| 摘要 |
PURPOSE:To improve the reliability of operation by changing a steering ratio control to a fail-safe control when a vehicle traveling condition is detected at the time of detecting the vehicle speed of zero while, on the other hand, prohibiting the change to the fail-safe control at the time of detecting a brake operating condition. CONSTITUTION:A rear wheel steering device 10 has a steering ratio control mechanism 64 whose input shaft is a rear wheel steering shaft 60 interlocked with a front wheel steering device 14 and, by controlling the control motor 100 of the mechanism 64 by means of a controller 132, a control valve 46 is controlled via an output rod. In this case, the steering ratio of rear wheels is set in accordance with the vehicle speed detected from the outputs of two vehicle speed sensors 122, 124 provided on each of separate rotary members to control the control motor 100. Also, when the traveling condition of a vehicle is detected by a travel detecting means at the time of detecting the vehicle speed of zero, a steering ratio control is changed to a fail-safe control while, on the other hand, at the time of detecting a brake operating condition, the change to the fail-safe control is prohibited. |
