| 摘要 |
PURPOSE:To ensure safe traveling by prohibiting the operation of a rear wheel steering mechanism when the output pulse signal of a vehicle speed sensor indicated the sudden reduction in vehicle speed in a device in which a rear wheel steering angle with respect to a front wheel steering angle (steering ratio) is varied in accordance with the outputs of said vehicle speed sensor. CONSTITUTION:The rear wheel steering mechanism 11 of a four wheel steering device has a spool valve 26 which is installed in the hydraulic circuit of a rear wheel power cylinder 22, and this spool valve 26 is controlled via a steering ratio variable mechanism 40 in accordance with the steering condition of front wheels transmitted to a transmission rod 39. The steering ratio which is controlled by this variable mechanism 40 is varied by a control unit 62 in accordance with the outputs of vehicle speed sensors 66, 67. Each of the vehicle speed sensors 66, 67 includes a reed switch which is opened/closed accompanying the rotation of a wheel and outputs a pulse signal in accordance with a traveling speed. In this case, when the pulse signals obtained from the vehicle speed sensors 66, 67 indicate the sudden reduction in traveling speed, a valve 36 is opened to prohibit the operation of the rear wheel steering mechanism 11. |
