Patent ID: 6176694
Filing Date: 2001-01-23
Classification: F04C

Abstract:
A double screw rotor assembly comprising:a casing, said casing comprising an inside wall defining a compression chamber, an inlet port and an outlet port respectively disposed in communication with said compression chamber;two screw rotors mounted in the compression chamber inside said casing and meshed with each other, said screw rotors each comprising a spiral thread around the periphery, said thread having a addendum of thread defining an outside diameter and abutted against the inside wall of said casing, a dedendum of thread defining a root diameter which non-linearly and gradually increases in a direction from said inlet port toward said outlet port, and a thread height defined between said addendum of thread and said dedendum of thread; andat least one transfer chamber defined within said casing and surrounded by the inside wall of said casing and side walls and dedendum of the thread of each of said screw rotors, said at least one transfer chamber having a volume gradually reducing in direction from said inlet port toward said outlet port.