Pilot actuated diaphragm valve

Abstract

A diaphragm valve operated by a solenoid pilot for opening and closing the gasoline passage from a pumped inlet to the nozzle of a gasoline dispenser. A valve body forms an internal fluid passage for series installation with that of the dispenser. An annular seat surrounds the body passage at an intermediate location while an upstream facing diaphragm cooperates with the seat to open and close the passage to fluid flow. A spaced apart valve plate in combination with the diaphragm form a liquid tight chamber into which gasoline at the inlet can enter through restrictive one-way orifices. Fluid pressure in the chamber aided by a bias spring urges the diaphragm toward the set in opposition to pump pressure at the inlet. The pilot valve is spring biased toward a closed relation and is loop connected from the chamber to the outlet. Energizing the pilot effects a reduction in chamber pressure enabling relatively greater inlet forces against the diaphragm to move the diaphragm toward open position. The pilot valve also operates as a backflow restrictor from the dispenser hose and in response to an overpressure opens to permit backflow to the chamber. A relief valve located internally of the chamber operates in conjunction with pilot backflow operation to relieve chamber pressure buildup to the inlet.