| 摘要 |
PURPOSE:To facilitate the control of hydraulic reaction force irrespective of steering pressure, by controlling a control pressure applied to a pressure mechanism with the use of a surplus stream in a pump discharge flow. CONSTITUTION:When a vehicle speed exceeds a predetermined value, a solenoid drive circuit 71 is controlled in accordance with a vehicle speed signal V delivered to a computer 70, and a current value I fed to a solenoid 63 in a solenoid relief valve 60 is lowered in accordance with an increase in the vehicle speed. The spring load of a relief pressure setting spring 68 is increased, and a control pressure fed into a reaction force chamber through an introduction port is increased. A reaction piston is pressed against an engaging ball with the axial thrust force to increase a manual torque which allows a sleeve valve and rotor valve to rotate relative to each other, and therefore, the control pressure Pc in accordance with the vehicle speed acts upon the reaction piston, thereby it is possible to provide a speed responsiveness in proportion to an increase in the vehicle speed. |
