Check valve in pressure control circuit

摘要

An integrated valve unit for a pressure control circuit which comprises a case, a drier wholely contained in the case, and a check valve formed and positioned in an inlet of the case having a longitudinal axis perpendicular to the longitudinal axis of the case. The check valve includes a cylinder chamber formed in the case having two end faces and a side wall, a fluid inlet port formed in one of the end faces, a pair of discharge ports in the side wall longitudinally spaced from each other and opening into the case, an axially slidable piston inserted into the chamber, a biasing member urging the piston towards one end face having the fluid inlet port formed therein, and an elastic seal member fixed to the piston member. The piston is capable of selectably closing the discharge ports upon axial sliding thereof. The elastic seal member is capable of sealing the portion of one end face including the fluid inlet port as the piston member slides toward that one end face. The elastic seal member can be shaped as a cup-shaped member fixed to the inlet port end face of a cylindrical piston and can have a smaller area then that of the piston end face to which it is affixed. The difference in areas of the seal member and the face of the piston operates to provide a substantially instantaneous opening and closing response to the valve which effectively prevents chattering and vibration.