Patent ID: 7008201

Claim:
A screw rotor device for positive displacement of a working fluid, comprising: a female rotor comprising a major diameter and a helical groove receding from said major diameter, said helical groove comprising a bottom land situated between a leading side and a trailing side, said leading side and said trailing side respectively comprising a leading ridge and a trailing ridge at said major diameter; a male rotor comprising a minor diameter and a helical thread extending from said minor diameter and rotatably intermeshing in phase with said helical groove, said helical thread comprising a top land situated between a leading face and a trailing face, said leading face and said trailing face comprising a leading edge and a trailing edge, respectively, wherein said top land is in a first sealing relationship with said bottom land, wherein said trailing face is in a second sealing relationship with said trailing ridge, wherein said trailing edge is in a third sealing relationship with said trailing side, and wherein a cross-sectional profile of said helical thread is comprised of a top land line between a leading line and a trailing line, said leading line and said trailing line being selected from a group consisting of a concave line, a straight line, a convex line, and any combination thereof; and a housing enclosing said female rotor and said male rotor, said housing comprising a front side, a back side, a first end, a second end, an inlet port, an outlet port, and a pair of cylindrical bores extending between said first end and said second end along a length of said front side and said back side, said pair of cylindrical bores comprising a front cusp extending along said length of said front side and a back cusp extending along said length of said back side of said housing, wherein said third sealing relationship extends continuously along said trailing side of said female rotor from said front cusp to said bottom land, said front cusp being in close tolerance with said major diameter of said female rotor.