| 摘要 |
PURPOSE:To obtain a proper rear wheel steering state by selectively driving and controlling a control valve for rear wheel steering control, a by-pass valve and a lock mechanism, depending upon a front and rear wheel steering angle, a vehicle speed and the displacement of a control valve. CONSTITUTION:A controller 6 determines a rear wheel steering angle, depending upon a front wheel steering angle and a vehicle speed supplied from sensors 4 and 19, and while feeding back a signal from a valve displacement sensor 14 and a rear wheel steering angle sensor 20, regulates a rear wheel steering control valve 10. A rear wheel steering power cylinder 3 is thereby actuated and rear wheels 5 are steered. In this case, when a vehicle speed becomes equal to or above the predetermined value. the controller 6 opens a bypass valve 15 and the right and left chambers 3a and 3b of a power cylinder 3 are made continuous to each other, thereby separating the rear wheels 5 from a steering control system. In addition, the rear wheels 5 are reset to a neutral position with a centering spring mechanism 17a, and a lock mechanism 18 is actuated for obtaining an un-steering state, thereby maintaining a two-wheel steering state. According to the aforesaid construction, a proper rear wheel steering state can be obtained. |
