US20060269433A1 - Discharge port for a scroll compressor - Google Patents

Abstract

A scroll compressor including an improved fixed scroll member, and in particular, an improved discharge port in the fixed scroll member. In one embodiment, a discharge port extends through the fixed scroll member and includes at least two sections defining different cross sectional shapes or profiles. A first section of the discharge port is in direct fluid communication with the high pressure working pocket between the scrolls, and includes a profile that decreases the stress loading and the stress concentration in the fixed scroll member. A second section of the discharge port includes a profile that improves the flow of working fluid through the discharge port and is shaped for cooperation with the discharge valve assembly.

Description

BACKGROUND OF THE INVENTION
• 1. Field of the Invention
• The present invention relates to scroll compressors, and in particular, to the discharge assembly of a scroll compressor.
• 2. Description of the Related Art
• Known compressors, including scroll compressors, typically have a three-part housing, including a generally cylindrical main housing, and end caps attached to opposite ends of the main housing. In the case of a scroll compressor, a fixed scroll member or other partition divides the housing interior into a suction chamber and a discharge chamber. In a typical low-side compressor, a motor-compressor unit is mounted within the housing and positioned within the suction chamber. The motor-compressor unit includes a non-orbiting scroll member which is fixed with respect to the housing, and an orbiting scroll member which includes an involute wrap in meshing engagement with the involute wrap of the non-orbiting scroll member. The orbiting scroll member is driven by the motor for orbital movement to define a plurality of variable-volume working pockets between the wraps of the non-orbiting and orbiting scroll members to compress the working fluid.
• The motor-compressor unit is operable to compress a working fluid at suction pressure, which enters the suction chamber through a suction port of the housing, to a discharge pressure. The motor-compressor unit then discharges the compressed working fluid through a discharge port in the non-orbiting, or fixed scroll member, into the discharge chamber. The working fluid then exits the housing through a discharge port in the housing. During operation, the fixed scroll member, particularly in the area thereof near the discharge port, may be subjected to significant stresses and could be potentially prone to stress induced damage in this area.
SUMMARY OF THE INVENTION
• The present invention provides a scroll compressor including an improved fixed scroll member, and in particular, an improved discharge port in the fixed scroll member. In one embodiment, a discharge port extends through the fixed scroll member and includes at least two sections defining different cross sectional shapes or profiles. A first section of the discharge port is in direct fluid communication with the high pressure working pocket between the scrolls, and includes a profile that decreases the stress loading and the stress concentration in the fixed scroll member. A second section of the discharge port includes a profile that improves the flow of working fluid through the discharge port and is shaped for cooperation with the discharge valve assembly.
• In one form of the invention, a scroll compressor includes a housing, a motor-compressor assembly disposed within the housing including a crankcase and a stator, rotor, and drive shaft assembly, the drive shaft rotatably supported by the crankcase, a first scroll member fixed with respect to the housing, including a base plate having a first side and an opposite second side, a first wrap extending from the first side, and a discharge port extending through the base plate and including a first section disposed adjacent the first side and having a non-circular profile, the first section transitioning into a second section disposed adjacent the second side and having a substantially circular profile, and a second scroll member coupled to the drive shaft for orbital movement, the second scroll member including a second wrap intermeshed with the first wrap.
• In another form of the invention, a scroll compressor includes a housing, a motor-compressor assembly disposed within the housing including a crankcase and a stator, rotor, and drive shaft assembly, the drive shaft rotatably supported by the crankcase, a first scroll member fixed with respect to the housing comprising a base plate having a first side and an opposite second side, a first wrap extending from the first side of the base plate, the wrap including a inner end portion having a substantially flat surface, and a discharge port extending through the base plate and including a first section disposed adjacent the first side of the base plate, the discharge portion further including a second section disposed adjacent the second side of the base plate, the second section having a greater cross-sectional area than the first section, and a second scroll member coupled to the drive shaft for orbital movement, the second scroll member including a second wrap intermeshed with the first wrap.
BRIEF DESCRIPTION OF THE DRAWINGS
• The above-mentioned and other features and advantages of this invention, and the manner of attaining them, will become more apparent and the invention itself will be better understood by reference to the following description of an embodiment of the invention taken in conjunction with the accompanying drawings, wherein:
• FIG. 1 is a perspective view of a known fixed scroll member;
• FIG. 2 is an end detail view of the fixed scroll member ofFIG. 1;
• FIG. 3 is a cross-sectional view of the fixed scroll member ofFIG. 1, taken along line3-3 ofFIG. 1;
• FIG. 4 is a cross-sectional, elevation view of a scroll compressor in accordance with the present invention;
• FIG. 5 is a perspective view of a fixed scroll member in accordance with the present invention;
• FIG. 6 is an end detail view of the fixed scroll member ofFIG. 5;
• FIG. 7 is a cross-sectional view of the fixed scroll member ofFIG. 5 taken along line7-7 ofFIG. 5;
• FIG. 8A is a detail view of the fixed scroll member ofFIG. 7 illustrating a valve assembly;
• FIG. 8B is a detail view of a portion of the discharge port of the fixed scroll member ofFIG. 8A;
• FIG. 9 is a fragmentary, perspective view of the fixed scroll member ofFIG. 5, and
• FIG. 10 is an exploded, perspective view of the valve assembly and fixed scroll member ofFIG. 5.
• Corresponding reference characters indicate corresponding parts throughout the several views. The exemplification set out herein illustrates one preferred embodiment of the invention, in one form, and such exemplification is not to be construed as limiting the scope of the invention in any manner.
DETAILED DESCRIPTION
• Referring toFIG. 4,scroll compressor10 is shown, which includes a cylindricalmain housing12,bottom cap14 withbase16 secured to a lower orfirst end18 ofhousing12, andtop cap20 secured to an upper orsecond end22 ofhousing12, each by a welding, brazing, or other suitable operation to thereby define an enclosed hermetic housing in which motor-compressor unit24 ofcompressor10 is disposed. Motor-compressor unit24 generally includes a first, fixedscroll member26, a second, orbitingscroll member28, as well ascrankcase30,drive shaft32, stator34, rotor36,outboard bearing assembly38, and other components which are discussed below.
• As illustrated inFIG. 4,fixed scroll member26 generally includesbase plate40 withinvolute wrap42 extending therefrom,discharge port44 fluidly communicating with the central portion ofwrap42, and dischargecheck valve assembly46 mounted tobase plate40 overdischarge port44. Additionally, fixedscroll member26 includes an outerperipheral surface48 having an annular shoulder orflange50 which is received over, and supported upon, the annularupper end22 ofhousing12. The open end oftop cap20 is received over the outerperipheral surface48 of fixedscroll member26 andupper end22 ofhousing12, and is welded thereto to secure the foregoing components together. In this manner, fixedscroll member26 is fixedly mounted tohousing12 andtop cap20, and the weight of fixedscroll member26 is supported byhousing12. Optionally, outerperipheral surface48 of fixedscroll member26 may include anannular groove52 in which a compressive O-ring seal54 is disposed to provide a more robust fluid seal between fixedscroll member26 andtop cap20.
• Fixedscroll member26 divides the interior ofhousing12 into asuction chamber56, in which motor-compressor unit24 is positioned, and which is in fluid communication withsuction inlet port58 ofhousing12, and adischarge chamber60, defined betweenfixed scroll member26 andtop cap20, which is in fluid communication withdischarge outlet port62 oftop cap20. Fixedscroll member26 is attached tocrankcase30 via a plurality of fasteners (not illustrated), such as threaded bolts, for example, which pass through bores27 (FIG. 5) infixed scroll member26 and are threaded into threaded holes (not illustrated) incrankcase30. Crankcase30 additionally includes athrust bearing surface72 for supporting orbitingscroll member28.
• Orbiting scroll member28 includesbase plate74, anannular hub76 extending from one side ofbase plate74 which is drivably coupled to aneccentric end78 ofdrive shaft32, and aninvolute wrap80 extending from an opposite side ofbase plate74, which is in meshing engagement withwrap42 of fixedscroll member26. Oldhamcoupling82 is coupled between fixed and orbitingscroll members26 and28 in a known manner, such as by first and second pairs of keys projecting from respective opposite sides of Oldhamcoupling82, which are slidably engaged within slots or keyways in fixed and orbitingscroll members26 and28, respectively. Oldhamcoupling82 functions in a known manner to prevent rotation of orbitingscroll member28 and to confine the movement of orbitingscroll member28 to orbital movement.Drive shaft32 includesupper portion84 rotatably supported by main bearing68 ofcrankcase30, andeccentric end78 ofdrive shaft32 is drivably fitted withinannular hub76 of orbitingscroll member26.
• In operation ofcompressor10, electrical energization of stator34 causes rotor36 anddrive shaft32 to rotate within stator34 in a known manner. Rotation ofdrive shaft32 in turn drives orbitingscroll member28 in an orbiting manner to define a plurality of variable-volume working pockets betweenwraps80 and42 of orbitingscroll member28 and fixedscroll member26, respectively. Working fluid at suction pressure withinsuction chamber56 is drawn into the working pockets defined between the wraps of orbiting and fixedscroll members28 and26 and is compressed with the working pockets. The compressed working fluid is discharged throughdischarge port44 offixed scroll member26 and dischargecheck valve assembly46 intodischarge chamber60 at discharge pressure, and thereafter passes throughdischarge outlet port62 ofcompressor10 into a refrigeration system (not shown).
• As illustrated inFIGS. 1-3, a knwon fixedscroll member100 includes involutewrap102 extending frombase plate104. Involutewrap102 includesinner end portion105.Inner end portion105 includesarcuate surface106 and substantiallyflat surface108. The mating wrap of the orbiting scroll member, partially illustrated in phantom inFIG. 2, includes a flat surface that corresponds withflat surface108 which, together, define the final pressure pocket of the working fluid before it is expelled throughdischarge port110.Discharge port110 extends betweensurfaces112 and114 ofbase plate104 and is substantially cylindrical along its entire length.
• As illustrated inFIG. 2,inner end portion105, and in particular,flat surface108, extends over a portion of opening116 ofcylindrical discharge port110. As a result, as illustrated inFIG. 3, an abrupt change in geometry, represented assection115, occurs betweeninvolute wrap102 andbase plate104near opening116 and includessharp corner pocket117 andledge119. Such an abrupt change in geometry forms an area of potentially significant stress concentration during the operation of the compressor. More specifically, as working fluid is pressurized between the involute wraps of the orbiting and non-orbiting scroll members, the pressurized fluid exerts a force onto the scroll members. This force acts, in a substantially uniformly distributed manner, alongsurface108, among other surfaces, and results in a bending stress atproximal end120 ofwrap end portion105. Additional bending stress atproximal end120 can result from a force acting atdistal end118 ofwrap end105 generated by frictional interaction between the orbiting scroll member and a tip seal (not illustrated) positioned ingroove101 ofwrap102. As a result of the abrupt change in geometry atsection115, the bending stress is magnified, or concentrated, in this area. Stated in another way, the abrupt change in geometry constricts the flow of stress frominvolute wrap102 tobase plate104 resulting in significant stress concentration at this location.
• To ameliorate this problem, a discharge port in the fixed scroll compressor according to the present invention can include several sections having different cross-sections, or profiles, to reduce the stress loading and the stress concentration that occurs at the location between the involute wrap and the base plate. Referring toFIGS. 5-10, and in particularFIG. 7, dischargeport44 includesfirst section45 andsecond section47.First section45 includes substantiallystraight side49 disposed adjacent, and substantially parallel to, substantially flat surface51 (FIG. 9) ofinner end portion53 ofinvolute wrap42.First section45 further includes curved side55 (FIGS. 8A and 9) oppositeflat surface49 forming, in co-operation withflat surface49, substantially D-shaped opening57 (FIG. 9).Second section47 includes substantiallycylindrical surface59 extending fromfirst section45 toside61 ofbase plate40. Thus, in this embodiment, dischargeport44 includes two sections having different profiles, a section having a substantially D-shaped profile and a second section having a substantially cylindrical profile. Preferably, the profile of a second section defines a larger cross-sectional area than the profile of a first section.
• As illustrated inFIGS. 7, 8A and8B, D-shapedfirst section45 increases the material at the interface betweeninvolute wrap42 andbase plate40 as compared to the known fixed scroll member illustrated inFIG. 3. As a result, the fixed scroll member has a greater resistance to stress loading at this interface. Furthermore, the change in geometry betweenwrap42 andplate40 is not as abrupt as the change in geometry in the known fixed scroll member. More specifically, in this embodiment, the cross-sectional thickness ofinner end portion53, illustrated asdimension63, is only slightly larger than the narrow section, illustrated asdimension64, at the interface betweenwrap42 andplate40. As a result, the resistance to stress through the narrow section is improved and the concentration of stress at this location is reduced.
• Notably, in this embodiment, as illustrated inFIGS. 7-9,flat surface49 offirst section45 andflat surface51 ofinvolute wrap42 are not co-planar. As a result,shelf66 extends substantially perpendicularly betweenflat surfaces49 and51, and in particular,shelf66 extends between radiusedcorner pocket67 andedge69. Similar to the above,corner pocket67 induces a stress concentration, or restriction to the flow of stress, betweeninvolute wrap42 andbase plate40. As illustrated inFIGS. 8A and 8B, to reduce the stress concentration and improve the flow of stress, fillet, or radius,70 is provided and extends fromflat surface51 and blends intoledge66. In other embodiments,fillet70 can extend betweenflat surface51 andflat surface49 offist section45.Fillet70 adds material to the cross-sectional thickness at this location, thereby lowering the stress loading, and providing a less abrupt transition betweeninvolute wrap42 andplate40, thereby lowering the stress concentration. Asfillet70 lowers the stress concentration at this location, the propensity for stress-induced failure at this location is reduced. Althoughfillet70 blends the transition betweenwrap42 andplate40 in this embodiment, other geometries and configurations may be used to accomplish the effect thereof in other embodiments.
• As illustrated inFIGS. 7, 8A and10,discharge valve assembly46 is affixed tobase plate40 of fixedscroll member26.Discharge valve assembly46 includesflexible valve plate71 andvalve stopper73 which are affixed toside61 ofplate40 byfastener75.Base plate40 includes threadedrecess81 for threadingly receivingfastener75 so that an end ofvalve plate71 andvalve stopper73 may be fastened thereto. The opposite, or free, ends ofvalve plate71 andvalve stopper73 are positionedproximate discharge port44. The free end ofvalve plate71 includeshead portion79 which is disposed over the circular profile ofsecond section47 ofdischarge port44. In operation,head portion79 prevents working fluid from exiting throughdischarge port44 until a desired discharge pressure of the working fluid is reached. Once the desired pressure is reached,head portion79 is lifted away from the discharge port by the working fluid resiliently flexingvalve plate71. Once the pressure of the working fluid exitingdischarge port44 has reduced,valve plate71 resiliently straightens placinghead portion79 overdischarge port44 once again. To preventvalve plate71 from over-flexing,valve stopper73 limits the travel ofvalve plate71 by providing a substantially rigid stop in a desired spaced relation tovalve plate71 whenvalve plate71 is resting againstdischarge port44. In this embodiment,plate40 includes recess77, in whichvalve plate71 andvalve stopper73 are disposed therein, to reduce the axial dimension of the fixed scroll member.
• As illustrated inFIG. 10,head portion79 is substantially circular and covers the substantially circular profile ofsecond section47. The circular profile ofsecond section47 can be manufactured by using a drill press or other common drilling process, as is well known in the art, thereby decreasing the time, and cost, required to construct the compressor. Further, in one embodiment, the circular profile ofsecond section47 can accommodate an existing circular valve member thereby reducing the amount of unique parts, and cost, required to construct the compressor. Thus, an advantage of the present form of the invention includes a first section, which reduces the stress loading and the stress concentration between the involute wrap and the base plate, and a second section which improves the manufacturability, and cost, of the compressor. In other embodiments, the discharge port can include more than two sections to achieve the advantages discussed above.
• While this invention has been described as having a preferred design, the present invention can be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains and which fall within the limits of the appended claims.

Claims (21)

1. A scroll compressor, comprising:

a housing;

a motor-compressor assembly disposed within said housing, including a crankcase, and a stator, rotor, and drive shaft assembly, said drive shaft rotatably supported by said crankcase;

a first scroll member fixed with respect to said housing, comprising:

a base plate having a first side and an opposite second side;

a first wrap extending from said first side; and

a discharge port extending through said base plate and including a first section disposed adjacent said first side and having a non-circular profile, said first section transitioning into a second section disposed adjacent said second side and having a substantially circular profile; and

a second scroll member coupled to said drive shaft for orbital movement, said second scroll member including a second wrap intermeshed with said first wrap.

2. The scroll compressor ofclaim 1, wherein said first wrap includes an inner end portion having a substantially flat surface disposed adjacent said first section of said discharge port.

3. The scroll compressor ofclaim 2, wherein said second wrap includes an inner end portion having a substantially flat surface cooperatively aligned with said substantially flat surface of said inner end portion of said first wrap.

4. The scroll compressor ofclaim 2, wherein said first section of said discharge port includes a substantially straight side disposed adjacent said substantially flat surface of said end portion of said first wrap, and an opposite curved side.

5. The scroll compressor ofclaim 4, wherein said substantially straight and said curved sides of said first section of said discharge port define a substantially D-shaped profile.

6. The scroll compressor ofclaim 4, wherein said base plate includes a shelf portion disposed between said inner end portion of said first wrap and said first section of said discharge port.

7. The scroll compressor ofclaim 6, wherein said base plate further includes a fillet radius at an intersection of said shelf portion and said substantially flat surface of said end portion of said first wrap.

8. The scroll compressor ofclaim 6, wherein said shelf portion overlaps said second section of said discharge port when viewed in section.

9. The scroll compressor ofclaim 1, further comprising a discharge valve assembly, including:

a flexible valve plate fixed to said second side of said base plate, said valve plate including a head portion disposed adjacent said second section of said discharge port; and

a valve stopper fixed to said second side of said base plate and disposed in spaced relation with respect to said head portion of said valve plate.

10. The scroll compressor ofclaim 9, wherein said second side of said base plate includes a recess, said valve plate and valve stopper disposed within said recess.

11. The scroll compressor ofclaim 1, wherein said first scroll member partitions an interior of said housing into a suction chamber and a discharge chamber, and said motor-compressor unit is disposed within said suction chamber.

12. A scroll compressor, comprising:

a housing;

a motor-compressor assembly disposed within said housing, including a crankcase, and a stator, rotor, and drive shaft assembly, said drive shaft rotatably supported by said crankcase;

a first scroll member fixed with respect to said housing, comprising:

a base plate having a first side and an opposite second side;

a first wrap extending from said first side of said base plate, said wrap including a inner end portion having a substantially flat surface; and

a discharge port extending through said base plate and including a first section disposed adjacent said first side of said base plate, said discharge portion further including a second section disposed adjacent said second side of said base plate, said second section having a greater cross-sectional area than said first section; and

a second scroll member coupled to said drive shaft for orbital movement, said second scroll member including a second wrap intermeshed with said first wrap.

13. The scroll compressor ofclaim 12, said first section of said discharge port having a substantially straight side disposed substantially parallel with said substantially flat side of said end portion of said first wrap, and an opposite curved side.

14. The scroll compressor ofclaim 13, wherein said substantially straight and said curved sides of said first section of said discharge port define a substantially D-shaped profile.

15. The scroll compressor ofclaim 12, wherein said second wrap includes an inner end portion having a substantially flat surface disposed substantially parallel with said substantially flat surface of said end portion of said first wrap.

16. The scroll compressor ofclaim 12, wherein said first side of said base plate further comprises:

a shelf portion disposed between said discharge port and said inner end portion of said first wrap; and

a fillet radius defined at an intersection of said shelf portion and said inner end portion of said first wrap.

17. The scroll compressor ofclaim 12, wherein said second section of said discharge port has a substantially circular profile.

18. The scroll compressor ofclaim 17, wherein said base plate includes a shelf portion disposed between said first wrap inner end portion and said discharge port, at least a portion of said shelf portion overlapping said second section of said discharge port when viewed in section.

19. The scroll compressor ofclaim 12, wherein said first scroll member partitions an interior of said housing into a suction chamber and a discharge chamber, and said motor-compressor unit is disposed within said suction chamber.

20. The scroll compressor ofclaim 12, further comprising a discharge valve assembly, including:

a flexible valve plate fixed to said second side of said base plate, said valve plate including a head portion disposed adjacent said discharge port; and

a valve stopper fixed to said second side of said base plate and disposed in spaced relation with respect to said valve plate head portion.

21. The scroll compressor ofclaim 12, wherein said second side of said base plate includes a recess, said valve plate and valve stopper disposed within said recess.

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