Abstract:
An apparatus for evacuating and sealing a panel having a core material and a pair of walls. The apparatus includes a flexible bag that surrounds the panel and a vacuum pump assembly configured to evacuate air from within the bag. A sealing mechanism is located in the bag. The sealing mechanism is configured to bond at least one pair of adjoining edges of the pair of walls together to seal a panel with an evacuated core.

Description:
CROSS-REFERENCE TO RELATED PATENT APPLICATIONS 
       [0001]    This application claims priority to and the benefit of U.S. Provisional Patent Application No. 61/272,201, filed Aug. 31, 2009, which is incorporated by reference herein in its entirety. 
     
    
     BACKGROUND 
       [0002]    Vacuum insulation panels are used to provide extremely high temperature insulation values with a relatively small thickness of insulating material. Vacuum insulation panels comprise two walls or films that define an interior space. Gasses such as air in the interior space are evacuated to form a partial vacuum. Because they are almost completely isolated from each other, the two walls transfer very little heat by conduction. The lack of gasses between the walls limits the heat exchange due to convection. To prevent atmospheric pressure from collapsing the vacuum insulation panel, a core or filler material is provided between the outer walls. In the presence of a partial vacuum, the walls are then sealed around the outside periphery to form the vacuum insulation panel. 
         [0003]    Because the edges must be sealed, vacuum insulation panels are formed to specific finished dimensions and cannot be trimmed or cut. Applications for the vacuum insulation panels are therefore limited by the shape and size of panels. The current manufacturing process for vacuum insulation panels uses a vacuum chamber with limited dimensions. The conventional vacuum chamber places a limit on the size of panels that can be made, which severely restricts the fields where the product can reasonably be used. The rigid vacuum chambers used to construct vacuum insulation panels are generally fairly small, limiting the ability to make larger panels, for example, for use in building construction or the like. A rigid vacuum chamber also contains a large interior volume, increasing the amount of air that must be evacuated to draw a vacuum. 
         [0004]    Further, there is currently no convenient way to make curved or specially shaped vacuum insulation panels. Such pieces would be useful in custom construction as well as other applications, such as automotive body panels. 
         [0005]    It would be advantageous, therefore, to provide a flexible method of forming vacuum insulation panels of a wide variety of shapes and sizes. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]    These and other features, aspects, and advantages of the present embodiments will become apparent from the following description, appended claims, and the accompanying exemplary embodiments shown in the drawings, which are briefly described below. 
           [0007]      FIG. 1  is an isometric view of a vacuum insulation panel according to an exemplary embodiment. 
           [0008]      FIG. 2  is a cross-section of the vacuum insulation panel of  FIG. 1  taken along line  2 - 2 . 
           [0009]      FIG. 3  is a schematic side view of the vacuum insulation panel of  FIG. 1  inserted into a flexible vacuum bag to evacuate the air inside the insulation panel. 
           [0010]      FIG. 4  is a schematic side view of a shaped vacuum insulation panel inserted into a flexible vacuum bag to evacuate the air inside the insulation panel. 
       
    
    
     DETAILED DESCRIPTION 
       [0011]    A flexible vacuum chamber using a polyurethane or silicone vacuum bag is provided to form a vacuum insulating panel. As shown in  FIGS. 1-2 , the vacuum insulating panel  10  comprises two walls or films  14  and  16  that surround a core or filler insulation material  12 . Vacuum insulation panels may be used in a wide variety of applications including appliances such as coolers, refrigerators, and freezers; building applications; and automobile and other vehicles applications. 
         [0012]    The core material  12  provides physical support for the insulation panel  10  to prevent the panel  10  from being collapsed by atmospheric pressure. Further, the core material  12  is configured to reduce convectional heat transfer by interrupting the flow of any gas molecules which may still remain inside the insulation panel  10  after the evacuation process. Such core materials may be, for example, perlite, mineral powder, mineral fiber, fiberglass, silica, open-cell foam or an aerogel or any other relatively low-weight material with a low thermal conductivity. According to one exemplary embodiment, the core  12  is formed of a carbon/silica aerogel. Carbon/silica aerogels are able to absorb gasses and moisture that may be trapped within the insulation panel  10 , thereby increasing the effectiveness of the panel  10 . 
         [0013]    The core material  12  is surrounded or encapsulated by two membrane films  14  and  16  which form the walls of the vacuum insulating panel  10 . The membrane films  14  and  16  provide a barrier against atmospheric gases and moisture so that the vacuum can be maintained. Ideally, the membrane films  14  and  16  are formed of a material such as glass or a metal foil that is impenetrable by atmospheric gasses. Glass, however, is too fragile for most applications where vacuum insulation panels are used. Metal can be used but significantly reduces the average insulation value of finished panel. Because the edges  17  of the two membrane films  14  and  16  are coupled together about the periphery of the panel  10 , heat can be transferred by conduction from one film to the other along the edges of the panel  10  if they are formed of a metal or other thermally conductive material. Generally, the films  14  and  16  are formed of a polymer film or a metal/polymer laminate film. Polymer or polymer/metal laminate films  14  and  16  are sealed about the periphery of the vacuum insulating panel with a heat sealing process or ultrasonic welding. 
         [0014]    The core material  12  is encased in the membrane films  14  and  16  with an open end  18  left along one edge through which air can be evacuated to draw a vacuum. According to an exemplary embodiment, shown in  FIG. 3 , the insulation panel  10  is then placed in a flexible vacuum assembly  20 . The vacuum assembly  20  comprises a flexible vacuum bag  22  that receives the insulation panel  10 , a vacuum pump assembly  24  to evacuate the air from inside the vacuum bag  22 , and a sealing mechanism  26  disposed inside the vacuum bag  22 . 
         [0015]    The vacuum bag  22  is configured to be large enough to completely surround the insulation panel  10  and the sealing mechanism  26 , but small enough to limit the interior volume of the bag  22  and the amount of air that must be evacuated from the interior of the bag  22 . The bag  22  is larger than the vacuum insulation panel  10  and sealing mechanism  26  (e.g., 10-15% larger) to allow the bag  22  to conform to the shape of the insulation panel  10  and sealing mechanism  26  as the air inside the bag  22  is evacuated. The bag  22  is formed from a flexible material that is relatively impermeable to air (e.g., polyurethane, vinyl, silicone, nylon, polyvinyl acetate, polyethylene, rubber, a rubber or polymer-coated fabric, a laminate of several different films, etc.). The vacuum bag  22  may be premade and selected to fit the size of the vacuum insulation panel  10  or may be custom made to fit the vacuum insulation panel  10 . 
         [0016]    The bag  22  is open on one end  28  to allow the insulation panel  10  and the sealing mechanism  26  to be inserted into the bag  22 . A breather layer (e.g., a fabric with a large, open weave) may be placed on one or both sides of the vacuum insulation panel  10  to allow air to more easily pass along the surface of the vacuum insulation panel  10  as the air is being evacuated from inside the vacuum bag  22 . After the insulation panel  10  and the sealing mechanism  26  have been inserted into the bag  22 , the open end  28  is closed (e.g., with a clamp, clip, tape, an adhesive, or other closure, etc.). 
         [0017]    The vacuum pump assembly  24  is coupled to the vacuum bag  22  with a hose or pipe  30 . The vacuum pump assembly  24  comprises a pump  32 , a gauge  34 , an air tank  36 , a check valve  38 , and a relief valve  40 . A connector allows air from inside the vacuum bag  22  to be evacuated by the pump  32  through the hose  30 . According to one exemplary embodiment, the hose  30  is simply fed through the open end  28  of the vacuum bag  22  and the bag  22  is sealed around the hose  30  with tape  42 , an adhesive, a clamp, or another closure. According to another exemplary embodiment, a valve or port may be coupled to the vacuum bag  22  to which the hose  30  may be connected with a corresponding fitting. 
         [0018]    According to an exemplary embodiment, the vacuum pump  32  draws a vacuum of less than approximately 0.0050 tons (0.0067 mbar) inside the vacuum bag  22 . 
         [0019]    In order to seal the open edge  18  of the panel  10  once the panel  10  is fully evacuated, a sealing mechanism  26  is provided at least partially inside the vacuum bag  22 . According to one exemplary embodiment, the sealing mechanism  26  is a heat sealer. The heat sealer  26  comprises an upper sealing element  50  and a lower sealing element  52 . The edges of the membrane films  14  and  16  that form the open end  18  are received between the upper sealing element  50  and the lower sealing element  52 . After the vacuum pump  32  has evacuated the air from inside the vacuum bag  22 , the open edges  18  of the membrane films  14  and  16  are compressed between the upper sealing element  50  and the lower sealing element  52  and the sealing elements  50  and  52  are heated. The heat and pressure cause the material forming the membrane films  14  and  16  to melt together, creating a bond. The sealing elements  50  and  52  may be continuously heated or may only be heated periodically, when compressing the open edge  18  of the membrane films  14  and  16 . Once the open edge  18  of the vacuum insulation panel  10  is sealed, the vacuum bag  22  may be opened, allowing the interior of the bag  22  to return to atmospheric pressure and the vacuum insulation panel  10  to be removed from the vacuum bag  22 . 
         [0020]    While the sealing mechanism  26  is shown as a hot bar heat sealer in the Figures, according to other exemplary embodiments, other sealing mechanisms may be used to close the open edge  18  of the vacuum insulation panel  10 . For example, the sealing mechanism  26  may comprise a moveable sealing head that is slid across the open edge  18  of the membrane films  14  and  16 , compressing and heating the membrane films  14  and  16  as the head moves along the edge to create a seal. According to still other exemplary embodiments, the sealing mechanism  26  may seal the open edge  18  of the membrane films  14  and  16  with an ultrasonic welding or an RF welding operation. 
         [0021]    Power for the sealing mechanism  26  may be provided by a battery or may be provided by an external source (e.g., the electrical grid) through a cord that passes through an opening in the vacuum bag  22 . The cord may pass through the open end  28  of the vacuum bag  22 , with the bag  22  being sealed around the cord with tape, an adhesive, a clamp, or another closure. The cord may also pass through a sleeve, gasket or other body coupled to a hole in the vacuum bag  22  that forms an airtight seal between the cord and the vacuum bag  22 . 
         [0022]    Referring now to  FIG. 4 , according to another exemplary embodiment, a flexible vacuum chamber  60  may comprise a mold tool or form  62  that matches the contour of the insulation panel  10  and a vacuum bag or film  64  covering the insulation panel  10 . The flexible vacuum chamber  60  further comprises a vacuum pump assembly  66  to evacuate the air from between the mold tool  62  and film  64 , and a sealing mechanism  68  disposed between the mold tool  62  and film  64 . The vacuum pump assembly  66  and the sealing mechanism  69  may be similar to the vacuum pump assembly  24  and sealing mechanism  26  described above. 
         [0023]    A curved or otherwise contoured (i.e., not flat) panel  10 , as shown in  FIG. 4 , requires a support member such as the mold tool  62  to prevent the panel  10  from collapsing under atmospheric pressure when a vacuum is drawn in the vacuum bag  64 . While the flexible vacuum chamber  60  comprising a curved mold tool  62  (e.g., shown in  FIG. 4 ) may be used to form a curved vacuum insulation panel  10 , according to other exemplary embodiments, a flat panel may be formed using a flat mold. 
         [0024]    The mold tool  62  is a rigid body that conforms to the shape of the vacuum insulation panel  10 . The mold tool  62  includes a mold surface  70  corresponding to the shape and size of the insulation panel  10  and a flange  72  that extends outward from the mold surface  70 . The mold tool  62  is formed of a material that is impermeable to air. 
         [0025]    The film  64  is a material that is generally impermeable to air (e.g., polyurethane, vinyl, silicone, nylon, polyvinyl acetate, polyethylene, rubber, a rubber or polymer-coated fabric, a laminate of several different films, etc.). The film  64  is coupled to the mold tool  62  such that the vacuum insulation panel  10  is held between the film  64  and the mold tool  62 . 
         [0026]    The insulation panel  10  is laid on the mold surface  70 . An adhesive material such as a sealing tape  74  is applied to the flange  72  of the mold tool  62  around the periphery of the mold surface  70 . The sealing tape  74  is a strip of resilient or putty-like material that is adhesive on both sides. The film  64  is then placed over the vacuum insulation panel  10  such that the film  64  overlaps the sealing tape  74 . The film  64  is pressed down to form a seal with the sealing tape  74 . A vacuum chamber  65  is therefore created between the mold tool  62  and the film  64 . 
         [0027]    The vacuum pump assembly  66  is coupled to the film  64  with a hose  80  in a manner similar to that described above. As shown in  FIG. 4 , according to one exemplary embodiment, the hose  80  is simply fed through one edge of the film  64  and the film  64  is sealed around the hose  80  with sealing tape  74 . According to another exemplary embodiment, a valve or port may be coupled to the film  64  to which the hose  80  may be connected with a corresponding fitting. 
         [0028]    According to one exemplary embodiment, the mold tool  62  may be formed of a thermally conductive material (e.g., a metal) and be heated during the insulation forming process to reduce the moisture content of the core material  12  of the panel  10 . Heat may be applied to the panel  10  through the support base or mold. By reducing the moisture content of the space between the two membrane films  14  and  16  (e.g., the moisture in the core material  12 ) the thermal conductivity of the vacuum insulation panel  10  is reduced, increasing its longevity and effectiveness. 
         [0029]    As mentioned above, the mold tool  62  may be flat, allowing a heated flat table or support surface to be employed as the mold tool  62 . Also, if the use of a mold tool  62  is not desired (see e.g., the system shown in  FIG. 3 ), the flexible vacuum chamber  60  may be modified to include a heated table or heated support surface placed adjacent to the vacuum panel  10 . 
         [0030]    Once connected, the vacuum pump assembly  66  is used to evacuate the air from inside the vacuum chamber  65  and from inside the vacuum insulation panel  10 . After the vacuum pump  66  has evacuated the air from inside the vacuum chamber  65 , the panel  10  is sealed with the sealing mechanism  68 . The open edges  18  of the membrane films  14  and  16  are compressed between the upper sealing element  82  and the lower sealing element  84  and the sealing elements  82  and  84  are heated. The heat and pressure cause the material forming the membrane films  14  and  16  to melt together, creating a bond. Once the open edge  18  of the vacuum insulation panel  10  is sealed, the vacuum chamber  65  may be opened by separating the film  64  from the mold tool  62 , allowing the interior of the chamber  65  to return to atmospheric pressure and the vacuum insulation panel  10  to be removed from the vacuum chamber  65 . 
         [0031]    If the mold tool  62  is not impermeable to air (e.g., if the tool includes cracks, holes, or other openings), a vacuum bag resembling that shown in  FIG. 3  is used to completely encapsulate the mold tool  62 , the vacuum insulation panel  10  and the sealing mechanism  68 . The vacuum chamber  65  is therefore formed by the vacuum bag with the mold tool  62  forming a support structure inside the vacuum chamber  65 . 
         [0032]    Using a flexible vacuum chamber  20  and  60  as described above has several advantages when forming a vacuum insulation panel  10  compared to conventional methods, which use a rigid vacuum chamber with a fixed interior volume. The interior volume of the vacuum chamber limits the size of the vacuum insulation panel that can be manufactured. Currently, vacuum insulation panels are used primarily for small enclosures, such as refrigeration boxes on boats. The size limitations of rigid vacuum chambers are a relatively small concern when the vacuum insulation panels themselves are relatively small. 
         [0033]    However, using a flexible vacuum assembly  20  or  60 , either with a backing mold  62  (referring to  FIG. 4 ) or without (referring to  FIG. 3 ), allows larger vacuum insulation panels  10  to be manufactured without a substantial rise in cost. A flexible vacuum assembly  20  or  60  allows larger panels  10  to be made for applications such as doors, etc. The vacuum bag material  22  or film  64  is durable, flexible, and reusable. Because the vacuum chamber (e.g., the interior of bag  22  or chamber  65 ) is flexible rather than rigid, the chamber can be sized so that there is less excess air to remove. By reducing the interior volume of the vacuum chamber, the vacuum time is reduced, in turn reducing the energy cost of running the vacuum pump assembly  24  or  66 . The reduction of the vacuum chamber interior volume using a flexible vacuum assembly  20  or  60  reduces the time and energy needed to form even smaller vacuum insulation panels  10 , such as those currently manufactured for refrigeration boxes using rigid vacuum chambers. The use of a flexible vacuum assembly  20  or  60  allows for panels  10  of various shapes (e.g., long, narrow panels, etc.) to be manufactured. Using a mold  62 , curved vacuum insulation panels  10  may be formed with a flexible vacuum assembly  20  or  60 . 
         [0034]    A flexible vacuum assembly  20  or  60  is lighter than a similarly sized rigid vacuum chamber. The flexible vacuum assembly  20  or  60  may therefore be transported to a construction site so that custom panels  10  may be made at the site. Custom insulation panels  10  may then be created to accommodate changes in the design of the structure for which the insulation panel  10  is being manufactured. 
         [0035]    Similar vacuum bag setups are used in other fields, such as boatbuilding, to compress or laminate materials. A vacuum bag assembly for manufacturing vacuum insulation panels may therefore be used with much of the same equipment (e.g., vacuum pump, gauges, hoses, sealing tape, vacuum bag film, etc.) as the existing lamination vacuum bag assemblies. Vacuum insulation panels may be manufactured for a variety of boat building applications, such as for refrigeration boxes, boat cabins, etc. 
         [0036]    It is important to note that the construction and arrangement of the flexible vacuum chamber as shown in the various exemplary embodiments is illustrative only. Although only a few embodiments have been described in detail in this disclosure, those skilled in the art who review this disclosure will readily appreciate that many modifications are possible (e.g., variations in sizes, dimensions, structures, shapes and proportions of the various elements, values of parameters, mounting arrangements, use of materials, colors, orientations, etc.) without materially departing from the novel teachings and advantages of the subject matter described herein. For example, elements shown as integrally formed may be constructed of multiple parts or elements, the position of elements may be reversed or otherwise varied, and the nature or number of discrete elements or positions may be altered or varied. The order or sequence of any process or method steps may be varied or re-sequenced according to alternative embodiments. Other substitutions, modifications, changes and omissions may also be made in the design, operating conditions and arrangement of the various exemplary embodiments without departing from the scope of the present embodiments.