JPS6185276A - Steering controller for car - Google Patents

Abstract

PURPOSE:To improve the steering response and steering stability by providing an actuator for variably controlling the lateral motion of rear wheel with correspondence to change of direction of chassis based on front wheel steering or lateral blow. CONSTITUTION:Front wheel steering angle and steering speed upon turning are fed through front wheel steering sensor 12 to a controller 15. While a car speed signal is fed through a car speed sensor 13 to the controller 15. Upon steering of front wheel, the controller 15 will function on the basis of the steer ing angle signal and steering speed signal from front wheel steering sensor 12 and the car speed signal from car speed sensor 13 to feed predetermined volume of oil with predetermined speed to hydraulic cylinder 11. Consequently, the piston rod 11a will function to the left or right thus to rotate the rotary shaft 6 and the rotary arm 7 through an arm 10 and to move a suspension arm 2 to the left or right to vary the rear wheel shaft 1.

Description

[Detailed description of the invention] Industrial applications The present invention relates to a steering control device for an automobile.

Conventional technology In order to improve the dynamic performance of the vehicle body in response to steering during steering operations, a front and rear wheel steering device was developed that steers the rear wheels in the same direction as the front wheels in conjunction with the steering of the front wheels. Conventionally developed, for example, Japanese Patent Application Laid-Open No. 56-163969,
It has already been published in Jikai +456-167562 and other publications.

Problems to be Solved by the Invention However, in the conventional front and rear wheel steering devices as described above, the interlocking mechanism between the front wheels and the rear wheels is extremely complicated, and the accuracy regarding the alignment of the four steered wheels is extremely high. Therefore, a large misalignment may occur due to variations in the production of parts or slight deformation due to external force, which poses a major problem in terms of +tfI, such as productivity and ease of maintenance in the market.

Historically, in the unlikely event that a failure occurs in the control string for steering the car and the steering locks, even if the Ai 1 wheel is returned to the straight-ahead position, the eastward direction is extremely difficult to turn. The situation has become dangerous, and there are also safety issues for the 4H East.

SUMMARY OF THE INVENTION An object of the present invention is to provide a steering control device that can improve the steering response and the accompanying improvement in steering stability when the rear wheels are turned and C1 is turned. .

The only way to solve the problem is to set the rear wheels of the car at approximately tlVi with respect to the car body.
It is configured to enable lateral movement (dOJ) in the direction of the wind, and the lateral movement of the rear four wheels approximately in the direction of the electric wheels can be varied in response to changes in the direction of the heavy body based on front wheel steering operation or external forces such as crosswinds. System @
In the above, for example, when the J wheels are steered in one direction due to a one-way steering operation, the actuator operates to move the rear wheels in the direction in which the front wheels are steered. The slip angle formed by the ratio of the rear wheel's lateral movement speed and the shunting speed is determined by the composite vector of the lateral movement speed vector of the rear wheel and the vehicle speed vector of the rear wheel section. Cornering force is generated at the rear wheel at this slip angle, which can improve responsiveness to steering operations.

Also, when the direction of the vehicle body changes in one direction due to equal pressure of a crosswind, the same actuator as above operates to move the rear wheels laterally in the opposite direction to the direction of change in the rotation of the vehicle body, thereby preventing the direction of travel from being deviated.
F.

Dormitory weaving example The implementation of the present invention will be explained below with reference to the accompanying drawings.

In Fig. 1, 1 is a rear wheel axle, and the rear wheel axle 1 is connected to a suspension arm 2, a support rod (tension rod or compression rod) 3, a strut damper 4, and a strut damper K, which will be described later. It is supported to become.

The base end of the frame arm 2 is pivotally connected to a rotating arm 7 iCxl+ 8 fixed to a rotating arm 16 that is rotatably supported by a vehicle body side member such as a cross member 5. It has a structure in which the rear four wheels 111 are pivotally attached to the lateral tips of the rear wheels 111 via a shaft 9.

The tip of the piston rod 11α of the hydraulic cylinder device 11 attached to the 1111 member is pivotally connected to the arm 10, and the rotation shaft 6 is rotated by the operation of the +1B pressure cylinder device d11, that is, the axial movement of the piston rod 11α, and the suspension is suspended. A trap is provided so that the horizontal position of the co-moveable fulcrum of the arm 2, ie, 4118, can be controlled by variable pressure.

The support rod 3 has one end connected to the rear wheel axle 1 and the other end connected to a t-body i located approximately lI+rearward of the rear wheel axle 1.
The strut damper 4 is connected to the rear wheel axle 10 so as to be swingable through an elastic material 3a such as rubber, and supports the load in the longitudinal direction of the rear wheel axle 10, and the lower end of the strut damper 4 is connected to the rear wheel axle 1. A cylinder member, a rod that is slidably fitted into the cylinder member with a T4 pin and whose upper end is connected to the vehicle body side member via a rubber elastic member 4α, and a rod provided between the cylinder member and the rod. compression coil spring 4h
It is configured to elastically support the cart in the vertical direction of the IT wheel axle 1.

In the above, in the neutral state where the hydraulic cylinder device 11 is not operating, the co-moving fulcrums of the left and right suspension arms 2, that is, the shafts 8, are held at symmetrical positions with respect to the center line of the electric body,
As the f& wheel shaft 1 moves up and down, the suspension arm 2 rotates up and down about the shaft 8.

Although not shown, the front wheels employ a conventionally well-known front wheel steering system that rotates to the right or left around a king pin based on the rotation of the steering wheel to achieve steering. At this time, the front wheel steering angle and steering speed signals are inputted from the front wheel steering sensor 12 to the control device 1115, and the vehicle speed sensor 13 inputs the tonnage speed signal to the control device 15. It looks like this.

And A + J wheel rotation Ir2 + Samurai, upper DC front wheel steering seta 1
The control device 15 operates based on the steering angle signal and the steering speed signal of 2 and the heavy speed signal of the vehicle speed sensor 13 to feed a predetermined amount of oil to the hydraulic cylinder system [111] at a predetermined speed rc. , the piston rod 11α moves to 20,000 on either the left or right, rotates the rotating shaft 6 and the rotating arm I via the arm 10, moves the suspension arm 2 to 20,000 on either the left or right, and thereby the rear wheel 1 so as to displace lll11 approximately one width direction by a predetermined pupil and at a predetermined speed.

The operation mode of the ^1J rear wheels during the above front wheel steering is shown in the second example.
, 6 will be explained in detail below using the two-wheel model shown in FIG.

FIG. 2 is a two-wheel model diagram showing a transient state in which the front wheel A is cut from the dotted line E to the solid line.

In Figure 2, when turning the front wheel A from point 1 to point 1 to turn to the right, if the rear wheel B remains as shown by the dotted line, the rear wheel B will be centered around the turning center point of the vehicle body. Since the knee of the turning circle moves in the linear direction at the vehicle speed V, the transport vector of the rear wheel B becomes Vr, and β with respect to the rotational plane X-XK of the rear wheel B.
A rear wheel BK cornering force is generated at the slip angle β.

At this time, this rear wheel cornering force acts in a direction that slows down changes in the yaw angle of the vehicle body.

However, in the present invention, as shown in FIG. 1, as soon as a steering operation is performed, the hydraulic cylinder device 111 is actuated by the signal pressure from the front wheel steering sensor 12 to move the return wheel axle 1 laterally in the steering direction. Therefore, when the front wheel A turns to the right from the dotted line to the solid line in Fig. 2, the rear wheel B
moves laterally from the dotted line to the right as shown by the solid line, so the actual movement vector of the rear wheel B is the composite vector Vf of the rear wheel speed vector ■r and the lateral movement speed vector νr.
', giving rise to a slip angle of I,
Due to the slip angle β, a cornering force Ff is applied to the front wheels from the rear wheels, and a cornering force Fr in the opposite direction is generated, and the response delay of the yaw angle to the steering operation becomes extremely small.

In addition, when the front wheel A is turned back as shown by the solid line as shown in FIG. Wheel B moves laterally from the dotted line toward the neutral position as shown by the solid line, and generates a slip angle β in the opposite direction to the above-mentioned increased cutting state, and after the wheel B moves in the opposite direction from the above-mentioned increased cutting state. Since the wheel cornering force Fr is fixed, inconveniences such as delays in the return of the rudder are eliminated.

Therefore, the hydraulic cylinder device 1 based on the above-mentioned control device 15
10 The rear wheel lateral movement caused by the operation is the lateral movement speed obtained by proportionally multiplying the angle corresponding to the front wheel steering angle, and the lateral movement speed obtained by proportionally multiplying the angle corresponding to the front wheel turning speed. At the same time, the magnification of the lateral movement and lateral movement speed with respect to the front wheel steering angle and the front wheel turning speed is controlled by the heavy speed signal of the vehicle speed sensor 13 so that it is small at low vehicle speeds and large at high vehicle speeds. It is possible to significantly improve the steering stability by keeping it in place.

In addition to the above-mentioned steering operations, the present invention also enables the control device to detect changes in the direction of the vehicle body based on signals from the lateral acceleration or yaw rate change detection sensor 14, even if the direction of the vehicle body changes due to external forces such as crosswinds while driving straight ahead. 15 is activated to activate the hydraulic cylinder system fill, which causes the rear wheels to move laterally.

In other words, in a car, for example, when a crosswind is encountered while driving, the aerodynamic center of the vehicle is generally located in front of the center of gravity of the vehicle, so the arrangement is designed to prevent crosswinds from the right direction. When hit, the front of the car swings to the left and the entire car tries to turn to the left.

In this case, when the lateral acceleration or yaw rate change detection sensor 14 detects the lateral acceleration or yaw rate change of the vehicle body, and the rate of change of the lateral acceleration or yaw rate becomes larger than the set value, the direction of the control device 151C is changed. is a button that causes the rear wheels to move laterally to the right at a moving speed proportional to the rate of change of the lateral acceleration or yaw rate. The proportional multiplication factor at this time is controlled by the m11# device 15 so that it is small at low vehicle speeds and large at high vehicle speeds based on the idle speed signal from the vehicle speed sensor 13.

Due to this lateral movement of the rear wheels, the deviation in the traveling direction of the vehicle body is corrected and the vehicle returns to its original traveling direction.

When the rate of change of the lateral acceleration or yaw rate becomes less than a set value, the hydraulic cylinder device 11 is activated by the control device 15 so as to gently return the rear wheels to the original neutral position rMK.

The correction operation for the deviation in the traveling direction due to external force as described above is as follows:
In addition to the crosswind, the deviation K in the traveling direction based on the lateral inclination when traveling on a land that has been stolen is also applied.

In the above embodiment, a hydraulic cylinder device is used as the actuator for laterally moving the rear wheels, but any actuator other than the hydraulic cylinder device, such as a *@motor, can be used.

Furthermore, the rear wheel suspension system is not limited to the type shown in the first diagram, but can be applied to any type of ffIt structure.

Effects of the Invention As described above, according to the present invention, the conventional front and rear wheel steering device steers the rear wheels in the same direction as the steering operation direction of the front wheels, generates cornering force in the rear wheels, and improves steering response. However, since the rear wheels are moved laterally in the front wheel steering direction, almost in the vehicle width direction, cornering force is generated by the slip angle formed by the ratio of the lateral movement speed and the vehicle speed. The lateral movement control mechanism is extremely simple compared to the conventional rear wheel steering control mechanism, and even if there are production variations in parts or slight deformation due to external forces, misalignment is minimized, and productivity and IF field are minimized. Not only is this extremely advantageous in terms of maintenance workability, but even in the unlikely event that a failure occurs in the rear wheel lateral movement control system and the rear wheels are locked in lateral movement, the vehicle will still be able to move straight. There is no difference in its characteristics from a general front-wheel-only Soushinto, and it is safe to live in.

Fourthly, in the present invention, not only during steering operation, but also when the direction of the vehicle body is turned against the driver's will due to an external force such as a crosswind, the rear wheels of K are moved laterally to correct the deviation in the direction of travel. Because of this configuration, together with the improvement in responsiveness during the steering operation, the steering stability of the automobile can be significantly improved, and this can bring about a great practical effect.

[Brief explanation of drawings]

Figure 1 of the prefecture shows a weaving example of the present invention! FiA strabismus prisoner, 2nd
6 and 6 are diagrams showing an example of the operating state of the rear wheels during the front wheel steering operation of the device according to the present invention K as a two-wheel model, and FIG. 2 shows a state in which the steering wheel is turned further, and FIG. 1 and 2 respectively show the state in which the steering wheel is turned back. DESCRIPTION OF SYMBOLS 1... Rear wheel axle, 2... Suspension arm, 3... Support rod, 4... Strut damper, 5... Cross member, 6... Rotating shaft, 7... Rotating arm, 8,9・
... Axis, 11... Hydraulic cylinder device, 12... Front wheel steering sensor, 13... Vehicle speed sensor, 14... Lateral acceleration or yaw rate change detection sensor, 15... Control device, A...・Front wheel, B...Rear wheel. that's all

Claims (5)

[Claims] (1) In an automobile equipped with a front wheel steering device, the rear wheels are configured to be able to move laterally with respect to the vehicle body approximately along the width direction of the vehicle, and the lateral movement of the rear wheels is controlled by steering operation of the front wheels or What is claimed is: 1. A steering control device for an automobile, comprising an actuator that performs variable control according to changes in the orientation of the vehicle body based on external forces such as crosswinds. (2) The lateral movement of the rear wheels is the amount of lateral movement obtained by proportionally multiplying the amount equivalent to the steering angle of the front wheels, and is controlled by an actuator to move the vehicle lateral to the side where the vehicle is turning. A steering control device for an automobile according to claim 1, characterized in that the steering control device for an automobile is configured such that: (3) The lateral movement of the rear wheels is controlled by an actuator so that the vehicle body moves laterally to the side where the vehicle is turning, with a lateral movement speed obtained by proportionally multiplying the amount equivalent to the steering speed of the front wheels. A steering control device for an automobile according to claim 1 or 2, characterized in that the steering control device for an automobile is configured such that: (4) In lateral movement of the wheels, when the rate of change in the vehicle's lateral acceleration or yaw rate due to external forces such as crosswinds is greater than a set value, the direction of the vehicle changes at a speed proportional to the rate of change. The steering control device for an automobile according to claim 1, wherein the steering control device for an automobile is controlled by an actuator so as to move the steering control device laterally in the opposite direction. (5) The amount of lateral movement of the rear wheels during front wheel steering, the magnification of the lateral movement speed to the front wheel turning angle, the front wheel turning speed, and the multiplier of the rear wheel lateral movement speed to the lateral acceleration or yaw rate change rate are as follows: The steering control device for an automobile according to any one of claims 2 to 4, characterized in that the steering control device for a vehicle is controlled to be small when the vehicle speed is low and to be large as the vehicle speed increases. .