JPH0321513A - Fluid pressure type active suspension - Google Patents

Abstract

PURPOSE:To enable abnormality detection in pressure control without delay by judging it as abnormality in pressure control when a deviation between an actual pressure warp which is not affected depending on acceleration/ deceleration of a vehicle and a target pressure warp exceeds a reference value. CONSTITUTION:In a suspension in the caption, supply and discharge of working fluid from a pump 6 to working fluid chambers 2FR to 2RL of an actuator 1 (1FR to 1RL) provided at each wheel is controlled from a high pressure flow passage 18 through pressure control valves 32, 34, 36, 38. The pressure control valves 32 to 38 are controlled so that pressure of the actuator 1 becomes a predetermined target control pressure including a target pressure warp determined according to a driving state of a vehicle. In this case, pressure in the actuator 1 is detected by pressure sensors 199FR to 199RL, and an actual pressure warp is acquired from the detected pressure. When a deviation between this actual pressure warp and the target pressure warp exceeds a reference value, it is judged as abnormality in pressure control.

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 described in, for example, Japanese Unexamined Patent Publication No. 64-22613, an attitude detection means for detecting the attitude state of a vehicle body, a fluid pressure actuator disposed between each wheel and the vehicle body,
A fluid pressure type active suspension having a pressure control valve that controls the pressure in the actuator, and a control means that controls the pressure control valve according to the posture detected by the posture detection means, A fluid pressure active suspension that corrects the pressure inside the actuator (feedback control) based on the deviation between the indicated pressure and the actual pressure inside the actuator, and determines that there is an abnormality in the pressure control valve when the deviation does not change. has been known for a long time.

Problems to be Solved by the Invention However, in the above-mentioned active suspension,
Since the abnormality of the pressure control valve is determined for each wheel, it is possible only when the attitude of the vehicle does not substantially change, that is, when the vehicle is traveling straight on a flat road at a substantially constant speed. Accurate abnormality judgment cannot be made. Further, if abnormality determination is not performed in situations other than when the vehicle is traveling straight on a flat road at a substantially constant speed, there is a problem that detection of abnormality in the pressure control valve will be delayed.

In view of the above-mentioned problems with conventional hydraulic active suspensions in which abnormality determination of the pressure control valve is performed for each wheel, the present invention was developed only when the vehicle is traveling at a constant speed on a flat road. It is an object of the present invention to provide a hydraulic active suspension that is improved so as to be able to accurately determine an abnormality even when the vehicle is traveling straight ahead under acceleration and deceleration conditions.

Means for Solving the Problems According to the present invention, the above object is achieved by providing a fluid pressure actuator disposed between each wheel and a vehicle body, and a pressure control system in the actuator. a pressure regulating means for adjusting the pressure within the actuator; a control means for controlling the pressure regulating means so that the pressure within the actuator reaches a predetermined target control pressure including a target pressure warp determined according to the running state of the vehicle; a pressure detection means for detecting pressure; a means for determining an actual pressure warp from the pressure detected by the pressure detection means; and a means for determining an actual pressure warp from the pressure detected by the pressure detection means; This is accomplished by a hydraulic active suspension having means for determining.

Effect of the Invention According to the above-described configuration, an actual pressure warp that is not affected by acceleration or deceleration of the vehicle is determined based on the pressure inside the actuator detected by the pressure detection means, and the actual pressure warp and the control means are determined. The deviation from the set target pressure warp is determined, and when the deviation exceeds the reference value, it is determined that the pressure control is abnormal. Therefore, the vehicle is on a flat road.
Accurate abnormality determination can be made not only when the vehicle is traveling straight at a constant speed, but also when the vehicle is traveling straight on a flat road while accelerating and decelerating. Compared to the case where abnormality determination is performed only when the vehicle is running, abnormality in pressure control can be detected without delay.

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 circuits of the illustrated hydraulic suspension are the right front wheel, left front wheel, right rear wheel, and
Actuator I FR provided corresponding to the left rear wheel,
These actuators have working fluid chambers 2PR and 2PR, respectively.
It has 2PL, 2RR, and 2RL.

Further, in the figure, 4 indicates a reserve tank that stores hydraulic oil as a working fluid, and the reserve tank 4 is connected to a suction channel 10 in which a filter 8 for removing foreign matter is provided.
It is connected in communication with the suction side of the pump 6. A drain passage 12 is connected to the pump 6 for collecting working fluid leaked inside the pump 6 into the reserve tank 4. The pump 6 is rotationally driven by an engine 14, and the rotation speed of the engine 14 is detected by a rotation speed sensor 16.

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

Further, one end of the high pressure flow path 18PR for the right front wheel, the high pressure flow path 18PL for the left front wheel, the high pressure flow path 18RR for the right rear wheel, and the high pressure flow path 18RL for the left rear wheel are connected to the high pressure flow paths 18F and 18R, respectively. . High pressure flow path 18PI? ,1 8PL,
There are filters 2 8PR, 2 8PL, 2 8RR, 2 8 in the middle of 1 8RR and 1 8RL, respectively.
RL is provided, and the other ends of these high-pressure channels are connected to P boats of pilot-operated three-boat switching control valves 40, 42, 44, and 46 of pressure control valves 32, 34, 36, and 38, respectively. ing.

The pressure control valve 32 is connected to the switching control valve 40 and the high pressure flow path 18P.
It consists of a flow path 50 that communicates and connects the low pressure flow path 48F'R for the right front wheel, and a fixed throttle 52 and a variable throttle 54 provided in the middle of the flow path.

A low pressure flow path 48FR is connected to the R port of the switching control well 40, and a connection flow path 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-port switching control valves 42, 44, 46 corresponding to the switching control valve 40; flow passages 60, 62, 64 corresponding to the flow passage 50; and fixed throttles 66, 68 corresponding to the fixed throttle 52. , 70, and variable apertures 72, 74, and 76 corresponding to the variable aperture 54, and the variable apertures 72 to 76 have solenoids 78, 80, and 82, respectively.

In addition, the switching Ma valves 42, 44, and 46 are the switching control valve 40.
The R boat has a low pressure flow path 48PL for the left rear wheel and a low pressure flow path 48R for the right rear wheel, respectively.
One end of a low pressure flow path 48RL for the R and left rear wheels is connected to the A boat, and one end of connection flow paths 84, 86, and 88 are connected to the A boat, respectively. Moreover, each of the switching control valves 42 to 46 has a flow path 60 between a corresponding fixed throttle and a variable throttle.
It is a Subur valve that takes in the pressure Pp in ~ 64 and the pressure Pa in the corresponding connection channels 84 to 88 as pilot pressure, and when the pressure Pp is higher than the pressure Pa, it is a switching position that connects boats P and A for communication. 42a, 44a
, 46a, and when the pressures Pp and Pa are equal to each other, communication of all ports is cut off.
2b, 44b, and 46b, and when the pressure Pp is lower than the pressure Pa, the switching positions 42cs, 44cs, and 46c connect the boat R and the boat A in communication.

As schematically shown in FIG. 1, each actuator IPR, IPL, IRR, IRL has a cylinder 106FR, 106PL., defining a working fluid chamber 2PR, 2PL, 2RR, 2RL, respectively. 1
06RR, 1 06RL and pistons 10 8PI that fit into the corresponding cylinders respectively? , 1 0
8FL, 1 0 81? l? , 1 0 81? L
Each cylinder is connected to the vehicle body (not shown), and the tip of the piston rod is connected to a suspension arm (not shown). Although not shown in the drawings, a suspension spring is elastically mounted between an upper seat fixed to the rod portion of the piston and a lower seat fixed to the cylinder.

Also, the cylinder 106PR of each actuator. 10 6
One ends of drain channels 110, 112, 114, and 116 are connected to PL, 106RR, and 106RL. The other ends of the drain channels 110, 112, 114, and 116 are connected to a drain channel 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.

Working fluid chamber 2FI? , 2PL, 2RI? , 21?
Accumulators 132, 134, 136, 138 are connected to L via apertures 124, 126, 128, 130, respectively.
is connected. Also piston 108PR, 108F
L, 1 0 8 RR, 1 0 81? L has flow paths 140PR, 140FL, and 140R, respectively.
R, 140RL is provided. These channels communicate and connect the corresponding channels 56, 84 to 88 with the working fluid chambers 2PR, 2PL, 2RR, 2RL,
Filters 14 2PR, 1 4 2 in the middle respectively
It has FL, 1 4 2 RR, and 1 4 2 RL. Also, actuators I FR, I PL,
IRR, 11? At a position close to L, the vehicle heights of the parts corresponding to each wheel are displayed: XFR, XPLSXRR, XRL.
Vehicle height sensors 144PR, 144PL, 144 that detect
RR and 144RL are provided.

Pilot-operated shutoff valves 150, 152, 154, and 156 are provided in the middle of the connection channels 56, 84 to 88, respectively, and these shutoff valves are connected to corresponding pressure control valves 40, 42, 44, and 46, respectively. High pressure flow path 1 on the more upstream side
When the differential pressure between the pressure in 8FR, 18PL, 18RR, and 18RL and the pressure in drain passages 110, 112, 114, and 116 is below a predetermined value, the valve is maintained in a closed state. In addition, the connection channels 56, 84 to 8
The portion between the corresponding pressure control valve 8 and the shutoff valve is downstream of the variable throttle of the corresponding pressure control valve flow path 50, 60, 62, 64 by the flow path 158, 160, 162, 164, respectively. It is connected in communication. Channel 158-1
Relief valves 166, 168, 1 are provided in the middle of 64, respectively.
70, 172 are provided, and these relief valves are connected to corresponding flow passages 158, 160, 162, 164, respectively.
The pressure on the upstream side of the flow path, that is, the side of the corresponding connection flow path, is taken in as a pilot pressure, and when the pilot pressure exceeds a predetermined value, the valve is opened and a part of the working fluid in the corresponding connection flow path is transferred to the flow path. 50, 60-64.

In addition, each of the cutoff valves 150 to 156 is a high pressure flow path 18P! ?
, 1 8 PL, 1 8 RR, and 1 8 RL may be configured to maintain the closed state when the pressure difference between the pressure in the valves and the atmospheric pressure is equal to or less than a predetermined value.

The other ends of the low pressure passages 48PR and 48PL are connected to one end of the low pressure passage 48F for the front wheels, and the other ends of the low pressure passages 48RR and RL are connected to one end of the low pressure passage 48H 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 176 at the other end.
It is connected to the reserve tank 4 via. 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 so that its solenoid 190 is energized and its excitation current is changed to open the valve and adjust the flow rate of the working fluid passing through the valve. Also, the high pressure flow path 18
R 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 of the working fluid in the high-pressure flow path and the low pressure, respectively. The pressure Pd of the working fluid in the flow path is detected. In addition, pressure sensors 19 are provided in the connection channels 56, 84, 86, and 88, respectively.
9PR, 19 9PL, 1 9 9RR, 1 9
9RL is provided, and these pressure sensors control the working fluid chambers 2PR, 2PL, 2RR, and 2R, respectively.
The pressure inside L is detected. Furthermore, the temperature T of the working fluid stored in the reserve tank 4 is
A temperature sensor 195 is provided to detect the temperature.

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 a human powered boat device 210 and an output boat device 212, which are connected to each other by a bidirectional common bus 214.

The human-powered boat device 210 includes a signal indicating the rotation speed N of the engine 14 from the rotation speed sensor 16, a signal indicating the temperature T of the working fluid from the temperature sensor 195, and pressure sensors 197 and 19.
Signals indicating the pressure Ps in the high-pressure flow path and the pressure Pd in the low-pressure flow path from 8, pressure sensors 1 99PL, 1
A signal indicating the pressure Pi (1-1, 2, 3, 4) in the working fluid chambers 2PL, 2PR, 2RL, and 2RR from 99PR, 1 99RL, and 1 99RR, respectively, and an ignition switch turned on from the ignition switch (IGSW) 216. a signal indicating whether the emergency switch (EMSW) 218 provided in the vehicle interior and operated by the occupant of the vehicle is in the on state; a signal indicating whether the switch is in the on state; vehicle height sensors 144FL, 14;
Vehicle height Xl of the parts corresponding to the left front wheel, right front wheel, left rear wheel, and right rear wheel from 4PR, 144RL, and 144RR, respectively.
Signals indicating (l-1, 2, 3, 4) are manually input.

The input port device 210 also receives a signal indicating the vehicle speed V from the vehicle speed sensor 234, a signal indicating the longitudinal acceleration Ga from the longitudinal G (acceleration) sensor, a signal indicating the lateral acceleration Gl from the lateral G (acceleration) sensor 238, and a signal indicating the lateral acceleration Gl from the steering angle sensor. A signal indicating the steering angle θ and a signal indicating whether the vehicle height control mode set by the vehicle height setting switch 248 is a high mode or a normal mode are respectively input.

The input boat device 210 processes the signals input thereto as appropriate, and processes them based on the block diagram stored in the ROM 206 (according to instructions from the CPU 204).
It is designed to output the processed signal to. ROM
206 is the control flow shown in FIGS. 3, 8A to 8C, and 16, and FIGS. 4 to 7, and 12 to 15.
The map shown in FIG. 17 is stored. In accordance with instructions from the CPU 204, the output boat device 212 outputs a control signal to the electromagnetic on-off valve 186 via a drive circuit 220, and outputs a control signal to the pressure control valves 32-38, specifically variable throttles 54, 72, respectively, via drive circuits 222-228. A control signal is output to solenoids 58, 78, 80, and 82 of 74 and 76, and a control signal is output to a display 232 via a drive circuit 230.

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

Note that the control flow shown in FIG. 3 is started when the ignition switch 216 is closed. In the flowchart shown in FIG. 3, the flag Ff is related to whether or not there is a failure at any part of the hydraulic suspension, and 1 indicates whether there is a failure at any part of the hydraulic suspension. The flag Fw is related to whether a severe abnormality of pressure warp exists with respect to the pressure in the working fluid chamber of each actuator, and 1 indicates that a severe abnormality of pressure warp exists; The flag Fe relates to whether or not the engine is in an operating state; 1 indicates that the engine is in an operating state; This flag relates to whether or not the pressure has ever exceeded the threshold pressure PC for opening the valve. 1 indicates that the pressure Ps has ever exceeded the pressure Pc, and the flag Fs indicates whether the pressure control valves 32 to 38 This relates to whether or not standby current 1b1 (1-1, 2, 3, 4) corresponding to standby pressure Pb1 (1-1, 2, 3, 4), which will be described later, is set, and 1 is the standby pressure. Indicates that the current is set.

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

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

In step 30, the rotation speed of the engine 14 detected by the rotation speed sensor 16. -N, a signal indicating the temperature T of the working fluid detected by the temperature sensor 195, a signal indicating the pressure Ps in the high pressure flow path detected by the pressure sensor 197, a low pressure flow path detected by the pressure sensor 198. A signal indicating the pressure Pd within the pressure sensor 1 9 9
PL, 1 9 9PR, 19 9RL, 1 9
Working fluid chambers 2PL, 2PR, detected by 9RR
2RL, a signal indicating the pressure P1 in 2RR, a signal indicating whether the ignition switch 216 is in the on state, a signal indicating whether the EMSW2 18 is in the on state, vehicle height sensors 144FL, 144PR, 144RL,
A signal indicating the vehicle height X1 detected by the vehicle speed sensor 234, a signal indicating the vehicle speed V detected by the vehicle speed sensor 234, and a longitudinal acceleration Ga detected by the longitudinal G sensor 236E.
, a signal indicating the lateral acceleration Gl detected by the lateral G sensor 238, a signal indicating the steering angle θ detected by the steering angle sensor 240, and whether the mode set by the vehicle height setting switch 248 is the high mode. A signal indicating whether the mode is normal mode is read, and then the process proceeds to step 40.

In step 40, it is determined whether or not the ignition switch is in the off state, and when it is determined that the ignition switch is in the off state, the process proceeds to step 240, where it is determined that the ignition switch is in the on state. When it is determined that this is the case, the process advances to step 50.

In step 50, it is determined whether or not the EMSW is in the on state, and when it is determined that the EMSW is in the on state, the process proceeds to step 210, where it is determined that the EMSW is not in the on state. When the determination has been made, the process advances to step 60.

In step 60, it is determined whether the flag Ff is 1 or not, and when it is determined that it is Ff-1, the process proceeds to step 21p, and it is determined that it is not Fr-1. If so, proceed to step 70.

In step 70, it is determined whether the engine is being operated by determining whether the engine rotation speed N detected by the rotation speed sensor 16 and read in step 3Q exceeds a predetermined value. is carried out, and when it is determined that the engine is not being operated, the process proceeds to step 110, and when it is determined that the engine is being operated, the process proceeds to step 80.

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

In step 80, the flag Fe is set to 1, and the time from the time when engine operation is started to the time when the standby pressure pbt of the pressure control valves 32 to 38 is set in step 200, which will be described later. A timer for Ts is started and then the process proceeds to step 90.

In this case, if the flag Fe has already been set to 1, it remains in that state, and if the timer Ts has already been activated, the timer continues counting.

In step 90, the current 1b applied to the solenoid 190 of the electromagnetic on-off valve 186 of the bypass valve 196 is RO
Based on the map corresponding to the graph shown in FIG. 4 stored in M206, calculation is performed according to Ib-1b+Δ1 bs , and the process then proceeds to step 100.

In step 100, the current 1b calculated in step 90 is applied to the solenoid 190 of the electromagnetic on-off valve 186, thereby driving the bypass valve 196 in the closing direction, and then the process proceeds to step 130.

In step 110, the operation of the Ts timer is stopped, and the process then proceeds to step 120. In this case, if the Ts timer is not activated, it remains in that state.

In step 120, it is determined whether the flag Fe is 1 or not, and when it is determined that the flag Fe is Fe-1, that is, it is determined that the engine has stopped after being started, the process proceeds to step 230. If it is determined that the engine is not Fe-1, that is, that the engine has not been started at all, the process advances to step 130.

In step 130, it is determined whether the pressure PS in the high-pressure flow path is equal to or higher than the threshold value Pc, and when it is determined that Ps≧Pc is not satisfied, the process proceeds to step 170, where Ps≧Pc If it is determined that this is the case, the process advances to step 140.

In step 140, the flag Fp is set to 1, and then the process proceeds to step 150.

In step 150, in order to control the ride comfort of the vehicle and the attitude of the vehicle body, various signals read in step 30 are used, as will be explained in detail later with reference to FIGS. 8A to 15. Based on the active calculation, the current 1ul to be energized to the solenoids 58, 78, 80, 82 of the variable throttles 54, 72-76 of each pressure control valve is calculated, and the process then proceeds to step 300.

In step 160, it is determined whether the flag Fp is 1 or not, and it is determined that the flag Fp is Fp-1, that is, the pressure Ps of the working fluid in the high pressure flow path has exceeded the threshold pressure Pc. When it is determined that the pressure has become lower than this, the process proceeds to step 150, and it is determined that the pressure is not Fp-1, that is, it is determined that the pressure PS has never exceeded the threshold pressure Pc. If the process has been performed, the process advances to step 170.

In step 170, it is determined whether or not the flag Fs is 1. If the flag Fs is Fs -1, but not 1, the process proceeds to step 180.

In step 180, 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 300, and it is determined that the time Ts has elapsed. If the process has been performed, the process advances to step 190.

In step 190, the operation of the Ts timer is stopped, and the pressure P1 read in step 30 is stored in the RAM 208 as the standby pressure pbt, and the pressure shown in FIG. Based on the map corresponding to the graph shown in FIG. Fluid chamber 2PL, 2PR, 2R
Variable restrictors 72 of pressure control valves 34, 32, 38, 36 to provide a pressure substantially equal to pressure P1 in L, 2RR.
, 54, 76, 74 solenoids 78, 58, 82, 8
The current 1bi (1-1, 2, 3, 4) to be energized to 0 is calculated, and then the process proceeds to step 200.

In step 200, the flag Fs is set to 1, and then the process proceeds to step 300.

In step 210, it is determined whether the flag is Fw-1 or not. When it is determined that the flag is not Fw-1, the process proceeds to step 230, and Fw-1 is determined.
If it is determined that this is the case, the process advances to step 220.

In step 220, a current of 1 ul (1=1, 2, 3, 4
) is set to the standby pressure current Ibi calculated in step 190, and then the process proceeds to step 230.

In step 230, the solenoid 190 of the electromagnetic on-off valve 186 of the bypass valve 196 is
The current 1b to be applied to is calculated by Ib-1b-ΔIbe, and the process then proceeds to step 240.

In step 240, the current 1b calculated in step 230 is applied to the solenoid 190, thereby driving the bypass valve 196 in the opening direction, and then the process proceeds to step 300.

In step 250, it is determined whether or not a timer related to the time Tart from when the ignition switch is turned off to when the main relay is turned off is activated, and whether a timer Toff is activated or not. If it is determined that the TOrf timer is not activated, the process proceeds to step 270, and the TOrf timer is not activated. If it is determined that the process is not valid, the process advances to step 260.

In step 260, the Toff timer is started, and the process then proceeds to step 270.

In step 270, the current 1 to be applied to the solenoid 190 of the electromagnetic on-off valve 186 is determined based on the map stored in the ROM 206 and corresponding to the graph shown in FIG.
b is calculated according to lb-1b-Albr, and then the process proceeds to step 280.

In step 280, the current 1b calculated in step 270 is applied to the solenoid 190 of the electromagnetic on-off valve 186, thereby driving the bypass valve 196 in the opening direction, and then the process proceeds to step 290.

In step 290, it is determined whether or not the time T off has elapsed, and when it is determined that the time T off has elapsed, the process proceeds to step 340, where the time T off has elapsed.
If it is determined that ff has not elapsed, the process advances to step 300.

In step 300, steps 90, 230, 27
It is determined whether the current 1b calculated at 0 is greater than or equal to the reference value Ibo, and when it is determined that it is not Ibalbo, the process proceeds to step 330, where Ib;i=
When it is determined that it is Ibo, step 31
Go to 0.

In step 310, the pressure Ps of the working fluid in the high pressure flow path read in step 30 is set to the reference value Pso(
<Pc) or more is determined, and PsaPs
If it is determined that it is not o, step 330
The process proceeds to step 320, and when it is determined that it is PB&Pso, the process proceeds to step 320.

In step 320, the current 1b1 calculated in step 190 or the current 1ui calculated in step 150 or 220 is outputted to the variable throttle solenoids 58, 78 to 82 of each pressure control valve. Each pressure control valve is activated to control its control pressure, and then the process proceeds to step 330.

In step 330, as will be explained later with reference to FIGS. 16 and 17, failure determination and diagnosis processing regarding abnormalities such as failures are performed for each part in the hydraulic active suspension, and then step 30 Steps 30 to 330 described above are repeated.

In step 340, the main relay is turned off, thereby ending the control flow shown in FIG. 3 and de-energizing the electrical control device i1200 shown in FIG. .

The above-mentioned pressure control by the bypass valve at the start of operation and at the time of normal operation stop does not constitute a main part of the present invention, and the details of these pressure controls can be found in the application filed by the same applicant as the present applicant. Please refer to Japanese Patent Application No. 63-307189 and Japanese Patent Application No. 63-307190.

Next, the active operation performed in step 150 will be described with reference to FIGS. 8A to 8C and FIGS. 9 to 15.

First, in step 400, each heave target value R
xh, pitch target value RXp, and roll target value Rxr are calculated based on maps corresponding to the graphs shown in FIGS. 9 to 11, respectively, and then the process proceeds to step 410.

In FIG. 9, 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 410, the heave (Xxh
), pitch (Xxp), roll (Xxr), warp (
A displacement mode conversion calculation is performed for Xxw), and then the process proceeds to step 420.

Xxh − (XI +X2) +(X3 +X4
)Xxp=- (X+ 10X2) +CX3+X4)
Xxr- CXI-X2 )+ (X3 -X4)X
XV-(XI-Xt)-(X3-X4) In step 420, the deviation of the displacement mode is calculated according to the following equation, and the process then proceeds to step 430.

E xh - R xh - X xhE xp -
R xp − X xpE xr − R xr −
X xrE KV - R xv - X
Alternatively, it may be the average value of XXV calculated in the past several cycles. Further, in the case of lEy+v1≦W+ (positive constant), E xv- 0 is set.

In step 430, PID compensation calculation for displacement feedback control is performed according to the following equation, and then the process proceeds to step 440.

C xh − K pxh − E xh+ K 1xh
I xh(n) 10K dxh (E xh(n
) - Exh(n-n+)IC XI) - K
pxp ●E Xp10K ixp I xp(
n) + K dxp (E xp(n) − E
xp(n-n+)IC xr - K pxr ●E
xr+ K lxr 1 xr(n) 10K dxr
(Exr(n) − Exr(n-n+)
IC xv − K pxw * E xv+ K l
xv I xw(n)+K dxv (Ex
v(n) − E xw (n-n+)) In each of the above equations, Ej(n) (j=xhs XpSXr, xv
) is the current Ej, and E j (n-n + ) is n1
This is Ej before the cycle. Also, Ij(n) and Ij(
n-1) are the current and one cycle previous Ij, respectively,
I j (n) − E j (n) + T x I j (
n-1), and with I jsax as a predetermined value, lljl
≦1 jmax. Furthermore, the coefficient KpjSKijq K
dj (j-xhq XI)%xr, xw) are a proportional constant, an integral constant, and a differential constant, respectively.

In step 440, an inverse transformation of the displacement mode is calculated according to the following equation, and then the process proceeds to step 450.

Px 1 -1/4 ・Kx H (C
xh-Cxp+Cxr+Cxv)Px 2 -1/4
・Kx 2 (Cxh − Cxp − Cxr −
Cxv) Px 3 -1/4 ●KX 3 (Cx
h+CxptenCxr-CXv)Px 4, -1/4
・Kx 4 (Cxh1Cxp - Cxr
10Xv) Sho Kx IKx 2 , Kx 3 , Kx
4 is a proportionality constant.

In step 450, the longitudinal and lateral directions of the vehicle are determined based on the longitudinal and lateral accelerations, respectively, based on the maps corresponding to the graphs shown in FIGS. 12 and 13 for the longitudinal and lateral directions of the vehicle, respectively. The correction amount of pressure Pga. Pgl is calculated, then step 4
Proceed to 60.

In step 460, the pitch (
Calculation of PD compensation for G feedback control is performed for C gp) and roll (C gr), and then the process proceeds to step 470.

Cgp-Kpgp-Pga+Kdgp ['ga
(n)-P ga(n-nI)I Cgr-Kpgr ●Pgl+Kdgr fPgl(
n) - P gl(n-r++ )1 In each of the above formulas, P ga (n) and Pgl (n) are the current Pga and Pgl, respectively, and P ga (n
-nl) and Pgl(n-n+) are Pga and Pgl before n1 cycles, respectively. Also, K 9g9 and Kpgr are proportional constants, K dgp and K dg
r is a differential constant.

In step 470, 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 θ101θ' as The process then proceeds to step 480.

In step 480, a G-mode inverse transform calculation is performed according to the following equation, and the process then proceeds to step 490.

Pg t -Kg I/4 ●(-Cgp+K2 r
・Cgr 10 Kl f ● Gl) Pg = =Kg t /4 ・(-Cgp-K!!t
-Cgrl\ -K, f◆Gl) Pg 3 -Kg s /4 ● (Cgp+
K2 r * CgrA +K1r ● Gl) Pg 4 −Kg a /4 ●(Cgp−K2 r
◆Cgrl\ -KI r - Gl) Kgl% Kgffi, Kg3, Kg
4 are proportionality constants, K+f and Kl r ,
K2 r and Kl r are constants as distribution gains between the front and rear wheels, respectively.

In step 490, in step 190, the RAM
Based on the pressure Pb1 stored in 20g and the results calculated in steps 440 and 480, P ui - P
xl+P g1+ P b1(l- 1, 2,
3, 4) The target control pressure Pui of each pressure control valve is calculated according to the following, and the process then proceeds to step 500.

In step 500, 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 510.

1 1 mKu IPu 1 +Kh (Psr-P
s )-Kl-Pd-α 12 mKu! Pu 2 +Kh (Psr-Ps
)−l(% ・Pd−α 13 −Ku 3 Pu 3 +Kh (Psr−P
s )-Kl ●Pd 14 mKu 4 Pu 4 +Kh (Psr-P
s ) - Kl - Pd KuI Ku2, Ku3, Kua are proportionality constants for each wheel, Kh and Kl are correction coefficients for the pressure in the high-pressure flow path and the pressure in the low-pressure flow path, respectively, and α
is a correction constant between the front and rear wheels, and I'sr is a reference pressure in the high pressure flow path.

In step 510, a temperature correction coefficient Kt 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. I-1, ?, 3, 4) A temperature correction calculation of the target current is performed, and then the process proceeds to step 520.

In step 520, Iv= (It+ It!) (It3 It4)
According to the current warp (amount of twist around the longitudinal axis of the vehicle body)
After that, the process proceeds to step 530.

In step 530, the deviation of the current warp is calculated according to the following formula using Riv as the target current warp,
Thereafter, the process proceeds to step 540.

Eiw-R1v-1w Note that the target current warp R1v in the above equation may be zero.

In step 540, the current warp target control amount is calculated according to 11vp mKivp * Eiv with K1vp as a proportionality constant, and then in step 550
Proceed to.

In step 550, the inverse transformation of the current warp is calculated according to the following equation, and then the process proceeds to step 560.

lv 1 - Eivp /4 Iv 1! --Elvp /4 Iv 3 = -E1vp /4 ly 4 -E1vp /4 In step 560, based on the results calculated in steps 510 and 550, the pressure is supplied to each pressure control valve according to the following formula, The final target current Iul to be output is calculated, and the process then proceeds to step 300 in FIG.

Iul=lt1+Ivl (1-1, 2, 3, 4) Next, referring to FIGS. 16 and 17, fail judgment and diagnosis processing performed in step 330 of the flowchart in FIG. I will explain about it.

In an initial step 600, a signal indicative of the pressure PI within the working fluid chamber of each actuator is passed through a low-pass filter before proceeding to step 610.

In step 610, based on the signal representing the pressure Pi processed in step 600, Pv = (Pfl-
Pfr) - (Prl-Prr), the pressure warp Pv is calculated, and then the process proceeds to step 620.

In step 620, it is determined whether the absolute value of the lateral acceleration Gl is less than or equal to a reference value A (positive constant), that is, whether the vehicle is substantially traveling straight.
If it is determined that ≦A is not true, step 69
If it is determined that IGII≦A, the process advances to step 630.

In step 630, it is determined whether the absolute value of the warp-related deviation Exv calculated in step 420 of FIG. 8A is less than or equal to the reference value B (positive constant), that is, whether the traveling road surface is a good road. It is determined whether or not, and when it is determined that lExvl≦B, the process advances to step 690;
When it is determined that IExvl≦B, the process advances to step 640.

In step 640, a first reference value is determined based on the map corresponding to the graph shown in FIG. 17 from the vehicle speed V read in step 30 in FIG. SWI and a second reference value SW2 are calculated,
Thereafter, the process proceeds to step 650.

In step 650, based on the current warp Iv calculated in step 520 of FIG. 8C and the pressure warp Pv calculated in step 610, the absolute value of (Iw-K-Py) is calculated using K as a correction coefficient. It is determined whether the value is less than or equal to the first reference value SW1, and Ilv-K*Pwl≦
If it is determined that it is SWI, step 69
If it is determined that lIv-KlIPw l≦SWI is not satisfied, the process proceeds to step 660.

In step 660, it is determined whether the absolute value of (Iv-K-Pv) is less than or equal to the second reference value SW2, and it is determined that f ly-K-Pw l≦SW. is performed, the process advances to step 680 and llw-K-
When it is determined that Pvl≦SW, the process advances to step 670.

In step 670, a control signal is output to the display 232 via the drive circuit 230, so that an alarm indicating that the pressure warp is slightly abnormal is displayed on the display, and the process then proceeds to step 690.

At step 680, flag Fv is set to 1 and an alarm indicating that the pressure warp is severely abnormal is displayed on display 232, followed by step 690.
Proceed to.

In step 690, it is determined whether or not a fail other than pressure warp exists anywhere within the hydraulic active suspension, and if it is determined that there is no fail, the process proceeds to step 710. , if it is determined that a fail exists, the process advances to step 700.

In step 700, it is determined whether the flag Fv is 1 or not, and when it is determined that it is not Fv -1, the process proceeds to step 720, where it is determined that it is Fv -1. If so, the process advances to step 710.

At step 710, flag Ff' is set to 1, and then step 720 follows.

In step 720, diagnosis processing is performed for each part within the hydraulic active suspension, and if an abnormality such as a failure exists, a code number indicating the location is displayed on the display 232, and the code number indicating the location is displayed. If there is no abnormality, the process proceeds to step 30 in FIG. 3 without displaying the code number on the display.

Thus, in the illustrated embodiment, a YES determination is made in step 620, that is, a determination that the vehicle is traveling substantially straight ahead, and a YES determination is made in step 630, ie, the driving road surface is a good road. When it is determined that this is the case, it is determined in steps 650 and 660 whether the absolute value of Iv=K−Pv is less than or equal to the first reference value Sw1, and less than or equal to the second reference value Sv2, respectively. It is determined whether or not.

When the absolute value of Iw-KePv exceeds the first reference value and is less than the second reference value, there is a slight abnormality in the pressure warp, so a warning to that effect is displayed on the display 232. This alerts the driver of the vehicle.

Furthermore, when the absolute value of Iv-K◆Pw exceeds the second reference value, it means that there is a severe abnormality in the pressure warp, so an alarm to that effect is displayed on the display, and a flag Fw related to the pressure warp is displayed. is set to 1. Therefore, the active control is stopped by the determination of YES in steps 60 and 210 of the flowchart of FIG. Then, in steps 230 and 240, the pressure in the high-pressure flow path is gradually reduced and the shutoff valve is closed, whereby each actuator performs corresponding pressure control with the pressure in the working fluid chamber of each actuator set to the standby pressure. Isolated from the valve, each actuator functions as a hydropneumatic suspension.

As is clear from the above explanation, according to the illustrated embodiment, abnormalities in pressure control are determined based on the pressure warp, which is not affected by acceleration or deceleration of the vehicle, so that the vehicle can maintain a constant speed on a flat road. It is possible to accurately determine abnormalities in pressure control not only when the vehicle is traveling straight ahead on a flat road while accelerating or decelerating, but also when the vehicle is traveling substantially straight on a flat road while accelerating or decelerating. An abnormality in pressure control can be detected earlier than in the case where abnormality determination is only performed when the vehicle is traveling straight ahead.

Furthermore, according to the illustrated embodiment, when the vehicle turns or runs on a rough road, no abnormality determination of the pressure control is performed, so that the active suspension described in the above-mentioned Japanese Patent Laid-Open No. 64-22613 is not used. As in the above case, the risk of erroneous determination of pressure control abnormality can be reduced compared to the case where an abnormality determination is made even when the vehicle turns or travels on a rough road.

Furthermore, according to the illustrated embodiment, if the pressure control abnormality is minor, the active control is not directly stopped, but a warning is issued to the vehicle driver while the active control is maintained. It is possible to ensure the active control function while alerting the vehicle driver, and if the pressure control abnormality is severe, the pressure in the working fluid chamber of each actuator is set to the standby pressure. Since each actuator is isolated from the pressure control valve, active control is continued to prevent deterioration of turning performance, for example, when the vehicle makes a sharp turn in the presence of excessive pressure warp. be able to.

Further, according to the illustrated embodiment, the abnormality determination reference values SW1 and SW! ! Since these values are set to decrease as the vehicle speed increases, abnormality determination can be made more strictly in the medium to high speed range than if these reference values were constant regardless of the vehicle speed.

In the above-mentioned embodiment, normal active control is performed when the pressure control abnormality is minor, but the flag indicating whether the pressure control abnormality is minor is set as Fwl. Assuming that Fvl-1 means that a slight abnormality exists, the flag Fvl is set to 1 in step 670, and then in step 150, Fvl-1 is set to 1.
If it is not Fwl-ml, the process proceeds to step 300, and if Fvl=1, based on the calculation result in step 150, the pressure is supplied to the pressure control valves for the left and right front wheels and the left and right rear wheels. The average value of the current may be calculated, and each pressure control valve may be controlled in step 320 based on the average value.

Furthermore, in the above embodiment, if the pressure control abnormality is severe, the pressure in the working fluid chamber of each actuator is set to the standby pressure. The pressure in the working fluid chambers of the left and right front wheel actuators detected by the pressure sensors is the average value of the working fluid chambers of the left and right front wheel actuators, and the pressure in the working fluid chambers of the left and right rear wheel actuators detected by the pressure sensors is the average value of the pressures in the working fluid chambers of the left and right rear wheel actuators, respectively. May be set.

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

Effects of the Invention According to the present invention, a pressure control abnormality is determined when the deviation between the actual pressure warp and the target pressure warp, which is not affected by acceleration or deceleration of the vehicle, exceeds a reference value. Accurate abnormality judgments can be made not only when the vehicle is traveling straight on a road at a constant speed, but also when the vehicle is traveling substantially straight on a flat road while accelerating and decelerating. Compared to the case where abnormality determination is performed only when traveling straight at high speed, abnormality in pressure control can be detected without delay.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram showing a fluid circuit of one embodiment of a hydraulic suspension according to the present invention, FIG. 2 is a block diagram showing an electric control device of the embodiment shown in FIG. 1,
FIG. 3 is a flowchart showing the control flow achieved by the electric control device shown in FIG. 2, and FIGS.
The diagrams show when the hydraulic suspension starts operating,
A graph showing a map used when calculating the current 1b supplied to the bypass valve during a normal operation stop and an abnormal situation. Current Ib supplied to the pressure control valve
Figures 8A to 8A are graphs showing the relationship between the vehicle speed V and the vehicle speed V. FIG. 10 is a graph showing the relationship between longitudinal acceleration Ga and target displacement amount Rxp, and FIG. 11 is a graph showing the relationship between lateral acceleration G1 and target displacement amount Rxr. 12 is a graph showing the relationship between longitudinal acceleration Ca and pressure correction Pga, and FIG. 13 is a graph showing the relationship between lateral acceleration Gl and pressure correction Pgl. Figure 14 is a graph showing the relationship between vehicle speed V, steering angular velocity θ, and predicted lateral acceleration change rate G1.
16 is a graph showing the relationship between the temperature T of the working fluid and the correction coefficient Kt. FIG. Figure 17 shows the vehicle speed ■ and the reference value Svl used for pressure warp abnormality determination.
and Sv2. I FR, I FL, I RR, I RL...
Actuator, 2Fl? , 2FL, 2Rf? , 2
J? L... Working fluid chamber, 4... Reserve tank, 6
...Bomb, 8...Filter, 10...Suction channel. 12... Drain flow path, 14... Engine, 16...
...Rotation speed sensor, 18...High pressure flow path. 20...Check valve. 22... Attenuator, 24, 26... Accumulator, 32, 34, 36, 38... Pressure control valve, 40, 42, 44, 46... Switching control valve, 48
...Low pressure flow path, 52...Fixed throttle, 54...Variable throttle, 56...Connection flow path, 58...Solenoid, 6
6, 68, 70... fixed aperture, 72, 74, 76...
・Variable aperture. 78, 80, 82... Solenoid, 84
, 86, 88... Connection channel, 110-118... Drain channel, 120... Filter. 124-130...
・Aperture, 132-138...Accumulator, 144
PR, 144FL, 144RR, 144RL...Vehicle height sensor, 150-156...Shutoff valve, 166-172
... Relief valve, 174 ... Oil cooler, 176
... Filter, 180 ... Relief valve, 182 ...
・Filter, 184...Aperture. 186... Solenoid on-off valve, 190... Solenoid, 192... On-off valve, 1
96...Bypass valve. 197, 198, 199PR
．． 1 99PL, 1 99RR, 1 99RL
... Pressure sensor, 200 ... Electric control device, 20
2...Microcomputer, 204...CPU,
206...ROM, 208...RAM, 210...
- Input boat device, 212... Output boat device, 21
6...IGSW, 218...EMSW, 220~2
30...Drive circuit. 232...display unit, 234...
・Vehicle speed sensor, 236... Front and rear G sensor, 238...
・Lateral G sensor, 240...Steering angle sensor. 248...
・Vehicle height setting switch 4 Figure 5 Figure 6 Figure 7 Figure 8A Figure 8C Figure ■ Figure 8B Figure ■ Figure 9 Figure 10 Figure 11 Figure 12 Figure 12 Pga Figure 13 Pgl Figure 15 Figure 16 Figure 0 Figure 14 Figure 17 Figure ■

Claims (1)

[Claims] A fluid pressure actuator disposed between each wheel and the vehicle body, a pressure adjusting means for adjusting the pressure within the actuator, and a predetermined pressure warp in which the pressure within the actuator is determined according to the running state of the vehicle. a control means for controlling the pressure adjusting means to achieve a target control pressure of; a pressure detecting means for detecting the pressure within the actuator;
A fluid pressure type active device having means for determining an actual pressure warp from the pressure detected by the pressure detection means, and means for determining an abnormality in pressure control when the deviation between the actual pressure warp and the target pressure warp exceeds a reference value. suspension.