JPH05338421A - Suspension device - Google Patents

Abstract

PURPOSE:To reduce the working number of a pressure source by providing a control valve opening and closing means to regulate pressure in a cylinder by way of opening and closing a control valve at the time when car height is abnormal and a PV product is abnormal. CONSTITUTION:The device is provided with a car height abnormality judgement means 22 to judge that car height is abnormal when a vehicle exceeds a specified range, an integrating means to find a PV product which is a product of pressure and capacity by way of integrating the detected pressure of a pressure sensor 30 and the measured capacity of a capacity measurement means 22 and a PV product abnormality judgement means 22 to judge that the PV product is abnormal at the time when the PV product exceeds the specified range. Additionally, when the car height is abnormal and the PV product is abnormal, pressure in cylinders 14-17 is regulated by opening and closing control valves SFL, SFR, SRL, SRR by a control valve opening and closing means 22.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a suspension device for a vehicle, and is particularly suitable for a suspension device for an automobile using air as a drive source.

[0002]

2. Description of the Related Art Conventionally, if it is attempted to control each wheel independently from four vehicle height sensors provided on each wheel,
The wheel indeterminacy problem occurs, and the solution of the load on each wheel becomes infinite.

Therefore, in an apparatus for adjusting the vehicle height of an automobile having four wheels, two rear wheels are simultaneously controlled so that two front wheels and one rear wheel are supported at three points so that the vehicle is not warped. I've been to However, when a roll is generated on the rear wheel side, there is no means for suppressing the roll, so that the roll cannot be suppressed. In order to deal with this, a technique has been developed, as disclosed in Japanese Patent Laid-Open No. 1-145216, in which four wheels are independently controlled, the occurrence of a warp is detected, and the control is interrupted when the warp occurs. ..

[0004]

In the above technique, the vehicle height value is measured, and the vehicle height of each wheel is controlled by the deviation from the vehicle height target value. Therefore, if the vehicle height value changes frequently during traveling, control is performed in an attempt to restore the vehicle height value to the original value each time. The frequency of control is high especially when driving on a rough road. For this reason, the pressure source such as a compressor is operated many times, and it is necessary to use a pressure source having high durability.

Therefore, it is an object of the present invention to reduce the number of operations of the pressure source.

[0006]

In order to solve the above-mentioned problems, the means used in the present invention is a cylinder which is arranged between a wheel and a vehicle body, and in which the distance between the wheel and the vehicle body can be adjusted by the pressure supplied to the inside. In a suspension device including a control valve for supplying and exhausting pressure to and from the cylinder, a pressure sensor for detecting the pressure in the cylinder, and a volume measuring unit for measuring the volume in the cylinder, the vehicle height exceeds a predetermined range. Vehicle height abnormality determining means for determining that the vehicle height is abnormal, and integrating means for integrating the pressure detected by the pressure sensor and the volume measured by the volume measuring means to obtain a PV product which is the product of the pressure and the volume.
When the PV product exceeds the predetermined range, it is judged as an abnormal PV product P
The V product abnormality determining means and the control valve opening / closing means for opening / closing the control valve to adjust the pressure in the cylinder when the vehicle height is abnormal and the PV product is abnormal are provided.

[0007]

According to the above means, even if the vehicle height changes frequently during traveling on a bad road, the pressure is not supplied to or discharged from the cylinder unless the vehicle height exceeds a predetermined range. Further, even if the vehicle height exceeds a predetermined range, the pressure is not supplied to or discharged from the cylinder unless the product of the pressure and the volume in the cylinder changes. Normally, when a vehicle climbs over a step during traveling, the vehicle height shrinks, but the pressure in the cylinder rises accordingly. In such a case, the above means does not control. In addition, it does not operate even if the heave changes due to changes in load due to loading of luggage or passengers getting on and off, rolls due to turning or cross wind, and pitches due to sudden braking or sudden starting. However, when pressure leaks from piping, etc., the product of the pressure and volume in the cylinder changes, and control is performed to suppress this change.Therefore, unnecessary control is not performed, and a pressure source that generates pressure is used. The number of operations of is reduced and the service life is extended.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. This embodiment discloses an air suspension device using air, but other compressible fluid may be used. In this embodiment, a motor M as a pressure source and a pump RP that is rotated by the motor M to generate air pressure.
(Compressor) is used.

In FIG. 1, the front left wheel 10, the front right wheel 11,
A cylinder 14 is provided between the rear left wheel 12 and the rear right wheel 13 and the vehicle body.
~ 17 are attached. The cylinders 14 to 17 increase the distance between the wheel and the vehicle body by increasing the internal pressure, and decrease the distance between the wheel and the vehicle body by decreasing the internal pressure. The distance between the wheel and the vehicle body, that is, the vehicle height is detected by vehicle height sensors 18 to 21 provided for each wheel, and the output thereof is sent to an electronic control unit (ECU) 22. As will be described later, the detection output of the vehicle height sensor is used to calculate the volume in the cylinder by adding the dead space of the cylinder and then integrating the pressure receiving area of the cylinder. The vehicle body is equipped with a pump RP which is a pressure source. The pump RP is connected to the motor M driven by the electronic control unit 22, and the rotation of the motor M generates pressure in the pipe 32. The pipe 32 is connected to the drain 31 via a discharge solenoid valve EX driven by the electronic control unit 22. When the discharge solenoid valve EX is opened, the pressure in the pipe 32 is discharged to the atmosphere. The front left wheel solenoid valve SFL driven by the electronic control unit 22 is disposed between the pipe 32 and the pipe 33 connected to the front left wheel cylinder 14. When the front left wheel solenoid valve SFL is opened, the pump RP
Alternatively, the pressure in the cylinder 14 can be increased or decreased by operating the discharge solenoid valve EX to change the vehicle height of the front left wheel. The front right wheel solenoid valve SFR driven by the electronic control unit 22 is arranged between the pipe 32 and the pipe 34 connected to the front right wheel cylinder 15. When the front right wheel solenoid valve SFR is opened, the pump RP or the discharge solenoid valve E is opened.
By operating X, the pressure in the cylinder 15 can be increased or decreased to change the vehicle height of the front right wheel. The rear left solenoid valve SRL driven by the electronic control unit 22 is provided with the pipe 32.
And a pipe 35 connected to the rear left wheel cylinder 16. When the rear left wheel solenoid valve SRL is opened, the pressure in the cylinder 16 can be increased or decreased by operating the pump RP or the discharge solenoid valve EX, and the vehicle height of the rear left wheel can be changed. The solenoid valve SRR for the rear right wheel driven by the electronic control unit 22 is arranged between the pipe 32 and the pipe 36 connected to the cylinder 17 of the rear right wheel.
When the rear right wheel solenoid valve SRR is opened, the pressure in the cylinder 17 can be increased or decreased by operating the pump RP or the discharge solenoid valve EX, and the vehicle height of the rear right wheel can be changed. The pressure in the pipe 32 is measured by the pressure sensor 30 and sent to the electronic control unit 22. Further, a door switch 24 for detecting opening / closing of the vehicle door is provided on the vehicle,
The door switch 24 sends a detection signal to the electronic control unit 22.

The operation of the electronic control unit 22 is shown in FIGS.
A description will be given along the flowchart shown in FIG.

FIG. 2 is a main routine of the electronic control unit 22. When the electronic control unit 22 starts,
First, in step 40, initialization is performed. Here, flags and variables used for the following control are set to initial values. Next, the routine shown in steps 41 to 44 is repeated. Step 41 is an input processing routine in which information from each sensor is input. Next, in step 42, it is determined whether or not the vehicle is currently stopped. When the vehicle is stopped and the door moves from open to closed (step 45), the target PV product calculation routine of step 43 is executed, and if the vehicle is running, the control object selection / output routine of step 44 is executed. .. Whether the vehicle is stopped and the door is opened / closed is to detect that the load of the vehicle has changed. When the load of the vehicle fluctuates due to loading of luggage or getting on / off of passengers, the target P is set to reset the target PV product.
V product operation is performed. In addition to the door switch, the opening / closing of the trunk may be detected or the load of the vehicle may be directly measured.

The details of the input processing routine of step 41 are shown in FIG. First, in step 50, the pressure sensor 30
Is substituted into the variable P, and the pressures PFL, PFR, PRL, PRR of the respective wheels are updated in steps 51 to 58 according to the states of the solenoid valves SFL, SFR, SRL, SRR.
As will be described later, in the controlled object selection / output routine, only one of the solenoid valves SFL, SFR, SRL and SRR is set to the ON state. When the solenoid valve is turned on, the ring cylinder connected to the solenoid valve is connected to the pipe 32. Therefore, the output of the pressure sensor 30 provided in the pipe 32 becomes the pressure value of the cylinder of the selected wheel. In step 59, the outputs of the vehicle height sensors 18 to 21 provided for the respective wheels are set to the vehicle height values HFL and HF, respectively.
Set to R, HRL, HRR. As described above, in the input processing routine, the pressure value and the vehicle height value of each wheel are obtained from the sensor output.

The details of the target PV product calculation routine of step 43 are shown in FIG. Here, the initial PV is corrected by taking into consideration the movement of the center of gravity of the vehicle due to loading of luggage, etc.
Find the product. First, the ground load of each wheel WFL, WFR, W
Calculate RL and WRR. The ground contact load is obtained by the equation 1 in step 60.

[0014]

## EQU1 ## WFL = SF × PFL + (HFL-HFR) × KF WFR = SF × PFR + (HFR-HFL) × KF WRL = SR × PRL + (HRL-HRR) × KR WRR = SR × PRR + (HRR-HFL) × KR where KF and KR are stabilizer constants of the front and rear wheels.

Next, in step 61, the ground contact loads of the respective wheels thus obtained are summed up to obtain the total vehicle weight W (Equation 2).
formula).

[0016]

## EQU2 ## W = WFL + WFR + WRL + WRR Further, the position of the center of gravity of the vehicle is obtained from the above calculation result. As shown in FIG. 9, the position of the center of gravity of the vehicle is LH, the distance between the wheel bases is LT, and the distances from the center of gravity to the sides are L1, L2, L3, and L4. Formula 3 and the balance in the roll direction are as shown in Formula 4, and L1, L2, L3, L4 and LH, LT
Since the relation of is as shown in Equation 5, L1, L2, L3
L4 is obtained by Equation 6 which is a modification of Equations 2-5. The center of gravity positions L1, L2, L3 and L4 are obtained in step 61.

[0017]

(3) (WFL + WFR) × L1 = (WRL + WRR) × L2

[0018]

(4) (WFL + WRL) × L4 = (WFR + WRR) × L3

[0019]

[Formula 5] L1 + L2 = LH L3 + L4 = LT

[0020]

L1 = (WRL + WRR) × LH / W L2 = (WFL + WFR) × LH / W L3 = (WFR + WRR) × LT / W L4 = (WFL + WRL) × LT / W L1, L2, L3 obtained here Redistribute load from L4. First, considering the pitch direction, when the sum of loads between the front wheels is W1 and the sum of loads between the rear wheels is W2 in FIG. 9, the equation 7 is established. Further, since the sum of W1 and W2 is W as in the formula 8, the formula 9 is established by the formula 7 and the formula 8.

[0021]

[Equation 7] W1 × L1 = W2 × L2

[0022]

[Equation 8] W1 + W2 = W

[0023]

## EQU00009 ## W1 = L2 / (L1 + L2) .times.W W2 = L1 / (L1 + L2) .times.W Next, considering the roll direction, the formula 10 is established from the balance in the roll direction.

[0024]

## EQU10 ## WFL.times.L4 = WFR.times.L3 WRL.times.L4 = WRR.times.L3 Further, WFL, WFR, WRL, and WRR can be described by using W1 and W2 as shown in Formula 11.

[0025]

[Formula 11] WFL = L3 / (L3 + L4) × W1 WFR = L4 / (L3 + L4) × W1 WRL = L3 / (L3 + L4) × W2 WRR = L4 / (L3 + L4) × W2 Then, the above formula 12 is obtained. Be done. Therefore, in step 62, the redistributed load is calculated from the total vehicle weight W and the center of gravity positions L1, L2, L3, L4 based on the equation (12).

[0026]

WFL = L2 / (L1 + L2) × L3 / (L3 + L4) × W WFR = L2 / (L1 + L2) × L4 / (L3 + L4) × W WRL = L1 / (L1 + L2) × L3 / (L3 + L4) × W WRR = L1 / (L1 + L2) × L4 / (L3 + L4) × W The initial pressure of each wheel is obtained from the redistributed load.
The initial pressure of each wheel is obtained by the equation (13). Step 6
At 3, this initial pressure value is obtained.

[0027]

PFL0 = (WFL− (HFL−HFR) × KF) / SF PFR0 = (WFR− (HFR−HFL) × KF) / SF PRL0 = (WRL− (HRL−HRR) × KR) / SR PRR0 = (WRR- (HRR-HRL) * KR) / SR As described above, the ground load WFL, WF of each wheel is calculated from the equation (1).
R, WRL, WRR are calculated, and the center of gravity position L
1. L2. L3. L4 is calculated, the loads WFL, WFR, WRL, WRR of each wheel are distributed according to the position of the center of gravity by the formula 12, and the pressure PFL, PFL of each wheel is further distributed from the distributed load.
By obtaining FR, PRL, and PRR and performing control with this pressure value as the target pressure, the target value is set so as to remove the load warp even if the load warp occurs in the vehicle at the initial time. Can be resolved immediately. Therefore, in step 64, the target P is calculated from the obtained initial pressure values PFL0, PFR0, PRL0, PRR0.
The V product is calculated according to the equation (14).

[0028]

PVFL0 = PFL0 × SF × (HFL-HF0) PVFR0 = PFR0 × SF × (HFR-HF0) PVRL0 = PRL0 × SR × (HRL-HR0) PVRR0 = PRR0 × SR × (HRR-HR0) where , HF0, HR0 are dead spaces, S
F and SR are pressure receiving areas of the cylinder. The dead space usually has different cylinders on the front wheel side and the rear wheel side. Also, the pressure receiving area of the cylinder is different between the front wheel side and the rear wheel side. The volume in the cylinder is obtained from the product of the stroke of the cylinder and the pressure receiving area of the cylinder. The cylinder stroke is the vehicle height minus the dead space. Therefore, the target PV product of each wheel is as shown in Expression 14.

Next, details of the control object selection / output routine of step 44 are shown in FIG. Here, the target wheel to be controlled is obtained from the vehicle height value and the pressure value, and the pressure is adjusted. First, in step 70, it is determined whether or not the flag Fcont is 0. The flag Fcont indicates whether or not pressure control is in progress. When the flag Fcont is 0, it indicates that control is not in progress, and when it is 1, it indicates that control is in progress. Next, Step 71
Check the vehicle height abnormality. Although details of this routine will be described later, generally speaking, when any one of the vehicle heights of the respective wheels becomes abnormal, a flag Fabn indicating a vehicle height abnormality is set to 1, and the wheel whose vehicle height value becomes abnormal is the target wheel. Is specified as. In step 72, if the value of the flag Fabn is 0 (normal vehicle height), this routine is terminated, and if the value of the flag Fabn is 1 (abnormal vehicle height), the routine proceeds to step 73. In step 73, the solenoid valve corresponding to the target wheel is opened. For example,
When the vehicle height of the front left wheel becomes abnormal, the front left wheel solenoid valve S
Drive FL to open. The solenoid valves on the other wheels remain closed. As a result, the cylinder of the target wheel and the pressure sensor 30
Can communicate with each other and the pressure of the cylinder of the target wheel can be measured. still,
In step 74, a predetermined time is waited until the opening pressure of the solenoid valve becomes stable. Then, the PV product PVxx of the target wheel is calculated from the pressure Pxx of the target wheel and the vehicle height Hxx of the target wheel. still,
xx shows the object among FL, FR, RL, and RR. The PV product PVxx is calculated based on the following equation.

[0030]

PVxx = Pxx × Sxx × (Hxx−Hx0) where Sx is the pressure receiving area of the cylinder and Hx0 is the dead space. In the case of the front wheel, F is entered, and in the case of the rear wheel, R is entered. Next, at step 76, the target P
It is determined whether or not the difference between the V product PVxx0 and the obtained PV product PVxx is within a predetermined value ΔPV. Where the target P
If the deviation of the PV product from the V product is within ΔPV, it is determined that the PV product is normal, and in step 77, the solenoid valve of the target wheel is closed and the process returns to the main routine. When the deviation of the PV product from the target PV product exceeds ΔPV, it is determined that the PV product is abnormal, and the control start process is performed in step 78.
In step 78, the drive of the pump RP or the discharge solenoid valve EX is instructed to start adjusting the pressure of the target wheel. Also,
At this time, the flag Fcont indicating that control is in progress is set to 1, and then the process returns to the main routine. If the vehicle is traveling in the main routine, the controlled object selection / output routine is executed again. When the controlled object selection / output routine is executed (during control) after the flag Fcont becomes 1 (step 70)
In step S79, the state of the flag Fcont is determined, and step 79 is executed. Step 79 is a control end determination / processing routine. Here, it is determined whether to continue the pressure adjustment or to end the pressure adjustment, and when it is ended, the pump RP or the electromagnetic valve EX for discharge is stopped and the electromagnetic valve of the target wheel is closed to stop the pressure control. In this way, when there is a wheel whose pressure has dropped, the vehicle height is checked and the PV product is checked to make sure that the wheel is abnormal, and then the abnormal wheel pressure is adjusted.

The subroutine of the controlled object selection / output routine will be described below.

FIG. 6 shows a vehicle height abnormality determination routine. First, in step 80, the vehicle height ranking is determined. here,
Sort according to the vehicle height of each wheel. Next, in step 81, the vehicle height value of the wheel having the lowest vehicle height is set to the variable Hmin.
To. Next, in step 82, the vehicle height value of the wheel having the highest vehicle height is substituted into the variable Hmax. Step 83
Then, it is judged whether or not this minimum vehicle height value Hmin is lower than the vehicle height which is lower than the target vehicle height value by ΔH0, and if it is lower, the routine branches to step 88. Further, in step 84, it is determined whether or not the maximum vehicle height value Hmax is higher than the vehicle height ΔH0 higher than the target vehicle height value, and if it is higher, the process branches to step 86. Both the minimum vehicle height and the maximum vehicle height, ΔH above and below the target vehicle height
If it is within 0, it is determined to be normal and the flag Fabn indicating an abnormality is set to 0 to return to the original routine. When the minimum vehicle height value is lower than the target vehicle height value-ΔH0, the wheel having the minimum vehicle height value is designated as the target wheel in step 88, Up is substituted for the flag Fdir indicating the pressure control direction, and an abnormality is detected in step 90. The flag Fabn shown is set to 1 to return to the original routine. If the highest vehicle height value is higher than the target vehicle height value + ΔH0, the wheel having the highest vehicle height value is designated as the target wheel in step 86, and the flag Fdir indicating the pressure control direction is set to Do.
Substituting wn, flag Fa indicating abnormality in step 90
bn is set to 1 to return to the original routine. In this way, it is determined that the vehicle height is abnormal if the vehicle height value of either wheel is more than the predetermined value away from the target value. Here, the judgment on the lower side is made earlier than the judgment on the higher side. First, priority is given to whether the vehicle height is too low. When there is a wheel that is too high and a wheel that is too low with respect to the predetermined width of the target value, the wheel that is too low is designated as the target wheel. As described above, in this embodiment, the wheels to be controlled are prioritized so that the control is performed from the lower side. This is because this control aims at recovery when the pressure drops due to pressure leakage. Further, if the vehicle height is too low, there is a danger that the vehicle body will hit a protrusion on the road surface, etc. Therefore, the wheel on the lower vehicle side is preferentially controlled.

The control opening processing routine is shown in FIG. At step 100, it is determined whether the pressure control direction is the rising direction or the falling direction by referring to the flag Fdir. If it is in the ascending direction (Fdir = Up), in step 101, the pump RP is driven to increase the pressure.

Since only the cylinder of the control target wheel is connected to the pump RP in the above process, the pressure of the cylinder of the control target wheel starts to rise. Next, at step 102, the provisional control target value HT is determined. The provisional control target value HT in the ascending direction is set to a value which is higher than the vehicle height value Hxx at the time of executing the control start processing routine, that is, by the constant ΔH1. Then, in step 105, the flag Fcont indicating that control is being performed is set to 1, and the process returns to the original routine. When the pressure control direction is the descending direction (Fdir = D
Now), in step 103, the discharge solenoid valve EX is driven to decrease the pressure. Since only the cylinder of the control target wheel is connected to the discharge solenoid valve EX in the above process, the pressure of the cylinder of the control target wheel starts to drop. Next, at step 104, the provisional control target value HT is determined. The provisional control target value HT in the case of the descending direction is set to a value which is lower than the vehicle height value Hxx at the time of executing the control start processing routine, that is, the control by a constant ΔH1. Then, in step 105, the flag Fcont indicating that control is being performed is set to 1, and the process returns to the original routine. As described above, in this routine, the pump RP or the discharge electromagnetic valve EX is driven to start the control, and the provisional control target is set. The constant ΔH1 used for the provisional control target is set to a value smaller than the vertical width ΔH0 with respect to the target vehicle height value used for the vehicle height abnormality determination. This is because the pressure control is subdivided and the pressure is adjusted evenly when there are a plurality of abnormal rings.

FIG. 8 shows a control end judgment / processing routine. In step 110, it is determined whether the pressure control direction is the rising direction or the falling direction by referring to the flag Fdir. If it is in the upward direction (Fdir = Up), it is determined in step 111 whether the vehicle height value Hxx has risen above the provisional target vehicle height value HT. If the vehicle height value Hxx does not exceed the provisional target vehicle height value HT, the control is continued. If the vehicle height value Hxx exceeds the provisional target vehicle height value HT, the pump R is set in step 112.
P is stopped, the solenoid valve of the target wheel is closed in step 115, and the flag Fcon indicating that control is in progress in step 116
The control is terminated by setting t to 0, and the routine returns. When the pressure control direction is the descending direction (Fdir = D
own), it is determined in step 113 whether the vehicle height value Hxx has fallen below the provisional target vehicle height value HT. Vehicle height H
If xx is not lower than the provisional target vehicle height value HT, the control is continued. If the vehicle height value Hxx is lower than the provisional target vehicle height value HT, the discharge solenoid valve EX is stopped in step 114, the solenoid valve of the target wheel is closed in step 115, the control is ended by setting the flag Fcont indicating that control is in progress to 0. Then, it returns to the original routine. As described above, in this routine, if the vehicle height value does not reach the provisional target vehicle height value, the control is continued, and when it reaches, the pump RP or the discharge solenoid valve EX is stopped and the solenoid valve of the target wheel is closed. Control ends.

As described above, in this embodiment, the vehicle height value is within the predetermined range by controlling the pressure in the cylinder when the vehicle height value and the PV product are both abnormal, or
When the product of the pressure and volume in the cylinder is within the predetermined range, control is not performed. This state corresponds to the case where the vehicle body or wheels move due to an external factor. For example, when a wheel rides over a pebbles, the cylinder receives a force from the wheel side and the vehicle height decreases, but the pressure inside the cylinder increases and the PV product remains almost constant. In this case, pressure adjustment is not performed in this embodiment. However, when the pressure in the cylinder leaks and the pressure decreases, the vehicle height decreases and the PV product decreases, so that the pump and the solenoid valve operate to increase the pressure. Therefore, since the pump operates only when the pressure surely leaks, there is an effect that the energy used in this system is small. In addition, the frequency of operation of the solenoid valve and pump is reduced, which improves the service life of the components.

In particular, when the vehicle is parked on a slope, separate control such as prohibiting the control is conventionally required, but in this embodiment, the PV product does not change during parking on the slope. Therefore, control of pressure application and discharge is not performed. In particular, control prohibition at the time of slope parking can be executed without adding a prohibition routine for judging the slope and prohibiting the pressure control.

Similarly, even when the vehicle is turning on a steady circle, conventionally it was necessary to add special control such as prohibiting the control, but in the present embodiment, during steady circle turning, Since the PV product does not change, the pressure application and discharge control are not performed. In particular, the control prohibition during the steady circular turn can be executed without adding a prohibition routine for judging the steady circular turn and prohibiting the pressure control.

Further, even when the vehicle is running on a rough road,
Conventionally, special control was required to prevent abnormal vehicle height reduction due to control hunting and excessive vehicle height control, but in this embodiment, the PV product changes during running on rough roads. Therefore, pressure application and discharge control are not performed. In particular, stable traveling can be maintained even during traveling on a rough road without adding a special control routine such as slope determination.

Further, in this embodiment, when the target PV product is obtained, the ground load on each wheel is calculated, the center of gravity position is calculated from the ground load, and the load is redistributed to each wheel according to the center of gravity position. When the initial pressure value is set from the distributed load and the target PV product is obtained from the initial pressure value, when the target is controlled, the load warp does not occur in the vehicle.

By eliminating the load warp during traveling, the characteristics of understeer and oversteer at the time of turning match, the left and right are balanced, and the steering performance is improved. Also, the vehicle height can be made horizontal even if there is a single load.

Further, in this embodiment, the control is performed for each wheel. It is not controlling more than two wheels at the same time. As a result, the number of pressure sensors used can be reduced. Further, the volume of the pump only needs to correspond to one cylinder, and a small pump can be used. Along with this, the motor can be small, and the power consumption is small.

[0043]

According to the present invention, the number of times the pressure source is operated can be reduced, the life of the pressure source is extended, and the reliability is improved.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of an embodiment of the present invention.

FIG. 2 is a flowchart of a main routine of the electronic control unit according to the embodiment of the present invention.

FIG. 3 is a flowchart of the input processing routine of FIG.

FIG. 4 is a flowchart of a target PV product calculation routine of FIG.

5 is a flowchart of a control target selection / output routine of FIG.

6 is a flowchart of a vehicle height abnormality determination routine of FIG.

7 is a flowchart of a control start processing routine of FIG.

FIG. 8 is a flowchart of a control end determination / processing routine of FIG.

FIG. 9 is an explanatory diagram of a vehicle load of the present invention.

[Explanation of symbols]

10 front left wheel, 11 front right wheel, 12 rear left wheel, 1
3 Rear right wheel 14-17 Cylinder 18-21 Vehicle height sensor 22 Electronic control unit 30 Pressure sensor 31 Drain 32-36 Piping EX Discharge solenoid valve Fcont Controlling flag Fdir Flag indicating pressure control direction H Vehicle height HT Temporary target vehicle High price KF, KR Front and rear wheel stabilizer constants LH Distance between wheel bases, Distance between LT treads L1, L2, L3, L4 Center of gravity position M Motor RP Pump P Pressure PV PV product PV0 Target PV product H0 dead space, HF0 Front wheel side , HR0
Rear wheel side S Pressure receiving area, SF Front wheel side, SR Rear wheel side SFL Front left wheel solenoid valve, SFR Front right wheel solenoid valve SRL Rear left wheel solenoid valve, SRR Rear right wheel solenoid valve WFL, WFR, WRL, WRR Ground load of each wheel W Total weight of vehicle W1 Sum of loads between front wheels, W2 Sum of loads between rear wheels Pxx0 Initial pressure value Vxx Volume xx = FL, FR, RL, RR

Claims (2)

[Claims] 1. A cylinder which is arranged between a wheel and a vehicle body and whose distance between the wheel and the vehicle body can be adjusted by the pressure supplied to the inside thereof; a control valve for supplying / discharging pressure to / from the cylinder; Pressure sensor for detecting; volume measuring means for measuring volume in the cylinder; vehicle height abnormality determining means for determining vehicle height abnormality when vehicle height exceeds a predetermined range; pressure detected by the pressure sensor and volume measuring means Integrating means for calculating the PV product which is the product of pressure and volume; PV product abnormality determining means for determining that the PV product is abnormal when the PV product exceeds a predetermined range; and the vehicle height is abnormal. And the control valve opening / closing means for opening / closing the control valve to adjust the pressure in the cylinder when the PV product is abnormal. 2. The suspension device according to claim 1, wherein when there are two or more wheels determined to be abnormal, the wheel on the lower vehicle height side is preferentially controlled.