| 摘要 |
PURPOSE:To enable the stable back by providing a detecting means for detecting a back, and variably controlling the operating force with a control characteristic different from that in the advancing time at the time of back. CONSTITUTION:A control unit 30 controls the opening and closing of variable throttle valves 13, 14 in such a manner that the opening of the variable throttle 13 on a pipeline 65 side becomes larger and the variable throttle 14 on the branched pipe 66 side smaller as the vehicle speed is increased. Thus, the pressure of a reaction chamber 12a obtains heavier steering force as the vehicle speed is increased. When an automobile is backed, the changing rate of reaction pressure is set larger than that in the advancing time, and thus the steering force can obtain the same assist as in the advancing time at the time of extremely low speed, and rapidly becomes heavier than that in the advancing time as the speed is increased. Consequently, the generation of yawing by unnecessary swinging of the steering wheel can be suppressed, and stable backing can be conducted. |
