Abstract:
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.

Description:
FIELD 
     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. 
     BACKGROUND AND SUMMARY 
     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. 
    
    
     
       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. 
         FIG. 1  is a vertical cross-sectional view through the center of a scroll type refrigeration compressor incorporating a compensation system in accordance with the present disclosure; 
         FIG. 2  is a schematic view of a prior art orbiting and non-orbiting scroll members at normal room temperature; 
         FIG. 3  is a schematic view of the prior art orbiting and non-orbiting scroll members illustrated in  FIG. 2  at an elevated temperature without the influence of the compensation member of the present disclosure; 
         FIG. 4  is a schematic view of the orbiting and non-orbiting scroll members illustrated in  FIG. 1  at normal room temperature; 
         FIG. 5  is a schematic view of the orbiting and non-orbiting scroll members shown in  FIG. 4  at an elevated operating temperature with the influence of the compensation member; 
         FIG. 6  is a schematic view of an orbiting and non-orbiting scroll members at an elevated operating temperature with the influence of a compensation member in accordance with another embodiment of the present disclosure; 
         FIG. 7  is a schematic view of an orbiting and non-orbiting scroll members in accordance with another embodiment of the present disclosure; 
         FIG. 8  is a schematic view of the orbiting and non-orbiting scroll members shown in  FIG. 7  at an elevated temperature with the influence of the compensation member; 
         FIG. 9  is a schematic view of an orbiting and non-orbiting scroll members in accordance with another embodiment of the present disclosure; 
         FIG. 10  is a schematic view of the orbiting and non-orbiting scroll members shown in  FIG. 7  at an elevated temperature with the influence of the compensation member; 
         FIG. 11  is a top plan view of the non-orbiting scroll member illustrated in  FIGS. 9 and 10 ; 
         FIG. 12  is a cross-sectional view of one of the thermal actuators illustrated in  FIGS. 9 and 10  at normal environmental temperature; and 
         FIG. 13  is a cross-sectional view of the thermal actuator illustrated in  FIG. 12  at normal operating temperatures. 
     
    
    
     DESCRIPTION 
     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  FIG. 1  a scroll compressor which incorporates a compensation system in accordance with the present disclosure which is designated generally by reference numeral  10 . Compressor  10  comprises a generally cylindrical hermetic shell  12  having welded at the upper end thereof a cap  14  and at the lower end thereof a base  16  having a plurality of mounting feet (not shown) integrally formed therewith. Cap  14  is provided with a refrigerant discharge fitting  18  which may have the usual discharge valve therein (not shown). Other major elements affixed to the shell include a transversely extending partition  22  which is welded about its periphery at the same point that cap  14  is welded to shell  12 , a main bearing housing  24  which is suitably secured to shell  12  and a lower bearing housing  26  also having a plurality of radially outwardly extending legs each of which is also suitably secured to shell  12 . A motor stator  28  which is generally square in cross-section but with the corners rounded off is press fitted into shell  12 . The flats between the rounded corners on the stator provide passageways between the stator and shell, which facilitate the return flow of lubricant from the top of the shell to the bottom. 
     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&#39;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&#39;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. 
     Referring now to  FIGS. 2 and 3 , a prior art set of scroll members without the temperature compensation in accordance with the present disclosure is illustrated.  FIG. 2  illustrates an orbiting scroll member  56 ′ and a non-orbiting scroll member  70 ′ at a normal environmental temperature. The surface of end plate  60 ′ of the orbiting scroll member  56 ′ extending between scroll wrap  58 ′ is formed as a generally planar surface. Similarly, the surface of end plate  74 ′ of the non-orbiting scroll member  70 ′ extending between scroll wrap  72 ′ is also formed as a generally planar surface. In this manner, when orbiting scroll member  56 ′ and non-orbiting scroll member  70 ′ are assembled, the flank surfaces of scroll wraps  58 ′ and  72 ′ engage each other, the tips of scroll wrap  58 ′ engage end plate  74 ′ and the tips of scroll wrap  72 ′ engage end plate  60 ′ to provide for the sealing of the compression pockets. 
       FIG. 3  illustrates the thermal expansion effects due to normal operating temperature on prior art orbiting scroll member  56 ′ and non-orbiting scroll member  70 ′ without the compensating effect of the temperature compensation system of the present disclosure. The higher temperature of the radially inner portion of wraps  58 ′ and  72 ′ cause the radially inner portion of wraps  58 ′ and  72 ′ to grow to a larger extent than the radially outer portion of the wraps causing the tip of wraps  58 ′ and  72 ′ to each form somewhat of a convex shape while the mating surface of end plates  60 ′ and  74 ′ maintain a general planar configuration. The engagement between the scroll wraps  58 ′ and  72 ′ and the respective scroll tips and end plates  74 ′ and  60 ′ will result in a leak path at the radially outer portion between the tips of wraps  58 ′ and  72 ′ and end plates  74 ′ and  60 ′, respectively. 
     Referring now to  FIGS. 1 ,  4  and  5 , the temperature compensation system in accordance with the present disclosure comprises an annular ring  88  attached to non-orbiting scroll member  70 . Non-orbiting scroll member  70  defines an annular flange  90  projecting upwardly from end plate  74  of non-orbiting scroll member  70 . Annular flange  90  defines an annular groove  92  within which is located annular ring  88 . Annular ring  88  is press fit within annular groove  92  or secured within annular groove  92  by other means known in the art. The reaction to temperature change or the coefficient of thermal expansion for the material of annular ring  88  is greater than the reaction to temperature change or the coefficient of thermal expansion of the material of non-orbiting scroll member  70 . Annular ring  88  may be manufactured from standard wrought materials, composite materials, shaped memory alloys, phase changing alloys or any other material known in the art that will provide the desired results. 
       FIGS. 4 and 5  schematically illustrates the operating principles for the temperature compensation system shown in  FIG. 1 .  FIG. 4  illustrates orbiting scroll member  56  and non-orbiting scroll member  70  at a normal environmental or room temperature. The surface of end plate  60  extending between scroll wrap  58  is formed as a generally planar surface. Similarly, the surface of end plate  74  extending between scroll wrap  72  is also formed as a generally planar surface. In this manner, when orbiting scroll member  56  and non-orbiting scroll member  70  are assembled at room temperature, the flank surfaces of scroll wraps  58  and  72  engage each other, the tip of scroll wrap  58  engages end plate  74  and the tip of scroll wrap  72  engages end plate  60  to provide for the sealing of the compression pockets. 
       FIG. 5  illustrates the thermal expansion effects due to normal operating temperature on orbiting scroll member  56  and non-orbiting scroll member  70  with the compensation effect of annular ring  88 . It has been observed that end plate  60  remains generally planar and provides continued proper engagement with generally flat thrust bearing surface  54  of main bearing housing  24 . The incorporation of annular ring  88  does not affect the thermal growth resulting in the convex shape of wraps  58 . The effect of the incorporation of annular ring  88  is only on non-orbiting scroll member  70 . As the temperature of non-orbiting scroll member  70  increases, the temperature of annular ring  88  also increases. This causes thermal expansion of annular ring  88  in an amount which is greater than the thermal expansion of annular flange  90  due to the differences in the coefficients of thermal expansion of their materials. This difference in thermal expansion will produce a load on annular flange  90  which will cause end plate  74  to form a concave surface which will reduce or eliminate the convex shape for the tips of wrap  72 . With the proper selection of materials such as copper based materials or ferrous based materials with austenitic structure which have a coefficient of thermal expansion higher than that of scroll members made of grey iron to choose from typical wrought materials, and the proper dimensioning of the components, the concave shape of end plate  74  can be made to better match the convex shape of the tips of wraps  58  of orbiting scroll member  56  while simultaneously causing the tips of wraps  72  of non-orbiting scroll member  70  to become generally planar. In this manner, the proper sealing between the tips of wraps  58  and  72  and the surfaces of end plates  74  and  60  respectively will be maintained at normal operating temperature as well as during the transition between normal environmental temperatures and normal operating temperatures. 
     Referring now to  FIGS. 6A and 6B , a compensation system in accordance with another embodiment of the present disclosure is illustrated.  FIGS. 4 and 5  illustrate annular ring  88  attached to non-orbiting scroll member  70 .  FIG. 6  illustrates an annular ring  188  attached to an orbiting scroll member  156 . 
     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 . 
       FIG. 6A  schematically illustrates the operating principles for this embodiment of the temperature compensation system. At normal environmental or room temperature, the surface of end plate  160  extending between scroll wrap  158  is formed as a generally planar surface similar to that illustrated in  FIG. 4  for scroll wrap  58  and end plate  60 . Similarly, the surface of end plate  174  extending between scroll wrap  172  is also formed as a generally planar surface similar to that illustrated in  FIG. 4  for scroll wrap  72  and end plate  74 . In this manner, when orbiting scroll member  156  and non-orbiting scroll member  170  are assembled at room temperature, the flank surfaces of scroll wraps  158  and  172  engage each other, the tip of scroll wrap  158  engages end plate  174  and the tip of scroll wrap  172  engages end plate  160  to provide for the sealing of the compression pockets. 
       FIG. 6A  illustrates the thermal expansion effects due to normal operating temperature on orbiting scroll member  156  and non-orbiting scroll member  170  with the compensation effect of annular ring  188 . It has been observed that end plate  174  remains generally planar. The incorporation of annular ring  188  does not affect the thermal growth resulting in the convex shape of wraps  172 . The effect of the incorporation of annular ring  188  is only on orbiting scroll member  156 . As the temperature of orbiting scroll member  156  increases, the temperature of annular ring  188  also increases. This causes thermal expansion of annular ring  188  in an amount which is greater than the thermal expansion of annular flange  190  due to the differences in the coefficients of thermal expansion of their materials. This difference in thermal expansion will produce a load on annular flange  190  which will cause end plate  160  to form a concave surface which will eliminate the convex shape for the tips of wrap  158 . With the proper selection of materials and the proper dimensioning of the components, the concave shape of end plate  160  can be made to better match the convex shape of the tips of wraps  172  of non-orbiting scroll member  120  while simultaneously causing the tips of wraps  158  of orbiting scroll member  156  to become generally planar. In this manner, the proper sealing between the tips of wraps  158  and  172  and the surfaces of end plates  174  and  160  respectively will be maintained at normal operating temperature as well as during the transition between normal environmental temperatures and normal operating temperatures. 
     The temperature compensation system illustrated in  FIG. 6A  can be used in scroll compressor  10  which utilizes axial movable non-orbiting scroll member  70 . Because annular ring  188  is disposed in base plate  160  of orbiting scroll member  156  and the fact that the back surface of base plate  160  is a thrust bearing surface in scroll compressor  10 , this compensation system may be more appropriate for a compressor  110  illustrated in  FIG. 6B . 
     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 . 
       FIGS. 7 and 8  schematically illustrate the operating principles of a temperature compensation system in accordance with another embodiment of the disclosure. The temperature compensation system in  FIGS. 7 and 8  comprises an annular ring  288  attached to a non-orbiting scroll member  270 . 
     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. 
       FIGS. 7 and 8  schematically illustrate the operating principles for the temperature compensation system similar to that shown in  FIG. 1 .  FIG. 7  illustrates orbiting scroll member  256  and non-orbiting scroll member  270  at a normal environmental or room temperature. The surface of end plate  260  extending between scroll wrap  258  is formed as a generally planar surface. Similarly, the surface of end plate  274  extending between scroll wrap  272  is also formed as generally planar surface. In this manner, when orbiting scroll member  256  and non-orbiting scroll member  270  are assembled at room temperature, the flank surfaces of scroll wraps  258  and  272  engage each other, the tip of scroll wrap  258  engages end plate  274  and the tip of scroll wrap  272  engages end plate  260  to provide for the sealing of the compression pockets. 
       FIG. 8  illustrates the thermal expansion effects due to the normal operating temperature of orbiting scroll member  256  and non-orbiting scroll member  270  with the compensation effect of annular ring  288 . It has been observed that end plate  260  remains generally planar and provides continued proper engagement with generally flat thrust bearing surface  54  of main bearing housing  24 . The incorporation of annular ring  288  does not affect the thermal growth resulting in the convex shape of wraps  258 . The effect of the incorporation of annular ring  288  is only on non-orbiting scroll member  270 . As the temperature of non-orbiting scroll member  270  increases, the temperature of annular ring  288  also increases. This causes thermal expansion of annular ring  288  in an amount which is less than the thermal expansion of annular portion  290  due to the differences in the coefficients of thermal expansion of their materials. This difference in thermal expansion will produce a load on annular portion  290  which will cause end plate  274  to form a concave surface which will reduce or eliminate the convex shape for the tips of wrap  272 . With the proper selection of materials, such as high nickel alloys or filament wound carbon fiber based composite materials which have a coefficient of thermal expansion lower than that of scroll members made of grey iron to choose from typical engineered materials, and the proper dimensioning of the components, the concave shape of end plate  274  can be made to better match the convex shape of the tip of wrap  258  of orbiting scroll member  256  while simultaneously causing the tip of wrap  272  of non-orbiting scroll member  270  to become generally planar. In this manner, the proper sealing between the tips of wraps  258  and  272  and the surfaces of end plates  274  and  260 , respectively, will be maintained at normal operating temperature as well as during the transition between normal environmental temperatures and normal operating temperatures. 
       FIGS. 9-11  schematically illustrate the operating principles of a temperature compensation system in accordance with another embodiment of the present disclosure. The temperature compensation system in  FIGS. 9-11  comprises a plurality of thermal actuators  388  attached to a non-orbiting scroll member  370 . 
     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  FIG. 11 , the present disclosure includes four bores  394 , four thermal actuators  388 , four bores  396  and four fasteners  398 . It is to be understood that the present disclosure is not limited to four thermal actuators but the present disclosure can have fewer or more thermal actuators  388  as determined by the specific design and development requirements. 
     Referring to  FIGS. 12 and 13 , thermal actuator  388  is illustrated in greater detail. Thermal actuator  388  comprises a cup  402 , a thermal expansion material  404 , a diaphragm  406 , a plug  408 , a guide  410  and a piston  412 . Thermal expansion material  404  is disposed within cup  402  and diaphragm  406  seals and retains thermal expansion material  404  within cup  402 . Plug  408  and piston  412  are assembled within guide  410  and guide  410  is secured to cup  402  to complete the assembly of thermal actuator  388 . Guide  410  is secured to cup  402  by welding, by the use of a retainer (not shown), by a threaded connection or by any other means known in the art. 
       FIG. 12  illustrates thermal actuator  388  in its cold or non-actuated condition. Thermal expansion material  404  is disposed within cup  402  in a solid state and piston  412  is in its retracted position.  FIG. 13  illustrates thermal actuator  388  in its heated or actuated condition. Thermal expansion material  404  reacts to heat by changing into a liquid material and expanding to push diaphragm  406  upward as illustrated in  FIG. 13 . Diaphragm  406  pushes plug  408  upward which in turn pushes piston  412  into its extended position as illustrated in  FIG. 13 . When thermal expansion material  404  cools, it returns to its solid condition as illustrated in  FIG. 12 . 
       FIGS. 9 and 10  schematically illustrate the operating principles for the temperature compensation system for this embodiment.  FIG. 9  illustrates orbiting scroll member  356  and non-orbiting scroll member  370  at a normal environmental or room temperature. The surface of end plate  360  extending between scroll wrap  358  is formed as a generally planar surface. Similarly, the surface of end plate  274  extending between scroll wrap  272  is also formed as a generally planar surface. In this manner when orbiting scroll member  356  and non-orbiting scroll member  370  are assembled at room temperature, the flank surfaces of scroll wraps  358  and  372  engage each other, the tip of scroll wrap  358  engages end plate  374  and the tip of scroll wrap  372  engages end plate  360  to provide for the sealing of the compression pockets. 
       FIG. 10  illustrates the thermal expansion effects due to the normal operating temperature of orbiting scroll member  356  and non-orbiting scroll member  370  with the compensation effect of thermal actuators  388 . It has been observed that end plate  360  remains generally planar and provides continued proper engagement with flat thrust bearing surface  54  of main bearing housing  24 . The incorporation of thermal actuators  388  does not affect the thermal growth resulting in the convex shape of wraps  358 . The effect of the incorporation of thermal actuators  388  is only on non-orbiting scroll member  370 . As the temperature of non-orbiting scroll member  370  increases, the temperature of thermal actuators  388  also increases. This causes the melting and expansion of thermal expansion material  440  in thermal actuators. This expansion of thermal expansion material  440  pushes pistons  412  outward, as detailed above, to apply a force to the upper end of annular flange  390  and the force applied to annular flange  390  by thermal actuators  388  will cause end plate  374  to form a concave surface which will reduce or eliminate the convex shape for the tips of wrap  372 . With the proper selection of the number and type of thermal actuators  388 , the concave shape of end plate  374  can be made to much better match the convex shape of the tip of wrap  358  of orbiting scroll member  356  while simultaneously causing the tip of wrap  372  of non-orbiting scroll member  370  to become generally planar to match end plate  360  of orbiting scroll member  356 . In this manner, the proper sealing between the tips of wraps  358  and  372  and the surfaces of end plates  374  and  360 , respectively, will be maintained at normal operating temperatures as well as during the transition between normal environmental temperatures and normal operating temperatures. Fasteners  398  are adjustable to provide for the room temperature position of fasteners  398  with respect to thermal actuators  388  to insure equal loads around the circumference of annular flange  390 . 
     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.