JPH02179534A - Fluid pressure type suspension - Google Patents

Abstract

PURPOSE:To improve the drive feeling during the traveling on a rough road by redu cing the control quantity on the basis of the car body accelerating speed 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 car body accelerating speed. 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 pressure control valves 32-38 controlled by a CPU, and an accelerating speed detecting means for detecting the accelerating speed of a vehicle and a traveling state judging means for judging the turn and the acceleration/deceleration speed of the 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 accelerating speed 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 a vehicle body, such as the suspension described in Japanese Patent Application Laid-Open No. 63-145115, and The actuator has a pressure adjustment means for adjusting the fluid pressure in the actuator, an acceleration detection means for detecting acceleration of the vehicle body, and a control means for controlling the pressure adjustment means, and the actual acceleration is detected by the acceleration detection means. When there is no load, the fluid pressure in each actuator is controlled to an offset pressure corresponding to its static support load,
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 acceleration to a pressure adjusting means when a substantial acceleration is detected by an acceleration detecting means.

According to such a suspension, when there is substantially no acceleration of the vehicle body, such as when the vehicle travels straight ahead at a substantially constant speed on a good road, the supporting load of the actuator is equal to the static supporting load. This control ensures the ride comfort of the vehicle, and when the vehicle body accelerates when the vehicle turns or accelerates or decelerates, and the posture of the vehicle body changes, the fluid in the actuator is adjusted based on the control amount based on the change in vehicle height. By controlling the pressure to increase or decrease relative to the offset pressure, changes in vehicle height are suppressed or reduced, thereby suppressing changes in the posture 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 crab A is controlled by a control amount based on the acceleration of the vehicle body caused by the unevenness of the road surface. Since the attitude of the vehicle body is controlled by controlling the adjustment means and adjusting the fluid pressure within the actuator to increase or decrease from the offset pressure, there is a problem in 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 the acceleration of the vehicle body can sufficiently suppress changes in the posture of the vehicle body when the vehicle turns or accelerates or decelerates. The problem is that it is no longer possible to do so.

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 posture control, that is, vehicle body acceleration control. The degree of contribution of the control that adjusts the fluid pressure in the actuator to reduce changes in vehicle height based on the road surface condition is changed depending on the road surface condition. The purpose of the present invention is to provide an improved hydraulic suspension that can improve ride comfort during vehicle travel.

Means for Solving the Problems According to the present invention, the above-mentioned objects include: a fluid pressure actuator disposed between each wheel and a vehicle body; a pressure adjustment means for adjusting the fluid pressure in the actuator; acceleration detection means for detecting acceleration/deceleration of the vehicle body; driving state determination means for determining turning and acceleration of the vehicle; a first control amount based on the acceleration detected by the acceleration detection means; and static support of the actuator. control means for controlling the pressure H adjustment means based on a second control amount based on the load, and the control means controls the first control amount when the vehicle is not turning or accelerating or decelerating. This is accomplished by a hydraulic suspension configured to reduce

Effects and Effects of the Invention According to the configuration as described above, the pressure is controlled based on the first control amount based on the acceleration of the vehicle body detected by the acceleration detection means and the second control amount based on the static support load of the seven cutuators. Since the control means for controlling the adjustment means is configured to reduce the first control amount when the vehicle is not turning or accelerating or decelerating, the degree of contribution of ride comfort control and attitude control is reduced depending on whether the vehicle is turning or accelerating. By appropriately changing the speed depending on whether or not the vehicle is in a deceleration state, it is possible to improve ride comfort when traveling on a rough road without impairing attitude control performance when traveling on a good road.

That is, when the vehicle turns or accelerates or decelerates, the support load of each actuator is determined based on the first control amount based on the acceleration of the vehicle body due to the turn or acceleration/deceleration, and the second control amount based on the static support load of the actuator. controlled, thereby virtually eliminating changes in vehicle body attitude.

Further, when the vehicle is not turning or accelerating or decelerating, the acceleration of the vehicle body caused by unevenness on the road surface is detected by the acceleration detection means, but the first control amount based on the acceleration of the vehicle body is reduced. As a result, 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 improving the ride comfort of the vehicle when driving on rough roads. is ensured.

The fluid pressure actuator in the present invention may have any structure as long as the supported load and vehicle height can be changed by adjusting the internal pressure. Further, the acceleration detection means may be one that directly detects longitudinal acceleration or lateral acceleration, such as an acceleration sensor, or may be one that indirectly detects and estimates acceleration, such as a steering angle sensor or a vehicle speed sensor. good.

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 11'R, I FL, which are provided corresponding to 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.
IRR and IRL, and each of these actuators has a working fluid chamber 2Pi? , 2PL, 21
7R, 21? It has L.

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.

Also, high pressure channels 18F and 18T? are connected to one ends of a high-pressure flow path 18PR for the right front wheel, a high-pressure flow path 18PL for the left front wheel, a high-pressure flow path 18RR for the right rear wheel, and a high-pressure flow path 18RL for the left rear wheel, respectively. High pressure flow path 18FR.

Filters 28 ['R, 28PL, 28RI? , 28R
The other ends of these high-pressure channels are connected to pilot-operated three-boat switching control valves 40.42.44.46 of pressure control valves 32.34.36.38, respectively.
connected to the port.

The pressure control valve 32 is connected to the switching control valve 40 and the high pressure flow path 18P.
I? and a low-pressure flow path 48FR for the right front wheel, and a fixed throttle 52 and a variable throttle 54 provided in the middle of the flow channel.

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 the When the pressures Pp and Pa are equal to each other, the switching position 40b switches to the switching position 40b, which cuts off communication between all boats when the pressures Pp and Pa are equal to each other.
When the pressure is lower than the pressure Pa, the switch is switched to a switching position 40c that connects the boat R and the boat A 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 48FL for the left rear wheel and a low pressure flow path 48R for the right rear wheel.
One end of the low pressure flow path 48RL for the R and left rear wheels is connected to the A boat, and one end of the connection flow path 84, 86, and 88 is connected to the A boat, respectively. Moreover, each of the switching control valves 42 to 46 has a flow path 60 between a corresponding fixed throttle and a variable throttle.
It is a spool valve that takes in the pressure Pp in ~64 and the pressure Pa in the corresponding connection channels 84~88 as pilot pressure, and when the pressure Pp is higher than the pressure Pa, the port P
Switching positions 42a and 44 that communicate and connect port A with
a, 46a, and switches to switching positions 42b, 44b, 46b where communication between all ports is cut off when pressures Pp and Pa are equal to each other, and when pressure Pp is lower than pressure Pa, ports R and A are communicated. The switching positions 42c, 44c and 146c are connected.

As shown in FIG. 1, each actuator IPR, 11, 11? R and IRL are respectively working fluid chambers 2F1? , 2PL, 2RR, 2! ? Cylinders 106PR, 106PL, 106R1 that define L? ,1
06RL and pistons 10 that fit into the respective corresponding cylinders gPRll 08PL, 108RR, 10
8RL, each connected to the vehicle body (not shown) through a cylinder, and connected to a suspension arm (not shown) at the tip of the rod portion of the piston. Although not shown in the internal explanation, a suspension spring is elastically loaded between an upper seat fixed to the rod portion of the piston and a lower seat fixed to the cylinder.

Also, the cylinders 106FR and 106P of each actuator
L, 106RR, 106RL have drain passages 110
．． 112.114.116 are connected at one end. The other end of the drain channel 110.112.114.116 is connected to a drain channel 118, which is connected to the reserve tank 4 via a filter 120,
This allows the working fluid leaked from the working fluid chamber to be returned to the reserve tank.

Accumulators 132.134.136.138 are connected to the working fluid chambers 2PR, 2PL, 2RR, and 2RL via throttles 124.126.128.130, respectively. Also pistons 108FR, 108PL, 10
8RR and 108RI have flow paths 140PR and 1, respectively.
40PL, 140RR, and 140RL are provided. These channels correspond to channels 56.84 to 8, respectively.
8 and working fluid chambers 2 PR, 2F+, 2 RR.

2RI, and a filter 14 in the middle of each.
It has 2PR, 142FL, 142RR, 142RI. Also, actuators I FR, I PL,
11? At positions close to R and IRL, vehicle height sensors 144PR, 144PL, and 144RR detect vehicle heights XPR, XPL, XRR, and XRL of parts corresponding to each wheel.
, 144RL are 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 serves as a steering characteristic changing means that changes the steering characteristic of the vehicle by controlling the support load of the corresponding wheel. It consists of

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
8 Fl? , 18PI4.18R1? , 18R1, and the pressure in the drain flow path 110.112.114.116 is maintained in a closed state when the differential pressure is less than a predetermined value. Also, connection flow path 56.84~
The portion between the corresponding pressure control valve 88 and the shutoff valve is a portion downstream of the variable throttle of the flow path 50.60.62.64 of the corresponding pressure control valve by the flow path 158.160.162.164, respectively. It is connected in communication. Channel 158~
In the middle of 164, relief valves 166, 168.
170.172 are provided, and these relief valves are connected to corresponding flow paths 158.160.162.16, respectively.
The pressure on the upstream side of 4, that is, the side of the corresponding connection channel, is taken in as a pilot pressure, and when the pilot pressure exceeds a predetermined value, the valve is opened to allow a part of the working fluid in the corresponding connection channel to flow. It is designed to lead to roads 50, 60-64.

In addition, the shutoff valves 150 to 156 are connected to the high pressure flow path 181'R, respectively.
, 18FL, 18RR, and 18RL and the atmospheric pressure may be configured to maintain the valve closed state when the differential pressure between the pressure in the valves 18FL, 18RR, and 18RL and the atmospheric pressure is equal to or less than a predetermined value.

The other ends of the low pressure passages 48PR and 48PL are connected to one end of the low pressure passage 48F for the front wheels, and the other ends of the low pressure passages 48RR and R1 are connected to one end of the low pressure passage 48R for the rear wheels. There is. The other ends of the low pressure channels 48F and 48R are connected to one end of the low pressure channel 48 in communication. The low pressure flow path 48 has an oil cooler 174 in the middle and a filter 17 at the other end.
It is connected to the reserve tank 4 via 6. A portion of the high-pressure flow path 18 between the check valve 20 and the attenuator 22 is connected to the low-pressure flow path 48 through a flow path 178 . A relief valve 180 is provided in the middle of the flow path 178 and is set to a predetermined pressure in advance.

In the illustrated embodiment, the high pressure channel 18R and the low pressure channel 4
8R is a flow path 188 that has a filter 182, a throttle 184, and a normally open electromagnetic on-off valve 186 that can adjust the flow rate.
are connected to each other by. The electromagnetic on-off valve 186 is configured to open by energizing a solenoid 190 and changing its excitation current, and to adjust the flow rate of the working fluid passing through the valve. Also, high pressure flow path 18R
and the low-pressure flow path 48R are connected to each other by a flow path 194 having a pilot-operated on-off valve 192 in the middle. The on-off valve 192 takes in the pressure on both sides of the throttle 184 as a pilot pressure, and maintains the closed position 192a when there is no differential pressure on both sides of the throttle 184, and when the pressure on the high pressure flow path 18R side with respect to the throttle 184 is high. Valve open position rI
1192b. 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, the high pressure channel 18R and the low pressure channel 481? are provided with pressure sensors 197 and 198, respectively, and these pressure sensors detect the pressure PS of the working fluid in the high-pressure flow path and the pressure Pd of the working fluid in the low-pressure flow path, respectively. . In addition, pressure sensors 1 are connected to the connection channels 56, 84, 86, and 88, respectively.
99PR, 199PL, 199RR, and 199RL are provided, and these pressure sensors detect the pressure in the working fluid chambers 2FR, 2PL, 2RR, and 2RL, respectively. 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. The electrical control device 2°O 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, 20g of random access memory (RAM),
It has an input boat device 210 and an output boat device 212, which are connected to each other by a bidirectional common bus 214.

The input boat device 210 includes a signal indicating the 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 F'd in the low-pressure flow path, respectively from 98, pressure sensor 199PI4.1
Working fluid chambers 2PL and 2F'l from 99FR, 199RL, and 199RR, respectively? , 2RL, 2+? A signal indicating the pressure Pi (1-1, 2, 3, 4) in R, a signal indicating whether the ignition switch is in the on state from the ignition switch (IGSW) 216, a signal provided in the small room and transmitted by the vehicle occupant. Emerging engine operated
A signal from the switch (EMSW) 218 indicating whether the switch is in the on state, vehicle height sensor 144FL, 14
4FR.

144RL, 1441? Vehicle height Xf (1-1,
The signals indicating 2, 3, and 4) are manually input.

In addition, the human-powered boat device 210 includes a signal 1= indicating the vehicle speed V from the vehicle speed sensor 234, a signal indicating the longitudinal acceleration Ga 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 steering angle. A signal indicating the steering angle θ from the sensor, a signal indicating the throttle opening θa from the throttle opening sensor 242, and an idle switch (IDSW) 2
44, a signal indicating whether the idle switch is on, a brake switch (BKSW) 246, a signal indicating whether the brake switch is on, and a vehicle height setting switch 248, which controls the vehicle height control. A signal indicating whether the mode is high mode or low mode is inputted.

The human-powered port device 210 processes the human-powered signals as appropriate, and uses the CPU and RAM 208 according to instructions from the CPU 204 based on the block diagram stored in the ROM 206.
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 flowcharts 1 and 11 shown in the figures and the maps shown in FIGS. 4 to 7 and 12 to 45 are stored. In accordance with instructions from the CPU 204, the output boat device 212 outputs a control signal to the electromagnetic on-off valve 186 via a drive circuit 220, and outputs a control signal to the pressure control valves 32-38 via drive circuits 222-228.
More specifically, control signals are output to solenoids 58, 78, and 80 degrees 82 of variable apertures 54, 72, 74, and 76, respectively, and are output to display 232 via 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 Ff' is related to whether or not there is a failure in any part of the fluid pressure suspension, and 1 indicates that there is a failure in any part of the fluid pressure suspension. The flag Fe 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 pressure P that completely opens the shutoff valves 150 to 156
This is related to whether or not you have ever experienced a level higher than c.
, 1 indicates that the pressure Ps has exceeded the pressure Pc, and the flag Fs indicates the standby pressure corresponding to the standby pressure Pb1 (1-1, 2, 3, 4) described later of the pressure control valves 32 to 38. This relates to whether or not 1bi (1-1, 2, 3, 4) is set, and 1 indicates that the standby pressure current is set.

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

In step 20, the contents stored in the RAM 208 are cleared and all flags are reset to 0, and then the process proceeds to step 3.

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 sensors 199PL, 199FR, 199RL,
199R1? Working fluid chamber 2PL, 2 detected by
PR, 2RI□, a signal indicating the pressure PI in 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 sensor 1441'L, 1441 “I?, 1
44RL, 144R1? A signal indicating the vehicle height Xi detected by the vehicle speed sensor 234, a signal indicating the vehicle speed V detected by the vehicle speed sensor 234, a signal indicating the longitudinal acceleration Ga detected by the longitudinal G sensor 236, a 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 signal indicating the steering angle θ detected by the steering angle sensor 240, and a signal indicating the steering angle θ detected by the steering angle sensor 240.
a signal indicating the throttle opening degree θa detected by 42;
A signal indicating whether the ID5W244 is in the on state, B
A signal indicating whether the KSW 246 is on or not 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 Ff is 1. When it is determined that the flag F is -1, the process proceeds to step 220, and it is determined that the flag is not Fr-1. If the process has been performed, 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 Fc is set to 1, and the process from the time when engine operation is started to the time when the standby pressure Pbl of the pressure control valves 32 to 38 is set in step 200, which will be described later. A timer is started for the time Ts, after which step 90 is entered.

In this case, if the flag Fc has already been set to 1, 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 then the process 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 196 in the closing direction, and then the process proceeds to step 130.

In step 110, the operation of the Ts timer is stopped, 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 it is determined that it is Fe-1, that is, it is determined that the engine has been started and then stopped. In some cases, the process proceeds to step 220, and if it is determined that the engine is not Fe-1, that is, the engine has not been started at all, the process proceeds to step 130.

In step 130, it is determined whether or not the pressure PS in the high pressure flow path is equal to or higher than the threshold value Pc. If 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 3o, so that the variable throttle 54 of each pressure control valve.
The current 1u1 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 suppressing pressure Pc. If it is determined that the value has become lower than this after the initial pressure is determined, the process proceeds to step 150, and it is determined that the pressure is not Fp-1, that is, it is determined that the pressure PS has never exceeded the threshold suppression pressure Pc. When this has been performed, the process advances to step 180.

In step 180, it is determined whether the flag FS is 1, and if it is determined that 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 Pbi, and the pressure P1 stored in the ROM 206 as shown in FIG. Based on the map corresponding to the graph, the pressure of the working fluid in the connecting channels 56, 84 to 88 between each pressure control valve and the shutoff valve is determined as the standby pressure P bi, that is, the operating pressure detected by the respective corresponding pressure sensor. Fluid chamber 2PL, 2PR,
Solenoid 78.58.82 of variable restrictor 72.54.76.74 of pressure control valve 34.32.38.36 for a pressure substantially equal to the pressure pt in 2RL, 2RR.
．． The current 1b [(1-1, 2, 3, 4)
is calculated, and then the process 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 Ib to be applied to is calculated by Ib-1b-ΔI be , and the process then 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 a timer related to the time Torr from when the ignition switch is turned off to when the main relay is turned off is activated, and if the T of'f timer is activated. When it is determined that it is activated, step 26
If it is determined that the Toff timer is not activated, the process advances to step 250.

In step 250, the Tofr timer is started, and the process then proceeds to step 260.

In step 260, based on the map corresponding to the graph shown in FIG.
b is calculated according to Ib-1b-ΔIbf', 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.
By doing so, the bypass valve 196 is driven in the valve opening direction, and the process then proceeds to step 280.

In step 280, it is determined whether or not the time Tofl' has elapsed, and when it is determined that the time Torf' has elapsed, the process proceeds to step 350, where the time Tofl' has elapsed.
If it is determined that f'f has not elapsed, the process advances to step 290.

In step 290, step 90.220.26
It is determined whether the current 1b calculated at 0 is greater than the reference value lbo, and Ib≧lb.

If it is determined that Ibo is not true, the process proceeds to step 320, and if it is determined that Il+≧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 Ibl calculated in step 200 or the current 1ui calculated in step 150 is applied to the variable throttle solenoid 58 of each pressure control valve.
78 to 82, each pressure control valve is driven and its control pressure is controlled, and then step 32
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 Ff' is set to 1, and then the process proceeds to step 340.

In step 340, diagnosis processing is performed for each part within 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 a code number indicating the location 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, thereby ending the control flow shown in FIG. 3 and stopping power to the electric control device 200 shown in FIG. Ru.

Note that the above-mentioned pressure control by the bypass valve at the start of operation and at the time of operation stop does not constitute a main part of the present invention, and the details of these pressure controls can be found in the patent 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 400, each heap target value R
xhs Pitch target value RXp and roll target value RX" 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, solid lines and broken lines indicate patterns when the vehicle height control modes set by the vehicle height setting switch are normal mode and high mode, respectively.

In step 410, the heap (lxh
), pitch (XXp), roll (Xxr), warp (X
A displacement mode conversion calculation is performed for XV), and the process then proceeds to step 420.

Xxh-(XI +X2)+(Xl +X
4)X)(p--(Xl +X2) + (Xl
+X4 )Xxr-(XI-X2) +(Xl
-Xa )Xxwm (Xl -X2)
-(Xl X 4 ) 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 xp= Rxp -X xp E xr -Rxr -X xr E xvm RIN/ -X It may be the average value of Xxv calculated in the past several cycles or the average value of Xxv calculated in the past several cycles. Further, when IExv]≦W+ (positive constant), it is set as EXV-0.

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 of the displacement feedback control is set to 9.0, as will be explained in detail later with reference to FIG. )SKij
s Kdj (j-xhx 19% Xr% xv) 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-Kpxh-Exh+KIxh-1xh(n)
+ K dxh (E xh(n) −E xh(n
-n+ )) Cxp= Kpxp @E xp+ K
lxp ・I xp(n) + Kdxp (E
xp(n)-E xp(n-n+)ICxr-K
pxr 11E xr+ K ixr I x
r(n) + Kdxr (E xr(n) −E
xr(n-tB) ICxvm K pxv II
E xw+ K ixv 1 xv(n)+ K
dxw (E xv(n)-E xv(n-nl
)1 In each of the above equations, E j(n) (j= xh,
19% Xr, XV) is the current Ej, and E j(n
-n 1 ) is the EJ n1 cycles ago. Also Ij
(n) and Ij (n-1) are the current (1: and Ij one cycle before, respectively, and TX is the time constant. I j (n) = E j (n) + T X I j (
n-1), and with I jsax as a predetermined value, INI≦
I jmax. Furthermore, the gain Kpm calculated in step 440, Kljx Kdj (j=xh,
x9s Xr%xv) are a proportional constant, an integral constant, and a differential constant, respectively.

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

Px 1-1/4 ・Kx I(Cxh-Cxp+Cx
r+Cxw)PX 2-174 ・Kx 2 (Cxh
-Cxp -Cxr -CXV)Px 3 -1/
4 ・KX 3 (Cxh+Cxp+Cxr-
Cxv) Px a -1/4 ・KX 4
(Cxh+Cxp-Cxr+Cxv)KX I
KX 2 , KX 3 , and KX a are proportionality constants.

In step 470, the longitudinal and lateral directions of the vehicle are determined based on the longitudinal and lateral accelerations, respectively, based on the maps corresponding to the graphs shown in FIGS. 15 and 16 for the longitudinal and lateral directions of the vehicle, respectively. The pressure compensation Pga%Pgl is calculated, and then step 4
Proceed to 80.

In step 480, as will be explained in detail later with reference to FIG. 11, the G feedback control gain Kpm is
, Kdffl(II-gps gr) are calculated, and then 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 ・Pga+Kdg9 1Pg
a(n)-P ga(n-n+)I Cgr-I-Kpgr -Pgl+Kdgr (P
gl(n)-P gl(n-n+)1 In each of the above formulas, p ga(n) and Pgl(n) are the current Pga and Pgl, respectively, and P ga(n
−nl ) and P gl(n−nl ) are each n1
Pga and Pgl before cycling. Also K pgp
and Kpgr are proportionality constants, K dgp and Kdg
r is a differential constant.

In step 500, the steering angular velocity θ is calculated according to θ■θ−θ′, where θ′ is the steering angle read in step 30 one cycle before the flowchart in FIG. Based on the map corresponding to the graph shown in FIG. 17 using the angular velocity and the vehicle speed V, the predicted lateral G tabulation rate, ie, G1, is calculated, and then the process proceeds to step 510.

In step 510, a G-mode inverse transform calculation is performed according to the following equation, and the process then proceeds to step 520.

Pg t -Kg + /4・ (2[' to -Cgp+
・For Cgr+, l' −Gl > Pg 2 =Kg 2 /4 ・(2 r for −Cgp−
-Cgp to one K Otori "miserable Gl) Pg 3-Kg 3/4 ・(2r to Cgp+
1 for Cgr+ r −Gl ) Pga = Kga /4 ・2 for (Cgl)−
r ・Cgr− 1 “ ・Gl) Kg I Kg 2 , Kg j , kg 4 are proportional constants, respectively, and Klr and Kl r , K21
' and 2r 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 Pb stored in 208 and the results calculated in steps 460 and 510, P ui −P
The target control pressure Pui of each pressure control valve is calculated according to xl+Pgl+Pbi(1-1, 2, 3, 4), and the process then proceeds 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.

11-Ku I Pu 1+Kh (100-Ps
)-Kl ・Pd-α 12-Ku2 Pu2 +Kh (100-Ps)
-Kl-Pd-α 13-Ku 3 Pu J+Kh (10O-Ps
)-Kl ・Pd 14- K u 4 P u 4 + K h (1
00-P S ) K1-Pd Ku + Ku 2 , Ku 3 , Ku 4 ,
Kh and K are proportional constants, and α is an extraction pressure constant between the front and rear wheels.

In step 540, the temperature correction coefficient KL is calculated based on the map corresponding to the graph shown in FIG. 18, and the target current is A temperature correction calculation is performed, and the process then proceeds to step 550.

In step 550, Iw - (Ill - IL2) - (IL'3 - IL4)
According to the current warb (amount of twist around the longitudinal axis of the vehicle body)
is calculated, and then the process proceeds to step 560.

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

In step 570, a second current warp control gfJuR is performed based on the map corresponding to the graph shown in FIG.
iv2 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 following formula, and then the process proceeds to step 590.

Wr = Ki('CIu I+Iu 2 ) +2Ks
f11
0, Ksl' is the average value of the spring constants of the suspension springs of the left and right front wheels, and Xsr is the average value of the vehicle heights X1 and K2 of the left and right front wheels. be.

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, Klr is a proportionality constant, and I
uj and 1u4 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 suspension springs of the left and right front wheels, and Xsr is the This is the average value of wheel heights X3 and K4.

In step 600, based on Wr and W' calculated in steps 580 and 590, the load distribution ratio K between the front and rear wheels is calculated according to K=W1'/Wr, and then the process proceeds to step 610. .

In step 610, a third current warp li! is generated based on the map corresponding to the graph shown in FIG. The control amount RIwa is calculated, and the process then proceeds to step 620.

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

Rlv−Kw 1 ・RIvl +Kw 2
-R1v2+Kv3 IIRivJ Note that KwI Kw2 and Kw3 are proportional constants.

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

E1va=R1v-1w Note that the target deviation R1v in the above equation may be zero.

In step 640, the current word processor control cycle is calculated according to E Ivp -Rlvp @E lv, with Kivp being a proportionality constant, and then the process proceeds to step 650.

In step 650, the current warb is inversely transformed according to the following equation, and then the process proceeds to step 660.

Iy H-Eivp /4 1v 2 m-Elvp /4 Iv 3--Elvp /4 Iw 4 mEIvp /4 In step 660, based on the results calculated in steps 540 and 650, according to the following formula A final target current 1ui to be supplied to each pressure control valve is calculated,
Thereafter, the process proceeds to step 290 in FIG.

I ul= I tl+ I vl (l-1, 2, 3, 4) Next, with reference 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 X1 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 x1 to X4 to calculate the effective value Y+-¥4 of the vibration component, and the process then proceeds to step 720.

In step 710, Xa −Y1 +X2 +X:1 +Xa
The rough road characteristic value Xa is calculated according to the following, and the process then proceeds to step 730. 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 1. After that, the process 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 CI+, step 79
0, and when it is determined that 1θ1>C1 is not satisfied, the process advances to step 760.

In step 770, lJ? It is determined whether the absolute value of the rate of change of G exceeds a predetermined value CI2, and IC
When it is determined that I1>Cl-2, the process proceeds to step 790, and when it is determined that ICII>C12 is not the case, the process proceeds to step 780.

In step 780, the absolute value of the lateral G is a predetermined value CI3.
If it is determined that Gll>Cl3, the process proceeds to step 790, and if it is determined that ICI1>Cl3, the process proceeds to step 800.

In step 790, the turning determination flag Fl 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 to 800, it is determined whether or not the vehicle is turning. If the vehicle is turning, flag F1 is set to 1; if the vehicle is not turning, flag F1 is set to 1. Flag Fl is set to O.

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

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

In step 830, it is determined whether the rate of change Ga between the front and back G exceeds a predetermined value Ca2, and if Ga>C
When it is determined that it is a2, step 850
The process proceeds to step 840, and when it is determined that Ga>Ca2 is not satisfied, the process proceeds to step 840.

In step 840, it is determined whether or not the front and rear G exceeds a predetermined value Ca3, and when it is determined that Ga>Ca3, the process advances to step 850, and the G
When it is determined that tl > Ca J is not satisfied, 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 0, 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 when it is determined that the BKSW is in the on state, step 8
The process proceeds to step 90, and if it is determined that the ID5w is not in the on state, the process proceeds 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 -0b wealth, and Ga <-
When it is determined that it is Cb I, step 9
The process advances to step 10, and when it is determined that Ga<-Cbl is not satisfied, the process advances to step 900.

In step 900, the front and back G (Ga) is set to a predetermined value -c
It is determined whether or not Ga<-Cb2
When it is determined that GH<-Cb 2, the process advances to step 920, and when it is determined that GH<-Cb 2, 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 or not the rough road determination flag FX is 1. 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. If 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 s XKpxr , XKpxv Gain component for rough roads of gain of I term (integral term)
, XKIxr s Rough road gain component of gain of XKIxvD term (differential term) XKdxh 5XKdxp s
XKdxr 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 Fl is 1, and when it is determined that the flag F1 is not 1, the process proceeds to step 1050, where it is determined that the flag F1 is 1. When the determination has been made, 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 SL Kl)XI) SL Kpxr SL Kp
Turning gain component LKI of gain of xwI term (integral term)
xh s LKIXI) 5LKIxr, LKIxv
Turning gain component L Kdx of gain of D term (differential term)
h, L Kdxp, L Kdxr, L K
dxv 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 VIAKpxr , AKpxv1
Acceleration gain component AKixh of gain of term (integral term)
, AKIXI) 5AKlxr, AKixv Acceleration gain component A Kdxh of the gain of the D term (differential term)
, A Kdxp , A Kdxr , A Kdx
w is calculated, and then the process proceeds to step 1090.

In step 1080, the acceleration gain component is set to 0, 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. When the determination is made, the process advances to step 1100.

At step 1100, based on the map corresponding to the graph shown in FIG. 27, the gain of the P term (proportional term) in the arithmetic expression of the operation executed at step 450 of FIG. 8A is calculated. Deceleration gain component B Kpx
h 1B Kpxp, B Kpxr %B Kpx
Deceleration gain component BK1x of gain of vI term (integral term)
h, BKIxp s BKlxr, BKixwD
Gain component B for deceleration of gain of term (differential term) Kdxh
, Bdxp, Bdxr, and Bdxv are calculated, and then the process proceeds to step 1120.

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

In step 1120, based on the map corresponding to the graphs shown in TS28 to FIG.
Correction coefficients PXKpj, PXK]j for each gain component calculated at 0.1040.1070.1100,
PXKdj P L Kpj, P L Klj, P L Kdj
PAKpj, PAKlj, PAKdj PBKpj, PBKIj, PBKdj (j %XI) SXrs xv) is calculated, and then the process proceeds to step 113o.

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. The gains Kpj, K of the P term, 1st term, and D term of the arithmetic expression of the operation, respectively.
! j, Kdj (j-xll, XpSXr, IN/)
is set by calculating according to the following formula, and then the process proceeds to step 450 in FIG. 8A.

K pj−PXKI)j(XKI)j)+PLKpj
Fist LKI)j+PAKpj-AKpJ+PBKpj
・BKpj+CpjKij-PXKlj (-XKlj
)+PLKij・LKij+ P A K lj jar A
K 1j+ P B K lj・B K 1j+ Cf
jKdj -P X Kdj (-X Kdj
) + P L Kdj No. LKdj+PA
Kdj medium AKdJ+PBKdj-BKdj+Cdj<
j−xh, XI)% Xrs xw)(Cpj, C
1jSCdj is a constant) Next, the G feedback control gain calculation routine performed in step 480 of FIG. 8B will be described 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. When it is determined that the flag FW is not 1, the process proceeds to step 1220, and when the flag FW is 1, 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
Gain component for rough roads of gain X Kpg9 SX Kp
gr Rough road gain component of D term (differential term) gain X Kdg
p and X Kdgr are calculated based on maps corresponding to the graphs shown in FIGS. 35 and 36, respectively, and then step 123
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 Fl 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 calculated. Turning gain component L Kpg
p, L Kpgr Turning gain component L Kdg of gain of D term (differential term)
p and L Kdgr are calculated, and then the process proceeds to step 1260.

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

In step 1260, it is determined whether or not the turning determination flag F 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 AKpgp
, AKpgr Gain component for acceleration of gain of D term (differential term) A Kdg
p and A Kdgr are 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 is 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 Kl)
gp, B Kl) gr Deceleration gain component of gain of p 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 PXKpgpSPXKpgr P L Kpgp , P L KpgrP A K for each gain component calculated in 1240.1270.1300
pgp%P A K pgrP B Kl)gl) S
P B Kpgr is calculated and then step 133
Go to 0.

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 G feedback control gain is calculated according to the following formula, that is, executed at step 490 in FIG. 8B. The P-term gains xpgp, Kpgr and the D-term gains Kdgp, Kdgr of the arithmetic expression are set by being calculated according to the following formulas, and then the process proceeds to step 490 in FIG. 8B.

KPgP -p x KPgP <-x Kl)g9
＞+ P L K pgp ・L K pgp+ P
A K pgp ・A K pgp + PBKpgp Cloudy BK9gl) + CI) gpKpgr = PXKG) gr
(-XKpgr) +PLKpgr ・LKpgr +PAKpgr ・AKpgr +PBKpgr -BKpgr +CpgrKdgp
-PXKdgp (-XKdgp) 10PL Kdg
l) -L Kdgl)+ P A Kdgp lIA
Kdgp+ P B Kdgp-B Kdg9 +
CdgpKdgr =PXKdgr (-XKdgr
)+ P L Kdgr @L Kdgr+ P A
Kdgr -A Kdgr+ P B Kdgr ・
B Kdgr + Cdgr (Cpgp, Cpgr
, Cdgp, and Cdgr are constants) In the above embodiment, P of the arithmetic expressions in steps 450 and 490
The gains of the term, 1st term, and D term are calculated using separate maps, and for the same term, the gains of each mode such as heap are calculated using the same map. It may also 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 vehicle ride comfort control and vehicle body attitude control are performed, and steps 550 to 65 are performed.
0, calculations are performed to control the steering characteristics.

As described above, in step 520, the pressure Pg1 corresponding to the first control amount based on the acceleration of the vehicle body, the pressure Pbl corresponding to the second control amount based on the static support load of each actuator, A target pressure Pu1 is calculated as the sum of the pressure Px1 corresponding to the third control amount based on the high Xt, and a current 1t for ride comfort control and attitude control corresponding to this target pressure.
1 and the steering characteristic control current 1vl, a final target current Jul is calculated in step 660, and 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 calculated. 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 1250, 1280, and 1310. G feedback control gain Kpgl), Kpgr SKdgp,
Kdgr is reduced, thereby reducing the control amount based on the longitudinal acceleration Ga and the lateral acceleration G1 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 a vehicle turns or accelerates or decelerates, each actuator is controlled based on a first control amount based on the acceleration of the vehicle body, a second control amount based on the standby pressure of the actuator, and a third control amount based on changes in vehicle height. The pressure within the working fluid chamber is controlled;
This effectively suppresses changes in the attitude of the vehicle body.

Furthermore, when the vehicle is not turning or accelerating or decelerating, the acceleration of the vehicle body caused by unevenness of the road surface is detected by the longitudinal acceleration sensor and the lateral acceleration sensor, and the change in vehicle height is detected by the vehicle height sensor. By reducing the first control amount based on the acceleration of the vehicle body and the third control amount based on changes in the vehicle body, the pressure in the working fluid chamber of each actuator is substantially reduced based on the second control]m. The standby pressure is controlled to ensure a 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, Since the first and third control amounts are adjusted according to the vehicle speed, and the second and third control amounts are also adjusted depending on the vehicle speed, good ride comfort and good attitude control can be achieved under virtually all driving conditions of the vehicle. It is possible to achieve both performance and 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 calculation formulas are Set each gain to a certain constant,
P xi, P giS of the calculation formula in step 520
A gain is set for each of Pbl, and the former two, Pxl and P
The gain of gl may be adjusted based on the determination result of the driving conditions in step 430.

Further, the gain of the calculation formula in steps 450 and 490 is set to a constant constant, the target pressure in step 520 is calculated according to P ui = P xi + P gl, and in step 660, 1t is set to Iui-.
1 1tl+Kivl Iwi+ K Ibl
It may be configured to calculate the gain K ltl according to I bl and adjust the gain K ltl by 33 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 R1w in the equation of step 630 may be 0, and lEiwl≦Ei
When vl (constant), it may be set to Eiw-0.

Furthermore, although the horizontal axes of the graphs shown in FIGS. 19 and 21 are lateral acceleration, these horizontal axes may also be yaw rate, and the graph shown in FIG. 19 also shows steering angle and vehicle speed. It may be replaced with a three-dimensional map used 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,
Current supplied to the bypass valve during normal operation stoppage and during operation stoppage in abnormal situations! Fig. 7 is a graph showing the map used when calculating b, and Fig. 7 shows the pressure PI in the working fluid chamber of each actuator and the current 1b supplied to each pressure control valve.
FIGS. 8A and 8B are flowcharts showing the active calculation routine performed in step 150 of the flowchart shown in FIG. FIG. 10 is a flowchart showing a routine for determining the running condition carried out in step 430 of the flowchart shown in FIG. 8A; FIG. FIG. 11 is a flowchart showing the G feedback control gain calculation routine performed in step 480 of the flowchart shown in FIG. 8B, and FIG. 12 is a graph showing the relationship between vehicle speed V and target displacement ff1Rxh. Fig. 13 is a graph showing the relationship between longitudinal acceleration Ga and target displacement ff1Rxp, Fig. 14 is a graph showing the relationship between lateral acceleration G1, target displacement, and QRxr, and Fig. 15 is a graph showing longitudinal acceleration Ga and target displacement. FIG. 16 is a graph showing the relationship between lateral acceleration G1 and target pressure Pgl, FIG. 17 is a graph showing the relationship between vehicle speed V, and FIG. 18 is a graph showing the relationship between lateral acceleration G1 and target pressure Pgl. FIG. 19 is a graph showing the relationship between fluid temperature T and correction coefficient Kt. FIG. 20 is a graph showing the relationship between lateral acceleration G1 and first current warp control mRiv+. FIG. Second current warp control
8W RIν2, and FIG. 21 is a graph showing the relationship between the lateral acceleration 61 and the load distribution ratio between the front and rear wheels and the third current warp control QRIwa.
Figures 2 to 24 are graphs showing the relationship between the rough road characteristic value Xa and each gain component, and Figure 25 is a graph showing the relationship between the absolute value of the steering angular velocity or the rate of change of lateral acceleration and each gain component. Figure 26 is a graph showing the relationship between the rate of change in throttle opening or rate of change in longitudinal acceleration and each gain component, and Figure 27 is a graph showing the relationship between the rate of change in longitudinal acceleration and each gain component. 28 to 34 are graphs showing the relationship between vehicle speed V and correction coefficients for each gain component, and FIGS. 35 and 36 are graphs showing the relationship between vehicle speed V and correction coefficients for each gain component.
A graph showing the relationship between tXa or vehicle height warp 51E xν and each gain component, and FIG. 38 is a graph showing the relationship between the rate of change in throttle opening or the rate of change in longitudinal acceleration and each gain component, and FIG. 39 is a graph showing the relationship between the rate of change in longitudinal acceleration and each gain component. Graphs showing, Figures 40 to 4
FIG. 5 is a graph showing the relationship between the vehicle speed V and the correction coefficient for each gain component. IPR, IPIl, I R1? , I R1,... actuator, 2FR, 2F+, , 2RR, 21? L・
... Working fluid chamber, 4... Reserve tank, 6...
Pump, 8... Filter, 10... Suction channel, 12
...Drain passage, 14...Engine. 16... Rotation speed sensor, 18... High pressure flow path, 20...
・Reverse +1 valve, 22... Attenuator, 24.26
...accumulator, 32.34.36.38...
Pressure control valve 140.42.44.46...Switching control valve, 48...Low pressure flow path, 52...Fixed throttle, 54...
...Variable aperture. 56... Connection flow path, 58... Solenoid, 66.6
8.70...fixed aperture, 72.74.76...variable aperture. 78.80.82... Solenoid, 84.86.88
... Connection channels 1110 to 118... Drain channel, 1
20...Filter, 124-130...Aperture, 13
2-138...Accumulator, 144PR, 144
P.L. 144RR, 144RL...Vehicle height sensor, 50-15
6...Shutoff valve, 166-172...Relief valve, 1
74... Oil cooler, 176... Filter, 18
0... Relief valve, 182... Filter, 184...
... Throttle, 186... Solenoid on-off valve, 190... Solenoid, 192... On-off valve, 196... Bypass valve, 197.198.199... PR, 199P+,,
199RR, 199R1, ... pressure sensor, 200.
... Electric control device, 202 ... Microcomputer, 204 ... CPU, 206 ... ROM, 208
... RAM, 210 ... Input port device, 212.
...Output boat device, 216...IGSW. 218... EMSW, 220-230... Drive circuit. 232...Display device, 234...Vehicle speed sensor, 236
...Front and rear G sensor, 238...Lateral G sensor, 240
...Steering angle sensor, 242...Throttle opening sensor, 244...ID5W, 246...BKSW, 2
48...Medium/high setting switch patent Applicant: Toyota Motor Corporation
Patent Attorney Akashi RokiFigure Figure Time Figure Figure 8A Figure 8C ■ Figure 8B Figure 10 Figure 11 Figure 12 Figure 14 Figure 15 Figure ga Figure 16 Figure gl Figure iwx Figure Figure iw2 iw3 Figure 22 Figure λa Figure 23 Figure a Figure 24 Figure ■ Figure 25 Figure 26 Figure 27 Figure Ga Figure ■ Figure Figure ■ Figure 37 Figure 1θ1 again; Figure 38 Figure 39 Figure Ga Figure 35 Figure 36 Figure ■ Figure Figure ■ Figure Figure (Method) % formula % Correct. 1゜Indication of the case 1999 Patent Application No. 137832 2, Name of the invention Fluid pressure suspension 3゜Relationship with the case

Claims (1)

[Claims] A fluid pressure actuator disposed between each wheel and the vehicle body, a pressure adjusting means for adjusting the fluid pressure in the actuator, an acceleration detecting means for detecting the acceleration of the vehicle body, and a fluid pressure actuator for controlling the turning and acceleration/deceleration of the vehicle. control for controlling the pressure adjustment means based on a driving state determination means for determining, a first control amount based on the acceleration detected by the acceleration detection means, and a second control amount based on the static support load of the actuator; and wherein the control means is configured to reduce the first control amount when the vehicle is not turning or accelerating or decelerating.