Eccentric oscillating reducer

Abstract

To provide a technology capable of suppressing an axial movement amount of an input shaft when a speed reducer is separated from a motor, while reducing the weight of the speed reducer.SOLUTION: An eccentric oscillation type speed reducer comprises an input shaft 26, an eccentric body provided on the input shaft 26, and an external gear 30 that is oscillated by the eccentric body. In the eccentric oscillation type speed reducer, an input shaft bearing supporting the input shaft 26 is not arranged on one side in an axial direction with respect to the external gear 30, but arranged on the other side in the axial direction with respect to the external gear 30. The eccentric oscillation type speed reducer comprises a first regulation member 50A that regulates axial movement with respect to the input shaft 26. At least a portion of the first regulation member 50A overlaps the external gear 30 in the axial direction.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to an eccentric oscillating type reduction gear device. [Background technology]

[0002] Patent Document 1 discloses an actuator including a motor and an eccentric oscillating reduction gear. This eccentric oscillating reduction gear includes an input shaft, an eccentric body provided on the input shaft, an external gear oscillated by the eccentric body, and input shaft bearings disposed on both axial sides of the external gear and supporting the input shaft. The input shaft bearings are typically restricted from axial movement toward the opposite side of the external gear by movement restricting members such as snap rings provided on the carrier. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-148198 Summary of the Invention [Problem to be solved by the invention]

[0004] There are cases where a reduction in the weight of a reduction gear transmission is required. One possible solution is to eliminate the input shaft bearing. However, simply omitting the input shaft bearing would allow the input shaft to move toward the side where the input shaft bearing is not located when the reduction gear transmission is separated from the motor, potentially increasing the amount of axial movement. This could lead to unintended malfunctions, so an improvement is desirable.

[0005] An object of the present disclosure is to provide a technique that can reduce the weight of the reduction gear transmission while suppressing the amount of axial movement of the input shaft when the reduction gear transmission is separated from the motor. [Means for solving the problem]

[0006] The reduction gear disclosed herein is an eccentric oscillating type reduction gear including an input shaft, an eccentric body provided on the input shaft, and an external gear oscillated by the eccentric body, in which an input shaft bearing supporting the input shaft is not arranged on one axial side of the external gear, and a first restricting member is arranged on the other axial side of the external gear and restricts axial movement relative to the input shaft, and at least a portion of the first restricting member overlaps with the external gear in the axial direction. [Effects of the Invention]

[0007] According to the present disclosure, it is possible to reduce the weight of the reduction gear transmission while suppressing axial movement of the input shaft when the reduction gear transmission is separated from the motor. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 2 is a side cross-sectional view of the actuator of the first embodiment. [Figure 2] FIG. 2 is an enlarged view of the reduction gear transmission of the first embodiment. [Figure 3] FIG. 3 is an explanatory diagram relating to the effect of the reduction gear transmission of the first embodiment. [Figure 4] FIG. 6 is another explanatory diagram relating to the effect of the reduction gear transmission of the first embodiment. [Figure 5] FIG. 6 is an enlarged view of a reduction gear transmission according to a second embodiment. [Figure 6] FIG. 10 is an enlarged view of a reduction gear transmission according to a third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] The following describes the embodiments. Identical components are designated by the same reference numerals, and redundant explanations will be omitted. In each drawing, components are omitted, enlarged, or reduced as appropriate for the sake of convenience. The drawings should be viewed in accordance with the orientation of the reference numerals.

[0010] (First embodiment) Referring to Fig. 1, an actuator 10 includes a motor 12 and a reduction gear 14.

[0011] The motor 12 may be, for example, a permanent magnet motor, an induction motor, a reluctance motor, a coreless motor, or the like. The motor 12 includes a motor shaft 16, a stator 18 and a rotor 20 that generate a rotating magnetic field that rotates the motor shaft 16, and a motor casing 22 that houses the stator 18 and the rotor 20. The stator 18 is fixed to the motor casing 22, and the rotor 20 is fixed to the motor shaft 16. The motor casing 22 includes a cylindrical motor frame 22a and a pair of covers 22b that cover the stator 18 and the rotor 20 from both axial sides. Motor shaft bearings 24A and 24B that rotatably support the motor shaft 16 are incorporated into the pair of covers 22b. The motor shaft bearings 24A and 24B include a first motor shaft bearing 24A located on the input side (anti-load side) of the stator 18 and the rotor 20, and a second motor shaft bearing 24B located on the anti-input side (load side) of the stator 18 and the rotor 20.

[0012] The reduction gear 14 includes an input shaft 26 to which rotation of the motor shaft 16 is input, an eccentric body 28 provided on the input shaft 26, an external gear 30 oscillated by the eccentric body 28, an internal gear 32 meshing with the external gear 30, and an output member 34 that outputs output rotation transmitted from a gear mechanism formed by the external gear 30 and the internal gear 32 to a driven member. In addition, the reduction gear 14 includes an eccentric bearing 36 arranged between the eccentric body 28 and the external gear 30, carriers 38A and 38B arranged axially laterally relative to the external gear 30, a reduction gear casing 40 that houses the external gear 30 and the carriers 38A and 38B, and an inner pin 42 protruding from the carrier 38A. The driven member is, for example, a part of a driven machine such as a conveyor, a wheel, a machine tool, or a robot.

[0013] Hereinafter, the direction along the rotation center C26 of the input shaft 26 will be referred to as the axial direction X, and the radial and circumferential directions of a circle concentric with the rotation center C26 will simply be referred to as the radial and circumferential directions. The side of the axial direction X where the motor 12 is located will be referred to as the input side, and the side opposite the input side in the axial direction X will be referred to as the anti-input side. The side of the axial direction X where the external gear 30 is located will be referred to as the external gear side, and the side opposite the external gear 30 in the axial direction X will be referred to as the anti-external gear side. The state where the reduction gear 14 is separated from the motor 12 (see FIG. 3, etc.) will be referred to as the separated state, and the state where the reduction gear 14 is assembled to the motor 12 (see FIG. 1, etc.) will be referred to as the assembled state.

[0014] The reduction gear 14 of this embodiment is an eccentric oscillating type reduction gear, and is capable of transmitting output rotation to the output member 34 by oscillating one of the external gear 30 and the internal gear 32 (here, the external gear 30) by the input shaft 26 (crank shaft). Here, an example will be described in which the carrier 38A serves as the output member 34, but the reduction gear casing 40 may also serve as the output member 34. The reduction gear 14 of this embodiment is a center crank type in which the input shaft 26 is disposed concentrically with the center C32 of the internal gear 32.

[0015] The input shaft 26 is integrated with the motor shaft 16. Rotation is input to the input shaft 26 from the external motor shaft 16. The input shaft 26 is separate from the motor shaft 16. In this embodiment, an example is shown in which rotation is directly input to the input shaft 26 from the motor shaft 16, but rotation may be input via another member. When the motor 12 is in an assembled state with the reduction gear transmission 14 attached, the axial movement of the input shaft 26 is restricted by motor shaft bearings 24A and 24B of the motor 12. In this embodiment, axial movement of the input shaft 26 toward the input side is restricted when a movement restricting portion 16c provided on the motor shaft 16 integrated with the input shaft 26 abuts against the first motor shaft bearing 24A from the opposite input side. Axial movement of the input shaft 26 toward the opposite input side is restricted when a rotor 20 fixed to the motor shaft 16 integrated with the input shaft 26 abuts against the second motor shaft bearing 24B from the input side via a spacer 21. The movement restricting portion 16c of this embodiment is a protrusion that protrudes radially outward from the outer periphery of the motor shaft 16.

[0016] The input shaft 26 is a crankshaft equipped with at least one (three in this embodiment) eccentric body 28. In this embodiment, the eccentric body 28 is provided as part of the same member as the input shaft 26, but may be provided separately from the input shaft 26. The eccentric body 28 is eccentric with respect to the rotation center C26 of the input shaft 26 by an eccentricity amount e. When the number of eccentric bodies 28 is M (three in this embodiment), the eccentric phases of the multiple eccentric bodies 28 are shifted by 360° / M. The number of eccentric bodies 28 is not particularly limited and may be one, two, or four or more.

[0017] The external gears 30 are individually provided corresponding to the multiple eccentric bodies 28, and are supported by the corresponding eccentric bodies 28 via eccentric bearings 36 so as to be relatively rotatable. The external gears 30 have an axial hole 30a through which the input shaft 26 passes and in which the eccentric bearings 36 are disposed. The multiple external gears 30 are in contact with each other at opposing locations in the axial direction X. The axial movement of the multiple external gears 30 is restricted by gear restricting members that are disposed on both axial sides of the multiple external gears 30. The gear restricting members in this embodiment are outer rings 44a of main bearings 44, which will be described later. Specific examples of the gear restricting members are not particularly limited, and may also be carriers 38A, 38B, etc.

[0018] The internal gear 32 is integrated with the reduction gear casing 40. In this embodiment, the reduction gear casing 40 is configured by combining multiple casing members 40a, 40b. The casing members 40a, 40b include a first casing member 40a having the internal gear 32 provided on an inner periphery thereof, and a second casing member 40b that is provided closer to the motor 12 in the axial direction X than the first casing member 40a and is connected to the motor casing 22.

[0019] The eccentric bearing 36 includes a plurality of rolling elements 36a and a retainer 36b that maintains the relative positions of the plurality of rolling elements 36a. The rolling elements 36a in this embodiment are rollers, but specific examples thereof are not particularly limited. The eccentric bearing 36 in this embodiment does not include a dedicated outer ring, and the inner circumferential surface of the shaft hole 30a of the external gear 30 also serves as the outer ring. The eccentric bearing 36 in this embodiment does not include a dedicated inner ring, and the outer circumferential surface of the eccentric element 28 also serves as the inner ring. Alternatively, the eccentric bearing 36 may include dedicated outer and inner rings.

[0020] The carriers 38A, 38B include a first carrier 38A arranged on the anti-input side relative to the external gear 30, and a second carrier 38B arranged on the input side relative to the external gear 30. A main bearing 44 is arranged between the reduction gear casing 40 and the carriers 38A, 38B, connecting the reduction gear casing 40 and the carriers 38A, 38B so as to be rotatable relative to each other.

[0021] The inner pins 42 are provided at positions offset from the center C32 of the internal gear 32 and spaced apart around the center C32. The inner pins 42 axially pass through pin holes 30b formed in the external gear 30. In this embodiment, the inner pins 42 are configured as part of the same member as the carrier 38A, but may be configured separately from the carrier 38A. In this embodiment, the inner pins 42 connect the first carrier 38A and the second carrier 38B. The inner pins 42 contact the pin holes 30b of the external gear 30, and can synchronize the rotation component of the external gear 30 with the carriers 38A and 38B when the external gear 30 oscillates. Here, "synchronization with the rotation component" refers to maintaining the rotation component of the external gear 30, the rotation components of the carriers 38A and 38B, and the revolution component of the inner pins 42 at the same magnitude within a numerical range including zero. The inner pin 42 of this embodiment is in contact with the pin hole 30b of the external gear 30 via a roller 46 arranged on the outer periphery of the inner pin 42. Alternatively, the inner pin 42 may be in direct contact with the pin hole 30b of the external gear 30.

[0022] The operation of the actuator 10 (reduction gear 14) described above will now be described. The motor shaft 16 is rotated by a rotating magnetic field generated by the stator 18 and the rotor 20. The rotation of the motor shaft 16 is input to the input shaft 26. When the input shaft 26 rotates, the eccentric body 28 of the input shaft 26 causes the external gear 30 to oscillate so that the center of the external gear 30 rotates around the center of rotation C26 of the input shaft 26. When the external gear 30 oscillates, the meshing position between the external gear 30 and the internal gear 32 changes around the center of the internal gear 32. Accordingly, with each rotation of the input shaft 26, one of the external gear 30 and the internal gear 32 (here, the external gear 30) rotates by an amount corresponding to the difference in the number of teeth between the external gear 30 and the internal gear 32. This rotation component is transmitted as output rotation to the output member 34 (here, the first carrier 38A) via the inner pin 42. At this time, the output rotation, which is decelerated relative to the rotation of the input shaft 26, is transmitted to the output member .

[0023] Here, in the reduction gear 14 of this embodiment, an input shaft bearing that supports the input shaft 26 is not arranged on one side (here, the input side) in the axial direction X with respect to the external gear 30. Moreover, in the reduction gear 14 of this embodiment, an input shaft bearing that supports the input shaft 26 is not arranged on the other side (here, the non-input side) in the axial direction X with respect to the external gear 30. Here, the "input shaft bearing" refers to one that is arranged between the carriers 38A, 38B and the input shaft 26 and that directly supports the input shaft 26.

[0024] 2, the reduction gear 14 includes a first restricting member 50A disposed on the other side in the axial direction X (opposite the input side) of the external gear 30, a second restricting member 50B disposed on one side in the axial direction X (input side) of the external gear 30, and shaft fixing members 52A and 52B fixed to the input shaft 26 in the axial direction X.

[0025] The restricting members 50A, 50B are plate-shaped members disposed radially outward of the input shaft 26. In this embodiment, the restricting members 50A, 50B are circumferentially continuous annular members, but may be cutout annular members with a circumferentially cutout portion. The outer peripheral portions 50a of the restricting members 50A, 50B are positioned closer to the external gear than the inner peripheral portions 50b of the restricting members 50A, 50B. As will be described later, the axial movement of the restricting members 50A, 50B relative to the input shaft 26 is restricted.

[0026] The shaft fixing members 52A, 52B include a first shaft fixing member 52A arranged on the opposite side of the external gear from the first restricting member 50A, and a second shaft fixing member 52B arranged on the opposite side of the external gear from the second restricting member 50B. In this embodiment, the first shaft fixing member 52A and the second shaft fixing member 52B are each a retaining ring. The shaft fixing members 52A, 52B formed by a retaining ring are fitted into a groove 54 formed in the input shaft 26, thereby being fixed to the input shaft 26 in the axial direction X. The shaft fixing members 52A, 52B restrict axial movement of the restricting members 50A, 50B located between the external gear 30 and the shaft fixing members 52A, 52B. In this embodiment, the shaft fixing members 52A, 52B directly restrict the axial movement of the restricting members 50A, 50B, but may also restrict it via other members (for example, an input shaft bearing 70, a collar, etc., which will be described later).

[0027] The inner peripheral portions 50b of the restricting members 50A, 50B contact the shaft fixing members 52A, 52B located on the opposite side of the external gear relative to the restricting members 50A, 50B, thereby restricting axial movement toward the opposite side of the external gear relative to the input shaft 26. Furthermore, the inner peripheral portions 50b of the restricting members 50A, 50B contact a step 26a provided on the input shaft 26, thereby restricting axial movement toward the external gear. This restricts movement of the restricting members 50A, 50B to both sides of the input shaft 26 in the axial direction, and positions the restricting members 50A, 50B in the axial direction X relative to the input shaft 26. This holds true whether the reduction gear transmission 14 is in a separated state or an assembled state. The step 26a of the input shaft 26 is located on the external gear side relative to the restricting members 50A, 50B, and its outer diameter increases toward the external gear side.

[0028] At least a portion of the regulating members 50A, 50B overlaps in the axial direction X with the external gear 30 adjacent to the regulating members 50A, 50B in the axial direction X. As a result, as will be described later, when the reduction gear transmission 14 is in a separated state, the regulating members 50A, 50B come into contact with the external gear 30, thereby restricting axial movement of the regulating members 50A, 50B toward the external gear. In this embodiment, the entire circumferential direction of the regulating members 50A, 50B overlaps with the external gear 30 in the axial direction X. Alternatively, a portion of the circumferential direction of the regulating members 50A, 50B may overlap with the external gear 30 in the axial direction X. In this embodiment, this condition is satisfied by the outer peripheral portions 50a of each of the first regulating member 50A and the second regulating member 50B.

[0029] Assume the outer diameter R50 of the regulating members 50A and 50B, the inner diameter R30a of the shaft hole 30a of the external gear 30, and the eccentricity e of the eccentric body 28. The outer diameter R50 refers to the distance (radius) from the rotation center C26 of the input shaft 26 to the outer peripheral surfaces of the regulating members 50A and 50B. The inner diameter R30a refers to the distance (radius) from the center C30a of the shaft hole 30a to the inner peripheral surface of the shaft hole 30a. In this case, by making the outer diameter R50 of the regulating members 50A and 50B larger than the difference (R30a-e) between the inner diameter R30a of the shaft hole 30a and the eccentricity e of the eccentric body 28, it is possible to overlap at least a portion of the circumferential direction of the regulating members 50A and 50B with the external gear 30 in the axial direction X. Furthermore, by making the outer diameter R50 of the regulating members 50A and 50B larger than the sum (R30a+e) of the inner diameter R30a of the axial hole 30a and the eccentricity e of the eccentric body 28, the entire circumferential direction of the regulating members 50A and 50B can be overlapped axially with the external gear 30.

[0030] The multiple eccentric bearings 36 are in contact with each other at opposing locations in the axial direction X. Here, the opposing locations of the retainers 36b of the multiple eccentric bearings 36 are in contact. The first and second restricting members 50A and 50B restrict axial movement of the eccentric bearings 36 toward the opposite external gear side as viewed from the restricting members 50A and 50B by contact between the restricting members 50A and 50B and the eccentric bearings 36 adjacent to each other in the axial direction X. In this embodiment, the outer peripheral portions 50a of the restricting members 50A and 50B contact the retainers 36b of the eccentric bearings 36, thereby restricting the axial movement of the eccentric bearings 36. As a result, the axial movement of the multiple eccentric bearings 36 is restricted by the first and second restricting members 50A and 50B, and the multiple eccentric bearings 36 are positioned in the axial direction X with respect to the input shaft 26. This is true whether the reduction gear transmission 14 is in a separated state or an assembled state.

[0031] The effects of the reduction gear device 14 described above will now be described.

[0032] (A) In the reduction gear 14, an input shaft bearing is not disposed on one side (input side) in the axial direction X with respect to the external gear 30. Therefore, by omitting the input shaft bearing, it is possible to reduce the weight of the reduction gear 14. Furthermore, by omitting the input shaft bearing, it is possible to reduce friction loss, and it is possible to improve the transmission efficiency of the reduction gear 14.

[0033] Referring to Figure 3, let us assume that the first stop member 50A is not present, assuming that no input shaft bearing is disposed on one side of the external gear 30 in the axial direction X (the input side, the right side in Figure 3). In this case, when the reduction gear transmission 14 is in a separated state, the input shaft 26 is permitted to move significantly toward the side where the input shaft bearing is not present. This can cause unintended problems such as the input shaft 26 falling off or wear and tear on the rolling elements 36a of the eccentric bearing 36.

[0034] (A) Here, in the reduction gear transmission 14 of this embodiment, a first stop member 50A is disposed on the other side of the external gear 30 in the axial direction X (the anti-input side, the left side in FIG. 3 ), and the first stop member 50A overlaps with the external gear 30 in the axial direction X. As shown in FIG. 3 , consider a case in which the input shaft 26 attempts to move to one side (the right side in FIG. 3 ) where the input shaft bearing is not disposed. In this case, the first stop member 50A comes into contact with the external gear 30, thereby restricting axial movement toward the external gear. Furthermore, the axial movement of the input shaft 26 is restricted by the first stop member 50A, whose axial movement relative to the input shaft 26 is restricted. As a result, the external gear 30 and the first stop member 50A can restrict axial movement of the input shaft 26 toward one side. Therefore, even if an input shaft bearing is not arranged on one side (input side) of the external gear 30 in the axial direction X, the amount of axial movement of the input shaft 26 when the reduction gear 14 is in a separated state can be suppressed compared to when the first regulating member 50A is not present.

[0035] (B) The first restricting member 50A restricts the axial movement of the eccentric bearing 36. Therefore, when the reduction gear 14 is in a separated state, the first restricting member 50A can prevent components (such as the rolling elements 36a) of the eccentric bearing 36 from falling off. The same effect can be obtained with the second restricting member 50B.

[0036] (C) The reduction gear 14 is fixed to the input shaft 26 in the axial direction X and includes a first shaft fixing member 52A that restricts axial movement of the first restricting member 50A. Therefore, when the reduction gear 14 is in a separated state and the input shaft 26 attempts to move to one side (input side) in the axial direction X, the movement of the input shaft 26 can be restricted by the external gear 30, the first restricting member 50A, and the first shaft fixing member 52A.

[0037] (D) The first shaft fixing member 52A is a retaining ring. Therefore, the axial movement of the first restricting member 50A relative to the input shaft 26 can be restricted with a simple configuration.

[0038] (E) In the reduction gear 14, an input shaft bearing is not disposed on the other side (non-input side) in the axial direction X with respect to the external gear 30. Therefore, the omission of the input shaft bearing can further reduce the weight of the reduction gear 14. In addition, the omission of the input shaft bearing can further improve the transmission efficiency of the reduction gear 14.

[0039] See FIG. 4. It is assumed that, as in this embodiment, an input shaft bearing is not disposed on the other side in the axial direction X (the anti-input side, left side in FIG. 4) of the external gear 30, and that the second restricting member 50B is not present. In this case, when the reduction gear 14 is in a separated state, the input shaft 26 is permitted to move significantly toward the side where the input shaft bearing is not present. Furthermore, even when the input shaft bearing 70 is disposed on the other side in the axial direction X (the anti-input side) of the external gear 30, as in a second embodiment described below, the same holds true when the carrier 38A is not provided with a movement restricting portion that restricts axial movement of the input shaft bearing 70 toward the opposite external gear side, and when the second restricting member 50B is not present.

[0040] (F) Here, the reduction gear 14 has a second restricting member 50B disposed on one side of the external gear 30 in the axial direction X (the input side, the right side in FIG. 4 ), and the second restricting member 50B overlaps with the external gear 30 in the axial direction X. As shown in FIG. 4 , consider a case in which the input shaft 26 attempts to move to the other side of the axial direction X (the non-input side, the left side in FIG. 4 ). In this case, the second restricting member 50B comes into contact with the external gear 30, thereby restricting axial movement toward the external gear. Furthermore, the input shaft 26 is restricted from axial movement toward the other side by the second restricting member 50B, whose axial movement relative to the input shaft 26 is restricted. As a result, the external gear 30 and the second restricting member 50B can restrict axial movement of the input shaft 26 toward the other side. Therefore, as described above, the axial movement of the input shaft 26 when the reduction gear 14 is in the disengaged state can be suppressed more effectively than when the second restricting member 50B is not provided. In turn, coupled with the effect of the first restricting member 50A, the amount of axial movement of the input shaft 26 can be significantly restricted.

[0041] (G) The reduction gear 14 includes a second shaft fixing member 52B that is fixed to the input shaft 26 in the axial direction X and that restricts axial movement of the second restricting member 50B. Therefore, when the input shaft 26 attempts to move to the other side (non-input side) in the axial direction X, the movement of the input shaft 26 can be restricted by the external gear 30, the second restricting member 50B, and the second shaft fixing member 52B.

[0042] (H) The second shaft fixing member 52B is a retaining ring. Therefore, the axial movement of the second restricting member 50B relative to the input shaft 26 can be restricted with a simple configuration.

[0043] Next, other features of the reduction gear 14 will be described. Refer to FIG. 2. The input shaft 26 of this embodiment has a hollow portion 26b, and the motor shaft 16 is inserted into the hollow portion 26b. The input shaft 26 is connected to the motor shaft 16 using a connection structure 60 so as to be rotatable together with the motor shaft 16. The connection structure 60 of this embodiment includes a key groove 60a formed on the inner circumferential surface of the hollow portion 26b of the input shaft 26 and the outer circumferential surface of the motor shaft 16, and a key 60b fitted into the key groove 60a. There are no particular limitations on the specific example of the connection structure 60. The connection structure 60 may also be, for example, a male spline and a female spline provided on the input shaft 26 and the motor shaft 16, respectively, that fit together.

[0044] As will be described below, the input shaft 26 is fastened to the motor shaft 16 in the axial direction X by a bolt 62. The bolt 62 applies an axial force F1 to the input shaft 26, pressing the input shaft 26 against the motor shaft 16. In this embodiment, the bolt 62 applies the axial force F1 to the input shaft 26 via a seat member 64 on which the head of the bolt 62 sits. The seat member 64 is a flanged bushing. The seat member 64 includes a cylindrical portion 64a that is inserted into the hollow portion 26b of the input shaft 26 from the non-input end, and a flange portion 64b that protrudes radially outward from the non-input end of the cylindrical portion 64a. The cylindrical portion 64a includes a counterbore hole 64c that receives the head 62a of the bolt 62, and an insertion hole 64d that has an inner diameter smaller than the counterbore hole 64c and through which the shank 62b of the bolt 62 is inserted. The head 62a of the bolt 62 is seated on the bottom surface of the countersunk hole 64c. The shank 62b of the bolt 62 is threaded into the female threaded hole 16a formed in the non-input end of the motor shaft 16, thereby transmitting the axial force F1 of the bolt 62 to the input shaft 26. In this embodiment, the axial force F1 of the bolt 62 is transmitted to the input shaft 26 via the flange 64b of the seat member 64. The axial force F1 transmitted to the input shaft 26 is received by the step 16b formed on the motor shaft 16. As a result, the axial force F1 of the bolt 62 presses the input shaft 26 against the step 16b of the motor shaft 16, thereby fastening the input shaft 26 to the motor shaft 16 in the axial direction X. At this time, frictional resistance corresponding to the axial force F1 acts between the input shaft 26 and the motor shaft 16, and this frictional resistance restricts the relative rotation of the input shaft 26 with respect to the motor shaft 16.

[0045] (I) In this manner, the input shaft 26 is axially fastened to the motor shaft 16 by the bolts 62. Therefore, when an overturning moment acts on the input shaft 26, the overturning moment can be transmitted from the input shaft 26 to the motor shaft 16 via the bolts 62. Consequently, the motor shaft 16, supported by the motor shaft bearing 24, can effectively resist the overturning moment acting on the input shaft 26. This has the advantage of being able to effectively resist the overturning moment, particularly even when an input shaft bearing for resisting the overturning moment is omitted. The overturning moment here refers to a moment that bends the non-input end of the input shaft 26. Furthermore, to resist the overturning moment acting on the input shaft 26, it is not necessary to insert the motor shaft 16 deeply into the hollow portion 26b of the input shaft 26. Therefore, it is possible to resist the overturning moment acting on the input shaft 26 while ensuring ease of assembly when connecting the input shaft 26 to the motor shaft 16.

[0046] In relation to this effect, the bolt 62 may apply the axial force F1 directly to the input shaft 26, instead of using the seat member 64. In this case, a solid portion may be provided in the non-input side portion of the input shaft 26 where the hollow portion 26b was located, and the bolt 62 may be seated in the solid portion of the input shaft 26. In this case, there is an advantage in that the seat member 64 can be omitted, thereby reducing the number of parts.

[0047] Furthermore, when the seat member 64 is inserted into the hollow portion 26b provided in the input shaft 26 as described above, the hollow portion 26b is provided to penetrate the input shaft 26 in the axial direction X. In this case, there is an advantage that a large change in the wall thickness is unlikely to occur over the entire range of the input shaft 26 in the axial direction X, making it easier to provide a uniform quench-hardened layer over the entire range.

[0048] Second Embodiment: See FIG. 5. The reduction gear 14 of this embodiment differs from the first embodiment in the presence or absence of an input shaft bearing 70, which will be described below. More specifically, in the first embodiment, an example was described in which input shaft bearings were not arranged on either axial side of the external gear 30. The reduction gear 14 of this embodiment includes an input shaft bearing 70 that is arranged on the opposite side of the external gear from the first stop member 50A and supports the input shaft 26. The input shaft bearing 70 is arranged between the first shaft fixing member 52A and the first stop member 50A. Specific examples of the input shaft bearing 70 are not particularly limited, but include, for example, a ball bearing and a roller bearing. The input shaft bearing 70 includes rolling elements 70a, an outer ring 70b arranged on the first carrier 38A, and an inner ring 70c arranged on the input shaft 26.

[0049] The input shaft bearing 70 is disposed in a shaft insertion hole 38a formed in the first carrier 38A, through which the input shaft 26 is inserted. The shaft insertion hole 38a is not provided with a movement restricting portion such as a step or a retaining ring that restricts axial movement of the input shaft bearing 70 toward the opposite external gear side. This simplifies the shape of the shaft insertion hole 38a, and reduces the cost required for processing (such as cutting) to obtain the shaft insertion hole 38a.

[0050] The input shaft bearing 70 is restricted from axial movement toward the opposite external gear side relative to the input shaft 26. In this embodiment, this is achieved by the first shaft fixing member 52A, which is disposed on the opposite external gear side relative to the input shaft bearing 70. The first shaft fixing member 52A of this embodiment restricts the axial movement of the first restricting member 50A toward the opposite external gear side via the input shaft bearing 70. The axial movement of the first restricting member 50A toward the opposite external gear side is restricted by contact between the input shaft bearing 70 and its inner peripheral portion 50b. As described above, the axial movement of the first restricting member 50A toward the external gear side is restricted by contact with the step portion 26a of the input shaft 26. As a result, as described above, the first restricting member 50A is restricted from axial movement in both directions relative to the input shaft 26 and is positioned in the axial direction X relative to the input shaft 26. This is true whether the reduction gear transmission 14 is in a separated state or an assembled state.

[0051] As a result, when the input shaft 26 attempts to move to one side (input side) in the axial direction X where the input shaft bearing 70 is not arranged, the movement of the input shaft 26 can be restricted by the external gear 30, the first restricting member 50A, and the input shaft bearing 70.

[0052] In addition, the reduction gear 14 of this embodiment includes the components described above in (A) to (D) and (F) to (I), and can obtain the effects corresponding to those descriptions.

[0053] (Third embodiment) Please refer to Fig. 6. The reduction gear 14 of this embodiment differs from the first embodiment in terms of a reduction gear casing 40 and carriers 38A and 38B, which will be explained next.

[0054] The casing members 40a, 40b, 40c of the reduction gear casing 40 of this embodiment include a third casing member 40c that is located on the opposite side of the motor 12 in the axial direction X from the first casing member 40a and that houses the first carrier 38A.

[0055] In the above-described embodiment, the inner pin 42 is supported by the first carrier 38A and the second carrier 38B from both sides in the axial direction X. In this embodiment, the second carrier 38B is not disposed on the axially opposite side of the first carrier 38A across the external gear 30. In other words, the reduction gear 14 of this embodiment includes only the first carrier 38A and does not include the second carrier 38B. With this structure, the inner pin 42 of this embodiment is supported by a single carrier 38A from one axial side. As a result, by omitting the carrier 38B of the reduction gear 14, the axial dimension of the reduction gear 14 can be reduced.

[0056] In addition, the reduction gear 14 of this embodiment includes the components described above in (A) to (I), and can obtain the effects corresponding to those descriptions.

[0057] Next, we will explain modified forms of each of the components described so far. Hereinafter, when components with reference numerals ending in "A" or "B" (such as the restricting member 50 and the shaft fixing member 52) are referred to collectively, the letters will be omitted.

[0058] There is no particular limitation on the type of eccentric oscillating reduction gear 14. As an example, the eccentric oscillating reduction gear 14 may be a distribution type in which multiple input shafts 26 are arranged at positions offset from the center C32 of the internal gear 32.

[0059] In the embodiment, an example has been described in which "one side in the axial direction X" is the input side and "the other side in the axial direction X" is the non-input side. Alternatively, "one side in the axial direction X" may be the non-input side and "the other side in the axial direction X" may be the input side. For example, in the first to third embodiments, an example has been described in which an input shaft bearing is not arranged on the input side, which is one side in the axial direction of the reduction gear 14, and the first stop member 30A is arranged on the non-input side, which is the other side in the axial direction of the external gear 30. Alternatively, an input shaft bearing may not be arranged on the non-input side, which is one side in the axial direction of the reduction gear 14, and the first stop member 30A may be arranged on the input side, which is the other side in the axial direction of the external gear 30. In this case, as in the second embodiment, an input shaft bearing 70 may be arranged on the input side, which is the other side in the axial direction of the external gear 30, or as in the first embodiment, the input shaft bearing 70 may be omitted.

[0060] In the above description, the first restricting member 50A is restricted from moving in the axial direction relative to the input shaft 26 by the first shaft fixing member 52A. However, the present invention is not limited to this. The first restricting member 50A itself may be fixed to the input shaft 26 in the axial direction X, thereby restricting the axial movement relative to the input shaft 26. This may be achieved, for example, by fitting a portion of the first restricting member 50A into a groove formed in the input shaft 26.

[0061] In the above description, the second restricting member 50B is restricted from moving in the axial direction relative to the input shaft 26 by the second shaft fixing member 52B. However, the present invention is not limited to this. The second restricting member 50B itself may be fixed to the input shaft 26 in the axial direction X, thereby restricting the axial movement of the input shaft 26. This is assumed to be achieved, for example, by fitting a portion of the second restricting member 50B into a groove formed in the input shaft 26. Furthermore, the second restricting member 50B may be disposed at a position that does not overlap with the external gear 30 in the axial direction X, and may only have the function of restricting the axial movement of the eccentric bearing 36.

[0062] The first and second restricting members 50A and 50B may not restrict the axial movement of the eccentric bearing 36. This is intended, for example, to assume that a bearing restricting member for restricting the axial movement of the eccentric bearing 36 is provided separately from the restricting members 50A and 50B.

[0063] Specific examples of the first shaft fixing member 52A and the second shaft fixing member 52B are not limited to snap rings. The first shaft fixing member 52A and the second shaft fixing member 52B may be, for example, a collar, a nut, or the like. This collar may be fixed to the input shaft 26 in the axial direction X by press-fitting. This nut may be fixed to the input shaft 26 in the axial direction by screwing it onto a male thread provided on the input shaft 26. Furthermore, the first shaft fixing member 52A may be constituted by an input shaft bearing 70 fixed to the input shaft 26 by interference fit or the like.

[0064] The input shaft 26 does not have to be fastened to the motor shaft 16 in the axial direction X by the bolts 62 .

[0065] The above-described embodiments and variations are merely examples. The abstract technical concepts should not be interpreted as being limited to the contents of the embodiments and variations. Many design changes are possible in the contents of the embodiments and variations, such as changes, additions, and deletions of components. In the above-described embodiments, the contents that allow such design changes are emphasized by adding the notation "embodiment." However, design changes are also permitted even in contents without such notation. Hatching on cross sections in the drawings does not limit the material of the hatched objects. The structures / numerical values ​​referred to in the embodiments and variations naturally include those that can be considered identical when taking into account manufacturing errors, etc.

[0066] In the embodiments, a component that is made up of a single member may be made up of multiple members. Similarly, in the embodiments, a component that is made up of multiple members may be made up of a single member. [Explanation of symbols]

[0067] 12...motor, 14...reduction gear, 16...motor shaft, 26...input shaft, 28...eccentric body, 30...external gear, 36...eccentric bearing, 38A, 38B...carrier, 42...inner pin, 50A...first restricting member, 50B...second restricting member, 52A...first shaft fixing member, 52B...second shaft fixing member, 62...bolt, 70...input shaft bearing.

Claims

1. An eccentric oscillating reduction gear device comprising: an input shaft; an eccentric body provided on the input shaft; and an external gear oscillated by the eccentric body, an input shaft bearing for supporting the input shaft is not disposed on one axial side of the external gear, a first restricting member that is disposed on the other axial side of the external gear and restricts axial movement relative to the input shaft, An eccentric oscillating reduction gear device in which at least a portion of the first restricting member overlaps with the external gear in the axial direction.

2. an eccentric bearing disposed between the external gear and the eccentric body, The eccentric oscillating reduction gear device according to claim 1 , wherein the first restricting member restricts axial movement of the eccentric bearing.

3. 3. The eccentric oscillating reduction gear device according to claim 1, further comprising a first shaft fixing member that is arranged on the opposite side of the external gear from the first restricting member, is fixed in the axial direction to the input shaft, and restricts axial movement of the first restricting member.

4. 4. The eccentric oscillating type reduction gear device according to claim 3, wherein the first shaft fixing member is a snap ring.

5. an input shaft bearing that is disposed on an inverted external gear side relative to the first restricting member and restricts axial movement of the input shaft toward the inverted external gear side; 5. The eccentric oscillating reduction gear device according to claim 1, wherein the axial movement of the first restricting member is restricted by the input shaft bearing.

6. an input shaft bearing for supporting the input shaft is not disposed on the other side of the external gear, a second restricting member that is disposed on the one side of the external gear and restricts axial movement with respect to the input shaft, The eccentric oscillating reduction gear device according to claim 1 , wherein at least a portion of the second restricting member overlaps with the external gear in the axial direction.

7. 7. The eccentric oscillating reduction gear device according to claim 6, further comprising a second shaft fixing member that is arranged on the opposite side of the external gear from the second restricting member, is fixed in the axial direction to the input shaft, and restricts axial movement of the second restricting member.

8. 8. The eccentric oscillating type reduction gear device according to claim 7, wherein the second shaft fixing member is a snap ring.

9. a carrier disposed axially laterally with respect to the external gear; an inner pin that penetrates the external gear and synchronizes the rotation component of the external gear with the carrier, 9. The eccentric oscillating reduction gear device according to claim 1, wherein no other carrier is disposed on the axially opposite side of the carrier across the external gear.

10. 10. The eccentric oscillating reduction gear device according to claim 1, wherein the input shaft is separate from an external motor shaft that inputs rotation to the input shaft, and is axially fastened to the motor shaft by a bolt.

Images