BIDIRECTIONAL CARTRIDGE VALVE

摘要

A bidirectional cartridge valve comprises a generally cylindrical valve housing including an end port and a side port each opening into an axial, cylindrical bore defining a valve chamber. A flow control element is movable in the valve chamber between a valve open position to open a flow path between the two ports and a valve closed position to block the flow path between the two ports. The flow control element includes a first passage provided with a first check valve connecting the end port with the valve chamber and a second passage with a second check valve connecting the side port with the valve chamber. A cylindrical pilot seat in the chamber includes a partial, axial bore defining a pilot chamber and an opening through the seat connecting the valve chamber with the pilot chamber. A third passage is provided through the valve housing, provided with a third check valve, connecting the pilot chamber to the side port. A fourth passage is provided through the valve housing connecting the pilot chamber to the valve chamber at a select axial position occupied by the flow control element. A fifth passage is provided through the flow control element, provided with a fourth check valve, connecting the valve chamber at the select axial position to the end port to provide a fluid path in communication with the fourth passage. A pilot valve is movable in the pilot chamber between a pilot valve open position to open a flow path between the valve chamber and the pilot chamber whereby fluid pressure at either of the two ports causes the flow control element to move in the valve open position, and a pilot valve closed position to block a flow path between the valve chamber and the pilot chamber whereby fluid pressure in the valve chamber exceeds fluid pressure at both ports to maintain the flow control element in the closed position.