JP2008174144A - In-wheel motor system and electric vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enhance a hold loading property of a drive wheel by suppressing variation of tire ground-contact force of the drive wheel. <P>SOLUTION: An annular vertically movable plate 33 is provided on a frame dress up part movably in a vertical direction, and a stator mounting part mounted with a motor stator of an electric motor is provided on an outer peripheral side of the vertically movable plate 33. An annular rotation plate is rotatably provided on the vertically movable plate 33, and a motor rotor of the electric motor is mounted to an inner peripheral surface of the rotation plate. A flexible coupling for eccentrically connecting the rotation plate and a wheel is arranged at an inner side of the wheel 5, and springs 55, 57 for resiliently supporting the vertically movable plate 33 relative to the frame dress up part are provided, and a piezo-actuator 59 for dampening vertical vibration of the vertically movable plate 33 relative to the frame dress up part is provided between the frame dress up part and the vertically movable plate 33. A plurality of piezo-electric bodies 59a for expanding/contracting the piezo-actuator 59 in a vertical direction according to an applied voltage are superposed. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an in-wheel motor system in which an outer rotor type electric motor is disposed inside a wheel of a drive wheel in an electric vehicle, and an electric vehicle.

  In recent years, various developments have been made on in-wheel motor systems. The in-wheel motor systems according to the prior art shown in Patent Document 1 and Patent Document 2 will be briefly described as follows.

  In other words, a knuckle as an undercarriage component in an electric vehicle is provided with an annular vertical movement plate that is movable in the vertical direction. The vertical movement plate has a stator mounting portion on the outer peripheral side. A motor stator of an electric motor is attached to the stator attachment portion. Further, an annular rotary plate is rotatably provided on the vertical movement plate, and a motor rotor of an electric motor is attached to the rotary plate.

  A flexible coupling that couples the rotating plate and the wheel so as to be eccentric is disposed inside the wheel of the drive wheel in the electric vehicle. The knuckle is indirectly provided with a spring that elastically supports the vertical movement plate with respect to the knuckle, and the vertical vibration with respect to the knuckle of the vertical movement plate is provided between the knuckle and the vertical movement plate. An oil damper that attenuates the vibration is provided.

  Therefore, when the rotating plate is rotated integrally with the motor rotor by supplying current to the electric motor, the wheel is rotated through the flexible coupling, in other words, the driving wheel is rotated, and the electric vehicle is rotated. It can be run (general action of in-wheel motor system).

In addition to the general function of the in-wheel motor system, the vertical movement plate is elastically supported by the knuckle by a spring, and an oil damper is provided between the knuckle and the vertical movement plate, so the electric motor A floating mount can be mounted on the lower part of the vehicle spring. As a result, while the electric motor functions as a dynamic vibration absorber while the electric vehicle is running, the vertical vibration of the vertical movement plate with respect to the knuckle of the vertical movement plate by the cooperation of the oil damper and the spring, in other words, the electric motor The vibration in the vertical direction with respect to the knuckle can be suppressed.
JP 2005-28923 A JP 2005-35223 A

  By the way, in the in-wheel motor system according to the above-described prior art, the frequency range in which the damping action is exerted is determined by the characteristics of the oil damper. The vibration in the vertical direction of the electric motor cannot be controlled over a range. In addition, the oil damper itself is heavy and the electric motor cannot fully function as a dynamic vibration absorber. For this reason, there is a problem that fluctuations in the tire ground contact force of the drive wheels cannot be sufficiently suppressed, and it is not easy to improve the hold loadability of the drive wheels.

  Therefore, an object of the present invention is to provide an in-wheel motor system and an electric vehicle having a novel configuration that can solve the above-described problems.

  A first feature of the present invention (feature of the invention described in claim 1) is an in-wheel motor system in which an outer rotor type electric motor is disposed inside a wheel of a drive wheel in an electric vehicle. And an annular vertical movement plate having a stator mounting portion on which the motor stator of the electric motor is mounted on the outer peripheral side, and rotatably provided on the vertical movement plate. An annular rotating plate to which a motor rotor of the electric motor is attached; a flexible coupling that is disposed inside the wheel and that connects the rotating plate and the wheel in an eccentric manner; and A spring that elastically supports the part, and is provided between the suspension part and the vertical movement plate. Is stretchable configured in the vertical direction in accordance with an applied voltage, and subject matter that anda piezoelectric actuator for damping vibrations in the vertical direction relative to the chassis parts of the vertically movable plate.

  It should be noted that “provided” in the description of the specification and claims includes not only being provided directly but also indirectly provided via an intermediate member.

  According to the first feature, when the rotating plate is rotated integrally with the motor rotor by supplying current to the electric motor, the wheel is rotated through the flexible coupling, in other words, The drive wheel can be rotated to run the electric vehicle (general operation of the in-wheel motor system).

  In addition to the general operation of the in-wheel motor system, the spring is elastically supported by the spring with respect to the undercarriage component, and the piezo is interposed between the undercarriage component and the vertical motion plate. Since the actuator is provided, the electric motor can be floating mounted on the lower part of the vehicle spring. Accordingly, while the electric vehicle is running, the electric motor functions as a dynamic vibration absorber, and the vertical vibration of the vertical movement plate with respect to the undercarriage component is achieved by the cooperation of the piezo actuator and the spring. In other words, it is possible to suppress the vertical vibration of the electric motor with respect to the suspension part.

  Here, since the piezo actuator is configured to be able to expand and contract in the vertical direction according to the applied voltage, the damping action by the piezo actuator can be reduced only by appropriately changing the magnitude and polarity of the applied voltage of the piezo actuator. The frequency range to be played can be expanded, and the vibration of the electric motor in the vertical direction can be suppressed over a wide frequency range by the cooperation of the piezo actuator and the spring while the electric vehicle is running. In addition, since the piezo actuator is lighter than an oil damper, the electric motor can sufficiently function as a dynamic vibration absorber.

  According to a second feature of the present invention (a feature of the invention described in claim 2), in addition to the first feature, the piezo actuator includes a plurality of piezoelectric bodies that expand and contract in the vertical direction according to an applied voltage. The gist of this is

  A third feature of the present invention (feature of the invention described in claim 3) is that an in-wheel motor system comprising the first feature or the second feature is provided in an electric vehicle that travels by rotational driving of a plurality of drive wheels. The gist is that each drive wheel is provided.

  According to the invention of any one of claims 1 to 3, the electric motor can be operated over a wide frequency range by the cooperation of the piezo actuator and the spring during the running of the electric vehicle. The vibration of the driving wheel can be sufficiently suppressed, so that the electric motor can sufficiently function as a dynamic vibration absorber. The hold loadability of the drive wheel can be improved.

  An embodiment of the present invention will be described with reference to FIGS. 1 to 3.

  Here, FIG. 1 is a perspective view showing a main part of the in-wheel motor system according to the embodiment of the present invention, FIG. 2 is a sectional view of the in-wheel motor system according to the embodiment of the present invention, and FIG. 1 is a schematic plan view of an electric vehicle according to an embodiment of the invention.

  As shown in FIGS. 2 and 3, the electric vehicle 1 according to the embodiment of the present invention is driven by the rotational drive of the four drive wheels 3, and is an outer rotor type inside the wheel 5 of the drive wheels 3. The in-wheel motor system 9 provided with the electric motor 7 is provided for each drive wheel 3. Hereinafter, the peripheral configuration of the in-wheel motor system 9 according to the embodiment of the present invention and the specific configuration of the in-wheel motor system 9 will be sequentially described.

  An axle 11 in the electric vehicle 1 is provided with a knuckle 13 as a suspension part, and a hub 15 is rotatably provided on the knuckle 13 via a bearing 17. The hub 15 is integrally provided with the wheel 5 described above. The wheel 5 is integrally provided on the outer periphery of the wheel disk 19 and the wheel disk 19 fixed to the hub 15, and is a driving wheel. And a wheel rim 23 to which three tires 21 can be assembled. The axle 11 is elastically supported on a body frame (not shown) of the electric vehicle 1 by a shock absorber 25.

  As shown in FIGS. 1 to 3, a guide member 29 is integrally provided on a support plate 27 that constitutes a part of the knuckle 13, and a slide bar 31 is provided on the guide member 29 in the vertical direction. The slide bar 31 is provided with an annular vertical movement plate 33 via a pair of brackets 35, 37. In other words, the support plate 27 is provided with an annular vertical movement plate 33 movably in the vertical direction via the guide member 29, the slide bar 31, and the pair of brackets 35 and 37. The vertical movement plate 33 has a stator mounting ring (stator mounting portion) 39 on the outer peripheral side, and a motor stator 7 s of the electric motor 7 is mounted on the outer peripheral surface of the stator mounting ring 39. . Further, an annular rotating plate 41 is rotatably provided on the stator mounting ring 39 via a bearing 43, and a motor rotor 7 r of the electric motor 7 is attached to the inner peripheral surface of the rotating plate 41. .

  A flexible coupling 45 that connects the rotating plate 41 and the wheel 5 in an eccentric manner is disposed inside the wheel 5, and this flexible coupling 45 is known as disclosed in JP-A-2006-1313. The specific configuration of the flexible coupling 45, which is a coupling, is as follows. That is, the rotary plate 41 is integrally provided with an annular knuckle side connection plate 47, and the wheel disk 19 is integrally provided with an annular disk side connection plate 49. An annular intermediate connection plate 51 is disposed between the knuckle side connection plate 47 and the disk side connection plate 49. The intermediate connection plate 51 is connected to the knuckle side connection plate 47 through a pair of first guide mechanisms (not shown) so as to be movable in a first direction parallel to the radial direction of the wheel disk 19. It is connected to the side connection plate 49 via a pair of second guide mechanisms 53 so as to be movable in a second direction orthogonal to the first direction.

  Between the bracket 35 and the upper part of the guide member 29 in the slide bar 31, an upper spring 55 is provided that elastically supports the vertical movement plate 33 with respect to the knuckle 13 from above, and the bracket 37 in the slide bar 31 is provided. A lower spring 57 that elastically supports the vertical movement plate 33 with respect to the knuckle 13 from below is provided between the lower portion of the guide member 29 and the guide member 29. A piezo actuator 59 is provided between the knuckle 13 and the vertical movement plate 33 via a pair of arms 61 and 63 for attenuating vertical vibration of the vertical movement plate 33 relative to the knuckle 13. The actuator 59 is formed by laminating a plurality of piezoelectric bodies 59a that expand and contract in the vertical direction according to the applied voltage. In other words, the actuator 59 can be expanded and contracted in the vertical direction according to the applied voltage.

  The operation and effect of the embodiment of the present invention will be described.

  When the rotating plate 41 is rotated integrally with the motor rotor 7r by supplying current to the electric motor 7, the wheel 5 is rotated via the flexible coupling 45, in other words, the driving wheel 3 is rotated. The electric vehicle 1 can be driven (general operation of the in-wheel motor system 9).

  In addition to the general operation of the in-wheel motor system 9, the upper and lower motion plates 33 are elastically supported by the upper spring 55 and the lower spring 57 with respect to the knuckle 13 from above and below. Since the piezo actuator 59 is provided between the motor 33 and the electric motor 7, the electric motor 7 can be floating mounted on the lower part of the vehicle spring. As a result, the knuckle of the vertical movement plate 33 is obtained by the cooperation of the piezo actuator 59 and the spring (the upper spring 55 and the lower spring 57) while the electric motor 7 functions as a dynamic vibration absorber while the electric vehicle 1 is traveling. 13, in other words, vibrations in the vertical direction of the knuckle 13 of the electric motor 7 can be suppressed.

  Here, since the piezo actuator 59 is configured to be able to expand and contract in the vertical direction according to the applied voltage, the damping action by the piezo actuator 59 can be achieved only by appropriately changing the magnitude and polarity of the applied voltage of the piezo actuator 59. The frequency range to be played can be expanded, and the vertical vibration of the electric motor 7 can be suppressed over a wide frequency range by the cooperation of the piezo actuator 59 and the springs 55 and 57 while the electric vehicle 1 is traveling. . Further, since the piezo actuator 59 is lighter than the oil damper, the electric motor 7 can sufficiently function as a dynamic vibration absorber.

  As described above, according to the embodiment of the present invention, while the electric vehicle 1 is traveling, the vibration of the electric motor 7 in the vertical direction is suppressed over a wide frequency range by the cooperation of the piezo actuator 59 and the springs 55 and 57. In addition, since the electric motor 7 can sufficiently function as a dynamic vibration absorber, the fluctuation of the tire ground contact force of the drive wheels 3 can be sufficiently suppressed, and the hold loading property of the drive wheels 3 can be suppressed. Can be improved.

  In addition, this invention is not restricted to description of the above-mentioned embodiment, In addition, it can implement in a various aspect. Further, the scope of rights encompassed by the present invention is not limited to these embodiments.

It is a perspective view which shows the principal part of the in-wheel motor system which concerns on embodiment of this invention. It is sectional drawing of the in-wheel motor system which concerns on embodiment of this invention. 1 is a schematic plan view of an electric vehicle according to an embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Electric vehicle 3 Drive wheel 5 Wheel 7 Electric motor 7r Motor rotor 7s Motor stator 9 In-wheel motor system 13 Knuckle 15 Hub 27 Support plate 29 Guide member 31 Slide bar 33 Vertical motion plate 39 Stator attachment ring 41 Rotation plate 45 Flexible coupling 55 Upper spring 57 Lower spring 59 Piezo actuator 59a Piezoelectric body

Claims (3)

In an in-wheel motor system in which an outer rotor type electric motor is arranged inside a wheel of a drive wheel in an electric vehicle,
An annular vertical movement plate having a stator mounting portion that is provided on the undercarriage part in the electric vehicle so as to be movable in the vertical direction and on which the motor stator of the electric motor is mounted on the outer peripheral side;
An annular rotating plate provided rotatably on the vertical movement plate, to which a motor rotor of the electric motor is attached;
A flexible coupling that is disposed inside the wheel and connects the rotating plate and the wheel in an eccentric manner;
A spring that elastically supports the vertical movement plate with respect to the underbody part;
A piezo actuator provided between the undercarriage component and the vertical movement plate, configured to be able to expand and contract in the vertical direction according to an applied voltage, and damps the vertical vibration of the vertical movement plate with respect to the undercarriage component; ,
An in-wheel motor system comprising:   The in-wheel motor system according to claim 1, wherein the piezo actuator is formed by stacking a plurality of piezoelectric bodies that expand and contract in the vertical direction according to an applied voltage. In an electric vehicle that travels by rotating a plurality of drive wheels,
An electric vehicle comprising the in-wheel motor system according to claim 1 for each drive wheel.

Images