US 2863179 A
Description (OCR text may contain errors)
Dec. 9, 1958 R. s. GAUGLER l 2,863,179
REFRIGERATING APPARATUS Filed June 25, 1955 H/S ATTORNE)l United States Patent REFRIGERATING APPARATUS Richard S. Gaugler, Dayton, hio, assignor to General Motors Corporation, Detroit, Mich., a corporation of Delaware Application June 23, 1955, Serial No. 517,581
Claims. (Cl. 20--4) This invention relates to refrigerating apparatus and more particularly to an improved arrangement for insulating the walls of refrigerators and the like.
It is an object of this invention to provide an improved and practical insulation in which gas having a low coetiicient of conductivity is used in combination with glass fibers or the like.
It is another object of this invention to provide an enclosure material for gas and glass fiber type of insulation which will prevent the escape of the gas as well as prevent the introduction of air or moisture into the insulation.
Still another object of this invention is to provide a packaging material for gas charged insulation which includes a thin plastic sheet having a vapor deposited coating of metal such as aluminum formed on one side of the sheet. l
Prior to this invention it was considered impractical to use a metallic foil as part of the container for the gas and glass fibers due to the fact that the metallic foil would serve to quickly conductthe heat from the one side of the bag to the other side ofthe bag directly through the metal foil itself. It has now been found that by using a vapor deposited metal coating, it is possible to obtain benelits of a metallic film type barrier without any appreciable transfer of heat by conduction through the film itself.
` Another object `of this invention is to provide a gas barrier which represents an improvement over the inventions shown in copending application S. N. 289,482, filed May 23, 1952 now Patent 2,779,066 and S. N. 496,525, tiled March 24, 1955 now Patent 2,817,123.
Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawing, wherein a preferred form of the present invention is clearly shown.
In the drawings:
Figure 1 is a perspective view with parts broken away showing a household refrigerator constructed in accordance with the invention; and
Figure 2 is a fragmentary sectional view on a greatly enlarged scale showing the construction of the wall of the inner bag which encloses the insulating gas and fibers.
Figure 3 is a perspective view with parts broken away showing bag insulation including an outer bag containing a compressible insulation and a gasfilled inner bag having the wall construction shown in Fig. 2.
For purposes of illustrating the invention 'there is shown in the drawings a household refrigerator whereas certain aspects of the invention are equally applicable to other types of products wherein it is desired to provide heat or vapor insulation for preventing the rapid transfer of heat or vapor through a wall section or the like.
Referring now to the drawings wherein a preferred embodiment of the invention is disclosed, reference nud 2,863,179 Ice Patented Dec. 9,
meral 10 designates the outer shell or housing of a con# ventional household refrigerator. Reference numerals 11 and 12 designate the liners or innerv walls of the frozen food compartment 16 and unfrozen food compartment 18 respectively of the refrigerator. The space between each inner wall and the outer wall is lled with bag type insulation 14 to be described more fully herein after. Refrigeration is produced by means of a conventional refrigeration system including evaporator coils 20 which surround the liner 11 of the frozen food storage compartment and a second evaporator 22 disposed in the compartment 18. The usual access door 24 is provided for the food compartments as shown.
The insulation 14 is of the bag type and comprises an outer protective bag 30 within which there is dis-` posed a layer of compressible insulation 32 and an inner gas filled hermetically sealed bag 34 containingl fibrous insulation 36. The brous insulation 36 and the insulation 32 comprise glass fibers or the like. The bag 34 is charged with a suitable insulating gas having a low coeicient of conductivity such as difluorodichloromethane, commonly called Freon or F-l2. It has been found lthat by replacing the air with Freon in each of the inner bags of insulation, it is possible to materially reduce the rate of heat transfer through the insulation. This reduction in the heat transfer makes it possible to reduce the thickness of the insulation approximately 50% without increasing the heat losses through the walls of the refrigerator. The big problem in utilizing the insulating properties of Freon or other similar gases is that of providing a bag which will prevent the loss of Freon from the bag during the life of the refrigerator and which will also prevent the ingress of air into the bag. The density of the iiberglass insulation 32 is preferably about 1.2 pounds per cubic f .g foot whereas the density of the fiberglass insulation 36 in the inner bag is preferablyabout 3.7 pounds per cubic foot. For a more detailed discussion of the problems and general construction involved reference should be made to the above mentioned copending applications.
Referring now to Figure 2 of the drawing wherein the construction of the novel inner bag walls has been shown, reference numeral 40 designates a thin sheet of polyester of ethylene glycol and terephthalic acid commonly known as Mylar which has a vapor deposited aluminum coating 42 on each side thereof. Other metals such as silver or copper could be used for the coating but aluminum is the preferred metal for this purpose. The Mylar sheet 40 is preferably approximately .001 inch thick whereas the Vapor deposited aluminum coating is only 600 to 1000 angstrom units thick. The sheet 40, in conjunction with the one or more layers of vapor deposited aluminum, constitutes an ideal barrier to the passage of air, Freon and moisture. In order to protect the metallic deposit 42 from damage in handling, it is preferable to apply layers of Mylar 44 to opposite sides of the metallized sheet 40. It is also desirable to provide a layer of heat scalable material 46 such as vinylidene chloride, commonly known as Saran on one side of material so as to facilitate forming heat sealed seams 47 for sealing the bags. The vapor deposited aluminum coating is applied to the Mylar while the sheet of Mylar is suspended in a vacuum chamber and aluminum vapor is introduced into the chamber so as to deposit itself on the Mylar. The various laminations forming the walls of the bag 34 have not been shown in Figure 3 of the drawing but it is to be understood that walls of the bag 34 are constructed as shown in Figure 2.
In lieu of the outer protective lrns 44 of Mylar one can use vinyl chloride-vinyl acetate copolymer plasticized with acrylo nitrile rubber. This latter material,
commonly known as Hycar vinyl, is desirable in that it is heat scalable and is sufficiently strong to protect the metallized lm which constitutes the main barrier to the passage of gas and moisture. The metallized lm may be applied to materials other than Mylar such as polystyrene but Mylar is the preferred material for receiving the vapor deposited metal lm in that the metal lm adheres much more readily to the Mylar. Experience indicates that the metal adheres to the Mylar as if an interfacial bond is formed between the Mylar and the metal.
Itwill be noted that the compressible insulation 32 adjacent the `hermetically sealed bag allows for eX- pansion and contraction of the bag without causing bulging of the main refrigerator walls and also makes it possible to press the bags against exposed refrigerant lines such as those forming the evaporator Z without leaving objectionable air pockets between the insulation and the refrigerator walls.
While the form of embodiment of the invention as herein disclosed constitutes a preferred form, it is to be understood that other forms might be adopted, as may come within the scope of the claims which follows.
What is claimed is as follows.
l. In a refrigerator, an outer wall, an inner wall spaced from said outer wall, insulation between said walls supported by said walls, said insulation comprising flexible bag means snugly engaging said walls, ller material within said bag means having voids therein, and a gas lling said voids, said gas having a coecient of thermal conductivity less than that of air, said bag means comprising a plastic film having a vapor deposited metallic coating thereon not more than .00001 inch thick forming a barrier to the passage of said gas, air and moisture.
2. In a refrigerator, an outer wall, an inner wall spaced from said outer wall, insulation between said walls supported by said walls, said insulation comprising ilexible outer bag means snugly engaging said walls, ller material within said bag means having voids therein, and a gas filling said voids, said gas having a coefficient of thermal conductivity less than that of air, said bag means comprising walls formed by a plastic lm having a vapor deposited metallic coating having a thickness of between .000006 and .00001 inch thereon, said plastic film comprising a polyester of ethylene glycol and terephthalic acid.
3. In a refrigerator, an outer wall, an inner wall spaced from said outer wall, insulation between said Walls supported by said walls, said insulation comprising outer bag means snugly engaging said walls, filler material within said bag means having voids therein, and a gas lling said voids, said gas having a coefficient of thermal conductivity less than that or air, said bag means comprising walls formed by a lm of a polyester of ethylenel glycol and terephthalic acid having a vapor deposited metallic coating less than .00001 of an inch thick.
4. Bag type insulation adapted to be confined and supported between spaced walls comprising means forming a bag having a seam, ller material within said bag having voids therein, and a gas filling said voids, said gas having a coeicient of thermal conductivity less than that of air, the walls of said bag comprising a plastic lm having a vapor deposited metallic coating thereon not more than .00001 inch thick and -a layer of scalable `material for sealing the bag at its seam.
5. Bag type insulation adapted to be confined and supported between spaced walls comprising means forming a bag, filler material within said bag having voids therein, a gas lling said voids, said gas having a coelcient of thermal conductivity less than that of air, said bag means comprising walls formed by a lm comprising a polyester of ethylene glycol and terephthalic acid having a vapor deposited metal coating less than .00001 of an inch thick.
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