Relief valve for an oil pump

摘要

A relief valve for regulating discharged oil pressure of an oil pump at a predetermined level comprises a cylinder including a bore therein and relief grooves formed symmetrically relatively to an axial center of the bore, while each of the relief grooves has a respective opening to an inner peripheral portion of the bore; a valve body disposed in the cylinder so as to be slidably moved in the bore in response to the discharged oil pressure supplied into the bore at one side of the valve body; a spring provided in the other side of the valve body constantly urging the valve body toward the one side of the valve body so as to close the openings of the relief grooves by the valve body; and an adjusting means for adjusting a change rate of an opening area of the relief grooves relatively to one slide movement of the valve body against the force of the spring so that the change rate of the opening area at the beginning of slide movement of the valve body is smaller than that at the end of the slide movement of the valve body.