DE936985C - Thermal insulation, especially for refrigerators - Google Patents

Description

Thermal insulation, particularly for refrigerators The invention relates to Insulations used between the inside and outside walls of a refrigerator especially insulations that use a gas as an insulating medium.

Insulations are known which consist of a sealed element exist, which with a gas, for example difluorodichloromethane, with less Thermal conductivity as air and further with an inert material, for example Glass wool, is filled. The aforementioned inert material takes on the task of to counteract heat transfer through radiation or convection.

It is also known a thermal insulation, which consists of two the shell forming containers laid one inside the other consists of thin, flexible metal plates, between which a filling compound is enclosed and which form a hermetically sealed one Space are connected. The thermal conductivity of this insulation is determined by an evacuation of the isolation room is reduced. In doing so, those acting on the walls from the outside Pressures absorbed by the filling compound.

The invention has the task of creating an insulation which is manufactured separately from the cooling equipment for which it is intended and which can then be stored in any way and used in manufacture can.

According to the invention, this object is achieved by an insulation which is characterized by that the sealed element in shape a double-walled bag is executed, of which one layer, for example a copolymer of vinyl chloride and vinylidene chloride, impermeable to air and moisture and the other layer, for example a polyester of ethylene glycol and terephthalic acid or polystyrene, which is impermeable to the enclosed gas, and that in addition to this element between the walls one. further insulation is arranged, the consists of an elastically deformable material.

The invention is described in detail below on the basis of an exemplary embodiment described and illustrated with reference to the drawing. In the drawing represents Fig. I is a perspective view of a conventional household refrigerator with a Thermal insulation according to the invention, in which some parts have broken out; Fig. 2 is a partial section through a side wall of the refrigerator according to the invention on a larger scale; Fig. 3 is a piece of that for the covering of the thermal insulation material used substance; Fig. Q. is another piece of this material in the cut.

The illustration shows the thermal insulation according to the invention in use on a household refrigerator, but it can also be successfully used for other purposes, where good thermal insulation is important.

The refrigerator shown in Fig. I consists of an outer wall io and an inner wall 12, between which hermetically sealed, with insulating material filled balloons 14 and insulating plates 16, which are not covered, are inserted: The balloons 14 consist of layers 18 and 2o, which are sealed at 24 and which are filled with glass fiber insulating material26 and a gas which is a has low thermal conductivity, e.g. B. difluorodichloromethane. Tests have shown that by replacing the air in the isolation balloons with difluorodichlormethane a considerable reduction in heat transfer through the insulation is possible. The insulating capacity of insulation in balloons can be roughly calculated on the basis of this Increase double.

The difficulty that arises is the escape of difluorodichloromethane from the balloons and its replacement by air.

Further, it is not only necessary to find a material that prevents escape, but it is also necessary to ensure that the insulation is not affected by changes in atmospheric pressure will. Since fridges are partly at sea level or almost at sea level Sea level and others at altitudes of several thousand meters or transported above such heights would be at sea level balloon filled with difluorodichloromethane might burst at such great heights. This difficulty is overcome by the fact that between the walls of the refrigerator and leaving the balloons some space of limited extent the balloons allowed.

As can be seen from FIGS. 1 and 2, this space becomes with Compressible or loose insulation material that is not enclosed in balloons is. This allows expansion or contraction of those contained in the balloons Insulation .14 without exerting excessive * pressure on the walls. The concentration the fiberglass insulation 16 is approximately 5. 7031 kg / m2 (e.g. 25 pounds per cubic foot), while the density of the fiberglass insulation in the balloons is preferably approximately 7,1093 kg / m2 (3.75 pounds per cubic foot).

Because the balloons are made of layered material, the diffusion of gas through the balloon material is significantly reduced.

The layers are preferably bonded to one another by an adhesive layer 32, for example based on rubber, or made of a vinyl chloride bonded by the possible holes 30, as shown in Fig. q. are indicated to be closed. the The likelihood that two holes will lie straight on top of each other is very high small amount. It is much more likely that, as in Fig. 3 and q. indicated are offset from one another; thereby making each layer those present in the other layer Closes holes.

A copolymer of vinyl chloride or vinylidene chloride, such as. B. that Known under the name "Saran", it has certain properties that make it suitable for use make one of the layers appear particularly suitable. It can be easy can be sealed using heat and is very gas-impermeable. Copolymers of this type can withstand the very low temperatures that occur in refrigerators excellent.

The outer layer of the balloons is preferably made from a polyester made of ethylene glycol and terephthalic acid, the z. B. as »Mylar« in stores and that is about eight times less gas-permeable than "Saran". At higher Temperatures, "Saran" is plastic, while "Mylar" is not plastic, so that a combination of the two gives very satisfactory results.

Another material that will be used for the balloon layers is the polystyrene, which is almost impermeable to difluorodichloromethane, but while it lets air through and that in connection with another material, e.g. "Saran," which is impermeable to air.

The layers preferably become 0.02 mm (.ooi inches) or thicker chosen. The thicker the layers, the lower the leakage loss; but Because of the high cost of the material, the thickness of the layers should be as small hold as possible. -.

Instead of using individual layer sheets, the material can also be layered by spraying on, in other words: the Way of obtaining a multilayer material can be different.

Due to the special combination of materials and the Using gas, a surprisingly good insulation is achieved, which is their insulating Retains properties for a long time without being affected by temperature or pressure fluctuations to be influenced.

Claims (2)

PATENT CLAIMS: i. Insulation to insert between the interior and the outer walls of a refrigerator, consisting of a sealed element, which with an inert material, such as glass fibers and a gas with lesser Thermal conductivity as air, such as difluorodichloromethane, is characterized by that the sealed element (i4) is designed in the form of a double-walled bag is, of which one layer, for example a copolymer of vinyl chloride and Vinylidene chloride, impermeable to air and moisture and the other layer, for example a polyester of ethylene glycol and terephthalic acid or polystyrene; is impermeable to the enclosed gas, and that in addition to this element (i4) between the walls (io. 12) a further insulation (i6) is arranged which consists of an elastically deformable material. 2. Insulation according to claim i, characterized in that the layers (i8, ao) are connected to one another via their superposed surfaces with the aid of an adhesive (32), for example vinyl chloride. Cited publications: German patent specifications No. 678 69o, 665 319, 661 688, 653 374.