Closed loop compressed gas system with oil mist lubricated screw compressor

Claim 1

In a closed loop compressed gas system including a rotary helical screw compressor having a low pressure suction port and a high pressure discharge port and closed loop means connecting said hermetic helical screw compressor discharge and suction ports and for continuously circulating a working fluid in gaseous or vapor form between said ports by way of said closed loop means through said helical screw compressor by a pressure difference due to compression within said compressor, and wherein said compressor comprises: a hermetic housing, intersecting parallel bores within said hermetic housing, shaft borne helical screw rotors intermeshed and mounted within respective intersecting parallel bores for rotation about respective shaft axes, and defining with said housing bores a compression chamber and being open at one end to said loop means via said suction port and at the other end to said loop means via said discharge port, sealed antifirction bearing means borne by said housing for solely rotatably supporting the helical screw rotor shaft to opposite sides of said helical screw rotor and for solely taking up radial and axial thrust forces acting therein, and wherein said hermetic compressor housing and said helical screw rotor shafts define sealed chambers at respective ends of said helical screw rotors which bear antifriction bearing pack assemblies constituting said antifriction bearing means, the improvement wherein: said closed loop system includes within said closed loop means a working fluid in gaseous or vapor form bearing a petroleum based lubricant in oil mist form having a mass weight ratio with respect to said working fluid being approximately 0.25 to 12% by weight and wherein said compressor further comprises closed loop lubricating passage means including said compression chamber and said sealed chambers housing said antifriction bearing means, passage means connecting respective sealed chambers on opposite sides of said helical screw rotors bearing said antifriction bearing pack assemblies, and discrete gaps between said rotary shaft, said helical screw rotors and said compressor housing such that the miscible oil, in mist form, is carried by the working fluid moving continuously through the working chamber and the sealed chambers bearing the anti-friction bearing pack assemblies and said closed loop lubricating passage means by working fluid compression pressure differential to facilitate oil mist lubrication of respective bearing pack assemblies, thereby eliminating the need for an oil pump, an oil sump and an oil separator.