first needle rollers in the axial direction and are arranged in an annular shape around the planetary shaft;
having
The carrier pin is
a grease retaining portion for retaining semi-solid grease for lubricating the needle roller;
The grease retaining portion is
A first spiral groove provided on an outer circumferential surface of the carrier pin;
a second groove having an annular shape facing a boundary portion between the first needle roller and the second needle roller,
The first groove extends from the second groove on both sides in the axial direction. A planetary gear device according to any one of claims 1 to 3,
The consistency of the grease according to the test method of JIS K 2220 is 340 or less. A planetary gear device according to any one of claims 1 to 4, further comprising:
A planetary gear device, wherein the grease retaining portion is provided at least in a range from a center of the planetary gear in an axial direction to one end of the planetary gear in the axial direction . 3. A planetary gear device according to claim 1,
The first opening is located on an outer circumferential surface of the carrier pin other than both end surfaces in a circumferential direction relative to the central axis. 7. The planetary gear device according to claim 6,
The first opening is located on an end face of an outer circumferential surface of the carrier pin that is radially outward relative to the central axis. A planetary gear device according to claim 6 or claim 7,
The plurality of needle rollers include
A plurality of first needle rollers arranged in an annular shape around the planetary shaft;
a plurality of second needle rollers that are adjacent to the plurality of first needle rollers in the axial direction and are arranged in an annular shape around the planetary shaft;
having
The first opening opens toward a boundary between the first needle roller and the second needle roller. 2. The planetary gear device according to claim 1,
The second hole extends to a second opening provided in an axial end surface of the carrier pin . A planetary gear device according to any one of claims 1 to 3,
The planetary gear device, wherein the grease retaining portion is a groove provided on an outer peripheral surface of the carrier pin. 4. The planetary gear device according to claim 3,
a pair of annular washers interposed between one axial end of the needle roller and the carrier, and between the other axial end of the needle roller and the carrier;
Further equipped with
The first groove extends from a same axial position as one of the washers to a same axial position as the other of the washers.

Images