Importance

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Abstract

A liquid material dispenser, for use, for example, in dispensing liquid medicine over an extended period of time, which includes a housing (10) enclosing a reservoir (12) for storing the liquid to be dispensed and having an outlet (14) through which the liquid is dispensed, and a connecting passageway (16) between the reservoir and the outlet. Located in the passageway is a diaphragm (18), one side of which defines a pumping chamber (20) and the other side of which defines a pressure control chamber (22). The diaphragm (18) is cyclically displaceable through a pumping stroke for pumping liquid through the outlet (14) and a drawing stroke for drawing liquid from the reservoir (12). Also located in the passageway (16) are a pair of valves (30, 33) which serve, during the drawing stroke, to cause the diaphragm (18) to draw liquid from the reservoir (12) into the pumping chamber (20), and during the pumping stroke, to cause the diaphragm (18) to pump liquid from the pumping chamber (20) through the outlet (14). An electrolytic cell (24) generates gas at suitable times for suitable durations and rates which is supplied to the pressure control chamber (22) to drive the pumping member (18) through the pumping stroke. A vent is used for venting the gas from the pressure control chamber (22) to the atmosphere to drive the pumping member (18) through the drawing stroke. The vent has an inlet vent opening (40) inside the pressure control chamber (22), with the opening (40) being caused to open to end the pumping stroke and to close after a portion of the gas has vented.

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First Claim