WO1994025697A1 - Panneau isole sous vide et son procede de fabrication - Google Patents

Panneau isole sous vide et son procede de fabrication Download PDF

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Publication number
WO1994025697A1
WO1994025697A1 PCT/US1994/004484 US9404484W WO9425697A1 WO 1994025697 A1 WO1994025697 A1 WO 1994025697A1 US 9404484 W US9404484 W US 9404484W WO 9425697 A1 WO9425697 A1 WO 9425697A1
Authority
WO
WIPO (PCT)
Prior art keywords
cavity
panel
vacuum
compressed
fiberglass
Prior art date
Application number
PCT/US1994/004484
Other languages
English (en)
Inventor
John A. Bridges
Philip H. Neal
John E. Besser
Original Assignee
Aladdin Industries, Inc.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Aladdin Industries, Inc. filed Critical Aladdin Industries, Inc.
Publication of WO1994025697A1 publication Critical patent/WO1994025697A1/fr

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
    • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
    • F17C13/00—Details of vessels or of the filling or discharging of vessels
    • F17C13/001—Thermal insulation specially adapted for cryogenic vessels
    • E—FIXED CONSTRUCTIONS
    • E04—BUILDING
    • E04B—GENERAL BUILDING CONSTRUCTIONS; WALLS, e.g. PARTITIONS; ROOFS; FLOORS; CEILINGS; INSULATION OR OTHER PROTECTION OF BUILDINGS
    • E04B1/00—Constructions in general; Structures which are not restricted either to walls, e.g. partitions, or floors or ceilings or roofs
    • E04B1/62—Insulation or other protection; Elements or use of specified material therefor
    • E04B1/74—Heat, sound or noise insulation, absorption, or reflection; Other building methods affording favourable thermal or acoustical conditions, e.g. accumulating of heat within walls
    • E04B1/76—Heat, sound or noise insulation, absorption, or reflection; Other building methods affording favourable thermal or acoustical conditions, e.g. accumulating of heat within walls specifically with respect to heat only
    • E04B1/78—Heat insulating elements
    • E04B1/80—Heat insulating elements slab-shaped
    • E04B1/803—Heat insulating elements slab-shaped with vacuum spaces included in the slab
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
    • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
    • F17C2203/00—Vessel construction, in particular walls or details thereof
    • F17C2203/03—Thermal insulations
    • F17C2203/0304—Thermal insulations by solid means
    • F17C2203/0329—Foam
    • F17C2203/0333—Polyurethane
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
    • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
    • F17C2203/00—Vessel construction, in particular walls or details thereof
    • F17C2203/03—Thermal insulations
    • F17C2203/0304—Thermal insulations by solid means
    • F17C2203/0345—Fibres
    • F17C2203/035—Glass wool
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
    • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
    • F17C2203/00—Vessel construction, in particular walls or details thereof
    • F17C2203/03—Thermal insulations
    • F17C2203/0304—Thermal insulations by solid means
    • F17C2203/0358—Thermal insulations by solid means in form of panels
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
    • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
    • F17C2203/00—Vessel construction, in particular walls or details thereof
    • F17C2203/03—Thermal insulations
    • F17C2203/0391—Thermal insulations by vacuum
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
    • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
    • F17C2260/00—Purposes of gas storage and gas handling
    • F17C2260/03—Dealing with losses
    • F17C2260/031—Dealing with losses due to heat transfer
    • F17C2260/033—Dealing with losses due to heat transfer by enhancing insulation
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25D—REFRIGERATORS; COLD ROOMS; ICE-BOXES; COOLING OR FREEZING APPARATUS NOT OTHERWISE PROVIDED FOR
    • F25D2201/00—Insulation
    • F25D2201/10—Insulation with respect to heat
    • F25D2201/14—Insulation with respect to heat using subatmospheric pressure
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
    • Y02A30/00—Adapting or protecting infrastructure or their operation
    • Y02A30/24—Structural elements or technologies for improving thermal insulation
    • Y02A30/242—Slab shaped vacuum insulation
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B80/00—Architectural or constructional elements improving the thermal performance of buildings
    • Y02B80/10—Insulation, e.g. vacuum or aerogel insulation

Definitions

  • the present invention relates to a vacuum insulated panel and to a method of making such a vacuum insulated panel. More particularly, the present invention is directed to a vacuum insulated panel, and to a method of forming such a panel for use as an insulation barrier to prevent transmission of heat between the sides of the panel.
  • Such panels are particularly well suited for use, e.g. , in refrigeration equipment and particularly for use in the door or walls of a refrigerator; however, the scope of potential uses is not limited to the same and a wide variety of applications are presently intended, only some of which are enumerated herein below.
  • the present invention also relates to a vacuum insulated panel and methods of forming such vacuum insulated panels such that the panels will retain a vacuum for extended periods of time, and particularly for fifteen or more years.
  • Vacuum insulated panels fabricated according to the method of the present invention are extremely efficient at preventing the transmission of heat over extended periods of time, are relatively inexpensive and easy to manufacture, and are thus useable in a wide range of industrial, commercial and residential applications. 3. Discussion of Background and Material Information
  • Foam plastic panels are currently very widely employed as insulating panels in refrigerators, refrigerated trucks, picnic coolers and freezers.
  • Refrigerator and freezer manufacturers have been constantly striving to increase the efficiency of their products, and in particular, have attempted over the years to produce a reliable, highly efficient and moderate cost product.
  • attempts to increase efficiency in refrigerators and freezers have achieved success by employing more and better foam insulation in the wall panels of the refrigerators and freezers, by increasing the compressor efficiency and by various design changes, including the relocation of the heat generating components of the refrigerator and/or freezer.
  • the Environmental Protection Agency has promulgated regulations to limit the use of fluorocarbons in all applications, since there is increased concern throughout government, industry and society in general that increased use of fluorocarbons might contribute to depletion of the ozone layer and result in an increase in exposure to ultraviolet rays, which is a significant cause of skin cancer. It is conceivable that, in the not too distant future, the use of fluorocarbons will be totally banned.
  • thermos or vacuum flask It is well known that excellent thermal insulation capability can be obtained by providing a sealed vacuum between two members. Perhaps the most common device utilizing this principal is the ordinary thermos or vacuum flask.
  • STANLEY the assignee's own expired U.S. Patent No. 1,071,817, patented September 2, 1913, such a vacuum or thermos bottle is disclosed.
  • the STANLEY patent discloses filling of an evacuated space between the inner and outer walls of a bottle or flask with a finely divided material, such as metallic oxides, so as to enable the vacuum to achieve a desired degree of heat insulation at a much reduced gaseous pressure, i.e., with much less exhaustion.
  • a "rough” or “soft” vacuum is generally defined as a vacuum having a pressure in the range of 1 to 10 "3 torr (i.e., in the millitorr range).
  • a "high” or “hard” vacuum is generally defined as a vacuum having a pressure in the range of 10 "3 to 10 " ° torr (i.e., in the microtorr range) .
  • a soft vacuum is a vacuum that permits relatively more gases to remain within the evacuated space than in the case of a hard vacuum. Accordingly, while it is substantially easier (i.e., faster and thus less expensive) to obtain a soft vacuum, the thermal insulation efficiency of a hard vacuum is much higher than a soft vacuum. Accordingly, research efforts are now being directed towards developing long-lasting vacuum insulating panels.
  • the difference in thermal conductivity of air or other gases at various pressures can be quite substantial. It is well known that thermal conductivity of air between atmospheric pressure and approximately 10 torr remains relatively constant. Then, there is a sharp drop in thermal conductivity as the pressure is decreased to about 10 '3 torr. There is then little discernable further decrease below pressures of about 10 *3 torr.
  • the vacuum insulated panels of the present invention overcome all of the above mentioned problems and result in vacuum insulated panels of extremely high efficiency, in terms of their impedance to transfer heat, in terms of the long term viability of the vacuum established, and in terms of their manufacturing simplicity; as a result, panels formed in accordance with the present invention result in moderate manufacturing cost.
  • the entire cavity defined by the metal wall members is filled with a cake or block of powder or particulate material, such as activated carbon black, silica (silica gel) , or a combination thereof.
  • a gas-permeable getter-impermeable material is positioned adjacent to a vacuum aperture of the cavity.
  • a vacuum- insulated panel of good durability and insulating qualities is achieved.
  • the filler material contained within the cavity defined by the vacuum panel of the present invention is in the form of a composite material.
  • the composite material comprises a layer of compressed activated carbon and a fiberglass layer.
  • the fiberglass layer is positioned intermediate the carbon layer and the vacuum aperture of the panel.
  • the present invention is directed to a vacuum insulated panel and to a method of producing such a vacuum insulated panel for use in various environments, and particularly in the cabinet walls of refrigerators and freezers.
  • the present invention is directed to a vacuum insulated panel that does not require internal reinforcing members or spacers, but which provides a getter material within the vacuum insulated panel to absorb any gases that may be produced by outgassing from the material of the wall panels thereof.
  • a substantial additional increase in insulation efficiency may be achieved by surrounding at least one side of the vacuum panel of the present invention within a foamed insulating material.
  • the first and second wall members comprise stainless steel panel members, while the gas-permeable getter-impermeable material comprises fiberglass.
  • the panel further includes a foam insulation material covering an exterior side of at least one of the wall members.
  • the preventing structure comprises a fiberglass layer spacing the compressed cake from one of the wall members. Additionally, a fiberglass layer positioned on opposed sides of the compressed cake can be provided, with each layer being adjacent to one of the wall members, one of the layers comprising the preventing structure.
  • the present invention also related to a method of making a vacuum insulated panel, comprising the steps of providing a compressed block of particulate getter material in a recess in a first panel member completely sealing a peripheral edge of the first panel member to a peripheral edge of a second panel member to define a cavity evacuating the cavity through an aperture in one of the panel members, and preventing the evacuation of particulate getter material through the aperture while the cavity is being evacuated by providing a gas- permeable getter-impermeable material within the cavity, between the block and the one panel member, adjacent to the aperture.
  • the method of making a vacuum insulated panel includes the compressing block comprises activated carbon and further includes the step of covering at least one exterior side of the panel with an insulating material.
  • the gas- permeable, getter-impermeable material comprises a layer of fiberglass, and further includes providing a fiberglass layer adjacent each panel member and spacing the compressed block from the panel members, wherein one of the layers comprises the gas-permeable, getter-impermeable material.
  • the invention also relates to a vacuum insulated panel comprising first and second metal wall members joined together about respective peripheral sections of the wall members to define a cavity, a getter positioned within the cavity, the getter comprising a compressed cake of particulate material for filling a portion of the cavity, a device for assisting in evacuating the cavity to establish a vacuum within the cavity, and structure for preventing the getter from being evacuated by the device for assisting in evacuating the cavity, the preventing structure comprising a layer of fiberglass material positioned adjacent the assisting device, the fiberglass material layer contacting one of the metal wall members and the compressed cake of particulate material.
  • the vacuum insulated panel in accordance with the invention also includes an additional layer of fiberglass material on an opposite side of the compressed cake from the fiberglass material layer, the fiberglass layers spacing the compressed cake from the first and second metal wall members.
  • the layer of fiberglass material can comprise fiberglass batting and the compressed cake can comprise compressed activated carbon.
  • each of the metal wall members comprise stainless steel sheets, which are welded to each other.
  • the present invention further relates to a vacuum insulated panel comprising first and second peripherally joined, metal panels defining a cavity, a compressed cake positioned within said cavity, a device for assisting in creating a vacuum within the cavity, and the compressed cake comprises a particulate getter material which fills a portion of the cavity.
  • the preventing structure further acts as the structure for preventing the getter from being evacuated during creation of a vacuum within the cavity.
  • the preventing structure comprises a layer of fiberglass material, the cake and the layer of fiberglass material together preventing the metal panels from contacting each other during creation of the vacuum.
  • the vacuum insulated panel in accordance with the invention utilizes a layer of fiberglass material which comprises fiberglass batting and the compressed cake comprises compressed activated carbon.
  • each of the metal wall members comprise stainless steel sheets, which are welded to each other.
  • the device for assisting in creating a vacuum within the cavity comprise an aperture within one of the metal panels.
  • the contact preventing structure includes layers of fiberglass material surrounding the compressed cake, one of the layers comprising the preventing structure.
  • the method of making a vacuum insulated panel further includes sealing the aperture, and the compressed block includes at least activated carbon. Further, the method involves using the compressed block and the fiberglass material to prevent the metal members from contacting each other during evacuation of the cavity. Additionally, the cavity is evacuated by establishing a hard vacuum within the cavity. Further, the particulate getter material is compressed within the recess in the first metal member.
  • the present invention also relates to a method of forming a vacuum insulated panel comprising the steps of providing a peripherally sealable cavity, positioning, within the cavity, a compressed cake of particulate material between two layers of fiberglass material, providing an evacuation port for the cavity, peripherally sealing the cavity, and evacuating the cavity, through the evacuation port to a hard vacuum.
  • the method also includes sealing the evacuation port to maintain the hard vacuum within the cavity, the cavity being defined by two panel members, wherein the step of sealing the cavity comprises sealing the cavity by contacting the two cavity defining panel members directly to each other, the fiberglass layers preventing the compressed cake from contacting wall surfaces of the cavity and one of the layers being positioned to prevent evacuation of particulate material during evacuation of the cavity.
  • the particulate material and the fiberglass layers are compressed to form a sandwich prior to positioning within the cavity, the compressed block comprises a block of at least activated carbon, and the layers of fiberglass material comprise layers of fiberglass batt. Additionally, a layer of foam insulating material is provided on an exterior surface of the cavity.
  • Fig. 1 is a perspective view of the exterior of a vacuum- insulated panel of a first embodiment of the present invention
  • Fig. 2 is a cross-sectional view of the vacuum insulated panel of the embodiment of the present invention shown in Fig. l, taken along line 2-2 of Fig. 1;
  • Fig. 3 is a partially cross-sectional view of the thermal insulated panel of another embodiment of the present invention, wherein a vacuum panel is encased within a block of polyurethane type foam insulating material;
  • Fig. 4 is a cross-sectional view of the vacuum insulated panel according to yet another embodiment of the present invention, showing the panel cavity formed of one flat and one dish-shaped member;
  • Fig. 5 is a cross-sectional close-up view of a portion of the vacuum insulated panel of the invention showing the area adjacent to the evacuation port in greater detail;
  • Fig. 6 is a cross-sectional view of the vacuum insulated panel according to yet another embodiment of the present invention, showing the panel cavity formed of one flat and one dish-shaped member, wherein the flat side of the panel is covered by or encased in a layer of insulating foam.
  • Fig. 11 is a cross-sectional view of the panel of Fig. 10, after a hard vacuum has been created within the panel, with the particulate material block supporting opposite walls of the evacuated panel;
  • Fig. 12 is perspective view of the exterior of a vacuum insulated panel formed in accordance with yet another embodiment of the present invention.
  • Fig. 15 is a cross-sectional view of the panel of Fig. 12, before a vacuum is created within the panel, but after a layer of fiberglass material has been placed over the compressed block of particulate material, and showing the edges of opposed panels positioned prior to being welded to each other, before a vacuum has been created therein;
  • Fig. 17 is a cross-sectional view of a vacuum insulated panel formed in accordance with yet another embodiment of the present invention prior to sealing the evacuation tube located on one panel wall;
  • Fig. 18 is a cross-sectional view similar to that of Fig.
  • Fig. 19 is a cross-sectional view of the compressed block of the embodiment of Figs. 17 and 18 before being positioned within the base of a panel.
  • the present invention is directed to a vacuum insulated panel and method of making the same. While the vacuum insulated panel of the present invention is particularly directed toward utility in the refrigerator- freezer industry, additional uses therefor are anticipated in ice chests, refrigerated trucks, in roof and building insulation, as well as in any other industrial, commercial or residential environment, wherein highly efficient, long-term thermal insulation is desired. Uses with similar requirements are also clearly within the scope of the present invention.
  • the vacuum insulated panel 10 is formed of two wall or panel members 12, 14, comprising relatively thin, metal sheets, such as stainless steel, that are shaped into the illustrated shallow dish-like configuration using a single stage die or any other conventional forming technique.
  • These wall members 12, 14 have a peripherally extending edge 16 at which the two wall members are welded to each to form an air tight cavity.
  • an exhaust or evacuation tube 18 must be attached to the external surface of one of the panels 12, 14, at an aperture 21 provided on one of the panels.
  • An adhesive 28, for securing the edges of the fiberglass paper 26 onto the inner surface of the panel 14, may comprise a sodium silicate solution because it does not outgas.
  • Outgassing refers to the spontaneous evolution of gas from a material in a vacuum and, as noted above, use of a sodium silicate solution as the adhesive 28 eliminates/minimizes the problem of adhesive outgassing in the vacuum insulated panel. Obviously, outgassing results in deterioration of the vacuum and is to thus be avoided, to as great a degree as possible.
  • Sodium silicate is also selected because it can be baked without deterioration at high temperatures.
  • the block 22 illustrated in Fig. 2 represents a compressed block of powder or particulate material which performs a plurality of essential functions in enhancing the heat insulating properties of the vacuum insulated panel of the present invention.
  • the block can be formed, e.g., of particulate charcoal, activated carbon or carbon black, silica gel (i.e., silica), or an appropriate mixture thereof.
  • silica gel i.e., silica
  • silica silica
  • the terms "silica” and “silica gel” are used interchangeably and refer to a material that is generally designated as silica within the industry.
  • the block is formed, e.g., by compressing the silica gel or carbon to form a solid block or cake of a desired shape and size.
  • the block is manufactured by placing a sheet of fiberglass paper 60 over a vacuum port 62 provided in the bottom of a form 64, as shown in Fig. 8.
  • the form which is generally rectangular (although any desired shape can be utilized, consistent with the selected panel shape) , has dimensions which are very slightly less than the inner dimensions of one of the panel wall members 12, 14.
  • charcoal (or carbon black) 66 is placed within the form over the vacuum, the vacuum is turned on. While the application of a vacuum helps to compress the particulate charcoal or carbon material, a piston type compressor arrangement 68 is provided to apply downward pressure P, on top of the particulate material 66, to tamp it down firmly until it forms a solid cake of the desired density.
  • the packing density utilized according to a preferred feature of the present invention for a charcoal or carbon black particulate material is in the range of 16 to 25 pounds per cubic foot.
  • the compressed block of particulate matter acts as a getter.
  • the function of a getter is to absorb any generated gasses outgassing from the walls of the vacuum panel after the panel has been evacuated.
  • a second, and extremely important, function of the compressed block 22 of particulate material positioned within the cavity defined by the panels 12, 14, is to support the panels that form the wall members of the cavity against collapse during the evacuation of the cavity.
  • a significant shortcoming of known vacuum insulated panels has been the failure to provide satisfactory interior supports to the wall surfaces forming the evacuated cavity in order to prevent the collapse of the cavity upon application of a hard vacuum, which, when used, significantly enhances the energy efficiency of the panel.
  • the compressed block of particulate matter is of sufficient density to support the walls in their spaced configuration, as is clearly shown in Fig. 11.
  • the block of particulate material serves as the only support for spacing the flat main panel portions from each other, during and after application of a desired vacuum. Accordingly, this enables thinner (i.e., more easily deformable) metal sheets to be used for forming the wall panels herein, saving material and thus reducing production costs.
  • a third significant function of the compressed block of particulate material 22 is to act as a radiant barrier to heat transmission through the cavity, via radiation.
  • the block of particulate material utilized within the evacuated cavity is compressed, it nevertheless is of a particulate composition, and thus contains a large number of extremely small voids which substantially diminish the amount of heat transmission by radiation occurring within' the evacuated cavity. Moreover, the compressed cake enhances uniform heat distribution throughout the panel, and thus minimizes/eliminates local hot spots that can adversely affect the insulation properties of the panel.
  • charcoal or activated carbon black when used as the solid particulate material of the present invention, is utilized in a particle size within a range of .4 to 1.0 microns.
  • silica gel i.e., silica
  • a preferred particle size is in the range of 1.0 through 10.0 microns.
  • the particles of silica gel would be compressed via a mechanism such as is schematically illustrated in Fig. 8, to a density lying within the range of 6 to 12 pounds per cubic foot. This is in contrast to the preferred density range of charcoal or activated carbon black which, as set forth above, lies in a preferred range of 16 to 25 pounds per cubic foot.
  • the compressed block of particulate material has very significant functions in the present invention.
  • it acts as a support for the panel walls, it acts as a radiant barrier, and it acts as a getter to keep the vacuum clean over extended periods of time.
  • activated carbon black, or charcoal is noted to be a substantially better conductor (i.e., worse insulator) than silica gel.
  • silica gel is not as efficient a getter material as the activated carbon black. Accordingly, one desirable composition of a material for forming the particulate cake or block 22 can be obtained by using a combination of silica gel and charcoal to achieve a particulate block having effective getter properties, and yet good insulative properties as well.
  • the density to which the block would be compressed would lie somewhere within the ranges set forth above for the carbon black and for the silica gel, depending on the proportions of the various components in the particulate material mixture, and the desired characteristics for the compressed block and complete panel.
  • the cake is positioned between the panel members by first placing it into the shallow depression provided in base panel 14, as shown in Fig. 9.
  • the dimensions of the block 22 are selected so that it substantially fills the cavity formed within the panels 12, 14.
  • the areas shown to exist between the lateral edges of the block 22 and the panel edges (note particularly Figs.
  • the wall panel members 12, 14 are illustrated such that each of them is of a substantially identical, shallow dished configuration, this is not an essential feature of the present invention.
  • the present invention can also be embodied in a vacuum insulated panel wherein the wall members defining the cavity to be evacuated are as shown in Fig. 4.
  • the panel members 30 and 32 are of different shapes.
  • the member 30 is a flat plate while the member 32 is of a dished configuration.
  • the exhaust tube 18 is secured to the dished panel member 32, it is expressly within the scope of the present invention to locate the exhaust tube in the flat member 30, when the panel is formed of one flat and one dished member.
  • the flat plate 30 can be formed of a mild, cold- rolled (e.g., carbon) steel which is less expensive than the stainless steel that is used for the dish-shaped panel member 32 and for each of the substantially identically dished-shaped wall panel members 12 and 14 as shown in Figs. 1 and 2 (stainless steel being used in view of the thinness of the panel member walls) .
  • a flat plate member 30 and a dish-shaped plate 132 are illustrated, the embodiment could equally well involve two substantially identical panel members, each formed of a shallow dish configuration as illustrated in the embodiment of Figs, l and 2, e.g.
  • the thickness of the panel members which form the skin of the chamber or cavity which forms a significant feature of the vacuum insulated panel of the present invention can be, according to a preferred embodiment, selected to be within the range of .002-.013 inch, and preferably .004 inch.
  • the use of this preferred thickness range for the panel wall members results in a very light, very thin and thus relatively inexpensive yet highly efficient vacuum insulated panel.
  • the efficiency of the panel as an insulator is enhanced by the use of thinner panel members since such construction minimizes conductive heat transfer through the panel.
  • vacuum insulated panels as described above are highly suitable for use in refrigerator cabinets and doors and are substantially more efficient from a thermal insulation point of view than an equivalent thickness of blown polyurethane foam, these vacuum insulated panels can nevertheless be made even much more efficient by the addition of a relatively small thickness of the same or a similar foam.
  • FIG. 3 a further embodiment of the present invention is shown in Fig. 3.
  • the vacuum insulated panel 10 substantially as depicted in and as described with respect to Figs. 1 and
  • mild cold-rolled steel is substantially less expensive than stainless steel.
  • stainless steel has the substantial advantage of being significantly more resistant to rust than cold-rolled steel.
  • the foam also acts as a rust inhibitor for the panel. The use of a composite or sandwich panel thus enhances the possible use of a less expensive cold-rolled steel instead of the more expensive stainless steel to fabricate at least one of the panel members.
  • Fig. 6 illustrates a further embodiment of the present invention.
  • the vacuum insulated panel is constructed of one flat and one dish-shaped member, 30 and 32, respectively.
  • the nipple 18 is positioned on the flat member and the foam 40 is applied about the vacuum insulated panel such that the entire flat member 30 is encased within or covered by the foam. However, a portion of the dish-shaped member is not covered by the foam.
  • the exemplary embodiment of the invention as disclosed above can be installed within, for example, the door of a refrigerator by securing the flat surface of the dish-shaped member of the panel to the inside of the shell of the door (e.g. by the use of a suitable adhesive) and then applying the foam 40 thereabout to cover the nipple 18 and to fill the remainder of the door shell cavity to achieve a composite structure similar to that shown in Fig. 6.
  • the ordinate of the graph shows, in degrees Fahrenheit, the change in temperature at the side of the panel opposite from where the hot water was positioned after an interval of sixty minutes.
  • the abscissa of the graph is calibrated in terms of inches of polyurethane foam and represents the equivalent insulating value, in inches of foam, for various constructions of insulating panels.
  • the equivalent R-values are also shown along the abscissa.
  • Plots A and B are labeled in Fig. 7 to show the insulating value of both fresh foam and aged foam.
  • fresh foam has a somewhat better insulating value than aged foam.
  • freon utilized in the manufacture of the foam is retained in the pores of the fresh foam, and thus lowers the heat conductivity thereof.
  • this retained freon escapes from the pores of the foam and is replaced with other gases having a lower resistance to heat transfer than freon.
  • aged foam has a somewhat lower insulating value than fresh foam.
  • a one inch aged foam layer will result in a temperature change of 44° (per 60 minutes)
  • a two inch layer of aged foam will result in a temperature drop of 24° in the same time period.
  • a three inch layer of foam will result in a 14° temperature drop over sixty minutes as shown by the X's on curve B in Fig. 7.
  • these panels exhibit excellent insulating qualities, resulting from the synergistic effect of the vacuum insulated panel according to the present invention and the encasement of one side of the vacuum insulated panel of the present invention within a relatively thin layer of polyurethane foam.
  • the upper panel member 112 is substantially flat and the lower panel member 114 is substantially dish-shaped, with the upper wall panel member having a periphery 116 which mates with the out-turned peripheral flange 117 of dish-shaped lower wall panel member 114 and which are welded to each other along the peripheral area 119.
  • the upper panel 112 is shown as flat, it could instead be provided in the form of a dish-shaped member.
  • the compressed particulate block has, as its primary functions, gettering and providing a radiative barrier whereas the fiberglass layer has as its primary function a filtering of the particulate carbon material to prevent any of the particulate material from entering the vacuum tube.
  • the relatively "short" compressed block of material 122 is provided at the bottom of dish 114, preferably with its upper surface 122a positioned below the peripheral flange 116 of dish 114.
  • the particulate material which would otherwise be at the same height or at a greater height than the periphery 116 (as shown in the embodiment of Fig. 9, for example) will find its way onto the overlying peripheral edge areas where a weld is to be formed. This results in a better seal when the two metal panels are welded, thereby preserving the integrity of the vacuum formed between the panels, and lengthening the useful life of the insulating panel.
  • the use of the fiberglass batt serves several other functions. It provides a larger pumping and filtering area for the vacuum tube, i.e. , a larger area through which air can be evacuated from the sandwich formed by the panels without admitting particulate carbon or other material. It thus provides a larger volume filter to keep charcoal from entering the pump during an evacuation procedure, as is illustrated in Fig. 16, and enables faster evacuation of the cavity.
  • any of the materials previously described above could be used to form the compressed cake or block, depending upon the precise characteristics of the panel desired; and, similarly, it is contemplated that different densities and/or materials could be used to form the fiberglass panel 123.
  • the panel of the embodiment of Figs. 12-16 can be used in combination with a foam layer 40 as discussed with respect to the embodiment of Figs. 3 and 6.
  • Figs. 17-19 illustrate a further embodiment of the present invention with respect to a panel 210.
  • Panel 210 has an upper panel wall 212 and a lower panel wall 214 which are formed from relatively thin metal sheets, e.g., of stainless steel which are welded together, e.g. , by resistance welding or any of the other techniques set forth above with respect to the earlier described embodiments of the present invention.
  • relatively thin metal sheets e.g., of stainless steel which are welded together, e.g. , by resistance welding or any of the other techniques set forth above with respect to the earlier described embodiments of the present invention.
  • the upper panel member 212 is a substantially flat member while the lower panel member 214 is substantially dish-shaped, with the upper wall panel member having a peripheral edge, seam, or flange 216 which mates with the outer turned peripheral flange seam or edge 217 of the dish-shaped lower wall panel member 214 and which are welded to each other along the peripheral area 219.
  • the upper panel is illustrated in Fig. 17 as a flat panel member, it could equally well, within the teachings of the present invention, be in the form of a dish shaped member similar to the lower panel member.
  • An advantage of the sandwich type construction of the filler member is that the activated carbon does not contact either of the metal panel members, but instead is positioned and retained away from the surfaces of the panel members as shown at 222d in Fig. 18. This results in substantially improved insulation values for the composite panel as will be discussed below, while retaining the gettering function of the activated carbon, which in turn results in a vacuum panel of extremely long durability.
  • the entire block of filler material supports the walls of the panel during and after evacuation, as in the previously described embodiments.
  • the sandwich filler construction of this embodiment of the present invention can be fabricated by utilizing in situ compression in an manner similar to that of the embodiment of Figs. 12-16. However, it is the preferred embodiment of the present invention to pre-compress the entire sandwich prior to positioning the sandwich within the wall panel member of the present invention.
  • evacuation of the panel, with the block of filler material contained therein includes heating the panel for approximately 2 hours at a temperature in the vicinity of 650°F to achieve a pressure level of between 10 "3 -10 "4 torr.
  • the panel as described above, being approximately 1/2 in thick and having an area of 15 x 15 in 2 would contain 600 gm of carbon or approximately 100 g of carbon when combined with one or two fiberglass batt layers. Regardless of the composition of the compressed block of material received within the vacuum panel wall members, the block or cake or filler material will provide support for the panel members to prevent collapse during evacuation of the panel.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Architecture (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Electromagnetism (AREA)
  • Civil Engineering (AREA)
  • Structural Engineering (AREA)
  • Thermal Insulation (AREA)
  • Refrigerator Housings (AREA)

Abstract

Panneau isolé sous vide présentant une valeur d'isolation thermique élevée et une durée de vie prolongée du vide, et procédé de fabrication d'un tel panneau. Ce dernier est composé de parois métalliques (212, 214) soudées sur leur périphérie, qui définissent une cavité dans laquelle est disposé un bloc comprimé (222b) d'un matériau particulaire. Ce matériau particulaire, de préférence du charbon actif, de la silice ou d'une combinaison des deux, sert de barrière à la transmission thermique rayonnante à travers le panneau, fait office de dégazeur permettant de maintenir le vide dans la cavité, tout en soutenant les parois du panneau contre l'affaissement lorsque le vide est produit dans la cavité. Ce panneau isolé sous vide peut être recouvert d'un matériau isolant à base de mousse de polyuréthanne. Selon un mode de réalisation, le panneau isolé peut comprendre un gateau comprimé d'un matériau particulaire tel que du charbon actif, ainsi qu'une couche supérieure d'un matelas de fibre de verre. Ces deux matériaux sont pris en sandwich entre les panneaux métalliques, le charbon actif servant de barrière à la transmission thermique rayonnante à travers le panneau, tout en agissant comme un dégazeur, le matelas de fibres de verre (222a) servant à filtrer le matériau particulaire afin de l'empêcher de sortir du panneau lorsque celui-ci est placé sous vide, et permettant également d'essuyer les parois latérales de l'un des panneaux lorsque ces derniers sont assemblés, et d'empêcher l'entrée du matériau particulaire comprimé dans la zone périphérique des panneaux, lesquels sont soudés ensemble pour constituer un panneau entier. Selon un autre mode de réalisation de l'invention, le gateau se trouvant dans la cavité est un élément disposé en sandwich comprenant une couche de charbon actif comprimé (222b) placé entre deux couches (222a, 222c) de fibres de verre comprimées.
PCT/US1994/004484 1993-04-28 1994-04-28 Panneau isole sous vide et son procede de fabrication WO1994025697A1 (fr)

Applications Claiming Priority (2)

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US5343893A 1993-04-28 1993-04-28
US08/053,438 1993-04-28

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0715138A3 (fr) * 1994-12-02 1996-12-04 Matsushita Refrigeration Panneau d'isolation thermique à vide
EP3559571A4 (fr) * 2016-12-23 2020-08-26 Whirlpool Corporation Structures isolées sous vide ayant des structures de chambre interne

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2742385A (en) * 1952-06-14 1956-04-17 Gen Electric Insulated structures
US3052019A (en) * 1960-06-10 1962-09-04 Bell Aerospace Corp Insulation
US3256000A (en) * 1964-04-22 1966-06-14 Union Tank Car Co Method of treating powder
EP0034225A1 (fr) * 1980-02-04 1981-08-26 The Gates Rubber Company Procédé pour la fabrication de courroies trapézoidales
US4745015A (en) * 1981-09-30 1988-05-17 The Dow Chemical Company Thermal insulating panel

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2742385A (en) * 1952-06-14 1956-04-17 Gen Electric Insulated structures
US3052019A (en) * 1960-06-10 1962-09-04 Bell Aerospace Corp Insulation
US3256000A (en) * 1964-04-22 1966-06-14 Union Tank Car Co Method of treating powder
EP0034225A1 (fr) * 1980-02-04 1981-08-26 The Gates Rubber Company Procédé pour la fabrication de courroies trapézoidales
US4745015A (en) * 1981-09-30 1988-05-17 The Dow Chemical Company Thermal insulating panel

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0715138A3 (fr) * 1994-12-02 1996-12-04 Matsushita Refrigeration Panneau d'isolation thermique à vide
US5885682A (en) * 1994-12-02 1999-03-23 Matsushita Refrigeration Company Vacuum heat insulation panel
EP3559571A4 (fr) * 2016-12-23 2020-08-26 Whirlpool Corporation Structures isolées sous vide ayant des structures de chambre interne

Also Published As

Publication number Publication date
CA2161336A1 (fr) 1994-11-10

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