| 摘要 |
PURPOSE:To enhance the rigidity of a steering wheel upon straight running at a high speed to realize a safe running, by controlling a power steering unit upon high speed running such that a main valve side varitable restrictor is actuated in its closing direction while a reaction chamber side variable restrictor is actuated in its opening direction to enhance the reaction pressure of the steering unit. CONSTITUTION:An auxiliary spool 29 is fixed to a plunger 31 in a solenoid 30. Variable restrictor are constituted by an annular bead 29c formed on the outer periphery of an auxiliary spool 29 and two annular beads 27a, 27e on a main steel 27. Upon stopping the main spool 27 and the auxiliary spool 29 are held in the positions shown in the drawing. Pressure oil from a pump 32 is fed to a main valve 24. Since the reaction chamber side variable restrictor is closed and therefore, the reaction pressure does not raise, the torque of steering becomes lower. Upon straight running at a high speed a solenoid 30 is energized to move the auxiliary spool 29 rightward. Therefore, the main valve 24 side variable restrictor is constricted while the reaction chamber 33 side variable restrictor is opened. Accordingly, the rigidity of the steering wheel may be enhanced since the reaction pressure raises.
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