Scroll machine with floating seal

Abstract

A scroll machine utilizing working fluid under pressure to enhance axial sealing, including several embodiments of a multi-function floating seal to isolate the axial biasing fluid, and provide vacuum protection and a degree of high pressure ratio protection.

We claim: 
     
       1. A scroll machine comprising: (a) a hermetic shell;   (b) an orbiting scroll member disposed in said shell and having a first spiral wrap on one face thereof;   (c) a non-orbiting scroll member disposed in said shell and having a second spiral wrap on one face thereof, said wraps being intermeshed with one another;   (d) means for causing said orbiting scroll member to orbit about an axis with respect to said non-orbiting scroll member whereby said wraps will create pockets of progressively changing volume between a suction pressure zone and a discharge pressure zone;   (e) means for mounting one of said scroll members for limited axial movement with respect to the other scroll member;   (f) means defining an annular cavity exposed to a surface of one of said scroll members which will cause pressurized fluid in said cavity to bias said one scroll member toward the other scroll member, said cavity having a radially inner wall surface and a radially outer wall surface;   (g) means defining a fluid leakage path between said cavity and the interior of said shell;   (h) means for supplying fluid under pressure to said cavity for biasing said scroll members axially together; and   (i) annular seal means disposed in said cavity, said seal means having first and second seals sealingly engaging said inner and outer wall surfaces, respectively, to isolate said pressurized fluid in said cavity from said leakage path and said discharge pressure zone.   
     
     
       2. A scroll machine as claimed in claim 1 wherein said inner and outer wall surfaces are cylindrical and coaxial. 
     
     
       3. A scroll machine as claimed in claim 1 wherein said machine is a compressor and said pressurized fluid is the working fluid being compressed from a suction pressure to a discharge pressure. 
     
     
       4. A scroll machine as claimed in claim 3 wherein said pressurized fluid is at a pressure intermediate said suction pressure and discharge pressure. 
     
     
       5. A scroll machine as claimed in claim 1 wherein said seal means floats axially in said cavity. 
     
     
       6. A scroll machine as claimed in claim 1 wherein said seal means is of sandwich construction comprising a first annular element and a second annular element, and wherein said first and second seals comprise generally flat inner and outer annular lip seals clamped between said elements. 
     
     
       7. A scroll machine as claimed in claim 6 wherein said inner and outer lip seals are integral with one another. 
     
     
       8. A scroll machine as claimed in claim 6 wherein said inner and outer lip seals are separate parts. 
     
     
       9. A scroll machine as claimed in claim 6 wherein said lip seals are formed of a filled PTFE material. 
     
     
       10. A scroll machine as claimed in claim 9 wherein said PTFE is filled with glass. 
     
     
       11. A scroll machine as claimed in claim 10 wherein said glass is approximately 5% by weight of the seal material. 
     
     
       12. A scroll machine as claimed in claim 9 wherein said PTFE is filled with MoS 2 . 
     
     
       13. A scroll machine as claimed in claim 12 wherein said MoS 2  is approximately 5% by weight of the seal material. 
     
     
       14. A scroll machine as claimed in claim 6 wherein said lip seals are planar in configuration when in an unstressed state. 
     
     
       15. A scroll machine as claimed in claim 6 wherein said lip seals each having a slightly conical exposed periphery when in an unstressed state. 
     
     
       16. A scroll machine as claimed in claim 15 wherein there are a plurality of inner and outer lip seals. 
     
     
       17. A scroll machine as claimed in claim 6 wherein there are a plurality of inner lip seals having an annular spacer element disposed therebetween. 
     
     
       18. A scroll machine as claimed in claim 17 wherein said spacer element is formed of a relatively rigid material having a plurality of ridges on the portions of its surface which engage said lip seals. 
     
     
       19. A scroll machine as claimed in claim 6 wherein said first element has a plurality of circumferentially spaced axially extending posts extending through said second element. 
     
     
       20. A scroll machine as claimed in claim 19 wherein the free ends of said posts are swedged to clamp said lip seals between said elements. 
     
     
       21. A scroll machine as claimed in claim 19 wherein said lip seals are integral with one another and said post extends therethrough. 
     
     
       22. A scroll machine as claimed in claim 19 wherein said inner and outer lip seals are separate parts and said posts extend therebetween. 
     
     
       23. A scroll machine as claimed in claim 6 wherein there are a plurality of inner lip seals. 
     
     
       24. A scroll machine as claimed in claim 6 wherein said seal means floats axially in said cavity. 
     
     
       25. A scroll machine as claimed in claim 1 wherein said one scroll member is said non-orbiting scroll member. 
     
     
       26. A scroll compressor comprising: (a) a hermetic shell;   (b) an orbiting scroll member disposed in said shell and having a first spiral wrap on one face thereof;   (c) a non-orbiting scroll member disposed in said shell and having a second spiral wrap on one face thereof, said wraps being intermeshed with one another;   (d) means for causing said orbiting scroll member to orbit about an axis with respect to said non-orbiting scroll member whereby said wraps will create pockets of progressively decreasing volume to compress a fluid from a suction pressure to a discharge pressure;   (e) means for mounting one of said scroll members for limited axial movement with respect to the other scroll member;   (f) means defining a cavity exposed to a surface of one of said scroll members which will cause pressurized fluid in said cavity to bias said one scroll member toward the other scroll member;   (g) means defining a first fluid leakage path between said cavity and a zone in said shell at suction pressure;   (h) means defining a second fluid leakage path between said cavity and a zone in said shell at discharge pressure;   (i) means for supplying fluid to said cavity at a pressure intermediate said suction and discharge pressures for biasing said scroll members axially together; and   (j) seal means disposed in said cavity, said seal means having . .three seals, said.!. .Iadd.a .Iaddend.first seal isolating said pressurized fluid in said cavity from said first leakage path, . .said.!. .Iadd.a .Iaddend.second seal isolating said cavity from said second leakage path, and . .said.!. .Iadd.a .Iaddend.third seal . .isolating.!. .Iadd.engaging a different component of said compressor to isolate .Iaddend.fluid at suction pressure from fluid at discharge pressure across a face of said seal means.   
     
     
       27. A scroll machine as claimed in claim 26 wherein said seal means floats axially in said cavity with said first and second seals remaining effective. 
     
     
       28. A scroIl machine as claimed in claim 26 wherein said seal means is of sandwich construction comprising a first annular element and a second annular element, and wherein said first and second seals comprise generally flat inner and outer annular lip seals clamped between said elements. 
     
     
       29. A scroll machine as claimed in claim 28 wherein said inner and outer lip seals are integral with one another. 
     
     
       30. A scroll machine as claimed in claim 28 wherein said inner and outer lip seals are separate parts. 
     
     
       31. A scroll machine as claimed in claim 28 wherein there are a plurality of inner lip seals having an annular spacer element disposed therebetween. 
     
     
       32. A scroll machine as claimed in claim 26 wherein all of said seals are annular in configuration, said third seal being of a diameter which provides a positive net scaling force under normal operating conditions. 
     
     
       33. A scroll machine as claimed in claim 32 wherein said third seal is of a width such that the unit pressure thereon in a sealing direction is greater than normal discharge pressure. 
     
     
       34. A scroll machine as claimed in claim 26 wherein said seal means floats axially in said cavity and wherein the existence of a vacuum at the suction inlet of said compressor will cause said seal means to move axially and render said third seal ineffective. 
     
     
       35. A multi-function seal assembly comprising: (a) an annular inner lip seal adapted to sealingly engage the outside of a first cylindrical surface;   (b) an annular outer lip seal adapted to sealingly engage the inside of a second cylindrical surface, said seal assembly being mounted for movement along the center axes of said seals;   (c) first and second clamping elements clamping said inner and outer seals therebetween; and   (d) a third annular seal operatively associated with one of said elements and being adapted to sealingly engage a generally flat annular sealing surface.   
     
     
       36. A multi-function seal assembly as claimed in claim 35 wherein said three seals are coaxial with one another. 
     
     
       37. A multi-function seal assembly as claimed in claim 35 wherein said first and second cylindrical surfaces define the side walls of an annular cavity, said sealing surface being disposed opposite the bottom of said cavity. 
     
     
       38. A scroll machine comprising: (a) a hermetic shell;   (b) an orbiting scroll member disposed in said shell and having a first spiral wrap on one face thereof;   (c) a non-orbiting scroll member in said shell and having a second spiral wrap on one face thereof, said wraps being intermeshed with one another;   (d) means for causing said orbiting scroll member to orbit about an axis with respect to said non-orbiting scroll member whereby said wraps will create pockets of progressively changing volume;   (e) means for mounting one of said scroll members for limited axial movement with respect to the other scroll member;   (f) means defining an annular cavity exposed to a surface on one of said scroll members which will cause pressurized fluid in said cavity to bias said one scroll member toward the other scroll member, said cavity having a radial inner wall surface and a radial outer wall surface;   (g) means defining a fluid leakage path between said cavity and the interior of said shell;   (h) means for supplying fluid under pressure to said cavity for biasing said scroll members axially together; and   (i) annular seal means disposed in said cavity, said seal means having first and second seals sealingly engaging said inner and outer wall surfaces, respectively, to isolate said pressurized fluid in said cavity from said leakage path, said seal means being of sandwich construction comprising a first annular element having an annular axially extending rib and a second annular element formed of two annular parts disposed on opposite sides of said rib wherein said first and second seals comprise generally flat inner and outer annular lip seals clamped between said elements.   
     
     
       39. A scroll machine comprising: (a) a hermetic shell;   (b) an orbiting scroll member disposed in said shell and having a first spiral wrap on one face thereof;   (c) a non-orbiting scroll member in said shell and having a second spiral wrap on one face thereof, said wraps being intermeshed with one another;   (d) means for causing said orbiting scroll member to orbit about an axis with respect to said non-orbiting scroll member whereby said wraps will create pockets of progressively changing volume;   (e) means for mounting one of said scroll members for limited axial movement with respect to the other scroll member;   (f) means defining an annular cavity exposed to a surface of one of said scroll members which will cause pressurized fluid in said cavity to bias said one scroll member toward the other scroll member, said cavity having a radially inner wall surface and a radially outer wall surface;   (g) means defining a fluid leakage path between said cavity and the interior of said shell;   (h) means for supplying fluid under pressure to said cavity for biasing said scroll members axially together; and   (i) annular seal means disposed in said cavity, said seal means having first and second seals sealingly engaging said inner and outer wall surfaces, respectively, to isolate said pressurized fluid in said cavity from said leakage path, said seal means being of sandwich construction comprising a first annular element having an annular axially extending rib and a second annular element formed of two annular parts disposed on opposite sides of said rib wherein said first and second seals comprise generally flat inner and outer annular lip seals clamped between said elements and wherein said rib is swedged at circumferentially spaced points to clamp said two annular parts and said lip seals between said elements.   
     
     
       40. A scroll compressor comprising: (a) a hermetic shell;   (b) an orbiting scroll member disposed in said shell and having a first spiral wrap on one face thereof;   (c) a non-orbiting scroll member in said shell and having a second . .signal.!. .Iadd.spiral .Iaddend.wrap on one face thereof, said wraps being intermeshed with one another;   (d) means for causing said orbiting scroll member to orbit about an axis with respect to said non-orbiting scroll member whereby said wraps will create pockets of progressively changing volume;   (e) means for mounting one of said scroll members for limited axial movement with respect to the other scroll member;   (f) means defining an annular cavity exposed to a surface of one of said scroll members which will cause pressurized fluid in said cavity to bias said one scroll member toward the other scroll member, said cavity having a radially inner wall surface and a radially outer wall surface;   (g) means defining a first fluid leakage path between said cavity and the interior of said shell;   (h) means defining a second fluid leakage path between said cavity and a zone in said shell at discharge pressure;   (i) means for supplying fluid under pressure to said cavity for biasing said scroll members axially together; and   (j) annular seal means disposed in said cavity, said seal means having first and second seals sealingly engaging said inner and outer wall surfaces, respectively, to isolate said pressurized fluid in said cavity from said .Iadd.first and second .Iaddend.leakage . .path.!. .Iadd.paths.Iaddend., said seal means being of sandwich construction comprising a first annular element having an annular axially extending rib and a second annular element formed of two annular parts disposed on opposite sides of said rib wherein said first and second seals comprise generally flat inner and outer annular lip seals clamped between said elements;   wherein one face of said seal means is exposed to the fluid in said cavity with said first seal isolating said cavity from said discharge pressure zone and said second seal isolating said cavity from the interior of said shell, the opposite face of said seal means being exposed to both the interior of said shell and to discharge pressure, said seal means . .comprising.!. .Iadd.engaging another component of said compressor to define .Iaddend.a third annular seal for isolating the interior of said shell from discharge pressure across said opposite face of said seal means.   
     
     
       41. A scroll compressor comprising: (a) a hermetic shell;   (b) an orbiting scroll member disposed in said shell and having a first spiral wrap on one face thereof;   (c) a non-orbiting scroll member in said shell and having a second spiral wrap on one face thereof, said wraps being intermeshed with one another;   (d) means for causing said orbiting scroll member to orbit about an axis with respect to said non-orbiting scroll member whereby said wraps will create pockets of progressively changing volume;   (e) means for mounting one of said scroll members for limited axial movement with respect to the other scroll member;   (f) means defining an annular cavity exposed to a surface of one of said scroll members which will cause pressurized fluid in said cavity to bias said one scroll member toward the other scroll member, said cavity having a radially inner wall surface and a radially outer wall surface;   (g) means defining a first fluid leakage path between said cavity and the interior of said shell;   (h) means defining a second fluid leakage path between said cavity and a zone in said shell at discharge pressure;   (i) means for supplying fluid under pressure to said cavity for biasing said scroll members axially together; and   (j) annular seal means disposed in said cavity, said seal means having first and second seals sealingly engaging said inner and outer wall surfaces, respectively, to isolate said pressurized fluid in said cavity from said .Iadd.first and second .Iaddend.leakage paths, said seal means being of sandwich construction comprising a first annular element having an annular axially extending rib and a second annular element formed of two annular parts disposed on opposite sides of said rib wherein said first and second seals comprise generally flat inner and outer annular lip seals clamped between said elements;   wherein one face of said seal means is exposed to the fluid in said cavity with said first seal isolating said cavity from said discharge pressure zone and said second seal isolating said cavity from the interior of said shell, the opposite face of said seal means being exposed to both the interior of said shell and to discharge pressure, said seal means . .comprising.!. .Iadd.engaging another component of said compressor to define .Iaddend.a third annular seal for isolating the interior of said shell from discharge pressure across said opposite face of said seal means and wherein said third seal is integral with said second element of said seal means.   
     
     
       42. A scroll compressor comprising: (a) a hermetic shell;   (b) a discharge fluid port in a partition disposed in said shell;   (c) an orbiting scroll member disposed in said shell and having a first spiral wrap on one face thereof;   (d) a non-orbiting scroll member in said shell and having a second spiral wrap on one face thereof, said wraps being intermeshed with one another;   (e) means for causing said orbiting scroll member to orbit about an axis with respect to said non-orbiting scroll member whereby said wraps will create pockets of progressively changing volume;   (f) means for mounting one of said scroll members for limited axial movement with respect to the other scroll member;   (g) means defining an annular cavity exposed to a surface of one of said scroll members which will cause pressurized fluid in said cavity to bias said one scroll member toward the other scroll member, said cavity having a radially inner wall surface and a radially outer wall surface;   (h) means defining a first fluid leakage path between said cavity and the interior of said shell;   (i) means defining a second fluid leakage path between said cavity and a zone in said shell at discharge pressure;   (j) means for supplying fluid under pressure to said cavity for biasing said scroll members axially together; and   (k) annular seal means disposed in said cavity, said seal means having first and second seals sealingly engaging said inner and outer wall surfaces, respectively, to isolate said pressurized fluid in said cavity from said .Iadd.first and second .Iaddend.leakage . .path.!. .Iadd.paths.Iaddend., said seal means being of a sandwich construction comprising a first annular element and a second annular element wherein said first and second seals comprise generally flat inner and outer annular lip seals clamped between said elements;   wherein one face of said seal means is exposed to the fluid in said cavity with said first seal isolating said cavity from said discharge pressure zone and said second seal isolating said cavity from the interior of said shell, the opposite face of said seal means being exposed to both the interior of said shell and to discharge pressure, said seal means . .comprising.!. .Iadd.engaging another component of said compressor to define .Iaddend.a third annular seal for isolating the interior of said shell from discharge pressure across said opposite face of said seal means said third seal surrounding said discharge fluid port.   
     
     
       43. A scroll compressor comprising: (a) a hermetic shell;   (b) a discharge fluid port in a partition disposed in said shell;   (c) a hardened valve seat on said partition surrounding said discharge fluid port;   (d) an orbiting scroll member disposed in said shell and having a first spiral wrap on one face thereof;   (e) a non-orbiting scroll member in said shell and having a second spiral wrap on one face thereof, said wraps being intermeshed with one another;   (f) means for causing said orbiting scroll member to orbit about an axis with respect to said non-orbiting scroll member whereby said wraps will create pockets of progressively changing volume;   (g) means for mounting one of said scroll members for limited axial movement with respect to the other scroll member;   (h) means defining an annular cavity exposed to a surface of one of said scroll members which will cause pressurized fluid in said cavity to bias said one scroll member toward the other scroll member, said cavity having a radially inner wall surface and a radially outer wall surface;   (i) means defining a first fluid leakage path between said cavity and the interior of said shell;   (g) means defining a second fluid leakage path between said cavity and a zone in said shell at discharge pressure;   (k) means for supplying fluid under pressure to said cavity for biasing said scroll members axially together; and   (l) annular seal means disposed in said cavity, said seal means having first and second seals sealingly engaging said inner and outer wall surfaces, respectively, to isolate said pressurized fluid in said cavity from said .Iadd.first and second .Iaddend.leakage . .path.!. .Iadd.paths.Iaddend., said seal means being of a sandwich construction comprising a first annular element and a second annular element wherein said first and second seals comprise generally flat inner and outer annular lip seals clamped between said elements;   wherein one face of said seal means is exposed to the fluid in said cavity with said first seal isolating said cavity from said discharge pressure zone and said second seal isolating said cavity from the interior of said shell, the opposite face of said seal means being exposed to both the interior of said shell and to discharge pressure, said seal means . .comprising.!. .Iadd.engaging another component of said compressor to define .Iaddend.a third annular seal for isolating the interior of said shell from discharge pressure across said opposite face of said seal means said third seal surrounding said discharge fluid port.   
     
     
       44. A scroll compressor comprising: (a) a hermetic shell;   (b) a discharge fluid port in a partition disposed in said shell;   (c) a hardened valve seat on said partition surrounding said discharge fluid port, said valve seat being a separate annular member affixed to said partitions and surrounding said discharge fluid port;   (d) an orbiting scroll member disposed in said shell and having a first spiral wrap on one face thereof;   (e) a non-orbiting scroll member in said shell and having a second spiral wrap on one face thereof, said wraps being intermeshed with one another;   (f) means for causing said orbiting scroll member to orbit about an axis with respect to said non-orbiting scroll member whereby said wraps will create pockets of progressively changing volume;   (g) means for mounting one of said scroll members for limited axial movement with respect to the other scroll member;   (h) means defining an annular cavity exposed to a surface of one of said scroll members which will cause pressurized fluid in said cavity to bias said one scroll member toward the other scroll member, said cavity having a radially inner wall surface and a radially outer wall surface;   (i) means defining a first fluid leakage path between said cavity and the interior of said shell;   (j) means defining a second fluid leakage path between said cavity and a zone in said shell at discharge pressure;   (k) means for supplying fluid under pressure to said cavity for biasing said scroll members axially together; and   (l) annular seal means disposed in said cavity, said seal means having first and second seals sealingly engaging said inner and outer wall surfaces, respectively, to isolate said pressurized fluid in said cavity from said .Iadd.first and second .Iaddend.leakage . .path.!. .Iadd.paths.Iaddend., said seal means being of a sandwich construction comprising a first annular element and a second annular element wherein said first and second seals comprise generally flat inner and outer annular lip seals clamped between said elements;   wherein one face of said seal means is exposed to the fluid in said cavity with said first seal isolating said cavity from said discharge pressure zone and said second seal isolating said cavity from the interior of said shell, the opposite face of said seal means being exposed to both the interior of said shell and to discharge pressure, said seal means . .comprising.!. .Iadd.engaging another component of said compressor to define .Iaddend.a third annular seal for isolating the interior of said shell from discharge pressure across said opposite face of said seal means said third seal surrounding said discharge fluid port.   
     
     
       45. A scroll compressor comprising: (a) a hermetic shell;   (b) a discharge fluid port in a partition disposed in said shell;   (c) a hardened valve seat on said partition surrounding said discharge fluid port, said valve seat being a locally hardened surface on said partition surrounding said discharge fluid port;   (d) an orbiting scroll member disposed in said shell and having a first spiral wrap on one face thereof;   (e) a non-orbiting scroll member in said shell and having a second spiral wrap on one face thereof, said wraps being intermeshed with one another;   (f) means for causing said orbiting scroll member to orbit about an axis with respect to said non-orbiting scroll member whereby said wraps will create pockets of progressively changing volume;   (g) means for mounting one of said scroll members for limited axial movement with respect to the other scroll member;   (h) means defining an annular cavity exposed to a surface of one of said scroll members which will cause pressurized fluid in said cavity to bias said one scroll member toward the other scroll member, said cavity having a radially inner wall surface and a radially outer wall surface;   (i) means defining a first fluid leakage path between said cavity and the interior of said shell;   (j) means defining a second fluid leakage path between said cavity and a zone in said shell at discharge pressure;   (k) means for supplying fluid under pressure to said cavity for biasing said scroll members axially together; and   (l) annular seal means disposed in said cavity, said seal means having first and second seals sealingly engaging said inner and outer wall surfaces, respectively, to isolate said pressurized fluid in said cavity from said .Iadd.first and second .Iaddend.leakage . .path.!. .Iadd.paths.Iaddend., said seal means being of sandwich construction comprising a first annular element having an annular axially extending rib and a second annular element formed of two annular parts disposed on opposite sides of said rib wherein said first and second seals comprise generally flat inner and outer annular lip seals clamped between said elements;   wherein one face of said seal means is exposed to the fluid in said cavity with said first seal isolating said cavity from said discharge pressure zone and said second seal isolating said cavity from the interior of said shell, the opposite face of said seal means being exposed to both the interior of said shell and to discharge pressure, said seal means . .comprising.!. .Iadd.engaging another component of said compressor to define .Iaddend.a third annular seal for isolating the interior of said shell from discharge pressure across said opposite face of said seal means said third seal surrounding said discharge fluid port.   
     
     
       46. A scroll compressor having a discharge zone at discharge pressure comprising: (a) a hermetic shell;   (b) an orbiting scroll member disposed in said shell and having a first spiral wrap on one face thereof;   (c) a non-orbiting scroll member in said shell and having a second spiral wrap on one face thereof, said wraps being intermeshed with one another;   (d) means for causing said orbiting scroll member to orbit about an axis with respect to said non-orbiting scroll member whereby said wraps will create pockets of progressively changing volume;   (e) means for mounting one of said scroll members for limited axial movement with respect to the other scroll member;   (f) means defining an annular cavity exposed to a surface of one of said scroll members which will cause pressurized fluid in said cavity to bias said one scroll member toward the other scroll member, said cavity having a radially inner wall surface and a radially outer wall surface;   (g) means defining a first fluid leakage path between said cavity and the interior of said shell;   (h) means defining a second fluid leakage path between said cavity and a zone in said shell at discharge pressure;   (i) means for supplying fluid under pressure to said cavity for biasing said scroll members axially together; and   (j) annular seal means disposed in said cavity, said seal means having first and second seals sealingly engaging said inner and outer wall surfaces, respectively, to isolate said pressurized fluid in said cavity from said .Iadd.first and second .Iaddend.leakage . .path.!. .Iadd.paths.Iaddend.;   wherein one face of said seal means is exposed to the fluid in said cavity with said first seal isolating said cavity from said discharge pressure zone and said second seal isolating said cavity from the interior of said shell, the opposite face of said seal means being exposed to both the interior of said shell and to discharge pressure, said seal means . .comprising.!. .Iadd.engaging another component of said compressor to define .Iaddend.a third annular seal for isolating the interior of said shell from discharge pressure across said opposite face of said seal means said third seal surrounding said discharge fluid port.   
     
     
       47. A scroll compressor having a discharge zone at discharge pressure machine comprising: (a) a hermetic shell;   (b) an orbiting scroll member disposed in said shell and having a first spiral wrap on one face thereof;   (c) a non-orbiting scroll member disposed in said shell and having a second spiral wrap on one face thereof, said wraps being intermeshed with one another;   (d) means for causing said orbiting scroll member to orbit about an axis with respect to said non-orbiting scroll member whereby said wraps will create pockets of progressively changing volume;   (e) means for mounting one of said scroll members for limited axial movement with respect to the other scroll member;   (f) means defining an annular cavity exposed to a surface on one of said scroll members which will cause pressurized fluid in said cavity to bias said one scroll member toward the other scroll member, said cavity having a radial inner wall surface and a radial outer wall surface;   (g) means defining a first fluid leakage path between said cavity and the interior of said shell;   (h) means defining a second fluid leakage path between said cavity and said discharge zone;   (i) means for supplying fluid under pressure to said cavity for biasing said scroll members axially together; and   (j) annular seal means disposed in said cavity, said seal means having first and second seals sealingly engaging said inner and outer wall surfaces, respectively, to isolate said pressurized fluid in said cavity from said .Iadd.first and second .Iaddend.leakage . .path.!. .Iadd.paths.Iaddend.;   wherein one face of said seal means is exposed to the fluid in said cavity with said first seal isolating said cavity from said discharge pressure zone and said second seal isolating said cavity from the interior of said shell, the opposite face of said seal means being exposed to both the interior of said shell and to discharge pressure, said seal means . .comprising.!. .Iadd.engaging another component of said compressor to define .Iaddend.a third annular seal for isolating the interior of said shell from discharge pressure across said opposite face of said seal means, said third seal being integral with said second element of said seal means. .Iadd.   
     
     
       48.  A scroll machine comprising: (a) a hermetic shell;   (b) an orbiting scroll member disposed in said shell and having a first spiral wrap on one face thereof;   (c) a non-orbiting scroll member disposed in said shell and having a second spiral wrap on one face thereof, said spiral wraps being intermeshed with one another;   (d) means for causing said orbiting scroll member to orbit about an axis with respect to said non-orbiting scroll member whereby said wraps will create pockets of progressively changing volume between a suction pressure zone defining a suction pressure and a discharge pressure zone defining a discharge pressure;   (e) means defining a cavity disposed within one of said scroll members;   (f) means defining a fluid path between said discharge pressure zone and said suction pressure zone;   (g) means for supplying intermediate pressurized fluid to said cavity, said intermediate pressurized fluid being at a pressure inbetween said suction and discharge pressures; and   (h) seal means disposed in said cavity to isolate said intermediate pressurized fluid in said cavity whereby said seal means engages another component of said compressor to close said fluid path and said discharge pressure zone. .Iaddend..Iadd.49. A scroll machine as claimed in claim 48 wherein said one scroll member is said non-orbiting scroll member.   
     
     
        .Iaddend..Iadd.50.  A scroll machine as claimed in claim 48 wherein said seal means floats axially in said cavity between a first position wherein said seal means isolates fluid in said suction pressure zone from fluid in said discharge pressure zone and a second position wherein fluid in said discharge pressure zone is leaked to said suction pressure zone. .Iaddend..Iadd.51. A scroll machine as claimed in claim 50 wherein said seal means is disposed in said first position under normal operating conditions. .Iaddend..Iadd.52. A scroll machine as claimed in claim 50 wherein said seal means moves to said second position when the ratio between said discharge pressure and said suction pressure exceeds a predefined limit. .Iaddend..Iadd.53. A scroll machine as claimed in claim 48 wherein said intermediate pressurized fluid reacts against a surface of said one scroll member to bias said one scroll member toward the other scroll member. .Iaddend..Iadd.54. A scroll machine as claimed in claim 48 wherein said cavity is substantially defined by said non-orbiting scroll member. .Iaddend..Iadd.55. A scroll machine as claimed in claim 48 including a leakage path between said cavity and said suction pressure zone. .Iaddend..Iadd.56. A scroll machine as claimed in claim 48 wherein said seal means provides a first seal isolating said cavity from said discharge pressure zone, and a second seal isolating said cavity from said suction pressure zone, said engagement creating a third seal isolating said discharge pressure zone from said suction pressure zone. 
     
     
        .Iaddend..Iadd.57.  A scroll machine comprising: (a) a hermetic shell;   (b) an orbiting scroll member disposed in said shell and having a first spiral wrap on one face thereof;   (c) a non-orbiting scroll member disposed in said shell and having a second spiral wrap on one face thereof, said spiral wraps being intermeshed with one another;   (d) means for causing said orbiting scroll member to orbit about an axis with respect to said non-orbiting scroll member whereby said wraps will create pockets of progressively changing volume to compress a working fluid between a suction pressure zone defining a suction pressure and a discharge pressure zone defining a discharge pressure;   (e) means defining a cavity disposed within one of said scroll members;   (f) means defining a fluid path between said discharge pressure zone and said suction pressure zone;   (g) means for supplying said working fluid under pressure to said cavity; and   (h) seal means disposed to move in said cavity between a first position wherein said seal means engages another component of said scroll machine to isolate said discharge pressure zone from said suction pressure zone and a second position in which a leakage of fluid in said discharge pressure zone into said suction pressure zone is permitted. .Iaddend..Iadd.58. A scroll machine as claimed in claim 57 wherein said working fluid being supplied to said cavity is at a pressure intermediate said suction pressure and said discharge pressure. .Iaddend..Iadd.59. A scroll machine as claimed in claim 57 wherein said seal means is disposed in said first position under normal operating conditions. .Iaddend..Iadd.60. A scroll machine as claimed in claim 57 wherein the existence of a vacuum at the suction inlet of said compressor will cause said seal means to move from said first position to said second position.   
     
     
        .Iaddend..Iadd.61.  A scroll machine as claimed in claim 57 wherein said pressurized fluid reacts against a surface of said one scroll member to bias said one scroll member toward the other scroll member. .Iaddend..Iadd.62. A scroll machine as claimed in claim 57 wherein said cavity is exposed to a surface of said non-orbiting scroll member. .Iaddend..Iadd.63. A scroll machine as claimed in claim 62 wherein said working fluid under pressure reacts against said surface to bias said non-orbiting scroll member toward said orbiting scroll member. .Iaddend..Iadd.64. A scroll machine of claim 57 wherein said seal means floats axially in response to the ratio between said suction pressure and 
     
     
        said discharge pressure. .Iaddend..Iadd.65.  A scroll compressor comprising: (a) a hermetic shell;   (b) an orbiting scroll member disposed in said shell and having a first spiral wrap on one face thereof;   (c) a non-orbiting scroll member disposed in said shell and having a second spiral wrap on one face thereof, said spiral wraps being intermeshed with one another;   (d) means for causing said orbiting scroll member to orbit about an axis with respect to said non-orbiting scroll member whereby said wraps will create pockets of progressively changing volume to compress a working fluid between a suction pressure zone defining a suction pressure and a discharge pressure zone defining a discharge pressure zone;   (e) means defining a cavity disposed within one of said scroll members;   (f) means defining a leakage path between said discharge pressure zone and said suction pressure zone;   (g) means for supplying said working fluid to said cavity at a pressure intermediate said suction pressure and said discharge pressure; and   (h) movable seal means disposed in said cavity for closing said leakage path by engaging another component of said compressor, said seal means being disposed under normal operating conditions of said compressor in a first position wherein said seal means isolates said discharge pressure zone from said suction pressure zone and wherein said seal means moves within said cavity to a second position wherein said fluid in said discharge pressure zone is leaked into said suction pressure zone when the ratio of said discharge pressure to said suction pressure exceeds a predefined limit. .Iaddend..Iadd.66. A scroll machine as claimed in claim 65 wherein said working fluid being supplied to said cavity reacts against said scroll members to bias said scroll members together. .Iaddend.