Speed reducer

Abstract

To provide a speed reducer capable of further enhancing rigidity.SOLUTION: The speed reducer in this embodiment includes an internal tooth gear, a carrier 3 rotatably provided on the internal tooth gear, a sun shaft rotatably supported by the carrier 3, and a planetary shaft rotatably supported by the carrier 3 for revolving about the sun shaft, the planetary shaft including a first planetary gear engaging with a sun gear, and a second planetary gear 28 engaging with internal teeth, the carrier 3 existing between two peripherally adjacent planetary shafts and existing in a region between two second straight lines L2 parallel to a first straight line L1 connecting a carrier axis A1 and a planetary axis A2 and contacting a tooth top circle diameter D of the second planetary gear 28.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a reducer. [Background technology]

[0002] A planetary gear reducer as a reducer includes a sun gear, multiple planetary gears that mesh with the sun gear and revolve around the sun gear, a carrier that rotatably supports the multiple planetary gears, and an internal gear that is positioned radially outward of the multiple planetary gears and meshes with the multiple planetary gears. Some planetary gears in planetary gear reducers have separate gears that mesh with the sun gear (hereinafter referred to as the first planetary gear) and the internal gear (hereinafter referred to as the second planetary gear).

[0003] In this type of planetary gear, a first planetary gear and a second planetary gear are arranged side by side in the axial direction on a planetary shaft that is rotatably supported by a carrier. In order to improve the rigidity of the entire reducer, the carrier may include two carrier plates that rotatably support both axial ends of the planetary shaft. In order to further improve the rigidity of the reducer, multiple pillars may be provided to connect the two carrier plates. The multiple pillars are often provided between two planetary shafts that are adjacent in the circumferential direction (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] US Patent Application Publication No. 2017 / 0198785 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the above-mentioned conventional technology, since the multiple pillars are arranged at intervals in the circumferential direction, the pillars cannot effectively bear the moment load depending on the position (direction) of the moment load acting on the reducer, and therefore there is room for improvement in order to increase the rigidity of the reducer.

[0006] The present invention provides a reducer that can further increase rigidity. [Means for solving the problem]

[0007] A reducer according to one embodiment of the present invention comprises an internal gear having internal teeth, a carrier rotatably arranged relative to the internal gear, a sun shaft arranged coaxially with the rotation axis of the carrier, rotatably supported by the carrier, and having a sun gear, and a plurality of planetary shafts arranged circumferentially around the rotation axis of the carrier, rotatably supported by the carrier, and revolving relative to the sun shaft, the planetary shafts comprising a first planetary gear meshed with the sun gear and a second planetary gear meshed with the internal teeth, the carrier being located between two circumferentially adjacent planetary shafts, and located in an area between two second straight lines that are parallel to a first straight line connecting the rotation axis of the carrier and the rotation axis of the planetary shaft relative to the carrier, and that are tangent to the tip circle diameter of the second planetary gear.

[0008] This configuration allows the carrier to be positioned as far as possible between adjacent planetary shafts in the circumferential direction, which allows the carrier to bear as much of the moment load acting on the reducer as possible, thereby further increasing the rigidity of the reducer.

[0009] In the above configuration, the carrier may include two carrier plates rotatably supported on both axial sides of the internal teeth of the internal gear, and a pillar portion connecting the two carrier plates, wherein the sun shaft and the plurality of planetary shafts are rotatably supported on the two carrier plates, and the pillar portion may be disposed between two circumferentially adjacent planetary shafts and formed in a region between two second straight lines that are parallel to a first straight line connecting the rotation axis of the carrier and the rotation axis of the planetary shaft relative to the carrier plate and are tangent to a tip circle diameter of the second planetary gear.

[0010] In the above configuration, the carrier may be present in a region between two third straight lines that pass through a rotation axis of the carrier and are tangent to a tip circle diameter of the second planetary gear.

[0011] In the above configuration, there may be an even number of the planetary shafts.

[0012] In the above configuration, the pillar portion includes a pillar portion main body arranged between two circumferentially adjacent planetary shafts, and a connecting portion connecting the two circumferentially adjacent pillar portion main bodies, and the connecting portion may be arranged radially inward of the internal gear relative to the planetary shafts.

[0013] In the above configuration, a side surface of the connecting portion on the planetary shaft side may be formed in an arc shape when viewed in the axial direction. [Effects of the Invention]

[0014] The above-described reducer can further increase its rigidity. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a schematic cross-sectional view of a reducer according to an embodiment of the present invention. [Figure 2] 3 is a plan view of a first carrier plate according to an embodiment of the present invention, viewed from the inner flange portion side. FIG. [Figure 3]5 is an explanatory diagram illustrating the rigidity of the reducer against a moment load according to the embodiment of the present invention. FIG. [Figure 4] FIG. 4 is an explanatory diagram showing an existence region of a pillar portion under a first condition in the embodiment of the present invention. [Figure 5] FIG. 10 is an explanatory diagram showing an existence region of a pillar portion under a second condition in the embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0016] Next, an embodiment of the present invention will be described with reference to the drawings.

[0017] <Reducer> FIG. 1 is a schematic cross-sectional view of a reducer 1. As shown in FIG. 1, the reducer 1 is a so-called planetary gear reducer. The reducer 1 includes a cylindrical internal gear 2, a carrier 3 rotatably mounted relative to the internal gear 2, a sun shaft 4 arranged coaxially with a rotation axis A1 of the carrier 3, and four planet shafts 5 arranged in the direction of rotation of the carrier 3 centered on the rotation axis A1. In the following description, the rotation axis A1 of the carrier 3 will be referred to as the carrier axis A1. A direction parallel to the carrier axis A1 will be referred to as the axial direction. The rotation direction of the carrier 3 will be referred to as the circumferential direction. A direction perpendicular to the axial direction and the circumferential direction (the radial direction of the carrier 3) will be referred to as the radial direction.

[0018] <Internal gear> An annular outer flange portion 6 that protrudes radially outward is formed on the outer peripheral surface 2a of the internal gear 2. The outer flange portion 6 is for attaching the reducer 1 to an external device (not shown). The outer flange portion 6 has a plurality of bolt insertion holes 6a arranged at equal intervals in the circumferential direction. The reducer 1 is fixed to the external device by inserting bolts (not shown) into the bolt insertion holes 6a and tightening them to the external device (not shown).

[0019] An annular inner flange portion 7 that protrudes radially inward is formed on the inner peripheral surface 2b of the internal gear 2. Internal teeth 7a are formed on the inner peripheral surface of the inner flange portion 7. The internal teeth 7a are formed over the entire inner flange portion 7 in the axial direction. Main bearings 81, 82 (a first main bearing 81 and a second main bearing 82) are provided on both axial sides of the inner flange portion 7 on the inner peripheral surface 2b of the internal gear 2. The two main bearings 81, 82 are formed symmetrically with respect to the inner flange portion 7. For this reason, in the following explanation, only the first main bearing 81 of the two main bearings 81, 82 will be explained. The parts of the second main bearing 82 will be assigned the same reference numerals as those of the first main bearing 81, and explanations thereof will be omitted.

[0020] The first main bearing 81 is, for example, a ball bearing, and includes an inner race 81a, an outer race 81b disposed radially outward of the inner race 81a, and rolling elements 81c disposed between the inner race 81a and the outer race 81b. The rolling elements 81c are, for example, spheres. However, the present invention is not limited to this, and various rolling elements such as cylindrical rollers can be used.

[0021] The outer race 81b is molded integrally with the internal gear 2. The inner race 81a is molded integrally with the carrier 3. A cylindrical seal retaining portion 8 is formed to protrude in the axial direction on the side of the internal gear 2 opposite the inner flange portion 7 across the first main bearing 81. The outer peripheral surface of an annular seal portion 9 is fitted into the inner peripheral surface 8a of the seal retaining portion 8. The seal portion 9 provides a seal between the internal gear 2 and the carrier 3.

[0022] <Career> The carrier 3 is composed of two carrier plates 11, 12 (first carrier plate 11, second carrier plate 12) that overlap in the axial direction. Of the two carrier plates 11, 12, the first carrier plate 11 is rotatably supported by the internal gear 2 via a first main bearing 81. Of the two carrier plates 11, 12, the second carrier plate 12 is rotatably supported by the internal gear 2 via a second main bearing 82.

[0023] The two carrier plates 11, 12 are formed roughly symmetrically around the inner flange portion 7. For this reason, the following description will only describe the first carrier plate 11 of the two carrier plates 11, 12. The components of the second carrier plate 12 will be denoted by the same reference numerals as those of the first carrier plate 11 and will not be described again. Furthermore, the second carrier plate 12 will only be described with respect to the differences from the first carrier plate 11.

[0024] FIG. 2 is a plan view of the first carrier plate 11 as viewed from the inner flange portion 7 side. As shown in FIGS. 1 and 2, the first carrier plate 11 includes a disk-shaped plate body 13 and a column portion 14 for connecting the two carrier plates 11 and 12 together. An inner race 81a of a first main bearing 81 is integrally formed on the outer circumferential portion 13a of the plate body 13 on the side facing the second carrier plate 12. This allows the plate body 13 of the first carrier plate 11 to be rotatably supported by the internal gear 2 via the first main bearing 81. The outer circumferential portion 13a of the plate body 13 on the opposite side to the second carrier plate 12 is configured as a seal surface 13b. The inner circumferential surface of a seal portion 9 is fitted into the seal surface 13b. This allows the seal portion 9 to seal between the internal gear 2 and the carrier 3.

[0025] A through hole 13c penetrating in the axial direction is formed in the radial center of the plate body 13. The through hole 13c is arranged coaxially with the carrier axis A1. A first bearing housing 15 is formed on the second carrier plate 12 side of the through hole 13c. The first bearing housing 15 is a circular recess when viewed in the axial direction. The first bearing housing 15 is arranged coaxially with the carrier axis A1.

[0026] First bearing housing 15 is formed with a step from through hole 13c. The inner diameter of first bearing housing 15 is larger than the inner diameter of through hole 13c. First bearing housing 15 is provided with first bearing 17. First bearing 17 is, for example, a ball bearing. However, this is not limited to this, and various bearings such as a cylindrical roller bearing can be used as first bearing 17. First bearing 17 is for supporting sun shaft 4 so that it can rotate freely.

[0027] Four second bearing housings 16 are formed on the plate body 13 around the first bearing housing 15. The second bearing housings 16 are arranged at equal intervals in the circumferential direction around the carrier axis A1. The second bearing housings 16 are recesses formed on one surface 13d of the plate body 13 facing the second carrier plate 12. The second bearing housings 16 are formed in a circular shape when viewed in the axial direction. The second bearing housings 16 are provided with second bearings 18. The second bearings 18 are, for example, ball bearings. However, this is not limited to this, and various other bearings such as cylindrical roller bearings can be used for the second bearings 18. The second bearings 18 are for rotatably supporting the planetary shafts 5.

[0028] The pillar portion 14 is formed to protrude from one surface 13d of the plate body 13 toward the second carrier plate 12. The pillar portion 14 is formed so as to avoid the second bearing housing 16 and the planetary shaft 5 (including the second planetary gear 28 described below) supported by the second bearing housing 16. In other words, the pillar portion 14 includes four pillar portion bodies 21 arranged between two circumferentially adjacent second bearing housings 16, and a connecting portion 22 connecting two circumferentially adjacent pillar portion bodies 21.

[0029] The column body 21 is formed in a quadrangular column shape. An outer surface 21a on the radially outer side of the column body 21 extends along the circumferential direction. Two side surfaces 21b extend perpendicular to the outer surface 21a when viewed from the axial direction and face each other in the circumferential direction. The connecting portion 22 is formed so as to connect the radially inner end portions of the pillar portion main body 21. In other words, the connecting portion 22 is disposed radially inward of the planetary shaft 5. An inner surface 22a on the radially inner side of the connecting portion 22 is formed in an arc shape centered on the carrier axis A1. An outer surface 22b on the radially outer side of the connecting portion 22 is formed in an arc shape so as to avoid the second bearing housing 16. The outer surface 22b of the connecting portion 22 and the side surface 21b of the pillar portion main body 21 are smoothly connected.

[0030] The connecting portion 22 does not necessarily have to be formed over the entire space between two circumferentially adjacent column main bodies 21. In other words, the connecting portion 22 does not necessarily have to be formed over the entire circumference. That is, it is sufficient if the connecting portion 22 extends a predetermined length in the circumferential direction from the side surface 21b of the column main body 21. This will be described in detail later. The column body 21 and the connecting portion 22 protrude by the same length from one surface 13d of the plate body 13. Therefore, the tip 14a of the column 14 is flat. Hereinafter, the protruding length of the column body 21 and the connecting portion 22 protruding from one surface 13d of the plate body 13 will be referred to as the protruding length of the column 14.

[0031] With this configuration, the first carrier plate 11 and the second carrier plate 12 are joined by butting the tips 14a of the respective column portions 14 together. This forms a fixed gap between the plate bodies 13 of the carrier plates 11, 12. The protruding length of the column portions 14 is determined so that this fixed gap is longer than the axial length of the inner flange portion 7 of the internal gear 2. The inner flange portion 7 faces between the two plate bodies 13.

[0032] A plurality of (for example, four in this embodiment) pin holes 23 are formed in the tip 14a of each pillar 14 at a location corresponding to the pillar body 21. The first carrier plate 11 and the second carrier plate 12 are positioned by press-fitting a pin (not shown) into each pin hole 23. The second carrier plate 12 does not have the sealing surface 13b of the first carrier plate 11. Therefore, the axial thickness of the second carrier plate 12 is thinner than the axial thickness of the first carrier plate 11.

[0033] <Sun axis> The sun shaft 4 is rotatably supported by first bearings 17 provided on the carrier plates 11 and 12. An end 4a of the sun shaft 4 on the second carrier plate 12 side protrudes outward in the axial direction via the first bearing 17. A sun gear 24 and an input gear 25 are provided at this protruding portion, in this order from the first bearing 17 side. The sun gear 24 is integrally molded with the sun shaft 4. The input gear 25 is fitted and fixed to the sun shaft 4. The input gear 25 rotates integrally with the sun shaft 4. A drive gear 26a of an electric motor 26, for example, is engaged with the input gear 25. This transmits power to the input gear 25.

[0034] <Planetary shaft> The planetary shaft 5 is rotatably supported by the second bearings 18 provided on the carrier plates 11 and 12. That is, the planetary shaft 5 rotates about a rotation axis A2. Hereinafter, this rotation axis A2 will be referred to as the planetary axis A2. The planetary axis A2 is parallel to the carrier axis A1. An end 5a of the planetary shaft 5 on the second caliper plate 12 side protrudes outward in the axial direction via a second bearing 18. A first planetary gear 27 is fitted and fixed to this protruding portion. The first planetary gear 27 is meshed with the sun gear 24. A second planetary gear 28 is integrally formed between the two second bearings 18 on the planetary shaft 5. The second planetary gear 28 is in mesh with the internal teeth 7a of the inner flange portion 7.

[0035] <Reduction gear operation> Next, the operation of the reducer 1 will be described. When the electric motor 26 is driven, the sun gear 24 (sun shaft 4) is rotated via the drive gear 26a and the input gear 25. This rotates the first planetary gear 27 meshed with the sun gear 24. The second planetary gear 28 rotates integrally with the first planetary gear 27. The second planetary gear 28 is meshed with the internal teeth 7a of the inner flange portion 7. Therefore, the planetary gears 27, 28 and the planetary shaft 5 revolve around the carrier axis A1 while rotating about the planet axis A2.

[0036] As the planetary gears 27, 28 and the planetary shaft 5 revolve, the carrier 3 rotates relative to the internal gear 2. At this time, by fixing the internal gear 2 to an external device (not shown), the carrier 3 functions as an output part. In other words, by attaching a driven body (not shown) to the carrier 3, the rotation of the drive gear 26a is decelerated via the carrier 3 and output to the driven body. For example, when the carrier 3 is fixed to an external device, it is also possible to make the internal gear 2 function as an output part.

[0037] When the reducer 1 is driven, a moment load is applied to the carrier 3. The position (direction) of the moment load changes as the carrier 3 or the internal gear 2 rotates. The carrier 3 is provided with pillar portions 14. The pillar portions 14 are formed around the entire circumference on the radially inner side of each planetary shaft 5 (second planetary gear 28). Therefore, the pillar portions 14 can bear the moment load regardless of the position of the moment load.

[0038] Here, a case where the connecting portion 22 is not present in the column portion 14 and only the column portion main body 21 is present will be described. Fig. 3 is an explanatory diagram of the rigidity of the reducer 1 (carrier 3) against a moment load. Fig. 3 corresponds to the above-mentioned Fig. 2. Fig. 3 shows the case where only the column main body 21 is included, as shown in Fig. 2 by a two-dot chain line.

[0039] As shown in Figure 3, when the pillar portion 14 consists only of the pillar portion main body 21, the pillar portion 14 does not exist depending on the position of the moment load (see, for example, arrow Y1). This makes it difficult to ensure sufficient rigidity for the carrier 3 (reduction gear 1). In particular, when there is an even number of planetary shafts 5 (first planetary gears 27 and second planetary gears 28), the area where the pillar portion 14 does not exist becomes large (see ranges S1 and S2 in Figure 3). In contrast to this, in this embodiment, the pillar portion 14 has a connecting portion 22 in addition to the pillar portion main body 21. Therefore, the connecting portion 22 ensures the rigidity of the carrier 3 against the moment load even if the position of the moment load changes.

[0040] 4 and 5 are explanatory diagrams showing the areas where the pillar portions 14 are present. For the sake of convenience of explanation, only a quarter of the circumference of the carrier 3 is shown in FIGS. From the above, it is not necessary for the connecting portion 22 to be formed over the entire circumference. As shown in Fig. 4, the connecting portion 22 (pillar portion 14) needs to be parallel to at least the first line L1 connecting the carrier axis A1 and the planet axis A2, and to be present in the region S3 between two second lines L2 tangent to the tip circle diameter D of the second planetary gear 28. Hereinafter, this condition will be referred to as the first condition.

[0041] 5, it is desirable that the connecting portion 22 (pillar portion 14) be present in an area S4 between a third straight line L3 that passes through the carrier axis A1 and is tangent to the tip circle diameter D of the second planetary gear 28. Hereinafter, this condition will be referred to as the second condition.

[0042] As described above, in the above-described embodiment, the pillar portions 14 are formed so as to satisfy at least the first condition. Therefore, compared to a case where only the pillar portion main body 21 is provided on the carrier 3, pillar portions 14 (connecting portions 22) separate from the pillar portion main body 21 can be protruded on both circumferential sides of the pillar portion main body 21. In other words, the carrier 3 (pillar portions 14) can be positioned as far as possible between adjacent planetary shafts 5 in the circumferential direction. Therefore, it is possible for the carrier 3 to bear as much of the moment load acting on the reducer 1 as possible. This allows the rigidity of the reducer 1 to be increased.

[0043] The carrier 3 includes two carrier plates 11, 12 and a pillar portion 14 connecting the two carrier plates 11, 12. By configuring the carrier 3 in this manner, it is possible to easily form the carrier 3 so as to satisfy at least the first condition. In turn, this makes it easier to increase the rigidity of the reducer 1. By forming the carrier 3 so as to satisfy the second condition, the connecting portion 22 can protrude further in the circumferential direction compared to when the first condition is satisfied. This allows more carriers 3 to be present between the planetary shafts 5 that are adjacent in the circumferential direction. Therefore, the carriers 3 can further bear the moment load acting on the reducer 1. This ensures that the rigidity of the reducer 1 can be increased.

[0044] When the reducer 1 has an even number of planetary shafts 5 (first planetary gears 27, second planetary gears 28) as in this embodiment, the area that is less susceptible to moment loads becomes large (see, for example, FIG. 3). For this reason, the above configuration can be suitably used when the number of planetary shafts 5 is an even number.

[0045] The pillar portion 14 includes a pillar portion main body 21 and a connecting portion 22. The connecting portion 22 is disposed radially inward of the planetary shaft 5. That is, in a structure such as the reducer 1, which has a first planetary gear 27 that meshes with the sun gear 24 and a second planetary gear 28 that meshes with the internal teeth 7a separately, a space is formed radially inward of the second planetary gear 28. The connecting portion 22 is disposed by effectively utilizing this space. Therefore, the connecting portion 22 can be formed around the entire circumference without increasing the size of the reducer 1. The rigidity of the reducer 1 can be more reliably increased.

[0046] The outer surface 22b of the connecting portion 22 on the radially outer side is formed in an arc shape so as to avoid the second bearing housing 16. Loads other than moment loads are also applied to the connecting portion 22. By forming the outer surface 22b of the connecting portion 22 in an arc shape, it is possible to prevent stress from being applied locally to the connecting portion 22. As a result, the rigidity of the reducer 1 can be further increased.

[0047] The present invention is not limited to the above-described embodiment, and includes various modifications to the above-described embodiment without departing from the spirit of the present invention. For example, in the above embodiment, the carrier 3 is described as being configured with two carrier plates 11, 12 that overlap in the axial direction and pillar portions 14 formed on each of the carrier plates 11, 12. However, this is not limited thereto, and the carrier 3 may be configured to rotatably support the sun shaft 4 and the planetary shafts 5. The carrier 3 may be configured to satisfy the first and second conditions described above.

[0048] In the above embodiment, the carrier 3 is rotatably supported by the internal gear 2. However, this is not limiting, and the carrier 3 may be rotatably provided relative to the internal gear 2. The carrier 3 may also be rotatably supported by a member separate from the internal gear 2.

[0049] In the above-described embodiment, the speed reducer 1 has been described as having four planetary shafts 5 (first planetary gears 27, second planetary gears 28). However, this is not limited to this, and the number of planetary shafts 5 may be two or more. The number of planetary shafts 5 is not limited to an even number, and may be an odd number. Even in such a case, the same effects as those of the above-described embodiment can be achieved.

[0050] Among the embodiments disclosed in this specification, those that are comprised of multiple objects may be integrated, and conversely, those that are comprised of a single object may be separated into multiple objects. Regardless of whether they are integrated, it is sufficient that they are configured to achieve the object of the invention. [Explanation of symbols]

[0051] 1...Reducer 2...Internal gear 3. Career 4…Sun axis 5...Planetary shaft 7a…Internal teeth 11...First carrier plate (carrier plate) 12...Second carrier plate (carrier plate) 14...Column part 21...Column body 22...Connection part 22b…Outer surface (side) 24...Sun gear 27...First planetary gear 28...Second planetary gear A1...Carrier axis (carrier rotation axis) A2...Planet axis (rotation axis of the planetary shaft relative to the carrier (carrier plate)) L1…first straight line L2…Second straight line L3…Third straight line S1,S2,S3,S4...area

Claims

1. an internal gear having internal teeth; A carrier rotatably provided with respect to the internal gear; a sun shaft that is disposed coaxially with a rotation axis of the carrier, rotatably supported by the carrier, and has a sun gear; a plurality of planetary shafts provided in a circumferential direction around a rotation axis of the carrier, the planetary shafts being rotatably supported by the carrier and revolving around the sun shaft; Equipped with The planetary shaft is a first planetary gear meshed with the sun gear; A second planetary gear meshed with the internal teeth; Equipped with the carrier is present between two of the planetary shafts adjacent to each other in the circumferential direction, and is present in an area between two second straight lines that are parallel to a first straight line connecting a rotation axis of the carrier and a rotation axis of the planetary shaft relative to the carrier, and are tangent to a tip circle diameter of the second planetary gear; reducer.

2. The carrier is Two carrier plates are supported rotatably on both axial sides of the internal teeth of the internal gear, with the carrier plates sandwiching the internal teeth of the internal gear; A column portion connecting the two carrier plates; Equipped with The sun shaft and the planetary shafts are rotatably supported by the two carrier plates, The pillar portion is disposed between two of the planetary shafts adjacent to each other in the circumferential direction, and is formed in a region between two second straight lines that are parallel to a first straight line connecting a rotation axis of the carrier and a rotation axis of the planetary shaft relative to the carrier plate, and are tangent to a tip circle diameter of the second planetary gear. The reducer according to claim 1 .

3. the carrier is present in a region between two third straight lines that pass through a rotation axis of the carrier and are tangent to a tip circle diameter of the second planetary gear; The reducer according to claim 1 or 2.

4. An even number of said planetary shafts are provided. The reducer according to claim 1 or 2.

5. The column portion is A pillar body disposed between two planetary shafts adjacent to each other in the circumferential direction; A connecting portion connecting two adjacent column bodies in the circumferential direction; Equipped with The connecting portion is disposed radially inward of the internal gear relative to the planetary shaft. The reducer according to claim 2.

6. A side surface of the connecting portion on the planetary shaft side is formed in an arc shape when viewed in the axial direction. The reducer according to claim 5.

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