| 摘要 |
PURPOSE:To obtain a changing characteristic of manual torque which is suitable for any running condition, by providing a flow control valve whose opening degree is controlled in accordance with the speed of a vehicle and a flow control device whose opening degree is set in response to the running condition of the vehicle on, for example, a mountain road, in a reaction force control passage. CONSTITUTION:A first flow control valve 70 whose opening degree is controlled in accordance with the speed of a vehicle produces a pressure in a reaction force control passage 62 in accordance with the vehicle speed. This pressure is introduced into a reaction force mechanism 40 to change the assist force of a power cylinder 66. When the steering angle is made to be large, the pressure of a servo passage 61 rises, and accordingly, a part of working fluid in the passage 61 flows into the reaction force control passage 62 through a second flow control valve 80, and therefore, the pressure introduced into the reaction force mechanism rises to change the inclination of a manual torque assist force characteristic in the decreasing direction. At this time the opening degree of the second flow control valve 80 is controlled in accordance with the vehicle speed, and therefore, the manual torque assist force characteristic is also changed.
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