JPH02179533A - Fluid pressure type suspension - Google Patents

Abstract

PURPOSE:To improve the drive feeling during the traveling on a rough road by reducing the control quantity on the basis of the ground clearance during the turn or acceleration/deceleration, in the constitution in which a pressure adjusting means for adjusting the fluid pressure supplied into a fluid pressure actuator between a wheel and a car body is controlled to the control quantity on the basis of the ground clearance. CONSTITUTION:The pressure of the working fluid supplied into the working fluid chamber 2 (2FL-2RR) of an actuator 1 (1FL-1RR) interposed between each wheel and a car body in correspondence with the right/left and front/rear wheels is adjusted by the pressure control valves 32-38 controlled by a CPU, and a ground clearance detecting means for detecting the ground clearance of the part corresponding to each wheel and a traveling state judging means for judging the turn and the acceleration/deceleration speed of a vehicle are installed. In a CPU, a pressure control instruction is generated on the basis of the first control quantity on the basis of the detected ground clearance and the second control quantity on the basis of the static supporting load of the actuator 1. Further, in this case, the first control quantity is reduced when the vehicle is turned or accelerated/decelerated.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to suspensions for vehicles such as automobiles, and more particularly to hydraulic suspensions.

BACKGROUND ART As one type of hydraulic suspension for vehicles such as automobiles, there is a hydraulic actuator disposed between each wheel and the vehicle body, such as the suspension described in Japanese Patent Application Laid-Open No. 63-145115. , a pressure adjustment means for adjusting the fluid pressure in the actuator, a vehicle height detection means for detecting the vehicle height of a portion corresponding to each wheel, and a control means for controlling the pressure adjustment means, and the vehicle height detection means When a substantial change in vehicle height (change in vehicle body posture) is not detected, the fluid pressure in each actuator is controlled to an offset pressure corresponding to its static support load, and the vehicle height detection means detects a substantial change in vehicle height. 2. Description of the Related Art Hydraulic suspensions are conventionally known which are configured to suppress changes in the attitude of a vehicle body by outputting a command value corresponding to the change in vehicle height to a pressure adjusting means when a change in vehicle height is detected.

According to such a suspension, when the vehicle height does not substantially change, such as when the vehicle travels straight ahead at a substantially constant speed on a good road, the supporting load of the actuator is controlled to the static supporting load. This ensures the ride comfort of the vehicle, and when the vehicle body posture changes when the vehicle turns or accelerates or decelerates, and the vehicle height of the parts corresponding to each wheel changes due to this, the vehicle height changes. By controlling the fluid pressure within the actuator to increase or decrease from the offset pressure using a control amount based on the change, changes in vehicle height are suppressed or reduced, thereby suppressing changes in the attitude of the vehicle body.

Problems to be Solved by the Invention However, in the above-mentioned hydraulic suspension, even when the vehicle is traveling on a rough road, the pressure adjustment means is controlled by a control amount based on changes in vehicle height caused by unevenness of the road surface. Since posture control during mid-rest is performed by adjusting the fluid pressure in the actuator to increase or decrease from the offset pressure, there is a problem that the ride comfort of the vehicle is poor when the vehicle is traveling on rough roads.

In addition, in order to improve the ride comfort of the vehicle when driving on rough roads, reducing the control amount for the pressure adjustment means based on changes in vehicle height will prevent changes in the posture of the vehicle body when the vehicle turns or accelerates or decelerates. The problem is that it cannot be suppressed.

The present invention provides ride comfort control, that is, control that constantly adjusts the fluid pressure in the actuator to an offset pressure corresponding to its static support load, regardless of the stroke of each wheel, and vehicle body attitude control, that is, vehicle height control. Based on moxibustion, the degree of contribution of the control that adjusts the fluid pressure in the actuator to reduce changes in vehicle height is changed depending on the road surface condition. The object of the present invention is to provide an improved hydraulic suspension that can improve riding comfort when traveling on the road.

Means for Solving the Problems According to the present invention, a fluid pressure actuator disposed between each wheel and a vehicle body, and a pressure adjustment means for adjusting the fluid pressure in the actuator are provided. a vehicle height detection means for detecting the vehicle height of a portion corresponding to each wheel; a driving state determination means for determining turning and acceleration/deceleration of the vehicle; and a first vehicle height detection means based on the vehicle height detected by the vehicle height detection means. and a second control amount based on a static support load of the actuator. This is accomplished by a hydraulic suspension configured to reduce the first control amount when not present.

Effects and Effects of the Invention According to the configuration as described above, the pressure is adjusted based on the first control amount based on the vehicle height detected by the vehicle height detection means and the second control amount based on the static support load of the actuator. The control means for controlling the vehicle is configured to reduce the first control amount when the vehicle is not turning or accelerating or decelerating. It is possible to appropriately change the position depending on whether or not the vehicle is in the current state, thereby improving ride comfort when driving on a rough road without impairing attitude control performance when driving on a good road.

In other words, when the vehicle turns or accelerates or decelerates, the support of each actuator is determined based on the first control amount based on changes in vehicle height due to turning or acceleration/deceleration, and the second control amount based on the static support load of the actuator. Loads are controlled, which virtually eliminates body position changes.

Furthermore, when the vehicle is not turning or accelerating or decelerating, changes in vehicle height due to unevenness of the road surface are detected by the vehicle height detection means, but the first control amount based on the change in vehicle height is reduced. , the fluid pressure in each actuator is controlled to a pressure close to a predetermined offset pressure mainly based on the second control amount based on its static support load, thereby ensuring good ride comfort of the vehicle when driving on rough roads. Secured.

The fluid pressure actuator according to the present invention may have any structure as long as the supported load and vehicle height can be changed by adjusting the internal pressure.

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 suspension according to the present invention. The fluid circuit of the illustrated hydraulic suspension includes actuators IF1, which are provided corresponding to the front right wheel, front left wheel, rear right wheel, and rear left wheel of the vehicle, which are not shown in the figure, respectively. , 11L,
IRI? , 11? These actuators each have working fluid chambers 2PR, 2PL, 2RR,
It has 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 18PR for the right front wheel, the high pressure flow path 18PL 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 18H, respectively. High pressure flow path 1gPR.

181 L, 18 RR, 181? There are filters 2811.28FL and 281? in the middle of L, respectively. R, 28R
The other ends of these high-pressure channels are connected to the pilot-operated 3-port switching control valves 40.42.44.46 of the pressure control valves 32.34.36.38, respectively.
Attached to the boat.

The pressure control valve 32 is connected to the switching control valve 40 and the high pressure flow path 18F.
It consists of a flow path 50 that communicates and connects the low-pressure flow path 481'R 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 port 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.
It is a spool valve that takes in the pressure Pp in the flow path 50 between and the pressure Pa in the connection flow path 56 as pilot pressure, and when the pressure Pp is higher than the pressure Pa, it is a switching valve that connects port P and port A for communication. When the pressures Pp and Pa are equal to each other, the switching position 40a is switched to the switching position 40b where communication of all ports is cut off, and the pressure Pp is switched to the switching position 40b.
When the pressure is lower than the pressure Pa, the switch is switched to a switching position 40c in which port R and port A are connected in communication. 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 48F14 for the left rear wheel and a low pressure flow path 48F for the right rear wheel.
RR, one end of the low pressure flow path 48RL for the left rear wheel is connected, and the connection flow path 84, 86, 88 is connected to the A port, respectively.
is connected at one end. In addition, the switching control valves 42 to 46
are the flow paths 6 between the corresponding fixed throttle and variable throttle, respectively.
Pressure Pp in o~64 and corresponding connection channels 84~88
This is a spool valve that takes in the internal pressure Pa as pilot pressure, and when the pressure Pp is higher than the pressure pa, the boat P
Switching positions 42a and 44 that communicate and connect boat A with
a, 46a, and switch to switching positions 42b, 44b, 46b where communication between all boats is cut off when the pressures Pp and Pa are very equal, and when the pressure Pp is lower than the pressure Pa, the communication between boat R and boat A is switched. Switching position for communicating and connecting i242 c s 44 c 146
c.

As schematically shown in FIG. 1, each actuator IPR, 11L, 11? The working fluid chambers 2PR, 2PL, and 21? Cylinder 106FR, 106FL, 106RI defining R, 2RL? ,
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 plan view, a suspension spring is elastically mounted 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 106P 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 2r'R, 2PL, 2RR, 2R1 via throttles 124.126.128.130, respectively. Piston 108P+ again? , 1081 conversion,
108R1? , 108RL has a flow path 140F!
? , 1401'L, 140RR, and 140RL are provided. Each of these channels is a corresponding channel 56.
．． 84 to 88 and working fluid chambers 2PR, 2PL, 2RR.

2RL, and a filter 142 is installed in the middle of each.
It has PR, 142PL, 142RR, 142RI. Also actuators IFR, IFI1, IR
Vehicle height sensors 144F'R, 144PL, 144RI? are located close to R, IRl, and detect vehicle heights XFR, XFL, and XRRSXRL corresponding to each wheel. ,
144RL is provided.

In this way, each pressure control valve, each actuator, etc. not only increases or decreases the vehicle height at the corresponding position, but also changes the steering characteristics to improve the vehicle's steering characteristics by controlling the support load of the corresponding heavy wheels. constitutes a means.

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 pressure difference between the pressure inside 8FR, 181'l, 18■, 18R1 and the pressure inside the drain flow path 110.112.114.116 is below a predetermined value, the valve is maintained in a closed state. ing. 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 and a portion of the working fluid in the corresponding connection channel is guided to the channels 50, 60 to 64.

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

The other ends of the low pressure channels 48FR and 48P+ are connected to one end of the low pressure channel 48F for the front wheels, and the other ends of the low pressure channels 48RR and R1 are connected to the low pressure channel 481 for the rear wheels. is connected to one end of the The other ends of the low pressure channels 48F and 48R are connected to one end of the low pressure channel 48 in communication. Low pressure channel 4
8 has an oil cooler 174 in the middle and is connected to the reserve tank 4 via a filter 176 at the other end. 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, high pressure flow path 181? and low pressure channel 481? is connected to U and I by a flow path 188 that has a filter 182, a throttle 184, and a normally open electromagnetic on-off valve 186 capable of adjusting the flow rate. Solenoid on-off valve 18
6 is configured to open the valve and adjust the flow rate of the working fluid passing through the valve by energizing the solenoid 190 and changing its excitation current. Further, the 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 18R side with respect to the throttle 184 is high. The valve is switched to the open position 192b. In this way, the throttle 184, the electromagnetic on-off valve 186, and the on-off valve 192 cooperate with each other to selectively connect the high-pressure flow path 18R and the low-pressure flow path 48R1, and therefore the high-pressure flow path 18 and the low-pressure flow path 48, so that the high-pressure flow path 18R and the low-pressure flow path 48R1 are connected to each other. A bypass valve 196 is configured to control the flow rate of the working fluid flowing into the low-pressure flow path.

Furthermore, in the illustrated embodiment, pressure sensors 197 and 198 are provided in the high-pressure flow path 18R and the low-pressure flow path 48H, respectively, and these pressure sensors measure the pressure PS and the pressure of the working fluid in the high-pressure flow path, respectively. The pressure Pd of the working fluid in the low pressure flow path is detected. In addition, pressure sensors 19 are provided in the connecting channels 56, 84, 86, and 88, respectively.
9FR, 199PL, 199RR, and 199RL are provided, and these pressure sensors detect the working fluid chamber 2F'l? , 21'L, 2RR, and 2RL are detected. Furthermore, the reserve tank 4 is provided with a temperature sensor 195 that detects the temperature T of the working fluid stored in the tank.

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 human-powered boat device 210 receives a signal indicating the U rotation speed N of the engine 14 from the rotation speed sensor 16, and pressure sensors 197 and 1.
Signals indicating the pressure Ps in the high-pressure flow path and the pressure Pd in the low-pressure flow path from 98, pressure sensors 199PL, 19
9PR, 199RL, 1991? lHarisotl' and working fluid chamber 2F'l5.2PR, 2R14, 21? A signal indicating the pressure PI (+-1, 2, 3, 4) in R, a signal indicating whether the ignition switch is on from the ignition switch (IGSW) 216, a signal indicating whether the ignition switch is on or not, and a signal L1 provided in the passenger compartment of the vehicle. A signal indicating whether or not the switch is in the on state from the emergency engine switch (EMSW) 218 operated by the vehicle height sensor 144FL, 1
44PR.

From 144 R1, 144RR, vehicle height X1 (1-1
, 2, 3, 4) are respectively input.

The input port device 210 also receives a signal indicating the vehicle speed V from the vehicle speed sensor 234, a signal indicating the longitudinal acceleration Ca from the longitudinal G (acceleration) sensor, a signal indicating the lateral acceleration G1 from the lateral G (acceleration) sensor 238, and a signal indicating the lateral acceleration G1 from the steering angle sensor. A signal indicating the steering angle θ, a signal indicating the throttle opening θa from the throttle opening sensor 242, an idle switch (IDSW) 24
4, a signal indicating whether the idle switch is in the on state, a signal indicating whether the brake switch is in the on state, from the brake switch (BKSW) 246, and a signal indicating the vehicle height control set by the vehicle height setting switch 248. A signal indicating whether the mode is high mode or low mode is inputted.

The human-powered boat device 210 processes the human-powered signals as appropriate, and stores the two in the program stored in the ROM 206.
&<CPU and RAM 208 according to instructions from CPU 204
It is designed to output the processed signal to. ROM
206 is Fig. 3, Fig. 8A to Fig. 8C, Fig. 9 to Fig. 11
The control flow shown in the figures and the maps shown in FIGS. 4 to 7 and 12 to 45 are stored. The output boat device 212 outputs the drive circuit 2 according to instructions from the CPU 204.
20, a control signal is output to the electromagnetic on-off valve 186, and the drive circuits 222-228 are connected to the pressure control valves 32-38, specifically the solenoids 58, 78, 80. The control signal is output to the display 232 via the drive circuit 230.

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. Furthermore, in the flowchart shown in FIG. 3, the flag Fr is related to whether or not there is a failure in any part of the fluid pressure suspension, and l is related to whether or not there is a failure in any of the 64 parts of the fluid pressure suspension. The flag Fc is related to whether or not the engine is in an operating state, 1 indicates that the engine is in an operating state, and the flag Fp indicates that the pressure Ps of the working fluid in the high pressure flow path is Threshold suppressing force p that completely opens the shutoff valves 150 to 156
This is related to whether or not you have ever experienced a level of C or higher.
1 indicates that the pressure Ps has exceeded the pressure Pc, and the flag Fs indicates the standby pressure 1bi (1 -1, 2, 3, 4) is set or not, 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 O, 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 pressure Ps in the high pressure flow path detected by 98, pressure sensor 199 PL, 199F! ? , 199RL
11991? l? Working fluid chamber 2PL detected by
A signal indicating the pressure Pi in 2DOR, 2RL, and 2RR, a signal indicating whether the ignition switch 216 is in the on state, a signal indicating whether the EMSW 218 is in the on state, vehicle height sensors 144FL, 144FR, 144R
L, a signal indicating the vehicle height X1 detected by 144RR,
A signal indicating the vehicle speed detected by the vehicle speed sensor 234,
A signal indicating the longitudinal acceleration Ca detected by the longitudinal G sensor 236, a signal indicating the lateral acceleration G1 detected by the lateral G sensor 238, a signal indicating the steering angle θ detected by the steering angle sensor 240, a throttle opening sensor 242 A signal indicating the throttle opening θa detected by ID5W
BKSW2, a signal indicating whether or not 244 is in the on state.
46 is in the on state and a signal indicating whether the mode set by the vehicle height setting switch 248 is high mode or low mode are read, and then the process proceeds to step 40.

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 240, where it is determined that 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 EMSW is in the on state, and when it is determined that the EMSW is in the on state, the process proceeds to step 220, where it is determined that the EMSW is not in the on state. When the determination has been made, the process advances to step 60.

In step 60, it is determined whether or not the flag Fl' is 1, and when it is determined that the flag is Fl'-1, the process proceeds to step 220, where it is determined that the flag Fl' is not Ff'-1. If the determination is successful, the process advances to step 70.

In step 70, whether or not the engine is being operated is determined by determining whether the engine rotation speed N detected by the rotation speed sensor 16 and read in step 32 exceeds a predetermined value. A determination is made, and when it is determined that the engine is not being operated, the process proceeds to step 110, and when it is determined that the engine is being operated, the process proceeds to step 80.

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 80, the flag Fe is set to 1, and from the time when the engine operation is started until the time when the standby pressure P old of the pressure control valves 32 to 38 is set in step 200, which will be described later. A timer is started for a time Ts, after which the process proceeds to step 90. In this case, if the flag Fc has already been set to l, it remains in that state, and if the timer Ts has already been activated, the timer continues counting.

In step 90, 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 100.

In step 100, the current 1b calculated in step 90 is applied to the solenoid 190 of the electromagnetic on-off valve 186, thereby driving the bypass valve 195 in the closing direction, and then the process proceeds to step 130.

In step 110, the operation of the TS timer is externalized, and the process then proceeds to step 120. In this case, if the Ts timer is not activated, it remains in that state.

In step 120, it is determined whether the flag Fe is 1 or not, and when it is determined that Fc=1, that is, the engine has been started and then stopped, step 220 is performed. If it is determined that the engine is not FO-1, that is, the engine has not been started at all, the process advances to step 130.

In step 130, it is determined whether the pressure PS in the high pressure flow path is equal to or higher than the threshold value Pc, and when it is determined that Ps≧Pc is not satisfied, the process proceeds to step 170, where Ps≧ When it is determined that it is Pc, the process advances to step 140.

In step 140, flag Fp is set to 1, and then the process proceeds to step 150.

In step 150, in order to control the ride comfort of the vehicle, the posture control of the vehicle body, and the steering characteristics, the
As will be described in detail with reference to the drawings that follow, active calculations are performed based on the various signals read in step 30, so that the variable throttle 54 of each pressure control valve.
The current 1 ul to be energized to the solenoids 58, 78, 80, 82 of 72 to 76 is calculated, and then step 290
Proceed to.

In step 170, it is determined whether the flag Fp is 1 or not, and it is determined that the flag Fp is Fp-1, that is, the pressure Ps of the working fluid in the high pressure flow path is equal to or higher than the threshold pressure Pc. If it is determined that the value has become lower than this after the above, the process proceeds to step 1.50, and it is determined that the pressure is not Fp-1, that is, the pressure PS has never exceeded the threshold pressure Pc. When the determination has been made, the process advances to step 180.

In step 180, it is determined whether the flag Fs is 1 or not, and if it is determined that it is Fs-1, the process proceeds to step 290, and it is determined that it is not Fs-1. If so, proceed to step 190.

In step 190, 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 290, where it is determined that the time Ts has elapsed. When this has been performed, the process advances to step 200.

In step 200, 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 Pbl, and the pressure shown in FIG. Based on the map corresponding to the graph shown in FIG. Working fluid chamber 2PL, 2PR, 2R
L, 2RR variable restrictor 72 of the pressure control valve 34.32.38.36 to a pressure substantially equal to the pressure PI in 2RR.
．． 54.76.74 solenoid 78.58.82.8
The current 1bi (1-1, 2, 3, 4) to be energized to 0 is calculated, and the process then proceeds to step 210.

In step 210, flag Fs is set to 1, and then the process proceeds to step 290.

In step 220, the solenoid 190 of the electromagnetic on-off valve 186 of the bypass valve 196 is adjusted based on the map corresponding to the graph shown in FIG. 6 stored in the ROM 206.
The current 1b to be applied to is calculated by Ib-1b-ΔI be , and then the process proceeds to step 230 .

In step 230, the current 1b calculated in step 220 is applied to the solenoid 190, thereby driving the bypass valve 196 in the opening direction, and then the process proceeds to step 290.

In step 240, it is determined whether or not a timer related to Torr is activated, which is the time from when the ignition switch is turned off to when the main relay is turned off, and the Tol'r timer is activated. When it is determined that the
If it is determined that the timer is not activated, the process advances to step 250.

In step 250, the To('f' timer is started, and the process then proceeds to step 260.

In the step tube 260, based on the map corresponding to the graph shown in FIG. `` is calculated according to the following, and then the process proceeds to step 270.

In step 270, the current 1b calculated in step 260 is applied to the wire 190 of the electromagnetic on-off valve 186, thereby driving the bypass valve 196 in the opening direction, and then the step ? Proceed to section 280.

In step 280, it is determined whether or not the time Tol'f' has elapsed, and when it is determined that the time Tol'l' has elapsed, the process proceeds to step 350, and the time Torr has elapsed. If it is determined that the data is not present, the process advances to step 290.

In step 290, step 90.220.26
It is determined whether the current tb calculated at 0 is greater than or equal to the reference value Ibo, and Ib≧Ib.

If it is determined that Ib is not true, the process proceeds to step 320, and if it is determined that Ib≧Ibo, the process proceeds to step 300.

In step 300, it is determined whether the pressure Ps of the working fluid in the high pressure flow path read in step 30 is greater than or equal to the reference value Pso, and it is determined that Ps≧Pso is not satisfied. When the Ps
When it is determined that ≧Pso, step 3
Proceed to step 10.

In step 310, the current l1 calculated in step 200 or the current lui calculated in step 150 is applied to the variable throttle solenoid 58.7 of each pressure control valve.
Each pressure control valve is driven by the output to the valves 8 to 82, and the control pressure thereof is controlled.
Go to 0.

In step 320, it is determined whether or not a fail exists at any location within the hydraulic suspension, and when it is determined that a fail does not exist, the process proceeds to step 340, where it is determined that a fail exists. If it is determined to do so, the process advances to step 330.

In step 330, the fail flag F'' is set to 1, and the process then proceeds to step 340.

In step 340, a diagnosis process is performed for each part in the hydraulic suspension, and if an abnormality such as a failure exists, a code number indicating the location is displayed on the display 232, and the code number indicating the location is displayed. There is also an abnormality at the location (if there is no one nigga, the process returns to step 30 without displaying the code number on the display, and steps 30 to 34 described above are performed).
0 is repeated.

In step 350, the main relay is turned off, thereby terminating the control flow shown in FIG. 3 and de-energizing the electrical control device 200 shown in FIG. Ru.

Furthermore, the pressure control by the bypass valve at the time of starting the operation and at the time of stopping the operation described above does not constitute the main part of the present invention, and the details of these pressure controls are referred to in the application filed by the same applicant as the present applicant. Please refer to Japanese Patent Application No. 63-307189 and Japanese Patent Application No. 63-307190.

Next, the active operation performed in step 150 will be described with reference to FIGS. 8A to 8C and FIGS. 9 to 45.

First, in step 40'O, the heap 11 target value Rxb, the pitch target straightness RXp, and the roll target value RXr are calculated based on the maps corresponding to the graphs shown in FIGS. 12 to 14, respectively. The process then proceeds to step 410.

In FIG. 12, solid lines and broken lines indicate patterns when the vehicle height control mode set by the vehicle height setting switch is normal mode and high mode, respectively.

In step 410, the heap (Xxb
), pitch (Xxp), roll (Xxr), and warp (Xxw) are calculated for displacement mode conversion,
Thereafter, the process proceeds to step 420.

Xxh-(XI+X2)+(X3+Na)XX
I)--(Xl +X2) + (X3 +X4)
Xxr-(XtX2)+(X3-Xa)X
xv=(XI-X2)-(X3-Xa) In step 420, the deviation of the displacement mode is calculated according to the following equation, and then the process proceeds to step 430.

E xh −Rxh −X xh E Xl) −Rxp −X xp E xr−Rxr −X xr E xv −Rxv −X XXV calculated at knob 410 or Xx calculated in the past few cycles
The instep of ν may be straight. Further, when IExv≦W+ (positive constant), Exw-0 is set.

In step 430, as will be explained in detail later with reference to FIG.
Turning determination, acceleration determination, and deceleration determination are performed, and then the process proceeds to step 440.

In step 440, based on the determination result in step 430, the gain KpjSK ij of the displacement feedback control is determined, as will be explained in detail later with reference to FIG.
%Kdj (j=xh, XI)SxrSxv) is calculated, and then the process proceeds to step 450.

In step 450, PID compensation calculation for displacement feedback control is performed according to the following equation, and then the process proceeds to step 460.

Cxh −K pxh −E xh+ K i
xh I xh(n)+K dxh (E
xh(n) −E xh(n−n+)ICxp −
K pxp IIE xp+ K ixp I xp
(n) + K dxp (E xp(n) −E x
p(n-n+)ICxr -K pxr 11
E xr+ K ixr I xr
(n) + K dxr (E xr(n) −E
xr(n-nI))CXV-Kpxv ・E
xw+K ixv II1 xw(n)+K dx
w (E xw(n) −E xw(n−nl
)) In each of the above formulas, E j(n) (j= Xll
, Xp, Xr%xv) is the current Ej, and E j(
rl-n I ) is Ej nl cycles ago. Also, Ij(n) and Ij(n-1) are the current and one cycle previous Ij, respectively, and TX is the time constant, Ij(n)=Ej(n)+T x Ij(n
-1), and Ijmax is a predetermined value, 1ljl≦
I jmax. Further, the gains Kpj, Kij, Kdj (j−xhS
xp, xr, xw) are proportional constant, integral constant,
It is a differential constant.

In step 460, an inverse transformation of the cystic mode is performed according to the equation shown below, and the process then proceeds to step 470.

Px I-1/4 ・Kx I(Cxh-Cxp+Cx
r+Cxv)PX 2-1/4 ・KX 2 (CXI
I-Cxp-Cxr-Cxw)Px 3 -1/4
・KX 3 (Cxb+Cxp+Cxr-Cxw
)PX 4 -1/4 ・Kx 4 (Cxh+
Cxp-Cxr+Cxv) Kx IKX 2 , Kx
3, Kx 4 is a proportionality constant.

In step 470, the longitudinal and lateral directions of the vehicle are calculated based on the longitudinal and lateral accelerations, respectively, based on the maps corresponding to the graphs shown in FIGS. 15 and 16, respectively. The pressure correction property P gaSP gl in the lateral direction is calculated, and the process then proceeds to step 480 .

In step 480, as will be explained in detail later with reference to FIG. 11, the gain KpI of the G feedback control is
Il, KdIIl(II-gaSgr) are calculated,
Thereafter, the process proceeds to step 490.

In step 490, the pitch (C
Gp) and roll (Cgr), calculation of PD compensation of G feedback control is performed, and then step 50
Go to 0.

Cgp-Kpgp ΦPga+Kdgp (Pga(
n)-P ga (n - Tomi II)) Cgr-Kpgr Pgl+Kdgr (Pgl(n
)-P gl(n-nI )1 In each of the above formulas, P ga(n) and Pgl(n) are the current Pga and Pgl, respectively, and P ga(n
-nI) and Pgl (n-nl) are [Pga and Pgl before 11 cycles, respectively. Moreover, K pgp and Kpgr are proportional constants, and K dgp and K dg
r is a differential constant.

In step 500, the steering angular velocity θ is calculated according to θ−θ′, where θ′ is the steering angle read in step 3o one cycle before the flowchart in FIG. Based on the map corresponding to the graph shown in FIG. 17 using the angular velocity and gravity velocity V, the rate of change in lateral G, that is, G1, is calculated as FE">
The process then proceeds to step 510.

In step 510, an inverse G-mode conversion calculation is performed according to the equation (), and the process then proceeds to step 520.

Pg r −Kg I/4 ・(2 r to −Cgp+
・Cgr+ 1 "ΦG+) Pg2-Kg2/4・ (Cgp K2 "Cgr-
, I' ・Gl) Pg J −Kg J /4 ・(Cg[
)+2 r ・Cgrl＼+1r reference 〇+) Pg 4 −Kg a /4 ・(Cgl)−
2 r ・To Cgr - KI r φ Gl) Note that Kg+ Kg2, Kg3, and Kga are proportional constants, respectively, and Klr and ni, r , K21', and ni2r
are constants as distribution gains between the front and rear wheels, respectively.

In step 520, the RAM in step 200 is
Based on the pressure Pbi stored in 208 and the results calculated in steps 460 and 510, P ui −P
The target control pressure Pui of the six pressure control valves is determined according to xl+Pgi+PbL (1-1, 2, 3, 4), and the process then proceeds to step 530.

In step 530, the L1 target current to be supplied to each pressure control valve is calculated according to the formula F, and then the process proceeds to step 540.

11 = Ku 1 Pu 1 +Kh
(I Do-Ps )-Kl ・Pd-α 12 -Ku 2 Pu 2 +Kh (1
0O−Ps )−Kl φ Pd −α 13 =Ku 3 Pu 3 +Kh (
100Ps )-Kl ・Pd 14-Ku4 Pu4 +Kh (100-Ps
)-Kl φ Pd Note that KuI Ku2, Ku3, Ku4, Kh, and Kl are proportional constants, and α is a correction constant between the front and rear wheels.

In step 540, the humidity correction coefficient Kt is calculated based on the map corresponding to the graph shown in FIG. A temperature correction calculation is performed, and then the process proceeds to step 550.

In step 550, the current warp (the amount of twist around the longitudinal axis of the vehicle body) is calculated according to Iv-(ILl-112) (IL3-114), and then the process proceeds to step 560.

In step 560, the first current warp control nmRi is performed based on the map corresponding to the graph shown in FIG.
vl is played, and the process then proceeds to step 570.

In step 570, the second current warp control mRiw is performed based on the map corresponding to the graph shown in FIG.
p is calculated, and then the process proceeds to step 570.

In step 580, the ground load of the front wheels is calculated according to the above formula, and then the process proceeds to step 590.

Wr=Kl[' (Iu 1 + Iu 2 ) +2
Ksf. is the average value of the spring constant of the suspension spring, and Xs is the average value of the vehicle heights X1 and X2 of the left and right front wheels.

In step 590, the ground load of the rear wheels is calculated according to the following formula, and then the process proceeds to step 600.

Wr −Kir(Iu J +Iu a ) +2Ks
r・XsrIn the above equation, Kir is a proportionality constant, and I
u3 and Iu4 are the final target currents for the left rear wheel and right rear wheel calculated in step 660 one cycle before, Ksr is the average value of the spring constants of the left and right front suspension springs, and XSr is the This is the average value of wheel heights X3 and X4.

In step 600, based on Wf and Wr calculated in steps 580 and 590, the load distribution ratio K between the front and rear wheels is calculated according to K-W'/Wr, and the process then proceeds to step 610.

In step 610, a third current warp control uRiw is performed based on the map corresponding to the graph shown in FIG.
3 is calculated, and the process then proceeds to step 620.

In step 620, step 5
The sum of the current warp control amounts calculated in steps 60, 570, and 610 is calculated, and the process then proceeds to step 63,0.

Riv-Kv 1 IIR1wI+Kw 2 ・Ri
v2+Kv3-Rlv3 Note that Kv I Kv 2 and Kw 3 are proportionality constants.

In step 630, the bias of the current warp is calculated according to the following equation, and then the process proceeds to step 640.

Eiw-Rlv-1v Note that 1'' standard deviation I Ri in the above formula may be O.

In step 640, the current warp E1 target control amount is calculated according to Eivp-R1vp-Eiv using Kivl) as a proportionality constant, and then the process proceeds to step 650.

In step 650, an inverse transform of the current warp is calculated according to the following equation, and the process then proceeds to step 660.

Iw 1 =Eiwp /4 Iw 2 --Elwp /4 Iv 3 --Eiwp /4 Iv 4 -Eivp /4 In step 660, based on the results calculated in steps 540 and 650, the following formula is used. Accordingly, the final L1 reference current 1ui to be supplied to each pressure control valve is calculated, and then the process proceeds to step 290 in FIG.

I ui −I Li+ I vi (l−1, 2, 3, 4) Next, referring to the flowchart shown in FIG.
The running condition determination routine performed in step 430 in the figure will be described.

First, in step 700, a bypass filter process is performed to remove components below a predetermined frequency from the vehicle heights XI to X4 read in step 30 over several cycles, and then the process proceeds to step 710.

In step 710, RMS processing is performed on the bypass filtered vehicle heights X and -Y4 to calculate effective values Y and -Y4 of the vibration components, and then the process proceeds to step 720.

In step 710, the rough road characteristic value Xa is calculated according to Xa = Y1 + X2 + Y3 + Y4, and then in step 730
Proceed to. Note that the larger Xa is, the greater the degree of roughness of the road.

In step 730, the rough road characteristic value Xa is set to a predetermined value CX.
It is determined whether Xa>CX is exceeded, and when it is determined that Xa>CX is not satisfied, the process proceeds to step 750;
If it is determined that Xa>Cx, the process advances to step 740.

In step 740, the rough road determination flag Fx is set to 1, and the process then proceeds to step 760.

In step 750, the rough road determination flag FX is reset to 0, and the process then proceeds to step 760.

Thus, in steps 700 to 750, it is determined whether the vehicle is traveling on a rough road or not. If the vehicle is traveling on a rough road, the flag Fx is set to 1, and it is determined that the vehicle is traveling on a rough road. If the vehicle is not traveling on the road, the flag FX is set to 0.

In step 760, it is determined whether the absolute value of the steering angular velocity θ exceeds a predetermined value CI, and 1θl>
When it is determined that it is C1l, step 79
Go to 0, 1θ! > If it is determined that it is not C1, the process advances to step 760.

In step 770, it is determined whether the absolute value of the rate of change of tAG exceeds a predetermined value CI2, and
When it is determined that GII>C10, the process proceeds to step 790, and when it is determined that IGII>C2 is not the case, the process proceeds to step 780.

In step 780, the absolute value of FMG is set to a predetermined value CI.
It is determined whether Gll>C10 is exceeded.
When it is determined that ICII>C10 is not satisfied, the process proceeds to step 790, and when it is determined that ICII>C10 is not satisfied, the process proceeds to step 800.

In step 790, the turning determination flag F is set to 1, and the process then proceeds to step 810.

In step 800, the turning determination flag F1 is reset to 0, and the process then proceeds to step 810.

Thus, in steps 760-800, the width.

A determination is made as to whether or not the vehicle is turning. If the vehicle is turning, flag F1 is set to 1, and if the vehicle is not turning, flag F1 is set to 0.

In step 810, the idle switch (IDSW)
) is off, and when it is determined that ID5W is not off, the process advances to step 860, and when it is determined that ID5w is off, the process advances to step 820.

In step 820, the rate of change θa of the throttle opening is determined.
It is determined whether or not θ exceeds a predetermined value Ca1.
When it is determined that a > Ca 1, the process proceeds to step 850, and when it is determined that θa>Ca is not satisfied, the process proceeds to step 830.

In step 830, it is determined whether the tabulation rate Ga of the front and rear G exceeds a predetermined value Ca2, and if Ga>C
When it is determined that it is a2, step 850
If it is determined that Ga>Ca2 is not satisfied, the process advances to step 840.

In step 840, it is determined whether the front and rear G exceeds a predetermined value CaJ, and when it is determined that Ga>Ca3, the process proceeds to step 850, where the Ga
>Ca 3, the process advances to step 860.

In step 850, the acceleration determination flag Fa is set to 1, and the process then proceeds to step 870.

In step 860, the acceleration determination flag Fa is reset to O, and the process then proceeds to step 870.

Thus, in steps 810 to 860, it is determined whether or not the vehicle is in an accelerating state. If the vehicle is accelerating, the flag Fa is set to 1, and if the vehicle is not accelerating, the flag Fa is set to 1. flag Fa is set to 0.

In step 870, the brake switch (BKSW)
) is in the on state, and B K S
When it is determined that W is in the on state, the process advances to step 890, and when it is determined that ID5W is not in the on state, the process advances to step 880.

In step 880, it is determined whether or not the ID5W is in the on state, and when it is determined that the ID5W is not in the on state, the process advances to step 920, and the ID5W is in the on state.
When it is determined that W is in the on state, the process advances to step 890.

In step 890, it is determined whether the rate of change Ga between the front and back G is less than a predetermined value -Cb1, and if a<-C
If it is determined that it is b+, step 910
The process proceeds to step 90O, and when it is determined that Ga<-Cb 1 is not satisfied, the process proceeds to step 90O.

In step 900, the front and rear G (Ga) is set to a predetermined value -c
It is determined whether or not Ga<Cb is less than b2.
If it is determined that it is not 2, step 920
If it is determined that Ga<-Cb2, the process advances to step 910.

In step 910, the deceleration determination flag Fb is set to 1, and the process then proceeds to step 440 in FIG. 8A.

In step 920, the deceleration determination flag Fb is reset to 0, and the process then proceeds to step 440.

Thus, in steps 870 to 920, it is determined whether the vehicle is in a deceleration state, and if the vehicle is in a deceleration state, the flag Fb is set to 1, and if the vehicle is not in a deceleration state, the flag Fb is set to 1. The flag Fb is set to 0.

Next, the displacement feedback control gain calculation routine performed in step 440 of FIG. 8A will be described with reference to the flowchart of FIG. 10.

First, in step 1000, it is determined whether the rough road determination flag Fx is 1 or not. When it is determined that the flag Fx is not 1, the process proceeds to step 1020, and when the flag FX is 1, the process proceeds to step 1020. When it is determined that there is, the process advances to step 1010.

In step 1010, step 450 of FIG. 8A
P term (proportional term) in the arithmetic expression of the operation executed in
The rough road gain component of the gain XKpxh, XKpx
p , XKpxr , XKpxwI term (integral term) gain component for rough roads XKIXII , XK+Xp,
XKixr , XKdxh , XKdxp , XKdxh , XKdxp , X
Kr1xr and XKdxv are shown in Fig. 22 and 2, respectively.
The calculation is performed based on the maps corresponding to the graphs shown in FIGS. 3 and 24, and then the process proceeds to step 1030.

In step 1020, the rough road gain component is set to 0, and the process then proceeds to step 1030.

In step 1030, it is determined whether or not the turning determination flag F is 1. If it is determined that the flag F is not 1, the process proceeds to the steering knob 1050, and if the flag F1 is 1, the process proceeds to the steering knob 1050. If it is determined that there is, the process advances to step 1040.

At step 1040, based on the map corresponding to the graph shown in FIG. 25, the gain of the P term (proportional term) in the arithmetic expression of the operation executed at step 450 of FIG. 8A is calculated. Turning gain component L Kpx
h, L Kpxp s L Kpxr, L Kp
Turning gain component LKI of gain of xv1 term (integral term)
xh 5LKixp, LKixr 5LKixvD
Turning gain component L Kdxh of the gain of the term (differential term)
, L Kdxp , L Kdxr SL Kdx
w is calculated, and then the process proceeds to step 1060.

In step 1050, the turning gain component is set to O, and the process then proceeds to step 1060.

In step 1060, it is determined whether or not the turning determination flag F1 is 1, and when it is determined that the flag F1 is not 1, the process proceeds to step 1080, where it is determined that the flag F1 is 1. When the determination has been made, the process advances to step 1070.

At step 1070, based on the map corresponding to the graph shown in FIG. 26, the gain of the P term (proportional term) in the arithmetic expression of the operation executed at step 450 of FIG. 8A is calculated. Acceleration gain component AKpxh
, AKpxp , AKpxr , AKI3Xll/
Acceleration gain component AKlxh of gain of 1st term (integral term)
5AKixp, AKixr, AKixwD terms (
Acceleration gain component A Kdxh S
A Kdxp SA Kdxr and A Kdxv are calculated, and then the process proceeds to step 1090.

In step 1080, the acceleration gain component is set to O, and the process then proceeds to step 1090.

In step 1090, it is determined whether or not the acceleration determination flag Fa is 1, and when it is determined that the flag Fa is not 1, the process proceeds to step 1110, where it is determined that the flag Fa is 1. If the determination has been made, the process advances to step 1100.

In step 1100, based on the map corresponding to the graph shown in FIG. 27, the P term (proportional term) in the expression p of the operation p executed in step 450 of FIG. 8A is calculated. Gain deceleration gain component B Kpx
h, B Kl)XI) SB Kpxr, B
Deceleration gain component B of gain of KpxwI term (integral term)
Kixh, BKixp, BKixr 1BKi
Deceleration gain component B K of gain of xwD term (differential term)
dxh, Bdxp, Bdxr, and Bdxv are calculated, and then the process proceeds to step 1120.

In step 1110, the deceleration gain component is set to 0, and the process then proceeds to step 1120.

In step 1120, based on the map corresponding to the graphs shown in FIGS. 28 to 34, step 110
．． Correction coefficients PXKpj, PXKijSP for each gain component calculated in 1040, 1070.1100
XKdj PLKpj, PLKijSPLKdj PAKpj, PAKIj, PAKdj PBKpjSPBKijSPBKdj (j - Xll, XI), xr, xw) is calculated, and then the process proceeds to step 1130.

In step 1130, step 1010.104
Based on each gain component calculated at 0.1070.1100 and the correction coefficient calculated at step 1120, the displacement feedback control gain is calculated according to the following formula, that is, executed at step 450 in FIG. 8A. Gain Kpj%Kl of the P term, 1st term, and D term of the calculation formula, respectively
j, Kdj (j-xll, xL

Kpj-PXKpj (-XKpj) +p LKpj
-LKpj+PAKpj-AKpj+P BKpj@
BKpj+CpjKij-PXKij (-XKij)
+P LKij・ LKIj+ P A K ijφ
AKIj+PBKijΦ B K t, H+ c BK
DJ style PXKdj (-XKdj) + PLKdj・L
Kdj+PAKdj-AKdj+PBKdj・BK
dj+Cdj(j-xh, xp, xr, xv) (CpjSC1jSCdj is a constant) Next, the G feedback control gain calculation routine performed in step 480 of FIG. 8B will be explained with reference to the flowchart of FIG. 11. .

First, in step 1200, it is determined whether or not the rough road determination flag Fx is 1. If it is determined that the flag Fx is not 1, the process proceeds to step 1220, and if the flag Fx is 1, then the process proceeds to step 1220. If it is determined that there is, the process advances to step 1210.

In step 1210, step 490 of FIG. 8B
P term (proportional term) in the arithmetic expression of the operation executed in
The rough road gain component of the gain XKI)gl), XKpg
r Rough road gain component of the D term (differential term) gain XKdgp
, XKdgr are calculated based on the maps corresponding to the graphs shown in FIG. 35 and FIG.
Go to 0.

In step 1220, the rough road gain component is set to 0, and the process then proceeds to step 1230.

In step 1230, it is determined whether or not the turning determination flag F1 is 1, and when it is determined that the flag F1 is not 1, the process proceeds to step 1250, where it is determined that the flag F1 is 1. When the determination has been made, the process advances to step 1240.

At step 1240, based on the map corresponding to the graph shown in FIG. 37, the gain of the P term (proportional term) in the arithmetic expression of the operation executed at step 450 of FIG. 8A is determined. Turning gain component L Kl)
gl), L Kpgr Turning gain component of gain of D term (differential term) L Kdg
p SL Kdgr is calculated, and then the process proceeds to step 1260.

In step 1250, the turning gain component is set to O, and the process then proceeds to step 1260.

In step 1260, it is determined whether or not the turning determination flag F1 is 1, and when it is determined that the flag F1 is not 1, the process proceeds to step 1280, where it is determined that the flag F1 is 1. When the determination is made, the process advances to step 1270.

At step 1270, based on the map corresponding to the graph shown in FIG. 38, the gain of the P term (proportional term) in the arithmetic expression of the operation executed at step 490 of FIG. 8B is calculated. Acceleration gain component AKpgl
), AKpgr Gain component for acceleration of D term (differential term) gain A Kdg
p SA Kdgr is calculated, and then the process proceeds to step 1290.

In step 1280, the acceleration gain component is set to 0, and the process then proceeds to step 1290.

In step 1290, it is determined whether or not the acceleration determination flag Fa is 1, and when it is determined that the flag Fa is not 1, the process proceeds to step 1310, where it is determined that the flag Fa is 1. When the determination has been made, the process advances to step 1300.

At step 1300, based on the map corresponding to the graph shown in FIG. 39, the gain of the P term (proportional term) in the arithmetic expression of the operation executed at step 490 of FIG. 8B is determined. Deceleration gain component B Kpg
p, B Kpgr Gain component for deceleration of gain of D term (differential term) B Kdg
p SB Kdgr is calculated, and then the process proceeds to step 1320.

In step 1310, the deceleration gain component is set to 0, and the process then proceeds to step 1320.

In step 1320, based on the map corresponding to the graphs shown in FIGS. 40 to 45, step 120
．． Correction coefficient P X Kpg[) SP for each gain component calculated in 1240.1270.1300
X KpgrP L Kpgp, P L Kpgr
PAKpgp, PAKpgr PB Kpgp, PB Kpgr are calculated,
Thereafter, the process advances to step 1330.

In step 1330, step 1210.124
Based on each gain component calculated at 0.1270.1300 and the correction coefficient calculated at step 1320, the 6 feedback control gain is calculated according to the following formula, that is, executed at step 490 in FIG. 8B. The P-term gains Kpgp, Kpgr and the D-term gains KdgpSKdgr of the arithmetic expressions are calculated according to the following formulas, and then the process proceeds to step 490 in FIG. 8B.

Kpgp -pXKpgp (-XKI)gp)+
P L Kpgp II L Kpgp 10P A K
pgp豐A K pgp十PBKpgpψB Kpg
p 10CpgpKpgr -PXKpgr (-X
Kpgr ) + PLKpgr φ LKpgr + P A Kpgr -A Kpgr + P B
Kpgr #B Kpgr 10CpgrKdgp =
P XKdgl) (-XKdgp) + P L
Kdgp' L I((Igp+ P A Kdg
p -A Kdgp+ P B Kdgp-B Kd
gp 10 Cagl) Kdgr -P X Kdgr
(-X Kdgr) + P L Kdgr Φ
L Kdgr+ P A Kdgr 11 A K
dgr+ P B Kdgr 11 B Kdgr
+ Cdgr(Cpgp, Cpgr, C(1g
(p, Cdgr are constants) In the above embodiment, the P term, 1 term,
The gain of the D term is calculated by each individual map,
For the same term, the gains of each mode such as heap are calculated using the same map, but these maps may be set individually for each mode. Furthermore, maps of the same type may be combined into one map, such as the maps corresponding to the graphs shown in FIGS. 22 to 24, for example.

Thus, according to this embodiment, steps 400-530
In accordance with the present invention, calculations for ride comfort control and mid-rest posture control of the φ vehicle are performed, and steps 550 to 65 are performed.
At 0, calculations are performed to control the steering characteristics.

As described above, in step 520, the pressure Pxi corresponding to the first control r8m based on the small height Xt, the pressure Pold corresponding to the second control amount 911 based on the static support load of each actuator, and the vehicle body 1] Standard pressure Put is calculated as the sum of the pressure Pgi corresponding to the third control amount based on the acceleration of
In step 660, a final target current 1ui is calculated as the sum of the current 11+ for ride comfort control and attitude control corresponding to this target pressure and the current 1vi for steering characteristic control.
Based on this final target current, the control pressure of each pressure control valve, and therefore the pressure in the working fluid chamber of each actuator, is controlled.

In this case, if it is determined in steps 760 to 920 that the vehicle is not in a turning or acceleration/deceleration state, each gain component is set to 0 in steps 1050, 1080, and 1110. The displacement feedback control gains Kpj, Kij, and Kdj are reduced, thereby reducing the control amount based on the small height Xi when the vehicle is not in a turning or acceleration/deceleration state.

Therefore, the degree of contribution of ride comfort control and attitude control, especially the degree of contribution of attitude control in comparison with ride comfort control, is appropriately changed depending on whether the vehicle is turning or accelerating/decelerating. It is possible to improve ride comfort when traveling on a rough road without impairing attitude control performance during turning and acceleration/deceleration while traveling on a good road.

For example, when turning or accelerating or decelerating a vehicle, each control is performed based on a first control amount based on changes in vehicle height, a second control amount based on standby pressure of the actuator, and a third control amount based on the acceleration of the vehicle body. The pressure within the working fluid chamber of the actuator is controlled, thereby effectively suppressing the attitude change of the vehicle body.

Furthermore, when the vehicle is not turning or accelerating or decelerating, the vehicle height sensor detects changes in vehicle height due to unevenness of the road surface, and the acceleration of the vehicle body is detected by the longitudinal acceleration sensor and lateral acceleration sensor. By reducing the first control amount based on the change and the third control amount based on the acceleration of the vehicle body, the pressure in the working fluid chamber of each actuator is substantially put on standby mainly based on the second control amount rB. This ensures good ride comfort for the vehicle.

In addition, in the above-mentioned embodiment, it is determined not only whether the vehicle is in a turning, acceleration, or deceleration state, but also whether the traveling road is a rough road, and based on the determination result, The second and third control amounts are adjusted according to the vehicle speed, and the second and third control amounts are also adjusted by 2J depending on the vehicle speed, resulting in good ride comfort and good posture under virtually all driving conditions of the vehicle. It is possible to achieve both control performance and control performance.

In the above-mentioned embodiment, the gains of the calculation formulas in steps 450 and 490 are calculated based on the results of the determination of the driving conditions performed in step 430, but these calculations Set each gain in the equation to a certain constant,
The system is configured to set a gain to each of Pxi, Pgl, and Pold of the expression p in step 520, and adjust the gains of the former two, Pxi and Pgi, based on the determination result of the running condition in step 430. Good too.

Further, the gain of the calculation formula in steps 450 and 490 is set to a certain constant, the target pressure in step 520 is calculated according to P uim P Xi + P gi , and in step 660 Iul-KIL
I I Li+KIwl I vi+ K i
It may be configured to calculate according to bl I bl and adjust the gain K itl based on the result of the determination of the driving conditions performed in step 430.

Further, steps 560-620 are not essential steps for the present invention, and therefore these steps may be omitted. In that case, the target current warb Riw in the equation of step 630 may be 0, and 1Eivl≦Ei
When vl (constant), it may be set to E1cy0.

Further, the horizontal axes of the graphs shown in FIGS. 19 and 21 are lateral acceleration, but these horizontal axes may also be yaw-1-, and the graph shown in FIG. 19 is the steering angle. It may also be replaced with a three-dimensional map using vehicle speed as a parameter. Furthermore, although the horizontal axis of the graph shown in FIG. 20 is the steering angular velocity, this horizontal axis may also be the rate of change of the lateral acceleration or the rate of change of the yaw rate.

Although the present invention has been described in detail with respect to specific embodiments above, the present invention is not limited to such embodiments, and various other embodiments are possible within the scope of the present invention. This will be clear to those skilled in the art.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram showing a fluid circuit of one embodiment of a hydraulic suspension according to the present invention, FIG. 2 is a block diagram showing an electric control device of the embodiment shown in FIG. 1,
FIG. 3 is a flowchart showing the control flow achieved by the electric control device shown in FIG. 2, and FIGS.
The diagrams show when the hydraulic suspension starts operating,
Normal operation stop at 11 o'clock, operation stop in abnormal situation l-
Figure 7 is a graph showing a map used when calculating the current 1b supplied to the bypass valve when the pressure Pi in the working fluid chamber of each actuator and the current 11)i supplied to each pressure alIt control valve. Graph showing the relationship between
8B are flowcharts showing the active calculation routine performed in step 150 of the flowchart shown in FIG. 3, and FIG. 9 is a flowchart showing the driving conditions performed in step 430 of the flowchart shown in FIG. 8A. Flowchart showing the determination routine, FIG. 10 is 8A
A flowchart showing a routine for displacement feedback control gain calculation performed in step 440 of the flowchart shown in FIG. 11, and FIG. 12 is a graph showing the relationship between the vehicle speed V and the 11-mark displacement amount Rxh, and FIG. 13 is a graph showing the relationship between the longitudinal acceleration Ga and 1.1
14 is a graph showing the relationship between lateral acceleration G1 and F11 standard deviation mRxr, and FIG. 15 is a graph showing the relationship between longitudinal acceleration Ga and target pressure Pga. The graph shown in Fig. 16 shows the lateral acceleration G1 and de1
FIG. 17 is a graph showing the relationship between vehicle speed V, FIG. 18 is a graph showing the relationship between working fluid temperature T and correction coefficient Ki, and FIG. 20 is a graph showing the relationship between the lateral acceleration Gl and the first current warp control amount R1wl, FIG. 20 is a graph showing the relationship between the steering angular velocity θ and the second current warp control amount Riw2, and FIG. The figure is a graph showing the relationship between the lateral acceleration 61, the load distribution ratio between the front and rear wheels, and the third current warb control amount Riv3. 25 is a graph showing the relationship between the absolute value of the steering angular velocity or the absolute value of the rate of change of lateral acceleration and each gain component, and FIG. 26 is a graph showing the relationship between the rate of change of the throttle opening. or a graph showing the relationship between the rate of change in longitudinal acceleration and each gain component; FIG. 27 is a graph showing the relationship between the rate of change in longitudinal acceleration and each gain component;
Figures 34 to 34 are graphs showing the relationship between vehicle speed ■ and correction coefficients for each gain component, and Figures 35 and 36 are graphs showing the relationship between rough road characteristics ff1Xa or small warp fuExv and each gain component. 37 is a graph showing the relationship between the absolute value of the steering angular velocity or the absolute value of the moxibustion rate of lateral acceleration and each gain component, and FIG. A graph showing the relationship between the rate of change and each gain component, FIG. 39 is a graph showing the relationship between the rate of change in longitudinal acceleration and each gain component, and FIGS. 40 to 45 show the relationship between the vehicle speed V and each gain. It is a graph showing the relationship between complementary 1F coefficients and components. 11 R, IP+,, I R1? , I RL...actuator, 2PR, 2P+7.2RI? ,2R1,
... Working fluid chamber, 4... Reserve tank, 6...
・Pump, 8... Filter, 10... Suction channel, 1
2...Drain channel, 14...Engine. 16... Rotation speed sensor, 18... High pressure flow path, 20...
・Reverse 1 valve, 22 ・Atenniator, 24.26・
...Accumulator, 32.34.36.38...Pressure control valve, 40.42.44.46...Switching 1-control valve, 48...Low pressure flow path, 52...Fixed throttle 154
...Variable aperture. 56... Connection flow path, 58... Solenoid, 66.6
8.70...Fixed aperture, 72.74.76...i+
J-shaped aperture. 78.80,82... Solenoid, 84.86.88
... Connection channel, 110-118... Drain channel, 1
20...Filter, 124-130...Aperture, 13
2~138...Accumulator, 144F'l? ,1
441 L1144RR, 144RL...Vehicle height sensor, 50-156...Shutoff valve, 166-172...Relief valve, 174...Oil cooler, 176...Filter, 18o...Relief valve, 182... Filter, 184... Throttle, 186... Solenoid shut-off valve, 19
0...Solenoid, 192...Opening/closing valve, 196...
・Bypass valve, 197.198.199-r'R, 19
91! +,, 199 RR, 199R1, -... Pressure sensor, 200... Electric control device, 202... Microcomputer, 204... CPU, 206... R
OM, 208...RAM, 210...Input port device, 212...Output port device, 216...IGS
W. 218... EMSW, 220-230... Drive circuit. 232...Display device, 234...Vehicle speed sensor, 236
...Front and rear G sensor, 238...tJ'f G sensor, 240...Steering angle sensor, 242...Throttle opening sensor, 244...ID5W, 246...BK
SW, 248...Medium/high setting switch patent applicant: Toyota Motor Corporation representative
Attorney Patent Attorney Roki Akashi Figure Figure Time Figure Figure 8A Figure 8C ■ ↓ Figure 8B Figure 10 Figure 11 Figure 12 Figure 13 Figure 14 Figure 15 Figure ga Figure gl Figure iw1 Figure Figure iw2 iw3 Figure 22 Figure a Figure 23 Figure a Figure 24 Figure Figure Figure 25 Figure 26 Figure 27 Ga Figure ■ Figure Figure ■ Figure 37 Figure 101 or IGII 38 Figure 39 Figure Ga Figure ■ Figure ■ Figure ■ Figure (Method) Display of the incident 1999 Patent Application No. 132069 2゜Name of the inventionHydraulic suspension 3゜Compensator Relationship with the incident

Claims (1)

[Claims] A fluid pressure actuator disposed between each wheel and the vehicle body, a pressure adjustment means for adjusting the fluid pressure in the actuator, a vehicle height detection means for detecting the vehicle height of a portion corresponding to each wheel, a first control amount based on the vehicle height detected by the vehicle height detection means and a second control amount based on the static support load of the actuator. a control means for controlling the pressure adjustment means, the control means being configured to reduce the first control amount when the vehicle is not turning or accelerating or decelerating.