Hydraulic pressure control valve

Abstract

A hydraulic pressure control valve of the present invention applied in hydraulic power steering includes a cylindrical casing whose plural first grooves disposed on its circumferential surface at stated intervals are brought in communication with different destinations of pressure oil, and a valve body which is inserted rotatably into the casing and whose second grooves of the same number as the first grooves, disposed on its peripheral surface at stated intervals are brought in communication alternately with a high pressure source and a low pressure source, and a portion thereof is disconnected with the low pressure source. At corners on the casing opposing each other across the communicating portions on both sides of the disconnected portion of the valve body, notches are formed in such a shape that, until the relative angular displacement between the valve body and casing reaches the predetermined magnitude, variations of communicating areas produced between the first and second grooves by the relative angular displacement is substantially not produced. In the hydraulic pressure control valve, the first groove of the valve body interposed between the notches is not in communication with the low pressure source, and the pressurized oil which flows in through one communicating portion of this portion is introduced into the groove of the adjacent casing through the other communicating portion without flowing back to the low pressure source, so that flowing noises of pressured oil produced when the relative displacement is produced between the valve body and casing can be reduced sharply.