Directly operated pneumatic valve having a differential assist return

摘要

A fluid control valve includes a valve body (12) having both fluid inlet (28) and discharge ports (30). A flow passage (34) axially extending within the valve body communicates with the inlet and discharge ports. A valve member (38) within the flow passage is movable by an actuator force in a first direction to direct a pressurized fluid from the inlet to the discharge port. The valve member includes first (42) and second (43) valve heads having different diameters and a valve seating member (44). The valve seating member engages first and second sealing diameters of the flow passage, the second sealing diameter being smaller than the first. Fluid pressure acting on the different diameters of the first valve head and valve seating member in contact with the second sealing diameter creates a net return force directing the valve member in a second direction opposite to the first direction upon removal of the actuator force.