JPH02279408A - Fluid pressure type active suspension - Google Patents

Abstract

PURPOSE:To prevent malfunction of an active suspension due to false detection of acceleration by controlling pressure regulating means by means of the correction amount based on acceleration when the acceleration exceeds a blind zone, forming the suspension so that the width of the blind zone is increased with decreasing the car speed. CONSTITUTION:With a suspension in the title, accumulators 132 - 138 are connected through restrictors 124 - 130 to working fluid chambers 2FR - 2RL partitioned by pistons of actuators 1RF - 1RL provided to every wheel. The supply and exhaust of a working fluid to respective working fluid chambers 2FR - 2RL are controlled through pressure control valves 32 - 38. In this case, the pressure control valves 32 - 38 are correctively controlled by means of the correction amount based on the acceleration at that time when the acceleration detected by an acceleration sensor exceeds a blind zone. Further, the width of the blind zone is adapted to increase as the car speed detected by a car speed sensor decreases. Malfunction of the active suspension during travelling of the car at low speeds can thus be prevented.

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.

BACKGROUND ART As one type of active suspension for vehicles such as automobiles, as described in, for example, Japanese Patent Application Laid-Open No. 62-295714 and Japanese Patent Application Laid-open No. 63-242707, a suspension system is provided between each wheel and the vehicle body. Conventionally, active suspensions are configured to control the fluid pressure in the fluid pressure actuator based on the detection results of the lateral acceleration detection means, thereby suppressing or reducing changes in the posture of the vehicle body when the vehicle turns. Are known.

Problems to be Solved by the Invention In the conventional active suspension system, when the vehicle is driving on a rough road or with a chain attached, or when the door is opened and closed relatively vigorously, the lateral acceleration sensor detects unnecessary lateral acceleration. As a result, erroneous control is performed to control the fluid pressure in the actuator even though there is no need to control the fluid pressure, which may result in unnatural shaking of the vehicle body.

The present invention has been developed in view of the above-mentioned problems in conventional active suspensions in which the fluid pressure in the actuator is controlled based on the detection result of the lateral acceleration detection means, and also because of the erroneous detection of the lateral acceleration detection means. Focusing on the fact that this is mainly caused when the vehicle is driving at low speeds or when it is stopped, we have developed an improved hydraulic active system that prevents unnatural shaking of the vehicle body even when the vehicle is driving at low speeds on rough roads. The purpose is to provide suspension.

Means for Solving the Problems According to the present invention, the above-mentioned objects include: a fluid pressure actuator disposed between each wheel and a vehicle body; a pressure adjustment means for adjusting the fluid pressure in the actuator; a vehicle speed detecting means; an acceleration detecting means for detecting acceleration of the vehicle body; and a control means for correcting and controlling the pressure adjusting means with a correction amount based on the acceleration when the acceleration detected by the acceleration detecting means exceeds a dead zone. This is achieved by a hydraulic active suspension configured such that the width of the dead zone increases as the vehicle speed detected by the vehicle speed detection means decreases.

Functions and Effects of the Invention As described above, in the conventional active suspension, erroneous control is performed mainly when the vehicle is running at low speed or when the vehicle is stopped. According to the above configuration, when the acceleration detected by the acceleration detecting means exceeds the dead zone, the pressure adjusting means is corrected by a correction amount based on the acceleration, and the lower the vehicle speed, the wider the dead zone. Therefore, even if the vehicle is driven at low speed on a rough road or with chains attached, or if the door is opened and closed relatively harshly while the vehicle is stopped, and the lateral acceleration detection means erroneously detects acceleration, the acceleration Since the base correction control is not performed, it is possible to prevent unnatural shaking of the vehicle body due to inappropriate control of the fluid pressure within the actuator.

Furthermore, during medium-high speed driving where relatively large changes in vehicle body posture occur, such as when turning at relatively high vehicle speeds, correction control of fluid pressure based on acceleration is performed without any problems, so that the vehicle body posture can be adjusted. Control performance is not impaired.

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 active suspension shown in the figure is an actuator 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.
l, I PL, I RR, 1) has IL,
Each of these actuators has a working fluid chamber 2Fl?
, 2PL, 2RR, and 2RL.

In the figure, 4 indicates a reserve tank that stores hydraulic oil as a working fluid.
0 communicates with the suction side of the pump 6. A drain passage 12 is connected to the pump 6 for collecting working fluid leaked inside the pump 6 into the reserve tank 4. The pump 6 is rotationally driven by an engine 14, and the rotation speed of the engine 14 is detected by a rotation speed sensor 16.

A high pressure flow path 18 is connected to the discharge side of the pump 6.

A check valve 20 is provided in the middle of the high-pressure flow path 18 to allow only the flow of working fluid from the pump toward each actuator, and between the pump 6 and the check valve 20, the working fluid discharged from the pump is provided. An attenuator 22 is provided to absorb pressure pulsations and reduce pressure changes. The high pressure flow path 18 includes a front wheel high pressure flow path 18F and a rear wheel high pressure flow path 1.
8R is connected to one end, and accumulators 24 and 26 are connected to these high pressure channels, respectively.

Each of these accumulators has a high pressure gas sealed therein so as to absorb pressure pulsations of the working fluid and perform a pressure accumulating function.

Also, high pressure channels 18F and 181? are connected to one end of a high pressure flow path 18FR for the right front wheel, a high pressure flow path 18PL for the left front wheel, a high pressure flow path 18RR for the right rear wheel, and a high pressure flow path 18RL for the left rear wheel, respectively. High pressure flow path 18PI? .

18FL, 18I? There are filters 28Fl in the middle of R and 18RL, respectively. , 28PL, 28R1? , 2
81? The other ends of these high-pressure channels are pilot-operated three-boat switching control valves 40.42.44.4 of the pressure control valves 32.34.36.38, respectively.
It is connected to 6 P boats.

The pressure control valve 32 is connected to a switching control valve 40 and a high pressure flow path 18P.
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 passage 48PR is connected to the R port of the switching control valve 40, and a connection passage 56 is connected to the A boat. The switching control valve 40 has a fixed throttle 52 and a variable throttle 54.
It is a spool valve that takes in the pressure Pp in the flow path 50 between the When the pressures Pp and Pa are equal to each other, the switching position 40b switches to the switching position 40b, which cuts off communication between all boats when the pressures Pp and Pa are equal to each other.
When the pressure is lower than the pressure Pa, the switch is switched to a switching position 40c that connects the boat R and the boat A in communication. Further, the variable throttle 54 changes the effective passage cross-sectional area of the throttle by controlling the current applied to the solenoid 58, thereby changing the pressure Pp in cooperation with the fixed throttle 52.

Similarly, pressure control valves 34 to 38 are each pressure control valve 32
pilot-operated three-boat switching control valves 42, 44, 46 corresponding to the switching control valve 40; a flow path 60, 62, 64 corresponding to the flow path 50; and a fixed throttle 66. 68,70, and variable apertures 72,74,76 corresponding to the variable aperture 54, and the variable apertures 72-76 each have a solenoid 78,80,82.

In addition, the switching control valves 42, 44, and 46 are switching control valves 40.
The R boat has a low pressure flow path 48 FL for the left rear wheel and a low pressure flow path 48 FL for the right rear wheel.
One end of the low pressure flow path 48RL for the RR and left rear wheels is connected to the A boat, and the connection flow paths 84, 86, and 88 are connected to the A boat, 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 pressure Pa inside as a pilot pressure, and when the pressure Pp is higher than the pressure Pa, the boat P
Switching positions 42a and 44 that communicate and connect boat A with
a, 46a, and switch to switching positions 42b, 44b, 46b which cut off communication between all boats when pressures Pp and Pa are equal to each other, and connect boat R and boat A when pressure Pp is lower than pressure Pa. The switching positions 42c s 44c s 46e are connected.

As schematically shown in FIG. 1, each actuator IPR, IFL, IR1? %IRI is working fluid chamber 2PR, 2PL, 21? Cylinder 106PR1106PL, 106RR, defining R, 2RL,
106RL and the piston 108PI that fits into the corresponding cylinder? , 108PL, 108RR, 10
8RL, each connected to the vehicle body (not shown) through a cylinder, and connected to a suspension arm (not shown) at the tip of the rod portion of the piston. Although not shown in the internal explanation, a suspension spring is elastically loaded between an upper seat fixed to the rod portion of the piston and a lower seat fixed to the cylinder.

Also, the cylinders 106FR and 106F of each actuator
L, 106RR, and 106RL have a drain flow path 110.
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 2RL via throttles 124.126.128.130, respectively. Also pistons 108PR, 108FL, 10
8RI? , 108) Each IL has a flow path 14OFR.
, 140PL, 140RR, and 140RL are provided. Each of these channels has a corresponding channel 56.84.
~88 and working fluid chamber 2Pl? , 2P+7.2R)? .

2RL, and a filter 142 is installed in the middle of each.
It has PR, 142FL, 142RR, and 142RL. Also, actuators I PR, I PL, 1
1? In positions close to R and IRL, vehicle heights XPR, XFL, and XRRSXRL of the parts corresponding to each wheel are respectively displayed.
Vehicle height sensors 144FR, 144FL, 144 that detect
R1? , 144RL are provided.

Pilot-operated shutoff valves 150.152.154.156 are provided in the middle of the connecting channels 56.84 to 88, respectively, and these shutoff valves are connected to corresponding pressure control valves 40.42.44.46, respectively. High pressure flow path 1 on the more upstream side
8F)? , 18PL, 18RR, 18RL and the pressure in the drain channels 110, 112, 114, 116 are kept in a closed state when the differential pressure is less than a predetermined value. 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 each take in the pressure of the upstream portion of the corresponding flow path 158, 160, 162, 164, that is, the corresponding connection flow path side, as pilot pressure, and the pilot pressure is set to a predetermined value. When the value is exceeded, the valve is opened and a portion of the working fluid in the corresponding connection channel is guided to the channels 50, 60 to 64.

In addition, the shutoff valves 150 to 156 are connected to the high pressure flow path 18FR, respectively.
The valve may be configured to maintain the valve closed state when the pressure difference between the pressure inside 18FL, 18R)l, and 18RL and the atmospheric pressure is equal to or less than a predetermined value.

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

In the illustrated embodiment, the high pressure channel 18R and the low pressure channel 4
8R is a flow path 188 that has a filter 182, a throttle 184, and a normally open electromagnetic on-off valve 186 that can adjust the flow rate.
are connected to each other by. The electromagnetic on-off valve 186 is configured to open by energizing a solenoid 190 and changing its excitation current, and to adjust the flow rate of the working fluid passing through the valve. Also, the high pressure flow path 181
? and the low-pressure flow path 48R are connected to each other by a flow path 194 having a pilot-operated on-off valve 192 in the middle. The on-off valve 192 takes in the pressure on both sides of the throttle 184 as a pilot pressure, and maintains the closed position 192a when there is no differential pressure on both sides of the throttle 184, and when the pressure on the high pressure flow path 18R side with respect to the throttle 184 is high. The valve is switched to the open position 192b. Thus aperture 1
84, the electromagnetic on-off valve 186 and the on-off valve 192 cooperate with each other to selectively communicate and 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, to direct the low-pressure flow from the high-pressure flow path. A bypass valve 196 is configured to control the flow rate of the working fluid flowing into the passage.

Furthermore, in the illustrated embodiment, pressure sensors 197 and 198 are provided in the high-pressure flow path 18R and the low-pressure flow path 48H, respectively, and these pressure sensors measure the pressure PS and the pressure of the working fluid in the high-pressure flow path, respectively. The pressure Pd of the working fluid in the low pressure flow path is detected. In addition, pressure sensors 19 are provided in the connecting channels 56, 84, 86, and 88, respectively.
9PR, 199PL, 199RR, 199RL are provided, and these pressure sensors control the working fluid chambers 2FR, 2PL, 2RR, 21?, respectively. The pressure inside L is detected. Further, 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) 2.
06, random access memory (RAM) 208,
It has 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 includes a signal indicating the rotation speed N of the engine 14 from the rotation speed sensor 16, and pressure sensors 197 and 1.
Signals indicating the pressure PS in the high-pressure flow path and the pressure Pd in the low-pressure flow path from 98, pressure sensors 199PL, 19
9FR, 199RI1.199RJ? A signal indicating the pressure PI (1-1, 2, 3, 4) in the working fluid chambers 2 PL, 2 PR, 2RL, and 2RR, respectively, and an ignition switch (IGSW) 21.6 indicates whether the ignition switch is in the on state. Signal indicating whether or not vehicle height sensor 144FL, 144P! ? .

144RL, 144R1? Vehicle height X1 (1-1) of the parts corresponding to the left front wheel, right front wheel, left rear wheel, right rear wheel respectively
, 2, 3, 4) are respectively input.

Input port device 210 also includes a signal indicating vehicle speed V from vehicle speed sensor 234, a signal indicating longitudinal acceleration Ga from longitudinal G (acceleration) sensor 236, and a signal indicating longitudinal acceleration Ga from longitudinal G (acceleration) sensor 238.
A signal indicating the lateral acceleration G1 from the steering angle sensor 240, 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 low mode, respectively. It is now entered.

The input port device 210 appropriately processes signals input thereto and outputs the processed signals to the CPU and RAM 208 based on the program stored in the ROM 206 (according to instructions from the CPU 204).
06 is the control flow shown in Fig. 3, Fig. 6A to Fig. 6C, and Fig. 10, and Fig. 4, Fig. 5, Fig. 7 to Fig. 9,
I have memorized the maps shown in Figures 11 to 14,
The CPU processes signals based on each control flow. In accordance with instructions from the CPU 204, the output boat device 212 outputs a control signal to the electromagnetic on-off valve 186 via a drive circuit 220, and outputs a control signal to the pressure control valves 32-38, specifically variable throttles 54, 72, .
Control signals are output to solenoids 58, 78, 80, and 82 of 74, 76, and are output to display 232 via drive circuit 230.

Next, the operation of the illustrated embodiment will be explained 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.
6 is related to whether or not the pressure has ever exceeded the threshold suppressing pressure Pc for completely opening the valve, 1 indicates that the pressure Ps has ever exceeded the pressure Pc, and the flag Fs indicates whether the pressure control valve Standby pressure Pb1 (described later) in 32 to 38
Standby pressure current 1 corresponding to j-1, 2, 3, 4)
This relates to whether bl (1-1, 2, 3, 4) is set, and 1 indicates that the standby pressure current is set.

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

In step 20, 5c! stored in the RAM 208! t & contents are cleared and all flags are O
The process is then reset 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 pressure Ps in the high pressure flow path detected by 98, pressure sensors 199PL, 199FR, 199RL,
Working fluid chambers 2PL and 2P detected by 199RR
A signal indicating the pressure PI in R, 2RL, and 2RR, a signal indicating whether the ignition switch 216 is in the on state, and a vehicle height sensor 144 FL.

A signal indicating vehicle height X1 detected by 144FR, 144RL, and 144RR, a signal indicating vehicle speed V detected by vehicle speed sensor 234, a signal indicating longitudinal acceleration Ga detected by longitudinal G sensor 236, and lateral G sensor 238.
A signal indicating the lateral acceleration G1 detected by the steering angle sensor 240, a signal indicating the steering angle θ detected by the steering angle sensor 240, and a signal indicating whether the mode set by the vehicle height setting switch 248 is the 7% high mode or the low mode. The signal is read, and then the process proceeds to step 40.

In step 40, it is determined whether the ignition switch is in the off state or not. 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. If it is determined that there is, 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
The time T until the standby pressure P old of 8 is set
A timer for s is started and then the process proceeds to step 70. 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. 4 stored in M206, calculation is performed according to Ib-1b+ΔIbs, and the process then proceeds to step 80.

In step 80, the current 1b 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, the pressure Ps in the high-pressure channel reaches the threshold K.
A determination is made as to whether or not Ps is greater than or equal to Pc, and Ps≧Pc
If it is determined that Ps≧Pc is not true, the process proceeds to step 120, and if it is determined that Ps≧Pc, the process proceeds to step 100.

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

In step 110, in order to control the ride comfort of the vehicle and the attitude of the vehicle body, the process proceeds to step 30, as will be described in detail later with reference to FIGS. 6A to 6C and FIGS. 7 to 14. By performing active calculations based on various signals read in, the variable throttle 5 of each pressure control valve
4. The current 1u1 to be energized to the solenoids 58, 78, 80, 82 of 72 to 76 is calculated, and then step 1
Proceed to 70.

In step 120, it is determined whether the flag Fc is 1 or not, and it is determined that the flag Fc is Fc-1, that is, the pressure Ps of the working fluid in the high pressure flow path is equal to or higher than the threshold pressure PC. If it is determined that the pressure has become lower than this value after the initial pressure, the process proceeds to step 110, and it is determined that it is not Fe-1, that is, it is determined that the pressure PS has never exceeded the threshold pressure Pc. When this has been performed, the process advances to step 130.

In step 130, it is determined whether or not the flag Fs is 1. When it is determined that 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, and the pressure PI read in step 30 is stored in the RAM 2081 as the standby pressure Pbl, and RO! v12061: Based on the self-stored map corresponding to the graph shown in FIG. the pressure Pbl, that is, the working fluid chamber 2PL detected by the respective corresponding pressure sensor;
Pressure control valves 34.32.38.36 to provide a pressure substantially equal to the pressure P1 in 2PR% 2RL, 2RR.
variable aperture 72.54.76.74 solenoid 78.
58.82.80 current 1bl (1-1,2
, 3, 4) are calculated, 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 1b calculated in step 70 is greater than or equal to the reference value Ibo, and when it is determined that Ib≧Ibo is not satisfied, the process returns to step 30. , when 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, the current 1bl calculated in step 150 or the current 1ul calculated in step 110 is applied to the variable throttle solenoid 58 of each pressure control valve.
78 to 82, each pressure control valve is driven and its control pressure is controlled, and then step 30
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 start of the operation described above does not constitute a main part of the present invention, and details of this pressure control can be found in Japanese Patent Application No. 63-307189 filed by the same applicant as the present applicant. Please refer to the issue. Moreover, the pressure control by the bypass valve when the operation is stopped is also disclosed in Japanese Patent Application No. 63-30719 filed by the same applicant as the present applicant.
It may be done as described in No. 0.

Next, the active operation performed in step 110 will be described with reference to FIGS. 6A to 6C and FIGS. 7 to 14.

First, in step 300, a heap target value Rxh, a pitch target value RXps, and a roll target value Rxr based on the target posture of the vehicle body are calculated based on maps corresponding to the graphs shown in FIGS. 7 to 9, respectively. Then step 31
Go to 0.

In FIG. 7, 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 310, the heap (Xxh
), pitch (Xxp), roll (Xxr), warp (X
A displacement mode conversion calculation is performed for Xv), and the process then proceeds to step 820.

Xxh-(XH+X4y)+(X3+X
4)XXI) --(XI +X2) + (X3
+X4 )Xxr= (XI-X2) +(X3-
X4) Xxw-(XI-X2)-(X3
4) In step 320, the deviation of the displacement mode is calculated according to the following formula, and then step 33
Go to 0.

E xh -Rxh -X xh E XI) -RXp-X XI) E xr-Rxr -X xr E xw-RX1ll -X It may be the Xxv calculated in step 310 or the average value of Xxv calculated in the past several cycles.

Also, if IEXIII≦W, (positive constant), EX
It is considered as C.

In step 330, PrD compensation calculation for displacement feedback control is performed according to the following equation, and then the process proceeds to step 340.

Cxh= K pxh −E xh+ K Ixh
I xh (n) + K dxh f Ex
h(n) −E xh(n−r++ )ICXp
-K pxp 0E Xp+ K IXI) I x
p(n) + K dxp I E xp(n) −E
xp(n-nl)l]Cxr-Kpxr'Exr
+Kjxr-1xr(n)+Kdxr(E
xr(n) −E xr(n−tH month Cxv=
K pxv E xw+K IX1/ I x
w(n) + K dxw f E xw(n) −E
xv(n-n+month) In each of the above formulas, Ej(n) (j
=xh, xp, xr, Pi/) is the current Ej, and Ej(n-n1) is the Ej n1 cycles ago. Also, Ij(n) and Ij(n-1) are the current and one cycle previous Ij, respectively, and TX is the time constant, and Ij(n) -Ej(n)+TXIj(n
-1), and I jiax is a predetermined value, 1ljl≦
I jmax. Furthermore, the coefficients Kpj, Klj, K
dj (j-xh, XP.

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

In step 340, an inverse transformation of the displacement mode is calculated according to the following equation, and the process then proceeds to step 350.

PX! =174 ・KX 1 (Cxh −CXI)
+ Cxr+ Cxv) PX: -1/4 ・Kx
: (Cxh-CXI)-Cxr-Ci)Px 3
=1/4 IIKX 3 (Cxh ten Cxp+ Cxr
-Cxw)Px a = 1/4 ・KX 4 (Cx
h+ Cxp -Cxr+ CI/) Kx HKx
2 , KX 3 , and KX a are proportionality constants.

In step 350, according to the routine shown in FIG. 10, pressure correction amounts Pga and Pg in the longitudinal direction and lateral direction of the vehicle are calculated based on the longitudinal acceleration and lateral acceleration, respectively.
l is calculated, and then the process proceeds to step 360.

In step 360, the pi;nochi (
Calculation of PD compensation of G feedback control is performed for Cgp) and roll (Cgr), and then step 3
Proceed to 70.

Cgp=Kpgp −Pga+Kdgp iPga(
n)-P ga(n-nl )I Cgr-Kpgr -Pgl+Kdgr (Pgl
(n)-Pgl(rho n+)) In each of the above formulas, P ga(n) and Pgl(n) are the current Pga and Pgl, respectively, and P ga(n
-nl) and Pgl(n-nl) are Pga and Pgl, respectively, before n1 cycles. Moreover, K pgp and Kpgr are proportionality constants, K dH) and K dg
r is a differential constant.

In step 370, 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 380.

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

Pg + -Kg + /4 ・ (-Cgp
2 to 10 f' -Cgr+, f -Gl
) Pg,! -Kg! /4' (-cgp-to=
r' Cgr-, r number G+) Pg 3-Kg 3/4-(Cgp+Kp r φCg
r10Kl r -GI ) Pga = Kg 4 /4 ・(Cgp-!!r
-Cgr-Kl r -Gl ) Furthermore, Kg l Kg! ! -Kg 3 and Kga are proportional constants, Klr and 1r, respectively! ! f
' and 2r are constants as distribution gains between the front and rear wheels, respectively.

In step 390, the RAM in step 150 is
Based on the pressure Pbl stored in 20g and the results calculated in steps 340 and 380, P ul −P
The target control pressure Put of each pressure control valve is calculated according to xi0P gl+P bl (1-1, 2, 3, 4), and then the process proceeds to step 400.

In step 400, a target current to be supplied to the bath pressure control valve is calculated according to the following equation, and then the process proceeds to step 410.

11-Ku HPu 1 +Kh (Psr-Ps
)-Kl-Pd-α12-Ku2Pu! +Kh (Psr-Ps
)−Kl−pa−α 13 =Ku 3 Pu 3 +Kh (Psr−P
s )-Kl -Pd 14-Ku 4 Pu 4 +Kh (Psr-Ps
)-Kl ・Pd Kul 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,
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 410, a temperature correction coefficient K 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. 1-1, 2, 3, 4), temperature correction calculation of the target current is performed, and then the process proceeds to step 420.

In step 420, the current warp (the amount of torsion around the longitudinal axis of the vehicle body) is calculated according to the formula Ill-It-(It3 It4), and then the process proceeds to step 430.

In step 430, the deviation of the current warp is calculated according to the following formula with Rlv as the target current warp,
Thereafter, the process proceeds to step 440.

E 1w −Rlv −1w Note that the target current warp R1v in the above equation may be O.

In step 440, the current warp target control amount is calculated according to Elwp - Rlwp · Eiv with Kivp as a proportionality constant, and then the process proceeds to step 450.

In step 450, the current warb is inversely transformed according to the following equation, and then the process proceeds to step 460.

Iv I-Elvp /4 11111! --Eivp/4 Iv 3 --Eivp /4 Iw t -Elwp /4 In step 460, based on the results calculated in steps 410 and 450, the pressure is supplied to the 8 pressure control valves according to the following formula. The final target current Iul to be calculated is calculated,
Thereafter, the process proceeds to step 170 in FIG.

I ul= I tl+ I wl (l-1, 2, 3, 4) Next, the calculation of the pressure correction portions Pga and Pgl performed in step 350 will be explained with reference to FIGS. 10 to 12. .

First, in step 510, based on the map corresponding to the graph shown in FIG. 11, in steps 550 and 560 described later, the pressure in the longitudinal direction is calculated as shown in FIG. Longitudinal acceleration Ga for minute Pga
The width of the dead zone is calculated, and the process then proceeds to step 520.

In step 520, it is determined whether 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 the determination has been made, the process proceeds to step 540, and if it is determined that the absolute value of Ga is not less than or equal to A, the process proceeds to step 530.

In step 530, it is determined whether the absolute value of the longitudinal acceleration Ga is less than or equal to a positive constant aI, and when it is determined that the absolute value of Ga is less than or equal to 81, the process proceeds to step 550. If it is determined that the absolute value of Ga is not less than C1, the process advances to step 560.

In step 540, the correction performance Pg of the pressure in the longitudinal direction is
a is set to 0, and the process then proceeds to 570.

In step 550, the correctability Pga of the pressure in the longitudinal direction is calculated by /7A according to the following formula, and then the process proceeds to step 570.

P ga −S GN (Ga)x P a (Ga
) here bl bl φ APa
(Ga) -1Gal -'--(1)a I
-AalA In step 560, the correction property Pga of the pressure in the longitudinal direction is calculated according to the following formula, and then in step 57
Go to 0.

P ga -S GN (Ga)
)Here - b b, meeting a! 'Qa(Ga)
−1Ga I + −(2)C
2-al a:!
In formulas (1) and (2), C2 and bl are positive constants, and 5GN(Ga)=-1(Ga<0)-1(Ga>O).

In step 570, steps 610 and 62 described below are performed based on the map corresponding to the graph shown in FIG.
0, the width B of the dead zone of the lateral acceleration Gl with respect to the lateral pressure correction property Pgl of <ftW is calculated as shown in FIG. 16, and then the process proceeds to step 580.

In step 580, it is determined whether the absolute value of the lateral acceleration G1 is less than or equal to the reference value B calculated in step 570, and it is determined that the absolute value of Gl is less than or equal to B. If this has been done, the process proceeds to step 600, and if it is determined that the absolute value of G1 is not less than or equal to B, the process proceeds to step 590.

In step 590, it is determined whether the absolute value of lateral acceleration G1 is less than or equal to a positive constant Cl, and when it is determined that the absolute value of G1 is less than or equal to C1, the process proceeds to step 610. If the absolute value of G1 is not less than or equal to C1, the process advances to step 620.

In step 600, the lateral pressure correction property Pgl
is set to O, then proceeding to step 360 of FIG. 6B.

In step 610, the lateral pressure correctability Pgl is calculated according to the following formula, and then in step 360
Proceed to.

P gl - S G N (Gl) x P 1 (Gl)
Here d, d,・B PI(Gl) −1CI +−−−−・−(3)(
113cl-8 In step 620, the lateral pressure correctability Pgl is calculated according to the following formula, and then in step 360
Proceed to.

P gl-S G N (Gl)X Q 1(Gl) here dl dl 1 c2Ql(
Gl)-10I ++ -m- (4)
CH-C1 Committee -C1 In formulas (3) and (4), C! ! and dl are positive constants, 5GN(Gl)--1(Gl<0)-1(Gl>0).

Thus, according to the illustrated embodiment, the pressure correction properties Pga and Pgl are determined based on the longitudinal acceleration Ga and the lateral acceleration G1, respectively, as shown in FIGS. 15 and 16, respectively.
is calculated, but in this case, the lower the vehicle speed is, the wider the widths A and B of each dead zone are, and the lower the vehicle speed is, the larger the range in which correction control based on acceleration is not performed on the pressure in the working fluid chamber of the actuator. be done. Therefore, even if the vehicle is driven at low speed on a rough road or with chains attached, or the door is opened and closed relatively vigorously while the vehicle is stopped, even if acceleration is detected by the acceleration sensor due to these reasons, the active suspension may malfunction. It is possible to prevent unnatural shaking of the vehicle body due to inappropriate control of the operation, that is, the pressure in the working fluid chamber.

The pressure correction bones Pga and Pgl are three-dimensional maps using longitudinal acceleration Ga, vehicle speed V, lateral acceleration G1, and vehicle speed V as parameters, respectively, and are set so that the lower the vehicle speed, the larger the widths A and B of the dead zone. It may also be calculated based on a three-dimensional map.

Further, in the above embodiment, both the widths A and B of the dead zone are increased as the vehicle speed decreases, but only the width B of the dead zone for lateral acceleration may be increased.

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

[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 shows a map used when calculating the current 1b supplied to the bypass valve at the start of operation of the active suspension, and Figure 5 shows the pressure P1 in the working fluid chamber of each actuator and the map supplied to each pressure control valve. Graphs 6A to 6C showing the relationship between the current 1bi and the current 1bi
A flowchart showing the active calculation routine performed in step 110 of the flowchart shown in the figure, FIG. 7 is a graph showing the relationship between the vehicle speed V and the target displacement jlRxh, and FIG. 8 is a graph showing the relationship between the longitudinal acceleration Ga and the target Displacement amount RX
Figure 9 is a graph showing the relationship between lateral acceleration G1
A graph showing the relationship between and [ ] target displacement ff1Rxr,
FIG. 10 is a flowchart showing a routine for calculating the target pressure Pga in the longitudinal direction and the target pressure Pgl in the lateral direction performed in step 350 of the flowchart shown in FIGS. 6A to 6C, and FIG. 12 is a graph showing the relationship between the width A of the dead zone in the calculation of the correction bone Pga for pressure in the longitudinal direction and the vehicle speed V, and the width A of the dead zone in the calculation of the correction bone Pgl for the pressure in the groove direction. Figure 3 is a graph showing the relationship between IHj and width B; Figure 3 is a graph showing the relationship between vehicle speed V and steering angular velocity θ and change rate G1 of pre-Mj lateral acceleration; Figure 14 is a graph showing the relationship between the temperature of the working fluid. A graph showing the relationship between T and correction coefficient Kt,
Figure 15 shows the correction bone P for longitudinal acceleration Ca and longitudinal pressure.
A graph showing the relationship between ga and Fig. 16 is lateral acceleration G
1 is a graph showing the relationship between lateral pressure correction bone Pgl and lateral pressure correction bone Pgl. II in R, IFL, 11? R, II? L...actuator, 2PR, 2PL% 21? R, 21? L...
- Working fluid chamber, 4... Reserve tank, 6... Pump, 8... Filter, 10... Suction channel, 12...
...Drain channel, 14... Engine 16... Rotation speed sensor, 18... High pressure channel, 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 flow path, 52...Fixed throttle, 54...Variable throttle. 56... Connection flow path, 58... Solenoid, 66.6
8.70...fixed aperture, 72.74.76...variable aperture. 78.80.82... Solenoid, 84.86.88
... Connection channel, 110-118... Drain channel, 1
20...Filter, 124-130...Aperture, 13
2~138-7 cumulator, 144Pi? N 144
FL, 144R1? , 144)? L...Vehicle height sensor, 50-156...Shutoff valve, 166-172.
...Relief valve, 174...Oil cooler, 176.
...Filter, 18o...Relief valve, 182...
Filter, 184... Throttle, 186... Solenoid on-off valve, 19o... Solenoid, 192... On-off valve, 19
6...Bypass valve, 197.198.199...P
R, 199PL, 199i? R, 199RL...pressure sensor, 200...electric control device, 2o2...
Microcomputer, 204...CPU, 206.
・・ROM, 20g-RAM, 210-=input port i
Placement, 212... Output boat device, 216 IGSW
. 220, to 230... Drive circuit, 232... Display device, 234-9. Vehicle speed sensor, 236... Front and rear G sensor, 238... Lateral G sensor, 240... Steering angle sensor, 248... Vehicle height setting switch permission application Toyota Motor Corporation

Claims (1)

[Claims] a fluid pressure actuator disposed between each wheel and the vehicle body; a pressure adjusting means for adjusting the fluid pressure in the actuator; a vehicle speed detecting means; an acceleration detecting means for detecting the acceleration of the vehicle body; and control means for correcting and controlling the pressure regulating means with a correction amount based on the acceleration when the acceleration detected by the detecting means exceeds the dead zone, and the lower the vehicle speed detected by the vehicle speed detecting means, the more the dead zone is Hydraulic active suspension configured for increased width.