HEAT-INSULATING MEANS FOR REFRIGERATOR OR FREEZING CHAMBER

摘要

PURPOSE: To form vacuum heat insulation which is invariable over a long period by inserting a heat insulating material having a specific closed cell structure into a hermetically closed space comprising diffusion-tight plate members, and evacuating the hermetically closed space by means of a vacuum source whenever necessary until a predetermined vacuum pressure is reached. CONSTITUTION: In a refrigerator, a plurality of wall parts 10 surrounding a cold room comprise wall parts having outer and inner plate members 11, 12 and a hermetically closed space 13 filled with a heat insulating material is defined therein. The heat insulating material used is at least partly comprised of a closed cell structure produced by foaming polyolisocyanate with a gas such as carbon dioxide which has such properties that it can diffuse through the cell structure with a velocity that is at least five times faster than air. The hermetically closed space 13 is evacuated via an evacuation conduit 17 by actuation of a vacuum pump 18 and operation of the vacuum pump 18 is stopped by an electric control means 20 when a sensor 19 detects that a predetermined vacuum pressure has been reached.