JPS62198510A - Active type suspension control device - Google Patents

Abstract

PURPOSE:To keep the motion characteristics accurate and to make this motion characteristics applicable to driver's preference, by constituting a suspension control device so that it controls the stroke desired values to be in the opposite directions to each other, at right/left mutually confronting wheels, by lateral acceleration or lengthwise acceleration. CONSTITUTION:When detected signal of a lateral acceleration detecting unit 24 is input into stroke desired value set circuits 26f, 26r for front wheels and rear wheels, these set circuits 26f, 26r amplify the signals according to gain of a gain setting unit 27, and output these signals as stroke desired values Tf, Tr at each wheel position. By this way, stroke desired values of the front right wheel and the rear right wheel increase in the negative direction or in the positive direction, and at the same time, stroke desired values of the front left wheel and the rear left wheel increase in the opposite direction to the right wheels. In this way, the stroke between the upper and lower portions of a spring, at each wheel position, can be made coincident with the stroke desired value to which a bend of a tire is added, and consequently, the motion characteristics can be kept accurate.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an active suspension control device that actively suppresses rocking of a vehicle body by controlling a suspension.

[Conventional technology]

As a conventional active suspension control device, there is one disclosed in Japanese Patent Application Laid-open No. 7943.8/1983.

As shown in FIG. 3, the cylinder tube 1a of an actuator 1, which is a double-acting hydraulic cylinder, is attached to a wheel side member, and the piston rod 1b of this actuator 1 is attached to a vehicle body side member 2. installed,
In addition, a coil spring 3 is installed between the cylinder tube 1a and the vehicle body side member 2, and this coil spring 3
supports the vehicle body side member 2, and connects side pressure chambers A and B of the actuator l to a hydraulic power source 5 via a center bypass type electromagnetic directional switching valve 4. An orifice 6 is connected between the side pressure chambers A and B of the actuator 1.

Therefore, the relative displacement (stroke) between the unsprung part and the unsprung part
A stroke sensor 9 serving as a relative displacement detection means detects the stroke, and the electromagnetic directional switching valve 4 is controlled by the control device 10 so that the stroke fluctuation becomes small.

The control method in this case is as schematically shown in FIG.
When steering the steering wheel, depressing the accelerator pedal, depressing the brake pedal, etc., which cause a change in the attitude of the vehicle (block ■), lateral acceleration or longitudinal acceleration occurs in the vehicle body in response (block ■). This causes posture changes such as rolling and pitching of the vehicle body (block ■). When a posture change occurs in the vehicle body in this way, this is detected by the stroke sensor 9 (block ■), and the deviation between the detected stroke value and a preset target stroke (usually set to zero) is calculated. Then, the electromagnetic directional control valve 4 is switched and controlled in accordance with the deviation to control the actuator 1 (block (2)), thereby controlling the change in the attitude of the vehicle body to be small.

[Problem that the invention seeks to solve]

However, in the conventional active suspension control device described above, in any case, the relative displacement between the unsprung mass and the sprung mass at each wheel position is controlled so that the deviation from the fixed target stroke becomes zero. Because of this configuration, there was a problem in that it was difficult to prevent rolls due to tire deflection.

In other words, even if the relative displacement between the unsprung part and the unsprung part is controlled to be zero when turning, the deflection of the tires will cause a roll angle α7 expressed by the following equation (1) in the vehicle. , it was impossible to prevent this.

αt=M-V-He/Krr...
(1) Here, M is the sprung mass, y is the lateral acceleration, Hc is the ground clearance of the center of gravity, and KTr is the roll stiffness due to tire deflection.

Furthermore, since the target stroke is always a constant value, there is also the problem that it is difficult to change the actual roll characteristics from the driver's seat according to the driver's preference.

Therefore, the present invention has been made by focusing on the problems of the conventional example, and changes the stroke target value, which is the target of ff+lJ of the actuator, to the zero roll or reverse roll direction according to the detected lateral acceleration value. It is possible to completely suppress changes in the attitude of the vehicle body, and to obtain roll characteristics or pitch characteristics according to the driver's preference, by changing the direction to zero pitch or reverse pitch according to the detected longitudinal acceleration value. Therefore, it is an object of the present invention to provide an active suspension control device that can solve the above problems.

[Means for solving problems]

In order to achieve the above object, the present invention detects the deviation between the actual stroke and the target stroke by detecting the relative displacement between the sprung mass and the sprung mass of the vehicle, and adjusts each of the vehicle to match the target stroke. In an active suspension control device equipped with a vehicle height adjustment mechanism that adjusts the vehicle height at a wheel position, a relative displacement detection means for detecting a sprung mass and a relative displacement between the sprung mass at each wheel position of the vehicle; an acceleration detector that detects the lateral acceleration or longitudinal acceleration generated in the vehicle; and a stroke target value that outputs stroke target values having different signs for the left and right wheels or opposing wheels of the front and rear wheels to the vehicle height adjustment mechanism based on the detected value of the acceleration detector. - a target value setting circuit.

[Effect]

This invention detects the deviation between the actual stroke, which is obtained by detecting the relative displacement between the sprung mass and the sprung mass of the vehicle, and the target stroke, and adjusts the vehicle height at each wheel position of the vehicle to match the target stroke. In an active suspension control device equipped with a vehicle height adjustment mechanism, a lateral acceleration detector detects the lateral acceleration that occurs when the vehicle turns, and the detection signal is corrected by a stroke target value setting circuit, and +
.

- is output as a stroke target value with a different sign, and the vehicle height adjustment mechanism is controlled according to the deviation between this and the actual stroke detection value between unsprung and unsprung parts, and the change in vehicle body posture is adjusted to zero roll or reverse. By changing the direction of roll, it is possible not only to completely suppress roll caused by tire deflection, but also to obtain roll characteristics according to the driver's preference. Similarly, when braking or starting, it is possible not only to completely suppress pitching caused by tire deflection, but also to obtain pinch characteristics that suit the driver's preference.

〔Example〕

Embodiments of the present invention will be described below based on the drawings.

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG. 2 is a block diagram showing an example of a control device applicable to the present invention.

In FIG. 1, 11FL, 11FR, 11RL,
111? I? are the vehicle body side member 12 and each wheel 1, respectively.
3FL.

], 3FR,l 3RL, 131? It is an active suspension device interposed between wheel side members 14 that individually support the wheels R, and supplies working fluid to a hydraulic cylinder 15, a coil spring 16, a stroke sensor 17, and a hydraulic cylinder 15 as actuators, respectively. It is equipped with a vehicle height adjustment mechanism composed of a directional switching valve 18 to be controlled.

Here, the hydraulic cylinder 15 has its cylinder tube 1
5a is attached to the vehicle body side member 12, and the piston rod 1
5b is attached to the wheel side member 14. Further, the coil spring 16 is connected to the vehicle body side member 12 and the wheel side member 14.
It is installed between the hydraulic cylinder 15 and supports the vehicle body load, and under normal conditions, the amount of displacement from the neutral point is adjusted by adjusting the stroke of the hydraulic cylinder 15 based on the movement of the wheel load during turning, even during vibration. Ru. Furthermore, the stroke sensor 17 is configured with a potentiometer, for example, and detects the stroke between the vehicle body side member 12 and the wheel side member 14 from the neutral position, and accordingly generates a positive detection signal when the stroke is displaced upward from the neutral position. , respectively, outputs a negative detection signal when displaced downward. Furthermore, each input boat of the directional control valve 18 is connected to a hydraulic unit 20 having a built-in hydraulic pump, and the return port is connected to a tank 21. The high pressure accumulators 22f and 22r and the low pressure accumulator 23f are installed in the high pressure side piping and the low pressure side piping, respectively.

23r is connected to improve the responsiveness of the directional control valve 18.

A lateral acceleration detector 24 is disposed on the vehicle body, and outputs a detection signal y having a voltage corresponding to the lateral acceleration generated on the vehicle body. The sign of this signal y is set to be positive when the vehicle turns to the right, and negative when the vehicle turns to the left.

Each of the suspension devices 11FL and IIFR
, 11RL, and 11RR, the detection signals of the stroke sensor 17 and the detection signal of the lateral acceleration detector 24 are transmitted to the control device 2.
5, and this controller 25 controls the lateral acceleration detector 24.
The detection signal y of the stroke sensor 17 and the detection signal DS of the stroke sensor 17
Based on this, a control signal for controlling the direction switching valve 18 of each suspension device 11FL to IIRR is output.

In one example of the control device 25, as shown in the block diagram of FIG. 2, the lateral acceleration detection signal y from the lateral acceleration detector 24 is supplied to stroke target value setting circuits 26f and 26r.

An example of these stroke target value setting circuits 26f and 26r includes front wheel side amplifiers 28f and 26r, to which the detection signal y of the lateral acceleration detector 24 is supplied and whose gain can be adjusted by a gain setting device 27 disposed near the driver's seat. The amplified outputs of the rear wheel side amplifier 28r and the front wheel side amplifier 28f are the front wheel suspension devices 11FL and 11FI, respectively? The comparison unit 29F is supplied as the target stroke value Tf for controlling the
A comparison unit 2 in which the amplified outputs of L, 29FR and the rear wheel side amplifier 28r are supplied as target stroke values Tr for controlling the rear wheel suspension devices 11RL and 11RR, respectively.
91? L.

29RR. Here, the comparison section 29FI.

291? L and comparison units 29FR and 29RR compare the target stroke values Tf and Tr with the stroke detection signal DS of the stroke sensor 17, respectively, with opposite signs.

Based on these, the deviation signals εFL to εIIR output from the comparators 29FL to 29RR are determined by the directional control valve 1.
A controller 30FL outputs a control signal to control 8.
~30RR is supplied.

Here, the wheel loads of the front and rear wheels of the vehicle and the hydraulic cylinders 15. of the suspension devices 11FL to IIRR are considered. Assuming that the characteristics of the hydraulic system loop gain, coil spring 16, etc. are equal, if the gain constant Kf of the front wheel amplifier 28f is controlled to be equal to or less than the gain constant Kr of the rear wheel amplifier 28r using the gain setter 27, the steering characteristics of the vehicle become neutral. Be steered or oversteered. Conversely, when the gain constant Kf of the front wheel amplifier 28f is controlled to be larger than the gain constant Kr of the rear wheel amplifier 28r by the gain setter 27, the steering characteristics of the vehicle become understeer.

In this way, the front wheel side amplifier 28f and the rear wheel side amplifier 28
The reason why the steering characteristics can be changed by changing the gain constant Kf and KrO value at r is as described below.

In other words, depending on the magnitude of the gain constants Kf and Kr, when the vehicle turns, the reverse roll moment for countering centrifugal force can be made different between the front wheels and the rear wheels. This corresponds to different rates. Therefore, if Kf > Kr is selected, the amount of left and right wheel load transfer on the front wheels increases during a turn, and the left and right total cornering power of the tire decreases compared to that on the rear wheels, which improves stability. The factor Ks increases and the steering characteristics of the vehicle become understeer characteristics. Similarly, if Kf <Kr is selected,
Contrary to the above, the amount of left and right wheel load transfer on the rear wheel side increases,
The left and right total cornering power of the tires is reduced compared to that of the front wheels, and as a result, the stability factor Ks is reduced and the steering characteristics of the vehicle become oversteer characteristics.Furthermore, when Kf = Kr is selected, neutral steering It can be a characteristic.

Next, the operation of the above embodiment will be explained. Assuming that all the vehicles are traveling straight at a constant speed on a flat road with no unevenness, the lateral acceleration detected by the lateral acceleration detector 24 y is It is zero. Therefore, the stroke target value setting circuits 26f, 26r
The Z-stroke target value Tf and the value of Tr output from the motor become zero.

On the other hand, since the actual stroke detection values DS, . It becomes approximately zero.

Therefore, the directional control valve 18 is held at the neutral position, the supply of pressure fluid to the hydraulic cylinder 21 is cut off, and the control is performed to generate a relatively high damping force.

If you turn the steering wheel (not shown) to the right (or left) from this state to cause the vehicle to turn to the right (or to the left), lateral acceleration will occur in the vehicle toward the left or right. become. For this reason, the lateral acceleration detector 24
A positive number (or negative number) detection signal y corresponding to the lateral acceleration is output from.

Therefore, the stroke target value setting circuit 26f for the front and rear wheels
, 26r is a positive (or negative) lateral acceleration detection value y,
This is amplified based on the gain of the gain setter 27, which is set by the driver in advance in anticipation of roll due to tire deflection, and these are set as stroke target values Tf and T at each wheel position.
Output each as r. At this time, the roll angle α is a negative number (
or a positive number), the stroke target values of the front right wheel and rear right axle increase in the negative direction (or positive direction), and the stroke target values of the front left wheel and rear left wheel increase in the positive direction (or negative direction). will increase.

On the other hand, when lateral acceleration occurs in the vehicle to the left (or right), a roll occurs in which the vehicle body tilts downward to the left (or downward to the right), and the actual strokes of the left wheel DSFL, DSR*
increases in the negative direction (or in the positive direction), and the actual strokes DS and DSRL of the right wheel increase in the positive direction (or in the negative direction), which are detected by the stroke sensor 17.

Therefore, the deviation signal εF11+εRR between the stroke target value and the actual stroke at the right wheel position increases in the positive direction (or negative direction), and conversely, the deviation signal between the stroke target value and the actual stroke at the left wheel position increases. ε, ε,
increases in the negative direction (or positive direction), and these are supplied to the directional control valves 18 at each wheel position via the controllers 30FL to 30RR, so that the hydraulic cylinder 15 at the right wheel increases the actual stroke. The hydraulic cylinder 15 in the left wheel will act to increase the actual stroke in the positive direction (or negative direction).

As a result, the stroke between the unsprung part and the unsprung part of each wheel position is controlled to match the stroke target value that takes into account the deflection of the tire, so that the vehicle body can It is maintained in a state where no roll occurs at all, and therefore a comfortable steering feeling and riding comfort without any roll feeling can be obtained.

Furthermore, if the gains of the front wheel amplifier 28f and the rear wheel amplifier 28r are both set considerably large by the gain setter 27 in the stroke target value setting circuits 26f and 26r according to the driver's preference, the vehicle will Reverse roll characteristics, that is, when turning to the right, the vehicle body rolls downward to the right, and when turning to the left, the vehicle body is set to roll downward to the left, ensuring a more comfortable steering feel and riding comfort. be able to.

Furthermore, with the gain setting device 27, the front wheel side amplifier 28f
and the gain constant Kf of the rear wheel side amplifier 28r.

By appropriately setting Kr, desired steering characteristics can be obtained as described above. That is, if the driver desires stable driving, the understeer characteristic is obtained by setting Kf>Kr. On the other hand, if it is desired to run on a curve while sliding the tail, set Kf≦Kr to obtain neutral steer or oversteer characteristics.

In summary, in this embodiment, the stroke target value setting circuits 26f and 26r correct the lateral acceleration detection signal y by arbitrarily changing its amplification gain, taking into account changes in the posture of the vehicle body due to tire deflection. It is possible to perform posture change suppression control, and also to obtain a comfortable steering feeling by setting steering characteristics according to the driver's preference.

In addition, in the above embodiment, a case was explained in which a stroke sensor consisting of a potentiometer was applied as a relative displacement detection means for detecting relative displacement between an unsprung part and an unsprung part, but the invention is not limited to this. Of course, any relative displacement detection means such as a transformer can be applied.

Further, in the above embodiment, an active suspension was described for controlling the roll characteristics during turning, but it is also possible to control the pitching characteristics during braking and starting in the same way. Specifically, the target value for the front wheels during braking should be set in a positive direction (vehicle height higher than when in neutral), and the target value for the rear wheels should be set in a negative direction (vehicle height lower than when in neutral). .

Furthermore, it goes without saying that it is better to set it in the opposite direction when starting.

C Effects of the Invention] As explained above, according to the present invention, the stroke target value setting circuit strokes values with different signs for the left and right wheels or the opposite wheels of the front and rear wheels based on the detected value of the lateral acceleration or longitudinal acceleration of the vehicle. The stroke target value is output as a target value, and the actuator at each wheel position is controlled according to the deviation between this stroke target value and the actual stroke detection value.
It is possible to accurately control motion characteristics such as roll, taking into account the amount of tire deflection. Further, by making the amplification gain variable during control, it is possible to change the dynamic characteristics of the vehicle according to the driver's preference.

[Brief explanation of drawings]

FIG. 1 is a schematic block diagram showing an embodiment of the present invention, FIG. 2 is a block diagram showing an example of a control device applicable to the present invention, FIG. 3 is a block diagram of a conventional device, and FIG. 4 is an explanatory diagram for explaining the operation. In the figure, llFF to IIRR are suspension devices, 15
17 is a hydraulic cylinder, 17 is a stroke sensor, 18 is a directional control valve, 24 is a lateral acceleration detector, 25 is a control device, 26
f and 26r are stroke target value setting circuits, 27 is a gain setter, 28f is a front wheel side amplifier, 28r is a rear wheel side amplifier, 29FF to 29RR are comparison units, and 3OFF to 30RR are controllers.

Claims (3)

[Claims] (1) A vehicle that detects the deviation between the actual stroke, which is the relative displacement between the sprung and unsprung parts of the vehicle, and the target stroke, and adjusts the vehicle height at each wheel position of the vehicle to match the target stroke. An active suspension control device equipped with a high adjustment mechanism includes relative displacement detection means for detecting relative displacement between sprung and unsprung parts at each wheel position of the vehicle, and detects lateral acceleration or longitudinal acceleration occurring in the vehicle. The vehicle is equipped with an acceleration detector and a stroke target value setting circuit that outputs stroke target values having different signs for left and right wheels or front and rear opposing wheels to the vehicle height adjustment mechanism based on the detected value of the acceleration detector. An active suspension control device featuring: (2) The active suspension control device according to claim 1, wherein the stroke target value setting circuit is constituted by an amplifier capable of changing the amplification gain of the detection signal of the acceleration detector. (3) The stroke target value setting circuit is configured to be able to change the amplification gain of the lateral acceleration detection signal of the acceleration detector independently between the front wheel side and the rear wheel side. The active suspension control device described in Section 1.