Pump for semi-fluid materials

Claim 1

IN A POSITIVE DISPLACEMENT PUMP OF THE TYPE HAVING A PAIR OF PUMP CYLINDERS OPEN AT ONE END TO PROVIDE FOR INDUCTION OF MATERIAL TO BE PUMPED INTO THE CYLINDERS DURING THE RETRACTION STROKES OF THEIR PISTONS AND TO PROVIDE FOR DISCHARGE OF THE MATERIAL FROM THE CYLINDERS DURING THE EXTENSION STROKES OF THEIR PISTONS, AND FURTHER HAVING MEANS TO DRIVE THE PISTONS BACK AND FORTH IN THEIR CYLINDERS IN OPPOSITE PHASE RELATIONSHIP: (A) FIXED WALL MEANS DEFINING A FEED CHAMBER HAVING (1) SPACED APART UPRIGHT FRONT AND REAR WALL PORTIONS CONNECTED BY BOTTOM AND SIDE WALL PORTIONS, (2) AN INLET WHICH OPENS INTO ITS UPPER PORTION OF ADMIT TO THE FEED CHAMBER MATERIAL TO BE PUMPED, (3) A DELIVERY PORT OPENING THROUGH SAID FRONT WALL PORTION, AND (4) A PAIR OF CYLINDER PORTS OPENING THROUGH SAID REAR WALL PORTION, ONE FOR EACH PUMP CYLINDER AND COMMUNICATING WITH THE OPEN END THEREOF; (B) A VALVE MOUNTED IN THE FEED CHAMBER FOR ROTARY MOTION ABOUT AN AXIS FIXED WITH RESPECT THERETO AND NORMAL TO SAID FRONT AND REAR WALL PORTIONS THEREOF, SAID VALVE EXTENDING SUBSTANTIALLY ENTIRELY ACROSS THE SPACE BETWEEN THE FRONT AND REAR WALL PORTIONS AND HAVING (1) A REAR PORTION OPERABLE UPON ROTARY MOVEMENT OF THE VALVE FROM ONE OPERATING POSITION THEREOF TO ANOTHER TO COVER AND CLOSE OFF FIRST ONE AND THEN THE OTHER OF THE CYLINDER PORTS FROM THE INTERIOR OF THE VALVE CHAMBER, (2) MEANS ON THE FRONT OF THE VALVE TO AT ALL TIMES CLOSE OFF THE DELIVERY PORT FROM THE INTERIOR OF THE VALVE CHAMBER, AND (3) PASSAGE MEANS EXTENDING FORE AND AFT THROUGH THE VALVE AND OPENING THROUGH SAID REAR PORTION THEREOF, TO COMMUNICATE THE DELIVERY PORT WITH WHICHEVER CYLINDER PORT IS COVERED BY SAID REAR PORTION OF THE VALVE; AND (C) MATING CURVED SURFACES ON THE UNDERSIDE OF THE VALVE AND THE BOTTOM PORTION OF THE CHAMBER, SAID SURFACES BEING CONCENTRIC TO THE VALVE AXIS AND BEING UNIFORMLY CONTIGUOUS THROUGHOUT AN ANGLE OF SUBSTANTIAL MAGNITUDE SO AS TO PRECLUDE SOLIDS IN THE MATERIAL CONTAINED IN THE VALVE CHAMBER FROM BECOMING WEDGED BETWEEN THE UNDERSIDE OF THE VALVE AND THE BOTTOM PORTION OF THE CHAMBER OR TENDING TO BUILD UP ON THE VALVE OR ITS CHAMBER DURING ROTARY MOTION OF THE VALVE FROM ONE OF ITS OPERATING POSITIONS TO ANOTHER, AND PREVENT THE ACCUMULATION OF MATERIAL ON ANY WALL PORTION OF THE FEED CHAMBER OR THE VALVE THAT WOULD TEND TO INTERFERE WITH SAID MOTION OF THE VALVE.