Patent ID: 6719547
Filing Date: 2004-04-13
Classification: F01C

Abstract:
A screw rotor device for positive displacement of a working fluid, comprising:a housing having an inlet port at a first end and an outlet port at a second end and a pair of cylindrical bores extending therebetween; a male rotor having at least one phase-offset helical thread, wherein said male rotor is rotatably mounted about a first axis extending between said first end and said second end of said housing, wherein a cross-section of said phase-offset helical thread, in any plane perpendicular to said first axis, comprises a tooth and a toothless sector, said tooth being subtended by a first arc angle with respect to said axis and said sector having a second arc angle proportionally greater than said first arc angle by a phase-offset multiplier, said tooth having a profile comprising a minor diameter arc and a tooth segment radially extending to a major diameter arc in close tolerance with said housing, and wherein said phase-offset multiplier is at least two for any cross-section taken in any said perpendicular plane; and a female rotor having at least one helical groove, wherein said female rotor is rotatably mounted about a second axis and counter-rotates with respect to said male rotor and has a periphery in close tolerance with said housing, and wherein said helical groove intermeshes with said helical thread.