JPH0450016A - Active suspension device for vehicle - Google Patents

Abstract

PURPOSE:To improve ease of vehicle driving by controlling the hydraulic pressure of a hydraulic supporting means according to a total amount where predicted amount of load movement in the horizontal direction of a vehicle body is added to the load movement in the horizontal direction of the vehicle body obtained from lateral acceleration working upon a vehicle body for effective prevention of the initial rolling of the vehicle body. CONSTITUTION:A control valve 17 of a suspension unit 12 is provided between an oil passage 16 communicating with the hydraulic chamber 15 of a hydraulic actuator 14 and a feed oil passage 4 and a discharge oil passage 6. At a by-path passage 166 connected between the oil passage 16 and an accumulator 20, a switching valve 22 is disposed. Besides, the control valve 17 and the switching valve 22 are generated by a controller 30 according to respective detected signals from a steering wheel angle sensor 33, a vehicle speed sensor 34 and so forth. When prescribed turning conditions have been satisfied from the steering conditions of a steering wheel and vehicle speed, the predicted amount of load movement predicted at the time of turning start is added to the load movement to control hydraulic feed and discharge.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an active suspension system for a vehicle that controls the attitude of a vehicle body, that is, the roll of a vehicle body when turning.

(Prior Art) This type of active suspension device includes a hydraulic actuator including a hydraulic cylinder between the vehicle body and each wheel, and supports the vehicle body via these hydraulic actuators, that is, by hydraulic pressure. That's what I do. Therefore, if the vehicle body is supported hydraulically in this way, the roll generated in the vehicle body can be reduced by increasing the hydraulic pressure of the hydraulic actuator on the outer wheel side according to the magnitude of lateral acceleration acting on the vehicle body when turning. This makes it possible to maintain a constant attitude of the vehicle body even when turning.

(Problem to be Solved by the Invention) By the way, the above-mentioned roll control of the vehicle body is performed based on the lateral acceleration acting on the vehicle body when turning, so when implementing roll control, first, the lateral acceleration of the vehicle body is However, the lateral acceleration sensor can only detect the lateral acceleration after the vehicle body starts turning and after the lateral acceleration actually begins to act on the vehicle body. .

In addition, the rise in lateral acceleration detected by a lateral acceleration sensor is also affected by the installation location of the lateral acceleration sensor itself relative to the vehicle body. For example, if the lateral acceleration sensor is installed at the rear of the vehicle body, it is The rise in lateral acceleration will be slower than when installed at

Therefore, even if the hydraulic pressure of the hydraulic actuator is controlled to maintain a constant posture of the vehicle based on the magnitude of the lateral acceleration obtained from the lateral acceleration sensor during a turn, there may be a delay in the operation of the hydraulic actuator. As a result, the vehicle body rolls once, resulting in what is called an initial roll of the vehicle body. The sharper the vehicle turns, the greater this initial roll of the vehicle body becomes, impairing its handling stability.

This invention was made based on the above-mentioned circumstances, and
The purpose is to provide an active suspension device for a vehicle that can suppress the initial roll of the vehicle body during turning and improve steering stability.

(Means for Solving the Problems) In order to achieve the above-mentioned object, the present invention provides hydraulic support means that are interposed between the vehicle body and each wheel to support the vehicle body, and detect the lateral acceleration of the vehicle body. A lateral acceleration detection means, a load movement detection means for detecting the amount of load movement on the left and right sides of the vehicle body from the magnitude of the lateral acceleration obtained by the lateral acceleration detection means, and supply and discharge of hydraulic pressure to the hydraulic support means based on the amount of load movement. In an active suspension system for a vehicle, the vehicle active suspension device includes a hydraulic control means for canceling the amount of load movement and maintaining the vehicle body in a constant posture by controlling the vehicle, and a steering wheel steering detection means for detecting the steering state of the steering wheel of the vehicle. , further comprising a vehicle speed detection means for detecting the running speed of the vehicle, so that when a predetermined turning condition is satisfied based on the steering condition of the steering wheel and the vehicle speed, the turning is started at the above-mentioned load movement amount by the hydraulic control means. The supply and discharge of hydraulic pressure to and from the hydraulic support means is controlled by adding a predicted amount of load movement that is predicted at a given time.

(Function) According to the above-mentioned active suspension system, when it is determined that the vehicle is about to turn based on the steering condition of the steering wheel and the vehicle speed, the predicted amount of load movement to the left and right of the vehicle body is calculated from the lateral acceleration. In addition to the amount of load movement -1 Since the supply and discharge of hydraulic pressure to the hydraulic support means is controlled based on this total amount, when the vehicle actually turns, the hydraulic control of the hydraulic support means has already been completed. You can leave it there.

(Example) FIG. 1 shows the configuration of a hydraulic active suspension system for an automobile. This figure shows a suspension unit 12 as a hydraulic support means provided for each wheel, that is, front left and right wheels and rear left and right wheels, and a suspension spring 13 of this suspension unit 12 and a single-acting hydraulic cylinder. Hydraulic actuator I consisting of
4 is interposed between the vehicle body 7 and the wheels 8. Note that FIG. 1 representatively shows a suspension unit combined with one wheel.

The control valve 17 of the suspension unit 12 is inserted between an oil passage 16 communicating with the hydraulic chamber 15 of the hydraulic actuator 14, and a supply oil passage 14 and a discharge oil passage 6, which will be described later. One end of a branch passage 16a is connected to the middle of the oil passage I6, and an accumulator 20 is connected to the other end of the branch passage 16a. Gas is sealed in the accumulator 20, and due to the compressibility of the gas, a so-called gas spring action is exerted. A first throttle 19 is disposed in the middle of the branch path 16a, and this first throttle 19
regulates the amount of hydraulic oil flowing between the accumulator 20 and the hydraulic chamber 15 of the hydraulic actuator 14, thereby achieving a desired vibration damping effect.

A first throttle 1 is provided between the oil passage 16 and the accumulator 20.
A bypass path 16b that bypasses 9 is connected,
A second throttle 21 and a switching valve 22 are arranged in this bypass passage 16b.

The second diaphragm 21 has a smaller orifice diameter than the first diaphragm I9. The switching valve 22 is in a closed state (the state shown in the figure) when the switching valve 22 is not energized, and when the switching valve 22 is switched to the open state, the hydraulic oil is transferred to the switching valve 2 in the open state.
2 and the second throttle 21 can flow between the accumulator 20 and the hydraulic chamber 15, thereby weakening the vibration damping effect. That is, by opening and closing the switching valve 22, the spring rigidity of the suspension unit 12 changes in two stages.

The other end of the supply oil passage 4 mentioned above is connected to the discharge side of the oil pump 1, and the suction side of the oil pump 1 communicates with the inside of the reserve tank 3 via the oil passage 2. Therefore, when the oil pump 1 is driven, the reserve tank 3
The hydraulic oil stored therein is discharged to the supply oil path 4 side. In the supply oil passage 4, an oil filter 9, a check valve 10, and an accumulator 11 for maintaining line pressure are arranged in order from the oil pump l side. The check valve 10 allows only the flow of hydraulic oil from the oil pump 1 side toward the suspension unit 12 side, and allows high-pressure hydraulic oil to be stored in the accumulator I1.

The control valve 17 is of a type that changes its valve opening in proportion to the supplied current value, and depending on this valve opening, the control valve 17 changes the valve opening between the supply oil passage 4 side and the discharge oil passage 6 side. In other words, the supply and discharge of the oil amount to and from the hydraulic actuator 14 can be controlled. And control valve 17
The structure is such that the larger the current value supplied to the hydraulic actuator 14, the greater the hydraulic pressure within the hydraulic actuator 14, that is, the supporting force generated thereby. The hydraulic oil discharged from the control valve 17 to the discharge oil path 6 side is returned to the reservoir tank 3 as described above.

The control valve 17 and the switching valve 22 are electrically connected to the output side of a controller 30 constituting a hydraulic control means, and their operation is controlled by a drive signal from the controller 30. Therefore, controller 3
Various sensors are connected to the input side of 0, respectively.
These sensors include a lateral acceleration detection means that is attached to the vehicle body 7 and detects the lateral acceleration acting on the vehicle body 7, that is, a lateral G sensor 31, and a lateral G sensor 31 that is attached to each wheel and detects the stroke amount of the wheel. a height sensor 32, a steering wheel steering detection means for detecting the steering wheel angle of a steering wheel (not shown) of the automobile, that is, a steering wheel angle sensor 33;
There is a vehicle speed sensor 34 as a vehicle speed detection means for detecting the traveling speed of the automobile, that is, the vehicle speed.

Therefore, the aforementioned control valve 17 and switching valve 22 are
The operation is controlled by the controller 30 based on the detection signal of each sensor.

During normal driving, the switching valve 22 is closed, and slight vibrations input to the vehicle body from the road surface are suppressed because the hydraulic chamber 15 of the hydraulic actuator 14 communicates with the accumulator 20 via the first throttle 19. , absorbed and attenuated.

Next, the operation of the suspension unit 12 controlled by the controller 30, that is, the roll control of the vehicle body 7, will be explained with reference to the block diagram of FIG.

First, when the car turns, the controller 30
When a detection signal is supplied from the lateral G sensor 31 to A moving amount ΔW is calculated.

ΔW=K −cy Here, K is the hydraulic actuator 14 on the left and right wheels so as to cancel the load movement on the left and right sides of the car body caused by the lateral acceleration of the car body 7 when the car turns, that is, the moment force.
This is a control gain for controlling the hydraulic pressure within the vehicle based on the lateral acceleration, and this control gain can be calculated using the following equation.

K=MH/L In the above equation, as is clear from FIG. 3, M represents the mass of the vehicle body 7, H represents the height of the center of gravity of the vehicle body 70, and L represents the tread. Incidentally, FIG. 3 shows the load movement amount ΔW when the automobile turns left.

When the load movement amount ΔW is calculated as described above,
This load movement amount ΔW is multiplied by the front wheel control ratio α in the arithmetic circuit 42, and as a result, the front wheel side load movement amount ΔW
F is calculated. On the other hand, the calculation circuit 42 multiplies the load movement amount ΔW by the rear wheel control ratio (1-α) to calculate the rear wheel side load movement amount ΔWR.

Here, the front wheel control ratio α, that is, the front-rear distribution ratio is used to control understeer and oversteer of the automobile, and α takes a value determined by experiment in the range of 0 to α<l.

When the front wheel side load movement amount ΔWF and the rear wheel side load movement amount ΔWR are calculated, based on these load movement amounts, the drive control amount of the control valve 17 that is paired with each hydraulic actuator 14, that is, its current value is calculated. The hydraulic pressure of each hydraulic actuator 14 is thereby controlled. To explain this point in more detail, if the car is currently turning to the left, the hydraulic actuator 1 for the right front wheel
Regarding No. 4, the oil pressure is controlled based on the front wheel side load movement amount ΔWF, that is, the FR control amount. However, regarding the left front wheel hydraulic actuator 14, the sign of the front wheel side load movement amount ΔWF is reversed. The oil pressure is controlled based on the FL control amount obtained. Therefore, in FIG. 2, the FL control amount is calculated by the calculation circuit 44 by multiplying the front wheel side load movement amount ΔWF by -1. Therefore, in this case, the hydraulic pressure of the hydraulic actuator 14 for the right front wheel is increased by a pressure corresponding to the front wheel side load movement amount ΔWF, whereas the oil pressure of the left front wheel hydraulic actuator 14 is increased by the pressure corresponding to the front wheel side load movement amount ΔWF. The pressure will be reduced by the pressure equivalent to WF.

On the other hand, on the rear wheel side, similarly to the front wheel side, the hydraulic pressure of the right rear wheel hydraulic actuator 14 is controlled based on the rear wheel side load movement amount ΔWR, that is, the RR control amount. As for the left rear wheel hydraulic actuator 14, its hydraulic pressure is controlled by the calculation circuit 45 based on the RL control amount obtained by inverting the sign of the rear wheel side load movement amount ΔWR. Therefore, as in the case of the front wheels, the hydraulic pressure of the hydraulic actuator 14 of the right rear wheel is increased by a pressure corresponding to the rear wheel side load movement amount ΔWR, and in contrast, the hydraulic pressure of the hydraulic actuator I4 of the left rear wheel is increased by a pressure corresponding to the rear wheel side load movement amount ΔWR. is reduced by a pressure corresponding to the rear wheel side load movement amount ΔWR.

As mentioned above, when the car is turning left, the hydraulic pressure in the hydraulic actuator 14 of the front and rear right wheels is increased depending on the magnitude of the lateral acceleration GY acting on the car body 7, and conversely, the hydraulic pressure in the front and rear right wheel hydraulic actuators 14 is increased. The hydraulic pressure in the left wheel hydraulic actuator 14 is reduced, thereby canceling out the load movement in the left-right direction of the vehicle body 7 and preventing the vehicle body 7 from rolling.

In addition, in Figure 2, the additional point is 46. 47. 48. 49 is supplied with other control amounts from A, B, C, and D, and examples of the other control amounts include, for example, the control amount executed based on the detection signal from the vehicle height sensor 32 There are control variables for adjusting vehicle height, etc.

In the roll control of the vehicle body 7 described above, the hydraulic pressure of each hydraulic actuator 14 is controlled based on the magnitude of the lateral acceleration GV from the lateral G sensor 31. However, in the case of this embodiment, the lateral Not only acceleration GY,
Roll control of the vehicle body 7 is also performed based on detection signals from the steering wheel angle sensor 33 and the vehicle speed sensor 34.

That is, when the detection signal from the steering wheel angle sensor 33 is supplied to the controller 30, within the controller 30, first, the steering angle θH is determined from the detection signal, and at the same time, the steering angular velocity δH is calculated. This steering angular velocity δH can be calculated by differentiating the steering angle θH.

The steering angle θH and the steering angular velocity δH are then supplied to a turning judgment circuit 50, as shown in FIG. 2, and the turning judgment circuit 50 judges whether or not the automobile is about to turn. That is, the steering angle θH is steered beyond the range of ±θl (for example, θ1-5°), and the steering angular velocity δH is also within the range of ±δl (for example, δI = 50
deg/sec), the turning judgment circuit 50 outputs a turning signal that predicts the turning of the automobile.

This turning signal is then input to the vehicle speed determination circuit 51,
The vehicle speed determination circuit 51 determines whether or not to output a turning signal based on the vehicle speed V obtained from the vehicle speed sensor 34.

In this case, the vehicle speed determination circuit 51 determines whether the vehicle speed is V or the predetermined speed Vl.
(For example, V 1 = 50 km/h), the turning signal is output.

When a turning signal is output from the vehicle speed determination circuit 51, in this case, the switch circuit 52 is closed.
As a result, the predicted amount of load movement Δwy stored in the storage circuit 53 is supplied to the addition point 54.
At this addition point 54, the predicted amount Δwy is added to the load movement amount ΔW from the arithmetic circuit 41 described above.

Here, the predicted amount Δwy is a value obtained by predicting in advance the load movement that will occur in the vehicle body 7 when a turning signal is output via the turning judgment circuit 50 and the vehicle speed judgment circuit 51.

Therefore, when the turning signal is supplied to the switch circuit 52, the hydraulic pressure of each hydraulic actuator 14 after this is calculated by adding the predicted amount Δwy to the load movement amount ΔW from the calculation circuit 41.
It will be controlled based on the total amount added.

The roll control routine for the vehicle body 7 described above is shown in the flowchart of FIG. As is clear from this flowchart, in steps Sl and S2, first, the steering angle θH
Each steering angular velocity δH is determined, and in the next step S3, the vehicle speed V is determined. Then, step S1. , S
2. In the determination in S3, if any is negative (No), the process advances to step S4, and in this step,
The load movement amount △W is calculated, and then the next step S5
Then, the hydraulic pressure of each hydraulic actuator 14 is controlled based on the load movement amount ΔW.

However, steps Sl, S2. If all the determinations in S3 are positive (Yes), the load movement amount ΔW is calculated in step S6, and the next step $
In step 7, the predicted load movement amount ΔW is obtained by adding the predicted amount △Wy to the load movement amount △W, and in step $5,
The hydraulic pressure of each hydraulic actuator 14 is controlled based on the load movement amount ΔW in consideration of the predicted amount ΔWy.

Therefore, in the present invention, based on the steering angle θH1 of the steering wheel, the steering angular velocity δH, and the vehicle speed V, it is determined whether the vehicle is in a situation where it is about to turn, and
Now, in a situation where the car is turning left, the arithmetic circuit 41
Since the load movement amount ΔW is corrected by adding the predicted amount Δwy to the load movement amount ΔW calculated in , in this case, the load movement amount ΔW calculated by the arithmetic circuit 41 is still 0. Even if it is smaller or smaller, the oil pressure of the hydraulic actuator 14 of each wheel will be controlled substantially based on the predicted amount Δwy before the vehicle performs a left turn. . That is, in this case, before the automobile actually turns to the left, the hydraulic pressure of the hydraulic actuator 14 for the front and rear right wheels is increased, as is clear from the above explanation; is reduced in pressure, and as a result, it is possible to effectively prevent the initial roll of the vehicle during the turning transition period. After this, when the transition to a steady turning occurs, the switch circuit 52 shown in FIG. 2 will be opened, but in this case, the lateral By controlling the oil pressure of each hydraulic actuator 14 based on the acceleration Gy, that is, the actual load movement amount ΔW, roll of the vehicle body 7 is prevented.

In the above description and the block diagram shown in FIG. 2, the case where the car turns left is taken as an example, but when the car tries to turn right, the situation is opposite to the above case. That is, in this case, the hydraulic pressure of the hydraulic actuator 14 for the front and rear right wheels is reduced in consideration of the predicted amount ΔWy, and in contrast, the hydraulic pressure of the hydraulic actuator 14 for the front and rear left wheels is increased. This will prevent the initial roll during the turning transition period. Regarding this point, when the car turns to the right, the sign of the load movement amount ΔW calculated by the calculation circuit 4I in FIG. 2 becomes negative, so in this case, the predicted amount ΔW
y will also take a negative value.

This invention is not limited to the one embodiment described above, and various modifications are possible. For example, the hydraulic support means is not limited to what is shown in FIG. 1, and the specific structure can be modified in various ways. Furthermore, regarding the values used as judgment or judgment criteria in the turning judgment circuit 50 and the vehicle speed judgment circuit 51, that is, the values representing turning conditions, the values in one embodiment are shown merely as an example, and there are no restrictions on the values. It is not something that will be done.

(Effects of the Invention) As explained above, according to the active suspension device for a vehicle of the present invention, it is determined from the steering condition of the steering wheel and the vehicle speed whether or not the vehicle is about to turn. When a car is about to make a turn, the predicted amount of load movement on the left and right sides of the car body is calculated based on the total amount added to the amount of load movement on the left and right sides of the car body obtained from the lateral acceleration acting on the car body. Since the hydraulic pressure is controlled, the hydraulic pressure of each hydraulic support means can be controlled before the automobile actually turns. As a result, it is possible to effectively prevent the initial roll of the vehicle body during the turning transition period of the vehicle, and to improve the handling stability.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention; FIG. 1 is a schematic configuration diagram of an active suspension device, FIG. 2 is a block diagram explaining the operation of the controller, and FIG. 3 is a FIG. 4, which is a diagram for explaining the load movement that occurs, is a flowchart showing a vehicle body roll control routine. l...oil pump, 7...car body, 8...wheels,
14... Hydraulic actuator, 17... Control valve, 30... Controller, 31... Lateral G sensor, 3
2... Vehicle height sensor, 33... Steering wheel angle sensor, 3
4...Vehicle speed sensor. Figure 1 Applicant: Mitsubishi Motors Corporation Agent, Patent Attorney Kan Nagato Figure 4: Two left turns

Claims (1)

[Claims] A hydraulic support means is installed between the vehicle body and each wheel to support the vehicle body, a lateral acceleration detection device detects the lateral acceleration of the vehicle body, and the vehicle body is detected based on the magnitude of the lateral acceleration obtained by the lateral acceleration detection device. Hydraulic control that cancels the amount of load movement and maintains the vehicle body in a constant posture by controlling the supply and discharge of hydraulic pressure to the hydraulic support means based on the load movement detection means that detects the amount of left and right load movement, and the amount of load movement. The active suspension system for a vehicle further comprises: a steering wheel steering detecting means for detecting a steering state of a steering wheel of the vehicle; and a vehicle speed detecting means for detecting a running speed of the vehicle; When a predetermined turning condition is satisfied based on the steering condition of the steering wheel and the vehicle speed, the predicted amount of load movement expected at the start of the turn is added to the above load movement amount to supply and discharge hydraulic pressure to the hydraulic support means. An active suspension device for a vehicle characterized by controlling.