reducer

Abstract

One aspect of the present invention provides a speed reducer comprising: a housing; a speed reduction mechanism having a gear carrier rotatable relative to the housing, the speed reduction mechanism being disposed within the housing to reduce the speed of rotation input from a motor and output the reduced speed; and a bolt protruding from the gear carrier toward the outside of the housing and having an external thread for fastening to an internal thread provided on a second arm, the bolt being disposed on the gear carrier.

Description

Technical Field

[0001] This invention relates to a speed reducer. Background Technology

[0002] In applications such as industrial robots, a pair of arms are connected in a rotatable manner. A motor unit for driving the arms is located at the connection point (joint). The motor unit includes a motor and a reducer connected to the motor. In the motor unit, the motor torque generated by the rotation of the motor is reduced in speed by the reducer and then output to the arm.

[0003] The reducer includes a housing and a gear carrier rotatably disposed within the housing. A threaded hole (internal thread) is formed in the gear carrier (see, for example, Patent Document 1 below). In the structure of Patent Document 1 below, the arm is fixed to the gear carrier by bolts fastened to the threaded hole.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2016-75354 Summary of the Invention

[0007] The problem the invention aims to solve

[0008] There is a possibility of bolt hole breakage when excessive tightening torque is applied to the bolt hole, or when bolts are repeatedly tightened and loosened. In the reducer described in Patent Document 1, the bolt hole is formed within the gear carrier itself. Therefore, if the bolt hole breaks, the gear carrier itself must be replaced. As a result, in conventional reducers, there is a possibility of time-consuming and costly repair work.

[0009] The present invention provides a speed reducer that can reduce the time and cost spent on repair work.

[0010] Solution for solving the problem

[0011] (1) One aspect of the reducer of the present invention comprises: a housing; a reduction mechanism having a transmission portion disposed in a manner rotatable relative to the housing, the reduction mechanism being disposed within the housing and outputting a rotation input from a drive source after reduction; and a bolt protruding from the transmission portion toward the outside of the housing. The bolt has an external thread for fastening to an internal thread portion disposed on a connecting member.

[0012] According to this design, when the transmission part needs repair due to bolt breakage, the repair work can be completed simply by replacing the bolt after removing the connecting component from the transmission part. Therefore, by providing bolts that are separate from the transmission part, compared to the conventional structure where an internal thread is formed in the transmission part itself, the time and cost spent on repair work when the threaded part breaks can be reduced.

[0013] (2) Alternatively, the bolt may have: a head; and a shank protruding from the head and having the external thread. Alternatively, a bolt through hole may be formed in the transmission part for receiving the head and allowing the shank to protrude from the transmission part.

[0014] (3) Alternatively, the transmission part may include: a main body extending within the housing along the rotation axis of the transmission part; and a flange extending radially relative to the main body toward the rotation axis and opposite to the housing in a direction along the rotation axis. Alternatively, the bolt through hole may be formed in the flange.

[0015] (4) Alternatively, the bolt may be formed of a material with a hardness higher than that of the transmission part.

[0016] (5) Alternatively, internal teeth may be provided on the inner circumference of the housing. Alternatively, the reduction mechanism may include: a crankshaft connected to the input shaft of the drive source, having an eccentric portion that rotates eccentrically relative to the rotation axis of the transmission unit; and a oscillating gear having external teeth that mesh with the internal teeth. As the eccentric portion rotates eccentrically, the oscillating gear rotates within the housing while its external teeth cross the internal teeth, and the transmission unit rotates about the rotation axis as the oscillating gear rotates. Alternatively, the bolt may be positioned in the transmission unit at a position opposite to the oscillating gear in the direction along the rotation axis, with its external thread protruding from the transmission unit.

[0017] (6) Alternatively, internal teeth may be provided on the inner circumference of the housing. Alternatively, the transmission part may include: a main body having external teeth that mesh with the internal teeth, capable of flexing and deforming radially intersecting the rotation axis of the transmission part; and a flange extending radially relative to the main body and facing the housing in a direction along the rotation axis. Alternatively, the deceleration mechanism may include a wave generator rotatably disposed inside the main body, causing the main body to flex and deform radially with rotation, while simultaneously changing the meshing position between the external teeth and the internal teeth circumferentially about the rotation axis. Alternatively, the bolt may be fixed to the flange.

[0018] (7) One aspect of the reducer of the present invention comprises: a circular gear having: a cylindrical portion having internal teeth; and a flange portion extending from the cylindrical portion; a flexible gear having external teeth meshing with the internal teeth, the flexible gear being rotatably disposed inside the cylindrical portion and capable of flexing and deforming radially in the cylindrical portion; a wave generator being rotatably disposed inside the flexible gear, which, while rotating, causes the flexible gear to flex and deform radially, and changes the meshing position between the external teeth and the internal teeth in the circumferential direction of the cylindrical portion; and a bolt protruding axially from the flange portion toward the cylindrical portion and fixed to the flange portion. The bolt has an external thread portion for fastening to an internal thread portion provided on a connecting member.

[0019] According to this design, a bolt is provided on the flange of the circular gear. Therefore, when the circular gear needs repair due to bolt breakage, the repair work can be completed simply by replacing the bolt after removing the connecting component from the circular gear. As a result, the time and cost spent on repair work can be reduced.

[0020] The effects of the invention

[0021] Based on the above-mentioned forms, the time and cost spent on repair work can be reduced. Attached Figure Description

[0022] Figure 1 This is a perspective sectional view of the speed reducer according to the first embodiment.

[0023] Figure 2 yes Figure 1 Enlarged view of Part II.

[0024] Figure 3 This is a perspective sectional view of the speed reducer according to the second embodiment.

[0025] Figure 4 This is a perspective sectional view of the reducer according to the third embodiment.

[0026] Explanation of reference numerals in the attached figures

[0027] 1. Reducer; 5. Housing; 6. Reducer mechanism; 11. Gear carrier (transmission part); 12. First oscillating gear (gear); 12a. External gear; 13. Second oscillating gear (gear); 13a. External gear; 14. Crankshaft; 24. Internal gear; 41. First block (main body); 50. Base plate (main body); 51. Support column (main body); 52. Gear carrier flange (flange); 61. Bolt through hole; 62. Bolt; 62a. Head; 62c. Rod; 62d. External thread; 100. Second arm (connecting component); 200. Reducer; 201. Crankshaft; 211. First eccentric part (eccentric part); 212. Second eccentric part; 214. Input shaft; 24 0. Bolt through hole; 241. Bolt; 241a. Head; 241b. Rod; 241c. External thread; 300. Reducer; 301. Circular gear (housing); 302. Flexible gear; 303. Wave generator; 311. First flange; 312. First bolt through hole; 315. Bolt; 315a. Head; 315b. Rod; 315c. External thread; 320. Main shaft; 320a. External tooth; 322. Second flange; 325. Second bolt through hole; 326. Bolt; 326a. Head; 326b. Rod; 326c. External thread; 350. Input shaft; O1. Axis (rotation axis). Detailed Implementation

[0028] Next, embodiments of the present invention will be described based on the accompanying drawings. In the embodiments and variations described below, there are cases where the corresponding structures are labeled with the same reference numerals and the description is omitted. In the following description, expressions such as "parallel," "orthogonal," "center," and "coaxial," which indicate relative or absolute configurations, not only precisely indicate such configurations but also indicate a state of relative displacement by angle or distance with tolerances, achieving the same function.

[0029] (First Embodiment)

[0030] [Reducer 1]

[0031] Figure 1 This is a perspective sectional view of the reducer 1 according to the first embodiment.

[0032] like Figure 1 As shown, the reducer 1 is installed in the connection part (joint part) of a pair of arms in, for example, an industrial robot. The pair of arms are connected in a rotatable manner. The reducer 1 reduces the motor torque input from a motor (not shown) and outputs it.

[0033] The reducer 1 has a housing 5 and a reduction mechanism 6.

[0034] <Shell 5>

[0035] The housing 5 includes a cylindrical portion 21 and a housing flange portion 22. In the following description, the direction along the axis O1 of the cylindrical portion 21 will be referred to as the axial direction, the direction intersecting the axis O1 from the axial view 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.

[0036] The cylindrical portion 21 has: a first region 21a located on a first side in the axial direction; a second region 21b located on a second side in the axial direction relative to the first region 21a; and a central region 21c located between the first region 21a and the second region 21b.

[0037] The inner diameter of the central region 21c is smaller than the inner diameters of the first region 21a and the second region 21b.

[0038] An internal tooth 24 is provided on the inner circumferential surface of the central region 21c. The internal tooth 24 has multiple pin slots 25 and internal tooth pins 26.

[0039] Multiple pin grooves 25 are formed on the inner circumferential surface of the central region 21c. The pin grooves 25 open on the inner circumferential surface of the central region 21c and extend axially. The pin grooves 25 are formed at equal intervals in the circumferential direction.

[0040] Internal toothed pins 26 are respectively housed in multiple pin grooves 25. The internal toothed pins 26 are formed as cylinders extending axially. The internal toothed pins 26 are housed in the pin grooves 25 with a portion of the internal toothed pin 26 protruding radially inward from the pin groove 25. The internal toothed pins 26 are held in the pin grooves 25 in a manner that allows them to rotate about an axis parallel to axis O1. The internal teeth 24 may also be integrally formed with the cylindrical portion 21.

[0041] The housing flange 22 extends radially outward from the central region 21c. A plurality of through holes 22a are formed in the housing flange 22. The through holes 22a penetrate the housing flange 22 axially. The through holes 22a are formed at intervals in the circumferential direction. For example, a first arm (not shown) of a pair of arms is fixed to the housing flange 22. Bolts (not shown) are inserted into the through holes 22a and the through holes formed in the first arm. The housing flange 22 and the first arm are fixed by tightening the bolts and nuts. The through holes 22a may also be internally threaded holes for bolt tightening.

[0042] <Deceleration Mechanism Section 6>

[0043] The reduction mechanism 6 includes a gear carrier (transmission unit) 11, multiple oscillating gears (first oscillating gear 12 and second oscillating gear 13) and multiple crankshafts 14.

[0044] The gear carrier 11 is the output part of the reducer 1. The gear carrier 11 is disposed inside the housing 5 in a manner that allows it to rotate about an axis (rotation axis) O1. The gear carrier 11 includes a first block 41 and a second block 42. The first block 41 and the second block 42 are formed of, for example, aluminum alloy.

[0045] At least a portion of the first block 41 is disposed inside the first region 21a. The first block 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 block 41 and the inner peripheral surface of the first region 21a. Thus, the first block 41 is supported on the housing 5 in a manner that allows it to rotate about the axis O1.

[0046] A first through hole 44 is formed at the radial center of the first block 41. The first through hole 44 penetrates the first block 41 axially. A plurality of first shaft support holes 45 are formed on the outer periphery of the first block 41. The first shaft support holes 45 are formed at intervals in the circumferential direction.

[0047] The second block 42 is disposed on the second side of the axial direction relative to the first block 41 within the housing 5. The second block 42 includes a base plate 50, a support column 51, and a gear carrier flange portion 52.

[0048] The substrate 50 is formed as a circular plate coaxially arranged with axis O1. At least a portion of the substrate 50 is disposed inside the second region 21b. The bearing 53 is located between the outer peripheral surface of the substrate 50 and the inner peripheral surface of the second region 21b. Thus, the second block 42 is supported on the housing 5 in a manner that allows it to rotate about axis O1.

[0049] A second through hole 57 is formed at the radial center of the substrate 50. The second through hole 57 penetrates the substrate 50 in the axial direction. A plurality of second axial support holes 59 are formed on the outer periphery of the substrate 50. Each second axial support hole 59 is axially opposite to each first axial support hole 45.

[0050] 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 block 41 by bolts 60 or the like in a state where it is axially mated with the first block 41. Thus, the first block 41 and the second block 42 rotate integrally with respect to the housing 5 about the axis O1. The portion of the gear carrier 11, excluding the gear carrier flange portion 52, constitutes the main body of the gear carrier 11.

[0051] The gear carrier flange 52 extends radially outward from the portion of the base plate 50 that protrudes axially relative to the housing 5. The gear carrier flange 52 is axially opposite to the second region 21b. The outer diameter of the gear carrier flange 52 is larger than the outer diameter of the cylindrical portion 21 but smaller than the outer diameter of the housing flange 22. A plurality of bolt through holes 61 are formed in the gear carrier flange 52. The bolt through holes 61 penetrate the gear carrier flange 52 axially. The bolt through holes 61 are formed at circumferential intervals. Bolts 62 are held within the bolt through holes 61.

[0052] Bolt 62 is made of a material, such as iron, with a hardness higher than that of the second piece 42. As long as the hardness of bolt 62 is higher than that of gear carrier 11, the combination of bolt 62 and gear carrier 11 (second piece 42) can be appropriately selected. For example, the gear carrier 11 can be made of resin material, and bolt 62 can be made of a metal material with a hardness higher than that of gear carrier 11.

[0053] Bolt 62 has a head 62a, a flange 62b, and a shank 62c. Bolt 62 is positioned with the top end of shank 62c facing a second axial direction. Bolt 62 is inserted into bolt through hole 61 from a first axial direction relative to gear carrier flange 52. Therefore, bolt 62 is radially outward relative to oscillating gears 12 and 13 and axially opposite to cylinder 21.

[0054] The head 62a is housed within the bolt through hole 61. Anti-rotation can also be implemented between the head 62a and the inner circumferential surface of the bolt through hole 61. As an anti-rotation measure, the head 62a and the bolt through hole 61 can also be formed into non-circular shapes when viewed from the axial direction. As an anti-rotation measure, interlocking splines can also be formed on the outer circumferential surface of the head 62a and the inner circumferential surface of the bolt through hole 61.

[0055] A flange 62b extends from the first axial end of the head 62a. The flange 62b is opposite to the gear carrier flange 52 from the first axial side. The flange 62b restricts the movement of the bolt 62 relative to the gear carrier flange 52 to the second axial side.

[0056] The rod portion 62c protrudes axially to a second side from the head 62a. The rod portion 62c protrudes axially to a second side relative to the gear carrier flange portion 52. An external thread portion 62d is formed on the outer peripheral surface of the rod portion 62c.

[0057] Bolt 62 can also be pressed into the bolt through hole 61. If the second piece 42 is made of resin material or the like, bolt 62 can also be fixed to the second piece 42 as a single unit using insert molding or the like.

[0058] The first oscillating gear 12 and the second oscillating gear 13 are arranged axially overlapping inside the central region 21c. The outer diameters of the first oscillating gear 12 and the second oscillating gear 13 are slightly smaller than the inner diameter of the cylindrical portion 21 (central region 21c). 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 mesh with internal teeth 24 (internal tooth pins 26), respectively. The number of teeth on the external teeth 12a and 13a is set to be slightly less than the number of teeth on the internal teeth 24 (for example, one less). There can be one oscillating gear or more than three oscillating gears.

[0059] A first central hole 12b is formed in the center of the first oscillating gear 12. A second central hole 13b is formed in the center of the second oscillating gear 13. The inner diameter of each central hole 12b and 13b is equal to the inner diameter of the first through hole 44.

[0060] A plurality of first clearance holes 12c are formed on the outer periphery of the first oscillating gear 12. Each first clearance hole 12c is spaced apart circumferentially. A plurality of second clearance holes 13c are formed on the outer periphery of the second oscillating gear 13. Each second clearance hole 13c is spaced apart circumferentially at the same interval as the first clearance holes 12c. Corresponding support 51 from a plurality of support columns 51 passes through each clearance hole 12c and 13c. The inner diameter of the clearance holes 12c and 13c is larger than the outer diameter of the support column 51. Therefore, the operation of each oscillating gear 12 and 13 is not obstructed by the support column 51.

[0061] On the outer periphery of the first oscillating gear 12, a first through hole 12d is formed in the portion located between adjacent first clearance holes 12c. On the outer periphery of the second oscillating gear 13, a second through hole 13d is formed in the portion located between adjacent second clearance holes 13c. Each through hole 12d and 13d is arranged at the same spacing as each shaft support hole 45 and 59.

[0062] 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 59 and through holes 12d and 13d. The crankshaft 14 is mounted between the first block 41 and the base plate 50. The crankshaft 14 includes a main shaft 71, a first eccentric portion 72, a second eccentric portion 73, and a protrusion 74.

[0063] 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 in a first shaft support hole 45 by means of a bearing 76. The second axial end of the main shaft 71 is rotatably supported in a second shaft support hole 59 by means of a bearing 77. Bearings 76 and 77 are, for example, angular contact bearings with cylindrical rollers as rolling elements.

[0064] The first eccentric portion 72 is formed in the portion of the main shaft 71 located within the first through hole 12d. The first eccentric portion 72 is eccentric relative to the axis O2 of the main shaft 71. The first eccentric portion 72 is rotatably supported within the first through hole 12d by means of an eccentric portion bearing 81.

[0065] The second eccentric portion 73 is formed in the portion of the main shaft 71 located within the second through hole 13d. The second eccentric portion 73 is eccentric relative to the axis O2 of the main shaft 71. The second eccentric portion 73 is rotatably supported within the second through hole 13d by means of an eccentric portion bearing 82. The phase of each eccentric portion 72, 73 is offset from the axis O2 by, for example, 180°.

[0066] A protrusion 74 protrudes axially from the main shaft 71 to the first side. A transmission gear 85 is mounted on the protrusion 74. The input shaft of the motor (not shown) is directly or indirectly connected to the transmission gear 85. That is, the motor torque is input to the reducer 1 via the transmission gear 85.

[0067] Figure 2 yes Figure 1 An enlarged sectional view of part II.

[0068] like Figure 2 As shown, a second arm 100 of a pair of arms is fixed to the gear carrier flange 52. Specifically, the second arm 100 has a seat 101 opposite to the gear carrier flange 52 and a nut 102 located on the seat 101. A through hole 110 is formed in the seat 101, extending axially through the seat 101. The through hole 110 has a tapered portion 110a and a straight portion 110b. The inner diameter of the tapered portion 110a gradually decreases, for example, from the second axial side toward the first axial side. The straight portion 110b extends from the tapered portion 110a toward the first axial side. A rod portion 62c of a bolt 62 is inserted into the through hole 110.

[0069] The nut 102 has a tapered portion 102a at its first axial end. The nut 102 is located in the seat 101 with the tapered portion 102a embedded in the tapered portion 110a. An internal thread portion 102b is formed on the inner circumferential surface of the nut 102. An external thread portion 62d formed on the rod portion 62c engages with the internal thread portion 102b. Thus, the nut 102 is fastened to the bolt 62 from the second axial side relative to the second arm 100, thereby fixing the second arm 100 to the gear carrier flange portion 52. As long as the bolt 62 can be tightened, the nut 102 and the through hole 110 can also be structured without the tapered portion.

[0070] In the reducer 1 of this embodiment, the motor torque of the motor is input to the reduction mechanism 6 via the transmission gear 85. If each crankshaft 14 rotates in one direction due to the torque transmitted to the transmission gear 85, the eccentric portions 72 and 73 of the crankshaft 14 rotate while being eccentric about the axis O2. As a result, each oscillating gear 12 and 13 oscillates within the housing 5 and rotates about the axis O1 while accompanying the rotation of the eccentric portions 72 and 73. Thus, the oscillating gears 12 and 13 rotate while their external teeth 12a and 13a pass over the internal tooth pins 26 one by one, for example. As the oscillating gears 12 and 13 rotate, the gear carrier 11 rotates about the first axis O1. As a result, the motor torque of the motor, after being reduced by the reduction mechanism 6, is output to the output member as the rotation of the gear carrier 11.

[0071] The torque generated by the rotation of the gear carrier 11 is transmitted to the second arm 100 via bolt 62. As a result, the second arm 100 rotates about axis O1 relative to the first arm.

[0072] Thus, in the reducer 1 of this embodiment, it is provided with a structure that has a bolt 62 protruding from the gear carrier 11 to the outside of the housing 5 and is provided for fastening to the internal thread portion 102b provided on the second arm 100.

[0073] According to this structure, when the gear carrier 11 needs repair due to damage to bolt 62, the repair work can be completed simply by replacing bolt 62 after removing the second arm 100 from the gear carrier 11. Thus, by providing bolt 62 that is separate from the gear carrier 11, compared to the previous structure where the gear carrier 11 itself has an internal thread, the time and cost spent on repair work when the threaded part is damaged can be reduced.

[0074] Furthermore, by using bolts 62 that are separate from the gear carrier 11, the load applied to the gear carrier 11 when tightening to the nut 102 can be reduced. Therefore, it is easy to ensure the tightening force between bolts 62 and nut 102. As a result, the second arm 100 is stably mounted to the reducer 1.

[0075] In the reducer 1 of this embodiment, a bolt through hole 61 is formed in the second block 42. The bolt through hole 61 is designed to accommodate the head 62a and to allow the rod portion 62c to protrude toward the side opposite to the first block 41 along the axis O1.

[0076] According to this structure, it is possible to prevent the head 62a from protruding axially from the second block 42. Therefore, even when the gear carrier 11 is provided with bolts 62, it is possible to prevent the axial enlargement of the reducer 1.

[0077] In the reducer 1 of this embodiment, the gear carrier flange 52, which is opposite to the cylinder 21 in the gear carrier 11, is provided with a bolt through hole 61.

[0078] According to this structure, compared to the case where bolt through holes 61 are formed in the main body (substrate 50, etc.) of the gear carrier 11, there are fewer constraints on the layout of the bolt through holes 61. Therefore, the design freedom of the bolt through holes 61 and bolts 62 is increased. In this case, increasing the number of bolts 62, their nominal diameter, etc., makes it easier to improve the connection strength between the gear carrier 11 and the second arm 100.

[0079] In the reducer 1 of this embodiment, the bolt 62 is made of a material with a hardness higher than that of the gear carrier 11.

[0080] This structure makes it easy to ensure the strength of bolt 62. Therefore, compared to the case where the gear carrier 11 itself has an internal thread, it is easier to ensure the tightening force.

[0081] (Second Implementation)

[0082] Figure 3 This is a perspective sectional view of the reducer 200 according to the second embodiment. The reducer 200 of the second embodiment differs from that of the first embodiment in that it adopts a so-called center crankshaft type. In the center crankshaft type reducer 200, the main shaft 210 of the crankshaft 201 is arranged on the axis O1.

[0083] exist Figure 3 In the reducer 200 shown, the crankshaft 201 passes through the first through hole 44, the first central hole 12b, the second central hole 13b and the second through hole 57 and is mounted between the first block 41 and the second block 42.

[0084] The crankshaft 201 includes a main shaft 210, a first eccentric portion 211, and a second eccentric portion 212.

[0085] The main shaft 210 is a hollow shaft extending along axis O1. The first axial end of the main shaft 210 is rotatably supported within the first through hole 44 by means of bearing 220. The second axial end of the main shaft 210 is rotatably supported within the second through hole 57 by means of bearing 221. The input shaft 214 of a motor is fixed within the main shaft 210. The input shaft 214 of the motor can also be indirectly connected to the main shaft 210 by means of a reduction gear or the like.

[0086] The first eccentric portion 211 extends from the portion of the main shaft 210 located within the first central hole 12b. The first eccentric portion 211 is eccentric relative to the axis O1 of the main shaft 210. The first eccentric portion 211 is rotatably supported within the first central hole 12b by means of an eccentric portion bearing 222.

[0087] The second eccentric portion 212 extends from the portion of the main shaft 210 located within the second central hole 13b. The second eccentric portion 212 is eccentric relative to the axis O1 of the main shaft 210. The second eccentric portion 212 is rotatably supported within the second central hole 13b by means of an eccentric portion bearing 223. The phase of each eccentric portion 211, 212 is offset from the axis O1 by, for example, 180°.

[0088] A first pin through hole 230 is formed on the outer periphery of the first piece 41. Multiple first pin through holes 230 are formed at intervals in the circumferential direction.

[0089] In the substrate 50 of the second piece 42, a second pin through hole 231 is formed at a position opposite to the first pin through hole 230 in the axial direction.

[0090] The first block 41 and the second block 42 are connected by a connecting pin 235. The connecting pin 235 passes through the second pin through hole 231, the second through hole 13d, the first through hole 12d, and the first pin through hole 230 from the second axial side relative to the second block 42. The connecting pin 235 has an external thread 235a at its top end (the first axial end). The external thread 235a protrudes from the first axial side relative to the first block 41. A nut 236 is tightened into the external thread 235a. Washers 237 are respectively located between the outer circumferential surface of the connecting pin 235 and the inner circumferential surface of the first through hole 12d, and between the outer circumferential surface of the connecting pin 235 and the inner circumferential surface of the second through hole 13d.

[0091] The sealing ring 238 is located between the outer peripheral surface of the substrate 50 and the inner peripheral surface of the cylindrical portion 21.

[0092] A bolt through hole 240 is formed in the portion of the outer periphery of the substrate 50 between the second pin through holes 231 that are adjacent in the circumferential direction. The bolt through hole 240 has a large diameter portion 240a and a small diameter portion 240b that is connected to a second side of the large diameter portion 240a in the axial direction.

[0093] A bolt 241 is held within a bolt through hole 240. The bolt 241 passes through the bolt through hole 240 axially from a first side relative to the second block 42. The bolt 241 has a head 241a and a shank 241b. The head 241a is housed within a large-diameter portion 240a. The shank 241b extends axially through a small-diameter portion 240b. An external thread 241c is formed in the portion of the shank 241b protruding from the second block 42. The external thread 241c is fastened to a nut provided on the second arm.

[0094] In this embodiment, bolt 241 is provided on the outer peripheral portion of the base plate 50. Therefore, an external threaded portion 241c is provided on the base plate 50 at a position axially opposite to the second oscillating gear 13, protruding from the second block 42. Thus, a portion of bolt 241 (head 241a, etc.) is housed within the bolt through hole 240. Therefore, even when bolt 241 is provided on the gear carrier 11, axial enlargement of the reducer 200 can be suppressed. Bolt 241 is positioned radially inward relative to the housing 5, thus radial enlargement of the reducer 200 can also be suppressed.

[0095] (Third Implementation)

[0096] Figure 4 This is a perspective sectional view of the reducer 300 according to the third embodiment. The third embodiment differs from the embodiments described above in that it employs a harmonic gear as the reducer 300.

[0097] Figure 4 The reducer 300 shown includes a circular gear (housing) 301, a flexible gear 302, and a wave generator 303. The flexible gear 302 and the wave generator 303 constitute the reduction mechanism.

[0098] The circular gear 301 has a rigidity to the extent that it does not deform under external force. In this embodiment, the rigidity of the circular gear 301 is at least higher than that of the flexible gear 302 (the main body 320 described later), and more preferably, the circular gear 301 has the highest rigidity among the constituent materials of the reducer 300.

[0099] The circular gear 301 has a cylindrical portion 310 and a first flange portion 311.

[0100] The cylindrical portion 310 is configured to be coaxial with the axis O1. Internal teeth 310a are formed on the inner circumferential surface of the cylindrical portion 310.

[0101] A first flange portion 311 extends radially outward from the cylindrical portion 310. A plurality of first bolt through holes 312 are formed in the first flange portion 311. The first bolt through holes 312 penetrate the first flange portion 311 axially. The first bolt through holes 312 are formed at intervals in the circumferential direction. Each bolt through hole 312 has a large-diameter portion 312a and a small-diameter portion 312b connected to a first side of the large-diameter portion 312a in the axial direction.

[0102] A bolt 315 passes through the first bolt through hole 312 from the second side in the axial direction. The head 315a of the bolt 315 is housed within the large-diameter portion 312a. The shaft portion 315b of the bolt 315 passes through the small-diameter portion 312b and protrudes from the first flange portion 311 towards the first side in the axial direction. An external thread portion 315c is formed at the top end of the shaft portion 315b (the portion protruding from the first flange portion 311).

[0103] For example, a first arm (not shown) of a pair of arms is fixed to the first flange portion 311. Specifically, the first arm is fixed to the first flange portion 311 by fastening the external thread portion 315c of the bolt 315 to the nut (not shown). Alternatively, an internal thread portion for fastening the external thread portion 315c may be formed directly on the first arm.

[0104] The flexible gear 302 is shaped like a cap when viewed in cross-section along the axial direction. The flexible gear 302 has a main body 320, a neck 321, and a second flange 322. The main body 320 and the neck 321 are examples of a "cylindrical portion".

[0105] The main body 320 is located inside the cylindrical portion 310. The main body 320 is formed into an annular shape when viewed axially. The circumference of the outer peripheral surface of the main body 320 is shorter than the circumference of the inner peripheral surface of the cylindrical portion 310. External teeth 320a are formed on the outer peripheral surface of the main body 320. The external teeth 320a mesh with internal teeth 310a. The number of teeth on the external teeth 320a is set to be slightly less than the number of teeth on the internal teeth 310a.

[0106] The main body 320 is configured to flex and deform radially. Due to a pressing force acting in the first radial direction, the main body 320 flexes into an ellipse with the first direction as its major axis and a second direction orthogonal to the first direction as its minor axis. When the main body 320 is flexed into an ellipse, the portion of the external tooth 320a overlapping the major axis and the portion surrounding the portion overlapping the major axis mesh with the internal tooth 310a.

[0107] The neck 321 is formed as a cylinder connected to the second axial side of the main body 320. The neck 321 protrudes to the second axial side relative to the cylindrical portion 310 of the circular gear 301. As long as the flexible gear 302 is configured such that at least the main body 320 can flex and deform, the neck 321 may not flex and deform.

[0108] The second flange portion 322 extends radially outward from the second side edge of the neck 321 in the axial direction. Preferably, the rigidity of the second flange portion 322 is higher than that of the main body 320. The second flange portion 322 includes a thin-walled portion 322a located on the inner periphery and a thick-walled portion 322b connected to the outer periphery of the thin-walled portion 322a. The axial dimension of the thick-walled portion 322b is larger than that of the thin-walled portion 322a. In the illustrated example, at least the thick-walled portion 322b of the second flange portion 322 is located radially outward than the first flange portion 311.

[0109] A plurality of second bolt through holes 325 are formed in the second flange portion 322. The second bolt through holes 325 penetrate the second flange portion 322 axially. The second bolt through holes 325 are formed at intervals in the circumferential direction. A bolt 326 passes through the second bolt through hole 325 from the first side in the axial direction. The head 326a of the bolt 326 abuts against the thick-walled portion 322b from the second side in the axial direction. The shaft portion 326b of the bolt 326 passes through the second bolt through hole 325 and protrudes from the second flange portion 322 towards the second side in the axial direction. An external thread portion 326c is formed at the top end of the shaft portion 326b (the portion protruding from the second flange portion 322).

[0110] For example, a second arm (not shown) of a pair of arms is fixed to the second flange portion 322. Specifically, the second arm is fixed to the second flange portion 322 by fastening the external thread portion 326c of the bolt 326 to the nut (not shown). Alternatively, an internal thread portion for fastening the external thread portion 326c may be formed directly on the second arm.

[0111] The wave generator 303 includes a hub 330, a bushing 331, and a wave bearing 332.

[0112] The hub 330 has a connecting shaft 340 and a hub flange 341.

[0113] The connecting shaft 340 is a hollow shaft coaxially disposed inside the circular gear 301 (cylinder 310) with the axis O1. The motor input shaft 350 is fixed to the connecting shaft 340.

[0114] The hub flange 341 extends radially outward from the second axial end of the connecting shaft 340. The hub flange 341 is located on the second axial side of the cylindrical portion 310.

[0115] The bushing 331 is located on the first axial side of the inner side of the cylindrical portion 310 relative to the hub flange portion 341. The bushing 331 is formed into an elliptical shape centered on the axis O1 when viewed axially. The bushing 331 is connected to the hub flange portion 341 by means of a crosshead coupling 345. The crosshead coupling 345 is disposed between the bushing 331 and the hub flange portion 341. The crosshead coupling 345 is connected by a key and a keyway to be able to move radially relative to the bushing 331 and the hub flange portion 341. The bushing 331 is configured such that as the hub 330 rotates, the crosshead coupling 345 moves radially, thereby allowing the bushing 331 to rotate about the axis O1 in response to the rotation of the hub 330.

[0116] The wave bearing 332 is mounted and fixed between the outer peripheral surface of the bushing 331 and the inner peripheral surface of the main body 320. The wave bearing 332 is configured to flex and deform as the bushing 331 rotates. That is, the orientation of the long axis of the wave bearing 332 gradually changes around the axis O1 as the bushing 331 rotates.

[0117] In the reducer 300 of this embodiment, the rotational force of the hub 330 is transmitted to the bushing 331 via the crosshead coupling 345, causing the bushing 331 to rotate about the axis O1. This causes a change in the orientation of the long axis of the wave bearing 332. The main shaft 320 is pushed radially outward by the wave bearing 332, causing it to flex radially. Due to this radial flex, the external teeth 320a and internal teeth 310a formed on the main shaft 320 mesh. As the orientation of the long axis of the wave bearing 332 changes, the external teeth 320a successively cross over the internal teeth 310a. Thus, while the meshing position between the internal teeth 310a and the external teeth 320a changes circumferentially, the flexible gear 302 rotates about the axis O1.

[0118] In the reducer 300 of this embodiment, a bolt 315 is provided on the first flange portion 311 of the circular gear 301. Therefore, when the circular gear 301 needs to be repaired due to damage to the bolt 315, the repair work can be completed simply by replacing the bolt 315 after the first arm is removed from the circular gear 301.

[0119] In the reducer 300 of this embodiment, a bolt 326 is provided on the second flange portion 322 of the flexible gear 302. Therefore, when the flexible gear 302 needs to be repaired due to damage to the bolt 326, the repair work can be completed simply by replacing the bolt 326 after removing the second arm from the flexible gear 302.

[0120] As a result, it can reduce the time and cost spent on repair work when the threaded part is damaged.

[0121] In the third embodiment described above, a structure in which bolts 315 and 326 are respectively provided on each flange portion 311 and 322 has been described, but the structure is not limited to this. The reducer 300 may have a bolt provided on at least one of the flange portions 311 and 322.

[0122] In the above embodiment, the case where the flexible gear 302 is formed into a cap shape has been described, but the flexible gear 302 can also be formed into a cup shape. The opening of the neck 321 of the cup-shaped flexible gear 302 is closed.

[0123] (Other variations)

[0124] 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 can be made without departing from the spirit of the present invention. The present invention is not limited by the foregoing description, but only by the appended claims.

[0125] In the above embodiments, an example of a connecting component was described using the arm of an industrial robot, but the embodiment is not limited to this structure. The connecting component could also be the arm of industrial equipment (e.g., construction machinery).

[0126] Furthermore, without departing from the spirit of the present invention, the constituent elements in the above embodiments may be appropriately replaced with well-known constituent elements, and the above-described variations may also be appropriately combined.

Claims

1. A speed reducer comprising: a housing; a speed reduction mechanism portion having a transmission portion provided so as to be rotatable relative to the housing, the speed reduction mechanism portion being provided in the housing and reducing and outputting rotation input from a drive source; and a bolt protruding from the transmission portion toward the outside of the housing, the bolt having an external thread portion for fastening with an internal thread portion provided to a connecting member, an internal tooth being provided to the inner periphery of the housing, the speed reduction mechanism portion comprising: a crankshaft connected to an input shaft of the drive source, having an eccentric portion that rotates eccentrically relative to the rotational axis of the transmission portion; and a swing gear having an external tooth that meshes with the internal tooth, the swing gear turning within the housing while making the external tooth thereof straddle the internal tooth as the eccentric portion rotates eccentrically, the transmission portion rotating around the rotational axis as the swing gear turns, the transmission portion comprising: a first block disposed on a first side relative to the swing gear in the direction along the rotational axis; and a second block having a base plate disposed on a second side relative to the swing gear in the direction along the rotational axis, the second block being joined to the first block in a state of penetrating the swing gear, the bolt being provided in a state of penetrating only the second block, and the external thread portion protruding from the second block.

2. The speed reducer according to claim 1, wherein the bolt comprises: a head portion; and a shaft portion protruding from the head portion and formed with the external thread portion, a bolt penetration hole being formed in the transmission portion, the bolt penetration hole receiving the head portion and making the shaft portion protrude from the transmission portion.

3. The speed reducer according to claim 2, wherein the transmission portion comprises: a main body portion including the base plate, extending within the housing along the rotational axis of the transmission portion; and a flange portion protruding from the base plate in the radial direction of the rotational axis and opposing the housing in the direction along the rotational axis, the bolt penetration hole being formed in the flange portion.

4. The speed reducer according to claim 1 or 2, wherein the bolt is formed of a material having a higher hardness than the hardness of the transmission portion.

5. The speed reducer according to claim 1, wherein the bolt is provided in a state of penetrating only a position in the base plate that opposes the swing gear in the direction along the rotational axis, and the external thread portion protrudes from the base plate. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

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