Shaft holding mechanism and reduction gear

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 relates to a shaft holding mechanism and a speed reducer. [[Background Art]]

[0002] Rotating equipment used in industrial robots and the like is equipped with a speed reducer for reducing the driving torque of a motor. This type of speed reducer includes a case and a plurality of gears housed in the case (see, for example, Patent Document 1 below). The case is formed with a through hole through which the input shaft of the motor passes. A bearing that rotatably supports the input shaft is provided in the through hole.

[0003] Incidentally, a lubricant is sealed in the case of the speed reducer for the purposes of ensuring lubricity between the respective gears, cooling a seal member, and the like. The outflow of the lubricant to the outside of the case is restricted by a seal member provided in the through hole. [[Prior Art Documents]] [[Patent Documents]]

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

[0005] However, in the above-described conventional technology, since the seal member is disposed outside the case with respect to the bearing, it is difficult for the lubricant to reach the seal member. Therefore, there is a possibility that the seal member may become high temperature due to frictional heat or the like generated between the seal member and the input shaft.

[0006] The present invention provides a shaft holding mechanism and a speed reducer that can effectively supply a lubricant to a seal member. [[Means for Solving the Problem]]

[0007] To solve the above problems, the present invention employs the following embodiments. A shaft holding mechanism according to one aspect of the present invention comprises a base that forms a storage space for containing a lubricant, 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 provided on the side of the sealing member opposite to the storage space and rotatably supports the shaft within the through hole.

[0008] According to this embodiment, obstruction of the lubricant flow within the containment space by the bearing can be suppressed. Therefore, the lubricant can be effectively delivered to the sealing member. As a result, it is possible to suppress the sealing member from becoming hot due to frictional heat generated between it and the shaft. In this case, for example, thermal deformation of the sealing member can be suppressed, and the sealing performance can be maintained over a long period of time.

[0009] In the shaft holding mechanism according to the above embodiment, it is preferable that the sealing member is not arranged on the side of the bearing opposite to the housing space.

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

[0011] In the shaft holding mechanism according to the above embodiment, it is preferable that a reduction gear mechanism connected to the shaft is provided within the housing space.

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

[0013] In the shaft holding mechanism according to the above embodiment, it is preferable that a restricting member is detachably provided on the base portion on the side of the base portion opposite to the sealing member with respect to the bearing, for restricting the movement of the bearing in a direction away from the sealing member. A gear reducer according to one aspect of the present invention comprises a case forming a housing space for containing a lubricant, a gear reduction mechanism housed in the housing space, a shaft that penetrates the case through a through hole formed in the case and is connected to the gear reduction mechanism 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 provided on the side of the sealing member opposite to the housing space and rotatably supports the shaft within the through hole. [Effects of the Invention]

[0014] According to each of the above embodiments, lubricant can be effectively supplied to the sealing member. [Brief explanation of the drawing]

[0015] [Figure 1] This is a cross-sectional view of the speed reducer according to the first embodiment. [Figure 2] This is an enlarged view of part II of Figure 1. [Figure 3] This is a cross-sectional view of a speed reducer according to the second embodiment. [Figure 4] This is a partial cross-sectional view of the gearbox according to the third embodiment. [Modes for carrying out the invention]

[0016] Next, embodiments of the present invention will be described with reference to the drawings. In the embodiments and modifications described below, corresponding components may be denoted by the same reference numerals and their descriptions may be omitted. In the following description, expressions indicating relative or absolute arrangements such as "parallel," "orthogonal," "center," and "coaxial" will not only strictly represent such arrangements, but will also represent states of relative displacement with tolerances or angles and distances that allow the same function to be obtained.

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

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

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

[0020] The first case 21 includes a cylindrical portion 21a and a flange portion 21b. Internal teeth 24 are provided on an inner peripheral surface of the cylindrical portion 21a. The internal teeth 24 include a plurality of pin grooves 25 formed on the inner peripheral surface of the cylindrical portion 21a, and internal tooth pins 26 respectively accommodated in each of the pin grooves 25. The pin grooves 25 open on the inner peripheral surface of the cylindrical portion 21a and extend in the axial direction. Each of the pin grooves 25 is formed at equal pitches in the circumferential direction. The internal tooth pins 26 are formed in a columnar shape extending along the axial direction. The internal tooth pins 26 are accommodated in the pin grooves 25 in a state where a part thereof protrudes radially inward from the pin grooves 25. The internal tooth pins 26 are held by the pin grooves 25 so as to be rotatable around an axis parallel to the axis O1. Note that the internal teeth 24 may be formed integrally with the cylindrical portion 21a.

[0021] The flange portion 21b protrudes radially outward from an axially central portion of the cylindrical portion 21a.

[0022] The second case 22 closes the opening of the first case 21 from the first side in the axial direction. The second case 22 is formed in a bottomed cylindrical shape that opens toward the second side in the axial direction. 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 sealing material 28 is interposed between the outer surface of the cylindrical portion 21a and the inner surface of the peripheral wall 31.

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

[0024] Figure 2 is an enlarged view of part II of Figure 1. As shown in Figure 2, the inner diameter of the support cylinder 35 gradually decreases from the first side to the second side in the axial direction. Specifically, the support cylinder 35 consists of a large-diameter section 37, a medium-diameter section 38, and a small-diameter section 39 connected in the axial direction. A groove 40 is formed in the large-diameter section 37. The groove 40 extends around the entire circumference of the inner circumferential surface of the large-diameter section 37. The first stepped surface 37a connecting the large-diameter section 37 and the medium-diameter section 38, and the second stepped 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> As shown in Figure 1, the reduction gear 6 comprises a carrier 11, a plurality of oscillating gears (first oscillating gear 12 and second oscillating gear 13), and a plurality of crankshafts 14. The lubrication performance of the reduction gear 6 is maintained by a lubricant sealed within the housing space S.

[0026] The carrier 11 is the output section of the reduction gear 1. The carrier 11 is rotatably mounted inside the case 5 around the axis O1. The carrier 11 in this embodiment comprises a first block 41 and a second block 42. The first block 41 is positioned on the first axial side within the case 5. The first block 41 is formed in a disc shape and is positioned coaxially with the axis O1. A bearing 43 is interposed between the outer circumferential surface of the first block 41 and the inner circumferential surface of the cylindrical portion 21a. As a result, the first block 41 is supported by the case 5 so as to be rotatable around 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. Multiple first axial support holes 45 are formed on the outer circumference of the first block 41. Each first axial support hole 45 has a tapered portion in which the inner diameter gradually decreases as it approaches the first side in the axial direction. Each first axial support hole 45 is formed at intervals in the circumferential direction.

[0028] The second block 42 is located within the case 5 on the second axial side relative to the first block. The second block 42 comprises a substrate 50 and support columns 51. The substrate 50 is formed in the shape of a disc and is positioned coaxially with axis O1. The substrate 50 closes the opening located on the second axial side of the first case 21 (cylindrical portion 21a). A bearing 53 is interposed between the outer circumferential surface of the substrate 50 and the inner circumferential surface of the cylindrical portion 21a. As a result, the second block 42 is supported by the case 5 so as to be rotatable around axis O1.

[0029] A seal ring 55 is interposed between the outer circumferential surface of the substrate 50 and the inner circumferential surface of the cylindrical portion 21a, on the second axial side (opposite side from the first block 41) from 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 circumferential surface of the substrate 50 and the inner circumferential 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 slide against at least one of the substrate 50 and the cylindrical portion 21a (in this embodiment, the substrate 50) 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. Multiple second axial support holes 59 are formed in the outer periphery of the substrate 50. The second axial support holes 59 have a tapered portion in which the inner diameter gradually decreases as it approaches the second side in the axial direction. Each second axial support hole 59 faces each of the first axial support holes 45 described above in the axial direction. The second axial support holes 59 are sealed by an outer periphery cap 58b.

[0031] The support column 51 protrudes axially from the portion of the substrate 50 located between adjacent second axial support holes 59. The support column 51 is fixed to the first block 41 by bolts 60 or the like, in a state where it abuts against the first block 41 in the axial direction. As a result, the first block 41 and the second block 42 rotate together as a single unit 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 circumferential surface of the first oscillating gear 12. External teeth 13a are formed on the outer circumferential 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 mesh with the internal teeth 24 (internal tooth pins 26) described above, respectively. The number of teeth of the external teeth 12a and 13a is set to be slightly less than the number of internal tooth pins 26 (pin grooves 25) (for example, one less). Note that there may be only one oscillating gear.

[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 diameters of each central hole 62 and 63 are equal to the inner diameter of the first through hole 44.

[0034] Multiple first relief holes 65 are formed on the outer circumference of the first oscillating gear 12. Each first relief hole 65 is formed at intervals in the circumferential direction. Multiple second relief holes 66 are formed on the outer circumference of the second oscillating gear 13. Each second relief hole 66 is formed at the same pitch as the first relief holes 65 and at intervals in the circumferential direction. A corresponding support column 51 from the above-mentioned plurality of support columns 51 passes through each relief hole 65, 66. The inner diameter of the relief holes 65, 66 is larger than the outer diameter of the support column 51. This prevents the operation of each oscillating gear 12, 13 from being hindered by the support column 51.

[0035] On the outer circumference of the first oscillating gear 12, a first through hole 67 is formed in the portion located between adjacent first relief holes 65. On the outer circumference of the second oscillating gear 12, a second through hole 68 is formed in the portion located between adjacent second relief holes 66. Each through hole 67, 68 is arranged at the same pitch as the shaft support holes 45, 46 described above.

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

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

[0038] The first eccentric portion 72 is formed in the part of the main shaft 71 located within 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 within the first through hole 67 via an eccentric portion bearing 81. The second eccentric portion 73 is formed in the part of the main shaft 71 located within the second through hole 68. The 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 within the second through hole 68 via an eccentric portion bearing 82. Note that each eccentric portion 72, 73 is, for example, 180° out of phase around the axis O2.

[0039] The projection 74 protrudes from the main shaft 71 in the first axial direction. A transmission gear 85 is attached to the projection 74.

[0040] <Input axis 7> As shown in Figure 2, the input shaft 7 rotates around axis O1 as the motor rotates, thereby transmitting the motor's driving torque to the reduction mechanism 6. The input shaft 7 is composed of 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 axis O1. A motor is connected to the outer shaft 100 from the first axial side. An enlarged portion 110 is formed at the second axial end of the outer shaft 100, with an outer diameter larger than that of the central part of the outer shaft 100. A groove 111 is formed on the outer circumferential surface of the enlarged portion 110. The groove 111 extends along the entire circumference of the outer circumferential surface of the enlarged portion 110. A projection 112 is formed on the portion of the enlarged portion 110 that is located on the first axial side relative to the groove 111, projecting radially outward. The projection 112 extends, for example, along the entire circumference of the enlarged portion 110.

[0042] The input shaft 7 is rotatably supported in the case 5 via a bearing 115 interposed between the enlarged portion 110 and the support cylinder 35. The outer ring 115a of the bearing 115 is inserted into the large-diameter portion 37 of the support cylinder 35. The outer ring 115a is held between the first stepped surface 37a and a retaining ring (regulating 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 to expand or contract radially. Therefore, the retaining ring 117 is configured to be detachable from the groove 40 by contracting it from its natural length, for example, using a tool.

[0043] The second axial end face of the outer ring 115a abuts against the first stepped surface 37a. The first axial end face of the outer ring 115a abuts against the retaining ring 117. As a result, the axial movement of the outer ring 115a relative to the case 5 within the through hole 57 is restricted.

[0044] The inner ring 115b of the bearing 115 is held between the projection 112 of the enlarged portion 110 and the retaining ring 119 fitted into the groove 111. Specifically, the enlarged portion 110 is inserted inside the inner ring 115b. The retaining ring 119 is fitted into the groove 111 with its inner circumference protruding from the outer surface of the enlarged portion 110. The first axial end face of the inner ring 115b abuts against the projection 112. The second axial end face of the inner ring 115b abuts against the retaining ring 119. As a result, the axial movement of the inner ring 115b relative to the input shaft 7 is restricted.

[0045] The inner shaft 101 is a hollow round shaft extending along the axis O1. Specifically, the inner shaft 101 comprises a fixed portion 120 and an overhanging portion 121 connected to the second axial side of the fixed portion 120. The fixing part 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, by a key or D-cut) as long as it is configured to be non-rotatable relative to the outer shaft 100.

[0046] The protruding portion 121 projects from the outer shaft 100 to the 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 enlarged portion 110. A seal ring (sealing member) 123 is interposed between the protruding portion 121 and the middle diameter portion 38 of the support cylinder 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 circumferential surface of the protruding portion 121 and the inner circumferential surface of the middle diameter portion 38. As a result, the seal ring 123 blocks the connection between the inside and outside of the case 5 on the second axial side (housing space S side) of the bearing 115 within the through hole 36. That is, the bearing 115 is positioned on the atmospheric side relative to the seal ring 123. The seal ring 123 is configured 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 (in this embodiment, the protruding portion 121) as the input shaft 7 rotates. The axial movement of the seal ring 123 relative to the case 5 is restricted between the second stepped surface 38a and the bearing 115.

[0047] The gear shaft 102 is a solid round shaft extending along axis O1. The gear shaft 102 comprises a fixed portion 130 and an input gear (gear) 131 connected to the fixed portion 130 on the second axial side. The fixing part 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 in the second axial direction. The input gear 131 meshes with the transmission gear 85 within 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 composed of at least the input shaft 7, case 5, bearing 115, and seal ring 123.

[0049] As shown in Figure 1, in the reduction gear 1 of this embodiment, the input shaft 7 rotates due to 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 due to the torque transmitted to the transmission gear 85, each eccentric part 72, 73 of the crankshaft 14 rotates eccentrically around the axis O2. As a result, each oscillating gear 12, 13 rotates around the axis O1 while oscillating inside the case 5, following the rotation of the eccentric parts 72, 73. As a result, the oscillating gears 12, 13 rotate with their external teeth 12a, 13a overcoming the internal tooth pins 26 one by one. As the oscillating gears 12, 13 rotate, the carrier 11 rotates around the first axis O1. As a result, the rotation of the crankshaft 14 is reduced 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 gear 6. The lubricant moves inside the case 5 due to the operation of the reduction gear 6 (for example, the rotation of the reduction gear 6 itself, or the decrease in viscosity due to the heat generated in the reduction gear 6). In this embodiment, the housing 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 prevents the lubricant from leaking out of the case 5.

[0051] In particular, in this embodiment, the bearing 115 is positioned within the through hole 57 of the case 5 on the opposite side (atmospheric side) from the housing space S than the seal ring 123. This configuration prevents the lubricant flow within case 5 from being obstructed by the bearing 115. As a result, the lubricant can be effectively distributed to the seal ring 123. Consequently, the seal ring 123 is prevented from becoming overheated due to frictional heat generated between it and the input shaft 7. In this case, for example, thermal deformation of the seal ring 123 can be suppressed, and the sealing performance can be maintained over a long period of time.

[0052] In this embodiment, a seal ring is not positioned on the side of the bearing 115 opposite to the housing space S. This configuration allows for effective lubrication of all seal rings 55 and 123 of the reduction gear 1.

[0053] By the way, in a conventional configuration where the sealing member is located on the outside of the case relative to the bearing, if it becomes necessary to remove the input shaft from the reduction gear, the sealing member must be removed before the input shaft. In this case, when removing the sealing member, there is a possibility that the case may be scratched by inserting a jig or the like between the through hole and the sealing member.

[0054] Here, we will describe how to attach and detach the input shaft 7 in the gearbox 1 of this embodiment. 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 deformed and compressed, thereby removing the retaining ring 117 from the case 5. This allows the bearing 115 to move axially toward the first side relative to the case 5.

[0055] Next, by pulling the input shaft 7 out of the case 5, the entire input shaft 7, along with the bearing 115, is removed from the case 5. In other words, the input shaft 7 is removed from the case 5 separated from the seal ring 123. This allows the retaining ring 119 to be removed and the bearing 115 to be replaced, or the seal ring 123 in the through hole 57 to be replaced.

[0056] To reattach the input shaft 7 to the case 5, first attach the bearing 115 to the input shaft 7. Specifically, insert the enlarged portion 110 inside the inner ring 115b, and then attach the retaining ring 119 to the enlarged portion 110. Next, insert the input shaft 7 into the through hole 57 together with the bearing 115. At this time, insert the input shaft 7 until the outer ring 115a abuts against the first stepped surface 37a, so that the input gear 131 meshes with the transmission gear 85. After that, attach the retaining ring 117 to the through hole 57, and the installation of the input shaft 7 is completed.

[0057] Thus, in this embodiment, the input shaft 7 is configured to be detachable from the case 5 while separated from the seal ring 123. With this configuration, it is not necessary to remove the seal ring 123 when removing the input shaft 7 from the case 5. Therefore, the risk of tools or other objects coming into contact with the inner surface of the through hole 57 is reduced. Consequently, damage to the case 5 can be suppressed. In addition, maintenance can be improved compared to when work is performed while being careful about contact between tools and the case 5.

[0058] Furthermore, in this embodiment, the inner diameter of the seal ring 123 is smaller than the inner diameter of the bearing 115. Therefore, when removing the input shaft 7, it is possible to prevent the portion of the input shaft 7 that is in close contact with the seal ring 123 (enlarged portion 110) from coming into contact with the bearing 115 or the case 5.

[0059] In this embodiment, the deceleration mechanism 6 is provided within the accommodation space S. With this configuration, as described above, leakage of lubricant from inside case 5 can be suppressed, and the lubrication performance of the reduction gear mechanism 6 can be maintained over 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 prevents contact between the input gear 131 and the seal ring 123 when removing the input shaft 7. As a result, maintainability can be further improved.

[0061] In this embodiment, a retaining ring 117 is detachably provided on the case 5 to restrict the movement of the bearing 115 in the direction away from the seal ring 123 (the first axial direction). With this configuration, when removing the input shaft 7, the input shaft 7 can be removed 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, a configuration was described in which the bearing 115 is removed together with the input shaft 7, but the configuration is not limited to this. That is, the input shaft 7 may be removed separately from the bearing 115. In this case, the sizes of the bearing 115, seal ring 123, and input gear 131 can be changed as appropriate. Also, the input shaft 7 may be non-removable (a configuration that does not assume removal). In the embodiment described above, a configuration was described in which the bearing 115 is positioned on the atmospheric side relative to the seal ring 123, but the configuration is not limited to this. The reduction gear 1 only needs to have the seal ring 123 positioned on the housing space S side relative to the bearing 115. In the embodiment described above, the input shaft 7 is divided into multiple components (outer shaft 100, inner shaft 101, gear shaft 102), but the configuration is not limited to this. The input shaft 7 may be formed as a single unit. In the embodiment described above, a configuration in which the bearing 115 is inserted into the through hole 36 was described, but the configuration is not limited to this. 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. Figure 3 is a cross-sectional view of the reduction gear 200 according to the second embodiment. This embodiment differs from the first embodiment described above in that the input shaft 230 penetrates the reduction mechanism 6 in the axial direction. In the gearbox 200 shown in Figure 3, the second case 22 of case 5 is formed in a bottomed cylindrical shape that opens toward the second side in the axial direction. The second case 22 has 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, abutting it in the axial direction.

[0064] The bottom wall 32 of the second case 22 does not have the through-hole 36 of the first embodiment. 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 as it moves toward the second side in the axial direction. 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 stepped surface 220a. In the second block (base portion) 42, a recess 225 is formed around the second through-hole 57. The inner diameter of the recess 225 is larger than that of the large-diameter portion 220 and opens toward the second side in the axial direction. When the motor is connected to the reduction gear 200, a part of the housing of the motor fits into the recess 225. The second through-hole 57 described above opens on 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. The outer ring 236a of the bearing 236 is held between the stepped surface 220a of the second through hole 57 and the retaining ring 237 held in the large-diameter portion 220. That is, the bearing 236 is positioned on the atmospheric side relative to the seal ring 235. The retaining ring 237 is held in a groove 223 formed on 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 motor's drive torque to the transmission gear 85. The input shaft 230 passes through 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 with a connecting shaft 231 and a gear shaft 232 assembled in the axial direction.

[0068] The connecting shaft 231 is a hollow round shaft extending along axis O1. A motor is connected to the connecting shaft 231 from the second axial side. The outer diameter of the connecting shaft 231 gradually decreases towards the first axial side. Specifically, the connecting shaft 231 has a large diameter section 240, a medium diameter section 241, and a small diameter section 242. The large diameter section 240 and the medium diameter section 241 are connected via a stepped surface 240a. The outer diameter of the large diameter section 240 of the connecting shaft 231 is smaller than the inner diameter of the medium diameter section 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 section 242 of the connecting shaft 231 is sufficiently smaller than the inner diameters of the central holes 62 and 63 of the oscillating gears 12 and 13. This suppresses interference between the oscillating gears 12 and 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 inside the seal ring 235 and is located inside the central holes 62 and 63. The outer circumferential 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. The medium diameter portion 221 is inserted inside the bearing 236 (inner ring 236b). The bearing 236 is held between the stepped surface 240a of the connecting shaft 231 and the retaining ring 250 held by 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 to the small-diameter portion 242 of the connecting shaft 231 by press-fitting or the like. 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 the first axial side. 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. As a result, the input shaft 230, together with the bearing 236, is removed from the reduction gear 1. This embodiment also provides the same effects and advantages as the first embodiment.

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

[0073] The inner diameter of the support cylinder 310 gradually increases as it moves toward the first side in the axial direction. Specifically, the support cylinder 310 consists of a large-diameter section 320, a medium-diameter section 321, and a small-diameter section 322 connected in the axial direction. When the motor 330 is connected to the reduction gear 300, a portion of the housing 331 of the motor 330 fits into the large-diameter section 320. The output shaft 332 of the motor 330 passes through the large-diameter section 320 and is located within the medium-diameter section 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 to a second axial side. A bearing 345 is interposed between the 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 axially positioned between a retaining ring 346, which is detachably attached to the inner circumferential surface of the medium-diameter portion 341, and the interface between the medium-diameter portion 341 and the small-diameter portion 322.

[0075] A seal ring 347 is interposed between the axial second end of the connecting portion 341 (the side of the housing space S relative to the bearing 345) 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, blocking 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 transmission gear 85 and the input gear 342. The intermediate gear 350 is located 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 fixed together, coaxially superimposed on axis O1, by means of screws 355, for example. The intermediate gear 350 is fixed to a support shaft 360. The support shaft 360 extends coaxially with axis O1 and passes through 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 and advantages as in the embodiments described above.

[0079] (Other variations) Although preferred embodiments of the present invention have been described above, the present invention is not limited to these embodiments. Additions, omissions, substitutions, and other modifications are possible without departing from the spirit of the present invention. The present invention is not limited by the above description, but only by the appended claims. In the above-described embodiment, the shaft holding mechanism was explained using a configuration in which the input shaft 7 transmits the motor's drive torque to, for example, the reduction gear 6, but the configuration is not limited to this. The shaft may be connected to a component other than the reduction gear 6. The above-described embodiment explains the case where the shaft is used as the input shaft, but the configuration is not limited to this. The shaft may also be the output shaft.

[0080] Furthermore, without departing from the spirit of the present invention, the components in the embodiments described above can be replaced with well-known components as appropriate, and the modifications described above can be combined as appropriate. [Explanation of symbols]

[0081] 5…Case (base) 6...Deceleration mechanism section 7…Input axis (shaft) 22…Case 2 (Base) 36…Through hole 42…Second block (base) 57…Second through hole (through hole) 117… Retaining ring (regulating member) 123...Seal ring (sealing component) 131... Input gear (gear) 230... Input axis (shaft) 236... Bearings 237... Retaining ring (regulating member) 257... Input gear (gear) 311…Through hole 342... Input gear (gear) 345... Bearing 346... Retaining ring (regulating member) 347...Seal ring (sealing component)

Claims

1. A base that forms a containment space in which the lubricant is contained, A shaft that penetrates the base through a through hole formed in the base, A sealing member surrounds the shaft within the through hole and seals the space between the shaft and the base, The seal member is provided on the side opposite to the housing space and includes a bearing that rotatably supports the shaft within the through hole, The aforementioned shaft is The outer shaft supported by the aforementioned bearing, The outer shaft is connected to the inner shaft with which the sealing member is in close contact, The gear shaft is fixed to the aforementioned internal shaft, The inner shaft is formed in the shape of a hollow shaft extending in the axial direction, The gear shaft is The gear shaft fixing portion fixed inside the inner shaft, A shaft holding mechanism comprising a gear that protrudes axially from the gear shaft fixing portion toward the housing space and is connected to a reduction mechanism portion located in the housing space.

2. The outer shaft is formed in the shape of a hollow shaft extending in the axial direction, The aforementioned inner shaft is The inner shaft fixing portion fixed inside the outer shaft, The sealing member has an outer circumferential surface that is in close contact with the sealing member, and comprises an overhang that protrudes in the axial direction from the inner shaft fixing portion, The shaft holding mechanism according to claim 1, wherein the inner diameter of the sealing member is smaller than the inner diameter of the bearing.

3. The shaft holding mechanism according to claim 2, wherein the outer diameter of the gear is smaller than the inner diameter of the sealing member.

4. The shaft holding mechanism according to claim 2 or 3, wherein the protruding portion protrudes radially in a direction intersecting the axial direction with respect to the inner shaft fixing portion.

5. Of the outer shaft, an enlarged portion is formed at the end closer to the protruding portion in the axial direction, such that its outer diameter is larger than that of the other parts of the outer shaft. The shaft holding mechanism according to claim 4, wherein the bearing supports the outer shaft via the enlarged portion.

6. A case that forms a containment space in which the lubricant is contained, The reduction mechanism unit housed within the aforementioned housing space, A shaft that penetrates the case through a through hole formed in the case and is connected to the reduction mechanism within the case, A sealing member surrounds the shaft within the through hole and seals the space between the shaft and the case, The seal member is provided on the side opposite to the housing space and includes a bearing that rotatably supports the shaft within the through hole, The aforementioned shaft is The outer shaft supported by the aforementioned bearing, The outer shaft is connected to the inner shaft with which the sealing member is in close contact, The gear shaft is fixed to the aforementioned internal shaft, The inner shaft is formed in the shape of a hollow shaft extending in the axial direction, The gear shaft is The gear shaft fixing portion fixed inside the inner shaft, A speed reducer comprising a gear that protrudes axially from the gear shaft fixing portion toward the housing space and is connected to a reduction mechanism portion located in the housing space.

7. The aforementioned case is, The bottom wall and, The gearbox according to claim 6, further comprising a support cylinder that protrudes from the bottom wall and constitutes the through hole in which the sealing member and the bearing are provided.

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