Easily assembled, leakproof liquid dispensing pump

Abstract

An easily assembled, low cost, disposable pump is disclosed for use with household liquid product containers. The pump is designed to prevent leakage of the product regardless of container attitude and comprises hollow outer and inner cylinders, each having an end wall, the cylinders being nested in telescoped manner with their end walls in spaced adjacency to form an intake valve chamber and a superimposed product receiving and discharging pump chamber. Liquid inlet duct means is formed in the respective end walls of each cylinder for admission of fluid, and a plunger assembly including a hollow stem and a piston is slidably received in the inner cylinder for reciprocable pumping action therein. The hollow stem provides communication between the pumping face of the piston and atmosphere, via a check valve disposed in the stem. A second check valve is disposed in the valving chamber formed by the telescoped cylinders. The nested cylinders also define an enclosed annular passage intermediate their side walls, each cylinder having a vent conduit in its side wall communicating with this annular passage. The vent conduit of the outer cylinder is continuously open to the interior of the container, while that of the inner cylinder is closed by juxtaposition of the piston head in its normal extended position, but is open to provide communication to atmosphere along the piston stem above the piston head whenever the plunger assembly is depressed. The arrangement provides for venting the interior of the container to atmosphere during pumping operation, yet prevents leakage through the vent conduits between uses of the pump, regardless of container attitude.