Patent ID: 6654551
Filing Date: 2003-11-25
Classification: F24D,H05B,Y02B

Abstract:
Heating device with an electric resistance placed inside a sandwich-type hermetically sealed structure, comprising two rigid elements one of which acts as a heating plate,characterized in that the electric resistance is a serpentine consisting of a thin strip of highly conductive material of a constant width, the ratio between width and thickness being substantially 10 to, formed of a series of U-shaped bends, crossed by a series of parallel transversal strips of mica said serpentine being lodged between two sheets of mica, inside the chamber of a rectangular substantially box-shaped panel resulting from a basic tray-shaped structure and from one or more similarly tray-shaped closing structures, inserted side by side within said basic structure, the external length of said dosing structures corresponding to the internal length of the basic structure less the width of a rectangular supporting plate, by means of hermetically sealed bushes, to the electric feed wiring of the serpentine, the overall external width of said closing structures, placed side by side, corresponding to the internal width of said basic structure and the external height of each of said closing structures to the internal height of said basic structure less the overall thickness of the serpentine, of the sheets and of the transversal mica strips, each formed of a rectangular metal sheet bent at 90Â° at the four sides with continuous weldings being done on all edges of the basic structure and closing strictures, and on the upper face of said rectangular plate, matching and substantially lying on one and the same geometrical plane, the effect of all this being to provide a hermetic seal for the chamber of the panel and a free volume insufficient for receiving a quantity of inflammable gaseous substances that could lead to a deflagration.