JP4582068B2 - Vehicle suspension system - Google Patents

Description

  The present invention relates to a suspension system mounted on a vehicle, and more particularly to a suspension system including an electromagnetic actuator and a fluid spring.

In recent years, there is a suspension system provided with a fluid spring capable of adjusting the vehicle height using the pressure of fluid in order to adjust the distance between the vehicle body wheels, that is, the vehicle height. On the other hand, as a suspension system, a system that causes an electromagnetic actuator to function as an absorber for vibration damping, that is, a so-called electromagnetic suspension system (hereinafter sometimes abbreviated as “electromagnetic suspension”) has been studied. The vehicle height adjustment by the fluid spring has a problem that the speed of changing the vehicle height is low, but the suspension system described in Patent Document 1 below includes both the fluid spring and the electromagnetic suspension described above, By adjusting the vehicle height by cooperating both the fluid spring and the electromagnetic suspension, the vehicle height can be adjusted quickly.
JP 2006-117210 A

  In general, as a control of the fluid spring when changing the vehicle height, the fluid continues to flow in or out until the actual vehicle height reaches the target vehicle height. In many cases, control is used to stop the operation. For example, in the case of a suspension system that adjusts the vehicle height by cooperating both the fluid spring and the electromagnetic suspension, the target vehicle height is reached by an electromagnetic actuator that changes the vehicle height compared to the fluid spring. If it reaches, the inflow and outflow of the fluid to the fluid spring will stop at the time of arrival, and in order to maintain the vehicle height, the electromagnetic actuator must continue to exert the driving force at that time . Therefore, the power consumption of the system is increased, and the system has a problem that the vehicle height adjustment efficiency is poor in that respect. In the system described in the above patent document, a pressure sensor capable of detecting the pressure in the fluid spring is provided, and the inflow / outflow of the fluid to the fluid spring is controlled based on the pressure. Even after the vehicle body reaches the target vehicle height by the driving force, the inflow and outflow of the fluid are continuously performed up to a predetermined pressure. Then, the driving force of the electromagnetic actuator is reduced in accordance with the subsequent change in the pressure in the fluid spring, thereby addressing the above problem. This coping means is only an example, and efficient vehicle height adjustment can be performed without relying on that means. This invention is made | formed in view of such a situation, and makes it a subject to provide the suspension system which can perform efficient vehicle height adjustment.

  In order to solve the above-described problems, the vehicle suspension system according to the present invention is configured such that when the vehicle height is adjusted by cooperating the fluid spring and the electromagnetic actuator, the fluid spring is adjusted until the distance between the vehicle body wheels reaches the target separation distance. In addition, control is performed so that the fluid flows in and out, and the distance between the vehicle wheels is changed to the immediate separation distance that is set before the target separation distance by using the force of the electromagnetic actuator, and the immediate separation is performed. It is configured to control to reduce the force of the electromagnetic actuator after reaching the distance.

  The suspension system of the present invention can be configured relatively simply such that it is not necessary to provide a pressure sensor, and the fluid spring exerts the force necessary to maintain the vehicle height by relatively simple control. Therefore, according to the present suspension system, the power consumption of the system can be suppressed. That is, the suspension system of the present invention is a system that can perform efficient vehicle height adjustment.

Aspects of the Invention

  In the following, some aspects of the invention that can be claimed in the present application (hereinafter sometimes referred to as “claimable invention”) will be exemplified and described. As with the claims, each aspect is divided into sections, each section is numbered, and is described in a form that cites the numbers of other sections as necessary. This is merely for the purpose of facilitating the understanding of the claimable inventions, and is not intended to limit the combinations of the constituent elements constituting those inventions to those described in the following sections. In other words, the claimable invention should be construed in consideration of the description accompanying each section, the description of the embodiments, etc., and as long as the interpretation is followed, another aspect is added to the form of each section. In addition, an aspect in which some constituent elements are deleted from the aspect of each item can be an aspect of the claimable invention. In the following items, each of items (1) to (5) corresponds to each of items 1 to 5.

(1) The vehicle body and the wheel can be elastically supported by the fluid pressure mutually, and the distance between the vehicle body and the wheel, which is the separation distance between the vehicle body and the wheel in the vertical direction, can be changed by the fluid flowing in and out. A structured fluid spring;
An actuator that is provided in parallel with the fluid spring and has an electric motor and exerts an actuator force that is a force in the approach / separation direction between the vehicle body and the wheel by the force of the electric motor;
A control device for controlling the inflow and outflow of fluid to and from the fluid spring and controlling the actuator force exerted by the actuator by controlling the operation of the electric motor in order to change the distance between vehicle body wheels to a target separation distance; A vehicle suspension system comprising:
The control device is
The fluid spring is controlled so that the fluid flows in and out until the actual distance between the vehicle body wheels reaches the target separation distance,
The actuator force to be exerted on the actuator is controlled so that the actual distance between the vehicle wheels is the near distance set before the target distance, and the actual distance between the wheels is the distance between the eyes. A suspension system for a vehicle that is controlled to be reduced after becoming.

  If the control target of the actuator is the target separation distance, the inflow / outflow of the fluid to the fluid spring stops when the distance between the vehicle body wheels becomes the target separation distance. On the other hand, in the aspect described in this section, the actuator control is set so as to be closer to the actual distance between the vehicle wheels at the time of starting the vehicle height change than the current separation distance, that is, the target separation distance. The distance is adopted as a control target. For this reason, the inflow / outflow of fluid to / from the fluid spring can be continued even after the distance between the vehicle body wheels becomes the immediate separation distance. Since the actuator force is reduced after the distance between the vehicle body wheels becomes the immediate separation distance, the force required to maintain the target separation distance thereafter can be made to depend on the fluid spring. Therefore, according to the system of the aspect of this section, it is possible to suppress power consumption, and it is possible to quickly adjust the vehicle height by using the actuator force. That is, according to the aspect of this section, the vehicle height can be adjusted efficiently. As described above, it is possible to provide a sensor for detecting the pressure of the fluid in the fluid spring and control the actuator and the fluid spring based on the detected pressure. In the aspect, since it is not necessary to provide such a sensor, according to the system of this section, it is possible to simplify the configuration and avoid an increase in cost.

  The “fluid spring” in the aspect of this section includes, for example, a diaphragm type air spring in which compressed air as a fluid is sealed in a pressure chamber, a cylinder filled with hydraulic fluid as a fluid, and an accumulator communicating with the cylinder. It is possible to employ various springs such as a hydraulic spring configured to include

  The “actuator” in the aspect of this section functions as, for example, an actuator that can actuate the actuator force as a resistance force against the approach and separation between the vehicle body and the wheel, that is, an electromagnetic absorber that generates a damping force against vibration. Can be adopted. Moreover, the system of this aspect can also be made into a system which controls an actuator for the purpose of suppression of a roll, pitch, etc. of a vehicle body. The “electric motor” in this section may be a rotary motor or a linear motor.

  In the aspect described in this section, when the actuator force is reduced, the actuator force may be reduced to a non-zero magnitude, or the actuator force may be reduced to zero. That is, the actuator force may not be exerted. From the viewpoint of reducing the power consumption of the actuator, it is desirable to reduce the actuator force to zero. Moreover, when reducing actuator force, you may reduce in steps and may reduce continuously. Further, the timing for reducing the actuator force, that is, the starting point of the reduction may be the time when the actual distance between the wheels of the vehicle body becomes the current separation distance, and the time when a certain amount of time has passed since that time. May be. That is, “after the actual distance between the wheels of the vehicle body becomes the current separation distance” in this section means after the time when the actual distance between the wheels of the vehicle body becomes the current separation distance.

  (2) The vehicle suspension system according to (1), wherein the control device determines an actuator force to be exerted on the actuator based on a deviation of an actual vehicle body wheel distance from the current separation distance.

  In the aspect described in this section, for example, the actuator force can be increased as the deviation increases. Specifically, at the start of the vehicle height adjustment, the actuator force is large and the vehicle height adjustment is performed quickly. The closer to the immediate separation distance, the smaller the actuator force and the slower the vehicle height adjustment. Therefore, according to the aspect of this section, a smooth vehicle height adjustment operation is performed, and a good riding comfort of the vehicle is ensured even during vehicle height adjustment.

  (3) The control device is configured to be able to change the control gain used in determining the actuator force to be exerted on the actuator, and the control gain is reduced after the actual distance between the wheels of the vehicle body becomes the immediate separation distance. The vehicle suspension system according to (1) or (2), wherein the actuator force is reduced by doing so.

  If the control gain is changed, the magnitude of the actuator force can be changed by relatively easy control. Therefore, according to the aspect of this section, for example, the control gain is reduced according to the inflow / outflow amount of the fluid with respect to the fluid spring, the elapsed time after the actual distance between the vehicle body wheels becomes the current separation distance, etc. By doing so, it is possible to appropriately reduce the actuator force.

  (4) The control device according to any one of (1) to (3), wherein the control device controls the actuator force not to be exerted after the direction of the actuator force exerted on the actuator is reversed. Vehicle suspension system.

  When the distance between the vehicle body wheels is set to the immediate separation distance by the actuator and then approaches the target separation distance from the immediate separation distance by the fluid spring, the direction of the actuator force is reversed to become a force that hinders vehicle height adjustment. According to the aspect described in this section, since the actuator force is prevented from being exerted after the direction of the actuator force is reversed, it is possible to reliably set the distance between the vehicle body wheels to the target separation distance by the fluid spring. . Note that the timing at which the actuator force is not exerted may be at the time when the direction of the actuator force is reversed, or may be after that time. For example, it is also possible to execute control so that the actuator force is gradually reduced from the time when the direction of the actuator force is reversed and finally the actuator force is not exhibited.

  (5) In any one of (1) to (4), the control device gradually reduces the actuator force exerted on the actuator after the actual distance between the wheels of the vehicle body becomes the immediate separation distance. The vehicle suspension system described.

  The aspect described in this section can be an aspect in which, for example, the actuator force is gradually reduced in accordance with an increase in the inflow / outflow amount of the fluid with respect to the fluid spring. In such a mode, the force that mutually supports the vehicle body and the wheel at the time of adjusting the vehicle height, that is, the force that moves the vehicle body and the wheel closer to each other does not change suddenly, and the behavior of the vehicle body at the time of adjusting the vehicle height is not changed. Can be made smooth.

  (6) The vehicle suspension system according to any one of (1) to (5), wherein the immediate separation distance is set to a distance within 10 mm from the target separation distance.

  (7) The immediate separation distance is set to a distance within 15% of the difference between the actual separation distance between the vehicle body wheels and the target separation distance from the target separation distance before the adjustment of the vehicle body wheel distance is started. The vehicle suspension system according to any one of items (1) to (5).

  The modes described in the above two terms are modes in which the immediate separation distance is specifically limited. If the target separation distance is set as described above, efficient vehicle height adjustment can be performed. From the viewpoint of quickly adjusting the vehicle height, it is desirable to adjust the vehicle height using the actuator force as close to the target separation distance as possible. Therefore, in the case of the former mode, it is more preferable that the difference between the current separation distance and the target separation distance is within 5 mm. In the case of the latter mode, the distance between the vehicle body wheels before the vehicle height adjustment is started. More desirably, it is within 10% of the difference between the distance and the target separation distance.

  (8) Any one of the items (1) to (7), wherein the control device gradually approaches the current separation distance to the target separation distance after the actual distance between the wheels of the vehicle body becomes the immediate separation distance. The vehicle suspension system according to claim 1.

  The aspect described in this section can be an aspect in which, for example, the immediate separation distance is gradually brought closer to the target separation distance in accordance with an increase in the inflow / outflow amount of the fluid with respect to the fluid spring. By adopting such an aspect, it is possible to make the current separation distance close to the target separation distance so that the actuator force does not act as a force that hinders vehicle height adjustment so that the direction of the actuator force does not reverse. In addition, when the above-described control is performed in which the actuator force is determined based on the deviation of the actual distance between the vehicle wheels relative to the current separation distance, the direction of the actuator force is reversed and the actuator force is a force that hinders vehicle height adjustment. It is also possible to make the force that hinders the vehicle height adjustment relatively small by bringing the immediate separation distance closer to the target separation distance. That is, according to the aspect of this section, after the actual distance between the vehicle wheels becomes the current separation distance, the distance between the vehicle wheels can be reliably brought close to the target separation distance by the fluid spring and the relatively small actuator force. It becomes possible.

  (9) The vehicle control device according to any one of (1) to (8), wherein the control device controls the actuator force exerted on the actuator only when the vehicle body and the wheel are separated from each other. Suspension system.

  The speed of vehicle height adjustment performed by letting fluid flow out from the fluid spring is relatively high. When the vehicle body and wheels are brought close to each other, even if the vehicle height adjustment is performed using only the fluid spring, efficient vehicle height adjustment is possible. Can be implemented. On the contrary, the speed of the vehicle height adjustment performed by flowing the fluid into the fluid spring must be relatively low. The aspect of this section takes this into consideration, and according to the aspect of this section, the actuator is not used when the vehicle body and the wheel are brought close to each other, so the power consumption by the actuator can be effectively suppressed. It is.

  (10) The vehicle according to any one of (1) to (9), wherein the actuator is an electromagnetic absorber capable of causing an actuator force to act as a resistance force against approaching / separating between a vehicle body and a wheel. Suspension system.

  The aspect described in this section is an aspect in which the system is configured as a so-called electromagnetic suspension system by causing the actuator to function as an absorber.

(11) The actuator is
(a) a male screw portion which is not movable relative to one of the sprung member and the unsprung member, and (b) is relatively immovable relative to the other of the sprung member and the unsprung member, And a female screw portion that rotates relative to the male screw portion as the vehicle body and the wheel approach and separate from each other, and the electric motor causes a relative rotational force to the male screw portion and the female screw portion. The vehicle suspension system according to any one of (1) to (10), wherein the actuator force is exerted by applying

  The aspect described in this section is an aspect in which the electromagnetic actuator is limited to a so-called screw mechanism. According to the aspect of this section, the resistance force against the relative rotation between the male screw portion and the female screw portion constituting the screw mechanism is generated by the electric motor, so that the damping force with respect to the approach and separation between the vehicle body and the wheel is effectively obtained. Can be generated. It is arbitrary which male screw part is provided on either the sprung member side or the unsprung member side, and which is provided with the female screw part. Furthermore, the male screw portion may be configured to be non-rotatable and the female screw portion may be configured to rotate. Conversely, the female screw unit may be configured to be non-rotatable and the male screw unit configured to be rotatable.

  Several embodiments of the claimable invention will now be described in detail with reference to the drawings. In addition to the following examples, the claimable invention is implemented in various modes including various modifications and improvements based on the knowledge of those skilled in the art, including the mode described in the above [Mode of Invention]. can do.

(A) First embodiment << Configuration and function of suspension system >>
FIG. 1 schematically shows a vehicle suspension system 10 according to a first embodiment. The suspension system 10 includes four independent suspension type suspension devices corresponding to the front, rear, left and right wheels 12, each of which is a spring absorber in which a suspension spring and a shock absorber are integrated. Assy20. The wheel 12 and the spring absorber assembly 20 are generic names, and when it is necessary to clarify which of the four wheels corresponds, as shown in FIG. In some cases, FL, FR, RL, and RR are attached to the front wheel, the right front wheel, the left rear wheel, and the right rear wheel.

  As shown in FIG. 2, the spring absorber assembly 20 connects a suspension lower arm 22 as an unsprung member for holding the wheel 12 and a mount portion 24 as a sprung member provided on the vehicle body. And an actuator 26, which is an electromagnetic absorber, and an air spring 28 as a fluid spring provided in parallel therewith.

  The actuator 26 includes an outer tube 30 and an inner tube 32 that fits into the outer tube 30 and protrudes upward from the upper end portion of the outer tube 30. The outer tube 30 is connected to the lower arm 22 via a mounting member 34 provided at the lower end portion thereof, while the inner tube 32 is connected to the mount portion 24 at a flange portion 36 formed at the upper end portion thereof. ing. The outer tube 30 is provided with a pair of guide grooves 38 on the inner wall surface thereof so as to extend in the direction in which the axis of the actuator 26 extends (hereinafter sometimes referred to as “axial direction”). Each of a pair of keys 40 attached to the lower end portion of the inner tube 32 is fitted into each of the outer tube 30 and the inner tube 32 by the guide groove 38 and the key 40. Relative rotation is impossible and relative movement is possible in the axial direction. Incidentally, a seal 42 is attached to the upper end portion of the outer tube 30 to prevent air leakage from the pressure chamber 44 described later.

  The actuator 26 includes a screw rod 50 as a male screw portion in which a thread groove is formed, and a nut 52 as a female screw portion that holds the bearing ball and is screwed with the screw rod 50. And a mechanism and an electric motor 54 (a three-phase DC brushless motor, which may be simply referred to as “motor 54” hereinafter). The motor 54 is fixedly accommodated in the motor case 56, and the flange portion of the motor case 56 is fixed to the upper surface side of the mount portion 24, and the flange portion 36 of the inner tube 32 is attached to the flange portion of the motor case 56. By being fixed, the inner tube 32 is connected to the mount portion 24 via the motor case 56. A motor shaft 58 that is a rotation shaft of the motor 54 is integrally connected to the upper end portion of the screw rod 50. That is, the screw rod 50 is disposed in the inner tube 32 with the motor shaft 58 extended, and is rotated by the motor 54. On the other hand, the nut 52 is fixedly supported on the upper end portion of the nut support cylinder 60 attached to the inner bottom portion of the outer tube 30 in a state of being screwed with the screw rod 50.

  The air spring 28 includes a housing 70 fixed to the mount portion 24, an air piston 72 fixed to the outer tube 30 of the actuator 26, and a diaphragm 74 connecting them. The housing 70 has a generally cylindrical shape with a lid, and is fixed to the lower surface side of the mount portion 24 on the upper surface side of the lid portion 76 in a state where the inner tube 32 of the actuator 26 is passed through a hole formed in the lid portion 76. Yes. The air piston 72 has a generally cylindrical shape, and is fixed to the upper portion of the outer tube 30 with the outer tube 30 fitted therein. The housing 70 and the air piston 72 are connected by a diaphragm 74 while maintaining airtightness, and the pressure chamber 44 is formed by the housing 70, the air piston 72, and the diaphragm 74. The pressure chamber 44 is filled with compressed air as a fluid. With such a structure, the air spring 28 elastically supports the lower arm 22 and the mount portion 24, that is, the wheel 12 and the vehicle body, by the pressure of the compressed air.

  When the vehicle body and the wheel 12 approach / separate, the outer tube 30 and the inner tube 32 move relative to each other in the axial direction. Along with the relative movement, the screw rod 50 and the nut 52 relatively move in the axial direction, and the screw rod 50 rotates with respect to the nut 52. The motor 54 can apply a rotational torque to the screw rod 50, and the rotational torque can generate a resistance force in a direction that prevents the approach and separation between the vehicle body and the wheel 12. It is possible. This resistance force becomes a damping force against the approach / separation between the vehicle body and the wheel 12, whereby the actuator 26 functions as a so-called absorber (also referred to as “damper”). The actuator 26 also has a function of moving the vehicle body and the wheel 12 closer to or away from each other by the actuator force. That is, the actuator force in the approaching / separating direction between the vehicle body and the wheel 12 can be applied as a driving force. With this function, it is possible to effectively suppress the roll of the vehicle body at the time of turning, the pitch of the vehicle body at the time of acceleration / deceleration, and the vehicle height of the vehicle.

  An annular buffer rubber 77 is attached to the inner wall surface of the upper end of the outer tube 30, and a buffer rubber 78 is also attached to the inner bottom wall surface of the outer tube 30. When the vehicle body and the wheel 12 approach / separate, when the key 40 moves relative to some extent in a direction in which the vehicle body and the wheel 12 are separated (hereinafter, may be referred to as “rebound direction”), the key 40 is interposed via the buffer rubber 77. In contrast, when the vehicle body and the wheel 12 are relatively moved in a direction in which the vehicle body and the wheel 12 approach each other (hereinafter, may be referred to as a “bound direction”), the lower end of the screw rod 50 is the buffer rubber 78. It contacts with the inner bottom wall surface of the outer tube 30 via. That is, the spring absorber assembly 20 has stoppers (so-called bound stoppers and rebound stoppers) against the approach and separation between the vehicle body and the wheels 12.

  The suspension system 10 is a fluid inflow / outflow device for inflowing / outflowing air (air) as a fluid to / from an air spring 28 of each spring / absorber assembly 20, more specifically, a pressure chamber 44 of the air spring 28. An air supply / discharge device 80 is connected to supply air to the pressure chamber 44 and discharge air from the pressure chamber 44. FIG. 3 shows a schematic diagram of the air supply / discharge device 80. The air supply / discharge device 80 includes a compressor 82 that supplies compressed air to the pressure chamber 44. The compressor 82 includes a pump 84 and a pump motor 86 that drives the pump 84. The pump 84 sucks air from the atmosphere through the filter 88 and the check valve 90, pressurizes the air, and performs a check. It discharges through the valve 92. The compressor 82 is connected to the pressure chambers 44 of the four air springs 28 via the individual control valve device 100. The individual control valve device 100 includes four individual control valves 102 which are provided corresponding to the pressure chambers 44 of the air springs 28 and are normally closed valves, and open and close the flow paths for the pressure chambers 44. It is. The compressor 82 and the individual control valve device 100 are common to each other via a dryer 104 that removes moisture from the compressed air, and a flow restriction device 110 in which a throttle 106 and a check valve 108 are provided in parallel with each other. They are connected by a passage 112. The common passage 112 branches from between the compressor 82 and the dryer 104, and an exhaust control valve 114 for exhausting air from the pressure chamber 44 is provided at the branching portion.

  Due to the above-described structure, the suspension system 10 can adjust the amount of air in the pressure chamber 44 of each air spring 28 by the air supply / discharge device 80, and the vertical direction can be adjusted by adjusting the amount of air. It is possible to change the distance between the vehicle body and the wheel 12 (hereinafter sometimes referred to as “vehicle-wheel-wheel distance”). Specifically, it is possible to increase the distance between the vehicle body wheels by increasing the amount of air in the pressure chamber 44, and to decrease the distance between the vehicle body wheels by decreasing the amount of air.

  In the present suspension system 10, the operation of the spring absorber assembly 20 is controlled by a suspension control device. This suspension control device is an actuator electronic control unit (actuator ECU) 142 that controls the actuator 26, that is, actuator force, and an air spring 28 that controls the air spring 28, that is, the air supply / discharge device 80. And a unit (air spring ECU) 144.

  The air spring ECU 144 has a controller 146 mainly composed of a computer having a CPU, ROM, RAM, and the like, and a driver 148 as a drive circuit for the air supply / discharge device 80. Electric power is supplied from the battery 152 to the control valves 102, the pump motor 86, and the like included in the air supply / discharge device 80 via the driver 148 and the converter 150. Further, the controller 146 includes a vehicle speed sensor 154 for detecting a vehicle traveling speed (hereinafter sometimes abbreviated as “vehicle speed”), four stroke sensors 156 for detecting a distance between each wheel 12 and the vehicle body 24, and driving. A vehicle height change switch 158 for changing the vehicle height by an operator's operation is connected (represented in FIG. 1 as “v”, “St”, and “HSw”, respectively). The ROM included in the computer of the controller 146 stores a vehicle height adjustment program, various data, and the like, which will be described later. In the suspension system 10, the set vehicle height selectable by the driver is a set standard vehicle height (Mid vehicle height), and a set high vehicle height (Hi vehicle height) set as a vehicle height higher than the set standard vehicle height. , A set low vehicle height (Low vehicle height) set as a vehicle height lower than the set standard vehicle height is set, and a desired set vehicle height is selectively set by operating the vehicle height change switch 158 by the driver. Be changed. The vehicle height change switch 158 issues a command for shifting the set vehicle height to a higher set vehicle height or a lower set vehicle height, that is, a vehicle height increase command or a vehicle height decrease command. It is structured.

On the other hand, the actuator ECU 142 includes a controller 160 mainly composed of a computer including a CPU, ROM, RAM, and the like, and an inverter 162 as a drive circuit corresponding to the motor 54 included in each actuator 26. The inverter 162 is connected to the battery 152 via the converter 168, and power is supplied to each motor 54 from the battery 152 as a power supply source. Since the motor 54 is driven at a constant voltage, the amount of power supplied to the motor 54 is changed by changing the amount of supplied current, and the force of the motor 54 becomes a force corresponding to the amount of supplied current. Incidentally, the amount of supplied current is determined by each inverter 162 changing a ratio (duty ratio) between a pulse on time and a pulse off time by PWM (Pulse Width Modulation). In addition to the vehicle speed sensor 154, the controller 160 further includes an operation angle sensor 170 for detecting the operation angle of the steering wheel, a longitudinal acceleration sensor 172 for detecting the actual longitudinal acceleration that is the longitudinal acceleration actually generated in the vehicle body, and the vehicle body. The lateral acceleration sensor 174 for detecting the actual lateral acceleration that is actually generated laterally, the four longitudinal acceleration sensors 176 for detecting the longitudinal acceleration of each mount 24 of the vehicle body corresponding to each wheel 12, and the longitudinal of each wheel 12. Four longitudinal acceleration sensors 178 that detect acceleration, a throttle sensor 180 that detects the opening of the accelerator throttle, a brake pressure sensor 182 that detects the master cylinder pressure of the brake, and a rotation angle sensor 184 that detects the rotation angle of the motor 54 are connected. (In FIG. 1, “δ”, “Gx”, “Gy”, “Gz _u , respectively. ”,“ Gz _L ”,“ Sr ”,“ Br ”,“ ω ”). The ROM included in the computer of the controller 160 stores a program relating to actuator force control, various data, and the like, which will be described later. The controller 160 of the actuator ECU 142 and the controller 146 of the air spring ECU 144 described above can communicate with each other.

≪Control of suspension system≫
In the present suspension system 10, the four spring absorber assemblies 20 can be controlled independently. In each of the spring absorber assemblies 20, the actuator force of the actuator 26 is independently controlled to control the vibration of the vehicle body and the wheel 12, that is, the control for damping the sprung vibration and the unsprung vibration (hereinafter referred to as “vibration damping”). Control ”(hereinafter sometimes referred to as“ roll suppression control ”), and control that suppresses the vehicle body pitch (hereinafter also referred to as“ pitch suppression control ”). Is done. In addition, the actuator 26 and the air spring 28 cooperate to execute control for adjusting the distance between the vehicle body wheels (hereinafter also referred to as “vehicle height adjustment control”). The vibration damping control, roll suppression control, and pitch suppression control are executed by causing the actuator force to act as a damping force, a roll suppression force, and a pitch suppression force, respectively. Specifically, the target actuator force is determined by adding the damping force component, roll suppression force component, and pitch suppression force component, which are the components of the actuator force for each control of vibration damping control, roll suppression control, and pitch suppression control, The actuator 26 is centrally executed by being controlled so as to exert its target actuator force. In addition, the vehicle height adjustment control controls the air supply / discharge device 80 that adjusts the air amount of the air spring 28 and exhibits a target actuator force including a vehicle height adjustment component that is an actuator force component that adjusts the vehicle height. This is executed by controlling the actuator 26 so as to. Hereinafter, each of vibration damping control, roll suppression control, and pitch suppression control will be described with respect to a method for determining an actuator force component in each of them, and further, vehicle height adjustment control may be performed by operating the air supply / discharge device 80, and A method for determining the vehicle height adjustment component will be described in detail. In the following description, the actuator force and the component thereof are positive values in the direction in which the vehicle body and the wheel 12 are separated (rebound direction), and those in the direction in which the vehicle body and the wheel 12 are brought closer (bound direction). Is treated as a negative value.

i) Vibration Attenuation Control In the vibration attenuation control, the damping force component F _V is determined so as to exert an actuator force having a magnitude corresponding to the speed of the vibration in order to attenuate the vibration of the vehicle body and the wheel 12. Specifically, the operating speed in the vertical direction of the mount 24 of the vehicle body calculated by the longitudinal acceleration sensor 176 provided on the mount 24 of the vehicle body, the so-called sprung speed V _U, and the lower arm 22 are provided. The damping force component F _V is calculated according to the following equation based on the vertical movement speed of the wheel detected by the vertical acceleration sensor 178, that is, the so-called unsprung speed V _{L.
F V = C U · V U} -C L · V L
Here, C _U is a gain for exerting a damping force corresponding to the vertical operating speed of the mount 24 of the vehicle body, and C _L is a damping force corresponding to the vertical operating speed of the wheel 12. It is a gain to show it. That is, C _U and C _L are so-called attenuation coefficients. Note that the damping force component F _V can be determined by other methods. For example, the index value of the relative speed between the wheel and the vehicle body can be determined according to the following equation based on the rotation speed V of the motor 54 obtained from the detection value of the rotation angle sensor 184 provided in the motor 54. is there.
F _V = C · V (C: damping coefficient)

ii) Roll suppression control In roll suppression control, when the vehicle turns, the actuator force in the bounce direction is applied to the actuator 26 on the inner ring side and the actuator 26 on the outer ring side in the rebound direction according to the roll moment resulting from the turn. The actuator force is exhibited as a roll restraining force. Specifically, first, as a lateral acceleration indexing the roll moment received by the vehicle body, an estimated lateral acceleration Gyc estimated based on the steering angle δ of the steering wheel and the vehicle speed v, and an actually measured actual lateral acceleration Gyr. Based on this, a control lateral acceleration Gy ^* , which is a lateral acceleration used for control, is determined according to the following equation.
Gy ^* = K ₁ · Gyc + K ₂ · Gyr (K ₁ , K ₂ : gain)
Such based on the determined control-use lateral acceleration Gy ^*, the roll restraining force component F _R is determined according to the following equation.
F _R = K ₃ · Gy ^* (K ₃ : Gain)

iii) Pitch suppression control In the pitch suppression control, for the nose dive of the vehicle body that occurs during braking of the vehicle body, the actuator 26FL, FR on the front wheel side in the rebound direction depends on the pitch moment that causes the nose dive. Actuator force is exerted on the actuators 26RL, RR on the rear wheel side in the bound direction as the pitch restraint force. For the squat of the vehicle body generated during acceleration of the vehicle body, the actuator force in the rebound direction is applied to the actuators 26RL, RR on the rear wheel side according to the pitch moment that generates the squat, and the actuator 26FL on the front wheel side. , FR causes the actuator force in the bounce direction to be exhibited as a pitch suppression force. Specifically, as longitudinal acceleration indicative of the pitch moment acting on the vehicle body, the actual longitudinal acceleration Gx that is actually measured is adopted, on the basis of the actual longitudinal acceleration Gx, the pitch restraining force component F _P is determined according to the following formula .
F _P = K ₄ · Gx (K ₄ : Gain)

iv) Vehicle height adjustment control In the vehicle height adjustment control, the actuator 26 and the air spring 28 are set in accordance with the relationship between the target vehicle height set based on the driver's intention and the actual vehicle height. The vehicle height is adjusted in cooperation. First, the control of the air spring 28 will be described in detail. The target vehicle height stored in the controller 146, specifically, the target vehicle body wheel distance h ^* (hereinafter referred to as “target separation distance h ^* ”). The vehicle height is adjusted by comparing the actual vehicle body wheel distance h detected by the stroke sensor 156 and adjusting the amount of air in the pressure chamber 44 of the air spring 28. In the operation of the air supply / discharge device 80 when raising the vehicle height (hereinafter sometimes referred to as “vehicle height increase operation”), first, the pump motor 94 is activated and the individual control valve 102 is opened. Thus, the compressed air is supplied to the pressure chamber 44 of the air spring 28. After the state is continued, when the distance between the vehicle wheels reaches the target distance h ^* , the individual control valve 102 is closed, and the vehicle wheel distances for all the wheels 12 that need to raise the vehicle height. After reaching the target distance h ^* , the operation of the pump motor 94 is stopped. In the operation of the air supply / discharge device 80 for lowering the vehicle height (hereinafter sometimes referred to as “vehicle height reduction operation”), first, the exhaust control valve 114 is opened and the individual control valve 102 is opened. As a result, air is exhausted from the pressure chamber 44 of the air spring 28 to the atmosphere. Thereafter, when the distance between the vehicle body wheels becomes the target distance h ^* , the individual control valve 102 is closed, and the distance between the vehicle body wheels for all the wheels 12 that had to reduce the vehicle height is the target distance h ^* . After that, the exhaust control valve 114 is closed. However, the above-described vehicle height increasing operation and vehicle height decreasing operation are prohibited from being executed when a specific prohibition condition (hereinafter sometimes referred to as “vehicle height adjustment prohibition condition”) is satisfied. Specifically, a roll moment or a pitch moment is acting on the vehicle body, vibration is generated in at least one of the vehicle body and the wheel 12, and the distance between the four vehicle body wheels exceeds a certain allowable range. If even one of the unequalities is satisfied, the operation of the air supply / discharge device 80 is prohibited. In that case, the individual control valve 102 is closed, the pump motor 94 is stopped or the exhaust control valve 114 is closed, and the amount of air in the pressure chamber 44 of the air spring 28 is maintained.

In the vehicle height adjustment control, the actuator 26 is caused to exert a force for adjusting the vehicle height as well as the adjustment of the air amount of the air spring 28 described above. It should be noted that the speed of the vehicle height decreasing operation performed by causing air to flow out from the air spring 28 is relatively high, and conversely, the speed of the vehicle height increasing operation performed by flowing air into the air spring 28 must be relatively low. In view of this, in this embodiment, the actuator 26 exerts a force for adjusting the vehicle height only in the case of the vehicle height increasing operation. The high adjustment component F _H is determined. In the determination of the vehicle height adjustment component F _H, the vehicle height that is the target of the actuator 26 is set before the target vehicle height of the air spring 28. Specifically, the immediate separation distance h _A ^* (= h ^* −δh), which is a set distance δh (5 mm in the present system) in front of the target separation distance h ^* of the air spring 28, is Control target. Then, the vehicle height adjustment component F _H is determined according to the following equation based on the separation distance deviation Δh (= h _A ^* −h), which is a deviation from the actual separation distance h _A ^{* of} the actual vehicle body wheel distance h. It is.
F _H = K ₅ · Δh (K ₅ : gain)

More specifically, the vehicle height adjustment component F _H is determined after the actual vehicle wheel distance h becomes the immediate separation distance h _A ^*, and more specifically, the actual vehicle wheel distance h exceeds the immediate separation distance h _A ^* by the air spring 28. This is reduced when the target separation distance h ^* is approached. In such a case, the distance difference Δh is negative, but the direction of the height adjustment component F _H is to be inverted from the rebound direction the bound direction, by the vehicle height adjusting component F _H is reduced, The vehicle height adjustment component F _H is suppressed from acting as an obstacle to an increase in vehicle height due to the air spring 28. Then, after the direction of the vehicle height adjustment component F _H is reversed, the vehicle height adjustment component F _H is reduced by correcting the gain according to the following equation.
K ₅ '= α ・ K ₅
FIG. 4 shows the relationship between the elapsed time t _c after the direction of the vehicle height adjustment component F _H is reversed and the correction coefficient α. By changing the correction coefficient α as shown in the figure, the gain K ₅ is gradually decreased to [0], that is, the vehicle height adjustment component F _H is gradually decreased to [0].

When the specific prohibition condition described above is satisfied during the vehicle height adjustment, in the control of the actuator 26 in the vehicle height adjustment control, so as to maintain the vehicle height at the time of the prohibition, The vehicle height adjustment component F _H at the time of the prohibition is maintained. Moreover, so that the same when the direction of vehicle height adjusting component F _H was a state that satisfies prohibition condition after inversion, height adjusting component F _H at the time of the prohibition is maintained. In this case, the counting of the time t _c after the direction of the vehicle height adjustment component F _H is reversed is prohibited, and the gradual decrease of the correction coefficient α is also prohibited.

v) Actuator force and motor operation control When the damping force component F _V , the roll restraining force component F _R , the pitch restraining force component F _P and the vehicle height adjusting component F _H are determined as described above, The actuator force F is determined.
F = F _V + F _R + F _P + F _H
The actuator 26 is controlled to exhibit the determined target actuator force F. That is, since the control of the actuator 26 in the vibration damping control, roll suppression control, pitch suppression control, and vehicle height adjustment control is performed in a unified manner by controlling so as to exert the target actuator force F. is there. The operation control of the motor 54 for exerting the target actuator force F is performed by the inverter 162. More specifically, a command for the motor force direction and duty ratio based on the determined target actuator force F is issued to the inverter 162, the switching element of the inverter 162 is switched, and the electric motor 54 is changed to the issued motor. In the force direction, an actuator force having a magnitude corresponding to the duty ratio is exhibited.

≪Control program≫
The control of the air spring 28 in the above-described vehicle height adjustment control is performed in a short time interval (for example, several msec to several tens msec) while the air spring control program shown in the flowchart of FIG. 5 is in the ON state. This is performed by being repeatedly executed by the controller 146. In addition, the actuator force control as described above is performed with a short time interval (for example, several milliseconds to several tens of milliseconds) while the ignition switch is in the ON state. This is performed by being repeatedly executed by the controller 160. Note that these two programs are executed in parallel. Below, the flow of each control is demonstrated easily, referring the flowchart shown in a figure.

i) the air spring control program vehicle height adjustment control, the target vehicle is a flag indicating vehicle height reaches the target height flag f _H is used, the vehicle height adjustment is performed based on the flag f _H. Flag value 0, 1, 2 of the flag f _H, respectively Low vehicle height, Mid vehicle height, which is to correspond to the Hi vehicle height, with respect to the flag f _H, the target distance is h ₀ ^*, h ₁ ^*, it is what is h ₂ ^*. Of the processes according to this control program, the process of adjusting the vehicle height, that is, the process of adjusting the distance between the vehicle body wheels for each wheel 12 is executed individually for each wheel 12.

In the air spring control program, first, in step 1 (hereinafter abbreviated as “S1”, the same applies to other steps), a target vehicle height determination subroutine is executed. This subroutine is a routine for performing the control shown in the flowchart of FIG. In this routine, when the vehicle speed v is equal to or higher than the threshold speed v ₀ , the flag value of the target vehicle height flag f _H is set to 0 in view of vehicle stability, and in other cases, the vehicle height change is performed. command based on the operation of the switch 158 depending on whether the vehicle height increasing command or a vehicle height reducing command, the flag value of the target vehicle height flag f _H is changed to either a high vehicle height side or low-height side, A target separation distance h ^* is determined. Subsequently, in S2 of the main program, it is determined whether or not the vehicle height adjustment prohibition condition described above is satisfied. If it is determined that the vehicle height adjustment prohibition condition is not satisfied, the current time corresponding to each wheel is determined in S5 and S6. and the actual wheel-body distance h, and the target distance h ^* corresponding to the flag value of the target vehicle height flag f _H is compared judged respectively at. If it is determined that it is necessary to increase the distance between the vehicle body wheels, in S7, the distance between the vehicle body wheels is adjusted to increase in accordance with the vehicle height increasing operation described above. On the contrary, when it is determined that the distance between the vehicle body wheels needs to be reduced, in S8, the distance between the vehicle body wheels is adjusted so as to decrease according to the vehicle height reduction operation described above. If the vehicle height adjustment prohibition condition is satisfied, or if it is determined that it is not necessary to change the distance between the vehicle body wheels, the air amount is maintained in S9 as described above. When it is determined that the vehicle height adjustment prohibition condition is satisfied, the prohibition flag f is set to 1, and when it is determined that the vehicle height adjustment prohibition condition is not satisfied, the prohibition flag f is set to 0. After the series of processes described above, one execution of this program ends.

ii) Actuator control program The actuator control program is executed for each of the actuators 26 of the spring absorber assembly 20 provided on each of the four wheels 12. In the following description, processing by this program for one actuator 26 will be described in consideration of simplification of description. In this process, in S31 to S33, as described above, the damping force component F _V, the roll restraining force component F _R, pitch restraining force component F _P are determined, respectively. Next, in S34, a vehicle height adjustment component determination subroutine is executed to determine the vehicle height adjustment component F _H. The vehicle height adjustment component determination subroutine is a routine for performing the control shown in the flowchart in FIG. In this routine, when the vehicle height adjustment prohibition condition is not satisfied in the air spring control program, that is, when the prohibition flag f is 0, the actual vehicle body wheel at the present time corresponding to each wheel in S53 and 56. The distance h is compared with the target separation distance h ^* . When it is determined that it is necessary to increase the distance between the vehicle body wheels, the vehicle height adjustment component F _H is determined as described above in S57 and subsequent steps. More specifically, after the direction of the vehicle height adjustment component F _H is reversed, in S60, the time t _C after the reversal is counted by adding the program execution interval δt, and the time t _{C The} correction coefficient α for _C is determined with reference to the map data shown in FIG. Then, in S61 follows, the gain K ₅ is corrected, so as to gradually decrease the vehicle height adjusting component F _H. Further, when it is determined that the distance between the vehicle body wheels needs to be reduced, the vehicle height adjustment is performed only by the air spring 28, so the vehicle height adjustment component F _H is set to 0 in S55. When the prohibition flag f is 1, the vehicle height adjustment component F _H is set to the previous one so as to maintain the vehicle height at that time in consideration of the prohibition during vehicle height adjustment. The vehicle height adjustment component F _H when the program is executed is set. In addition, when the direction of the vehicle height adjustment component F _H is reversed, the elapsed time t _C after the reversal is not counted, and thus the value of the correction coefficient α at the time of prohibition is maintained. Incidentally, the elapsed time t _C is reset when it is determined in S53 that it is not necessary to change the distance between the vehicle body wheels.

  As described above, after all four components of the actuator force are determined, the target actuator force F to be exhibited by the actuator 26 is determined in S35 of the main program. Next, a control signal corresponding to the determined target actuator force F is transmitted to the motor 54 via the inverter 162, and one execution of the actuator control program is completed.

≪Generation of force to adjust vehicle height≫
FIG. 9 schematically shows changes in the distance between vehicle body wheels in the vehicle height adjustment control, changes in the air in the air spring 28, and generation of the vehicle height adjustment component F _H of the actuator 26. FIG. 9A shows the case where the actuator 26 and the air spring 28 are controlled at the same target vehicle height. In this case, when the distance between the vehicle body wheels is set to the target separation distance by the actuator 26, the inflow of air into the air spring 28 is stopped at that time, and the actuator height is maintained in order to maintain the vehicle height. 26 continues to exert the actuator force at that time. As a result, the power consumption of the system increases, and the efficiency of adjusting the vehicle height deteriorates. FIG. 9B shows the case where the vehicle is controlled by the suspension system 10 of this embodiment, and the case where the vehicle height adjustment is not prohibited in the middle. In the case of the present system 10, the inflow of air to the air spring is continued even after the distance between the vehicle body wheels becomes the current separation distance h _A ^* by the actuator 26, and the distance between the vehicle body wheels is further reduced. Since the actuator force is gradually reduced to [0] after the separation distance h _A ^* is reached, the force required to maintain the target separation distance h ^* thereafter can be made to depend on the air spring 28. Therefore, according to the present suspension system, the vehicle height can be quickly adjusted using the actuator force, and the power consumption can be suppressed, so that the vehicle height can be adjusted efficiently. In this embodiment, since the actuator force is controlled to be gradually decreased after the distance between the vehicle body wheels becomes the current separation distance, the force for moving the vehicle body and the wheel 12 closer to or away from each other during vehicle height adjustment is obtained. There is no sudden change, and the behavior of the vehicle body when adjusting the vehicle height can be made smooth.

(B) Second Embodiment Since the vehicle suspension system of the second embodiment has the same hardware configuration as the system of the first embodiment, in the description of the present embodiment, the system of the first embodiment. Constituent elements having the same functions as those indicated by the same reference numerals are used to indicate corresponding elements, and the description thereof is omitted. Since the system of the present embodiment is different from the system of the first embodiment in the control by the ECU, the control by the ECU of the present embodiment will be described below.

In this embodiment, the control of the actuator 26 in the vehicle height adjustment control by the suspension ECU 140 is different from the control in the first embodiment. The control of the actuator 26 in the vehicle height adjustment control, that is, the determination of the vehicle height adjustment component F _H is performed by executing the vehicle height adjustment component determination subroutine shown in the flowchart of FIG. In the present embodiment, not only in the vehicle height increasing operation (S78 or less) but also in the vehicle height decreasing operation (S82 or less), the air spring 28 and the actuator 26 are cooperated so that the vehicle height is adjusted. Has been. In this embodiment, the difference between the target separation distance h ^* and the current separation distance h _A ^* with respect to the difference between the vehicle body wheel distance h ₀ and the target separation distance h ^* before the start of the vehicle height adjustment is the ratio r ( In this system, r = 0.1 In other words, the current separation distance h _A ^* is determined from the target separation distance h ^* and the vehicle body wheel distance h ₀ before starting the vehicle height adjustment and the target separation distance. (The position is set to be within 10% of the difference from h ^* .) (S76). That is, in this embodiment, the overall 1-r is adjusted so that the vehicle height is adjusted by both the actuator 26 and the air spring 28, and the remaining r is controlled by the air spring 28 (see FIG. 11). ). Further, in the present embodiment, the vehicle height adjustment component F _H corresponds to the increase in the inflow / outflow amount of air to the air spring 28 after the actual vehicle body wheel distance h becomes the immediate separation distance h _A ^* . The immediate separation distance h _A ^* is determined so as to gradually approach the target separation distance h ^* by δh (S79, S83). In the present program, verge distance h _A ^* is determined to be necessary is imminent distance h _A ^* determination in S75 when the execution of the first program becomes necessary height adjustment, It is determined in S76. In other words, even if the current separation distance h _A ^* is changed after the actual vehicle wheel distance h becomes the immediate separation distance h _A ^* , it is set again at the next vehicle height adjustment. It has become.

FIG. 11 shows changes in the distance between vehicle body wheels when the vehicle height increasing operation is performed in the vehicle height adjustment control of this embodiment, the amount of change in air in the air spring 28, and the vehicle height adjustment component F of the actuator 26. FIG. 6 is a schematic diagram showing how _H is generated. In addition, this figure is a thing when vehicle height adjustment was not prohibited on the way. As can be seen from this figure, verge distance h _A ^* is the vehicle height adjusting component F _{for H} orientation is caused to asymptotically to a target distance h ^* to not reversed, the vehicle height adjusting component F _H the air spring 28 It is possible not to act as a hindrance to the vehicle height adjustment by. Further, in the suspension system of the present embodiment, the inflow of air into the air spring 28 is continued even after the distance between the vehicle body wheels becomes the current separation distance h _A ^* by the actuator 26, and further, the vehicle body wheel After the distance becomes the immediate separation distance h _A ^* , the immediate separation distance h _A ^* is gradually made closer to the target separation distance h ^* , thereby reducing the actuator force. Therefore, the force required to maintain the target separation distance h ^* thereafter can be made to depend on the air spring 28. That is, according to this suspension system, the vehicle height can be adjusted efficiently as in the first embodiment.

1 is a schematic diagram illustrating an overall configuration of a vehicle suspension system according to a first embodiment. It is front sectional drawing which shows the spring absorber Assy shown in FIG. FIG. 2 is a schematic diagram showing a spring absorber assembly and an air supply / discharge device shown in FIG. 1. It is the schematic which shows the relationship between the time passage after the direction of the vehicle height adjustment component of an actuator force is reversed, and the correction coefficient for correcting the control gain used in the determination of the vehicle height adjustment component. It is a flowchart showing the air spring control program performed by air spring ECU shown in FIG. It is a flowchart which shows the target vehicle height determination subroutine performed in an air spring control program. It is a flowchart showing the actuator control program performed by actuator ECU shown in FIG. It is a flowchart which shows the vehicle height adjustment component determination subroutine performed in an actuator control program. It is the schematic which shows the mode of the change of the distance between vehicle body wheels in vehicle height adjustment control, the variation | change_quantity of the air in an air spring, and the generation | occurrence | production of the vehicle height adjustment component of an actuator force. It is a flowchart which shows the vehicle height adjustment component determination subroutine performed in the actuator control program in the suspension system for vehicles of 2nd Example. It is the schematic which shows the mode of the change of the distance between vehicle body wheels in the vehicle height adjustment control of the suspension system for vehicles of 2nd Example, and the generation | occurrence | production of the vehicle height adjustment component of the air pressure of an air spring, and an actuator force.

Explanation of symbols

10: Vehicle suspension system 20: Spring absorber assembly 22: Lower arm (unsprung member) 24: Mount part (sprung member) 26: Actuator 28: Air spring (fluid spring) 50: Screw rod (male thread part) 52: Nut (female thread portion) 54: Electric motor 142: Actuator electronic control unit 144: Air spring electronic control unit

Claims (5)

The vehicle body and the wheel are elastically supported by the pressure of the fluid, and the distance between the vehicle body and the wheel, which is the distance between the vehicle body and the wheel in the vertical direction, can be changed by flowing in and out of the fluid. Fluid springs,
An actuator that is provided in parallel with the fluid spring and has an electric motor and exerts an actuator force that is a force in the approach / separation direction between the vehicle body and the wheel by the force of the electric motor;
A control device for controlling the inflow and outflow of fluid to and from the fluid spring and controlling the actuator force exerted by the actuator by controlling the operation of the electric motor in order to change the distance between vehicle body wheels to a target separation distance; A vehicle suspension system comprising:
The control device is
The fluid spring is controlled so that the fluid flows in and out until the actual distance between the vehicle body wheels reaches the target separation distance,
The actuator force to be exerted on the actuator is controlled so that the actual distance between the vehicle wheels is the near distance set before the target distance, and the actual distance between the wheels is the distance between the eyes. A suspension system for a vehicle that is controlled to be reduced after becoming.   2. The vehicle suspension system according to claim 1, wherein the control device determines an actuator force to be exerted on the actuator based on a deviation of an actual vehicle body wheel distance from the current separation distance. 3.   The control device is configured to be able to change the control gain used in determining the actuator force to be exerted on the actuator, and after the actual distance between the wheels of the vehicle body reaches the current separation distance, the control gain is reduced. The vehicle suspension system according to claim 1 or 2, wherein the actuator force is reduced.   The vehicle suspension system according to any one of claims 1 to 3, wherein the control device controls the actuator force not to be exerted after the direction of the actuator force exerted on the actuator is reversed. The vehicle suspension according to any one of claims 1 to 4, wherein the control device gradually reduces the actuator force exerted on the actuator after the actual distance between the vehicle body wheels becomes the immediate separation distance. system.

Images