Patent ID: 6200116
Filing Date: 2001-03-13
Classification: F01C,F04C

Abstract:
A vacuum pump comprising:a pump body having a screw mechanism section comprising two externally threaded rotors mounted on respective shafts and adapted for counter-rotation in a first chamber within the pump body with intermeshing of the rotor threads to pump gas from a pump inlet by action of the two externally threaded rotors;each of the two externally threaded rotors having a root diameter increasing and a thread diameter decreasing in a direction from pump inlet and in which the gas is pumped;the two externally threaded rotors having cavities sealed at ends of the two externally threaded rotors located situated closest to the inlet of the pump; andshaft bearings to position the two externally threaded rotors in the pump body, the shaft bearings located inside the cavities in the rotors.