Samuel Reid Hanford

US Patent:

52844250, Feb 8, 1994

Filed:

Nov 18, 1992

Appl. No.:

7/978346

Inventors:

Ludwig K. Holtermann - Old Saybrook CT
Jodie D. Haupt - North Guilford CT
Samuel R. Hanford - Ivoryton CT

Assignee:

The Lee Company - Westbrook CT

International Classification:

F04B 4500

US Classification:

417395

Abstract:

A pump for dispensing accurately measured amounts of fluid has a one way check valve in the flow path on the upstream side of a pump chamber and a one way check valve in the flow path at the downstream side of the pump chamber which is of variable internal volume. A flow passage provides fluid communication from the upstream check valve to the pump chamber and enters the pump chamber by a centrally located opening that is surrounded by a valve seat. One wall of the pump chamber is a flexible and elastic diaphragm that is attached to the plunger portion of a solenoid actuator. The plunger and diaphragm are biased by a spring acting upon the plunger such that, in the absence of excitation of the solenoid coil, the diaphragm is biased against a valve seat, preventing flow through the pump. All components exposed to the fluid media are formed of chemically inert, non-corrosive substances and the pump can be sized to accurately dispense fluids in increments of as little as 10 microliters, representing the volume of fluid that passes through the pump in one cycle of the solenoid actuator.