The present invention relates to a system for steering rear wheels of a motor vehicle.
A four-wheel steering system for steering rear wheels together with front wheels is known. Japanese Patent Laid Open No. 58-112875 dicloses such a system wherein the rear wheels are steered simultaneously with the front wheels by the operation of a steering wheel. In the system, the steering system of the rear wheels is employed with the steering device operated in the same manner as the front wheels. Namely, the steering device for the rear wheels comprises the same gear device as the front wheel such as a rack and pinion device. The gear device is synchronized with the movement of the front steering system so as to turn the rear wheels about kingpins.
However, the rear steering system is extremely complicated so that not only is the system expensive but it also takes up space. In addition, the proportion of the rear wheel steering angle to the front wheel steering angle is very small. Accordingly, errors in gears and play in links affect the control of the steering angle. In order to accurately control the steering angle, it is necessary to improve the precision of gearings and links and to minimize backlash and play formed therein.
In another system, an actuator operated by an oil pressure device or by an electric motor is provided to directly control the steering system for the rear wheels. However, it is difficult to accurately control a small steering angle and to maintain the rear wheels at desired angular position only by the actuator.