Positive displacement diaphragm pumps employing displacer valves

Claim 1

A diaphragm pump for discharging minute quantities of liquid, said pump adapted to be submerged in a receptacle containing the liquid to be discharged, said pump comprising: (a) a pump body composed of a plurality of segments, (b) an inlet port defined at the lower end of the body and an outlet port defined thereabove, (c) at least three spaced pumping chambers defined within said pump body between said inlet and outlet ports and in communication therewith, (d) conduits interconnecting said pumping chambers in series between said inlet and outlet ports, (e) at least one pumping diaphragm secured within said body between said segments to seal off one side of each pumping chamber, (f) at least three driving diaphragms secured with said pump body, each in association with a respective one of said pumping chambers, (g) at least three pressure chambers defined within said pump body, each in association with a respective one of said pumping chambers, a pulse generator connected between a supply of pressurized air and said pump body to deliver control pulses of air to said pressure chambers in a particular sequence and for a desired duration of time, and (i) at least three displacer valves secured to said pumping diaphragm and said driving diaphragms to draw fuid into said pump body through said inlet port, advance the fluid sequentially from pumping chamber to pumping chamber, and then discharge the fluid through said outlet port in discrete pulses, while preventing backflow through said pumping chambers, in response to said control pulses of air.