DISPLACING AIR IN A REFRIGERATOR
Publication Date: 2010-Aug-31
The IP.com Prior Art Database
The present invention provides a method for displacing air in a refrigerator to allow for the insertion of polyurethane foam insulation. The method utilizes Hydrogen or Helium gas to reduce the formation of air voids in the foam and allows for an even foam flow within a gap between the outer case and the inner liner of the refrigerator. The method improves the efficiency of the foam insulation and allows for the maintenance of cooler temperatures within the refrigerator.
DISPLACING AIR IN A REFRIGERATOR
The present invention relates generally to appliances, and more particularly to a method for displacing air in a refrigerator to allow for the insertion of polyurethane foam insulation.
Conventional refrigerators are known to comprise several basic components including an outer case, an inner liner and insulation inserted in a gap between the outer case and the inner liner. As is known, the inner liner defines at least one interior compartment which may be used to store items to be cooled. The at least one interior compartment may be accessible through at least one compartment door. In general, the outer case is made of metal, whereas the inner liner is made of plastic. The outer case is normally formed by folding a sheet of a suitable metal material into an inverted U-shape to form a casing having a top, a bottom and side walls.To make the inner liner, a thick piece of plastic designed to fit within the metal outer case has its outer edges clamped and is then heated. The hot plastic is next pulled by vacuum into a mold and cooled. After trimming, the resulting inner plastic liner is inserted into the outer metal case. To improve the performance and efficiency of the refrigerator, insulation, in the form of a polyurethane foam, is inserted in the gap between the outer case and the inner liner.
Polyurethane foam is an insulation material that is commonly used in conventional refrigerators. Foam insulation, measured by foam insulation K factor, is used to enhance appliance efficiency by significantly reducing thermal losses. Additionally, foam insulation reduces the refrigerator weight by providing good structural support so that less steel is required. Spray methods and other techniques have been employed to insert the polyurethane foam in the gap between the outer case and inner liner of the refrigerator. Once inserted in the gap, the foam is heated in an oven and expands to add rigidity and insulation to the at least one interior compartment.
One problem with polyurethane foam is that air voids, which negatively affect insulation and appliance efficiency, are commonly formed when the foam is inserted into the refrigerator. The presence of air in the gap between the outer case and the inner liner creates numerous voids as the insulation foam is inserted and allowed to expand. The air voids also affect the consistency and stability of the foam and cause an uneven foam flow within the refrigerator. Many techniques have been employed to eliminate voids in polyurethane foam, including vacuum casting and compression molding. Alternatively, vents and ports have been applied to evacuate air from a mold. Although some techniques have been proven to be effective in reducing air entrapment, they are also known to be costly.
It would be desirable to create a cost-effective method for inserting foam insulation into a refrigerator that reduces foam voids and provides an even foam flow within the gap between the...