Speed reducer and motor with speed reducer

Abstract

To provide a speed reducer which can reduce an input of an unnecessary deformation load to a crankshaft, and to provide a motor with the speed reducer.SOLUTION: A speed reducer includes a casing, a crankshaft 10, and a speed reducer body. The crank shaft 10 has: a rotation support part which is rotatably supported by the casing; and an eccentric part 20 which is eccentric with respect to the rotation support part and receives rotational force from the outside to rotate. The speed reducer body has an engagement part engaged with an outer circumferential surface of the eccentric part 20, decelerates rocking rotation of the eccentric part received by the engagement part, and outputs the decelerated rotation to the outside. The crankshaft 10 is provided with a flange part 12 protruding to the radial outer side from an eccentric part side end of the rotation support part and abutting with an end surface in an axial direction of the engagement part. The flange part 12 is formed such that a center in a direction orthogonal to the axial direction coincides with a center of the eccentric part in the direction orthogonal to the axial direction.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a reducer and a motor with a reducer. [Background technology]

[0002] Conventionally, motors with speed reducers have been known that reduce the rotation of a motor using a speed reducer to obtain high rotational torque. There are various mechanisms for the speed reducers used in such motors with speed reducers, and one known mechanism converts the rotation of the motor into oscillating rotation of a crankshaft and then slows down the oscillating rotation using a planetary gear mechanism or the like (see, for example, Patent Document 1).

[0003] The reducer disclosed in Patent Document 1 includes a casing, a crankshaft rotatably supported by the casing, and a reducer body that reduces the oscillating rotation of an eccentric portion of the crankshaft. The crankshaft has a rotation support portion rotatably supported by the casing and an eccentric portion eccentric with respect to the rotation support portion. The crankshaft rotates in response to the rotation of an output shaft of a motor. The reducer body includes an eccentric portion bearing fitted to the outer peripheral surface of the eccentric portion of the crankshaft, and an oscillating gear rotatably supported by the eccentric portion via the eccentric portion bearing and having internal and external teeth. The reducer body also includes a fixed gear fixed to the casing and having internal teeth that mesh with the external teeth of the oscillating gear, and an output gear rotatably held by the casing and having external teeth that mesh with the internal teeth of the oscillating gear. The internal teeth of the fixed gear and the external teeth of the output gear are formed concentrically with the central axis of the crankshaft.

[0004] In this reducer, when the crankshaft rotates in response to the rotation of the motor's output shaft, the eccentric portion of the crankshaft oscillates and rotates the oscillating gear via the eccentric portion bearing. At this time, the oscillating gear rotates on its axis while its external teeth mesh with the internal teeth of the fixed gear, and this rotation component is transmitted to the output gear through the meshing portion between the internal teeth of the oscillating gear and the external teeth of the output gear. As a result, the output gear outputs rotation reduced to a predetermined reduction ratio to an external device.

[0005] The crankshaft of this reducer is also provided with a flange that protrudes radially outward from the end of the rotation support portion on the eccentric portion side. This flange is formed in an annular shape concentric with the rotation support portion. The end face of the flange facing the eccentric portion abuts against the end face of the eccentric portion bearing (engagement portion) fitted to the eccentric portion. The flange absorbs the thrust reaction force (reaction force in the tilting direction) acting on the eccentric portion bearing when torque is transmitted to an external device. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 6838849 Summary of the Invention [Problem to be solved by the invention]

[0007] The reducer described in Patent Document 1 is designed to receive the thrust reaction force acting on the eccentric bearing by the annular flange of the crankshaft. However, the eccentric bearing is supported on the outer peripheral surface of the eccentric portion of the crankshaft, and its center in the direction perpendicular to the axial direction is concentric with the eccentric portion. Therefore, the axis of the flange of the crankshaft is offset radially from the axis of the eccentric bearing.

[0008] As a result, the end face of the eccentric bearing abuts against the end face of the opposing flange in a non-concentric state (radially offset state). As a result, the thrust load (load in the tilting direction) acting on the flange from the eccentric bearing acts unevenly around the center of the flange. Therefore, in the reducer described in Patent Document 1, when the thrust reaction force acting on the eccentric bearing increases, a large deformation load is likely to act on the entire flange and crankshaft.

[0009] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a reducer and a motor with a reducer that can suppress the input of unnecessary deformation load to the crankshaft. [Means for solving the problem]

[0010] In order to solve the above problems, the reducer and the motor with the reducer according to the present invention employ the following configurations. That is, a first aspect of the reducer of the present invention comprises a casing, a crankshaft having a rotational support part rotatably supported by the casing and an eccentric part eccentric with respect to the rotational support part, and which rotates when it receives a rotational force from the outside, and a reducer main body having an engagement part that engages with the outer peripheral surface of the eccentric part, and which decelerates the oscillating rotation of the eccentric part received by the engagement part and outputs it to the outside, wherein the crankshaft is provided with a flange part that protrudes radially outward from the end of the rotational support part on the eccentric part side and abuts against the axial end face of the engagement part, and the flange part is formed so that its center in a direction perpendicular to the axial direction coincides with the center of the eccentric part in a direction perpendicular to the axial direction.

[0011] In the reducer of the first embodiment described above, the center of the flange portion in a direction perpendicular to the axial direction of the crankshaft and the center of the eccentric portion in a direction perpendicular to the axial direction of the crankshaft are aligned with each other. Therefore, the engaging portion of the reducer body engaged with the outer peripheral surface of the eccentric portion abuts concentrically against the flange portion. Therefore, the thrust load acting on the flange portion of the crankshaft from the engaging portion of the reducer body is uniform over the circumferential area, making it difficult for a biased deformation load to act on the flange portion.

[0012] A second aspect of the present invention provides a reducer according to the first aspect, wherein the flange portion is formed in an annular shape such that the distance of the outer circumferential surface from the eccentric portion is uniform in the circumferential direction.

[0013] In this case, the engaging portion of the reducer body engaged with the outer peripheral surface of the eccentric portion is more likely to abut more evenly in the circumferential direction against the end face of the flange portion. Also, in this configuration, since the flange portion has an annular shape, the flange portion can be made smaller and lighter.

[0014] A third aspect of the reducer of the present invention is a reducer of the first or second aspect, wherein the reducer body comprises a bearing which is the engagement portion, a oscillating gear which is rotatably supported on the eccentric portion of the crankshaft via the bearing and has first internal teeth and first external teeth, a fixed gear which is fixed to the casing and meshes with the first external teeth of the oscillating gear and has second internal teeth concentric with the central axis of the rotation support portion of the crankshaft, and an output gear which meshes with the first internal teeth of the oscillating gear and has second external teeth concentric with the central axis.

[0015] In this case, when the crankshaft receives a rotational force from an external source and rotates, causing the eccentric portion of the crankshaft to oscillate and rotate, the oscillating gear oscillates via a bearing engaged with the outer peripheral surface of the eccentric portion. At this time, the oscillating gear rotates on its axis with its first external teeth meshing with the second internal teeth of the fixed gear. At this time, the output rotor rotates in response to the rotation of the oscillating gear, since its second external teeth are meshed with the second internal teeth of the oscillating gear. The rotation of the output rotor is output to an external device. When transmitting power to an external device, the reducer of this configuration receives a reaction force from the external device through the output rotor. This reaction force is input to the crankshaft through the output rotor, oscillating rotor, and bearing. At this time, part of the reaction force acts on the flange of the crankshaft as a thrust load (load in the tilting direction). Because the flange is shaped to coincide with the radial center of the bearing, the thrust load acting on the flange from the bearing is uniform over the circumferential area centered on the center of the flange.

[0016] Furthermore, a motor with a reducer according to a first aspect of the present invention is characterized by comprising a reducer according to any one of the first to third aspects and a motor section connected to the crankshaft of the reducer. [Effects of the Invention]

[0017] In the reducer and motor with reducer according to the present invention, the engagement portion of the reducer body engaged with the outer peripheral surface of the eccentric portion of the crankshaft abuts concentrically against the flange portion, so that a thrust load acts evenly in the circumferential direction from the engagement portion of the reducer body to the flange portion of the crankshaft, making it difficult for a biased deformation load to act on the flange portion. Therefore, when the reducer or the motor with a reducer according to the present invention is used, it is possible to suppress the input of unnecessary deformation load to the crankshaft. [Brief explanation of the drawings]

[0018] [Figure 1] FIG. 1 is a perspective view of a motor with a reducer according to an embodiment. [Figure 2] 2 is a cross-sectional view of the motor with a reducer according to the embodiment taken along line II-II in FIG. 1. [Figure 3] 3 is a cross-sectional view of the motor with a reducer according to the embodiment taken along line III-III in FIG. 2. [Figure 4] FIG. [Figure 5] 4 showing the crankshaft of the embodiment. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0019] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0020] Fig. 1 is a perspective view of a motor with a reducer 1 according to this embodiment, and Fig. 2 is a cross-sectional view taken along line II-II in Fig. 1. A motor with a reducer 1 according to this embodiment is used, for example, in a wheel drive unit of a vehicle such as a motorcycle. As shown in Figures 1 and 2, the motor with a reducer 1 includes a flat motor unit 2 configured as a so-called DC brushless motor, a control unit 3 that controls the drive of the motor unit 2, a reducer 4 that reduces the rotational power of the motor unit 2 and transmits that power to an external device, and a casing 5 that houses these components. The casing 5 includes a casing main body 5A having a short axis and a control unit cover 5B that closes one axial end (the right end in Figure 2) of the casing main body 5A, and an annular block 5C that is attached to the other axial end (the left end in Figure 2) of the casing main body 5A. The motor axis (rotation axis) of the motor unit 2 coincides with the central axis L of a crankshaft 10 (described later) of the reducer 4. In the following explanation, the direction along the motor axis (central axis L) may be simply referred to as the axial direction, the direction around the motor axis may be simply referred to as the circumferential direction, and the direction perpendicular to the motor axis and the circumferential direction may be simply referred to as the radial direction.

[0021] The motor 1 with a reducer is arranged in a casing 5 with a control unit 3, a motor unit 2, and a reducer 4 arranged in this order from one end to the other end in the axial direction. A partition wall 6 is integrally formed with the casing main body 5A, projecting radially inward from approximately the center position in the axial direction. Inside the casing main body 5A, the side of the partition wall 6 facing the control unit 3 serves as a motor accommodating section, and the side of the partition wall 6 opposite the control unit 3 serves as a reducer accommodating section. Furthermore, a substantially cylindrical bearing housing 7 is integrally formed with the partition wall 6 on the radially inner side. The bearing housing 7 holds a bearing 8 (ball bearing) for rotatably supporting one end of a crankshaft 10 (described later) of the reducer 4.

[0022] The casing body 5A has a connecting flange 40 that projects radially outward from the outer periphery at one axial end. A control unit cover 5B that covers the outside of the control unit 3 is connected to this connecting flange 40. The casing 5 is designed so that the casing body 5A can be fixed to a wheel support part of a vehicle or the like. The outer periphery of the casing body 5A tapers in a stepped manner from one axial end to the other axial end. An annular block 5C is attached to the end of the casing body 5A at the other axial end where the diameter is narrowest.

[0023] <Motor section 2> The motor section 2 is housed in a motor housing section within the casing body 5A. The motor section 2 includes a stator 30 in the form of a disk with holes, and a rotor 31 arranged radially inside the stator 30 so as to be rotatable. The stator 30 has a stator core 32 formed by laminating multiple electromagnetic steel sheets or by pressure molding soft magnetic powder. The outer peripheral edge of the stator core 32 is fastened to one axial end face of the casing body 5A by multiple bolts 29.

[0024] Additionally, a plurality of teeth (reference numerals omitted) projecting radially inward are formed in a circumferential arrangement on the inner periphery of the stator core 32. A coil 33 is wound around each of these teeth. Three-phase alternating current is applied to the coils 33 wound around each tooth from a power supply circuit (not shown). This causes the stator 30 to generate a rotating magnetic field.

[0025] The rotor 31 includes an annular rotor core 34 whose inner periphery is fitted and fixed to one axial end of the crankshaft 10 of the reducer 4, and a ring magnet 35 (permanent magnet) fixed to the outer periphery of the rotor core 34. The inner periphery of the rotor core 34 is disposed adjacent to one axial end of the bearing 8 held in the bearing housing 7. The ring magnet 35 is magnetized so that different magnetic poles (north and south poles) are arranged alternately along the circumferential direction on its outer surface. The rotor 31 rotates due to the attractive and repulsive forces acting between the rotating magnetic field generated on the stator 30 side and the ring magnet 35. The permanent magnet arranged on the outer periphery of the rotor core 34 is not limited to the ring magnet 35, but may be a plurality of magnet pieces divided in the circumferential direction.

[0026] <Control unit> The control unit 3 includes a cylindrical control unit cover 5B with a bottom, and a control board 50 fixed to one axial end face of the casing body 5A inside the control unit cover 5B. The control board 50 is equipped with a control circuit for controlling the motor unit 2, a sensor for detecting the rotation of the rotor 31, and the like. Also connected to the control board 50 are a power harness 51 (see FIG. 1) connected to an external battery or the like, and a signal harness 52 (see FIG. 1) connected to an external control device.

[0027] <Reducer> Fig. 3 is a cross-sectional view of the speed reducer-equipped motor 1 taken along line III-III in Fig. 2. Fig. 4 is a side view of the crankshaft 10, and Fig. 5 is a view of the crankshaft 10 taken along arrow IV in Fig. 4. The reducer 4 includes a casing 5 (casing main body 5A), a crankshaft 10 that rotates upon receiving rotational force from the motor section 2, and a reducer main body 11 that reduces the rotation of the eccentric section 20 of the crankshaft 10 and outputs the reduced rotation to the outside (wheels of the vehicle). The reducer 4 of this embodiment is configured as a hypocycloid reduction mechanism. The reduction mechanism of the reducer 4 is not limited to a hypocycloid reduction mechanism, but may be any other mechanism that can reduce the speed of rotation of the eccentric portion 20 of the crankshaft 10 and output it to the outside.

[0028] The crankshaft 10 includes a pair of rotation support portions 22a, 22b rotatably supported on the casing 5 via bearings 8, 21, and an eccentric portion 20 that is eccentric with respect to the central axis L (rotation axis) of the rotation support portions 22a, 22b. The rotation support portions 22a, 22b are both formed in a cylindrical shape and are formed coaxially so that their central axes L coincide with each other. The rotation support portions 22a, 22b are respectively disposed on one end side and the other end side in the axial direction of the crankshaft 10. The eccentric portion 20 is formed in a cylindrical shape, and both axial ends are connected to the rotation support portions 22a, 22b. The outer peripheral surface of the eccentric portion 20 is a cylindrical surface centered on a central axis O that is radially spaced from the central axis L of the rotation support portions 22a, 22b. When the rotation support parts 22a and 22b receive a rotational force from the motor part 2 and rotate, the eccentric part 20 oscillates and rotates around the central axis L at a constant radius.

[0029] A pair of bearings 24 (eccentric bearings made of ball bearings) are arranged side by side in the axial direction on the outer circumferential surface of the eccentric portion 20. These bearings 24 rotatably support the inner circumferential portion of an oscillating gear 25 (described later) of the reducer main body 11. In this embodiment, these bearings 24 form engaging portions that engage with the outer circumferential surface of the eccentric portion 20. Each bearing 24 has an inner ring 24i that is fitted with the outer circumferential surface of the eccentric portion 20 and an outer ring 24o that is fitted with the inner circumferential surface of the oscillating gear 25.

[0030] Rotation support portion 22a, which is arranged at one axial end side (right side in FIGS. 2 and 3) of crankshaft 10, is rotatably supported by partition wall 6 of casing main body 5A via bearing 8. Rotation support portion 22b, which is arranged at the other axial end side (left side in FIGS. 2 and 3) of crankshaft 10, is rotatably supported by an output gear 27 (described later) of reducer 4 via bearing 21. Output gear 27 is rotatably supported by annular block 5C of casing 5 via another bearing 26. Therefore, rotation support portion 22b at the other axial end side of crankshaft 10 is rotatably supported by annular block 5C (casing 5).

[0031] 2, 4, and 5, a flange portion 12 that protrudes radially outward from the outer circumferential surface of the rotation support portion 22a is integrally formed on the end portion of the rotation support portion 22a on the motor portion 2 side that is on the eccentric portion 20 side. The flange portion 12 has a circular outer surface shape, but it is not a circular shape that is concentric with the rotation support portion 22a, but rather a circular shape that is concentric with the eccentric portion 20 that is adjacent to it in the axial direction. Therefore, the flange portion 12 is formed so that the center in the direction perpendicular to the axial direction coincides with the center of the eccentric portion 20 in the direction perpendicular to the axial direction (a point that passes through the central axis O of the eccentric portion 20).

[0032] Both axial end faces 12f, 12s of the flange portion 12 are formed by flat surfaces perpendicular to the axial direction. One end face 12f of the flange portion 12 rises radially outward from the outer peripheral surface of the rotation support portion 22a, and the other end face 12s of the flange portion 12 rises radially outward from the outer peripheral surface of the eccentric portion 20. 2, one end face 12f of the flange portion 12 abuts against the end face of the inner ring 8i of the bearing 8 that supports the rotation support portion 22a. In this way, the flange portion 12 restricts the positional deviation of the bearing 8 toward the other end in the axial direction.

[0033] 2, the other end surface 12s of the flange portion 12 abuts against the end surface of the inner ring 24i of one bearing 24 fitted onto the outer peripheral surface of the eccentric portion 20. The flange portion 12 thereby restricts the axial displacement of the bearing 24 towards one end, and also receives the thrust reaction force (load in the tilting direction) acting on the bearing 24 through the reducer body 11.

[0034] 5, the flange portion 12 is formed in an annular shape with a uniform spacing distance of its outer circumferential surface from the eccentric portion 20. Therefore, the end face of the inner ring 24i of the bearing 24 abuts against the end face 12s of the flange portion 12 uniformly in the circumferential direction. In FIG. 5, dots are added to the area of ​​the end surface 12s of the flange portion 12 with which the end surface of the inner ring 24i of the bearing 24 abuts.

[0035] The reducer main body 11 also includes the above-mentioned pair of bearings 24 that are fitted to the eccentric portion 20 of the crankshaft 10, an oscillating gear 25 having the pair of bearings 24 fixed to its inner peripheral portion and having internal teeth 55b (first internal teeth) and external teeth 55a (first external teeth) on its outer peripheral region, a fixed gear 16 having internal teeth 16b (second internal teeth) that mesh with the external teeth 55a of the oscillating gear 25, and an output gear 27 having external teeth 17a (second external teeth) that mesh with the internal teeth 55b of the oscillating gear 25.

[0036] The oscillating gear 25 has a perforated, disk-shaped base wall 53 extending radially, a substantially cylindrical bearing housing 54 protruding from the radially inner end of the base wall 53 to the side opposite the motor unit 2, and a substantially cylindrical toothed wall 55 connected to the radially outer end of the base wall 53. A substantially cylindrical recess that opens toward the side opposite the motor unit 2 is formed between the toothed wall 55 and the bearing housing 54. The outer rings 24o of the bearing 24 described above are fitted and fixed to the inner circumferential surface of the bearing housing 54. The toothed wall 55 of the oscillating gear 25 has external teeth 55a formed on its outer circumferential surface and internal teeth 55b formed on its inner circumferential surface.

[0037] The fixed gear 16 is formed in an annular shape as a whole. The fixed gear 16 is fixed to the inner periphery of the casing main body 5A. Internal teeth 16b are formed on the inner periphery of the fixed gear 16. The fixed gear 16 is disposed on the outer periphery side of the tooth wall 55 of the oscillating gear 25, and the internal teeth 16b on the inner periphery can mesh with the external teeth 55a of the tooth wall 55.

[0038] The internal teeth 16b of the fixed gear 16 are formed so as to be concentric with the central axis L of the rotation support portions 22a, 22b of the crankshaft 10 when the fixed gear 16 is fixed to the casing main body 5A. The outer diameter of the external teeth 55a of the oscillating gear 25 is formed smaller than the inner diameter of the internal teeth 16b of the fixed gear 16. Furthermore, the number of teeth of the external teeth 55a of the oscillating gear 25 and the number of teeth of the internal teeth 16b of the fixed gear 16 are set to be different. Therefore, when the oscillating gear 25 oscillates in response to the oscillating rotation of the crankshaft 10, the external teeth 55a of the oscillating gear 25 meshes with the internal teeth 16b of the fixed gear 16, and the oscillating gear 25 receives a reaction force from the external teeth 55a and rotates in a predetermined direction. The rotation speed is reduced by a predetermined reduction ratio relative to the oscillating rotation of the crankshaft 10.

[0039] The output gear 27 includes a disk-shaped base wall 56 extending radially, and a substantially cylindrical outer toothed ring 17 protruding from a radially outer portion of the base wall 56 toward the motor unit 2. The outer peripheral surface of the base wall 56 is rotatably supported via bearings 26 on the inner peripheral surface of the annular block 5C of the casing 5. The output gear 27 is a member that outputs the rotation of the motor unit 2, which has been reduced in speed by the reducer body 11, to an external device. Fastening holes 28 are provided on the outer end surface of the base wall 56 to fasten and fix the output gear 27 to an external device (wheels of a vehicle).

[0040] A bearing accommodating recess 57 is formed on the surface of the base wall 56 facing the motor unit 2. The bearing accommodating recess 57 is provided in the radial center region of the base wall 56. The bearing accommodating recess 57 holds the bearing 21 for supporting the rotation support portion 22b of the crankshaft 10.

[0041] With the output gear 27 held in the annular block 5C (casing 5), the externally toothed ring 17 is inserted into an annular recess between the bearing housing 54 and the tooth wall 55 of the oscillating gear 25. On the outer circumferential surface of the externally toothed ring 17, external teeth 17a that can mesh with the internal teeth 55b of the oscillating gear 25 are formed. In this embodiment, the external toothed ring 17 has a structure in which a separate annular member having the external teeth 17a is fixed to a cylindrical portion formed integrally with the base wall 56. However, the structure of the external toothed ring 17 is not limited to this. The entire external toothed ring 17 may be formed by a member that is integral with the base wall 56.

[0042] The external teeth 17a of the external toothed ring 17 are formed so as to be concentric with the central axis L of the rotation support portions 22a, 22b of the crankshaft 10 when the output gear 27 is held in the annular block 5C (casing 5). The outer diameter of the external teeth 17a of the external toothed ring 17 is formed smaller than the inner diameter of the internal teeth 55b of the oscillating gear 25. Furthermore, the number of teeth of the external teeth 17a of the external toothed ring 17 is set to be the same as the number of teeth of the internal teeth 55b of the oscillating gear 25. With this configuration, when the oscillating gear 25 oscillates in response to the oscillating rotation of the crankshaft 10, only the rotation of the oscillating gear 25 is transmitted to the output gear 27. Therefore, the rotational power of the motor unit 2, which has been reduced through the reducer 4, is output to an external device (wheels of a vehicle) through the output gear 27.

[0043] <Effects of the embodiment> In the reducer 4 (motor 1 with a reducer) of this embodiment, the flange portion 12 of the crankshaft 10 is formed so that the center of the flange portion 12 in a direction perpendicular to the axial direction coincides with the center (central axis O) of the eccentric portion 20. Therefore, the inner ring 24i (engagement portion) of the bearing 24 of the reducer body 11 comes into concentric contact with the flange portion 12 of the crankshaft 10. As a result, a thrust load acts evenly in the circumferential direction from the inner ring 24i of the bearing 24 to the flange portion 12 of the crankshaft 10, making it difficult for a biased deformation load to act on the flange portion 12. Therefore, when the reducer 4 (motor 1 with a reducer) of this embodiment is employed, it is possible to suppress the input of unnecessary deformation load to the crankshaft 10 during use.

[0044] Therefore, by adopting the reducer 4 (motor 1 with reducer) of this embodiment, it is possible to contribute to Goal 7 of the Sustainable Development Goals (SDGs) led by the United Nations, which is to "Ensure access to affordable, reliable, sustainable and modern energy for all."

[0045] Furthermore, in the reducer 4 (reducer-equipped motor 1) of this embodiment, the flange portion 12 of the crankshaft 10 is formed in an annular shape with a uniform distance in the circumferential direction between the outer circumferential surface and the eccentric portion 20. This makes it easier for the inner ring 24i of the bearing 24 to abut against the end face 12s of the flange portion 12 of the crankshaft 10 more uniformly in the circumferential direction. Therefore, when this configuration is adopted, it is possible to further suppress the input of unnecessary deformation load to the crankshaft 10 during use. Also, in this configuration, since the outer periphery of the flange portion 12 is circular, it is possible to make the flange portion 12 smaller and lighter than when the outer periphery of the flange portion 12 is polygonal.

[0046] Furthermore, in the reducer 4 (motor 1 with reducer) of this embodiment, the reducer main body includes a bearing 24, an oscillating gear 25, a fixed gear 16, and an output gear 27. The bearing 24 is held on the inner periphery of the oscillating gear 25, and internal teeth 55b (first internal teeth) and external teeth 55a (second external teeth) are provided on the outer periphery of the oscillating gear 25. The fixed gear 16 is fixed to the casing 5, and includes internal teeth 16b (second internal teeth) that mesh with the external teeth 55a of the oscillating gear 25 and are concentric with the central axis L of the crankshaft 10. The output gear 27 includes external teeth (second external teeth) that mesh with the internal teeth 55b of the oscillating gear 25 and are concentric with the central axis L. Therefore, when this configuration is adopted, the power of the motor section can be efficiently decelerated and output to an external device, but part of the reaction force from the external device is likely to act as a large load that presses the bearing 24 in the tilting direction. However, in this embodiment, the flange section 12 of the crankshaft 10 is formed so that the center of the flange section 12 in the direction perpendicular to the axial direction coincides with the center (central axis O) of the eccentric section 20, so that the input of unnecessary deformation load to the crankshaft 10 can be reliably suppressed.

[0047] The present invention is not limited to the above-described embodiment, and various design modifications are possible without departing from the spirit of the present invention. For example, in the above-described embodiment, the speed reducer motor 1 is applied to the wheel drive unit of a vehicle, but the application of the speed reducer motor 1 is not limited to this. The speed reducer motor 1 can be applied to various other devices as long as the device uses a reduced motor power.

[0048] Furthermore, in the above embodiment, the flange portion 12 provided on the crankshaft 10 is formed in a circular shape (annular shape), but the shape of the flange portion 12 is not limited to this. The flange portion 12 may be, for example, polygonal when viewed in the axial direction. In this case, too, the flange portion 12 may be formed so that the center of the flange portion 12 in a direction perpendicular to the axial direction coincides with the center of the eccentric portion 20 in a direction perpendicular to the axial direction. [Explanation of symbols]

[0049] 1...motor with reducer, 2...motor section, 3...control section, 4...reduction gear, 5...casing, 5A...casing body, 5B...control section cover, 5C...annular block, 6...partition wall, 7...bearing housing, 8...bearing, 8i...inner ring, 10...crankshaft, 11...reduction gear body, 12...flange section, 12f...end face, 12s...end face, 16...fixed gear, 16b...internal teeth, 17...external tooth ring, 17a...external teeth, 20...eccentric section, 21...bearing, 22a...rotation support section, 22b...rotation support section, 24...bearing, 2 4i...inner ring, 24o...outer ring, 25...oscillating gear, 26...bearing, 27...output gear, 28...fastening hole, 29...bolt, 30...stator, 31...rotor, 32...stator core, 33...coil, 34...rotor core, 35...ring magnet, 40...connecting flange, 50...control board, 51...harness, 52...harness, 53...base wall, 54...bearing housing, 55...tooth wall, 55a...external teeth, 55b...internal teeth, 56...base wall, 57...bearing accommodating recess, L...central axis, O...central axis.

Claims

1. A casing; a crankshaft having a rotation support portion rotatably supported by the casing and an eccentric portion eccentric with respect to the rotation support portion, the crankshaft rotating when receiving a rotational force from an outside; a reducer body having an engagement portion that is engaged with an outer peripheral surface of the eccentric portion, the reducer body reducing the speed of the oscillating rotation of the eccentric portion received by the engagement portion and outputting the reduced speed to the outside; Equipped with The crankshaft is provided with a flange portion that protrudes radially outward from an end portion of the rotation support portion on the eccentric portion side and abuts against an axial end surface of the engagement portion, A reducer characterized in that the flange portion is formed so that its center in a direction perpendicular to the axial direction coincides with the center of the eccentric portion in the direction perpendicular to the axial direction.

2. The reducer according to claim 1, wherein the flange portion is formed in an annular shape such that a distance between an outer circumferential surface of the flange portion and the eccentric portion is uniform in a circumferential direction.

3. The reducer body includes: A bearing serving as the engagement portion; an oscillating gear rotatably supported by the eccentric portion of the crankshaft via the bearing, the oscillating gear having first internal teeth and first external teeth; a fixed gear fixed to the casing, meshed with the first external teeth of the oscillating gear, and having second internal teeth concentric with a central axis of the rotation support portion of the crankshaft; an output gear having second external teeth meshed with the first internal teeth of the oscillating gear and concentric with the central axis; The reducer according to claim 1, further comprising:

4. A reducer according to any one of claims 1 to 3; a motor unit connected to the crankshaft of the reduction gear; A motor with a reducer comprising:

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