Abstract:
The present invention is for the retention of a heat shield for a scroll compressor. In one embodiment, the heat shield is deformed into a position such that it rests in a groove located in the non-orbiting scroll. In another embodiment the housing end cap deforms the heat shield. The deformed position of the heat shield prevents flexing and vibrating found in heat shields of prior art. In addition the heat shield must have holes in it to allow for the discharge valve to pass through. The present invention is to put slots in the heat shield, thus preventing the need for exact alignment of the heat shield in position.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to the retention of a heat shield in a sealed scroll compressor by creating a bias force on the heat shield. 
     Modern refrigerant compressors are typically contained within a sealed shell. The compressors are frequently divided into two compartments, a discharge chamber and a suction chamber. 
     A scroll compressor is one common type of sealed compressor. In a scroll compressor an orbiting scroll and a non-orbiting scroll each have a base, with generally spiral wraps extending from the bases. The orbiting scroll and the non-orbiting scroll are placed together such that the wraps create compression chambers. A shaft connected to a motor drives the orbiting scroll. As the orbiting scroll orbits the volume of the compression chambers is decreased. 
     Refrigerant is compressed in the chambers and discharged into the discharge chamber through a discharge port located in the non-orbiting scroll. The refrigerant may reach high temperature within the discharge chamber. 
     Historically, a thick separator plate isolated the discharge chamber from the base of the non-orbiting scroll. More recently, scroll compressor designs have attempted to eliminate the separator plate. 
     However, without a separator plate the refrigerant in the discharge chamber comes into contact with the base of the non-orbiting scroll. The refrigerant heats the base and consequently the compression chambers, which costs efficiency. A relatively thin heat shield has been placed extending about the base of the non-orbiting scroll. Due to the operation of the scroll compressor, there are pressure and temperature differences on each side of the heat shield. The pressure and temperature differences may create vibration and flexing of the thin heat shield. 
     One other concern is the heat shield may need to have openings, such as to allow flow from a pressure relief valve. In the past this has required that the heat shield be precisely aligned within the compressor such that the opening in the heat shield is aligned over the pressure relief valve to facilitate flow. 
     SUMMARY OF THE INVENTION 
     In embodiments of this invention a heat shield is associated within the base of a non-orbiting scroll. As known, the heat shield provides a barrier to insulate the non-orbiting scroll from the hot refrigerant in the discharge chamber. To address the above mentioned concern the heat shield is held at a deformed position such that a bias force resists flexing or vibration. 
     In a preferred embodiment a groove is placed in a boss surrounding a discharge port in the non-orbiting scroll. The heat shield is deformed into the groove. In a free state, the heat shield has a disc like appearance. An opening in the center of the heat shield is received over the boss. The heat shield is placed on the boss and pressed down. Essentially there is an interference fit between the heat shield and the boss. This fit deforms the heat shield away from its free curved shape creating a spring pre-load. The bias force from the deformation keeps the heat shield in position resisting flexing or vibration. 
     Preferably the inner edge of the heat shield is held in position in a groove located in the boss. The groove may have several different configurations. In the preferred configuration the bottom side of the groove is flat with a radius at the corner. The edge extends upward and is angled slightly toward the outside of the scroll. The angle prevents the heat shield from moving out of the groove. 
     In another embodiment the groove can be square cut. This groove has a distinct bottom, side, and top portion. This groove provides good support from the top when holding the heat shield in place. A third embodiment includes an angled groove, which has only two sides. The bottom side of the groove is flat, and a side extends upwardly and outwardly. 
     An alternative to having a curved heat shield is an embodiment where the outside edge of the heat shield is turned upward. The outside edge contacts the upper end cap when installed, deforming the heat shield when the end cap is secured to the compressor housing. This contact creates a downward bias force on the heat shield. Again, the bias force resists flexing and vibrating of the heat shield following installation. 
     In another embodiment, the heat shield is captured between the non-orbiting scroll and the outer housing. A portion of the heat shield is deformed when held at this captured position such that the bias force as mentioned above does occur. 
     One other aspect of the invention provides a heat shield, which more easily accommodates components such as a pressure relief valve. The valve requires a hole to be placed in the heat shield allowing the flow to pass through. One known heat shield is used with a non-orbiting scroll having ribs on a rear face, with pockets between the ribs. There is usually a hole in the heat shield through which the flow from the pressure relief valve may pass. However the single hole has needed to be aligned over the pressure relief valve. This aspect of the invention allows for the adjustments to be made in the alignment of the heat shield and the relief valve. In one aspect the hole aligned over the pressure relief valve can be a slot to allow for the valve and the heat shield to be slightly misaligned and still allow flow through the hole. There may also be a plurality of holes within an area of the heat shield, or a series of spaced holes in the heat shield. The holes may be off center within the heat shield again to allow for misalignment. 
    
    
     These and other features of the present invention can be best understood from the following specification and drawings. 
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The following drawings describe the invention in an illustrative manner, by way of example only: 
     FIG. 1 shows a prior art scroll compressor 
     FIG. 2 shows a side view of a heat shield according to the present invention prior to installation 
     FIG. 3A is a top view of a heat shield according to the present invention 
     FIG. 3B is a side view of heat shield according to the present invention 
     FIG. 4 is a side view of heat shield following installation on the scroll compressor 
     FIG. 5 shows a cross-section of the non-orbiting scroll boss showing location of the heat shield groove. 
     FIG. 6 is a side view of the preferred embodiment of the heat shield groove 
     FIG. 7 shows a side view of an alternative embodiment of the heat shield groove 
     FIG. 8 is a side view of a third embodiment of the heat shield groove 
     FIG. 9 is a side view of an alternate embodiment of the invention, after installation on the scroll compressor 
     FIG. 10A shows a cross-sectional view of another embodiment. 
     FIG. 10B shows an undeformed portion of the FIG. 10A embodiment. 
     FIG. 11 is a top view of the non-orbiting scroll. 
     FIG. 12 is a top view of another embodiment heat shield. 
     FIG. 13 shows a top view of another embodiment heat shield. 
     FIG. 14 shows a top view of another embodiment heat shield. 
     FIG. 15 shows a top view of yet another embodiment heat shield. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     A known scroll compressor  21  includes a heat shield  22 , as shown in FIG.  1 . Scroll compressor  21  includes an orbiting scroll  23  and a non-orbiting scroll  24 . Non-orbiting scroll  24  has a base  25 , with generally spiral wraps  26  extending from the base. Likewise orbiting scroll  23  has a base  27  with generally spiral wraps  28 . The orbiting scroll  23  and the non-orbiting scroll  24  are placed together and the wraps  26  and  28  create compression chambers  29 . A shaft  30  connected to a motor drives orbiting scroll  23 , and as this occurs the volume of the compression chambers  29  is decreased. 
     The non-orbiting scroll  24  is sealed to the outer housing end cap  31  of the compressor  21  in the area of  32 , thus creating two separate chambers, a discharge chamber  33  and a suction chamber  34 . Suction pressure refrigerant passes through suction tube  35  and enters chamber  34 . Thus, the non-orbiting scroll  24  provides the function of a separator plate. Refrigerant is compressed in chambers  29  and discharged into discharge chamber  33  through a discharge port  36  located in the non-orbiting scroll  24 . 
     The refrigerant in discharge chamber  33  is at a relatively high temperature. A heat shield  22  is used to insulate the base of the non-orbiting scroll  24  from the heat of the discharge chamber  33 . This in turn insulates the refrigerant in the compression chambers  29  from the heat. The heat shield  22  is a relatively thin component extending about the base  25  of the non-orbiting scroll  24  with chambers  37  and  38  between the base  25  and the heat shield  22 . 
     A pressure difference often exists across the heat shield  22  due to the variance in pressure and temperature on each side of the heat shield  22 . A pressure relief valve  39  may extend from non-orbiting scroll  24 . Also the discharge of refrigerant into chamber  33  is somewhat cyclic and causes cyclic pressure variation in chamber  33 . As a result of the pressure differences the heat shield  22  may vibrate or flex in its position, thus creating noise. The compressor described to this point is generally as disclosed in U.S. patent application entitled “Scroll Compressor with Heat Shield” (U.S. Pat. No. 6,287,089) 
     To address the above noise the heat shield of this invention is deformed so as to be biased into either the base  25 , or an end cap  31 . As shown in FIG. 2, groove  40  is formed in a boss  41  in non-orbiting scroll  24  to receive an inner end  42  of heat shield  43 . As explained below, the heat shield  43  is held at this position with a bias force. 
     In the preferred embodiment of the invention the heat shield  43  has a free shape with a disc like appearance, as shown FIG.  3 A. As can be seen there is a cut out area  44  in the center of the heat shield  43  along inner end  42 . The curved shape of the disk is shown in FIG. 3B as having an upwardly extending curved shape  45 . 
     Opening  44  allows heat shield  43  to fit over a boss  41  extending from the top of the fixed scroll  24 , as shown in FIG.  2 . Once the heat shield  43  had been placed on boss  41  it is pressed down. The curved shape  45  of the heat shield  43 , as shown in FIG. 3B, is forced downwardly with groove  40  providing an interference fit. When the shield is forced to its operative position, as shown in FIG. 4, a spring bias is created trying to move the heat shield back to the FIG. 2 position. 
     The preferred location of the groove  40  in the boss  41  is shown in FIG.  5 . FIG. 6 shows the preferred shape of the groove  40 . The groove  40  may have several different configurations. The bottom side  50  of the groove  40  is flat with a radius  51  at the corner. The edge extending upward  52  is angled slightly toward the outside of the scroll. The angle prevents the heat shield from moving out of the groove  40 . 
     In another embodiment the groove  40  can be square cut, shown in FIG.  7 . This groove has a distinct bottom  60 , side  61 , and top portion  62 . This more distinct groove provides good support from the top when holding the heat shield  43  in place. 
     As shown in FIG. 8, a third embodiment shows an angled groove, which has only two sides. The bottom side  70  of the groove being flat, and a side  71  extending upward and outward from that. 
     FIG. 9 shows another embodiment where the outside edge  80  of a heat shield  81  is turned upward. An upper end cap  31  contacts the outward edge  80  at  82 . This contact creates a downward bias force on the heat shield  81 . Once the upper end cap  31  is welded to center shell  83  the heat shield  81  is deformed by this contact. Again this creates a bias force resisting flexing and vibrating of the heat shield. 
     As shown in FIG. 10A, a non-orbiting scroll  24  and an outer housing end cap  31  capture a shoulder portion  88  of a heat shield  90 . Such a heat shield is better described in U.S. Pat. No. 6,428,293, the capturing aspect of which is incorporated herein by reference. 
     The heat shield  90  as disclosed in this invention preferably has a contact point  92  contacting a portion of the non-orbiting scroll  24 . This contact point leads to some deformation in the heat shield  90 , such that the benefits mentioned above are achieved. 
     As shown in FIG. 10B, the heat shield  90  has an undeformed shape  94  which is deformed to the position  96  such as shown in phantom in  10 B when the heat shield is captured between the non-orbiting scroll  24  and the end cap  31 . When held in this position, a bias force tending to bias the heat shield back against the non-orbiting scroll is created, providing the benefits as mentioned above. 
     The portion  94  may be one, or a plurality of circumferentially spaced portions which are deformed to the phantom position shown in  96 , or could be a circumferentially continuous portion. 
     There is also a requirement for the heat shield  43  to allow passage of flow from pressure relief valve  39 . As can be seen from non-orbiting scroll shown in FIG. 11 there may be ribs  92  and pockets  91  around pressure relief valve  39 . Likewise the heat shield  43  has ribs  92  running across it, between the ribs  92  there are pockets  93 . In order to fit, the heat shield  43  requires a hole  94  in one of its pockets  93  allowing the flow from the pressure relief valve  39  to pass through. In another aspect of this invention, the holes  94  have been modified in order to accommodate for misalignment of the heat shield  43  and the pressure relief valve  39 . FIG. 12 shows an embodiment of this with one hole  94  within each pocket  93  of the heat shield. With this feature, the heat shield does not require being particularly aligned with the non-orbiting scroll. 
     In another embodiment there may be a plurality of holes in a pocket  93 , as shown in FIGS. 13 and 14. These holes  94  may be aligned so they are off center. Another embodiment shows that there may be holes in more than one of the ribs  92 . 
     In FIG. 13 the holes  94  in the heat shield  143  are set off center within the pocket, allowing for a valve  39  that has been set off center to still be aligned to facilitate flow of gasses to pass through the holes  94 . Furthermore the valve  39  may not be located the same distance from the center in every heat shield. FIG. 14 shows an embodiment  243  in which the holes  194  vary in distance from the center of the heat shield. 
     FIG. 15 shows another variation  343  for allowing misalignment of a flow valve  39  and the required hole in the heat shield  43  is to replace the holes with slots  95 . 
     The foregoing description is only exemplary of the principles of the invention. Many modifications and variations of the present invention are possible in light of the above teachings. The preferred embodiments of this invention have been disclosed, however, so that one of ordinary skill in the art would recognize that certain modifications would come within the scope of this invention. It is, therefore, to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described. For that reason the following claims should be studied to determine the true scope and content of this invention