US2000863A - Heat insulating wall construction - Google Patents

Description

May 7, 1935- v E, R. POWELL v 2,000,863

HEAT INSULATING WALL CONSTRUCTION Filed OGL. l5, 1928 'lll/1.1112711'.- ff

Patented May 7, V19.35

UNITED sTATEs 2,000,863 HEAT TNSULATTNG WALL CONSTRUCTION Edward R. Powell, Alexandria, Ind., assignor, by Amesne assignments, to Johns-Manville Prod? ucts Corporation,v New York, N. Y., a corporation of Delaware Application october 15, 1928, serial No. 312,543

2 claims. (ci. 22o- 9) i This invention relates to improvements in heatinsulating wall constructions and the like, and particularly to means for the preventionA of the accumulation of moisture Within refrigerator walls.

l Among the several objects of this invention may be noted the establishment of means for positive exclusion of moisture-laden air from the aircells which ymake the insulation effective, the provision of an insulated wall which will permit so-called breathing freely and, at the same time, be air-tight, the provision of means for permitting free expansion of air` into and out of an insulating block without permitting moisture-laden air to contact with its cold inner surfaces so as to cause condensation, and the provision of an' insulated wall of the class described which can be easily and cheaply constructed and which` is durable. Other objects will be in part obvious and in part pointed out hereinafter.,`

The invention accordingly comprises the elements and combinations of elements, features of construction, and arrangements of parts which will be exemplified in the structure hereinafter described, and' the scope of the application of which will be indicated in the following claims. y

In the accompanying drawing in which are il lustrated three of various of the invention, l Fig. 1 is a sectional view of a refrigerator Wall;

Fig. 2 is an enlarged sectional view of a portion of the insulation shown in Fig. 1;

Fig. 3 is an enlarged sectional view of the insupossible embodiments a wall, preferably f lation under different `conditions than exist in Fig. 2;

Fig. 4 is a sectional View illustrating the conf f densation of moisture-laden air on an insulated wall;

Fig. 5 is a sectional View illustrating one embodiment of the invention;-

Fig. 6 is a sectional view illustrating a second embodiment of the invention; and,

Fig. 7 is a sectional view of a. third embodiment.l

- Similar reference characters indicatey corresponding parts throughout `the several views of the drawing.

Referring now more particularly to -the drawing, Fig. 1 illustrates in section a conventional refrigerator wall construction, in which numeral l indicates a Wooden corner post, 3 indicates an exterior sheet metal casing, 5 indicates an insulating material and 1 indicates an interior sheet metal lining.' This illustration is exemplary of the refrigerator construction in common use today. It has several notable disadvantages, which will be set out hereinafter. The insulation material 5, whether it be cork board, rock cork, hair felt or any of the other fibrous insulating materials is absorbent towards water; b ut in order to /there were no insulating material present.

keep it at its best insulating value, it is desirable that it be kept dry. On the other hand expanded rubber of certain kinds has such a welldefined cellular structure and the cells are so nearly air-tight that breathing effects are not always present. A But these breathing effects with their prior disadvantages are always present in an insulation ofibrous character whether the bers are coated or uncoated, loose or molded into blocks. For this purpose the insulation is generally coated with asphalt, as illustrated at 9, on the side which is not in tight connection with an airtight sheet metal lining. This construction is assumed to be waterproof because if water is l poured on the asphaltized surface, it runs off immediately and does not wet the surface. However, it is not altogether true that this asphalt coating is waterproof, as will'appear hereinafter.

When the air contained in the pores of the insulating material is subjected to change in temperature, the air expands and contracts, undergoing an appreciable change of volume. Under iconfined conditions, the effect is an appreciable change of pressure. It may be mentioned that in the average heat insulating material approxi- Vmately eighty to ninety per cent of the total 'volume is occupied by air; therefore, the expansion isfor all practical purposes the same as if In consequence, the heat insulating material must have an outlet for the increased volume of air contained therein, and the air frequently enters and enlarges minute holes or pores in the asphalt coating. When the temperature drops, and the volume inside contracts, there is created at these minute pores a suction or negative pressure, and any lm of water which may be upon the surface is drawn inwardly to dampen the insulating is deleterious to the insulation, and renders it, `in fact almost useless. The alternate giving out and taking in of air, as described, is commonly called breathing.

Fig. 4 illustrates how a slab of insulation which admits air at a few places Il quickly becomes saturated with water. Thev 'cold inner surface I3 .f

stant volume. Such panels would probably have Sii Y pressure.

I the dotted line.

to be built of thin metal sheets with all seams soldered -or welded, and would need to be tested for air-tightness.v As a result it would be extremely diicult to produce a number of containers that were entirely air-tight Without a largepercentage of the number being rejected; thereby increasing the production costs. In addition, such a'metal container would not be entirely practicable to use, as it probably ,wouldvbe unable to withstand the pressures generated, which, it has been shown, amount to over two hundred pounds per square foot with a temperaf ture change. or increment of sixty degrees Fahrenheit. This pressure would be more than sufficient to buckle a thin sheet of metal and destroy soldered or welded seams.

My invention comprises the provision of means for allowing for a free expansion of air into and out of the insulating material without permitting moisture-laden air to contact with the cold innersurface and condense to eiect the ruination of the insulation.

Fig. illustrates one rform of the invention. In this form the asphalt coating 9 is entirely eliminated. The insulation block 5 composed of rock cork or cork board or` other iibrous insulating --materials is .so cut as to t snugly aga'inst the inner sheet metal lining l! and the Wood corner" post l. An angular flashing strip ill is placed between the wooden post and the insulation material with its upper end overlapping the top of the block of insulation. This flashing strip continues substantially all the way around the block of insulation and provides the means for holding to the edge thereof a iiexible air-tight diaphragm I9. This flexible air-tight diaphragm is formed 'with a reex, curved surface which may expand or be iiexed, for example, as illustrated in the alternative positions (in dotted lines) so as to .allow a large increase in volume of contained `gases, and at the same time prevent admission on contraction of any moisture-laden air. The principle on which this operates is that the surface 2l of the insulation, being unhampered by the presence of an asphalt vor other coating,

'-.breathes freely into the open space 23 between said surface 2l and the diaphragm l 9 pushing out said diaphragm. As a result there is little or no excess pressure set up, the volume increasing substantially so as to accomodate any or exloessive increase in pressure and maintain the 'total pressure substantially equal to the exterior As a result there is no tendency to leak at the inner surfaces and edges of the block of insulation.

Fig. 6 illustrates an alternative form and second embodiment ofthe invention which comprises a flexible air-tight tough, coated paper diaphragm 25 constructed with a concave formation, with which it is possible to take up the expansion of air and take an over-centered, expanded, bulged or buckled position illustrated by In this embodiment the diaphragm is supported at each side by block supports 21, which hold the diaphragm at a suitable distance from the insulation surface.

g Fig. 7, illustrating a third embodiment of the invention, shows a trap made of layers of paper 29, laid in piled position and alternately joined at opposite'ends to the' end supporting members 28 so as to permit expansion but retard or prel aooaaca vent to a great extent by providing a tortuouspath the mixing of the cold dry air in the insulation with the relatively warm moist air outside. l

The layers of paper constitute a flexible sealing diaphragm secured at its outer edges and provided in the midportion with means for facilitating flexing, including discontinuous overlapping portions. i

The principle set forth is that a diaphragm is in some fashion held to the surface'ofthe in sulation so as to permit expansion of the air therein without substantial increase in pressure therein, and at the samev time prevent the entrance of warmy moist air into the insulation block.

The three embodiments set forth are merely ex emplary of thetrange of modication of panel construction which is comprehended by this invention. For example, vthe diaphragm may be made of cloth or paper saturated with rubber, oils, waxes, and asphalts and such materials. Flexibility is desirable, so that the response to 1ncreased pressure will be immediate, eliminating opportunities for the air to be dissipated at the edges. This invention comprehends the simultaneous use of two or more-diaphragms in a structure, such as, for example, a combination oi' modifications shown in.l Figs. 5 and 7. in this instance it is desirable that the third embodiment be placed adjacentY to the insulation inside oi the first embodiment. With this structure, if the exterior diaphragm for some reason broke down,

ther interiordiaphragm would serve as a seal and diiusion would be substantially prevented.

In view of the above, it will be seen that the several objects of the invention are achieved and other advantageous results attained.

Asmany changes could bemade vin carrying out the above constructions Without departing from the scope of the invention, itis intended that all matter contained in the above description or shown in the accompanying drawing shall be interpreted as illustrative and sense. A

I claim:

not in a limiting elliv 1. The heat insulating wall constructionwhich comprises spaced interior and exterior sheets of protective sheathing, heat insulating material disposed therebetween, a diaphragm having a reflex surface attached to the exterior surface of said. insulation material and defining' a space with the exterior sheathing and adapted to buckle under conditions of increased pressure within said insulation material and substantially ,accommodate said increase in pressure.

2. The heat insulating wall construction which comprises interior and exterior protective sheathings, insulation material therebetween ai'xed to said inner protective sheathing, a diaphragm with 1 reiiexed curvature attached by means oi.' a ashing strip extending around the the edge of the insulation` to said insulation material, defining a Spacey/ith the exterior sheathing, and adapted to increase the space between said diaphragm and said insulation material `when an increased pressure is set up within said insulation material, and at the Sametime substantially prevent any flow of air or other fluid f rom the exterior surrounding into the insulation material.

` EDWARD R. POWELL.

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