JPH0468186B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) This invention relates to improvements in front and rear wheel steering devices for vehicles such as four-wheeled vehicles.

(Prior Art) FIG. 1 is a block diagram of a steering system proposed by the present applicant in Japanese Patent Application Laid-Open No. 57-60974.

A conventional steering device 100 includes a turning direction sensor 102 that detects operation of a steering wheel (steering handle) 101, and an acceleration/deceleration sensor 103 that detects acceleration/deceleration of the vehicle. The control computer 104 performs the following processing based on the detection outputs of the respective sensors 102 and 103.

At a constant vehicle speed, each rear wheel steering angle δr is set to δr = k·δf, which is the front wheel steering angle δf multiplied by a proportionality constant k, in order to generate the lateral acceleration necessary for turning in the vehicle. Furthermore, when the vehicle accelerates or decelerates, k is a function corresponding to the acceleration or deceleration.

Then, the control computer 104 supplies information δr related to the rear wheel steering angle obtained through calculation to the rear wheel steering drive means 105, and the rear wheels 106, 1
06 is being steered.

The rear wheel steering drive means 105 includes a servo actuator 105a, a gear box 105b, a tie rod 105c, and a knuckle arm 105d.
05d, etc., and information δr related to the rear wheel steering angle.
The configuration is such that the rear wheels 106, 106 are steered based on this.

Further, the front wheel steering means 107 transmits the steering operation of the steered wheel 101 to the gearbox 107b via the steering shaft 107a, converts the steering operation into a linear motion of the tie rod 107c by the gearbox 107b, and transmits the steering operation via the knuckle arms 107d, 107d. The vehicle is configured to steer the left and right front wheels 108, 108 by using the steering wheel.

Further, the turning direction sensor 102 is connected to the steering shaft 107.
It is configured to detect rotation of a.

In this way, the conventional steering device 100 applies a rear wheel steering angle δr proportional to the front wheel steering angle δf to the rear wheels to generate the lateral acceleration necessary for turning, and then adjusts the proportionality constant k according to the acceleration. Since it is a function of the curve, it is possible to suppress changes in the turning radius and turning characteristics during acceleration and deceleration.

(Problem to be Solved by the Invention) Generally, when a vehicle is cornering, the driving vehicle often accelerates in the latter half of the cornering, but in this case, at curves with relatively poor visibility, the vehicle body tends to move inward in the direction of the turn. It is easier to see to the front of the corner and operate the steering wheel more easily if you face the corner (see Figure 6B).

However, the conventional steering system determines the rear wheel steering angle based on the product output δr (δr = k・δf) obtained by multiplying the front wheel steering angle δf by a coefficient k set according to acceleration/deceleration. Because of this configuration, even if the acceleration is the same, the amount of steering angle of the rear wheels differs greatly between when the front wheel steering angle is large and when it is small.

In this way, with conventional steering systems, the steering angle of the rear wheels changes depending on the steering angle of the front wheels. It is difficult to set desired characteristics, such as setting the steering angle of the rear wheels to be changed.

This invention was made to solve these problems, and its purpose is to provide a vehicle that can change its attitude so that when accelerating during cornering, the driver can see all the way to the front of the corner. An object of the present invention is to provide a front and rear wheel steering device.

(Means for Solving the Problems) In order to solve the above problems, a front and rear wheel steering device for a vehicle according to the present invention includes a front wheel steering angle detection means for detecting a steering angle of the front wheels, and a detection output of the front wheel steering angle detection means. or a rear wheel steering angle calculation means for generating rear wheel steering angle information based on a detection output of a lateral motion sensor that detects the lateral movement of the vehicle; an acceleration detection means for detecting the degree of acceleration of the vehicle; and a front wheel steering angle. When it is determined that the vehicle is in a turning state based on the detection output of the detection means, the steering angle of the rear wheels is corrected so that the attitude of the vehicle is directed inward in the turning direction in response to the detection output of the acceleration detection means. a rear wheel steering angle correction information calculating means for generating information for steering the rear wheels; a subtracting means for subtracting the rear wheel turning angle correction information from the rear wheel turning angle information; and a subtracting means for subtracting the rear wheel turning angle correction information from the rear wheel turning angle information; The vehicle is characterized by being equipped with a rear wheel steering drive means.

(Operation) The rear wheel turning angle correction information calculation means calculates and outputs rear wheel turning angle correction information according to the degree of acceleration when the vehicle is running and turning and is in an acceleration state.

The subtraction means supplies information obtained by subtracting the rear wheel turning angle correction information from the rear wheel turning angle information to the rear wheel turning drive means.

Therefore, when accelerating during cornering, the attitude of the vehicle is corrected so that it faces inward in the direction of the turn, allowing the driver to see beyond the corner, making it possible to drive comfortably even on curves with poor visibility.

(Embodiments) Examples of the present invention will be described below with reference to the accompanying drawings.

FIG. 2 is a schematic plan view of a vehicle equipped with a front and rear wheel steering device according to the present invention.

In FIG. 2, there is a single steering wheel (steering wheel), and the steering shaft 2 of the steering wheel 1 is controlled by a direction changing means, for example, a rack and pinion system, which is installed in a gear box 3, and the steering rotation of the steering wheel 1 is controlled by a tie rod 4. This is converted into movement in the width direction of the vehicle. Both ends of the tie rod 4 are connected to knuckle arms 6, 6 that support the front wheels 5, 5, and by the function of the knuckle arms 6, 6 which are rotatably supported in the left and right directions, the displacement of the tie rod 4 in the vehicle width direction is controlled by the front wheels. 5, 5 in the steering direction of the handle 1.

On the other hand, 7 is a rear wheel side gearbox, and a shaft 8a extending from a rear wheel steering servo actuator 8 is connected to a direction changing means such as a rack and pinion type built in this gearbox 7. Knuckle arms 10, 10 are rotatably connected to both ends of the tie rod 9, which passes through the gear box 7 in a movable manner in the vehicle width direction.
supports the rear wheels 11,11. As a result, the tie rod 9 is displaced in the width direction of the vehicle body by the rotation of the shaft 8a, similar to the steering of the front wheel side, and furthermore, the rear wheel 1
1 and 11 in the required steering direction.

In addition, in this embodiment, the rear wheel side gearbox 7
, a rear wheel steering servo actuator 8, a tie rod 9, and each knuckle arm 10, 10 constitute a rear wheel steering drive means.

In addition, in this embodiment, the rear wheel side gearbox 7
, a rear wheel steering servo actuator 8, a tie rod 9, and each knuckle arm 10, 10 constitute a rear wheel steering drive means.

On the other hand, the vehicle is equipped with an on-vehicle computer 12, and is configured to perform rear wheel steering control using this computer 12.

A front wheel steering angle sensor 15 constituting a front wheel steering angle detection means for detecting the steering angle of the front wheels is disposed in the gear box 3 on the front wheel side. By detecting the magnitude of front wheel steering which is proportional to , and providing the detection result to the computer 12, the rear wheels are steered in accordance with the front wheel steering.

Reference numeral 14 denotes an acceleration sensor constituting acceleration detecting means, which detects that the vehicle speed is in an accelerated state by, for example, detecting the rotational speed of the axle.

FIG. 3 is a functional block diagram of the rear wheel steering control system.

A front wheel steering angle sensor 15 and an acceleration sensor 14 shown in FIG. 1 are connected to the computer 12. The computer 12 is used to calculate rear wheel steering angle information d2, and control information corresponding to the degree of acceleration (rear wheel steering to direct the vehicle body attitude inward in the turning direction) is provided. The rear wheel steering angle correction information calculation means (e) calculates the rear wheel turning angle correction information (d4) for correcting the rear wheel steering angle, and the subtraction means (c) subtracts the control information d4 from the rear wheel steering angle information d2.

The detection output (front wheel steering angle) d1 of the front wheel steering angle sensor 15 is subjected to arithmetic processing based on preset data in the computer 12 to obtain rear wheel steering information d2 corresponding to the detection result d1. This information d2 is positive when the steering of the rear wheels is in the same phase as the steering of the front wheels, and negative (that is, ±d2) when the steering of the rear wheels is in the opposite phase.

Then, this information d2 is given to the servo actuator 8, and is applied to the shaft 8 through operations such as digital-to-analog conversion, amplification, and motor drive.
A is rotated to steer the rear wheels 11, 11.

On the other hand, the acceleration sensing sensor 14 is connected to the computer 12 as described above.
In step 4, detect the presence or absence of acceleration and the magnitude of acceleration at the same time.
This detection result d3 is input to the computer 12. The computer 12 performs arithmetic processing based on preset data to obtain required control information d4 corresponding to the detection result d3. By subtracting this control information d4, the rear wheel steering information d2 is
, and the information (±D2-d4) is supplied to the servo actuator 8.

When the front wheel steering angle signal d1 output from the front wheel steering angle sensor 15, which is the front wheel steering angle detecting means, exceeds a predetermined threshold value set in advance, the rear wheel steering angle correction information calculation means E Only when wheels 5 and 5 are being steered, control information (rear wheel steering angle correction information) d4 is generated and output according to the degree of acceleration.

Next, the control information d4 will be specifically explained.

This control information d4 is used to steer the rear wheels so that the attitude of the vehicle is additionally turned inward in the turning direction, in response to the steering information of the rear wheels steered according to the rear wheel steering information d2 while the vehicle is running and turning. This is to steer the front wheels by a required angle in a direction opposite to the direction in which the front wheels are steered, and as described above, the magnitude of this additional steering is set to a specific value.

That is, as shown in FIGS. 4 and 5, for the rear wheels 11, 11 shown by solid lines originally set by the rear wheel steering information d2, the steering angle of the rear wheels is further changed by changing the steering angle of the front wheels. Turning angle θ1 or θ in the opposite direction to the direction
Only 2 of the control information (rear wheel steering angle correction information) d4
The fourth
The figure shows a state in which the rear wheels 11, 11 are steered in the opposite phase to the front wheels 5, 5, and FIG. 5 shows a state in which they are steered in the same phase, both of which are additionally steered. The rear wheels 11a, 11a shown by imaginary lines represent the steered state of the rear wheels after the steering is done.

Therefore, in the computer 12, when the vehicle is running and turning, that is, when the front wheels are being steered,
If the vehicle is in an accelerating state, it is detected and the rear wheels are steered by a predetermined angle so that the posture of the vehicle body faces inward in the turning direction, allowing the driver to easily see ahead during, for example, the latter half of cornering.

Figures 6a and 6b show a state in which the vehicle C is traveling on a curve E, Figure a shows the vehicle body posture in a conventional steering system, and Figure 6b shows a state in which the vehicle C is running on a curve E. Therefore, it shows a state in which the attitude of the vehicle body has changed.

As is clear from the figure, with the conventional steering system, the driver cannot see ahead of the corner as shown by the arrow (H1), but with the front and rear wheel steering system according to the present invention, the driver cannot see ahead of the corner. As for the forward visibility direction, you can easily and clearly see ahead of the corner as shown by arrow (H2).

In this embodiment, a configuration has been described in which the detection output d1 of the front wheel steering angle sensor 15 is supplied to the computer 12 to obtain rear wheel steering angle information d2, but the lateral movement (lateral acceleration) shown by the dotted line in FIG. The rear wheel turning angle information d2 may be obtained based on the detection output of the detection means 13. The lateral movement (lateral acceleration) detection means 13 can be configured using a sensor for detecting lateral movement of the vehicle body, such as a lateral acceleration sensor or a yaw rate sensor.

Further, in this embodiment, the acceleration detecting means 14 is constituted by a sensor that directly detects the vehicle speed, but it may be constituted by a simple sensor that detects the accelerator pressing force or the like.

In addition, although we have given an example of a case where an on-vehicle computer is used to execute according to a predetermined control program,
The rear wheel steering control system may be configured with other electrical circuits having the same function.

(Effects of the Invention) As described above, the front and rear wheel steering device for a vehicle according to the present invention adjusts the posture of the vehicle body so that the vehicle body faces inward in the turning direction when the vehicle accelerates in the latter half of cornering while traveling on a curve or the like. This allows the driver to easily and clearly see ahead of the corner.
You can drive comfortably even on curves with poor visibility.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of a conventional steering device, Fig. 2 is a schematic plan view of a vehicle equipped with a front and rear wheel steering device according to the present invention, and Fig. 3 is a rear wheel steering control system configured using an on-board computer. 4 to 6 are functional diagrams. In the drawing, 1 is a steering wheel, 5 is a front wheel, 8 is a rear wheel steering servo actuator, 11 is a rear wheel, 12 is a computer that performs rear wheel steering control, 13 is a lateral movement (lateral acceleration) detection means, Reference numeral 14 denotes an acceleration sensing sensor constituting an acceleration detecting means, 15 a front wheel steering angle sensor constituting a front wheel steering angle detecting means, B a calculating means constituting a rear wheel steering angle calculating means, C a subtraction means, and E a rear wheel steering angle sensor. Rudder angle correction information calculation means, d1 is a front wheel steering angle signal (output of a front wheel steering angle sensor), d2 is rear wheel turning angle information, d3 is acceleration information (output of an acceleration sensing sensor), d4 is rear wheel turning angle correction information (control information).

Claims (1)

[Scope of Claims] 1. Front wheel steering angle detection means for detecting the steering angle of the front wheels; rear wheel steering angle calculating means for generating wheel turning angle information; acceleration detecting means for detecting the degree of acceleration of the vehicle; and when it is determined that the vehicle is in a turning state based on the detection output of the front wheel steering angle detecting means. , rear wheel turning angle correction information for generating rear wheel turning angle correction information for correcting the rear wheel turning angle so as to direct the attitude of the vehicle inward in the turning direction in response to the detection output of the acceleration detecting means; A calculation means, a subtraction means for subtracting the rear wheel turning angle correction information from the rear wheel turning angle information, and a rear wheel steering drive means for steering the rear wheels based on the subtracted output of the subtraction means. Features: Front and rear wheel steering system for vehicles.