Abstract:
A compressor may include a housing, a compression mechanism supported within the housing, and a seal assembly. The housing may include a suction pressure region and a first discharge passage in communication with a discharge pressure region. The compression mechanism may include a second discharge passage in communication with the first discharge passage. The seal assembly may be sealingly engaged with the housing and the compression mechanism to define a chamber and to provide sealed communication between the first and second discharge passages. The seal assembly may include a seal member engaged with the compression mechanism and including a leg having an opening therein. The leg may isolate the chamber from the discharge pressure region when in a first position and may provide communication between the chamber and the discharge pressure region through the opening when in a second position different than the first position.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation of U.S. patent application Ser. No. 11/073,492 filed on Mar. 4, 2005. The disclosure of the above application is incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates to scroll compressors, and more specifically, to seal assemblies for scroll compressors. 
       BACKGROUND AND SUMMARY OF THE INVENTION 
       [0003]    A class of machines exists in the art generally known as “scroll” machines for the displacement of various types of fluids. Such machines may be configured as an expander, a displacement engine, a pump, a compressor, etc., and the features of the present invention are applicable to any one of these machines. For purposes of illustration, however, the disclosed embodiments are in the form of a hermetic refrigerant compressor. 
         [0004]    Generally speaking, a scroll machine comprises two spiral scroll wraps of similar configuration, each mounted on a separate end plate to define a scroll member. The two scroll members are interfitted together with one of the scroll wraps being rotationally displaced 180° from the other. The machine operates by orbiting one scroll member (the “orbiting scroll”) with respect to the other scroll member (the “fixed scroll” or “non-orbiting scroll”) to make moving line contacts between the flanks of the respective wraps, defining moving isolated crescent-shaped pockets of fluid. The spirals are commonly formed as involutes of a circle, and ideally there is no relative rotation between the scroll members during operation; i.e., the motion is purely curvilinear translation (i.e., no rotation of any line in the body). The fluid pockets carry the fluid to be handled from a first zone in the scroll machine where a fluid inlet is provided, to a second zone in the machine where a fluid outlet is provided. The volume of a sealed pocket changes as it moves from the first zone to the second zone. At any one instant in time there will be at least one pair of sealed pockets; and where there are several pairs of sealed pockets at one time, each pair will have different volumes. In a compressor, the second zone is at a higher pressure than the first zone and is physically located centrally in the machine, the first zone being located at the outer periphery of the machine. 
         [0005]    A compressor may include a housing, a compression mechanism, and a seal assembly. The housing may include a suction pressure region operating at a suction pressure and a first discharge passage in communication with a discharge pressure region operating at a discharge pressure. The compression mechanism may be supported within the housing and may include first and second scroll members meshingly engaged with one another to form a series of compression pockets. The first scroll member may include a second discharge passage in communication with the first discharge passage. The seal assembly may be sealingly engaged with the housing and the compression mechanism to provide sealed communication between the first and second discharge passages. The seal assembly and the compression mechanism may define a chamber in communication with one of the compression pockets. The seal assembly may include a seal member engaged with the compression mechanism and including a leg having an opening therein. The leg may isolate the chamber from the discharge pressure region when in a first position and may provide communication between the chamber and the discharge pressure region through the opening when in a second position different than the first position. 
         [0006]    The opening in the leg may include a notch in a first end of the leg that is in communication with the discharge pressure region and isolated from the chamber when the leg is in the first position. The notch may be in communication with the discharge pressure region and the chamber when the leg is in the second position. 
         [0007]    A compressor may include a housing, a compression mechanism, and a sealing assembly. The housing may include a first pressure region operating at a first pressure and a first discharge passage in communication with a discharge pressure region operating at a discharge pressure. The compression mechanism may be supported within the housing and may include non-orbiting and orbiting scroll members meshingly engaged with one another to form a series of compression pockets. The non-orbiting scroll member may include a second discharge passage in communication with the first discharge passage. The seal assembly that may be sealingly engaged with the housing and the non-orbiting scroll member to provides sealed communication between the first and second discharge passages, the seal assembly may include a seal member engaged with the non-orbiting scroll member and including a leg having an opening therein. The leg may provide sealed communication between the first and second discharge passages when in a first position and may provide communication between the first pressure region and the discharge pressure region through the opening when in a second position different than the first position. 
         [0008]    Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]    The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein: 
           [0010]      FIG. 1  is a vertical cross-sectional view of a scroll compressor incorporating a floating seal design in accordance with the present invention; 
           [0011]      FIG. 2  is an enlarged view of the floating seal illustrated in  FIG. 1 ; 
           [0012]      FIG. 2A  is an enlarged view of circled  2 A in  FIG. 2  illustrating a seal in accordance with another embodiment of the present invention; 
           [0013]      FIG. 3  is a view similar to  FIG. 2  but illustrating a floating seal design in accordance with another embodiment of the present invention; 
           [0014]      FIG. 4  is a view similar to  FIG. 2  but illustrating a floating seal design in accordance with another embodiment of the present invention; 
           [0015]      FIG. 5  is a view similar to  FIG. 2  but illustrating a floating seal design in accordance with another embodiment of the present invention; 
           [0016]      FIG. 6  is a view similar to  FIG. 3  but incorporating a discharge valve assembly with the floating seal; 
           [0017]      FIG. 7  is a view similar to  FIG. 3  but incorporating a temperature protection system with the floating seal; 
           [0018]      FIG. 8  is a view similar to  FIG. 3  but incorporating a pressure protection system with the floating seal; 
           [0019]      FIG. 9  is a view similar to  FIG. 2  but incorporating a pressure protection system with the floating seal in accordance with another embodiment of the present invention; 
           [0020]      FIG. 10A  is an enlarged view of the pressure relief valve illustrated in  FIGS. 7 and 9  in its closed position; 
           [0021]      FIG. 10B  is an enlarged view of the pressure relief valve illustrated in  FIGS. 7 and 9  in its open position; 
           [0022]      FIG. 11A  is a plan view of a vented seal assembly in accordance with another embodiment of the present invention; and 
           [0023]      FIG. 11B  is an enlarged view of the vented seal shown in  FIG. 11A  installed in a compressor. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0024]    The following description of the preferred embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses. 
         [0025]    There is illustrated in  FIG. 1  a scroll compressor which incorporates a floating seal arrangement in accordance with the present invention and which is designated generally by reference numeral  10 . Compressor  10  comprises a generally cylindrical hermetic shell  12  having welded at the upper end thereof a cap  14  and at the lower end thereof a base  16  having a plurality of mounting feet (not shown) integrally formed therewith. Cap  14  is provided with a refrigerant discharge fitting  18  which may have the usual discharge valve therein (not shown). Other major elements affixed to the shell include a transversely extending partition  22  which is welded about its periphery at the same point that cap  14  is welded to shell  12 , a stationary main bearing housing or body  24  which is suitably secured to shell  12 , and a lower bearing housing  26  also having a plurality of radially outwardly extending legs, each of which is also suitably secured to shell  12 . A motor stator  28 , which is generally square in cross-section but with the corners rounded off, is pressfitted into shell  12 . The flats between the rounded corners on the stator provide passageways between the stator and shell, which facilitate the flow of lubricant from the top of the shell to the bottom. 
         [0026]    A drive shaft or crankshaft  30  having an eccentric crank pin  32  at the upper end thereof is rotatably journaled in a bearing  34  in main bearing housing  24  and a second bearing  36  in lower bearing housing  26 . Crankshaft  30  has at the lower end a relatively large diameter concentric bore  38  which communicates with a radially outwardly inclined smaller diameter bore  40  extending upwardly therefrom to the top of the crankshaft. Disposed within bore  38  is a stirrer  42 . The lower portion of the interior shell  12  is filled with lubricating oil, and bore  38  acts as a pump to pump lubricating fluid up the crankshaft  30  and into bore  40 , and ultimately to all of the various portions of the compressor which require lubrication. 
         [0027]    Crankshaft  30  is rotatively driven by an electric motor including stator  28 , windings  44  passing therethrough and a rotor  46  pressfitted on the crankshaft  30  and having upper and lower counterweights  48  and  50 , respectively. A counterweight shield  52  may be provided to reduce the work loss caused by counterweight  50  spinning in the oil in the sump. Counterweight shield  52  is more fully disclosed in Assignee&#39;s U.S. Pat. No. 5,064,356 entitled “Counterweight Shield For Scroll Compressor,” the disclosure of which is hereby incorporated herein by reference. 
         [0028]    The upper surface of main bearing housing  24  is provided with a flat thrust bearing surface on which is disposed an orbiting scroll member  54  having the usual spiral vane or wrap  56  on the upper surface thereof. Projecting downwardly from the lower surface of orbiting scroll member  54  is a cylindrical hub  58  having a journal bearing therein and in which is rotatively disposed a drive bushing  60  having an inner bore  62  in which crank pin  32  is drivingly disposed. Crank pin  32  has a flat on one surface which drivingly engages a flat surface (not shown) formed in a portion of bore  62  to provide a radially compliant driving arrangement, such as shown in aforementioned Assignee&#39;s U.S. Pat. No. 4,877,382, the disclosure of which is hereby incorporated herein by reference. An Oldham coupling  64  is also provided positioned between and keyed to orbiting scroll member  54  and a non-orbiting scroll member  66  to prevent rotational movement of orbiting scroll member  54 . Oldham coupling  64  is preferably of the type disclosed in the above-referenced U.S. Pat. No. 4,877,382; however, the coupling disclosed in Assignee&#39;s U.S. Pat. No. 5,320,506 entitled “Oldham Coupling For Scroll Compressor”, the disclosure of which is hereby incorporated herein by reference, may be used in place thereof. 
         [0029]    Non-orbiting scroll member  66  is also provided having a wrap  68  positioned in meshing engagement with wrap  56  of orbiting scroll member  54 . Non-orbiting scroll member  66  has a centrally disposed discharge passage  70  communicating with an upwardly open recess  72  which is in fluid communication with a discharge muffler chamber  74  defined by cap  14  and partition  22  through an opening defined by partition  22 . An annular recess  76  is also formed in non-orbiting scroll member  66  within which is disposed a floating seal assembly  78 . Recesses  72  and  76  and floating seal assembly  78  cooperate to define axial pressure biasing chambers which receive pressurized fluid being compressed by wraps  56  and  68  so as to exert an axial biasing force on non-orbiting scroll member  66  to thereby urge the tips of respective wraps  56 ,  68  into sealing engagement with the opposed end plate surfaces. 
         [0030]    With reference to  FIGS. 1 and 2 , floating seal assembly  78  comprises a single metal plate  80 , an annular inner seal  82  and an annular outer seal  84 . Metal plate  80  is preferably manufactured from cast iron or powdered metal but any other material, metal or plastic, which meets the performance requirements for plate  80  may be utilized. Plate  80  includes an upwardly projecting planar sealing lip  86  which engages partition  22  to separate the discharge area of compressor  10  from the suction area of compressor  10 . 
         [0031]    Annular inner seal  82  is preferably manufactured from a polymer such as glass filled PTFE or Teflon® but any suitable polymer can be used. Annular inner seal  82  is disposed within a groove  88  formed by plate  80 . Annular inner seal  82  engages non-orbiting scroll member  66  and plate  80  to separate the discharge area of compressor  10  from the intermediate pressurized fluid within recess  76 . 
         [0032]    Annular inner seal  82  has a U-shaped cross section with the opening between the legs of the U-shaped cross section being open towards the discharge area of compressor  10  which is at a higher pressure than the intermediate pressurized fluid within recess  76 . This orientation for annular inner seal  82  pressure energizes the legs of annular inner seal  82  to improve its performance. 
         [0033]    Annular outer seal  84  is preferably manufactured from a polymer such as glass filled PTFE or Teflon® but any suitable polymer can be used. Annular outer seal  84  is disposed within a groove  90  formed by plate  80 . Annular outer seal  84  engages non-orbiting scroll member  66  and plate  80  to separate the intermediate pressurized fluid within recess  76  from the suction area of compressor  10 . Annular outer seal  84  has a U-shaped cross section with the opening between the legs of the U-shaped cross section being open towards the intermediate pressurized fluid within recess  76  which is at a higher pressure than the pressurized fluid within the suction area of compressor  10 . This orientation for annular outer seal  84  pressure energizes the legs of annular outer seal  84  to improve its performance. 
         [0034]    The overall seal assembly therefore provides three distinct seals, namely, an inside diameter seal at  92 , an outside diameter seal at  94  and a top seal at  96 . Seal  92  isolates fluid under intermediate pressure in the bottom of recess  76  from fluid under discharge pressure in recess  72 . Seal  94  isolates fluid under intermediate pressure in the bottom of recess  76  from fluid at suction pressure within shell  12 . Seal  96  isolates fluid at suction pressure within shell  12  from fluid at discharge pressure across the top of seal assembly  78 .  FIGS. 1 and 2  illustrate a wear ring  98  attached to partition  22  which provides seal  96  between plate  80  and wear ring  98 . In lieu of wear ring  98 , the lower surface of partition  22  can be locally hardened by nitriding, carbo-nitriding or other hardening processes known in the art. 
         [0035]    The diameter of seal  96  is chosen so that there is a positive upward sealing force on floating seal assembly  78  under normal operating conditions i.e. at normal pressure ratios. Therefore, when excessive pressure ratios are encountered, floating seal assembly  78  will be forced downwardly by discharge pressure, thereby permitting a leak of high side discharge pressure gas directly across the top of floating seal assembly  78  to a zone of low side suction gas. If this leakage is great enough, the resultant loss of flow of motor cooling suction gas (aggravated by the excessive temperature of the leaking discharge gas) will cause a motor protector (not shown) to trip, thereby de-energizing the motor. The width of seal  96  is chosen so that the unit pressure on the seal itself (i.e. between sealing lip  86  and wear ring  98 ) is greater than normally encountered discharge pressure, thus insuring consistent sealing. 
         [0036]    Referring now to  FIG. 2A , a floating seal assembly  78 ′ is illustrated. Floating seal assembly  78 ′ is the same as floating seal assembly  78  except that annular inner seal  82  is replaced by an annular inner seal  82 ′ and annular outer seal  84  is replaced by annular outer seal  84 ′. 
         [0037]    Annular inner seal  82 ′ is the same as annular inner seal  82  except for its cross sectional configuration. Annular inner seal  82 ′ is preferably manufactured from a polymer such as glass filled PTFE or Teflon® but any suitable polymer can be used. Annular inner seal  82 ′ is disposed within groove  88  formed by plate  80 . Annular inner seal  82 ′ engages non-orbiting scroll member  66  and plate  80  to form seal  92  which isolates fluid under intermediate pressure in the bottom of recess  76  from fluid under discharge pressure in recess  72 . Annular inner seal  82 ′ has a V-shaped cross-section with the opening between the legs of the V-shaped cross section being opened towards the discharge area of compressor  10  which is at a higher pressure than the intermediate pressurized fluid within recess  76 . This orientation for annular inner seal  82 ′ pressure energizes the legs of annular inner seal  82 ′ to improve its performance. 
         [0038]    Annular outer seal  84 ′ is the same as annular outer seal  84  except for its cross sectional configuration. Annular outer seal  84 ′ is preferably manufactured from a polymer such as glass filled PTFE or Teflon® but any suitable polymer can be used. Annular outer seal  84 ′ engages non-orbiting scroll member  66  and plate  80  to form seal  94  and isolate the intermediate pressurized gas within recess  76  from the suction area of compressor  10 . Annular outer seal  84 ′ has a V-shaped cross section with the opening between the legs of the V-shaped cross section being opened towards the intermediate pressurized fluid within recess  76  which is at a higher pressure than the pressurized fluid within the suction area of compressor  10 . This orientation for annular outer seal  84 ′ pressure energizes the legs of annular outer seal  84 ′ to improve its performance. 
         [0039]    The function, operation and benefits for floating seal assembly  78 ′ are the same as detailed above for floating seal assembly  78  and thus will not be repeated here. 
         [0040]    With reference to  FIG. 3 , a floating seal assembly  178  in accordance with another embodiment of the present invention is illustrated. Floating seal assembly  178  comprises a single metal plate  180 , an annular inner seal  182  and an annular outer seal  184 . Metal plate  180  is preferably manufactured from cast iron on powdered metal but any other material, metal or plastic, which meets the performance requirements for metal plate  180  may be utilized. Metal plate  180  includes an upwardly projecting planar sealing lip  186  which engages partition  22  to separate the discharge area of compressor  10  from the suction area of compressor  10 . 
         [0041]    Annular inner seal  182  is preferably manufactured from a polymer such as glass filled PTFE or Teflon® but any suitable polymer can be used. Annular inner seal  182  is disposed within a groove  188  formed by metal plate  180 . Annular inner seal  182  engages non-orbiting scroll member  66  and metal plate  180  to separate the discharge area of compressor  10  from the pressurized fluid within recess  76 . Annular inner seal  182  has an L-shaped cross-section with the inside surface of the L-shaped cross section facing the discharge area of compressor  10  which is at a higher pressure than the intermediate pressurized fluid within recess  76 . This orientation for annular inner seal  182  pressure energizes the legs of annular inner seal  182  to improve its performance. 
         [0042]    Annular outer seal  184  is preferably manufactured from a polymer such as glass filled PTFE on Teflon® but any suitable polymer can be used. Annular outer seal  184  is disposed within a groove  190  formed by metal plate  180 . Annular outer seal  184  engages non-orbiting scroll member  66  and metal plate  180  to separate the pressurized fluid within recess  76  from the suction area of compressor  10 . Annular outer seal  184  has an L-shaped cross-section with the inside surface of the L-shaped cross-section facing the intermediate pressurized fluid within recess  76  which is at a higher pressure the pressurized fluid within the suction area of compressor  10 . This orientation for annular outer seal  184  pressure energizes the legs of annular outer seal  184  to improve its performance. 
         [0043]    The overall seal assembly therefore provides three distinct seals, namely, an inside diameter seal at  92 , an outside diameter seal at  94  and a top seal at  96 . Seal  92  isolates fluid under intermediate pressure in the bottom of recess  76  from fluid under discharge pressure in recess  72 . Seal  94  isolates fluid under intermediate pressure in the bottom of recess  76  from fluid at suction pressure within shell  12 . Seal  96  isolates fluid at suction pressure within shell  12  from fluid at discharge pressure across the top of seal assembly  78 .  FIG. 3  illustrates wear ring  98  attached to partition  22  which provides seal  96  between plate  180  and wear ring  98 . In lieu of wear ring  98 , the lower surface of partition  22  can be locally hardened by nitriding, carbo-nitriding or other hardening processes known in the art. 
         [0044]    The diameter of seal  96  is chosen so that there is a positive upward sealing force on floating seal assembly  178  under normal operating conditions i.e. at normal pressure differentials. Therefore, when excessive pressure differentials are encountered, floating seal assembly  178  will be forced downwardly by discharge pressure, thereby permitting a leak of high side discharge pressure gas directly across the top of floating seal assembly  178  to a zone of low side suction gas. If this leakage is great enough, the resultant loss of flow of motor cooling suction gas (aggravated by the excessive temperature of the leaking discharge gas) will cause a motor protector (not shown) to trip, thereby de-energizing the motor. The width of seal  96  is chosen so that the unit pressure on the seal itself (i.e. between sealing lip  186  and wear ring  98 ) is greater than normally encountered discharge pressure, thus insuring consistent sealing. 
         [0045]    With reference to  FIG. 4 , a floating seal assembly  278  in accordance with another embodiment of the present invention is illustrated. Floating seal assembly  278  comprises a single metal plate  280 , an annular inner seal  282  and an annular outer seal  284 . Metal plate  280  is preferably manufactured from cast iron or powdered metal but any other material, metal or plastic, which meets the performance requirements for metal plate  280  may be utilized. Metal plate  280  includes an upwardly projecting planar sealing lip  286  which engages partition  22  to separate the discharge area of compressor  10  from the suction area of compressor  10 . 
         [0046]    Annular inner seal  282  is preferably manufactured from a polymer such as glass filled PTFE or Teflon® but any suitable polymer can be used. Annular inner seal  282  is disposed within a groove  288  formed by metal plate  280 . Annular inner seal  282  engages non-orbiting scroll member  66  and metal plate  280  to separate the discharge area of compressor  10  from the pressurized fluid within recess  76 . Annular inner seal  282  has an L-shaped cross-section when it is installed with the inside surface of the L-shaped cross-section facing the discharge area of compressor  10  which is at a higher pressure than the intermediate pressurized fluid within recess  76 . This orientation for annular inner seal  282  pressure energizes the legs of annular inner seal  282  to improve its performance. 
         [0047]    Annular outer seal  284  is preferably manufactured from a polymer such as glass filled PTFE or Teflon® but any suitable polymer can be used. Annular outer seal  284  is disposed within a groove  290  formed by metal plate  280 . Annular outer seal  284  engages non-orbiting scroll member  66  and metal plate  280  to separate the pressurized fluid within recess  76  from the suction area of compressor  10 . Annular outer seal  284  has an L-shaped cross-section when it is installed with the inside surface of the L-shaped cross-section facing the intermediate pressurized fluid within recess  76  which is at a higher pressure than the pressurized fluid within the suction area of compressor  10 . This orientation for annular outer seal  284  pressure energizes the legs of annular outer seal  284  to improve its performance. 
         [0048]    The overall seal assembly therefore provides three distinct seals, namely, an inside diameter seal at  92 , an outside diameter seal at  94  and a top seal at  96 . Seal  92  isolates fluid under intermediate pressure in the bottom of recess  76  from fluid under discharge pressure in recess  72 . Seal  94  isolates fluid under intermediate pressure in the bottom of recess  76  from fluid at suction pressure within shell  12 , seal  96  isolates fluid at suction pressure within shell  12  from fluid at discharge pressure across the top of seal assembly  78 .  FIG. 4  illustrates wear ring  98  attached to partition  22  which provides seal  96  between metal plate  280  and wear ring  98 . In lieu of wear ring  98 , the lower surface of partition  22  can be locally hardened by nitriding, carbo-nitriding or other hardening processes known in the art. 
         [0049]    The diameter of seal  96  is chosen so that there is a positive upward sealing force on floating seal assembly  278  under normal operating conditions i.e. at normal pressure differentials. Therefore, when excessive pressure differentials are encountered, floating seal assembly  278  will be forced downwardly by discharge pressure, thereby permitting a leak of high side discharge pressure gas directly across the top of floating seal assembly  278  to a zone of low side suction gas. If this leakage is great enough, the resultant loss of flow of motor cooling suction gas (aggravated by the excessive temperature of the leaking discharge gas) will cause a motor protector (not shown) to trip, thereby de-energizing the motor. The width of seal  96  is chosen so that the unit pressure on the seal itself (i.e. between sealing lip  286  and wear ring  98 ) is greater than normally encountered discharge pressure, thus insuring consistent sealing. 
         [0050]    With reference to  FIG. 5 , a floating seal assembly  378  in accordance with another embodiment of the present invention is illustrated. Floating seal assembly  378  comprises a single metal plate  380 , an annular inner seal  382  and an annular outer seal  384 . Metal plate  380  is preferably manufactured from cast iron or powdered metal but any other material, metal or plastic, which meets the performance requirements for plate  380  may be utilized. Plate  380  includes an upwardly projecting planar lip  386  which engages partition  22  to limit the movement of metal plate  380 . 
         [0051]    Annular inner seal  382  is preferably manufactured from a polymer such as glass filled PTFE or Teflon® but any suitable polymer can be used. Annular inner seal  382  is disposed within a groove  388  formed by plate  380 . Annular inner seal  382  engages non-orbiting scroll member  66  and plate  380  to separate the discharge area of compressor  10  from the pressurized fluid within recess  76 . Annular inner seal  382  has an L-shaped cross-section with the inside surface of the L-shaped cross section facing the discharge area of compressor  10  which is at a higher pressure than the intermediate pressurized fluid within recess  76 . This orientation for annular inner seal  382  pressure energizes the legs of annular inner seal  382  to improve its performance. 
         [0052]    Annular outer seal  384  is preferably manufactured from a polymer such as glass filled PTFE or Teflon® but any suitable polymer can be used. Annular outer seal  384  is disposed within a groove  390  formed by plate  380 . Annular outer seal  384  engages non-orbiting scroll member  66  and plate  380  to separate the pressurized fluid within recess  76  from the suction area of compressor  10 . Annular outer seal  384  has an L-shaped cross-section with the inside surface of the L-shaped cross-section facing the intermediate pressurized fluid within recess  76  which is at a higher pressure the pressurized fluid within the suction area of compressor  10 . This orientation for annular outer seal  384  pressure energizes the legs of annular outer seal  384  to improve its performance. 
         [0053]    Floating seal assembly  378  further comprises an annular seal  392 . Annular seal  392  is preferably manufactured from a polymer such as glass filled PTFE or Teflon® but any suitable polymer can be used. Annular seal  392  is disposed within a groove  394  formed by plate  380 . Annular seal  392  engages partition  22  and plate  380  to separate the discharge area of compressor  10  from the suction area of compressor  10 . Annular seal  392  has an L-shaped cross-section with the inside surface of the L-shaped cross-section facing the discharge area of compressor  10  which is at a higher pressure than the pressurized fluid within the suction area of compressor  10 . This orientation for annular seal  392  pressure energizes the legs of annular seal  392  to improve its performance. 
         [0054]    The overall seal assembly therefore provides three distinct seals, namely an inside diameter seal at  92 , an outside diameter seal at  94  and a top seal at  96 . Seal  92  isolates fluid under intermediate pressure in the bottom of recess  76  from fluid under discharge pressure in recess  72 . Seal  94  isolates fluid under intermediate pressure in the bottom of recess  76  from fluid at suction pressure within shell  12 . Seal  96  isolates fluid under discharge pressure in recess  72  from fluid at suction pressure within shell  12 .  FIG. 5  does not illustrate the incorporation of wear ring  98 . Because annular seal  392  provides top seal  96 , wear ring  98  and/or local hardening of partition  22  is not required. 
         [0055]    Referring now to  FIG. 6 , floating seal assembly  178  is illustrated incorporating a discharge valve assembly  400 . While discharge valve assembly  400  is illustrated in conjunction with floating seal assembly  178 , it is within the scope of the present invention to incorporate discharge valve assembly  400  into floating seal assemblies  78 ,  278  and  378  if desired. 
         [0056]    Discharge valve assembly  400  is disposed within the inner periphery of planar sealing lip  186 . Discharge valve assembly  400  includes a discharge valve base  430  which defines a plurality of apertures  432  which permit the flow of compressed gas from recess  72  into discharge muffler chamber  74 . A mushroom shaped valve retainer  434  is secured to a central aperture  436  disposed within valve base  430  by a threaded connection or by any other means known in the art. Disposed between valve base  430  and valve retainer  434  is an annular valve disc  438 . The diameter of valve disc  438  is large enough to cover the plurality of apertures  432  when valve disc  438  is seated on valve base  430 . The diameter of the upper portion of valve retainer  434  which is in contact with valve disc  438  is chosen to be less than and in a desirable proportion to the diameter of valve disc  438  to control the forces acting on the valve during the operation of compressor  10 . The diameter of the upper portion of valve retainer  434  is chosen to be between 50% and 100% of the diameter of valve disc  438 . In the preferred embodiment, the diameter of the upper portion of valve retainer  434  is chosen to be approximately 95% of the diameter of valve disc  438 . 
         [0057]    During operation of compressor  10 , it is undesirable for valve disc  438  to become dynamic under the flow pulsations that occur during extreme conditions of operation such as at high pressure ratio. The proper contact area between valve disc  438  and valve retainer  434  and a phenomenon known as “stiction” will prevent valve disc  438  from becoming dynamic. Stiction is a temporary time dependent adhesion of valve disc  438  to valve retainer  434  caused by surface tension of lubricating oil being disposed between them. 
         [0058]    Valve retainer  434  is provided with a central through aperture  440  which is sized to allow a proper amount of discharge gas to pass through valve retainer  434  when valve disc  438  closes apertures  432 . This flow of gas through valve retainer  434  limits the amount of vacuum which can be created during powered reverse rotation of compressor  10 . This powered reverse rotation can occur due to a three phase miswiring condition or it can occur due to various situations such as a blocked condenser fan where the discharge pressure builds up to a point of stalling the drive motor. If aperture  440  is chosen too small of a diameter, excess vacuum will be created during reverse operation. If aperture  440  is chose to large, reverse rotation of compressor  10  at shut down will not be adequately prevented. 
         [0059]    During normal operation of compressor  10 , valve disc  438  is maintained in an open position, as shown in  FIG. 6  and pressurized refrigerant flows from open recess  72 , through the plurality of apertures  432  and into discharge muffler chamber  74 . When compressor  10  is shut down either intentionally as a result of the demand being satisfied or unintentionally as a result of a power interruption, there is a strong tendency for the backflow of compressed refrigerant from discharge muffler chamber  74  and to a lesser degree for the gas in the pressurized chambers defined by scroll wraps  56  and  68  to effect a reverse orbital movement of orbiting scroll member  54 . Valve disc  438  is initially held in its open position due to stiction as described above. When compressor  10  is shut down, the forces due to the initial reverse flow of compressed refrigerant and, in this particular design to a lesser extent, those due to the force of gravity will eventually overcome the temporary time dependent “stiction” adhesion and valve disc  438  will drop onto valve base  430  and close the plurality of apertures  432  and stop the flow of compressed refrigerant out of discharge muffler chamber  74  except for the amount allowed to flow through aperture  440 . The limited flow through aperture  440  is not sufficient to prevent floating seal assembly  178  from dropping thus enabling the breaking of seal  96  and allowing refrigerant at discharge pressure to flow to the suction pressure area of compressor  10  to equalize the two pressures and stop reverse rotation of orbiting scroll member  54 . 
         [0060]    Thus, floating seal assembly  178  which includes valve base  430 , valve retainer  434  and valve disc  438  limits the amount of pressurized refrigerant that is allowed to backflow through compressor  10  after shut down. This limiting of refrigerant backflow has the ability to control the shut down noise without having an adverse impact on the performance of compressor  10 . The control of shut down noise is thus accomplished in a simple and low cost manner. 
         [0061]    During powered reversals, aperture  440  allows sufficient refrigerant backflow to limit any vacuum from being created and thus provides sufficient volume of refrigerant to protect scroll members  54  and  66  until the motor protector trips and stops compressor  10 . 
         [0062]    Referring now to  FIG. 7 , floating seal assembly  178  is illustrated incorporating a temperature protection system  500  and a pressure protection system  700 . While temperature protection system  500  is illustrated in conjunction with floating seal assembly  178 , it is within the scope of the present invention to incorporate temperature protection system  500  into floating seal assemblies  78 ,  278  and  378  if desired. 
         [0063]    Temperature protection system  500  comprises a circular valve cavity  506  disposed within plate  180 . The bottom of cavity  506  communicates with an axial passage  510  of circular cross-section which is in turn in communication with a radial passage  512 . The radially outer outlet end of passage  512  is in communication with the suction gas area within shell  12 . The intersection of passage  510  and the planar bottom of cavity  506  define a circular valve seat in which is normally disposed the spherical center valving portion of a circular slightly spherical relatively thin saucer-like bi-metallic valve  514  having a plurality of through holes disposed radially outwardly of the spherical valving portion. 
         [0064]    Valve  514  is retained in place by a cup-shaped retainer  520  which has an open center portion and a radially outwardly extending flange  522 . After valve  514  is assembled in place, retaining ring  520  is pushed over a cylindrical surface  524  formed on plate  180  to retain the assembly of valve  514 . 
         [0065]    Being disposed adjacent discharge gas recess  72 , temperature protection system  500  is fully exposed to the temperature of the discharge gas very close to where it exits scroll wraps  56  and  68 . The closer the location at which the discharge gas temperature is sensed is to the actual discharge gas temperature existing in the last scroll compression bucket, the more accurately the machine will be controlled in response to discharge temperature. The materials of bi-metallic valve  514  are chosen, using conventional criteria, so that when discharge gas reaches a predetermined temperature, valve  514  will “snap” into its open position in which it is slightly concave upwardly with its outer periphery engaging the bottom of cavity  506  and its center valving portion elevated away from the valve seat. In this position, high pressure discharge gas can leak through the holes in valve  514  and passages  510  and  512  to the interior of shell  12  at suction pressure. This leakage causes the discharge gas to be recirculated thus reducing the inflow of cool suction gas as a consequence of which, the motor loses its flow of cooling fluid, i.e. the inlet flow of relatively cool suction gas. A motor protector (not shown) will heat up due to both the presence of relatively hot discharge gas and the reduced flow of cooling gas. The motor protector will eventually trip thus shutting down compressor  10 . When temperature protection system  500  is closed, discharge gas flows from recess  72  through one or more apertures  532 , through partition  22  and into discharge muffler chamber  74 . Pressure protection system  700  as discussed below with reference to  FIGS. 9 ,  10 A and  10 B can be incorporated with floating seal assembly  378  as illustrated in  FIG. 7 . 
         [0066]    Referring now to  FIG. 8 , floating seal assembly  178  is illustrated incorporating a pressure protection system  600 . While pressure protection system  600  is illustrated in conjunction with floating seal assembly  178 , it is within the scope of the present invention to incorporate pressure protection system  600  into floating seal assemblies  78 ,  278  and  378  if desired. 
         [0067]    Pressure protection system  600  comprises a valve cavity  606  disposed within plate  180 . The bottom of cavity  606  communicates with an axial passage  610  of circular cross-section which is in turn in communication with a radial passage  612 . The radially outer end of passage  612  is in communication with the suction gas area within shell  12 . 
         [0068]    A pressure responsive valve  614  is disposed within cavity  606  by being press fit, by being threaded or by other means known in the art. Pressure responsive valve  614  comprises an outer housing  616  defining a stepped fluid passage  618 , a ball  620 , an inner housing  622 , a biasing member  624  and a spring seat  626 . Outer housing  616  is secured within cavity  606  such that stepped fluid passage  618  is in communication with discharge muffler chamber  74  and axial passage  610 . Ball  620  is disposed within stepped fluid passage  618  and under normal conditions, ball  620  engages a valve seat defined by stepped fluid passage  618 , inner housing  622  is disposed below ball  620 , biasing member  624  is disposed below inner housing  622  and spring seat  626  is disposed below biasing member  624 . Biasing member  624  biases inner housing  622  against ball  620  and ball  620  against the valve seat defined by stepped fluid passage  618  to close stepped fluid passage  618  during normal operating conditions for compressor  10 . Discharge gas flows from recess  72  through one or more apertures  632 , through partition  22  and into discharge muffler chamber  74 . 
         [0069]    When fluid pressure within discharge muffler chamber  74  exceeds a predetermined value, the fluid pressure acting against ball  620  will overcome the biasing load of biasing member  624  and ball  620  will be moved off of the valve seat defined by stepped fluid passage  618 . In this position, high pressure discharge gas will pass through stepped fluid passage  618  and through passages  610  and  612  to the interior of shell  12  at suction pressure. This leakage causes the discharge gas to be recirculated thus reducing the inflow of cool suction gas as a consequence of which, the motor loses its flow of cooling fluid i.e. the inlet flow of relatively cool suction gas. A motor protector (not shown) will heat up due to both the presence of relatively hot discharge gas and the reduced flow of cooling gas. The motor protector will eventually trip thus shutting down compressor  10 . 
         [0070]    Referring now to  FIGS. 9 ,  10 A and  10 B, floating seal assembly  78  is illustrated incorporating pressure protection system  700 . While pressure protection system  700  is illustrated in conjunction with floating seal assembly  78 , it is within the scope of the present invention to incorporate pressure protection system  700  into floating seal assembly  178 ,  278  and  378  if desired. 
         [0071]    Pressure protection system  700  comprises a fluid passage  704  and a valve cavity  706  disposed within plate  80 . Fluid passage  704  extends between recess  76  and valve cavity  706 . One end of valve cavity  706  is in communication with the suction area of compressor  10  within shell  12 . The other end of valve cavity  706  is in communication with gas at discharge pressure within recess  72 . 
         [0072]    A pressure responsive valve  714  is disposed within cavity  706  by being press fit, by being threaded or by other means known in the art. Pressure responsive valve  714  comprises an outer housing  716  defining a stepped fluid passage  718 , a ball  720 , an inner housing  722  a biasing member  724  and a spring seat  726 . Outer housing  716  is secured within cavity  706  such that stepped fluid passage  718  is in communication with recess  72  at one end and in communication with gas at suction pressure within shell  12  at its opposite end. A radial passage  728  extends between recess  76  and stepped fluid passage  718 . Ball  720  is disposed within stepped fluid passage  718  adjacent the valve seat and under normal operating conditions ball  720  engages the valve seat to close stepped fluid passage  718 . Inner housing  722  is disposed adjacent ball  720  and it defines a radial passage  730  whose function is described below. Biasing member  724  is disposed adjacent inner housing  722  and spring seat  726  is disposed adjacent biasing member  724 . As illustrated in  FIG. 10A , biasing member  724  biases inner housing  722  against ball  720  and ball  720  against the valve seat defined by stepped fluid passage  718  during normal operations of compressor  10 . In this position, radial passage  730  is out of alignment with radial passage  728  and fluid flow from recess  76  to the suction area of compressor  10  is prohibited. 
         [0073]    When fluid pressure within recess  72  exceeds a predetermined value, the fluid pressure acting against ball  720  will overcome the biasing load of biasing member  724  and ball  720  along with inner housing  722  will be moved to the position illustrated in  FIG. 10B . In this position, radial passage  730  will align with radial passage  728  and intermediate pressurized gas within recess  76  will be vented to the suction area of compressor  10  within shell  12 . The loss of the intermediate pressurized gas within recess  76  will cause floating seal assembly  78  to drop thus breaking seal  96  between plate  80  and wear ring  98  and allowing discharge gas to leak to suction. In addition, the biasing load urging non-orbiting scroll member  66  into engagement with orbiting scroll member  54  will decrease creating a fluid leak between the discharge and suction areas of compressor  10  across the tips of scroll wraps  56  and  68 . This leakage from discharge to suction causes the discharge gas to be recirculated thus reducing the inflow of cool suction gas as a consequence of which the motor loses its flow of cooling fluid i.e. the inlet flow of relatively cool suction gas. A motor protector (not shown) will heat up due to both the presence of relatively hot discharge gas and the reduced flow of cooling gas. The motor protector will eventually trip thus shutting down compressor  10 . 
         [0074]    Referring now to  FIGS. 11A and 11B , an annular inner seal  82 ″ in accordance with another embodiment of the present invention is illustrated.  FIG. 11A  illustrates annular inner seal  82 ″ in its formed condition and  FIG. 11B  illustrates annular inner  82 ″ in its assembled condition. Annular inner seal  82 ″ is a direct replacement for annular inner seal  82  illustrated in  FIGS. 1 and 2  and thus the description of  FIGS. 1 and 2  including the discussion of annular inner seal  82  apply also to annular inner seal  82 ″. 
         [0075]    Annular inner seal  82 ″ is preferably manufactured from a polymer such as glass filled PTFE or Teflon® but any suitable polymer can be used. Annular inner seal  82 ″ is designed to be disposed within groove  88  formed by plate  80 . Annular inner seal  82 ″ engages non-orbiting scroll member  66  and plate  80  to separate the discharge area of compressor  10  from the intermediate pressurized fluid within recess  76 . 
         [0076]    When assembled, annular inner seal  82 ″ has a U-shaped cross-section with the opening between the legs of the U-shaped cross-section being open towards the discharge area of compressor  10  which is at a higher pressure than the intermediate pressurized fluid within recess  76  during normal operation of compressor  10 . This orientation for annular inner seal  82 ″ energizes the legs of annular inner seal  82 ″ as well as urging annular inner seal  82 ″ into contact with the lower surface  88 ″ of groove  88  to improve its performance. 
         [0077]    Annular inner seal  82 ″ defines a plurality of notches  84 ″ which extend through the end of the leg in contact with metal plate  80  as illustrated in  FIG. 11B . Notches  84 ″ act as a vent to relieve fluid pressure within recess  76  during a flooded start of compressor  10 . 
         [0078]    During a flooded start of compressor  10 , recess  76  will contain liquid refrigerant. Compressor  10  has the capability of the flooded start due to the radial compliancy, built into compressor  10 . During the flooded start of compressor  10 , the liquid refrigerant within recess  76  flashes off to create a fluid pressure within recess  76  that is greater than the fluid pressure within discharge muffler chamber  74 . This increased pressure will lift annular inner seal  82 ″ away from lower surface  88 ″ as shown in  FIG. 11B . Notches  84 ″ help to create a flow path depicted by arrow  90 ″ which bleeds the excessive pressurized fluid off to discharge muffler chamber  74 . When fluid pressure within discharge muffler chamber  74  exceeds fluid pressure within recess  76 , annular inner seal  82 ″ will again be urged against lower surface  88 ″. This additional sealing point in conjunction with the energizing of the legs of annular inner seal  82 ″ will minimize any effect notches  84 ″ will have on the sealing by annular inner seal  82 ″ during normal operation of compressor  10 . 
         [0079]    While notches  84 ″ have been illustrated and described in relation to annular inner seal  82 ″, it is within the scope of the present invention to incorporate notches  84 ″ into annular inner seal  82 ′, annular inner seal  182 , annular inner seal  282  or annular inner seal  382  if desired. 
         [0080]    The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.