HYDRAULIC CONTROL VALVE, POWER STEERING DEVICE AND METHOD AND TOOL FOR MANUFACTURING VALVE SPOOL

摘要

PROBLEM TO BE SOLVED: To more favorably reduce the rate of change of a throttle area for a relative angular displacement of a valve body and a valve spool and to favorably increase steering assist force at the early stage of steering. SOLUTION: On groove edges of a plurality of oil grooves 20 of the valve spool 2 having the grooves 20 and engaged with the valve body so as to displace the relative angle, first chamfer parts 21 chamfered from a side face of the groove 20 to a peripheral face of the valve spool and second chamber parts 22 chambered from the side face inside both ends in the longitudinal direction of the parts 21 are formed.