JPH0379420A - Fluid pressure active suspension - Google Patents

Abstract

PURPOSE:To prevent abrupt change in a car position when the supply pressure of a working fluid exceeds a predetermined value, by controlling the controlled pressure to an aimed pressure by means of feed-back control based on detected car height, and by gradually changing the aimed pressure to the value determined by the running condition of an automobile. CONSTITUTION:To front wheel and rear wheel high pressure channels 18A, 18R connected to a high pressure channel 18 that is connected to a discharge side of a pump 6, via pressure control valves 32, 34, 36, 38, actuators 1FR-1RL related to front and rear, right and left wheels are forked and connected. On the way of each working fluid supply passage, cutting valves 150, 152, 154, 156 that are closed when the supply pressure is not more than a predetermined value, are provided. When the supply pressure exceeds the predetermined value, the pressure control valves 32-38 are so controlled as for the controller pressure to be an aimed pressure by feed-back control based on detected car height. The aimed pressure is so controlled as to be gradually changed from a virtually equal one to the pressure in the actuator until the supply pressure exceeds the predetermined value, to the one determined by the running condition of an automobile.

Description

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

Conventional techniques such as Utility Model Application Publication No. 62-202404 and Japanese Patent Application Publication No. 63
As described in No. 106132, as one of the active suspensions of vehicles such as automobiles, there is a fluid pressure actuator disposed between each wheel and the vehicle body, and an operation for supplying working fluid at supply pressure to the actuator. a fluid supply passage; a working fluid discharge passage for discharging the working fluid from the actuator; a shutoff valve that is provided in the middle of the working fluid supply passage and the working fluid discharge passage and is selectively opened and closed; and the working fluid supply passage and the working fluid discharge. BACKGROUND ART Hydraulic active suspensions are conventionally known that include pressure control means provided in the middle of a passage to control the supply and discharge of working fluid to and from corresponding actuators and to control the pressure within the actuators.

In conventional hydraulic active suspensions incorporating such shutoff valves, the shutoff valve closes in response to supply pressure below a predetermined value, and closes in response to supply pressure exceeding a predetermined value. When a shutoff valve that opens in response is used, the supply pressure rises at the start of suspension operation, causing a sudden change in the pressure inside the actuator at the time the shutoff valve opens. This may cause shock to the vehicle body.

In order to prevent the occurrence of such a shock, for example, if the patent application filed in 1983 is filed by the same applicant as the applicant,
As described in No. 307188, the pressure within the actuator is detected at the start of suspension operation, and the command pressure to the pressure control means is made substantially equal to the detected pressure (standby pressure); As described in Japanese Patent Application No. 1-50732 filed by the same applicant, the pressure inside each actuator is estimated from the vehicle height of the part corresponding to each wheel, and the command pressure to the pressure control valve is estimated. It is conceivable to make the pressure substantially equal to the standby pressure (standby pressure).

Problem to be Solved by the Invention When such standby pressure control is performed, it is possible to prevent a sudden change in the pressure inside the actuator at the stage when the shutoff valve is opened, thereby causing a shock to the rIi body. However, when active control is started, in which the control pressure of the pressure control means is controlled to the target pressure determined by the vehicle running condition by feedback control based on the vehicle height, the target pressure is compared with the standby pressure. If the targets are significantly different, there is a problem in that the attitude of the vehicle body changes rapidly.

In order to reduce the shock at the stage of opening the shutoff valve, the control pressure of each pressure control means is controlled to a standby pressure substantially equal to the pressure in the corresponding actuator at the start of suspension operation. In view of the above-mentioned problems in the conventional hydraulic active suspension, the attitude of the vehicle body suddenly changes even when active control is started after the pressure in each actuator has been controlled to standby pressure. The objective is to provide an improved hydraulic active suspension that is free of

Means for Solving the Problems According to the present invention, the above-mentioned objects include vehicle height detection means for detecting the vehicle height of a portion corresponding to each wheel, and a fluid disposed between each wheel and the vehicle body. a pressure actuator, a working fluid supply passage that supplies working fluid at a supply pressure to the actuator, a working fluid discharge passage that discharges the working fluid from the actuator, and a working fluid discharge passage provided midway between the working fluid supply passage and the working fluid discharge passage. a cutoff valve that closes in response to the supply pressure being lower than a predetermined value; and a shutoff valve that is provided in the middle of the working fluid supply passage and the working fluid discharge passage to control the supply and discharge of the working fluid to the corresponding actuator. and pressure control means for controlling the pressure within the actuator, and controlling the pressure so that the control pressure of the pressure control means is substantially equal to the pressure within the actuator at least until the supply pressure exceeds the predetermined value. controlling the pressure control means so that when the supply pressure exceeds the predetermined value, the control pressure of the pressure control means becomes a target pressure by feedback control based on the vehicle height detected by the vehicle height detection means; control means for controlling the target pressure, and the target pressure is configured to be gradually changed from a value substantially equal to the pressure within the actuator until the supply pressure exceeds the predetermined value to a value determined by the running state of the vehicle. This is achieved through a hydraulic active suspension.

Effect of the Invention According to the above configuration, the pressure control means is controlled so that the control pressure is substantially equal to the pressure within the corresponding actuator, at least until the supply pressure of the working fluid exceeds a predetermined value. When the pressure exceeds a predetermined value, the control pressure is controlled to the target pressure by feedback control based on the vehicle height detected by the vehicle height detection means. Since the pressure in each actuator is gradually changed from a value substantially equal to the pressure in the corresponding actuator to a value determined by the driving state of the vehicle, even when active control is started after the pressure in each actuator has been controlled to the standby pressure, The pressure in each actuator is controlled to gradually change from the standby pressure to a predetermined target pressure depending on the running state of the vehicle, thereby reliably preventing a sudden change in the attitude of the vehicle body at the active control start stage.

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

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

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

Further, in the figure, 4 indicates a reserve tank that stores hydraulic oil as a working fluid, and the reserve tank 4 is connected to a suction flow path 10 in which a filter 8 for removing foreign matter is provided in the middle.
The pump 6 is connected to 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 flow path 181? and 18R are connected to one end of a right front wheel high pressure flow path 18PR, a left front wheel high pressure flow path 181'L, a right rear wheel high pressure flow path 18RR1, and a left rear wheel high pressure flow path 18RL, respectively. High pressure flow path 18FR.

18) Filters 28PR, 28PL, 28RR, and 28RL are provided in the middle of L, 18RR, and 18RL, respectively, and the other ends of these high-pressure flow paths are controlled by pilot operation of pressure control valves 32, 34, 36, and 38, respectively. It is connected to the P port of type 3 boat switching control valve 40.42.44.46.

The pressure control valve 32 is connected to the switching control valve 40 and the high pressure flow path 18F.
It consists of a flow path 50 that communicates and connects the 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 path.

A low pressure flow path 481'R is connected to the R port of the switching control valve 40, and a connection flow path 56 is connected to the A port. The switching control valve 40 has a fixed throttle 52 and a variable throttle 5.
This is a spool valve that takes in the pressure Pp in the flow path 50 and the pressure Pa in the connecting flow path 56 as pilot pressure, and connects the boat P and boat A for communication when the pressure Pp is higher than the pressure Pa. Switched to switching position 40a,
When the pressures Pp and Pa are equal to each other, the switch is switched to the switching position 40b which cuts off communication between all boats, and the pressure P
When p is lower than pressure Pa, the switch is switched to a switching position 40c that connects boat R and boat A in communication. In addition, the variable throttle 54 changes the effective passage cross-sectional area of the throttle by controlling the current supplied to the solenoid 58, and thereby works together with the fixed throttle 52 to increase the pressure P
It is designed to change p.

Similarly, pressure control valves 34 to 38 are each pressure control valve 32
pilot-operated 3-port switching control valves 42, 44, 46 corresponding to the switching control valve 40, flow passages 60, 62.64 corresponding to the flow passage 50, and fixed throttles 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 have solenoids 78, 80, and 82, respectively.

In addition, the switching control valves 42, 44, and 46 are switching control valves 40
The R port has a low pressure flow path 48FL for the left rear wheel and a low pressure flow path 48R for the right rear wheel, respectively.
Low pressure flow path 481 for R1 left rear wheel? One end of L is connected, and the A port has connection channels 84, 86, and 88, respectively.
is connected at one end. In addition, the switching control valves 42 to 46
are the flow paths 6 between the corresponding fixed throttle and variable throttle, respectively.
Pressure Pp within 0-64 and corresponding connection channels 84-88
It is a spool valve that takes in the internal pressure Pa as a 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
When the pressures Pp and Pa are equal to each other, the switches are switched to the switching positions 42b, 44b, and 46b, which cut off communication between all ports, and when the pressure Pp is lower than the pressure Pa, the board R and port A are communicated. The switching positions 42c, 44c, and 46c are connected.

As schematically shown in FIG. 1, each actuator IPR, IPL, IRR, II? L are working fluid chambers 21''R, 2t'L, 21'il'l, 21, respectively.
? Cylinder defining L 1.06PR, 106FL, 1
06RR, 106RL and pistons 108FR, 108PL, 1081 that fit into the corresponding cylinders, respectively.
? I? , 1081? Each cylinder is connected to the vehicle body (not shown), and the tip of the rod portion of the piston is connected to a suspension arm (not shown). Although not shown in the internal explanation, a suspension spring is loaded between the upper seat fixed to the rod of the piston and the lower seat fixed to the cylinder.

Also, the cylinder 1061”R, 106 of each actuator
1) Drain passage 1 for L, 106RR, 106RL
10.112.114.116 are connected at one end. The other end of the drain passage 110, 112, 114, 116 is connected to a drain passage 118, which is connected to the reserve tank 4 via a filter 120, thereby preventing leakage from the working fluid chamber. The used working fluid is returned to the reserve tank.

Accumulators 132.134.136.138 are connected to the working fluid chambers 2PR, 2PL, 2RR, and 2RI via throttles 124.126.128.130, respectively. Also piston 108FR, 108F15.10
8RR and 108RL have flow paths 140FR and 14, respectively.
0F+,,140RI? , 140RL are provided. These flow paths are the corresponding flow paths 56.84 to 56.
88 and working fluid chambers 2FR, 2PL, 2RR.

2RL, and a filter 142 is installed in the middle of each.
FR, 142PL, 142RR, 1421? Lwo#
There is L. Also, actuators I PR, I PL,
In the vicinity of I RR and IRl, there are vehicle height XFI? of the parts corresponding to each wheel. , XFL, XRR
, vehicle height sensor 144PR, 144PL that detects XRL
, 144RR, 1441? L is provided.

Pilot-operated cutoff valves 150, 152.154.156 are provided in the middle of the connection channels 56.84 to 88, respectively, and these cutoff valves are connected to corresponding pressure control valves 40.42.44.46, respectively. High pressure flow path 1 on the more upstream side
When the pressure difference between the pressure in 8FR, 18FL, 18RR, 18RL and the pressure in drain flow path 110, 112, 114, 116 is within a predetermined value, the valve is maintained in a closed state. In addition, the portions between the corresponding pressure control valves and the cutoff valves of the connection channels 56, 84 to 88 are respectively flow channels 1
58.160.162.164 communicates with the portion downstream of the variable throttle of the flow path 50.60.62.64 of the corresponding pressure control valve. Relief valves 166, 168, 170, 1 are provided in the middle of the flow paths 158 to 164, respectively.
72 are provided, and these relief valves respectively take in the pressure at the upstream side of the corresponding channel 158, 160, 162, 164, that is, the side of the corresponding connection channel, as pilot pressure, and When the pilot pressure exceeds a predetermined value, the valve is opened to guide a portion of the working fluid in the corresponding connection flow path to the flow paths 50, 60 to 64.

In addition, each of the cutoff valves 150 to 156 is connected to the high pressure flow path 18F+?
, 18 FL, 18 RR, 181? The valve may be maintained in a closed state when the differential pressure between the pressure inside L and the atmospheric pressure is below a predetermined value.

Low pressure flow path 4811? The other end of 48FL is connected to one end of the low pressure flow path 48F for the front wheels, and the low pressure flow path 481? l
? and l? The other end of L is the low pressure flow path 481 for the rear wheels? is connected to one end of the The other ends of the low pressure channels 48F and 48R are connected to one end of the low pressure channel 48 in communication. The low pressure flow path 48 has an oil cooler 174 in the middle and is connected to the reserve tank 4 via a filter 176 at the other end. A valve 20 and an attenuator 22 are installed on the opposite side of the high pressure flow path 18.
The portion between is connected to the low pressure flow path 48 by 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 the illustrated embodiment, the high pressure flow path 18I? The low-pressure flow path 48R is a flow path 18 having a filter 182, a throttle 184, and a normally open electromagnetic on-off valve 186 that can adjust the flow rate.
They are connected to each other by 8. 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 1
81? 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 when there is no differential pressure on both sides of the throttle 184, it maintains the valve closed position 192a and closes the throttle 18.
4, when the pressure on the high pressure flow path 18R side is high, the valve is switched to the closed position 192b. In this way, the throttle 184, the electromagnetic on-off valve 186, and the on-off valve 192 cooperate with each other to selectively connect the high-pressure flow path 18R and the low-pressure flow path 48R1, and therefore the high-pressure flow path 18 and the low-pressure flow path 48, so that the high-pressure flow path 18R and the low-pressure flow path 48R1 are connected to each other. The bypass valve 196 that controls the flow rate of the working fluid flowing into the low-pressure flow path is opened.

Furthermore, in the illustrated embodiment, the high pressure flow path 18I? and low pressure channel 481? have pressure sensors 197 and 198, respectively.
are provided, 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 199 PI? , 199PL, 1991, 199
RL is provided, and these pressure sensors detect the pressures in the working fluid chambers 2PR, 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. Electrical control device 200 includes a microcomputer 202 .

The microcomputer 202 may have a general configuration as shown in FIG. 2, and includes a central processing unit (CPU) 204 and a read-only memory (ROM).
206, random access memory (RAM) 208, a human port device 210, and an output port 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, a signal indicating the temperature T of the working fluid from the temperature sensor 195, and pressure sensors 197 and 19.
8, a signal indicating the pressure Ps in the high pressure flow path and the pressure Pd in the low pressure flow path, pressure sensor 199FL, 1991
From SR, 199R14, 199RR respectively working fluid chamber 2+: L, 2 F+? , 2 +? l2.2+? I
? A signal indicating the internal pressure P1 (1-1, 2, 3, 4),
A signal from the ignition switch (IGSW) 216 indicating whether the ignition switch is in the on state;
Vehicle height sensor 144FL, 144PR, 144RL, 1
From the 44RR, signals indicating vehicle heights Xt (i-1, 2, 3, 4) corresponding to the left front wheel, right front wheel, left rear wheel, and right rear wheel, respectively, are manually input.

In addition, the input port device 210 includes a signal indicating the vehicle speed ■ from the vehicle speed sensor 234, a signal indicating the longitudinal acceleration Ga from the longitudinal G (acceleration) sensor 236, and a signal indicating the longitudinal acceleration Ga from the longitudinal G (acceleration) sensor 236.
8, a signal indicating the lateral acceleration G1, a signal indicating the steering angle θ from the steering angle sensor 240, and a signal indicating whether the vehicle height control mode set by the vehicle height setting switch 248 is high mode or normal mode. Each of them is to be input.

The input port device 210 appropriately processes the signals input thereto, and outputs the processed signals to the CPU and RAM 208 according to instructions from the CPU 204 based on a program stored in the ROM 206 . ROM2
06 stores the control flows shown in Fig. 3 and Figs. 7A to 7D and the maps shown in Figs. 4 to 6 and Figs. 8 to 14, and the CPU It is designed to process signals based on flows. Output boat device 21
2 outputs a control signal to the electromagnetic on-off valve 186 via the drive circuit 220 according to instructions from the CPU 204, and the drive circuit 222
228 to the pressure control valves 32 to 38, in particular the solenoids 58.
78, 80, and 82, and outputs a control signal to the drive circuit 230.
A control signal is output to the display 232 through the .

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

Note that the control flow shown in FIG. 3 is started when the ignition switch 216 is closed. Further, in the flowchart shown in FIG. 3, the flag Fc indicates that the pressure Ps of the working fluid in the high pressure flow path is
This relates to whether or not the pressure Ps has ever exceeded the threshold pressure Pc that causes the valve to fully open.
c or more, and the flag Fs indicates that the standby pressure Pb1 (1
-1, 2, 3, 4) standby pressure current 1b
This relates to whether or not i (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 in the figure) is turned on, and then in step 2
Go to 0.

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

In step 30, a signal indicating the rotation speed N of the engine 14 detected by the rotation speed sensor 16, a signal indicating the rotation speed N of the engine 14 detected by the rotation speed sensor 16,
A signal indicating the temperature T of the working fluid detected by the pressure sensor 195, and a pressure Ps in the high pressure flow path detected by the pressure sensor 197.
A signal indicating the pressure Pd in the low pressure flow path detected by the pressure sensor 198, a pressure sensor 199PL,
A signal indicating the pressure PI in the working fluid chambers 2PL, 2PR, 2RL, and 2RR detected by 199FR, 199RL, and 199RR, a signal indicating whether the ignition switch 216 is in the on state, and a vehicle height sensor 144PL.
, 144PR, 144RL, and 144RR, a signal indicating the vehicle height Xi detected by the vehicle speed sensor 234, a signal indicating the longitudinal acceleration Ca detected by the longitudinal G sensor 236, and a signal indicating the longitudinal acceleration Ca detected by the lateral G sensor 238. A signal indicating the detected lateral acceleration Gl, a signal indicating the steering angle θ detected by the steering angle sensor 240, and a signal indicating whether the mode set by the vehicle height setting switch 248 is high mode or normal mode. Reading is performed, 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, where the ignition switch is in the on state. When it is determined that this is the case, the process advances to step 50.

In step 50, 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 30 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 90, and when it is determined that the engine is being operated, the process proceeds to step 60.

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

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

In step 70, the current 1b applied to the solenoid 190 of the electromagnetic on-off valve 186 of the bypass valve 196 is RO
Based on the map corresponding to the graph shown in FIG.

In step 80, the current Ib calculated in step 70 is applied to the solenoid 190 of the electromagnetic on-off valve 186, thereby driving the bypass valve 196 in the closing direction, and then the process proceeds to step 90.

In step 90, it is determined whether the pressure Ps in the high-pressure flow path is equal to or higher than the threshold value Pc, and when it is determined that Ps≧Pc is not satisfied, the process proceeds to step 120, where Ps≧ When it is determined that it is Pc, the process advances to step 100.

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

In step 110, in order to control the ride comfort of the vehicle and the posture of the insect body, step 30 is performed, as will be described in detail later with reference to FIGS. 7A to 7D and FIGS. 8 to 14. The solenoids 58, 78, 80, 8 of the illuminating throttles 54, 72 to 76 of each pressure control valve are
The current 1ui to be applied to 2 is calculated, and the process then proceeds to step 170.

In step 120, it is determined whether the flag Fc is 1 or not, and it is determined that it is Fc-1, that is, is the pressure Ps of the working fluid in the high-pressure flow path equal to or higher than the threshold pressure Pc? When it is determined that the pressure has become lower than this value, the process proceeds to step 11.0, and it is determined that the pressure is not Fc-1, that is, the pressure PS has become equal to or higher than the threshold pressure Pc. If it is determined that there is no such information, the process advances to step 130.

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

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

In step 150, the operation of the Ts timer is stopped. Also, from the vehicle height XI read in step 30,
Based on the map corresponding to the graph shown in FIG. 5 stored in the ROM 206, the working fluid chamber 2r11.2r'l? ,2I? L, 2R1? The standby pressure P old is calculated for the internal pressure P1 and stored in RAM20.
8 and pressure control valves 34.32.38.
36 variable apertures 72.54.76.74 solenoid 7
The standby pressure current 1bi (1-1, 2, 3, 4) to be applied to 8.58.82.80 is calculated based on the map corresponding to the graph shown in FIG. 6, and then the process proceeds to step 160. .

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

In step 170, it is determined whether the current Ib calculated in step 70 is greater than or equal to the reference value 1bo, and when it is determined that Ib≧Ibo is not satisfied, the process proceeds to step 30. Returning, if it is determined that Ib≧Ibo, the process advances to step 180.

In step 180, it is determined whether the pressure Ps of the working fluid in the high pressure flow path read in step 30 is equal to or higher than the reference value Pso, and it is determined that Ps≧Pso is not satisfied. When it has been carried out, the process returns to step 30 and Ps≧
When it is determined that it is Pso, step 19
Go to 0.

In step 190, in step 150 /fL
'fL electric current ff1lbl or the current 1ui calculated in step 110 is output to the variable throttle solenoids 58, 78 to 82 of each pressure control valve, thereby driving each pressure control valve and controlling its control pressure. control, and then returns to step 30 and steps 30 to 190 described above are repeated.

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

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

Note that the pressure control by the bypass valve at the time of starting the operation described above does not constitute a main part of the present invention, and the details of this pressure control can be found in Japanese Patent Application No. 1983-1999 filed by the same applicant as the present applicant. See No. 307189. Moreover, the pressure control by the bypass valve when the operation is stopped is also disclosed in Japanese Patent Application No. 63-3071 filed by the same applicant as the present applicant.
It may be done as described in No. 90.

Next, the active operation performed in step 110 will be described with reference to FIGS. 7A to 7D and FIGS. 8 to 14.

In the inner boxes 7A to 7D, the flag Fi indicates whether or not the displacement target initial value calculated in step 310, which will be described later, has been calculated, and 1 indicates that the displacement target initial value has been calculated. It is shown that. Also flag F xhSF
xpSF xr and FXV are each heap (Rxh)
, Pitch (Rxp), O-ru (Rxr), Warb (
Rxv), the deviation between the current mouth mark position amount and the previous target displacement amount Erxh, ErxpSErxrsErxν
This relates to whether the absolute value of the above-mentioned deviation has become less than or equal to the corresponding reference value, and 1 indicates that the absolute value of the above-mentioned deviation has become less than or equal to the corresponding reference value.

First, in step 300, it is determined whether or not the flag Fi is 1. When it is determined that the flag is Fi-1, the process proceeds to step 330, and it is determined that the flag is not Fi-1. If the process has been performed, the process advances to step 310.

In step 310, the displacement target initial value Rxho s RXI)o 5Rxr6 , Rx
wg is calculated, and then the process proceeds to step 320.

Rxho −(Xl +X: ) +
(Xa +X4)Rxpo --(XI
+x =: ) 10 (Xa +X4)R
xr6- (X+ -X2) + (Xa -Xa
)Rxvo = (X+ X= ) −(Xa −X
4) In step 320, the flag F1 is set to 1, and then the process proceeds to step 330.

In step 330, the heap daily target value Rxb is calculated based on the map corresponding to the graph shown in FIG. 8, and then the process proceeds to step 340.

In FIG. 8, solid lines and broken lines indicate patterns when the vehicle height control mode set by the vehicle height setting switch is normal mode and high mode, respectively.

In step 340, it is determined whether the flag Fxh is 1 or not, and when it is determined that it is Fxh-1, the process proceeds to step 400, and it is determined that it is not Fxh-1. If so, the process advances to step 350.

In step 350, Rxh(n) is
The current target displacement amount calculated at 0, Rxttl
Step 370 (described below) before (Tl-1) one cycle
Let the target displacement calculated in RXIII(0)-
As Rxho, E rxh −Rxh(n) −Rxhl(n−+)
The deviation E rxh is calculated based on, and then step 3
Proceed to 60.

In step 360, the absolute value of the deviation E rxh)
It is determined whether or not the JrQ value E rxhl or not, and when it is determined that Erxhl≦E rXhl, the process proceeds to step 390, and 1Erxhl≦ErX
If it is determined that it is not h1, step 37
Go to 0.

In step 370, with Tr as a time constant, Rxh
l(n) −1/ Tr ・E rxl+(n)+ R
]I collar position Rxl+ after correction based on xhl(n-+)
1(n) is calculated, and then the process proceeds to step 380.

In step 380, [one degree of melon Rxh is rewritten to the corrected value calculated in step 370,
After that, the process proceeds to step 400.

In step 390, flag Fxh is set to 1, and then the process proceeds to step 400.

Steps 400 to 460 are similar to steps 330 to 390 described above, except that in step 400 the pitch target value Rxp is calculated based on a map corresponding to the graph shown in FIG. Pitch target value R according to the procedure
xp is calculated, and then the process proceeds to step 470.

Steps 470 to 530 are similar to steps 330 to 390 described above, except that in step 470, the roll target value Rxr is calculated based on a map corresponding to the graph shown in FIG. The roll target value IRxr is calculated in the manner described above, and the process then proceeds to step 540.

In steps 540 to 590, Rxw(n) in step 550 executed first is a constant stored in ROM2O6, and Rxpl(o) (=RXI)
The warb target value Rxw is calculated in the same manner as steps 340 to 390 above, except that it is set to a constant close to O with the same sign as O), and then step 6
Go to 00.

Note that Rxw(n
) may be 0.

In step 600, the heap (Xxh
), pitch (XXI)), roll (Xxr), warp (
A displacement mode conversion calculation is performed for Xxw), and then the process proceeds to step 610.

Xxh −(XI +Xp) + (XI +X4
)Xxp=-(Xl+X2)+(XJ+X
4)Xxr-(XI-X2)+(XI-
X4 )Xxv −(XI −X2 ) (XI
X4) In step 610, the displacement mode deviation is calculated according to the following formula, and then step 6
Proceed to 20.

E xh −Ry: h −X xh E xp −Rxp −X XI) E xr −Rxr −X xr E xw −RXll/ −X
xv −0.

In step 620, PID compensation calculation for displacement feedback control is performed according to the following equation, and then the process proceeds to step 630.

Cxh −K pxh −E xh+ K lxh
I xh (n) + K dxh (E xh (n)
-E xh(n-n+)ICXI)-K pxp
II E l+ K IXI) I
xp(n) + K dxp (E xp(n) −E
xp(n-nJanuaryCxr -K pxr ・E xr
+ K Ixr I xr(n) + K dxr
(E xr(n) −E xr(n−n+ )ICx
w −K pxw eE )N/+ K lxw I
xw(n) 10K dxv (E xw(n) −E
xv(n-n1 month) In each of the above formulas, Ej(n) (
j=xh, xp, xr, xw) is the current Ej, and Ej(nn+) is the Ej nl cycles ago. Also, N(n) and Ij(n-1) are the current and one cycle previous Ij, respectively, and TX is the time constant, Ij(n) -Ej(n)+T x Ij(n
-1), and 1ljl with I j+*ax as a predetermined value.
≦I jmax. Furthermore, the coefficients Kpj, KljSK
dj (j=xhSxp.

xr, xw) are a proportional constant, an integral constant, and a differential constant, respectively.

In step 630, calculation of inverse transformation of the displacement mode is performed according to the following formula, and then in step 640
Proceed to.

Px + -1/4-Kx + (CXh-Cxp+C
xr+Cxw)Px = =I/411Kx: (C
xh-CXp-Cxr-Cxw)PX 3-1/4 ・
KX 3 (CXl1+ CXI)+ Cxr -CX
V) PX 4 = 1/4 KX 4 (Cxh
10CXI) -Cxr+Cxw)KX IKx 2
KX 3 and Kx 4 are proportionality constants.

In step 640, the longitudinal direction and lateral direction of the kosode are determined based on the longitudinal acceleration and lateral acceleration, respectively, based on the maps corresponding to the graphs shown in FIGS. 11 and 12 for the longitudinal direction and lateral direction of the vehicle, respectively. The pressure correction amounts Pga and PgI are calculated, and then step 6
Go to 50.

In step 650, the pitch (C
Gp) and roll (Cgr) are calculated for PD compensation of G feedback control, and then step 66
Go to 0.

Cgp-Kpgp-Pga+Kdgp (Pga(
n)-P ga(n-n tom)1 Cgr-Kpgr ・Pgl+Kdgr fPg
l(n)-pgl(n-nl)1 In each of the above equations, P ga(n) and PgJ(n) are the current Pga and Pgl, respectively, and P ga(n
-nl) and Pgl(n-rB) are Pga and Pgl, respectively, before the nI cycle. Further, K pgp and Kpgr are proportional constants, and K dgp and Kdgr are differential constants.

In step 660, step 1 of the flowchart of FIG.
The steering angle read in step 30 before the cycle is θ
The steering angular velocity θ is calculated according to θ-θ-θ' as ,
Thereafter, the process proceeds to step 670.

In step 670, a G-mode inverse conversion calculation is performed according to the following equation, and the process then proceeds to step 680.

Pg + -Kg + /411 (to -Cgp+!! [
'ψCgr+, f' -Gl) Pg: =Kg 2 /4 ・(-Cgp
-Kp r QCgr-, r Φ GI) Pg 3 -Kg 3 /4 ・ (Cgp+
2r ・1 r −GI to Cgr+) Pg 4 −Kg 4 /4 ・(2 r −Cgr− to Cgp−, r Italian Gl) Note that Kgl Kg=, KgJ, and Kg4 are proportional constants, respectively, and Klr and Klr, 2r and 2r are constants as distribution gains between the front and rear wheels, respectively.

In step 680, R, A in step 150
Pressure Pbj stored in M 208 and step 63
Based on the results calculated at 0 and 670, Put −
The 11-point control pressure Pul of each pressure control valve is calculated according to Pxi+Pgi+PI)1(1-1,2,3,4), and then the process proceeds to step 690.

In step 690, the 11-point flow to be supplied to each pressure control valve is calculated according to the following formula, and then the process proceeds to step 700.

11 −Ku I Pu 1 +Kh (Ps
r-Ps)-Kl・Pd-αIce-Ku! ! Pu 2 +Kh (
Psr-Ps )-Kl φ Pd -α 13 -Ku 3 PI 3 +Kh (P
sr-Ps)-Kl ・P'' 14 = Ku 4 Pu 4 +Kh (
Psr Ps ) - Kl Pd KuI Ku2, Ku3, Kua are proportionality constants for each wheel, Kh and 1 are correction coefficients for the pressure in the high-pressure flow path and the pressure in the low-pressure flow path, respectively, and α
is a correction constant between the front and rear wheels, and Psr is a reference pressure in the high pressure flow path.

In step 700, a temperature correction coefficient KL is calculated based on the temperature T of the working fluid read in step 30 and a map corresponding to the graph shown in FIG. -1, 2, 3, 4), temperature correction calculation of the target current is performed, and then the process proceeds to step 710.

In step 710, Iw-(111-1tp) (It43-1t4)
According to the current warp (amount of twist around the longitudinal axis of the vehicle body)
is calculated, and then the process proceeds to step 720.

In step 720, the deviation of the current warp is calculated according to the formula F with Riw as the target current warp,
Thereafter, the process proceeds to step 730.

Eiw-Rlw-1w Note that the target current warp R1w in the above equation may be O.

In step 730, the current warb target control amount is calculated according to E Iwp - K iwp ΦElv, with Klwp being a proportionality constant, and then the process proceeds to step 740.

In step 740, an inverse transform of the current warp is calculated according to the following equation, and then the process proceeds to step 750.

Iw + −Elwp /4 1w! ! --Elvp /4 Iw 3 = -Eivp /4 Iw 4 = EiVI) /4 In step 750, based on the results calculated in steps 700 and 740, the pressure is supplied to each pressure control valve according to the following formula. The final target current 1ul to be achieved is calculated,
Thereafter, the process proceeds to step 170 in FIG.

I ul -1 tl+ I wl (l-1, 2, 3, 4) Thus, according to this embodiment, when the pressure Ps in the high-pressure flow path is less than the predetermined value Pc, the working fluid chamber of each actuator The pressure is controlled to the standby pressure Pbl calculated in step 150. When the pressure in the high-pressure flow path exceeds a predetermined value Pc, the pressure in the working fluid chamber of each actuator is controlled to the standby pressure, and is then controlled to a pressure determined according to the vehicle running state by feedback control of the vehicle height. In the process of transitioning to active control, by executing steps 300 to 590,
Each target value Rxh of heap, pitch, roll, and warb,
Rxp, Rxr, and Rxv are gradually changed from the corresponding values in the standby pressure control stage to values that are determined by the vehicle's running condition, so that the pressure in the working fluid chamber of each actuator is changed from the standby pressure to a value that is determined by the vehicle's running condition. This avoids a sudden change in the pressure in the working fluid chamber of each actuator and a sudden change in the posture of the small body caused by this.

In the above embodiment, the standby pressure Pbl is calculated in step 150, and the standby pressure current 1bi supplied to each pressure control valve based on the calculation result corresponds to the graph shown in FIG. After the standby pressure Pb1 is calculated in step 150 and the flag Fs is set to 1 in step 160, the pressure Pbl is rewritten to the target pressure Pul. Thereafter, the process may be configured to proceed to step 690.

Further, in the above embodiment, the standby pressure Pbl is calculated from the vehicle height detected by the vehicle height sensor based on the map corresponding to the graph shown in FIG. 199 r'L.

The standby pressure may be set by rewriting the pressure pi in the working fluid chambers 2PL, 2PR, 2RL, and 2RR detected by 199FR, 199RL, and 199RR to the standby pressure Pbl in step 150, respectively.

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.

Effects of the Invention According to the present invention, the pressure control means is controlled so that the control pressure is substantially equal to the pressure within the corresponding actuator at least until the supply pressure of the working fluid exceeds a predetermined value, and the supply pressure is When the predetermined value is exceeded, the control pressure is controlled by feed pack control based on the vehicle height detected by the vehicle height detection means to reach the standard pressure, and the target pressure is maintained until the target pressure exceeds the predetermined value. Since the pressure in the corresponding actuator is gradually changed to a value determined by the driving condition of the vehicle, the pressure in the actuator is controlled by the standby force and then active control. Even when the active control starts, the pressure in each actuator is controlled to gradually change from the standby f pressure to a predetermined 1" standard pressure depending on the running condition of the middle wheel, and this causes the vehicle body to It is possible to reliably reduce sudden changes in posture to 1.
.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram showing a fluid circuit of one embodiment of a hydraulic active suspension according to the present invention, FIG. 2 is a block diagram showing an electrical control device of the embodiment shown in FIG. 1, and FIG. 3 is a flowchart showing the control flow achieved by the electric control device shown in FIG. 2;
The figure is a graph used to calculate the current Tb supplied to the Kuinokusu valve (at the start of operation of the fluid active suspension). A graph showing the relationship between high Hi and the standby pressure in the working fluid chamber of the corresponding actuator. Figures 7A to 7D are flowcharts showing the active calculation routine performed in step 150 of the flowchart shown in Figure 3; The diagram shows vehicle speed V and target displacement QRx
A graph showing the relationship between h and Fig. 9 is the longitudinal acceleration Ga
and the target displacement amount RXI), the first graph shows the relationship between
Figure 0 is a graph showing the relationship between lateral acceleration Gl and 1-mark displacement RXr, Figure 11 is a graph showing the relationship between longitudinal acceleration Ga and pressure correction Pga, and Figure 12 is a graph showing the relationship between longitudinal acceleration Ga and pressure correction Pga. 13 is a graph showing the relationship between lateral acceleration G1 and pressure supplementary W component Pgl; FIG. 13 is a graph showing vehicle speed V and steering coefficient; FIG.
The figure is a graph C showing the relationship between the temperature T of the working fluid and the correction coefficient Kt. 1 PI? , I PCll 1? R, 1, R1□・
・Actuator, 2Fl? ,2Fi,,2I? R,2
RL... Working fluid chamber, 4... Reserver, 6.
... pump, 8 ... filter, 10 ... suction channel,
12...Drain passage 114...Engine, 16...
Rotation speed sensor, 18... High pressure flow path, 20... Check valve, 22... Attenuator 24.26... Accumulator, 32.34.36.38... Pressure control valve. 4(), 42.44.46... switching control valve, 48.
...Low pressure flow path, 52...Fixed throttle, 54...++J
Variable throttle, 56... Connection flow path, 58... Solenoid, 6
6.68.70...Fixed aperture, 72.74.76...
・Variable aperture. 78.80.82... Solenoid, 84.86.88
... Connection channel, 110-118... Drain channel, 1
20...Filter, 124-130...Aperture, 13
2-138...Accumulator, 144FR, 1
,44F+,,144RR,144RI,...Vehicle height sensor, 150-156...Shutoff valve, 166-172.
...Relief valve, 174...Oil cooler 176.
...Filter, 180...Relief valve, 182...
Filter, ]84...Aperture. 186...Solenoid on/off valve, 190...Solenoid, 1
92...Opening/closing valve, 1.96・t ipes valve, i, 97
．． , 198.199PR, 199FL, i-99RR,
1,99RL...pressure sensor, 200...electric control device, 202...microcomputer, 204...
・CPU, 206...ROM, 208...RAM,
210... Input port device, 212... Output port device, 216... ■GSW, 218... EMSW,
220-230... Drive circuit, 232... Display device,
234... Vehicle speed sensor, 236... Front and rear G sensor,
238...1 yellow G sensor, 240...steering angle sensor, 248...vehicle height setting switch Patent applicant
Toyota Motor Corporation Representative Patent Attorney Akashi RokiFigure 8 Figure 10 Figure 1 Figure ga Figure 12 gl Figure 4, Plate iT

Claims (1)

[Claims] Vehicle height detection means for detecting the vehicle height of a portion corresponding to each wheel, a fluid pressure actuator disposed between each wheel and the vehicle body, and a working fluid supply passage that supplies working fluid at supply pressure to the actuator. a working fluid discharge passage for discharging the working fluid from the actuator; and a shutoff that is provided in the middle of the working fluid supply passage and the working fluid discharge passage and closes in response to the supply pressure being equal to or less than a predetermined value. a valve; a pressure control means provided in the middle of the working fluid supply passage and the working fluid discharge passage for controlling the supply and discharge of working fluid to the corresponding actuator and controlling the pressure within the actuator; The pressure control means is controlled so that the control pressure of the pressure control means is substantially equal to the pressure in the actuator until the pressure exceeds the predetermined value, and when the supply pressure exceeds the predetermined value, the vehicle height control means for controlling the pressure control means so that the control pressure of the pressure control means becomes a target pressure by feedback control based on the vehicle height detected by the detection means, and the target pressure is set so that the supply pressure is the predetermined value. The hydraulic active suspension is configured to gradually change from a value substantially equal to the pressure in the actuator up to a value determined by the driving state of the vehicle.