US20110047934A1

US20110047934A1 - Flexible vacuum chamber

Info

Publication number: US20110047934A1
Application number: US12/871,690
Authority: US
Inventors: Lance Brown
Original assignee: Glacier Bay Inc
Current assignee: Glacier Bay Inc
Priority date: 2009-08-31
Filing date: 2010-08-30
Publication date: 2011-03-03

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

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

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.
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.
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.
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

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.

FIG. 1 is an isometric view of a vacuum insulation panel according to an exemplary embodiment.

FIG. 2 is a cross-section of the vacuum insulation panel of FIG. 1 taken along line 2-2.

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.

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

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.
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.
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.
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.
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.
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.).
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.

Claims

1. An apparatus for evacuating and sealing a panel having a core material and a pair of walls, comprising:

a flexible bag configured to surround the panel;

a vacuum pump assembly configured to evacuate air from within the bag;

a sealing mechanism located in the bag, wherein the sealing mechanism is configured to bond at least one pair of adjoining edges of the pair of walls together to seal the panel after the core material has been evacuated.

2. The apparatus of claim 1, further comprising a layer of breathable material positioned between the panel and the bag.

3. The apparatus of claim 1, wherein the vacuum pump is connected to the bag with a hose and wherein the hose extends into the bag and wherein the connection between the hose and the bag is sealed.

4. The apparatus of claim 1, wherein the sealing mechanism comprises a heat sealing mechanism.

5. The apparatus of claim 1, wherein the sealing mechanism comprises an RF welding device.

6. The apparatus of claim 1, further comprising a curved mold for supporting the panel during the evacuation of the bag.

7. The apparatus of claim 1, wherein at least one portion of the bag is a curved rigid mold for supporting the panel during evacuation of the bag.

8. The apparatus of claim 6, wherein the mold comprises a heater for heating the panel and thereby removing moisture from the core material.

9. A method for evacuating and sealing an insulation panel including a core material and a surrounding film, comprising the steps of:

placing the panel in a flexible bag;

placing a sealing mechanism in the bag;

evacuating the bag using a vacuum pump assembly;

after the core material is evacuated, sealing edges of the surrounding film to thereby seal the evacuated core material.