JPH0764176B2 - 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, for example, JP-A-62-295714 and JP-A-63-2427 are known.
As described in Japanese Patent Publication No. 07, the fluid pressure in the fluid pressure actuator arranged between each wheel and the vehicle body is controlled based on the detection result of the lateral acceleration detecting means, and when the vehicle turns, etc. 2. Description of the Related Art Active suspensions that are configured to suppress or reduce changes in the posture of a vehicle body have been conventionally known.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention In such a conventional active suspension, when the vehicle travels on a bad road, runs on a chain, or when the door is opened / closed comparatively violently, the lateral acceleration sensor needs unnecessary lateral acceleration. Is detected, and therefore, erroneous control is performed in which the fluid pressure is controlled in spite of the fact that it is not necessary to control the fluid pressure in the actuator, and an unnatural swing of the vehicle body may occur.

The present invention has been made in view of the above-mentioned problems in the conventional active suspension configured so that the fluid pressure in the actuator is controlled based on the detection result of the lateral acceleration detecting means, and is caused by the erroneous detection of the lateral acceleration detecting means. Paying attention to the fact that unnecessary posture control is mainly performed when the vehicle is traveling at low speed or at a standstill, and unnatural shaking of the vehicle body may occur even when the vehicle travels on a rough road at low speed. It is an object of the present invention to provide an improved fluid pressure type 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. A vehicle speed detecting means; an acceleration detecting means for detecting the acceleration of the vehicle body; and a control means for correcting and controlling the pressure adjusting means with a correction amount of a predetermined gain based on the acceleration detected by the acceleration detecting means. The predetermined gain is set to have a dead zone, and in a region where the vehicle body acceleration exceeds the dead zone, the predetermined gain is set to increase gradually as the magnitude of the vehicle body acceleration increases, and the vehicle speed detected by the vehicle speed detecting means is This is achieved by a hydraulic active suspension configured such that the lower the dead zone width is increased.

As described above, the erroneous control in the conventional active suspension is mainly performed when the vehicle is running at a low speed or is stopped. According to the above configuration, the pressure adjusting means is correction-controlled by the control means with a correction amount of a predetermined gain based on the acceleration detected by the acceleration detecting means, and the predetermined gain has a dead zone and the acceleration of the vehicle body is in the dead zone. In the region exceeding .gamma., It is set so as to gradually increase as the magnitude of the acceleration of the vehicle body increases, and the width of the dead zone increases as the vehicle speed decreases.

Therefore, even if the vehicle is traveling at a low speed on a bad road or traveling with a chain attached, or when the vehicle is relatively stopped and the door is relatively opened and closed, and the acceleration of the vehicle body is erroneously detected by the lateral acceleration detecting means, Since the correction control based on the acceleration is not performed, it is possible to prevent the unnatural swing of the vehicle body due to the unnecessary control of the fluid pressure in the actuator. In addition, since the magnitude of the acceleration of the vehicle body when turning or accelerating / decelerating at low speed is smaller than that when turning or accelerating / decelerating at high speed, when the vehicle is turning without correction control based on acceleration. The posture of the car body in the car does not deteriorate significantly.

Further, according to the above configuration, the predetermined gain is set to gradually increase as the magnitude of the vehicle body acceleration increases in the region where the vehicle body acceleration exceeds the dead zone. Even if the acceleration of the vehicle body fluctuates above and below the threshold value of the dead zone of the gain, the correction control amount based on the acceleration of the vehicle body does not change suddenly regardless of the vehicle speed. It is possible to improve control performance and riding comfort.

In addition, during medium to high speed traveling, where a relatively large change in posture of the vehicle body occurs, such as when turning is performed at a relatively high vehicle speed, the width of the dead band of the gain is set to the original width. Attitude control is performed with a control amount necessary and sufficient to effectively suppress changes in the vehicle body attitude due to acceleration, so the attitude control performance of the vehicle body is not impaired, and good maneuvering stability during mid-high speed traveling is achieved. It is possible to reliably prevent adverse effects.

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 in the figure are actuators 1FR, 1FR provided corresponding to the right front wheel, left front wheel, right rear wheel and left rear wheel of the vehicle, which are not shown in the figure, respectively.
FL, 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 passage 18F and one end of the rear wheel high pressure passage 18R are connected to the high pressure passage 18, and accumulators 24 and 26 are connected to these high pressure passages, respectively. Each of these accumulators is filled with high-pressure gas, absorbs pressure pulsation of the working fluid, and is used for accumulating 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. Has become A low-pressure passage 48FR is connected to the R port of the switching control valve 40, and a connection passage 56 is connected to the A port. The switching control valve 4 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 the pressure.
When it is higher than Pa, it is switched to the switching position 40a which connects and connects the port P and port A, and when the pressures Pp and Pa are equal to each other, the switching position 40 which blocks communication of all the ports.
When the pressure Pp is lower than the pressure Pa, the pressure is switched to the switching position 40c for connecting the ports R and A to each other. In addition, the variable diaphragm 54 is the Sonorade
The effective passage cross-sectional area of the throttle is changed by controlling the electric current supplied to 58, whereby the pressure Pp is changed 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, and the variable diaphragms 72 to 76 are Sonorade 78, 80, 82, respectively. have.

Further, the switching control valves 42, 44, and 46 are configured similarly to the switching control valve 40, and the R ports of the switching control valves 42, 44, and 46 are low-pressure passage 48FL for the left rear wheel, low-pressure passage 48RR for the right rear wheel, and left rear, respectively. One end of the wheel low-pressure flow path 48RL is connected, and one end of each of the connection flow paths 84, 86, 88 is connected to the A port. The switching control valves 42 to 46 are spool valves that take in the pressure Pp in the flow passages 60 to 64 between the corresponding fixed throttle and the variable throttle and the pressure Pa in the corresponding connecting flow passages 84 to 88 as pilot pressures. And when the pressure Pp is higher than the pressure Pa, the switching positions 42a, 44a, 46 for connecting the port P and the port A in communication.
Switching positions 42b, 44b, 46b that switch to a and shut off communication of all ports when pressures Pp and Pa are equal to each other
, And when the pressure Pp is lower than the pressure Pa, the port R
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 cylinders 106FR, 106FL,
Working fluid chambers 2FR, 2FL, 2RR, 2 in cooperation with 106RR and 106RL and their corresponding cylinders
It consists of pistons 108FR, 108FL, 108RR, 108RL that define the RL, each connected to a vehicle body not shown in the figure by a cylinder, and not shown in the figure at the tip of the rod portion of the pistane. It is connected to the suspension arm. Although not shown in the figure, a suspension spring is mounted between the upper seat fixed to the rod portion of the piston and the lower seat fixed to the cylinder.

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

The working fluid chambers 2FR, 2FL, 2RR, 2RL have throttles 124, 1 respectively
Accumulators 132, 134, 136, 1 through 26, 128, 130
38 is connected. Also piston 108FR, 108FL, 108R
Flow paths 140FR, 140FL, 140RR, 140RL for R and 108RL, respectively.
Is provided. These flow passages connect the corresponding flow passages 56, 84 to 88 and the working fluid chambers 2FR, 2FL, 2RR, 2RL in communication with each other, and filters 142FR, 142FL, 142R are provided on the way, respectively.
It has R and 142 RL. Actuators 1FR, 1FL,
A vehicle height sensor for detecting the vehicle heights XFR, XFL, XRR, and XRL of the parts corresponding to the wheels, respectively, at positions close to 1RR and 1RL.
144FR, 144FL, 144RR, 144RL are provided.

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 flow path in the corresponding connection flow path is 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 the solenoid valve 190 is excited and the 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 the pressure on the high-pressure flow path 18R side is higher than that of the throttle 184. Sometimes 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 in the working fluid chambers 2FR, 2FL, 2RR, and 2RL are detected by these pressure sensors, respectively. Further, the reserve tank 4 is provided with a temperature sensor 195 for detecting the temperature T of the guidance fluid stored in the tank.

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
Of the working fluid temperature T from the temperature sensor 195, signals from the pressure sensors 197 and 198 showing the pressure Ps in the high-pressure passage and pressure Pd from the low-pressure passage, and the pressure sensor 199FR. , 199FL, 199RR, 199RL, the pressure Pi of 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. ROM206 is shown in FIGS. 3 and 6A to 6C.
The control flow shown in FIG. 10 and FIG. 4 and FIG.
The maps shown in FIG. 7 to FIG. 9 and FIG. 11 to FIG. 14 are stored, and the CPU processes signals based on each control flow. The output port device 212 outputs a control signal to the electromagnetic opening / closing valve 186 via the drive circuit 220 according to the instruction of the CPU 204, and the pressure control valves 32 to 38 via the drive circuits 222 to 228.
In detail, variable aperture 54, 72, 74, 76 Sonorade
The control signal is output to 58, 78, 80 and 82, and the control signal is output to the display device 232 via the drive circuit 230.

Next, the operation of the illustrated embodiment will be described with reference to the flowchart 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 a standby pressure Pbi (i = 1, 2, 3, 4) of the pressure control valves 32 to 38 described later. 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 21, a main relay (not shown) is turned on, and then step 20 is proceeded to.

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

In step 30, a signal indicating the rotation speed N of the engine 14 detected by the rotation speed sensor 16, a signal indicating the temperature T of the working fluid detected by the temperature sensor 195, and pressure sensors 197 and 198, respectively. Pressure in high pressure channel
Ps and a signal indicating the pressure Pd in the low-pressure channel, pressure sensor 199F
Working fluid chamber 2F detected by L, 199FR, 199RL, 199RR
L, 2FR, 2RL, a signal indicating the pressure Pi in 2RR, a signal indicating whether the ignition switch 216 is in the ON state, a signal indicating the vehicle height Xi detected by the vehicle height sensors 144FL, 144FR, 144RL, 144RR A signal indicating the vehicle speed V detected by the vehicle speed sensor 234, a signal indicating the longitudinal acceleration Ga detected by the longitudinal G sensor 236, a signal indicating the lateral acceleration G1 detected by the lateral G sensor 238, detected by the steering angle sensor 240 The signal that indicates the steering angle θ and the signal that indicates whether the mode set by the vehicle height setting switch 248 is the high mode or the normal mode are read, and then the process proceeds to step 40.

In step 40, it is determined whether or not the ignition switch is in the off state, and when it is determined that the ignition switch is in the off state, the process proceeds to step 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. If it is determined that the engine is not operating, step 90 is performed.
If 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, based on the map corresponding to the graph shown in FIG. 4 in which the current Ib applied to the solenoid valve 190 of the solenoid valve 186 of the bypass valve 196 is stored in the ROM 206. 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 valve 190 of the solenoid 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 14 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, 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 does not exceed 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 6, 74 Sonorade 78, 58, 82, 80
(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 valve 186 of Sonorade 190
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, the control flow shown in FIG. 3 is terminated, and the power supply to the electric control device 200 shown in FIG. 2 is stopped. 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 14.

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 820.

_{Xxh = (X 1 + X 2} ) + (X 3 + X 4) Xxp = - (X 1 + X 2) + (X 3 + X 4) Xxr = (X 1 -X 2) + (X 3 -X 4) Xxw = (X ₁ -X ₂₎ - Te is at the (X ₃ -X ₄₎ step 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, displacement feedback control PID compensation calculation is performed according to the following equation, and then step 3
Proceed to 40.

Cxh = Kpxh · Exh + Kixh · Ixh (n) + Kdxh {Exh (n) -Exh (n-n 1)} Cxp = Kpxp · Exp + Kixp · Ixp (n) + Kdxp {Exp (n) -Exp (n-n 1)} cxr = Kpxr · Exr + Kixr · Ixr (n) + Kdxr {Exr (n) -Exr (n-n 1)} Cxw = Kpxw · Exw + Kixw · Ixw (n) + Kdxw {Exw (n) -Exw (n-n 1)} Note Te at the above formulas, Ej (n) (j = xh, xp, xr, xw) are the current Ej, Ej (n-n ₁₎ is Ej of n ₁ cycles before. Ij (n) and Ij (n-1) are Ij at the present time and one cycle before, respectively, and Tx is a time constant, and Ij (n) = Ej (n) × Tx + Ij (n-1), and Ijmax is predetermined. As a value, | Ij | ≦ Ijmax. 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 340, the inverse transformation of the displacement mode is calculated according to the following equation, and then the process proceeds to step 350.

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 350, pressure corrections Pga and Pgl in the longitudinal and lateral directions of the vehicle are calculated based on the longitudinal acceleration and lateral acceleration, respectively, according to the routine shown in FIG. 10, and then the routine proceeds to step 360.

In step 360, the pitch (Cgp) is calculated according to the following formula.
The PD compensation calculation of the G feedforward control is performed for the roll and the roll (Cgr), and then the process proceeds to step 370.

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

In step 370, the steering angle velocity is calculated according to = θ−θ ′, where θ ′ is the steering angle read in step 30 one cycle before in the flowchart of FIG. 3, and the steering angle velocity and the vehicle speed V are used. Based on the map corresponding to the graph shown in FIG. 13, the rate of change of the predicted lateral G, that is, Is calculated, and then the process proceeds to step 380.

In step 380, the G-mode inverse conversion operation is performed according to the following equation, and then the process proceeds to step 390.

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 390, based on the pressure Pbi stored in the RAM 208 in step 150 and the result calculated in steps 340 and 380, 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 400.

In step 400, 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 410.

I ₁ = Ku ₁ Pu ₁ + Kh (Psr-Ps) -Kl · Pd-α I ₂ = Ku ₂ Pu ₂ + Kh (Psr-Ps) -Kl · Pd-α I ₃ = Ku ₃ Pu ₃ + Kh (Psr-Ps ) −Kl ・ Pd I ₄ ＝ Ku ₄ Pu ₄ ＋ Kh (Psr−Ps) −Kl ・ Pd where 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 410, 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. 14, and Iti = KtIi ( i = 1, 2, 3, 4), the target current temperature correction calculation is performed, and then the process proceeds to step 420.

In step 420, the current warp (the amount of twist around the longitudinal axis of the vehicle body) according to Iw = (It ₁ −It ₂ ) − (It ₃ −It ₄ ).
Is calculated, and then the process proceeds to step 430.

In step 430, the deviation of the warp is calculated according to the following equation using Riw as the target current warp, and then the process proceeds to step 440.

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

In step 440, the current warp target control amount is calculated according to Eiwp = KiwpEiw using Kiwp as a proportional constant, and then the process proceeds to step 450.

In step 450, the inverse calculation of the current warp is performed according to the following equation, and then the process proceeds to step 460.

Iw ₁ = Eiwp / 4 Iw ₂ = -Eiwp / 4 Iw ₃ = -Eiwp / 4 Iw ₄ = Eiwp / 4 In step 460, based on the results calculated in steps 410 and 450, the following formula 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) Next, the calculation of the correction amounts Pga and Pgl of the pressure performed in step 350 will be described with reference to FIGS. 10 to 12.

First, in step 510, based on the map corresponding to the graph shown in FIG. 11, in the following steps 550 and 560, the correction of the pressure in the front-rear direction calculated as shown in FIG. 15 is performed. The dead zone width A of the longitudinal acceleration Ga is calculated for the minute Pga, and then the process proceeds to step 520.

In step 520, it is determined whether or not the absolute value of the longitudinal acceleration Ga is less than or equal to the reference value A calculated in step 510, and it is determined that the absolute value of Ga is less than or equal to A. If so, the routine proceeds to step 540, and if it is determined that the absolute value of Ga is not less than A, then the routine proceeds to step 530.

In step 530, it is determined whether or not the absolute value of the longitudinal acceleration Ga is a positive constant a ₁ or less, and the absolute value of Ga is a ₁
When it is determined that the following is true, the process proceeds to step 550, and when it is determined that the absolute value of Ga is not less than or equal to a ₁ , the process proceeds to step 560.

In step 540, the correction amount Pga in the front-rear direction is 0.
Is set, and then proceed to 570.

In step 550, the correction amount Pga of the pressure in the front-rear direction is calculated according to the following equation, and then the process proceeds to step 570.

Pga ＝ SGN （Ga） × Pa （Ga） Here In step 560, the correction amount Pga of the pressure in the front-rear direction is calculated according to the following equation, and then the process proceeds to step 570.

Pga ＝ SGN （Ga） × Qa （Ga） Here Naoshiki At a (1) and (2), a ₂ and b ₁ are positive constants, SGN (Ga) = - a 1 (Ga <0) = 1 (Ga> 0).

In step 570, based on the map corresponding to the graph shown in FIG. 12, steps 610 and 620 described later are executed.
The dead zone width B of the lateral acceleration Gl for the lateral pressure correction Pgl calculated as shown in FIG. 16 is calculated, and then the routine proceeds to step 580.

In step 580, the absolute value of lateral acceleration Gl is calculated in step 5
When it is determined whether the absolute value of Gl is less than or equal to the reference value B calculated in 70, and when it is determined that the absolute value of Gl is less than or equal to B, the routine proceeds to step 600, where the absolute value of Gl is B. When it is determined that the following is not true, the process proceeds to step 590.

In step 590, the absolute value of the lateral acceleration Gl is a positive constant c.
_When it is determined whether the absolute value of G1 is ₁ or less, and when it is determined that the absolute value of G1 is c ₁ or less, the process proceeds to step 610, and it is determined that the absolute value of Gl is not c ₁ or less. If so, proceed to step 620.

In step 600, the lateral pressure correction amount Pgl is set to 0, after which the process proceeds to step 360 in FIG. 6B.

In step 610, the lateral pressure correction amount Pgl is calculated according to the following equation, and then the process proceeds to step 360.

Pgl = SGN (Gl) × Pl (Gl) Here In step 620, the lateral pressure correction amount Pgl is calculated according to the following equation, and then the process proceeds to step 360.

Pgl = SGN (Gl) × Ql (Gl) Here In the formulas (3) and (4), c ₂ and d ₁ are positive constants, and SGN (Gl) =-1 (Gl <0) = 1 (Gl> 0).

Thus, according to the illustrated embodiment, FIG. 15 and FIG.
As shown in Fig. 16, longitudinal acceleration Ga and lateral acceleration Gl
The respective correction amounts Pga and Pgl of the pressure are calculated on the basis of the above. In this case, the widths A and B of the dead zones are increased as the vehicle speed becomes lower, whereby the correction control based on the acceleration with respect to the pressure in the working fluid chamber of the actuator is performed. The lower the vehicle speed, the greater the range where the operation is not performed. Therefore, even if the vehicle runs on a rough road at low speed or runs on a chain, or the door is opened / closed comparatively violently when the vehicle is stopped, and the acceleration sensor detects acceleration due to these, the erroneous operation of the active suspension may occur. It is possible to prevent unnatural shaking of the vehicle body caused by unnecessary control of the pressure in the working fluid chamber.

Even if the dead zone widths A and B are increased or decreased according to the vehicle speed V, if the magnitudes of the longitudinal acceleration Ga and the lateral acceleration Gl exceed the dead zone thresholds, the pressure correction amounts Pga and Pgl are increased.
Is calculated according to the above equations, the pressure correction does not change abruptly even if the magnitude of acceleration fluctuates above and below the dead zone threshold, and therefore, for example, the graphs shown in FIGS. 15 and 16 are used. In the map corresponding to, the lower the vehicle speed, the dead zone width A
And B are increased, and the acceleration in the region exceeding the dead zone threshold is not corrected according to the above equations but is calculated as it is according to the original map value. The posture can be controlled well and the riding comfort of the vehicle can be improved.

Further, since the magnitudes of the longitudinal acceleration and lateral acceleration of the vehicle body when turning or accelerating / decelerating at a lower speed are smaller than those at a high speed, even if the correction amount of pressure is calculated to be 0 or a small value, it is possible to turn the vehicle when turning. The posture of the vehicle body in this case does not deteriorate significantly.
When turning or accelerating / decelerating at high speed, the dead zone widths A and B are set small, and the optimum pressure correction amount is calculated according to the acceleration of the vehicle body. It is possible to effectively control changes in the posture of the vehicle body.

The pressure corrections Pga and Pgl are three-dimensional maps having the longitudinal acceleration Ga and the vehicle speed V, the lateral acceleration Gl and the vehicle speed V as parameters, respectively. The lower the vehicle speed, the widths A and B of the dead zones.
May be calculated based on a three-dimensional map that is set to increase.

Further, in the above-described embodiment, both the dead zone widths A and B are increased as the vehicle speed becomes lower, but only the lateral acceleration dead zone width B may be increased.

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

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing a fluid circuit of one embodiment of a fluid pressure type active suspension according to the present invention, FIG. 2 is a block diagram showing an electric control device of the embodiment shown in FIG. FIG. 3 is a flow chart showing a control flow achieved by the electric control device shown in FIG.
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 supplied to each pressure control valve. 6 to 6C are flow charts showing the active calculation routine executed 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
FIG. 9 is a graph showing the relationship between the longitudinal acceleration Ga and the target displacement amount Rxp, FIG. 9 is a graph showing the relationship between the lateral acceleration Gl and the target displacement amount Rxr, and FIG. 10 is FIGS. 6A to 6C. FIG. 11 is a flow chart showing a routine for calculating the target pressure Pga in the front-rear direction and the target pressure Pgl in the lateral direction, which is performed in step 350 of the flow chart shown in FIG. 11, and FIG. 11 is a correction amount Pga of the vehicle speed V and the front-rear direction pressure. Fig. 12 is a graph showing the relationship between the dead band width A in the calculation of Fig. 12 and Fig. 12 is a graph showing the relationship between the vehicle speed V and the dead band width B in the calculation of the lateral pressure correction amount Pgl. , Fig. 13 shows the rate of change of vehicle speed V, steering angular velocity, and predicted lateral acceleration. Fig. 14 is a graph showing the relationship between
15 is a graph showing the relationship between the acceleration and the correction coefficient Kt, FIG. 15 is a graph showing the relationship between the longitudinal acceleration Ga and the correction amount Pga of the longitudinal pressure, and FIG. 16 is the lateral acceleration Gl and the lateral pressure. 6 is a graph showing the relationship between the correction amount Pgl and Pgl. 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 ...... Sonolaid, 66, 6
8, 70 …… Fixed aperture, 72, 74, 76 …… Variable aperture, 78, 80, 8
2 …… Sonolaid, 84,86,88 …… Connecting channel, 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 …… Throttle, 186 …… Solenoid on-off valve, 190 …… Sonorade, 192 …… On-off 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, 2
20-230 …… Drive circuit, 232 …… Indicator, 234 …… Vehicle speed sensor, 236 …… Front and rear G sensor, 238 …… Horizontal 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 Co., Ltd. (72) Inventor: Takashi Yonekawa 1, Toyota Town, Aichi Prefecture, Toyota Motor Corporation ( 72) Inventor Toshio Onuma 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Corporation (72) Inventor Toshiaki Hamada 2-1, Asahi Town, Kariya City Aichi Prefecture Aisin Seiki Co., Ltd. (72) Inventor Koichi Kokubo Aisin Seiki Co., Ltd., 2-1-1 Asahi-cho, Kariya city, Aichi (56) Reference JP-A-63-227411 (JP, A) JP-A-62-261513 (JP, A) JP-A-59-120508 ( 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, a vehicle speed detecting means, and an acceleration detecting means for detecting an acceleration of the vehicle body. Means and a control means for correcting and controlling the pressure adjusting means with a correction amount of a predetermined gain based on the acceleration detected by the acceleration detecting means, and the predetermined gain has a dead zone and the acceleration of the vehicle body is In the region exceeding the dead zone, the dead zone is set so as to gradually increase as the magnitude of the acceleration of the vehicle body increases, and the width of the dead zone increases as the vehicle speed detected by the vehicle speed detecting means decreases. Fluid pressure active suspension.