Hermetic rotary helical screw compressor with improved oil management

Claim 1

A hermetic rotary helical screw compressor comprising: a closed, vertically oriented generally cylindrical outer enclosure, an inner cylindrical housing concentrically fixed within said outer enclosure and forming with said outer enclosure a first sealed chamber therebetween, said inner housing including an upper compressor discharge housing fluid sealed from and overlying a lower compressor inlet housing, said upper compressor discharge housing forming a second chamber, and said lower compressor inlet housing forming a third chamber sealed from said first and second chambers, a compressor inlet tube extending inwardly through said outer enclosure wall and through said lower compressor inlet housing and opening up into said third chamber, intermeshed helical screw rotors rotatably supported within said lower compressor housing and in fluid communication with said inlet tube for compressing a working fluid supplied to said inlet tube, a compressor discharge passage fluid connecting the upper end of said first chamber to the lower end of said second chamber, an electric drive motor coaxially supported within said upper compressor discharge housing above said compressor discharge passage, and including a fixed stator and a concentric rotor rotatably positioned within the same, a qUantity of oil provided within said outer enclosure with the bottom of said outer enclosure forming an oil sump, an oil pump within said outer enclosure in fluid communication with said sump, means for delivering oil under pressure from said pump to said screw compressor screw rotors for lubrication and mixing with said compressor working fluid passing therethrough, a first axial fluid passage means within said motor for passing compressed working fluid and entrained oil axially upward to cool the motor and for impingement against the upper end of compressor discharge housing, second axial fluid passage means within said motor for passing said compressor discharge and entrained oil axially downward to further cool said motor, and radial passage means fluid connected to the second axial passage means for directing the compressed working fluid and the entrained oil radially outwards of said upper compressor discharge housing and into said first chamber for gravity separation of said oil from said compressed working fluid and return to said sump.