JP2008044538A - In-wheel motor drive unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an in-wheel motor drive unit further improved in vehicle riding comfort and driving stability. <P>SOLUTION: This in-wheel motor drive unit 21 includes a casing 22, a motor portion A, a deceleration portion B, a wheel hub 32 and a wheel hub bearing 33. The wheel hub bearing 33 is a ball bearing made of ceramic and having a plurality of rollers 33e. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an in-wheel motor drive device in which an output shaft of an electric motor and a wheel hub are coaxially connected via a reduction gear.

  A conventional in-wheel motor drive device is described in, for example, Japanese Patent Application Laid-Open No. 2005-7914 (Patent Document 1). The in-wheel motor drive device described in the publication discloses a motor that generates a driving force, a wheel hub that connects a tire, and a motor and a wheel hub that decelerate the rotation of the rotor of the motor and transmit it to the tire. A reduction gear. This reduction gear employs a parallel shaft gear mechanism formed by combining a plurality of gears having different numbers of teeth.

Such an in-wheel motor drive device in which the output shaft of the electric motor and the wheel hub are coaxially connected via a speed reducer eliminates the need for a large-scale power transmission mechanism such as a propeller shaft and a differential. It is attracting attention in terms of weight reduction and compactness.
JP 2005-7914 A Japanese Patent Laid-Open No. 5-332401 (Fig. 1-3)

  On the other hand, by attaching an in-wheel motor drive device including a motor and a speed reducer to each drive wheel, the unsprung weight of the vehicle increases. This causes the ride comfort of the vehicle to deteriorate. In addition, since the moment load generated during turning is increased as the unsprung weight increases, there is also a problem that traveling stability is lowered.

  Accordingly, an object of the present invention is to provide an in-wheel motor drive device that further improves the riding comfort and running stability of an automobile.

  An in-wheel motor drive device according to the present invention includes a casing, a motor unit that rotationally drives the motor-side rotating member, a speed-reducing unit that decelerates the rotation of the motor-side rotating member and transmits the rotation to the wheel-side rotating member, and wheel-side rotation A wheel hub fixedly connected to the member, and a wheel hub bearing that rotatably supports the wheel hub with respect to the casing. The wheel hub bearing is a rolling bearing having a plurality of rolling elements formed of ceramics.

  By adopting the in-wheel motor drive device with the above configuration in an automobile, it is not necessary to provide a motor, a drive shaft, a differential gear mechanism, etc. on the chassis, so that a large cabin space can be secured and the left and right drive wheels can be secured. Each rotation can be controlled.

  In addition, since the rolling elements formed of ceramics are lighter than conventional rolling elements formed of bearing steel or the like, the entire in-wheel motor drive device can be reduced in weight by adopting such a configuration. . As a result, the unsprung weight of an automobile employing this in-wheel motor drive device can be reduced, and an automobile having a good ride comfort can be obtained.

Preferably, the wheel hub bearing is a double row rolling bearing having a double row raceway surface. If a PCD (Pitch Circle Diameter) of a plurality of rolling elements arranged on the track surface on the outboard side is d ₁ and a PCD of the plurality of rolling elements arranged on the track surface on the inboard side is d ₂ , d _1> satisfy the _{d 2.}

  By setting it as the said structure, the rigidity of a wheel hub bearing improves. Moreover, since the number of rolling elements that can be accommodated increases by increasing the PCD, the load capacity on the outboard side also increases. In particular, since the moment load generated when the vehicle turns is supported on the outboard side of the wheel hub bearing, the vehicle having excellent running stability can be obtained with the above configuration.

  Preferably, the motor side rotation member has an eccentric part. The speed reduction portion is rotatably held by the eccentric portion and revolves around the rotation axis as the motor side rotation member rotates, and the casing is fixed to the outer periphery of the revolution member. The outer peripheral engagement member that engages with the part to cause the rotation of the revolving member, and the rotation of the revolving member is converted into a rotation about the rotation axis of the motor-side rotating member to form a wheel-side rotating member. A motion conversion mechanism for transmission.

  By adopting a compact speed reducing portion that has a high speed reduction ratio as described above, it is possible to transmit sufficient torque to the drive wheels even when the motor portion has a low torque. As a result, a lightweight and small in-wheel motor drive device can be obtained.

  According to the present invention, the in-wheel motor drive device can be reduced in weight by employing the ceramic rolling element for the wheel hub bearing. Further, by setting the PCD on the outboard side of the wheel hub bearing to be larger than the PCD on the inboard side, the rigidity of the wheel hub bearing is improved and the load capacity on the outboard side is also increased.

  With reference to FIG. 5 and FIG. 6, the electric vehicle 11 provided with the in-wheel motor drive device which concerns on one Embodiment of this invention is demonstrated. 5 is a plan view of the electric vehicle 11, and FIG. 6 is a view of the electric vehicle 11 as viewed from the rear.

  Referring to FIG. 5, an electric vehicle 11 includes an in-wheel motor drive device that transmits driving force to a chassis 12, front wheels 13 as steering wheels, rear wheels 14 as drive wheels, and left and right rear wheels 14. 15. Referring to FIG. 6, the rear wheel 14 is accommodated in the wheel housing 12a of the chassis 12 and is fixed to the lower portion of the chassis 12 via a suspension device (suspension) 12b.

  The suspension device 12b supports the rear wheel 14 by a suspension arm extending to the left and right, and suppresses vibration of the chassis 12 by absorbing vibration received by the rear wheel 14 from the ground by a strut including a coil spring and a shock absorber. Furthermore, a stabilizer that suppresses the inclination of the vehicle body when turning is provided at the connecting portion of the left and right suspension arms. The suspension device 12b is an independent suspension type in which the left and right wheels can be moved up and down independently in order to improve the followability to the road surface unevenness and efficiently transmit the driving force of the driving wheels to the road surface. Is desirable.

  The electric vehicle 11 needs to be provided with a motor, a drive shaft, a differential gear mechanism, and the like on the chassis 12 by providing an in-wheel motor drive device 15 for driving the left and right rear wheels 14 inside the wheel housing 12a. This eliminates the need to secure a wide cabin space and control the rotation of the left and right drive wheels.

  On the other hand, in order to improve the running stability of the electric vehicle 11, it is necessary to suppress the unsprung weight. In addition, in-wheel motor drive device 15 is required to be reduced in size in order to secure a wider cabin space. Therefore, an in-wheel motor drive device 21 according to an embodiment of the present invention as shown in FIG.

  With reference to FIGS. 1-4, the in-wheel motor drive device 21 which concerns on one Embodiment of this invention is demonstrated. 1 is a schematic cross-sectional view of the in-wheel motor drive device 21, FIG. 2 is a cross-sectional view taken along II-II in FIG. 1, FIG. 3 is an enlarged view around the eccentric portions 25a and 25b in FIG. These are the elements on larger scale of the wheel hub bearing part C. FIG.

  First, referring to FIG. 1, an in-wheel motor drive device 21 includes a motor unit A that generates a driving force, a deceleration unit B that decelerates and outputs the rotation of the motor unit A, and an output from the deceleration unit B. A wheel hub bearing portion C for transmitting to the drive wheel 14 is provided, and the motor portion A and the speed reduction portion B are accommodated in the casing 22 and attached to the wheel housing 12a of the electric vehicle 11 as shown in FIG.

  The motor unit A includes a stator 23 fixed to the casing 22, a rotor 24 disposed at a position facing the inner side of the stator 23 with an axial clearance, and a rotor 24 fixedly connected to the inner side of the rotor 24. It is an axial gap motor provided with the motor side rotation member 25 which rotates integrally. Further, a sealing member 34 is provided on the end surface of the motor part A opposite to the speed reduction part B in order to prevent dust from entering the motor part A.

  The rotor 24 includes a flange-shaped rotor portion 24 a and a cylindrical hollow portion 24 b, and is rotatably supported with respect to the casing 22 by a double row rolling bearing 35. In addition, a sealing member 36 is provided at a boundary portion between the casing 22 and the rotor 24 in order to prevent the lubricant encapsulated in the speed reduction portion B from flowing into the motor portion A.

  The motor-side rotating member 25 is arranged from the motor part A through the speed reducing part B to the hollow part 28b of the wheel side rotating member 28, and has eccentric parts 25a and 25b in the speed reducing part B. One end of the motor-side rotating member 25 is fitted to the rotor 24, and is supported by rolling bearings 37 and 38 at both ends of the speed reduction unit B. Further, the two eccentric portions 25a and 25b are provided with a 180 ° phase change in order to cancel the centrifugal force due to the eccentric motion.

  The speed reduction part B is rotatably supported with respect to the casing 22 by curved plates 26a, 26b as revolving members held rotatably by the eccentric parts 25a, 25b, and needle roller bearings 27c, and the curved plates 26a, 26b. A plurality of outer pins 27 as outer peripheral engaging members that engage with the outer peripheral portion of the outer peripheral portion, a motion conversion mechanism that transmits the rotational motion of the curved plates 26 a and 26 b to the wheel-side rotating member 28, and a counterweight 29.

  The wheel side rotation member 28 has a flange portion 28a and a cylindrical hollow portion 28b. The end face of the flange portion 28a has holes for fixing the inner pins 31 at equal intervals on the circumference around the rotation axis of the wheel side rotation member 28. The outer diameter surface of the hollow portion 28b is fitted with the inner diameter surface of the wheel hub 32, and the inner diameter surface of the hollow portion 28b is formed by the rotation axis of the motor side rotation member 25 and the rotation axis of the wheel side rotation member 28. The motor side rotation member 25 is rotatably supported by the rolling bearing 38 so as to coincide with each other. In this embodiment, a needle roller bearing is adopted as the rolling bearing 38 from the viewpoint of reducing the radial dimension of the wheel hub bearing portion C.

  Referring to FIG. 2, the curved plate 26 a has a plurality of corrugations composed of trochoidal curves such as epitrochoids on the outer peripheral portion, 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. The through hole 30b is provided at the center of the curved plate 26a and passes through the eccentric portion 25a.

  The curved plate 26a is rotatably supported by the rolling bearing 39 with respect to the eccentric portion 25a. This rolling bearing 39 is fitted to the eccentric portion 25a, an inner ring 39a having an inner raceway surface on the outer diameter surface, an outer ring 39b fitted to the inner wall surface of the through hole 30b and having an outer raceway surface on the inner diameter surface, It is a deep groove ball bearing provided with balls 39c as a plurality of rolling elements disposed between an inner ring 39a and an outer ring 39b, and a cage (not shown) that holds the plurality of balls 39c.

  The outer pins 27 are arranged at equal intervals on a circumferential track centering on the rotation axis of the motor side rotation member 25. This coincides with the revolution trajectory of the curved plates 26a and 26b. Therefore, when the curved plates 26a and 26b revolve, the curved waveform and the outer pin 27 engage with each other, and the curved plates 26a and 26b rotate. Cause it to occur. Further, in order to reduce the contact resistance with the curved plates 26a, 26b, a needle roller bearing 27a is provided at a position in contact with the outer peripheral surface of the curved plates 26a, 26b.

  The counterweight 29 has a disc shape and has a through-hole that fits with the motor-side rotating member 25 at a position off the center. Each counterweight 29 is arranged to cancel the couple generated by the rotation of the curved plates 26a and 26b. Arranged on the outside of 25a and 25b with a 180 ° phase change from the eccentric part.

  Here, as shown in FIG. 3, the curved plates 26a and 26b and the counterweight 29 have a center point G between the two curved plates 26a and 26b, and a center point G and the centers of the curved plates 26a and 26b. The distance between the center point G and each counterweight 29 is L2, the mass of the curved plates 26a and 26b is m1, and the mass of the counterweight 29 is m2. Are ε1 and ε2, respectively, such that L1 × m1 × ε1 = L2 × m2 × ε2.

  The motion conversion mechanism includes a plurality of inner pins 31 held by the wheel-side rotating member 28 and through holes 30a provided in the curved plates 26a and 26b. The inner pins 31 are provided at equal intervals on a circumferential track centering on the rotational axis of the wheel-side rotating member 28, one end is fixed to the wheel-side rotating member 28, and the other end is from a through hole 30 a. A retaining portion 31b is provided to prevent the slipping out. Further, in order to reduce the contact resistance with the curved plates 26a and 26b, needle roller bearings 31a are provided at positions where the curved plates 26a and 26b come into contact with the inner wall surfaces of the through holes 30a. 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 dimension of the through hole 30a is predetermined from the outer diameter dimension of the inner pin 31 (the maximum outer diameter including the needle roller bearing 31a). The minute is set.

  The outer diameter of the inner pin 31 is smaller than the inner diameter of the through hole 30a, and the inner pin 31 and the inner peripheral surface of the through hole 30a rotate while repeating a contact state and a non-contact state. From the viewpoint of smoothly transmitting the rotation to the drive wheel 14, it is desirable to provide a plurality of inner pins 31.

  The wheel hub bearing portion C includes a wheel hub 32 fixedly connected to the wheel-side rotating member 28 and a wheel hub bearing 33 that holds the wheel hub 32 rotatably with respect to the casing 22. The wheel hub 32 has a cylindrical hollow portion 32a and a flange portion 32b. The wheel-side rotating member 28 is fitted to the inner diameter surface of the hollow portion 32a, and the drive wheel 14 (not shown) is fixedly connected to the flange portion 32b by a bolt 32c. In addition, a sealing member 32d is provided at the opening of the hollow portion 32a in order to prevent dust from entering the in-wheel motor drive device 21 and to prevent the lubricant from flowing out.

  The wheel hub bearing 33 is a double-row angular ball bearing that employs balls 33e as rolling elements. As the raceway surfaces of the balls 33e, a first outer raceway surface 33a (right side in the figure) and a second outer raceway surface 33b (left side in the figure) are provided on the inner diameter surface of the outer member 22a. A first inner raceway surface 33c facing the surface 33a is provided on the outer diameter surface of the wheel-side rotating member 28, and a second inner raceway surface 33d facing the second outer raceway surface 33b is provided on the outer diameter surface of the wheel hub 32, respectively. ing. The balls 33e are formed between the first outer raceway surface 33a and the first inner raceway surface 33c (hereinafter referred to as “first raceway surface”), and between the second outer raceway surface 33b and the second inner raceway surface 33d. A plurality of them are arranged between each other (hereinafter referred to as “second raceway surface”). The wheel hub bearing 33 includes a retainer 33f that holds the balls 33e in the left and right rows, and a sealing member 33g that prevents the lubricant enclosed in the bearing from flowing out and dust from the outside. . Further, the outer member 22 a having the first and second outer ring raceway surfaces 33 a and 33 b is fixed to the casing 22 by bolts 22 b from the viewpoint of the incorporation of the wheel hub bearing 33.

  The in-wheel motor drive device 21 configured as described above has the outer raceway surfaces 33a and 33b of the wheel hub bearing 33 provided on the outer member 22a, and the inner raceway surfaces 33c and 33d provided on the wheel side rotation member 28 and the wheel hub 32. The outer ring and inner ring as components of the bearing can be omitted. As a result, the radial dimension of the wheel hub bearing 33 can be reduced. Or when making the dimension of radial direction the same dimension, since the diameter of the ball | bowl 33e can be enlarged, it becomes possible to increase load capacity. Furthermore, the improvement effect of the assemblability by reducing the number of parts can also be expected.

  The ball 33e is formed of ceramics. Ceramics are excellent in high strength, heat resistance, wear resistance, and the like, and are lighter than conventional rolling element materials such as bearing steel. Therefore, the wheel hub bearing 33 can be reduced in weight by using the ceramic balls 33e. Thereby, since the unsprung weight of the electric vehicle 11 can be reduced, the riding comfort of the electric vehicle 11 is improved.

Further, referring to FIG. 4, the PCD of the second raceway surface located on the outboard side (pointing to the side closer to the wheel) is d ₁ , and the _first PCD located on the inboard side (pointing to the side far from the wheel). When the PCD of the raceway surface is d ₂ , d ₁ > d ₂ is satisfied.

  By setting it as the said structure, the rigidity of the wheel hub bearing 33 further improves. Further, since the distance l (referred to as “ball pitch”) between the balls 33e arranged on the first and second raceway surfaces is increased, the wheel hub 32 can be stably supported.

  Furthermore, since the second raceway surface can accommodate more balls 33e than the first raceway surface, the load capacity on the outboard side can be improved. The moment load generated when the electric vehicle 11 turns is supported mainly on the outboard side of the wheel hub bearing 33. Therefore, by improving the load capacity of this portion, the electric vehicle 11 having excellent running stability can be obtained.

  In addition, although the example in which the ball | bowl 33e with the same diameter was arrange | positioned was shown on the 1st and 2nd track surface, you may arrange | position the ball | bowl from which a magnitude | size differs in a right and left track surface, without restricting to this. . For example, the rolling elements on the first raceway surface may be larger than the rolling elements on the second raceway surface, or the rolling elements on the second raceway surface may be larger than the rolling elements on the first raceway surface.

  In the in-wheel motor drive device 21 configured as described above, the outer diameter surface of the wheel-side rotating member 28 and the inner diameter surface of the wheel hub 32 are plastically coupled by expanding and caulking the wheel-side rotating member 28.

  As a method of assembling the wheel hub bearing portion C, first, the cage 33f that accommodates the balls 33e is placed on the first inner raceway surface 33c provided on the wheel-side rotating member 28. Next, the outer member 22a is disposed at a position where the first outer raceway surface 33a properly contacts the ball 33e, and is fixed to the casing 22 by a bolt 22b. Next, the wheel hub 32 is moved to the wheel-side rotating member 28 so that the ball 33e properly contacts the second outer raceway surface 33b in a state where the retainer 33f containing the ball 33e is placed on the second inner raceway surface 33d. Fit into.

  In this state, the wheel-side rotating member 28 and the wheel hub 32 are merely fixed by fitting, so that when the large moment load is applied when the electric vehicle 11 turns, the wheel hub 32 is axially moved. There is a risk of slipping. This causes a rotation failure of the wheel hub bearing 33, and the wheel hub 32 cannot be stably held.

  Therefore, the outer diameter surface of the wheel side rotation member 28 and the inner diameter surface of the wheel hub 32 are plastically coupled by expanding and caulking. Specifically, the in-wheel motor drive device 21 is fixed, and a crimping jig (not shown) having an outer diameter slightly larger than the inner diameter of the hollow portion 28b of the wheel-side rotating member 28 is press-fitted into the hollow portion 28b. To do.

  As a result, the wheel side rotation member 28 and the wheel hub 32 are plastically coupled at the plastic coupling portion 40. By fixedly connecting the wheel-side rotating member 28 and the wheel hub 32 by the above method, the coupling strength can be significantly increased as compared with the case of fixing by fitting. Thereby, the wheel hub 32 can be stably held.

  In the above embodiment, the motor-side rotating member 25 is supported by interposing the rolling bearing 38 in the hollow portion 28b of the wheel-side rotating member 28. However, a part of the wheel hub 32 is used as the wheel-side rotating member 28. In this case, a rolling bearing is disposed in the hollow portion 32a of the wheel hub 32 to support the motor-side rotating member 25. Become.

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

  The motor unit A receives, for example, an electromagnetic force generated by supplying an alternating current to the coil of the stator 23, and the rotor 24 constituted by a permanent magnet or a direct current electromagnet rotates. At this time, the rotor 24 rotates at a higher speed as a higher frequency voltage is applied to the coil.

  Thereby, when the motor side rotation member 25 connected to the rotor 24 rotates, the curved plates 26 a and 26 b revolve around the rotation axis of the motor side rotation member 25. At this time, the outer pin 27 engages with the curved waveform of the curved plates 26 a and 26 b to cause the curved plates 26 a and 26 b to rotate in the direction opposite to the rotation of the motor-side rotating member 25.

  The inner pin 31 inserted through the through hole 30a comes into contact with the inner wall surface of the through hole 30a as the curved plates 26a and 26b rotate. At this time, since the inner diameter of the through hole 30a is set larger than the outer diameter of the inner pin 31, the inner pin 31 and the inner wall surface of the through hole 30a are in contact with each other while repeating a contact state and a non-contact state. Exercise. As a result, the revolving motion 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 wheel-side rotating member 28.

  At this time, since the rotation of the motor-side rotating member 25 is decelerated by the speed reducing portion B and transmitted to the wheel-side rotating member 28, it is necessary for the drive wheel 14 even when the low torque, high rotation type motor portion A is adopted. It is possible to transmit an appropriate torque.

  By employing the in-wheel motor drive device 21 according to the above embodiment in the electric vehicle 11, the unsprung weight can be suppressed. As a result, the electric vehicle 11 having excellent running stability can be obtained.

Note that the reduction ratio of the speed reduction unit B having the above-described configuration 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. The 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.

  In this way, by adopting the speed reduction unit B that can obtain a large reduction ratio without using a multi-stage configuration, a compact and high reduction ratio in-wheel motor drive device can be obtained. Further, by providing the needle roller bearings 27a and 31a at positions where they contact the curved plates 26a and 26b of the outer pin 27 and the inner pin 31, the contact resistance is reduced, so that the transmission efficiency of the speed reduction portion B is improved. .

  In the above-described embodiment, two curved plates 26a and 26b of the deceleration portion B are provided with 180 ° phase shifts. However, the number of curved plates can be arbitrarily set. For example, three curved plates are provided. In such a case, it is preferable to change the 120 ° phase.

  Moreover, although the motion conversion mechanism in said embodiment showed the example comprised by the inner pin 31 fixed to the wheel side rotation member 28, and the through-hole 30a provided in the curve boards 26a and 26b, Without being limited to the above, it is possible to adopt an arbitrary configuration capable of transmitting the rotation of the speed reduction unit B to the wheel hub 32. For example, it may be a motion conversion mechanism composed of an inner pin fixed to a curved plate and a hole formed in the output member.

  Moreover, although the deceleration part B in said embodiment showed the example which employ | adopted the cycloid reduction gear (K-H-V type planetary reduction gear) with a very large reduction ratio, this invention is others of the reduction part B. This can be applied to the case where the speed reduction mechanism is adopted. However, since the deceleration portion B having a large transmission torque as shown in FIG. 1 has a large heat generation amount, it is considered that the effect when the present invention is applied is high.

  In addition, although description of the action | operation in said embodiment was performed paying attention to rotation of each member, the motive power containing a torque is actually transmitted from the motor part A to a driving wheel. Therefore, the power decelerated as described above is converted into high torque.

  Further, in the description of the operation in the above embodiment, power is supplied to the motor unit A to drive the motor unit A, and the power from the motor unit A is transmitted to the drive wheels 14, but on the contrary, When the vehicle decelerates or goes down a hill, the power from the drive wheel 14 side is converted into high-rotation and low-torque rotation by the deceleration unit B and transmitted to the motor unit A, and the motor unit A generates power. May be. Furthermore, the electric power generated here may be stored in a battery and used later for driving the motor unit A or for operating other electric devices provided in the vehicle.

  Further, a brake can be added to the configuration of the above embodiment. For example, in the configuration of FIG. 1, in the space on the right side of the rotor 24 in the drawing, a rotating member that rotates integrally with the rotor 24, a piston that is non-rotatable in the casing 22 and that can move in the axial direction, and this piston are operated. It may be a parking brake that disposes a cylinder and locks the rotor 24 by fitting the piston and the rotating member when the vehicle is stopped.

  Alternatively, it may be a disc brake in which a flange formed on a part of a rotating member that rotates integrally with the rotor 24 and a friction plate installed on the casing 22 side are sandwiched by a cylinder installed on the casing 22 side. Furthermore, a drum brake can be used in which a drum is formed on a part of the rotating member, a brake shoe is fixed to the casing 22 side, and the rotating member is locked by friction engagement and self-engagement.

  In the above embodiment, the outer raceway surfaces 33a and 33b of the wheel hub bearing 33 are formed on the outer member 22a, and the inner raceway surfaces 33c and 33d are formed on the wheel side rotation member 28 and the wheel hub 32. However, the present invention is not limited to this, and any form can be adopted. For example, an outer raceway surface may be formed on the outer ring fitted to the casing, and an inner raceway surface may be provided on the inner race fitted to the wheel-side rotating member or the wheel hub.

  In the above embodiment, the wheel-side rotating member 28 and the wheel hub 32 are fixedly connected by expanding and caulking. However, the present invention is not limited to this. Also good.

  In the above-described embodiment, an example in which an angular ball bearing is adopted as the wheel hub bearing 33 has been shown. However, the present invention is not limited to this, and for example, a plain bearing, a cylindrical roller bearing, a tapered roller bearing, and a needle roller bearing. Spherical roller bearings, deep groove ball bearings, angular contact ball bearings, 4-point contact ball bearings, etc., regardless of whether the rolling element is a roller or a ball, whether it is a plain bearing or a rolling bearing In addition, any bearing can be applied regardless of whether it is a double row or a single row. Similarly, any type of bearing can be adopted for bearings arranged in other locations.

  In the above-described embodiment, an example in which an axial gap motor is employed for the motor unit A has been described. However, the present invention is not limited to this, and a motor having an arbitrary configuration can be applied. For example, it may be a radial gap motor including a stator fixed to the casing and a rotor disposed at a position facing the stator with a radial gap inside.

  Furthermore, although the electric vehicle 11 shown in FIG. 5 showed the example which used the rear wheel 14 as the driving wheel, it is not restricted to this, The front wheel 13 may be used as a driving wheel and may be a four-wheel driving vehicle. . In the present specification, “electric vehicle” is a concept including all vehicles that obtain driving force from electric power, and should be understood as including, for example, a hybrid vehicle.

  As mentioned above, although embodiment of this invention was described with reference to drawings, this invention is not limited to the thing of embodiment shown in figure. Various modifications and variations can be made to the illustrated embodiment within the same range or equivalent range as the present invention.

It is a schematic sectional drawing of the in-wheel motor drive device concerning one Embodiment of this invention. It is sectional drawing in II-II of FIG. It is an enlarged view of the eccentric part periphery of FIG. It is an enlarged view of the wheel hub bearing part of FIG. It is a top view of the electric vehicle which has the in-wheel motor drive device of FIG. FIG. 6 is a rear sectional view of the electric vehicle in FIG. 5.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 Electric vehicle, 12 Chassis, 12a Wheel housing, 12b Suspension device, 13 Front wheel, 14 Rear wheel, 15, 21 In-wheel motor drive device, 22 Casing, 22a Outer member, 23 Stator, 24 Rotor, 24a, 28a, 32b Flange portion, 24b, 28b, 32a hollow portion, 25 motor side rotating member, 25a, 25b eccentric portion, 26a, 26b curved plate, 27 outer pin, 27a, 31a needle roller bearing, 28 wheel side rotating member, 29 counterweight 30a, 30b Through-hole, 31 Inner pin, 32d, 33g, 34, 36 Sealing member, 33 Wheel hub bearing, 33a First outer raceway, 33b Second outer raceway, 33c First inner raceway, 33d Second Inner raceway surface, 33e, 39c ball, 33f cage, 35, 37, 38, 9,41 rolling, 39a inner, 39 b outer, 22b volts, 40 plastic coupling portion.

Claims (3)

A casing,
A motor unit for rotationally driving the motor side rotating member;
A speed reducer that decelerates the rotation of the motor side rotating member and transmits it to the wheel side rotating member;
A wheel hub fixedly connected to the wheel-side rotating member;
A wheel hub bearing that rotatably supports the wheel hub with respect to the casing;
The wheel hub bearing is an in-wheel motor drive device which is a rolling bearing having a plurality of rolling elements formed of ceramics. The wheel hub bearing is a double row rolling bearing having a double row raceway surface,
When the PCD of the plurality of rolling elements arranged on the raceway surface on the outboard side is d ₁ and the PCD of the plurality of rolling elements arranged on the raceway surface on the inboard side is d ₂ ,
satisfy d _{1> d 2,} in-wheel motor drive device according to claim 1. The motor side rotating member has an eccentric part,
The deceleration part is
A revolving member that is rotatably held by the eccentric part and performs a revolving motion around its rotational axis as the motor-side rotating member rotates.
An outer periphery engaging member that is fixed to the casing and engages with an outer peripheral portion of the revolving member to cause rotation of the revolving member;
The motion conversion mechanism according to claim 1, further comprising: a rotation conversion mechanism that converts a rotation motion of the revolution member into a rotation motion centered on a rotation axis of the motor side rotation member and transmits the rotation motion to the wheel side rotation member. In-wheel motor drive device.

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