Hermetic rotary helical screw compressor with improved oil management

• US 3,922,114 A
• Filed: 07/19/1974
• Issued: 11/25/1975
• Est. Priority Date: 07/19/1974
• Status: Expired due to Term

• Current Assignee: Marshall Industries Inc.
• Original Assignee: Clark B. Hamilton, Donald D. Schaefer, Harold W. Moody Jr
• Inventors: Hamilton, Clark B., Moody, Harold W. Jr., Schaefer, Donald D.
• Primary Examiner(s): Husar, C. J.
• Assistant Examiner(s): Sessions, O. T.
• Application Number:
  US05/490,169
• Time in Patent Office: 494 Days
• Field of Search: 417/362,366,369,372,410,902 418/97,88 62/469 184/6.16,6.18
• US Class Current: 417/366
• CPC Class Codes: F04C 18/16 with helical teeth, e.g. chevron-shaped, screw type for non-parallel axes of movement F04C18/48
• CPC Class Codes: F04C 2240/51 for cantilever assemblies
• CPC Class Codes: F04C 23/008 Hermetic pumps
• CPC Class Codes: F04C 29/045 of the electric motor in hermetic pumps
• CPC Class Codes: Y10S 417/902 Hermetically sealed motor pump unit
• CPC Class Codes: Y10S 418/01 Non-working fluid separation

Abstract

A two part, inner, cylindrical housing concentrically carried within a sealed outer enclosure forms with the outer enclosure, a first sealed chamber and within itself, an upper chamber carrying the electric motor and a lower compressor inlet chamber in a vertical array. The compressor discharge gas, including entrained oil, passes through ducts within the motor to cool the motor with the swirling gas and entrained oil discharged against the upper end of the inner cylindrical housing to separate some of the oil from the discharge gas by centrifugal force. Axial ducts carried by the stator move the discharge gas downwardly to further cool the motor. Discharge gas nozzles fluid connected to the stator ducts discharge the gas and entrained oil against the inner wall of the outer enclosure and the oil drains to the bottom of the enclosure which forms an oil sump.

Claims

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.

2. The hermetic rotary helical screw compressor as claimed in claim 1, wherein:

said first axial passage means comprises ducts formed within said rotor extending upwardly from one end face to the other such that rotation of said rotor provides a swirling action to the compressed gas and the entrained oil such that some separation of oil from the gas occurs centrifugally by contact of the gas with the upper end of the compressor discharge housing.

3. The hermetic rotary helical screw compressor as claimed in claim 2, wherein:

said second axial passage means comprises ducts at least partially defined by said stator and extending downwardly from the upper end face of the stator but terminating short of the lower end face thereof.

4. The hermetic rotary helical screw compressor as claimed in claim 2, wherein:

said first fluid passage means further comprises the annular air gap between the concentrically positioned rotor and stator.

5. The hermetic rotaty helical screw compressor as claimed in claim 3, wherein:

said first fluid passage means further comprises the annular air gap between the concentrically positioned rotor and stator.

6. The hermetic rotary helical screw compressor as claimed in claim 3, wherein:

said radial passage means comprise a plurality of circumferentially spaced radial openings within said upper compressor discharge housing, intersecting said circumferentially spaced axial ducts within said stator.

7. The hermetic rotary helical screw compressor as claimed in claim 5, wherein:

said radial passage means comprise a plurality of circumferentially spaced radial openings within said upper compressor discharge housing, intersecting said circumferentially spaced axial ducts within said stator.

8. The hermetic rotary helical screw compressor as claimed in claim 6, wherein:

said radial opening means are canted to permit the gaseous compressor discharge working fluid and the entrained oil to be discharged generally tangential to the inner wall of the outer enclosure so as to sweep the inner sidewall of the enclosure circumferentially and to deposit the entrained oil thereon.

9. The hermetic rotary helical screw compressor as claimed in claim 6, wherein:

said radial passage means comprise a plurality of nozzles fluid coupled to the discharge sides of said radial opening within said compressor outlet housing with the discharge end of said nozzle opening into said first chamber so as to discharge compressed working fluid and entrained oil in a direction corresponding to the direction of rotation of said motor rotor.

10. The hermetic rotary helical screw compressor as claimed in claim 9, wherein said discharge gas nozzles comprise short elbow tubes having right angle portions including a first radial portion coaxial with the radial openings within the upper compressor discharge housing and secured to the outside of said housing in axial alignment with said openings, and a second Circumferential portion which extends generally tangential to the inner periphery of said upper compressor discharge housing and spaced therefrom.

11. The hermetic rotary helical screw compressor as claimed in claim 1, wherein:

said outer enclosure consists of upper and lower partially nested, enclosure sections which are welded circumferentially at their exterior juncture line to permit ready separation of the enclosure sections and access to the interior of the hermetic screw compressor.