4-WHEEL STEERING APPARATUS FOR AUTOMOBILE

摘要

PURPOSE:To improve steering performance by allowing rear wheels to always pass outside the locus of traveling of front wheels by a prescribed value with respect to the center of turn, when steering is controlled so that the ratio of the rear-wheel steering angle with respect to the front-wheel steering angle varies according to the variation of automobile. CONSTITUTION:Right and left front wheels 1 and 1 are steered through a rack- pinion type steering mechanism by operating a steering wheel, and right and left rear wheels 7 and 7 are steered through a rack-pinion type steering mechanism by the revolution of a pulse motor 14 controlled by a controller 26. The characteristic of the rear-wheel steering ratio with respect to the car speed (ratio of rear-wheel steering-angle with respect to the front-wheel steering-angle) is memorized into the characteristic memory part 33 of the controller 26. The rear- wheel steering ratio is set so that the steering characteristic that the turning center point C on the center line perpendicular to the direction F of advance of the center G of gravity of an automobile at a certain time in turning traveling is positioned before the extension line S in the lateral direction perpendicular to the line L in the longitudinal direction of the automobile A which passes through the center G of gravity can be obtained.