Abstract:
A method of fabricating a refrigerator cabinet or door includes forming a wrapper and an inner liner. The method further includes forming a vacuum insulated core comprising a permeable core material that is disposed inside an impermeable envelope. A sheet of prefabricated compressible foam material is positioned between the vacuum insulated core between the inner door liner and/or the door wrapper. The prefabricated compressible foam material may be cut from a sheet of foam having substantially uniform thickness prior to fabrication of the refrigerator door. The foam compresses to accommodate differences in spacing between the vacuum insulated core and the door wrapper and/or the door liner.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    Refrigerators typically include a refrigerated cabinet having one or more openings that can be selectively closed off by doors that are movably mounted to the cabinet. The doors are typically insulated, and seal off the openings when in a closed position. A known type of construction utilized in fabricating refrigerator cabinets and doors includes an outer wrapper and inner liner having an interior cavity or space that is filled with insulating foam. The foam may comprise a polyurethane foam that is injected into the space after the wrapper and liner are interconnected. The foam expands to fill the interior space prior to curing. 
         [0002]    Another type of insulated cabinet construction includes vacuum insulated internal panels. Vacuum insulated panels provide improved insulating properties whereby the cabinet walls can be thinner, yet retain the same insulation properties. However, known vacuum insulated refrigerator cabinet and door constructions may suffer from various drawbacks. 
       SUMMARY OF THE INVENTION 
       [0003]    A method of fabricating a refrigerator cabinet or door includes forming a wrapper having a peripheral edge portion. An inner liner having a peripheral edge portion is also formed. The wrapper and liner may comprise an outer door panel (“door wrapper”) and an inner door liner. The method further includes forming a vacuum insulated core comprising a permeable core material that is disposed inside an impermeable envelope. The envelope is evacuated to form a vacuum inside the envelope. A sheet of prefabricated compressible foam material is positioned between the vacuum insulated core between at least one of the inner door liner and the door wrapper. The method includes securing at least a portion of the peripheral edge portion of the door wrapper to the peripheral edge portion of the inner door liner with the vacuum insulated core positioned between the door wrapper and the inner door liner. The prefabricated compressible foam material may be cut from a sheet of foam having substantially uniform thickness prior to fabrication of the refrigerator door. The foam compresses to accommodate differences in spacing between the vacuum insulated core and the door wrapper and/or the door liner. Because the space between the vacuum insulated core and the wrapper and the space between the insulated core and the liner is preferably quite small to provide a thinner door construction, it is difficult to inject conventional foams (e.g. polyurethane) into this limited space. The use of a prefabricated compressible foam sheet eliminates gaps that would otherwise exist, and also provides support for the wrapper and/or liner to reduce flexing/bending that could otherwise occur due to a gap between, for example, the door wrapper and the vacuum insulated core. 
         [0004]    These and other features, advantages, and objects of the present disclosure will be further understood and appreciated by those skilled in the art by reference to the following specification, claims, and appended drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0005]      FIG. 1  is an isometric view of a refrigerator; 
           [0006]      FIG. 2  is an exploded isometric view showing a refrigerator door having a vacuum insulated core and one or more prefabricated foam sheets; 
           [0007]      FIG. 3  is an isometric view showing a vacuum insulated core prior to folding into a three dimensional shape as shown in  FIG. 2 ; 
           [0008]      FIG. 4  is a fragmentary cross sectional view taken along the line IV-IV;  FIG. 3 ; 
           [0009]      FIG. 5  is a partially schematic cross sectional view of the refrigerator door taken along the line V-V;  FIG. 1 ; and 
           [0010]      FIG. 6  is a partially schematic cross sectional view of a refrigerator door having a vacuum insulated core and preformed foam sheet. 
       
    
    
     DETAILED DESCRIPTION 
       [0011]    For purposes of description herein, the terms “upper,” “lower,” “right,” “left,” “rear,” “front,” “vertical,” “horizontal,” and derivatives thereof shall relate to the invention as oriented in  FIG. 1 . However, it is to be understood that the disclosed subject matter may assume various alternative orientations and step sequences, except where expressly specified to the contrary. It is also to be understood that the specific devices and processes illustrated in the attached drawings, and described in the following specification, are simply exemplary embodiments of the inventive concepts defined in the appended claims. Hence, specific dimensions and other physical characteristics relating to the embodiments disclosed herein are not to be considered as limiting, unless the claims expressly state otherwise. 
         [0012]    With reference to  FIG. 1 , a refrigerator  1  includes an insulated cabinet  2  having internal spaces  4  and  6  with openings  8  and  10 , respectively on a front side  12  of cabinet  2 . In the illustrated example, the interior space  4  comprises a fresh food refrigerated space that can be accessed by opening one or both doors  14  and  16 , and the interior space  6  comprises a freezer compartment that can be accessed by opening drawer  18 . Drawer  18  includes an insulated front panel  20 . It will be understood that the term “door” as used herein generally refers to a movable door (e.g. doors  14  and  16 ) or an insulated panel  20  on a movable drawer  18 . It will be understood that the construction/method of fabricating door  16  as described herein is equally applicable to the door  14  and front panel  20  of drawer  18 . 
         [0013]    With further reference to  FIG. 2 , door  16  includes an outer skin or wrapper  22 , a liner  24  and a vacuum insulated core  26 . As discussed in more detail below, a prefabricated foam sheet  28  may be positioned between liner  24  and vacuum insulated core  26 . A prefabricated foam sheet  30  may also be positioned between the wrapper  22  and vacuum insulated core  26 . Door  16  may include only foam sheet  28 , only foam sheet  30 , or both foam sheets  28  and  30 . 
         [0014]    Outer wrapper  22  may comprise sheet metal or polymer that is formed to provide a desired  3 D shape utilizing known processes. The wrapper  22  may include a central area  32  that is generally planar, and side walls  34 A- 34 D that extend transversely from the central area  32 . The side walls  34 A- 34 D may include inwardly-extending flanges  36 A- 36 D that are configured to interconnect with liner  24 . The wrapper  22  may optionally include one or more openings  38  that may be utilized to mount a user display  40  and/or an ice and/or water dispenser  42  ( FIG. 1 ). 
         [0015]    Liner  24  is preferably made by thermoforming a sheet of polymer material utilizing known thermoforming. Liner  24  may also be made utilizing an injection molding process. The liner  24  includes a central portion  44  and sidewall portions  46 A- 46 D. The side walls  46 A- 46 D may include connecting structures or flanges  48 A- 48 D that are configured to engage the flanges  36 A- 36 D and/or side walls  34 A- 34 D of wrapper  22 . The configurations of the peripheral edge portions  50  and  52  of wrapper  22  and liner  24  may have various known configurations, and are generally configured to be interconnected to one another in a known manner. 
         [0016]    The vacuum insulated core  26  may include a central area  54  and side walls  56 A- 56 D. With further reference to  FIGS. 3 and 4 , the vacuum insulated core  26  may be fabricated from a flat sheet of core material  26 A having flaps  58 A- 58 D that are folded along fold lines  60 A- 60 D, respectively to form side walls  56 A- 56 D, respectively. With reference to  FIG. 4 , the panel  26 A comprises a permeable core material  62  that is disposed inside an impermeable envelope  64  that is sealed along a seam  66 . The envelope  64  is evacuated to form a vacuum. In a preferred embodiment, the core material comprises fiberglass, silica powder, or other suitable material, and the envelope  64  comprises one or more layers of foil and/or polymer. V-shaped notches  68 A- 68 D may be formed utilizing a V-shaped forming tool  70  to thereby provide fold lines  60 A- 60 D. As discussed in more detail below, additional layers of core material  90  may be utilized to provide increased thickness in specific regions if required for a particular application. 
         [0017]    Referring again to  FIG. 2 , the vacuum insulated core  26  is configured to fit closely within wrapper  22 , with side walls  56 A- 56 D of vacuum insulated core  26  being disposed directly adjacent, but inside side walls  34 A- 34 D, respectively, of wrapper  22 . Liner  24  is configured to fit within vacuum insulated core  26  in a nesting manner, with central portion  44  of liner  24  disposed immediately adjacent central area  54  of vacuum insulated core  26 , and with side walls  46 A- 46 D of liner  24  being disposed adjacent and inside of, side walls  56 A- 56 D of vacuum insulated core  26 . 
         [0018]    Due to manufacturing tolerances, and the like, gaps may be present in at least some regions between liner  24  and vacuum insulated core  26 . Similarly, gaps may also exist between wrapper  22  and vacuum insulated core  26  in some regions. To account for such gaps, prefabricated foam sheet  28  and/or prefabricated sheet  30  may be positioned between vacuum insulated core  26  and liner  24  and/or between vacuum insulated core  26  and wrapper  22 . The prefabricated foam sheets  28  and  30  preferably comprise a compressible foam material having a thickness of about 0.060-1.0 inches, and more preferably about 0.125-0.375 inches. The foam sheets  28  and  30  may comprise a known foam material that is prefabricated in sheets having uniform thickness, and the sheets  28  and  30  may be cut to size as required for a particular application. Examples of suitable foam materials include polyethylene, EVA (Ethylene-vinyl acetate) and polyurethane. The prefabricated foam sheets  28  and  30  preferably have sufficient stiffness to significantly reduce or prevent flexing of liner  24  and/or wrapper  22 , respectively if a user applies an out of plane force to the liner  24  or wrapper  22 . However, prefabricated foam sheets  28  and  30  also preferably have sufficient resilience/compressibility to permit some compression during the assembly process to thereby account for variations in the gap between liner  24  and core  26 , and variations in the gap between wrapper  22  and core  26 . Typically, the gaps between the components are selected to be the same size or smaller than the thicknesses of sheets  28  and  30  even if the gaps are at a maximum possible size due to tolerances in the components such that sheets  28  and  30  are compressed at least somewhat and completely fill the gaps. 
         [0019]    During assembly, the wrapper  22  may be positioned in a lower tool or fixture  72 . If a prefabricated foam sheet  30  is to be installed between vacuum insulated core  26  and wrapper  22 , the prefabricated foam sheet  30  is cut to size. The prefabricated foam sheet may optionally be adhesively attached to the wrapper  22  and/or the vacuum insulated core  26 . The adhesive may comprise hot melt adhesive, two-part adhesive, or other suitable adhesive. The prefabricated foam sheet  30  may be sized and configured such that an edge portion  78  of foam sheet  30  is folded along a rectangular fold line  76  during assembly whereby the edge portion  76  is disposed between side walls  34 A- 34 D of wrapper  22  and side walls  56 A- 56 D of vacuum insulated core  26 . It will be understood that the prefabricated foam sheet  30  may be cut to remove corner portions of sheet  30  to form flaps to prevent bunching/overlap at the corners in a manner that is similar to the flaps  58 A- 58 D of vacuum insulated core material  26 A as shown in  FIG. 3 . 
         [0020]    If a prefabricated foam sheet  28  is to be utilized in the assembly process, the foam sheet  28  is cut to size, and positioned between liner  24  and vacuum insulated core  26 . The foam sheet  28  may be adhesively secured to liner  24  and/or to vacuum insulated core  26 . The adhesive may comprise hot melt adhesive, two-part adhesive, or other suitable adhesive. The foam sheet  28  may also be cut and folded along fold line  80 , whereby the edge portion  82  of prefabricated foam sheet  28  may be positioned between side walls  56 A- 56 D of vacuum insulated core  26 , and side walls  46 A- 46 D of liner  24 . 
         [0021]    An upper tool or fixture  74  may then be utilized to press the wrapper  22  and liner  24  together. The lower tool  72  and upper tool  74  may be configured to ensure that the peripheral edge portions  50  and  52  of wrapper  22  and liner  24  are engaged with one another. The peripheral edge portions  50  and  52  may be sealed and/or interconnected utilizing various suitable known techniques. The assembled door may then be removed from the fixtures  72  and  74 . 
         [0022]    With reference to  FIG. 5 , a door  16 A includes a wrapper  22 A, liner  24 A, and a vacuum insulated core  26 A. The door  16 A includes a prefabricated foam sheet  28 A, and may also optionally include a prefabricated foam sheet  30 A. The wrapper  22 A is preferably formed from sheet metal (e.g. stainless steel) utilizing known metal forming processes, and the inner liner  24 A is formed from a polymer material. The liner  24 A may be fabricated by thermoforming a sheet of polymer material. The peripheral edge portion  50 A of wrapper  22 A comprises an inwardly-extending flange. The peripheral edge portion of liner  24 A comprises an outwardly-extending flange  52 A that overlaps the flange  50 A of wrapper  22 A. During assembly, the flanges forming the peripheral edges  50 A and  52  are interconnected and sealed utilizing known processes. 
         [0023]    With further reference to  FIG. 6 , a refrigerator door  16 B includes a metal wrapper  22 B, and a polymer liner  24 B. Liner  24 B may be formed from a sheet of polymer material utilizing a thermoforming process. A prefabricated foam sheet  28 B is positioned between the liner  24 B and the vacuum insulated core  26 B. A prefabricated foam sheet  26 B may optionally be positioned between wrapper  22 B and vacuum insulated core  26 B. The vacuum insulated core  26 B includes side wall portions  84  and  86 . The side wall portions  84  have an increased thickness “T,” and fit within side walls  88  of wrapper  22 B. The increased thickness of side wall  84  may be formed by stacking an additional strip  90  ( FIG. 3 ) of vacuum insulated core material to the side walls of the vacuum insulated core  26 B. The end portion  86  of the side wall may comprise a single layer of vacuum insulated core material. For example, the flaps  58 A- 58 D ( FIG. 3 ) may have a width “W 1 ,” and the strips  90  may have a width “W 2 ” that is significantly less than the width “W 1 .” 
         [0024]    Referring again to  FIG. 6 , the liner  24  may include an end portion  92  that is U-shaped or J-shaped, whereby the end portion  92  extends around the end portion  86  of the side walls of vacuum insulated core  26 . During assembly, the peripheral edge portion  50 B of wrapper  22 B is sealed/attached to peripheral edge portion  52 B of inner liner  24 B. The peripheral edge portions  50 B and  52 B may comprise overlapping flanges that are pressed together by upper and lower tool fixtures  74 ,  72 , respectively ( FIG. 2 ) in a known manner. 
         [0025]    It is to be understood that variations and modifications can be made on the aforementioned structure without departing from the concepts of the present disclosure, and further it is to be understood that such concepts are intended to be covered by the following claims unless these claims by their language expressly state otherwise.