JP2018047722A - Suspension device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a suspension device that can control a postural change, such as roll and pitch, of a vehicle body while improving ride feeling in a vehicle.SOLUTION: A suspension device SD includes an actuator A, A, A, Aand a controller C. The controller C includes: a reduction force operation part 31 for acquiring reduction force F, F, F, Ffor reducing apparent spring constant of a suspension spring S, S, S, S; and a correction part 32 for correcting the reduction force F, F, F, Fbased on lateral acceleration Gand longitudinal acceleration G, and subtracts reduction force F', F', F', F'corrected from controlling force F, F, F, Fto acquire final control force F, F, F, F.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a suspension device.

  This type of suspension device includes, for example, four fluid pressure cylinders interposed with suspension springs between a vehicle body and four wheels on the front, rear, left, and right of the vehicle, and a control device for controlling the fluid pressure cylinders. (For example, refer to Patent Document 1).

  In addition to outputting the vehicle height adjustment force to the fluid pressure cylinder, this control device detects the relative displacement between the vehicle body and the front, rear, left and right four wheels to determine the spring force exerted by the suspension spring. The control force exerted by the fluid pressure cylinder is controlled so that the spring constant of the suspension spring becomes smaller according to the speed.

  In the suspension device configured in this way, the spring constant of the suspension spring increases when the vehicle is stopped, and the change in the vehicle body posture can be suppressed when the vehicle is loaded or unloaded, and the apparent spring constant of the suspension spring decreases during traveling. The vehicle body transmission rate of vibration input from road surface unevenness and the like is reduced.

Japanese Patent Laid-Open No. 02-95912

  As described above, in the conventional suspension device, the vehicle body transmission rate of the vibration input from the road surface during traveling of the vehicle is reduced, so that riding comfort is improved. However, when a large lateral acceleration or longitudinal acceleration is generated while the vehicle is running and a force exceeding the limit of the control force that can be exerted by the fluid pressure cylinder is applied to the vehicle body, the roll and pitch of the vehicle body become large. there were.

  Accordingly, the present invention has been developed to improve the above-described problems, and an object of the present invention is to provide a suspension device that can suppress posture changes such as roll and pitch of the vehicle body while improving the riding comfort in the vehicle. It is.

  The suspension device in the problem solving means of the present invention includes a correction unit that corrects a reduction force that reduces the apparent spring constant of the suspension spring based on the lateral acceleration and the longitudinal acceleration. Therefore, when a large lateral acceleration or longitudinal acceleration occurs while the vehicle is running and a force exceeding the limit of the control force that can be exerted by the actuator acts on the vehicle body, the reduction force is reduced by the correction and the suspension is suspended. The apparent spring constant of the spring can be increased.

  In the suspension device according to the second aspect, the correction unit corrects the reduction force to decrease when the absolute value of the longitudinal acceleration and the absolute value of the lateral acceleration become larger than the threshold values set respectively. If the suspension device is configured in this way, in a situation where the apparent spring constant of the suspension spring may be reduced, the spring constant can be lowered to reduce the vibration transmissibility, thereby ensuring the riding comfort in the vehicle. When a situation where priority should be given to restraining the posture change, the apparent spring constant of the suspension spring can be increased to suppress the posture change of the vehicle body B.

  Furthermore, the suspension device according to the third aspect has a stroke sensor for detecting the relative displacement of the unsprung member with respect to the sprung member, and the reducing force calculation unit obtains the reducing force based on the relative displacement. If the suspension device is configured in this way, a constant reduction force is always required with respect to the spring force exerted by the suspension spring, so that the riding comfort can be improved even if the load on the vehicle V changes.

  In the suspension device according to claim 4, the correction unit obtains the lateral acceleration coefficient from the absolute value of the lateral acceleration, obtains the longitudinal acceleration coefficient from the absolute value of the longitudinal acceleration, and reduces the lateral acceleration coefficient and The reduction force is corrected by multiplying by the longitudinal acceleration coefficient. In this way, when the limit of the ride comfort control of the suspension device approaches, the apparent spring constant of the suspension spring increases, causing the driver to recognize that the limit is approaching and causing excessive posture change. Occurrence can be prevented.

  According to the suspension device of the present invention, it is possible to suppress the posture change such as the roll and pitch of the vehicle body while improving the riding comfort in the vehicle.

It is the figure which showed the structure of the suspension apparatus of this invention. It is the figure which showed the structural example of the controller. It is a figure explaining the gravity center of a vehicle, a wheel base, and a tread. It is the figure which showed the relationship between the absolute value of a lateral acceleration, and a lateral acceleration coefficient. It is the figure which showed the relationship between the absolute value of the front-back direction acceleration, and the front-back direction acceleration coefficient.

The present invention will be described below based on the embodiments shown in the drawings. As shown in FIG. 1, the suspension device SD includes a vehicle body B as a sprung member of the vehicle V and four front and rear wheels W _FR , W _FL , W _RR , W _RL as unsprung members of the vehicle V. The four actuators A _FR , A _FL , A _RR , A _RL and the actuators A _FR , A _FL , A _RR , A _RL are installed together with the suspension springs S _FR , S _FL , S _RR , S _RL. And a controller C to be controlled.

The actuators A _FR , A _FL , A _RR , A _RL are extendable, for example, as shown in FIG. 1, and the four wheels W _FR , W _FL , W _RR , front, rear, left and right of the vehicle body B and the vehicle V are a cylinder device AC which is interposed between the W _RL, a liquid and a fluid pressure control device HC extending and retracting the respective cylinder devices AC by supplying and discharging the cylinder device AC. The fluid pressure control device HC may be provided individually for each cylinder device AC. However, as in the present example, if the liquid is distributed from one fluid pressure control device HC to the four cylinder devices AC, the fluid pressure control device HC The pressure controller HC can be integrated and the cost can be reduced.

Although not shown, the hydraulic pressure control device HC controls, for example, a pump, a hydraulic pressure circuit, a switching valve that is provided in the hydraulic pressure circuit and switches expansion and contraction of the cylinder device AC, and pressure in the cylinder device AC. A control valve and a drive control unit for driving these pumps and various valves are provided. Then, the hydraulic pressure control device HC adjusts the pressure in the cylinder device AC in accordance with a command from the controller C to control the expansion and contraction direction and thrust of the cylinder device AC, thereby causing the cylinder device AC to function as an active suspension. ing. In this way, the controller C controls the thrust in each actuator A _FR , A _FL , A _RR , A _RL according to the control force determined by itself.

Cylinder device AC can body B and the wheels _W FR of the end vehicle _V, W _FL, W _RR, connected to one of _{W RL,} the other end of the vehicle body B and wheel _{W FR, W FL, W RR} , W RL coupled to the other of the vehicle body B and the wheels _{W FR, W FL, W RR} , is interposed between the _{W RL.} In addition to the suspension springs S _FR , S _FL , S _RR , S _RL in addition to the suspension springs S _FR , S _FL , S _RR , S _RL between the vehicle body B and the wheels W _FR , W _FL , W _RR , W _RL. Are intervened. Note that the damper D may be omitted, for example, by incorporating a circuit that allows each cylinder device AC to function as the passive damper D in the hydraulic pressure control device HC.

As shown in FIG. 2, the controller C is installed in the vehicle body B and includes three acceleration sensors 21, 22, and 23 that detect the vertical accelerations G ₁ , G ₂ , and G ₃ , respectively. An acceleration sensor 24 that detects the lateral acceleration G _lat of B, an acceleration sensor 25 that is installed in the vehicle body B and detects the longitudinal acceleration G _long of the vehicle body B, and four wheels W _FR , W _FL , W _RR , W relative displacement _H FR of the right above each wheel _RL and the vehicle body _B, H _FL, H _RR, a stroke sensor 26, 27, 28, 29 for detecting the _{H RL,} a control force calculating section 30, a reduced force calculation unit 31 The correction unit 32 and the subtraction unit 33 are provided.

The acceleration sensors 21, 22, and 23 detect the vertical accelerations G ₁ , G ₂ , and G ₃ of the vehicle body B, and are installed at any three locations that are not on the same straight line in the front-rear or left-right direction of the vehicle body B. Has been. The acceleration sensors 21, 22, and 23 output the detected vertical accelerations G ₁ , G ₂ , and G ₃ to the control force calculation unit 30. The acceleration sensor 24 and the acceleration sensor 25 input the detected lateral acceleration G _lat and longitudinal acceleration G _long to the control force calculation unit 30, respectively. The stroke sensors 26, 27, 28, and 29 input the detected relative displacements H _FR , H _FL , H _RR , and H _RL to the reduction force calculation unit 31, respectively. If the stroke sensors 26, 27, 28, 29 are integrated in the cylinder device AC, the installation becomes easy, and the suspension device SD can be incorporated into the vehicle V without difficulty.

Control force calculating unit 30, in this example, processes the vertical acceleration _{G 1, G 2, G 3} , bounce velocity _{V B} of the vehicle body B, and the pitch angular velocity _{V P} and roll angular velocity _{V R} determined, bounce velocity V _B, the pitch angular velocity _{V P,} the roll angular velocity _{V R} and the lateral acceleration _{G lat} and four actuator _a FR from the longitudinal acceleration _{G long, a FL, a RR} , a RL should exhibit controlled force _{F AFR, F AFL,} F _ARR and F _ARL are obtained.

Here, assuming that the vehicle body B is a rigid body and obtaining the vertical speeds of any three locations that are not on the same straight line in the front-rear or left-right direction of the vehicle body B, the vertical direction, the front-rear direction rotation, and the lateral direction of the vehicle body B Each speed of rotation is obtained. Bounce speed _{V B,} to determine the pitch angular velocity _{V P} and roll angular velocity _{V R,} the control force calculating section 30 first integrates the vertical acceleration _{G 1, G 2, G 3} , three speeds of the vertical direction Ask for. Then, the control force calculating unit 30 includes a bounce velocity V _B is the vertical velocity at the center of gravity of the vehicle body B from these speeds, the pitch angular velocity V _P is the angular velocity of the longitudinal rotation of the gravity center position, the gravity center position Request roll velocity V _R is the lateral rotation of the angular velocity of. Therefore, the acceleration sensors 21, 22, and 23 are provided at arbitrary three locations that are not on the same straight line in the front-rear or left-right direction of the vehicle body B.

Furthermore, the control force calculating unit 30, bounce velocity V _B obtained as described _above, the pitch angular velocity V _P and roll angular velocity V _R, the lateral acceleration G _lat and longitudinal acceleration detected by the acceleration sensor 24 and the acceleration sensor 25 control force _F AFR from _{G long, F AFL, F ARR} , seek _{F ARL.}

As shown in FIG. 3, the longitudinal distance from the center of gravity to the front wheels W _FR , W _FL is L _F, and the longitudinal distance from the center of gravity to the rear wheels W _RR , W _RL is L _R , Also, let T be the tread of the right wheel W _FR (W _RR ) and the left wheel W _FL (W _RL ). Control force calculating unit 30 obtains a force to dampen the vertical vibration of the vehicle body B by multiplying a gain to bounce velocity V _B.

The control force calculating unit 30, in this embodiment, it obtains the pitch direction of the damping moment is multiplied by a gain in the pitch angular velocity V _P, the pitch of the vehicle body B by dividing the attenuation moment wheelbase _(L F ₊ L _R) Find the force to control the vibration caused by.

Furthermore, the control force calculating unit 30, in this example, determine the roll direction of the damping moment is multiplied by a gain roll velocity V _R, to dampen the vibration caused by the roll of the vehicle body B by dividing the attenuation moment tread W Seeking power for.

Further, in this example, the control force calculation unit 30 multiplies the input longitudinal acceleration G _long by a gain to obtain a force necessary to prevent the pitch of the vehicle body B due to the inertial force acting in the longitudinal direction.

The control force calculating unit 30 multiplies the input lateral acceleration G _lat by a gain to obtain a force necessary to prevent the vehicle body B from being rolled by centrifugal force.

Finally, in this example, the control force calculation unit 30 calculates the control forces F _AFR , F _AFL , F _ARR , F _ARL to be generated by the actuators A _FR , A _FL , A _RR , A _RL from these five forces. Ask. The control force is obtained by setting the sign of the downward force as positive and the sign of the upward force as negative.

In order to suppress the bounce of the vehicle body B, the actuators A _FR , A _FL , A _RR , and A _RL need to generate forces of the same magnitude in the same direction. In order to suppress the pitch of the vehicle body B, the front actuators A _FR , A _FL and the rear actuators A _RR , A _RL must exhibit the same magnitude and opposite directions. In order to suppress the roll of the vehicle body B, the right actuators A _FR and A _RR and the left actuators A _FL and A _RL need to exhibit the same magnitude and opposite directions.

Therefore, the control force calculating unit 30, force to suppress the bounce determined from bouncing velocity V _B, force to suppress the pitch obtained from the pitch angular velocity V _P and lateral acceleration G _lat, roll angular velocity V _R and the longitudinal acceleration G _The control force F _AFR , F to be generated by each actuator A _FR , A _FL , A _RR , A _RL by adding the force to suppress the roll obtained from the _{long so as} to suppress the bounce, pitch and roll of the vehicle body B _AFL , F _ARR and F _ARL are obtained. The obtained control forces F _AFR , F _AFL , F _ARR , and F _ARL are input to the subtractor 33.

The reduction force calculation unit 31 reduces the reduction forces F _CFR , F _CFL that reduce the apparent spring constant of the suspension springs S _FR , S _FL , S _RR , S _RL from the relative displacements H _FR , H _FL , H _RR , H _RL. , F _CRR , F _CRL are obtained. Specifically, the reduction force calculation unit 31 multiplies the relative displacements H _FR and H _FL by the front wheel side gain G _SPF, and multiplies the relative displacements H _RR and H _RL by the rear wheel side gain G _SPR respectively. _CFR , F _CFL , F _CRR , and F _CRL are obtained. The reduction forces F _CFR , F _CFL , F _CRR , and F _CRL thus obtained are corrected by the correction unit 32 and then subtracted from the control forces F _AFR , F _AFL , F _ARR , and F _ARL of each wheel by the subtraction unit 33. .

For example, if the final control force, which is the final control force generated in the front right actuator A _FR , is _FTFR , if the correction by the correction unit 32 is ignored, the final control force is _FTFR = F _AFR −F It is calculated by _{CFR = F AFR -H FR · G} SPF. On the other hand, if the spring constant of the suspension spring _{S FR} and _{K SPF,} the spring force _{F SPF} of the suspension spring _{S FR} exerts on the vehicle body _is described as _{F SPF = K SPF · H FR} . Therefore, when the actuator _{A FR} is exerted a final control force _{F TFR,} the portion above the actuator _{A FR} of the vehicle body B, the spring force _{F SPF} of final control force _{F TFR} and suspension spring _{S FR} acts. The total spring force _{F SPF} of final control force _{F TFR} and the suspension spring _{S FR becomes F TFR + F SPF = F AFR} + (K SPF -G SPF) · H FR. Therefore, seeking final control force _{F TFR} As described above, when the actuator _{A FR} exerts final control force _{F TFR,} the spring constant of the suspension spring _{S FR} is reduced apparently from _{K SPF} only _{G SPF,} and the vehicle body B The natural frequency of the system composed of the suspension spring _SFR is reduced and the riding comfort is improved. The reduction force calculation unit 31 obtains the reduction forces F _CFR , F _CFL , F _CRR , and F _CRL for each wheel, and the controller C calculates the reduction force F from the control forces F _AFR , F _AFL , F _ARR , and F _ARL for each wheel. _{CFR, F} CFL, _F CRR, by subtracting _{F CRL,} final control force _F TFR for each _wheel, F _TFL, F _TRR, seek _{F TRL.} Thus, since the controller C calculates the final control forces F _TFR , F _TFL , F _TRR , F _TRL , the spring constants of the suspension springs S _FR , S _FL , S _RR , S _RL of the vehicle V are substantially reduced. This can improve the riding comfort of the vehicle. In general, the front wheel gain _GSPF is the same value for the left and right wheels, and the rear wheel gain _GSPR is the same value for the left and right wheels. This is because the constants are the same for the front left and right wheels and the same for the rear left and right wheels, but if appropriate for the vehicle V, the gain to multiply the relative displacement in each of the four wheels is arbitrarily set. it can.

Subsequently, the correction unit 32 corrects the reduction forces F _CFR , F _CFL , F _CRR , and F _CRL obtained by the reduction force calculation unit 31 based on the lateral acceleration G _lat and the longitudinal acceleration G _long , respectively. Specifically, the correction unit 32, reduces force _{F CFR, F CFL, F CRR} , the lateral acceleration coefficient gamma ₁ obtained from the absolute value of the lateral acceleration _{G lat} to _{F CRL} absolute value of the longitudinal acceleration _{G long} The reduction forces F _CFR , F _CFL , F _CRR , and F _CRL are corrected by multiplying by the longitudinal acceleration coefficient γ ₂ obtained from the above.

As shown in FIG. 4, the lateral acceleration coefficient γ ₁ takes a value of 1 until the absolute value of the lateral acceleration G _{lat reaches} the first lateral acceleration threshold G _lat1 and exceeds the first lateral acceleration threshold G _lat1 . The value is gradually decreased from 1 and 1 and is set to take a value of 0 when the second lateral acceleration threshold value G _lat2 is exceeded.

As shown in FIG. 5, the longitudinal acceleration coefficient γ ₂ takes a value of 1 until the absolute value of the longitudinal acceleration G _{long reaches} the first longitudinal acceleration threshold G _long1, and exceeds the first longitudinal acceleration threshold G _long1 . The value is gradually decreased from 1 and 1 and is set to take a value of 0 when the second longitudinal acceleration threshold G _long2 is exceeded. The _{values of} the first lateral acceleration threshold G _lat , the second lateral acceleration threshold G _{lat 2} , the first longitudinal acceleration threshold G _{long 1,} and the second longitudinal acceleration threshold G _long 2 are the actuators A _FR , A _FL , A _RR , A _It may be determined in consideration of the maximum force that can generate _RL . In other words, the first lateral acceleration threshold value G _lat1 , the second lateral direction so that the rolls, pitches, and bounces of the vehicle body B do not become excessive due to the reducing forces F _CFR , F _CFL , F _CRR , F _CRL . The acceleration threshold value G _lat2 , the first longitudinal acceleration threshold value G _long1, and the second longitudinal acceleration threshold value G _long2 may be set.

The reduction forces F ′ _CFR , F ′ _CFL , F ′ _CRR and F ′ _CRL corrected by the correction unit 32 in this way are input to the subtraction unit 33. The subtracting unit 33 subtracts the reducing forces F ′ _CFR , F ′ _CFL , F ′ _CRR , and F ′ _CRL from the control forces F _AFR , F _AFL , F _ARR , and F _ARL obtained by the control force calculating unit 30 for final control. The forces _FTFR , _FTFL , _FTRR , and _FTRL are obtained.

The controller C, thus the obtained final control force _{F TFR, F TFL, F TRR} , and outputs the _{F TRL} to fluid pressure control device HC. Fluid pressure control device HC, the pump drives the respective main valves, the input final control force _{F TFR, F TFL, F TRR} , F TRL actuator _A FR in _street, A _FL, A _RR, control the _{A RL} Demonstrate power.

In this example, the actuators A _FR , A _FL , A _RR , A _RL are hydraulic actuators having a cylinder device AC and a hydraulic circuit, but the actuators A _FR , A _FL , A _RR , A _{The RL} may be an electric actuator using a motor. The actuators A _FR , A _FL , A _RR , A _RL may be pneumatic actuators that are driven by air pressure.

As described above, the suspension device SD allows the actuators A _FR , A _FL , A _RR , A _RL to exert the force to suppress the posture change such as roll, pitch, and bounce of the vehicle body B, and the suspension springs S _FR , S _{FL, S RR,} reduces the apparent spring constant of the _{S RL.} Therefore, the suspension device SD can reduce the vehicle body transmission rate of vibration input from the road surface while the vehicle is traveling, and can improve the riding comfort in the vehicle V.

In the suspension device SD of the present invention, the reduction force that reduces the apparent spring constant of the suspension springs S _FR , S _FL , S _RR , S _RL is corrected based on the lateral acceleration G _lat and the longitudinal acceleration G _long. A correction unit 32 is provided. Therefore, a situation in which a large lateral acceleration or longitudinal acceleration is generated during traveling of the vehicle, and a force exceeding the limit of the control force that can be exerted by the actuators A _FR , A _FL , A _RR , A _RL acts on the vehicle body B. Then, the reduction forces F ′ _CFR , F ′ _CFL , F ′ _CRR , and F ′ _CRL can be reduced by correction to increase the apparent spring constants of the suspension springs S _FR , S _FL , S _RR , and S _RL . As described above, the suspension device SD reduces the apparent spring constant of the suspension springs S _FR , S _FL , S _RR , S _RL when a large lateral acceleration or longitudinal acceleration does not act on the vehicle body B during vehicle travel. Thus, when a large lateral acceleration or longitudinal acceleration is applied to the vehicle body B while improving the riding comfort in the vehicle V, the apparent spring constants of the suspension springs S _FR , S _FL , S _RR , S _RL are increased. The roll and pitch of B can be suppressed.

  As described above, according to the suspension device SD of the present invention, it is possible to suppress the posture change such as the roll and pitch of the vehicle body B while improving the riding comfort in the vehicle V.

Further, in this example, the correction unit 32 uses the first longitudinal acceleration threshold G _long1 and the first lateral acceleration, which are thresholds for setting the absolute value of the longitudinal acceleration G _{long and} the absolute value of the lateral acceleration G _lat , respectively. When it becomes larger than the threshold value G _lat1 , the reduction forces F _CFR , F _CFL , F _CRR , and F _CRL are corrected so as to decrease. When the suspension device SD is configured in this way, in a situation where the apparent spring constants of the suspension springs S _FR , S _FL , S _RR , S _RL may be reduced, the spring constant is lowered to reduce the vibration transmissibility. When the riding comfort in the vehicle V can be ensured and priority is given to the suppression of the posture change of the vehicle body B, the apparent spring constants of the suspension springs S _FR , S _FL , S _RR , S _RL are increased to increase the vehicle body B. Can prevent changes in posture.

Furthermore, in this example, a stroke sensor that detects relative displacements H _FR , H _FL , H _RR , and H _RL of the wheels W _FR , W _FL , W _RR , and W _RL that are unsprung members with respect to the vehicle body B that is a sprung member. 26, 27, 28, and 29 so that the reduction force calculation unit 31 obtains the reduction forces F _CFR , F _CFL , F _CRR , and F _CRL based on the relative displacements H _FR , H _FL , H _RR , and H _RL. It has become. When the suspension device SD is configured in this way, the reduction forces F _CFR , F _CFL , F _CRR , and F _CRL are always obtained at a constant ratio with respect to the spring force exerted by the suspension springs S _FR , S _FL , S _RR , and S _RL. Therefore, the riding comfort can be improved even if the loading amount on the vehicle V changes.

Further, in this example, the correction unit 32 obtains the lateral acceleration coefficient γ ₁ from the absolute value of the lateral acceleration G _lat and obtains the longitudinal acceleration coefficient γ ₂ from the absolute value of the longitudinal acceleration G _long to reduce the reduction force. The reduction forces F _CFR , F _CFL , F _CRR , and F _CRL are corrected by multiplying F _CFR , F _CFL , F _CRR , and F _CRL by the lateral acceleration coefficient γ ₁ and the longitudinal acceleration coefficient γ ₂ . In this way, the lateral acceleration coefficient γ ₁ is gradually decreased as the absolute value of the lateral acceleration G _lat increases, and the longitudinal acceleration coefficient γ ₂ is gradually decreased as the absolute value of the longitudinal acceleration G _long increases. Thus, if these are multiplied by the reducing forces F _CFR , F _CFL , F _CRR , and F _CRL , the suspension increases as the absolute value of the lateral acceleration G _{lat and} the absolute value of the longitudinal acceleration G _long increase. spring _{S FR, S FL, S RR} , S RL apparent suspended from the spring constant spring _S FR _of, S _FL, S _RR, so changes to the actual spring constant of the _{S RL.} In this way, the apparent spring constants of the suspension springs S _FR , S _FL , S _RR , S _RL become higher when the limit is reached where the change in the posture of the vehicle body B cannot be suppressed by the control that gives priority to riding comfort. By making the driver recognize that the limit is approaching, excessive posture changes can be prevented.

In this example, the control force calculating section 30, lateral acceleration _{G lat,} longitudinal acceleration _{G long,} bouncing velocity _{V B,} the control to suppress the attitude change of the vehicle body B from the pitch angular velocity _{V P} and roll angular velocity _{V R} However, the control is merely an example, and the control forces F _AFR , F _AFL , F _ARR , and F _ARL may be obtained using other control laws such as skyhook control.

In this example, the lateral acceleration coefficient γ ₁ and the longitudinal acceleration coefficient γ ₂ change from 1 to 0 depending on the magnitude of the absolute value of each acceleration in the lateral direction and the longitudinal direction. If appropriate, the minimum value may be set to a value larger than 0 and smaller than 0.5.

The relative displacements H _FR , H _FL , H _RR , H _RL of the wheels W _FR , W _FL , W _RR , W _RL and the vehicle body B are detected in the vertical direction detected by the acceleration sensors 21, 22, 23 provided on the vehicle body B. It can be obtained by using the accelerations G ₁ , G ₂ , G ₃ and the vertical accelerations of the wheels W _FR , W _FL , W _RR , W _RL . Therefore, instead of providing the stroke sensor 26, 27, 28, 29, the wheels _{W FR, W FL, W RR} , it may be provided an acceleration sensor for detecting a vertical acceleration of the _{W RL.}

  This is the end of the description of the embodiments of the present invention, but the scope of the present invention is not limited to the details shown or described.

A _FR , A _FL , A _RR , A _RL ... Actuator, B ... Car body (sprung member), C ... Controller, S _FR , S _FL , S _RR , S _RL ... Suspension spring, V: vehicle, W _FR , W _FL , W _RR , W _RL ... wheel (unsprung member), 31 ... reduction force calculation unit, 32 ... correction unit, 26, 27, 28, 29 ... Stroke sensors

Claims (4)

An actuator interposed with a suspension spring between a sprung member and an unsprung member of the vehicle;
A controller for controlling the actuator,
The controller is
A reduction force calculation unit for obtaining a reduction force for reducing the apparent spring constant of the suspension spring;
A correction unit that corrects the reduction force based on longitudinal acceleration and lateral acceleration acting on the sprung member;
A suspension device, wherein a final control force is obtained by subtracting the reduction force corrected by the correction unit from a control force of the actuator. The correction unit corrects the reduction force so as to decrease when the absolute value of the longitudinal acceleration and the absolute value of the lateral acceleration are larger than thresholds set respectively. The suspension device described in 1. A stroke sensor for detecting relative displacement of the unsprung member with respect to the sprung member;
The suspension device according to claim 1, wherein the reduction force calculation unit obtains the reduction force based on the relative displacement. The correction unit obtains a longitudinal acceleration coefficient from the absolute value of the longitudinal acceleration, obtains a lateral acceleration coefficient from the absolute value of the lateral acceleration, and uses the longitudinal acceleration coefficient and the lateral acceleration as the reduction force. The suspension device according to any one of claims 1 to 3, wherein the reduction force is corrected by multiplying by a coefficient.

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