Positive displacement pump

Claim 1

AN IMPROVED POSITIVE DISPLACEMENT PUMP FOR PUMPING FLUIDS, SAID PUMP COMPRISING THE COMBINATION OF A HOUSING INCLUDING AN ENTRANCE PORT FOR RECEIVING THE FLUID TO BE PUMPED AND AN EXIT PORT FOR DISCHARGING THE FLUID, A PISTON MOUNTED WITHIN SAID HOUSING FOR MOVEMENT BETWEEN SAID ENTRANCE AND EXIT PORTS AND INCLUDING A LONGITUDINAL PASSAGEWAY EXTENDING BETWEEN OPPOSITE ENDS OF THE PISTON, SAID PISTON ALSO INCLUDING A FIRST PERIPHERAL GROOVE AND COOPERATING FIRST RADIAL PASSAGEWAY FOR PROVIDING FLUID COMMUNICATION BETWEEN SAID ENTRANCE PORT AND SAID LONGITUDINAL PASSAGEWAY WHEN THE PISTON IS IN A FIRST POSITION, AND A SECOND PERIPHERAL GROOVE AND COOPERATING SECOND RADIAL PASSAGEWAY FOR PROVIDING FLUID COMMUNICATION BETWEEN SAID LONGITUDINAL PASSAGEWAY AND SAID EXIT PORT WHEN THE PISTON IS IN A SECOND POSITION, SAID PUMP HOUSING FORMING A PUMP CHAMBER ADJACENT ONE END OF SAID PISTON IN FLUID COMMUNICATION WITH SAID LONGITUDINAL PASSAGEWAY, A DIAPHRAGM MEMBER FORMING A FLUID CHAMBER ADJACENT THE OTHER END OF SAID PISTON AND IN FLUID COMMUNICATION WITH SAID LONGITUDINAL PASSAGEWAY, DRIVING MEANS FOR PERIODICALLY DRIVING SAID PISTON FROM SAID FIRST POSITION TO SAID SECOND POSITION SO AS TO REDUCE THE VOLUME OF SAID PUMP CHAMBER AND THEREBY INCREASE THE FLUID PRESSURE IN THE CHAMBER FORMED BY SAID DIAPHRAGM SO THAT THE DIAPHRAGM DISCHARGES FLUID THROUGH SAID PASSAGEWAY AND SAID EXIT PORTS WHEN THE PISTON IS IN SAID SECOND POSITION, AND MEANS FOR RETURNING THE PISTON FROM SAID SECOND POSITION TO SAID FIRST POSITION BETWEEN THE SUCCESSIVE FLUID DISCHARGES EFFECTED BY SAID DIAPHRAGM MEMBER.