WO2019065712A1

WO2019065712A1 - In-wheel motor drive device

Info

Publication number: WO2019065712A1
Application number: PCT/JP2018/035632
Authority: WO
Inventors: 丹丹崔; 四郎田村
Original assignee: Ntn株式会社
Priority date: 2017-09-27
Filing date: 2018-09-26
Publication date: 2019-04-04
Also published as: JP2019059394A

Abstract

An in-wheel motor drive device 21 comprises: an electric motor unit A having a motor rotary shaft 25; a reduction gear unit B for decelerating and outputting the rotation of the electric motor unit A; and a wheel bearing unit C for transmitting the output from the reduction gear unit B to drive wheels 14. The reduction gear unit B comprises a detection device 37 for detecting the rotation speed of the motor rotary shaft 25. The detection device 37 is disposed farther to the outboard side than the electric motor unit A.

Description

In-wheel motor drive

The present invention relates to an in-wheel motor drive device in which an electric motor portion and a wheel bearing portion are connected via a reduction gear portion.

Since the in-wheel motor drive is housed inside the wheel, it becomes the unsprung weight of the vehicle. Since the increase in unsprung weight deteriorates the ride quality of the vehicle, reducing the size and weight of the in-wheel motor drive is an important requirement. Since the output torque of the electric motor is proportional to the size and weight of the electric motor, a large motor is required to generate the torque necessary for driving the vehicle by the motor alone. Therefore, a means to miniaturize is used by using an electric motor in combination with a reduction gear.

Patent Document 1 discloses an in-wheel motor in which an electric motor portion (motor) having a rotor shaft, a reduction mechanism (a reduction gear mechanism and a reduction planetary gear), and a wheel bearing portion having an output shaft are accommodated in a casing. A drive is disclosed. This in-wheel motor drive device includes a detection device (resolver device) that detects the rotational position of the rotor shaft. The detection device is provided at a position on the inboard side (the center side of the vehicle) of the motor (see FIG. 5 and paragraphs 0064 and 0065 of the same document).

Patent No. 5601260

In the conventional in-wheel motor drive device, since the detection device is provided on the inboard side of the motor, the motor protrudes larger than the wheel width and protrudes to the vehicle body side. In this case, the motor may interfere with the suspension system of the vehicle, which needs to be avoided. However, trying to develop a new dedicated suspension system for avoiding interference results in a significant cost increase including vehicle design. Therefore, it is desirable to constitute an in-wheel motor drive so that projection to the inboard side of an electric motor part may be reduced as much as possible.

The present invention has been made in view of the above circumstances, and provides an in-wheel motor drive device capable of reducing the inboard protrusion amount of the electric motor portion as much as possible and preventing interference with the suspension device of the vehicle. The purpose is to

The present invention is intended to solve the above problems, and an electric motor unit having a motor rotation shaft, a reduction gear unit that decelerates and outputs the rotation of the electric motor unit, and an output from the reduction gear unit In an in-wheel motor drive provided with a wheel bearing unit for transmitting to a drive wheel, the reduction gear unit includes a detection device for detecting the number of rotations of the motor rotation shaft, and the detection device is configured by the electric motor unit It is also characterized in that it is placed on the outboard side.

According to this configuration, by disposing the detection device on the outboard side of the electric motor unit, the amount of protrusion of the electric motor unit to the inboard side can be reduced compared to the case where the detection device is disposed on the inboard side. . Thus, interference between the electric motor unit and the suspension device of the vehicle can be effectively prevented.

In the in-wheel motor drive device described above, the reduction gear portion includes an input shaft integrated coaxially with the motor rotation shaft on the outboard side of the electric motor portion, and the detection device is provided at the input shaft It is desirable to be provided coaxially at the outboard end.

According to this configuration, since the input shaft of the reduction gear unit is integrated with the motor rotation shaft, the rotation number of the motor rotation shaft can be detected by detecting the number of rotations of the input shaft with the detection device. Further, by providing the detection device at the outboard side end of the input shaft, the amount of protrusion of the electric motor section to the inboard side is not increased.

In the in-wheel motor drive device of the above configuration, the input shaft preferably includes an input gear between the detection device and the electric motor unit. According to this configuration, it is possible to secure a space for arranging the detection device on the outboard side of the input gear.

In the in-wheel motor drive device configured as described above, the reduction gear portion includes an intermediate shaft between the wheel bearing portion and the input gear, and the intermediate shaft is an input-side intermediate gear engaged with the input gear. And the output-side intermediate gear engaged with the wheel bearing portion, and the input-side intermediate gear may be disposed closer to the inboard side than the output-side intermediate gear.

If the input-side intermediate gear is disposed on the outboard side of the output-side intermediate gear, the input gear engaged with the input-side intermediate gear is also restricted in position, which also restricts the arrangement space of the detection device. . In the present invention, by arranging the input-side intermediate gear closer to the inboard side than the output-side intermediate gear, the detection device can be arranged on the outboard side of the input gear without being restricted by the input-side intermediate gear. Space can be secured.

Further, an in-wheel motor drive device according to the present invention includes a casing in which the electric motor portion, the reduction gear portion, the wheel bearing portion, and the detection device are accommodated, and the casing is configured to detect the electric motor. It is desirable to have an opening for receiving the device therein and a lid closing the opening.

According to this configuration, by forming the opening for the detection device in the casing, the assembly operation and the adjustment operation of the detection device can be easily performed. Further, by closing the opening with the lid, damage to the detection device due to the collision of foreign matter from the outside can be reliably prevented.

According to the present invention, the inboard protrusion amount of the electric motor unit can be reduced as much as possible, and interference with the suspension system of the vehicle can be prevented.

It is a sectional view showing an in-wheel motor drive concerning a first embodiment. It is an expanded sectional view showing an important section of an in-wheel motor drive. It is sectional drawing which shows the in-wheel motor drive device which concerns on 2nd embodiment. It is a top view which shows schematic structure of the electric vehicle carrying an in-wheel motor drive device. FIG. 5 is a rear sectional view showing the electric vehicle of FIG. 4;

The in-wheel motor drive device which concerns on 1st embodiment of this invention is demonstrated based on FIG.1, FIG.2, FIG.4 and FIG. First, an electric vehicle equipped with the in-wheel motor drive device of the present embodiment will be described based on FIGS. 4 and 5. FIG. 4 is a schematic plan view of the electric vehicle 11 equipped with the in-wheel motor drive device 21, and FIG. 5 is a schematic cross-sectional view of the electric vehicle 11 as viewed from the rear.

As shown in FIG. 4, the electric vehicle 11 includes a chassis 12, a front wheel 13 as a steered wheel, a rear wheel 14 as a drive wheel, and an in-wheel motor drive device 21 for transmitting driving force to the rear wheel 14. Equip. As shown in FIG. 5, the rear wheel 14 is housed inside the wheel housing 15 of the chassis 12 and fixed to the lower part of the chassis 12 via a suspension system (suspension) 16.

The suspension device 16 supports the rear wheel 14 by suspension arms extending leftward and right, and absorbs a vibration that the rear wheel 14 receives from the ground and suppresses a vibration of the chassis 12 by a strut including a coil spring and a shock absorber. A stabilizer that suppresses the inclination of the vehicle body at the time of turning or the like is provided at the connection portion of the left and right suspension arms. The suspension device 16 is of 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 unevenness of the road surface and efficiently transmit the driving force of the rear wheel 14 to the road surface.

The electric vehicle 11 eliminates the need to provide a motor, a drive shaft, a differential gear mechanism, etc. on the chassis 12 by providing in-wheel motor drive devices 21 for driving the left and right rear wheels 14 inside the wheel housing 15 Therefore, the cabin space can be widely secured, and the rotation of the left and right rear wheels 14 can be controlled, respectively.

Next, the structure of the in-wheel motor drive device 21 is demonstrated based on FIG.1 and FIG.2. FIG. 1 shows a cross-sectional view of the in-wheel motor drive device 21. As shown in FIG. FIG. 2 is an enlarged sectional view of an essential part of the in-wheel motor drive device 21. As shown in FIG. In the following description, in a state where the in-wheel motor drive device 21 is mounted on a vehicle, the side closer to the outer side of the vehicle is referred to as the outboard side, and the side closer to the center is referred to as the inboard side.

As shown in FIG. 1, the in-wheel motor drive device 21 includes an electric motor unit A that generates a driving force, a reduction gear unit B that decelerates and outputs the rotation of the electric motor unit A, and a reduction gear unit B And a wheel bearing C for transmitting an output to a rear wheel 14 as a driving wheel. The electric motor unit A, the reduction gear unit B, and the wheel bearing unit C are accommodated or attached to the casing 22 respectively. The casing 22 may be an integral structure as shown in FIG. 1 or a divisible structure.

The electric motor unit A includes a stator 23 fixed to the casing 22, a rotor 24 disposed so as to face the radially inner side of the stator 23 with a gap, and a radially inner side of the rotor 24 and is integral with the rotor 24. It is comprised by the radial gap type electric motor provided with the motor rotating shaft 25 which rotates. The motor rotation shaft 25 can rotate at a high speed of about ten thousand and several thousand revolutions per minute. The stator 23 is constituted by winding a coil 23b around a magnetic core 23a, and the rotor 24 is constituted by a permanent magnet or the like. An end (right side in FIG. 1) of the motor rotation shaft 25 on one side in the axial direction is rotatably supported by the rolling bearing 41 with respect to the casing 22.

The reduction gear portion B includes an input gear 29, an input-side intermediate gear 31 and an output-side intermediate gear 32 as intermediate gears, and a final output gear 34. The input gear 29 integrally has an input shaft 30. The input shaft 30 is coaxially integrated with the motor rotation shaft 25. In the present embodiment, the input shaft 30 and the motor rotation shaft 25 are integrally configured by a single shaft member. That is, the motor rotating shaft 25 is configured at the inboard side of a single shaft member, and the input shaft 30 is configured at the outboard side. The input side intermediate gear 31 and the output side intermediate gear 32 integrally have an intermediate shaft 33. The input side intermediate gear 31 is disposed closer to the inboard side than the output side intermediate gear 32. The final output gear 34 integrally has an output shaft 35.

The input shaft 30, the intermediate shaft 33 and the output shaft 35 are offset so as to be parallel to one another. The input shaft 30 is rotatably supported (double-supported) on the casing 22 by rolling bearings 42, the intermediate shaft 33 by rolling

bearings

43, 44, and the output shaft 35 by rolling

bearings

45, 46.

As shown in FIG. 1, in the reduction gear portion B, the input gear 29 and the input intermediate gear 31 are engaged (meshed), and the output intermediate gear 32 and the final output gear 34 are engaged (meshed). There is. The number of teeth of the input side intermediate gear 31 is larger than the number of teeth of the input gear 29 and the output side intermediate gear 32, and the number of teeth of the final output gear 34 is larger than the number of teeth of the output side intermediate gear 32. From the above configuration, a parallel shaft gear reducer configured to reduce rotational movement of the motor rotation shaft 25 in two steps is configured. The in-wheel motor drive device 21 is housed inside the wheel housing 15 (see FIG. 5) and serves as an unsprung load, so reduction in size and weight is essential. By combining the parallel shaft gear reducer with the electric motor, it becomes possible to use a small electric motor of low torque and high rotation type. For example, in the case of using a parallel shaft gear reducer having a reduction ratio of 11, the electric motor can be miniaturized by using an electric motor rotating at a high speed of about 10,000 to several thousand revolutions per minute. As a result, a compact in-wheel motor drive device 21 can be realized, and the unsprung weight can be suppressed to obtain the electric vehicle 11 excellent in traveling stability and NVH characteristics.

In the present embodiment, helical gears are used as the input gear 29, the input intermediate gear 31, the output intermediate gear 32, and the final output gear 34. The helical gear is effective in that the noise is quiet and the torque fluctuation is small because the number of meshing teeth simultaneously increases and the tooth contact is dispersed. Preferably, the module of each gear is set to about 1 to 3 in consideration of the gear ratio of the gear and the number of revolutions of the limit.

The reduction gear unit B includes a detection device 37 that detects the number of rotations of the motor rotation shaft 25 in the electric motor unit A. The detection device 37 is disposed on the outboard side of the electric motor unit A, more specifically, on the outboard side of the input gear 29 of the input shaft 30. In other words, the input gear 29 is disposed between the electric motor unit A and the detection device 37.

The detection device 37 is disposed at the outboard end of the input shaft 30. The detection device 37 is fixed to the inside of the casing 22 and the rotor 38 fixed to the small diameter portion 30a formed at the outboard side end of the input shaft 30, and at the outer periphery of the rotor 38 via a radial gap. It is comprised by the resolver provided with the stator 39 opposingly arranged. The rotor 38 is a rotor ring fitted to the outer peripheral surface of the small diameter portion 30 a so as to rotate integrally with the input shaft 30. The rotor 38 is rotationally locked to the small diameter portion 30 a of the input shaft 30 by, for example, key fitting. The detection device 37 can be disposed at any position as long as it is on the outboard side coaxial with the electric motor unit A.

Further, the rotor 38 is held from both sides in the axial direction by the shoulder surface 30 b formed on the input shaft 30 and the fixing means 40 disposed on one side of the rotor 38 in the axial direction, whereby the small diameter portion of the input shaft 30 is obtained. It is axially positioned with respect to 30a. The fixing means 40 includes a pressing member 40 a in contact with the end face of the rotor 38 and a bolt 40 b for fixing the pressing member 40 a to the input shaft 30. The pressing member 40a has, for example, a disk shape, and has a hole 40c through which the shaft portion of the bolt 40b can be inserted. The shaft portion of the bolt 40b is inserted into the hole 40c of the pressing member 40a, and is screwed into the screw hole 30c formed in the small diameter portion 30a of the input shaft 30, thereby fixing the pressing member 40a to the input shaft 30 Do. Thus, the rotor 38 is sandwiched by one surface of the pressing member 40 a and the shoulder surface 30 b of the input shaft 30.

The stator 39 includes a core 39a and a coil 39b wound around the outer peripheral surface of the core 39a. The core 39a is fixed to the inner peripheral surface of the casing 22 in a detent state, for example, by fixing pins arranged at a plurality of places separated in the circumferential direction. The coil 39b is wound around the core 39a via an insulating bobbin mounted on the core 39a.

The casing 22 has an opening 22a and a lid 22b closing the opening 22a at a part on the outboard side of the detection device 37. The opening 22 a functions as a storage port when assembling the in-wheel motor drive device 21 or functions as an inspection port for adjusting the detection device 37 after the in-wheel motor drive device 21 is assembled. . The opening 22a is formed in the casing 22 so as to open toward the outboard side. The lid 22b is detachably fixed to the opening 22a by bolts or other fixing means 22c. The lid 22b has a hole 22d through which the fixing means 22c can be inserted.

The wheel bearing portion C is configured of an inner ring rotation type wheel bearing 51. The wheel bearing 51 is a double-row angular contact ball bearing mainly composed of a hub wheel 60, an inner ring 52, an outer ring 53, balls 56 and a cage (not shown).

A flange portion 60a for wheel attachment is formed on the outer periphery of the hub wheel 60 on the outboard side, and the inner ring 52 is fitted and caulked and fixed to the small diameter step portion on the inboard side. After the wheel bearing 51 is assembled, the crimped portion 60 b fixes the inner ring 52 and applies a preload to the wheel bearing 51. An inner raceway surface 54 on the outboard side is formed on the outer periphery of the hub wheel 60, and an inner raceway surface 54 on the inboard side is formed on the outer periphery of the inner ring 52. A brake disc 62 and a wheel (not shown) are attached to the wheel attachment flange 60a via a bolt 70. The peripheral portion of the brake disc 62 is positioned on the outboard side of the lid 22 b so as to cover the lid 22 b of the casing 22. On the inner periphery of the outer ring 53, double rows of outer race surfaces 55 are formed corresponding to the inner race surface 54 of the hub wheel 60 and the inner race surface 54 of the inner ring 52. The output shaft 35 is spline-fitted to the hub wheel 60 and is coupled so as to be able to transmit torque.

The wheel bearing 51 and the casing 22 are coupled by an attachment 47. A portion of the attachment 47 is fastened and fixed to the casing 22 by a bolt 71, and the other portion is fixed to a flange portion formed on the outer periphery of the outer ring 53 (not shown). The attachment 47 is bolted and fixed to the bracket of the suspension device 16 (not shown).

In the in-wheel motor drive device 21, lubricating oil is supplied to each part by a rotary pump (not shown) for cooling of the electric motor and for lubrication and cooling of the reduction gear. The inside of the bearing for the wheel bearing 51 is lubricated by grease.

According to the in-wheel motor drive device 21 according to the present embodiment described above, by arranging the detection device 37 on the outboard side of the electric motor unit A, the detection device 37 is the inboard side of the motor rotation shaft 25 The amount of protrusion of the electric motor unit A to the inboard side can be reduced as much as possible, as compared to the case where the electric motor unit A is disposed at the end. Furthermore, since detection device 37 is disposed in the region between input gear 29 and brake disc 62, in-wheel motor drive device 21 increases its axial length by effectively utilizing this region. Configured without

Since the input shaft 30 of the reduction gear unit B is integrated coaxially with the motor rotation shaft 25 on the outboard side of the electric motor unit A, the rotational speed of the input shaft 30 is detected by the detection device 37, The rotation speed of the motor rotation shaft 25 can be detected. Further, by providing the detection device 37 at the outboard side end of the input shaft 30, the amount of protrusion of the electric motor portion A to the inboard side is not increased. Moreover, since the input shaft 30 includes the input gear 29 between the detection device 37 and the electric motor unit A, a space for disposing the detection device 37 closer to the outboard side than the input gear 29 can be secured.

Further, when the input side intermediate gear 31 is disposed on the outboard side with respect to the output side intermediate gear 32, the position of the input gear 29 engaged with the input side intermediate gear 31 is also restricted, whereby the detection device 37 The placement space of is also constrained. However, in the present embodiment, by arranging the input side intermediate gear 31 on the inboard side with respect to the output side intermediate gear 32, the input side intermediate gear 31 is not restricted by the input side intermediate gear 31. A space for arranging the detection device 37 can be secured.

Further, by forming the opening 22 a for the detection device 37 in the casing 22, the assembly work and maintenance work of the detection device 37 can be easily performed. In particular, after assembling the in-wheel motor drive device 21, the lid 22b can be removed, and the phase adjustment work of the rotor 38 in the detection device 37 can be efficiently performed through the opening 22a. Furthermore, the detection device 37 is protected by the lid 22b by closing the opening 22a with the lid 22b. In addition, the detection device 37 is also covered by the brake disc 62, thereby reliably preventing damage due to collision such as external stepping stones.

FIG. 3 is a cross-sectional view showing a second embodiment of the in-wheel motor drive device. In the first embodiment described above, although the motor rotation shaft 25 of the electric motor unit A and the input shaft 30 of the reduction gear unit B are integrated by a single shaft member, the in-wheel motor according to the present embodiment In the drive device 21, the motor rotation shaft 25 and the input shaft 30 connect separate shaft members, whereby the motor rotation shaft 25 and the input shaft 30 are coaxially integrated. That is, the input shaft 30 is coaxially connected to the motor rotation shaft 25 via the connecting portion 58 by spline fitting (including serration fitting).

Both ends of the motor rotation shaft 25 are supported at both ends by rolling

bearings

41 and 48. Further, both ends of the input shaft 30 are supported at both ends by rolling

bearings

42 and 49. The other configuration in this embodiment is the same as that of the first embodiment. The in-wheel motor drive device 21 which concerns on this embodiment has an effect similar to 1st embodiment.

In addition, this invention is not limited to the structure of the said embodiment, It is not limited to the effect mentioned above. The present invention can be variously modified without departing from the scope of the present invention.

Although the resolver is exemplified as the detection device 37 in the above embodiment, the present invention is not limited to this, and a Hall element or other sensor can be used for the detection device 37. Further, the detection device 37 may have a form in which a magnetic encoder or the like is used for the rotor 38. The stator 39 may be a semiconductor magnetic sensor.

In the above embodiment, the reduction gear unit B (parallel shaft gear reduction gear) having one intermediate shaft 33 is illustrated, but the invention is not limited thereto, and two or more intermediate shafts and corresponding input intermediate gears And the reduction gear part B may be comprised by the output side intermediate gear.

21 in-wheel motor drive device 22 casing 22a opening 22b lid 25 motor rotation shaft 29 input gear 30 input shaft 31 input intermediate gear 32 output intermediate gear 33 intermediate shaft 37 detection device A electric motor portion B reduction gear portion C wheel Bearing for

Claims

An in-wheel motor comprising: an electric motor unit having a motor rotation shaft; a reduction gear unit for decelerating and outputting rotation of the electric motor unit; In the drive,
The reduction gear unit includes a detection device that detects the number of rotations of the motor rotation shaft,
The said detection apparatus is arrange | positioned rather than the said electric motor part at the inboard side, The in-wheel motor drive device characterized by the above-mentioned.
The reduction gear unit includes an input shaft coaxially integrated with the motor rotation shaft on the outboard side of the electric motor unit,
The in-wheel motor drive according to claim 1, wherein the detection device is provided coaxially at an outboard side end of the input shaft.
The in-wheel motor drive according to claim 2, wherein the input shaft comprises an input gear between the detection device and the electric motor unit.
The reduction gear unit includes an intermediate shaft between the wheel bearing unit and the input gear.
The intermediate shaft includes an input-side intermediate gear engaged with the input gear, and an output-side intermediate gear engaged with the wheel bearing portion.
The in-wheel motor drive according to claim 3, wherein the input-side intermediate gear is disposed closer to the inboard side than the output-side intermediate gear.
A casing in which the electric motor unit, the reduction gear unit, the wheel bearing unit, and the detection device are accommodated;
The in-wheel motor drive device according to any one of claims 1 to 4, wherein the casing includes an opening for receiving the detection device therein, and a lid closing the opening.