JPH0532114A - Car camber angle control device - Google Patents

Abstract

PURPOSE:To enhance the head swinging performance in the early period of cornering and also the converging performance at the time of straight advance by sensing the sideways acceleration of a car in its parts fore and aft, operating a front and a rear driving means for changing the camber angle independently, and thereby controlling the camber angles. CONSTITUTION:A suspension device 1 having a driving means to change the camber angle is installed at the front wheels 10F and rear wheels 10R of a car, and the sideways accelerations of the car in its parts fore and aft are sensed by sideways acceleration sensors 2F, 2R mounted in proximity to respective axles. The signals from these sensors 2F, 2R are fed to a controller 3, and the driving means for respective suspension devices 1 are controlled by the front wheel and rear wheel control parts 23F, 23R. This permits enhancing the head swinging performance of the car in the initial period of cornering and the converging performance at the time of straight advance.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a camber angle control device for automatically controlling the camber angles of front and rear wheels of a vehicle.

[0002]

2. Description of the Related Art For example, when a vehicle body rolls during turning of a vehicle, the wheels tilt with the vehicle body in a direction opposite to the center of turning, that is, in the vehicle width direction due to centrifugal force, or as the wheel alignment changes, the ground camber. The corners change. This change in camber angle not only causes uneven wear of the tire, but also causes the canvas last to decrease the cornering force.

In order to solve such a problem, the applicant of the present invention has previously proposed a camber angle control device described in JP-A-60-15213. This camber angle control device detects, for example, an acceleration in the vehicle width direction (hereinafter referred to as lateral acceleration) that occurs when the vehicle turns, sets a target camber angle based on the output signal, and sets the target camber angle. The camber angles of the front and rear wheels are changed to achieve this.

According to this camber angle control device, there is an advantage that the canvas last acting in the direction opposite to the cornering force can be reduced to improve the turning stability of the vehicle and, in turn, the running stability.

[0005]

On the other hand, considering the turning and convergence of the vehicle in a lane change or the like, the vehicle is required to have the ability to turn with a high response and quickly converge to a straight traveling state. This turning and convergence performance is greatly affected by the way cornering force is generated between the front and rear wheels.

However, in the conventional camber angle control device, specifically, the lateral acceleration generated in the vehicle is detected by one lateral acceleration sensor provided at a predetermined position, and the front wheel and the rear wheel are detected based on the detected value. The camber angle was controlled similarly. Therefore, different camber angle control cannot be performed for the front wheels and the rear wheels. Therefore, there is a problem that the above-described turning performance and convergence performance cannot be positively improved.

The present invention has been developed in view of the above problems, and a vehicle capable of detecting different lateral accelerations before and after the vehicle to improve the turning performance at the initial turning and the converging performance at the time of going straight. The present invention provides a camber angle control device.

[0008]

A camber angle control device for a vehicle according to the present invention is a camber angle control device for a vehicle capable of independently controlling the camber angles of front and rear wheels of the vehicle. Front and rear wheel drive means that can be changed to
Two lateral acceleration detecting means installed at a distance in the front-rear direction of the vehicle, and front wheel control for controlling the camber angle by driving the front wheel driving means based on the output signal of the lateral acceleration detecting means on the front side of the vehicle Means and a rear wheel control means for controlling the camber angle of the rear wheel drive means by driving the rear wheel drive means based on the output signal of the lateral acceleration detection means on the vehicle rear side.

[0009]

In the vehicle camber angle control device of the present invention, the front wheel control means drives the front wheel drive means on the basis of the output signal of the lateral acceleration detection means on the front side of the vehicle to control the camber angle thereof, and the rear wheel control means. The means drives the driving means for the rear wheels on the basis of the output signal of the lateral acceleration detecting means on the rear side of the vehicle to control the camber angle thereof. At times, it is possible to quickly bring the vehicle to a straight state.

[0010]

FIG. 1 shows an embodiment of a camber angle control device of the present invention, which is applied to a vehicle equipped with a double wishbone type four-wheel independent suspension mechanism. First, the structure will be described. As shown in the figure, a suspension device 1 having a drive means for changing the camber angle is attached to each of the front and rear wheels 10F, 10R of the vehicle.
Of these, the hub carrier 11 that supports the front wheels 10F is shown in FIG.
As shown in FIG. 3, each of the hub carriers 11 supporting the rear wheels 10R has a lower arm 12 rotatably connected to a lower end thereof and a side rod 13 rotatably connected to an intermediate portion thereof. A variable length upper link 14 is connected to the upper end portion thereof, and each arm 12, rod 13, and link 14 are connected to a vehicle body side (not shown) via a rubber bush or the like. Further, the lower arm 12 and the hub carrier 11 are connected by a wind-up link 15 to improve the support rigidity in the rotational direction of the wheel and to effectively move the upper connection point of the hub carrier to the inner side in the vehicle width direction. As a result, the kingpin tilt angle is increased to achieve an ideal negative scrub.

A hydraulic chamber 16 and a piston 17 as shown in FIG. 4 are incorporated in the variable length upper link 14, and the length of the upper link 14 can be changed by expanding and contracting the piston 17. When the upper link 14 is lengthened, the camber angle of the wheel changes in the positive direction, and when the upper link 14 is shortened, the camber angle changes in the negative direction. A spring 18 is installed inside the hydraulic chamber 16 by a stop pin 19, and a control valve 21 for controlling the hydraulic pressure from a hydraulic source 20 is connected to the hydraulic chamber 16 and opens and closes the control valve 21. By doing so, the piston 17 is expanded and contracted. Although this hydraulic circuit will not be described in detail here, for example, the above-mentioned Japanese Patent Laid-Open No.
The hydraulic circuit described in 0-15213 can also be used. A stroke sensor 22 for detecting the stroke length of the piston 17 is attached to the variable length upper link 14, and a detection signal from the sensor 22 is output to the controller 3 shown in FIGS. Further, the control valve 21 is opened and closed by an output signal from the controller 3.

In the camber angle control device of the present invention, as shown in FIG. 1, two lateral acceleration sensors 2F and 2R are attached with a distance in the front-rear direction of the vehicle. The lateral acceleration sensors 2F and 2R detect the lateral acceleration generated in the front of the vehicle and the lateral acceleration generated in the rear of the vehicle, and the detection signals are output to the controller 3. For these purposes, it is desirable that the lateral acceleration sensors 2F and 2R be provided near the front wheel shaft and the rear wheel shaft.

The controller 3 comprises a front wheel control section 23F and a rear wheel control section 23R, of which the front wheel control section 23F has a lateral acceleration detection signal from a front lateral acceleration sensor 2F and variable lengths of the front wheels. A stroke detection signal of the upper link 14 is input, and the control valve 21 of each front wheel is opened / closed by a signal from the front wheel control section 23F. Similarly, the lateral acceleration detection signal from the rear lateral acceleration sensor 2R and the stroke detection signal of the variable length upper link 14 of each rear wheel are input to the rear wheel control section 23R, and the signal from the front wheel control section 23R is input. Thus, the control valve 21 of each rear wheel is opened and closed. Both control units 23F,
The 23R has a built-in microcomputer (not shown), and stores, for example, a program as shown in the flowchart of FIG. 7 and a lateral acceleration-camber angle correlation (hereinafter referred to as a control map) shown in FIG. 6 in advance. ..

Next, the operation of this camber angle control device will be described. The process shown in FIG. 7 is executed as a timer interrupt process for each predetermined period ΔT (for example, 5 msec), and the detection signals from the front and rear lateral acceleration sensors 2F and 2R and the detection signals of the stroke sensors 22 for all the wheels are determined. It is always input to the controller 3. The figure shows the front wheel controller 23F.
There are mainly programs within.

First, in step S1, the front wheel control unit 23
In F, the front wheel target camber angle θ _{FP of the} front wheels 10F to be controlled is calculated based on the detection signal from the lateral acceleration sensor 2F in front of the vehicle according to the control map shown in FIG. 6, and in the rear wheel control unit 23R, the lateral acceleration behind the vehicle is calculated. The rear wheel 10R according to the control map shown in FIG. 6 based on the detection signal from the sensor 2R.
The rear wheel target camber angle θ _RP to be controlled is calculated.

Next, in step S2, the front wheel control unit 23F compares the front wheel target camber angle θ _FP with the current front wheel actual camber angle θ _FR, and the rear wheel control unit 23R compares the rear wheel target camber angle θ _{FP. RP} is compared with the actual rear wheel camber angle θ _RR at the present time. This camber angle comparison is performed based on the length of the variable length upper link 14 of each wheel, and the output value when the output value from the stroke sensor 22 is a stroke length that satisfies the target camber angles θ _FP and θ _RP. It is judged by whether or not If the target camber angles θ _FP and θ _RP and the actual camber angles θ _FR and θ _RR are judged to be equal by comparing these output values, the program ends, and it is judged that they are not equal. Moves to step S3.

In step S3, the front and rear wheels 10F, 10
The program is terminated by expanding and contracting the piston 17 of the R variable length upper link 14 to a stroke length that satisfies the target camber angles θ _FP and θ _RP . By controlling the camber angle based on the processing shown in FIG. 7, the vehicle behaves as follows.

For example, when the vehicle is turning, the momentary yaw center is behind the vehicle as shown in FIG. 8a, so that the lateral acceleration in front of the vehicle is larger than the lateral acceleration in the rear of the vehicle. The output value of the acceleration sensor 2F is larger than the output value of the lateral acceleration sensor 2R at the rear of the vehicle.
In this case, the ground camber angle θ ₀ of the outer turning wheel is tilted in the positive direction and that of the inner turning wheel is tilted in the negative direction as shown in FIG. 5, so that the front wheel as shown in FIG. By controlling the camber angle θ of the outer turning wheel in the negative direction and the camber angle θ of the inner turning wheel in the positive direction, the increase in the cornering force of the front wheels becomes larger than the increase in the cornering force of the rear wheels, and the vehicle turns. Easier to do.

On the other hand, when the vehicle converges, the instantaneous yaw center is located in front of the vehicle as shown in FIG. 8b, so that the lateral acceleration behind the vehicle is larger than the lateral acceleration in front of the vehicle. The output value of the acceleration sensor 2R is larger than the output value of the lateral acceleration sensor 2F in front of the vehicle. In this case, the cornering of the rear wheels is controlled by controlling the camber angle θ of the turning outer wheel of the rear wheels in the negative direction and the camber angle θ of the turning inner wheel in the positive direction with respect to the lateral acceleration behind the vehicle as shown in FIG. The amount of increase in the force becomes larger than the amount of increase in the cornering force of the front wheels, and the vehicle easily converges.

Therefore, when the vehicle turns, it tends to overturn and tends to turn, and when the vehicle converges, it tends to understeer and tends to converge. Although the camber angle of the wheels is controlled by the program stored in the microcomputer in this embodiment, a theoretical circuit having the same function may be used. Further, the two lateral acceleration sensors are installed in the front and the rear of the vehicle, but in the present invention, both may be installed with a distance in the front-rear direction of the vehicle, and one of them is on the front side of the vehicle, The other may be on the rear side of the vehicle.

[0021]

As described above, according to the camber angle control device of the present invention, the front wheel control means drives the front wheel drive means on the basis of the output signal of the front lateral acceleration detection means to control the camber angle thereof. However, since the rear wheel control means drives the rear wheel drive means based on the output signal of the rear lateral acceleration detection means to control the camber angle thereof, the turning performance of the vehicle at the beginning of turning and the straight traveling transition time The convergence of the vehicle can be improved.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of a camber angle control device of the present invention.

FIG. 2 is a front wheel suspension device used in the camber angle control device of FIG. 1, (a) is a perspective view of a suspension mechanism, and (b) is a front view.

3 is a rear wheel suspension device used in the camber angle control device of FIG. 1, (a) is a perspective view of a suspension mechanism, and (b) is a front view.

FIG. 4 is a vertical cross-sectional view showing a camber angle changing actuator used in the camber angle control device of FIG.

FIG. 5 is an explanatory diagram showing a roll state of the vehicle.

6 is a correlation diagram between a control camber angle in a turning state and lateral acceleration in the camber angle control device of FIG.

7 is a flowchart of a program for controlling the camber angle in the camber angle control device of FIG.

FIG. 8 is an explanatory diagram of an instantaneous yaw center and lateral acceleration when the vehicle is turning and turning is converged.

[Explanation of symbols]

 1 is a suspension device having driving means 2F and 2R are lateral acceleration sensors (lateral acceleration detecting means) 3 is a controller 23F is a front wheel control unit 23R is a rear wheel control unit

Claims (1)

Claims: 1. A camber angle control device for a vehicle capable of independently controlling camber angles of front and rear wheels of a vehicle, comprising front and rear wheel drive means capable of independently changing camber angles of front and rear wheels of the vehicle. ,
Two lateral acceleration detecting means installed at a distance in the front-rear direction of the vehicle, and front wheel control for controlling the camber angle by driving the front wheel driving means based on the output signal of the lateral acceleration detecting means on the front side of the vehicle Means and rear wheel control means for controlling the camber angle by driving the driving means for the rear wheels based on the output signal of the lateral acceleration detecting means on the rear side of the vehicle. apparatus.