Piston pump having rolling diaphragm

Claim 1

A RECIPROCATING SINGLE ACTION PISTON PUMP COMPRISING IN COMBINATION: (A) A CYLINDER BODY DEFINING A SUCTION INLET AND A PRESSURE OUTLET AND HAVING A BOTTOM SURFACE; (B) A RECIPROCATING PISTON ARRANGED INSIDE SAID CYLINDER BODY AND HAVING A BOTTOM SURFACE JUXTAPOSED TO SAID BOTTOM SURFACE OF SAID CYLINDER BODY; (C) A ROLLING DIAPHRAGM HAVING A RADIALLY OUTER PORTION SECURED TO SAID CYLINDER BODY, AN INTERMEDIATE ROLLING WALL AND A RADIALLY INNER PORTION SECURED TO SAID PISTON AND SUBDIVIDING THE INTERIOR OF SAID CYLINDER BODY INTO A PUMP CHAMBER AND AN INACTIVE CHAMBER; (D) MEANS FOR EXHAUSTING TO THE OUTER ATMOSPHERE AIR CONTAINED IN SAID INACTIVE CHAMBER DURING THE SUCTION STROKE OF SAID PISTON WITHOUT AN AUXILIARY VACUUM PUMP, SAID EXHAUSTING MEANS INCLUDING MEANS FOR MINIMIZING THE CLEARANCE BETWEEN SAID BOTTOM SURFACE OF SAID CYLINDER BODY AND SAID BOTTOM SURFACE OF SAID PISTON; AND (E) MEANS EFFECTIVE DURING A PREPONDERANT PORTION OF THE COMPRESSION STROKE OF SAID PISTON FOR PRECLUDING THE BACKFLOW OF AIR FROM THE OUTER ATMOSPHERE INTO SAID INACTIVE CHAMBER.