초록 ▼

A shaft oil purge system comprises an entrance seal, an exit seal and a buffer air flow. The entrance seal comprises a circumferential carbon seal running on an inner shaft and another carbon seal running on an outer shaft. The exit seal comprises a labyrinth seal positioned on the inner shaft and t

A shaft oil purge system comprises an entrance seal, an exit seal and a buffer air flow. The entrance seal comprises a circumferential carbon seal running on an inner shaft and another carbon seal running on an outer shaft. The exit seal comprises a labyrinth seal positioned on the inner shaft and towards the exit end of the annulus between the shafts. An abradable material filled groove positioned radially outward from the exit seal allows the inner shaft to rub without compromising the integrity of the outer shaft. The buffer air flow enters the annulus from a cavity at the entrance seal, purges oil from the annulus and improves the efficiency of the seals.

대표청구항 ▼

We claim: 1. An assembly for a cavity between an inner shaft and an outer shaft comprising: an entrance seal positioned towards the forward end of said cavity, said entrance seal including two circumferential carbon seals wherein one said circumferential carbon seal runs on an outer diameter of sai

We claim: 1. An assembly for a cavity between an inner shaft and an outer shaft comprising: an entrance seal positioned towards the forward end of said cavity, said entrance seal including two circumferential carbon seals wherein one said circumferential carbon seal runs on an outer diameter of said inner shaft and one said circumferential carbon seal runs on an outer diameter of said outer shaft; and a buffer air flow fed into said entrance seal. 2. The assembly of claim 1, further comprising an exit seal positioned towards an aft end of said cavity. 3. The assembly of claim 2, wherein said exit seal comprises a labyrinth seal. 4. The assembly of claim 2, wherein said exit seal is positioned on said inner shaft. 5. The assembly of claim 1, further comprising a groove positioned towards an aft end of said cavity. 6. The assembly of claim 5, wherein said groove is positioned on said outer shaft. 7. The assembly of claim 5, wherein said groove is filled with an abradable material. 8. The assembly of claim 1, wherein said entrance seal has an initial built radial clearance of less than about 0.0005 inches. 9. The assembly for an annulus between an inner shaft and an outer shaft comprising: a first circumferential carbon seal running on an outer diameter of said inner shaft; a second circumferential carbon seal running on an outer diameter of said outer shaft; a labyrinth seal positioned towards an aft end of said annulus; and a buffer air flow fed into a cavity between said first circumferential carbon seal and said second circumferential carbon seal. 10. The assembly of claim 9, wherein said buffer air flow comprises an external air flow. 11. The assembly of claim 9, wherein said buffer air flow comprises an engine air flow. 12. The assembly of claim 9, wherein an outer seal interface between said second circumferential carbon seal and said outer shaft has a coating material. 13. The assembly of claim 9, wherein said labyrinth seal has an initial built radial clearance of between about 0.002 inches and about 0.020 inches. 14. The assembly of claim 9, wherein said labyrinth seal is positioned on said inner shaft and further comprising a groove filled with an abradable material positioned on said outer shaft and radially outward from said labyrinth seal. 15. The assembly of claim 14, wherein said abradable material comprises a silver material. 16. The assembly of claim 14, wherein said abradable material comprises a silver material. 17. The assembly for an aircraft engine comprising: an inner shaft seal running on an outer diameter of a low pressure turbine shaft of said aircraft engine; an outer shaft seal running on an outer diameter of a high pressure turbine shaft of said aircraft engine; an exit seal positioned towards an aft end of an annulus between said high pressure turbine shaft and said low pressure turbine shaft, said exit seal positioned on said low pressure turbine shaft; an abradable material filled groove positioned on said high pressure turbine shaft and radially outward from said exit seal; and a buffer air flow fed into a cavity between said inner shaft seal and said outer shaft seal. 18. The assembly of claim 17, wherein said inner shaft seal comprises a circumferential carbon seal. 19. The assembly of claim 17, wherein said inner shaft seal runs on an inner shaft runner mounted on said low pressure turbine shaft. 20. The assembly of claim 19, wherein an inner seal interface between said inner shaft seal and said inner shaft runner has a coating material. 21. The assembly of claim 20, wherein said coating material comprises chrome. 22. The assembly of claim 17, wherein said inner shaft seal and said outer shaft seal are mounted on a bearing support housing of said aircraft engine. 23. The assembly of claim 17, wherein said inner shaft seal and said outer shaft seal have an initial built radial clearance of less than about 0.005 inches. 24. An assembly for sealing a forward end of an annulus between an inner shaft and an outer shaft comprising: an inner shaft seal running on an outer diameter of said inner shaft; an outer shaft seal running on an outer diameter of said outer shaft; and a buffer air flow fed into a cavity between said inner shaft seal and said outer shaft seal. 25. The assembly of claim 24, wherein said inner shaft seal and said outer shaft seal each comprise a circumferential carbon seal. 26. The assembly of claim 24, wherein said inner shaft seal has an initial built radial clearance of less than about 0.005 inches. 27. The assembly of claim 24, wherein said buffer air flow comprises an engine air flow. 28. An assembly for an annulus between an inner shaft and an outer shaft comprising: an entrance seal having a first circumferential carbon seal and a second circumferential carbon seal, said entrance seal having an initial built radial clearance of less than about 0.005 inches, said first circumferential carbon seal running on an outer diameter of said inner shaft and positioned towards a forward end of said annulus, said second circumferential carbon seal running on an outer diameter of said outer shaft and positioned towards said forward end; a labyrinth seal positioned on said outer diameter of said inner shaft and towards an aft end of said annulus, said labyrinth seal having an initial built radial clearance of between about 0.002 inches and about 0.020 inches; a groove positioned on said inner diameter of said outer shaft and radially outward from said labyrinth seal, said groove filled with a silver material having a radial thickness of between about 0.005 inches and about 0.040 inches; and a buffer air flow fed into a cavity between said first circumferential carbon seal and said second circumferential carbon seal. 29. A method of purging oil from an annulus between an inner and an outer shaft comprising the steps of: feeding a buffer airflow into a cavity at an entrance seal of said annulus, wherein said entrance seal comprises two circumferential carbon seals wherein one said circumferential carbon seal runs on an outer diameter of said inner shaft and one said circumferential carbon seal runs on an outer diameter of said outer shaft; and restricting the buffer air flow at the exit end of said annulus. 30. The method of claim 29, wherein said step of feeding the buffer air flow comprises feeding an external air flow between said two circumferential carbon seals. 31. The method of claim 29, wherein said step of feeding the buffer air flow comprises feeding an engine air flow. 32. The method of claim 29, wherein said step of restricting the buffer air flow comprises forcing the buffer air flow through a labyrinth seal positioned on the outer diameter of said inner shaft. 33. The method of claim 29, wherein said step of restricting the buffer air flow comprises forcing the buffer air flow between an exit seal on said inner shaft and an abradable material filled groove on said outer shaft.