| 摘要 |
PROBLEM TO BE SOLVED: To provide an always optimal steering characteristic regardeless of a vehicle speed by providing a means for changing a fluid flow rate to a chamber for operating pressure on a force transmitting member as a function of the vehicle speed and changing resistance to relative rotation of two valve members of a directional control valve as a fuction of the vehicle speed. SOLUTION: When rotating a steering wheel 18, a hydraulic power cylinder directional control valve 22 is actuated, and a hydraulic fluid is made to flow to either one of a pair of conduits 28, 30 to generate steering assisting force in a power steering motor 31. The directional control valve 22 includes an inner rotary valve member 40 and an outer rotary valve member 42 relatively rotated according to an angle of torsion of an elastic torsion bar 51 in proportion to steering force, and generates the steering assisting force according to relative rotation quantity of both valve members 40, 42. The outer rotary valve member 42 is connected to a force transmitting member 116 faced with a chamber 138 by a cam assembly 120, and is pressed toward the outer valve member 42 by a spring 130 acting between a collar 202 and the force transmitting member 116. |
