JPS54162339A - Power steering system - Google Patents

Abstract

PURPOSE: To improve performance of a power steering system, by changing the pressure in an oil outlet chamber in accordance with pressure change in an oil supply chamber that is changed with resistance on the road surface.

CONSTITUTION: Valve spool 6 is fitted in valve housing 7 in the manner that it is turned around itself and movable in axial direction by means of sleeves 13, 14, and the spool 6 is urged by spring 15 toward the end face of ball screw shaft 3. Further, a pressure oil ejecting port 3b in the form of nozzle is formed in the end face of stopper projection 3a which is engaged in the end face of handle shaft 1 of ball screw shaft 3, such that it is communicated with pressure oil supplying port 10 via conduits 16, 17. With such an arrangement, when the handle shaft 1 is turned and rotational displacement corresponding to the resistance on the road surface is caused between valve spool 6 and valve housing 7, thereby controlling the flow rate of pressure oil supplied to the hydraulic cylinder, oil ejecting pressure at nozzle 3b is raised and valve spool 6 is shifted against the force of spring 15 to the position where axial force is balanced. At the same time, opening area of outlet oil communicating port 6a is limited by projection 1a, and pressure difference in oil outlet chamber B and in oil supply chamber A is decreased, so that occurrence of caviation can be prevented.

COPYRIGHT: (C)1979,JPO&Japio