JP2012097903A - In-wheel motor driving device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an in-wheel motor driving device which can prevent uneven wear inside a decelerating part and contributing to labor saving in management of dimensional errors during assembling.SOLUTION: The in-wheel motor driving device 21 includes a motor part A, the decelerating part B decelerating the rotation of the motor part A to transmit the rotation to an output shaft 28, and a wheel hub 32 to which the decelerated rotation by the decelerating part is transmitted. The decelerating part B includes: an input shaft 25 driven to rotate by the motor part; an output shaft 28 having a center hole to accept the input shaft and connected to the wheel hub so as not to be relatively rotated; two input shaft bearings 37a, 37b disposed on one side inner circumference of the center hole of the output shaft 28, and the other side in an axial direction, respectively, for rotatably supporting the input shaft at both ends in the axial direction of the decelerating part; and a decelerating mechanism that decelerates the rotation of the input shaft and transmits the rotation to the output shaft.

Description

  The present invention relates to a support structure for an output shaft of an in-wheel motor drive device.

  As a conventional cycloid reduction mechanism, there is a structure as described in Japanese Patent No. 2888673 (Patent Document 1). The structure described in Patent Document 1 is a cycloid reduction mechanism, and a high reduction ratio can be obtained as compared with a planetary gear type reduction mechanism that is general as a conventional reduction gear. However, in the conventional cycloid reduction mechanism as described above, the casing that rotatably supports the output shaft at one end in the axial direction, the internal gear disposed at the central portion in the axial direction, and the output at the other end in the axial direction. When the casing that rotatably supports the shaft is connected and fixed to each other by a bolt that extends in parallel with the axis, it is difficult to manage the assembly accuracy of the casing and the internal gear.

  That is, the casings and internal gears at both ends are assembled coaxially and in series so as to coincide with the axis, but when the parallelism of these casings and internal gears is slightly shifted after completion of the assembly, they are provided inside. The outer pins are worn unevenly, and the durability is reduced.

  As an in-wheel motor drive device including a cycloid reduction mechanism that eliminates such a problem, for example, a device described in Japanese Patent Application Laid-Open No. 2009-52630 (Patent Document 2) is known. The in-wheel motor drive device described in Patent Document 2 is coupled to a motor unit, a speed reduction unit that receives a driving force from the motor unit and decelerates the number of rotations to output to the wheel side, and an output shaft of the speed reduction unit The wheel hubs are arranged coaxially and in series. Since this speed reduction part is a cycloid speed reduction mechanism, it is advantageous in that the required torque of the drive motor can be reduced and the size and weight of the in-wheel motor drive device can be reduced. In addition, since the cylindrical outer pin holding portion holds the outer pin parallel to the axis, the outer pin is always held in parallel, and uneven wear of the outer pin can be prevented.

Japanese Patent No. 2888673 JP 2009-52630 A

  However, the present inventor has found that there is a further improvement in the conventional in-wheel motor drive device. That is, in the in-wheel motor drive device described in Patent Document 2, the wheel hub on the wheel side and the wheel-side rotating member of the speed reduction unit are usually coincident with the axis of the speed reduction unit. However, the wheel hub and the wheel-side rotating member are fixed to each other by diameter caulking, and are rotatably supported by the wheel hub bearing at the central portion in the axial direction. For this reason, the wheel-side rotating member is cantilevered inside the speed reduction portion. Then, the wheel side rotating member is given a radial load and a bending moment load from the wheel hub, and when the wheel side rotating member temporarily does not coincide with the central axis of the speed reducing portion, or one end in the axial direction of the wheel side rotating member is set to the other end in the axial direction. On the other hand, internal deformation such as temporary displacement may occur, and the inner pin and the curved plate inside the speed reduction portion may be unevenly worn.

  Moreover, the speed reduction mechanism used for a vehicle is not only manufactured by assembling a large number of parts having various dimensions, but also has different linear expansion coefficients such as steel material for securing strength and aluminum material for weight reduction. Manufactured by combining different kinds of metal members. For this reason, it is difficult to precisely manage internal gaps, dimensional errors, and geometric errors. Therefore, there is a possibility that the coaxial arrangement, the right angle arrangement, and the parallel arrangement of the parts may be out of the allowable range, and there is a concern about uneven wear inside the speed reduction unit, an increase in noise vibration, and a decrease in life.

  In view of the above circumstances, an object of the present invention is to provide an in-wheel motor drive device that can prevent uneven wear inside the speed reduction portion and contributes to labor saving in managing dimensional errors during assembly.

  The in-wheel motor drive device according to the present invention includes a motor unit, a deceleration unit that decelerates the rotation of the motor unit, and a wheel hub to which the rotation decelerated by the deceleration unit is transmitted. The speed reducer includes an input shaft that is rotationally driven by the motor unit, a center hole that receives the input shaft, and is connected to the wheel hub so as not to rotate relative to the wheel hub. Two input shaft bearings that are provided respectively on the circumference and the inner circumference of the other side and rotatably support the input shaft at both axial ends of the speed reduction portion, and a speed reduction mechanism that reduces the rotation of the input shaft and transmits it to the output shaft And have.

  Preferably, the speed reduction mechanism has an eccentric portion provided on the outer periphery of the input shaft between the two input shaft bearings, and is rotatably held by the eccentric portion and is centered on the rotation axis of the input shaft as the input shaft rotates. A revolving member that performs a revolving motion, an outer peripheral engagement member that engages with the outer peripheral portion of the revolving member to cause the revolving member to rotate, and takes out the revolving motion of the revolving member and converts it into a rotational motion of the output shaft. A motion conversion mechanism.

  Preferably, the motion conversion mechanism includes a plurality of through holes provided in the revolution member, and a plurality of inner pins that are inserted through the through holes and supported at both ends by the output shaft.

  An in-wheel motor drive device according to an embodiment of the present invention includes a motor unit, a speed reduction unit that decelerates rotation of the motor unit and transmits the motor unit to an output shaft, and a wheel hub coupled to the output shaft. Is inserted from a cylindrical casing side member that extends from one end to the other end in the axial direction of the speed reduction portion and integrally formed with the one end and the other end, and an inner space of the casing side member. An output shaft and two output shaft bearings provided on the inner periphery of both ends of the casing side member, respectively, for rotatably supporting the output shaft.

  According to this embodiment, since the two output shaft bearings are provided on the inner circumferences of both ends in the axial direction of the casing side member and rotatably support the output shaft, the output shaft is supported at both ends. Therefore, it becomes possible to hold the output shaft coaxially with the speed reduction part against the radial load and bending moment load input from the wheel hub, and to prevent the internal deformation of the speed reduction part and to prevent uneven wear inside the speed reduction part. Can be prevented. Further, the management of dimensional errors and geometric errors can be saved by supporting both ends of the output shaft.

  The cylindrical casing side member extending from one end to the other end in the axial direction of the speed reducing portion and integrally forming the one end and the other end is the axial direction as viewed from the center in the axial direction of the speed reducing portion. It refers to a fixing member that is attached to the casing across one and the other. Therefore, the casing side member may have the same axial dimension as the speed reducing part and span the entire axial direction of the speed reducing part from one end to the other end of the speed reducing part. May be short.

  In addition, the cylindrical casing side member in which one end and the other end are integrally formed is formed by forming the one end and the other end separately, and mechanically connecting them with a connecting member such as a bolt. Does not include.

  The reduction unit may be a general planetary gear type reduction mechanism, or may be a cycloid reduction mechanism. In addition, the output shaft of the speed reducer and the wheel hub may be coupled and fixed so that they cannot move relative to each other in the radial direction. Preferably, the wheel hub and the output shaft are allowed to have misaligned center axes. However, they are connected so that they cannot rotate relative to each other. According to such an embodiment, since the center axis of the wheel hub is allowed to be inconsistent with the center axis of the output shaft, the bending moment load is absorbed at the connecting portion, and the bending moment load is applied from the wheel hub to the output shaft. Is not given. Accordingly, it is possible to suitably prevent internal deformation of the speed reduction portion. Specifically, they are connected by a sliding type constant velocity joint. Alternatively, either the wheel hub or the output shaft has a center hole extending along the axial direction, the other remaining in the center hole is inserted, and the wheel hub and the output shaft rotate relative to each other with a radial clearance. Linked impossible. More specifically, a plurality of grooves and protrusions are provided at equal intervals in the inner periphery of the center hole, and the same grooves and protrusions are also provided in the circumferential direction on the other outer periphery of the wheel hub and the output shaft. They are provided at regular intervals and they fit loosely.

  On the other hand, the coupling between the motor unit and the speed reduction unit is not particularly limited. In addition, the input shaft of the speed reduction unit to which rotation is input from the motor unit may be rotatably supported by the casing, but preferably the output shaft has a central hole extending along the axial direction. The speed reducer is provided on the input shaft received in the center hole of the output shaft by being drivingly coupled to the motor portion, and on the one side inner periphery and the other side inner periphery of the center hole of the output shaft. It further has two input shaft bearings that rotatably support the input shaft at both axial ends. According to this embodiment, the two input shaft bearings that are respectively provided on the inner circumference on one side and the inner circumference on the other side of the output shaft and that rotatably support the input shaft at both ends in the axial direction of the speed reduction portion are further provided. Since it has, both input shafts are supported. Therefore, not only the output shaft but also the input shaft can be held coaxially with the speed reduction portion, and internal deformation of the speed reduction portion can be further suppressed, and uneven wear inside the speed reduction portion can be prevented. Further, the management of the dimensional error and the geometric error can be saved by supporting the input shaft with both ends.

  The motor part and the speed reduction part may be coupled by fixing the input shaft of the speed reduction part to the motor rotation shaft of the motor part so that the relative movement in the radial direction is impossible. Preferably, the motor part is attached and fixed to the rotor. A motor rotation shaft for outputting the rotational drive of the unit to the input shaft. The motor rotation shaft and the input shaft are coupled so as not to be relatively rotatable while allowing the center axes of the motor shaft to be misaligned. According to such an embodiment, since the center axis of the motor rotation shaft is allowed to be inconsistent with the center axis of the input shaft, the bending moment load is absorbed at the connecting portion, and the motor rotation shaft to the input shaft, Or conversely, no bending moment load is applied. Therefore, it is possible to suitably prevent both the motor unit and the speed reduction unit from being deformed internally. Specifically, they are connected by a sliding type constant velocity joint. Alternatively, either the motor rotation shaft or the input shaft has a center hole extending along the axial direction, and the other remaining in one center hole is inserted, and the motor rotation shaft and the input shaft are accompanied by a radial clearance. They are connected so that they cannot rotate relative to each other. More specifically, a plurality of grooves and protrusions are provided on the inner periphery of the center hole at equal intervals in the circumferential direction, and similar grooves and protrusions are also provided around the other outer periphery of the motor rotation shaft and the input shaft. They are provided at equal intervals in the direction, and they fit loosely.

  Preferably, the speed reducing unit has a cycloid speed reducing mechanism. Specifically, the speed reducer is attached to the input shaft by being eccentric from the rotation axis of the input shaft, and the inner periphery is attached to the outer periphery of the eccentric member so as to be relatively rotatable. Accordingly, a revolving member that performs a revolving motion around the rotation axis, an outer peripheral engagement member that engages with the outer peripheral portion of the revolving member to cause the revolving motion of the revolving member, and an output shaft provided on the output shaft. And an inner engagement member for extracting motion. The casing side member supports the outer peripheral engagement member at both ends. According to this embodiment, since the casing side member supports the outer peripheral engagement member at both axial ends, the outer peripheral engagement member can be held in parallel with the axis of the speed reduction portion. Therefore, uneven wear inside the speed reduction portion can be prevented.

  More specifically, the inner engagement members are pins extending in parallel with the axis, and a plurality of inner engagement members are disposed on the output shaft at equal intervals in the circumferential direction. The output shaft includes an output shaft main body disposed on the side close to the wheel hub, a plurality of pins protruding from the output shaft main body, and a ring portion disposed on the side far from the wheel hub and coupling the tips of the plurality of pins to each other. including. An output shaft bearing is provided between the inner circumference of one end in the axial direction of the casing side member and the outer circumference of the output shaft body, and between the inner circumference of the other end in the axial direction of the casing side member and the outer circumference of the ring portion. Is provided with one output shaft bearing. More preferably, one input shaft bearing is provided between the inner periphery of the output shaft main body and one outer periphery of the input shaft, and one remaining between the inner periphery of the ring portion and the other outer periphery of the input shaft. Input shaft bearings are provided.

  According to the present invention, two input shaft bearings are provided on the inner circumference on the one side and the other side on the other side in the axial direction of the center hole of the output shaft, respectively, and the input shaft can freely rotate at both ends in the axial direction of the speed reduction portion. Therefore, the output shaft can be held coaxially with the speed reduction portion. Therefore, against the radial load and bending moment load input from the wheel hub to the output shaft, the output shaft of the speed reducer is prevented from becoming parallel to the axis, and uneven wear inside the speed reducer is prevented. Can do. As a result, the durability performance of the in-wheel motor drive device is improved.

  In a further preferred embodiment, the casing side member, the output shaft, the input shaft, and the output shaft and the input, which are constituent elements of the speed reduction unit, are provided by having the output shaft bearing and the input shaft bearing at both axial ends of the speed reduction unit. It is possible to unitize various rotating elements arranged between the shafts. Therefore, it is possible to assemble the unitized reduction unit on an assembly line different from the assembly line of the in-wheel motor drive device, and the assembly efficiency of the in-wheel motor drive device is improved.

It is a longitudinal cross-sectional view which shows the in-wheel motor drive device which becomes one Example of this invention. It is a cross-sectional view in the deceleration part of FIG.

  Hereinafter, embodiments of the present invention will be described in detail based on examples shown in the drawings.

  FIG. 1 is a longitudinal sectional view showing an in-wheel motor drive apparatus according to an embodiment of the present invention. FIG. 2 is a transverse cross-sectional view of the speed reduction portion of FIG. The in-wheel motor drive device 21 includes a motor unit A as a motor drive device that generates a driving force, a deceleration unit B that decelerates and outputs the rotation of the motor unit A, and a drive wheel (not shown) that outputs from the deceleration unit B And a wheel hub bearing portion C for transmitting to the vehicle, and is mounted in a wheel housing of the electric vehicle. And it arrange | positions coaxially and in series in order of the motor part A, the deceleration part B, and the wheel hub bearing part C.

  The motor part A includes a cylindrical motor part casing 22a that forms an outer shell, a partition wall 46 that defines an internal space between the motor part A and the speed reduction part B, and an end opposite to the partition wall 46 at both ends of the motor part casing 22a. An axial gap motor having a rear cover 22r fixed to the motor, a stator 23 fixed to the motor casing 22a and the rear cover 22r, and a rotor 24 disposed at a position facing the stator 23 with an axial gap therebetween. It is. Further, a sealing member 47 is provided in the center hole of the rear cover 22r in order to prevent dust from entering the motor part A.

  The rotor 24 has a flange-shaped rotor portion 24a and a cylindrical hollow portion 24b. The hollow portion 24b extends along the axis O and has a through hole 48 at the center. The rotor portion 24a has a flange shape that expands radially outward from the end of the hollow portion 24b, and both surfaces thereof face the stator 23, respectively. An input shaft 25 extending from the speed reduction portion B is inserted and fixed in the hollow portion 24b which is a motor rotation shaft fixed to the rotor.

  The partition wall 46 has a through-hole at the center, and includes a disk-shaped partition wall main body 46w and a cylindrical portion 46p extending along the axis O from the center of the partition wall main body 46w toward the motor part A side. The hollow portion 24b and the input shaft 25 pass through the through hole of the cylindrical portion 46p. Further, the partition wall 46 rotatably supports the outer periphery of the hollow portion 24b via the rolling bearings 36a and 36b at two locations on the inner periphery of the cylindrical portion 46p separated in the axis O direction. A sealing member 49 is provided in the annular gap between the cylindrical portion 46p and the hollow portion 24b in order to prevent the lubricant encapsulated in the speed reduction portion B from entering the motor portion A.

  A plurality of grooves and protrusions extending in the direction of the axis O are formed on the inner peripheral surface of the through hole 48 at equal intervals in the circumferential direction. A plurality of similar grooves and protrusions extending in the direction of the axis O are formed at equal intervals in the circumferential direction on the outer peripheral surface of the input shaft 25 on the motor portion A side. The input shaft 25 extending from the speed reduction portion B is inserted into the through hole 48 of the hollow portion 24b and is serrated, and the input shaft 25 and the rotor 24 are connected so as not to be relatively rotatable. However, this serration fitting is loosely fitted with a radial gap, allowing the relative center axes to be misaligned and allowing some radial relative movement and bending. As a result, the bending moment load is absorbed by the radial gap, and the bending moment load is not transmitted from the rotor 24 to the input shaft 25 or vice versa.

  Although not shown in the drawings, as a modification, a hole may be provided in the input shaft, and one end of the rotor rotation shaft may be inserted into the input shaft and connected so as not to be relatively rotatable with a radial clearance. .

  The input shaft 25 extends along the axis O, and is arranged from the motor part A to the speed reduction part B in order to transmit the driving force of the motor part A to the speed reduction part B. The input shaft bearings 37a, 37b. The two input shaft bearings 37a and 37b are rolling bearings. Two eccentric portions 25a and 25b are formed on the outer periphery of the input shaft 25 between the input shaft bearing 37a and the input shaft bearing 37b. The eccentric portions 25a and 25b provided in the speed reduction portion B have a disc shape, but are provided eccentric from the axis O. The two eccentric portions 25a and 25b are provided with a phase difference of 180 ° in order to cancel out vibrations generated by the centrifugal force due to the eccentric motion.

  The speed reduction part B is an input shaft 25 that is drivingly coupled to the motor part A, eccentric parts 25a and 25b, an output shaft 28 that outputs reduced speed rotation, and a revolution member that is rotatably held by the eccentric parts 25a and 25b. Curve plates 26a and 26b, a plurality of outer pins 27 as outer peripheral engagement members that engage with the outer peripheral portions of the curve plates 26a and 26b, and a motion conversion mechanism that transmits the rotational motion of the curve plates 26a and 26b to the output shaft 28. And an annular center collar 29 inserted between the curved plates 26a and 26b.

  The speed reduction part casing 22b that forms the outline of the speed reduction part B is a cylindrical member in which both ends of the axis O direction and the central part are integrally formed. The speed reduction part casing 22b is connected and fixed to the outer ring side member 22c of the wheel hub bearing part C by a bolt 56 at one end in the axial direction, and is connected and fixed to the motor part casing 22a of the motor part A by a bolt 57 at the other end in the axial direction. . And a diameter dimension becomes small in order of the motor part casing 22a, the deceleration part casing 22b, and the outer ring | wheel side member 22c. For this reason, the flange part 22m is formed in the axial direction other end of the outer ring | wheel side member 22c, and the volt | bolt 56 penetrates the flange part 22m. A flange portion 22l is formed at the other axial end of the deceleration portion casing 22b, and a bolt 57 passes through the flange portion 22l. The outer peripheral portion of the partition wall main body 46w is connected and fixed to the end of the speed reduction portion casing 22b on the side close to the motor portion A by bolts 58. The casings 22a and 22b, the rear cover 22r, and the outer ring side member 22c constitute the casing 22 of the in-wheel motor drive device 21.

  An outer pin holding member 45, which will be described later, is attached and fixed to the inner periphery of the speed reduction unit casing 22b. The outer pin holding member 45 is a casing-side member, and is a cylindrical member in which both end portions and the center portion in the axis O direction are integrally formed, and has inward flange portions 45f at both ends in the axis O direction. The flange portions 45f at both ends hold the outer pin 27 in parallel with the axis O via the needle roller bearing 27a. An output shaft is coaxially inserted into the inner space of the outer pin holding member 45.

  The output shaft 28 extends along the axis O, an output shaft main body 28m disposed on the side close to the wheel hub bearing portion C, a plurality of inner pins 31 protruding from the output shaft main body 28m and extending in parallel with the axis O, And a ring portion 28r that is disposed on the side far from the wheel hub bearing portion C and connects the tips of the plurality of inner pins 31 to each other. The output shaft main body 28m has a center hole 51 extending along the axis O. A plurality of inner pins 31 are arranged on the output shaft 28 at equal intervals in the circumferential direction. The center hole 51, the space surrounded by the plurality of inner pins 31, and the center hole of the ring portion 28r receive the end of the input shaft 25.

  In the annular space between the inner peripheral surface of the center hole 51 and the outer peripheral surface of the input shaft 25, the one input shaft bearing 37b described above is provided. Further, one input shaft bearing 37a remaining in the annular space between the inner peripheral surface of the ring portion 28r and the outer peripheral surface of the input shaft 25 is provided. Thus, the input shaft 25 is rotatably supported by the output shaft 28 via the input shaft bearings 37a and 37b at two locations on both ends of the speed reduction portion B and separated in the direction of the axis O.

  The output shaft main body 28m is formed with a plurality of holes for fixing the inner pins 31 at equal intervals on the circumference centered on the axis O, on the outer diameter side of the center hole 51. A center hole 52 extending along the axis O is formed on the wheel hub bearing portion C side with respect to the center hole 51. The center hole 52 has a smaller diameter than the center hole 51. Similarly, the outer periphery of one end of the output shaft main body 28m constituting the center hole 52 is smaller in diameter than the outer periphery of the other end of the output shaft main body 28m constituting the center hole 51. In this way, the output shaft main body 28m is formed with a small diameter at one end in the axis O direction and formed with a large diameter at the other end in the axis O direction.

  A plurality of grooves and protrusions extending in the direction of the axis O are formed on the inner peripheral surface of the center hole 52 at equal intervals in the circumferential direction. A plurality of similar grooves and protrusions extending in the direction of the axis O are formed at equal intervals in the circumferential direction on the outer peripheral surface of the end of the wheel hub 32 on the speed reduction portion B side. A wheel hub 32 extending from the wheel hub bearing portion C is inserted into the center hole 52 and is serrated, and the output shaft 28 and the wheel hub 32 are connected so as not to be relatively rotatable. However, this serration fitting is loosely fitted with a radial gap, allowing the relative center axes to be misaligned and allowing some radial relative movement and bending. Thereby, the bending moment load is absorbed by the radial gap, and the bending moment load is not transmitted from the wheel hub 32 to the output shaft 28.

  Although not shown in the drawings, as a modification, a hole may be provided in the wheel hub, and one end of the output shaft may be inserted into the wheel hub and connected so as not to be relatively rotatable with a radial clearance.

  The center hole 52 and the inward flange portion 45f at one end of the outer pin holding member 45 are located at the same position in the axis O direction. One output shaft bearing 38b is provided in the annular space between the outer periphery of the output shaft main body 28m and the inner peripheral surface of the inward flange portion 45f at the outer diameter side of the center hole 52 and at the same axial position. It is done.

  A ring-shaped protrusion 53 that protrudes toward the motor part A is formed on the inner peripheral part of the ring part 28 r of the output shaft 28. The outer periphery 54 of the protrusion 53 has a smaller diameter than the outer periphery 55 at the same position as the input shaft bearing 37a in the axis O direction. Thus, the ring portion 28r is formed to have a large diameter at one end in the axis O direction and to have a small diameter at the other end in the axis O direction. A small-diameter outer periphery 54 of the output shaft 28 and an inward flange portion 45f at the other end of the outer pin holding member 45 are located at the same position in the axis O direction. One output shaft bearing 38a is provided in the annular space between the outer periphery 54 and the inner peripheral surface of the inward flange portion 45f.

Thus, the outer pin holding member 45 serving as the casing side member rotatably supports the output shaft 28 via the two output shaft bearings 38a and 38b provided on the inner circumferences of both ends of the casing side member.

  Referring to FIG. 2, the curved plate 26 b has a plurality of corrugations composed of trochoidal curves such as epitrochoids on the outer periphery, and a plurality of through holes 30 a and 30 b penetrating from one end face to the other end face. Have A plurality of through holes 30a are provided at equal intervals on the circumference centered on the rotation axis of the curved plate 26a, and receive inner pins 31 described later. Further, the through hole 30b is provided at the center (rotation axis) of the curved plate 26a and becomes the inner periphery of the curved plate 26b. The curved plate 26b is attached to the outer periphery of the eccentric portion 25b so as to be relatively rotatable.

  The curved plate 26b is rotatably supported by the rolling bearing 41 with respect to the eccentric portion 25b. This rolling bearing 41 is fitted to the outer peripheral surface of the eccentric portion 25b, and the inner ring member 42 having the inner raceway surface 42a on the outer periphery thereof and the inner peripheral surface of the through hole 30b of the curved plate 26b as the outer raceway surface 43 The cylindrical roller bearing includes a plurality of rollers 44 disposed between the raceway surface 42a and the outer raceway surface 43, and a cage (not shown) that holds the spacing between the adjacent rollers 44, 44. Alternatively, the rolling bearing 41 may be a deep groove ball bearing. The inner ring member 42 further includes a pair of flange portions facing each other with the inner raceway surface 42a of the inner ring member 42 on which the rollers 44 roll, and holds the rollers 44 between the pair of flange portions. The same applies to the curved plate 26a.

  A plurality of outer pins 27 that engage with the outer peripheries of the curved plates 26a, 26b are provided at equal intervals on a circumferential track centering on the axis O. When the curved plates 26a and 26b are revolved around the eccentric portions 25a and 25b, the curved concave portions on the outer periphery of the curved plates 26a and 26b and the outer pin 27 are engaged, and the curved plates 26a and 26b are rotated. Give rise to

  The outer pin 27 disposed inside the speed reduction part casing 22b may be directly held by the speed reduction part casing 22b, but preferably is an outer pin holding part fitted and fixed to the inner wall of the speed reduction part casing 22b. 45. More specifically, both end portions in the axial direction of the outer pin 27 are rotatably supported by needle roller bearings 27 a attached to the outer pin holding portion 45. Thus, by attaching the outer pin 27 to the outer pin holding portion 45 so as to be rotatable, the contact resistance due to the engagement with the curved plates 26a, 26b can be reduced.

  From the viewpoint of reducing the weight of the in-wheel motor drive device 21, the casings 22a and 22b are formed of a light metal such as an aluminum alloy or a magnesium alloy. On the other hand, the outer ring side member 22c that supports the radial load of the drive wheel is preferably made of steel, and the outer pin holding portion 45, which requires high strength, is preferably made of carbon steel.

  The motion conversion mechanism includes a plurality of through holes 30a provided in the curved plates 26a and 26b, and a plurality of inner pins 31 provided in the center of the output shaft 28 and inserted through the through holes 30a. The inner pins 31 are provided at equal intervals on a circumferential track centering on the rotation axis O of the output shaft 28, and both ends in the axial direction are fixed to the output shaft main body 28m and the ring portion 28r, respectively. As shown in FIG. 2, the inner pin 31 is also referred to as an inner engagement member because it engages with the curved plates 26a and 26b on the inner diameter side of the outer peripheral portions of the curved plates 26a and 26b.

  In order to reduce the frictional resistance with the curved plates 26a, 26b, a needle roller bearing 31a is provided at the center in the axial direction of the inner pin 31. On the other hand, the through hole 30a is provided at a position corresponding to each of the plurality of inner pins 31, and the inner diameter of the through hole 30a is the outer diameter of the inner pin 31 ("the maximum outer diameter including the needle roller bearing 31a"). The same shall apply hereinafter).

  Returning to FIG. 1, the wheel hub bearing portion C constitutes a wheel hub 32 connected to the output shaft 28, a wheel hub bearing 33 that rotatably holds the wheel hub 32, and an outer ring of the wheel hub bearing 33. And an outer ring side member 22c. The wheel hub 32 extends along the axis O, and includes a cylindrical hollow portion 32a, an outer cylindrical portion 32b attached and fixed to the outer periphery of the hollow portion 32a, and a shaft portion 32d inserted and fixed in the center hole of the hollow portion. Have. The shaft portion 32 d extends along the axis O, and the end portion on the speed reduction portion B side is connected to the output shaft 28. A driving wheel (not shown) is fixedly connected to a flange portion 32f formed on the outer periphery of the outer cylinder portion 32b by a bolt 32c.

  The hollow portion 32a and the outer cylinder portion 32b are fixed by diameter expansion caulking. “Diameter caulking” means that a caulking jig (not shown) having an outer diameter slightly larger than the inner diameter of the hollow portion 32a is press-fitted into the center hole of the hollow portion 32a with the in-wheel motor drive device 21 fixed. By doing so, the hollow part 32a and the outer cylinder part 32b are plastic-coupled by the plastic coupling part 40. By fixing and connecting the hollow portion 32a and the outer cylinder portion 32b by the above method, the coupling strength can be greatly increased as compared with the case of fixing by fitting. Thereby, it becomes possible to hold | maintain the flange part 32f stably.

  The wheel hub bearing 33 is a double-row angular ball bearing that employs balls 33e as rolling elements. As the outer raceway surface of the ball 33e, a first outer raceway surface 33a (right side in the drawing) is provided on the inner circumferential surface of the outer ring side member 22c on the side closer to the speed reduction portion B, and the second outer raceway surface on the side farther from the speed reduction portion B. An outer raceway surface 33b (left side in the figure) is provided. As the inner raceway surface of the ball 33e, the first inner raceway surface 33c that faces the first outer raceway surface 33a is the outer peripheral surface of the hollow portion 32a, and the second inner raceway surface 33d that faces the second outer raceway surface 33b. It is provided on the outer peripheral surface of the outer cylinder part 32b. A plurality of balls 33e are arranged between the first outer raceway surface 33a and the first inner raceway surface 33c and between the second outer raceway surface 33b and the second inner raceway surface 33d. Further, the wheel hub bearing 33 prevents the cage 33f that holds the balls 33e in the left and right rows in the direction of the axis O, and the leakage of a lubricant such as grease enclosed in the bearing and the entry of dust from the outside. And a sealing member 33g.

  The operation principle of the in-wheel motor drive device 21 having the above configuration will be described in detail.

  For example, the motor unit A receives an electromagnetic force generated by supplying an alternating current to the stator 23, and the rotor 24 including a magnetic body or a permanent magnet rotates. As a result, the input shaft 25 rotates together with the rotor 24 as a speed reducer input shaft, and the eccentric portions 25a and 25b coupled to the input shaft 25 move eccentrically about the axis O.

  Then, the curved plates 26a and 26b revolve around the axis O. At this time, the outer pin 27 engages with the curved concave portions formed on the outer circumferences of the curved plates 26 a and 26 b while being in rolling contact with each other, and causes the curved plates 26 a and 26 b to rotate in the direction opposite to the rotation of the input shaft 25. .

  The outer diameter of the inner pin 31 inserted through the through hole 30a is sufficiently smaller than the inner diameter of the through hole 30a, and comes into contact with the inner peripheral surface of the through hole 30a as the curved plates 26a and 26b rotate. Thereby, the revolution movement of the curved plates 26 a and 26 b is not transmitted to the inner pin 31, and only the rotational motion of the curved plates 26 a and 26 b is transmitted to the wheel hub 32 via the output shaft 28.

At this time, the output shaft 28 arranged coaxially with the axis O takes out the rotation motion of the curved plates 26a and 26b as the output portion of the speed reduction unit. The reduction ratio of the reduction part B is calculated as (Z _A −Z _B ) / Z _B where Z _{A is} the number of outer pins 27 and Z _B is the number of waveforms of the curved plates 26a and 26b. In the embodiment shown in FIG. 2, since Z _A = 12 and Z _B = 11, the reduction ratio is 1/11, and a very large reduction ratio can be obtained. As a result, the rotation of the input shaft 25 is decelerated by the speed reduction unit B and transmitted to the output shaft 28. Therefore, even when the low torque, high rotation type motor unit A is employed, the necessary torque is transmitted to the drive wheels. It becomes possible.

  In this way, by adopting the speed reduction unit B that can obtain a large speed reduction ratio without using a multi-stage configuration, the in-wheel motor drive device 21 having a compact and high speed reduction ratio can be obtained. Since the outer pin 27 is rotatable with respect to the outer pin holding portion 45 and the needle roller bearing 31a is provided at a position where the outer pin 27 comes into contact with the curved plates 26a and 26b of the inner pin 31, the frictional resistance is reduced. The transmission efficiency of the deceleration part B is improved.

  By the way, according to the present embodiment, the two output shaft bearings are provided on the inner circumferences of both ends of the cylindrical outer pin holding member 45 integrally formed at both ends in the axis O direction and rotatably support the output shaft 28. 38a, 38b. As a result, the output shaft 28 can be supported at both ends, and the output shaft 28 can be held coaxially with the speed reduction portion B against a radial load and a bending moment load input from the wheel hub 32 to the speed reduction portion B. Become. Therefore, the internal deformation of the deceleration part B can be suppressed and uneven wear of the inner pin 31, the curved plates 26a and 26b, and the outer pin 27 can be prevented.

  Further, according to the present embodiment, the input shaft 25 is provided at both ends of the output shaft main body 28m on the one side in the axis O direction and the inner periphery of the ring portion 28r on the other side in the axis O direction. Are further provided with two input shaft bearings 37a and 37b. Thereby, the input shaft 25 can be supported at both ends, and not only the output shaft 28 but also the input shaft 25 can be held coaxially with the speed reduction portion. Therefore, the internal deformation of the speed reduction part B can be further suppressed, and uneven wear of the curved plates 26a and 26b and the rolling bearing 41 can be prevented.

  Further, according to the present embodiment, the output shaft main body 28m is formed with a small diameter at one end in the axis O direction and formed with a large diameter at the other end in the axis O direction. Further, the ring portion 28r of the output shaft 28 is formed with a large diameter at one end in the axis O direction and formed with a small diameter at the other end in the axis O direction. As a result, the output shaft bearings 38a and 38b and the inner pin 31 can be disposed at the same radial position, and the input shaft bearings 37a and 37b can be disposed at the same axial position as both ends of the inner pin 31 and on the inner diameter side. It becomes possible to arrange in. As a result, the parts layout arrangement of the speed reduction part B becomes suitable, and the speed reduction part B can be reduced in size.

  Furthermore, according to the present embodiment, the output shaft bearings 38a and 38b are provided on the inner periphery of both ends of the outer pin holding member 45 to rotatably support the output shaft 28, and the input shaft bearings 37a, Since the input shaft 25 is rotatably supported by providing 37b and the curved plates 26a and 26b are provided between the input shaft bearings 37a and 37b, the reduction part B can be unitized. Therefore, it is possible to assemble the unitized reduction unit B in an assembly line different from the assembly line of the in-wheel motor drive device 21, and the assembly efficiency of the in-wheel motor drive device 21 is improved.

  Although the embodiments of the present invention have been described with reference to the drawings, the present invention is not limited to the illustrated embodiments. Various modifications and variations can be made to the illustrated embodiment within the same range or equivalent range as the present invention.

  The in-wheel motor drive device according to the present invention is advantageously used in electric vehicles and hybrid vehicles.

  21 in-wheel motor drive device, 22 casing, 22a motor part casing, 22b speed reduction part casing, 22c outer ring side member, 22r rear cover, 23 stator, 24 rotor, 24b hollow part, 25 input shaft, 25a, 25b eccentric part, 26a, 26b Curved plate, 27 Outer pin, 28 Output shaft, 28m Output shaft body, 28r Ring part, 29 Center collar, 31 Inner pin, 32 Wheel hub, 33 Wheel hub bearing, 37a, 37b Input shaft bearing, 38a, 38b Output shaft Bearing, 41 Rolling bearing, 45 Outer pin holding member (casing side member), 46 Bulkhead.

Claims (3)

A motor unit, a deceleration unit that decelerates the rotation of the motor unit, and a wheel hub to which the rotation decelerated by the deceleration unit is transmitted,
The speed reduction unit includes an input shaft that is rotationally driven by the motor unit;
An output shaft having a central hole for receiving the input shaft and connected to the wheel hub in a relatively non-rotatable manner;
Two input shaft bearings that are respectively provided on one inner circumference and one other inner circumference of the center hole of the output shaft and rotatably support the input shaft at both axial ends of the speed reducer;
An in-wheel motor drive device comprising: a reduction mechanism that decelerates the rotation of the input shaft and transmits it to the output shaft. The deceleration mechanism is
An eccentric portion provided on an outer periphery of the input shaft between the two input shaft bearings;
A revolving member that is rotatably held by the eccentric portion and performs a revolving motion around the rotation axis of the input shaft as the input shaft rotates,
An outer periphery engaging member that engages with an outer peripheral portion of the revolving member to cause rotation of the revolving member;
The in-wheel motor drive device according to claim 1, further comprising: a motion conversion mechanism that extracts a rotation motion of the revolution member and converts the rotation motion into a rotation motion of the output shaft. 3. The in-wheel according to claim 2, wherein the motion conversion mechanism includes a plurality of through holes provided in the revolving member and a plurality of inner pins that are inserted through the through holes and supported at the output shafts at both ends thereof. Motor drive device.

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