Helically threaded intermeshing rotors

Claim 1

IN A COMPRESSOR OR SIMILAR DEVICE OF THE TYPE HAVING (A) A HOUSING WITH INTERSECTING CYLINDRICAL ROTOR CHAMBERS AND SUCTION AND DISCHARGE PORTS ARRANGED DIAGONALLY OPPOSITE EACH OTHER NEAR THE ENDS OF SAID HOUSING, AND (B) A PAIR OF COMPLEMENTARY HELICALLY THREADED ROTORS CONSISTING OF A MAIN ROTOR AND A GATE ROTOR EACH HAVING A PLURALITY OF THREADS WITH CREST EDGES AND TROUGHS, (C) SAID ROTORS BEING ROTATABLY SUPPORTED WITHIN THE CHAMBERS OF SAID HOUSING AND COOPERATING WITH EACH OTHER AND THE HOUSING TO FORM POCKETS AS THE SUCTION END OF THE ROTORS FOR RECEIVING FLUID THROUGH SAID SUCTION PORT, TO ADVANCE SAID POCKETS AND THE FLUID THEREIN AXIALLY ALONG THE ROTORS AND TO EXHAUST THE FLUID AT THE DISCHARGE END OF THE ROTORS THROUGH THE THE DISCHARGE PORT AS THE ROTORS REVOLVE ABOUT THE AXES THEREOF, (D) THE THREADS OF EACH ROTOR HAVING SEALING ENGAGEMENT WITH THE TROUGHS OF THE MATING ROTOR THROUGHOUT THE LENGTHS OF THE ROTORS, AND ALSO HAVING SEALING ENGAGEMENT WITH THE HOUSING THROUGHOUT AT LEAST THOSE PORTIONS OF THE LENGTHS OF THE THREADS WHICH EXTEND BETWEEN THE SUCTION PORT AND THE DISCHARGE PORT, AND (E) THE THREADS OF THE MAIN ROTOR LYING SUBSTANTIALLY OUTSIDE THE PITCH CIRCLE THEREOF AND THE THREADS OF THE GATE ROTOR LYING SUBSTANTIALLY INSIDE THE PITCH CIRCLE THEREOF; THE IMPROVEMENT WHICH COMPRISES: (1) EACH OF SAID ROTORS HAVING AXIALLY EXTENDING COMPRESSION AND DISCHARGE AREAS WHEREIN THE ROTOR THREADS ARE OF DIFFERENT SHAPES, THE COMPRESSION AREAS EXTENDING FROM THE SUCTION ENDS OF THE ROTORS TO THE LEADING EDGE OF THE DISCHARGE PORT AND THE DISCHARGE AREAS EXTENDING FROM SAID EDGE TO THE DISCHARGE ENDS OF THE ROTORS, (2) THE THREADS OF THE MAIN ROTOR HAVING LANDS AT THE TIPS THEREOF OF SUBSTANTIALLY UNIFORM WIDTH AND BEING OF GENERATED FORM SUBSTANTIALLY FROM TIP TO ROOT THEREOF THROUGHOUT THE AXIAL LENGTH OF THE COMPRESSION AREA AND HAVING ARCUATE TIPS IN THE DISCHARGE AREA WHICH GRADUALLY INCREASE IN ARCUATE WIDTH TOWARD THE DISCHARGE END OF THE ROTOR, THE FLANKS OF THE THREADS IN THE DISCHARGE AREA BETWEEN THE ARCUATE TIPS AND THE ROOTS THEREOF BEING OF GENERATED FORM, THE GENERATED PORTIONS OF THE MAIN ROTOR THREADS BEING GENERATED BY THE CREST EDGES OF THE GATE ROTOR THREADS AND THE ARCUATE TIPS OF THE MAIN ROTOR THREADS HAVING THEIR CENTERS OF CURVATURE SUBSTANTIALLY ON THE PITCH CIRCLE OF SAID THREADS MIDWAY BETWEEN THE SIDES OF THE THREADS, AND (3) THE THREADS OF THE GATE ROTOR BEING COMPLEMENTARY TO THOSE OF THE MAIN ROTOR, (4) WHEREBY THE THREADS OF THE MAIN AND GATE ROTORS COOPERATE TO FORM AN UNBROKEN SEAL THROUGHOUT THE COMPRESSION AREAS, FORM PROPER SEALS THROUGH THE DISCHARGE AREA, AND DO NOT FORM CLOSED POCKETS AT THE DISCHARGE ENDS OF THE ROTORS.