The scroll machine has a first and a second scroll member each having intermeshed scroll wraps. A compensation member is attached to one of the scrolls. As the scroll machine warms to operating temperature, the compensation member exerts a force on the one scroll member causing it to deflect. The deflection of the scroll member compensates for the unequal growth of the scroll wrap which is caused by a temperature difference between the radially inner section and the radially outer section of the scroll wrap.
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1. A scroll machine comprising:
a first scroll member including a first end plate having a first spiral wrap extending therefrom;
a second scroll member including a second end plate having a second spiral wrap extending therefrom, said second spiral wrap being intermeshed with said first spiral wrap such that a distal end of said first spiral wrap engages said second end plate and a distal end of said second spiral wrap engages said first end plate;
a drive member for causing said scroll members to orbit relative to one another whereby said spiral wraps create pockets of progressively changing volume between a suction pressure zone and a discharge pressure zone; and
a compensation member attached to one of said first and second scroll members and having a first reaction to a temperature change, said first reaction to said temperature change causing said one scroll member to maintain a sealed relationship between said distal end of said first spiral wrap and said second end plate and between said distal end of said second spiral wrap and said first end plate at said suction pressure zone and said discharge pressure zone.
33. A scroll machine comprising:
a non-orbiting scroll member having a first spiral wrap projecting outward from a first end plate;
an orbiting scroll member having a second spiral wrap projecting outward from a second end plate, said second spiral wrap being intermeshed with said first spiral wrap such that a distal end of said first spiral wrap engages said second end plate and a distal end of said second spiral wrap engages said first end plate;
a drive member for causing said orbiting scroll member to orbit relative to said non-orbiting scroll member whereby said spiral wraps create pockets of progressively changing volume between a suction pressure zone and a discharge pressure zone; and
a compensation member attached to one of said orbiting and non-orbiting scroll members and formed from a material having a first coefficient of thermal expansion, said one scroll member being formed from a material having a second coefficient of thermal expansion different than said first coefficient of thermal expansion, said compensation member will cause said one scroll member to maintain a sealed relationship between said distal end of said first spiral wrap and said second end plate and between said distal end of said second spiral wrap and said first end plate at said suction pressure zone and said discharge pressure zone upon heating of said compensation member.
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The present disclosure relates to scroll machines. More particularly, the present disclosure relates to scroll compressors having a pair of scroll members which incorporate a thermal compensation system which changes the contour of at least one of the end plates of the scroll members in response to changes in temperature.
The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
Scroll type machines are becoming more and more popular for use as compressors in both refrigeration as well as air conditioning 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 which progressively decrease in size as they travel from an outer suction port toward a center discharge port. Typically one of the scroll members is stationary and the other is orbiting. An electric motor is provided which operates to drive the orbiting scroll member via a suitable drive shaft affixed to the motor rotor. In a hermetic compressor, the bottom of the hermetic shell normally contains an oil sump for lubricating and cooling purposes.
Scroll compressors depend upon a number of seals to be created to define the moving or successive chambers. One type of seals which must be created are the seals between opposed flank surfaces of the wraps. These flank seals are created adjacent to the outer suction port and travel radially inward along the flank surface due to the orbiting movement of one scroll with respect to the other scroll. The other type of sealing is one required between the end plate of one scroll and the tip of the wrap of the other scroll. This tip to end plate sealing has been the subject of numerous designs and developments in the scroll compressor field.
One solution to the creation of tip seals has been to machine a groove in the end surface of the wrap and insert a sealing member which can be biased away from the wrap and towards the end plate of the opposite scroll. Unfortunately, due to the machining of the groove, the manufacture of the sealing member and the assembly of these components, the costs associated with incorporating tip seals are not insignificant. Also, the tip seals themselves introduce additional radial and tangential leak paths that are not insignificant, especially in smaller machines. They also introduce additional reliability and durability concerns as they are wear prone elements.
Other designs for scroll compressors have incorporated axial biasing of one scroll with respect to the opposing scroll. The axial biasing operates to urge the tips of the scroll members against their opposing end plate in order to enhance the sealing at the tip of the wrap. The biasing of one scroll member with respect to the opposing scroll member in conjunction with dimensional control of the scroll members themselves has allowed scroll compressors to be manufactured without separate tip sealing members between the tip of the wrap and the opposing end plate.
The dimensional control of the scroll members is capable of producing a scroll wrap which mates with the opposing end plate. When axial biasing is incorporated, the scroll wrap tips are biased against the opposing end plate to provide the necessary sealing. A scroll machine compresses fluid using fluid chambers which move radially inward toward the inner section of the scroll wrap while their volume is decreased to compress the fluid. The compression of the fluid causes the generation of heat such that the scroll wrap is hotter at its radially inner section than at its radially outer section. The difference in temperature of the inner and outer sections of the wrap will result in a difference in the thermal expansion between the inner and outer sections of the wrap and thus the possibility of creating a leak path between the scroll wrap tips and its opposing end plate in at least a portion of the scroll wrap. In addition to creating a leak path between the scroll wrap tips and the opposing end plate, the growth of the inner most section may result in reduced tip to end plate contact bearing area and the possibility of galling the end plate by the scroll wrap is created.
Various methods have been devised to accommodate the unequal growth in the height of the scroll wrap due to thermal expansion. Some designs have provided for machining the scroll wraps such that they are progressively shorter as they approach the central area. In this manner, once the compressor reaches an intended operating temperature, the unequal thermal expansion of the scroll wrap will create a matched height of the scroll wrap for both members. The disadvantages to this design approach include the inherent leak path which is present when the compressor is not operating at the intended operating temperature; as well as determining what the intended operating temperature is when the compressor is in an environment which can drastically change temperatures such as a compressor located outside where temperatures change between winter and summer. Additionally, the manufacturing techniques and controls to produce the tapered wrap can significantly add to the overall cost of the scroll machine. Other designs have proposed variations to the above described wrap height variation such as the radially outer portion being constant in height, the middle portion being progressively shorter and the radially inner portion being constant in height. The disadvantages to these designs are the same as those described above for the progressively shorter designs.
Continued development of scroll machines includes the development of methods for accommodating the difference in thermal expansion of the wraps which is caused by the temperature gradient which occurs between the radially outer portion and the radially inner portion of the scroll machine.
The present disclosure provides the art with a scroll machine which continuously adjusts to the variation of the height of the scroll wrap so that the tip of the wrap and the opposing end plate provide sealing contact between these components during the various operating temperatures experienced by the scroll wraps. The present disclosure utilizes a scroll member which has a first portion which is manufactured from a material having a first coefficient of thermal expansion and a second portion which is manufactured from a material having a second coefficient of thermal expansion. As the temperature of the scroll member changes, the two materials react differently to the temperature change due to the difference in their coefficient of thermal expansion to compensate for the thermal expansion and adjust the relationship between the scroll wrap and the opposing end plate. One aspect of this disclosure is that the cause of the distortion itself, that leads to improper sealing, namely the temperature distribution in the member, can be used to counteract the distortion.
Other advantages and objects of the present disclosure will become apparent to those skilled in the art from the subsequent detailed description, appended claims and drawings.
The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way.
The following description is merely exemplary in nature and is not intended to limit the present disclosure, 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 in
A drive shaft or crankshaft 30 having an eccentric crank pin 32 at the upper end thereof is rotatably journaled in a bearing 34 in main bearing housing 24 and a second bearing 36 in lower bearing housing 26. Crankshaft 30 has at the lower end a relatively large diameter concentric bore 38 which communicates with a radially outwardly inclined smaller diameter bore 40 extending upwardly therefrom to the top of crankshaft 30. Disposed within bore 38 is a stirrer 42. The lower portion of the interior shell 12 defines an oil sump 44 which is filled with lubricating oil to a level slightly below the lower end of a rotor 46 but above the lower end of stator end-turns of windings 48, and bore 38 acts as a pump to pump lubricating fluid up the crankshaft 30 and into bore 40 and ultimately to all of the various portions of the compressor which require lubrication.
Crankshaft 30 is rotatively driven by an electric motor including stator 28, windings 48 passing therethrough and rotor 46 press fitted on the crankshaft 30 and having upper and lower counterweights 50 and 52, respectively.
The upper surface of main bearing housing 24 is provided with a flat thrust bearing surface 54 on which is disposed an orbiting scroll member 56 having the usual spiral vane or wrap 58 extending upward from an end plate 60. Projecting downwardly from the lower surface of end plate 60 of orbiting scroll member 56 is a cylindrical hub having a journal bearing 62 therein and in which is rotatively disposed a drive bushing 64 having an inner bore 66 in which crank pin 32 is drivingly disposed. Crank pin 32 has a flat on one surface which drivingly engages a flat surface (not shown) formed in a portion of bore 66 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 coupling 68 is also provided positioned between orbiting scroll member 56 and main bearing housing 24 and keyed to orbiting scroll member 56 and a non-orbiting scroll member 70 to prevent rotational movement of orbiting scroll member 56. Oldham coupling 68 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 member 70 is also provided having a wrap 72 extending downwardly from an end plate 74 which is positioned in meshing engagement with wrap 58 of orbiting scroll member 56. Non-orbiting scroll member 70 has a centrally disposed discharge passage 76 which communicates with an upwardly open recess 78 which in turn is in fluid communication with a discharge muffler chamber 80 defined by cap 14 and partition 22. An annular recess 82 is also formed in non-orbiting scroll member 70 within which is disposed a seal assembly 84. Recesses 78 and 82 and seal assembly 84 cooperate to define axial pressure biasing chambers which receive pressurized fluid being compressed by wraps 58 and 72 so as to exert an axial biasing force on non-orbiting scroll member 70 to thereby urge the tips of respective wraps 58, 72 into sealing engagement with the opposed end plate surfaces of end plates 74 and 60, respectively. Seal assembly 84 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-orbiting scroll member 70 is designed to be mounted to main bearing housing 24 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.
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Orbiting scroll member 156 includes the usual spiral valve or wrap 158 extending upward from an end plate 160. Projecting downwardly from the lower surface of end plate 160 of orbiting scroll member 156 is a cylindrical hub for accommodating journal bearing 62 and drive bushing 64.
A non-orbiting scroll member 170 is designed to mate with orbiting scroll member 156. Non-orbiting scroll member 170 is provided with a wrap 172 extending downwardly from an end plate 174 which is positioned in meshing engagement with scroll wrap 158 of orbiting scroll member 156. Non-orbiting scroll member 170 has a centrally disposed discharge passage 176 which communicates with an upwardly open recess 178 which is designed to be in fluid communication with discharge muffler chamber 80.
Orbiting scroll member 156 defines an annular flange 190 projecting downwardly from the lower surface of end plate 160 of orbiting scroll member 156. Annular flange 190 defines an annular groove 192 within which is located annular ring 188. Annular ring 188 is press fit within annular groove 192 or secured within annular groove 192 by other means known in the art. The reaction to temperature change or the coefficient of thermal expansion of the material of annular ring 188 is greater than the reaction to temperature change or the coefficient of thermal expansion of the material orbiting scroll member 156.
The temperature compensation system illustrated in
Scroll compressor 110 fixes the position of non-orbiting scroll member 170 and orbiting scroll member 156 is provided with axial movement as is well known in the art. Scroll compressor 110 having axial compliant orbiting scroll member 156 is more tolerant of a convex shaped back surface than scroll compressor 10.
An orbiting scroll member 256 includes the usual spiral vane or wrap 258 extending upward from an end plate 260. Projecting downwardly from the lower surface of end plate 260 of orbiting scroll member 256 is a cylindrical hub for accommodating journal bearing 62 and drive bushing 64. Orbiting scroll member 256 is a direct replacement for orbiting scroll member 56.
Non-orbiting scroll member 270 is a direct replacement for non-orbiting scroll member 70 and non-orbiting scroll member 270 is designed to mate with orbiting scroll member 256. Non-orbiting scroll member 270 is provided with a wrap 272 extending downwardly from an end plate 274 and wrap 272 is positioned in meshing engagement with scroll wrap 258 of orbiting scroll member 256. Non-orbiting scroll member 270 has a centrally disposed discharge passage 276 which communicates with an upwardly open recess 278 which is designed to be in fluid communication with discharge muffler chamber 80. An annular recess 282 is also formed in non-orbiting scroll member 270 to accept seal assembly 84.
Non-orbiting scroll member 270 defines an annular portion 290 over which annular ring 288 is located. Annular ring 288 is press fit over annular portion 290 or secured to annular portion 290 by other means known in the art. The reaction to temperature change or the coefficient of thermal expansion for the material of annular ring 288 is less than the reaction to temperature change or the coefficient of thermal expansion of the material of non-orbiting scroll member 270. Annular ring 288 may be manufactured from standard wrought materials, composite materials, shaped memory alloys, phase change alloys or any other material known in the art that can provide the desired results.
An orbiting scroll member 356 includes the usual spiral vane or wrap 358 extending upward from an end plate 360. Projecting downwardly from the lower surface of end plate 360 of orbiting scroll member 356 is a cylindrical hub for accommodating journal bearing 62 and drive bushing 64. Orbiting scroll member 356 is a direct replacement for orbiting scroll member 56.
Non-orbiting scroll member 370 is a direct replacement for non-orbiting scroll member 70 and non-orbiting scroll member 370 is designed to mate with orbiting scroll member 356. Non-orbiting scroll member 370 is provided with a wrap 372 extending downwardly from an end plate 374 and wrap 372 is positioned in meshing engagement with scroll wrap 358 of orbiting scroll member 356. Non-orbiting scroll member 370 has a centrally disposed discharge passage 376 which communicates with an upwardly open recess 378 which is designed to be in fluid communication with discharge muffler chamber 80. An annular recess 382 is also formed in non-orbiting scroll member 370 to accept seal assembly 84.
Non-orbiting scroll member 370 defines an annular flange 390 projecting upwardly from end plate 374 of non-orbiting scroll member 370. Annular flange 390 defines an annular groove 392. Non-orbiting scroll member 370 further defines a plurality of bores 394 within each of which is disposed a respective thermal actuator 388. Annular flange 390 defines a plurality of bores 396 each of which is aligned with a respective bore 394. A fastener 398 is assembled into each bore 396 to provide cold temperature adjustment to a respective thermal actuator. As illustrated in
Referring to
While the above detailed description describes the preferred embodiment of the present disclosure, it should be understood that the present disclosure is susceptible to modification, variation and alteration without deviating from the scope and fair meaning of the subjoined claims.
Patent | Priority | Assignee | Title |
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4548555, | Sep 10 1982 | Sanden Corporation | Scroll type fluid displacement apparatus with nonuniform scroll height |
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Dec 28 2006 | Emerson Climate Technologies, Inc. | (assignment on the face of the patent) | / |
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