JP2018044632A - In-wheel motor driving device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an in-wheel motor driving device compact in an axial direction.SOLUTION: In an in-wheel motor driving device 21 including a driving portion A composed of an electric motor 28, a deceleration portion B composed of a parallel axis gear reducer 38 composed of a plurality of gears 34-37, a bearing portion C composed of a bearing 53 for a wheel, and a casing 22 accommodating the driving portion A and the deceleration portion B, the parallel axis gear reducer 38 has a fourth gear 37 for transmitting driving force to the bearing 53 for wheel, the bearing 53 for wheel includes a pair of inner rings 56, 57 fixed to the casing 22, an outer ring 58 supported rotatably to the casing 22, and rolling elements 59, 60 disposed between the inner rings 56, 57 and the outer ring 58. The fourth gear 37 of the parallel axis gear reducer 38 is rotatably disposed by the rolling bearings 51, 52 to the casing 22 at a radial outer side of the outer ring 58, and the rolling bearings 51, 52 are provided with seals 65, 66.SELECTED DRAWING: Figure 1

Description

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

  A conventional in-wheel motor drive device has a structure disclosed in Patent Document 1, for example. The in-wheel motor drive device disclosed in Patent Document 1 transmits an electric motor that generates a driving force, a parallel shaft gear reducer that decelerates and outputs the rotation of the electric motor, and an output from the parallel shaft gear reducer to wheels. It consists of a wheel hub that does.

  In this in-wheel motor drive device, an intermediate plate is provided between the electric motor and the parallel shaft gear reducer, a motor housing in which the electric motor is accommodated is provided on the inboard side of the intermediate plate, and the parallel shaft gear reducer A structure is provided in which the accommodated gear housing is provided on the outboard side of the intermediate plate.

  The electric motor includes a stator fixed to the motor housing and a rotor shaft that is rotatably supported by the motor housing inside the stator.

  The parallel shaft gear reducer includes a motor input gear coaxially connected to the rotor shaft of the electric motor, a first counter gear that is rotatably supported by the intermediate plate and the gear housing, and meshes with the motor input gear, The second counter gear is supported coaxially with the counter gear, and the output gear is provided on the axle of the wheel hub and meshes with the second counter gear.

  The wheel hub is mainly composed of an outer ring fixedly arranged with respect to the gear housing, an inner ring rotatably supported with respect to the gear housing, and a double row rolling element interposed between the outer ring and the inner ring. Is generally configured.

JP 2014-46742 A

  By the way, in the in-wheel motor drive device disclosed by patent document 1, the output from a parallel shaft gear reducer is made into a wheel hub by connecting a wheel hub and the output gear of a parallel shaft gear reducer so that torque transmission is possible. I try to communicate.

  In general, the wheel hub employs an inner ring rotating type structure in which an inner ring is coupled by spline fitting to a shaft portion extending from the output gear of the parallel shaft gear reducer toward the axial outboard side. By adopting such a structure, the rotational torque from the output gear can be transmitted to the wheel hub.

  On the other hand, since the in-wheel motor drive device is accommodated in the wheel space, there is a possibility that the in-wheel motor drive device may interfere with suspension parts around the wheel when protruding from the wheel space. For this reason, it is preferable that the in-wheel motor drive device has a smaller axial dimension.

  However, in the conventional in-wheel motor drive device, as described above, the structure in which the inner ring of the wheel hub is coupled by spline fitting to the shaft portion extending from the output gear of the parallel shaft gear reducer to the axial outboard side, that is, Since the electric motor, the parallel shaft gear reducer, and the wheel hub are simply arranged in the axial direction, it is difficult to reduce the axial dimension of the entire in-wheel motor driving device.

  The present invention has been proposed in view of the above-mentioned problems, and an object of the present invention is to provide an in-wheel motor drive apparatus that is compact in the axial direction by simple means.

  An in-wheel motor drive device according to the present invention includes a drive unit configured by an electric motor, a reduction unit configured by a parallel shaft gear reducer composed of a plurality of gears, a bearing unit configured by a wheel bearing, A structure including a drive unit and a casing that houses the speed reduction unit is provided.

  The parallel shaft gear reducer according to the present invention has an output gear that transmits a driving force to the wheel bearing. Further, the wheel bearing according to the present invention includes a pair of inner rings fixedly arranged with respect to the casing, an outer ring supported rotatably with respect to the casing, and a double row interposed between the inner ring and the outer ring. The structure provided with the rolling element.

  As technical means for achieving the above-mentioned object, the present invention arranges an output gear of a parallel-shaft gear reducer so as to be rotatable by a support bearing with respect to a casing on the radially outer side of the outer ring, and a seal is provided on the support bearing. It is provided.

  In the present invention, by arranging the output gear of the parallel shaft gear reducer on the radially outer side of the outer ring of the wheel bearing, the outer ring of the wheel bearing and the output gear of the parallel shaft gear reducer are overlapped in the axial direction. The axial dimension of the wheel bearing and the parallel shaft gear reducer can be reduced. Thereby, the axial direction dimension of the whole in-wheel motor drive device can be made small.

  In addition, by providing a seal on the support bearing that rotatably supports the output gear with respect to the casing, the seal structure is integrated with the support bearing, so a single seal that is separate from the support bearing is not required. It becomes. Thereby, the axial direction dimension of the whole in-wheel motor drive device can be made still smaller.

  The support bearing in the present invention is preferably composed of a pair of bearings located on the outboard side and the inboard side of the wheel bearing, and at least a structure in which a seal is provided at the outer opening of the bearing located on the outboard side.

  By adopting such a structure, it is possible to prevent the lubricating oil enclosed in the casing from flowing out to the outside without arranging an oil seal, and to reduce the axial dimension of the entire in-wheel motor drive device. Can contribute.

  In the present invention, a structure in which a fixed shaft is inserted into an inner ring of a wheel bearing and an O-ring is disposed in a radial gap between the inner ring and the fixed shaft is desirable.

  If such a structure is adopted, the inner ring and the fixed shaft do not rotate relative to each other, so that the O-ring can be sealed without an oil seal. Thus, by using an O-ring having a smaller width than the oil seal, it is possible to contribute to reducing the axial dimension of the entire in-wheel motor drive device.

  According to the present invention, the output gear of the parallel shaft gear reducer is disposed on the outer side in the radial direction of the outer ring so as to be rotatable by the support bearing with respect to the casing, and the support bearing is provided with a seal, thereby The axial dimension combined with the gear reducer can be reduced, and by integrating the seal structure with the support bearing, a single seal constituted separately from the support bearing becomes unnecessary. As a result, an in-wheel motor drive device that is compact in the axial direction can be easily realized.

In embodiment of this invention, it is sectional drawing which shows the whole structure of an in-wheel motor drive device. It is the schematic which looked at the parallel shaft gear reducer of FIG. 1 from the outboard side. It is a principal part expanded sectional view which shows the output gearwheel and wheel bearing of FIG. It is principal part expanded sectional drawing which shows the output gearwheel and the bearing for wheels in other embodiment of this invention. It is a top view which shows schematic structure of the electric vehicle carrying an in-wheel motor drive device. FIG. 6 is a rear sectional view showing the electric vehicle of FIG. 5.

  An embodiment of an in-wheel motor drive device according to the present invention will be described in detail with reference to the drawings. FIG. 5 is a schematic plan view of the electric vehicle 11 on which the in-wheel motor drive device 21 is mounted, and FIG. 6 is a schematic cross-sectional view of the electric vehicle 11 as viewed from the rear.

  As shown in FIG. 5, 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. Equip. As shown in FIG. 6, the rear wheel 14 is accommodated in a wheel housing 15 of the chassis 12, and is fixed to the lower portion of the chassis 12 via an independent suspension type suspension device (suspension) 16.

  In the electric vehicle 11, the in-wheel motor drive device 21 that drives the left and right rear wheels 14 is provided inside the wheel housing 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 wide cabin space can be secured and the rotation of the left and right rear wheels 14 can be controlled.

  In order to improve the running stability and NVH characteristics of the electric vehicle 11, it is necessary to suppress the unsprung weight, and further, downsizing of the in-wheel motor drive device 21 is required in order to secure a wide cabin space.

  Therefore, the in-wheel motor drive device 21 of the embodiment shown in FIG. 1 has the following structure. Thereby, the compact in-wheel motor drive device 21 is implement | achieved and the electric vehicle 11 excellent in driving | running | working stability and NVH characteristic can be obtained by restraining unsprung weight.

  Before describing the characteristic configuration of this embodiment, the overall configuration of the in-wheel motor drive device 21 will be described. In the following description, with the in-wheel motor drive device 21 mounted on the vehicle body, the side closer to the outside of the vehicle body is referred to as the outboard side (left side in the drawing), and the side closer to the center is inboard side (right side in the drawing). Called.

  As shown in FIG. 1, the in-wheel motor drive device 21 includes a drive unit A that generates a driving force, a deceleration unit B that decelerates and outputs the rotation of the drive unit A, and an output from the deceleration unit B as driving wheels. As a rear wheel 14 (see FIGS. 5 and 6). The drive part A and the speed reduction part B are accommodated in the casing 22 and attached to the wheel housing 15 (see FIG. 6) of the electric vehicle 11.

  The casing 22 is integrally formed by a motor housing 23 that houses the electric motor 28 of the drive unit A and a gear housing 24 that houses a part of the parallel shaft gear reducer 38 of the reduction unit B and a wheel bearing 53 of the bearing unit C. It is structured. The motor housing 23 and the gear housing 24 are arranged so as to be shifted in the radial direction.

  The drive unit A is a stator 25 fixed to the casing 22, a rotor 26 disposed so as to face the inner side in the radial direction of the stator 25 with a gap, and an inner side in the radial direction of the rotor 26 so as to rotate integrally with the rotor 26. And a radial gap type electric motor 28 having a motor rotating shaft 27. The motor rotating shaft 27 can rotate at a high speed of about 10,000 to 1000 rotations per minute. The stator 25 is configured by winding a coil around the outer periphery of the magnetic core. The rotor 26 has a permanent magnet or a magnetic material disposed therein.

  The motor rotating shaft 27 holds the rotor 26 by a holder portion 31 that extends integrally outward in the radial direction. The holder portion 31 has a configuration in which a concave groove in which the rotor 26 is fitted and fixed is formed in an annular shape. The motor rotating shaft 27 has one end in the axial direction (right side in FIG. 1) as a rolling bearing 32 and the other end (left side in FIG. 1) in the motor housing 23 of the casing 22 by a rolling bearing 33. On the other hand, it is supported rotatably.

  The reduction part B is configured by a parallel shaft gear reducer 38 including a first gear 34 as an input gear, a second gear 35 and a third gear 36 as intermediate gears, and a fourth gear 37 as an output gear. ing. The second gear 35 has a small-diameter tooth portion 39 on the inboard side and a large-diameter tooth portion 40 on the outboard side coaxially. Further, the third gear 36 has a large-diameter tooth portion 41 on the inboard side and a small-diameter tooth portion 42 on the outboard side coaxially.

  In the parallel shaft gear reducer 38, the tooth portion 43 of the first gear 34 meshes with the large diameter tooth portion 40 of the second gear 35, and the small diameter tooth portion 39 of the second gear 35 and the large diameter tooth of the third gear 36. When the portion 41 meshes with the small-diameter tooth portion 42 of the third gear 36 and the tooth portion 44 of the fourth gear 37, the rotational motion of the motor rotating shaft 27 is decelerated at a predetermined reduction ratio.

  Since the in-wheel motor drive device 21 is housed in the wheel housing 15 (see FIG. 6) and becomes an unsprung load, it is essential to reduce the size and weight. Therefore, by using the parallel shaft gear reducer 38 having a large reduction ratio, the electric motor 28 can be miniaturized by combining with the high-speed electric motor 28, and the in-wheel motor drive device 21 having a compact and high reduction ratio can be obtained. realizable.

  The first gear 34 is coaxially attached to the motor rotating shaft 27 by spline fitting, and is rotatably supported by the gear housing 24 of the casing 22 by rolling bearings 45 and 46. The second gear 35 is rotatably supported on the gear housing 24 by rolling bearings 47 and 48. The third gear 36 is rotatably supported on the gear housing 24 by rolling bearings 49 and 50. The fourth gear 37 is coaxially attached to the outer ring 58 of the wheel bearing 53 by spline fitting, and is rotatably supported by the gear housing 24 by rolling bearings 51 and 52 that are support bearings.

  As shown in FIG. 1, the first gear 34 to the third gear 37 are arranged on a straight line along the radial direction. Further, the rotation centers C1 to C4 of the first gear 34 to the fourth gear 37 are offset with a positional relationship as shown in FIG. Thus, by arranging the first gear 34 to the fourth gear 37, the reduction part B is made compact in the axial direction and the radial direction. In addition, the code | symbol M in a figure shows wheel space.

  Here, helical gears are used for the first gear 34 to the fourth gear 37. Helical gears are effective in that the number of teeth engaged simultaneously increases and the tooth contact is dispersed, so that the sound is quiet and torque fluctuation is small. In this way, by using a helical gear for the parallel shaft gear reducer 38, it is possible to realize the in-wheel motor drive device 21 that is easy to manufacture and can be reduced in cost, and that is quiet and efficient in terms of performance. it can.

  As shown in FIG. 1, the bearing portion C includes a wheel bearing 53 having the following structure. The wheel bearing 53 includes a pair of inner rings 56 and 57 fitted to the outer periphery of the fixed shaft 55 attached to the suspension member 54, an outer ring 58 disposed outside the inner rings 56 and 57, and inner rings 56 and 57. And a plurality of rolling elements 59, 60 arranged in two rows in the axial direction.

  Inner rings 56, 57 arranged on the inboard side and the outboard side of the wheel bearing 53 are stopped together with the fixed shaft 55, and are prevented from coming off by a nut 61 screwed into the end of the fixed shaft 55. A preload is applied to the wheel bearing 53 by the tightening force of the nut 61. By applying this preload, the wheel bearing 53 has a double-row angular ball bearing structure.

  Seal members 62 and 63 are provided at both ends of the wheel bearing 53 in the axial direction to prevent entry of muddy water and the like and leakage of grease. A flange 64 is integrally formed on the outboard side of the outer ring 58, and the rear wheel 14 (see FIGS. 5 and 6) is connected to the flange 64 with a hub bolt (not shown).

  The fourth gear 37 of the parallel shaft gear reducer 38 is disposed on the radially outer side of the outer ring 58 of the wheel bearing 53. As described above, the outer ring 58 is connected to the fourth gear 37 rotatably supported by the rolling bearings 51 and 52 with respect to the gear housing 24 so as to transmit torque by spline fitting.

  Thus, by arranging the fourth gear 37 of the parallel-shaft gear reducer 38 on the radially outer side of the outer ring 58 of the wheel bearing 53, the outer ring 58 and the fourth gear 37 can be overlapped in the axial direction. . As a result, since the axial dimension of the wheel bearing 53 and the parallel shaft gear reducer 38 can be reduced, the axial dimension of the entire in-wheel motor drive device 21 can be reduced.

  Further, by adopting a structure in which the outer ring 58 of the wheel bearing 53 is coupled to the fourth gear 37 of the parallel shaft gear reducer 38 so as to be able to transmit torque by spline fitting, the inner ring having the outer ring rotating type wheel bearing 53 is adopted. The wheel motor drive device 21 can be easily realized.

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

  As shown in FIG. 1, in the driving unit A, the rotor 26 rotates by receiving electromagnetic force generated by supplying an alternating current to the stator 25. In the reduction part B, the rotation of the motor rotating shaft 27 is decelerated by the first gear 34 to the fourth gear 37 of the parallel shaft gear reducer 38 and transmitted to the wheel bearing 53 of the bearing part C.

  At this time, the rotation of the motor rotating shaft 27 is decelerated by the parallel shaft gear reducer 38 and transmitted to the wheel bearing 53. Therefore, even when the low torque, high speed rotating electric motor 28 is employed, the rear wheel 14 ( It is possible to transmit the torque necessary for the process (see FIGS. 5 and 6).

  In this embodiment, the radial gap type electric motor 28 is exemplified as the drive unit A, but a motor having an arbitrary configuration is applicable. For example, an axial gap type electric motor including a stator fixed to a casing and a rotor arranged so as to face the inner side in the axial direction of the stator with a gap may be used.

  In this in-wheel motor drive device 21, lubricating oil for cooling the electric motor 28 is enclosed in the drive part A, and lubricating oil for cooling and lubricating the parallel shaft gear reducer 38 is enclosed in the reduction part B. Yes. When the in-wheel motor drive device 21 is driven, the drive unit A cools the electric motor 28 with the rotation of the rotor 26. In the speed reduction part B, the parallel shaft gear speed reducer 38 is cooled and lubricated by splashing by the rotation of the first gear 34 to the fourth gear 37.

  The overall configuration of the in-wheel motor drive device 21 in this embodiment is as described above, and the characteristic configuration will be described in detail below.

  Here, the in-wheel motor drive device 21 needs a seal structure in order to cool the electric motor 28, cool the parallel shaft gear reducer 38, and prevent the lubricating oil to be lubricated from flowing out to the outside. In this seal structure, since the oil seal that seals the rotating body is press-fitted and attached, it is necessary to provide a chamfered shape for facilitating the press-fitting on the casing and the shaft. Therefore, the axial dimension including the mounting shape of the oil seal increases.

  Therefore, in the in-wheel motor drive device 21 of this embodiment, as shown in FIG. 3, the fourth gear 37 of the parallel shaft gear reducer 38 is connected to the gear housing 24 on the radially outer side of the outer ring 58 of the wheel bearing 53. The roller bearings 51 and 52 that are rotatably supported are provided with seals 65 and 66, respectively. The seals 65 and 66 are provided at outer openings of the rolling bearings 51 and 52 located on the outboard side and the inboard side. Further, O-rings 67 and 68 are disposed in the radial gap between the rolling bearings 51 and 52 and the gear housing 24.

  As described above, by providing the rolling bearings 51 and 52 with the seals 65 and 66, the seal structure is integrated with the rolling bearings 51 and 52, so that a single seal configured separately from the rolling bearings 51 and 52 is provided. Is no longer necessary. Further, by providing the O-rings 67 and 68 having a smaller width than the oil seal, it is possible to prevent the lubricating oil sealed inside the gear housing 24 from flowing out.

  As a result, the overall axial dimension of the in-wheel motor drive device 21 can be reduced. Thus, it is easy to accommodate the in-wheel motor drive device 21 in the wheel space by realizing the in-wheel motor drive device 21 that is compact in the axial direction. Since the in-wheel motor drive device 21 can be prevented from protruding from the wheel space, interference with suspension components around the wheel can be prevented.

  Moreover, since the axial dimension of the in-wheel motor drive device 21 can be reduced, the wheel bearing 53 can be brought closer to the wheel center. Thus, when the wheel bearing 53 approaches the wheel center, the turning load can be evenly distributed by the two rolling elements 59 and 60 when the wheel bearing 53 receives the turning load. The durability of the bearing 53 is improved.

  Here, the spline fitting portion 69 that connects the outer ring 58 of the wheel bearing 53 and the fourth gear 37 of the parallel shaft gear reducer 38 so as to be able to transmit torque is worn by a load and wear powder is generated. There is a risk.

  On the other hand, in the in-wheel motor drive device 21 of this embodiment, the outer opening of the rolling bearing 51 arranged in the vicinity of the aforementioned spline fitting portion 69, that is, the opening on the spline fitting portion 69 side. A seal 65 is provided. Thereby, it is possible to prevent the wear powder from entering the inside of the rolling bearing 51 and to avoid the damage of the rolling bearing 51 due to the biting of the wear powder.

  In the embodiment shown in FIG. 3, the case where the seals 65 and 66 are provided in the outer openings of the rolling bearings 51 and 52 located on the outboard side and the inboard side is illustrated, but the present invention is limited to this. Alternatively, the structure shown in FIG. 4 may be used.

  In the in-wheel motor drive device 21 of the embodiment shown in FIG. 4, as in the embodiment of FIG. 3, a seal 66 is provided at the outer opening of the rolling bearing 52 located on the outboard side, and the rolling bearing 52, the gear housing 24, As shown in FIG. 4, an O-ring 70 is arranged in the radial gap between the inner ring 56 located on the inboard side of the wheel bearing 53 and the fixed shaft 55, as shown in FIG. Yes.

  Since the inner ring 56 of the wheel bearing 53 and the fixed shaft 55 do not rotate relative to each other, the O disposed in the radial gap between the inner ring 56 of the wheel bearing 53 and the fixed shaft 55 can be provided without providing an oil seal. The ring 70 can be sealed. Thus, by using the O-ring 70 having a smaller width dimension than the oil seal, it is possible to contribute to reducing the axial dimension of the entire in-wheel motor drive device 21.

  In the above embodiment, as shown in FIGS. 5 and 6, the electric vehicle 11 having the rear wheel 14 as a driving wheel is illustrated, but the front wheel 13 may be a driving wheel or 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 includes, for example, a hybrid vehicle.

  The present invention is not limited to the above-described embodiments, and can of course be implemented in various forms without departing from the gist of the present invention. It includes the equivalent meanings recited in the claims and the equivalents recited in the claims, and all modifications within the scope.

21 in-wheel motor drive device 22 casing 28 electric motor 33 to 36 gear 37 output gear (fourth gear)
38 Parallel shaft gear reducer 51, 52 Support bearing (rolling bearing)
53 Wheel bearing 55 Fixed shaft 56, 57 Inner ring 58 Outer ring 59, 60 Rolling element 65, 66 Seal 70 O-ring A Drive part B Reduction part C Bearing part

Claims (3)

A drive unit configured by an electric motor, a reduction unit configured by a parallel shaft gear reducer composed of a plurality of gears, a bearing unit configured by wheel bearings, and a casing that houses the drive unit and the reduction unit An in-wheel motor drive device comprising:
The parallel shaft gear reducer has an output gear that transmits a driving force to the wheel bearing, and the wheel bearing is a pair of inner rings that are fixedly arranged with respect to the casing, and is rotatable with respect to the casing. An outer ring supported by the inner ring and a rolling element interposed between the inner ring and the outer ring, and the output gear of the parallel shaft gear reducer is rotated by a support bearing with respect to the casing on the radially outer side of the outer ring. An in-wheel motor drive device characterized by being freely arranged and provided with a seal on the support bearing.   The said support bearing is comprised by a pair of bearing located in the outboard side and inboard side of the said wheel bearing, The seal | sticker was provided in the outer opening part of the bearing located in the said outboard side at least. In-wheel motor drive device.   The in-wheel motor drive device according to claim 1 or 2, wherein a fixed shaft is fitted into an inner ring of the wheel bearing, and an O-ring is disposed in a radial clearance between the inner ring and the fixed shaft.

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