| 摘要 |
PURPOSE:To safety control the traveling condition of a vehicle in a rear wheel steering device by changing from an ordinary steering ratio varying control to a steering ratio control having a characteristic on a safety side at the point of time when the lock of a wheel is detected. CONSTITUTION:A fail-safe oil branch pipe 112 is branched off separately from an oil feeding pipe 50, from an oil filter 110. The end of the oil branch pipe 112 is divided in two and the input ports of fail-safe solenoid valves 114, 116 are connected to each end 112a, 112b. The solenoid valves 114, 116 are electrified accompanying the ON action of the ignition key of a vehicle to carry out the closing action of corresponding oil branch pipes 112a, 112b. At the time of detecting a failure, electrification to both solenoid valves 114, 116 is cut off by means of a control unit 132 and an oil pressure fails to act on a power cylinder 40 to keep rear wheels in a neutral position. |
