JPH04191111A - Active suspension for vehicle - 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 based on the detected vehicle speed when the detected vertical acceleration of a body exceeds a specified one, and thereby controlling each rear wheel actuator based on signals in anti-phase with respect to signals due to vertical acceleration after the aforesaid time has elapsed. CONSTITUTION:The vertical acceleration of a body by a vertical G sensor 28 is stored by a rear wheel correction control section 42 of a controller 23 for the specified period of time. The maximum vertical acceleration is then detected based on the result of stored memory. And when the maximum vertical acceleration exceeds a specified one, the time required for each rear wheel to come to the irregularities of the surface of a road causing the aforesaid vertical acceleration, is computed based on the vehicle speed detected by a vehicle speed sensor 24 and the dimension of a wheel base. Each actuator of the rear wheels is thereby controlled while the control amount of correction for each rear wheel which is operated based on the vertical acceleration, is outputted after the aforesaid time has elapsed.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an improvement in a vehicular active suspension used in a vehicle such as an automobile.

(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 that is interposed between a vehicle body and a rear wheel and is capable of increasing and decreasing the supporting force of the vehicle body with respect to the rear wheels. a vertical acceleration detection means for detecting the vertical acceleration acting on the vehicle body due to vibration input from the front wheels due to road surface irregularities; a vehicle speed detection means for detecting the traveling speed of the vehicle; and control means for controlling the operation of the actuator, and when the control means detects that the vertical acceleration of the vehicle body detected by the vertical G detection means exceeds a predetermined value, the control means controls the operation based on the output of the vehicle speed detection means. calculates the delay time until the rear wheel reaches the uneven road surface that has been given a vertical acceleration of more than the predetermined value, and then outputs a signal based on the vertical acceleration after the delay time from the time when the front wheel passes the uneven road surface. The active suspension for a vehicle is characterized in that the actuator is actuated in accordance with a control signal obtained by inverting the actuator.

(Function) According to the present invention, when the vertical acceleration acting on the vehicle body due to the vibration input from the front wheels due to the uneven road surface exceeds a predetermined value, the uneven road surface causes the vertical acceleration of the predetermined value or more to be applied based on the output of the vehicle speed detection means. The delay time for the rear wheels to reach the road surface is calculated, and after the delay time from when the front wheels pass the road surface unevenness, the phase of the signal based on the vertical acceleration of the vehicle body when the front wheels pass the road surface unevenness is inverted. Since the control means is configured to operate the actuator in accordance with the obtained control signal, even if a relatively large vibration occurs in the vehicle body when the front wheels pass the uneven road surface, when the rear wheels pass the uneven road surface, the front wheels will not be affected by the unevenness. Control is performed in the direction of suppressing the occurrence of vehicle body vertical acceleration by referring to the vehicle body vertical acceleration when passing, so when the rear wheels pass through bumps, the vibration input can be reduced compared to when the front wheels pass bumps, making it easier for the occupants. You can get a good ride.

(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 to the downstream side of the accumulator 11,
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.
A return oil passage 6 communicating with the resurfacing tank 3 is also connected thereto.

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 accumulator 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 between the vehicle and the vehicle, and detects the internal pressure of the hydraulic chamber 15; a throttle sensor 31 detects the opening of the engine throttle valve; and a throttle sensor 31 detects the operating state of the brake pedal. 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 input 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, such as control to suppress 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, the preview control section 41 will be described. The control operation of the switching valve 22 performed by the preview control section 41 is represented by the control flowchart shown in FIG.

To explain the flowchart shown in Figure 3,
First, in step A1, 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 A6, 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 V 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 88.

Then, in step A8, 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 accumulator 20 are communicated via the switching valve 22. After the suspension characteristics have been set to soft and the predetermined time t has elapsed, the switching valve 22 returns to the OFF state, after which the process returns and the processing from step S1 onwards 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 input, and in particular, significantly reducing 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.
At the same time, the memory S max, G max and the flag are cleared, and in the following step S2, the detection outputs of various sensors necessary for control are read.

After step S2, the process proceeds to step S3, where the vehicle speed V detected by the vehicle speed sensor 24 is 30 to 120 km/h.
It is determined whether or not the steering angle θ is within a predetermined range of h, and if it is within the predetermined range, the process advances to step S4 to check whether the steering angle θ detected by the steering angle sensor 25 is 10° or less, that is, when the vehicle is running substantially straight. It is determined whether or not there is. 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 or not it is a time of sudden start and acceleration, and if it is not a time of sudden start and sudden acceleration, the process advances to step S6. Then, in step S6, the brake switch 3
2 is off, that is, whether or not braking is in progress.If braking is not in progress, in other words, if the vehicle speed is within a predetermined range, the vehicle is traveling approximately straight, and it is not in the process of sudden start, sudden acceleration, or braking, the The process advances to step S7.

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 described above 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 vertical G of the vehicle body detected by the vertical G sensor 28 on the side is stored in a memory, and these are stored and held for a certain period of time. Therefore, the detection information of the stroke S and the vertical G of the front wheel from a certain period of time ago is stored in the memory, and this certain period of time is set to be a sufficient time to carry out the control described later.

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 equal to or greater than mm.

If the absolute value of the stroke S of the front wheel is 5 mm or more, the process advances to step SIO 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 vertical G of the vehicle body detected by the vertical G sensor 28 on the front wheel side is determined. It is determined whether the value is 0.15g or more. If the absolute value of the vertical G of the vehicle body on the front wheel side is 0.15 g or more, the process advances to step S13 and timer 2 is turned on. In step S14 following step S13, timer 4
It is determined whether the timer 4 is on or not, and since it is initially in the off state, the process proceeds to step 515, where timer 4 is turned on and the process proceeds to step 316. However, if timer 4 is already on, the process proceeds from step S14 to step S16. Proceed directly to

After the above step S14 or step S15,
If it is determined in step 59.12 that the absolute value of stroke S or vertical G is less than a predetermined value, the process proceeds to step 516, where it is determined whether the flag is 1 or not. is 0, so the above step S2
Return to

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 proceeds from step Sll to step 31B, and time T2 in timer 2 is set to T.
It is determined whether or not the time has exceeded a predetermined time TC2 (front wheel side vehicle body vertical G sampling time) which is longer than the CI, and if it is within the predetermined time Te3, the process proceeds to step 81G described above, and since the flag is initially O, the above-described Return to step S2.

The above process is repeated until 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 in which a certain amount of front wheel stroke occurred but not a large vertical G force was generated on the vehicle body. It is determined that no correction control is necessary, and the process returns to step S1, where timer 1.4 is turned off.

If it is confirmed in step S19 that the timer 2 is on, the process proceeds to step S18, where it is determined whether or not the time T2 in the timer 2 exceeds the predetermined time TC2. When this happens, the process advances from step 318 to step S20.

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 vertical G on the front wheel side detected from the time TC2 hours is reached is the maximum vertical acceleration G m
Detected as ax. After that, when the process proceeds to step S22, it is determined whether the absolute value of the front wheel maximum stroke S max is 30 mm or more, and if it is 30 mm or more, the process proceeds to step S23 where the absolute value of the maximum vertical acceleration G max is 0.5 g or more. It is determined whether or not. If it is determined in step S23 that Gmax is less than 0°5g, and in step S22 described above, Smax is determined to be 30mm.
If it is determined that the flag is less than 1, it is determined that the vibration input when the front wheels pass is not so large and there is no need to start correction control for the rear wheels, and the process proceeds to step S24, where it is determined whether the flag is 1 or not. Since it is initially 0, the process returns to step S1 described above.

If it is determined in step S23 that Gmax is 0.5g or more, that is, if the front wheel maximum stroke Smax and maximum vertical acceleration Gmax both exceed predetermined values, vibration input from the road surface when the front wheels pass It is determined that it is necessary to perform large 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 the timer 3 is already turned on in step S26, it is reset. After step S26, step S
The process proceeds to step 27, where it is determined whether or not the flag is 1. Since it is initially 0, the process proceeds to step 328, where 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 the 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 manner, the timer 1.2 is off, so the process goes through step S16, and since the flag is 1, the process proceeds from step S16 to step S331. 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 the time T3 is set to be sufficiently longer than R, it is determined that the time T3 is less than or equal to the predetermined time TC3, and the step S3 described above is performed.
Return to 0.

Such processing is repeated until the time T4 in timer 4
When (the elapsed time since the vertical G of the vehicle body of a predetermined value or more is generated on the front wheel side) exceeds the delay time TR, the process advances from step 530 to step S32. Step S32
Then, the correction control amount for the rear wheels is calculated based on the vehicle body vertical G before the TR time (delay time TR) stored in the process of step S7. Specifically, as shown in Fig. 6, the stored output of the vertical G sensor on the front wheel side is once integrated to derive a signal corresponding to the vertical displacement speed on the spring, and the integrated signal is The value of the signal whose phase is inverted before the TR time is used as the 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.

Through the above control, the rear wheels are given a correction control amount having the characteristics shown in Fig. 6, but when such control is performed for a certain period of time, time T3 in timer 3 reaches a predetermined time. When TC3 (rear wheel control end time) is exceeded, the process returns from step S31 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 maximum front stroke stroke SmaX and the maximum vertical acceleration G max of the front wheels reach a predetermined value during correction control for the rear wheels. In some cases, a situation in which the
Since timer 3 is reset at 26, timer 3
The time at which the time T3 exceeds the predetermined time TC3 is substantially extended, and correction control for the rear wheels is continuously performed on a road surface with continuous road surface irregularities exceeding a certain level.

The rear wheel correction control unit 42, which performs the above-described control, is configured to detect a situation in which, 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 occurs in the front wheels, and the front wheels are sprung. If a vertical G of more than a predetermined value occurs, correction control is performed based on the vertical G of the vehicle body on the front wheel side when the front wheel passes the unevenness at the time when the rear wheel passes the unevenness. In other words, based on the vertical G generated on the spring of the front wheel when the front wheel passes over an uneven road surface, the amount of control applied to the rear wheels on the same left and right side as the front wheel is corrected in a direction that reduces the vertical G. The amount of control applied to the rear wheels can be corrected by referring to the behavior of the vehicle body when the front wheels pass, and it is possible to effectively alleviate the impulsive vibration input to the rear wheels when the rear wheels pass over the uneven road surface.

In addition, the amount of correction for the control amount for the rear wheels is derived by inverting the phase of the signal obtained by integrating the vertical G of the vehicle body on the front wheel side, making it possible to obtain stable performance that is resistant to noise. .

According to the above embodiment, the preview control unit 41 performs damping force control based on the output of the Brevigny sensor, and the rear wheel correction control R42 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 surface cannot be detected, the vibration input when the rear wheel passes through an uneven surface can be reduced 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 vertical G of the vehicle body when the front wheels pass through the unevenness of the road surface, so that the vertical G of the vehicle body is offset. It is possible to perform canceling correction and effectively improve the ride comfort, and also to obtain a stable ride comfort improvement effect because the signal obtained by integrating and inverting the phase of the vertical G signal of the vehicle body is used as the correction control amount. It produces the effect that can be achieved.

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 pressure sensor 30 may be used in combination. Furthermore, the order of phase inversion and integral processing may be reversed, or integral processing may be abolished. It goes without saying that various other modifications can be made without departing from the spirit of the invention.

(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 cancel the vertical acceleration of the vehicle body while passing the unevenness, when the rear wheels pass the unevenness, the vibration input can be reduced compared to when the front wheels pass the unevenness. This has the effect of providing an active suspension for a vehicle that can provide better ride comfort for the driver.

[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 a timing 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 28...Vertical G sensor, 29...Vehicle height sensor 42...Rear wheel correction control unit Applicant Mitsubishi Motors Corporation Figure 3 Procedural Amendment (, eh. September 3, 1990 Display of the case Patent No. 11ifi321956 of 1990 Name of the invention Person who corrects active suspension for vehicles Relationship to the case Patent applicant Zip code 108 Address 33-8 Shiba 5-chome, Minato-ku, Tokyo "30 strokes" in the "Detailed Description of the Invention" column and front face 1 of the specification subject to the amendment, page 19, line 16, page 17, line 17, and page 20, line 1 of the specification, 2. Correct "r 0.5g" on page 19, line 18, the last line of the same page, and page 20, line 7, to "r O,2g". 3. Figure 5 is corrected as shown in the attached sheet. Applicant Mitsubishi Motors Corporation

Claims (1)

[Claims] An actuator is interposed between the vehicle body and the rear wheels and is capable of increasing or decreasing the supporting force of the vehicle body relative to the rear wheels, and a vertical G sensor detects vertical acceleration acting on the vehicle body due to vibration input from the front wheels due to uneven road surfaces. means, vehicle speed detection means for detecting the traveling speed of the vehicle, and control means for controlling the operation of the actuator based on the detection output of each of the detection means, the control means detecting from the vertical G detection means. When it is detected that the vertical acceleration of the vehicle body exceeds a predetermined value, the delay time until the rear wheels reach the uneven road surface that caused a vertical acceleration of more than the predetermined value is determined based on the output of the vehicle speed detection means. The actuator is operated in accordance with a control signal obtained by calculating and inverting the phase of a signal based on the vertical acceleration after the delay time from when the front wheel passes the unevenness of the road surface. Active suspension for vehicles