Ambulatory pump

Abstract

A pump 10 for delivering a precise selected output volume has a rigid pump housing 12. A diaphragm 16 is in fluid right abutment with the pump housing 12 to define a pump chamber 40 therebetween. The diaphragm 16 is resiliently biased towed a selected metering position 46 wherein the diaphragm 16 assumes a cup-shaped configuration and the pump chamber 40 has a selected metering volume. The diaphragm 16 is drivable to a discharged position 52 wherein the pump chamber 40 has a selected discharge volume less than the metering volume by a selected output volume. The diaphragm 16 maintains the output volume substantially constant notwithstanding substantial variations in fluid pressure from the fluid supply of variations in ambient pressure. An inlet 32 selectively allows fluid to flow between a fluid supply 45 and the pump chamber 40 as the diaphragm 16 moves from the discharged position 52 to the metering position 46. The inlet 32 stops the fluid flow between the pump chamber 40 and the diaphragm 16 when the diaphragm 16 is driven from the metering position 46. A one-way outlet valve 28 in fluid communication with the pump chamber 40 permits flow of the output volume out of the pump chamber 40.