| 摘要 |
PURPOSE:To ensure the stability of a vehicle on a low friction road surface such as an icy road surface, by restraining the speed of change in rear wheel steering ratio in accordance with the slip factor of the road surface of restrain a change in movement of the vehicle in association with a change in rear wheel steering ratio. CONSTITUTION:In a four wheel steering device for a vehicle, in which the ratio of rear wheel steering is variable, there are provided a friction detecting means 1 for detecting the friction of a road surface and a limiting means 2 for limiting the speed of change in rear wheel steering ratio. Further, there is provided a limiting amount regulating means 3 receiving a signal from the friction detecting means 1, for setting the limiting amount by the limiting means 2 so that it is greater when the friction of the road surface is small than when the friction is large. Further, a limitation is exerted to the speed of change in rear wheel steering ratio in accordance with the slip rate of the road surface in view of the fact that the travel of the vehicle on a low friction surface such as an icy road surface is sensitive with respect to a change in rear wheel steering ratio. Thereby it is possible to ensure the stability of the vehicle during running particularly on a low friction road surface. |
