JP2020058137A - Motor support bearing for pre-load imparting structure, electric motor, and in-wheel motor drive unit - Google Patents

Abstract

To provide a pre-load imparting structure for a motor support bearing that is capable of improving assemblability of a component.SOLUTION: A protection member 72 includes: a ring part 72a; a cylinder part 72b projecting in an axial direction from the ring part 72a; and a projection part 72c projecting in an outer diameter direction from the ring part 72a. A concave part 81a includes: an axial groove 91 provided in the axial direction from its concave open end 81b toward a concave bottom surface 81c side; and a circumferential groove 92 in communication with the axial groove 91 on the concave bottom surface 81c side and provided in a circumferential direction. The projection part 72c is configured to be movable in the axial direction along the axial groove 91, and to movable in the circumferential direction along the circumferential groove 92.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a preload applying structure for a motor support bearing, an electric motor including the structure, and an in-wheel motor driving device.

  2. Description of the Related Art Conventionally, there has been known a technology of reducing vibration and noise by applying an axial preload to a bearing supporting a rotating shaft of an electric motor using an elastic member such as a wave washer or a spring (for example, , Patent Documents 1 and 2).

  However, in such a preload applying structure, when the state in which the elastic member is completely compressed in the axial direction is repeated, there is a problem that the elastic member is fatigued and deteriorated. The term “deterioration” means that the elastic member is damaged such as a crack or a crack, or that the elastic member is plastically deformed and the free length is shortened. On the other hand, Patent Document 3 proposes a preload applying structure provided with a backing ring as a protection member for protecting the elastic member from being completely compressed.

  More specifically, as shown in FIG. 13, the backing ring 100 has a shoulder portion 100 a disposed between the bearing 300 and the spring 200, and the spring 200 is disposed on the outer periphery of the shoulder portion 100 a so as to protrude in the axial direction. The spring 200 urges the bearing 300 in the axial direction via the shoulder 100a. When the bearing 300 is displaced to the right in FIG. 13 together with the motor rotation shaft 400, the protrusion 100b of the backing ring 100 is provided on the motor housing 600 before the spring 200 is completely compressed with this displacement. The spring 200 is configured to be prevented from being further compressed by abutting the stopper 500 that has been set.

JP 2009-201255 A JP 2016-32422 A Japanese Patent No. 3133014

  The backing ring 100 and the spring 200 shown in FIG. 13 are housed in a concave portion 600a provided in the motor housing 600. Here, the backing ring 100 and the spring 200 need to be accommodated with a certain margin (gap) with respect to the inner surface of the concave portion 600a so that axial displacement is allowed. For this reason, if the opening of the concave portion 600a turns sideways or downwards when assembling the components, the backing ring 100 and the spring 200 may fall off or fall down from the concave portion 600a. As described above, in the conventional configuration, there is a problem in the assemblability of the backing ring 100 and the spring 200 to the concave portion 600a of the motor housing 600, and a countermeasure is required.

  Therefore, an object of the present invention is to provide a preload applying structure of a motor support bearing, an electric motor, and an in-wheel motor drive device, which can improve the assemblability of parts.

  In order to solve the above-described problems, the present invention provides an elastic member that urges a bearing that supports a motor rotation shaft of an electric motor to apply a preload in an axial direction, and that an elastic member is completely compressed in an axial direction. A preload applying structure for a motor support bearing, comprising: a protection member to be prevented; and a casing provided with a recess in which the elastic member and the protection member are housed, wherein the protection member is disposed between the elastic member and the bearing. A ring portion, a cylindrical portion protruding in the axial direction from the ring portion and having an elastic member disposed on an outer periphery or an inner periphery, and a protruding portion projecting from the ring portion in an outer radial direction; An axial groove provided in the axial direction from the end toward the concave bottom surface side, and a circumferential groove provided in the circumferential direction and communicating with the axial groove on the concave bottom surface side, While being configured to be movable in the axial direction along the direction groove, Characterized in that it is configured to be movable in the circumferential direction along the groove.

  When assembling the protective member and the elastic member to the casing, the protective member is inserted into the concave portion of the casing with the elastic member attached to the protective member, or with the elastic member inserted into the concave portion of the casing. At this time, the protrusion of the protection member is moved along the axial groove, and the protection member is inserted into the recess in the axial direction. Next, the protection member is rotated by moving the protrusion along the circumferential groove. Thus, the circumferential phase of the protrusion and the axial groove is shifted, so that the axial movement of the protection member is regulated, and the protection member and the elastic member are prevented from falling off or falling down from the recess. . As described above, according to the present invention, since the protective member and the elastic member can be prevented from falling off or falling down with respect to the casing, the protective member, the elastic member, and the casing can be handled as an integrated unit. The assembly workability is improved.

  When the motor rotation shaft is displaced in the axial direction due to vibration, etc., before the elastic member is completely compressed in the axial direction, the cylindrical portion of the protective member comes into contact with the bottom surface of the concave portion, so that further compression of the elastic member is prevented. Is prevented. At this time, it is preferable that the protrusion does not contact the wall surface on the concave bottom surface side of the circumferential groove. In this way, by preventing the protrusion from contacting the wall surface on the concave bottom surface side of the circumferential groove, an axial load is prevented from acting between the protrusion and the concave wall surface on the concave bottom surface side. You. This makes it possible to prevent deformation and damage of the protrusions and the circumferential grooves.

  Further, by providing a convex or concave hook portion on the inner periphery of the protection member, when rotating the protection member along the circumferential groove, a tool or the like can be hooked on the hook portion to rotate the protection member. . Thereby, rotation of the protection member is facilitated, and assembling workability is further improved.

  As the elastic member, for example, an annular or spiral spring member can be used.

  Further, the preload applying structure according to the present invention supports a casing, a stator fixed to the casing, a motor rotation shaft, a rotor that rotates integrally with the motor rotation shaft, and a motor rotation shaft that is rotatable with respect to the casing. By applying the present invention to an electric motor including a bearing to be applied and a preload applying structure for applying an axial preload to the bearing, the assembling workability is improved.

  Further, the preload applying structure according to the present invention may be provided on both ends of the motor rotation shaft, and individually apply a preload to a pair of bearings supporting the motor rotation shaft.

  Also, an in-wheel including an electric motor having a preload applying structure according to the present invention, an electric motor unit, a wheel bearing unit, and a reduction gear unit that reduces the speed of the rotation of the electric motor unit and transmits the rotation to the wheel bearing unit. You may apply to a motor drive device.

  ADVANTAGE OF THE INVENTION According to this invention, since the assembling property of the protective member and the elastic member to the casing is improved, the assembling work becomes easier.

It is a sectional view of an in-wheel motor drive provided with a precompression giving structure concerning one embodiment of the present invention. It is sectional drawing which expands and shows the preload provision structure and its periphery. It is a perspective view of a protection member and an inner cover. It is sectional drawing which shows the state which attached the protection member and the wave spring. It is sectional drawing which shows a mode that a protection member is inserted in an axial direction with respect to an inner cover with a wave spring. It is sectional drawing which shows the state which rotated the protection member in the inner cover inside the circumferential direction. It is sectional drawing which shows a mode that a motor rotating shaft is inserted vertically and assembled. It is sectional drawing which shows a mode that an inner cover with which the protection member and the wave spring were assembled is assembled with respect to a casing main-body part. It is sectional drawing which shows the state which the cylindrical part of the protection member contacted the recess bottom surface. FIG. 6 is a cross-sectional view illustrating a preload applying structure according to another embodiment of the present invention. It is a top view showing the schematic structure of the electric vehicle carrying the in-wheel motor drive. FIG. 12 is a rear sectional view illustrating the electric vehicle in FIG. 11. It is sectional drawing which shows the conventional preload provision structure.

  Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings, taking an in-wheel motor drive device arranged in an inner space area of a wheel as an example. The present invention is not limited to the in-wheel motor drive device, but is also applicable to a so-called on-board type electric vehicle drive device in which the drive device is provided on a vehicle body. Further, the on-board type may be either a one-motor type in which one electric motor drives left and right wheels and a two-motor type in which two electric motors drive left and right wheels.

  FIG. 11 is a schematic plan view of the electric vehicle 11 on which the in-wheel motor drive device 21 is mounted, and FIG. 12 is a schematic sectional view of the electric vehicle 11 as viewed from the rear.

  As shown in FIG. 11, the electric vehicle 11 includes a chassis 12, a front wheel 13 as a steering wheel, a rear wheel 14 as a driving wheel, and an in-wheel motor driving device 21 that transmits driving force to the rear wheel 14. To equip. As shown in FIG. 12, the rear wheel 14 is housed inside a wheel casing 15 of the chassis 12 and is fixed to a lower portion of the chassis 12 via a suspension 16.

  The suspension device 16 supports the rear wheel 14 with a suspension arm extending left and right, and absorbs vibration received by the rear wheel 14 from the ground by a strut including a coil spring and a shock absorber to suppress the vibration of the chassis 12. A stabilizer is provided at a connection portion between the left and right suspension arms to suppress a tilt of the vehicle body during turning or the like. The suspension device 16 is of an independent suspension type in which the left and right wheels are moved up and down independently in order to improve the ability to follow the unevenness of the road surface and efficiently transmit the driving force of the rear wheel 14 to the road surface.

  In the electric vehicle 11, the in-wheel motor drive device 21 for driving the left and right rear wheels 14 is provided inside the wheel casing 15, thereby eliminating the need to provide a motor, a drive shaft, a differential gear mechanism, and the like on the chassis 12. Therefore, there is an advantage that a large cabin space can be secured and the rotation of the left and right rear wheels 14 can be controlled.

  Before describing the characteristic configuration of this embodiment, the overall configuration of the in-wheel motor driving device 21 will be described with reference to FIG. In the following description, when the in-wheel motor drive device 21 is mounted on the vehicle, the side (left side in FIG. 1) that is closer to the outside in the vehicle width direction is called the outboard side, and the side closer to the center (see FIG. 1). 1 is called the inboard side.

  As shown in FIG. 1, the in-wheel motor drive device 21 includes an electric motor unit A that generates a driving force, a speed reducer unit B that reduces the speed of rotation of the electric motor unit A, and outputs a signal. The main components are a wheel bearing C that transmits output to a rear wheel 14 as a driving wheel.

  The electric motor section A is constituted by an electric motor including a casing 22, a stator 23, a rotor 24, a motor rotation shaft 25, two rolling bearings 40 and 41, and a preload applying structure 70.

  The stator 23 is configured by winding a coil around a magnetic core, and is fixed to the casing 22. In the present embodiment, for convenience of assembly, the casing 22 is divided into three parts in the axial direction, and a casing body 80 having openings at both ends in the axial direction, and an inboard side of the casing body 80 (FIG. 1). An inner cover 81 that closes an opening on the right side) and an outer cover 82 that closes an opening on the outboard side (the left side in FIG. 1) of the casing body 80. The stator 23 is fixed to the inner surface of the casing body 80.

  The rotor 24 is formed of a permanent magnet or the like, and is arranged radially inside the stator 23 with a gap. In the present embodiment, a radial gap type electric motor in which the stator 23 and the rotor 24 face each other with a radial gap therebetween is adopted, but the stator 23 and the rotor 24 face each other with a gap in the axial direction. An axial gap type electric motor may be used.

  A motor rotation shaft 25 is inserted into the inner periphery of the rotor 24. The rotor 24 and the motor rotation shaft 25 are fixed to each other and are configured to rotate integrally. Rolling bearings 40 and 41 are provided at both ends of the motor rotating shaft 25, respectively, and the motor rotating shaft 25 is rotatably supported by the casing 22 by the rolling bearings 40 and 41. In the present embodiment, of the two rolling bearings 40, 41, the rolling bearing 40 on the outboard side (left side in FIG. 1) is provided in the casing body 80, and the rolling bearing 41 on the inboard side (right side in FIG. 1). Are provided on the inner cover 81.

  The preload applying structure 70 includes a wave spring 71 as an elastic member, a protection member 72 that suppresses deterioration of the wave spring 71 due to compression, and an inner cover 81 that houses these. The inner cover 81 is provided with a protection member 72, a wave spring 71, and a cylindrical recess 81 a in which the inboard-side rolling bearing 41 is accommodated. The protection member 72 has an annular ring portion 72a and a cylindrical tube portion 72b that projects in the axial direction from the inner diameter side of the ring portion 72a. The wave spring 71 is a spring member formed by spirally winding a wave-like plate material, and is arranged on the outer periphery of the cylindrical portion 72 b of the protection member 72.

  The ring portion 72a of the protection member 72 is interposed between the wave spring 71 and the outer ring 37 (see FIG. 2) of the inboard-side rolling bearing 41. Since the wave spring 71 is held in the inner cover 81 in a state of being compressed in the axial direction, the wave spring 71 moves the inboard-side rolling bearing 41 in the axial direction via the ring portion 72a (the left side in FIG. 1). To). The ring portion 72a is arranged so as not to come into contact with the inner ring 38, the rolling element 39, and the retainer (not shown) which rotate with the rotation of the motor rotation shaft 25 (so as not to generate sliding resistance). It contacts only the outer ring 37. The axial biasing force (preload) applied to the inboard-side rolling bearing 41 is also applied to the outboard-side rolling bearing 40 via the motor rotation shaft 25. As a result, a preload in the axial direction is applied to the pair of rolling bearings 40 and 41 that support the motor rotation shaft 25, and the vibration of the motor rotation shaft 25 is reduced.

  The outer diameter φK of the wave spring 71 is set so as to effectively apply an axial preload to the outer ring 37 of the rolling bearing 41 and not to apply a shearing force leading to deformation to the ring portion 72a. Desirably, the outer diameter 37 is set smaller than the outer diameter φH of the outer ring 37 and larger than the inner diameter φG of the outer ring 37 (see FIG. 2).

  As shown in FIG. 1, the reduction gear unit B includes a casing 22, an input shaft 27, an intermediate shaft 28, an output shaft 29, and a plurality of rolling bearings that rotatably support these shafts with respect to the casing 22. 42 to 47. The input shaft 27 is integrally and rotatably connected to the motor rotation shaft 25 by spline fitting (including serration fitting). On the other hand, the output shaft 29 is integrally and rotatably connected to a hub wheel 60 constituting a rotation shaft of the wheel bearing portion C by spline fitting (including serration fitting).

  An input gear 30 is provided integrally with the input shaft 27, and an output gear 35 is provided integrally with the output shaft 29. The intermediate shaft 28 is integrally provided with an input-side intermediate gear 31 that meshes with the input gear 30 and an output-side intermediate gear 32 that meshes with the output gear 35. The input gear 30, the input-side intermediate gear 31, the output-side intermediate gear 32, and the output gear 35 are formed by helical gears (external gears). Helical gears are more effective than spur gears in that the number of meshing teeth increases simultaneously and the tooth contact is dispersed, so that noise is quiet and torque fluctuation is small.

  The input shaft 27, the intermediate shaft 28, and the output shaft 29 are arranged in parallel with each other, and the gears provided on these shafts mesh with each other to form a three-shaft, two-stage parallel shaft gear reduction mechanism. The input shaft 27, the intermediate shaft 28, and the output shaft 29 are connected to the respective rolling bearings 42, 44, 46 on the inboard side (the right side in FIG. 1) provided on the casing body 80, and the outer cover 82 provided on the outer cover 82. It is rotatably supported by each rolling bearing 43, 45, 47 on the board side (left side in FIG. 1). As the rolling bearings 42 to 47 for supporting the shafts of the reduction gear unit B and the pair of rolling bearings 40 and 41 for supporting the motor rotating shaft 25, bearings capable of receiving both a radial load and a thrust load, For example, it is preferable to use a deep groove ball bearing.

  As shown in FIG. 1, the wheel bearing portion C is formed of an inner ring rotating type wheel bearing. The wheel bearing portion C is a double-row angular ball bearing mainly including an inner member 61 including a hub wheel 60 and a pair of inner rings 52, an outer ring 53, a plurality of balls 56, and a retainer (not shown). It is. An inner raceway surface 54 is formed on the outer periphery of each inner ring 52. On the other hand, double rows of outer raceway surfaces 55 are formed on the inner periphery of the outer race 53 in correspondence with the inner raceway surfaces 54 of the respective inner races 52. Balls 56 are arranged to be rollable between the inner raceway surface 54 and the outer raceway surface 55 facing each other. The outer ring 53 is fastened and fixed to a mounting portion of the casing 22 (outer cover 82) by bolts or the like.

  A flange portion 60a for mounting a wheel is formed on the outer periphery of the hub wheel 60 on the outboard side. Although not shown, a brake disc and a wheel are mounted on the wheel mounting flange portion 60a. On the other hand, the inner ring 52 is fitted to the small-diameter stepped portion on the inboard side of the hub wheel 60, and the caulked portion 60 b of the hub wheel 60 is pressed against the inner ring 52. The caulked portion 60b is formed by caulking the inboard end of the hub wheel 60 after the inner ring 52 is fitted to the hub wheel 60. The formation of the caulked portion 60b positions the inner ring 52 in the axial direction and applies a preload to the wheel bearing.

  In the in-wheel motor drive device 21 according to the present embodiment, when the motor rotation shaft 25 rotates, the input shaft 27 rotates integrally therewith, and the rotation movement is caused by the input gear 30 having an input side having more teeth than the input gear 30. The speed is reduced by being transmitted to the intermediate gear 31. Then, the rotational motion is further reduced by being transmitted from the output side intermediate gear 32 to the output gear 35 having more teeth.

  As described above, in the in-wheel motor drive device 21 according to the present embodiment, the rotational motion of the motor rotation shaft 25 is reduced in two steps by the reduction mechanism portion B, so that the amplified torque is transmitted to the rear wheel 14. It is possible to use a small electric motor of low torque and high rotation type. For example, when the reduction ratio of the speed reducer unit B is 11, the electric motor can be downsized by using an electric motor that rotates at a high speed of about ten thousand thousands of rotations per minute. As a result, a compact in-wheel motor driving device can be realized, and an electric vehicle having excellent running stability and NVH characteristics while suppressing unsprung weight can be obtained.

  The overall configuration and operation of the in-wheel motor drive device 21 according to the present embodiment are as described above. Next, a point that the present embodiment is excellent in assemblability will be described.

  FIG. 2 is an enlarged cross-sectional view showing the preload applying structure 70 according to the present embodiment and a peripheral portion thereof, and FIG. 3 is a perspective view of the protective member 72 and the inner cover 81.

  As shown in FIGS. 2 and 3, the protection member 72 includes a ring portion 72 a, a cylindrical portion 72 b protruding in the axial direction from the inner diameter side of the ring portion 72 a, and an arc-shaped protruding outer diameter direction from the ring portion 72 a. And a projection 72c. In the present embodiment, three projections 72c are provided at equal intervals in the circumferential direction of the ring 72a, but the number of the projections 72c may be two or four or more. A hook 72d for hooking a tool or the like is provided on the inner peripheral surface of the cylindrical portion 72b so as to extend in the axial direction. In the present embodiment, two hook portions 72d are provided at equal intervals in the circumferential direction of the cylindrical portion 72b, but the number of hook portions 72d may be one, or may be three or more.

  On the other hand, the concave portion 81a of the inner cover 81 has a plurality of axial grooves 91 extending in the axial direction from the concave opening end 81b toward the concave bottom surface 81c, and a ring extending in the circumferential direction on the deeper side than the axial groove 91. And a circumferential groove 92 are provided. Three axial grooves 91 are provided at regular intervals in the circumferential direction of the concave portion 81a, corresponding to the respective projecting portions 72c of the protection member 72. Similarly to the protrusion 72c, the number of the axial grooves 91 is not limited to three, but may be two or four or more. The circumferential groove 92 communicates with each axial groove 91 on the concave bottom surface 81 c side of each axial groove 91.

  Subsequently, a method of assembling the preload applying structure 70 according to the present embodiment will be described.

  First, as shown in FIG. 4, the wave spring 71 is mounted on the outer periphery of the cylindrical portion 72b of the protection member 72. Next, the protective member 72 and the inner cover 81 are aligned with each other so that each protrusion 72c of the protective member 72 corresponds to the axial groove 91 of the inner cover 81 (see FIG. 3). It is inserted into the recess 81 of the inner cover 81 together with the wave spring 71. At this time, as shown in FIG. 5, when the protrusion 72c moves along the axial groove 91, the protection member 72 and the wave spring 71 are guided in the axial direction in the recess 81a. Note that the outer diameter of the projection 72c is set slightly smaller than the inner diameter of the axial groove 91 so that the protection member 72 and the wave spring 71 can smoothly move in the axial direction at this time. The outer diameter of each of 71 is set slightly smaller than the inner diameter of concave portion 81 a excluding axial groove 91 and circumferential groove 92.

  Then, as shown in FIG. 6, when the protrusion 72 c moves to the inner side of the axial groove 91 and reaches the position of the circumferential groove 92, the protection member 72 is rotated in the circumferential direction, and The circumferential phase with the axial groove 91 is shifted. As a result, the protrusion 72c is arranged so as to face the wall surface 92a on the outboard side (the concave opening end 81b side) of the circumferential groove 92. The outer diameter of the projection 72c is set slightly smaller than the inner diameter of the circumferential groove 92 so that the protection member 72 can rotate smoothly in the circumferential direction at this time. Further, by hooking a tool or the like on the hook portion 72d provided on the protection member 72, the protection member 72 can be easily rotated in the circumferential groove 92.

  As shown in FIG. 6, by shifting the circumferential phase of the protrusion 72c and the axial groove 91, the protrusion 72c and the wall surface 92a on the outboard side of the circumferential groove 92 are axially engaged. Therefore, the protection member 72 is prevented from moving toward the concave opening end 81b. This prevents the protection member 72 and the wave spring 71 from falling off or falling down from the concave portion 81a. In this state, since the wave spring 71 is compressed in the axial direction between the ring portion 72a and the concave bottom surface 81c, the projection 72c is moved by the urging force of the wave spring 71 so that the protrusion 72c is located on the outboard side of the circumferential groove 92. The state is pressed against the wall surface 92a. Accordingly, the protection member 72 is held so as not to rotate in the circumferential direction by the frictional force generated between the protrusion 72c and the wall surface 92a on the outboard side, so that the circumferential direction between the protrusion 72c and the axial groove 91 is maintained. The falling and falling of the protection member 72 and the wave spring 71 due to the coincidence of the phases are prevented.

  The procedure for assembling components is not limited to the above procedure, and can be changed as appropriate. For example, after inserting only the wave spring 71 into the inner cover 81, the protection member 72 may be inserted into the inner cover 81 first.

  As described above, in the present embodiment, the engagement between the projection 72c and the circumferential groove 92 prevents the wave spring 71 and the protection member 72 from falling off or falling down with respect to the inner cover 81. The member 72 and the inner cover 81 can be handled as an integrated unit.

  By the way, in the configuration including the radial gap type electric motor as shown in FIG. 1, there is a situation that it is difficult to perform an assembling operation in which the opening of the casing (the casing main body 80) is turned sideways. In other words, when the casing is turned sideways and the rotor shaft with the rotor is to be inserted horizontally into the inner periphery of the stator, the motor shaft tends to tilt due to gravity. It is difficult to insert the shaft. If the motor rotation shaft is tilted, the stator and the rotor will be attracted by magnetic force, which hinders the assembling work. Therefore, in the configuration including the radial gap type electric motor, as shown in FIG. 7, the rotor 24 and the rolling bearings 40 and 41 are mounted with the opening of the casing body 80 to which the stator 23 is assembled facing upward. It is desirable to insert the fixed motor rotation shaft 25 vertically. On the other hand, if an assembling method in which the opening of the casing is directed upward is adopted, it is necessary to mount the inner cover 81 with the concave opening end 81b facing downward as shown in FIG. There is a problem that the wave spring 71 and the protection member 72 fall off from the concave portion 81a of the 81.

  On the other hand, according to the configuration according to the present embodiment, by attaching the protection member 72 and the wave spring 71 to the inner cover 81 in the above-described procedure, it is possible to prevent them from dropping and falling. is there. Therefore, as shown in FIG. 8, the wave spring 71 and the protection member 72 do not fall off the inner cover 81 even when the concave opening end 81 b of the inner cover 81 is turned downward. Accordingly, even in a configuration including a radial gap type electric motor in which the method of assembling the motor rotation shaft 25 vertically is preferable, the concave opening end 81 b faces downward with the protection member 72 and the wave spring 71 attached to the inner cover 81. And the workability of assembly is improved.

  When the assembly of the inner cover 81 to the casing body 80 is completed, the protection member 72 comes into contact with the inboard-side rolling bearing 41 as shown in FIG. It is pushed to the right in FIG. Thereby, the contact (engagement) between the protrusion 72c and the wall surface 92a on the outboard side of the circumferential groove 92 is released, and the protrusion 72c is brought into a non-contact state with the wall surface 92a on the outboard side. In this state, the protruding portion 72c is also held in a non-contact state with the wall surface 92b on the inboard side (the concave bottom surface 81c side) of the circumferential groove 92. That is, the axial width W1 of the circumferential groove 92 is larger than the axial width W2 of the protrusion 72c, and the protrusion 72c is held so that the axial movement in the circumferential groove 92 is allowed to some extent. . As described above, in the state after the assembly is completed, the projections 72c are in a non-contact state with the wall surfaces 92a, 92b on both sides of the circumferential groove 92, so that the wave springs are in contact with the rolling bearings 40, 41. An axial constant pressure preload by 71 is applied.

  In this state, the motor rotating shaft 25 is held at a predetermined axial position (the position shown in FIG. 2), and the cylindrical portion 72b of the protection member 72 is spaced from the concave bottom surface 81c of the inner cover 81 by a gap δ. In a non-contact state. However, as shown in FIG. 9, when the motor rotation shaft 25 receives an axial force due to vibration or the like during traveling of the vehicle and the motor rotation shaft 25 is displaced in the axial direction against the urging force of the wave spring 71, as shown in FIG. The cylindrical portion 72b contacts the concave bottom surface 81c. At this time, since the cylindrical portion 72b contacts the concave bottom surface 81c before the wave spring 71 is completely compressed in the axial direction, the fatigue caused by the compression of the wave spring 71 is suppressed.

  Generally, in order to effectively suppress the fatigue of the spring member, it is preferable to set the amount of expansion and contraction of the spring member to within 80% of a value obtained by subtracting the contact length from the free length of the spring member. Further, since the amount of expansion and contraction of the wave spring 71 is determined by the axial length T (see FIG. 9) of the cylindrical portion 72b, the free length F and the close contact length U of the spring member are used for the cylindrical portion 72b. The axial length T is preferably set to a value that satisfies the following expression (1).

  T> 0.2 * F + 0.8 * U (1)

  Further, as shown in FIG. 9, in the present embodiment, the projection 72c is configured not to contact the inboard wall surface 92b of the circumferential groove 92 in a state where the cylindrical portion 72b is in contact with the concave bottom surface 81c. Have been. Since the protrusion 72c is configured not to contact the inboard side wall surface 92b, an axial load acts between the protrusion 72c and the inboard side wall surface 92b. Can be avoided, and deformation and damage of the projection 72c and the circumferential groove 92 can be prevented.

  Subsequently, a configuration according to another embodiment of the present invention shown in FIG. 10 will be described.

  In the embodiment shown in FIG. 10, unlike the above-described embodiment, a wave spring 71 is arranged on the inner periphery of a protection member 72. That is, in the present embodiment, the cylindrical portion 72b of the protection member 72 is provided on the outer diameter side of the ring portion 72a, and the wave spring 71 is disposed on the inner periphery of the cylindrical portion 72b. Otherwise, the configuration is the same as that of the above-described embodiment.

  In the embodiment shown in FIG. 10, similarly to the above-described embodiment, the wave spring 71 is attached to the protection member 72, and the protection member 72 is inserted along the axial groove 91 of the inner cover 81, and the circumferential groove is formed. By rotating along the direction 92, it is possible to prevent the protection member 72 and the wave spring 71 from falling off or falling down with respect to the inner cover 81.

  As described above, according to the present invention, since the protective member and the elastic member can be prevented from falling off or falling down with respect to the casing, these components can be handled as an integrated assembly unit, and the assembly workability can be improved. Is improved. In addition, the variety of options in the mounting direction increases the degree of freedom in product design. In particular, in a radial gap type electric motor having a restriction in the mounting direction, by adopting the configuration of the present invention, a great improvement in the mounting workability can be expected. Further, the present invention is applicable not only to the radial gap type electric motor but also to an axial gap type electric motor and other electric motors, and improves the assembling workability in these electric motors. It is possible.

  Further, the present invention is not limited to the above-described embodiment at all, and it goes without saying that the present invention can be implemented in various other forms without departing from the gist of the present invention.

  For example, the circumferential groove 92 is not limited to the annular groove provided continuously over the entire circumference of the concave portion 81a as in the above-described embodiment, but may be a partial arc-shaped provided over a part of the circumferential direction. Groove may be used. In addition, one of the ring portion 72a and the cylindrical portion 72b of the protection member 72 may have a configuration in which a portion in the circumferential direction is divided, for example, having an axial slit. Further, the hook portion 72d for hooking a tool or the like when rotating the protection member 72 is not limited to a concave shape, but may be formed in a convex shape. Further, instead of the wave spring 71, another spiral or annular spring member such as a coil spring or a wave washer can be used.

  In the above-described embodiment, the preload applying structure 70 is provided only on one of the rolling bearings 41 of the pair of rolling bearings 40 and 41 that support the motor rotating shaft 25. May be provided with a preload applying structure 70 according to the present invention, and an axial preload may be individually applied to both the rolling bearings 40 and 41. Furthermore, the present invention is not limited to the structure for applying a preload to the motor support bearing in the electric motor, but is also applicable to the structure for applying a preload to the support bearing in the speed reducer.

Reference Signs List 21 in-wheel motor drive device 22 casing 23 stator 24 rotor 25 motor rotation shaft 40 rolling bearing 41 rolling bearing 70 preload applying structure 71 wave spring (elastic member)
72 Protective member 72a Ring part 72b Tube part 72c Projection part 72d Hook part 81a Recess 81b Recess opening end 81c Recess bottom 91 Axial groove 92 Circumferential groove 92a Outboard side wall surface (wall surface on the concave opening end side)
92b Inboard side wall (recess bottom side)
A Electric motor section B Reduction gear section C Wheel bearing section

Claims (7)

An elastic member that urges a bearing that supports a motor rotation shaft of the electric motor to apply a preload in the axial direction; a protection member that prevents the elastic member from being completely compressed in the axial direction; A casing provided with a recess in which the protection member is accommodated, and a preload applying structure for the motor support bearing,
A ring portion disposed between the elastic member and the bearing; a tubular portion projecting in the axial direction from the ring portion and having the elastic member disposed on an outer or inner periphery thereof; And a projection protruding in the outer diameter direction from the portion,
The concave portion has an axial groove provided in the axial direction from the concave portion opening end toward the concave bottom surface, and a circumferential groove provided in the circumferential direction so as to communicate with the axial groove on the concave bottom surface side. Has,
The projecting portion is configured to be movable in the axial direction along the axial groove, and is configured to be movable in the circumferential direction along the circumferential groove. Grant structure.   2. The preload applying structure for a motor support bearing according to claim 1, wherein the projection does not contact a wall surface of the circumferential groove on the concave bottom surface side in a state where the cylindrical portion contacts the concave bottom surface. 3.   The preload applying structure for a motor support bearing according to claim 1, wherein a convex or concave hook portion is provided on an inner periphery of the protection member.   4. The motor support bearing preload applying structure according to claim 1, wherein the elastic member is an annular or spiral spring member. 5. A casing, a stator fixed to the casing, a motor rotating shaft, a rotor that rotates integrally with the motor rotating shaft, a bearing that rotatably supports the motor rotating shaft with respect to the casing, and a bearing. An electric motor having a preload applying structure for applying an axial preload to the electric motor,
An electric motor, wherein the preload applying structure according to any one of claims 1 to 4 is used as the preload applying structure.   6. The electric motor according to claim 5, wherein the preload applying structure is provided on both ends of the motor rotation shaft, and individually applies a preload to a pair of bearings supporting the motor rotation shaft. 7. An in-wheel motor drive device including an electric motor unit, a wheel bearing unit, and a speed reducer unit that transmits the rotation of the electric motor unit to the wheel bearing unit by reducing the speed.
An in-wheel motor drive device, wherein the electric motor unit includes the electric motor according to claim 5.

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