Abstract:
A compressor assembly includes a shell which defines a discharge chamber. A discharge valve assembly is attached to the shell in communication with the discharge chamber. The discharge valve assembly includes a stamped or coined valve seat, a drawn tubular element and a stamped valve member. The stamping, drawing and coining operations used to manufacture the discharge valve assembly significantly reduce the manufacturing costs for the discharge valve assembly.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention relates generally to discharge valves for compressors. More particularly, the present invention relates to scroll compressors incorporating discharge valves having stamped valve plates.  
         BACKGROUND AND SUMMARY OF THE INVENTION  
         [0002]    Scroll type machines are becoming more and more popular for use as compressors in both refrigeration as well as air conditioning applications due primarily to their capability for extremely efficient operation. Generally, these machines incorporate a pair of intermeshed spiral wraps, one of which is caused to orbit relative to the other so as to define one or more moving chambers which progressively decrease in size as they travel from an outer suction port toward a center discharge port. An electric motor is provided which operates to drive the orbiting scroll member via a suitable drive shaft. Because scroll compressors depend upon a seal created between opposed flank surfaces of the wraps to define successive chambers for compression, suction and discharge valves are generally not required. However, when such compressors are 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 backflow of compressed gas from the system in combination with high pressure gas contained in the chambers and/or discharge muffler to effect a reverse orbital movement of the orbiting scroll member and associated drive shaft. This reverse movement often generates objectionable noise or rumble. Further, in machines employing a single phase drive motor, it is possible for the compressor to begin running in the reverse direction should a momentary power failure be experienced.  
           [0003]    In order to limit such reverse rotation, prior art scroll compressors have incorporated ball type check valves at the point of connection between the outer shell and the discharge line. While such ball type check valves have been effective to limit back flow of compressed refrigerant, they have demonstrated a tendency to vibrate or chatter under certain flow conditions thus presenting a further source of objectionable noise. Also, in severe situations, the chattering may result in damage or destruction of the ball stop and/or seat. Additionally, the occasional discharge of liquid through such ball type check valves further increases the possibility of damage thereto.  
           [0004]    Other prior art scroll compressors incorporate disc type check valve in the outlet from the outer shell which effectively prevents return flow of compressed gas from the refrigeration system and hence limits reverse orbital movement of the orbiting scroll member. Because reverse orbital movement is thus limited, the possibility of objectionable noise being generated thereby upon shut down of the compressor is greatly reduced. The disc type discharge valve does not require any biasing means but rather operates to create a pressure differential thereacross which moves the disc between seated and unseated positions. The disc type discharge valve provides an inexpensive, easily installed means to effectively resist reverse movement of the orbiting scroll. Further, because a relatively large stop surface area is provided extending around the periphery of the valve member, the possibility of damage from discharge of liquid therethrough is greatly reduced.  
           [0005]    While the above described disc valves have performed satisfactorily, the manufacture of the individual components of the disc type check valve required the machining of a housing and the machining or powder metal forming of one or more of the valve components. Both of these forming operations are relatively expensive leading to an increase in the manufacturing costs. The present invention overcomes the problems associated with the relatively expensive forming operations by providing a disc type check valve assembly where all of the components of the check valve assembly are manufactured by using a relatively lower cost stamping process or a powdered metal process. In one embodiment, one of the valve members is integral with the shell of the compressor.  
           [0006]    Other advantages and objects of the present invention will become apparent to those skilled in the art from the subsequent detailed description, appended claims and drawings. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0007]    In the drawings which illustrate the best mode presently contemplated for carrying out the present invention:  
         [0008]    [0008]FIG. 1 is a side elevational view, partially in cross section of a hermetically sealed compressor incorporating a disc type discharge valve assembly in accordance with the present invention;  
         [0009]    [0009]FIG. 2 is an enlarged cross section view of the disc type discharge valve assembly shown in FIG. 1;  
         [0010]    [0010]FIG. 3 is a cross section view of the discharge valve assembly shown in FIG. 2 taken along line  3 - 3  thereof;  
         [0011]    [0011]FIG. 4 is a cross section view of the discharge valve assembly shown in FIG. 2 taken along line  4 - 4  thereof;  
         [0012]    [0012]FIG. 5 is an enlarged cross section similar to that of FIG. 2 illustrating a disc type discharge assembly in accordance with another embodiment of the present invention;  
         [0013]    [0013]FIG. 6 is an enlarged cross section similar to that of FIG. 2 illustrating a disc type discharge assembly in accordance with another embodiment of the present invention;  
         [0014]    [0014]FIG. 7 is an enlarged cross section similar to that of FIG. 2 illustrating a disc type discharge assembly in accordance with another embodiment of the present invention;  
         [0015]    [0015]FIG. 8 is an enlarged cross section similar to that of FIG. 2 illustrating a disc type discharge assembly in accordance with another embodiment of the present invention;  
         [0016]    [0016]FIG. 9 is an enlarged cross section similar to that of FIG. 2 illustrating a disc type discharge assembly in accordance with another embodiment of the present invention;  
         [0017]    [0017]FIG. 10 is an enlarged cross section similar to that of FIG. 2 illustrating a disc type discharge assembly in accordance with another embodiment of the present invention;  
         [0018]    [0018]FIG. 11 is an enlarged cross section similar to that of FIG. 2 illustrating a disc type discharge assembly in accordance with another embodiment of the present invention;  
         [0019]    [0019]FIG. 12 is an enlarged cross section similar to that of FIG. 2 illustrating a disc type discharge assembly in accordance with another embodiment of the present invention;  
         [0020]    [0020]FIG. 13 is an enlarged cross section similar to that of FIG. 2 illustrating a disc type discharge assembly in accordance with another embodiment of the present invention;  
         [0021]    [0021]FIG. 14 is an enlarged cross section similar to that of FIG. 2 illustrating a disc type discharge assembly in accordance with another embodiment of the present invention;  
         [0022]    [0022]FIG. 15 is an enlarged cross-section similar to that of FIG. 14 illustrating an alternative welding operation; and  
         [0023]    [0023]FIG. 16 is an enlarged cross section similar to that of FIG. 2 illustrating a disc type discharge assembly in accordance with another embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0024]    The present invention is illustrated for exemplary purposes in conjunction with a hermetically sealed scroll compressor. It is to be understood that the present invention is not limited to a scroll compressor and that it is possible to use the disc type discharge valve assembly of the present invention on virtually any type of motor compressor or similar machine.  
         [0025]    Referring now to the drawings in which like reference numerals designate like or corresponding parts throughout the several views, there is shown in FIG. 1, a scroll compressor including the disc type discharge valve assembly in accordance with the present invention which is designated generally by the reference numeral  10 . Compressor  10  is comprised of a hermetic shell assembly  12 , a compressor section  14  and a motor drive section  16 . Hermetic shell assembly  12  is comprised of a lower shell  18 , an upper cap  20 , a bottom cover  22  and a partition plate  24 . Bottom cover  22 , lower shell  18 , partition plate  24  and upper cap  20  are fixedly and sealingly attached in the manner shown in FIG. 1 by welding during the assembly of compressor  10  to form a sealed suction chamber  26  and a sealed discharge chamber  28 . Hermetic shell assembly  12  further includes a suction inlet fitting  30  in communication with suction chamber  26  and a disc type discharge valve assembly  32  in communication with discharge chamber  28 .  
         [0026]    Compressor section  14  is comprised of a non-orbiting scroll member  34 , an orbiting scroll member  36  and a bearing housing  38 . Non-orbiting scroll member  34  includes an end plate and body  40  having a chamber  42  within which is disposed a spiral wrap  44 . Non-orbiting scroll member  34  further includes a plurality of embossments  46  which are adapted to be attached to bearing housing  38  by a plurality of bolts  48 .  
         [0027]    Orbiting scroll member  36  includes an end plate  50  and a spiral wrap  52  which extends upright from end plate  50  into chamber  42 . Spiral wrap  52  is meshed with spiral wrap  44  on non-orbiting scroll member  34  in the usual manner to form in combination with bearing housing  38  a portion of compressor section  14  of compressor  10 . At least one closed chamber  54  is defined by meshing wraps  44  and  52  with a discharge port  56  formed in the central portion of non-orbiting scroll member  34 . Discharge port  56  communicates with discharge chamber  28  formed by partition plate  24  and upper cap  20 .  
         [0028]    Bearing housing  38  includes a plurality (typically 3 or 4) of radially outwardly extending arms  58  affixed to hermetic shell assembly  12 . Arms  58  of bearing housing  38  align with embossments  46  on non-orbiting scroll member  34  and they each include a threaded hole  60  for accepting bolts  48  to attach non-orbiting scroll member  34  to bearing housing  38  as described above.  
         [0029]    Compressor section  14  further includes a crankshaft  62  having an eccentric shaft portion  64 . Eccentric shaft portion  64  is coupled to orbiting scroll member  36  through a drive bushing and bearing assembly  66 . An upper counter balance weight  68  is fixed to crankshaft  62 . Crankshaft  62  extends into motor drive section  16  and is supported at its lower end by a lower bearing assembly  70 . Lower bearing assembly  70  includes a plurality (typically 3 or 4) of radially outwardly extending arms  72  fixedly secured to shell assembly  12 . A central portion of lower bearing assembly  70  includes an elongated bore  76  within which is disposed a journal bearing  78  which receives the lower end of crankshaft  62 .  
         [0030]    Motor drive section  16  comprises a motor stator  80  and a motor rotor  82 . Motor stator  80  is securely mounted within lower shell  18  of shell assembly  12 , preferably by press fitting. Motor rotor  82  is coupled to crankshaft  62  and with crankshaft  62  rotates within motor stator  80 . Motor stator  80  and motor rotor  82  thus operate to rotate crankshaft  62  to cause orbiting scroll member  36  to orbit with respect to non-orbiting scroll member  34  thereby causing the at least one closed chamber  54  to form at an outer suction port and for chamber  54  to progressively decrease in size as it travels towards center discharge port  56  where it is discharged into discharge chamber  28 . A floating seal  84  seals the interface between suction chamber  26  and discharge chamber  28 .  
         [0031]    The embodiments shown in FIGS.  2 - 9  illustrate a valve plate which defines a valve seat which has been formed by a powdered metal, a stamping and/or coining process. The coining operation for the valve seat is an inexpensive process which produces a finished planar surface for the valve seat allowing the valve member to sealingly engage the valve seat to prohibit flow of the discharge gas. Thus, a significant cost savings and simplification of the compressor assembly can be achieved by incorporating the coining of the valve seat.  
         [0032]    Referring now to FIGS.  2 - 4 , discharge check valve assembly  32  comprises a discharge valve plate  90 , an elongated tubular member  92  and a valve member  94 . Discharge valve plate  90  is formed as an integral part of upper cap  20  of shell assembly  12  by a stamping and/or coining operation. Valve plate  90  has a plurality (three as shown in FIG. 3) of substantially identical arcuate cutout portions  96  provided therein. A substantially planar surface portion surrounds the plurality of cutout portions  96  to form a valve seat  98  for sealing engagement with valve member  94 .  
         [0033]    Elongated tubular member  92  has a generally radially outwardly extending annular flange  100  which is adapted to abut and be welded to the outer surface of upper cap  20 . In order to aid in the welding process and ensure a secure fluid-tight seal, an annular axially outwardly projecting rib  102  is provided on flange  100 . During the welding operation, rib  102  becomes sacrificial to supply a portion of the weld material as is well known in the art. Tubular member  92  can be welded to upper cap  20  by friction welding, resistance welding, laser welding, electron beam welding or any other welding technique know in the art. Tubular member  92  has a generally radially inwardly extending flange  104  which with valve plate  90  forms a chamber  106  within which valve member  94  is located. Flange  104  provides an annular stop surface or shoulder for restricting the movement of valve member  94 . The end of tubular member  92  opposite to flange  100  defines an enlarged diameter end  108  which is adapted to be connected to a suitable conduit (not shown) of the refrigeration system with which compressor  10  is to be utilized. Thus, tubular member  92  provides a discharge fluid passage between discharge chamber  28  and the refrigeration system.  
         [0034]    Valve member  94  is disposed within chamber  106  and is sized so as to be freely movable between valve seat  98  and flange  104 . Valve member  94  has a center opening  110  of substantial diameter through which the compressed fluid is allowed to flow when valve member  94  is spaced from valve seat  98  or when valve member  94  abuts flange  104 . When valve member  94  abuts valve seat  98 , the diameter of opening  110  is such that fluid communication through the plurality of cutout portions  96  is prohibited.  
         [0035]    Preferably, tubular member  92  and valve member  94  are fabricated from sheet metal such as steel whereas valve plate  90  is formed as an integral part of upper cap  20 . Tubular member  92  may also be formed from copper or other materials as dictated by the system requirements with which compressor  10  is to be utilized.  
         [0036]    In operation, with compressor  10  running, the pressure within discharge chamber  28  will be above the pressure that exists down stream of discharge check valve assembly  32  and thus, the compressed fluid will flow through openings  96  to thereby cause valve member  94  to move towards flange  104 , or to an open position, whereby the compressed gas may flow through opening  110  to the refrigeration system. Opening  110  is slightly smaller than the inside diameter of tubular member  92  and thus a pressure differential will exist across valve member  94  which will serve to retain valve member  94  against flange  104  thus preventing the possibility of chattering. When compressor  10  is shut down, the pressure within discharge chamber  28  may decrease below the pressure that exists downstream of valve assembly  32 . Under these conditions, the pressure drop across opening  110  in valve member  94  will result in a net force thereon causing valve member  94  to move against valve seat  98  of valve plate  90 , or to a closed position, where valve member  94  overlies openings  96  thereby preventing backflow of the compressed gas into discharge chamber  28 .  
         [0037]    Referring now to FIG. 5, a discharge valve assembly  132  according to another embodiment of the present invention is illustrated. Valve assembly  132  is shown welded to an upper cap  120  having an aperture  122  extending therethrough. Upper cap  120  is interchangeable with upper cap  20  shown in FIGS.  1 - 4 . Valve assembly  132  comprises a discharge valve plate  140 , an elongated tubular member  142  and valve member  94 . Discharge valve plate  140  is formed as a separate component by a stamping and/or coining operation and has the plurality of cutout portions  96  therein as well as valve seat  98  for sealing engagement with valve member  94 . Discharge valve plate  140  has a generally radially outwardly extending annular flange  146  which is adapted to abut and be welded to tubular member  142 . In order to aid in the welding process and ensure a secure fluid tight seal, an axially extending rib  148  is provided on flange  146 . During the welding operation, rib  148  becomes sacrificial to supply a portion of the weld material as is well known in the art.  
         [0038]    Tubular member  142  has a generally radially outwardly extending annular flange  150  which is adapted to abut both annular flange  146  and the inner surface of upper cap  120 . Annular flange  150  is also adapted to be welded to the inner surface of upper cap  120 . In order to aid in the welding process and ensure a secure fluid tight seal, an axially outwardly projecting rib  152  is provided on flange  100 . During the welding operation, rib  152  becomes sacrificial to supply a portion of the weld material as is well know in the art. Rib  152  is shown as being larger in diameter than rib  148 . It is within the scope of the present invention to have rib  152  smaller in diameter than rib  148  or to have rib  152  as the same diameter as rib  148  in order to facilitate the welding of valve plate  140  to tubular member  142  and tubular member  142  to the inner surface of upper cap  120 . Tubular member  142  has a generally radially inwardly extending flange  154  which with valve plate  140  forms a chamber  156  within which valve member  94  is located. Flange  154  provides an annular stop surface or shoulder for restricting the movement of valve member  94 . The end of tubular member  142  opposite to flange  150  defines enlarged diameter end  108  which, as described above, is adapted to be connected to the suitable conduit of the refrigeration system with which compressor  10  is to be utilized.  
         [0039]    Valve member  94  is disposed within chamber  156  and is sized so as to be freely movable between valve seat  98  and flange  154 . The movement, function and operation of valve member  94  in discharge valve assembly  132  is the same as that described above for the embodiment shown in FIGS.  1 - 4 .  
         [0040]    Referring now to FIG. 6, a discharge valve assembly  132 ′ according to another embodiment of the present invention is illustrated. Valve assembly  132 ′ is shown welded to upper cap  120  extending through aperture  122 . Valve assembly  132 ′ is similar to valve assembly  132  shown in FIG. 5 except that discharge valve plate  140  has been replaced with discharge valve plate  140 ′. Discharge valve plate  140 ′ is also formed by a stamping and/or coining operation and is similar to discharge valve plate  140  except that the center portion of valve plate  140 ′ includes a domed contour  160  in place of the generally planar center portion of valve plate  140 . Domed contour  160  provides rigidity to valve seat  98  allowing it to maintain its generally planar characteristic and thus improving the sealing relation between valve seat  98  and valve member  94 . The function and operation of valve assembly  132 ′ is the same as valve assembly  132  shown in FIG. 5.  
         [0041]    Referring now to FIG. 7, a discharge valve assembly  182  according to another embodiment of the present invention is illustrated. Valve assembly  182  is shown welded to upper cap  120  extending out of aperture  122 . Valve assembly  182  comprises a discharge valve plate  190 , an elongated tubular member  192  and valve member  94 . Discharge valve plate  190  is a generally cup shaped plate formed as a separate component by a stamping and/or coining operation and has the plurality of cutout portions  96  therein as well as valve seat  98  for sealing engagement with valve member  94 . Discharge valve plate  190  has a generally radially outwardly extending annular flange  196  which is adapted to abut and be welded to the outer surface of upper cap  120 . In order to aid in the welding process and ensure a secure fluid tight seal, an axially extending rib  198  is provided on flange  196 . During the welding operation, rib  198  becomes sacrificial to supply a portion of the weld material as is well known in the art.  
         [0042]    Tubular member  192  has a generally outwardly extending annular flange  200  which is adapted to abut and be welded to annular flange  196  of valve plate  190 . In order to aid in the welding process and ensure a secure fluid tight seal, an axially outwardly projecting rib  202  is provided on flange  200 . During the welding operation, rib  202  becomes sacrificial to supply a portion of the weld material as is well known in the art. Rib  202  is shown as being larger in diameter than rib  198 . It is within the scope of the present invention to have rib  202  smaller in diameter than rib  198  or to have rib  202  the same diameter as rib  198  in order to facilitate the welding the tubular member  192  to valve plate  190  and valve plate  190  to the outer surface of upper cap  120 . Tubular member  192  has a generally radially inwardly extending flange  204  which with valve plate  190  forms a chamber  206  within which valve member  94  is located. Flange  204  provides an annular stop surface or shoulder for restricting the movement of valve member  94 . The end of tubular member  192  opposite to flange  200  defines enlarged diameter end  108  which, as described above, is adapted to be connected to the suitable conduit of the refrigeration system with which compressor  10  is to be utilized. In order to ensure fluid tightness between valve plate  190  and tubular member  192 , a laser welding operation can be performed circumferentially around the seam  206  formed by the mating of valve plate  190  and tubular member  192 .  
         [0043]    Valve member  94  is disposed within chamber  206  and is sized so as to be readily movable between valve seat  98  and flange  204 . The movement, function and operation of valve member  94  in discharge valve assembly  182  is the same as that described above for the embodiment shown in FIGS.  1 - 4 .  
         [0044]    Referring now to FIG. 8, a discharge valve assembly  232  according to another embodiment of the present invention is illustrated. Valve assembly  232  is shown welded to upper cap  120  on opposite sides of aperture  122 . Valve assembly  232  comprises a discharge valve plate  240 , an elongated tubular member  242  and valve member  94 . Discharge valve plate  240  is a generally cup shaped plate formed as a separate component by a stamping and/or coining operation and has the plurality of cutout portions  96  therein as well as valve seat  98  for sealing engagement with valve member  94 . Discharge valve plate  240  has a generally radially outwardly extending annular flange  246  which is adapted to abut and be welded to the inner surface of upper cap  120 . In order to aid in the welding process and ensure a secure fluid tight seal, an axially extending rib  248  is provided on flange  246 . During the welding operation, rib  248  becomes sacrificial to supply a portion of the weld material as is well known in the art.  
         [0045]    Tubular member  242  has a generally outwardly extending annular flange  250  which is adapted to abut and be welded to the outer surface of upper cap  120 . In order to aid in the welding process and ensure a secure fluid tight sea, an axially outwardly projecting rib  252  is provided on flange  200 . During the welding operation, rib  252  becomes sacrificial to supply a portion of the weld material as is well known in the art. The end of tubular member  242  opposite to flange  150  defines enlarged diameter end  108  which, as described above, is adapted to be connected to the suitable conduit of the refrigeration system with which compressor  10  is to be utilized.  
         [0046]    Valve member  94  is disposed within a chamber  256  formed by valve plate  240  and upper cap  120 . Upper cap  120  provides an annular stop surface or shoulder for restricting the movement of valve member  94 . Valve member  94  is sized so as to be freely movable between valve seat  98  and upper cap  120 . The movement function and operation of valve member  94  in discharge valve assembly  232  is the same as that described above for the embodiment shown in FIGS.  1 - 4 .  
         [0047]    Referring now to FIG. 9, a discharge valve assembly  232 ′ according to another embodiment of the present invention is illustrated. Valve assembly  232 ′ is shown welded to upper cap  120  extending through aperture  122 . Valve assembly  232 ′ is similar to valve assembly  232  shown in FIG. 8 except that tubular member  242  has been replaced with tubular member  242 ′. Tubular member  242 ′ is similar to tubular member  242  except that annular flange  250  and rib  252  have been replaced with annular flange  250 ′ and rib  252 ′. Annular flange  250 ′ is adapted to abut and be welded to the inner surface of upper cap  120  radially inward of valve plate  240 . Rib  252 ′ aids in the welding process to ensure a secure fluid type seal. During the welding operation, rib  252 ′ becomes sacrificial to supply a portion of the weld material as is well know in the art. Valve member  94  is disposed within a chamber  256 ′ formed by valve plate  240  and tubular member  242 ′. Flange  250 ′ of tubular member  242 ′ provides an annular stop surface or shoulder for restricting the movement of valve member  94 . Valve member  94  is sized so as to be freely movable between valve seat  98  and flange  250 ′. The movement, function and operation of valve member  94  in discharge valve assembly  232 ′ is the same as that described above for the embodiment shown in FIGS.  1 - 4 .  
         [0048]    Referring now to FIG. 10, a discharge valve assembly  282  according to another embodiment of the present invention is illustrated. Valve assembly  282  is shown welded to upper cap  120  extending through aperture  122 . Discharge valve assembly  282  comprises a discharge valve plate assembly  290 , a tubular member  292  and valve member  94 . Discharge valve plate assembly  290  comprises a discharge valve plate  294  and a tubular element  296 . Valve plate  294  is formed preferably from powdered metal and has the plurality of cutout portions  96  therein as well as valve seat  98 . Valve plate  294  is secured to tubular element  296  by a forming operation which sandwiches valve plate  294  within an annular groove  298  of tubular element  296 . Tubular element  296  is secured to tubular element  292  by a brazing operation.  
         [0049]    Tubular member  292  comprises a steel drawn tubular fitting  300  and a tubular element  302 . Steel fitting  300  is preferably friction welded to upper cap  120  to provide a secure fluid tight seal. Steel drawn fitting  300  includes a reduced diameter portion  304  upon which tubular element  296  of valve plate assembly  290  is brazed. Reduced diameter portion  304  provides an annular stop surface or shoulder for restricting the movement of valve member  94 . Tubular element  302  is brazed to an internal diameter  306  of fitting  300 . The end of tubular element  302  opposite to fitting  300  defines enlarged diameter end  108  which, as described above, is adapted to be connected to the suitable conduit of the refrigeration system with which compressor  10  is to utilized.  
         [0050]    Valve member  94  is disposed within a chamber  308  formed by valve plate assembly  290  and tubular member  292 . Valve member  94  is sized so as to be freely movable between valve seat  98  and fitting  300 . The movement, function and operation of valve member  94  in discharge valve assembly  282  is the same as that described above for the embodiment shown in FIGS.  1 - 4 .  
         [0051]    Referring now to FIG. 11, a discharge valve assembly  332  according to another embodiment of the present invention is illustrated. Valve assembly  332  is shown welded to upper cap  120  extending through aperture  122 . Discharge valve assembly  332  comprises a discharge valve plate assembly  340 , a tubular element  342  and valve member  94 . Discharge valve plate assembly  340  comprises a discharge valve plate  344 , a cup shaped tubular fitting  346  and a stop  348 . Valve plate  344  is formed preferably from powdered metal and has the plurality of cutout portions  96  therein as well as valve seat  98 . Valve plate  344  is secured to tubular fitting  346  by a forming operation which sandwiches valve plate  344  within an annular groove  350  of tubular fitting  346 . Tubular fitting  346  and thus valve assembly  332  is secured to upper cap  120  by being brazed to a formed flange  352  extending from upper cap  120  surrounding aperture  122 . Stop  348  is a frusto-conical element which is brazed within tubular fitting  346  abutting an inwardly radially extending flange  354  of tubular fitting  346  to form an annular stop surface or shoulder for restricting the movement of valve member  94 .  
         [0052]    Tubular element  342  is brazed to an internal diameter  356  of tubular fitting  346 . The end of tubular element  342  opposite to fitting  346  defines enlarged diameter end  108  which, as described above, is adapted to be connected to the suitable conduit of the refrigeration system with which compressor  10  is to be utilized.  
         [0053]    Valve member  94  is disposed within a chamber  358  formed by valve plate assembly  340 . Valve member  94  is sized so as to be freely movable between valve seat  98  and stop  348 . The movement, function and operation of valve member  94  in discharge valve assembly  332  is the same as that described above for the embodiment shown in FIGS.  1 - 4 .  
         [0054]    Referring now to FIG. 12, a discharge valve assembly  382  according to another embodiment of the present invention is illustrated. Valve assembly  382  is shown welded to upper cap  120  extending through aperture  122 . Discharge valve assembly  382  comprises a valve plate assembly  390 , a tubular element  392  and a valve member  94 . Discharge valve plate assembly  390  comprises a discharge valve plate  394  and a tubular fitting  396 . Valve plate  394  is formed preferably from powdered metal and has the plurality of cutout portions  96  therein as well as valve seat  98 . Valve plate  394  is secured to tubular fitting  396  by a forming operation which sandwiches valve plate  394  within an annular groove  398  of tubular fitting  396 . Tubular fitting  396  has a generally radially outwardly extending annular flange  400  which is adapted to abut and be welded to the outer surface of upper cap  120 . In order to aid in the weld process and ensure a secure fluid tight seal, an axially extending rib  402  is provided on flange  400 . During the welding operation, rib  402  becomes sacrificial to supply a portion of the weld material as is well known in the art.  
         [0055]    Tubular element  392  comprises a tubular fitting  404  and a tube  406 . Tubular fitting  404  is brazed to an internal diameter  408  of tubular fitting  396 . The end of tubular fitting  404  extending within tubular fitting  396  forms an annular stop surface or shoulder for restricting the movement of valve member  94 . Tube  406  is brazed to an internal diameter  410  of fitting  404 . The end of tube  406  opposite to fitting  404  defines enlarged diameter end  108  which, as described above, is adapted to be connected to the suitable conduit of the refrigeration system with which compressor  10  is to be utilized.  
         [0056]    Valve member  94  is disposed within a chamber  412  formed by valve plate assembly  390  and tubular element  392 . Valve member  94  is sized so as to be freely movable between valve seat  98  and tubular fitting  404 . The movement, function and operation of valve member  94  in discharge valve assembly  382  is the same as that described above for the embodiment shown in FIGS.  1 - 4 .  
         [0057]    Referring now to FIG. 13, a discharge valve assembly  432  according to another embodiment of the present invention is illustrated. Valve assembly  432  is shown welded to upper cap  120  extending out of aperture  122 . Valve assembly  432  comprises a discharge valve plate  440 , an elongated tubular member  442  and valve member  94 . Discharge valve plate  440  is formed preferably from powdered metal and has the plurality of cutout portions  96  therein as well as valve seat  98 . Valve plate  440  is secured to tubular member  442  by being welded or brazed to an internal diameter  444  of tubular member  442 .  
         [0058]    Tubular member  442  has a generally outwardly extending annular flange  450  which is adapted to abut and be welded to the inside surface of upper cap  120 . In order to aid in the welding process and ensure a secure fluid tight seal, an outwardly projecting rib  452  is provided on flange  450 . During the welding operation, rib  452  becomes sacrificial to supply a portion of the weld material as is well known in the art. Tubular member  442  has a generally radially inwardly extending flange  454  which with valve plate  440  forms a chamber  456  within which valve member  94  is located. Flange  454  provides an annular stop surface or shoulder for restricting the movement of valve member  94 . The end of tubular member  442  opposite to flange  450  defines enlarged diameter end  108  which, as described above, is adapted to be connected to the suitable conduit of the refrigeration system with which compressor  10  is to be utilized.  
         [0059]    Valve member  94  is disposed within chamber  456  and is sized so as to be freely movable between valve seat  98  and flange  454 . The movement, function and operation of valve member  94  in discharge valve assembly  432  is the same as that described above for the embodiment shown in FIGS.  1 - 4 .  
         [0060]    Referring now to FIG. 14, a discharge valve assembly  482  according to another embodiment of the present invention is illustrated. Valve assembly  482  is shown welded to upper cap  120  adjacent to aperture  122 . Valve assembly  482  comprises a discharge valve plate  490 , an elongated tubular member  492  and valve member  94 . Discharge valve plate  490  is formed preferably from powdered metal and has the plurality of cutout portions  96  therein as well as valve seat  98 . Valve plate  490  is secured to tubular member  492  by being welded or brazed to an internal diameter  494  of tubular member  492 .  
         [0061]    Tubular member  492  has a generally outwardly extending annular flange  500  which is adapted to abut and be welded to the outside surface of upper cap  120 . In order to aid in the welding process and ensure a secure fluid tight seal, an outwardly projecting rib  502  is provided on flange  500 . During the welding operation, rib  502  becomes sacrificial to supply a portion of the weld material as is well known in the art. Tubular member  492  has a generally radially inwardly extending flange  504  which with valve plate  490  forms a chamber  506  within which valve member  94  is located. Flange  504  provides an annular stop surface or shoulder for restricting the movement of valve member  94 . The end of tubular member  492  opposite to flange  500  defines enlarged diameter end  108  which, as described above, is adapted to be connected to the suitable conduit of the refrigeration system with which compressor  10  is to be utilized.  
         [0062]    Valve member  94  is disposed within chamber  506  and is sized so as to be freely movable between valve seat  98  and flange  504 . The movement, function and operation of valve member  94  in discharge valve assembly  482  is the same as that described above for the embodiment shown in FIGS.  1 - 4 .  
         [0063]    Referring now to FIG. 15, a discharge valve assembly  482 ′ according to another embodiment of the present invention is illustrated. Valve assembly  482 ′ is the same as valve assembly  482  except that elongated tubular member  492  of valve assembly  482  is replaced by tubular member  492 ′ of valve assembly  482 ′. Tubular member  492 ′ is the same as tubular member  492  except that the enlarged portion of tubular member  492 ′ adjacent upper cap  120  is modified for friction welding to upper cap  120  as is well known in the art. During the welding operation, the enlarged end of tubular member  492 ′ adjacent upper cap  120  is curled over to form flange  500 ′ as is also well know in the art. The function and operation of valve assembly  482 ′ is the same as that described above for valve assembly  482 .  
         [0064]    Referring now to FIG. 16, a discharge valve assembly  532  according to another embodiment of the present invention is illustrated. Valve assembly  532  is shown friction-welded to upper cap  120  extending through aperture  122 . Discharge valve assembly  532  comprises a discharge valve plate  540 , a tubular member  542  and valve member  94 . Tubular member  542  includes a tubular fitting  544  and a valve body  546 . Valve plate  540  is preferably formed from powdered metal and has the plurality of cutout portions  96  therein as well as valve seat  98 . Valve plate  540  is secured to valve body  546  by an orbit-forming operation which sandwiches valve plate  540  within an annular groove  548  of valve body  546 . Before forming, valve body  546  includes an annular extension which extends beyond the outer edge of valve plate  540 . The annular extension is formed over the outside end of valve plate  540  to create a flange  550  which retains valve plate  540  within valve body  546  similar to the manner shown in previous embodiments.  
         [0065]    Tubular fitting  544  is designed to be friction welded to upper cap  120 . Prior to the friction welding operation, valve body  546  is pressed into an enlarged portion  554  of tubular fitting  544 . Valve body  546  can be pressed into tubular fitting  544  before or after the assembly of valve plate  540  but preferably it is done before. The open end of enlarged portion  554  of tubular fitting  544  extends beyond a shoulder  556  formed on valve body  546  such that only enlarged portion  554  of tubular fitting  544  contacts upper cap  120  before the welding operation. The open end is modified for friction-welding as is well known in the art. During the welding operation, the open end of enlarged portion  554  is curled over to form a flange  558  as is also known well in the art. The portion of flange  558  which extends into enlarged portion  554  retains valve body  546  within fitting  544 .  
         [0066]    Valve member  94  is disposed within a chamber  560  formed by valve plate  540  and valve body  546 . Valve member  94  is sized so as to be freely movable between valve seat  98  on valve plate  540  and valve body  546  which acts as a stop for valve member  94 . The movement function and operation of valve member  94  in discharge valve assembly  532  is the same as described above for the embodiment shown in FIGS.  1 - 4 .  
         [0067]    While the above detailed description describes the preferred embodiment of the present invention, it should be understood that the present invention is susceptible to modification, variation and alteration without deviating from the scope and fair meaning of the subjoined claims.