JP4078290B2 - Vehicle suspension system - Google Patents

Description

  The present invention relates to a vehicle suspension apparatus including a motor that generates a damping force, and more particularly to improvement of durability of the vehicle suspension apparatus.

As a vehicle suspension device, a device including an electric motor that generates a damping force between an unsprung portion and an unsprung portion has been proposed. For example, the vehicle suspension device of Patent Document 1 includes a ball screw mechanism that converts a linear motion of a piston that is input from the outside into a rotational motion of a motor, thereby obtaining a damping capacity of a shock absorber using the motor. It is done.
JP 2002-219920 A (3rd page, FIG. 3)

  However, in the conventional technology, when the motor has a small capacity, when a large input is applied from the road surface to the unsprung portion, the countering damping force is small, so the motor is rapidly rotated. As a result, a large regenerative current flows through the motor, which may deteriorate the durability of the motor. Considering these points, it is conceivable to increase the capacity of the motor, but in that case, the inertia of the motor rotor increases and the responsiveness deteriorates.

  This invention is made | formed in view of such a condition, The objective is to provide the vehicle suspension apparatus which can improve the durability of a motor.

The vehicle suspension system according to the present invention has a motor that generates a damping force between an unsprung portion and an unsprung portion, and an auxiliary damping force characteristic that differs from a motor damping force characteristic exhibited by the motor according to the number of rotations of the motor. Auxiliary damping force generating means for generating an auxiliary damping force between the sprung and unsprung portions.
The auxiliary damping force generating means has an auxiliary damping force characteristic that generates an auxiliary damping force that is greater than or equal to the damping force of the motor in a high rotation region of the motor.

According to the present invention, an auxiliary damping force according to the auxiliary damping force characteristic is generated in the vehicle suspension device together with the motor damping force according to the motor damping force characteristic. Therefore, the damping force can be changed according to the motor rotation speed, and without increasing the motor capacity, it is possible to suppress a rapid increase in the motor rotation speed and the increase in the regenerative current thereby increasing the durability of the motor. Can be improved.
According to the present invention, a large auxiliary damping force can be obtained in a region where the motor rotation speed is large. The high rotation region is a region where the regenerative current increases. According to the present invention, since the damping force in the high rotation region increases, an increase in regenerative current can be effectively suppressed.

  Preferably, the auxiliary damping force generating means has an auxiliary damping force characteristic that generates an auxiliary damping force that exponentially increases as the rotational speed of the motor increases.

  According to the present invention, an increase in the regenerative current can be more effectively suppressed in a region where the motor rotation speed is large.

  Preferably, the damping force generating means includes a fan that rotates integrally with a rotor of the motor, and a fan container that houses the fan together with a liquid.

  According to the present invention, it is possible to increase the auxiliary damping force exponentially in accordance with the motor rotational speed with a simple configuration using the damping force characteristic generated by the fluid.

  As described above, according to the present invention, it is possible to provide a suitable vehicle suspension device that can improve the durability of the motor.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(First embodiment)
FIG. 1 shows a configuration of a vehicle 1 according to an embodiment of the present invention. The vehicle 1 includes a vehicle body 2 and four wheels 3. The vehicle body 2 and the wheel 3 are connected via an electromagnetic suspension 4. The electromagnetic suspension 4 is an example of a vehicle suspension device provided with an absorber that generates a spring force and an unsprung damping force of the vehicle 1 using a motor.

  Note that the position of the member supported by the spring of the electromagnetic suspension 4 is referred to as “sprung”, and the position of the member not supported by the spring is referred to as “unsprung”. That is, the sprung is on the vehicle body 2 side, and the unsprung is on the wheel 3 side.

  Each electromagnetic suspension 4 is independently controlled by an electronic control device (hereinafter, the electronic control device is referred to as “ECU”) 10. The ECU 10 includes a CPU, a RAM, and a ROM. By providing the electromagnetic suspension 4 for each wheel 3, the ECU 10 can independently control the current applied to the motor of the electromagnetic suspension 4 according to the state of each wheel 3. Further, by adopting the electromagnetic suspension 4, it is possible to realize control with excellent responsiveness.

  A current flowing through the motor of each electromagnetic suspension 4 is detected by a current sensor 5. The detection result of each current sensor 5 is transmitted to the ECU 10. The current detection function by the current sensor 5 may be realized by the ECU 10.

  A vehicle height sensor 6 is provided in the vicinity of each wheel 3. Further, each electromagnetic suspension 4 is provided with a rotation speed sensor 7 for detecting the rotation speed of the motor. Detection signals from the vehicle height sensor 6 and the rotation speed sensor 7 are input to the ECU 10 and used for controlling the electromagnetic suspension 4.

  FIG. 2 shows the configuration of the electromagnetic suspension 4. Schematically, the electromagnetic suspension 4 includes a shock absorber 20 and a coil spring 22 on the outside thereof. The shock absorber 20 includes a ball screw portion 24 and a motor 26 above the ball screw portion 24. The ball screw portion 24 converts the vertical motion of the wheel into a rotational motion, and a damping force for the rotational motion is generated by the regenerative braking of the motor 26. As will be described later, an auxiliary damping force generation unit 28 characteristic of the present embodiment is provided above the motor 26, and the auxiliary damping force generation unit 28 has an auxiliary damping force characteristic. Force is generated between the sprung and unsprung. The auxiliary damping force characteristic changes according to the motor rotation speed in the same manner as the motor damping force characteristic, but is different from the motor damping force characteristic.

  The configuration of the electromagnetic suspension 4 in FIG. 2 will be described in detail. An attachment base 32 is attached to the vehicle body attachment surface 30. The mounting base 32 includes a flange portion 34 that is fixed to the vehicle body mounting surface 30 and a cylindrical portion 36 that extends downward from the flange portion 34.

  A cylindrical absorber housing 38 is disposed below the mounting base 32. The lower part of the mounting base 32 is fitted to the upper part of the absorber housing 38, and both can slide in the axial direction. The lower end of the absorber housing 38 is attached to the wheel.

  A flange-shaped spring receiving portion 40 is provided on the outer side of the absorber housing 38. The coil spring 22 is attached in a compressed state between the attachment base 32 corresponding to the upper seat and the spring receiving portion 40 equivalent to the lower seat.

  A rotor shaft 42 is provided inside the absorber housing 38 so as to be movable in the axial direction. A ball screw 44 (male screw) is provided at the lower end of the rotor shaft 42, and a ball screw nut 46 (female screw) is attached to the absorber housing 38, and they are engaged with each other. ing.

  The rotor shaft 42 extends upward in the absorber housing 38. Then, the rotor shaft 42 exits the absorber housing 38, penetrates the mounting base 32, and further extends into a cylindrical upper housing 48 disposed on the upper side of the mounting base 32.

  In the upper housing 48, the rotor shaft 42 is fitted into the rotor body 50. The rotor shaft 42 and the rotor body 50 are fixed, and a motor rotor 52 is constituted by these. The motor rotor 52 is disposed in a motor stator 54 fixed to the inner peripheral surface of the upper housing 48, and the motor 26 is configured by both of them.

  When the motor 26 is driven, the rotor shaft 42 is rotated relative to the ball screw nut 46 by the ball screw portion 24, and the absorber housing 38 is pushed downward or pulled upward with respect to the motor 26. In the present embodiment, an example in which the ball screw 44 is provided on the vehicle spring and the ball screw nut 46 is provided on the vehicle spring is described.

  The rotor shaft 42 extends further upward in the upper housing 48 beyond the motor 26. The rotor shaft 42 reaches the auxiliary damping force generator 28 provided at the upper part of the upper housing 48.

  The auxiliary damping force generator 28 has a partition wall 56. A sealed space 58 is formed by the partition wall 56 and the upper housing 48, and the sealed space 58 is filled with liquid. The liquid is oil in the present embodiment. The fan 60 is fixed to the rotor shaft 42 so as to be positioned in the sealed space 58. The fan 60 is provided so as to extend in the radial direction from the rotor shaft 42, and the shape is set so as to generate a desired damping force according to the rotation. A part of the upper housing 48 and the partition wall 56 function as a fan container of the present invention.

  The upper end of the rotor shaft 42 is rotatably supported by the upper housing 48 by a bearing 62. The rotor shaft 42 is rotatably supported on the mounting base 32 by a bearing 64, and the rotor body 50 is rotatably supported by the mounting base 32 by a bearing 66.

  The configuration of the electromagnetic suspension 4 has been described above. Next, the operation of the electromagnetic suspension 4 will be described.

  In the electromagnetic suspension 4 of FIG. 2, the coil spring 22 supports the weight of the sprung portion of the vehicle and prevents vibrations and shocks from the road surface from being transmitted to the vehicle body through the wheels. The shock absorber 20 attenuates vertical vibrations of the vehicle body caused by the coil spring 22. The shock absorber 20 can generate a damping force between the sprung and unsprung parts of the vehicle using the regeneration of the motor 26, and has excellent control response. The motor 26 is controlled by the ECU 10 (FIG. 1).

  When the vehicle is traveling on a flat place, the ECU 10 sets the current value applied to the motor 26 of the electromagnetic suspension 4 to a reference current value that is, for example, 0A. When the road surface is uneven and the wheel moves up and down, the coil spring 22 expands and contracts due to the relative movement between the mounting base 32 and the absorber housing 38. At this time, when the ball screw 44 rotates relative to the ball screw nut 46, the rotor shaft 42 rotates, and the motor 26 rotates to act as a generator to generate a regenerative current. A damping force is generated by the resistance force generated at this time.

  The current sensor 5 detects a current generated by electromagnetic induction inside the motor 26 and transmits it to the ECU 10. The ECU 10 applies to the motor 26 a current in a direction that suppresses expansion and contraction of the coil spring 22, that is, a current that is opposite to the current generated by electromagnetic induction. ECU10 sets the electric current applied to the motor 26 according to the acceleration of the up-down direction of a vehicle body, and adjusts damping force. Thus, the shock absorber 20 of the present embodiment functions as an electromagnetic shock absorber.

  The shock absorber 20 can displace the vehicle body in the vertical direction by driving the motor 26 and rotating the ball screw 44. Thereby, the shock absorber 20 of this Embodiment can be utilized in order to control the attitude | position of a vehicle body.

  As described above, the electromagnetic shock absorber has an electromagnetic actuator composed of a motor, so that high responsiveness is obtained and controllability is good. However, if there is an abrupt input from the suspension, a large current flows due to regeneration, and the motor may be damaged. In order to avoid such a situation, it is conceivable to increase the capacity of the electromagnetic actuator, but the inertia of the rotor is increased and the response is sacrificed.

  On the other hand, the electromagnetic suspension 4 of the present embodiment can suitably cope with the above problem by including the auxiliary damping force generation unit 28. That is, in the auxiliary damping force generator 28, the fan 60 rotates in the liquid as the rotor shaft 42 rotates, thereby generating a damping force and obtaining a damper effect. Due to this damping force, a rapid increase in the rotation of the motor 26 is suppressed.

  FIG. 3 shows a motor damping force characteristic, an auxiliary damping force characteristic, and a combined damping force characteristic thereof. The motor damping force characteristic is a characteristic of a damping force generated by regeneration of the motor 26, and the auxiliary damping force characteristic is a characteristic of a damping force generated by the auxiliary damping force generation unit 28.

  As illustrated, the motor 26 generates a damping force proportional to the motor rotation speed (rotor rotation speed). On the other hand, in the auxiliary damping force generation unit 28, the fan 60 is disposed in a space sealed with a liquid, and the damping force is generated by the resistance of the liquid. As shown in the figure, the auxiliary damping force generating unit 28 generates a damping force that increases exponentially according to the motor rotational speed, more specifically in proportion to the square of the motor rotational speed.

  Therefore, referring to the composite damping force characteristic, in the normal use region where the rotational speed is low, the damping force of the motor is dominant and the auxiliary damping force is small. Since the damping force proportional to the rotational speed is dominant, the controllability is good.

  On the other hand, since the auxiliary damping force increases exponentially in the high rotation region, the auxiliary damping force exceeds the motor damping force and becomes dominant. Since a large damping force is generated, a rapid change in the rotational speed can be suppressed. The regenerative current flowing through the motor is suppressed, and the motor can be prevented from generating heat.

  In this way, in the present embodiment, the electromagnetic actuator mainly exhibits a damper effect during low rotation and high controllability is obtained, and during high rotation, an overcurrent is applied to the electromagnetic actuator due to the damper effect due to the resistance of the liquid. Can be prevented from flowing. For example, suppose that the vehicle passes through a place with a lot of unevenness. At this time, a large input is generated and the rotation of the motor tends to increase rapidly. However, when the motor rotation speed increases, the auxiliary damping force increases, the rapid increase in the motor rotation speed is suppressed, and the motor is protected.

  As described above, according to the present invention, the vehicle suspension device generates the auxiliary damping force according to the auxiliary damping force characteristic together with the motor damping force according to the motor damping force characteristic. Therefore, even if the capacity of the motor is small, the damping force characteristic generated according to the motor speed is changed. Without increasing the motor capacity, it is possible to suppress a rapid increase in the motor rotation speed and an increase in the regenerative current, thereby improving the durability of the motor.

  Furthermore, according to the present invention, even if the motor fails or the control device fails, the auxiliary damping force generating means generates the auxiliary damping force. Therefore, the fail-safe structure can be provided in the electromagnetic suspension with a simple configuration.

Further, according to the present invention, a large auxiliary damping force can be obtained in a region where the motor rotation speed is large. Since the damping force in the high rotation region increases, an increase in regenerative current can be effectively suppressed. In particular, according to the present invention, the auxiliary damping force characteristic increases exponentially according to the motor rotational speed, so that an increase in the regenerative current can be effectively suppressed in a region where the motor rotational speed is large. Further, the present invention can increase the auxiliary damping force exponentially in accordance with the motor rotation speed with a simple configuration by utilizing the damping force characteristic generated by the fluid.
(Second Embodiment)
FIG. 4 shows a second embodiment of the present invention. Description of matters common to the first embodiment will be omitted as appropriate.

  As shown in FIG. 4, the electromagnetic suspension 4 of the present embodiment includes a planetary gear device 70 between the motor 26 and the auxiliary damping force generator 28 in addition to the configuration of FIG. 2. The planetary gear device 70 includes a sun gear 72, a planetary gear 74, and a ring gear 76.

  The sun gear 72 is provided on the rotor shaft 42. The carrier 78 of the planetary gear 74 is rotatably supported on the rotor shaft 42 by bearings 80 and 82. Further, a clutch 84 is provided on the outer periphery of the carrier 78. With the clutch 84 released, the carrier 78 can rotate. In a state where the clutch 84 is engaged, the carrier 78 is fixed to the upper housing 48 and cannot rotate.

  The clutch 84 is controlled by the ECU 10. The ECU 10 controls the clutch 84 based on the motor rotational speed N detected by the rotational speed sensor 7. The ECU 10 stores a predetermined threshold rotational speed N0, and compares the detected rotational speed N with the threshold rotational speed N0. The threshold rotational speed N0 is set in advance to an appropriate value in a range where no overcurrent flows to the motor 26. The ECU 10 releases the clutch 84 when the motor rotation speed N is less than the threshold rotation speed N0, and engages the clutch 84 when the motor rotation speed N is greater than or equal to the threshold rotation speed N0. The threshold rotational speed at the time of engagement and release may be set differently, thereby providing hysteresis.

  The ring gear 76 is connected to the fan shaft 86. In the present embodiment, unlike the first embodiment, the fan shaft 86 is separated from the rotor shaft 42.

  Next, the operation of the electromagnetic suspension of the present embodiment will be described. During normal regeneration, the clutch 84 is released under the control of the ECU 10. The motor 26 is rotated by an input from below and generates a regenerative current. However, the clutch 84 is not connected, the fan 60 does not rotate, and no auxiliary damping force acts. Therefore, a damping force is generated only by regeneration of the motor.

  When an abrupt input occurs and becomes greater than a certain threshold value, the motor rotation speed N reaches the threshold rotation speed N0. When the ECU 10 determines that the motor rotation speed N has become equal to or greater than the threshold rotation speed N0, the clutch 84 is engaged. As a result, the ring gear 76 rotates together with the fan 60. A combined damping force is generated by the regeneration of the motor 26 and the resistance of the liquid. The latter damping force increases exponentially, thereby preventing the occurrence of overcurrent in the motor.

  If the ECU 10 determines that the motor rotational speed N has decreased and has fallen below the threshold rotational speed NO, the ECU 10 releases the clutch 84. Thereby, the ring gear 76 stops and the electromagnetic suspension 4 returns to the state in which the first motor 26 generates a damping force.

  FIG. 5 schematically shows the rotation state of the planetary gear device 70. During normal control, the clutch 84 is released and the carrier 78 rotates. The ring gear 76 is set so as not to rotate.

  When excessive input occurs, the clutch 84 is engaged and the carrier 78 does not rotate. As a result, the ring gear 76 rotates together with the fan shaft 86, and a damping force is generated by the resistance of the liquid.

  FIG. 6 shows an example of setting the threshold rotational speed N0. As described above, the threshold rotational speed N0 is set in advance to an appropriate value within a range where no overcurrent flows through the motor 26. Furthermore, the example of FIG. 6 considers the response of the motor damping force according to the rotational speed. That is, when the motor rotation speed increases, the responsiveness tends to deteriorate and the damping force tends to decrease. Therefore, as shown in FIG. 6, the threshold rotational speed is set at a level at which the damping force does not decrease. Thereby, sufficient damping force can be obtained more reliably.

  As a modification of the present embodiment, the ECU 10 may use a detection signal other than the motor rotation speed N for clutch control. For example, the detection signal of the vehicle height sensor 6 can be used. That is, the magnitude of the input to the electromagnetic suspension can be detected by the vehicle height sensor 6. Therefore, the above-described control can be performed using the output of the vehicle height sensor 6.

  However, in this modification, the change in the vehicle height is proportional to the motor speed. Even if another detection signal corresponding to the motor rotational speed N is used as in this example, such control corresponds to control corresponding to the motor rotational speed.

  Next, FIG. 7 shows a motor damping force characteristic, an auxiliary damping force characteristic, and a combined damping force characteristic thereof. In the present embodiment, when the motor rotation speed N is less than the threshold rotation speed N0, the motor 26 generates the damping force of the suspension.

  In a region where the motor rotation speed N (rotor rotation speed N) is greater than or equal to the threshold rotation speed N0, the clutch 84 is connected, so that an auxiliary damping force is added to the motor damping force. Since the auxiliary damping force is proportional to the square of the rotational speed, a large damping force is generated.

  Therefore, also in the present embodiment, it is possible to effectively prevent the motor from being damaged at the time of high rotation while ensuring the controllability and responsiveness at the time of low rotation.

In this embodiment, in particular, in a normal region where the rotational speed is low, only the motor damping force is generated, and the damping force is proportional to the rotational speed. As shown in the composite damping force characteristic diagram, since the region where the damping force characteristic is linear is wide, there is an additional advantage that controllability is improved.
(Third embodiment)
FIG. 8 shows a third embodiment of the present invention. A description of matters common to the first and second embodiments will be omitted as appropriate.

  Referring to FIG. 8, schematically, the electromagnetic suspension 4 of the present embodiment is a modification of the second embodiment shown in FIG. The electromagnetic suspension 4 has a second motor 90 on the outer periphery of the carrier 78 of the planetary gear device 70, and a third motor 92 is connected to the ring gear 76. In the present embodiment, the third motor 92 corresponds to auxiliary damping force generation means. Further, the auxiliary damping force generating unit 28 using liquid such as the fan 60 of FIG. 4 is abolished. Further, the clutch 84 of FIG. 4 is also abolished.

  More specifically, the second motor rotor 94 is provided on the carrier 78, and the second motor stator 96 is disposed on the inner periphery of the upper housing 48, and the second motor 90 is configured by these.

  The ring gear 76 is provided with a third motor rotor 98, and a third motor stator 100 is disposed on the inner periphery of the upper housing 48. The second motor rotor 94 is rotatably supported on the upper housing 48 by a shaft 102. As described above, the third motor 92 corresponds to the auxiliary damping force generating means. As the third motor 92, a motor having a larger capacity than the motor 26 (hereinafter, appropriately referred to as the first motor 26) and the second motor 90 is provided. The first motor 26 and the second motor 90 may be relatively small motors.

  The second motor 90 and the third motor 92 are controlled by the ECU 10. The ECU 10 controls the second motor 90 and the third motor 92 together with the first motor 26 based on the motor rotational speed N detected by the rotational speed sensor 7. The ECU 10 stores a predetermined threshold rotational speed N0, and compares the detected rotational speed N with the threshold rotational speed N0. As described above, the threshold rotational speed N0 is set in advance to an appropriate value within a range where no overcurrent flows through the motor 26. The ECU 10 fixes the second motor 90 when the motor rotation speed N is greater than or equal to the threshold rotation speed N0.

  Next, the operation of the electromagnetic suspension of the present embodiment will be described. During normal regeneration, the first motor 26 and the second motor 90 rotate to generate a regenerative current, and these damping forces act. The third motor 92 does not rotate.

  When an abrupt input occurs and the input becomes larger than a certain threshold value, the motor rotation speed N reaches the threshold rotation speed N0. When the ECU 10 determines that the motor rotation speed N has reached the threshold rotation speed N0 or more, the ECU 10 controls the second motor 90 to stop. When the second motor 90 is fixed, the ring gear 76 rotates, and accordingly, the third motor 92 rotates to generate a regenerative current and a damping force. Since the third motor 92 has a large capacity, a larger damping force is generated, and overcurrent is prevented in the first motor 26 and the second motor 90.

  If the ECU 10 determines that the motor rotation speed N has decreased and has fallen below the threshold rotation speed N0, the ECU 10 releases the fixation of the second motor 90. Thereby, the 1st motor 26 and the 2nd motor 90 regenerate again.

  FIG. 9 shows the damping force characteristics of the first motor 26, the damping force characteristics of the second motor 90, the damping force characteristics of the third motor 92, and their combined damping force characteristics. The damping force characteristic of the third motor 92 corresponds to the auxiliary damping force characteristic.

  In the present embodiment, when the motor rotation speed N (rotor rotation speed N) is less than the threshold rotation speed N0, the combined damping force is a combination of the damping forces of the first motor 26 and the second motor 90. Since the first motor 26 and the second motor 90 have a relatively small capacity, the damping force is relatively small, but the response is high.

  On the other hand, in a region where the motor rotation speed N is equal to or greater than the threshold rotation speed N0, the combined damping force is a combination of the damping forces of the first motor 26 and the third motor 92. Since the capacity of the third motor 92 is large, a large damping force is generated.

  Therefore, also in the present embodiment, it is possible to effectively prevent the motor from being damaged at the time of high rotation while ensuring the controllability and responsiveness at the time of low rotation.

  As a modification of the present embodiment, a clutch may be provided instead of the second motor 90. The clutch may be the clutch 84 of the second embodiment shown in FIG. As described in the second embodiment, the clutch is controlled by the ECU 10 and is engaged when the motor rotation speed N is equal to or higher than the threshold rotation speed N0.

  In this modification, the first motor 26 performs regeneration when the rotational speed is low, and the first motor 26 and the third motor 92 perform regeneration when the rotational speed increases. Therefore, the advantage of the present invention can be obtained even in this modification.

  The present invention has been described based on the embodiments. This embodiment is an exemplification, and it will be understood by those skilled in the art that various modifications can be made to the combination of each component and each processing process, and such modifications are also within the scope of the present invention.

  The present invention can improve the durability of an electromagnetic vehicle suspension system, and is useful.

It is a figure which shows the structure of the vehicle which concerns on embodiment. It is a figure which shows the structure of the electromagnetic suspension which concerns on 1st Embodiment. It is a figure which shows the damping force characteristic which concerns on 1st Embodiment. It is a figure which shows the structure of the electromagnetic suspension which concerns on 2nd Embodiment. It is a figure which shows the operation state of the planetary gear apparatus in 2nd Embodiment. It is a figure explaining the setting of the threshold rotation speed in 2nd Embodiment. It is a figure which shows the damping force characteristic which concerns on 2nd Embodiment. It is a figure which shows the structure of the electromagnetic suspension which concerns on 3rd Embodiment. It is a figure which shows the damping force characteristic which concerns on 3rd Embodiment.

Explanation of symbols

  1 vehicle, 2 vehicle body, 3 wheels, 4 electromagnetic suspension, 5 current sensor, 6 vehicle height sensor, 7 speed sensor, 10 ECU, 20 shock absorber, 22 coil spring, 24 ball screw part, 26 motor, 28 auxiliary damping force Generating part, 56 partition wall, 58 sealed space, 60 fans.

Claims (3)

A motor that generates a damping force between the sprung and unsprung;
Auxiliary damping force generating means for generating an auxiliary damping force of an auxiliary damping force characteristic different from the motor damping force characteristic exhibited by the motor according to the number of rotations of the motor,
The vehicle suspension apparatus according to claim 1, wherein the auxiliary damping force generating means has an auxiliary damping force characteristic that generates an auxiliary damping force that is greater than or equal to the damping force of the motor in a high rotation region of the motor. 2. The vehicle suspension system according to claim 1, wherein the auxiliary damping force generating means has an auxiliary damping force characteristic that generates an auxiliary damping force that exponentially increases with an increase in the rotational speed of the motor. . The vehicle suspension apparatus according to claim 1 or 2, wherein the damping force generating means includes a fan that rotates integrally with a rotor of the motor, and a fan container that accommodates the fan together with a liquid.

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