Piston diaphragm pump

Claim 1

A PUMP COMPRISING A HOUSING MEMBER DEFINING A FLUID CAVITY AND A CYLINDER BORE, A PISTON IN SAID CYLINDER BORE, DRIVE MEANS TO RECIPROCATE SAID PISTON, A HEAD MEMBER SECURED TO SAID HOUSING DEFINING A DIAPHRAGM CAVITY AT THE OUTER END OF SAID CYLINDER BORE, A DIAPHRAGM SEPARATING SAID DIAPHRAGM CAVITY INTO WORKING CHAMBER OPENING TO SAID CYLINDER BORE AND A PUMPING CHAMBER, SAID DIAPHRAGM BEING OF A LAMINATED CONSTRUCTION HAVING A FIRST LAYER OF RESILIENT ELASTOMERIC MATERIAL AND A SECOND LAYER OF A HIGHLY CHEMICALLY RESISTANT MATERIAL EXPOSED TO THE FLUID IN THE PUMP CHAMBER, SAID DIAPHRAGM HAVING A RELATIVELY STIFF REINFORCING DISC DISPOSED BETWEEN SAID FIRST AND SECOND LAYERS, SAID DISC HAVING AN OUTER DIAMETER SUBSTANTIALLY AT LEAST AS GREAT AS THE DIAMETER OF SAID PUMPING CHAMBER, MOUNTING MEANS SECURING THE OUTER PERIPHERY OF SAID DIAPHRAGM TO ONE OF SAID MEMBERS INCLUDING A PAIR OF OPPOSED CLAMPING FACES, ONE OF SAID CLAMPING FACES HAVING A ROUNDED ANNULAR PROTUBERANCE ADJACENT ITS INNER PERIPHERY EXTENDING AXIALLY BEYOND SAID CLAMPING FACE AND THE OTHER OF SAID CLAMPING FACES HAVING A RECESSED SURFACE ADJACENT ITS INNER PERIPHERY OPPOSITE SAID PROTUBERANCE, SAID MOUNTING MEANS BEING SO CONSTRUCTED AND ARRANGED THAT WHEN SAID DIAPHRAGM IS CLAMPED BETWEEN SAID CLAMPING FACES SAID PROTUBERANCE AND SAID RECESSED SURFACE ARE AXIALLY SEPARATED FROM ONE ANOTHER BY A LEAST SUBSTANTIALLY THE THICKNESS OF SAID DIAPHRAGM, SAID PROTUBERANCE AXIALLY OF SETTING THE UNCLAMPED FROM THE CLAMPED PORTIONS OF SAID DIAPHRAGM AND THEREBY PRESTRESSING THE UNCLAMPED PORTION, INLET AND OUTLET PORTS OPENING INTO SAID PUMPING CHAMBER, AND VALVE MEANS IN SAID INLET AND OUTLET PORTS, WHEREBY RECIPROCATING OF SAID PISTON ACTS UPON FLUID WITHIN SAID WORKING CHAMBER AND IMPARTS OSCILLATION TO SAID DIAPHRAGM TO DRAW FLUID INTO AND FORCE FLUID OUT OF SAID PUMPING CHAMBER.