JPS60163769A - Steering device for vehicle - Google Patents

Abstract

PURPOSE:To improve turning performance, by a method wherein, in a steering device which varies the steering angle of rear wheels, a change in steer due to a change in the roll angle of a vehicle during turn running can be effectively reduced through control of steering of the rear wheels. CONSTITUTION:During running of a vehicle, based on previously set data by means of output signals from front wheel steering angle sensor 13 and other sensors, computing process is effected by a computer 12 to obtain rear wheel steering information d0. From a detecting signal (s) proportioning the roll angle of the vehicle body detected from a roll angle sensor 14, based on previously set data, control information d1, which steers the rear wheels in a direction in which a fluctuation amount, equivalent to a steer amount produced by means of said roll angle, is obtained. According to control information d0+ or -d1 determined through addition of steering information d0 to the control information d1, an actuator 8 for steering the rear wheels is controlled.

Description

[Detailed description of the invention] The present invention relates to a steering device for a vehicle such as a four-wheeled vehicle.

The present applicant has already steered not only the front wheels of a vehicle but also the rear wheels depending on certain conditions such as vehicle speed and front wheel steering angle, dramatically improving vehicle maneuverability and steering response. Various steering devices have been proposed that can improve the performance.

By the way, when a vehicle generally makes a turn, the vehicle body rolls (shakes) depending on the turning radius and vehicle speed. In addition, a stroke difference occurs between the left and right suspension strokes in response to this roll, and this stroke difference causes a backward steering change (bump steer, rebound steer) or a camber change determined by the link mechanism that constitutes the suspension.

Furthermore, the roll causes a change in the ground load of the left and right tires, and the roll of the vehicle body while the vehicle is running becomes a harmful disturbance to the vehicle, deteriorating the running performance. For example, the lateral force characteristics (or understeer characteristics, oversteer characteristics) that act on the front and rear tires change depending on the roll angle. As the characteristics change and turning performance deteriorates, the driver is forced to make corrective steering efforts.

Therefore, in this case, if the undesirable steering effort is compensated for by controlling the steering of the rear wheels and the roll fluctuations are canceled out, the adverse effects caused by the roll fluctuations can be effectively eliminated.

Therefore, an object of the present invention is to improve driving performance, especially turning performance, without being affected by steering changes due to changes in the roll angle of the vehicle body while the vehicle is turning, thereby achieving stable driving and comfortable driving. An object of the present invention is to provide a vehicle steering device that can perform the following operations.

In order to achieve the above object, the present invention is applied to a steering system for a vehicle that can variably control the steering angle of the rear wheels, and its main components include a detection means for detecting the roll angle of the vehicle body while driving; Processing means for outputting control information for steering the rear wheels in response to the detection result from the detection means, for example, control information for steering the rear wheels in a direction that reduces the amount of steering of the rear wheels determined by the roll angle of the vehicle body. The vehicle is characterized by comprising a control means for controlling steering of the rear wheels based on this control information.

Below, preferred embodiments that further embody the present invention will be described in detail with reference to the drawings.

First, in order to clarify the present invention, a schematic configuration of a vehicle steering system will be explained based on FIG. This figure is a schematic plan view showing the basic structure of a vehicle equipped with a steering device according to the present invention. In the figure, reference numeral 1 denotes a steering handle, and the steering shaft 2 of this handle 1 is connected to a direction changing means, for example, a rack and pinion system, which is installed inside a gear box 3, and the steering rotation of the handle 1 is controlled by the width of the vehicle body of a tie rod 4. Convert to motion in the direction. Both ends of this tie rod 4 are connected to a knuckle arm 6.6 that supports the front wheels 5, 5, and is supported rotatably in the left and right direction.
Due to this function, the displacement of the tie rod 4 in the vehicle width direction causes the front wheels 5, 5 to be steered in the steering direction of no./$1.

On the other hand, 7 is a rear wheel side gear box, and a shaft 8a extending rearward from a rear wheel steering servo actuator 8 is connected to a direction changing means such as a rack and binion type installed in this gear box 7. Furthermore, a knuckle arm 10.degree. 10 is rotatably connected to both ends of a tie rod 9 that passes through the gear box 7 in a movable manner in the vehicle width direction, and this knuckle arm 10.degree. 10 supports a rear wheel 11.11. This causes the tie rod 9 to be displaced in the width direction of the vehicle body by the rotation of the shaft 8a, similar to the steering of the front wheels, and furthermore, the rear wheels 1t,
11 in the required direction.

On the other hand, the vehicle is equipped with an on-board computer 12, and this computer 12 includes, for example, a front wheel steering angle sensor 13 that detects the steering angle of the front wheels, a lateral acceleration sensor that detects the acceleration of the vehicle in the lateral direction as shown in the figure, or a vehicle speed sensor 13 that detects the steering angle of the front wheels. The front wheel steering servo actuator 8 receives detection signals from various sensors provided as necessary, such as a vehicle speed sensor, and supplies corresponding control signals to the front wheel steering servo actuator 8 to steer the rear wheels.

A roll angle sensor 14 detects the roll angle of the vehicle body 15 as an electrical signal proportional to the roll angle using a gyroscope, for example, and supplies it to the computer 12.

Next, the configuration and functions of the main parts of the present invention will be specifically explained with reference to FIGS. 2 and 3. FIG. 2 is a functional block diagram of the rear wheel steering system, and FIG. 3 is a characteristic diagram for explaining the principle.

First, in FIG. 2, the computer 12 is connected to various sensors such as the front wheel steering angle sensor 13 shown in FIG. ) and the rear wheel steering information d corresponding to the detection result.

get. This information d is given to the servo actuator 8, and rotates the shaft 8a through operations such as digital-to-analog conversion, amplification, and motor drive.
11 is steered. The above configurations and functions have generally been proposed by the applicant, and can be configured as desired, and may not be provided in accordance with the present invention.

On the other hand, in the computer 12, the roll angle sensor 1
Detection signal S proportional to the roll angle of the vehicle body detected from 4.
control information d for steering the rear wheels in a direction that reduces the variation in the amount of steering caused by the roll angle is generated and output based on data (e) set in advance by arithmetic processing).

As is clear from the roll angle vs. steer amount characteristic P of the car body shown in Figure 3, the steer amount is a heuristically constant value that is determined by the suspension link configuration, ground load, etc. with respect to changes in the roll angle. varies according to a function of Therefore, if this characteristic P is set in the program as data (e) in advance, the amount of steering can be easily reduced, and the control information d1 for further reducing (cancelling) this amount of steering can be obtained by calculation. be able to. In addition, in the calculation process), the direction (left or right) and magnitude of the roll angle are determined at the same time.

Therefore, the control information d1 acts to cancel the characteristic P shown in FIG. 3, so to speak, and has the function of causing the rear wheels to have the opposite characteristic Q shown in FIG.

This control information d is added to the addition process (-c), and if the information d exists, the information do=f=d,
(± indicates steering to the left or right) and when the information do is not present, it is supplied alone to the actuator 8. As a result, the actuator 8 steers the rear wheels to cancel out the unnecessary steering change amount caused by the roll of the vehicle body, and does not adversely affect the original driving performance, especially the response characteristics during cornering. In addition, in the calculation process), control information d1 that completely cancels out such an unnecessary amount of steering change may be generated, or an arbitrary setting with a slight deviation may be used.

Each process in the computer 12 described above is executed according to a control program (software) stored in advance. Note that an electric circuit or the like having the same function may be used instead of the computer 12.

As described above, the vehicle steering system according to the present invention can effectively reduce steering changes caused by changes in the roll angle of the vehicle body during turning, by controlling the steering of the rear wheels. By improving running performance, especially turning performance, it is possible to achieve stable running and comfortable driving.

[Brief explanation of drawings]

FIG. 1 is a schematic plan view showing the basic structure of a vehicle equipped with a steering device according to the present invention, FIG. 2 is a functional block diagram of a rear wheel steering system, and FIG. 3 is a characteristic diagram for explaining the principle. In the drawing, 5 and 5 are front wheels, 1111 is a rear wheel, 12 is an onboard computer, 13 is a front wheel steering angle sensor, 14 is a roll angle sensor, 15 is a vehicle body, (a) and (e) are data, (b)
, ni) is arithmetic processing, and dl is control information. Patent Applicant Honda Motor Co., Ltd. Agent Patent Attorney 2 1) Production Department Patent Attorney Kuni Ohashi Production Volume Patent Attorney Yu Koyama Figure 1

Claims (2)

[Claims] (1) A vehicle steering device capable of varying the steering angle of the rear wheels, characterized by comprising the following means. (a) a detection means for detecting the roll angle of the vehicle body while the vehicle is running; (b) a processing means for outputting control information for steering the rear wheels in response to the detection result from the detection means; and (c) the control information. control means for controlling the steering of the rear wheels by; (2) The vehicle according to claim 1, wherein the processing means outputs control information for steering the rear wheels in a direction that reduces the amount of steering of the rear wheels determined by the roll angle of the vehicle body. Steering device.