Reducer

Abstract

To reduce the size of a speed reducer.SOLUTION: A speed reducer includes: a sun gear; an internal gear; and planetary gears which engage with the sun gear and the internal gear. The speed reducer has: a first carrier located at one axial side; and a second carrier located at the other axial side. The plurality of first planetary gears are held in the first carrier. The plurality of second planetary gears are held in the second carrier. One axial end of the second carrier protrudes to the one axial side farther than the other axial end of the first carrier.SELECTED DRAWING: Figure 15

Description

[Technical field]

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

[0002] 2. Description of the Related Art In a reducer employing a planetary gear mechanism, a technique for combining multiple stages of planetary gears in order to adjust the reduction ratio is known. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2009-197882 A [Patent Document 2] Patent No. 4808569 [Patent Document 3] JP 2019-7588 A [Patent Document 4] Patent No. 5846954 [Patent Document 5] Patent No. 5807401 Summary of the Invention [Problem to be solved by the invention]

[0004] Increasing the number of stages of the planetary gears may increase the size of the reducer in the axial direction.

[0005] One object of the present invention is to provide a reducer that can be reduced in size. [Means for solving the problem]

[0006] In one embodiment, the reducer has a sun gear, an internal gear, and planetary gears that mesh with the sun gear and the internal gear. The reducer includes a first carrier located on one axial side, and a second carrier located on the other axial side. A plurality of first planetary gears are held in the first carrier, and a plurality of second planetary gears are held in the second carrier. An end portion of the second carrier on one axial side protrudes further toward the one axial side than an end portion of the first carrier on the other axial side. The second carrier includes a second planetary shaft that is inserted through the radial center of the second planetary gear and supports the second planetary gear, and a pair of bearings that are arranged between the second planetary gear and the second planetary shaft in the radial direction. The second planetary gear includes, on an inner diameter side, a convex portion that protrudes to one axial side and a concave portion that is cut out from the other axial side to the one axial side. The pair of bearings include flanges that protrude radially outward. Of the pair of bearings, the flange of the bearing located on the one axial side faces the convex portion in the axial direction, and the flange of the bearing located on the other axial side faces the concave portion in the axial direction.

[0007] According to one aspect, the size of the reducer can be reduced. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a perspective view illustrating an example of a drive device according to the first embodiment. [Diagram 2] FIG. 2 is a perspective view illustrating an example of a reducer according to the first embodiment. [Diagram 3] FIG. 3 is a side cross-sectional view illustrating an example of the reducer according to the first embodiment. [Figure 4] FIG. 4 is a cross-sectional perspective view illustrating an example of a drive device according to the first embodiment. [Diagram 5] FIG. 5 is another cross-sectional side view showing the example of the reducer in the first embodiment. [Figure 6] FIG. 6 is a diagram showing an example of a carrier to which a bearing is attached in the first embodiment. [Figure 7] FIG. 7 is an exploded perspective view illustrating an example of the carrier in the first embodiment. [Figure 8] FIG. 8 is an exploded perspective view showing an example of an assembly process for the reducer according to the first embodiment. [Figure 9] FIG. 9 is an exploded perspective view illustrating an example of an assembly process for the reducer according to the first embodiment. [Figure 10] FIG. 10 is a perspective view showing an example of the revolving part in the first embodiment. [Figure 11]FIG. 11 is a perspective view showing an example of a reducer in the first modified example. [Figure 12] FIG. 12 is a side cross-sectional view showing an example of a reducer according to a first modified example. [Figure 13] FIG. 13 is a cross-sectional perspective view showing an example of the revolving part in the first modified example. [Figure 14] FIG. 14 is a perspective view showing an example of a carrier in the first modified example. [Figure 15] FIG. 15 is a cross-sectional perspective view illustrating an example of a reducer according to the second embodiment. [Figure 16] FIG. 16 is an exploded perspective view illustrating an example of a reducer according to the second embodiment. [Figure 17] FIG. 17 is a perspective view showing an example of attachment of the second carrier to the first carrier in the second embodiment. [Figure 18] FIG. 18 is a perspective view showing an example of a second carrier attached to a first carrier in the second embodiment. [Figure 19] FIG. 19 is an exploded perspective view illustrating an example of the second carrier in the second embodiment. [Figure 20] FIG. 20 is a cross-sectional view showing an example of a reducer according to the second modified example. [Figure 21] FIG. 21 is a cross-sectional perspective view showing an example of a reducer according to the second modified example. [Figure 22] FIG. 22 is a side cross-sectional view showing an example of a reducer according to the second modified example. [Diagram 23] FIG. 23 is a perspective view showing an example of a reducer in the third modified example. [Figure 24] FIG. 24 is a side cross-sectional view showing an example of a reducer according to the third modified example. [Diagram 25] FIG. 25 is a sectional perspective view showing an example of a planetary gear according to the third modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment of the reducer disclosed in the present application will be described in detail with reference to the drawings. Note that the dimensional relationship between elements in the drawings, the ratio between elements, etc. may differ from reality. The drawings may also include parts with different dimensional relationships and ratios. In order to make the description easier to understand, each drawing may show a coordinate system in which the direction in which an output shaft 98 described later extends is the axial direction, and the direction in which the output shaft 98 rotates is the circumferential direction.

[0010] (First embodiment) First, the drive device in the first embodiment will be described with reference to Fig. 1. Fig. 1 is a perspective view showing an example of the drive device in the first embodiment. As shown in Fig. 1, the drive device 1 in this embodiment includes a reducer 2 and a motor 9. The reducer 2 includes a connecting portion 10 and a main body portion 20. In the following, the side where the motor 9 is located may be referred to as the negative side in the axial direction, and the side where the reducer 2 is located may be referred to as the positive side in the axial direction.

[0011] The main body 20 of the reducer 2 is connected to the motor 9 via a connecting portion 10. More specifically, the connecting portion 10 is fixed to the motor 9 by a plurality of first screws 91 shown in Figs. 1 to 3, and is fixed to the main body 20 by a plurality of second screws 92. Fig. 2 is a perspective view showing an example of the reducer in the first embodiment. Fig. 3 is a side cross-sectional view showing an example of the reducer in the first embodiment. Fig. 3 shows a cross section cut along a plane PA shown in Fig. 2. In the following, when the four first screws 91 are to be expressed separately, they may be referred to as first screws 91a to 91d, and when the eight second screws 92 are to be expressed separately, they may be referred to as second screws 92a to 92h.

[0012] As shown in Fig. 3, the first screw 91 is inserted into a through hole 19 formed in the connecting portion 10 and fixed to a thread groove 99 formed in the motor 9 shown in Fig. 1. The second screw 92 is inserted into a through hole 1u formed in the connecting portion 10 and fixed to a thread groove 2v formed in the main body portion 20. In this embodiment, a through hole 29 is formed in the main body portion 20 at a position axially opposite to the through hole 19 of the connecting portion 10, as shown in Fig. 3.

[0013] In this embodiment, as shown in Fig. 3, for example, a size (length in the axial direction) L3 of the first screw 91 is smaller than an interval I1 in the axial direction between the through hole 19 of the connecting portion 10 and the through hole 29 of the main body portion 20. In this embodiment, for example, the length of the interval I1 is 5 mm, and the length L3 of the first screw 91 is 16 mm. In this case, the connecting portion 10 and the main body portion 20 are fixed after, for example, four first screws 91 are inserted into the through holes 19 of the connecting portion 10. In addition, the through holes 29 are formed so that the radial and circumferential positions of the through holes 29 are substantially the same as the radial and circumferential positions of the through holes 19.

[0014] In this configuration, as shown in Fig. 3, the tool T00 is inserted into the through hole 29 from the positive axial direction, so that the coupling portion 10 and the main body portion 20 are fixed together, and then the first screw 91 can be fastened. With this configuration, the axial length can be reduced, particularly in the reducer 2 having only one planetary gear stage. In this case, since the interval I1 is sufficiently smaller than the dimension of the tool T00, the reducer 2 can be fixed to the motor 9 without using a special tool or going through a special process. Note that the inner diameter R1 of the through hole 29 is, for example, larger than the outer diameter of the tool T00 and smaller than the inner diameter R2 of the through hole 19.

[0015] Next, a configuration for transmitting a driving force in this embodiment will be described. Fig. 4 is a cross-sectional perspective view showing an example of a driving device in the first embodiment. Fig. 1 shows a cross section taken along line AA in Fig. 4. An adapter 89 shown in Fig. 4 rotatably connects an output shaft 98 of the motor 9 and the sun gear 84. As a result, the driving force of the motor 9 is transmitted to the sun gear 84 via the output shaft 98 and the adapter 89.

[0016] 4, the adapter 89 in this embodiment is disposed, for example, on the inner periphery side of the coupling portion 10. Note that, as will be described later, the output shaft of the motor may be coupled to the sun gear 84, for example, by being press-fitted into the inner diameter side of the sun gear 84. Also, the output shaft and the sun gear 84 may be molded to be integrated by cutting the axial end of the output shaft of the motor.

[0017] The sun gear 84 transmits a driving force to the planetary gear 40 by meshing with the planetary gear 40 shown in FIG. 5. FIG. 5 is another side cross-sectional view showing an example of the reducer in the first embodiment. FIG. 5 shows a cross-section taken along line AA in FIG. 1. In this embodiment, the planetary gear 40 is rotatably held by the carrier 30 via the planetary shaft 48 as shown in FIG. 5. As shown in FIG. 5, the planetary gear 40 is rotatably supported by the planetary shaft 48 via the bearing 41. In this embodiment, for example, a roller bearing is used for the bearing 41. Note that the bearing 41 may be, for example, a full roller bearing without a cage.

[0018] A bearing 51 shown in Fig. 6 is mounted on the carrier 30 shown in Fig. 5. Fig. 6 is a diagram showing an example of a carrier on which a bearing is mounted in the first embodiment. In this embodiment, three planetary gears 40 are held on the carrier 30. In the following description, when the three planetary gears 40 need to be distinguished from one another, they may be referred to as planetary gears 40a to 40c, respectively.

[0019] As shown in Fig. 6, the carrier 30 in this embodiment includes a first member 31 and a second member 32. As shown in Fig. 7, the first member 31 and the second member 32 are assembled to face each other in the axial direction. Fig. 7 is an exploded perspective view showing an example of the carrier in the first embodiment. As shown in Fig. 7, the first member 31 includes an outer ring 33 and a coupling surface 37. The second member 32 includes an outer ring 34 and a support pillar 38. As shown in Fig. 7, the support pillar 38 is formed at a position adjacent to the planetary gear 40 in the circumferential direction.

[0020] The three planetary gears 40 in this embodiment are held by the carrier 30 after the bearings 51 are attached to the carrier 30. More specifically, the bearings 51 are attached to the outer ring 34 of the second member 32 of the carrier 30 from the positive axial direction side. The first member 31 and the second member 32 are assembled after the bearings 51 are attached to the second member 32. With this configuration, the bearings 51 can be formed so that the outer diameter of the bearings 51 is located on the outer diameter side of the tips of the teeth of the planetary gears 40 in the radial direction.

[0021] As shown in Fig. 5, the first member 31 has a through hole 3s and a screw groove 3v, and the second member 32 has through holes 3u, 3t, and 3z. As shown in Fig. 7, the through hole 3u is formed so as to penetrate the support 38 in the axial direction. The planetary shaft 48 shown in Fig. 5 is inserted into the through holes 3s and 3t. The first member 31 and the second member 32 are positioned and assembled by the planetary shaft 48.

[0022] 5, an internal gear 24 is formed on the inner periphery side of the main body 20. The planetary gears 40, which rotate in conjunction with the sun gear 84, mesh with the internal gear 24 and revolve along the internal gear 24. At that time, the carrier 30, which holds the planetary gears 40 via planetary shafts 48, rotates in conjunction with the revolution of the planetary gears 40. Note that the internal gear 24 in this embodiment is fixed to the main body 20 and does not rotate regardless of the revolution or rotation of the planetary gears 40.

[0023] As shown in Fig. 7, an outer thread 35 is formed in the outer ring 33 of the first member 31, and a flange 36 is formed in the outer ring 34 of the second member 32. A nut 53 shown in Fig. 5 is attached to the outer thread 35. A bearing 51 attached from the positive axial direction side is supported by the flange 36.

[0024] In this embodiment, the first member 31 and the second member 32 are fixed to each other by third screws 93, as shown in Fig. 7. The three third screws 93a to 93c are inserted into through holes 3u formed in the second member 32, and fixed to respective thread grooves 3v formed in the first member 31. The third screws 93 are an example of a locking member.

[0025] As described above, the carrier 30 in this embodiment is composed of two members, the first member 31 and the second member 32. The first member 31 and the second member 32 are positioned by the planetary shaft 48. This configuration improves the workability and assembly properties of the carrier 30, and also makes it possible to suppress deterioration in the accuracy of the planetary gears 40.

[0026] As shown in FIG. 6, the bearing 51 is attached to the carrier 30, and the planetary gear 40 is aligned and assembled. Then, the carrier 30 is inserted into the main body 20 from the negative axial direction side as shown by the arrow in FIG. 8. FIG. 8 is an exploded perspective view showing an example of an assembly process of the reducer in the first embodiment. A part of the first member 31 of the carrier 30 inserted into the main body 20, including the outer thread 35, protrudes in the positive axial direction from the end of the main body 20 on the positive axial direction side as shown in FIG. 9. FIG. 9 is an exploded perspective view showing an example of an assembly process of the reducer in the first embodiment. Then, as shown by the arrow in FIG. 9, a bearing 52 and a nut 53 are further attached to the first member 31 of the carrier 30 inserted into the main body 20.

[0027] In this embodiment, the bearing 52 is attached to the outer ring 33 of the first member 31 from the positive axial direction side. In this embodiment, the bearings 51 and 52 are formed to have approximately the same radial size. A nut 53 is further attached to the carrier 30 on which the bearing 52 is attached. The nut 53 is an example of an engagement member. In the following, the carrier 30 that holds the planetary gear 40 and to which the bearings 51 and 52 and the nut 53 are attached may be referred to as the revolving part 50.

[0028] Fig. 10 is a perspective view showing an example of the revolving part in the first embodiment. As shown in Fig. 10, the planetary gear 40 is sandwiched between a bearing 51 and a bearing 52 in the axial direction. Although not shown in Fig. 10, the bearing 52 is mounted on the carrier 30 so that the internal gear 24 of the main body 20 is sandwiched between the bearing 51 and the bearing 52 in the axial direction.

[0029] The nut 53 presses the bearings 51 and 52 toward the negative axial direction. In this case, the bearing 51 located on the input side (negative axial direction side) is pressurized by the nut 53 against the receiving portion 25 of the main body 20 and the flange 36 of the second member 32. The bearing 52 located on the output side (positive axial direction side) is pressurized by the nut 53 against the planetary gear 40, the receiving portion 26 of the main body 20, and the internal gear 24.

[0030] According to this configuration, the inner rings of the two bearings 51 and 52 are in contact with the internal gear 24 in the axial direction, and are both supported in the radial direction by the main body 20. This suppresses the occurrence of deflection and the like due to the load accompanying the rotation of the carrier 30.

[0031] In this embodiment, in order to reduce the interval I1 shown in FIG. 3, a portion of the connecting portion 10 on the positive axial direction side is located further to the positive axial direction side than the end of the bearing 51 on the negative axial direction side. That is, the receiving portion 15 formed on the connecting portion 10 faces the bearing 51 in the radial direction as shown in FIG. 5. This allows a portion of the bearing 51 to be further supported in the axial and radial directions by the receiving portion 15 of the connecting portion 10. With this configuration, the load of the carrier 30 is distributed to the connecting portion 10 in addition to the main body portion 20.

[0032] As shown in Fig. 4, a groove 3r for fixing a driven object is formed on the coupling surface 37 of the first member. In this embodiment, a driven object (not shown), such as a robot arm, is fixed to the first member 31 by a screw or the like, and rotates in conjunction with the carrier 30. In this embodiment, as shown in Figs. 4 and 5, a spigot portion 21 for coupling with a driven object or the like is formed on the outer circumferential surface of the main body 20.

[0033] Thus, in this embodiment, the bearings 51 and 52 are assembled so as to sandwich the internal gear 24 in the axial direction. In this configuration, the outer diameter of the bearing 52 on the output side (positive axial direction side) can be made the same as the outer diameter of the bearing 51 on the input side (positive axial direction side). This allows the bearing 51 to tolerate a sufficient load. Also, by adjusting the degree of fastening by the nut 53, the amount of pressure applied to the bearings 51 and 52 can be appropriately adjusted, thereby suppressing inclination of the gears, reducing backlash, and improving the durability of the gears.

[0034] In this embodiment, the carrier 30 is composed of a second member 32 on which the bearing 51 is attached, and a first member 31 on which the bearing 52 is attached. This improves the ease of assembly and workability of the carrier 30 supported at both ends by the two bearings. In addition, the reinforcement by the third screw 93 suppresses loosening of the first member 31 and the second member 32 in the axial direction.

[0035] As described above, the reducer 2 in this embodiment has the sun gear 84, the internal gear 24, and the planetary gear 40 meshing with the sun gear 84 and the internal gear 24. The reducer 2 has two bearings 51 and 52 arranged to sandwich the planetary gear 40 in the axial direction. At least one of the two bearings 51 and 52 is pressurized against the planetary gear 40 in the axial direction by the engagement member 53. In addition, the two bearings 51 and 52 have the same radial size. According to this configuration, the carrier 30 that holds the planetary gear 40 is supported at both ends by the two bearings 51 and 52 that have approximately the same radial size, so that the rigidity of the reducer 2 can be improved. In addition, the amount of pressurization of the bearings 51 and 52 changes depending on the degree of fastening of the nut 53, so that the amount of pressurization can be easily adjusted.

[0036] [Variations] Although the configuration of this embodiment has been described above, the embodiment is not limited to this. For example, the support pillars 38 may be formed on the first member 31 of the carrier 30, not on the second member 32. The number of support pillars 38 is not limited to the above, and may be different from the number of planetary gears 40 included in the carrier 30.

[0037] Also, although an example in which the nut 53 for pressurizing the bearings 51 and 52 is attached to the output side (axial positive side) has been described, the nut may be attached to the input side (axial negative side) as shown in Figs. 11 to 14. Fig. 11 is a perspective view showing an example of a reducer in a first modified example. Fig. 12 is a side cross-sectional view showing an example of a reducer in a first modified example. Fig. 13 is a cross-sectional perspective view showing an example of a revolving part in a first modified example. Fig. 14 is a perspective view showing an example of a carrier in a first modified example. Figs. 12 and 13 show a cross section cut along the plane PB shown in Fig. 11. In the following modified examples and embodiments, the same reference numerals are used for the same parts as those shown in the drawings described above, and duplicated explanations will be omitted.

[0038] As shown in FIG. 11, the driving device A1 in the first modification includes a motor A9 and a reducer A2. As shown in FIG. 14, the carrier A30 in the first modification includes a first member A31 and a second member A32. In the first modification, a flange A36 is formed on the outer ring A33 of the first member A31, and an outer thread A35 is formed on the outer ring A34 of the second member A32. The first member A31 further includes a coupling surface A37, and a recess A3w is further formed in the radial center portion of the first member A31. Note that FIG. 14 shows the carrier A30 without the bearing 52 attached thereto, but when assembling the reducer A2, the bearing 52 is attached to the first member A31, and then the second member A32 is fixed to the first member A31 so that the planetary gear 40 is held between the first member A31 and the second member A32.

[0039] In the first modified example, the bearing 52 is attached to the carrier A30 before the bearing 51 is attached. In the first modified example, the bearing 52 is attached to the outer ring A33 of the first member A31 from the axial negative side. Then, the first member A31 and the second member A32 are combined to hold the three planetary gears 40.

[0040] The carrier A30 on which the bearing 52 is mounted is inserted into the main body A20 from the axial positive side. Then, as shown in FIG. 13, a bearing 51 and a nut 54 are further mounted on the carrier A30 inserted into the main body A20 from the axial negative side. In the first modified example, the bearing 52 is supported in the radial direction by a receiving portion A26 formed on the main body A20. The bearing 51 is supported in the radial direction by a receiving portion A25 formed on the main body A20 and a receiving portion A15 formed on the connecting portion A10. Note that FIG. 13 does not show the internal gear A24 that is sandwiched between the bearing 51 and the bearing 52 in the axial direction.

[0041] In the first modified example, the output shaft A98 of the motor A9 shown in Fig. 11 is press-fitted into the inner diameter side of the sun gear A84 as shown in Fig. 12. The sun gear A84 is inserted into the through hole A3z of the carrier A30 and supported by the recess A3w. With this configuration, the driving force of the motor A9 is transmitted to the planetary gear 40 via the sun gear A84. As shown in Fig. 11, the first screw 91 inserted into the connecting portion A10 is fixed to a screw groove A99 formed in the motor A9.

[0042] In the configuration according to the first modified example, the portion of the sun gear A84 on the negative axial direction side is prevented from protruding from the end portion on the negative axial direction side of the revolving part A50. This allows the thickness (length in the axial direction) L2 of the reducer A2 shown in Fig. 12 to be smaller than the thickness L1 of the reducer 2 shown in Fig. 5 while ensuring the length of the sun gear A84.

[0043] In the first modified example, the nut 54 protrudes toward the connecting part A10 in the axial direction as shown in Fig. 12. In this case, when the connecting part A10 is fixed to the motor A9, the nut 54 is not visible. With this configuration, it is possible to prevent the nut 54 from being subjected to unintended operations such as disassembly after the reducer A2 is assembled.

[0044] Furthermore, in the first modified example, even when the axial length of the adapter 89 is increased to maintain the slip torque of the sun gear A84, the axial length of the reducer A2 can be reduced. However, in the first modified example, it is preferable that the output shaft A98 is inserted through the sun gear A84. With this configuration, the axial length of the reducer A2 can be further reduced while ensuring the axial length of the sun gear A84.

[0045] 11, the main body A20 may have a through hole A2q through which a second screw 92 is inserted, instead of the screw groove 2v in the first embodiment. With this configuration, as will be described later, the thickness (axial length) of the main body A20 can be reduced, and therefore the axial length of the reducer A2 can be made shorter.

[0046] Second Embodiment In the first embodiment, a configuration in which only one stage of planetary gears 40 is provided in the reducer 2 has been described, but the embodiment is not limited to this. For example, a configuration including two or more stages of planetary gears 40 is also possible. Note that, hereinafter, each member such as the planetary gear 40 shown in the first embodiment may be referred to with "first" added thereto, such as "first planetary gear 40."

[0047] In the second embodiment, a speed reducer including a second planetary gear 70 in addition to the first planetary gear 40 as shown in FIG. 15 will be described. FIG. 15 is a cross-sectional perspective view showing an example of a speed reducer in the second embodiment. As shown in FIG. 15, the speed reducer B2 in the second embodiment further includes a second body portion B0 between the connecting portion B10 and the first body portion 20 in the axial direction. In the second embodiment, the second screw 92 is further inserted, for example, into a through hole (not shown) formed in the second body portion B0. This fixes the connecting portion B10, the second body portion B0, and the first body portion B20. In the second embodiment, the bearing 51 may be supported by a receiving portion B5 formed in the second body portion B0 as shown in FIG. 15, instead of the receiving portion 15 of the connecting portion 10 in the first embodiment.

[0048] The reducer B2 includes a revolving section 50 including a first carrier 30 that holds the first planetary gears 40, and further includes a second carrier 60 that holds three second planetary gears 70. As shown in FIG. 15, a second sun gear 85 is inserted into the second carrier 60 from the axial negative side. The second planetary gears 70 rotate in conjunction with the second sun gear 85. An adapter B89 is connected to the second sun gear 85. The adapter B89 is attached to the output shaft of a motor (not shown). As a result, the driving force of the motor is transmitted to the second sun gear 85 via the adapter B89.

[0049] A second internal gear B7 is formed on the inner periphery side of the second main body portion B0. The second planetary gear 70 rotates in conjunction with the second sun gear 85, and thereby revolves in mesh with the second internal gear B7. The second carrier 60 that holds the second planetary gear 70 rotates with the revolution of the second planetary gear 70. In the second embodiment, the first sun gear B84 inserted in the revolving portion 50 rotates in conjunction with the second carrier 60. In the second embodiment, the second carrier 60 disposed on the input side (negative axial direction side) has a smaller effect on backlash than the first carrier 30, and therefore may be a so-called float-type self-aligning carrier that is not supported by bearings.

[0050] In the second embodiment, the second carrier 60 includes a base 61 and a bush 62, as shown in FIG. 16 and FIG. 17. FIG. 16 is an exploded perspective view showing an example of a reducer in the second embodiment. FIG. 17 is a perspective view showing an example of mounting the second carrier to the first carrier in the second embodiment. As shown in FIG. 16 and FIG. 17, the base 61 is formed with a through hole 6p and a through hole 69. The bush 62 is formed with a through hole 6q and a through hole 6z. The second planetary shaft 78 is inserted through the through hole 6p and the through hole 6q. The bush 62 is press-fitted into the base 61 via the second planetary shaft 78. The adapter B89 is press-fitted into the through hole 6z, and the first sun gear B84 is press-fitted into the through hole 69. As a result, the second carrier 60 rotates in conjunction with the rotation of the adapter B89. Also, the first sun gear B84 rotates in conjunction with the rotation of the second carrier 60. The base 61 and the bush 62 are an example of a pair of support members.

[0051] As shown in FIG. 18, a part of the base 61 protrudes in the positive axial direction from the end of the revolving part 50 on the negative axial direction side. FIG. 18 is a perspective view showing an example of the second carrier attached to the first carrier in the second embodiment. As shown in FIG. 18, the end of the base 61 on the positive axial direction side protrudes in the positive axial direction from the end 5P on the negative axial direction side of the revolving part 50 by a length P1. In this case, for example, the base 61 faces the bearing 51 in the radial direction. In this configuration, the axial length can be reduced in a reducer equipped with two-stage planetary gears. Note that, although an example in which the length P1 is substantially the same as the thickness (size in the axial direction) of the base 61 has been described, the relationship between the length P1 and the thickness of the base 61 is not limited thereto. For example, the configuration may be such that only a part of the base 61 protrudes from the end 5P, or a part of the second planetary gear 70 also protrudes from the end 5P.

[0052] As shown in Fig. 19, the second planetary gear 70 is supported by a second planetary shaft 78 via a pair of bearings 72 and 73 in the radial direction, for example. The bearings 72 and 73 are further supported by a wave washer 77 in addition to washers 74 and 75. Fig. 19 is an exploded perspective view showing an example of the second carrier in the second embodiment. In the second embodiment, the bearings 72 and 73 have a smaller diameter than the bearing 41, for example. The bearings 72 and 73 are, for example, ball bearings. The bearings 72 and 73 may also have flanges in the axial direction, for example.

[0053] 19, the three washers 74 are disposed between the base 61 of the second carrier 60 and each of the bearings 72 in the axial direction. The three washers 75 are disposed between the bearings 73 and each of the bushes 62 in the axial direction.

[0054] 19, a wave washer 77 is further disposed between bush 62 and washer 75 in the axial direction. Wave washer 77 is deformed by being pressurized in the positive axial direction by bush 62. As a result, bearings 72 and 73 support planetary gear 70 without any gap in the axial direction, improving the support accuracy of planetary gear 70, improving the durability of the gear, and reducing backlash.

[0055] As described above, the reducer B2 in the second embodiment includes the first carrier 30 located on one axial side, and the second carrier 60 located on the other axial side. A plurality of first planetary gears 40 are housed in the first carrier 30. A plurality of second planetary gears 70 are housed in the second carrier 60. A base portion 61 corresponding to an end portion on one axial side of the second carrier 60 protrudes toward one axial side beyond an end portion 5P on the other axial side of the first carrier 30. This makes it possible to reduce the axial length of the reducer B2.

[0056] [Variations] Although the configuration of this embodiment has been described above, the embodiment is not limited thereto. For example, wave washer 77 may be disposed between base 61 and washer 74 on the positive axial direction side. Also, while the embodiment has been described in which inner diameter R1 of through hole 29 is smaller than inner diameter R2 of through hole 19, the present invention is not limited thereto, and inner diameter R1 and inner diameter R2 may be substantially the same, or inner diameter R1 may be larger than inner diameter R2.

[0057] In addition, the first body portion 20 in the second embodiment is formed with a spigot portion having, for example, substantially the same shape as the spigot portion 21 of the body portion 20 in the first embodiment. In addition, in the first body portion 20, the second screw 92 is fixed to a thread groove having substantially the same shape as the thread groove 2v shown in FIG. 3. However, the shape of the first body portion is not limited to this. For example, as shown in FIGS. 20 to 22, in the first body portion C20, the spigot portion C21 may have a shape cut out in the radial direction, and may have a through hole C2q instead of the thread groove 2v.

[0058] FIG. 20 is a cross-sectional view showing an example of a reducer in the second modified example. FIG. 21 is a cross-sectional perspective view showing an example of a reducer in the second modified example. FIG. 22 is a side cross-sectional view showing an example of a reducer in the second modified example. FIG. 21 shows a cross section cut on a plane PC shown in FIG. 20. FIG. 22 shows a cross section cut on a plane PD shown in FIG. 20. Note that, as shown in FIG. 21, the outer diameter of the second sun gear C85 in the second modified example is larger than the outer diameter of the second sun gear 85 in the second embodiment. In addition, the adapter C89 is also formed to mesh with the second sun gear C85.

[0059] As shown in Fig. 21, the spigot portion C21 formed in the first main body portion C20 in the second modified example further includes a cutout portion C22 whose radial size is smaller than other portions. In the second modified example, the depth Da (radial size) of the cutout portion C22 shown in Fig. 22 is, for example, 2 mm or more, which is within a range that ensures the strength of the first internal gear C24 shown in Fig. 21. With this configuration, the weight of the first main body portion C20 can be reduced (for example, by about 5% of the entire reducer C2), thereby making the reducer C2 lighter.

[0060] In the second modified example, the second screw 92 is fixed to a through hole C2q formed in the first body portion C20. With this configuration, compared to the case where the screw groove 2v is provided, even if the thickness (length in the axial direction) T1 of the first body portion C20 is reduced, the effective screw length (the meshing length between the second screw 92 and the first body portion C20) can be sufficiently ensured. Furthermore, by forming the cutout portion C22 in the spigot portion C21, even when the second screw 92 protrudes from the through hole C2q to the positive axial direction side, the second screw 92 can be prevented from interfering with the spigot portion C21. This allows the reducer C2 to be further lightened in weight.

[0061] Furthermore, in order to ensure the size of the bearing, a ball bearing with a flange may be used for the second planetary gear 70 as described above. However, since it is necessary to check the length of the flange portion of the ball bearing in addition to the axial length of the planetary gear 70, the axial length of the reducer becomes large.

[0062] Therefore, in the third modified example, a configuration in which a convex portion and a concave portion are formed on the second planetary gear will be described. Fig. 23 is a perspective view showing an example of a reducer in the third modified example. Fig. 24 is a side sectional view showing an example of a reducer in the third modified example. Fig. 25 is a sectional perspective view showing an example of a planetary gear in the third modified example. Figs. 24 and 25 show a cross section taken along line DD in Fig. 23. As shown in Fig. 24, the reducer D2 in the third modified example includes a connecting portion D10, a first main body portion A20, and a second main body portion D0.

[0063] As shown in Fig. 24, the second planetary gear D70 in the third modified example has a recess D7a cut from the positive axial direction side to the negative axial direction side, and a protrusion D7b protruding to the negative axial direction side. As shown in Fig. 25, the recess D7a is cut out by a depth (size in the axial direction) L5, and the protrusion D7b protrudes by a length (size in the axial direction) L4. The second planetary gear D70 meshes with the second internal gear D7 formed in the second main body portion D0.

[0064] 25, the bearing D72 in the third modified example has a flange D7o protruding radially outward on the output side (axial positive side). The bearing D73 has a flange D7i protruding radially outward on the input side (axial negative side). The bearings D72 and D73 may be preloaded by a wave washer or the like, similar to the bearings 72 and 73 in the second embodiment. The second planetary shaft D78, which rotatably supports the second planetary gear 70, is press-fitted into the base D61 and bush D62 of the second carrier D60 via the bearings D72 and D73.

[0065] 25, the recessed portion D7a of the second planetary gear D70 holds the flange D7o of the bearing D72 in the axial direction, and the protruding portion D7b of the second planetary gear D70 holds the flange D7i of the bearing D73 in the axial direction.

[0066] According to this configuration, the axial distance L6 between the flanges of the two bearings D72 and D73 can be made larger than the axial length L7 of the tooth tip of the second planetary gear D70, which allows the use of a larger-sized bearing.

[0067] 24, the reducer D2 in the third modified example may include an orbital part A50 to which a nut 54 is attached from the negative axial direction side, and the output shaft of the motor A9 may be press-fitted into the inner diameter side of the second sun gear D85, as in the first modified example. Also, as in the first and second modified examples, the first main body part D20 in the third modified example may be formed with a through hole D2q to which the second screw 92 is fixed, as in the first and second modified examples, as shown in FIG. 23. With this configuration, the thickness (size in the axial direction) of the reducer D2 can be further reduced, as in the first and second modified examples.

[0068] The positions of the recessed portion D7a and the protruding portion D7b formed on the second planetary gear D70 shown in the third modified example are merely examples, and for example, the protruding portion may be formed on the positive axial direction side and the recessed portion may be formed on the negative axial direction side.

[0069] Although the present invention has been described above based on each embodiment and each modification, it goes without saying that the present invention is not limited to each embodiment and each modification, and various modifications are possible within the scope of the gist of the present invention. Such modifications that do not depart from the scope of the gist are also included in the technical scope of the present invention, and this will be clear to those skilled in the art from the description of the claims. [Explanation of symbols]

[0070] 1, A1 driving device, 2, A2, B2, C2, D2 reducer, 9, A9 motor, 10, A10, B10, D10 connecting portion, 15, A15 receiving portion, 19, 1u through hole, 20, A20, B20, C20 main body portion (first main body portion), 21, C21 spigot portion, C22 cutout portion, 24, A24, C24 internal gear (first internal gear), 25, 26, B5 receiving portion, 29, A2q, C2q, D2q through hole, 2v screw groove, 30, A30 carrier (first carrier), 31, A31 first member, 32, A32 second member, 33, A33, 34, A34 outer ring, 35, A35 external screw, 36, A36 flange, 37, A37 Connection surface, 38 Support, 3t, 3s, 3u, 3z, A3z Through hole, A3w Recess, 3v Screw groove, 40 Planetary gear (first planetary gear), 41 Bearing (first bearing), 48 Planetary shaft (first planetary shaft), 50, A50 Orbital part, 51, 52 Bearing, 53, 54 Nut, 60, D60 Second carrier, 61, D61 Base, 62 Bush, 69, 6p, 6q, 6z Through hole, 70, D70 Second planetary gear, 72, 73, D72, D73 Bearing, 74, 75 Washer, 77 Wave washer, 78, D78 Second planetary shaft, 84, A84, B84 Sun gear (first sun gear), 85, C85, D85 Second sun gear, 89, B89, C89 Adapter, 91 First screw, 92 Second screw, 93 Third screw, 98, A98 Output shaft, 99, A99 Thread groove, B0, D0 Second main body, B7, D7 Second internal gear, T00 Tool

Claims

1. A reducer having a sun gear, an internal gear, and a planetary gear meshing with the sun gear and the internal gear, A first carrier is located on one axial side, and a second carrier is located on the other axial side, a plurality of first planetary gears are held on the first carrier; a plurality of second planetary gears are held on the second carrier; an end portion of the second carrier on one axial side protrudes in the one axial direction further than an end portion of the first carrier on the other axial side; The second carrier is A gear is inserted through the radial center of the second planetary gear and supports the second planetary gear. A second planetary shaft; a pair of bearings disposed between the second planetary gear and the second planetary shaft in a radial direction; Equipped with the second planetary gear includes, on an inner diameter side, a convex portion that protrudes to one side in the axial direction and a concave portion that is cut out from the other side in the axial direction to the one side in the axial direction, The pair of bearings each include a flange protruding radially outward, The flange of the bearing located on one axial side of the pair of bearings faces the protruding portion in the axial direction, and the flange of the bearing located on the other axial side faces the recessed portion in the axial direction. reducer.

2. the first carrier is supported by two bearings disposed radially outward of the first carrier and opposed to each other in the axial direction; At least a portion of the second carrier in the axial direction faces at least one of the two bearings in the radial direction. The reducer according to claim 1 .

3. A pair of support members supporting the second planetary gear from both sides in the axial direction, a wave washer is disposed between a bearing located on one axial side of the pair of bearings in the axial direction and a support member located on one axial side of the second carrier; The reducer according to claim 1 or 2.

4. a first member formed on one axial side of the first planetary gear; a carrier formed on the other axial side of the first planetary gear and including a second member that faces the first member and the first planetary gear in the axial direction, the first member and the second member are connected by a first planetary shaft that supports the first planetary gear, the carrier is supported by the two bearings that face each other in the axial direction with the first planetary gear therebetween, The reducer according to claim 2 .

5. the second member includes at least one support pillar that is adjacent to the first planetary gear in the circumferential direction and in contact with the first member in the axial direction and that protrudes to one side in the axial direction, The first member and the second member are fixed by a locking member inserted into the support. The reducer according to claim 4.

6. the first member includes at least one support pillar that is adjacent to the first planetary gear in the circumferential direction and in contact with the second member in the axial direction and that protrudes toward the other axial direction, The first member and the second member are fixed by a locking member inserted into the support. The reducer according to claim 4.

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