JPH0741785B2 - Hydraulic suspension - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a suspension of a vehicle such as an automobile, and more particularly to a fluid pressure type suspension.

2. Description of the Related Art As one of fluid pressure type suspensions for vehicles such as automobiles, for example, a fluid pressure actuator arranged between each wheel and a vehicle body, such as a suspension described in JP-A-63-145115, The vehicle has pressure adjusting means for adjusting the fluid pressure in the actuator, vehicle height detecting means for detecting the vehicle height of a portion corresponding to each wheel, and control means for controlling the pressure adjusting means. When a change in height (change in body posture) is not detected, the fluid pressure in each actuator is controlled to be an offset pressure corresponding to the static supporting load, and the change in vehicle height is detected by the vehicle height detection means. Conventionally, there has been known a fluid pressure type suspension configured to output a command value corresponding to the change in vehicle height to a pressure adjusting means to suppress a change in posture of a vehicle body.

According to such a suspension, when the vehicle height does not substantially change as in the case where the vehicle travels straight on a good road, the supporting load of the actuator is controlled to the static supporting load, so that the vehicle rides on the vehicle. Comfort is ensured, the posture of the vehicle body changes when the vehicle turns or accelerates / decelerates, and if this changes the vehicle height of the part corresponding to each wheel, the control amount based on the change in the vehicle height By controlling the fluid pressure in the actuator to be increased or decreased from the offset pressure, the change in vehicle height is suppressed or reduced, which suppresses the change in posture of the vehicle body.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention However, in the fluid pressure type suspension as described above, even when the vehicle travels on a bad road, the pressure adjusting means is controlled by the control amount based on the change in the vehicle height due to the unevenness of the road surface. The fluid pressure in the actuator is controlled to increase or decrease from the offset pressure.However, if the vehicle height changes significantly, the fluid pressure in the actuator changes due to the response delay of the control system or the fluid system delay. Since the vehicle does not follow, there is a problem that the riding comfort of the vehicle is poor when the vehicle travels on a rough road, as compared with the case of the conventional general passive suspension. Further, if the control gain for the pressure adjusting means based on the change of the vehicle height is reduced in order to improve the riding comfort of the vehicle when traveling on a bad road, it is possible to sufficiently change the posture of the vehicle body when the vehicle travels on a good road. There is a problem that it cannot be suppressed.

The present invention provides control of ride comfort, that is, control that constantly adjusts the fluid pressure in the actuator to an offset pressure that corresponds to its static support load regardless of the stroke of each wheel, and vehicle body attitude control, that is, vehicle height control. Based on the change, the contribution of the control that adjusts the fluid pressure in the actuator to reduce the change in vehicle height is changed according to the road surface condition. An object of the present invention is to provide an improved fluid pressure type suspension capable of improving riding comfort during traveling.

Means for Solving the Problems According to the present invention, the object as described above is arranged between each wheel and the vehicle body and the fluid pressure inside is adjusted to increase or decrease the supporting load and increase or decrease the vehicle height. A fluid pressure actuator,
Pressure adjusting means for adjusting the fluid pressure in the actuator, vehicle height detecting means for detecting a vehicle height of a portion corresponding to each wheel, road surface state determining means for determining a road surface state, and detection by the vehicle height detecting means The road surface condition determining means is a road surface condition determining means for controlling the pressure adjusting means based on a first controlled variable based on the vehicle height and a second controlled variable based on a static supporting load of the actuator. Is configured so that the larger the size of the unevenness is, the worse the road surface condition is, and the control means reduces the gain of the control based on the first control amount when the road surface condition is bad than when the road surface condition is good. Achieved by a constructed hydraulic suspension.

According to the above-described configuration, the road surface condition determining means is configured to determine that the road surface condition is poor as the size of the unevenness of the road surface is large, and based on the vehicle height detected by the vehicle height detecting means. The control means for controlling the pressure adjusting means on the basis of the first control amount and the second control amount based on the static supporting load of the actuator has a first control amount when the road surface condition is poorer than when the road surface condition is good. Since it is configured to reduce the gain of control based on, the degree of contribution of ride comfort control and posture control is appropriately changed according to the road surface condition, and thereby the posture control performance during running on a good road is not impaired. It is possible to improve riding comfort when traveling on a rough road.

That is, when the vehicle travels on a good road, the control gain based on the first control amount is maintained at a predetermined value without being reduced. Since a substantial change in the vehicle height is not detected when the vehicle goes straight, the first control amount itself based on the vehicle height is small, and each actuator has a predetermined control amount corresponding to the second control amount mainly based on the static supporting load. The offset pressure is maintained, which ensures good riding comfort, and when the vehicle is turning or accelerating / decelerating, the first control amount and static support load of the actuator based on changes in vehicle height due to turning or acceleration / deceleration. Since the supporting load of each actuator is controlled based on the second control amount based on, the vehicle height is controlled so as to cancel the change in vehicle height caused by turning or acceleration / deceleration, and thereby the posture change of the vehicle body. Are virtually eliminated.

Further, when the vehicle travels on a rough road, the control gain based on the first control amount is reduced. When the vehicle goes straight, changes in the vehicle height due to the unevenness of the road surface are detected by the vehicle height detecting means, and when the vehicle is turning or accelerating / decelerating, the changes in the vehicle height due to the unevenness of the road surface and the turning or acceleration / deceleration of the vehicle are detected. Although detected by the high detection means, the control gain for the first controlled variable based on the change in vehicle height is reduced, so that the fluid pressure in each actuator is mainly controlled by the second control amount based on the static supporting load. It is controlled to a pressure close to a predetermined offset pressure based on the amount, and since the fluid pressure type suspension approaches a conventional general passive suspension, the fluid pressure in the actuator is It does not increase or decrease with respect to unevenness, which ensures good ride comfort of the vehicle when driving on rough roads, and is used to supply and discharge the working fluid to and from the actuator. That energy is reduced.

The fluid pressure actuator in the suspension of the present invention may have any structure as long as the support load and the vehicle height can be increased or decreased by adjusting the fluid pressure inside. Further, the road surface condition determining means may be of any structure as long as it can detect irregularities on the road surface on which the vehicle is traveling and determine that the condition is worse as the size of the irregularities on the road surface is larger. It may be configured to judge the road surface condition based on the detected variation in vehicle height, or directly detect the undulation of the road surface like an ultrasonic sensor or infrared sensor and judge the road surface condition based on the detection result. It may have a structure.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

Embodiment FIG. 1 is a schematic configuration diagram showing a fluid circuit of one embodiment of a fluid pressure type suspension according to the present invention. The fluid circuit of the hydraulic suspension shown in the figure has actuators 1FR, 1FL, 1RR, 1RL provided for the right front wheel, left front wheel, right rear wheel, and left rear wheel of the vehicle, which are not shown in the figure, respectively. These actuators have working fluid chambers 2FR, 2FL, 2RR and 2RL, respectively.

Further, in the figure, reference numeral 4 denotes a reserve tank for storing hydraulic oil as a working fluid, and the reserve tank 4 has a suction passage 10 provided with a filter 8 for removing foreign matter on the suction side of the pump 6 from the suction side. It is connected with. Pump 6
The working fluid leaking inside is stored in the reserve tank 4
The drain flow path 12 for collecting is connected to. The pump 6 is rotationally driven by the engine 14, and the rotational speed of the engine 14 is detected by the rotational speed sensor 16.

A high pressure flow path 18 is connected to the discharge side of the pump 6. A check valve 20 which allows only the flow of the working fluid from the pump to each actuator is provided in the middle of the high-pressure flow path 18, and the working fluid discharged from the pump is provided between the pump 6 and the check valve 20. An attenuator 22 is provided which absorbs the pressure pulsation and reduces the pressure change. One end of the front wheel high pressure flow path 18F and the rear wheel high pressure flow path 18R is connected to the high pressure flow path 18, and accumulators 24 and 26 are connected to these high pressure flow paths, respectively. Each of these accumulators is filled with a high-pressure gas to absorb the pressure pulsation of the working fluid and to accumulate the pressure. The high-pressure flow passages 18F and 18R have a high-pressure flow passage 18FR for the right front wheel, a high-pressure flow passage 18FL for the left front wheel, and a high-pressure flow passage for the right rear wheel, respectively.
18RR and one end of the high pressure flow path 18RL for the left rear wheel are connected.
Filters 28FR, 28FL, 28RR, 28RL are provided in the middle of the high pressure flow paths 18FR, 18FL, 18RR, 18RL, and the other ends of these high pressure flow paths are pressure control valves 32, 34, 36, respectively.
38 pilot operated 3-port switching control valves 40, 42,
It is connected to the P ports of 44 and 46.

The pressure control valve 32 includes a switching control valve 40, a flow passage 50 that connects the high pressure flow passage 18FR and the low pressure flow passage 48FR for the right front wheel, and a fixed throttle 52 and a variable throttle 54 provided in the middle of the flow passage. It has become. Low pressure passage 48FR for R port of switching control valve 40
Is connected, and the connection flow path 56 is connected to the A port. The switching control valve 40 is a spool valve that takes in the pressure Pp in the flow passage 50 between the fixed throttle 52 and the variable throttle 54 and the pressure Pa in the connection flow passage 56 as pilot pressure, and the pressure Pp is higher than the pressure Pa. Sometimes it is switched to a switching position 40a that connects and connects the ports P and A, and when the pressures Pp and Pa are equal to each other, it is switched to a switching position 40b that blocks the communication of all ports. When the pressure Pp is lower than the pressure Pa, the ports are switched. It is adapted to switch to a switching position 40c where R and port A are communicatively connected. Further, the variable throttle 54 changes the effective passage cross-sectional area of the throttle by controlling the current supplied to its solenoid 58, and thereby changes the pressure Pp in cooperation with the fixed throttle 52.

Similarly, the pressure control valves 34 to 38 are pilot-operated three-port switching control valves 42, 44, 46 corresponding to the switching control valve 40 of the pressure control valve 32, and the flow channels 60, 62, 62 corresponding to the flow channel 50.
64, fixed diaphragms 66, 68, 70 corresponding to the fixed diaphragm 52, and variable diaphragms 72, 74, 76 corresponding to the variable diaphragm 54. The variable diaphragms 72 to 76 are solenoids 78, 80, 82, respectively. have.

Further, the switching control valves 42, 44, and 46 are configured similarly to the switching control valve 40, and the R ports of the switching control valves 42, 44, and 46 are low-pressure passage 48FL for the left rear wheel, low-pressure passage 48RR for the right rear wheel, and left rear, respectively. One end of the wheel low-pressure flow path 48RL is connected, and one end of each of the connection flow paths 84, 86, 88 is connected to the A port. The switching control valves 42 to 46 are spool valves that take in the pressure Pp in the flow passages 60 to 64 between the corresponding fixed throttle and the variable throttle and the pressure Pa in the corresponding connecting flow passages 84 to 88 as pilot pressures. And when the pressure Pp is higher than the pressure Pa, the switching positions 42a, 44a, 46 for connecting the port P and the port A in communication.
Switching positions 42b, 44b, 46b that switch to a and shut off communication of all ports when pressures Pp and Pa are equal to each other
, And when the pressure Pp is lower than the pressure Pa, the port R
Switching positions 42c, 44c, 46a for connecting the port and port A for communication
It is designed to switch to.

Each actuator, as shown schematically in FIG.
1FR, 1FL, 1RR, 1RL are cylinders 106FR, 106FL,
Working fluid chambers 2FR, 2FL, 2RR, 2 in cooperation with 106RR and 106RL and their corresponding cylinders
It is composed of pistons 108FR, 108FL, 108RR, 108RL that define RL, each connected to a vehicle body not shown in the drawing by a cylinder, and not shown in the drawing by the tip of the rod portion of the piston. It is connected to the suspension arm. Although not shown in the figure, a suspension spring is mounted between the upper seat fixed to the rod portion of the piston and the lower seat fixed to the cylinder.

Cylinder of each actuator 106FR, 106FL, 106R
One ends of drain flow paths 110, 112, 114, and 116 are connected to R and 106RL. The other ends of the drain flow channels 110, 112, 114, 116 are connected to the drain flow channel 118, and the drain flow channel is connected to the reserve tank 4 via the filter 120,
As a result, the working fluid leaking from the working fluid chamber is returned to the reserve tank.

The working fluid chambers 2FR, 2FL, 2RR, 2RL have throttles 124, 1 respectively
Accumulators 132, 134, 136, 1 through 26, 128, 130
38 is connected. Also piston 108FR, 108FL, 108R
Flow paths 140FR, 140FL, 140RR, 140RL for R and 108RL, respectively.
Is provided. These flow passages connect the corresponding flow passages 56, 84 to 88 and the working fluid chambers 2FR, 2FL, 2RR, 2RL in communication with each other, and filters 142FR, 142FL, 142R are provided on the way, respectively.
It has R and 142 RL. Actuators 1FR, 1FL,
At positions close to 1RR and 1RL, vehicle heights HFR, HFL, HRR, HRL and reference vehicle heights HFRa, HFLa of parts corresponding to the wheels are set.
Vehicle height XFR, XFL, XRR, X as deviation from HRRa, HRLa
Vehicle height sensors 144FR, 144FL, 144RR, 144RL for detecting RL are provided.

Thus, each pressure control valve, each actuator, etc. not only increases or decreases the vehicle height at the corresponding position, but also provides a steer characteristic changing means for changing the steer characteristic of the vehicle by controlling the supporting load of the corresponding wheel. I am configuring.

Pilot operated shutoff valves 150, 152, 154, 156 are provided in the middle of the connection flow paths 56, 84 to 88, respectively, and these shutoff valves respectively correspond to the corresponding pressure control valves 40, 42, 44 ,.
When the pressure difference between the pressure in the high pressure flow passages 18FR, 18FL, 18RR, 18RL upstream of 46 and the pressure in the drain flow passages 110, 112, 114, 116 is below a predetermined value, the valve closed state is maintained. It is like this. Further, the portions of the connection flow passages 56, 84 to 88 between the corresponding pressure control valve and the shutoff valve are respectively flow passages 158, 160, 16.
2,164 corresponding pressure control valve flow paths 50, 60, 62, 64
Is connected to the downstream side of the variable throttle. Relief valves 166, 168, 17 are provided in the middle of the flow paths 158-164, respectively.
0, 172 are provided, and these relief valves take in the pressure on the upstream side of the corresponding flow passages 158, 160, 162, 164, that is, the side of the corresponding connection flow passage as a pilot pressure, and When the pressure exceeds a predetermined value, the valve is opened to remove a part of the working fluid in the corresponding connection flow passage 50,
It leads to 60-64.

The shutoff valves 150 to 156 are high pressure flow paths 18FR, 18FL, 18R, respectively.
The valve closed state may be maintained when the differential pressure between the pressure in R and 18RL and the atmospheric pressure is equal to or less than a predetermined value.

The other ends of the low pressure passages 48FR and 48FL 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 one end of the low pressure passage 48R for the rear wheels. . The other ends of the low pressure flow paths 48F and 48R are connected to one end of the low pressure flow path 48 so as to communicate with each other. The low-pressure flow path 48 has an oil cooler 174 in the middle and is connected to the reserve tank 4 at the other end via a filter 176. A portion of the high pressure passage 18 between the check valve 20 and the attenuator 22 is connected to the low pressure passage 48 by a passage 178. A relief valve 180, which is set to a predetermined pressure in advance, is provided in the flow path 178.

In the illustrated embodiment, the high-pressure flow path 18R and the low-pressure flow path 48R are connected to each other by a flow path 188 having a filter 182, a throttle 184, and a normally-closed type flow controllable electromagnetic on-off valve 186 on the way. There is. The solenoid opening / closing valve 186 is configured so that its solenoid 190 is excited and its exciting current is changed to open the valve and adjust the flow rate of the working fluid passing through the valve. 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 on the way. The on-off valve 192 takes in the pressure on both sides of the throttle 184 as pilot pressure, maintains the closed valve 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. Valve open position 192
It is designed to switch to b. Thus, the throttle 184, the solenoid on-off valve 186, and the on-off valve 192 cooperate with each other so that the high pressure passage 18R
And the low-pressure flow path 48R, and thus the high-pressure flow path 18 and the low-pressure flow path 48, are selectively connected to form a bypass valve 196 for controlling the flow rate of the working fluid flowing from the high-pressure flow path to the low-pressure flow path.

Further, in the illustrated embodiment, the high pressure flow path 18R and the low pressure flow path 4
The 8R is provided with pressure sensors 197 and 198, respectively, and these pressure sensors detect the pressure Ps of the working fluid in the high-pressure passage and the pressure Pd of the working fluid in the low-pressure passage, respectively. There is. In addition, the connection channels 56, 84, 86,
88 are pressure sensors 199FR, 199FL, 199RR, 199RL respectively.
Are provided, and the pressures inside the working fluid chambers 2FR, 2FL, 2RR, and 2RL are detected by these pressure sensors, respectively. Further, the reserve tank 4 has a temperature sensor 195 for detecting 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 the electric control device 200 shown in FIG. The electric control device 200 includes a microcomputer 202. The microcomputer 202 may have a general structure as shown in FIG. 2, and includes a central processing unit (CPU) 204 and a read only memory (ROM) 206.
, A random access memory (RAM) 208, 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 has an engine 14
Signal indicating the working fluid temperature T from the temperature sensor 195, signals indicating the pressure Ps in the high pressure passage and pressure Pd in the low pressure passage respectively from the pressure sensors 197 and 198, and the pressure sensor 199FL. , 199FR, 199RL, 199RR, the pressure Pi in the working fluid chambers 2FL, 2FR, 2RL, 2RR (i = 1,
2,3,4) signal, ignition switch (IG
SW) 216 is a signal indicating whether or not the ignition switch is on, and a signal indicating whether or not the ignition switch is on by an emergency switch (EMSW) 218 provided in the passenger compartment and operated by an occupant of the vehicle. , Left front wheel from vehicle height sensors 144FL, 144FR, 144RL, 144RR,
The vehicle height Xi (i = i) of the parts corresponding to the right front wheel, left rear wheel, and right rear wheel
Signals indicating 1, 2, 3, 4) are input respectively.

In the input port device 210, the vehicle speed sensor 234 indicates a vehicle speed V, the longitudinal G (acceleration) sensor indicates a longitudinal acceleration Ga, and the lateral G (acceleration) sensor 248 indicates a lateral acceleration Gl.
, A signal indicating a steering angle θ from a steering angle sensor, a signal indicating a throttle opening θa from a throttle opening sensor 242, a signal indicating whether or not the idle switch is in an on state from an idle switch (IDSW) 244, The brake switch (BKSW) 246 gives a signal indicating whether or not the brake switch is in the ON state, and the vehicle height setting switch 248 gives a signal indicating whether the vehicle height control mode is the high mode or the normal mode. Each is to be input.

The input port device 210 appropriately processes the signal input to it, and the CPU 204 based on the program stored in the ROM 206.
The processed signal is output to the CPU and the RAM 208 in accordance with the instruction. ROM206 is shown in Figure 3 and Figures 8A-8C.
The control flow shown in FIG. 9, FIG. 9 to FIG. 11 and FIG.
It stores the maps shown in FIGS. 7 and 12 to 45. The output port device 212 outputs a control signal to the electromagnetic opening / closing valve 186 via the drive circuit 220 according to the instruction of the CPU 204, and the pressure control valves 32 to 38 via the drive circuits 222 to 228, specifically, the variable throttles 54 and 72, respectively. A control signal is output to the solenoids 58, 78, 80, 82 of the 74, 76, and a control signal is output to the display device 232 via the drive circuit 230.

Next, the operation of the illustrated embodiment will be described with reference to the flow chart shown in FIG.

The control flow shown in FIG. 3 is started by closing the ignition switch 216. Also the third
In the flowchart shown in the figure, the flag Ff relates to whether or not there is a fail in any part of the fluid pressure suspension, and 1 indicates that there is a fail in any part of the fluid pressure suspension. Flag Fe relates to whether or not the engine is in operation, 1 indicates that the engine is in operation, and flag Fp indicates that the pressure Ps of the working fluid in the high-pressure passage is equal to the shutoff valve 150-. 1
It relates to whether or not the threshold value pressure Pc for completely opening the valve 56 has been exceeded or higher, where 1 indicates that the pressure Ps has reached the pressure Pc or higher, and the flag Fs is the pressure control valve. 32-38 standby pressure Pbi (i = 1, 2,
Standby pressure current Ibi (i = 1, 3,
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 is turned on, and then step 20 is proceeded to.

In step 20, the contents stored in the RAM 208 are cleared and all the flags are reset to 0, and then the process 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 temperature T of the working fluid detected by the temperature sensor 195, and pressure sensors 197 and 198, respectively. Pressure in high pressure channel
Ps and a signal indicating the pressure Pd in the low-pressure channel, pressure sensor 199F
Working fluid chamber 2F detected by L, 199FR, 199RL, 199RR
Signal indicating pressure Pi in L, 2FR, 2RL, 2RR, signal indicating whether ignition switch 216 is in ON state, EMS
A signal indicating whether the W218 is in the ON state, the vehicle height sensor 14
A signal indicating the vehicle height Xi detected by 4FL, 144FR, 144RL, 144RR, a signal indicating the vehicle speed V detected by the vehicle speed sensor 234, a longitudinal acceleration Ga detected by the longitudinal G sensor 236.
Signal indicating the lateral acceleration G detected by the lateral G sensor 238
a signal indicating the l, a signal indicating the steering angle θ detected by the steering angle sensor 240, a signal indicating the throttle opening θa detected by the throttle opening sensor 242, a signal indicating whether the IDSW 244 is in the ON state, A signal indicating whether or not the BKSW 246 is in the on state and a signal indicating whether the mode set by the vehicle height setting switch 248 is the high mode or the 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 and the ignition switch is in the on state. When the determination is made, the process proceeds 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, in which the EMSW is not in the on state. When the determination is made, the process proceeds to step 60.

In step 60, it is judged whether or not the flag Ff is 1, and when it is judged that Ff = 1, the routine proceeds to step 220, where it is judged that Ff = 1 is not established. If so, proceed to step 70.

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

The determination as to whether or not the engine is operating may be made by determining as to whether or not the power generation voltage of a generator driven by the engine, which is not shown in the figure, 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 operation of the engine is started to the time when the standby pressure Pbi of the pressure control valves 32 to 38 is set in step 200 described later. The timer for the time Ts is started, and then the process proceeds to step 90. In this case, flag Fe
Is already set to 1, the timer is maintained as it is, and when the timer Ts is already activated, the timer continues counting.

In step 90, the current Ib supplied to the solenoid 190 of the electromagnetic opening / closing valve 186 of the bypass valve 196 is stored in the ROM 206 according to the map corresponding to the graph shown in FIG. 4, according to Ib = Ib + ΔIbs It is calculated, and then the process proceeds to step 100.

In step 100, the electric current Ib calculated in step 90 is applied to the solenoid 190 of the electromagnetic opening / closing valve 186, whereby the bypass valve 196 is driven in the valve closing direction, and then the process proceeds to step 130.

In step 110, the operation of the Ts timer is stopped, and then the process proceeds to step 120. In this case, when the Ts timer is not operated, it is maintained as it is.

At step 120, it is judged if the flag Fe is 1, and if it is judged that Fe = 1, that is, if the engine is stopped after being started, step 220 If it is determined that Fe = 1, that is, the engine has not been started at all, the process proceeds to step 130.

In step 130, the pressure Ps in the high-pressure passage is the threshold value Pc.
If it is determined whether or not the above is true, and if it is determined that Ps ≧ Pc is not established, then the procedure proceeds to step 170, and if it is determined that Ps ≧ Pc is determined, then the procedure proceeds to step 140.

In step 140, the 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 attitude control of the vehicle body, and the steering characteristics, as described in detail later with reference to FIG. By performing active calculation based on the various signals provided, the current Iui supplied to the solenoids 58, 78, 80, 82 of the variable throttles 54, 72 to 76 of each pressure control valve is calculated, and then step 290 is performed. Go to.

In step 170, it is judged whether or not the flag Fp is 1, and it is judged that Fp = 1, that is, the pressure Ps of the working fluid in the high-pressure passage becomes equal to or higher than the threshold pressure Pc. After that, when it is determined that the value is lower than this, the routine proceeds to step 150, where it is determined that Fp = 1 is not established, that is, it is determined that the pressure Ps has never exceeded the threshold pressure Pc. If is performed, the process proceeds to step 180.

In step 180, it is determined whether or not the flag Fs is 1, and when it is determined that Fs = 1, the process proceeds to step 290, and it is determined that Fs = 1 is not established. 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, and it is determined that the time Ts has elapsed. Is performed, the process proceeds to step 200.

In step 200, the operation of the Ts timer is stopped, and the pressure Pi read in step 30 is the standby pressure.
Based on the map corresponding to the graph shown in FIG. 7 stored in the RAM 208 as the Pbi and stored in the ROM 206, the connection flow paths 56, 84 to 88 between the pressure control valves and the shutoff valves.
The pressure of the working fluid inside is the standby pressure Pbi, that is, the working fluid chamber 2F detected by the corresponding pressure sensor.
Variable throttles 72, 54, 7 of pressure control valves 34, 32, 38, 36 in order to bring the pressure substantially equal to the pressure Pi in L, 2FR, 2RL, 2RR.
Current Ibi applied to solenoids 78, 58, 82, 80 of 6, 74
(I = 1, 2, 3, 4) is calculated, and the subsequent step
Proceed to 210.

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

At step 220, based on the map corresponding to the graph shown in FIG.
Current I applied to solenoid 190 of solenoid valve 186
b is calculated by Ib = Ib−ΔIbe, and then the process proceeds to step 230.

In step 230, the electric current Ib calculated in step 220 is applied to the solenoid 190 to drive the bypass valve 196 in the valve opening direction, and then the process proceeds to step 290.

In step 240, it is determined whether or not the timer related to the time Toff from the time when the ignition switch is turned off to the time when the main relay is turned off is activated, and the Toff timer is activated. When it is determined that the Toff timer is not operating, the routine proceeds to step 260, and when it is determined that the Toff timer is not operated, the routine proceeds to step 250.

In step 250, the Toff timer is started,
Then proceed to step 260.

In step 260, based on the map corresponding to the graph shown in FIG.
The current Ib supplied to the solenoid 190 of 186 is calculated according to Ib = Ib−ΔIbo, and then the process proceeds to step 270.

In step 270, the bypass valve 196 is driven in the opening direction by energizing the solenoid 190 of the electromagnetic opening / closing valve 186 with the current Ib calculated in step 260, and then the process proceeds to step 280.

In step 280, it is determined whether or not the time Toff has elapsed. When it is determined that the time Toff has elapsed, the process proceeds to step 350, and it is determined that the time Toff has not elapsed. Is performed, the process proceeds to step 290.

In step 290, it is determined whether or not the current Ib calculated in steps 90, 220 and 260 is the reference value Ibo or more, and when it is determined that Ib ≧ Ibo is not satisfied, The process proceeds to step 320, and when it is determined that Ib ≧ Ibo, the process proceeds to step 300.

In step 300, it is judged whether or not the pressure Ps of the working fluid in the high-pressure flow passage read in step 30 is equal to or higher than the reference value Pso, and it is judged that Ps ≧ Pso is not satisfied. If so, the process proceeds to step 320, and if it is determined that Ps ≧ Pso, the process proceeds to step 310.

In step 310, the current Ibi calculated in step 200 or the current Iui calculated in step 150 is output to the solenoids 58, 78 to 82 of the variable throttles of the pressure control valves. The pressure control valve is driven to control the control pressure, and then the process proceeds to step 320.

In step 320, it is determined whether or not a fail exists in any part of the fluid pressure suspension. When it is determined that the fail does not exist, the process proceeds to step 340 and the fail exists. When it is determined to do so, the process proceeds to step 330.

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

In step 340, the diagnosis process is performed for each part in the fluid pressure type suspension, and when there is an abnormality such as a failure, a code number indicating the place is displayed on the display device 232, and any part is displayed. If there is no abnormality, the process returns to step 30 without displaying the code number on the display, and steps 30 to 340 described above are repeated.

In step 350, the main relay is turned off, which terminates the control flow shown in FIG. 3 and stops energizing the electric control device 200 shown in FIG. It

It should be noted that the pressure control by the bypass valve at the time of starting and stopping the operation described above does not form an essential part of the present invention, and the details of these pressure controls are the same as those of the applicant of the present application. Japanese Patent Application No. 63-307189 and Japanese Patent Application No. 63-
See 307190.

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

First, in step 400, the heave target value Rxh,
The pitch target value Rxp and the roll target value Rxr are calculated based on the maps corresponding to the graphs shown in FIGS. 12 to 14, respectively, and then the process proceeds to step 410.

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

In step 410, the vehicle height X _{1 at the} positions corresponding to the left front wheel, right front wheel, left rear wheel, and right rear wheel read in step 30.
Based on X ₄ to X ₄ , displacement mode conversion is calculated for heave (Xxh), pitch (Xxp), roll (Xxr), and warp (Xxw) according to the following formula, and then the process proceeds to step 420.

_{Xxh = (X 1 + X 2} ) + (X 3 + X 4) Xxp = - (X 1 + X 2) + (X 3 + X 4) Xxr = (X 1 -X 2) + (X 3 -X 4) Xxw = (X ₁ -X ₂₎ - Te is at the (X ₃ -X ₄₎ step 420, performs the operation of the deviation of the displacement modes according to the following equation, the process proceeds to thereafter step 430.

Exh ＝ Rxh－Xxh Exp ＝ Rxp－Xxp Exr ＝ Rxr－Xxr Exw ＝ Rxw－Xxw In this case, Rxw may be 0, or Xxw calculated in step 410 immediately after the start of suspension or the past It may be an average value of Xxw calculated in several cycles. If | Exw | ≦ W ₁ (a positive constant), Exw ＝
It is set to 0.

In step 430, as described later in detail with reference to FIG. 9, the traveling condition of the vehicle is judged, that is, the rough road judgment, the turning judgment, the acceleration judgment, and the deceleration judgment are performed. Go to.

In step 440, based on the judgment result in step 430, the gains Kpj, Kij, Kdj of displacement feedback control (j = xh, x) will be described in detail later with reference to FIG.
p, xr, xw) is calculated, and then the process proceeds to step 450.

In step 450, PID compensation calculation of displacement feedback control is performed according to the following equation, and then step 4
Go to 60.

Cxh = Kpxh · Exh + Kixh · Ixh (n) + Kdxh {Exh (n) -Exh (n-n 1)} Cxp = Kpxp · Exp + Kixp · Ixp (n) + Kdxp {Exp (n) -Exp (n-n 1)} cxr = Kpxr · Exr + Kixr · Ixr (n) + Kdxr {Exr (n) -Exr (n-n 1)} Cxw = Kpxw · Exw + Kixw · Ixw (n) + Kdxw {Exw (n) -Exw (n-n 1)} Note at a above formulas, Ej (n) (j = xh, xp, xr, xw) are the current Ej, Ej (n-n ₁₎ is Ej of n ₁ cycles before. Ij (n) and Ij (n-1) are Ij at the present time and one cycle before, respectively, and Tx is a time constant, and Ij (n) = Ej (n) × Tx + Ij (n-1), and Ijmax is predetermined. As a value, | Ij | ≦ Ijmax. Furthermore, the gains Kpj, Kij, Kdj (j
= Xh, xp, xr, xw) are a proportional constant, an integral constant, and a differential constant, respectively.

In step 460, the inverse transformation of the displacement mode is calculated according to the following equation, and then the process proceeds to step 470.

Px ₁ = 1/4 ・ Kx ₁ (Cxh−Cxp + Cxr + Cxw) Px ₂ = 1/4 · Kx ₂ (Cxh−Cxp−Cxr−Cxw) Px ₃ = 1/4 · Kx ₃ (Cxh + Cxp + Cxr−Cxw) Px ₄ = 1 / 4 · Kx ₄ (Cxh + Cxp−Cxr + Cxw) Kx ₁ , Kx ₂ , Kx ₃ , and Kx ₄ are proportional constants.

In step 470, the target pressures Pga and Pgl are calculated based on the maps corresponding to the graphs shown in FIG. 15 and FIG. 16 in the longitudinal and lateral directions of the vehicle, respectively, and then the process proceeds to step 480. .

In step 480, the gains Kpm and Kdm of the G feedback control are set, as will be described later in detail with reference to FIG.
(M = gp, gr) is calculated, and then the process proceeds to step 490.

In step 490, the pitch (Cgp) is calculated according to the following formula.
And PD of G feedback control for roll (Cgr)
Compensation calculation is performed, and then the process proceeds to step 500.

Cgp = Kpgp · Pga + Kdgp {Pga (n) −Pga (n−n ₁ )} Cgr = Kpgr · Pgl + Kdgr {Pgl (n) −Pgl (n−n ₁ )} In the above equations, Pga (n) And Pgl (n) are the current Pga and Pgl, respectively, and Pga (n−n ₁ ) and Pgl (n−).
n ₁ ) is Pga and Pgl before n ₁ cycles, respectively. Also
Kpgp and Kpgr are proportional constants, and Kdgp and Kdgr are differential constants.

In step 500, the steering angular velocity is calculated according to = θ-θ ', where θ'is the steering angle read in step 30 one cycle before in the flowchart of FIG. 3, and the steering angular velocity and the vehicle speed V are used. Based on the map corresponding to the graph shown in FIG. 17, the rate of change of the predicted lateral G, that is, Is calculated, and then the process proceeds to step 510.

In step 510, the inverse conversion operation in G mode is performed according to the following equation, and then the process proceeds to step 520.

Kg ₁ , Kg ₂ , Kg ₃ , and Kg ₄ are proportional constants, respectively, and K ₁ f
And K ₁ r, K ₂ f, and K ₂ r are constants as distribution gains between the front and rear wheels.

In step 520, based on the pressure Pbi stored in the RAM 208 in step 200 and the result calculated in steps 460 and 510, according to Pui = Pxi + Pgi + Pbi (i = 1, 2, 3, 4), The target control pressure Pui of the pressure control valve is calculated,
Then proceed to step 530.

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

I ₁ = Ku ₁ Pu ₁ + Kh (Psr-Ps) -Kl · Pd-α I ₂ = Ku ₂ Pu ₂ + Kh (Psr-Ps) -Kl · Pd-α I ₃ = Ku ₃ Pu ₃ + Kh (Psr-Ps ) −Kl · Pd I ₄ ＝ Ku ₄ Pu ₄ ＋ Kh (Psr−Ps) −Kl · Pd Note that Ku ₁ , Ku ₂ , Ku ₃ , Ku ₄ , Kh, and Kl are proportional constants, and α is between the front and rear wheels. It is a correction constant, and Psr is a reference pressure in the high-pressure flow path.

In step 540, the temperature correction coefficient Kt is calculated based on the temperature T of the working fluid read in step 30 and the map corresponding to the graph shown in FIG. 18, and Iti-Kt · Ii ( i = 1, 2, 3, 4) and the target current 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) according to Iw = (It ₁ −It ₂ ) − (It ₃ −It ₄ ).
Is calculated, and then the process proceeds to step 560.

In step 560, the first current warp control amount Riw ₁ is calculated based on the map corresponding to the graph shown in FIG. 19, and then the process proceeds to step 570.

At step 570, the second current warp control amount Riw ₂ is calculated based on the map corresponding to the graph shown in FIG. 20, and then the routine proceeds to step 580.

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

Wf = Kif (Iu ₁ + Iu ₂ ) + 2Ksf · Xsf In the above equation, Kif is a proportional constant, and Iu ₁ and Iu ₂ are 1
It is the final target current for the left front wheel and the right front wheel calculated in step 660 before the cycle, Ksf is the average value of the spring constants of the suspension springs of the left and right front wheels,
Xsf is the average value of the vehicle heights X ₁ and X ₂ of the left and right front wheels.

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

Wr = Kir (Iu ₃ + Iu ₄ ) + 2Ksr · Xsr In the above equation, Kir is a proportional constant, and Iu ₃ and Iu ₄ are 1
It is the final target current for the left rear wheel and the right rear wheel calculated in step 660 before the cycle, Ksr is the average value of the spring constants of the suspension springs of the left and right front wheels,
Xsr is the average value of the vehicle heights X ₃ and X ₄ of the left and right rear wheels.

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

In step 610, the third current warp control amount Riw ₃ is calculated based on the map corresponding to the graph shown in FIG. 21, and then the process proceeds to step 620.

In step 620, step 560 according to the following equation,
The total of the current warp control amounts calculated in 570 and 610 is calculated, and then the process proceeds to step 630.

Riw = Kw ₁ · Riw ₁ + Kw ₂ · Riw ₂ + Kw ₃ · Riw ₃ Kw ₁ , Kw ₂ and Kw ₃ are proportional constants.

In step 630, the deviation of the current warp is calculated according to the following equation using Riw as the target current warp, and then the process proceeds to step 640.

Eiw = Riw-Iw The target current warp Riw in the above equation may be zero.

In step 640, the current warp target control amount is calculated according to Eiwp = Kiwp-Eiw with Kiwp as a proportional constant, and then the process proceeds to step 650.

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

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

Iui = Iti + Iwi (i = 1, 2, 3, 4) Next, the running condition determination routine performed in step 430 of FIG. 8A will be described with reference to the flowchart shown in FIG.

First, in step 700, a high-pass filter process is performed for several cycles to remove components of a predetermined frequency or less from the vehicle heights X _{1 to} X ₄ read in step 30, and then to step 710. move on.

Te is At a step 710, the effective value of the vibration component _{1 '~ 4'} is calculated by the RMS processing on height _1-4 which is high-pass filtering is performed, the process proceeds to thereafter step 720.

In step 710, the rough road characteristic value Xa is calculated according to Xa = ₁ '+ ₂ ' + ₃ '+ ₄ ', and then step 73 is executed.
Go to 0. The larger Xa, the greater the degree of bad road.

In step 730, it is determined whether or not the rough road characteristic value Xa exceeds the predetermined value Cx. If it is determined that Xa> Cx is not established, the process proceeds to step 750 and Xa> Cx is established. If it is determined that there is, the process proceeds to step 740.

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

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

Thus, in steps 700 to 750, it is determined whether the vehicle is running on a bad road, and if the vehicle is running on a bad road, the flag Fx is set to 1 and the vehicle is bad. The flag Fx is set to 0 when the vehicle is not traveling on the road.

In step 760, the absolute value of the steering angular velocity is the predetermined value C
whether the determination exceeds the l ₁ is performed, the process proceeds to step 790 when the determination of the effect that ||> Cl ₁ were made,
If it is determined that ||> Cl ₁ is not satisfied, the process proceeds to step 770.

In step 770, the absolute value of the lateral G change rate is the predetermined value C.
If it is determined whether or not it exceeds l ₂ , and if it is determined that | l |> Cl _2, it proceeds to step 790.
When it is determined that | l |> Cl ₂ is not established, the routine proceeds to step 780.

In step 780, it is determined whether or not the absolute value of the lateral G exceeds the predetermined value Cl ₃ , and if it is determined that | Gl |> Cl ₃ , the process proceeds to step 790. When it is determined that | Gl |> Cl ₃ is not established, the process proceeds to step 800.

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

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

Thus, in steps 760 to 800, it is determined whether the vehicle is turning, and if the vehicle is turning, the flag Fl is set to 1, and if the vehicle is not turning, The flag Fl is set to 0.

In step 810, it is determined whether or not the idle switch (IDSW) is off. If it is determined that the IDSW is not off, the process proceeds to step 860, and it is determined that the IDSW is off. When the determination is made, the process proceeds to step 820.

In step 820, it is judged whether or not the rate of change a of the throttle opening exceeds a predetermined value Ca ₁ , and a> C
If it is determined that a ₁ is satisfied, the process proceeds to step 850, and if it is determined that a> Ca ₁ is not satisfied, the process proceeds to step 830.

In step 830, the change rate a between the front and rear G is a predetermined value Ca ₂
If it is determined whether or not a> Ca ₂ , the process proceeds to step 850.
If it is determined that a> Ca ₂ is not satisfied, step 8
Proceed to 40.

In step 840, it is determined whether or not the front-rear G exceeds a predetermined value Ca ₃ , and if it is determined that Ga> Ca ₃ , the process proceeds to step 850, and if Ga> Ca ₃ , If it is determined that there is not, the process proceeds to step 860.

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

In step 860, the acceleration determination flag Fa is reset to 0, and then the process 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, Flag Fa is set to zero.

In step 870, it is determined whether or not the brake switch (BKSW) is in the on state, and when it is determined that the BKSW is in the on state, the process proceeds to step 890.
When it is determined that the DSW is not in the on state, the process proceeds to step 880.

In step 880, it is determined whether or not the IDSW is in the on state, and when it is determined that the IDSW is not in the on state, the process proceeds to step 920, in which the IDSW is in the on state. When the determination is made, the process proceeds to step 890.

In step 890, the change rate a between the front and rear G is a predetermined value −C.
It is determined whether or not it is less than b ₁ , and when it is determined that a <−Cb _1, it proceeds to step 910,
If it is determined that a <−Cb ₁ is not established, the process proceeds to step 900.

In step 900, it is determined whether or not the front-rear G (Ga) is less than the predetermined value −Cb ₂ , and when it is determined that Ga <−Cb ₂ is not satisfied, the process proceeds to step 920. Ga <−Cb ₂
When it is determined that the value is, the process proceeds to step 910.

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

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

Thus, in steps 870 to 920, it is determined whether or not the vehicle is in the decelerating state. If the vehicle is in the decelerating state, the flag Fb is set to 1 and if the vehicle is not in the decelerating state. Flag Fb is set to 0.

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

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

In step 1010, the gain component XKpxh, XKpxp, XKpxr, XKpxw I term of the gain of the P term (proportional term) in the equation of the operation executed in step 450 of FIG. 8A ( Rough road gain components XKixh, XKixp, XKixr, and XKixw of gain of integral term) Rough road gain components XKdxh, XKdxp, XKdxr, and XKdxw of gain of D term (differential term) are shown in FIG. 22, FIG. 23, and FIG. Calculated based on the map corresponding to the graph shown in Figure 24, and then step 10
Proceed to 30.

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

In step 1030, it is determined whether or not the turning determination flag Fl is 1, and when it is determined that the flag Fl is not 1, the process proceeds to step 1050, and the flag Fl is 1 When the determination is made, the process proceeds to step 1040.

In 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 in step 450 of FIG. 8A is calculated. Swing gain component LKpxh, LKpxp, LKpxr, LKpxw Swing gain component of gain of I term (integral term) LKixh, LKixp, LKixr, LKixw Swing gain component of gain of D term (differential term) LKdxh, LKdxp, LKdxr, LKdxw is calculated, and then the process proceeds to step 1060.

In step 1050, the turning gain component is set to 0, and then the process proceeds to step 1060.

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

In 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 in step 450 of FIG. 8A is calculated. Acceleration gain component AKpxh, AKpxp, AKpxr, AKpxw I term (integration term) gain acceleration gain component AKixh, AKixp, AKixr, AKixw D term (differential term) gain acceleration gain component AKdxh, AKdxp, AKdxr, AKdxw is calculated, and then the process proceeds to step 1090.

In step 1080, the acceleration gain component is set to 0, and then the process proceeds to step 1090.

In step 1090, it is determined whether or not the acceleration determination flag Fb is 1, and when it is determined that the flag Fb is not 1, the process proceeds to step 1110 and the flag Fb is 1 When the determination is made, the process proceeds to step 1100.

In step 1100, based on the map corresponding to the graph shown in FIG. 27, the gain of P term (proportional term) in the arithmetic expression of the operation executed in step 450 of FIG. 8A is calculated. Deceleration gain component BKpxh, BKpxp, BKpxr, BKpxw I term (integration term) gain deceleration gain component BKixh, BKixp, BKixr, BKixw D term (differential term) gain deceleration gain component BKdxh, Bdxp, Bdxr, Bdxw is calculated, and then the process proceeds to step 1120.

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

In step 1120, steps 110, 1040, 107 are performed based on the map corresponding to the graphs shown in FIGS. 28 to 34.
The correction coefficients PXKpj, PXKij, PXKdj PLKpj, PLKij, PLKdj PAKpj, PAKij, PAKdj PBKpj, PBKij, PBKdj (j = xh, xp, xr, xw) for each gain component calculated at 0, 1100 are calculated, Then proceed to step 1130.

In step 1130, steps 1010, 1040, 1070, 11
Based on each gain component calculated in 00 and the correction coefficient calculated in step 1120, the displacement feedback control gain according to the following formula, that is, the calculation formula of the calculation executed in step 450 of FIG. 8A. , P term, I term, D
The gains Kpj, Kij, Kdj (j = xh, xp, xr, xw) of the terms are set by being calculated according to the following equations, and then the process proceeds to step 450 in FIG. 8A.

Kpj = PXKpj (-XKpj) + PLKpj · LKpj + PAKpj · AKpj + PBKpj · BKpj + Cpj Kij = PXKij (-XKij) + PLKij · LKij + PAKij · AKij + PBKij · BKij + PAKij · BKdj + PLKij · + PKij · + PKij · + PKij · + PKij · + PKdj · + PKij · + PKij xp, xr, xw) (Cpj, Cij, Cdj are constants) Next, the calculation routine of the G feedback control gain performed in step 480 of FIG. 8B will be described with reference to the flowchart of FIG.

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

In step 1210, the rough road gain components XKpgp and XKpgr D terms (differential terms) of the gain of P term (proportional term) in the arithmetic expression executed in step 490 of FIG. 8B are set. The rough road gain components XKdgp and XKdgr are calculated based on the maps corresponding to the graphs shown in FIGS. 35 and 36, respectively, and then the process proceeds to step 1230.

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

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

In 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 in step 450 of FIG. 8A is calculated. Turning gain components LKpgp, LKpgr The turning gain components LKdgp, LKdgr of the gain of the D term (differential term) are calculated, and then the process proceeds to step 1260.

In step 1250, the turning gain component is set to 0, and then the process proceeds to step 1260.

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

In step 1270, based on the map corresponding to the graph shown in FIG. 38, the gain of P term (proportional term) in the arithmetic expression of the operation executed in step 490 of FIG. 8B is calculated. Acceleration gain components AKpgp, AKpgr Acceleration gain components AKdgp, AKdgr of the gain of the D term (differential term) are calculated, and then the process proceeds to step 1290.

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

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

In 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 in step 490 of FIG. 8B is calculated. Deceleration gain components BKpgp, BKpgr Deceleration gain components BKdgp, BKdgr of the gain of the D term (differential term) are calculated, and then the process proceeds to step 1320.

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

In step 1320, based on the map corresponding to the graphs shown in FIGS. 40 to 45, steps 120, 1240 and 127 are executed.
The correction coefficients PXKpgp, PXKpgr PLKpgp, PLKpgr PAKpgp, PAKpgr PBKpgp, PBKpgr for each gain component calculated at 0 and 1300 are calculated, and then the process proceeds to step 1330.

In step 1330, steps 1210, 1240, 1270, 13
Based on each gain component calculated in 00 and the correction coefficient calculated in step 1320, the G feedback control gain is calculated according to the following formula, that is, the calculation formula of the calculation executed in step 490 of FIG. 8B. Gain of each P term of Kpg
The gains Kdgp and Kdgr of p and Kpgr and the D term are set by being calculated according to the following equations, and then the process proceeds to step 490 in FIG. 8B.

Kpgp = PXKpgp (-XKpgp) + PLKpgp · LKpgp + PAKpgp · AKpgp + PBKpgp · BKpgp + Cpgp Kpgr = PXKpgr (-XKpgr) + PLKpgr · LKpgr + PAKpgr · AKpgr + PBKpgr · BKpgr + Cpgr Kdgp = PXKdgp (-XKdgp) + PLKdgp · LKdgp + PAKdgp · AKdgp + PBKdgp · BKdgp + Cdgp Kdgr = PXKdgr (- (XKdgr) + PLKdgr / LKdgr + PAKdgr / AKdgr + PBKdgr / BKdgr + Cdgr (Cpgp, Cpgr, Cdgp, Cdgr are constants) In the above-described embodiment, the P, I, and D terms of the equations in steps 450 and 490 are used. The gain is calculated by each individual map, and the gain of each mode such as heave is calculated by the same map for the same term, but these maps are set individually for each mode. May be. Also, 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.

Thus, according to this embodiment, in steps 400 to 530, calculations for controlling the ride comfort of the vehicle and the attitude control of the vehicle body are performed according to the present invention, and in steps 550 to 650, the steering characteristics are controlled. Is calculated.

As described above, in step 520, the pressure Pxi corresponding to the first control amount based on the vehicle height Xi, the pressure Pbi corresponding to the second control amount based on the static supporting load of each actuator, and the vehicle body The target pressure Pui is calculated as the sum of the pressure Pgi corresponding to the third control amount based on the acceleration, and the current Iti for ride comfort control and attitude control and the current Iwi for steer characteristic control corresponding to this target pressure are calculated. As a sum, the final target current Iui is calculated in step 660, and the control pressure of each pressure control valve, and thus the pressure in the working fluid chamber of each actuator, is controlled based on this final target current.

Further, in steps 700 to 750, it is determined whether or not the unevenness of the road surface is large and the road surface is a bad road, and in these steps it is determined that the road surface is a bad road. ,
In step 1010, a bad road gain component, which is larger as the road surface condition is worse, is calculated, and in step 1130, the bad road gain component is used as a negative coefficient. Kpj, Kij, and Kdj are calculated to be small values.
The control amount based on Xi is reduced.

Therefore, the degree of contribution of the ride comfort control and the posture control, particularly the degree of contribution of the posture control in comparison with the ride comfort control, is appropriately changed according to the road surface condition so that it becomes smaller as the road surface condition becomes worse. It is possible to improve the riding comfort when traveling on a bad road without deteriorating the good attitude control performance at the time.

For example, when the vehicle travels on a good road, the displacement feedback control gains Kpj, Kij, and Kdj are calculated to be relatively large values, but when the vehicle goes straight, a substantial change in vehicle height is not detected. The pressures in the working fluid chambers are substantially maintained at the corresponding standby pressures Pbi, which ensures good riding comfort, and when the vehicle is turning or accelerating / decelerating, the first controlled variable based on the change in vehicle height and The pressure in the working fluid chamber of each actuator is controlled based on the second control amount based on the standby pressure of the actuator and the third control amount based on the acceleration of the vehicle body, which effectively suppresses the posture change of the vehicle body. It

Further, when the vehicle travels on a bad road, the vehicle height sensor detects a change in vehicle height due to the unevenness of the road surface when the vehicle goes straight, and when the vehicle is turning or accelerating / decelerating, the unevenness of the road surface and the turning of the vehicle are detected. A change in vehicle height due to acceleration / deceleration is detected by the vehicle height sensor, but the displacement feedback control gain Kp
By reducing j, Kij, and Kdj to small values, the first controlled variable based on changes in vehicle height is reduced, so that the pressure inside the working fluid chamber of each actuator is mainly controlled by the second and third controlled variables. On the basis of each of the above, the standby pressure is controlled substantially, which ensures a good riding comfort of the vehicle.

Further, in the above-described embodiment, it is determined whether the vehicle is in a turning, accelerating or decelerating state, not only on a bad road as a traveling condition of the vehicle, but also the first control amount is adjusted depending on the determination result. In addition, since the first control amount is adjusted depending on the vehicle speed as well, it is possible to achieve both good riding comfort and good attitude control performance under virtually all driving conditions of the vehicle.

Further, according to the above-described embodiment, not only the control based on the vehicle height Xi, that is, the displacement feedback control, but also the control based on the pressure Pgi corresponding to the third control amount, that is, the acceleration feedback control, is performed. It is possible to suppress a transient posture change at the time of acceleration or deceleration with good responsiveness.

In the above embodiment, the gains of the arithmetic expressions in steps 450 and 490 are calculated on the basis of the judgment result of the running condition performed in step 430. Set each gain of
A gain may be set for each of Pxi, Pgi, and Pbi of the arithmetic expression in 520, and the gains of Pxi and Pgi may be adjusted based on the determination result of the traveling condition in step 430.

In addition, the gain of the calculation formula in steps 450 and 490 is set to a constant value, the target pressure in step 520 is calculated according to Pui = Pxi + Pgi, and in step 660, according to Iui = Kiti / Iti + Kiwi / Iwi + Kibi / Ibi. The gain Kiti may be calculated and adjusted based on the determination result of the traveling condition performed in step 430.

Further, the standby pressure Pb corresponding to the second control amount of the present invention
i may be calculated in an arbitrary manner as a shared load of each actuator of each wheel, and may be calculated based on a map corresponding to the graph shown in FIG. 46, for example.

Further, steps 560 to 620 are not essential to the present invention, and thus these steps may be omitted. In that case, the target current warp Riw in the arithmetic expression of step 630 may be 0, and when | Eiw | ≦ Eiw ₁ (constant), Eiw = 0 may be set.

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

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

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing a fluid circuit of one embodiment of a fluid pressure type suspension according to the present invention, and FIG. 2 is a block diagram showing an electric control device of the embodiment shown in FIG.
FIG. 3 is a flow chart showing a control flow achieved by the electric control device shown in FIG. 2, and FIGS.
The figure shows the operation of the hydraulic suspension,
FIG. 7 is a graph showing a map used for calculating the current Ib supplied to the bypass valve at the time of normal operation stop and at the time of operation stop in an abnormal situation. FIG. 7 shows the pressure Pi and the pressure Pi in the working fluid chamber of each actuator. Graph showing the relationship between the current Ibi supplied to the pressure control valve, FIGS. 8A to 8C are flowcharts showing a routine of the active calculation performed in step 150 of the flowchart shown in FIG. FIG. 9 is a flow chart showing a routine for judging the traveling condition which is carried out in step 430 of the flow chart shown in FIG. 8A, and FIG. 10 is displacement feedback control which is carried out in step 440 of the flow chart shown in FIG. 8A. FIG. 11 is a flow chart showing the routine of gain calculation, and FIG. 11 is a flow chart of the G feedback control gain calculation performed in step 480 of the flow chart shown in FIG. 8B. Flowchart showing a routine, a graph showing the relationship, FIG. 13 is the longitudinal acceleration Ga and a target displacement between the FIG. 12 the vehicle speed V and the target displacement Rxh
FIG. 14 is a graph showing a relationship between the lateral acceleration Gl and the target displacement amount Rxr, and FIG. 15 is a graph showing a relationship between the longitudinal acceleration Ga and the target pressure Pga. , First
FIG. 6 is a graph showing the relationship between the lateral acceleration Gl and the target pressure Pgl, and FIG. 17 is the change rate of the vehicle speed V and the steering angular velocity and the predicted lateral acceleration. Fig. 18 is a graph showing the relationship between
And FIG. 19 is a graph showing the relationship between the lateral acceleration Gl and the first current warp control amount Riw _1, and FIG. 20 is a graph showing the relationship between the steering angular velocity and the second current. A graph showing the relationship between the warp control amount Riw ₂ and Fig. 21 shows lateral acceleration.
A graph showing the relationship between Gl and the load distribution ratio K between the front and rear wheels and the third current warp control amount Riw ₃ , FIGS. 22 to 24 show the relationship between the rough road characteristic value Xa and each gain component. Fig. 25 is a graph showing the relationship, Fig. 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 the lateral acceleration, and each gain component,
FIG. 26 is a graph showing the relationship between the change rate of the throttle opening or the change rate of longitudinal acceleration and each gain component, and FIG. 27 is a graph showing the relationship between the change rate of longitudinal acceleration and each gain component. 28 to 34 are graphs showing the relationship between the vehicle speed V and the correction coefficient for each gain component, FIGS. 35 and 36.
FIG. 37 is a graph showing the relationship between the rough road characteristic value Xa or the vehicle height warp amount Exw and each gain component, and FIG. 37 is the absolute value of the steering angular velocity or the lateral acceleration change rate and each gain component. FIG. 38 is a graph showing the relationship between the change rate of the throttle opening or the change rate of the longitudinal acceleration and each gain component, and FIG. 39 is a graph showing the relationship between the change rate of the longitudinal acceleration and each gain component. 40 to 45 are graphs showing the relationship between the vehicle speed V and the correction coefficient for each gain component, and FIG. 46 is a graph showing the relationship between the vehicle height Xi and the standby pressure Pbi. It is a graph which shows a relationship. 1FR, 1FL, 1RR, 1RL ... Actuator, 2FR, 2FL, 2R
R, 2RL …… Working fluid chamber, 4 …… Reservoir tank, 6 …… Pump, 8 …… Filter, 10 …… Suction passage, 12 …… Drain passage, 14 …… Engine, 16 …… Rotational speed Sensor, 18 ...... High pressure passage, 20 ...... Check valve, 22 ...... Attenuator, 24, 26 ...... Accumulator, 32, 34, 36, 38 ...... Pressure control valve, 40, 42,
44,46 …… Switching control valve, 48 …… Low pressure passage, 52 …… Fixed throttle, 54 …… Variable throttle, 56 …… Connection passage, 58 …… Solenoid,
66, 68, 70 ... Fixed aperture, 72, 74, 76 ... Variable aperture, 78,
80, 82 …… Solenoid, 84,86,88 …… Connection flow path, 110〜
118 …… Drain flow path, 120 …… Filter, 124-130 …… Aperture, 132-138 …… Accumulator, 144FR, 144FL, 144R
R, 144RL …… Vehicle height sensor, 50 to 156 …… Shut-off valve, 166 to 172
…… Relief valve, 174 …… Oil cooler, 176 …… Filter, 180 …… Relief valve, 182 …… Filter, 184 …… Throttle, 1
86 …… solenoid on-off valve, 190 …… solenoid, 192 …… on-off valve, 1
96 …… Bypass valve, 197, 198, 199 …… FR, 199FL, 199R
R, 199RL …… Pressure sensor, 200 …… Electric control device, 202…
… Microcomputer, 204 …… CPU, 206 …… ROM, 208…
… RAM, 210 …… input port device, 212 …… output port device,
216 …… IGSW, 218 …… EMSW, 220〜230 …… Drive circuit, 232…
… Display, 234 …… Vehicle speed sensor, 236 …… Front and rear G sensor, 238
…… Side G sensor, 240 …… Steering angle sensor, 242 …… Throttle opening sensor, 244 …… IDSW, 246 …… BKSW, 248 …… Vehicle height setting switch

Front Page Continuation (72) Inventor Hiroyuki Ikemoto 1 Toyota Town, Toyota City, Aichi Prefecture, Toyota Motor Co., Ltd. (72) Inventor Kaoru Ohashi 1 Toyota Town, Toyota City, Aichi Prefecture, Toyota Motor Co., Ltd. (72) Invention Toshio Yutani, 1 Toyota Town, Toyota City, Aichi Prefecture, Toyota Motor Co., Ltd. (72) Inventor: Kunihito Sato, 1 Toyota Town, Toyota City, Aichi Prefecture, Toyota Motor Co., Ltd. (56) Reference JP 2-60807 (JP, A) JP 61-268509 (JP, A)

Claims (1)

[Claims] 1. A fluid pressure actuator arranged between each wheel and a vehicle body, a pressure adjusting means for adjusting a fluid pressure in the actuator, and a vehicle height for detecting a vehicle height of a portion corresponding to each wheel. A detection means, a road surface state determination means for determining the road surface state, 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. And a control means for controlling the pressure adjusting means, wherein the road surface condition determining means is configured to determine that the road surface condition is worse as the size of the unevenness of the road surface is larger, and the control means is arranged when the road surface condition is poor. A fluid pressure suspension configured to reduce the gain of control based on the first controlled variable as compared to when the road surface condition is good.