US3038772A - Arrangement for draining off the defrosting water in refrigerating containers, particularly refrigerator cabinets - Google Patents

Description

OSTING WATER CULARLY HE DEF E S. PAR I BINETS 1960 ETR 2 HAF OFF CONTAIN GERATOR C REFR File April 28 June 12, 1962 United States Patent Ofiice 3,038,772 Patented June 12, 19 82 ARRANGEMENT FOR DRAINING OFF THE DE- FROSTING WATER IN REFRIGERATING CON- TAINERS, PARTICULARLY REFRIGERATOR CABINETS Georg Schiifer, Wiesbaden, Germany, assignor to Gesellschaft fiir Lindes Eisrnaschinen Aktiengesellschaft, Hollriegelskreuth, near Munich, Germany, a company of Germany Filed Apr. 28, 1960, Ser. No. 25,341 3 Claims. (Cl. 312-229) This invention relates to containers for refrigerating and/ or freezing goods that are perishable at room temperature, especially foods, and for the storage of such refrigerated or frozen goods. It refers particularly to refrigerator cabinets, refrigerators, refrigerating and freezing chests, community refrigerating and freezing installations and the like. The invention deals particularly with the task of flawlessly draining off of the defrosting water and the prevention of moistening of the heat-insulating material.

The defrosting water is known to flow down along some internal wall or internal surface of a refrigerating container of the mentioned type, and generally collects in a channel which leads the collected water to the outside. Those walls, floor parts and the collecting channel and discharge line to the outside that may be present must be packed water-tight against the heat-insulating material, so that the latter does not absorb any moisture and thereby sacrifice its heat-insulating effect. Sheet metal inserts, which-aside from their edgesare absolutely water-tight and water vapor-tight, have mostly been used for this purpose until the present. The suggestion has also been made to lacquer the entire internal walls of such a container. This suggestion, however, has not been realized-at least, in those refrigerating containers which consist, at least internally, entirely of foamed synthetic heat-insulating substance, perhaps as a self-supporting structural elementfor the reason that no lacquer has been known which would adhere to such a material.

Beyond this, the invention is predicated on the realization that an absolutely moisture-tight surface insulation of the internal walls of refrigerating and freezing containers is not desirable because in the course of a prolonged period an absolute sealing of the heat-insulating material against moisture is not possible anyhow, and consequently the moisture content in the heat-insulating material increases steadily in the course of time, without any possibility for the moisture content forming in it to evaporate.

For this reason it was first desirable to insulate not all run-off surfaces, but only those needed for the defrosting Water, against the passage of moisture. But it was found that moisture islands, which can never be fully dried out again, form in the insulating material even behind such surfaces.

The object of the present invention consequently consists of providing measures by which the defrosting water is prevented from penetrating into the insulating material, at the same time insuring that the formation of moisture islands within the insulating material is nevertheless prevented. The problem to be solved consists in avoiding both the penetration of defrosting water into the insulating layer and also the accumulation of water vapor diffusing from the the surroundings into the insulating layer.

According to the present invention the stated problem is solved in that the internal wall of a refrigerating or freezing container is coated, preferably sprayed, at least at the places to be wet by the defrosting water, with a water-impermeable, but water vapor-permeable epoxy resin provided with polyester additions. Such a lacquer has the advantage of adhering firmly also to foamed polystyrol and not flaking off or becoming fluid at the low temperatures of for example 20 to 30 C. required for refrigerating and freezing containers, and moreover not being attacked by condensate water or frozen fog formation. This lacquer, consisting essentially of two components, is moreover very conveniently processable, since it hardens Without solvent.

The defrosting water, therefore, does not penetrate through this lacquer layer during the defrosting process, while on the other hand the moisture present in the insulating material parts which lie behind the lacquered surfaces evaporates during the refrigerating or freezing period because of its water vapor permeability, out of the insulating material into the colder internal cooling chamber and deposits there as frost. According to a special development of the inventive idea, this drying process is further increased during the refrigerating period in that the lacquer coating is provided at greater intervals with small holes, which are of a size such that the defrosting water because of its cohesion forms drops which do not pass through these openings, but that on the other hand the small openings permit an easier passage for the escaping water vapor.

These holes have an approximate order of magnitude of 1 mm. in diameter and preferably occur at relative intervals of the order of magnitude of 1 dm.

The outer walls of the refrigerating container according to the invention are expediently covered, in a manner known per se as densely as possible-that is, water-tight as well as water-vapor-tight-and especially so on the floor side of the container. The covering is expediently done by means of metal foil, for example aluminum foil, which is adhered to paper which in turn is adhered exteriorly on the bituminized lower side of the porous styrofloor of the container.

The side walls can, under certain circumstances, remain free as such, that is, consist of self-supporting foamed polystyrol, and are merely sheathed on the outside with light metal sheaths, for example plates of zinc-plated sheet steel, in that these sheet metal plates are suspended in holding devices provided in the synthetic and secured for example with interspersed ledges of synthetic.

A mode of execution of the arrangement according to the invention is represented by way of example in the drawing, namely in the form of a cross-section through a refrigeratingand freezing chest.

The entire shaded part 1 consists of foamed polystyrol. The floor is slanted on the inside in the known manner and carries the vaporizer 2 with the ventilator 3, by which the cold air is circulated. Through the slanting of the floor it is achieved that the defrosting water flows towards the middle during the defrosting period, and collects in the defrosting channel 4, which communicates with a discharge channel 5 provided at one or more places of the chest, which discharge channel leads to the outside and is represented with dashes in the dravw'ng. According to the invention the surface of the internal slanting bottom and of channel 4 is covered along the places indicated by dots and dashes, with a coating 7 of epoxy resin provided with polyester additions. The channels 5 consist of simple tubes formed of synthetic plastic material. On the outside the floor is covered from below with an adhered layer of metal foil indicated by the dots 6. An end framing member of the chest is indicated at 8.

Advantageously, the exterior walls of a refrigerating container whose walls are composed of foamed heat-insulatingand, preferably, self-supporting-synthetic material such, for example, as foamed polystyrol, and an interior wall of which is coated, at places to be wet by defrosting water, with a water-vapor-permeable but water-impermeable lacquer composed of a polyester-modifled epoxy resin, may be so formed as to provide exterior recesses or similar holding devices therein or thereon for securing edges of sheets of sheathing material (e.g., synthetic plastic material, or sheet metal such as zinc-plated sheet steel, or the like) used as exterior covering of the refrigerating container. Such exterior covering material desirably provides a sheathing of the container which is both water-tight and water-vapor-tight.

The referred-to coating lacquer preferably has the following composition:

60% polyglycidyl ester (also known under the name Epoxy lacquer) having an epoxy value of 0.5 to 0.7 and 40% hardening agent which, in the present instance, consists of compounds containing aminoor carboxylor hydroxyl groups and which is, in particular, a cycloaliphatic polyamine.

The hardening agent serves to form cross linkages between the molecules, i.e. to form an interlacing of the lacquer with the carrying agent, specifically with the polystyrol.

I claim:

1. in a refrigerating apparatus having a refrigeration chamber formed of foamed heat-insulating material with an at least partly lacquered internal wall, an area of said internal wall being normally subject to being wetted by defrosting water, the improvement which consists in that at said area said internal wall is provided with a coating layer of a coating composition consisting essentially of polyester-modified epoxy resin said layer being water vapor-permeable but liquid water-impermeable.

2. In a refrigerating apparatus having a refrigeration chamber formed of foamed heat-insulating material said chamber having a bottom Wall and a defrosting water discharge channel therein said bottom wall sloping toward said channel, the improvement which consists in that the surface of said sloping bottom wall and of said discharge channel is provided with a coating layer of a coating composition consisting essentially of a polyester-modified epoxy resin said layer being Water vaporpermeable out liquid water-impermeable.

3. Arrangement according to claim 1, characterized in that the lacquer coating is provided, at regular intervals, with small holes which holes exhibit opening diameters of the order of magnitude of 1 mm, and occur at relative intervals of the order of magnitude of 1 dm.

References Cited in the tile of this patent UNITED STATES PATENTS 2,016,429 Hayden Oct. 8, 1935 2,767,558 Wallenbrock Oct. 23, 1956 2,770,406 Lane Nov. 13, 1956 2,908,602 Collardeau Oct. 13, 1959

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