Reducer and robot

Abstract

To provide a shaft holding mechanism which can supply a lubricant to a seal member effectively, and to provide a speed reducer.SOLUTION: A shaft holding mechanism according to one embodiment of the invention includes: a case 5 which forms a storage space S in which a lubricant is stored; an input shaft 7 which penetrates through a through hole 36 formed in the case 5 to penetrate through the case 5; a sealing ring 123 which encloses a periphery of the input shaft 7 in the through hole 36 and seals a gap between the input shaft 7 and the case 5; and a bearing 115 which is provided at the opposite side of the storage space S with respect to the seal ring 123 and rotatably supports the input shaft 7 in the through hole 36.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention provides Reducer and robot Regarding. [Background technology]

[0002] Rotating devices used in industrial robots and the like are equipped with a reducer for reducing the drive torque of a motor. This type of reducer includes a case and a plurality of gears housed in the case (see, for example, Patent Document 1 listed below). The case is formed with a through-hole through which the input shaft of the motor passes. A bearing is provided within the through-hole to rotatably support the input shaft.

[0003] Incidentally, a lubricant is sealed inside the case of the reducer to ensure lubrication between the gears, cool the seal members, etc. The leakage of the lubricant to the outside of the case is restricted by a seal member provided inside the through hole. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Utility Model Application Publication No. 59-131641 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the above-mentioned conventional technology, the seal member is located on the outside of the case relative to the bearing, making it difficult for the lubricant to reach the seal member, which can become hot due to frictional heat generated between the seal member and the input shaft.

[0006] The present invention can effectively supply lubricant to the seal member. Reducer and robot to provide. [Means for solving the problem]

[0007] In order to solve the above problems, the present invention employs the following aspects. A shaft holding mechanism according to one aspect of the present invention comprises a base that forms a storage space in which a lubricant is stored, a shaft that penetrates the base through a through hole formed in the base, a sealing member that surrounds the shaft within the through hole and seals the space between the shaft and the base, and a bearing that is located on the opposite side of the sealing member from the storage space and rotatably supports the shaft within the through hole.

[0008] According to this aspect, the flow of lubricant within the housing space can be prevented from being blocked by the bearing. This allows the lubricant to be effectively distributed to the seal member. As a result, the seal member can be prevented from becoming too hot due to frictional heat generated between the seal member and the shaft. In this case, for example, thermal deformation of the seal member can be prevented, and sealing performance can be maintained for a long period of time.

[0009] In the shaft holding mechanism of the above aspect, it is preferable that the seal member is not disposed on the opposite side of the bearing from the accommodation space.

[0010] In the shaft holding mechanism of the above aspect, it is preferable that the shaft is configured to be removable from the base portion while being separated from the seal member, and that the inner diameter of the seal member is smaller than the inner diameter of the bearing.

[0011] In the shaft holding mechanism of the above aspect, it is preferable that a speed reduction mechanism connected to the shaft is provided within the accommodation space.

[0012] In the shaft holding mechanism of the above aspect, it is preferable that a gear connected to the reduction mechanism is provided at the end of the shaft that is located on the storage space side relative to the sealing member, and that the outer diameter of the gear is smaller than the inner diameter of the sealing member.

[0013] In the shaft holding mechanism of the above aspect, it is preferable that a regulating member that regulates movement of the bearing in a direction away from the sealing member is removably provided on the base on the opposite side of the base from the sealing member relative to the bearing. A reducer according to one aspect of the present invention comprises a case that forms an accommodation space in which a lubricant is accommodated, a reduction mechanism portion accommodated within the accommodation space, a shaft that passes through the case through a through hole formed in the case and is connected to the reduction mechanism portion within the case, a sealing member that surrounds the shaft within the through hole and seals the space between the shaft and the case, and a bearing that is provided on the opposite side of the sealing member from the accommodation space and rotatably supports the shaft within the through hole. [Effects of the Invention]

[0014] According to each of the above aspects, the lubricant can be effectively supplied to the seal member. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a cross-sectional view of a reducer according to a first embodiment. [Figure 2] FIG. 2 is an enlarged view of part II in FIG. [Figure 3] FIG. 6 is a cross-sectional view of a reducer according to a second embodiment. [Figure 4] FIG. 10 is a partial cross-sectional view of a reducer according to a third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0016] Next, an embodiment of the present invention will be described with reference to the drawings. In the embodiments and modifications described below, corresponding components will be designated by the same reference numerals, and their description may be omitted. In the following description, expressions indicating relative or absolute arrangements, such as "parallel," "orthogonal," "center," and "coaxial," not only strictly indicate such arrangements, but also indicate a state in which the components are relatively displaced by an angle or distance to such an extent that tolerances or the same functions are obtained.

[0017] (First embodiment) [Reducer 1] FIG. 1 is a cross-sectional view of a reducer 1. As shown in Fig. 1, the reducer 1 is provided at a connecting portion (joint portion) of a pair of rotatably connected arms in, for example, an industrial robot. The reducer 1 reduces and outputs a driving torque input from a motor (not shown). For example, a gripping head or the like is attached to the output side of the reducer 1.

[0018] The reducer 1 includes a case (base) 5, a reduction mechanism 6, and an input shaft 7.

[0019] <Case 5> The case 5 forms an accommodation space S that accommodates the reduction mechanism 6. The case 5 is formed into a cylindrical shape with a bottom as a whole by combining a first case 21 and a second case 22. In the following description, the direction along the axis O1 of the case 5 will be simply referred to as the axial direction, the direction that intersects with the axis O1 as viewed from the axial direction will be referred to as the radial direction, and the direction that rotates around the axis O1 will be referred to as the circumferential direction.

[0020] The first case 21 includes a cylindrical portion 21a and a flange portion 21b. The inner peripheral surface of the cylindrical portion 21a is provided with internal teeth 24. The internal teeth 24 includes a plurality of pin grooves 25 formed on the inner peripheral surface of the cylindrical portion 21a and internal tooth pins 26 housed in each pin groove 25. The pin grooves 25 are open on the inner peripheral surface of the cylindrical portion 21a and extend in the axial direction. The pin grooves 25 are formed at equal intervals in the circumferential direction. The internal tooth pin 26 is formed in a cylindrical shape extending along the axial direction. The internal tooth pin 26 is housed in the pin groove 25 with a portion of it protruding radially inward from the pin groove 25. The internal tooth pin 26 is held in the pin groove 25 so as to be rotatable around an axis parallel to the axis O1. The internal teeth 24 may be formed integrally with the cylindrical portion 21a.

[0021] The flange portion 21b projects radially outward from the axial center of the cylindrical portion 21a.

[0022] The second case 22 closes the opening of the first case 21 from a first axial side. The second case 22 is formed in a cylindrical shape with a bottom that opens toward a second axial side. The first case 21 described above is assembled to the second case 22 with the cylindrical portion 21a fitted into the peripheral wall 31 of the second case 22 and the flange portion 21b abutting against the peripheral wall 31 in the axial direction. A sealant 28 is interposed between the outer peripheral surface of the cylindrical portion 21a and the inner peripheral surface of the peripheral wall 31.

[0023] The bottom wall 32 of the second case 22 projects radially inward from a first axial side edge of the peripheral wall 31. The bottom wall 32 is formed in an annular shape. A support tube 35 is formed on the inner peripheral edge of the bottom wall 32. The support tube 35 is coaxial with the axis O1 and extends to the first axial side. The inside of the support tube 35 defines a through hole 36 that connects the inside and outside of the case 5.

[0024] FIG. 2 is an enlarged view of part II in FIG. As shown in Fig. 2, the inner diameter of the support tube 35 gradually decreases from the first side to the second side in the axial direction. Specifically, the support tube 35 has a large diameter section 37, a medium diameter section 38, and a small diameter section 39 that are connected in the axial direction. A groove 40 is formed in the large diameter section 37. The groove 40 extends around the entire inner circumferential surface of the large diameter section 37. A first step surface 37a connecting the large diameter section 37 and the medium diameter section 38, and a second step surface 38a connecting the medium diameter section 38 and the small diameter section 39, are each formed as flat surfaces perpendicular to the axial direction.

[0025] <Deceleration mechanism section 6> 1, the reduction mechanism 6 includes a carrier 11, a plurality of oscillating gears (a first oscillating gear 12 and a second oscillating gear 13), and a plurality of crankshafts 14. The reduction mechanism 6 maintains its lubricating performance by a lubricant sealed in the accommodation space S.

[0026] The carrier 11 is an output part of the reducer 1. The carrier 11 is provided rotatably around an axis O1 inside the case 5. The carrier 11 of this embodiment includes a first block 41 and a second block 42. The first block 41 is disposed on a first axial side within the case 5. The first block 41 is formed in a disk shape and disposed coaxially with the axis O1. A bearing 43 is interposed between the outer peripheral surface of the first block 41 and the inner peripheral surface of the cylindrical portion 21a. This allows the first block 41 to be supported by the case 5 rotatably about the axis O1.

[0027] A first through-hole 44 is formed in the radial center of the first block 41, penetrating the first block 41 in the axial direction. A plurality of first shaft support holes 45 are formed in the outer periphery of the first block 41. Each first shaft support hole 45 has a tapered portion in which the inner diameter gradually decreases toward the first side in the axial direction. The first shaft support holes 45 are formed at intervals in the circumferential direction.

[0028] The second block 42 is disposed on a second axial side of the first block within the case 5. The second block 42 includes a substrate 50 and a support 51. The substrate 50 is formed in a disk shape and disposed coaxially with the axis O1. The substrate 50 closes an opening located on the second axial side of the first case 21 (tubular portion 21a). A bearing 53 is interposed between the outer peripheral surface of the substrate 50 and the inner peripheral surface of the cylindrical portion 21a. This allows the second block 42 to be supported by the case 5 so as to be rotatable about the axis O1.

[0029] A seal ring 55 is interposed between the outer peripheral surface of the substrate 50 and the inner peripheral surface of the cylindrical portion 21a, on the second axial side (the opposite side to the first block 41) of the bearing 53. The seal ring 55 surrounds the periphery of the substrate 50. The seal ring 55 is in close contact with the outer peripheral surface of the substrate 50 and the inner peripheral surface of the cylindrical portion 21a. As a result, the seal ring 55 blocks the connection between the inside and outside of the case 5 through the opening of the second case 22. The seal ring 55 is configured to be slidable on at least one of the substrate 50 and the cylindrical portion 21a (the substrate 50 in this embodiment) as the substrate 50 rotates.

[0030] A second through hole 57 is formed in the radial center of the substrate 50, penetrating the substrate 50 in the axial direction. The second through hole 57 is sealed by a central cap 58a. A plurality of second shaft support holes 59 are formed in the outer periphery of the substrate 50. Each second shaft support hole 59 has a tapered portion whose inner diameter gradually decreases toward the second side in the axial direction. Each second shaft support hole 59 faces a respective one of the first shaft support holes 45 in the axial direction. The second shaft support holes 59 are sealed by an outer periphery cap 58b.

[0031] The support pillar 51 protrudes from a portion of the base plate 50 located between adjacent second shaft support holes 59 toward the first side in the axial direction. The support pillar 51 is fixed to the first block 41 by bolts 60 or the like while abutting against the first block 41 in the axial direction. This allows the first block 41 and the second block 42 to rotate integrally with respect to the case 5.

[0032] The first oscillating gear 12 and the second oscillating gear 13 are arranged inside the cylindrical portion 21a in an axially overlapping state. The first oscillating gear 12 and the second oscillating gear 13 are formed with an outer diameter slightly smaller than the inner diameter of the cylindrical portion 21a. External teeth 12a are formed on the outer peripheral surface of the first oscillating gear 12. External teeth 13a are formed on the outer peripheral surface of the second oscillating gear 13. The external teeth 12a of the first oscillating gear 12 and the external teeth 13a of the second oscillating gear 13 are respectively engaged with the above-mentioned internal teeth 24 (internal tooth pins 26). The number of teeth of the external teeth 12a, 13a is set to be slightly less (for example, one less) than the number of internal tooth pins 26 (pin grooves 25). It should be noted that the number of oscillating gears may be one.

[0033] A first central hole 62 is formed in the center of the first oscillating gear 12. A second central hole 63 is formed in the center of the second oscillating gear 13. The inner diameter of each of the central holes 62, 63 is equal to the inner diameter of the first through hole 44.

[0034] A plurality of first relief holes 65 are formed in the outer peripheral portion of the first oscillatory gear 12. The first relief holes 65 are formed at intervals in the circumferential direction. A plurality of second relief holes 66 are formed in the outer peripheral portion of the second oscillatory gear 13. The second relief holes 66 are formed at intervals in the circumferential direction at the same pitch as the first relief holes 65. A corresponding support pillar 51 of the above-mentioned plurality of support pillars 51 passes through each of the relief holes 65, 66. The inner diameter of the relief holes 65, 66 is larger than the outer diameter of the support pillar 51. This prevents the operation of the oscillatory gears 12, 13 from being hindered by the support pillar 51.

[0035] First through holes 67 are formed in the outer peripheral portion of the first oscillating gear 12 between adjacent first relief holes 65. Second through holes 68 are formed in the outer peripheral portion of the second oscillating gear 12 between adjacent second relief holes 66. The through holes 67, 68 are arranged at the same pitch as the shaft support holes 45, 46 described above.

[0036] The crankshaft 14 functions as a power transmission section between the carrier 11 and the oscillating gears 12, 13. The crankshaft 14 passes through the corresponding shaft support holes 45, 46 and through holes 67, 68, and is bridged between the first block 41 and the base plate 50. Specifically, the crankshaft 14 includes a main shaft 71, a first eccentric portion 72, a second eccentric portion 73, and a protrusion 74.

[0037] The main shaft 71 extends along an axis O2 parallel to the axis O1. A first axial end of the main shaft 71 is rotatably supported in the first shaft support hole 45 via a bearing 76. A second axial end of the main shaft 71 is rotatably supported in the second shaft support hole 46 via a bearing 77. The bearings 76 and 77 are, for example, angular bearings having cylindrical rollers as rolling elements.

[0038] The first eccentric portion 72 is formed in a portion of the main shaft 71 that is located inside the first through hole 67. The axis O3 of the first eccentric portion 72 is eccentric with respect to the axis O2 of the main shaft 71. The first eccentric portion 72 is rotatably supported inside the first through hole 67 via an eccentric portion bearing 81. The second eccentric portion 73 is formed in a portion of the main shaft 71 that is located inside the second through hole 68. An axis O4 of the second eccentric portion 73 is eccentric with respect to the axis O2 of the main shaft 71. The second eccentric portion 73 is rotatably supported inside the second through hole 68 via an eccentric portion bearing 82. The eccentric portions 72, 73 are shifted in phase by, for example, 180° around the axis O2.

[0039] The protruding portion 74 protrudes from the main shaft 71 toward a first side in the axial direction. A transmission gear 85 is attached to the protruding portion 74.

[0040] <Input shaft 7> 2, the input shaft 7 rotates around an axis O1 in accordance with the rotation of the motor, thereby transmitting the driving torque of the motor to the speed reduction mechanism 6. The input shaft 7 is configured by combining an outer shaft 100, an inner shaft 101, and a gear shaft 102.

[0041] The outer shaft 100 is a hollow round shaft extending along the axis O1. A motor is coupled to the outer shaft 100 from a first axial side. An enlarged portion 110 is formed at a second axial end of the outer shaft 100, the outer diameter of which is larger than that of a central portion of the outer shaft 100. A groove 111 is formed on the outer peripheral surface of the enlarged portion 110. The groove 111 extends over the entire circumferential circumference of the outer peripheral surface of the enlarged portion 110. A protrusion 112 that protrudes radially outward is formed on a portion of the enlarged portion 110 located on the first axial side of the groove 111. The protrusion 112 extends, for example, over the entire circumference of the enlarged portion 110.

[0042] The input shaft 7 is rotatably supported on the case 5 via a bearing 115 interposed between the enlarged portion 110 and the support tube 35. An outer ring 115a of the bearing 115 is inserted into the large-diameter portion 37 of the support tube 35. The outer ring 115a is held between the first step surface 37a and a retaining ring (restricting member) 117 fitted into the groove 40. The retaining ring 117 is formed in an annular shape with a portion of its circumferential direction removed, such as a C-ring or E-ring. The retaining ring 117 is fitted into the groove 40 with its inner circumferential portion protruding from the inner circumferential surface of the large-diameter portion 37. The retaining ring 117 is configured to be elastically deformable so as to expand or contract in the radial direction. Therefore, the retaining ring 117 is configured to be detachable from the groove 40 by contracting it from its natural length using, for example, a tool.

[0043] The second axial end face of the outer ring 115a abuts against the first step face 37a. The first axial end face of the outer ring 115a abuts against the retaining ring 117. This restricts the axial movement of the outer ring 115a relative to the case 5 within the through hole 57.

[0044] The inner ring 115b of the bearing 115 is held between the protrusion 112 of the expanded portion 110 and a retaining ring 119 fitted in the groove 111. Specifically, the expanded portion 110 is inserted inside the inner ring 115b. The retaining ring 119 is fitted in the groove 111 with its inner peripheral portion protruding from the outer peripheral surface of the expanded portion 110. A first axial end face of the inner ring 115b abuts against the protrusion 112. A second axial end face of the inner ring 115b abuts against the retaining ring 119. This restricts axial movement of the inner ring 115b relative to the input shaft 7.

[0045] The inner shaft 101 is a hollow round shaft extending along the axis O1. Specifically, the inner shaft 101 includes a fixed portion 120 and a protruding portion 121 that is connected to the fixed portion 120 on a second side in the axial direction. The fixed portion 120 is fixed inside the outer shaft 100 by press-fitting or the like. However, the inner shaft 101 may be fixed to the outer shaft 100 by a method other than press-fitting (for example, a key or a D-cut) as long as it is configured to be unrotatable relative to the outer shaft 100.

[0046] The protruding portion 121 protrudes from the outer shaft 100 toward a second axial side. The outer diameter of the protruding portion 121 is larger than the outer diameter of the fixed portion 120 and smaller than the outer diameter of the expanded portion 110. A seal ring (sealing member) 123 is interposed between the protruding portion 121 and the medium diameter portion 38 of the support tube 35. The seal ring 123 surrounds the periphery of the protruding portion 121. The inner diameter of the seal ring 123 is smaller than the inner diameter of the bearing 115 (inner ring 115b). The seal ring 123 is in close contact with the outer peripheral surface of the protruding portion 121 and the inner peripheral surface of the medium diameter portion 38. As a result, the seal ring 123 isolates the inside and outside of the case 5 from each other within the through hole 36 on the second axial side (the housing space S side) of the bearing 115. In other words, the bearing 115 is disposed on the atmospheric side relative to the seal ring 123. The seal ring 123 is configured to be able to slide on at least one of the outer circumferential surface of the protruding portion 121 and the inner circumferential surface of the medium diameter portion 38 (the protruding portion 121 in this embodiment) as the input shaft 7 rotates. Note that the axial movement of the seal ring 123 relative to the case 5 is limited between the second step surface 38a and the bearing 115.

[0047] The gear shaft 102 is a solid round shaft extending along the axis O1. The gear shaft 102 includes a fixed portion 130 and an input gear (gear) 131 connected to the fixed portion 130 on a second side in the axial direction. The fixed portion 130 is fixed inside the inner shaft 101 by press fitting or the like.

[0048] The input gear 131 protrudes from the inner shaft 101 to a second side in the axial direction. The input gear 131 meshes with the transmission gear 85 inside the case 5. The maximum outer diameter of the input gear 131 is smaller than the inner diameter of the seal ring 123. The shaft holding mechanism of this embodiment is configured by at least the input shaft 7, the case 5, the bearing 115, and the seal ring 123.

[0049] As shown in FIG. 1 , in the reducer 1 of this embodiment, the input shaft 7 is rotated by the driving torque of the motor, and the driving torque of the motor is input to the reduction mechanism 6 via the transmission gear 85. When each crankshaft 14 rotates in one direction by the torque transmitted to the transmission gear 85, the eccentric portions 72, 73 of the crankshaft 14 rotate eccentrically about the axis O2. As a result, each oscillating gear 12, 13 rotates about the axis O1 while oscillating within the case 5 in accordance with the rotation of the eccentric portions 72, 73. As a result, the external teeth 12a, 13a of the oscillating gears 12, 13 rotate while riding over the internal tooth pins 26, for example, one by one. As the oscillating gears 12, 13 rotate, the carrier 11 rotates about the first axis O1. As a result, the rotation of the crankshaft 14 is decelerated and output as the rotation of the carrier 11.

[0050] As described above, a lubricant is sealed inside the case 5 for the purpose of lubricating the reduction mechanism 6. The lubricant moves inside the case 5 due to the operation of the reduction mechanism 6 (for example, the rotation of the reduction mechanism 6 itself, or the reduction in viscosity due to heat generated in the reduction mechanism 6). In this embodiment, the accommodation space S is sealed by a seal ring 55 interposed between the case 5 and the second block 42, and a seal ring 123 interposed between the case 5 and the input shaft 7. This makes it possible to prevent the lubricant from leaking from the case 5.

[0051] In particular, in this embodiment, the bearing 115 is arranged inside the through hole 57 of the case 5 on the opposite side of the seal ring 123 from the accommodation space S (on the atmospheric side). This configuration can prevent the flow of lubricant inside the case 5 from being blocked by the bearing 115. Therefore, the lubricant can be effectively distributed to the seal ring 123. As a result, the seal ring 123 can be prevented from becoming too hot due to frictional heat generated between the seal ring 123 and the input shaft 7. In this case, for example, thermal deformation of the seal ring 123 can be prevented, and sealing performance can be maintained for a long period of time.

[0052] In this embodiment, a seal ring is not disposed on the opposite side of the bearing 115 from the accommodation space S. According to this configuration, the lubricant can be effectively supplied to all of the seal rings 55, 123 that the reducer 1 has.

[0053] In a conventional configuration in which the seal member is disposed on the outside of the case relative to the bearing, if it becomes necessary to remove the input shaft from the reducer, the seal member must be removed before the input shaft. In this case, there is a risk that the case will be damaged when a jig or the like is inserted between the through hole and the seal member to remove the seal member.

[0054] Here, a method for attaching and detaching the input shaft 7 in the reducer 1 of this embodiment will be described. First, after removing the motor, a tool or the like is inserted into the through-hole 57 from the first axial side. Then, the retaining ring 117 is contracted and deformed, thereby removing the retaining ring 117 from the case 5. This allows the bearing 115 to move axially relative to the case 5 toward the first side.

[0055] Next, by pulling out the input shaft 7 from the case 5, the entire input shaft 7 is removed from the case 5 together with the bearing 115. In other words, the input shaft 7 is removed from the case 5 in a state separated from the seal ring 123. This makes it possible to remove the retaining ring 119 and replace the bearing 115, or to replace the seal ring 123 inside the through hole 57.

[0056] To reinstall the input shaft 7 in the case 5, first, the bearing 115 is attached to the input shaft 7. Specifically, the expanded portion 110 is inserted inside the inner ring 115b, and then a retaining ring 119 is attached to the expanded portion 110. Next, the input shaft 7 is inserted into the through hole 57 together with the bearing 115. At this time, by inserting the input shaft 7 until the outer ring 115a abuts against the first stepped surface 37a, the input gear 131 meshes with the transmission gear 85. Thereafter, the retaining ring 117 is attached to the through hole 57, and the installation of the input shaft 7 is completed.

[0057] In this manner, in this embodiment, the input shaft 7 is configured to be detachable from the case 5 in a state where it is separated from the seal ring 123. According to this configuration, there is no need to remove the seal ring 123 when removing the input shaft 7 from the case 5. This reduces the risk of a tool or the like coming into contact with the inner circumferential surface of the through hole 57. This reduces the risk of the case 5 being scratched. Furthermore, compared to when work is performed while paying attention to contact between a tool and the case 5, this improves maintainability.

[0058] Moreover, in this embodiment, the inner diameter of the seal ring 123 is smaller than the inner diameter of the bearing 115 . Therefore, when the input shaft 7 is removed, the portion of the input shaft 7 that is in close contact with the seal ring 123 (the expanded portion 110) can be prevented from coming into contact with the bearing 115 or the case 5.

[0059] In this embodiment, a configuration is adopted in which a speed reduction mechanism 6 is provided in the accommodation space S. According to this configuration, as described above, leakage of lubricant from inside the case 5 can be suppressed, and therefore the lubrication performance of the reduction mechanism 6 can be maintained for a long period of time.

[0060] In this embodiment, the outer diameter of the input gear 131 is smaller than the inner diameter of the seal ring 123 . This configuration can prevent the input gear 131 and the seal ring 123 from coming into contact with each other when removing the input shaft 7. As a result, the ease of maintenance can be further improved.

[0061] In this embodiment, a retaining ring 117 that restricts movement of the bearing 115 in a direction away from the seal ring 123 (toward the first axial side) is detachably provided on the case 5. According to this configuration, when removing the input shaft 7, the input shaft 7 can be removed integrally together with the bearing 115 simply by removing the retaining ring 117 from the case 5. This further improves maintainability.

[0062] In the first embodiment, the configuration in which the bearing 115 is removed integrally with the input shaft 7 has been described, but the present invention is not limited to this configuration. That is, the input shaft 7 may be configured to be removed separately from the bearing 115. In this case, the sizes of the bearing 115, the seal ring 123, and the input gear 131 can be changed as appropriate. Furthermore, the input shaft 7 may be non-removable (a configuration in which removal is not assumed). In the above-described embodiment, the configuration in which the bearing 115 is disposed on the atmosphere side relative to the seal ring 123 has been described, but the configuration is not limited to this. The reducer 1 only needs to have the seal ring 123 disposed on the accommodation space S side relative to the bearing 115. In the above-described embodiment, the input shaft 7 is divided into a plurality of members (the outer shaft 100, the inner shaft 101, and the gear shaft 102), but the present invention is not limited to this configuration. The input shaft 7 may be formed as a single unit. In the above embodiment, the bearing 115 is inserted into the through hole 36, but the present invention is not limited to this configuration. The bearing 115 may be fixed to the case 5 by press-fitting or the like.

[0063] (Second embodiment) Next, a second embodiment of the present invention will be described. Fig. 3 is a cross-sectional view of a reducer 200 according to the second embodiment. This embodiment differs from the first embodiment in that the input shaft 230 passes through the reduction mechanism 6 in the axial direction. 3, the second case 22 of the case 5 is formed in a cylindrical shape with a bottom that opens toward a second axial side. The second case 22 is formed with a flange portion 210 that protrudes radially outward from the peripheral wall 31. The flange portion 210 is fixed to the cylindrical portion 21a of the first case 21 in a state where it abuts against the cylindrical portion 21a in the axial direction.

[0064] The through-hole 36 of the first embodiment is not formed in the bottom wall 32 of the second case 22. Therefore, the second case 22 closes the entire opening of the first case 21 from the first side in the axial direction.

[0065] In this embodiment, the inner diameter of the second through hole 57 gradually decreases toward the second axial side. Specifically, the second through hole 57 has a large diameter portion 220, a medium diameter portion 221, and a small diameter portion 222. The large diameter portion 220 and the medium diameter portion 221 are connected via a step surface 220a. In addition, a recess 225 is formed around the second through hole 57 in the second block (base) 42. The recess 225 has an inner diameter larger than that of the large diameter portion 220 and opens toward the second axial side. When the motor is connected to the reducer 200, a part of the housing of the motor fits into the recess 225. The second through hole 57 described above opens at the bottom surface of the recess 225.

[0066] A seal ring 235 is fitted into the small diameter portion 222 of the second through-hole 57 . A bearing 236 is inserted into the large diameter portion 220. An outer ring 236a of the bearing 236 is held between a stepped surface 220a of the second through hole 57 and a retaining ring 237 held in the large diameter portion 220. In other words, the bearing 236 is disposed on the atmosphere side with respect to the seal ring 235. The retaining ring 237 is held in a groove 223 formed in the inner circumferential surface of the large diameter portion 220. The inner diameter of the bearing 236 (the inner diameter of the inner ring 236b) is larger than the inner diameter of the seal ring 235 and smaller than the inner diameter of the small diameter portion 222 of the second through hole 57.

[0067] The input shaft 230 transmits the driving torque of the motor to the transmission gear 85. The input shaft 230 penetrates the carrier 11 and the oscillating gears 12 and 13 through the second through-hole 57, the second central hole 63, the first central hole 62, and the first through-hole 44. Specifically, the input shaft 230 is configured such that a connecting shaft 231 and a gear shaft 232 are assembled in the axial direction.

[0068] The connecting shaft 231 is a hollow round shaft extending along the axis O1. A motor is connected to the inside of the connecting shaft 231 from the second axial side. The outer diameter of the connecting shaft 231 gradually decreases toward the first axial side. Specifically, the connecting shaft 231 has a large-diameter portion 240, a medium-diameter portion 241, and a small-diameter portion 242. The large-diameter portion 240 and the medium-diameter portion 241 are connected via a step surface 240a. The outer diameter of the large-diameter portion 240 of the connecting shaft 231 is smaller than the inner diameter of the medium-diameter portion 221 of the second through-hole 57 and larger than the inner diameter of the seal ring 235. The outer diameter of the small-diameter portion 242 of the connecting shaft 231 is sufficiently smaller than the inner diameters of the central holes 62, 63 of the oscillating gears 12, 13. This suppresses interference between the oscillating gears 12, 13 and the input shaft 230.

[0069] The connecting shaft 231 is inserted into the second through-hole 57 from the second axial side. In this state, the small diameter portion 242 passes through the inside of the seal ring 235 and is positioned within the central holes 62, 63. The outer peripheral surface of the small diameter portion 242 is in close contact with the seal ring 235. This blocks the connection between the inside and outside of the case 5 through the second through-hole 57. In addition, the medium diameter portion 221 is inserted into the inside of the bearing 236 (inner ring 236b). The bearing 236 is held between the stepped surface 240a of the connecting shaft 231 and a retaining ring 250 held in the medium diameter portion 241. The retaining ring 250 is held in a groove 251 formed in the medium diameter portion 241.

[0070] The gear shaft 232 includes a fixed portion 255 , an extension portion 256 and an input gear 257 . The fixed portion 255 is fixed by press-fitting or the like into the small diameter portion 242 of the connecting shaft 231. The extension portion 256 passes through the first central hole 62 of the first oscillating gear 12 and the first through-hole 41a of the first block 41. The input gear 257 protrudes from the extension portion 256 to a first side in the axial direction. The input gear 257 meshes with the transmission gear 85 inside the case 5. The maximum outer diameter of the input gear 257 is smaller than the inner diameter of the seal ring 123.

[0071] In this embodiment, when removing the input shaft 230, the retaining ring 237 is removed from the second through-hole 57, and then the input shaft 230 is pulled out. Then, the input shaft 230 is removed from the reducer 1 together with the bearing 236. This embodiment also provides the same effects as the first embodiment.

[0072] (Third embodiment) Next, a third embodiment of the present invention will be described. Fig. 4 is a cross-sectional view of a reducer 300 according to the third embodiment. This embodiment differs from the above-described embodiments in that the input shaft 340 is arranged parallel to (offset from) the axis O1. In the reducer 300 shown in Fig. 4, a support tube 310 is formed on the bottom wall 32 of the second case 22. The support tube 310 protrudes from the outer periphery of the bottom wall 32 toward a first side in the axial direction. An axis O5 of the support tube 310 is arranged parallel to the axis O1. A through hole 311 that connects the inside and outside of the case 5 is formed on the inside of the support tube 310.

[0073] The inner diameter of the support tube 310 gradually increases toward the first side in the axial direction. Specifically, the support tube 310 has a large diameter portion 320, a medium diameter portion 321, and a small diameter portion 322 that are connected to each other in the axial direction. When the motor 330 is connected to the reducer 300, a part of the housing 331 of the motor 330 fits inside the large diameter portion 320. The output shaft 332 of the motor 330 passes through the large diameter portion 320 and is located inside the medium diameter portion 321.

[0074] The input shaft 340 includes a connecting portion 341 connected to the output shaft 332, and an input gear 342 protruding from the connecting portion 341 toward the second side in the axial direction. A bearing 345 is interposed between a first axial end of the connecting portion 341 and the medium diameter portion 321. As a result, the input shaft 340 is rotatably supported by the case 5 via the bearing 345. The bearing 345 is positioned in the axial direction between a retaining ring 346 detachably attached to the inner circumferential surface of the medium diameter portion 341 and the boundary surface of the medium diameter portion 341 with the small diameter portion 322.

[0075] A seal ring 347 is interposed between a second axial end portion (on the housing space S side with respect to the bearing 345) of the connecting portion 341 and the small diameter portion 322. The seal ring 347 is in close contact with the outer circumferential surface of the connecting portion 341 and the inner circumferential surface of the small diameter portion 322, and blocks the connection between the inside and outside of the case 5 through the through hole 311.

[0076] The reduction gear mechanism 6 of this embodiment includes an intermediate gear 350 that connects the transfer gear 85 and the input gear 342. The intermediate gear 350 is disposed within the second case 22, between the bottom wall 32 and the first block 41. The intermediate gear 350 is a two-stage gear having a first gear 351 and a second gear 352. The first gear 351 and the second gear 352 are coaxially overlapped on the axis O1 and fixed by, for example, screws 355. The intermediate gear 350 is fixed to a support shaft 360. The support shaft 360 extends coaxially with the axis O1 and penetrates the intermediate gear 350 in the axial direction. The support shaft 360 is rotatably supported by the first block 41 and the bottom wall 32.

[0077] The outer diameter of the first gear 351 is larger than that of the second gear 352. The first gear 351 meshes with the input gear 342 of the input shaft 340. The second gear 352 meshes with the transmission gear 85.

[0078] In this embodiment as well, it is possible to achieve the same effects as those of the above-described embodiments.

[0079] (Other variations) Although the preferred embodiments of the present invention have been described above, the present invention is not limited to these embodiments. Addition, omission, substitution, and other modifications of the configuration are possible without departing from the spirit of the present invention. The present invention is not limited by the above description, but is limited only by the appended claims. In the above-described embodiment, the shaft holding mechanism is configured such that the input shaft 7 transmits the driving torque of the motor to, for example, the reduction mechanism 6. However, the present invention is not limited to this configuration. The shaft may be connected to something other than the reduction mechanism 6. In the above-described embodiment, the shaft is used as an input shaft, but the present invention is not limited to this configuration, and the shaft may be an output shaft.

[0080] In addition, within the scope of the spirit of the present invention, it is possible to replace the components in the above-described embodiments with well-known components as appropriate, and the above-described modified examples may be combined as appropriate. [Explanation of symbols]

[0081] 5...Case (base) 6...Deceleration mechanism section 7...Input shaft 22...Second case (base) 36...Through hole 42...Second block (base) 57...Second through hole (through hole) 117... Retaining ring (restricting member) 123...Seal ring (sealing member) 131...Input gear (gear) 230...Input shaft 236...Bearing 237...Stop ring (restriction member) 257...Input gear (gear) 311...Through hole 342...Input gear (gear) 345...Bearing 346... Retaining ring (restricting member) 347...Seal ring (sealing member)

Claims

1. a cylindrical case having a bottom and a first axis, the case defining a storage space for storing a lubricant; a reduction mechanism section accommodated in the accommodation space; a shaft that passes through the case through a through hole formed in the case and is connected to the reduction mechanism within the case; a seal member that surrounds the shaft in the through hole and seals the gap between the shaft and the case; a bearing provided on the opposite side of the sealing member from the accommodation space, the bearing rotatably supporting the shaft within the through hole, The shaft is configured to be removable from the case while being separated from the seal member, The inner diameter of the seal member is smaller than the inner diameter of the bearing, a gear connected to the reduction mechanism is provided at an end of the shaft that is located on the housing space side with respect to the seal member; The outer diameter of the gear is smaller than the inner diameter of the seal member, an intermediate gear that connects the reduction mechanism and the gear is rotatably provided on the case; The case is a bottom wall disposed with the axial direction as a thickness direction; a support cylinder that protrudes from the outer peripheral portion of the bottom wall along another axis parallel to the one axis and that forms the through hole in which the sealing member and the bearing are provided.

2. The reducer according to claim 1 , wherein the seal member is not disposed on the opposite side of the bearing from the accommodation space.

3. A reducer as described in claim 1 or claim 2, wherein a restricting member is removably provided on the case on the opposite side of the case from the sealing member with respect to the bearing, the restricting member restricting movement of the bearing in a direction away from the sealing member.

4. A pair of pivotally connected arms; a reducer provided at a connecting portion of the pair of arms, The reducer is a cylindrical case having a bottom and a first axis, the case defining a storage space for storing a lubricant; a reduction mechanism section accommodated in the accommodation space; a shaft that passes through the case through a through hole formed in the case and is connected to the reduction mechanism within the case; a seal member that surrounds the shaft in the through hole and seals the gap between the shaft and the case; a bearing provided on the opposite side of the sealing member from the accommodation space, the bearing rotatably supporting the shaft within the through hole, The shaft is configured to be removable from the case while being separated from the seal member, The inner diameter of the seal member is smaller than the inner diameter of the bearing, a gear connected to the reduction mechanism is provided at an end of the shaft that is located on the housing space side with respect to the seal member; The outer diameter of the gear is smaller than the inner diameter of the seal member, an intermediate gear that connects the reduction mechanism and the gear is rotatably provided on the case; The case is a bottom wall disposed with the axial direction as a thickness direction; a support cylinder that protrudes from the outer peripheral portion of the bottom wall along another axis parallel to the one axis and that forms the through hole in which the sealing member and the bearing are provided.

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