Importance

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Abstract

A discharge valve system is provided for a finger-operable pump with an actuating plunger. In one embodiment, the plunger includes a piston disposed in a pump pressurizing chamber. In another embodiment, the plunger is slidably disposed on a fixed piston so that the plunger and piston together define a pressurizing chamber. In either embodiment, the chamber receives fluid from a container. The actuating plunger defines a discharge passage establishing communication between the ambient atmosphere and the chamber. The discharge valve system includes a valve seat defined by the plunger in the discharge passage. A valve member is disposed in the discharge passage and is movable (a) upstream to a closed position against the valve seat wherein the valve member defines a first area subjected to the chamber pressure and (b) downstream to an open position away from the valve seat wherein the valve member defines a second area subjected to the chamber pressure such that the net pressure force imposed on the valve member by the chamber pressure is greater when the valve member is opened than when the valve member is closed. A spring biases the valve member toward the valve seat and another spring biases the plunger to an elevated, rest position.

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First Claim