JPH0331014A - Fluid pressure type active suspension - Google Patents

Abstract

PURPOSE:To enhance the characteristic of control of the posture of a vehicle body by providing a variable orifice in a feedback passage communicated with a pressure control means for controlling the feed and discharge of working fluid to and from a fluid pressure actuator, and by controlling the opening degree of the variable orifice so that it is becomes higher as the pressure in a high pressure passage is lower. CONSTITUTION:Pressure control valves 32, 34 are disposed respectively in high pressure fluid passages 18FR, 18FL which are communicated with a high pressure passage 18 connected to the discharge side of a pump 6 and which are connected to fluid chambers 2FR, 2FL in hydraulic actuators 1FR, 1FL provided respectively at wheel. Further, a control valve 40 for introducing a pressure in a fluid passage 50 between a fixed orifice 42 and a variable orifice 54 and a pressure in a connecting passage 56, as pilot pressures, respectively through pilot passages 50a, 56a is disposed in the pressure control valve 32 (also 34). In this case, a variable orifice 250 is disposed in the pilot in the passage 56a, and the degree of the orifice is controlled so that it becomes hither as the pressure in the high pressure passage 18FR is lower.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an active suspension for a vehicle such as an automobile, and more particularly to a hydraulic active suspension.

BACKGROUND ART As one type of active suspension for vehicles such as automobiles, as described in Japanese Patent Application Laid-Open No. 63-145115, a fluid pressure actuator disposed between each wheel and a vehicle body and a working fluid are used. A supply passage and a working fluid discharge passage; a pressure control valve that is provided in the middle of the supply passage and the discharge passage and controls the supply and discharge of the working fluid to the corresponding actuator and controls the pressure within the actuator; and a pressure control valve that controls the pressure control valve. control means, and controls the ride comfort of the vehicle and the posture of the vehicle body by controlling the pressure in the actuator via the pressure control valve based on the vehicle height of the portion corresponding to each wheel and the acceleration of the vehicle body. A hydraulic active suspension configured as described above has been known in the past.

Problems to be Solved by the Invention In the above-mentioned hydraulic active suspension, working fluid is supplied from the supply passage to the actuator by a pressure control well, and the working fluid is discharged from the actuator to the discharge passage, depending on the driving condition of the vehicle. The pressure inside the actuator is controlled by The amount increases, the consumption of working fluid increases, and the pressure in the supply passage upstream of the pressure control valve tends to drop. If the pressure in the supply passage upstream of the pressure control valve decreases, the pressure in the actuator cannot be adequately controlled.
Therefore, it becomes impossible to control the attitude of the vehicle body well.

When pumps and accumulators are made larger to solve this problem, energy consumption increases and fuel efficiency worsens. Furthermore, if the responsiveness of the pressure control valve is set low, the consumption of working fluid can be reduced, but the pressure inside the actuator cannot be controlled with good responsiveness, so There is a problem that sometimes the attitude control performance of the vehicle body becomes insufficient.

In view of the above-mentioned problems with conventional hydraulic active suspensions, the present invention has been developed to effectively control vehicle ride comfort and vehicle body posture without increasing energy consumption or deteriorating fuel efficiency. The purpose of the present invention is to provide an improved hydraulic active suspension.

Means for Solving the Problems According to the present invention, the above objects include a fluid pressure actuator disposed between each wheel and a vehicle body, a working fluid supply passage, a working fluid discharge passage, and the supply passage. and a pressure control means provided in the middle of the discharge passage for controlling supply and discharge of working fluid to and from the corresponding actuator and controlling the pressure within the actuator, and transmitting the pressure within the actuator to the corresponding pressure control means. a feedback passage provided in the middle of the feedback passage; means for detecting the pressure in the supply passage upstream of the pressure control means; This is achieved by means of a hydraulic active suspension having control means for increasing the degree of restriction.

Effect of the Invention According to the above-described configuration, the pressure in the supply passage upstream of the pressure control means is detected by the pressure detection means, and the lower the detected pressure is, the more the degree of throttling of the variable throttle is increased by the control means. This reduces the degree of pressure within the actuator that is transmitted to the pressure control means via the feedback passage, thereby reducing the responsiveness of the pressure control means, thereby causing the pressure control valve to supply and discharge the actuator to and from the actuator. The amount of fluid is reduced, the pressure in the supply passage upstream of the pressure control means is prevented from further decreasing, and the pressure in the supply passage is reduced so that the attitude of the vehicle body can be effectively controlled. recovery is promoted. Conversely, the higher the pressure in the supply passage, the more the control means reduces the degree of restriction of the variable restrictor, which increases the degree of transmission of the pressure in the actuator to the pressure control means via the feedback passage. The responsiveness of the control means is increased, thereby increasing the amount of working fluid supplied to and discharged from the actuator by the pressure control valve, thereby effectively controlling the ride comfort of the vehicle and the attitude of the vehicle body.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention will be explained in detail below by way of example embodiments with reference to the accompanying figures.

Embodiment FIG. 1 is a schematic diagram showing a fluid circuit of one embodiment of a hydraulic active suspension according to the present invention.

The fluid circuit of the illustrated active suspension includes actuators I PR provided corresponding to the right front wheel, left front wheel, right rear wheel, and left rear wheel of the vehicle, which are not illustrated.
, I FL, I RR, and IRL, and these actuators have working fluid chambers 2PR and 2PL, respectively.
, 2RR, 2RL.

Further, in the figure, 4 indicates a reserve tank that stores hydraulic oil as a working fluid, and the reserve tank 4 is connected to a suction flow path 10 in which a filter 8 for removing foreign matter is provided in the middle.
It is connected in communication with the suction side of the pump 6. A drain passage 12 is connected to the pump 6 for collecting working fluid leaked inside the pump 6 into the reserve tank 4. The pump 6 is rotationally driven by an engine 14, and the rotation speed of the engine 14 is detected by a rotation speed sensor 16.

A high pressure flow path 18 is connected to the discharge side of the pump 6.

A check valve 20 is provided in the middle of the high-pressure flow path 18 to allow only the flow of working fluid from the pump toward each actuator, and between the pump 6 and the check valve 20, the working fluid discharged from the pump is provided. An attenuator 22 is provided to absorb pressure pulsations and reduce pressure changes. The high pressure flow path 18 includes a front wheel high pressure flow path 18F and a rear wheel high pressure flow path 1.
8R is connected to one end, and accumulators 24 and 26 are connected to these high pressure channels, respectively.

Each of these accumulators has a high pressure gas sealed therein so as to absorb pressure pulsations of the working fluid and perform a pressure accumulating function.

Further, one end of the high pressure flow path 18FR for the right front wheel, the high pressure flow path 18FL for the left front wheel, the high pressure flow path 18RR for the right rear wheel, and the high pressure flow path 18RL for the left rear wheel are connected to the high pressure flow paths 18F and 18R, respectively. . High pressure flow path 18Pl? .

Filters 28PR, 28FL, 28RR, and 28RL are provided in the middle of 18FL, 18RR, and 18RL, respectively, and the other ends of these high-pressure channels are pilot-operated 3 pressure control valves 32, 34, 36, and 38, respectively.
Connected to P boat of boat switching control valve 40.42.44.46.

The pressure control valve 32 is connected to the switching control valve 40 and the high pressure flow path 18P.
It consists of a flow path 50 that communicates and connects R and the low-pressure flow path 4BPR for the right front wheel, and a fixed throttle 52 and a variable throttle 54 provided in the middle of the flow path.

A low pressure passage 48PR is connected to the R boat of the switching control valve 40, and a connection passage 56 is connected to the A boat. The switching control valve 40 has a fixed throttle 52 and a variable throttle 54.
The pressure Pp in the flow path 50 between the pilot path 50a and
It is a spool valve that takes in the pressure Pa in the connection passage 56 as a pilot pressure through the pilot passage 56a, and when the pressure Pp is higher than the pressure Pa, it is a switching valve that connects the boat P and the boat A for communication. When the pressures Pp and Pa are equal to each other, the switching position 40b switches to the switching position 40a, and when the pressures Pp and Pa are equal to each other, the switching position 40b switches to the switching position 40b, which disconnects communication between all boats, and when the pressure Pp is lower than the pressure Pa, the switching position 4 connects the boat R and the boat A.
It is designed to switch to 0c. Further, the variable throttle 54 changes the effective passage cross-sectional area of the throttle by controlling the current applied to the solenoid 58, thereby changing the pressure Pp in cooperation with the fixed throttle 52.

Similarly, pressure control valves 34 to 38 are each pressure control valve 32
A pilot-operated three-boat switching control valve 42, 44, 46 corresponding to the switching control valve 40, a flow path 60, 62, 64 corresponding to the flow path 50, and a fixed throttle 66, 68 corresponding to the fixed throttle 52. .70 and variable apertures 72, 74, and 76 corresponding to the variable aperture 54, and the variable apertures 72 to 76 each have a solenoid 78, 80, and 82.

In addition, the switching control valves 42, 44, and 46 are switching control valves 40
The R boat has a low pressure flow path 48FL for the left rear wheel and a low pressure flow path 481 for the right rear wheel.
? R, low pressure flow path 481 for left rear wheel? One end of L is connected, and the A port has connection channels 84, 86, 8, respectively.
One end of 8 is connected. In addition, the switching control valves 42 to 4
6 is a pilot passage 60a, 6 which controls the pressure Pp in the flow paths 60 to 64 between the corresponding fixed throttle and variable throttle, respectively.
2a.

64a as a pilot pressure, and the pressure Pa in the corresponding connection channels 84 to 88 is taken in as pilot pressure through the pilot passage 84a.
It is a spool valve that takes in pilot pressure through s 86a and 88a, and when the pressure Pp is higher than the pressure Pa, it switches to the switching position 42a% 44a s 46a, which connects the boat P and the boat A, and the pressure Pp is taken in as pilot pressure.
Switching positions 142b, 44b, 46bl that cut off communication between all boats when and Pa are equal to each other:
l: Switching position 42c where boat R and port A are connected in communication when pressure Pp is lower than pressure Pa
, 44c s 46c.

Pilot passages 56a, 84a, 86a, 88a
constitutes a part of a feedback passage that transmits the pressure P1 in the working fluid chamber of the corresponding actuator to the corresponding pressure control valve, and variable throttles 250 to 256 are provided in the middle of each pilot passage. Each of these variable apertures has its solenoid 250a% 25
2a s 254a.

By increasing or decreasing the current supplied to the switching control valve 4, the effective passage cross-sectional area of the throttle is increased or decreased.
The responsiveness of the corresponding pressure control valve is controlled by increasing or decreasing the degree of transmission of the pilot pressure Pa transmitted from 0 to 46.

As schematically shown in FIG. 1, each actuator IPR, IPL, IRR, IRL has a cylinder 106FR, 106PL, 106RR, defining a working fluid chamber 2PR, 2PL, 2RR, 2RL, respectively.
106RL, and pistons 108PR, 108FL, 108RR, 108 that fit into the corresponding cylinders, respectively.
RL, each connected to the vehicle body (not shown) through a cylinder, and connected to a suspension arm (not shown) at the tip of the rod portion of the piston. Although not shown in the internal explanation, a suspension spring is elastically loaded between an upper seat fixed to the rod portion of the piston and a lower seat fixed to the cylinder.

Also, the cylinders 106FR and 106F of each actuator
L, 106RR, and 106RL have a drain flow path 110.
112.114.116 are connected at one end. The other end of the drain passage 110, 112, 114, 116 is connected to a drain passage 118, which is connected to the reserve tank 4 via a filter 120, thereby preventing leakage from the working fluid chamber. The used working fluid is returned to the reserve tank.

Accumulators 132.134.136.138 are connected to the working fluid chambers 2PR, 2PL, 2RR, and 2RL via throttles 124.126.128.130, respectively. Also pistons 108PR, 108FL, 10
8RR and 108RL have flow paths 140PR and 14, respectively.
0FL, 140RR, and 140RL are provided.

These channels correspond to channels 56.84 to 88, respectively.
and working fluid chambers 2PR, 2PL, and 2RR.

2RL, and a filter 142 is installed in the middle of each.
It has PR, 142FL, 142RR, and 142RL. Also, actuators I FR, I PL, I
At positions close to RR and IRL, vehicle height sensors 144FI? detect vehicle heights XPRSXFLSXRR and XRL corresponding to each wheel, respectively. , 144FL, 144
RR and 144RL are provided.

Pilot-operated shutoff valves 150.152.154.156 are provided in the middle of the connecting channels 56.84 to 88, respectively, and these shutoff valves are connected to corresponding pressure control valves 40.42.44.46, respectively. High pressure flow path 1 on the more upstream side
When the differential pressure between the pressure in 8FR, 18FL, 18RR, 18RL and the pressure in drain flow path 1□10.112.114.116 is below a predetermined value, the valve is maintained in a closed state. In addition, the portions of the connecting channels 56.84 to 88 between the corresponding pressure control valves and the cutoff valves are respectively connected to the flow channels 158.160.162.164 and the flow channels 50.60.62.64 of the corresponding pressure control valves. It is connected to the downstream part of the variable throttle. Relief valves 166, 168, 170.
172 are provided, and these relief valves each take in the pressure of the upstream portion of the corresponding flow path 158, 160, 162, 164, that is, the side of the corresponding connection flow path, as a pilot pressure, and the pilot pressure is When a predetermined value is exceeded, the valve is opened to guide a portion of the working fluid in the corresponding connection flow path to the flow paths 50, 60 to 64.

The cutoff valves 150 to 156 are connected to the high pressure flow path 18PR, respectively.
18PL, 18RR, 181? The valve may be configured to maintain the closed state when the pressure difference between the pressure inside L and the atmospheric pressure is less than or equal to a predetermined value.

The other ends of the low pressure passages 48PR and 48PL are connected to one end of the low pressure passage 48F for the front wheels, and the other ends of the low pressure passages 48RR and RL are connected to the - end of the low pressure passage 48H for the rear wheels. There is. The other ends of the low pressure channels 48F and 48R are connected to one end of the low pressure channel 48 in communication. The low pressure flow path 48 has an oil cooler 174 in the middle and a filter 176 at the other end.
It is connected to the reserve tank 4 via. A portion of the high-pressure flow path 18 between the check valve 20 and the attenuator 22 is connected to the low-pressure flow path 48 through a flow path 178 .

A relief valve 180 is provided in the middle of the flow path 178 and is set to a predetermined pressure in advance.

In the illustrated embodiment, the high pressure channel 18R and the low pressure channel 4
8R is a flow path 188 that has a filter 182, a throttle 184, and a normally open electromagnetic on-off valve 186 that can adjust the flow rate.
are connected to each other by. The electromagnetic on-off valve 186 is configured to open by energizing a solenoid 190 and changing its excitation current, and to adjust the flow rate of the working fluid passing through the valve. Also, high pressure flow path 18R
and the low-pressure flow path 48R are connected to each other by a flow path 194 having a pilot-operated on-off valve 192 in the middle. The on-off valve 192 takes in the pressure on both sides of the throttle 184 as a pilot pressure, and maintains the closed position 192a when there is no differential pressure on both sides of the throttle 184, and when the pressure on the high pressure flow path 18F side with respect to the throttle 184 is high. Valve open position 1
92b. Thus aperture 18
4. The electromagnetic on-off valve 186 and the on-off valve 192 cooperate with each other to open the high pressure flow path 18R and the low pressure flow path 48R1, so the high pressure flow path 1
8 and the low-pressure flow path 48 to form a bypass valve 196 that controls the flow rate of the working fluid flowing from the high-pressure flow path to the low-pressure flow path.

Furthermore, in the illustrated embodiment, pressure sensors 197F are provided in the front wheel high pressure flow path 18R and the rear wheel high pressure flow path 18H, respectively.
and 197R are provided, and these pressure sensors measure the pressure Ps of the working fluid in the corresponding high pressure flow path.
r and Psr are detected. Further, a pressure sensor 198 is provided in the low pressure flow path 48R, and the pressure Pd of the working fluid in the low pressure flow path is detected by the pressure sensor. Connection channel 56.84.86
．． 88 has pressure sensors 199FR and 199PL, respectively.
, 199RR, and 199RL are provided, and the working fluid chamber 2 PR is controlled by these pressure sensors.

The pressure inside 2PL, 2RR, and 2RL is detected. Furthermore, a temperature sensor 195 is installed in the reserve tank 4 to detect the temperature T of the working fluid stored in the tank.
is provided.

The electromagnetic on-off valve 186 and the pressure control valves 32-38 are controlled by an electric control device 200 shown in FIG. Electrical control device 200 includes a microcomputer 202 .

The microcomputer 202 may have a general configuration as shown in FIG. 2, and includes a central processing unit (CPU) 204 and a read-only memory (ROM) 2.
06, random access memory (RAM) 208,
It has an input port device 210 and an output port device 212, which are connected to each other by a bidirectional common bus 214.

The input port device 210 includes a signal indicating the rotation speed N of the engine 14 from the rotation speed sensor 16, a signal indicating the temperature T of the working fluid from the temperature sensor 195, and pressure sensors 197F and 19.
7R and 198, respectively, the pressure Psl' in the high pressure flow path
5Psr and a signal indicating the pressure Pd in the low pressure flow path, pressure sensors 199FL, 199FR, 199RL, 199R
I? The working fluid chambers 2PL, 2PR, 2RL, respectively.
, a signal indicating the pressure PI (1-1, 2, 3, 4) in 2RR, a signal indicating whether the ignition switch is in the on state from the ignition switch (IGSW) 216, vehicle height sensors 144PL, 144FR, 144RL
, 1441? From R, left front wheel, right front wheel, left rear wheel,
Vehicle height XI of the part corresponding to the right rear wheel (1-1, 2, 3, 4
) are respectively input.

Input port device 210 also includes a signal indicating vehicle speed V from vehicle speed sensor 234, a signal indicating longitudinal acceleration Ga from longitudinal G (acceleration) sensor 236, and a signal indicating longitudinal acceleration Ga from longitudinal G (acceleration) sensor 238.
A signal indicating the lateral acceleration G1 from the steering angle sensor 240, a signal indicating the steering angle θ from the steering angle sensor 240, and a signal indicating whether the vehicle height control mode set by the vehicle height setting switch 248 is high mode or normal mode. It is now entered.

The input boat device 210 processes the signals input thereto as appropriate, and uses the CPU and RAM 20g according to instructions from the CPU 204 based on the program stored in the ROM 206.
It is designed to output the processed signal to. ROM
206 is the control flow shown in FIGS. 3, 6A to 6C, and 13, and the control flows shown in FIGS. 4, 5, and 7 to 12.
14 to 20 are stored, and the CPU processes signals based on each control flow. In accordance with instructions from the CPU 204, the output boat device 212 outputs a control signal to the electromagnetic on-off valve 186 via a drive circuit 220, and outputs a control signal to the pressure control valves 32 to 38 via drive circuits 222 to 228, specifically variable throttles 54.7, respectively.
A control signal is output to the solenoid 58.78.80.82 of 2.74.76, and the display 232 is output via the drive circuit 230.
It outputs a control signal to the variable apertures 250 to 256 via the drive circuits 258 to 264, and more specifically to the solenoid 2 thereof.
Control signals are output to 50a to 256a.

The operation of the illustrated embodiment will now be described with reference to the flowchart shown in FIG.

Note that the control flow shown in FIG. 3 is started when the ignition switch 216 is closed. Further, in the flowchart shown in FIG. 3, the flag Fc indicates that the pressure Ps of the working fluid in the high pressure flow path is
This relates to whether or not the pressure Ps has ever exceeded the threshold pressure Pc that causes the valve to fully open.
The flag Fs indicates that the standby pressure Pb1 (l
-1, 2, 3, 4) standby pressure current 1b
This relates to whether l(1-1, 2, 3, 4) is set, and 1 indicates that the standby pressure current is set.

First, in step 10, a main relay (not shown in the figure) is turned on, and then in step 2
Go to 0.

In step 20, the contents stored in the RAM 208 are cleared and all flags are reset to 0, and the process then proceeds to step 30.

In step 30, a signal indicating the rotation speed N of the engine 14 detected by the rotation speed sensor 16, a signal indicating the rotation speed N of the engine 14 detected by the rotation speed sensor 16,
A signal indicating the temperature T of the working fluid detected by the pressure sensor 195, a signal indicating the pressure Psf' and Psr in the high pressure flow path detected by the pressure sensors 197F and 197R, and a pressure in the low pressure flow path detected by the pressure sensor 198. Signal indicating Pd, pressure sensors 199FL, 199FR, 199RL,
Working fluid chambers 2PL and 2P detected by 199RR
R, 2RL, a signal indicating the pressure pt in 2RR, a signal indicating whether the ignition switch 216 is in the on state, vehicle height sensors 144FL, 144FR, 144RL
, a signal indicating the vehicle height X1 detected by the vehicle speed sensor 234, a signal indicating the vehicle speed ■ detected by the vehicle speed sensor 234, a signal indicating the longitudinal acceleration Ga detected by the longitudinal G sensor 236, a signal indicating the longitudinal acceleration Ga detected by the lateral G sensor 238. Acceleration G
1, a signal indicating the steering angle θ detected by the steering angle sensor 240, and a signal indicating whether the mode set by the vehicle height setting switch 248 is high mode or normal mode. Then step 4o
Proceed to.

In step 40, it is determined whether or not the ignition switch is in the off state, and when it is determined that the ignition switch is in the off state, the process proceeds to step 200, where the ignition switch is in the on state. When it is determined that this is the case, the process advances to step 50.

In step 50, it is determined whether or not the engine rotation speed N detected by the rotation speed sensor 16 and read in step 30 exceeds a predetermined value. If it is determined that the engine is not being operated, the process proceeds to step 85, and if it is determined that the engine is being operated, the process proceeds to step 60.

Note that whether or not the engine is being operated may be determined by determining whether or not the generated voltage of a generator (not shown in the drawings) driven by the engine is equal to or higher than a predetermined value.

In step 60, from the time when engine operation is started, in step 150, which will be described later, the pressure control valves 32 to 3 are
A timer is started for a time Ts until the standby pressure Pbl of 8 is set, after which the process proceeds to step 70. In this case, if the timer Ts has already been activated, the timer continues counting.

In step 70, the current 1b applied to the solenoid 190 of the electromagnetic on-off valve 186 of the bypass valve 196 is RO
Based on the map corresponding to the graph shown in FIG. 4 stored in M206, calculation is performed according to Ib-1b+ΔI bs , and the process then proceeds to step 80.

In step 80, the current 1b calculated in step 70 is applied to the solenoid 190 of the electromagnetic on-off valve 186, thereby driving the bypass valve 196 in the closing direction, and then the process proceeds to step 85.

In step 85, the average value Ps of the pressure in the high pressure channel is calculated according to the following equation, and then the process proceeds to step 90.

Ps = (Psr+Psr) /2 In step 90, the average value Ps of the pressure in the high pressure channel
is equal to or greater than the threshold value Pc, and Ps≧
When it is determined that it is not a PC, step 12
0, and when it is determined that Ps≧Pc, the process advances to step 100.

In step 100, flag Fc is set to 1, and then the process proceeds to step 110.

In step 110, in order to control the ride comfort of the vehicle and the attitude of the vehicle body, the process proceeds to step 30, as will be explained in detail later with reference to FIGS. 6A to 6C and FIGS. 7 to 12. By performing active calculations based on various signals read in, the variable throttle 5 of each pressure control valve
4. The current 1ui to be energized to the solenoids 58, 78, 80, 82 of 72 to 76 is calculated, and then step 1
Proceed to step 15.

At step 115, as will be explained in detail later with reference to FIGS. By controlling 250 to 256, the responsiveness of the pressure control valve is controlled, and the process then proceeds to step 170.

In step 120, it is determined whether the flag Fc is 1 or not, and it is determined that the flag Fc is Fc -1, that is, the pressure Ps of the working fluid in the high pressure flow path is equal to or higher than the threshold suppressing pressure Pc. If it is determined that the value has become lower than this after the initial pressure is determined, the process proceeds to step 110, and it is determined that the pressure is not Fc-1, that is, it is determined that the pressure PS has never exceeded the threshold suppression pressure Pc. When this has been performed, the process advances to step 130.

In step 130, it is determined whether the flag Fs is 1, and when it is determined that it is Fs -1, the process proceeds to step 170, and it is determined that it is not Fs -1. If so, the process proceeds to step 140.

In step 140, it is determined whether or not the time Ts has elapsed, and when it is determined that the time Ts has not elapsed, the process proceeds to step 170, where it is determined that the time Ts has elapsed. When this has been performed, the process advances to step 150.

In step 150, the operation of the Ts timer is stopped, and the pressure P1 read in step 30 is stored in the RAM 208 as the standby pressure Pb1, and the pressure shown in FIG. Based on the map corresponding to the graph shown in FIG. Working fluid chamber 2 PL, 2 PR,
' 2 RL, solenoid 78.58.
82. The current Ib1 (1-1, 2, 3,
4) is calculated, and then the process proceeds to step 160.

In step 160, the flag Fs is set to 1, and then the process proceeds to step 170.

In step 170, it is determined whether the current Ib calculated in step 70 is greater than or equal to the reference value Ibo, and when it is determined that Ib≧Ibo is not satisfied, the process proceeds to step 30. Returning, if it is determined that Ib≧Ibo, the process proceeds to step 180.

In step 180, the average value Ps of the pressure in the high-pressure flow path calculated in step 85 is determined to be equal to the reference value Pso (<P
c) It is determined whether or not the above is true, and when it is determined that Ps≧Pso is not satisfied, the process returns to step 30, and when it is determined that Ps≧Pso, the process proceeds to step 190.

In step 190, the current Ibi calculated in step 150 or the current 1ui calculated in step 110 is applied to the variable throttle solenoid 58 of each pressure control valve.
78 to 82, each pressure control valve is driven and its control pressure is controlled, and then step 30
Steps 30 to 190 described above are repeated.

In step 200, the bypass valve 1 is turned off by stopping the power supply to the trail 190 of the electromagnetic on-off valve 186.
96 is opened, and the process then proceeds to step 210.

In step 210, the main relay is turned off, thereby ending the control flow shown in FIG. 3 and stopping power supply to the electric control device 200 shown in FIG. Ru.

Claims (1)

[Claims] A fluid pressure actuator disposed between each wheel and the vehicle body, a working fluid supply passage and a working fluid discharge passage, and supply and discharge of working fluid to the corresponding actuator provided in the middle of the supply passage and the discharge passage. a pressure control means for controlling the pressure within the actuator, a feedback passage for transmitting the pressure within the actuator to the corresponding pressure control means, a variable throttle provided in the middle of the feedback passage; A hydraulic active suspension comprising means for detecting the pressure in the supply passage upstream of the pressure control means, and control means for increasing the degree of restriction of the variable restriction as the pressure in the supply passage becomes lower.