Contaminant separating fuel pump

Claim 1

IN A LIQUID FUEL PUMPING UNIT FOR AN AIRCRAFT ENGINE COMPRISING A CENTRIFUGAL BOOST PUMP AND A POSITIVE DISPLACEMENT PUMP, CONNECTED IN FLOW SERIES, BETWEEN A SOURCE OF FUEL AND THE ENGINE; MEANS FOR REMOVING SOLID PARTICLES OF CONTAMINANTS FROM THE PUMPED FUEL, DURING ITS FLOW THROUGH SAID PUMPING UNIT, COMPRISING: A HOLLOW, FRUSTO-CONICAL, BOOST PUMP IMPELLER HAVING ON ITS CONICAL WALL A PLURALITY OF HELICAL VANES WHOSE OUTER ENDS ARE IN CLOSELY-SPACED RELATION TO A MATING FRUSTO-CONICAL HOUSING ENCLOSING SAID IMPELLER, WHEREBY SAID VANES AND HOUSING DEFINE A PLURALITY OF HELICAL CHANNELS EXTENDING FROM THE INLET TO THE OUTLET THROUGH WHICH THE PUMPED FUELS FLOWS FROM A CENTRAL AXIAL INLET TO A PERIPHERAL CIRCULAR OUTLET OF SAID BOOST PUMP; DRIVING MEANS CONNECTING SAID IMPELLER WITH THE ENGINE SO THAT SAID IMPELLER IS ROTATED AT A SPEED PROPORTIONAL TO THAT OF THE ENGINE; THEREBY CREATING A CENTRIFUGAL FORCE WHICH ACTS ON THE LIQUID IN SAID CHANNELS AND FORCES THE DENSER SOILD CONTAMINANT PARTICLES RADIALLY OUTWARD TOWARD SAID HOUSING AND DOWNWARDLY ALONG THE INNER SURFACE OF SAID HOUSING, SAID SOLID PARTICLES, DISPLACING AN EQUAL VOLUME OF LIQUID FUEL INWARDLY TOWARD THE AXIS OF ROTATION OF SAID IMPELLER; AN ANNULAR TRAPPING GROOVE IN SAID HOUSING, INWHICH SAID SOLID PARTICLES ARE TRAPPED AND SEPARATED FROM THE MAIN STREAM OF PUMPED FUEL; A BYPASS CONDUIT CONNECTING SAID TRAPPING GROOVE WITH THE INLET TO SAID BOOST PUMP, AND A FILTER IN SAID CONDUIT FOR REMOVING SOLID CONRAMINANT PARTICLES FROM THE FUEL FLOWING THROUGH BYPASS CONDUIT, WHEREBY THE FUEL RETURNED TO SAID INLET IS FREED OF SAID SOLID CONTAMINANTS, AND THE PERCENTAGE OF CONTAMINANTS IN THE WHOLE STREAM OF PUMPED FUEL IS SUBSTANTIALLY REDUCED.