Discharge port for a scroll compressor

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 of FIG. 1;

FIG. 3 is a cross-sectional view of the fixed scroll member of FIG. 1, taken along line 3-3 of FIG. 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 of FIG. 5;

FIG. 7 is a cross-sectional view of the fixed scroll member of FIG. 5 taken along line 7-7 of FIG. 5;

FIG. 8A is a detail view of the fixed scroll member of FIG. 7 illustrating a valve assembly;

FIG. 8B is a detail view of a portion of the discharge port of the fixed scroll member of FIG. 8A;

FIG. 9 is a fragmentary, perspective view of the fixed scroll member of FIG. 5, and

FIG. 10 is an exploded, perspective view of the valve assembly and fixed scroll member of FIG. 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 to FIG. 4, scroll compressor 10 is shown, which includes a cylindrical main housing 12, bottom cap 14 with base 16 secured to a lower or first end 18 of housing 12, and top cap 20 secured to an upper or second end 22 of housing 12, each by a welding, brazing, or other suitable operation to thereby define an enclosed hermetic housing in which motor-compressor unit 24 of compressor 10 is disposed. Motor-compressor unit 24 generally includes a first, fixed scroll member 26, a second, orbiting scroll member 28, as well as crankcase 30, drive shaft 32, stator 34, rotor 36, outboard bearing assembly 38, and other components which are discussed below.

As illustrated in FIG. 4, fixed scroll member 26 generally includes base plate 40 with involute wrap 42 extending therefrom, discharge port 44 fluidly communicating with the central portion of wrap 42, and discharge check valve assembly 46 mounted to base plate 40 over discharge port 44. Additionally, fixed scroll member 26 includes an outer peripheral surface 48 having an annular shoulder or flange 50 which is received over, and supported upon, the annular upper end 22 of housing 12. The open end of top cap 20 is received over the outer peripheral surface 48 of fixed scroll member 26 and upper end 22 of housing 12, and is welded thereto to secure the foregoing components together. In this manner, fixed scroll member 26 is fixedly mounted to housing 12 and top cap 20, and the weight of fixed scroll member 26 is supported by housing 12. Optionally, outer peripheral surface 48 of fixed scroll member 26 may include an annular groove 52 in which a compressive O-ring seal 54 is disposed to provide a more robust fluid seal between fixed scroll member 26 and top cap 20.

Fixed scroll member 26 divides the interior of housing 12 into a suction chamber 56, in which motor-compressor unit 24 is positioned, and which is in fluid communication with suction inlet port 58 of housing 12, and a discharge chamber 60, defined between fixed scroll member 26 and top cap 20, which is in fluid communication with discharge outlet port 62 of top cap 20. Fixed scroll member 26 is attached to crankcase 30 via a plurality of fasteners (not illustrated), such as threaded bolts, for example, which pass through bores 27 (FIG. 5) in fixed scroll member 26 and are threaded into threaded holes (not illustrated) in crankcase 30. Crankcase 30 additionally includes a thrust bearing surface 72 for supporting orbiting scroll member 28.

Orbiting scroll member 28 includes base plate 74, an annular hub 76 extending from one side of base plate 74 which is drivably coupled to an eccentric end 78 of drive shaft 32, and an involute wrap 80 extending from an opposite side of base plate 74, which is in meshing engagement with wrap 42 of fixed scroll member 26. Oldham coupling 82 is coupled between fixed and orbiting scroll members 26 and 28 in a known manner, such as by first and second pairs of keys projecting from respective opposite sides of Oldham coupling 82, which are slidably engaged within slots or keyways in fixed and orbiting scroll members 26 and 28, respectively. Oldham coupling 82 functions in a known manner to prevent rotation of orbiting scroll member 28 and to confine the movement of orbiting scroll member 28 to orbital movement. Drive shaft 32 includes upper portion 84 rotatably supported by main bearing 68 of crankcase 30, and eccentric end 78 of drive shaft 32 is drivably fitted within annular hub 76 of orbiting scroll member 26.

In operation of compressor 10, electrical energization of stator 34 causes rotor 36 and drive shaft 32 to rotate within stator 34 in a known manner. Rotation of drive shaft 32 in turn drives orbiting scroll member 28 in an orbiting manner to define a plurality of variable-volume working pockets between wraps 80 and 42 of orbiting scroll member 28 and fixed scroll member 26, respectively. Working fluid at suction pressure within suction chamber 56 is drawn into the working pockets defined between the wraps of orbiting and fixed scroll members 28 and 26 and is compressed with the working pockets. The compressed working fluid is discharged through discharge port 44 of fixed scroll member 26 and discharge check valve assembly 46 into discharge chamber 60 at discharge pressure, and thereafter passes through discharge outlet port 62 of compressor 10 into a refrigeration system (not shown).

As illustrated in FIGS. 1-3, a knwon fixed scroll member 100 includes involute wrap 102 extending from base plate 104. Involute wrap 102 includes inner end portion 105. Inner end portion 105 includes arcuate surface 106 and substantially flat surface 108. The mating wrap of the orbiting scroll member, partially illustrated in phantom in FIG. 2, includes a flat surface that corresponds with flat surface 108 which, together, define the final pressure pocket of the working fluid before it is expelled through discharge port 110. Discharge port 110 extends between surfaces 112 and 114 of base plate 104 and is substantially cylindrical along its entire length.

As illustrated in FIG. 2, inner end portion 105, and in particular, flat surface 108, extends over a portion of opening 116 of cylindrical discharge port 110. As a result, as illustrated in FIG. 3, an abrupt change in geometry, represented as section 115, occurs between involute wrap 102 and base plate 104 near opening 116 and includes sharp corner pocket 117 and ledge 119. 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, along surface 108, among other surfaces, and results in a bending stress at proximal end 120 of wrap end portion 105. Additional bending stress at proximal end 120 can result from a force acting at distal end 118 of wrap end 105 generated by frictional interaction between the orbiting scroll member and a tip seal (not illustrated) positioned in groove 101 of wrap 102. As a result of the abrupt change in geometry at section 115, the bending stress is magnified, or concentrated, in this area. Stated in another way, the abrupt change in geometry constricts the flow of stress from involute wrap 102 to base plate 104 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 to FIGS. 5-10, and in particular FIG. 7, discharge port 44 includes first section 45 and second section 47. First section 45 includes substantially straight side 49 disposed adjacent, and substantially parallel to, substantially flat surface 51 (FIG. 9) of inner end portion 53 of involute wrap 42. First section 45 further includes curved side 55 (FIGS. 8A and 9) opposite flat surface 49 forming, in co-operation with flat surface 49, substantially D-shaped opening 57 (FIG. 9). Second section 47 includes substantially cylindrical surface 59 extending from first section 45 to side 61 of base plate 40. Thus, in this embodiment, discharge port 44 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 in FIGS. 7, 8A and 8B, D-shaped first section 45 increases the material at the interface between involute wrap 42 and base plate 40 as compared to the known fixed scroll member illustrated in FIG. 3. As a result, the fixed scroll member has a greater resistance to stress loading at this interface. Furthermore, the change in geometry between wrap 42 and plate 40 is not as abrupt as the change in geometry in the known fixed scroll member. More specifically, in this embodiment, the cross-sectional thickness of inner end portion 53, illustrated as dimension 63, is only slightly larger than the narrow section, illustrated as dimension 64, at the interface between wrap 42 and plate 40. 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 in FIGS. 7-9, flat surface 49 of first section 45 and flat surface 51 of involute wrap 42 are not co-planar. As a result, shelf 66 extends substantially perpendicularly between flat surfaces 49 and 51, and in particular, shelf 66 extends between radiused corner pocket 67 and edge 69. Similar to the above, corner pocket 67 induces a stress concentration, or restriction to the flow of stress, between involute wrap 42 and base plate 40. As illustrated in FIGS. 8A and 8B, to reduce the stress concentration and improve the flow of stress, fillet, or radius, 70 is provided and extends from flat surface 51 and blends into ledge 66. In other embodiments, fillet 70 can extend between flat surface 51 and flat surface 49 of fist section 45. Fillet 70 adds material to the cross-sectional thickness at this location, thereby lowering the stress loading, and providing a less abrupt transition between involute wrap 42 and plate 40, thereby lowering the stress concentration. As fillet 70 lowers the stress concentration at this location, the propensity for stress-induced failure at this location is reduced. Although fillet 70 blends the transition between wrap 42 and plate 40 in this embodiment, other geometries and configurations may be used to accomplish the effect thereof in other embodiments.

As illustrated in FIGS. 7, 8A and 10, discharge valve assembly 46 is affixed to base plate 40 of fixed scroll member 26. Discharge valve assembly 46 includes flexible valve plate 71 and valve stopper 73 which are affixed to side 61 of plate 40 by fastener 75. Base plate 40 includes threaded recess 81 for threadingly receiving fastener 75 so that an end of valve plate 71 and valve stopper 73 may be fastened thereto. The opposite, or free, ends of valve plate 71 and valve stopper 73 are positioned proximate discharge port 44. The free end of valve plate 71 includes head portion 79 which is disposed over the circular profile of second section 47 of discharge port 44. In operation, head portion 79 prevents working fluid from exiting through discharge port 44 until a desired discharge pressure of the working fluid is reached. Once the desired pressure is reached, head portion 79 is lifted away from the discharge port by the working fluid resiliently flexing valve plate 71. Once the pressure of the working fluid exiting discharge port 44 has reduced, valve plate 71 resiliently straightens placing head portion 79 over discharge port 44 once again. To prevent valve plate 71 from over-flexing, valve stopper 73 limits the travel of valve plate 71 by providing a substantially rigid stop in a desired spaced relation to valve plate 71 when valve plate 71 is resting against discharge port 44. In this embodiment, plate 40 includes recess 77, in which valve plate 71 and valve stopper 73 are disposed therein, to reduce the axial dimension of the fixed scroll member.

As illustrated in FIG. 10, head portion 79 is substantially circular and covers the substantially circular profile of second section 47. The circular profile of second section 47 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 of second section 47 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

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 of claim 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 of claim 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 of claim 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 of claim 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 of claim 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 of claim 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 of claim 6, wherein said shelf portion overlaps said second section of said discharge port when viewed in section.

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

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