| 摘要 |
PURPOSE:To enable ensurance of running stability of a vehicle even during abnormal running, by a method wherein through switching of a hydraulic control means, a steering angle ratio is controlled for variation from a reverse phase to an in phase, and setting of the steering ratio to a reverse phase is prohibited. CONSTITUTION:A hydraulic pump 71 is driven by an engine, and working oil pumped up from a reservoir 72 is fed to an unload valve 73. An electromagnetic change-over valve 74 has a discharge port connected to the reservoir 72 through a check valve 75 and has an input output port connected to an oil chamber for steering rear wheels through a conduit P. When, during control of a steering angle ratio, an abnormality detecting circuit 84 detects abnormality on a car speed sensor 81, a steering angle ratio sensor, and an electric motor 51, control of drive of the electric motor 51 by means of a motor control circuit 83 is stopped, and a gate circuit 85 is controlled for non-energization. This constitution changes over the electromagnetic change-over switch 74, and causes connection of the oil chamber to the reservoir 72 through the electromagnetic change- over switch 74 and a check valve 75. |
