JPH04191112A - Active suspension for vehicles - Google Patents

Abstract

PURPOSE:To improve riding comfort by computing the time required for each rear wheel to come to the irregularities of the surface of a road when the change in pressure of the hydraulic actuator of each front wheel exceeds a specified value, and thereby controlling the actuator of each rear wheel in such a way that change in inner pressure is in anti-phase with respect to that of the actuator after the aforesaid time has elapsed. CONSTITUTION:The variation of the inner pressure of the hydraulic actuator 14 of each front wheel, which is inputted from a pressure sensor 3O, is detected by the rear wheel correction control section 42 of a controller 23 so as to be stored. And when the maximum value of the variation exceeds a specified one, the time required for each rear wheel come to the irregularities of the surface of a road causing change in pressure, is computed based on the vehicle speed detected by a vehicle speed sensor 24 and a wheel base. The variation of each rear wheel is thereby restrained with signals in anti-phase with respect to signals due to change in inner pressure outputted to the hydraulic actuator 14 after the aforesaid time has elapsed.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to improvements in active suspensions for vehicles used in vehicles such as automobiles.

(Prior art) Conventionally, for example, as shown in Japanese Patent Application Laid-Open No. 64-90811, a non-contact road sensor is used to predict the unevenness of the road surface in front of the wheels, and the wheel passes over the unevenness. Active suspensions are known that control the operation of actuators to keep the displacement of the vehicle body constant when the vehicle is moved.

(Problem to be Solved by the Invention) However, when the operation of the actuator is simply controlled according to the unevenness of the road surface detected by the road sensor as in the above conventional example, the front and rear wheels are controlled before passing the unevenness of the road surface. As the amount of vibration is set, there may be cases where a relatively large vibration is generated in the vehicle body when the front wheels pass the unevenness even though the control is performed. There is a problem in that similar vibrations are generated, which tends to cause discomfort to the occupants.

(Means for Solving the Problems) The present invention has been devised in view of the above points, and is provided with a device interposed between the vehicle body and each wheel so as to be able to increase or decrease the supporting force of the vehicle body with respect to the wheels. a fluid actuator, a pressure detection means for detecting the internal pressure of the fluid actuator on the front wheel side, and a vehicle speed detection means for detecting the running speed of the vehicle;
and a control means for controlling the operation of the fluid actuator based on the detection output of each of the detection means, and the control means is configured such that the change in the internal pressure of the fluid actuator on the front wheel side detected by the pressure detection means reaches a predetermined value. When it is detected that the vehicle speed has exceeded the level, the delay time required for the rear wheels to reach the uneven road surface where the internal pressure has changed by a predetermined value or more is calculated based on the output of the vehicle speed detection means, and the delay time required for the front wheels to reach the uneven road surface where the internal pressure has changed by a predetermined value or more is calculated. An active suspension for a vehicle, characterized in that the active suspension for a vehicle is configured to operate a fluid actuator on the rear wheel side in response to a control signal obtained by inverting the phase of a signal based on the change in internal pressure after the delay time from when the vehicle passes through the vehicle. It is.

(Function) According to the present invention, when the change in the internal pressure of the fluid actuator on the front wheel side due to road surface irregularities exceeds a predetermined value, the change in the internal pressure of the front wheel side fluid actuator due to road surface irregularities is determined based on the output of the vehicle speed detection means. The delay time until the rear wheels reach the road surface is calculated, and a signal based on the change in the internal pressure of the fluid actuator on the front wheel side when the front wheels pass the road surface unevenness is generated after the above delay time from the time the front wheels pass the road surface unevenness. Since the control means is configured to operate the fluid actuator on the rear wheel side in accordance with the control signal obtained by inverting the phase, even if relatively large vibrations occur in the vehicle body when the front wheels pass over uneven road surfaces, the rear wheels When the front wheel passes through the bumps, control is performed to suppress changes in the internal pressure of the fluid actuator on the rear wheel side by referring to changes in the internal pressure of the fluid actuator when the front wheels pass through the bumps. Vibration input can be reduced compared to when the vehicle passes over uneven surfaces, providing better ride comfort for the occupants.

(Example) Hereinafter, an example of the present invention will be described in detail based on the accompanying drawings.

FIG. 1 is a schematic diagram of the system configuration of this embodiment.

In FIG. 1, an oil pump 1 is provided to suck oil stored in a reserve tank 3 through an oil passage 2 and discharge the oil to a supply oil passage 4. As shown in FIG. Supply oil path 4
An oil filter 9 and a check valve 10 are interposed therein, and the check valve 10 prohibits oil from flowing from the downstream side to the upstream side. An accumulator 11 for maintaining line pressure is located downstream of the check valve 10 in the supply oil line 4.
is connected, and on the downstream side of the Akicomulator 11,
A suspension unit 12 is connected. Although one suspension unit 12 is shown as a representative in FIG. 1, the suspension unit 12 is provided for each wheel, and each suspension unit 12
A return oil passage 6 communicating with the server tank 3 is also connected.

Each suspension unit 12 has the same structure, and between the vehicle body 7 and the wheels 8 is a suspension spring 13 and a single-acting hydraulic actuator 14.
A control valve 17 interposed between an oil passage 16 communicating with the oil pressure chamber 15 of the hydraulic actuator 14 and the supply oil passage 4 and the return oil passage 6 controls the oil pressure to the oil pressure chamber 15 of the hydraulic actuator 14. The supply and discharge of the fuel is controlled. The control valve 17 controls the pressure acting on the hydraulic actuator 14 by controlling the flow rate of oil flowing from the supply oil path 4 side to the discharge oil path 6 side, and controls the valve opening according to the supplied current value. It has become something that will be done. Therefore, this control valve 17 can control the pressure within the hydraulic actuator 14 in proportion to the supplied current value, and the larger the supplied current value, the greater the supporting force generated by the hydraulic actuator 14. It has become something to do.

Further, an oil passage 15 communicating with the hydraulic chamber of the hydraulic actuator 14 is connected to an accumulator 2 via a first orifice 19.
0 is connected, and the first orifice 19 exhibits a vibration damping effect, and the akicomulator 20 is filled with gas to exhibit a gas spring action. Further, a second orifice 21 is provided between the accumulator 20 and the oil passage 16 in parallel with the first orifice 19, and a switching valve 22 is provided between the second orifice 21 and the accumulator 20. , which switches communication and cutoff between the second orifice 21 and the accumulator 20. And the second orifice 2
1 has an orifice diameter larger than that of the first orifice 19.

Further, the switching valve 22 is normally turned off and is in the cutoff state shown in the figure.

The operation of the control valve 17 and the switching valve 22 is controlled by a controller 23 composed of a microcomputer. This controller 23 includes a vehicle speed sensor 24 that detects the running speed of the vehicle, a steering angle sensor 25 that detects the steering angle of the steering wheel, a lateral G sensor 26 that detects the left-right acceleration acting on the vehicle body, and a lateral G sensor 26 that detects the acceleration acting on the vehicle body in the longitudinal direction. a longitudinal G sensor 27 that detects the acceleration of the vehicle, a vertical G sensor 28 that detects the vertical acceleration acting on the springs of the vehicle body corresponding to each wheel, and a vehicle height sensor that is provided for each wheel and detects the stroke amount of the wheel. Detection output of sensor 29, hydraulic actuator 14 and first orifice 1
9, a pressure sensor 30 for each wheel is installed in the oil passage 16 to detect the internal pressure of the hydraulic chamber 15, a throttle sensor 31 detects the opening of the engine throttle valve, and a brake pedal operating state is detected. A brake switch 32 and a pair of left and right preview sensors 33 provided at the front of the vehicle body for right and left wheels are connected to the brake switch 32 and a pair of left and right preview sensors 33 for right and left wheels, respectively, to detect the presence of a protrusion on the road surface in front of the vehicle. and,
The controller 23 controls each control valve 17 and each switching valve 22 based on the detection outputs of these sensors 24 to 33.
The operating state of each wheel is controlled individually. As the preview sensor 43, an ultrasonic sensor is used which is arranged in front of the vehicle body and tilted downward.

The basic control operations for control valve 17 performed within controller 40 are represented by the control block diagram shown in FIG. That is, the output of the vertical G sensor 28 is integrated by an integrator 35 and then multiplied by KI by an amplifier 36, and the output of the vehicle height sensor 29 is differentiated by a differentiator 37 and then multiplied by KP by an amplifier 38. Ru. and amplifier 36.3
The output of 8 is input to an adder 39 and added to the control amount for vehicle height maintenance stored or calculated in the controller 23. The output of the adder 39 is input to the valve drive unit 40, and the valve drive unit 40 controls the pressure sensor 3 so that the hydraulic actuator 14 generates a control amount corresponding to the output of the adder 39.
Control valve 17 while feeding back the detection output of 0.
Outputs a drive signal to. In this way, the control valve 17
The operation of the hydraulic actuator 14 is controlled, and the hydraulic actuator 14 expands and contracts to effectively absorb human vibrations, thereby providing a soft ride.

Although not shown in the figure as control for the control valve 17, it goes without saying that known active suspension control i, such as control for suppressing vehicle body posture such as rolling or pitching, is also performed in response to acceleration acting on the vehicle body. .

On the other hand, a preview sensor 33 is provided in the controller 23.
a preview control unit 41 that detects unevenness on the road surface in front of the vehicle based on the detection output of the preview control unit 41 and controls the operation of the switching valve 22;
, and a rear wheel correction control section 42 that corrects and controls the operation of the control valve 17 for the rear wheels based on road surface passing information for the front wheels. Note that the rear wheel correction control section 42 constitutes a control means of the present invention.

First, to explain the preview control ta41, the control operation of the switching valve 22 performed by the preview control section 11 is represented by the control flowchart shown in FIG.

To explain the flowchart shown in Figure 3,
First, in step Δ1, the fluctuation frequency of the output of the vehicle height sensor 29 is calculated, and in the subsequent step A2, it is determined whether the calculated fluctuation frequency is greater than or equal to a predetermined value, thereby determining whether the fluctuation frequency corresponds to a high-frequency road surface. If it is determined that it corresponds to a high-frequency road surface, the process proceeds to step A3, where the switching valve 22 is turned on and opened to set the suspension characteristics softly, and then the process is returned. The processing from step S1 onwards is repeated.

Further, when it is determined in step A2 that the fluctuating frequency does not correspond to a high-frequency road surface, the process proceeds to step A4, and it is determined whether or not there is a protrusion or step on the road surface in front of the vehicle based on the output of the preview sensor 33. Step A4
If it is determined that there is no protrusion or step, there is no need to soften the suspension characteristics, so proceed to step A.
The process proceeds to step 5, where the switching valve 22 is turned off to be in the closed state, and then the process returns.

On the other hand, if it is determined in step A4 that there is a protrusion or step, the process proceeds to step 86, where the time required for the wheel to reach the protrusion or step is calculated. This time is
As shown in Figure 4, the distance between the protrusion or step on the road in front of the vehicle and the wheel (in the case of the front wheels, L in the case of the rear wheels).
+1) and the vehicle speed ■ detected by the vehicle speed sensor 24. In this case, preview sensor 3
If 3 detects the presence or absence of a protrusion or step at a predetermined distance in front of the vehicle body, the above L value will be a fixed value, and if the distance to the protrusion or step can be detected, the above L value will be This is the measured value.

After the time required for the wheel to reach the protrusion or step is calculated in step A6, the process proceeds to step A7, where it is determined whether or not the time calculated in step A6 has elapsed; if the time has not elapsed, then This determination is repeated, and when the time comes for the wheel to reach a protrusion or step, the process proceeds to step A8.

Then, in step 88, the switching valve 22 is turned on for a predetermined time t for the wheel on the same side as the preview sensor that detected the protrusion, and the second orifice 21 and the Akicomulator 20 are communicated via the switching valve 22. The suspension characteristic is set to be soft, and after the predetermined time t has elapsed, the switching valve 22 returns to the OFF state, and thereafter, the process returns and the step SID lowering process is repeated.

The preview control unit 41 that performs the above-described control controls the switching valve 2 when the fluctuation frequency of the vehicle height sensor output is equal to or higher than a predetermined value (when high-frequency vibrations are continuously input).
2 is turned on, while the switching valve 22 is turned on for a predetermined time t when passing over a protrusion (when high frequency vibration is inputted singly). Then, by turning on the switching valve 22, the second orifice is opened, and since the orifice diameter of the second orifice 21 is larger than the first orifice 19, the substantial The orifice diameter increases greatly. This reduces the damping force and the vibration transmission force to the vehicle body, making it possible to efficiently attenuate high-frequency vibration human force, and in particular, greatly reduce the feeling of pushing up when going over a bump. Further, after the predetermined time t has elapsed, the switching valve 22 is turned off again and the damping force increases, so that vibrations after riding over the protrusion can be efficiently contained.

Further, the correction control for each rear wheel hydraulic actuator 14 performed by the rear wheel correction control section 42 is represented by the control flowchart shown in FIG.

To explain the flowchart of FIG. 5, first, in step S1, timers 1 to 4, which will be described later, are set as initial settings.
and memory S max.

ΔP max and flag are cleared, followed by step S2
Now read the detection outputs of various sensors required for control. After step S2, the process proceeds to step S3, where it is determined whether the vehicle speed V detected by the vehicle speed sensor 24 is within a predetermined range of 30 to 120 kmb, and if it is within the predetermined range, the process proceeds to step S4. It is determined whether the steering angle θ detected by the steering angle sensor 25 is 10 degrees or less, that is, whether the vehicle is traveling substantially straight. If it is determined in step S4 that the vehicle is traveling substantially straight, the process proceeds to step S5, where it is determined whether or not the opening speed U of the throttle valve detected based on the detection output of the throttle sensor 31 is 20 deg/S or less, that is, if the It is determined whether the vehicle is not starting or accelerating rapidly.
If it is not a sudden start or sudden acceleration, the process advances to step S6. Then, in step S6, it is determined whether or not the brake switch 32 is off, that is, whether braking is not in progress. If braking is not in progress, that is, the vehicle speed is within a predetermined range, the vehicle is traveling approximately straight, and the vehicle suddenly starts and accelerates. If braking is not in progress, the process advances to step S7, which will be described later.

By the way, if it is determined in step S3 that the vehicle speed V is not within the predetermined range, it is determined that the effect of the control described later is small, and the process returns to step S1 described above.
If it is determined in Step 4 that the vehicle is not traveling substantially straight, if it is determined in Step S5 that the vehicle is suddenly starting or rapidly accelerating, and if it is determined that the vehicle is braking in Step S6, the control described below will have an adverse effect on the attitude control of the vehicle body. In order to avoid this, the process returns to step S1 and the subsequent processes are repeated.

Proceeding to step S7 described above, the stroke S of the front wheel, which is determined based on the detection output of the vehicle height sensor 29 of the front wheel corresponding to the rear wheel to be controlled (front wheels on the same side of the left and right positions), and the stroke S of the front wheel corresponding to the rear wheel to be controlled, Compatible front wheels (front wheels with same left and right positions)
The amount of pressure change ΔP(
The difference between the pressure sensor output and the reference pressure) is stored in the memory, and these are stored and retained for a certain period of time. Therefore, the detection information of the front wheel stroke S and pressure change amount ΔP from a certain period of time ago is stored in the memory, and this certain period of time is set to be sufficient time to perform the control described later. ing.

In step S8 following step S7, it is determined whether or not timer 1 is on. Since it is initially in the off state, the process proceeds to step S9 and the absolute value of the front wheel stroke S is 5.
It is determined whether or not it is less than "mm".

If the absolute value of the stroke S of the front wheel is 5 mm or more, the process advances to step 510 and timer 1 is turned on.

After that, when the process proceeds to step Sll, it is determined whether or not the timer 2 is on, and since it is initially in the off state, the process proceeds to step S12, where the absolute value of the pressure change amount ΔP in the front wheel side hydraulic actuator 14 is 4. It is determined whether or not it is equal to or greater than Kg/cut. If the absolute value of the pressure change ΔP on the front wheel side is 4 g/cr1 or more, the process advances to step S13 and timer 2 is turned on. Step S14 following step S13
Then, it is determined whether the timer 4 is on or not. Since it is initially in the off state, the process advances to step S15, where the timer 4 is turned on and the process proceeds to step 516. However, if the timer 4 is already on, the process proceeds to step 514. Proceed directly to step 816.

After the above step 514 or step S15 has passed,
If it is determined in step 39.12 that the stroke S or the absolute value of the pressure change ΔP is less than the predetermined value, the process proceeds to step 516, where it is determined whether the flag is 1 or not. , is initially 0, so the process returns to step S2 described above.

After that, if the timer 1 is on when the process reaches step S8 again, the process proceeds from step S8 to step S17 to determine whether the time T1 in the timer 1 exceeds a predetermined time TCI (front wheel stroke sampling time). If it is within the predetermined time TCI, step Sl
Proceed to l. In this way, if timer 2 is on when step Sll is reached again, the process advances from step Sll to step 318, and time T2 in timer 2 is set to T.
It is determined whether or not the predetermined time T[:2 (front wheel pressure change amount sampling time) longer than CI has been exceeded, and if it is within the predetermined time Te3, the process proceeds to step S16 described above, since the flag is initially 0. Returning to step S2 described above.

The above-mentioned processing is slowly returned and the time T1 in timer 1
exceeds the TCI for a predetermined time, step 51
7, the process advances to step S19, where it is determined whether or not timer 2 is on. If it is determined in step S19 that timer 2 is not on, this is a situation where a certain amount of front wheel stroke occurred, but no large pressure change occurred in the front wheel side hydraulic actuator 14. , it is determined that rear wheel correction control, which will be described later, is not necessary, and the process returns to step S1, where timer 1.
4 is turned off.

If it is confirmed in step 519 that the timer 2 is on, the process proceeds to step S18 described above, where it is determined whether or not the time T2 in the timer 2 exceeds the predetermined time TC2. If so, the process proceeds from step 518 to step 520.

In step S20, the maximum absolute value of the front wheel strokes S detected from when timer 1 is turned on until reaching TC1 time is detected as the front wheel maximum stroke S max, and in subsequent step S21, timer 2 is turned on. The maximum absolute value of the front wheel side pressure change amounts ΔP detected from the time TC2 hours is reached is detected as the front wheel maximum pressure change amount ΔPmax. After that, when the process proceeds to step S22, it is determined whether the absolute value of the front wheel maximum stroke Smax is 30mm or more, and 30ITll.
If it is T1 or more, the process advances to step S23 and the absolute value of the front wheel maximum pressure change amount ΔP max is 20 Kg/cn! It is determined whether or not the value is greater than or equal to the value. Then, step S23
If it is determined that the absolute value of ΔP max is less than 20 g/cat, and if it is determined that S max is less than 30 mm in step 322, the vibration input when the front wheels pass is not so large and the rear It is determined that there is no need to start wheel correction control, and the process proceeds to step S24, where it is determined whether or not the flag is 1. Since it is initially 0, the process returns to step S1.

In step S23, ΔP max is 20 Kg/cI1
If it is determined that it is less than 1 or more, that is, the front wheel maximum)
Loaf S max and front wheel maximum pressure change ΔP max
If both exceed the predetermined values, it is determined that the vibration input from the road surface when the front wheels pass is large and it is necessary to perform correction control for the rear wheels, and the process proceeds to step S25. In step S25, timer 1.2 is turned off, and in subsequent step S26, timer 3 is turned on. Note that if timer 3 is already turned on in step 526, it is reset. After step 326, the process advances to step S27 and the flag is set to 1.
It is determined whether or not the flag is 0. Since it is initially 0, the process proceeds to step 828, and the flag is set to 1.

Subsequently, in step S29, a delay time TR until the rear wheels pass the road surface that the front wheels have passed is calculated using the following arithmetic expression.

TR = (3,61/V) - Δ, where l is the wheel base ■ is the vehicle speed Δt is the calculation and response delay time TR unit is seC. In the subsequent step S30, the time T4 in the timer 4 is changed to step S29. It is determined whether or not the calculated delay time TR has been exceeded. If the delay time TR has not been reached, the process returns to step S2 and the subsequent processing is repeated.

When the process returns to step S2 in this way, the timer 1.2 is off, so the process goes through step 816, and since the flag is 1, the process goes from step S16 to step 531. In step S31, it is determined whether or not the time T3 in the timer 3 exceeds a predetermined time TC3 (rear wheel control end time).
(Since it is set, it is determined that the time T3 is less than or equal to the predetermined time TC3, and the above-mentioned step S3
Return to 0.

Such processing is repeated until the time T4 in timer 4
When (the elapsed time since a pressure change of a predetermined value or more occurs in the front wheels) exceeds the delay time TR, the process advances from step S30 to step S32. In step S32, the TR time (
The correction control amount for the rear wheels is calculated based on the pressure change amount ΔP before the delay time TR). Specifically, as shown in FIG. 6, the stored signal of the pressure change ΔP on the front wheel side is once integrated, and the value of the signal obtained by inverting the phase of this integrated signal before the TR time is calculated. It is used as a correction control amount.

Then, in the following step S33, the control amount calculated in step S32 is output, and then the process returns to step S2 and the subsequent processes are repeated. In this case, the correction control for the rear wheels can be carried out by, for example, adding a correction control amount to the output of the adder 39 shown in FIG. 2, or adding a correction control amount to the vehicle height maintenance control amount. All you have to do is increase or decrease the amount of control.

” By the control described in item 1 above, the special correction control amount as shown in FIG. When exceeds the predetermined time TC3 (rear wheel control end time), the process returns from step 531 to step S1, the correction control for the rear wheels is temporarily ended, and the above-described process is repeated.

In addition, since the processing related to timer 1゜2 is performed even after the -1 flag becomes 1, both the front wheel maximum stroke Smax and the maximum pressure change amount △Pmax are set to a predetermined value during correction control for the rear wheels. In some cases, a situation in which the value is exceeded is detected, but in such a case, timer 3 is reset in step 326, so the time at which time T3 in timer 3 exceeds the predetermined time TC3 is substantially extended. Therefore, correction control for the rear wheels is performed continuously on a road surface with continuous road surface irregularities of a certain degree or more.

The rear wheel correction control unit 42, which performs the above-described control, is configured to operate the front wheel correction control unit 42 when, during normal straight-ahead travel in a predetermined vehicle speed range, the front wheels pass through unevenness on the road surface, a stroke of a predetermined amount or more is generated in the front wheels, and the front wheel hydraulic actuator If a pressure change of more than a predetermined value occurs in 14, correction control is performed based on the internal pressure change of the front wheel actuator when the front wheel passes the unevenness at the time the rear wheel passes the unevenness. In other words, the road surface unevenness is detected based on the internal pressure change of the front wheel actuator when the front wheel passes the road surface unevenness, and the control amount to the rear wheels on the same side as the front wheel is corrected in a direction that reduces the internal pressure change. Therefore, it is possible to effectively alleviate the impactful vibration force exerted when the rear wheels pass over the uneven road surface.

In addition, the correction amount for the control amount for the rear wheels is derived by inverting the phase of the signal obtained by integrating the internal pressure change of the front wheel actuator, making it possible to obtain stable performance that is resistant to noise. .

According to the above embodiment, the preview control section 41 performs damping force control based on the preview sensor output, and the rear wheel correction control section 42 performs correction control for the rear wheels based on road surface passing information of the front wheels. Therefore, when the preview sensor 33 detects a protrusion or step on the road surface, the damping force can be lowered to reduce the vibration input when passing the protrusion or step. 33, even when a protrusion or step on the road cannot be detected, it is possible to reduce the vibration force when the rear wheel passes through an uneven surface compared to when the front wheel passes through an uneven surface.
The riding comfort of a vehicle can be efficiently improved.

In addition, the correction control for the rear wheels is performed based on the internal pressure change of the front wheel actuator when the front wheel passes over an uneven road surface, so that the internal pressure change is offset. It is possible to perform corrections to cancel vibrations, effectively improving riding comfort, and because the signal obtained by dividing and inverting the phase of the internal pressure change signal of the front wheel actuator is used as the correction control amount, stable riding can be achieved. It has the effect of improving comfort.

It should be noted that the present invention is not limited to the above-mentioned embodiments; for example, the damping force control by the preview control section 41 may be abolished, or regarding the correction control for the rear wheels,
The determination regarding the front wheel stroke may be abolished, or the detection output of the vertical G sensor 28 may be used in combination. Furthermore, the order of the integral processing and phase inversion processing for the detection signal of the internal pressure change of the front wheel actuator may be reversed, or the integral processing may be abolished. It goes without saying that modifications can be made.

(Effects of the Invention) As described above in detail with the embodiments, according to the present invention, even if a relatively large vibration occurs in the vehicle body when the front wheels pass through the unevenness of the road surface, when the rear wheels pass the unevenness, the front wheels Since the control is performed in a direction to offset the internal pressure change by referring to the internal pressure change of the front wheel fluid actuator when the rear wheel passes the unevenness, it is possible to reduce the vibration input when the rear wheel passes the unevenness compared to when the front wheel passes the unevenness. This has the effect of providing an active suspension for a vehicle that can provide better ride comfort for the occupants.

[Brief explanation of the drawing]

FIG. 1 is a schematic system configuration diagram showing an embodiment of the present invention;
FIG. 2 is a control block diagram schematically showing the basic control contents for the control valve 17, FIG. 3 is a flow chart diagram showing the control contents in the preview control section 41, and FIG. 4 is a control block diagram showing the basic control contents for the control valve 17. FIG. 5 is a flowchart showing the details of control in the rear wheel correction control section 42, and FIG. 6 is an evening/imming chart showing the outline of control when passing through uneven road surfaces. DESCRIPTION OF SYMBOLS 1...Oil pump, 14...Hydraulic actuator 17...Control valve, 22...Switching valve 23...
・Controller, 24...Vehicle speed sensor 29...Vehicle height sensor, 30...Pressure sensor 42...Rear wheel correction control unit Applicant Mitsubishi Usu f' Car Industry Co., Ltd. Figure 3 Figure 6 Procedure Amendment, 8) Indication of the September 3, 1990 case Patent Application No. 321957 of 1990 Person making the amendment The "Detailed Description of the Invention" column of the specification, Drawing 1, page 20 of the specification r3 (2nd line, 3rd line on the same page, and 8th line on the same page)
1++a'' is corrected to '10mm1. 2. Line 5 on page 20, line 7 on page 7, and line 144 on page 20 r 20 kg/cn! Correct J to "6 kg/Cl11". 3. Correct Figure 5 as shown in the attached sheet. Applicant Mitsubishi Motors Corporation

Claims (1)

[Claims] A fluid actuator is interposed between the vehicle body and each wheel and is provided to be able to increase or decrease the supporting force of the vehicle body with respect to the wheel; a pressure detection means for detecting the internal pressure of the fluid actuator on the front wheel side; and pressure detection means for detecting the internal pressure of the fluid actuator on the front wheel side. It has a vehicle speed detection means for detecting the vehicle speed, and a control means for controlling the operation of the fluid actuator based on the detection output of each of the detection means, and the control means controls the operation of the fluid actuator on the front wheel side detected by the pressure detection means. When it is detected that the change in internal pressure exceeds a predetermined value, the system calculates the delay time until the rear wheels reach the uneven road surface that caused a change in internal pressure by more than the predetermined value based on the output of the vehicle speed detection means. The fluid actuator on the rear wheel side is configured to operate in response to a control signal obtained by inverting the phase of a signal based on a change in internal pressure after the delay time from when the front wheel passes the uneven road surface. Features of active suspension for vehicles