USRE42371E1 - Scroll machine - Google Patents

Abstract

A compressor includes a normally open discharge valve assembly for controlling compressed refrigerant flow from the discharge chamber through the compression members. This controlling of flow results in an increased performance for the compressor by reducing recompression volume and the elimination of reverse rotation at shut down. The discharge valve assembly includes a valve seat, a valve plate and a valve stop secured within a recess formed within the compressor with a wave ring retainer. The valve stop and the valve seat include a contoured surface that is engaged by the valve plate when it opens and closes. The contoured surface controls the movement of the valve plate.

Description

FIELD OF THE INVENTION

The present invention relates to rotary compressors. More particularly the present invention relates to a unique retention system for a direct discharge valve system that is utilized in a scroll compressor.

BACKGROUND AND SUMMARY OF THE INVENTION

Scroll machines are becoming more and more popular for use as compressors in both refrigeration as well as air conditioning and heat pump 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 that progressively decrease in size as they travel from an outer suction port towards a center discharge port. An electric motor is normally provided that operates to drive the orbiting scroll member via a suitable drive shaft.

Because scroll compressors depend upon successive chambers for suction, compression, and discharge processes, suction and discharge valves in general are not required. However, the performance of the compressor can be increased with the incorporation of a discharge valve. One of the factors that will determine the level of increased performance is the reduction of what is called recompression volume. The recompression volume is the volume of the discharge chamber and the discharge port of the compressor when the discharge chamber is at its smallest volume. The minimization of this recompression volume will result in a maximizing of the performance of the compressor. In addition, 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 the backflow of compressed gas from the discharge chamber and to a lesser degree for the gas in the pressurized chambers to effect a reverse orbital movement of the orbiting scroll member and its associated drive shaft. This reverse movement often generates noise or rumble, which may be considered objectionable and undesirable. 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 interruption be experienced. This reverse operation may result in overheating of the compressor and/or other inconveniences to the utilization of the system. Additionally, in some situations, such as a blocked condenser fan, it is possible for the discharge pressure to increase sufficiently to stall the drive motor and effect a reverse rotation thereof. As the orbiting scroll orbits in the reverse direction, the discharge pressure will decrease to a point where the motor again is able to overcome this pressure head and orbit the scroll member in the forward direction. However, the discharge pressure will again increase to a point where the drive motor is stalled and the cycle is repeated. Such cycling is undesirable in that it is self-perpetuating. The incorporation of a discharge valve can reduce or eliminate these reverse rotation problems.

A primary object of the present invention resides in the provision of a very simple and unique retention system for a discharge valve, which is associated with the non-orbiting scroll and which can easily be assembled into a conventional gas compressor of the scroll type without significant modification of the overall compressor design. The discharge valve operates to minimize the recompression volume and at compressor shut down operates to prohibit backflow of the discharge gas through the compressor and thus driving the compressor in the reverse direction. Prohibiting the reverse operation of the compressor eliminates the normal shut down noise and other problems associated with such reverse rotation. The retention system includes a wave ring retainer that is disposed within a groove in the non-orbiting scroll member. This groove is located adjacent the discharge valve. The wave ring retainer biases the discharge valve against the non-orbiting scroll member, but the wave ring retainer will deflect at a specified pressure to increase the flow area for the discharge gas.

These and other features of the present invention will become apparent from the following description and the appended claims, taken in conjunction with the accompanying drawings.

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

The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein:

FIG. 1 is a vertical sectional view through the center of a scroll compressor that incorporates a retention system for a discharge valve assembly in accordance with the present invention;

FIG. 2 is a top elevational view of the compressor shown inFIG. 1 with the cap and a portion of the partition removed;

FIG. 3 is an enlarged view of the floating seal assembly and discharge valve assembly illustrated inFIG. 1;

FIG. 4A is an enlarged view of the discharge valve assembly illustrated inFIGS. 1 and 3 with the discharge valve being biased against the non-orbiting scroll member;

FIG. 4B is an enlarged view of the discharge valve assembly illustrated inFIGS. 1 and 3 with the discharge valve being spaced from the non-orbiting scroll member; and

FIG. 5 is an exploded perspective view of the retention system of the discharge valve assembly shown inFIGS. 1 and 3.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

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.

Referring now to the drawings in which like reference numerals designate like or corresponding parts throughout the several views, there is shown inFIG. 1 a scroll compressor that incorporates a retention system for a discharge valving system in accordance with the present invention and which is designated generally by reference numeral10. Compressor10 comprises a generally cylindrical hermetic shell12 having welded at the upper end thereof a cap14 and at the lower end thereof abase16 having a plurality of mounting feet (not shown) integrally formed therewith. Cap14 is provided with a refrigerant discharge fitting18. Other major elements affixed to the shell include a transversely extendingpartition22 that is welded about its periphery at the same point that cap14 is welded to shell12, a lower bearinghousing24 that is suitably secured to shell12 and a two piece upper bearinghousing26 suitably secured to lower bearinghousing24.

A drive shaft orcrankshaft28 having aneccentric crank pin30 at the upper end thereof is rotatably journaled in a bearing32 in lower bearinghousing24 and a second bearing34 in upper bearinghousing26.Crankshaft28 has at the lower end a relatively large diameterconcentric bore36 that communicates with a radially outwardly inclined smaller diameter bore38 extending upwardly therefrom to the top ofcrankshaft28. The lower portion of the interior shell12 defines anoil sump40 that is filled with lubricating oil to a level slightly above the lower end of a rotor42, and bore36 acts as a pump to pump lubricating fluid upcrankshaft28 and into bore38 and ultimately to all of the various portions of the compressor that require lubrication.

Crankshaft28 is rotatively driven by an electric motor including a stator46,windings48 passing therethrough and rotor42 press fitted oncrankshaft28 and having upper andlower counterweights50 and52, respectively.

The upper surface of upper bearinghousing26 is provided with a flatthrust bearing surface54 on which is disposed an orbitingscroll member56 having the usual spiral vane orwrap58 extending upward from anend plate60. Projecting downwardly from the lower surface ofend plate60 of orbitingscroll member56 is a cylindrical hub having a journal bearing62 therein and in which is rotatively disposed a drive bushing64 having aninner bore66 in whichcrank pin30 is drivingly disposed.Crank pin30 has a flat on one surface that drivingly engages a flat surface (not shown) formed in a portion ofbore66 to provide a radially compliant driving arrangement, such as shown in Assignee's U.S. Pat. No. 4,877,382, the disclosure of which is hereby incorporated herein by reference. An Oldham coupling68 is also provided positioned between orbitingscroll member56 and bearinghousing24 and keyed to orbitingscroll member56 and anon-orbiting scroll member70 to prevent rotational movement of orbitingscroll member56. Oldham coupling68 is preferably of the type disclosed in Assignee's co-pending U.S. Pat. No. 5,320,506, the disclosure of which is hereby incorporated herein by reference.

Non-orbiting scroll member70 is also provided having a wrap72 extending downwardly from anend plate74 that is positioned in meshing engagement withwrap58 of orbitingscroll member56.Non-orbiting scroll member70 has a centrally disposeddischarge passage76 that communicates with an upwardlyopen recess78 which, in turn, is in fluid communication with adischarge muffler chamber80 defined by cap14 andpartition22. Anannular recess82 is also formed innon-orbiting scroll member70 within which is disposed afloating seal assembly84. Recesses78 and82 andseal assembly84 cooperate to define axial pressure biasing chambers, which receive pressurized fluid being compressed bywraps58 and72 so as to exert an axial biasing force onnon-orbiting scroll member70 to thereby urge the tips ofrespective wraps58,72 into sealing engagement with the opposed end plate surfaces ofend plates74 and60, respectively.Seal assembly84 is preferably of the type described in greater detail in U.S. Pat. No. 5,156,539, the disclosure of which is hereby incorporated herein by reference. Non-orbitingscroll member70 is designed to be mounted to upper bearinghousing26 in a suitable manner such as disclosed in the aforementioned U.S. Pat. No. 4,877,382 or U.S. Pat. No. 5,102,316, the disclosure of which is hereby incorporated herein by reference.

Referring now toFIGS. 2 and 3, floatingseal assembly84 is of a coaxial sandwiched construction and comprises anannular base plate102 having a plurality of equally spaced upstandingintegral projections104 each having anenlarged base portion106. Disposed onplate102 is anannular gasket assembly108 having a plurality of equally spaced holes that mate with and receivebase portions106. On top ofgasket assembly108 is disposed anannular spacer plate110 having a plurality of equally spaces spaced holes that also mate with and receivebase portions106. On top ofplate110 is anannular gasket assembly112 having a plurality of equally spaced holes that mate with and receiveprojections104. The assembly ofseal assembly84 is maintained by an annularupper seal plate114, which has a plurality of equally spaced holes mating with and receivingprojections104.Seal plate114 includes a plurality ofannular projections116, which mate with and extend into the plurality of holes inannular gasket assembly112 andspacer plate110 to provide stability to sealassembly84.Seal plate114 also includes an annular upwardly projectingplanar sealing lip118.Seal assembly84 is secured together by swaging the ends ofprojections104 as indicated at120.

Referring now toFIG. 3,seal assembly84 therefore provides three distinct seals: first, an inside diameter seal at twointerfaces122; second, an outside diameter seal at twointerfaces124; and, third, a top seal at126.Seals122 isolate fluid under intermediate pressure in the bottom ofrecess82 from fluid under discharge pressure inrecess78.Seals124 isolate fluid under intermediate pressure in the bottom ofrecess82 from fluid under suction pressure within shell12.Seal126 is between sealinglip118 and an annular seat portion onpartition22.Seal126 isolates fluid at suction pressure from fluid at discharge pressure across the top ofseal assembly84.

The diameter and width ofseal126 are chosen so that the unit pressure between sealinglip118 and the seat portion onpartition22 is greater than normally encountered discharge pressure, thus ensuring consistent sealing under normal operating conditions of compressor10, i.e., at normal operating pressure ratios. Therefore, when undesirable pressure conditions are encountered,seal assembly84 will be forced downward breakingseal126, thereby permitting fluid flow from the discharge pressure zone of compressor10 to the suction pressure zone of compressor10. If this flow 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 to trip thereby the de-energizing motor. The width ofseal126 is chose so that the unit pressure between sealinglip118 and the seat portion ofpartition22 is greater than normally encountered discharge pressure, thus ensuring consistent sealing.

The scroll compressor as thus far broadly described is either now known in the art or is the subject of other pending applications for patent or patents of Applicant's Assignee.

The present invention is directed towards a retention system for a normally openmechanical valve assembly130, which is disposed withinrecess78, which is formed innon-orbiting scroll member70. While the present invention is being described in conjunction with normally openmechanical valve assembly130, the retention system of the present invention can be used with any other type of discharge valve also.Valve assembly130 moves between a first or closed condition, a second or open condition, and a third or fully open condition during steady state operation of compressor10.Valve assembly130 will close during the shut down of compressor10. Whenvalve assembly130 is fully closed, the recompression volume is minimized and the reverse flow of discharge gas throughscroll members56 and70 is prohibited.Valve assembly130 is normally open as shown inFIGS. 3 and 4A. The normally open configuration forvalve assembly130 eliminates the force required to openvalve assembly130 as well as eliminating any mechanical device needed to closevalve assembly130.Valve assembly130 relies on gas pressure differential for closing.

Referring now toFIGS. 3-5, dischargevalve assembly130 is disposed withinrecess78 and it comprises avalve seat132, avalve plate134, avalve stop136 and awave ring retainer138.Valve seat132 is a flat metal disc shaped member defining adischarge passage140, a pair ofalignment apertures142 and acavity144.Non-orbiting scroll member70 defines a pair of alignment bores. Whenapertures142 are in registry with the alignment bores,discharge passage140 is aligned withdischarge passage76. The shape ofdischarge passage140 is the same asdischarge passage76. The thickness ofvalve seat132, particularly in the area ofcavity144 is minimized to minimize the recompression volume for compressor10, which increases the performance of compressor10. The bottom surface ofcavity144 adjacent tovalve plate134 includes acontoured surface148. The flat horizontal upper surface ofvalve seat132 is used to securevalve plate134 around its entire circumference. Contouredsurface148 ofcavity144 provides for the normally open characteristic ofvalve assembly130. Contouredsurface148 may be a generally planar surface as shown inFIG. 4A or contouredsurface148 may be a curved surface. Whilecavity144 and contouredsurface148 are shown as a pocket withinvalve seat132, it is within the scope of the present invention to havecavity144 and thus surface148 extend through the edge ofvalve seat132. Also, it is within the scope of the present invention to eliminatevalve seat132 and incorporatecavity144 andsurface148 directly into and ontonon-orbiting scroll70 if desired.

Valve plate134 is a flat thin metal disc shaped member that includes anannular ring150, a generallyrectangular portion152 extending radially inward fromring150 and a generallycircular portion154 attached to the radial inner end ofrectangular portion152.Rectangular portion152 is designed to be smaller in width thancircular portion154. This reduced section therefore has a lower bending load thancircular portion154, which results in a faster opening ofvalve assembly130. This reduced section ofrectangular portion152 is acceptable from a durability standpoint since contouredsurface148 reduces the stress loading on this reduced section. The size and shape ofportion154 is designed to completely coverdischarge passage140 ofvalve seat132. The generally circular shape ofportion154 eliminates valve breakage that is associated with rectangular valve plates. In general, valve plates can have a tendency to twist during the closing of the valve due to the pressure fluctuations across the valve. When a rectangular shape valve twists before closing, the outside corner of the rectangle will hit first causing high loading and the breakage of the corner. The present invention, by using a generally circular portion to close the valve, eliminates the possibility of this corner breakage.Valve plate134 also includes a pair ofbosses156, which define a pair ofalignment apertures158. Whenapertures158 are in registry withapertures142 ofvalve seat132,rectangular portion152 positionscircular portion154 in alignment withdischarge passage140. The thickness ofvalve plate134 is determined by the stresses developed inrectangular portion152 asvalve plate134 deflects from its closed position to its open position as described below.

Valve stop136 is a thick metal, disc shaped member that provides support and backing forvalve plate134 andvalve seat132.Valve stop136 is similar in configuration tovalve plate134 and includes anannular ring160, a generallyrectangular portion162 extending radially inward fromring160, a generallycircular portion164 attached to the radially inner end ofrectangular portion162 and asupport section166 extending betweencircular portion164 andring160 on the side ofportion164 opposite toportion162.Valve stop136 also includes a pair ofbosses168, which define a pair ofalignment apertures170. Whenapertures170 are in registry withapertures158 invalve plate134,rectangular portion162 is aligned withrectangular portion152 ofvalve plate134 and it positionscircular portion164 in alignment withcircular portion154 ofvalve plate134.Rectangular portion162 andcircular portion164 cooperate to define a curvedcontoured surface172.

Discharge valve assembly130 is assembled tonon-orbiting scroll member70 by first placingvalve seat132 withinrecess78 with contouredsurface148 facing upward while aligningapertures142 with bores inrecess78 of non-orbitincinon-orbiting scroll member70 which alignspassage140 withpassage76. Next,valve plate134 is placed on top ofvalve plate132 withinrecess78 while aligningapertures158 withapertures142, which alignscircular portion154 withpassage140. Next,valve step136 is placed on top ofvalve plate134 withinrecess78 while aligningapertures170 withinapertures158, which alignsportions162 and164 withportions152 and154, respectively. A roll pin is inserted through each aligned set ofapertures170,158 and142 and press fit into each bore of non-orbitincinon-orbiting scroll member70 to maintain the alignment of these components. Finally,retainer138 is installed withinrecess78 to maintain the assembly ofvalve assembly130 withnon-orbiting scroll member70. The assembly ofretainer138 sandwiches the entireannular ring150 ofvalve seat132 between the upper flat surface ofvalve seat132 andring160 ofvalve stop136 to secure and retainvalve plate134.

Retainer138 is a wave ring retainer that is disposed within agroove180 formed intorecess78 ofnon-orbiting scroll member70. The wave shape ofretainer138 causes it to engage both theupper surface182 and thelower surface184 ofgroove180 to adequately retain discharge valve assembly withinrecess78, as shown inFIG. 4A. The wave shape ofretainer138 also allows for axial movement of discharge valve assembly due to the resilience and, thus, compression of the wave ring retainer as shown inFIG. 4B.

Discharge valve assembly130 is normally in a condition whereinvalve plate134 abuts the upper flat surface onvalve seat132. Contouredsurface148spaces valve plate134 fromvalve seat132 to provide for the normally open characteristic ofvalve assembly130. This allows limited fluid flow fromdischarge muffler chamber80 into the compression pockets formed byscroll members56 and70. In order to closevalve assembly130, fluid pressure withinmuffler chamber80biases valve plate134 against contouredsurface148 ofvalve seat132 when the fluid pressure inchamber80 is greater than the fluid pressure within the central most fluid pocket formed byscroll members56 and70. During operation of compressor10, the fluid pressure differential between fluid indischarge chamber80 and fluid within the central most fluid pocket formed byscroll members56 and70 will movevalve plate134 between abutment with contouredsurface148 ofvalve seat132 and abutment with valve stop136 or between a first closed position and a second open position. The normally open position ofvalve assembly130 eliminates the force that is required to open a typical discharge valve. The elimination of this force lowers the pressure differential for operating the valve, which, in turn, lowers power losses. In addition the normally open feature reduces the sound generated during the closing of the valve due to the gradual closing of the valve rather than the sudden closure of a normally closed valve. Contouredsurface148 provides for this gradual closing feature. The valve of the present invention operates solely on pressure differentials. Finally, the unique design forvalve assembly130 provides a large flow area to improve the flow characteristics of the system.

Whenvalve plate134 is in its second or open position, additional discharge pressure within discharge passage will react againstdischarge valve assembly130 and it will eventually exceed the spring force being applied bywave ring retainer138.Discharge valve assembly130 will then move axially upward to the position shown inFIG. 4B, the third or fully open position, to allow fluid flow around the outer periphery ofdischarge valve assembly130.

Valve plate134 is sandwiched betweenvalve seat132 and valve stop136 withannular ring160 ofvalve stop136 abuttingannular ring150 ofvalve plate134, which, in turn, abuts the upper flat surface ofvalve seat132.Rectangular portion152 andcircular portion154 normally lie in an unstressed condition in a generally horizontal position as shown inFIG. 4A. The deflection ofvalve plate134 occurs inrectangular portion152 andcircular portion154. To fully close,portions152 and154 deflect towardvalve seat132 and to openportions152 and154 deflect in the opposite direction towardvalve stop136. The stresses encountered byvalve plate134 are stresses that are both plus and minus in direction from the neutral normally open position. Thus, when comparing the stresses ofvalve plate134 with those encountered by the flap valve of a normally closed discharge valve, the stresses are significantly reduced. The normally closed flap valve begins in a position adjacent a valve seat when the flap valve is unstressed. As the valve begins to open the stresses begin at the unstressed condition and continue to grow as the flap valve opens. Thus they are undirectional from the unstressed condition. The present invention, by centering the stressed conditions ofvalve plate134 on both sides of the unstressed condition significantly reduces the stress loading experienced byvalve plate134.

In order to further reduce the stress loading and thus the life ofvalve plate134, the shape of contouredsurface148 ofvalve seat132 and contouredsurface172 ofvalve stop136 are chosen to ensure a gradual loading and minimizing of the stresses by distributing the loads over a broader area. Finally, the rounded contours and transitions betweenring150,rectangular portion152 andcircular portion154 are designed to eliminate stress risers. This elimination of stress risers, the equal distribution of the load and the reduction in the maximum stresses encountered significantly improves the life and performance fordischarge valve assembly130.

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.

Claims (33)

1. A scroll machine comprising:

a shell defining a discharge chamber;

a first scroll member having a first spiral wrap projecting outwardly from a first end cap;

a second scroll member having a second spiral wrap projecting outwardly from a second end cap, said second spiral wrap being intermeshed with said first spiral wrap;

a drive member for causing said scroll members to orbit relative to one another whereby said spiral wraps will create pockets of progressively changing volume between a suction pressure zone and a discharge pressure zone, said discharge pressure zone being in communication with said discharge chamber; and

a discharge valve disposed between said discharge pressure zone and said discharge chamber, said discharge valve being disposed within a recess formed by said first scroll member, said discharge valve being movable between a first, a second, and a third position, wherein:

said first position is a closed position where said discharge valve abuts a bottom surface of said recess and fluid flow between said discharge chamber and said discharge pressure zone is prohibited;

said second position is an open position where said discharge valve abuts said bottom surface of said recess and fluid flow between said discharge chamber and said discharge chamber and said discharge pressure zone is permitted at a first flow level; and

said third position is an open position where said discharge valve is spaced from said bottom surface of said recess and fluid flow between said discharge chamber and said discharge pressure zone is permitted at a second flow level greater than said first flow level.

2. The scroll machine according toclaim 1, wherein said discharge valve moves axially with respect to said first scroll member.

3. The scroll machine according toclaim 1, wherein fluid flows around an outer periphery of said discharge valve when said discharge valve is in said third position.

4. The scroll machine according toclaim 1, wherein a passage between said first scroll member and said discharge valve is opened when discharge valve moves from said second position to said third position.

5. The scroll machine according toclaim 1, wherein said discharge valve comprises a valve plate and a valve stop.

6. The scroll machine according toclaim 5, wherein said valve plate moves with respect to said valve stop when said discharge valve moves from said first position to said third position.

7. The scroll machine according toclaim 5, wherein said valve plate moves with respect to said first scroll member when said discharge valve moves from said second position to said third position.

8. The scroll machine according toclaim 1, wherein said discharge valve comprises a valve seat and a valve plate.

9. The scroll machine according toclaim 8, wherein said valve plate moves with respect to said valve seat when said discharge valve moves from said first position to said second position.

10. The scroll machine according toclaim 8, wherein said valve plate moves with respect to said first scroll member when said discharge valve moves from said second position to said third position.

11. The scroll machine according toclaim 1, wherein said discharge valve comprises a valve seat, a valve plate and a valve stop.

12. A scroll machine comprising:

a shell defining a discharge chamber;

a first scroll member having a first spiral wrap projecting outwardly from a first end plate;

a second scroll member having a second spiral wrap projecting outwardly from a second end plate, said second spiral wrap being intermeshed with said first spiral wrap;

a drive member for causing said scroll members to orbit relative to one another whereby said spiral wraps will create pockets of progressively changing volume between a suction pressure zone and a discharge pressure zone, said discharge pressure zone being in communication with said discharge chamber; and

a discharge valve assembly disposed between said discharge pressure zone and said discharge chamber, the complete assembly movable relative to said first scroll member and including a valve plate movable between a first open state and a closed state.

13. The scroll machine according to claim 12, wherein said discharge valve assembly moves axially with respect to said first scroll member.

14. The scroll machine according to claim 12, wherein said valve plate is normally in said first open state.

15. The scroll machine according to claim 12, wherein said discharge valve assembly is disposed within a recess formed by said first scroll member.

16. The scroll machine according to claim 12, wherein said discharge valve assembly further comprises a valve seat and a valve stop.

17. The scroll machine according to claim 16, wherein said valve plate moves with respect to said valve seat and said valve stop between said first open state and said closed state.

18. The scroll machine according to claim 16, wherein said valve plate engages said valve seat when said valve plate is in said closed state.

19. The scroll machine according to claim 16, wherein said valve plate is movable into a second open state.

20. The scroll machine according to claim 19, wherein said valve plate abuts said valve stop in said second open state.

21. The scroll machine according to claim 12, further comprising a biasing member applying a force on said discharge valve assembly to bias said discharge valve assembly in a first direction relative to said first scroll member.

22. The scroll machine according to claim 21, wherein said discharge valve assembly is movable in a second direction opposite to said first direction and against said force of said biasing member.

23. The scroll machine according to claim 12, wherein said discharge valve assembly is biased into engagement with said first scroll member.

24. The scroll machine according to claim 12, wherein said discharge valve assembly is movable between a first position and a second position relative to said first scroll member, said valve plate permitting communication between said discharge pressure zone and said discharge chamber when said discharge valve assembly is in either said first position or said second position and restricting communication between said discharge pressure zone and said discharge chamber when said valve plate is in said closed state and said discharge valve assembly is in said second position.

25. The scroll machine according to claim 24, wherein said discharge valve assembly abuts a surface of said first scroll member in said second position.

26. The scroll machine according to claim 24, further comprising a biasing member biasing said discharge valve assembly into said second position.

27. The scroll machine according to claim 24, wherein said discharge valve assembly is biased into said second position.

28. The scroll machine according to claim 12, wherein said discharge valve assembly and said valve plate cooperate to define a first open state, a second open state, a third open state, and a closed state.

29. The scroll machine according to claim 28, wherein said first open state, second open state, and said third open state provide three different flow levels between said discharge pressure zone and said discharge chamber and said closed state restricts flow between said discharge pressure zone and said discharge chamber.

30. The scroll machine according to claim 21, wherein said biasing member is a wave-ring.

31. The scroll machine according to claim 21, wherein said biasing member is received within a groove of said first scroll member.

32. The scroll machine according to claim 31, wherein said groove is an annular groove formed in a wall of said first scroll member.

33. The scroll machine according to claim 12, wherein movement of said valve plate between said first open state and said closed state is independent of movement of said discharge valve assembly relative to said first scroll member.

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