reducer

Abstract

A speed reducer is provided. The speed reducer includes a speed reduction mechanism portion and a transmission gear (40). The transmission gear is fixed in the axial direction by a drop-off limiting member in a state of being spline-engaged with an end portion of an input shaft. The transmission gear is engaged with an input gear (30) driven by a drive source and transmits driving force from the input gear to the input shaft. A recess (45) is provided on an outer side end surface of the transmission gear, and the recess accommodates an engagement portion of the end portion of the input shaft engaged with the drop-off limiting member. The recess is formed so as to satisfy two conditions: an engagement width (w2) in which the input shaft is engaged with the splines of the transmission gear is 60% or more of a tooth width (w1) of the transmission gear; and an axial center (ac) of the tooth width of the transmission gear is orthogonal to a plane (S1) in which the engagement width in which the input shaft is engaged with the splines of the transmission gear is located.

Description

Technical Field

[0001] This invention relates to speed reducers. Background Technology

[0002] In industrial robots, machine tools, etc., speed reducers are used to reduce the rotation of drive sources such as motors (for example, see Patent Document 1).

[0003] The reducer described in Patent Document 1 has internal teeth on the inner circumference of a cylindrical housing. A reduction mechanism is housed inside the housing, which meshes with the internal teeth to reduce the input rotation. The reduction mechanism includes: a gear carrier rotatably held in the housing; a crankshaft (input shaft) rotatably supported on the gear carrier; and an oscillating gear that oscillates and rotates due to a rotational force received from the eccentric portion of the crankshaft.

[0004] The oscillating gear has external teeth that mesh with the internal teeth of the housing, having fewer teeth than the internal teeth of the housing. A transmission gear (spur gear) is mounted on the crankshaft of the reduction mechanism section in a manner that allows it to rotate integrally with the crankshaft. The transmission gear meshes with the input gear on the drive source side.

[0005] In this reducer, if rotational power is transmitted to the crankshaft via the input gear and the transmission gear, the eccentric portion of the crankshaft rotates eccentrically, thereby activating the reduction mechanism. As a result, the power from the drive source side is reduced in speed by the reduction mechanism at a predetermined reduction ratio and output to the gear carrier or housing.

[0006] Furthermore, in the reducer described in Patent Document 1, an external spline is formed at the end of the crankshaft, and an internal spline is formed on the transmission gear mounted on the crankshaft.

[0007] The external spline of the crankshaft has a plurality of spline teeth formed at intervals in the circumferential direction of the crankshaft. The plurality of spline teeth are formed to extend from the end of the crankshaft along the axial direction of the crankshaft toward the reduction gear section. Furthermore, the external spline has a groove located between adjacent spline teeth in the circumferential direction. An inclined portion is provided at the end of the groove located on the reduction gear section side. The inclined portion is inclined in the groove in such a way that it extends radially outward toward the reduction gear section side of the crankshaft.

[0008] Therefore, when the internal spline of the transmission gear engages with the external spline of the crankshaft, the teeth of the internal spline of the transmission gear bite into the inclined portion on the side of the external spline. This suppresses the wobble of the transmission gear.

[0009] Existing technical documents

[0010] Patent documents

[0011] Patent Document 1: Japanese Patent Application Publication No. 2014-92249 Summary of the Invention

[0012] The problem the invention aims to solve

[0013] In the reducer described in Patent Document 1, the end of the crankshaft protrudes outward in the axial direction from the end face of the gear carrier. Furthermore, a transmission gear is mounted on the protruding end of the crankshaft. The transmission gear engages with the end spline of the crankshaft and is axially fixed to the crankshaft by a release restraint member such as a retaining ring to maintain the engagement.

[0014] At this point, due to the engagement between the detachment limiting member and the outer periphery of the crankshaft, the axial end of the crankshaft needs to protrude a certain length beyond the end face of the transmission gear in the axial direction. Therefore, the crankshaft length increases by the amount protruding from the end face of the transmission gear. Consequently, the miniaturization of the entire reducer is hindered by the increased crankshaft length.

[0015] Therefore, as a countermeasure to these problems, a structure is considered, for example, to provide a recess on the end face of the transmission gear (the end face facing the outer side in the axial direction) and to arrange the engagement part of the crankshaft end that engages with the disengagement limiting member inside the recess.

[0016] In this case, since the detachment limiting member is disposed within the recess of the transmission gear, the crankshaft length can be shortened. However, in this case, the meshing portion of the transmission gear engaging with the spline of the crankshaft will be biased axially inwards relative to the recess.

[0017] As a result, the axial center of the tooth width of the transmission gear and the axial center of the meshing part (the spline-formed meshing part) between the transmission gear and the crankshaft will be axially misaligned. This phenomenon causes the transmission gear to wobble during power transmission. Furthermore, this wobble behavior easily contributes to the vibration and noise generated when the reducer is operating.

[0018] The purpose of this invention is to provide a speed reducer that can shorten the shaft length of the input shaft of the speed reduction mechanism and suppress the generation of vibration noise during operation.

[0019] Solution for solving the problem

[0020] A speed reducer according to one embodiment of the present invention comprises: a speed reduction mechanism having an input shaft for reducing and outputting rotational speed input to the input shaft; and a transmission gear, which, in a state of spline engagement with the end of the input shaft, is axially fixed by a disengagement limiting member and meshes with an input gear driven by a drive source to transmit driving force from the input gear to the input shaft. A recess is provided on the outer end face of the transmission gear facing outward in the axial direction, the recess receiving the engagement portion of the end of the input shaft engaging with the disengagement limiting member. The recess is formed to satisfy the following two conditions: the meshing width of the spline engagement between the input shaft and the transmission gear is 60% or more of the tooth width of the transmission gear; and an orthogonal plane of the axis passing through the axial center of the tooth width of the transmission gear is located within the range of the meshing width of the spline engagement between the input shaft and the transmission gear.

[0021] In this structure, a recess is provided on the outer end face of the transmission gear, and an engaging portion that engages with the end of the input shaft and the disengagement restraint member is housed in this recess. Therefore, the outer end of the input shaft in the axial direction does not protrude significantly beyond the outer side of the transmission gear in the axial direction. Thus, the shaft length of the input shaft can be shortened.

[0022] In addition, in this structure, a recess is formed on the outer end face of the transmission gear in a manner that satisfies the following two conditions (condition 1) and (condition 2).

[0023] (Condition 1) The meshing width of the spline engagement between the input shaft and the transmission gear is more than 60% of the tooth width of the transmission gear.

[0024] (Condition 2) The plane orthogonal to the axis of the center of the tooth width of the transmission gear lies within the range of the meshing width of the spline engagement between the input shaft and the transmission gear.

[0025] Therefore, when the input gear meshes with the transmission gear to transmit power, it is less likely for the transmission gear to exhibit swaying behavior. Thus, in this reducer structure, the generation of vibration noise caused by the swaying behavior of the transmission gear can be suppressed.

[0026] Another embodiment of the present invention provides a reducer comprising: a housing having internal teeth on its inner circumference; a gear carrier rotatably held in the housing; a crankshaft rotatably supported on the gear carrier, which is subjected to an external rotational force to rotate its eccentric portion; an oscillating gear having external teeth that mesh with the internal teeth in a number fewer than the number of teeth of the internal teeth, which is subjected to a rotational force from the eccentric portion of the crankshaft and oscillates to output rotational force to the gear carrier; and a transmission gear, which is axially fixed by a disengagement limiting member in a state of engagement with the end spline of the crankshaft, and meshes with an input gear driven by a drive source to transmit driving force from the input gear to the crankshaft. A recess is provided on the outer end face of the transmission gear facing outward in the axial direction, the recess receiving the engagement portion of the end of the crankshaft engaging with the disengagement limiting member. The recess is formed to satisfy the following two conditions: the meshing width of the spline engagement between the crankshaft and the transmission gear is more than 60% of the tooth width of the transmission gear; and the orthogonal plane of the axis passing through the center of the tooth width of the transmission gear is located within the range of the meshing width of the spline engagement between the crankshaft and the transmission gear.

[0027] In this structure, a recess is provided on the outer end face of the transmission gear, and an engaging portion that engages with the end of the crankshaft and the disengagement restraining member is housed in this recess. Therefore, the outer end of the crankshaft in the axial direction does not protrude significantly beyond the outer side of the transmission gear in the axial direction. Thus, the crankshaft length can be shortened.

[0028] In addition, in this structure, a recess is formed on the outer end face of the transmission gear in a manner that satisfies the following two conditions (condition 1A) and (condition 2A).

[0029] (Condition 1A) The meshing width of the spline engagement between the crankshaft and the transmission gear is more than 60% of the tooth width of the transmission gear.

[0030] (Condition 2A) The plane orthogonal to the axis of the center of the tooth width of the transmission gear lies within the range of the meshing width of the spline engagement between the crankshaft and the transmission gear.

[0031] Therefore, when the input gear meshes with the transmission gear to transmit power, it is less likely for the transmission gear to exhibit swaying behavior. Thus, in this reducer structure, the generation of vibration noise caused by the swaying behavior of the transmission gear can be suppressed.

[0032] Furthermore, in particular, in the reducer of this technical solution, the gear carrier rotates as an output rotating body during operation. Therefore, in a configuration where the crankshaft is supported at a position offset from the rotation center of the gear carrier, the transmission gear rotates while meshing with the input gear around the rotation center of the gear carrier. In this case, due to changes in the output of the drive source, forces easily act on the transmission gear in a manner that causes swaying behavior. However, in this structure, a recess is formed on the outer end face of the transmission gear to satisfy both conditions (Condition 1A) and (Condition 2A). Therefore, the generation of vibration noise caused by the swaying behavior of the transmission gear can be effectively suppressed.

[0033] The effects of the invention

[0034] According to the present invention, the speed reducer can shorten the shaft length of the input shaft of the speed reduction mechanism and suppress the generation of vibration noise during operation. Attached Figure Description

[0035] Figure 1 This is a side view of an industrial robot equipped with a speed reducer.

[0036] Figure 2 This is a schematic front view of the speed reducer according to the implementation method.

[0037] Figure 3 The reducer in the implementation method is along Figure 2 A cross-sectional view along line III-III.

[0038] Figure 4 The reducer is an implementation method Figure 3 Enlarged view of part IV.

[0039] Figure 5 These are cross-sectional views of the transmission gear in the embodiment and the transmission gear in the comparative example.

[0040] Explanation of reference numerals in the attached figures

[0041] 10. Reducer; 11. Housing; 13A. First gear carrier module (gear carrier); 13B. Second gear carrier module (gear carrier); 14. Crankshaft (input shaft); 15A. First oscillating gear (oscillating gear); 15B. Second oscillating gear (oscillating gear); 30. Input gear; 35. Reduction mechanism section; 40. Transmission gear; 45. Recess; 48. Retaining ring (detachment limiting member); ac. Axial center; S1. Orthogonal plane of axis; w1. Tooth width; w2. Spline meshing width. Detailed Implementation

[0042] Next, embodiments of the present invention will be described with reference to the accompanying drawings.

[0043] Figure 1 This is a side view of an industrial robot 100 that employs the reducer 10 of the embodiment.

[0044] like Figure 1 As shown, the industrial robot 100 is used, for example, for tasks such as component supply and assembly in the manufacture of precision equipment. The industrial robot 100 of this embodiment includes a base 110, a first arm 120, a second arm 130, a working head 140, and an end effector 150.

[0045] The base 110 includes a motor 160 and a reducer 10. The motor 160 is a drive source such as a servo motor. The first arm 120 is connected to the output of the reducer 10.

[0046] The first arm 120 rotates about axis O1. The power of the motor 160 is reduced by the reducer 10 at a predetermined reduction ratio and transmitted to the first arm 120. The second arm 130 is rotatably connected to the front end of the first arm 120.

[0047] The second arm 130 rotates about an axis parallel to axis O1. The second arm 130 rotates using the power of a motor (not shown). A working head 140 is held at the front end of the second arm 130.

[0048] An end effector 150, such as a robotic arm, is mounted on the work head 140. The end effector 150 operates using power from a motor (not shown).

[0049] Figure 2 This is the front view of the reducer 10 when viewed from the input side (the side connected to the motor 160).

[0050] like Figure 2 As shown, the reducer 10 includes three transmission gears 40 (40A, 40B, 40C) composed of spur gears and an input gear 30 composed of spur gears. The input gear 30 is connected to the motor 160 (see reference). Figure 1 The output shaft is connected. Both the transmission gear 40 and the input gear 30 are involute gears.

[0051] exist Figure 2 The diagram shows the central axis O1 of the input gear 30 and the central axes C1, C2, and C3 of the three transmission gears 40A, 40B, and 40C. The central axis O1 of the input gear 30 coincides with the central axis O1 of the gear carriers (first gear carrier module 13A and second gear carrier module 13B), which will be described later. Furthermore, the central axis O1 of the input gear 30 also coincides with the central axis O1 of the first arm 120 (see reference). Figure 1 The axis O1 of the rotation center of ) is consistent.

[0052] Three transmission gears 40A, 40B, and 40C are arranged at approximately equal intervals on an imaginary circle centered on the central axis O1 of the input gear 30. The central axes C1, C2, and C3 of each transmission gear 40A, 40B, and 40C coincide with the central axes C1, C2, and C3 of the three crankshafts 14, which will be described later. Each tooth 40a (external tooth) of the three transmission gears 40A, 40B, and 40C meshes with the tooth 30a (external tooth) of the input gear 30.

[0053] The rotation input from motor 160 to input gear 30 is transmitted equally to the three transmission gears 40A, 40B, and 40C as a rotation in the opposite direction to the rotation of input gear 30.

[0054] Figure 3 It is along Figure 2 A cross-sectional view along line III-III.

[0055] like Figure 3 As shown, the reducer 10 includes a cylindrical housing 11, a first gear carrier module 13A, a second gear carrier module 13B, three crankshafts 14, a first oscillating gear 15A, and a second oscillating gear 15B.

[0056] The first gear carrier module 13A and the second gear carrier module 13B are rotatably held on the inner circumference of the housing 11. Three crankshafts 14 are rotatably supported on the first gear carrier module 13A and the second gear carrier module 13B. The first oscillating gear 15A and the second oscillating gear 15B rotate together with the two eccentric portions 14b of each crankshaft 14.

[0057] In this embodiment, the housing 11 is fixed to the base 110 of the industrial robot 100. The first gear carrier module 13A and the second gear carrier module 13B constitute a gear carrier that functions as an output rotating body. The first oscillating gear 15A and the second oscillating gear 15B constitute oscillating gears that oscillate and rotate due to rotational force received from the eccentric portion 14b of the crankshaft 14.

[0058] The first gear carrier module 13A has a perforated circular plate-shaped base plate portion 13Aa and a plurality of support portions 13Ab extending from the end face of the base plate portion 13Aa toward the second gear carrier module 13B.

[0059] The second gear carrier module 13B is formed as an open circular plate. The first gear carrier module 13A is assembled with the second gear carrier module 13B with the end face of the support portion 13Ab in contact with the end face of the second gear carrier module 13B. Each support portion 13Ab is fastened to the second gear carrier module 13B using bolts 16.

[0060] In addition, the second gear carrier module 13B is provided with a positioning pin 17, which is used to position the second gear carrier module 13B relative to each support portion 13Ab before fastening with bolts 16.

[0061] An axial gap (separation space) is ensured between the base plate portion 13Aa of the first gear carrier module 13A and the second gear carrier module 13B. The first oscillating gear 15A and the second oscillating gear 15B are arranged in this gap (separation space).

[0062] Furthermore, clearance holes 19 are formed in the first oscillating gear 15A and the second oscillating gear 15B respectively, for each support portion 13Ab of the first gear carrier module 13A to pass through. The clearance holes 19 are formed to be sufficiently large compared to the outer shape of the support portion 13Ab, so as to avoid the support portion 13Ab from obstructing the rotational movement of the first oscillating gear 15A and the second oscillating gear 15B.

[0063] The shell 11 has a cylindrical shell body 11a and a flange 11b that protrudes radially outward from the outer periphery of the shell body 11a. The shell body 11a and the flange 11b are integrally formed, for example, by casting.

[0064] The housing body 11a is arranged across the outer peripheral surface of the base plate portion 13Aa of the first gear carrier module 13A and the outer peripheral surface of the second gear carrier module 13B. The base plate portion 13Aa of the first gear carrier module 13A and the second gear carrier module 13B are rotatably supported on both axial sides of the housing body 11a by means of bearings 12.

[0065] In the housing body 11a, a plurality of pin grooves 18 are formed on the inner peripheral surface of a central region located axially in the center (the region opposite to the outer peripheral surfaces of the first oscillating gear 15A and the second oscillating gear 15B), extending parallel to the rotation center (central axis O1) of the first gear carrier module 13A and the second gear carrier module 13B. Each pin groove 18 rotatably accommodates a cylindrical internal toothed pin 20. The plurality of internal toothed pins 20 mounted on the inner peripheral surface (pin groove 18) of the housing body 11a are opposite to the outer peripheral surfaces of the first oscillating gear 15A and the second oscillating gear 15B.

[0066] In this embodiment, the internal toothed pin 20 installed in the pin groove 18 constitutes the internal teeth of the housing 11.

[0067] The first oscillating gear 15A and the second oscillating gear 15B are formed with an outer diameter slightly smaller than the inner diameter of the housing body 11a. External teeth 15Aa and 15Ba are formed on the outer peripheral surfaces of the first oscillating gear 15A and the second oscillating gear 15B, respectively, and engage with a plurality of internal toothed pins 20 disposed on the inner peripheral surface of the housing body 11a. The number of teeth 15Aa and 15Ba of the first oscillating gear 15A and the second oscillating gear 15B is set to be slightly less than the number of internal toothed pins 20 (pin grooves 18) (for example, one less).

[0068] Three crankshafts 14 are arranged on the same circumference centered on the rotation center (central axis O1) of the first gear carrier module 13A and the second gear carrier module 13B. Each crankshaft 14 is rotatably supported on the first gear carrier module 13A and the second gear carrier module 13B by means of bearings 21.

[0069] Each crankshaft 14 has a pair of shaft support portions 14a arranged axially apart and two eccentric portions 14b disposed between the pair of shaft support portions 14a. At one end of the crankshaft 14 in the axial direction, a gear mounting portion 14c is formed adjacent to the shaft support portion 14a. Each shaft support portion 14a passes through a shaft support hole 13Aa-1 formed in the first gear carrier module 13A (base plate portion 13Aa) and a shaft support hole 13Ba-1 formed in the second gear carrier module 13B. Each shaft support portion 14a is rotatably supported in the shaft support holes 13Aa-1 and 13Ba-1 by means of a bearing 21.

[0070] Each crankshaft 14 has a gear mounting portion 14c that passes through the shaft support hole 13Ba-1 of the second gear carrier module 13B and protrudes axially outward from the second gear carrier module 13B. Transmission gears 40 (40A, 40B, 40C) are mounted on the gear mounting portion 14c. The transmission gears 40 (40A, 40B, 40C) are connected to the gear mounting portion 14c in a manner that allows them to rotate integrally with the gear mounting portion 14c of the crankshaft 14.

[0071] The central axes of the two eccentric portions 14b of the crankshaft 14 are eccentric relative to the central axis of the shaft support portion 14a. In addition, the two eccentric portions 14b are eccentric in such a way that their phases are offset by 180° around the central axis of the shaft support portion 14a.

[0072] Each eccentric portion 14b of the crankshaft 14 passes through the first oscillating gear 15A and the second oscillating gear 15B respectively. Each eccentric portion 14b is rotatably engaged with the support holes 22 formed in the first oscillating gear 15A and the second oscillating gear 15B respectively by means of the eccentric bearing 23 (cylindrical roller bearing).

[0073] In the reducer 10 of this embodiment, when the plurality of crankshafts 14 are subjected to an external force and rotate in one direction, each eccentric portion 14b of the crankshaft 14 rotates in the same direction with a predetermined radius. As a result, the first oscillating gear 15A and the second oscillating gear 15B rotate (oscillate) in the same direction with the same radius as each eccentric portion 14b rotates. At this time, each external tooth 15Aa and 15Ba of the first oscillating gear 15A and the second oscillating gear 15B contacts in meshing manner with a plurality of internal toothed pins 20 held on the inner circumference of the housing body 11a.

[0074] In the reducer 10 of this embodiment, the number of teeth 15Aa and 15Ba of the external teeth of the first oscillating gear 15A and the second oscillating gear 15B is set to be slightly less than the number of internal tooth pins 20 on the housing body 11a side (for example, one less). Therefore, during the period when the first oscillating gear 15A and the second oscillating gear 15B rotate one revolution according to the rotation of the crankshaft 14, the first oscillating gear 15A and the second oscillating gear 15B are rotated by the reaction force in the direction of rotation from the internal tooth pins 20 on the housing body 11a side, and then revolve in the opposite direction of rotation by a predetermined tooth pitch. As a result, the first gear carrier module 13A and the second gear carrier module 13B, which engage with the first oscillating gear 15A and the second oscillating gear 15B by means of the crankshaft 14, rotate together with the first oscillating gear 15A and the second oscillating gear 15B in the same direction with the same tooth pitch.

[0075] As a result, the rotation of crankshaft 14 is reduced at a predetermined reduction ratio and output as the rotation of the first gear carrier module 13A and the second gear carrier module 13B. In this embodiment, the first gear carrier module 13A and Figure 1 The first arm 120 is connected as shown. Therefore, the rotation after being reduced by the reducer 10 is output as the rotation of the first arm 120.

[0076] Furthermore, in this embodiment, since the two eccentric portions 14b of the crankshaft 14 are eccentrically offset by 180° around the central axes C1, C2, and C3, the rotation phases of the first oscillating gear 15A and the second oscillating gear 15B are offset by 180°.

[0077] In this embodiment, the housing 11, the first gear carrier module 13A, the second gear carrier module 13B, the first oscillating gear 15A, the second oscillating gear 15B, the crankshaft 14, etc., constitute the reduction mechanism section 35 of the reducer 10. In addition, the crankshaft 14 constitutes the input shaft of the reduction mechanism section 35.

[0078] Figure 4 yes Figure 3 An enlarged view of section IV of the reducer 10 shown.

[0079] like Figure 4As shown, an external spline 52 is formed on the outer peripheral surface of the gear mounting portion 14c, which protrudes outward from the second gear carrier module 13B in the crankshaft 14. An engagement hole 51 is formed in the axial center of the transmission gear 40, extending through the transmission gear 40. An internal spline 53 is formed on the inner peripheral surface of the engagement hole 51.

[0080] The internal spline 53 of the transmission gear 40 engages with the external spline 52 of the crankshaft 14. With the internal spline 53 engaged (fitted) with the external spline 52 on the crankshaft 14 side, the transmission gear 40 is axially fixed to the crankshaft 14 by a pair of retaining rings 48, which act as release restraints. The pair of retaining rings 48 are positioned axially inside the transmission gear 40 (on the side opposite to the second gear carrier module 13B) and axially outside the transmission gear 40 (on the side away from the second gear carrier module 13B). Furthermore, the pair of retaining rings 48 are mounted on the outer circumferential surface of the crankshaft 14 in their respective positions.

[0081] Furthermore, an annular locking groove 54 is formed on the outer peripheral surface of the crankshaft 14. Each retaining ring 48 is locked into the corresponding locking groove 54.

[0082] Furthermore, a recess 45 is formed on the outer end face of the transmission gear 40 facing outward in the axial direction. This recess 45 receives the engagement portion of the end of the crankshaft 14 (the portion protruding from the engagement hole 51) that engages with the retaining ring 48. In this embodiment, the recess 45 is formed in a circular shape in the front view. The recess 45 is formed with an inner diameter that allows for the installation and removal of the retaining ring 48 relative to the end of the crankshaft 14 on the inner circumferential side of the recess 45.

[0083] The recess 45 of the transmission gear 40 is formed to satisfy the following two conditions (condition 1A) and (condition 2A).

[0084] • (Condition 1A) The meshing width w2 of the spline engagement between the crankshaft 14 and the transmission gear 40 is more than 60% of the tooth width w1 of the transmission gear 40.

[0085] • (Condition 2A) The plane S1, which is orthogonal to the axis of the center ac of the tooth width w1 of the transmission gear 40, is located within the range of the meshing width w2 of the spline meshing between the crankshaft 14 and the transmission gear 40.

[0086] In addition, "orthogonal plane S1" refers to the plane that passes through the center ac of the meshing part in the axial direction and is orthogonal to the central axis C1 (C2, C3) of the transmission gear 40.

[0087] Furthermore, while the reducer 10 of this embodiment employs an eccentric swing-type reduction mechanism section as the reduction mechanism section 35, the aforementioned rotary input section structure can also be applied to reducers employing reduction mechanism sections other than the eccentric swing type. In this case, the transmission gear 40 can be mounted on the input shaft of the reduction mechanism section in the same manner as described above.

[0088] At this time, the recess 45 of the transmission gear is formed to satisfy the following two conditions (condition 1) and (condition 2).

[0089] • (Condition 1) The meshing width w2 of the spline engagement between the input shaft and the transmission gear 40 is more than 60% of the tooth width w1 of the transmission gear 40.

[0090] • (Condition 2) The plane S1, which is orthogonal to the axis of the center ac of the tooth width w1 of the transmission gear 40, is located within the range of the meshing width w2 of the spline meshing between the input shaft and the transmission gear 40.

[0091] <Effects of the speed reducer in the implementation method>

[0092] In this embodiment, the reducer 10 has a recess 45 formed on the outer end face of the transmission gear 40 facing axially. The recess 45 houses the engagement portion of the input shaft (crankshaft 14) of the reduction mechanism 35, which engages with the retaining ring 48 (disengagement limiting member). Therefore, the outer end of the input shaft (crankshaft 14) does not protrude significantly beyond the outer side of the transmission gear 40 facing axially.

[0093] Furthermore, in the reducer 10 of this embodiment, a recess 45 is formed on the end face of the transmission gear 40 to satisfy both conditions (condition 1) and (condition 2). Therefore, when the input gear 30 meshes with the transmission gear 40 to transmit power, the meshing load acting between the input gear 30 and the transmission gear 40 is stably borne by the spline engagement portion between the crankshaft 14 and the transmission gear 40. Thus, when the reducer 10 is operating, swaying behavior is less likely to occur in the transmission gear 40.

[0094] As a result, when the reducer 10 of this embodiment is used, the shaft length of the input shaft of the reduction mechanism 35 can be shortened and the generation of vibration noise during operation can be suppressed.

[0095] Figure 5 These are cross-sectional views (a) of the transmission gear 40 that satisfies conditions (1) and (2), and (b) of the transmission gear 40′ that does not satisfy conditions (1) and (2).

[0096] Figure 5The transmission gear 40 shown in the cross-sectional view (a) has a recess 45 formed such that the meshing width w2 of the input shaft (crankshaft 14) meshing with the spline of the transmission gear 40 is 60% of the tooth width w1 of the transmission gear 40. In addition, the plane S1 orthogonal to the axis of the center ac of the tooth width w1 of the transmission gear 40 is located within the range of the meshing width w2.

[0097] Figure 5 The sectional view (b) shows that the transmission gear 40′ has a recess 45 formed such that the meshing width w2′ of the spline engagement between the input shaft (crankshaft 14) and the transmission gear 40′ is 50% of the tooth width w1 of the transmission gear 40′. However, the plane S1 orthogonal to the axis of the center ac of the tooth width w1 of the transmission gear 40′ deviates from the range of the meshing width w2′.

[0098] Under the same conditions, for the installation Figure 5 The sectional view (a) shows the reducer of the transmission gear 40 and the gear mounted thereon. Figure 5 The reducer with transmission gear 40′ shown in the sectional view (b) underwent a noise test.

[0099] Used Figure 5 The noise generated in the case of transmission gear 40 shown in the cross-sectional view (a) is 73.5 dBA. In contrast, using... Figure 5 The noise generated in the case of transmission gear 40′ shown in the sectional view (b) is 75 dBA.

[0100] After adopting Figure 5 In the case of the transmission gear 40 of this embodiment shown in the cross-sectional view (a), compared with the one adopted... Figure 5 Compared to the case of the transmission gear 40′ shown in the cross-sectional view (b), the stiffness of the meshing part that meshes with the input gear 30 is increased by about 10% to 15%, and the noise level is improved by about 1.0 to 2.0 bBA.

[0101] As can be seen from the noise test results above, when the recess 45 of the transmission gear 40 is formed in a manner that satisfies both conditions (1) and (2), the noise generated can be suppressed to a level that is inconsequential to the operator. Conversely, when the recess 45 is formed with specifications that do not satisfy both conditions (1) and (2), the noise generated cannot be suppressed to a level that is inconsequential to the operator.

[0102] In addition, the reducer 10 of this embodiment adopts an eccentric swing type reduction mechanism as the reduction mechanism 35, and the crankshaft 14 is supported at a position offset from the rotation center (axis O1) of the gear carrier (first gear carrier module 13A and second gear carrier module 13B).

[0103] Furthermore, in the reducer 10, the transmission gear 40 rotates around the rotation center of the gear carrier while meshing with the input gear 30. Therefore, when transmitting rotational power, due to changes in the output of the drive source, complex torques are applied to the transmission gear 40 from multiple directions, which can easily cause the transmission gear 40 to wobble.

[0104] However, in the reducer 10 according to this embodiment, a recess 45 is formed on the end face of the transmission gear 40 in a manner that satisfies both conditions (condition 1A) and (condition 1B). Therefore, the shaft length of the crankshaft 14 can be shortened and the generation of vibration noise caused by the rocking behavior of the transmission gear 40 can be effectively suppressed.

[0105] Furthermore, the present invention is not limited to the embodiments described above, and various design changes can be made without departing from its spirit. For example, the reducer 10 of this embodiment has two oscillating gears (first oscillating gear 15A and second oscillating gear 15B), but the number of oscillating gears may be one, or even three or more.

[0106] Furthermore, in the above embodiment, a retaining ring 48 is used as a detachment limiting member for axially fixing the transmission gear 40 to the end of the input shaft (crankshaft 14), but the detachment limiting member is not limited to a retaining ring. As a detachment limiting member, any member capable of axially fixing the transmission gear 40 to the input shaft (crankshaft 14) can also be a member of other forms, such as a pin.

[0107] Furthermore, in the above embodiment, the housing 11 side of the reducer 10 is fixed to the base, and the gear carrier (first gear carrier module 13A and second gear carrier module 13B) rotates as an output rotating body. However, it is also possible to reverse the configuration, fixing the gear carrier side to the base and using the housing 11 side as the output rotating body.

[0108] Furthermore, in the above embodiment, the reducer 10 is applied to the drive unit of the industrial robot 100, but the application of the reducer 10 is not limited to the drive unit of the industrial robot 100. As a reducer 10, it can also be applied to the drive units of various other equipment such as machine tools other than the industrial robot 100.

[0109] Furthermore, in the embodiments disclosed in this specification, for a component composed of multiple objects, these multiple objects can also be integrated into one, or conversely, a component composed of a single object can be divided into multiple objects. Whether or not they are integrated, as long as the configuration achieves the purpose of the invention, it is acceptable.

Claims

1. A speed reducer, wherein, This reducer has the following features: The speed reduction mechanism has an input shaft that reduces the rotation input to the input shaft and outputs it; and A transmission gear, which is axially fixed by a disengagement limiting member in a splined engagement with the end of the input shaft, meshes with an input gear driven by a drive source to transmit driving force from the input gear to the input shaft. The outer end face of the transmission gear facing outward in the axial direction has a recess that accommodates the engagement portion of the input shaft that engages with the disengagement limiting member. The recess is formed to satisfy the following two conditions: the meshing width of the spline engagement between the input shaft and the transmission gear is more than 60% of the tooth width of the transmission gear; and the orthogonal plane of the axis passing through the center of the tooth width of the transmission gear is located within the range of the meshing width of the spline engagement between the input shaft and the transmission gear.

2. A speed reducer, wherein, This reducer has the following features: The shell has internal teeth on its inner circumference; A gear carrier, which is rotatably held in the housing; A crankshaft, which is rotatably supported on the gear carrier, is subjected to an external rotational force that causes the eccentric portion of the crankshaft to rotate. The oscillating gear has external teeth that mesh with the internal teeth in a number fewer than the number of teeth of the internal teeth. It oscillates and rotates due to the rotational force from the eccentric part of the crankshaft, and outputs the rotational output to the gear carrier. as well as A transmission gear, which is axially fixed by a disengagement limiting member in a state of engagement with the end spline of the crankshaft, meshes with an input gear driven by a drive source to transmit driving force from the input gear to the crankshaft. The outer end face of the transmission gear facing outward in the axial direction has a recess that accommodates the engagement portion of the crankshaft end that engages with the disengagement limiting member. The recess is formed to satisfy the following two conditions: the meshing width of the spline engagement between the crankshaft and the transmission gear is more than 60% of the tooth width of the transmission gear; and the orthogonal plane of the axis passing through the center of the tooth width of the transmission gear is located within the range of the meshing width of the spline engagement between the crankshaft and the transmission gear.

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