Patent ID: 8251981

Claim:
A pump mechanism for use in an implantable drug delivery system having a positive pressure reservoir, the pump mechanism comprising: a) a pump having a pump inlet and a pump outlet; b) a pressure regulator, the pressure regulator comprising: i) a housing having a chamber; ii) a diaphragm dividing the chamber into a first subchamber and a second subchamber; iii) the first subchamber having a first inlet and a first outlet; and iv) the second subchamber having a second inlet and a second outlet; c) a positive pressure reservior; d) a valve for controlling flow from the positive pressure reservoir through the first inlet, the valve operatively connected to the diaphragm, the diaphragm being moveable within the chamber in response to difference in pressure between the first subchamber and the second subchamber wherein movement of the diaphram controls movement of the valve; and e) the pump inlet in fluid communication with the first outlet and the pump outlet in fluid communication with the second inlet.