Abstract:
A scroll compressor includes a discharge valve assembly having a valve member, a valve stop supported within the compressor shell and including an aperture there through and a communication member. The communication member defines a fluid passage extending into the discharge chamber from the valve stop toward the first discharge outlet in the discharge chamber and provides fluid communication between the aperture in the valve stop and a location downstream of the valve stop. A first side of the valve member abuts the valve stop when in an open position and the valve stop provides communication between the first side of the valve member and the communication member via the aperture.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 12/207,089 filed on Sep. 9, 2008 which claims the benefit of U.S. Provisional Application Nos. 60/993,451, 60/993,452, 60/993,464 and 60/993,465, each filed on Sep. 11, 2007 and U.S. Provisional Application No. 61/038,162, filed Mar. 20, 2008. The entire disclosure of each of the above applications is incorporated herein by reference. 
    
    
     FIELD 
     The present disclosure relates to compressors, and more specifically to backflow prevention devices in compressors. 
     BACKGROUND 
     This section provides background information related to the present disclosure which is not necessarily prior art. 
     During scroll compressor operation, a gas is pressurized by compression due to orbital travel of the scroll members. During compressor shutdown, the pressurized gas has a tendency to backflow to a lower pressure region and causes a reverse orbit of the scroll members. Scroll compressors may include a valve assembly to prevent a reverse rotation of the scroll members during shutdown. However, even with the valve assemblies, some reverse orbit may occur due to delays in valve closing. 
     SUMMARY 
     This section provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features. 
     A scroll compressor may include a shell, a partition, a first scroll member, a second scroll member, a drive member and a discharge valve assembly. The shell may include a suction pressure region and a discharge chamber having a discharge outlet. The partition may be coupled to the shell and may separate the suction pressure region from the discharge chamber. The first scroll member may be supported within the suction pressure region of the shell and may include a second discharge outlet in communication with the discharge chamber. The second scroll member may be meshingly engaged with the first scroll member and the drive member may be engaged with the second scroll member. The discharge valve assembly may include a valve member, a valve stop supported within the shell and including an aperture therethrough and a communication member. The communication member may define a fluid passage extending into the discharge chamber from the valve stop toward the first discharge outlet in the discharge chamber and may provide fluid communication between the aperture in the valve stop and a location downstream of the valve stop. A first side of the valve member may abut the valve stop when in an open position and the valve stop may provide communication between the first side of the valve member and the communication member via the aperture. 
     The communication member may include a first end fixed to the valve stop and defining a first opening in fluid communication with the aperture in the valve stop and a second end defining a second opening generally facing the first discharge outlet. The first side of the valve member may be in fluid communication with the second opening and a second side of the valve member opposite the first side may be in fluid communication with a first fluid pressure from the second discharge outlet. The second opening may be in fluid communication with a fluid at a second fluid pressure at the location downstream of the valve stop that is less than the first fluid pressure during compressor operation. The second opening may generally face a direction of fluid flow from the second discharge outlet to the first discharge outlet. The second fluid pressure may be a localized fluid pressure at the second opening from a fluid flow past the second end of the communication member. The second fluid pressure may define a lesser pressure oscillation during compressor operation than the first fluid pressure. 
     The second end of the communication member may be positioned relative to the first discharge outlet to create a flow restriction therebetween. The second opening of the communication member may be spaced apart from the first discharge outlet. The second opening of the communication member may be located within the first discharge outlet. The second end of the communication member may be located at a maximum fluid flow velocity region of the discharge chamber. 
     The first and second scroll members may be axially displaceable relative to one another. The scroll compressor may additionally include a bearing housing supported within the shell and supporting the first and second scroll members thereon with the first scroll member being axially displaceable relative to the bearing housing. The communication member may include a generally tubular body forming the fluid passage. The generally tubular body may include a first end fixed to the valve stop in communication with the aperture and a second end opposite the first end and extending generally parallel to a longitudinal axis of the first discharge outlet. The valve stop may be fixed to the partition within the discharge chamber. 
     In another arrangement, a scroll compressor may include a shell, a partition, a first scroll member, a second scroll member, a drive member and a discharge valve assembly. The shell may include a suction pressure region and a discharge chamber having a first discharge outlet. The partition may be coupled to the shell and may separate the suction pressure region from the discharge chamber. The first scroll member may be supported within the suction pressure region of the shell and may include a second discharge outlet in communication with the discharge chamber. The second scroll member may be meshingly engaged with the first scroll member and the drive member may be engaged with the second scroll member. The discharge valve assembly may include a valve member, a valve stop fixed to the partition and including an aperture therethrough, and a communication member defining a fluid passage extending from the valve stop and including a first end fixed to the valve stop and defining a first opening adjacent to and in fluid communication with the aperture in the valve stop and a second end defining a second opening facing the first discharge outlet. The valve member may be secured between the partition and the valve stop. 
     The valve stop may be located within a first region of the discharge chamber and the second end of the communication member may be located within a second region of the compressor experiencing a lesser pressure fluctuation during compressor operation than the first region. The valve member may be displaceable between an open position allowing fluid flow from the second discharge outlet to the first discharge outlet and a closed position isolating the second discharge outlet from the first discharge outlet. The valve member may include a first side facing the aperture in the valve stop and abutting the valve stop when in the open position. The first side may be in communication with the second region of the discharge chamber via the communication member and may be isolated from the first region when in the open position. The second end of the communication member may be positioned relative to the first discharge outlet to create a fluid flow restriction and create a lesser pressure fluctuation at the second region relative to the first region. 
     Further areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. 
    
    
     
       DRAWINGS 
       The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure. 
         FIG. 1  is a sectional view of a compressor according to the present disclosure; 
         FIG. 2  is a fragmentary section view of the compressor of  FIG. 1 ; 
         FIG. 3  is a fragmentary section view of the compressor of  FIG. 1 ; 
         FIG. 4  is a section view of a valve assembly shown in  FIG. 1 ; 
         FIG. 5  is a schematic illustration of an arrangement between a communication member and a discharge fitting according to the present disclosure; 
         FIG. 6  is a schematic illustration of an alternate arrangement between a communication member and a discharge fitting according to the present disclosure; 
         FIG. 7  is a schematic illustration of an alternate arrangement between a communication member and a discharge fitting according to the present disclosure; 
         FIG. 8  is a graphical illustration of gas pressures within the compressor of  FIG. 1 ; and 
         FIG. 9  is a fragmentary section view of an alternate compressor according to the present disclosure. 
     
    
    
     Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings. 
     DETAILED DESCRIPTION 
     Example embodiments will now be described more fully with reference to the accompanying drawings. 
     The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. It should be understood that throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features. 
     The present teachings are suitable for incorporation in many different types of scroll and rotary compressors, including hermetic machines, open drive machines and non-hermetic machines. For exemplary purposes, a compressor  10  is shown as a hermetic scroll refrigerant-compressor of the low-side type, i.e., where the motor and compressor are cooled by suction gas in the hermetic shell, as illustrated in the vertical section shown in  FIG. 1 . 
     With reference to  FIG. 1 , compressor  10  may include a cylindrical hermetic shell  12 , a compression mechanism  14 , a seal assembly  15 , a main bearing housing  16 , a retaining assembly  17 , a motor assembly  18 , a refrigerant discharge fitting  20 , a discharge valve assembly  21 , and a suction gas inlet fitting  22 . Hermetic shell  12  may house compression mechanism  14 , main bearing housing  16 , and motor assembly  18 . Shell  12  may include an end cap  24  at the upper end thereof, a transversely extending partition  26 , and a base  28  at a lower end thereof. End cap  24  and transversely extending partition  26  may generally define a discharge chamber  30 . Discharge chamber  30  may generally form a discharge muffler for compressor  10 . Refrigerant discharge fitting  20  may be attached to shell  12  at opening  32  in end cap  24 . Suction gas inlet fitting  22  may be attached to shell  12  at opening  34 . Compression mechanism  14  may be driven by motor assembly  18  and supported by main bearing housing  16 . Main bearing housing  16  may be affixed to shell  12  at a plurality of points in any desirable manner, such as staking. 
     Motor assembly  18  may generally include a motor stator  36 , a rotor  38 , and a drive shaft  40 . Windings  41  may pass through stator  36 . Motor stator  36  may be press fit into shell  12 . Drive shaft  40  may be rotatably driven by rotor  38 . Rotor  38  may be press fit on drive shaft  40 . 
     Drive shaft  40  may include an eccentric crank pin  42  having a flat  44  thereon and upper and lower counter-weights  46 ,  48 . Drive shaft  40  may include a first journal portion  50  rotatably journaled in a first bearing  52  in main bearing housing  16  and a second journal portion  54  rotatably journaled in a second bearing  56  in lower bearing housing  58 . Drive shaft  40  may include an oil-pumping concentric bore  60  at a lower end. Concentric bore  60  may communicate with a radially outwardly inclined and relatively smaller diameter bore  62  extending to the upper end of drive shaft  40 . The lower interior portion of shell  12  may be filled with lubricating oil. Concentric bore  60  may provide pump action in conjunction with bore  62  to distribute lubricating fluid to various portions of compressor  10 . 
     Compression mechanism  14  may generally include an orbiting scroll  64  and a non-orbiting scroll  66 . Orbiting scroll  64  may include an end plate  68  having a spiral vane or wrap  70  on the upper surface thereof and an annular flat thrust surface  72  on the lower surface. Thrust surface  72  may interface with an annular flat thrust bearing surface  74  on an upper surface of main bearing housing  16 . A cylindrical hub  76  may project downwardly from thrust surface  72  and may have a drive bushing  78  rotatively disposed therein. Drive bushing  78  may include an inner bore in which crank pin  42  is drivingly disposed. Crank pin flat  44  may drivingly engage a flat surface in a portion of the inner bore of drive bushing  78  to provide a radially compliant driving arrangement. 
     Non-orbiting scroll  66  may include an end plate  80  having a spiral wrap  82  on a lower surface thereof. Spiral wrap  82  may form a meshing engagement with wrap  70  of orbiting scroll  64 , thereby creating an inlet pocket  84 , intermediate pockets  86 ,  88 ,  90 ,  92 , and an outlet pocket  94 . Non-orbiting scroll  66  may be axially displaceable relative to main bearing housing  16 , shell  12 , and orbiting scroll  64 . Non-orbiting scroll  66  may include a discharge passageway  96  in communication with outlet pocket  94  and upwardly open recess  98  which may be in fluid communication with discharge chamber  30  via an opening  100  in partition  26 . 
     Non-orbiting scroll  66  may include an annular recess  106  in the upper surface thereof defined by parallel coaxial inner and outer side walls  108 ,  110 . Annular recess  106  may provide for axial biasing of non-orbiting scroll  66  relative to orbiting scroll  64 , as discussed below. More specifically, a passage  112  may extend through end plate  80  of non-orbiting scroll  66 , placing recess  106  in fluid communication with intermediate pocket  90 . While passage  112  is shown extending into intermediate pocket  90 , it is understood that passage  112  may alternatively be placed in communication with any of the other intermediate pockets  86 ,  88 ,  92 . 
     Seal assembly  15  may include first and second seals  138 ,  140 . First and second seals  138 ,  140  may each include an L-shaped cross-section and may sealingly engage partition  26 , as described in “Compressor Sealing Arrangement”, filed Sep. 9, 2008, U.S. application Ser. No. 12/207,051, the disclosure of which is incorporated herein by reference. 
     Orbiting scroll  64  and non-orbiting scroll  66  may generally be supported by main bearing housing  16 . Main bearing housing  16  may include a radially extending body portion  162  defining thrust bearing surface  74  and a plurality of arms  164  (one of which is shown) extending axially upwardly therefrom. Main bearing housing  16  may be pressed into shell  12  and staked thereto to fix main bearing housing  16  relative to shell  12 . 
     Retaining assembly  17  may include an Oldham coupling  182  and a retaining ring  186 , as described in “Compressor with Retaining Mechanism”, filed Sep. 9, 2008, U.S. application Ser. No. 12/207,072, the disclosure of which is incorporated herein by reference. Oldham coupling  182  may be engaged with orbiting and non-orbiting scrolls  64 ,  66  to prevent relative rotation therebetween. Retaining ring  186  may limit axial displacement of non-orbiting scroll  66  relative to main bearing housing  16 . 
     With reference to  FIGS. 1-4 , discharge valve assembly  21  may include a valve housing  224 , a backflow communication member  226 , and a valve member  228 . Valve housing  224  may be coupled to partition  26  adjacent opening  100  therein. Valve housing  224  may include a valve stop  230  having a series of legs  232  extending axially therefrom and providing an axial offset between opening  100  and valve stop  230 . Legs  232  may be circumferentially disposed about valve stop  230 , providing openings  234  therebetween. Legs  232  may also circumferentially surround opening  100  in partition  26 . Valve stop  230  may include an aperture  236  generally surrounded by an annular ridge  238 . Annular ridge  238  may extend axially toward partition  26  and may provide a reduced surface area for engagement with valve member  228 , as discussed below. 
     Backflow communication member  226  may include a generally tubular member extending from valve stop  230  toward discharge fitting  20  and forming a fluid passage therebetween. Backflow communication member  226  may extend generally linearly between discharge passageway  96  and opening  32 . Alternatively, a backflow communication member  326  may include a bent body, as discussed below ( FIG. 9 ). Backflow communication member  226  may include a first end  240  coupled to valve stop  230  and providing sealed fluid communication between aperture  236  and a second end  242  of backflow communication member  226  downstream of valve stop  230  proximate discharge fitting  20 . More specifically, backflow communication member  226  may have a longitudinal extent that is greater than one-half of the distance between opening  32  in end cap  24  and discharge passageway  96  of compression mechanism  14 . Second end  242  of backflow communication member  226  may include an outwardly flared opening  243  generally facing the outlet formed by discharge fitting  20 . Second end  242  may extend generally parallel to the longitudinal axis of the opening defined by discharge fitting  20 . 
     Opening  243  may generally face a direction of fluid flow from compression mechanism  14  to discharge fitting  20  during operation of compressor  10 . More specifically, second end  242  may be located in a maximum fluid flow velocity region of discharge chamber  30  during operation of compressor  10 . Opening  243  may face a direction generally opposite a direction of fluid flow from discharge fitting  20  to compression mechanism  14  during compressor shut-down. Second end  242  of backflow communication member  226  may cooperate with end cap  24  and discharge fitting  20  to isolate second end  242  of backflow communication member  226  from pressure fluctuations by creating a flow restriction (R) upstream of second end  242  during normal operation of compressor  10 , as discussed below. Alternatively, or additionally, the fluid flow velocity past second end  242  may isolate opening  243  from pressure fluctuations by creating a localized pressure drop at opening  243 . 
     First, second, and third exemplary arrangements of the relation between discharge fitting  20  and second end  242  of backflow communication member  226  are shown schematically in  FIGS. 5-7  for illustration purposes only and have been simplified from the actual geometry of compressor  10 . In a first arrangement ( FIG. 5 ), second end  242   a  of backflow communication member  226   a  may be disposed within discharge chamber  30   a  and spaced a distance (L 1 ) from an opening of discharge fitting  20   a , generally similar to the arrangement shown in compressor  10 . In this arrangement, a restriction (R 1 ) for flow from discharge chamber  30   a  to discharge fitting  20   a  may be created by the flow area (A 1 ) defined by the relation between second end  242   a  of backflow communication member  226   a  and discharge fitting  20   a . For simplicity, an outer diameter (D 1a ) of second end  242   a  and an inner diameter (D 1b ) of an inlet of discharge fitting  20   a  are assumed to have similar diameters (D 1 =D 1a =D 1b ). The flow area (A 1 ) may then be calculated based on the equation for the surface area of a cylinder having a height (L 1 ) and a diameter (D 1 ), A 1 =πD 1  L 1 . It is understood that second end  242   a  and an inlet of discharge fitting  20   a  may have differing diameters, resulting in a flow area corresponding to the surface area of a truncated conical shape, as seen in compressor  10 . 
     In a second arrangement ( FIG. 6 ), second end  242   b  of backflow communication member  226   b  may extend outside of discharge chamber  30   b  and may extend a distance into discharge fitting  20   b . The restriction (R 2 ) may then be defined by the minimum flow area (A 2 ) between second end  242   b  and discharge fitting  20   b . In the example shown, second end  242   b  has an outer diameter (D 2a ) and discharge fitting  20   b  has an inner diameter (D 2b ). The minimum flow area (A 2 ) may be defined by: A 2 =π(D 2b   2 −D 2a   2 )/4. The third arrangement ( FIG. 7 ) may be generally similar to the second arrangement. Therefore, the restriction (R 3 ) may be similarly defined. However, in the third arrangement, second end  242   c  of backflow communication member  226   c  may be disposed inside of discharge chamber  30   c . An inlet of discharge fitting  20   c  may also extend into discharge chamber  30   c  and second end  242   c  of backflow communication member  226   c  may extend a distance into discharge fitting  20   c  to form restriction (R 3 ) generally similar to restriction (R 2 ). 
     The restrictions (R, R 1 , R 2 , R 3 ) may generally create a pressure drop relative to discharge chamber  30 , as well as a reduction in pressure fluctuation, as discussed below. Restrictions (R, R 1 , R 2 , R 3 ) may generally provide isolation for valve member  228 , as discussed below. 
     Valve member  228  may be disposed within legs  232  of discharge valve assembly  21  and between valve stop  230  and partition  26 . Valve member  228  may be generally free from a direct connection with valve housing  224  and partition  26 . Valve member  228  may be displaceable between first and second positions based on a pressure acting thereon. 
     More specifically, valve member  228  may be in the form of a disc member having upper and lower surfaces  244 ,  246 . Upper surface  244  may generally face valve stop  230  and lower surface  246  may generally face partition  26 . In the second position ( FIG. 2 ), valve member  228  may generally abut partition  26  and overly opening  100  therein, preventing fluid communication between discharge chamber  30  and recess  98 . In the first position ( FIG. 3 ), valve member  228  may generally abut annular ridge  238  of valve stop  230 , allowing fluid communication between recess  98  and discharge chamber  30 . Annular ridge  238  may generally provide a reduced contact area between valve member  228  and stop member  230 , resulting in a quicker response time of valve member  228 . In the first position, upper surface  244  of valve member  228  may be generally isolated from discharge pressure except as provided from backflow communication member  226  due to its engagement with valve stop  230 . 
     More specifically, during normal operation of compressor  10 , the pressure (P 0 ) of discharge gas provided by compression mechanism  14  varies based on the rotational position of drive shaft  40 . Pressure (P 0 ) may generally vary between upper and lower limits (P 0max , P 0min ). The pressure (P 1 ) of discharge gas within discharge chamber  30  may also vary during operation of compression mechanism  14  since discharge gas is provided to discharge chamber  30  directly by compression mechanism  14 . However, the volume of discharge chamber  30  may generally damp the pressure fluctuations provided by compression mechanism  14 . Additionally, due to system losses, the average pressure (P 1AVG ) in discharge chamber  30  may generally be less than the average pressure (P 0AVG ) of discharge gas provided by compression mechanism  14 . The pressure (P d ) downstream of restriction (R) may experience fluctuations to a lesser extent than pressure (P 1 ), due to a damping effect of restriction (R). Further, the average pressure (P dAVG ) downstream of restriction (R) may be less than the average pressures (P 0AVG , P 1AVG ). 
     The exposure of upper surface  244  of valve member  228  to pressure (P d ) may therefore result in an increased stability of valve member  228 . More specifically, the reduced fluctuation of pressure (P d ) relative to pressures (P 0 , P 1 ), as well as the reduced average pressure (P dAVG ) relative to average pressures (P 0AVG , P 1AVG ), may provide stability in the position of valve member  228  during compressor operation. As seen in  FIG. 8 , pressure (P d ) may remain below minimum values of pressures (P 0 , P 1 ) resulting from the pressure fluctuations previously discussed. As such, valve member  228  may remain seated against valve stop  230  even during fluctuation of pressures P 0 , P 1 . 
     As seen in  FIG. 9 , an alternate compressor  310  having a side, or horizontally mounted discharge fitting  320  may include a discharge valve assembly  321  including a bent communication member  326 . While communication member  326  is bent to accommodate a side mounted discharge fitting  320 , it is understood that the description of discharge valve assembly  21  applies equally to discharge valve assembly  321 . 
     The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.