JP2018070095A - In-wheel motor drive device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve miniaturization of an in-wheel motor drive device by making the dimension of the in-wheel motor drive device in a vehicle width direction smaller than a known dimension, to thereby enhance versatility of the drive device or its peripheral elements.SOLUTION: An in-wheel motor drive device 21 according to the present invention comprises a motor part A, a bearing part C for wheel, and a reduction gear part B. The reduction gear part B has: an input shaft 35 to which a rotational driving force is input; an output shaft 38 from which the rotational driving force is output; at least one intermediate shaft 36 parallel to the input shaft 35 and the output shaft 38; an input gear 30 provided in the input shaft 35; an output gear 34 provided in the output shaft 38; and a large-diameter intermediate gear 31 and a small-diameter intermediate gear 32 provided in the intermediate shaft 36 and having different pitch circle diameters. These input gear 30 and the output gear 34, and the large-diameter intermediate gear 31 and the small-diameter intermediate gear 32 constitute a power transmission path from the input shaft 35 to the output shaft 38, and an idler gear 33 is provided on this power transmission path.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an in-wheel motor drive device.

  As the in-wheel motor, there are known a direct system in which the rotational driving force of the motor is directly transmitted to the wheels, and a reduction gear combined system in which the rotational driving force of the motor is decelerated by a speed reducer and transmitted to the wheels. For example, Patent Document 1 discloses an in-wheel motor drive device that includes a speed reducer and is arranged so that an output shaft and an input shaft are parallel to each other as an example of a device that employs a speed reducer combined system. Yes.

JP2012-214202A

  Thus, by arranging the output shaft and the input shaft so as to be parallel to each other, for example, compared to the case where the motor, the speed reducer, and the wheel bearing are coaxially arranged in series, the in-wheel motor It is possible to reduce the dimension in the vehicle width direction of the drive device (the dimension in the direction perpendicular to the front-rear direction of the vehicle when mounted on the vehicle; the same applies hereinafter). However, the in-wheel motor drive device described in Patent Document 1 has a configuration in which a reduction planetary gear mechanism that constitutes a reduction gear is arranged coaxially with an output shaft. In this case, even if the motor and the wheel bearing are arranged in parallel, it is difficult to sufficiently reduce the dimension in the vehicle width direction of the in-wheel motor drive device.

  That is, when the in-wheel motor drive device is not sufficiently small in the vehicle width direction and the inboard side of the in-wheel motor drive device projects from the wheel, the wheel and It becomes difficult to completely accommodate the in-wheel motor drive device. In this case, the vehicle body for the internal combustion engine vehicle cannot be used for the electric vehicle equipped with the in-wheel motor drive device, which may increase the cost of the electric vehicle.

  In view of the above circumstances, in the present specification, the in-wheel motor drive device is made smaller in size in the vehicle width direction than the known size, so that the in-wheel motor drive device can be downsized, and thus the drive device or its surroundings. Increasing the versatility of elements is a technical issue to be solved.

  The solution to the above problem is achieved by the electric actuator according to the present invention. That is, this actuator is an in-wheel motor drive device including a motor unit, a wheel bearing unit, and a reduction gear unit that decelerates rotation by the motor unit and transmits the reduced speed to the wheel bearing unit. An input shaft to which the rotational driving force by the unit is input, an output shaft from which the rotational driving force is output, at least one intermediate shaft parallel to the input shaft and the output shaft, an input gear provided on the input shaft, and an output An output gear provided on the shaft, and a large-diameter intermediate gear and a small-diameter intermediate gear provided on the intermediate shaft and having different pitch circle diameters, the input gear and the output gear, and the large-diameter intermediate gear and the small-diameter intermediate gear are: A power transmission path from the input shaft to the output shaft is configured, and an idler gear is disposed on the power transmission path.

  Thus, in the present invention, a reduction gear unit having a large-diameter intermediate gear and a small-diameter intermediate gear provided on the intermediate shaft in addition to the input shaft, the output shaft, and the intermediate shaft that are parallel to each other, and the input gear and the output gear. Is provided in the in-wheel motor drive device, and a power transmission path from the input shaft to the output shaft is configured by the input gear, the output gear, and the large-diameter intermediate gear, the small-diameter intermediate gear, and the output gear. By configuring the power transmission path in this way, at least two-stage deceleration can be achieved with only a minimum number of gears arranged in series in the vehicle width direction. Therefore, as compared with the case where the planetary gear mechanism is arranged in series with the output shaft as in Patent Document 1, it is possible to obtain a rotational output having a required size while reducing the size in the vehicle width direction of the in-wheel motor drive device. Is possible.

  In the present invention, the idler gear is disposed on the power transmission path described above. By disposing the idler gear in this way, the distance between the input shaft and the intermediate shaft, or the distance between the intermediate shaft and the output shaft can be changed as appropriate, so the arrangement of the elements constituting the in-wheel motor drive device is compact. It is possible to set the orientation to be changed.

  Specifically, as described above, when two intermediate gears having different pitch circle diameters are provided on the intermediate shaft to adopt a two-stage or more reduction gear structure, a relatively large-diameter gear is used to increase the reduction ratio as much as possible. For example, if an intermediate large-diameter gear is increased in diameter to increase the number of teeth, interference between the intermediate gear and an adjacent output shaft or its peripheral elements may occur. In order to avoid this interference, it is necessary to displace any element, for example, the peripheral element of the output shaft toward the inboard side of the vehicle as shown in FIG. 3, but when this happens, the center of rotation is bent. Due to the arrangement of the shafts so as to have a shape, for example, there is a possibility that a motor that should be separated from the output shaft may interfere with surrounding elements of the output shaft, and as a result, the motor is further connected to the inboard side of the vehicle. It was necessary to shift to. On the other hand, in the present invention, since the idler gear is arranged on the power transmission path, for example, as shown in FIG. 1, the idler gear meshes between the small-diameter intermediate gear and the output gear. Thus, the distance between the rotation center of the intermediate shaft and the rotation center of the output shaft can be increased. Therefore, for example, the large-diameter intermediate gear can be increased in diameter without shifting the peripheral elements of the output shaft, and thus the motor, to the inboard side of the vehicle, and both high output and compactness can be achieved. . Therefore, it is possible to divert an existing vehicle body for an internal combustion engine automobile to an electric vehicle equipped with an in-wheel motor drive device, and improve the versatility of the in-wheel motor drive device and its peripheral elements.

  In the in-wheel motor drive device according to the present invention, the pitch circle diameter of the idler gear is larger than the pitch circle diameter of the gear meshing with the idler gear on the side close to the input shaft on the power transmission path, and the idler gear and the power It may be configured to be smaller than the pitch circle diameter of the gear meshing on the side close to the output shaft on the transmission path.

  By selecting each gear so that such a relationship is established, the large-diameter intermediate gear can be separated from the peripheral element of the output shaft to such an extent that interference with the peripheral element of the output shaft can be surely avoided. The drive device can be reliably accommodated in the wheel housing while avoiding an increase in the size of the drive device by disposing the intermediate gear having a larger diameter on the outer diameter side of the in-wheel drive device than necessary.

  In the in-wheel motor drive device according to the present invention, the idler gear meshes with the small-diameter intermediate gear and the output gear, and when viewed from the vehicle width direction, the rotation center of the idler gear, the rotation center of the small-diameter intermediate gear, and A configuration may be adopted in which the rotation centers of the output gears are in a linearly aligned position.

  By arranging the idler gear, the small-diameter intermediate gear, and the output gear in this manner, the large-diameter intermediate gear arranged coaxially with the small-diameter intermediate gear can be separated from the output gear and the output shaft very efficiently. In addition, since the rotation centers of the three gears are arranged in a straight line, the force received by the idler gear when the small-diameter intermediate gear and the output gear mesh with each other cancels out both the radial component and the thrust component. A large load does not act on the idler gear. Therefore, it is possible to increase the degree of freedom in selecting the idler gear. For example, by selecting a small idler gear as much as possible, it is possible to further reduce the size of the in-wheel motor drive device.

  Further, the in-wheel motor drive device according to the present invention may be configured such that the idler gear is positioned closer to the outboard side of the vehicle than the large-diameter intermediate gear.

  The in-wheel motor drive device according to the present invention further includes a casing that houses at least the speed reducer portion, and the shaft of the idler gear is supported by a bearing attached to the casing on the vehicle outboard side. It may be a thing.

  In this way, by adopting a configuration in which the idler gear is supported by the bearing attached to the casing on the outboard side, for example, the idler gear is cantilevered, and the center of rotation of the shaft is large in diameter when viewed from the vehicle width direction. An idler gear can be arranged at a position overlapping the gear. Therefore, even when the idler gear is arranged, it is possible to further reduce the size of the in-wheel motor drive device by configuring the speed reducer portion as compactly as possible.

  Further, the in-wheel motor driving device according to the present invention has one intermediate shaft, and the large-diameter intermediate gear and the input gear of one intermediate shaft mesh with each other, and the small-diameter intermediate gear and the idler gear of one intermediate shaft mesh with each other. The structure which makes it may be sufficient.

  In the present invention, by disposing an idler gear on the power transmission path, it is possible to suppress an increase in the vehicle width direction dimension of the in-wheel motor drive device while increasing the diameter of the large-diameter intermediate gear. Therefore, for example, there is one intermediate shaft, and a power transmission path is constituted by one large-diameter intermediate gear and one small-diameter intermediate gear provided on the intermediate shaft, an input gear, an output gear, and an idler gear. However, it is possible to reduce the size of the in-wheel motor drive device to such an extent that the wheel housing can be accommodated while exhibiting the necessary and sufficient reduction ratio and thus the output torque.

  As described above, according to the present invention, the in-wheel motor drive device is reduced in size in the vehicle width direction to be smaller than a known size, so that the in-wheel motor drive device can be reduced in size, and the drive device or its surroundings can be obtained. It becomes possible to improve the versatility of the member.

It is sectional drawing of the in-wheel motor drive device which concerns on 1st embodiment of this invention, and is sectional drawing along the PP line of FIG. It is a partial cross section figure of the in-wheel motor drive device along the QQ line of FIG. It is sectional drawing of the in-wheel motor which concerns on the other structure used as the comparison object of the in-wheel motor drive device shown in FIG. 1, and is sectional drawing along the SS line | wire of FIG. It is a partial cross section figure of the in-wheel motor drive device along the RR line | wire of FIG. 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. It is a front view which shows the state which attached the suspension connection member to the in-wheel motor drive device shown in FIG. It is a side view which shows the state which attached the suspension connection member to the in-wheel motor drive device shown in FIG. It is sectional drawing of the in-wheel motor drive device which concerns on 2nd embodiment of this invention.

  Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. Note that in each drawing, substantially the same elements are denoted by the same reference numerals as much as possible, and the detailed description thereof will be omitted once described. The same applies to the description after the second embodiment of the present invention to be described later.

  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 FIGS. 5 and 6, 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 drive that transmits driving force to the rear wheel 14. Device 21. As shown in FIG. 6, the rear wheel 14 is accommodated in a wheel housing 15 of the chassis 12 and fixed to the lower portion of the chassis 12 via a suspension device (suspension) 16.

  The suspension device 16 supports the rear wheel 14 by a suspension arm that extends from side to side, and includes a strut 17 including a coil spring and a shock absorber, and a suspension connection member that connects the strut 17 and an in-wheel motor drive device 21 described later. By 100, the vibration which the rear-wheel 14 receives from the ground is absorbed, and the vibration of the chassis 12 is suppressed. A stabilizer that suppresses the inclination of the vehicle body during turning or the like is provided at a connecting portion of the left and right suspension arms. The suspension device 16 is an independent suspension type in which the left and right wheels are independently moved up and down in order to improve the followability to the road surface unevenness 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 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.

  Next, the configuration of the in-wheel motor drive device 21 will be described. Note that. In the following description, in a state where the in-wheel motor drive device 21 is mounted on the vehicle, the vehicle width direction outer side of the vehicle is referred to as an outboard side, and the vehicle width direction inner side is referred to as an inboard side.

  FIG. 1 is a longitudinal sectional view of the in-wheel motor drive device 21 taken along the line P-P in FIG. 2, and FIG. 2 shows one of the in-wheel motor drive device 21 taken along the line Q-Q in FIG. It is a front view containing a partial cross section.

  As shown in FIGS. 1 and 2, the in-wheel motor drive device 21 includes a motor part A that generates a rotational drive force, and a speed reducer part B that decelerates and outputs the rotational drive force input by the motor part A. And a wheel bearing portion C for transmitting the output from the speed reducer portion B to the rear wheel 14 as a drive wheel. The motor part A, the speed reducer part B, and the wheel bearing part C are each accommodated in the casing 22. Note that the casing 22 may be an integral structure, but in the present embodiment, as shown in FIG. In this case, the outboard side is referred to as a first divided casing 22a, and the inboard side is referred to as a second divided casing 22b.

  As shown in FIG. 1, the motor unit A includes a stator 23 fixed to the casing 22, a rotor 24 arranged to face the inner side in the radial direction of the stator 23 with a predetermined gap, and a radius of the rotor 24. A radial gap type motor 26 having a motor rotating shaft 25 that is disposed on the inner side in the direction and rotates integrally with the rotor 24 is provided. The motor 26 can be rotated at a high speed of, for example, about 10,000 to 1,000 revolutions per minute. The stator 23 is configured by winding a coil around a magnetic core, and the rotor 24 is configured by a permanent magnet or the like.

  One end (left end in FIG. 1) in the axial direction of the motor rotating shaft 25 is connected to the casing 22 by a bearing 40, and the other end in the axial direction (right end in FIG. 1) is connected to the casing 22 by a bearing 41. Each is supported rotatably. The pair of bearings 40 and 41 constitutes a motor part A together with the motor 26.

  As shown in FIG. 1, the reduction gear unit B includes an input gear 30, a large-diameter intermediate gear 31, a small-diameter intermediate gear 32, an idler gear 33, an output gear 34, an input shaft 35, and an intermediate shaft 36. And an idler gear shaft 37 and an output shaft 38. Among these, the input gear 30 is formed integrally with a hollow input shaft 35, and this input shaft 35 is coaxially connected to the motor rotating shaft 25 by spline fitting (including serration fitting, the same applies hereinafter). Yes. In this case, the motor rotation shaft 25 and the input shaft 35 rotate around a common rotation center O1. The large diameter intermediate gear 31 and the small diameter intermediate gear 32 are formed integrally with the intermediate shaft 36. In this case, the large diameter intermediate gear 31 and the small diameter intermediate gear 32 rotate around a common rotation center O2. The idler gear 33 is formed integrally with the idler gear shaft 37, and rotates around the rotation center O <b> 3 that is the central axis of the idler gear shaft 37. The output gear 34 is formed integrally with the output shaft 38, and rotates around the rotation center O <b> 4 that is the central axis of the output shaft 38.

  In addition, the input shaft 35, the intermediate shaft 36, the idler gear shaft 37, and the output shaft 38, which are all gear shafts, are arranged in parallel to each other. Among these, the input shaft 35 is supported by a pair of bearings 42 and 43, the intermediate shaft 36 is supported by a pair of bearings 44 and 45, and the output shaft 38 is rotated with respect to the casing 22 by a pair of bearings 46 and 47, respectively. It is supported freely. Regarding the intermediate shaft 36, in this embodiment, the inboard-side bearing 44 is accommodated in a recess 31 a provided on the inboard-side end surface of the large-diameter intermediate gear 31, thereby positioning the bearing 44 as much as possible. It is close to the outboard side. In addition, regarding the output shaft 38, in this embodiment, the outboard side rolling bearing 47 is accommodated in a recess 34 a provided on the end face of the output gear 34, thereby allowing the output gear 34 to be outboard as much as possible. It is close to the side.

  Further, as shown in FIG. 1, in the reduction gear unit B, the input gear 30 and the large-diameter intermediate gear 31 mesh with each other, and the small-diameter intermediate gear 32 coaxial with the large-diameter intermediate gear 31 and the idler gear 33 mesh with each other. The idler gear 33 and the output gear 34 are meshed with each other. At this time, the number of teeth of the large diameter intermediate gear 31 is larger than the number of teeth of either the input gear 30 or the small diameter intermediate gear 32, and the number of teeth of the output gear 34 is larger than the number of teeth of the small diameter intermediate gear 32. Is set. With the above configuration, the reduction gear unit B has a speed reduction structure that reduces the rotational kinetic force input from the motor rotation shaft 25 in two stages, and includes the input gear 30 and the output gear 34, the large diameter intermediate gear 31, and the small diameter intermediate gear. 32 and the idler gear 33 constitute a power transmission path from the input shaft 35 to the output shaft 38.

  Further, as shown in FIG. 2, the rotation center of the intermediate shaft 36 is between the rotation center O1 of the input shaft 35 of the speed reducer part B and the rotation center O4 of the output shaft 38 forming the axle of the wheel bearing part C. O2 and the rotation center O3 of the idler gear shaft 37 are arranged so as to be bent. Specifically, the rotation centers O <b> 1 to O <b> 4 are arranged along the inner peripheral surface of the wheel housing 15, so that the outer peripheral contour of the in-wheel motor drive device 21 is made compact.

  In this embodiment, the idler gear 33 is disposed on the outboard side with respect to the large-diameter intermediate gear 31 as shown in FIG. Further, outer rings of a pair of bearings (here, rolling bearings) 48 and 49 are attached to the first divided casing 22a on the outboard side via an attachment portion 39, and the inner rings of the bearings 48 and 49 are connected to an idler gear shaft 37. The idler gear 33 is rotatably supported with respect to the casing 22. At this time, a concave portion 33a is provided on the end surface of the idler gear 33 on the outboard side, and the idler gear 33 is disposed so that the pair of bearings 48 and 49 are accommodated in the concave portion 33a. The gear 33 can be arranged at a position overlapping the large-diameter intermediate gear 31 (see FIG. 2).

  When the idler gear 33 meshes with the small-diameter intermediate gear 32 and the output gear 34, for example, when viewed from the vehicle width direction, the rotation center of the idler gear 33 (that is, the rotation center O3 of the idler gear shaft 37) and the small-diameter intermediate gear 33, for example. Even if the rotation center of the gear 32 (that is, the rotation center O2 of the intermediate shaft 36) and the rotation center of the output gear 34 (that is, the rotation center O4 of the output shaft 38) are located in a line. Good. In FIG. 2, from the viewpoint of suppressing uneven wear due to sliding contact between the same teeth, the number of teeth of the small-diameter intermediate gear 32 and the number of teeth of the idler gear 33 are slightly different so that the respective rotation centers O2 to O4 are substantially linear. They are arranged so that they are in a line.

  The pitch circle diameter of the idler gear 33 is arbitrary, but when considering reduction of the outer diameter dimension (virtual circumscribed circle dimension) of the in-wheel motor drive device 21, for example, the idler gear 33 and the power transmission paths O1 to O1. A gear that is larger than the pitch circle diameter of the gear (here, the small-diameter intermediate gear 32) meshed on the side close to the input shaft 35 on O4 and meshed on the side close to the output shaft 38 on the power transmission path O1 to O4 (here, It can be set smaller than the pitch circle diameter of the output gear 34).

  Further, as the input gear 30, the intermediate gears 31, 32, the idler gear 33, and the output gear 34 constituting the speed reducer part B, known types of gears can be applied. Gears are used. 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. Each gear module can be arbitrarily set in consideration of the gear meshing ratio and the limit rotational speed, but when considering the gear meshing ratio and the limit rotational speed, for example, about 1 to 3 It is possible to set.

  In this embodiment, the wheel bearing portion C is constituted by an inner ring rotation type wheel bearing 50 (see FIG. 1). The wheel bearing 50 includes a pair of bearing inner rings 51 and 52 disposed on the outer periphery of the output shaft 38 as an axle, a bearing outer ring 53 disposed on the outer periphery of the bearing inner rings 51 and 52, a bearing inner ring 51, 52, a double row inner race 54 formed on the outer peripheral surface of the bearing 52, a double row outer race 55 formed on the inner peripheral surface of the bearing outer ring 53, and a plurality of rolling elements disposed between the inner race 54 and the outer race 55. This is a double-row angular contact ball bearing provided with a ball 56 and a cage (not shown) for holding each ball 56.

  Further, the bearing outer ring 53 is provided with a flange portion 57 extending radially outward, and the flange portion 57 is connected to a hub attachment 101 of a suspension connecting member 100 described later by a bolt 58. The hub attachment 101 is connected to the casing 22 (the first divided casing 22a on the outboard side) with a bolt 59 at a position different from the connection position with the flange portion 57 in the circumferential direction, for example. As a result, the hub attachment 101 is fixed to the in-wheel motor drive device 21.

  On the other hand, the bearing inner ring 51 on the outboard side of the pair of bearing inner rings 51 and 52 is fixed to the outer periphery of the output shaft 38 as an axle by spline fitting. The bearing inner ring 51 is provided with a flange portion 60 extending radially outward. The flange portion 60 is a flange for mounting a wheel. For example, as shown in FIG. 1, the brake disc 104 and the rear wheel 14 ( A wheel 105 shown in FIG. 6 is attached with a hub bolt 61. With the above configuration, the rotational driving force from the motor unit A is obtained. It is transmitted to the rear wheel 14 while being decelerated via the reduction gear part B.

  In the in-wheel motor drive device 21, for cooling the motor part A and lubricating and cooling the speed reducer part B, lubricating oil is supplied to each part by a rotary pump (not shown). The inside of the wheel bearing 50 is lubricated with grease.

  Since the in-wheel motor drive device 21 is housed inside the wheel housing 15 (see FIGS. 2 and 6) and affects the unsprung load, it is essential to reduce the size and weight. By combining the above-described parallel shaft gear type reduction gear unit B with the motor unit A, it is possible to use a low-torque, high-rotation type and small motor 26. Thereby, the compact in-wheel motor drive device 21 can be realized, and the electric vehicle 11 excellent in running stability and NVH characteristics can be obtained while suppressing the unsprung weight.

  Next, the advantage of disposing the idler gear 33 on the power transmission paths O1 to O4, which is a characteristic configuration of the present invention, is the in-wheel motor drive device 71 without the idler gear 33 (FIGS. 3 and 4). This will be explained by comparing with the above.

  3 is a longitudinal sectional view of the in-wheel motor drive device 71 in which the idler gear 33 shown in FIG. 1 and the like is missing, and FIG. 4 is a front view including a partial cross-section of the in-wheel motor drive device 71 shown in FIG. FIG. As shown in FIGS. 3 and 4, when there is no idler gear 33 and the small-diameter intermediate gear 32 and the output gear 34 mesh directly, the distance between the large-diameter intermediate gear 31 and the output shaft 38 becomes very close. . Therefore, depending on the required pitch circle diameter (number of teeth) of the large-diameter intermediate gear 31, as shown in FIG. 3, the inboard side bearing 46 that supports the output shaft 38 is further shifted to the inboard side. Need arises. However, in this type of drive device 21, as shown in FIG. 4, the rotation centers O 1, O 2, O 4 of the shafts 31, 36, 38 are bent along the inner peripheral surface of the wheel housing 15. Therefore, it is necessary to further shift the motor 26 (for example, the stator 23) toward the inboard side in order to avoid interference with the bearing 46 by shifting the bearing 46 toward the inboard side. In contrast, in the present invention, as shown in FIG. 1, the idler gear 33 is disposed on the power transmission paths O1 to O4, so that the idler gear 33 meshes between the small-diameter intermediate gear 32 and the output gear 34. Thus, the distance between the rotation center O2 of the intermediate shaft 36 and the rotation center O4 of the output shaft 38 can be increased (see FIGS. 2 and 4). Therefore, the large-diameter intermediate gear 31 can be increased in diameter without shifting the peripheral elements (here, the bearings 46) of the output shaft 38 and the motor 26 to the inboard side. It is possible to achieve both high output and compactness.

  Further, as an advantage of disposing the idler gear 33 on the power transmission paths O1 to O4, the layout around the in-wheel motor drive device 21 can be suitably changed. Hereinafter, description will be made mainly with reference to FIGS.

  7 and 8 are a front view and a side view showing a state where the suspension connecting member 100 is attached to the in-wheel motor drive device 71. FIG. As shown in FIGS. 7 and 8, the suspension connecting member 100 (sometimes referred to as a knuckle) has a structure that can be divided in the vehicle width direction, and includes an outboard side member (hub attachment 101), an inboard The in-wheel motor drive device 71 is accommodated between the side member (suspension bracket 102). The hub attachment 101 is connected to the in-wheel motor drive device 71, and the suspension bracket 102 is connected to the suspension device 16 via the strut 17. Therefore, by connecting the hub attachment 101 and the suspension bracket 102, the in-wheel motor drive device 71 and the wheels 14 attached to the drive device 71 are connected to the suspension device 16.

  Here, in order to connect the hub attachment 101 and the suspension bracket 102, as shown in FIG. 8, the hub attachment 101 and the suspension bracket 102 are connected to each other around the in-wheel motor driving device 71, respectively. It is necessary to reach to the outside of the drive device 71 in the radial direction. However, in the in-wheel motor drive device 71 configured as shown in FIG. 3, since the small-diameter intermediate gear 32 and the output gear 34 are directly meshed with each other, the rotational center O2 of the small-diameter intermediate gear 32 is input. It must be arranged between the rotation center O1 of the gear 30 and the rotation center O4 of the output gear 34 (the side closer to the strut 17 in comparison with FIG. 2). In this case, as shown in FIG. 4, the upper portion of the axle (output shaft 38) is blocked by the large-diameter intermediate gear 31, and the surplus space S1 is in a very narrow state. As a result, the coupling portion 103 between the hub attachment 101 and the suspension bracket 102 must be provided in this narrow surplus space S1 (see FIG. 7), and the thickness dimension of the coupling portion 103 is restricted, so that the strength and rigidity are limited. There was a risk of problems.

  On the other hand, according to the in-wheel motor drive device 21 according to the present invention, the idler gear 33 is disposed at the position where it meshes with the small-diameter intermediate gear 32 and the output gear 34, and therefore, as shown in FIG. The large-diameter intermediate gear 31 can be arranged on the side far from the strut 17 by taking a large distance between O4 and O4. As a result, as shown in FIG. 2, the surplus space S <b> 2 expands above the axle (output shaft 38), so that a coupling space between the hub attachment 101 and the suspension bracket 102 can be increased. As a result, the problems of strength and rigidity are solved, and the suspension connecting member 100 (hub attachment 101, suspension bracket 102) as a peripheral member can be designed without being affected by the external shape of the in-wheel motor drive device 21. Can be done.

  Hereinafter, although the first embodiment of the present invention has been described, the in-wheel motor driving device 21 is not limited to the above-described embodiment, and can take any form within the scope of the present invention.

  For example, in the first embodiment, the case where a pair of rolling bearings 48 and 49 is employed as the bearing of the idler gear 33 has been described. Of course, other types of bearings may be employed. FIG. 9 shows a longitudinal sectional view of an in-wheel motor drive device 121 according to the second embodiment of the present invention. As shown in FIG. 9, the in-wheel motor drive device 21 according to the present embodiment employs a needle bearing 62 as a bearing that rotatably supports the idler gear 33 instead of the pair of rolling bearings 48 and 49. Yes. The idler gear 33 has a structure that meshes with the small-diameter intermediate gear 32 and the output gear 34 that are opposed to each other through the rotation center O3 (see FIG. 2), so that the radial component and the thrust component of the force acting on the idler gear 33 are reduced. Offset or diminished. Therefore, even when the rolling bearings 48 and 49 are employed, a type of bearing having a small ball diameter can be employed, and the support structure of the idler gear 33 can be miniaturized as much as possible. From the above circumstances, as shown in FIG. 9, as long as it is for supporting the idler gear 33, even the needle bearing 62 having a load capacity not so large can be adopted without any problem. Further downsizing is possible.

  In the above embodiment, the case where the idler gear 33 is disposed between the small-diameter intermediate gear 32 and the output gear 34 has been described, but of course, it is meshed with any two gears on the power transmission paths O1 to O4. It is also possible to arrange the idler gear 33 at the position. Since the positions of at least the large-diameter intermediate gear 31 and the small-diameter intermediate gear 32 are changed by the arrangement, the idler gear 33 having an appropriate size is arranged at an appropriate position as necessary, so that the in-wheel motor drive device 21 is arranged. It is possible to appropriately reset the layout of each element or the layout of peripheral elements of the in-wheel motor drive device 21 such as the suspension connecting member 100.

  Moreover, in the said embodiment, the case where the intermediate gear unit which integrally provided two intermediate gears (large diameter intermediate gear 31 and small diameter intermediate gear 32) in the intermediate shaft 36 was integrated in the reduction gear part B was illustrated. However, of course, the present invention can also be applied to the case where the reduction gear unit B is configured by incorporating two or more intermediate gear units. In that case, it is desirable that the idler gear 33 is disposed at a position where the idler gear 33 meshes with the final-stage small-diameter intermediate gear and the output gear 34.

DESCRIPTION OF SYMBOLS 11 Electric vehicle 12 Chassis 13 Front wheel 14 Rear wheel 15 Wheel housing 16 Suspension device 17 Struts 21, 71, 121 In-wheel motor drive device 22 Casing 23 Stator 24 Rotor 25 Motor rotating shaft 26 Motor 30 Input gear 31 Large diameter intermediate gear 32 Small diameter Intermediate gear 33 Idler gear 34 Output gear 35 Input shaft 36 Intermediate shaft 37 Idler gear shaft 38 Output shaft 40-49 Bearing 50 Wheel bearings 51, 52 Bearing inner ring 53 Bearing outer ring 57 Flange portion 60 Flange portion 62 Needle bearing 100 Suspension connecting member DESCRIPTION OF SYMBOLS 101 Hub attachment 102 Suspension bracket 103 Connection part 104 Brake disc 105 Wheel A Motor part B Reducer part C Wheel bearing part O1, O2, O3, O4 Rotation center S1, S2 Extra space

Claims (6)

In an in-wheel motor drive device comprising a motor unit, a wheel bearing unit, and a speed reducer unit that decelerates the rotation of the motor unit and transmits it to the wheel bearing unit.
The speed reducer unit includes an input shaft to which rotational driving force from the motor unit is input, an output shaft to which the rotational driving force is output, at least one intermediate shaft parallel to the input shaft and the output shaft, and An input gear provided on the input shaft, an output gear provided on the output shaft, and a large-diameter intermediate gear and a small-diameter intermediate gear provided on the intermediate shaft and having different pitch circle diameters,
The input gear and the output gear, and the large-diameter intermediate gear and the small-diameter intermediate gear constitute a power transmission path from the input shaft to the output shaft,
An in-wheel motor drive device, wherein an idler gear is disposed on the power transmission path.   A pitch circle diameter of the idler gear is larger than a pitch circle diameter of a gear meshing with the idler gear on the side close to the input shaft on the power transmission path, and the output shaft on the idler gear and the power transmission path. The in-wheel motor drive device according to claim 1, wherein the in-wheel motor drive device is smaller than a pitch circle diameter of a gear meshing on a side close to the gear. The idler gear meshes with the small-diameter intermediate gear and the output gear;
The in-wheel motor according to claim 1 or 2, wherein when viewed from the vehicle width direction, the rotation center of the idler gear, the rotation center of the small-diameter intermediate gear, and the rotation center of the output gear are arranged in a straight line. Drive device.   The in-wheel motor drive device according to any one of claims 1 to 3, wherein the idler gear is positioned on an outboard side of the vehicle with respect to the large-diameter intermediate gear. A casing for accommodating at least the speed reducer,
The in-wheel motor drive device according to any one of claims 1 to 4, wherein the shaft of the idler gear is supported by a bearing attached to the casing on an outboard side of the vehicle.   The intermediate shaft is one, the large-diameter intermediate gear of the one intermediate shaft and the input gear mesh with each other, and the small-diameter intermediate gear of the one intermediate shaft and the idler gear mesh with each other. The in-wheel motor drive device as described in any one.

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