Speed reducer and robot

Abstract

The present application relates to a shaft holding mechanism and a speed reducer, the shaft holding mechanism of the present application having: a housing (5) that forms a housing space (S) that houses a lubricant; an input shaft (7) that penetrates the housing (5) through a through-hole (36) formed in the housing (5); a seal ring (123) that surrounds the periphery of the input shaft (7) within the through-hole (36) and seals between the input shaft (7) and the housing (5); and a bearing (115) that is provided on the side opposite the housing space (S) with respect to the seal ring (123) and supports the input shaft (7) so as to be rotatable within the through-hole (36).

Description

Technical Field

[0001] This invention relates to shaft retaining mechanisms and speed reducers.

[0002] This application claims priority based on Japanese Patent Application No. 2020-091150, filed in Japan on May 26, 2020, which is incorporated herein by reference. Background Technology

[0003] In rotating devices used in industrial robots, a reducer is installed to reduce the driving torque of a motor. This reducer has a housing and multiple gears housed within the housing (see, for example, Patent Document 1 below). A through-hole is formed in the housing for the input shaft of the motor to pass through. A bearing is provided within the through-hole, which supports the input shaft so that it can rotate.

[0004] However, lubricant is sealed inside the reducer housing to ensure lubrication between gears and cooling of sealing components. A sealing component located within the through-hole restricts the lubricant from flowing out of the housing.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Utility Model Publication No. 59-131641 Summary of the Invention

[0008] The problem the invention aims to solve

[0009] However, in the aforementioned prior art, the sealing member is positioned on the outer side of the housing relative to the bearing, making it difficult for lubricant to reach the sealing member. Consequently, the sealing member may become hot due to frictional heat generated between it and the input shaft.

[0010] The present invention provides a shaft retaining mechanism and a speed reducer capable of effectively supplying lubricant to a sealing member.

[0011] Solution for solving the problem

[0012] To solve the above problems, the present invention adopts the following technical solution.

[0013] The shaft retaining mechanism of one embodiment of the present invention comprises: a base forming a receiving space for receiving lubricant; a shaft passing through a through hole formed in the base; a sealing member surrounding the shaft within the through hole and sealing the shaft and the base; and a bearing disposed on the side opposite to the receiving space relative to the sealing member and supporting the shaft within the through hole to enable rotation.

[0014] This technical solution can suppress the flow of lubricant within the bearing's containment space. Therefore, the lubricant can effectively reach the sealing member. As a result, it can prevent the sealing member from becoming too 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 sealing performance can be maintained for a long period.

[0015] For the shaft retaining mechanism of the above technical solution, it is preferable that the sealing member is not provided on the side opposite to the storage space relative to the bearing.

[0016] For the shaft retaining mechanism of the above technical solution, it is preferable that the shaft is configured to be removable from the base in a state of separation from the sealing member, wherein the inner diameter of the sealing member is smaller than the inner diameter of the bearing.

[0017] For the shaft holding mechanism of the above technical solution, it is preferable to provide a deceleration mechanism part in the storage space, which is connected to the shaft.

[0018] For the shaft retaining mechanism of the above technical solution, it is preferable that a gear is provided at the end of the shaft on the side of the storage space relative to the sealing member, the gear is connected to the reduction mechanism, and the outer diameter of the gear is smaller than the inner diameter of the sealing member.

[0019] For the shaft retaining mechanism of the above technical solution, it is preferable that a limiting member is provided on the side of the base opposite to the sealing member relative to the bearing, and the limiting member restricts the bearing from moving away from the sealing member.

[0020] A speed reducer according to one embodiment of the present invention comprises: a housing forming a storage space for storing lubricant; a speed reduction mechanism portion housed within the storage space; a shaft passing through a through hole formed in the housing and connected to the speed reduction mechanism portion within the housing; a sealing member surrounding the shaft within the through hole and sealing the shaft and the housing; and a bearing disposed on the side opposite to the storage space relative to the sealing member and supporting the shaft within the through hole to enable rotation.

[0021] The effects of the invention

[0022] By utilizing the above-mentioned technical solutions, lubricant can be effectively supplied to the sealing components. Attached Figure Description

[0023] Figure 1 This is a cross-sectional view of the speed reducer according to the first embodiment.

[0024] Figure 2 yesFigure 1 Enlarged view of Part II.

[0025] Figure 3 This is a cross-sectional view of the reducer according to the second embodiment.

[0026] Figure 4 This is a partial cross-sectional view of the reducer according to the third embodiment.

[0027] Explanation of reference numerals in the attached figures

[0028] 5. Housing (base); 6. Reduction mechanism; 7. Input shaft; 22. Second housing (base); 36. Through hole; 42. Second assembly (base); 57. Second through hole; 117. Retaining ring (restricting member); 123. Sealing ring (sealing member); 131. Input gear; 230. Input shaft; 236. Bearing; 237. Retaining ring (restricting member); 257. Input gear; 311. Through hole; 342. Input gear; 345. Bearing; 346. Retaining ring (restricting member); 347. Sealing ring (sealing member). Detailed Implementation

[0029] Next, embodiments of the present invention will be described based on the accompanying drawings. In the embodiments and variations described below, the same reference numerals are sometimes used to refer to corresponding structures and the description is omitted. Furthermore, in the following description, expressions indicating relative or absolute configurations such as "parallel," "orthogonal," "centered," and "coaxial" not only strictly indicate such configurations, but also indicate a state in which relative displacement occurs by tolerance, angle, or distance to achieve the same function.

[0030] (First Implementation)

[0031] [Reducer 1]

[0032] Figure 1 This is a cross-sectional view of reducer 1.

[0033] like Figure 1 As shown, the reducer 1 is located at the joint (joint portion) of a pair of robotic arms that are rotatably connected, such as in an industrial robot. The reducer 1 reduces and outputs the driving torque input from a motor (not shown). A gripping head, for example, is mounted on the output side of the reducer 1.

[0034] The reducer 1 has a housing (base) 5, a reduction mechanism 6, and an input shaft (shaft) 7.

[0035] <Shell 5>

[0036] The housing 5 forms a storage space S for housing the deceleration mechanism 6. The housing 5 is integrally cylindrical with a bottom by combining the first housing 21 and the second housing 22. In the following description, the direction along the axis O1 of the housing 5 will be referred to as the axial direction, the direction intersecting the axis O1 when viewed from the axial direction will be referred to as the radial direction, and the direction of rotation around the axis O1 will be referred to as the circumferential direction.

[0037] The first housing 21 has a cylindrical portion 21a and a flange portion 21b.

[0038] An internal tooth 24 is provided on the inner circumferential surface of the cylindrical portion 21a. The internal tooth 24 has: a plurality of pin grooves 25 formed on the inner circumferential surface of the cylindrical portion 21a; and internal tooth pins 26, which are respectively housed in each pin groove 25.

[0039] The pin groove 25 opens on the inner circumferential surface of the cylindrical portion 21a and extends axially. Each pin groove 25 is formed at equal intervals in the circumferential direction.

[0040] The internal toothed pin 26 is formed as a cylinder extending axially. The internal toothed pin 26 is housed within the pin groove 25 with a portion protruding radially inward from it. The internal toothed pin 26 is held in the pin groove 25 in a manner that allows it to rotate about an axis parallel to the axis O1. Furthermore, the internal teeth 24 may also be integrally formed with the cylindrical portion 21a.

[0041] The flange portion 21b protrudes radially outward from the central portion in the axial direction of the cylindrical portion 21a.

[0042] The second housing 22 seals the opening of the first housing 21 from the first side in the axial direction. The second housing 22 is formed as a bottomed cylindrical shape with an opening facing the second side in the axial direction. The first housing 21 is assembled to the second housing 22 with the cylindrical portion 21a embedded in the peripheral wall 31 of the second housing 22 and the flange portion 21b axially mating with the peripheral wall 31. Furthermore, the sealing material 28 is located between the outer peripheral surface of the cylindrical portion 21a and the inner peripheral surface of the peripheral wall 31.

[0043] The bottom wall 32 of the second housing 22 protrudes radially inward from the first axial end 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 is coaxial with the axis O1 and extends axially to the first side. The inner side of the support cylinder 35 forms a through hole 36 connecting the inside and outside of the housing 5.

[0044] Figure 2 yes Figure 1 Enlarged view of Part II.

[0045] like Figure 2As shown, the inner diameter of the support cylinder 35 gradually decreases from the first side to the second side along the axial direction. Specifically, the large-diameter portion 37, the intermediate-diameter portion 38, and the small-diameter portion 39 of the support cylinder 35 are connected axially. A groove 40 is formed in the large-diameter portion 37. The groove 40 extends throughout the entire circumference of the inner circumference of the large-diameter portion 37. The first step surface 37a connecting the large-diameter portion 37 and the intermediate-diameter portion 38, and the second step surface 38a connecting the intermediate-diameter portion 38 and the small-diameter portion 39, are each formed as a flat surface orthogonal to the axial direction.

[0046] <Deceleration Mechanism Section 6>

[0047] like Figure 1 As shown, the reduction mechanism 6 includes a gear carrier 11, multiple oscillating gears (first oscillating gear 12 and second oscillating gear 13), and multiple crankshafts 14. The reduction mechanism 6 maintains lubrication performance using lubricant sealed within the storage space S.

[0048] The gear carrier 11 is the output part of the reducer 1. The gear carrier 11 is configured to be rotatable about axis O1 inside the housing 5. The gear carrier 11 in this embodiment has a first component 41 and a second component 42.

[0049] Component 41 is disposed on the first axial side within housing 5. Figure 1 (On the right side of the paper, and so on below). The first component 41 is formed as a circular plate coaxially arranged with the axis O1. The bearing 43 is located between the outer peripheral surface of the first component 41 and the inner peripheral surface of the cylindrical portion 21a. Thus, the first component 41 is supported on the housing 5 in a manner that allows it to rotate about the axis O1.

[0050] A first through hole 44 is formed at the radial center of the first component 41, extending axially through the first component 41. A plurality of first shaft support holes 45 are formed on the outer periphery of the first component 41. Each first shaft support hole 45 has a tapered portion whose inner diameter gradually decreases as it moves toward a first axial side. The first shaft support holes 45 are formed at intervals in the circumferential direction.

[0051] Within the housing 5, the second component 42 is disposed on the second axial side relative to the first component. The second component 42 has a base plate 50 and a support post 51.

[0052] The substrate 50 is formed as a circular plate coaxially aligned with axis O1. The substrate 50 seals the second axial side of the first housing 21 (cylindrical portion 21a). Figure 1 The opening is located on the left side of the paper (hereinafter the same). The bearing 53 is located between the outer peripheral surface of the substrate 50 and the inner peripheral surface of the cylindrical portion 21a. Thus, the second component 42 is supported on the housing 5 in a manner that allows it to rotate about the axis O1.

[0053] A sealing ring 55 is located between the outer peripheral surface of the substrate 50 and the inner peripheral surface of the cylindrical portion 21a, and is situated on a second axial side (opposite to the first component 41) to the bearing 53. The sealing ring 55 surrounds the substrate 50. The sealing ring 55 is in close contact with both the outer peripheral surface of the substrate 50 and the inner peripheral surface of the cylindrical portion 21a. Thus, the sealing ring 55 blocks the connection between the interior and exterior of the housing 5 via the opening of the second housing 22. The sealing ring 55 is configured to slide on at least one of the substrate 50 and the cylindrical portion 21a (in this embodiment, the substrate 50) as the substrate 50 rotates.

[0054] A second through hole 57 is formed at the radial center of the substrate 50, extending axially through the substrate 50. The second through hole 57 is sealed by a central cap 58a. A plurality of second axial support holes 59 are formed on the outer periphery of the substrate 50. Each second axial support hole 59 has a tapered portion whose inner diameter gradually decreases as it moves toward a second axial side. Each second axial support hole 59 is axially opposite to each of the first axial support holes 45 described above. Furthermore, the second axial support holes 59 are sealed by an outer periphery cap 58b.

[0055] The support column 51 protrudes axially from the portion of the base plate 50 located between adjacent second shaft support holes 59 towards the first side. The support column 51 is fixed to the first component 41 by bolts 60 or the like in a state of axial mating with the first component 41. As a result, the first component 41 and the second component 42 rotate integrally with respect to the housing 5.

[0056] The first oscillating gear 12 and the second oscillating gear 13 are arranged inside the cylindrical portion 21a in an axially overlapping state. The outer diameters of the first oscillating gear 12 and the second oscillating gear 13 are formed to be 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 respectively mesh with the aforementioned internal teeth 24 (internal tooth pins 26). 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). Alternatively, there may be only one oscillating gear.

[0057] 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 central hole 62 and 63 is equal to the inner diameter of the first through hole 44.

[0058] A plurality of first clearance holes 65 are formed on the outer periphery of the first oscillating gear 12. The first clearance holes 65 are spaced apart in the circumferential direction. A plurality of second clearance holes 66 are formed on the outer periphery of the second oscillating gear 13. The second clearance holes 66 are spaced apart in the circumferential direction at the same spacing as the first clearance holes 65. A corresponding support 51 of the plurality of supports 51 described above passes through each clearance hole 65, 66. The inner diameter of the clearance holes 65, 66 is larger than the outer diameter of the support 51. Therefore, the support 51 does not obstruct the operation of the oscillating gears 12, 13.

[0059] A first through hole 67 is formed on the outer periphery of the first oscillating gear 12 between adjacent first clearance holes 65. A second through hole 68 is formed on the outer periphery of the second oscillating gear 12 between adjacent second clearance holes 66. The through holes 67 and 68 are arranged at the same spacing as the aforementioned shaft support holes 45 and 46.

[0060] The crankshaft 14 functions as a power transmission section between the gear carrier 11 and the oscillating gears 12 and 13. The crankshaft 14 passes through corresponding shaft support holes 45 and 46 and through holes 67 and 68, and is mounted between the first assembly 41 and the base plate 50. Specifically, the crankshaft 14 has a main shaft 71, a first eccentric portion 72, a second eccentric portion 73, and a protrusion 74.

[0061] The main shaft 71 extends along an axis O2 parallel to axis O1. The first axial end of the main shaft 71 is supported by a bearing 76, allowing it to rotate within a first shaft support hole 45. The second axial end of the main shaft 71 is supported by a bearing 77, allowing it to rotate within a second shaft support hole 46. Furthermore, bearings 76 and 77 are, for example, angular contact bearings with cylindrical rollers as rolling elements.

[0062] The first eccentric portion 72 is formed in the portion of the main shaft 71 located within the first through hole 67. The axis O3 of the first eccentric portion 72 is eccentric relative to the axis O2 of the main shaft 71. The first eccentric portion 72 is supported by means of an eccentric portion bearing 81 so that it can rotate within the first through hole 67.

[0063] The second eccentric portion 73 is formed in the portion of the main shaft 71 located within the second through hole 68. The axis O4 of the second eccentric portion 73 is eccentric relative to the axis O2 of the main shaft 71. The second eccentric portion 73 is supported by an eccentric portion bearing 82 so that it can rotate within the second through hole 68. Furthermore, the phases of each eccentric portion 72, 73 are offset about the axis O2 by, for example, 180°.

[0064] The protrusion 74 protrudes axially to the first side from the self-shaft 71. A transmission gear 85 is installed on the protrusion 74.

[0065] <Input axis 7>

[0066] like Figure 2 As shown, the input shaft 7 rotates around axis O1 along with the rotation of the motor, thereby transmitting the driving torque of the motor to the reduction gear unit 6. The input shaft 7 is a structure composed of an outer shaft 100, an inner shaft 101, and a gear shaft 102.

[0067] The outer shaft 100 is a hollow circular shaft extending along axis O1. A motor is connected to the outer shaft 100 from the first axial side. An enlarged portion 110, with an increased outer diameter relative to the central portion of the outer shaft 100, is formed at the second axial end of the outer shaft 100. A groove 111 is formed on the outer peripheral surface of the enlarged portion 110. The groove 111 extends circumferentially throughout the entire outer peripheral surface of the enlarged portion 110. A protrusion 112, projecting radially outward, is formed in the portion of the enlarged portion 110 located on the first axial side relative to the groove 111. The protrusion 112 extends, for example, throughout the entire circumference of the enlarged portion 110.

[0068] The input shaft 7 is rotatably supported on the housing 5 by means of a bearing 115 located 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 (restricting member) 117 embedded in the groove 40. The retaining ring 117 is formed, for example, as a C-ring, E-ring, or the like, with a portion of its circumferential direction cut off. The retaining ring 117 is embedded in 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 elastically deform in a radially expanding or contracting manner. Therefore, by using, for example, a tool, to shrink the retaining ring 117 from its natural length, it is configured to be detachable from the groove 40.

[0069] 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. Thus, the axial movement of the outer ring 115a relative to the housing 5 within the through hole 57 is restricted.

[0070] The inner ring 115b of the bearing 115 is held between the protrusion 112 of the enlarged portion 110 and the retaining ring 119 embedded in the groove 111. Specifically, the enlarged portion 110 is inserted into the inner side of the inner ring 115b. The retaining ring 119 is embedded in the groove 111 with its inner circumferential portion protruding from the outer circumferential surface of the enlarged portion 110. The first axial end face of the inner ring 115b abuts against the protrusion 112. The second axial end face of the inner ring 115b abuts against the retaining ring 119. Thus, the axial movement of the inner ring 115b relative to the input shaft 7 is restricted.

[0071] The inner shaft 101 is a hollow circular shaft extending along the axis O1. Specifically, the inner shaft 101 has a fixing part 120 and a protrusion 121 that is connected to a second side of the axial direction relative to the fixing part 120.

[0072] The fixing part 120 is fixed to the outer shaft 100 by pressing or the like. However, the inner shaft 101 can be fixed to the outer shaft 100 by any means other than pressing (e.g., key, D-shaped cut, etc.).

[0073] The protrusion 121 protrudes axially from the outer shaft 100 to a second axial side. The outer diameter of the protrusion 121 is larger than the outer diameter of the fixed portion 120 and smaller than the outer diameter of the enlarged portion 110. A sealing ring (sealing member) 123 is located between the protrusion 121 and the middle diameter portion 38 of the support cylinder 35. The sealing ring 123 surrounds the protrusion 121. The inner diameter of the sealing ring 123 is smaller than the inner diameter of the bearing 115 (inner ring 115b). The sealing ring 123 is in close contact with the outer peripheral surface of the protrusion 121 and the inner peripheral surface of the middle diameter portion 38. Thus, the sealing ring 123 blocks the connection between the inside and outside of the housing 5 at a position in the through hole 36 that is axially second on the second side (receiving space S side) of the bearing 115. That is, the bearing 115 is configured to be on the atmospheric side relative to the sealing ring 123. The sealing ring 123 is configured to slide on at least one of the outer peripheral surface of the protrusion 121 and the inner peripheral surface of the intermediate diameter portion 38 (protrusion 121 in this embodiment) as the input shaft 7 rotates. Furthermore, the axial movement of the sealing ring 123 relative to the housing 5 between the second step surface 38a and the bearing 115 is restricted.

[0074] The gear shaft 102 is a solid round shaft extending along axis O1. The gear shaft 102 has: a fixed part 130; and an input gear (gear) 131, which is connected to a second side in the axial direction relative to the fixed part 130.

[0075] The fixing part 130 is fixed inside the inner shaft 101 by pressing or the like.

[0076] The input gear 131 protrudes axially from the inner shaft 101 to the second side. The input gear 131 meshes with the transmission gear 85 within the housing 5. The maximum outer diameter of the input gear 131 is smaller than the inner diameter of the sealing ring 123. Furthermore, the shaft retaining mechanism of this embodiment is constituted by at least the input shaft 7, the housing 5, the bearing 115, and the sealing ring 123.

[0077] like Figure 1As shown, in the reducer 1 of this embodiment, the input shaft 7 rotates using 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 using the torque transmitted to the transmission gear 85, each eccentric portion 72, 73 of the crankshaft 14 rotates eccentrically about the axis O2. As a result, each oscillating gear 12, 13 oscillates within the housing 5 and rotates about the axis O1 as the eccentric portions 72, 73 rotate. Consequently, the external teeth 12a, 13a of the oscillating gears 12, 13 rotate, for example, one by one, over the internal tooth pin 26. Accompanying the rotation of the oscillating gears 12, 13, the gear carrier 11 rotates about the first axis O1. As a result, the rotation of the crankshaft 14 is reduced and output as the rotation of the gear carrier 11.

[0078] Here, as described above, lubricant is sealed inside the housing 5 for purposes such as lubrication of the reduction gear 6. The lubricant moves within the housing 5 due to the movement of the reduction gear 6 (e.g., rotation of the reduction gear 6 itself, or low viscosity caused by heat generated at the reduction gear 6). In this embodiment, the storage space S is sealed using a sealing ring 55 between the housing 5 and the second component 42 and a sealing ring 123 between the housing 5 and the input shaft 7. This prevents lubricant leakage from the housing 5.

[0079] In particular, in this embodiment, the structure is such that the bearing 115 is disposed in the through hole 57 of the housing 5 on the side opposite to the sealing ring 123 and the storage space S (atmospheric side).

[0080] This structure prevents the bearing 115 from blocking the flow of lubricant within the housing 5. Therefore, the lubricant can effectively reach the sealing ring 123. As a result, the sealing ring 123 can be prevented from becoming too hot due to frictional heat generated between it and the input shaft 7. In this case, for example, thermal deformation of the sealing ring 123 can be suppressed, and sealing performance can be maintained for a long time.

[0081] In this embodiment, the structure is such that no sealing ring is provided on the side opposite to the storage space S relative to the bearing 115.

[0082] This structure allows for the efficient supply of lubricant to all the sealing rings 55 and 123 of the reducer 1.

[0083] However, in structures where the sealing member is configured to be located on the outer side of the housing relative to the bearing, as is the case in the past, if the input shaft needs to be removed from the reducer, the sealing member must be removed before the input shaft. In this situation, during the removal of the sealing member, the housing may be damaged by inserting clamps or other devices between the through hole and the sealing member.

[0084] Here, the method for mounting and dismounting the input shaft 7 of the reducer 1 in this embodiment will be described.

[0085] First, after removing the motor, a tool or similar device 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 housing 5. This allows the bearing 115 to move axially to the first axial side relative to the housing 5.

[0086] Next, pull the input shaft 7 out of the housing 5, thereby removing the input shaft 7 and bearing 115 together from the housing 5. That is, remove the input shaft 7 from the housing 5 in a state separated from the sealing ring 123. As a result, the retaining ring 119 can be removed to replace the bearing 115 or the sealing ring 123 in the through hole 57.

[0087] When reinstalling the input shaft 7 onto the housing 5, first install the bearing 115 onto the input shaft 7. Specifically, after inserting the enlarged portion 110 into the inner ring 115b, install the retaining ring 119 onto the enlarged portion 110. Next, insert the input shaft 7 and the bearing 115 together into the through hole 57. At this time, insert the input shaft 7 until the outer ring 115a abuts against the first step surface 37a, thereby engaging the input gear 131 with the transmission gear 85. After this, install the retaining ring 117 into the through hole 57, and the installation of the input shaft 7 is complete.

[0088] In this embodiment, the input shaft 7 is configured to be detachable from the housing 5 while the self-sealing ring 123 is separated.

[0089] With this structure, the sealing ring 123 does not need to be removed when the input shaft 7 is taken out of the housing 5. Therefore, the possibility of tools or the like coming into contact with the inner circumferential surface of the through hole 57 can be reduced. Thus, damage to the housing 5 can be suppressed. Furthermore, maintainability can be improved compared to situations where work is performed while worrying about tools coming into contact with the housing 5.

[0090] Furthermore, in this embodiment, the inner diameter of the sealing ring 123 is smaller than the inner diameter of the bearing 115.

[0091] Therefore, when the input shaft 7 is removed, it is possible to prevent the contact between the close-fitting portion (enlarged portion 110) in the input shaft 7 that is in close contact with the sealing ring 123 and the bearing 115 and housing 5.

[0092] In this embodiment, the deceleration mechanism 6 is located within the storage space S.

[0093] Using this structure, as described above, it is possible to suppress the leakage of lubricant from the housing 5, thereby maintaining the lubrication performance of the reduction gear section 6 for a long time.

[0094] In this embodiment, the outer diameter of the input gear 131 is smaller than the inner diameter of the sealing ring 123.

[0095] This structure prevents contact between the input gear 131 and the sealing ring 123 when the input shaft 7 is removed. As a result, maintainability can be further improved.

[0096] In this embodiment, the structure is such that the retaining ring 117 is provided on the housing 5 in a detachable manner, and the retaining ring 117 restricts the movement of the bearing 115 in the direction away from the sealing ring 123 (the first side in the axial direction).

[0097] With this structure, when removing the input shaft 7, the input shaft 7 and bearing 115 can be removed together as a single unit simply by removing the retaining ring 117 from the housing 5. This allows for further improvement in maintainability.

[0098] Furthermore, in the first embodiment, a structure in which the bearing 115 and the input shaft 7 are removed as a single unit was described, but this structure is not limited to. That is, a structure in which the input shaft 7 and the bearing 115 are removed separately is also possible. In such a case, the dimensions of the bearing 115, the sealing ring 123, and the input gear 131 can be appropriately modified. Alternatively, the input shaft 7 may not be removed (a structure that does not presuppose removal).

[0099] In the above embodiment, the structure in which the bearing 115 is disposed on the atmospheric side relative to the sealing ring 123 has been described, but the structure is not limited to this. The sealing ring 123 of the reducer 1 can be disposed on the receiving space S side relative to the bearing 115.

[0100] In the above embodiment, a structure in which the input shaft 7 is divided into multiple components (outer shaft 100, inner shaft 101, gear shaft 102) has been described, but the structure is not limited to this. The input shaft 7 may also be formed integrally.

[0101] In the above embodiment, the structure in which the bearing 115 is inserted into the through hole 36 has been described, but the structure is not limited to this. The bearing 115 can also be fixed to the housing 5 by pressing or the like.

[0102] (Second Implementation)

[0103] Next, the second embodiment of the present invention will be described. Figure 3 This is a cross-sectional view of the reducer 200 according to the second embodiment. In this embodiment, the difference from the first embodiment described above is that the input shaft 230 passes through the reduction mechanism portion 6 axially.

[0104] exist Figure 3In the reducer 200 shown, the second housing 22 of the housing 5 is formed as a bottomed cylindrical shape with an opening on a second side facing the axial direction. A flange 210 is formed on the second housing 22, protruding radially outward from the peripheral wall 31. The flange 210 is fixed to the cylindrical portion 21a of the first housing 21 in a state of axially abutting against the cylindrical portion 21a.

[0105] The through hole 36 of the first embodiment is not formed in the bottom wall 32 of the second housing 22. Therefore, the second housing 22 completely blocks the opening of the first housing 21 from the first side in the axial direction.

[0106] In this embodiment, the inner diameter of the second through hole 57 gradually decreases towards 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 by a stepped surface 220a. Furthermore, in the second component (base) 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 it opens towards the second axial side. When the motor is connected to the reducer 200, a portion of the housing in the motor is embedded in the recess 225. The aforementioned second through hole 57 opens on the bottom surface of the recess 225.

[0107] A sealing ring 235 is embedded in the small diameter portion 222 of the second through hole 57.

[0108] 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, which is held in the large-diameter portion 220. That is, the bearing 236 is positioned on the atmospheric side relative to the sealing ring 235. The retaining ring 237 is held in a groove 223, which is 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 sealing ring 235 and smaller than the inner diameter of the small-diameter portion 222 of the second through hole 57.

[0109] The input shaft 230 transmits the driving torque of the motor to the transmission gear 85. The input shaft 230 passes through the second through hole 57, the second central hole 63, the first central hole 62, and the first through hole 44, and passes through the gear carrier 11 and the oscillating gears 12 and 13. Specifically, the input shaft 230 is a structure in which the connecting shaft 231 and the gear shaft 232 are assembled axially.

[0110] The connecting shaft 231 is a hollow circular 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 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 by a stepped 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, but larger than the inner diameter of the sealing ring 235. The outer diameter of the small diameter portion 242 of the connecting shaft 231 is sufficiently smaller than the inner diameter 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.

[0111] 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 sealing ring 235 and is located within the central holes 62 and 63. The outer peripheral surface of the small diameter portion 242 is in close contact with the sealing ring 235. This blocks the connection between the inside and outside of the housing 5 via the second through hole 57. Additionally, the intermediate 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, which is held within the intermediate diameter portion 241. The retaining ring 250 is held in a groove 251 formed in the intermediate diameter portion 241.

[0112] The gear shaft 232 has a fixed part 255, an extension part 256, and an input gear 257.

[0113] The fixing part 255 is fixed within the small-diameter part 242 of the connecting shaft 231 by pressing or other means. The extension part 256 passes through the first central hole 62 of the first oscillating gear 12 and the first through hole 41a of the first assembly 41. The input gear 257 protrudes axially from the extension part 256 to the first side. The input gear 257 meshes with the transmission gear 85 within the housing 5. The maximum outer diameter of the input gear 257 is smaller than the inner diameter of the sealing ring 123.

[0114] 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. In this way, the input shaft 230 and the bearing 236 are removed together from the reducer 1.

[0115] In this embodiment, it also has the same effect as in the first embodiment.

[0116] (Third implementation)

[0117] Next, the third embodiment of the present invention will be described. Figure 4This is a cross-sectional view of the reducer 300 according to the third embodiment. In this embodiment, the difference from the above embodiments is that the input shaft 340 is configured to be parallel (offset) to the axis O1.

[0118] exist Figure 4 In the reducer 300 shown, a support cylinder 310 is formed on the bottom wall 32 of the second housing 22. The support cylinder 310 protrudes axially from the outer periphery of the bottom wall 32 towards a first side. The axis O5 of the support cylinder 310 is configured to be parallel to the axis O1. A through hole 311 connecting the interior and exterior of the housing 5 is formed on the inner side of the support cylinder 310.

[0119] The inner diameter of the support cylinder 310 gradually increases towards the first axial direction. Specifically, the large diameter portion 320, the intermediate diameter portion 321, and the small diameter portion 322 of the support cylinder 310 are connected axially.

[0120] When the motor is connected to the reducer 300, a portion of the housing 331 of the motor 330 is embedded within the large-diameter portion 320. The output shaft 332 of the motor 330 is located within the intermediate-diameter portion 321 via the large-diameter portion 320.

[0121] The input shaft 340 has: a connecting portion 341 connected to the output shaft 332; and an input gear 342 protruding from the connecting portion 341 toward a second side in the axial direction.

[0122] The bearing 345 is located between the first axial end of the connecting portion 341 and the intermediate diameter portion 321. Thus, the input shaft 340 is rotatably supported on the housing 5 by means of the bearing 345. Furthermore, the bearing 345 is axially positioned between the retaining ring 346, which is detachably mounted on the inner circumferential surface of the intermediate diameter portion 341, and the boundary surface between the intermediate diameter portion 341 and the minor diameter portion 322.

[0123] The sealing ring 347 is located between the second axial end of the connecting portion 341 (on the side of the receiving space S relative to the bearing 345) and the small diameter portion 322. The sealing ring 347 is in close contact with the outer peripheral surface of the connecting portion 341 and the inner peripheral surface of the small diameter portion 322, blocking the connection between the inside and outside of the housing 5 via the through hole 311.

[0124] The reduction mechanism 6 of this embodiment has an intermediate gear 350 connecting the transmission gear 85 and the input gear 342. The intermediate gear 350 is disposed within the second housing 22 between the bottom wall 32 and the first assembly 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 passes through the intermediate gear 350 axially. The support shaft 360 is rotatably supported on the first assembly 41 and the bottom wall 32.

[0125] 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.

[0126] In this embodiment, the same effect as in the embodiments described above can be achieved.

[0127] (Other variations)

[0128] The preferred embodiments of the present invention have been described above, but the present invention is not limited to these embodiments. Additions, omissions, substitutions, and other modifications to the structure may be made 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.

[0129] In the above embodiment, an example of a shaft holding mechanism is described using a structure where the input shaft 7 transmits the motor's drive torque to, for example, the reduction gear unit 6, but the structure is not limited to this. The shaft may also be connected to a location other than the reduction gear unit 6.

[0130] In the above embodiments, the case where a shaft is used as an input shaft has been described, but the structure is not limited to this. The shaft can also be an output shaft.

[0131] Furthermore, without departing from the spirit of the present invention, the constituent elements of the above embodiments can be appropriately replaced with known constituent elements, and the above variations can also be appropriately combined.

Claims

1. A speed reducer, wherein, This reducer has the following features: The shell forms a storage space for storing lubricant and is a bottomed cylindrical shape with an axis as its axial direction. The deceleration mechanism is housed within the storage space. A shaft passes through a through hole formed in the housing and penetrates the housing, and is connected to the reduction mechanism within the housing; A sealing member that surrounds the shaft within the through hole and seals the shaft from the housing; and A bearing, located on the side opposite to the receiving space relative to the sealing member, supports the shaft within the through hole to enable rotation. The shaft is configured to be removable from the housing while detached from the sealing member. The inner diameter of the sealing member is smaller than the inner diameter of the bearing. A gear connected to the reduction mechanism is provided at the end of the shaft located on the storage space side relative to the sealing member. The outer diameter of the gear is formed to be smaller than the inner diameter of the sealing member. An intermediate gear connecting the reduction mechanism and the gear is rotatably mounted on the housing. The housing includes: The bottom wall, configured with the said axial direction as its thickness direction; and A support cylinder protrudes from the outer periphery of the bottom wall along another axis parallel to the first axis, and forms the through hole provided with the sealing member and the bearing.

2. The reducer according to claim 1, wherein, The sealing member is not located on the side opposite to the storage space relative to the bearing.

3. The reducer according to claim 1 or 2, wherein, On the side of the housing opposite to the sealing member relative to the bearing, a restricting member is provided in the housing in a removable manner, which restricts the bearing from moving away from the sealing member.

4. A robot, wherein, This robot has the following features: A pair of arms, connected in a rotatable manner; and A speed reducer, which is located at the connection point of the pair of arms. This reducer has the following features: The shell forms a storage space for storing lubricant and is a bottomed cylindrical shape with an axis as its axial direction. The deceleration mechanism is housed within the storage space. A shaft passes through a through hole formed in the housing and penetrates the housing, and is connected to the reduction mechanism within the housing; A sealing member that surrounds the shaft within the through hole and seals the shaft from the housing; and A bearing, located on the side opposite to the receiving space relative to the sealing member, supports the shaft within the through hole to enable rotation. The shaft is configured to be removable from the housing while detached from the sealing member. The inner diameter of the sealing member is smaller than the inner diameter of the bearing. A gear connected to the reduction mechanism is provided at the end of the shaft located on the storage space side relative to the sealing member. The outer diameter of the gear is formed to be smaller than the inner diameter of the sealing member. An intermediate gear connecting the reduction mechanism and the gear is rotatably mounted on the housing. The housing includes: The bottom wall, configured with the said axial direction as its thickness direction; and A support cylinder protrudes from the outer periphery of the bottom wall along another axis parallel to the first axis, and forms the through hole provided with the sealing member and the bearing.

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