Diaphragm valve with filter screen and movable wiper element

Abstract

A diaphragm-type control valve for irrigation systems has an outer clam-shell housing that encloses a vertically reciprocable diaphragm assembly. A primary valve seat inside the housing is engaged and disengaged by a seal on the underside of the diaphragm to open and close the valve by connecting and disconnecting its inlet and outlet passages. Pressurized water from a lower inlet chamber of the valve travels through a small metering orifice in the center of the diaphragm assembly to an upper pressure control chamber above a flexible membrane of the diaphragm assembly. A solenoid actuated pilot valve is operatively coupled to the upper pressure control chamber for venting pressurized water therefrom to permit the diaphragm assembly to move upwardly to open the valve. A filter screen is mounted to the underside of the diaphragm assembly to prevent debris from clogging the metering orifice, clogging the small passages of the pilot valve, or fouling the solenoid. A cylindrical wiper element supported by a cylindrical carrier surrounds the filter screen and is moved up and down along the filter screen as the valve opens and closes to scour algae, mineral deposits and other debris from the surface of the filter screen which are carried away through the main outlet passage of the valve.