JP4879142B2 - Reduction gear - Google Patents

Description

  The present invention relates to a reduction gear. In particular, a speed reduction device including a cylindrical member having inner teeth formed on the inner periphery, and a carrier that is rotatably supported coaxially with the cylindrical member and has an external gear that engages with the inner teeth. About.

Patent Document 1 discloses an eccentric rocking type speed reducer. The reduction gear has a cylindrical member and a carrier. Internal teeth are formed on the inner periphery of the cylindrical member. In the following description, the cylindrical member may be referred to as an internal gear. The carrier is disposed coaxially with the cylindrical member, and is rotatably supported by the cylindrical member via the first bearing. An external gear that engages with the internal teeth of the cylindrical member is supported by the carrier. The external gear rotates eccentrically with respect to the axis of the internal gear. The external gear is disposed inside the internal gear and meshes with the internal gear. When the external gear rotates eccentrically, the carrier rotates with respect to the internal gear. When the external gear rotates eccentrically only once, the external gear and the internal gear relatively rotate (spin) by an angle corresponding to the difference in the number of teeth between the external teeth and the internal teeth. The carrier rotates relative to the internal gear as the external gear rotates. As a result, the speed at which the carrier and the internal gear rotate relative to the speed at which the external gear rotates eccentrically can be reduced.
The speed reduction device of Patent Document 1 fixes one of two members (for example, two links of a robot arm) to be relatively rotated to a cylindrical member and the other to a carrier. In this specification, the two members that the speed reducer relatively rotates are referred to as rotated members.

JP 2007-278355 A

In the reduction gear of Patent Document 1, the two rotated members that are rotated relative to each other are only supported by the first bearing interposed between the carrier and the cylindrical member. That is, the load (including moment) acting between the two rotated members is supported by the first bearing.
On the other hand, since the external gear supported by the carrier meshes with the internal teeth of the cylindrical member, high accuracy is required for the assembly accuracy of the carrier and the cylindrical member. The first bearing between the carrier and the cylindrical member is required to maintain high assembly accuracy while supporting a load acting between the two rotated members. Therefore, the first bearing needs to be designed according to the situation in which the speed reducer is used (the magnitude of the load acting between the two rotated members and the assembly accuracy of the carrier and the cylindrical member).
Designing the first bearing according to the usage situation is nothing more than designing the core parts (mainly the cylindrical member and the carrier) of the reduction gear according to the usage situation. That is, in the conventional speed reducer, it is necessary to design the speed reducer for each situation used.
An object of the present invention is to provide a speed reducer capable of sharing a core component for a speed reducer having different load conditions acting between two rotated members.

  If the load (thrust load, radial load, bending moment, etc.) acting between the two rotated members is supported by a component other than the core component, the core component can be shared. For this purpose, a support unit for fixing each rotated member is adopted separately from the speed reduction unit provided with the core parts, and the speed reduction unit and the support unit are configured to be separable. The support unit includes a first support member and a second support member that rotate relative to each other via the second bearing. By adopting a structure in which the rotated member is fixed to each of the first support member and the second support member and the load acting between the rotated members is supported by the second bearing, the load is reduced by the speed reduction unit (in particular, the cylindrical shape). It is possible to prevent direct addition to the member and the carrier. That is, it is not necessary to support the load acting between the rotated members with the first bearing. Therefore, the speed reduction unit may be designed mainly considering the assembly accuracy of the cylindrical member and the carrier. By combining a reduction unit manufactured with the same design with a support unit corresponding to a load condition to be used, a reduction device corresponding to various load conditions can be realized. That is, it is possible to realize a speed reducer that uses a common core component for various load conditions.

The speed reduction device of the present invention includes a speed reduction unit and a support unit. The speed reduction unit includes a cylindrical member and a carrier. Internal teeth are formed on the inner periphery of the cylindrical member. The carrier is coaxially disposed inside the cylindrical member and is rotatably supported by the cylindrical member via the first bearing. The carrier has an external gear that engages with the internal teeth of the cylindrical member. The support unit includes a first support member and a second support member. The first support member is a member for attaching one of the two rotated members to be rotated relative to each other, and is non-rotatably attached to the outer periphery of the cylindrical member of the reduction unit. The second support member is a member for attaching the other rotated member, and is non-rotatably attached to the carrier of the speed reduction unit. The second support member extends radially outward of the carrier and is rotatably supported by the first support member via a second bearing. In the reduction gear device of the present invention, the reduction gear unit and the support unit can be separated.
Note that the speed reduction unit of the present invention is not intended to be an eccentric rocking type speed reduction unit, unlike the speed reduction device of Patent Document 1 described above. For example, a reduction unit of a type in which a planetary gear (external gear) revolves around a sun gear while meshing with an outer ring gear (internal gear), such as a reduction unit using a general planetary gear mechanism. In the reduction unit, the carrier attached to the planetary gear rotates (spins) with respect to the internal gear as the planetary gear revolves. That is, the speed reduction unit of the present invention only needs to be a speed reduction unit in which the carrier rotates with respect to the internal gear as the external gear engaged with the internal teeth of the cylindrical member rotates.

  According to the speed reducer described above, the load acting between the two rotated members can be supported by the support unit. That is, it is possible to prevent a force from acting directly on the speed reduction unit from the rotated member. Even if the load conditions acting between the two rotated members are different, the speed reduction unit including the core component can be shared. It is only necessary to prepare a plurality of types of support units according to the load conditions, and it is not necessary to prepare a plurality of types of reduction units according to the load conditions. The support unit has a simple structure compared to the speed reduction unit. Therefore, it is possible to significantly reduce the manufacturing cost of the reduction gear by providing a plurality of types of support units rather than preparing a plurality of types of reduction units according to the load conditions.

In the speed reducer according to the present invention, it is preferable that the second bearing is a bearing that restrains movement of both the first support member and the second support member in both the relative axial direction and the radial direction. In other words, the second bearing preferably has the functions of a radial bearing and a thrust bearing.
If the second bearing is a bearing that restrains both axial and radial movements, the relative positions of the first support member and the second support member even if a load is applied between the two rotated members. A relationship can be maintained. More specifically, the axial distance and the radial distance between the first support member and the second support member can be kept constant. As a result, the positional relationship between the two rotated members fixed to the speed reducer can be maintained at a constant distance.
The second bearing may be composed of two bearings, a radial bearing and a thrust bearing.

It is preferable that any one of the coupling between the cylindrical member and the first support member and the coupling between the carrier and the second support member is a coupling that allows the cylindrical member to move in the axial direction.
In this case, an event in which the load of the rotated member is applied to the deceleration unit can be more efficiently prevented. Specifically, if the cylindrical member and the first support member are allowed to move in the axial direction, even if a thrust load acts on the first support member from the rotated member, the load is the cylindrical member. Does not work. Therefore, it can prevent that the assembly | attachment precision of a cylindrical member and a carrier falls. Similarly, if the carrier and the second support member are allowed to move in the axial direction, even if a thrust load acts on the second support member from the rotated member, the load does not act on the carrier. Therefore, it can prevent that the assembly | attachment precision of a cylindrical member and a carrier falls.

  According to the speed reducer of the present invention, it is possible to provide a speed reducer capable of sharing a core component when manufacturing a speed reducer with different load conditions acting between two rotated members. As a result, it is not necessary to prepare a plurality of types of core parts according to the load conditions, and the manufacturing cost of the reduction gear can be greatly reduced.

The features of each embodiment are described below.
(First Feature) A first through hole is formed at a position offset from the center of the external gear, and a columnar portion formed in the carrier passes through the first through hole.
(Second feature) The speed reduction unit includes a crankshaft having an eccentric body, a second through hole is formed at a position offset from the center of the external gear, and the eccentric body is fitted into the second through hole. is doing.
(Third feature) The crankshaft is rotatably supported by the carrier by a third bearing.

Embodiments will be described with reference to the drawings.
(First embodiment)
FIG. 1 shows a cross-sectional view of a reduction gear device 100 of the present embodiment. In addition, hatching of some components is abbreviate | omitted for clarification of drawing.
The speed reduction device 100 is a speed reduction device for a robot that is fixed to the base 62 and rotates the arm 72. The base 62 and the arm 72 are members that are relatively rotated by the speed reducer 100 and may be referred to as a rotated member.
As shown in FIG. 1, the speed reduction device 100 includes a speed reduction unit 50 and a support unit 64.
The deceleration unit 50 roughly includes a cylindrical member 56 and carriers (upper carrier 16X and lower carrier 16Y). Note that the upper carrier 16X and the lower carrier 16Y are coupled to each other to form one carrier. In the present specification, the upper carrier 16X and the lower carrier 16Y may be collectively referred to as the carrier 16 for easy understanding of the description. Inner teeth 48 are formed on the inner periphery of the cylindrical member 56. Actually, the internal teeth 48 are formed of a plurality of cylindrical pins (internal tooth pins). A plurality of internal teeth pins are rotatably fitted in each of a plurality of grooves (not shown) formed in the circumferential direction on the inner surface of the cylindrical member 56. Therefore, the cylindrical member 56 can also be referred to as an internal gear provided with internal teeth (internal tooth pins) 48. In the following description, the cylindrical member 56 may be referred to as an internal gear 56. Further, a protrusion 58 is formed on the outer periphery of the cylindrical member 56. The carrier 16 is coaxially arranged inside the cylindrical member 56 and has a disk shape. The carrier 16 is rotatably supported by the cylindrical member 56 via a pair of angular ball bearings (first bearings) 10X and 10Y. The carrier 16 includes external gears 42X and 42Y. The external gears 42 </ b> X and 42 </ b> Y are engaged with the internal teeth 48 of the cylindrical member 56.

The deceleration unit 50 will be described in more detail.
First, the relationship between the carrier 16 and the external gears 42X and 42Y will be described. A columnar portion 18 is formed on the upper carrier 16X. The columnar portion 18 and the lower carrier 16Y are fixed by the bolts 54. The upper carrier 16X and the lower carrier 16Y are arranged at positions that sandwich the external gears 42X and 42Y from the axial direction. On the other hand, the first through hole 20X is formed at a position offset from the center of the external gear 42X. A plurality of first through holes 20X are formed along the circumferential direction of the external gear 42X (not shown). A first through hole 20Y is formed at a position offset from the center of the external gear 42Y. A plurality of first through holes 20Y are also formed along the circumferential direction of the external gear 42Y. The columnar portion 18 of the upper carrier 16X passes through the first through holes 20X and 20Y. Therefore, when the external gears 42X and 42Y rotate with respect to the internal gear 56, the carrier 16 rotates with respect to the internal gear 56 as the external gears 42X and 42Y rotate. Since the carrier 16 and the external gears 42 </ b> X and 42 </ b> Y rotate integrally with the internal gear 56, the carrier 16 has external gears 42 </ b> X and 42 </ b> Y that engage with the internal teeth 48 of the cylindrical member 56. It can be said.

  An upper carrier through hole 22X is formed around the axis of the upper carrier 16X, and a lower carrier through hole 22Y is formed around the axis of the lower carrier 16Y. A central through hole 28X is formed at the center of the external gear 42X, and a central through hole 28Y is formed at the center of the external gear 42Y. A motor gear 26 (described later) passes through the carrier through holes 22X and 22Y and the center through holes 28X and 28Y. A second through hole 32X is formed at a position offset from the center of the external gear 42X. A plurality of second through holes 32X are formed along the circumferential direction of the external gear 42X (not shown). The second through hole 32Y is formed at a position offset from the center of the external gear 42Y. A plurality of second through holes 32Y are also formed along the circumferential direction of the external gear 42Y. The number of teeth of the external gears 42X and 42Y is smaller than the number of teeth of the internal gear 56 (the number of internal teeth pins 48).

  The speed reduction unit 50 further includes a crankshaft 36 having eccentric bodies 34X and 34Y. An input gear 30 is fixed to the crankshaft 36. The input gear 30 meshes with the motor gear 26 fixed to the output shaft (not shown) of the motor 52. Therefore, when the output shaft of the motor 52 rotates, the crankshaft 36 rotates. When the crankshaft 36 rotates, the eccentric bodies 34X and 34Y rotate eccentrically around the axis of the crankshaft 36.

The relationship between the crankshaft 36 and the carrier 16 and the relationship between the crankshaft 36 and the external gears 42X and 42Y will be described.
The crankshaft 36 is rotatably supported by the carrier 16 by a pair of tapered roller bearings (third bearings) 38X and 38Y. The pair of tapered roller bearings 38X and 38Y restrains the crankshaft 36 from moving in the thrust direction (axial direction) and the radial direction (direction orthogonal to the axial direction).
As described above, the crankshaft 36 has the eccentric bodies 34X and 34Y. The eccentric body 34X is fitted in the second through hole 32X formed in the external gear 42X. More precisely, the eccentric body 34X is fitted into the second through hole 32X via the needle roller bearing 40X. The eccentric body 34Y is fitted into the second through hole 32Y via the needle roller bearing 40Y.

The support unit 64 includes an upper first support member 4X, a lower first support member 4Y, an upper second support member 2X, and a lower second support member 2Y. Upper first support member 4 </ b> X and lower first support member 4 </ b> Y are fixed by bolts 60. The upper second support member 2X and the lower second support member 2Y are fixed by bolts 44 and 70. In the following description, the upper first support member 4X and the lower first support member 4Y are collectively referred to as a first support member 4, and the upper second support member 2X and the lower second support member 2Y are collectively referred to as a second support. It may be called the member 2.
One rotated member (base portion) 62 is attached to the first support member 4 by a bolt 46. In other words, the first support member 4 is fixed to the base portion 62 by the bolt 46. A groove 6 is formed on the inner periphery of the upper first support member 4X. The protrusion 58 formed on the outer periphery of the cylindrical member 56 and the groove 6 formed on the inner periphery of the upper first support member 4X are spline-coupled. That is, the first support member 4 is attached to the outer periphery of the cylindrical member 56 so as not to rotate. In addition, the 1st support member 4 and the cylindrical member 56 can move relatively to an axial direction.
The other rotating member (arm) 72 is attached to the second support member 2. The second support member 2 is fixed to the upper carrier 16X by the bolts 12 and 14. Therefore, the second support member 2 cannot rotate with respect to the carrier 16. The second support member 2 extends radially outward of the carrier 16, and is rotatably supported by the first support member 4 by a pair of angular ball bearings (second bearings) 68X and 68Y. . The pair of angular ball bearings 68X and 68Y restrains the second support member 2 from moving in the thrust direction and the radial direction.

The features of the reduction gear 100 will be described.
As described above, of the two rotated members 62 and 72 that are relatively rotated, one rotated member (base) 62 is attached to the first support member 4 and the other rotated member (arm) 72 is the second. It is attached to the support member 2. Therefore, a load (a thrust load, a radial load, a bending moment, etc.) acting between the two rotated members 62 and 72 can be supported by the pair of second bearings 68X and 68Y. It is not necessary to support the load acting between the two rotated members 62 and 72 by the first bearings 10X and 10Y. As a result, when designing the speed reduction unit 50, the assembly accuracy of the internal gear 56 and the carrier 16 may be mainly considered. More specifically, it is not necessary to increase the size of the first bearings 10X and 10Y even if the load acting between the two rotated members 62 and 72 increases. When the load acting between the two rotated members 62 and 72 increases, the size of the second bearings 68X and 68Y may be increased. That is, only the support unit 64 needs to be designed according to the load acting between the two rotated members 62 and 72. The support unit 64 has a simpler structure than the speed reduction unit 50. Therefore, the support unit 64 is designed according to the load acting between the two rotated members 62, 72 rather than designing the deceleration unit 50 according to the load acting between the two rotated members 62, 72. This can reduce the manufacturing cost of the reduction gear. In the reduction gear 100, the protrusion 58 formed on the internal gear 56 and the groove 6 formed on the first support member 4 are spline-coupled. Then, the reduction unit 50 and the support unit 64 can be separated. Support units 64 having different sizes can be attached to the same deceleration unit 50.
In the speed reduction device 100, it is not necessary to prepare a plurality of speed reduction units 50 according to the magnitude of the load acting between the two rotated members 62 and 72. In other words, by combining a reduction unit 50 manufactured with the same design with a support unit corresponding to a load condition to be used, it is possible to realize a reduction gear device corresponding to various load conditions.

The operation mechanism of the reduction gear 100 will be described. In the following description, alphabetical subscripts may be omitted when describing an event common to substantially the same parts having a plurality of parts.
As described above, when the output shaft of the motor 52 rotates (autorotates), the crankshaft 36 rotates through the input gear 30. Depending on the difference in the number of teeth between the motor gear 26 and the input gear 30, the rotation of the output shaft of the motor 52 is decelerated and transmitted to the crankshaft 36. When the crankshaft 36 rotates, the eccentric body 34 rotates eccentrically around the axis of the crankshaft 36. Note that the motor 52 is fixed to the base 62 by a bolt 53, and the motor 52 itself does not rotate. When the eccentric body 34 rotates eccentrically, the external gear 42 rotates eccentrically around the axis of the internal gear 56 along with the eccentric rotation. In other words, the external gear 42 revolves around the axis of the internal gear 56. The external gear 42 revolves around the axis of the internal gear 56 while meshing with the internal gear 56. Therefore, the external gear 42 rotates with respect to the internal gear 56 by a difference in the number of teeth from the internal gear 56.
As described above, the columnar portion 18 of the upper carrier 16 </ b> X passes through the first through hole 20 of the external gear 42. Therefore, when the external gear 42 rotates with respect to the internal gear 56, the carrier 16 also rotates with respect to the internal gear 56. As described above, the eccentric body 34 of the crankshaft 36 is fitted in the second through hole 32 of the external gear 42. Therefore, when the external gear 42 rotates with respect to the internal gear 56, the crankshaft 36 revolves around the axis of the internal gear 56.

  The internal gear 56 is non-rotatably attached to the first support member 4, and the first support member 4 is fixed to the base 62. The carrier 16 is non-rotatably attached to the second support member 2, and the second support member 2 is rotatably supported by the first support member 4. Therefore, when the carrier 16 rotates with respect to the internal gear 56, the arm 72 fixed to the second support member 2 can be rotated with respect to the base 62.

Other features of the reduction gear 100 will be described.
As described above, the protrusion 58 formed on the internal gear 56 and the groove 6 formed on the first support member 4 are spline-coupled. Therefore, the internal gear 56 can move in the axial direction with respect to the first support member 4. For example, even if the positional relationship in the thrust direction between the first support member 4 and the second support member 2 changes due to the thrust load acting between the two rotated members 62 and 72, the internal gear 56 and the carrier 16 It is possible to prevent the positional relationship from changing. Therefore, the assembly accuracy of the internal gear 56 and the carrier 16 can be maintained satisfactorily. Furthermore, the speed reduction unit 50 and the support unit 64 can be assembled only by fixing the second support member 2 and the carrier 16 with the bolts 12 and 14. Therefore, the manufacturing process of the reduction gear 100 can be simplified.
The second support member 2 and the carrier 16 are fixed with bolts 12 and 14. As a result, it is possible to prevent the positional relationship between the deceleration unit 50 and the support unit 64 from changing significantly. For example, in addition to the connection between the internal gear 56 and the first support member 4, and also the connection between the carrier 16 and the second support member 2 is a spline connection, the reduction unit 50 can be easily moved in the axial direction inside the support unit 64. It will move. Since the second support member 2 and the carrier 16 are fixed by the bolts 12 and 14, the speed reduction unit 50 is prevented from easily moving in the axial direction inside the support unit 64.
The eccentric direction of the eccentric body 34X and the eccentric body 34Y is symmetric with respect to the axis of the crankshaft 36. Therefore, the external gear 42X and the external gear 42Y are eccentrically symmetrical with respect to the axis of the internal gear 56. As a result, the external gears 42X and 42Y can be rotated with good balance.
The oil seal 8 is disposed between the carrier 16 and the internal gear 56. An oil seal 66 is disposed between the first support member 4 and the second support member 2. The oil seals 8 and 66 can prevent oil introduced into the speed reduction device 100 from leaking outside the speed reduction device 100.

In the speed reduction device 100 of the above embodiment, the connection between the cylindrical member (internal gear) 56 and the first support member 4 is a spline connection. The carrier 16 and the second support member 2 are fixed by bolts 12 and 14. However, both the cylindrical member 56, the first support member 4, and the carrier 16 and the second support member 2 may be fixed with bolts. Even in this case, the load acting between the two rotated members 62 and 72 can be supported by the second bearing (in the above embodiment, a pair of angular ball bearings 68X and 68Y).
Further, in the speed reduction device 100 of the above-described embodiment, the second bearing (a pair of angular ball bearings 68X and 68Y) restrains the movement in both the axial direction and the radial direction between the first support member 4 and the second support member 2. ) Is arranged. However, the 2nd bearing should just be a bearing which restrains the movement to the axial direction of the cylindrical member 56 at least. Even in that case, at least a thrust load can be supported.

(Second embodiment)
FIG. 2 shows a cross-sectional view of the reduction gear device 200 of the present embodiment. The speed reduction device 200 is a modification of the speed reduction device 100, and components that are substantially the same as the speed reduction device 100 may be omitted by attaching the same reference numerals as the speed reduction device 100 to the last two digits. .
In the speed reducer 200, a protrusion 258 is formed on the outer periphery of the upper carrier 216X, and a groove 206 is formed on the inner periphery of the upper second support member 202X. The protrusion 258 and the groove 206 are splined. The carrier 216 (the upper carrier 216X and the lower carrier 216Y) can move in the axial direction with respect to the second support member 202 (the upper second support member 202X and the lower second support member 202Y). Further, the cylindrical member 256 and the upper first support member 204X are fixed by the bolt 280. Therefore, the deceleration unit 250 is prevented from easily moving in the axial direction inside the support unit 264.
Comparing the speed reducer 200 and the speed reducer 100, the speed reducer 200 has a spline connection between the carrier 216 and the second support member 202, and the speed reducer 100 has a spline connection between the tubular member 56 and the first support member 4. It is different only in that it is. Therefore, the speed reduction device 200 has substantially the same function and effect as the speed reduction device 100.
In the reduction gear 200, both the cylindrical member 256 and the first support member 204, and the carrier 216 and the second support member 202 may be fixed with bolts. The second bearing (the pair of angular ball bearings 268X, 268Y) may be a bearing that restrains at least the movement of the cylindrical member 256 in the axial direction.

  Specific examples of the present invention have been described in detail above, but these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above.

In each of the above embodiments, the eccentric oscillating type deceleration unit has been described as an example of the deceleration unit. However, it is not intended that the speed reduction unit of the speed reduction device according to the present invention be limited to the eccentric rocking type speed reduction unit. For example, the speed reduction unit may be a speed reduction unit having a general planetary gear mechanism (a speed reduction mechanism having a sun gear, a planetary gear, and an outer ring gear).
In each of the above embodiments, the rotated member attached to the first support member has been described as the base. That is, the example which rotates the to-be-rotated member attached to a 2nd supporting member with respect to the base was demonstrated. However, the rotated member attached to the second support member may be a base, and the rotated member attached to the first rotating member may be rotated with respect to the base.

  The technical elements described in this specification or the drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technology exemplified in this specification or the drawings achieves a plurality of objects at the same time, and has technical utility by achieving one of the objects.

Sectional drawing of the reduction gear device of 1st Example is shown. Sectional drawing of the speed reducer of 2nd Example is shown.

Explanation of symbols

2 (2X, 2Y), 202 (202X, 202Y): second support member 4 (4X, 4Y), 204 (204X, 204Y): first support member 10X, 10Y, 210X, 210Y: first bearing 16 (16X) , 16Y), 216 (216X, 216Y): carrier 36, 236: crankshaft 42X, 42Y, 242X, 242Y: external gear 48, 248: internal teeth (internal tooth pins)
50, 250: Reduction unit 56, 256: Cylindrical member (internal gear)
64, 264: Support units 68X, 68Y, 268X, 268Y: Second bearing 100, 200: Reduction gear

Claims (3)

It has a deceleration unit and a support unit,
The deceleration unit
A cylindrical member having inner teeth formed on the inner periphery;
A carrier that is coaxially arranged inside the cylindrical member, is rotatably supported by the cylindrical member via a first bearing, and has an external gear that engages with the internal teeth. And
Support unit is
A first support member that is a member for attaching one of the rotated members, and is attached to the outer periphery of the cylindrical member of the speed reduction unit so as not to rotate;
A member for attaching the other rotated member, which is non-rotatably attached to the carrier of the speed reduction unit, extends radially outward of the carrier and is rotatable to the first support member via the second bearing. A second support member supported by
A speed reduction device, wherein the speed reduction unit and the support unit are separable.   The speed reducer according to claim 1, wherein the second bearing is a bearing that restrains relative axial and radial movements of the first support member and the second support member.   The coupling of the tubular member and the first support member, or the coupling of the carrier and the second support member is a coupling that allows the tubular member to move in the axial direction. The reduction gear according to 1 or 2.

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