Abstract:
A compressor includes a discharge and/or suction valve whose valve seat has a spiral groove that faces the valve. When the valve is closed, the spiral groove provides a minute fluid passageway between the valve and the valve seat. The spiral groove reduces fluid adhesion between the valve and the seat so that the compressor is quieter, more efficient and less expensive to make.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The subject invention generally pertains to reciprocating compressors and more specifically to valves and valve plates of such compressors.  
         [0003]     2. Description of Related Art  
         [0004]     To prevent backflow through a suction or discharge opening of a valve plate, compressors often use ring-type valves (similar in shape to washers) that can seal against the valve plate to cover the opening. In reciprocating compressors, the valves function as suction and discharge check valves that enable a reciprocating piston to compress the gas within a cylinder. The valves also determine which direction the gas flows through the compressor.  
         [0005]     The sealing surface of the valve plate against which the valve seals is known as a valve seat. Typically, the surface finish of both the valve and the valve seat are ground as smooth as possible to ensure a positive seal between the two. Although a smooth finish may provide a tight seal, such a surface finish can create several problems. One, adhesion of a fluid such as refrigerant or oil trapped between the valve and the valve seat can cause the valve to stick and delay its opening, which can reduce the operating efficiency of the compressor. Two, the resulting delayed opening can make a compressor noisy. Also, a smoothly ground surface can be costly to produce.  
         [0006]     Some compressors have something other than a smooth finish between the valve and the valve seat. The compressor disclosed in U.S. Pat. No. 1,718,350, for instance, has a series of concentric ridges on either the valve or its seat, thereby providing the valve with multiple seats for better sealing. Since the ridges are concentric, however, fluid can still be trapped within the concentric grooves that lie between the ridges. So even though such a design may provide better sealing, the design does not address the problem of liquid adhesion occurring between the valve and the valve seat.  
         [0007]     U.S. Pat. No. 5,078,582 discloses a compressor whose valve seats have a roughened surface to quiet the operation of the valve. It is not clear, however, how the surface is roughened. If the surface is created by a distribution of pits, the pits may provide pockets that trap fluid in a manner similar to that of the grooves disclosed in the &#39;350 patent just described. If the surface, however, is roughened by a series of protrusions, fluid passageways winding around the protrusions may provide relatively short leakage paths across the valve. Although a compressor designed according to the &#39;582 patent may be quieter, such a compressor is not necessarily more efficient.  
         [0008]     Consequently, a need exists for a compressor valve arrangement that is quieter, more efficient and less expensive than current valve arrangements.  
       SUMMARY OF THE INVENTION  
       [0009]     It is an object of the present invention to provide a reciprocating compressor with a valve plate that includes a valve seat with a spiral groove to reduce the noise, reduce the manufacturing cost, and/or increase the efficiency of the compressor.  
         [0010]     Another object of some embodiments is to provide a valve plate with a spiral groove so that when the valve is closed, the groove provides a minute fluid communication passageway between a cylinder and another chamber of the compressor.  
         [0011]     Another object of some embodiments is to create a valve seat with a spiral groove that provides the valve seat with a surface finish of between 10 and 250 microinches.  
         [0012]     Another object of some embodiments is to create a valve plate with an annular valve opening that is generally centered relative to a machined spiral groove in the valve seat.  
         [0013]     Another object of some embodiments is to incorporate both a suction valve seat and a discharge valve seat in a common valve plate, wherein both seats include a spiral groove.  
         [0014]     One or more of these and/or other objects of the invention are provided by a compressor that includes a valve plate, wherein the valve plate has at least one valve seat with a spiral groove. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0015]      FIG. 1  is a cross-sectional view of a compressor shown connected to a schematically illustrated refrigerant system.  
         [0016]      FIG. 2  is an enlarged view of the encircled portion of  FIG. 1 .  
         [0017]      FIG. 3  is an enlarged view of the encircled portion of  FIG. 2 .  
         [0018]      FIG. 4  is a view taken along line  4 - 4  of  FIG. 3  but with the suction valve and piston omitted.  
         [0019]      FIG. 5  is a view taken along line  5 - 5  of  FIG. 3 . 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0020]     A refrigerant system  10 , shown in  FIG. 1 , includes a compressor  12  for compressing refrigerant gas and for forcing the refrigerant sequentially through a discharge outlet  14  of compressor  12 , through a condenser  16  that releases heat for condensing the refrigerant, through an expansion device  18  (e.g., expansion valve, capillary tube, orifice, etc.) for cooling the refrigerant by expansion, and through an evaporator  20  for absorbing heat from an outside source or heat load. From evaporator  20 , the refrigerant returns to compressor  12  via a suction inlet  22  to repeat the cycle.  
         [0021]     Referring further to  FIGS. 2 and 3 , compressor  12  comprises a compressor housing assembly  24 , which in this example includes a number of components including, but not necessarily limited to, a cylinder block  26 , a cylinder head  28 , a hermetically sealed shell  30 , a discharge muffler  32 , and other components of the compressor.  
         [0022]     To compress the refrigerant, an electric motor  34  drives a piston  36  in reciprocating motion within a cylinder  38 . A valve plate  40  provides a discharge valve seat  42  for a discharge valve  44  and a suction valve seat  46  for a suction valve  48 . Additional components of the discharge valve assembly include a spider  50  attached to the face of valve plate  40 , a center plug  52  attached to spider  50 , and a spring  54  (e.g., a wave spring) that urges valve  44  against discharge valve seat  42 .  
         [0023]     Referring to  FIG. 4 , suction valve seat  46  comprises an inner seat  46   a  and an outer seat  46   b  that define an annular suction opening  56  between the two. Suction opening  56  provides a gas passageway that runs past valve seat  46 . Suction valve  48  is a generally annular spring steel washer that is of a shape and size to overlie and cover suction opening  56 . To hold valve  48  in place yet allow the valve to resiliently flex between a closed position against valve seat  46  and an open position spaced apart from seat  46 , suction valve  48  includes two outwardly protruding tabs  58  that engage a curved upper edge of cylinder block  26 . When the gas pressure differential between a suction chamber  60  and cylinder  38  is sufficient to force valve  48  away from valve seat  46  (as a result of piston  36  retracting or moving in a return stroke  62  within cylinder  38 ), valve  48  moves to its open position to uncover suction opening  56 .  
         [0024]     To minimize valve noise, to increase compressor efficiency, and/or to minimize the manufacturing cost of producing valve plate  40 , the surface finish of suction valve seat  46  is produced by machining, turning or otherwise producing a spiral groove  64  on the face of valve plate  40 . Groove  64  is laid out along a spiral pattern similar to that of a phonograph record, and the center of the spiral  66  is generally in line with the center of valve seat  46 . Groove  64  preferably has an axial depth and a radial pitch that provides the face of the valve plate with a surface finish of about 10 to 250 microinches when measured along a radial path perpendicular to the groove. To avoid creating a short, direct leak path between suction chamber  60  and cylinder  38 , groove  64  provides a spiral path that extends multiple revolutions on both the inner and outer seats of valve seat  46 , whereby any minute backflow gas leakage along groove  64  when valve  48  is closed must make multiple passes or laps around each seating surface. To reduce fluid adhesion between valve  48  and seat  46 , groove  64  maintains at least some minute fluid communication across valve seat  46  when valve  48  is closed.  
         [0025]     Referring to  FIG. 5 , discharge valve seat  42  comprises an inner seat  42   a  on center plug  52  and an outer seat  42   b  on valve plate  40 . The inner and outer seats define an annular discharge opening  68  between the two. Discharge opening  68  provides a gas passageway that runs past valve seat  42 . Discharge valve  44  is a generally annular spring steel washer that is of a shape and size to overlie and cover discharge opening  68 . Valve  44  is radially contained between a central post  70  and several peripheral posts  72  of spider  50 . A back surface  74  of spider  50  limits the axial movement of discharge valve  44 . Spring  54  interposed between valve  44  and surface  74  urges valve  44  to its closed position against discharge valve seat  42 . When the gas pressure differential between cylinder  38  and a discharge chamber  76  overcomes the closing force of spring  54  (as a result of piston  36  extending or moving in a compression stroke  78  within cylinder  38 ), discharge valve  44  lifts away from valve seat  42  to an open position where valve  44  uncovers discharge opening  68 .  
         [0026]     Again, to minimize valve noise, to increase compressor efficiency, and/or to minimize the manufacturing cost of producing valve plate  40  and plug  52 , the surface finish of discharge valve seat  42  is produced by machining, turning or otherwise producing a spiral groove  80  on the face of valve plate  40  and plug  52 . Groove  80  preferably has an axial depth and a radial pitch that provides the face of valve plate  40  and plug  52  with a surface finish of about 10 to 250 microinches when measured along a radial path perpendicular to the groove. To avoid creating a short, direct leak path between discharge chamber  76  and cylinder  38 , groove  80  provides a spiral path that extends multiple revolutions on both the inner and outer seats of valve seat  42 , whereby any minute backflow gas leakage along groove  80  when valve  44  is closed must make multiple passes or laps around each seating surface. To reduce fluid adhesion between valve  44  and seat  42 , groove  80  maintains at least some minute fluid communication across valve seat  42  when valve  44  is closed.  
         [0027]     To provide additional information on the structure and function of compressor  12 , U.S. Pat. Nos. 4,811,757; 6,254,354; and 6,358,026 are hereby incorporated by reference herein.  
         [0028]     Although the invention is described with respect to a preferred embodiment, modifications thereto will be apparent to those of ordinary skill in the art. Therefore, the scope of the invention is to be determined by reference to the following claims: