| 摘要 |
PURPOSE:To improve durability by reducing the frequency of use of the equipment on the rear-wheel steering side by prohibiting the steering for rear wheels when car speed is below a prescribed value and steering the rear wheels in the same direction to that of the front wheels in the car speed region exceeding the prescribed car speed, in a 4-wheel steering device. CONSTITUTION:A four-wheel steering device assists the steering for front wheels 12 (additive are omitted) by a steering wheel 19 by using a power steering device 37, and the steering angle of rear wheels 13 is controlled in correspondence with the steering angle of the steering wheel 19 by a rear-wheel steering means 47. A flow-rate control valve 41 controlled by a control circuit 42 according to the output of a car speed sensor 43 is installed onto the discharge side of a pump 39 on the rear-wheel steering means 47 side, and a fluid control valve 45 controlled according to the steering of the steering wheel 19 is installed onto the downstream side of the control valve 41. If the care speed is below a prescribed car speed in this case, flow-rate control valve 41 is controlled so that the whole quantity of pressurized fluid is returned to the suction side, and when the car speed is over the prescribed value, the rear wheels 13 are steered in the same direction to that of the front wheels 12 through a fluid control valve 45. |
