Abstract:
A method of forming a vacuum insulated refrigerator cabinet, the method comprising providing first and second sheets of material. The first sheet of material is thermoformed over a first forming tool forming a first intermediate structure. The first intermediate structure is then thermoformed over a second forming mold to create a second intermediate structure. The second sheet of material is then sealing connected with the second intermediate structure forming an annular space. A vacuum is created in the annular space creating a vacuum insulated cabinet.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    The present application is related to U.S. patent application Ser. No. ______, filed ______, entitled A METHOD TO CREATE VACUUM INSULATED CABINETS FOR REFRIGERATORS (Atty. Docket No. SUB-02833-US-NP); and U.S. patent application Ser. No. ______, filed ______, entitled FOLDED VACUUM INSULATED STRUCTURE (Atty. Docket No. SUB-03635-US-NP); and U.S. patent application Ser. No. ______, filed ______, entitled A VACUUM PANEL CABINET STRUCTURE FOR A REFRIGERATOR (Atty. Docket No. SUB-03629-US-NP); and U.S. patent application Ser. No. ______, filed ______, entitled DUAL COOLING SYSTEMS TO MINIMIZE OFF-CYCLE MIGRATION LOSS IN REFRIGERATORS WITH A VACUUM INSULATED STRUCTURE (Atty. Docket No. SUB-03714-US-NP); and U.S. patent application Ser. No. ______, filed ______, entitled VACUUM INSULATED DOOR STRUCTURE AND METHOD FOR THE CREATION THEREOF (Atty. Docket No. SUB-03598-US-NP); and U.S. patent application Ser. No. ______, filed entitled VACUUM INSULATED STRUCTURE TUBULAR CABINET CONSTRUCTION (Atty. Docket No. SUB-03628-US-NP); and U.S. patent application Ser. No. ______, filed entitled FOLDED VACUUM INSULATED STRUCTURE (Atty. Docket No. SUB-03627-US-NP); and U.S. patent application Ser. No. ______, filed ______, entitled METHOD TO CREATE VACUUM INSULATED CABINETS FOR REFRIGERATORS (Atty. Docket No. SUB-04016-US-NP), all of which are incorporated herein by reference in their entirety. 
         [0002]    The present application is a continuation of U.S. patent application Ser. No. 13/833,685, filed Mar. 15, 2013, entitled METHOD TO CREATE VACUUM INSULATED CABINETS FOR REFRIGERATORS. The present application also claims priority to and the benefit of U.S. Provisional Application Ser. No. 61/622,821, filed Apr. 11, 2012, entitled VACUUM INSULATED CABINETS FOR HOUSEHOLD REFRIGERATORS. The entire disclosures of each application are hereby incorporated by reference. 
     
    
     FIELD OF THE INVENTION 
       [0003]    The present invention generally relates to a vacuum insulated cabinet and the method for constructing therefore. 
       BACKGROUND OF THE INVENTION 
       [0004]    Known plastic liner forming processes, as shown in traditional refrigerator cabinet construction  FIGS. 1A-1C , the plastic sheet does not have an impermeable layer to provide a sufficient barrier for a vacuum insulated cabinet. In current refrigerator cabinet versions an manufacturing an insulated refrigerator cabinet, as shown in  FIGS. 1A-1C , a material sheet  12  having a single layer plastic is thermoformed over a first forming tool  11  to create a first intermediate structure  15 . A steel sheet wrapper  13  is then fitted over the first intermediate structure  15  to create an annular space  16 . The annular space  16  is filled with insulation material  14  by any conventional means. The current insulation used in the refrigerator cabinet is polyurethane foam blown into the cavity between the plastic liner and the metal wrapper. 
       SUMMARY OF THE INVENTION 
       [0005]    One aspect of the present invention includes a method of forming a vacuum insulated refrigerator cabinet providing first and second sheets of material comprising at least a first layer of thermal plastic material that is at least partially permeable to nitrogen and oxygen and the second layer of material that is substantially impermeable to oxygen, nitrogen and water vapor. At least a portion of the first sheet of material is heated to a temperature at which the first sheet of material can be plastically deformed. A first forming tool is utilized to deform the first sheet of material and form a first intermediate structure having a base sidewall defining a generally quadrilateral perimeter and four first sidewalls extending transversely from the quadrilateral perimeter to define a cavity having an opening that opens in a first direction and defines a peripheral edge extending around the opening. A second forming tool is provided having sidewall portions defining four generally rectangular outwardly facing surfaces and four generally rectangular inwardly facing surfaces, and an end surface extending transversely between the inwardly and outwardly facing surfaces. The first intermediate structure is disengaged from the first forming tool followed by positioning the second forming tool into the cavity of the first intermediate structure. The base sidewalls are plastically deformed to form a second intermediate structure having a base sidewall and four inner sidewalls extending transversely from the base sidewall and defining a second cavity that opens in a second direction that is substantially opposite the first direction. The inner sidewalls are spaced apart inwardly from the first sidewalls to define an annular space that opens in the first direction. The second sheet of material is sealingly connected to the second intermediate structure around the peripheral edge to substantially close off the opening. A vacuum is formed in the annular space with an appropriate porous, thermally insulating material such as fumed silica compacted and placed in the annular space to withstand atmospheric pressure and to provide superior thermal insulation properties. 
         [0006]    Another aspect of the present invention includes a method of forming a vacuum insulated refrigerator cabinet providing first and second sheets of material comprising at least a first layer of thermoplastic material and a second layer of material. At least a portion of the first sheet of material is heated to a temperature at which the first sheet of material can be plastically deformed. A first forming tool is utilized to deform the first sheet of material and form a first intermediate structure having the base sidewall defining a generally quadrilateral perimeter and at least one first side wall extending transversely from the quadrilateral perimeter to define a cavity having an opening that opens in a first direction and defines a peripheral edge extending around the opening. A second forming tool is provided having sidewall portions defining a plurality of generally rectangular outwardly facing surfaces and a plurality of generally rectangular inwardly facing surfaces, and an end surface extending transversely between the inwardly and outwardly facing surfaces. The first intermediate part is disengaged from the first forming tool followed by positioning the second forming tool in the cavity of the first intermediate structure. The base sidewall is plastically deformed to form a second intermediate structure having a base sidewall and a plurality of inner sidewalls extending transversely from the base sidewall and defining a second cavity that opens in a second direction that is substantially opposite the first direction. The inner sidewalls are spaced apart inwardly from the first sidewalls to define an annular space that opens in the first direction. The second sheet of material is sealingly connected to the second intermediate structure around the peripheral edge in order to substantially close off the opening. A vacuum is formed in the annular space with an appropriate porous, thermally insulating material such as fumed silica compacted and placed in the annular space to withstand atmospheric pressure and to provide superior thermal insulation properties. 
         [0007]    Yet another aspect of the present invention includes the method for forming a vacuum insulated refrigerator cabinet providing first and second sheets of material comprising at least a first layer of thermal plastic material that is at least partially permeable to oxygen, nitrogen and water vapor, and a second layer of material that is substantially impermeable to oxygen, nitrogen and water vapor. At least a portion of the first sheet of material is heated to a temperature at which the first sheet of material can be plastically deformed. A first forming tool is utilized to deform the first sheet of material and form a first intermediate structure which defines a cavity having an opening that opens in a first direction and defines a peripheral edge extending around the opening. A second forming tool is also provided. The first intermediate part is disengaged from the first forming tool followed by positioning the second forming tool in the cavity of the first intermediate structure. A base sidewall is plastically deformed in order to form a second intermediate structure having a base sidewall and a plurality of inner sidewalls extending transversely from the base sidewall and defining a second cavity that opens in the second direction substantially opposite the first direction. The inner sidewalls are spaced apart inwardly from the first sidewalls to define an annular space that opens in the first direction. The second sheet of material is sealingly connected to the intermediate structure around the peripheral edge in order to substantially close off the opening. A vacuum is formed in the annular space with an appropriate porous, thermally insulating material such as fumed silica compacted and placed in the annular space to withstand atmospheric pressure and to provide superior thermal insulation properties. 
         [0008]    These and other features, advantages, and objects of the present invention 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 
         [0009]      FIG. 1A  is a side plan view of a prior art version of a vacuum insulated cabinet; 
           [0010]      FIG. 1B  is a side plan view of a prior art version of a vacuum insulated; cabinet; 
           [0011]      FIG. 1C  is a side plan view of prior art version of a vacuum insulated refrigerator cabinet; 
           [0012]      FIG. 2A  is a side plan view of a method according to the present invention; 
           [0013]      FIG. 2B  is a side plan view of the method of the present invention; 
           [0014]      FIG. 2C  is a side plan view of the method of the present invention; 
           [0015]      FIG. 2D  is a side plan view of the method of the present invention; 
           [0016]      FIG. 2E  is a side plan view of the method of the present invention; 
           [0017]      FIG. 2F  is a side plan view of the method of the present invention; 
           [0018]      FIG. 3A  is a side plan view of another embodiment of the present invention; 
           [0019]      FIG. 3B  is a side plan view of the method of the present invention shown in  FIG. 3A ; 
           [0020]      FIG. 3C  is a side plan view of the method of the present invention shown in  FIG. 3A ; 
           [0021]      FIG. 3D  is a side plan view of the method of the present invention shown in  FIG. 3A ; and 
           [0022]      FIG. 4  is a side plan view of yet another embodiment of the method of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0023]    Before the subject invention is described further, it is to be understood that the invention is not limited to the particular embodiments of the invention described below, as variations of the particular embodiments may be made and still fall within the scope of the appended claims. It is also to be understood that the terminology employed is for the purpose of describing particular embodiments, and is not intended to be limiting. Instead, the scope of the present invention will be established by the appended claims. 
         [0024]    Where a range of values is provided, it is understood that each intervening value, to the tenth of the unit of the lower limit unless the context clearly dictates otherwise, between the upper and lower limit of that range, and any other stated or intervening value in that stated range, is encompassed within the invention. The upper and lower limits of these smaller ranges may independently be included in the smaller ranges, and are also encompassed within the invention, subject to any specifically excluded limit in the stated range. Where the stated range includes one or both of the limits, ranges excluding either or both of those included limits are also included in the invention. 
         [0025]    In this specification and the appended claims, the singular forms “a,” “an” and “the” include plural reference unless the context clearly dictates otherwise. 
         [0026]      FIGS. 2A-2F  show a method of forming a vacuum insulated cabinet  10  according to the present invention.  FIG. 2A  shows a first forming tool  24  having a generally quadrilateral perimeter formed from a base wall  29  and a plurality of sidewalls  31  with two extending flanges  28  configured to extend from a bottom portion  25  of the quadrilateral perimeter. The first forming tool  24  may further include at least one vacuum channel  26 .  FIG. 2A  also shows a first material sheet  20 . The first material sheet  20  is typically comprised of a first layer of thermoplastic material that is partially permeable to oxygen, nitrogen and water vapor and a second layer of material that is substantially impermeable to oxygen, nitrogen and water vapor. A typical plastic composite used in this process is a first layer of high impact polystyrene (HIPS) food grade, specially tailored for refrigeration products and a second impermeable layer of EVOH. One exemplary embodiment uses Polystyrol 2710 by BASF and Edistr RR740E by Polimeri Europa as the first layer. 
         [0027]    The first material sheet  20  is first softened typically using heat until the first material sheet  20  reaches a temperature at which the first material sheet  20  can be plastically deformed. Typically, the first material sheet  20  is deformed into a semi-circle like shape typically formed by blowing air centrally on the first material sheet  20  while the first material sheet  20  has its edges clamped down to hold the edges in place, as shown in the dashed lines in  FIG. 2A . The first material sheet  20  is then lowered onto a top perimeter  27  of the first forming tool  24 . The edges of the first material sheet  20  are configured to be clamped onto the flanges  28  of the first forming tool  24 . The flanges  28  are typically comprised of the sidewalls  31  of the first forming tool  24 . A vacuum is then used to thermoform the first material sheet  20  over the first forming tool  24  to form the first intermediate structure  30  (shown in  FIG. 2B ). 
         [0028]    Next, as shown in  FIG. 2B , the first intermediate structure  30  is aligned over a second forming mold  50 . As also shown in  FIG. 2B , the first intermediate structure  30  has a base sidewall  32  defining a generally quadrilateral perimeter  34  and a plurality of first sidewalls  36 , typically four sidewalls, extending transversely from the quadrilateral perimeter  34  in order to define a cavity  38  which has an opening  40  that opens in a first direction and defines a peripheral edge  42  extending around the opening  40 . The opening  40  of the cavity  38  of the first intermediate structure  30  is aligned with a second forming tool  50 . The second forming tool  50  is typically comprised of sidewall portions  52  which define a plurality of generally rectangular outwardly facing surfaces  54  and a plurality of generally rectangular inwardly facing surfaces  56 , and at least one end surface  58  extending transversely between the inwardly  56  and outwardly  54  facing surfaces. Again, the second forming tool  50  includes vacuum holes  53 , to help form the first intermediate structure  30  onto the second forming tool  50  in order to produce the second intermediate structure  60 . 
         [0029]    As shown in  FIG. 2B , the first intermediate structure  30  is heated to a temperature at which it can plastically deform. The first intermediate structure  30  is then formed over the second forming mold  50  using vacuum holes  53  to help form the second intermediate structure  60 . Optionally, a third forming tool  80  may be utilized. The third forming tool  80  is configured to engage the second forming tool  50  in order to help form the second intermediate structure  60 . The third forming tool  80  is typically an opposite version of the second forming tool  50 . For example, if the second forming tool  50  is a female mold, the third forming tool  80  is a corresponding male mold, and vice versa. 
         [0030]      FIG. 2C  shows the second intermediate structure  60 . The second intermediate structure  60  typically includes a base sidewall  62  and a plurality of inner sidewalls  64  extending transversely from the base sidewall  62  and defining a second cavity  66  that opens in a second direction that is substantially opposite the first direction. The inner sidewalls  64  are spaced apart inwardly from the first sidewalls  62  to define an annular space  70  that opens in the first direction. Next, a second material sheet  22  is sealingly connected to the second intermediate structure  60 . The second material sheet  22  is extended across the peripheral edge of the second intermediate structure  60  in order to substantially close off the opening  68  of the second intermediate structure  60  and form an annular space  70 . As shown in  FIG. 2E , the porous insulation material  90  is typically inserted and compacted to a density to withstand atmospheric pressure into the annular space  70  through at least one opening hole  92  typically located on the second material sheet  22 . Additionally, the second material sheet  22  may have additional holes  94  in order to let air exit out of the annular space  70 . Alternatively, the pre-formed and compacted insulation material  90  may be inserted into the annular space  70  of the second intermediate structure  60  prior to the sealing of the second material sheet  22 . Once the insulation material  90  is inserted and the second material sheet  22  is sealingly connected to the second intermediate structure  60 , a vacuum is used, typically in holes  92  and  94 , in order to form a vacuum within the annular space  70  and sealed to produce a vacuum insulated cabinet  10 . Moreover, as shown in  FIG. 2F , a sheet wrapper  100  may optionally be disposed over the vacuum insulated structure  10  in order to provide additional structural support. The sheet wrapper  100  is typically comprised of steel and is generally quadrilateral in shape having an opening  102  on one side configured to receive the vacuum insulated cabinet  10 . 
         [0031]      FIGS. 3A-3D  show an alternate embodiment of the present invention.  FIG. 3A  shows a first forming tool  24  having a base sidewall  29  defining a generally quadrilateral perimeter and a plurality of sidewalls  31  extending transversely from the quadrilateral perimeter in order to define a cavity  33  having an opening  35  that opens in a second direction. As shown in  FIGS. 2A and 3A , the first forming tool  24  may be a male or a female type mold structure. The first material sheet  20  is plastically deformed through heating the first material sheet  20  which allows the first material sheet  20  to form a first intermediate structure  30  utilizing the first forming tool  24 . Edges of the first material sheet  20  are clamped to the flanges  28  or transversely extending sidewalls  31  in order to form the first intermediate structure  30 . Once the first intermediate structure  30  is formed, it typically comprises a base sidewall  32  defining a generally quadrilateral perimeter  34  and a plurality of sidewalls  36  extending transversely from the quadrilateral perimeter  34  in order to define a cavity  38  having an opening  40  that opens in the second direction. 
         [0032]    Next, a second forming tool  50  is disposed inside of the cavity  38  of the first intermediate structure  30 . The second forming tool  50  typically has sidewall portions  52  defining a plurality of generally rectangular outwardly facing surfaces  54  and inwardly facing surfaces  56  and at least one end surface  58  extending transversely between the inwardly  56  and outwardly  54  facing surfaces. Moreover, the second forming tool  50  includes a cavity  57  defined by the at least one base sidewall  55  and plurality of inner sidewalls  64  extending transversely from the base wall  55  defining a second cavity  59  that opens in the first direction. Once the second forming tool  50  is engaged with the first intermediate structure  30 , the first intermediate structure  30  is plastically deformed using a vacuum system to produce a second intermediate structure  60 . The second intermediate structure  60  typically has a base wall  62  and inner sidewalls  64  extending transversely from the base wall  62  defining a second cavity  68  that opens in the first direction and the inner sidewalls  64  are spaced apart inwardly from the first sidewall  62  in order to define an annular space  70 . In the embodiment shown in  FIGS. 3A-3D , the second forming tool  50  is comprised of pre-formed and compacted highly porous insulation material  90 . The insulation material  90  is configured to be solid enough to withstand atmospheric pressure when evacuated and to allow the first intermediate structure  30  to be formed over the insulation material  90  to produce the second intermediate structure  60 . In the embodiment shown in  FIG. 3C , the second forming tool  50  remains within the annular space  70 , and is sealed inside by the second material sheet  22 . The second material sheet  22  is sealingly connected to the second intermediate structure  60  around an edge of the base sidewall  62  of the second intermediate structure  60 . As shown in  FIG. 3D , air can then be evacuated from the structures shown in  FIG. 3C  in order to produce a vacuum insulated cabinet  10 . 
         [0033]    As shown in  FIG. 4 , the insulation material  90  may be inserted into the second intermediate structure prior to the covering of the structure  60  with the second material sheet  22 . The insulation material  90  may be inserted in such a way that forms a semi-circle shape rising above the cavity  66  in the second intermediate structure. The second material sheet  22  is configured to compact the insulation material  90  to a desired compaction level during the sealing process. The addition and compaction steps can be repeated as desired to reach the desired compaction level of the insulation material  90  to withstand atmospheric pressure when the annular cavity is which contains material  90  is evacuated. The insulation material  90  is typically a highly porous granular insulation such as fumed silica or an open cell polyurethane foam or may be any other insulation material  90  known to one of ordinary skill in the art. Any ambient air is then evacuated from the annular space  70  forming a vacuum insulated cabinet  10 . The processes described above result in less thinning of the first  20  and second  22  material sheet in order to ensure that the first material sheet  20  and the second material sheet  22  remain intact in order to provide a vacuum insulated structure.