JPH0725247B2 - Fluid pressure active suspension - Google Patents

Description

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

2. Description of the Related Art As one of active suspensions for vehicles such as automobiles, as disclosed in, for example, Japanese Patent Publication No. 60-500662, a fluid pressure actuator disposed between each wheel and a vehicle body and each actuator Conventionally known is a fluid pressure type active suspension having a pressure adjusting means for adjusting the fluid pressure of the vehicle and a controlling means for controlling the pressure adjusting means with a control amount based on a changing speed of a vehicle height of a portion corresponding to each wheel. ing.

According to such a fluid pressure type active suspension,
Compared with the case where the fluid pressure in each actuator is not controlled based on the changing speed of the vehicle height, it is possible to effectively suppress and control the transient change in the posture of the vehicle body.

Problems to be Solved by the Invention However, in the above active suspension,
When the vehicle travels on a rough road, the speed of change in vehicle height increases, and as a result, the control amount based on the speed of change in vehicle height becomes excessive, which causes a shock to the vehicle body and gives a feeling of strangeness to the occupants of the vehicle. There is a problem.

Especially when the speed of change in vehicle height fluctuates at high frequencies and high
Due to the response delay of the control system, the fluid pressure in the actuator does not respond well to the control output of the control means, abnormal vibration or noise is generated in the suspension due to the phase delay, and the consumption of working fluid increases. There is a problem.

The present invention has been made in view of the above-mentioned problems in the conventional fluid pressure type active suspension in which the fluid pressure in the actuator is controlled based on the change speed of the vehicle height, and the fluid pressure type improved so as not to cause these problems. It aims to provide active suspension.

Means for Solving the Problems According to the present invention, the above object is to provide a fluid pressure actuator arranged between each wheel and a vehicle body, and a pressure adjusting means for adjusting a fluid pressure in the actuator. Means for obtaining the changing speed of the vehicle height of the portion corresponding to each wheel, and the pressure adjustment based on a first control amount based on the changing speed of the vehicle height and a second control amount based on the static supporting load of the actuator. And a control means for controlling the means, the control means being achieved by a fluid pressure type active suspension configured to reduce the first control amount when the changing speed of the vehicle height is equal to or higher than a predetermined value.

According to the above-described configuration, when the vehicle height change speed is equal to or higher than the predetermined value, the first control amount based on the vehicle height change speed is reduced, so that the high vehicle height change speed is met. A sudden change in the fluid pressure in the actuator based on the large first controlled variable is avoided, and thus a shock to the vehicle body due to a sudden change in the fluid pressure in the actuator is avoided.

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 active suspension according to the present invention.
The fluid circuits of the active suspension shown are the front right wheel, left front wheel, right rear wheel, and
Actuator 1FR, 1FL provided for the left rear wheel,
1RR, 1RL, and these actuators have working fluid chambers 2FR, 2FL, 2RR, 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 in the same manner as 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 front wheel, low-pressure passage 48RR for the right rear wheel, and left rear wheel, respectively. Is connected to one end of the low-pressure flow path 48RL, and one end of each of the connection flow paths 84, 86, and 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
And switching positions 42c, 44c, 46c that connect 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 working fluid chambers 2FR, 2FL, 2R respectively
Cylinder for defining R and 2RL 106FR, 106FL, 106RR, 106RL
And piston 108F that fits in the corresponding cylinder
R, 108FL, 108RR, and 108RL, each of which is connected to a vehicle body not shown in the figure by a cylinder, and is connected to a suspension arm not shown in the figure at the tip of the rod portion of the piston. There is. 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 paths 100, 112, 114, 116 are connected to the drain flow path 118, and the drain flow path 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,
Vehicle height sensors 144FR, 144FL, 144RR, 144RL for detecting vehicle heights XFR, XFL, XRR, XRL of portions corresponding to the respective wheels are provided at positions close to 1RR, 1RL.

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 and a part of the working fluid in the corresponding connecting fluid is passed through the flow path 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 open type flow rate adjustable electromagnetic on-off valve 186 in the middle. 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 192b
It is designed to switch to. 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 signal indicating whether or not the ignition switch is on, vehicle height sensor 144FL, 144FR, 144RL, 1
From 44RR, signals indicating vehicle heights Xi (i = 1, 2, 3, 4) of portions corresponding to the left front wheel, the right front wheel, the left rear wheel, and the right rear wheel are respectively input.

Further, the input port device 210 outputs a signal indicating the vehicle speed V from the vehicle speed sensor 234 and a longitudinal acceleration G from the longitudinal G (acceleration) sensor 236.
Signal indicating a, lateral acceleration G1 from lateral G (acceleration) sensor 238
, A signal indicating the steering angle θ from the steering angle sensor 240, and a signal indicating whether the vehicle height control mode set by the vehicle height setting switch 248 is the high mode or the normal mode, respectively. It has become.

The input port device 210 appropriately processes the signal input thereto, 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. ROM 206 is shown in FIG. 3 and FIGS. 6A to 6C.
The control flow shown in the figure, the maps shown in FIGS. 4 and 5, and 7 to 25 are stored, and the CPU processes signals based on each control flow. There is. The output port device 212 outputs a control signal to the electromagnetic on-off valve 186 via the drive circuit 220 according to the instruction of the CPU 204, and the drive circuit 222 to
Control signals are output to the pressure control valves 32 to 38 via 228, specifically, the solenoids 58, 78, 80 and 82 of the variable throttles 54, 72, 74 and 76, respectively, and to the display 232 via the drive circuit 230. Is output.

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 flow chart shown in the figure, the flag Fc relates to whether or not the pressure Ps of the working fluid in the high-pressure passage has become equal to or higher than the threshold pressure Pc for completely opening the shutoff valves 150 to 156. 1 indicates that the pressure Ps has become equal to or higher than the pressure Pc, and the flag Fs corresponds to the below-described standby pressure Pbi (i = 1, 2, 3, 4) of the pressure control valves 32 to 38. It is related to whether or not the standby pressure current Ibi (i = 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 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 a pressure sensor.
A signal indicating the pressure Ps in the high-pressure channel detected by 197,
A signal indicating the pressure Pd in the low pressure passage detected by the pressure sensor 198, the pressure Pi in the working fluid chambers 2FL, 2FR, 2RL, 2RR detected by the pressure sensors 199FL, 199FR, 199RL, 199RR
Signal indicating whether the ignition switch 216 is in the ON state, vehicle height sensor 144FL, 144FR, 144R
L, a signal indicating vehicle height Xi detected by 144RR, a signal indicating vehicle speed V detected by vehicle speed sensor 234, a signal indicating longitudinal acceleration Ga detected by longitudinal G sensor 236, lateral G
A signal indicating the lateral acceleration Gl detected by the sensor 238, a signal indicating the steering angle θ detected by the steering angle sensor 240,
A signal indicating whether the mode set by the vehicle height setting switch 248 is the high mode or the normal mode is 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 200 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 engine is operating by determining whether or not the engine speed N detected by the engine speed sensor 16 and read in step 30 exceeds a predetermined value. When it is determined that the engine is not operating, the process proceeds to step 90, and when it is determined that the engine is operating, the process proceeds to step 60.

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 60, the operation of the timer for the time Ts 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 150 described later is started, Then proceed to step 70.
In this case, if the timer Ts has already been operated, the timer continues to count.

In step 70, according to Ib = Ib + ΔIbs, the current Ib supplied to the solenoid 190 of the solenoid valve 186 of the bypass valve 196 is stored in the ROM 206 according to the map corresponding to the graph shown in FIG. It is calculated, and then the process proceeds to step 80.

In step 80, the current calculated in step 70
The bypass valve 196 is driven in the valve closing direction by energizing the solenoid 190 of the electromagnetic opening / closing valve 186, and then the process proceeds to step 90.

In step 90, it is judged whether or not the pressure Ps in the high-pressure passage is the threshold value Pc or more, and when it is judged that Ps ≧ Pc is not established, the routine proceeds to step 120, where Ps ≧ When it is determined that it is Pc, the process proceeds to step 100.

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

In step 110, as described in detail later with reference to FIGS. 6A to 6C and FIGS. 7 to 25, in order to control the riding comfort of the vehicle and the attitude control of the vehicle body, step 30 is performed. By performing active calculation based on various signals read in, 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. Then proceed to step 170.

In step 120, it is judged whether the flag Fc is 1 or not, and it is judged that Fc = 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 value, the routine proceeds to step 110, where it is determined that Fc = 1 is not established, that is, it is determined that the pressure Ps has never exceeded the threshold pressure Pc. Is performed, the routine proceeds to step 130.

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

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

In step 150, 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. 5 stored in the RAM 208 as the Pbi and stored in the ROM 206, the connection flow paths 56, 84 to 88 between the respective 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 160.

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

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

In step 180, it is determined 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 determined that Ps ≧ Pso is not satisfied. If so, the process returns to step 30, and if it is determined that Ps ≧ Pso, the process proceeds to step 190.

In step 190, the current Ibi calculated in step 150 or the current Iui calculated in step 110 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 its control pressure, and then the process returns to step 30,
30 to 190 are repeated.

In step 200, the solenoid 190 of the solenoid valve 186 is
The bypass valve 196 is opened by stopping the power supply to the valve, and then the process proceeds to step 210.

In step 210, 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

The pressure control by the bypass valve at the time of starting the operation described above does not form an essential part of the present invention, and the details of this pressure control are described in Japanese Patent Application No. 63-307189 filed by the same applicant as the applicant of the present application. See issue. Further, the pressure control by the bypass valve when the operation is stopped may be performed as described in Japanese Patent Application No. 63-307190 filed by the applicant of the present application.

Next, the active calculation performed in step 110 will be described with reference to FIGS. 6A to 6C and FIGS. 7 to 25.

First, in step 300, the heave target value Rxh, the pitch target value Rxp, and the roll target value Rxr based on the target attitude of the vehicle body are calculated based on the maps corresponding to the graphs shown in FIGS. 7 to 9, respectively. Then, proceed to Step 310.

Incidentally, in FIG. 7, 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 310, 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 320.

_{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 = Te is at the _{(X 1 -X 2) + (} X 3 -X 4) step 320, performs the operation of the deviation of the displacement modes according to the following equation, the process proceeds to thereafter step 330.

Exh = Rxh-Xxh Exp = Rxp-Xxp Exr = Rxr-Xxr Exw = Rxw-Xxw In this case, Rxw may be 0, or Xxw calculated in step 310 immediately after the activation of the active suspension or the past It may be the average value of Xxw calculated in several cycles of. If | Exw | ≦ W ₁ (a positive constant), Exw = 0.

In step 330, Ej (n) (j = xh, xp, xr, x
w) is the current Ej, and Ej (n−n ₁ ) is Ej n ₁ cycle before.
As a result, the time differential value of the deviation of the displacement mode is calculated according to the following equation, and then the process proceeds to step 340.

Exh = Exh (n) -Exh ( n-n 1) Exp = Exp (n) -Exp (n-n 1) Exr = Exr (n) -Exr (n-n 1) Exw = Exw (n) -Exw Te is at the (n-n ₁₎ step 340, as the lower limit of detectable vehicle speed by a vehicle speed sensor V _0, determination vehicle speed V is whether or not a constant reference value V ₀ or less, that the vehicle is stopped It is determined whether or not it is in the middle. If it is determined that V ≦ V ₀ is not established, the process proceeds to step 360, and if it is determined that V ≦ V ₀ is performed, the process proceeds to step 350.

In step 350, the correction values xh ', xp', xr ', xw' of the time differential value of each mode are calculated based on the maps corresponding to the graphs shown in FIGS. 10 to 13, respectively. Then proceed to step 390.

In step 360, it is determined whether or not the road is a bad road. If it is determined that the road is a bad road, the process proceeds to step 380, and the road is not a bad road. When the determination is made, the process proceeds to step 370.

In this case, it is possible to determine whether or not the traveling road is a bad road by, for example, Japanese Patent Application No. 63-3310 filed by the same applicant as the applicant of the present application.
It may be performed based on the vehicle height detection result as described in No. 42, or may be performed based on the warp Xxw as described in Japanese Patent Application No. Hei.

In step 370, the correction values xh ', xp', xr ', xw' of the time differential value of each mode are calculated based on the maps corresponding to the graphs shown in FIGS. 14 to 17, respectively. Then proceed to step 390.

In step 380, the correction values xh ', xp', xr ', xw' of the time differential value of each mode are calculated based on the maps corresponding to the graphs shown in FIGS. 18 to 21, respectively. Then proceed to step 390.

In step 390, PID correction calculation of displacement feedback control is performed according to the following equation, and then step 4
Go to 00.

Cxh = Kpxh ・ Exh ＋ Kixh ・ Ixh (n) ＋ Kdxh ・ xh ′ Cxp ＝ Kpxp ・ Exp ＋ Kixp ・ Ixp (n) ＋ Kdxp ・ xp ′ Cxr ＝ Kpxr ・ Exr ＋ Kixr ・ ExwKwx ・ Kwx ・ Kwxw n) + Kdxw · xw ′ In the above equations, Ij (n) and Ij (n-1) are the current and one cycle previous Ij, and Tx is the time constant Ij (n) = Ej (n). + Tx Ij (n−1), and | Ij | ≦ Ijmax where Ijmax is a predetermined value. Further, the coefficients Kpj, Kij, and Kdj (j = xh, xp, xr, xw) are a proportional constant, an integral constant, and a differential constant, respectively.

In step 400, the calculation of the inverse conversion of the displacement mode is performed according to the following equation, and then the process proceeds to step 410.

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 410, based on the maps corresponding to the graphs shown in FIG. 22 and FIG. 23, the pressure correction amounts Pga and Pgl in the front-rear direction and the lateral direction of the vehicle are calculated,
Then proceed to step 420.

In step 420, 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 430.

Cgp = Kpgp · Pga + Kdgp { Pga (n) -Pga (n-n 1)} Cgr = Kpgr · Pgl + Kdgr {Pgl (n) -Pgl (n-n 1)} Note At a above formulas, 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 430, the steering angle speed 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 from this steering angle speed and vehicle speed V Based on the map corresponding to the graph shown in FIG. 24, the rate of change of the predicted lateral G, that is, Is calculated, and then the process proceeds to step 440.

In step 440, the inverse conversion operation in G mode is performed according to the following equation, and then the process proceeds to step 450.

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 450, based on the pressure Pbi stored in the RAM 208 in step 150 and the result calculated in steps 400 and 440, 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 460.

In step 460, 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 470.

_{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 ₁ ＝ Ku ₄ Pu ₄ ＋ Kh (Psr−Ps) −Kl ・ Pd Note that Ku ₁ , Ku ₂ , Ku ₃ , Ku ₄ are proportional constants for each wheel, and Kh and Kl are high pressures, respectively. A correction coefficient for the pressure in the flow passage and a pressure in the low pressure passage, α is a correction constant between the front and rear wheels, and Psr is a reference pressure in the high pressure passage.

In step 470, 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. 25, 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 480.

In step 480, the current warp (twist amount around the longitudinal axis of the vehicle body) according to Iw = (It ₁ −It ₂ ) − (It ₃ −It ₄ ).
Is performed, and then the process proceeds to step 490.

In step 490, 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 500.

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

In step 500, the current warp target control amount is calculated in accordance with Eiwp = Kiwp · Eiw using Kiwp as a proportional constant, and then the process proceeds to step 510.

In step 510, the inverse conversion of the current warp is calculated according to the following equation, and then the process proceeds to step 520.

Iw ₁ = Eiwp / 4 Iw ₂ = -Eiwp / 4 Iw ₃ = -Eiwp / 4 Iw ₄ = Eiwp / 4 In Step 520, the following formula is used based on the results calculated in Steps 470 and 510. Then, the final target current Iui to be supplied to each pressure control valve is calculated, and then the process proceeds to step 170 in FIG.

Iui = Iti + Iwi (i = 1, 2, 3, 4) Thus, according to the illustrated embodiment, when the time differential value of the deviation of each mode calculated in step 330, that is, the change speed of the vehicle height is high, Velocity change speeds xh ′, xt ′, xr ′, which are reduced and corrected in steps 350, 370, and 380,
xw ′ is calculated, and the PID compensation calculation of the displacement feedback control is performed based on this calculation result in step 390, so the vehicle height change speed becomes excessive, which causes a shock to the vehicle body and gives an occupant a strange feeling. Is avoided.

In particular, in steps 340 and 360, a determination of no or yes is made. Even if the vehicle speed change speed fluctuates with high frequency and amplitude when driving on a bad road, the vehicle height change speed is changed in step 380. Is reduced and corrected, and the PID compensation calculation of displacement feedback control is performed in step 390 based on this reduced and corrected value, so abnormal vibration and abnormal noise of the suspension are avoided and the consumption of working fluid is reduced. It can be reduced.

Further, from the viewpoint of the ride comfort of the vehicle, it is preferable that the control amount based on the vehicle height change speed is small, and conversely, in order to effectively suppress the vehicle height change when the vehicle is stopped, It is preferable that the control amount based on the changing speed is high, and thus it is difficult to satisfy both of them. However, according to the illustrated embodiment, in the region where the changing speed of the vehicle height is extremely high, Since the change speed is corrected and calculated to a negative value, it is possible to improve the riding comfort of the vehicle when the vehicle is traveling on a bad road.

When the vehicle is stopped for which a yes determination is made in step 340, the reduction correction amount of the vehicle height change speed performed in step 350 is smaller than in other cases, and the vehicle height change speed is relatively high. Based on the above, the PID compensation calculation of the displacement feedback control is performed in step 390, and thereby, the change in the posture of the vehicle body caused by the occupant getting on and off when the vehicle is stopped is effectively suppressed.

26 and 27 show step 330 in the above embodiment.
11 is a flowchart showing a routine for calculating a correction value of a time differential value of a deviation in a displacement mode which may be executed instead of ~ 380. The calculation performed in steps 600 and 800 is
Since it is the same as the operation performed in step 330 of FIG. 6A, its explanation is omitted.

In the embodiment shown in FIG. 26, step 600 is followed by step 610, and in step 610, it is determined whether the time differential value xh of the deviation of the heave exceeds the reference value Axh. When it is determined that xh> Axh, the process proceeds to step 630, and when it is determined that xh> Axh is not satisfied, the process proceeds to step 620.

In step 620, the correction value xh 'is set to xh, and then the process proceeds to step 640.

In step 630, the correction value xh ′ is set to Axh,
Then proceed to step 640.

In step 640, the time derivative of the pitch deviation xp
Is determined to exceed the reference value Axp, and xp
When it is determined that> Axp, the routine proceeds to step 660. When it is determined that xh> Axp is not established, the process proceeds to step 650.

In step 650, the correction value xp 'is set to xp, and then the process proceeds to step 670.

In step 660, the correction value xp 'is set to xp, and then the process proceeds to step 670.

In step 670, the time derivative of roll deviation xr
Is determined to exceed the reference value Axr, xr
If it is determined that it is> Axr, the process proceeds to step 690, and if it is determined that xr> Axr is not satisfied, the process proceeds to step 680.

In step 680, the correction value xr 'is set to xr, and then the process proceeds to step 700.

In step 690, the correction value xr ′ is set to Axr,
Then proceed to step 700.

In step 700, the time derivative of the warp deviation xw
Is determined to exceed the reference value Axw, and xw
If it is determined that> Axw, the process proceeds to step 720, and if it is determined that xw> Axw is not satisfied, the process proceeds to step 710.

In step 710, the correction value xw 'is set to xw, after which the process proceeds to step 390 in FIG. 6B.

In step 720, the correction value xw ′ is set to Axw,
Then proceed to step 390.

Further, in the embodiment shown in FIG. 27, step 810 is performed after step 800, and in step 810, the correction value xh ′ is a map corresponding to the graph shown in FIG. 28. Calculation is performed based on the above, and then the process proceeds to step 820.

In step 820, the correction value xp 'is calculated based on the map corresponding to the graph shown in FIG. 29, and then the process proceeds to step 830.

In step 830, the correction value xr 'is calculated based on the map corresponding to the graph shown in FIG. 30, and then the process proceeds to step 840.

In step 840, the correction value xw ′ is calculated based on the map corresponding to the graph shown in FIG. 31, and then the
Proceed to step 390 in Figure 6B.

Thus, also in these embodiments, when the vehicle height changing speed is high, the vehicle height changing speed is reduced and corrected, and the reduced and corrected vehicle height changing speeds xh ', xp', xr ', xw'.
Since the PID compensation calculation of the displacement feedback control is performed on the basis of the above, it is possible to reliably prevent the vehicle height from changing at an excessively high rate, which causes a shock to the vehicle body and gives an occupant an uncomfortable feeling.

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.

EFFECTS OF THE INVENTION As is apparent from the above description, according to the present invention, the first control amount based on the changing speed of the vehicle height is reduced when the changing speed of the vehicle height is equal to or higher than a predetermined value. It is avoided that the fluid pressure is suddenly changed by the first control amount, and thus the shock of the vehicle body due to this is effectively prevented, and the abnormal vibration and noise of the suspension are prevented. Furthermore, the consumption of working fluid is reduced.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic configuration diagram showing a fluid circuit of one embodiment of a fluid pressure type active suspension according to the present invention, and FIG. 2 is an electric control device of the embodiment shown in FIG. FIG. 3 is a block diagram showing the flow chart, FIG. 3 is a flow chart showing a control flow achieved by the electric control device shown in FIG.
Fig. 5 is a graph showing a map used to calculate the current Ib supplied to the bypass valve at the start of operation of the active suspension. Fig. 5 is the pressure Pi in the working fluid chamber of each actuator and the pressure Pi 6A to 6C are flow charts showing a routine of the active calculation performed in step 110 of the flow chart shown in FIG. 3, and FIG. 7 is a vehicle speed V. Graph showing the relationship between the target displacement Rxh and the 8th
Figure is a graph showing the relationship between longitudinal acceleration Ga and target displacement Rxp. Figure 9 is a graph showing the relationship between lateral acceleration Gl and target displacement Rxr. Figures 10 to 21 are displacement modes. The graph showing the map used for the calculation of the correction value of the time differential value of the deviation of Fig. 22, Fig. 22 is the graph showing the relationship between the longitudinal acceleration Ga and the correction amount Pga of the pressure, and Fig. 23 is the lateral acceleration Gl. Fig. 24 is a graph showing the relationship between the pressure correction amount Pgl and Fig. 24 is the rate of change of the vehicle speed V, the steering angular velocity, and the predicted lateral acceleration. Fig. 25 is a graph showing the relationship between
And a graph showing the relationship between the correction coefficient Kt, FIG.
FIG. 27 shows correction values xh ′, xp ′, x of time derivative of deviation of displacement mode in another embodiment of the present invention.
A flowchart showing a routine for calculating r ′ and xw ′,
28 to 31 are graphs showing maps used for calculation of the correction values xh ', xp', xr ', xw' in the embodiment shown in FIG. 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, 1
4 …… Engine, 16 …… Revolution sensor, 18 …… High pressure flow path, 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 flow path, 58 ...... Solenoid, 66, 6
8, 70 …… Fixed aperture, 72, 74, 76 …… Variable aperture, 78, 80, 8
2 ... Solenoid, 84, 86, 88 ... Connection flow path, 110-118 ...
… Drain flow path, 120 …… Filter, 124-130 …… Restrictor, 132
~ 138 …… Accumulator, 144FR, 144FL, 144RR, 144RL
...... Vehicle height sensor, 150 to 156 ...... Shut-off valve, 166 to 172 ...... Relief valve, 174 ...... Oil cooler, 176 ...... Filter, 180 ......
Relief valve, 182 …… Filter, 184 …… Restrictor, 186 …… Electromagnetic on-off valve, 190 …… Solenoid, 192 …… Open / close valve, 196 …… Bypass valve, 197, 198, 199FR, 199FL, 199RR, 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 , 220
~ 230 …… Drive circuit, 232 …… Display unit, 234 …… Vehicle speed sensor,
236 …… front and rear G sensor, 238 …… lateral G sensor, 240 …… steering angle sensor, 248 …… vehicle height setting switch

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshio Yutani, 1 Toyota Town, Toyota City, Aichi Prefecture, Toyota Motor Corporation (72) Inventor, Kunihito Sato, 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Corporation (72) Inventor Masaki Kasai 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Corporation (72) Inventor Koichi Kokubo 2-1, Asahi Town, Kariya City Aichi Prefecture Aisin Seiki Co., Ltd. (72) Inventor Sugiyama Takami 2-1, Asahi-cho, Kariya city, Aichi Aisin Seiki Co., Ltd. (56) Reference JP-A 54-155522 (JP, A) JP-A 60-176805 (JP, A) JP-A 62-289420 (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 change speed of a vehicle height at a portion corresponding to each wheel. Means, and a control means for controlling the pressure adjusting means based on a first control amount based on a changing speed of the vehicle height and a second control amount based on a static supporting load of the actuator, the control means. Is a fluid pressure type active suspension configured to reduce the first control amount when the vehicle height changing speed is equal to or higher than a predetermined value.