High pressure seal vent

• US 9,022,760 B2
• Filed: 11/02/2011
• Issued: 05/05/2015
• Est. Priority Date: 11/02/2011
• Status: Active Grant

• Current Assignee: Trane International Inc. (Trane Technologies plc)
• Original Assignee: Trane International Inc. (Trane Technologies plc)
• Inventors: Bakkestuen, Robert S., Johnson, Jay H.
• Primary Examiner(s): Trieu, Thai Ba
• Assistant Examiner(s): Singh, Dapinder
• Application Number:
  US13/287,673
• Publication Number:
  US 20130108495A1
• Time in Patent Office: 1,280 Days
• Field of Search: 418/79, 418/84, 418/88, 418/98, 418/104, 418/194, 418/201.1, 418/202, 418/205, 417/423.13, 623/234, 624/02
• US Class Current: 418/104
• 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 23/008 Hermetic pumps
• CPC Class Codes: F04C 27/009 Shaft sealings specially adapted for pumps
• CPC Class Codes: F04C 29/0028 Internal leakage control
• CPC Class Codes: G01F 1/34 by measuring pressure or differential pressure

Abstract

A compressor for compressing refrigerant in a refrigerant circuit includes a housing defining a compression chamber. A screw rotor is mounted within the housing and configured to form a pocket of high pressure refrigerant and a pocket of low pressure refrigerant within the compression chamber. The screw rotor has a rotor shaft rotating about an axis. A bearing cavity includes at least one bearing rotatably supporting the rotor shaft. A partition through which the rotor shaft extends separates the bearing cavity from the compression chamber. A contacting seal is sealingly engaged with the rotor shaft and disposed in the bearing cavity proximate the partition. A passage has an opening adjacent the rotor shaft between the contacting seal and the compression chamber and in fluid communication with the pocket of low pressure refrigerant.

Claims

1. A compressor for compressing refrigerant in a refrigerant circuit, the compressor comprising:

a housing defining a compression chamber;

a screw rotor mounted within the housing and configured to form a pocket of high pressure refrigerant and a pocket of low pressure refrigerant within the compression chamber, the screw rotor having a rotor shaft rotating about an axis;

a bearing cavity including at least one bearing rotatably supporting the rotor shaft;

a partition separating the bearing cavity from the compression chamber and through which the rotor shaft extends;

a refrigerant leakage path disposed between the pocket of high pressure refrigerant and the at least one bearing;

a contacting seal sealingly engaged with the rotor shaft and disposed in the bearing cavity proximate the partition, the contacting seal is disposed between the at least one bearing and the refrigerant leakage path, the contacting seal defining a high seal side pressure region and a low seal side pressure region, wherein the at least one bearing is disposed on one side of the contacting seal having the low seal side pressure region, and the refrigerant leakage path is disposed on another side of the contacting seal having the high seal side pressure region; and

a passage having an opening directly adjacent the compression chamber at the rotor shaft between the contacting seal and the compression chamber and in fluid communication with the refrigerant leakage path and the pocket of low pressure refrigerant.

2. The compressor of claim 1, wherein the contacting seal is a contacting lip seal.

3. The compressor of claim 1, wherein a portion of the passage is external to the housing.

4. The compressor of claim 3, wherein the compression chamber has an axial length, and wherein the passage discharges into the compression chamber at a location along the axial length.

5. The compressor of claim 1, wherein the passage is internal to the housing.

6. The compressor of claim 5, wherein the passage discharges in a direction substantially parallel to the axis into the pocket of low pressure refrigerant.

7. The compressor of claim 5, wherein the passage discharges into the pocket of low pressure refrigerant at an angle to the axis, wherein the angle ranges from about 10°

to about 70°

.

8. The compressor of claim 7, wherein the angle is about 49°

.

9. The compressor of claim 5, wherein the compression chamber has an axial length, and wherein the passage discharges into the compression chamber at a location along the axial length.

10. A compressor for compressing refrigerant in a refrigerant circuit, the compressor comprising:

a housing defining a compression chamber;

a pair of intermeshing screw rotors mounted within the housing and configured to form a plurality of pockets, each pocket having a range of operable refrigerant pressure less than a compressor discharge pressure at a compressor discharge, one of the pair of intermeshing screw rotors having a rotor shaft rotating about an axis;

a bearing cavity including at least one bearing rotatably supporting the rotor shaft;

a partition separating the bearing cavity from the compression chamber and through which the rotor shaft extends, wherein a refrigerant leakage path is formed fluidly connecting the compression chamber to the bearing cavity;

a contacting seal sealingly engaged with the rotor shaft and disposed in the bearing cavity adjacent the refrigerant leakage path, the refrigerant leakage path is disposed between the at least one bearing and at least one of the plurality of pockets,

the contacting seal disposed between the at least one bearing and the refrigerant leakage path, the contacting seal defining a high seal side pressure region and a low seal side pressure region, wherein the at least one bearing is disposed on one side of the contacting seal having the low seal side pressure region, and the refrigerant leakage path is disposed on another side of the contacting seal having the high seal side pressure region; and

a passage having an opening directly adjacent the refrigerant leakage path at the rotor shaft between the contacting seal and the refrigerant leakage path and in fluid communication with the refrigerant leakage path and at least one of the plurality of pockets.

11. A method of reducing the wear rate of a shaft seal, the shaft seal sealingly engaged with a rotor shaft of a screw rotor that rotates about an axis and that is mounted within a compression chamber of a rotor housing, the shaft seal disposed in a bearing cavity directly proximate a partition separating the bearing cavity from the compression chamber and through which the rotor shaft extends, the method comprising:

operating the screw rotor to produce a pocket of high pressure refrigerant and a pocket of low pressure refrigerant within the compression chamber; and

passing a volume of high pressure refrigerant from an area directly adjacent the compression chamber at the rotor shaft between the shaft seal and the compression chamber to the pocket of low pressure refrigerant,

the passing a volume of high pressure refrigerant includes passing refrigerant from a refrigerant leakage path to the pocket of low pressure refrigerant, wherein the refrigerant leakage path fluidly connects the compression chamber to the bearing cavity and is disposed between at least one bearing and the pocket of high pressure refrigerant, where a contacting seal is sealingly engaged with the rotor shaft and is disposed in the bearing cavity adjacent the refrigerant leakage path,

the passing a volume of high pressure refrigerant includes passing refrigerant over the contacting seal, wherein the contacting seal is disposed between the at least one bearing and the refrigerant leakage path, the contacting seal defining a high seal side pressure region and a low seal side pressure region, wherein the at least one bearing is disposed on one side of the contacting seal having the low seal side pressure region, and the refrigerant leakage path is disposed on another side of the contacting seal having the high seal side pressure region.

12. The method of claim 11, wherein the compression chamber has an axial length, and wherein passing a volume of high pressure refrigerant includes discharging the refrigerant at a location along the axial length.

13. The method of claim 11, wherein passing a volume of high pressure refrigerant includes passing the refrigerant to the exterior of the housing.

14. The method of claim 13, wherein the compression chamber has an axial length, and wherein passing a volume of high pressure refrigerant includes discharging the refrigerant at a location along the axial length.

15. The method of claim 11, wherein passing a volume of high pressure refrigerant includes discharging the refrigerant in a direction substantially parallel to the axis into the pocket of low pressure refrigerant.

16. The method of claim 11, wherein passing a volume of high pressure refrigerant includes discharging the refrigerant at an angle to the axis into the pocket of low pressure refrigerant.

17. The method of claim 16, wherein the angle ranges from about 10°

to about 70°

.

18. The method of claim 17, wherein the angle is about 49°

.

19. A method of determining the optimum position of a vent to maximize the adiabatic efficiency of a compressor, the compressor including a shaft seal sealingly engaged with a rotor shaft of a screw rotor that is mounted within a compression chamber, the shaft seal disposed in a bearing cavity directly proximate a partition separating the bearing cavity from the compression chamber and through which the rotor shaft extends, a refrigerant leakage path is formed fluidly connecting the compression chamber to the bearing cavity, the shaft seal is sealingly engaged with the rotor shaft and disposed in the bearing cavity adjacent the refrigerant leakage path, the refrigerant leakage path is disposed between at least one bearing and at least one pocket of the compression chamber, the shaft seal is disposed between the at least one bearing and the refrigerant leakage path, the shaft seal defining a high seal side pressure region and a low seal side pressure region, wherein the at least one bearing is disposed on one side of the shaft seal having the low seal side pressure region, and the refrigerant leakage path is disposed on another side of the shaft seal having the high seal side pressure region, the method comprising:

locating an opening of a first vent adjacent the rotor shaft between the shaft seal and the compression chamber;

locating a discharge of the first vent in fluid communication with a first operable pocket of low pressure refrigerant;

operating the screw rotor to create a pocket of high pressure refrigerant and the first pocket of low pressure refrigerant;

measuring a power consumed and an overall refrigerant flow rate produced by the compressor during operation;

locating an opening of a substituted second vent adjacent the rotor shaft between the shaft seal and the compression chamber;

locating a discharge of the second vent in fluid communication with a second operable pocket of low pressure refrigerant;

operating the screw rotor to create a pocket of high pressure refrigerant and the second pocket of low pressure refrigerant;

measuring a subsequent power consumed and a subsequent overall refrigerant flow rate produced by the compressor during operation; and

determining the position of the vent for the compressor by evaluating compressor operation results having the first vent and compressor operation results having the substituted second vent.

20. A method of determining the optimum internal dimensions of a vent to maximize the adiabatic efficiency of a compressor, the compressor including a shaft seal sealingly engaged with a rotor shaft of a screw rotor that is mounted within a compression chamber, the shaft seal disposed in a bearing cavity directly proximate a partition separating the bearing cavity from the compression chamber and through which the rotor shaft extends, a refrigerant leakage path is formed fluidly connecting the compression chamber to the bearing cavity, the shaft seal is sealingly engaged with the rotor shaft and disposed in the bearing cavity adjacent the refrigerant leakage path, the refrigerant leakage path is disposed between at least one bearing and at least one pocket of the compression chamber, the shaft seal is disposed between the at least one bearing and the refrigerant leakage path, the shaft seal defining a high seal side pressure region and a low seal side pressure region, wherein the at least one bearing is disposed on one side of the shaft seal having the low seal side pressure region, and the refrigerant leakage path is disposed on another side of the shaft seal having the high seal side pressure region, the method comprising:

locating a first-sized vent between

     1) a region adjacent the rotor shaft between the shaft seal and the compression chamber and

     2) an operable pocket of low pressure refrigerant;

operating the screw rotor to create a pocket of high pressure refrigerant and the pocket of low pressure refrigerant;

measuring a power consumed and an overall refrigerant flow rate produced by the compressor during operation;

locating a substituted second-sized vent between the region and the operable pocket of low pressure refrigerant;

operating the screw rotor to create a pocket of high pressure refrigerant and the pocket of low pressure refrigerant;

measuring a subsequent power consumed and a subsequent overall refrigerant flow rate produced by the compressor during operation; and

determining the internal dimension of the vent for the compressor by evaluating compressor operation results having the first-sized vent and compressor operation results having the substituted second-sized vent.