Liquid dispensing system with improved sealing augering screw and method for dispensing

摘要

A liquid dispenser has an augering screw that serves both a metering function and a valving function. The augering screw is axially movable between a position in which fluid can flow and a sealing position in which liquid flow through the nozzle is substantially prevented. The screw is preferably designed with a curved contour between the threads and with a plurality of thread-defining channels to allow liquid to fill more completely around the screw and to dispense more liquid with fewer screw turns than prior screw designs.