JPH0361107A - Suspension control device of vehicle - Google Patents

Abstract

PURPOSE:To make roll center height variable and improve the turning characteristics of vehicles by constituting a lower arm with two members, and installing a restraint releasing means which selectively brings to a state of releasing restraint in accordance with the conditions of turning vehicle for each arm member. CONSTITUTION:The top of a knuckle 2 pivotally supporting a wheel 1 is supported to a car body 4 through a strut assembly 3 while its bottom is supported to the car body 4 through No.1 and No.2 lower arms 5, 9. A fixing member 6 fixing No.1 lower arm 5 to the car body 4 is connected to the car body through a lock cylinder 8. The inner end of No.2 lower arm 9 is positioned higher than the inner end of No.1 lower arm 5, and fixed to the car body 4. A lock cylinder 10 is installed in the middle part thereof. Control is so made to bring the lock cylinder 8 into a state of releasing restraint on detection of the vehicle in a state of turning, and bring the lock cylinder 10 into a state of releasing restraint when the state of turning is not detected.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a suspension control device for controlling the roll center height of a vehicle.

(Prior Art) Conventionally, the roll center height of a vehicle has been uniquely determined by the suspension setting.

That is, in a general suspension as shown in FIG. The point where the line segment connecting the intersection point P with the extension line of the upper arm (an extension line of the upper arm) and the ground contact center of the wheel 03 intersects the center line C'F of the vehicle body is defined as the roll center RC when the vehicle is traveling straight.

By the way, the roll center is the I
There is a midpoint between R, and when considering the vehicle body, it is also the instantaneous center point for the vertical stroke of the wheel. Here, if we focus on the vertical movement of the wheels when considering the vehicle body as a reference, when the wheels bump, the higher the height of the roll center, the greater the displacement of the wheels outward in the vehicle width direction, which increases the tread. Therefore, the higher the I call center, the more kL2
(k is the spring constant of the spring, and L is the tread).

In this case, the characteristics on the rebound side are opposite to the above, but
Since most of the roll reaction force of the vehicle is received by the outer turning wheel, the roll stiffness is determined by the above-mentioned bump characteristics that occur on the outer turning wheel.

(Problem to be solved by the invention) Therefore, in order to increase roll rigidity and improve turning performance, it is sufficient to set the roll center high, but if the roll center is set high, There is a problem that the straight running performance of the vehicle deteriorates due to the influence of tread changes.

That is, in order to improve straight running performance, it is preferable that the roll center is low, and the influence of roll center height on straight running performance and turning performance has shown a completely opposite tendency as shown in FIG.

For this reason, in the past, it was necessary to select a roll center height that could achieve both straight-line performance and turning performance to some extent, and there was a problem in that straight-line performance and turning performance could not be efficiently improved.

(Structure of the Invention) The present invention has been devised in view of the above points, and includes a wheel support member that rotatably supports a wheel, and a wheel support member that is provided between the wheel support member and the vehicle body and is disposed substantially in the vehicle width direction. The upper arm provided or the first and second arms provided together as the lower arm are provided corresponding to each of the arms such that the restraint on the wheel support member by the first and second arms can be independently released. a turning detection means for detecting that the vehicle is in a turning state, and an operation of the first and second restraint releasing means in accordance with a detection output of the turning detection means. the second arm is arranged to define a higher roll center than the first arm; When it is detected that the vehicle is in a turning state, the first restraint release means is set to a restraint release state, and when it is not detected that the vehicle is in a turning state, the second restraint release means is set to a restraint release state. This is a suspension control device for a vehicle characterized by the following.

(Function) According to the present invention, the first and second arms provided corresponding to each arm can independently release the restraint on the wheel support member by the first and second arms provided together as the upper arm or the lower arm. The operation of the second restraint release means is selectively controlled by the control means, and the control means brings the first restraint release means into the restraint release state when the vehicle is in a turning state. The roll center height of the vehicle is defined by the second arm and becomes higher, improving the turning performance of the vehicle.

On the other hand, when the turning state is not detected, the control means sets the second restraint release means to the restraint release state.
The arm loses its function as a suspension arm, and the roll center height of the vehicle is defined by the first arm and becomes lower, improving the straightness of the vehicle.

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

As shown in FIG. 1, a wheel 1 is rotatably supported by a knuckle 2, and a strut assembly 3 whose lower end is fixed to the -L portion of the knuckle 2 has an upper end supported by a vehicle body 4. There is. Note that the strut assembly 3 constitutes upper guide means. A first lower arm 5 is provided between the lower part of the knuckle 2 and the vehicle body 4 and is arranged in the vehicle width direction, and the outer end of the first lower arm 1.5 is pivotally connected to the knuckle. The inner end of the first lower arm 5 is pivotally connected to the vehicle body 4 via a pivot member 6, and this pivot member 6 is slidable in the vehicle width direction by a slide bearing 7. 4, and the pivot member 6 is connected to the vehicle body via a lock cylinder 8.

Similarly to the first lower arm 5, the second lower arm 9 is disposed between the lower part of the knuckle 2 and the vehicle body 4 in the vehicle width direction, and has its outer end pivoted to the knuckle 2. The inner end of the second lower arm 9 is located above the inner end of the first lower arm 5 and is pivotally connected to the vehicle body 4, and the second lower arm 9 extends from the inner end toward the outer end of the first lower arm. 5
It is arranged with an angle of inclination that is more inclined downward. Further, a lock cylinder IO is provided at the intermediate portion of the second lower arm 9.

The lock cylinders 8 and 1O have similar structures, and as shown in FIG. 2, a piston 12 is slidably inserted into the cylinder 11, and is connected to a member connected to the cylinder 11 and the piston 12. It is possible to restrict or allow relative displacement between the member and the member being used.

That is, oil is sealed in the cylinder 11, and two oil chambers partitioned by the piston 12 are communicated with each other by a communication passage 13, and this communication passage 13 is provided with a lock valve 14 made of a solenoid valve. There is. For this reason, the lock valve 14 can switch and control the communication and isolation of the two oil chambers, and when the two oil chambers are in the communication state, the relative relationship between the member connected to the cylinder 11 and the member connected to the piston 12 is reduced. Displacement is allowed and the corresponding lower arm loses its function as a suspension arm.

Further, when the lock valve 14 is in the closed state, relative displacement between the assembly connected to the cylinder 11 and the member connected to the piston 12 is restricted, and the corresponding lower arm functions as a suspension arm. Note that the lock cylinders 8 and 10 are the first and second lock cylinders, respectively.
This serves as a means of releasing the restraints.

Lock valve 1 provided in lock cylinders 8 and 10
4 is controlled by a controller 15. In addition, as shown in FIG. 4, the controller 1
Reference numeral 5 includes a turning detection means and controls the operation of the lock cylinders 8 and 10 in accordance with the detection output of a steering angle sensor 16 that detects the steering angle of the steering wheel.The control operation is shown in FIG. . In other words, the control shown in FIG. 4 is such that when the steering angle of the steering wheel exceeds a predetermined value, the lock cylinder 10 is placed in a locked state (the lock valve is cut off), while the lock cylinder 8 is placed in a free state (the lock valve is placed in a communication state). ), and when the steering angle of the steering wheel does not exceed a predetermined value, the lock cylinder 8 is set to the locked state (
lock cylinder 1
0 is set to a free state (the lock valve is in a communicating state). Note that the predetermined value in this case is set to a relatively small value because it determines whether or not the vehicle is in a turning state.

Next, the operation of this embodiment will be explained. The second lower arm 9 is pivotally connected to the vehicle body 4 at an inner end above the first lower arm 5, and is arranged to be inclined downwardly from the inner end to the outer end to a greater extent than the first lower arm 5. Therefore, the roll center height defined by the second lower arm 9 is set higher than the roll center height defined by the first lower arm 5.

When the steering angle of the steering wheel exceeds a predetermined value (when the vehicle is in a turning state), the controller 15 sets the lock cylinder 8 in a free state, while the lock cylinder 1
0 is in the locked state, the part of the first lower arm 5 attached to the vehicle body side becomes slidable in the vehicle width direction, the first lower arm 5 loses its function as a suspension arm, and the second lower arm 9 becomes a suspension arm. Functions as A-1. Therefore, the roll center height of the vehicle is
is defined by the lower arm 9 and becomes higher, improving the turning performance of the vehicle.

On the other hand, when the steering angle of the steering wheel does not exceed a predetermined value (when the vehicle is traveling almost straight), the lock cylinder 10
Since the lock cylinder 8 is set in a free state and the lock cylinder 8 is set in a locked state, the second lower arms 1 and 9 become telescopic and lose their function as suspension arms, and the first lower arms 1 and 5 function as suspension arms. do. Therefore, the height of the roll center of the vehicle is lower than that of the first lower arm 5.
, which improves the straight-line performance of the vehicle.

In this way, according to the above embodiment, the roll center height can be switched and controlled depending on whether the vehicle is in a straight-ahead state or a turning state, and the turning performance and straight-ahead performance of the vehicle can be independently improved. 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 upper arm of a double wishbone type suspension may be provided with a first and second arm, and various other modifications may also be made. Needless to say, it is possible to implement it.

(Effects of the Invention) Second, as specifically explained in conjunction with the embodiments, according to the present invention, the roll center height increases when the vehicle is in a turning state, and the roll center height increases when the vehicle is in a straight-ahead state. Since the center height is lowered, the turning performance and straight-line performance of the vehicle are significantly improved.

[Brief explanation of drawings]

Fig. 2 is a schematic configuration diagram showing an embodiment of the present invention, Fig. 2 is a structural diagram of the lock cylinders 8 and 10, Fig. 3 is a block diagram of the control system, and Fig. 4 shows the control operation of the controller 15. Flowchart diagram, FIG. 5 is a schematic configuration diagram showing a conventional example,
FIG. 6 is a characteristic diagram showing the influence of roll center height on turning performance and straightness.

Claims (1)

[Claims] A wheel support member that rotatably supports a wheel, first and second arms that are provided together as an upper arm or a lower arm that are provided between the wheel support member and the vehicle body and are arranged substantially in the vehicle width direction; and first and second restraint release means provided corresponding to each of the arms so as to be able to independently release the restraint on the wheel support member by the second arm, and detecting that the vehicle is in a turning state. a turning detection means, and the first and second turning detection means according to the detection output of the turning detection means.
control means for controlling the operation of the restraint releasing means of the restraint releasing means and selectively bringing both restraint releasing means into a restraint releasing state, the second arm being arranged so as to define a roll center higher than the first arm. The control means sets the first restraint release means to the restraint release state when the turning state is detected, and causes the second restraint release means to release the restraint when the turning state is not detected. A suspension control device for a vehicle, characterized in that the device is configured to