Electrical insulating medium

Application filed June 3, 1920. Serial No. 386,193.

To all whom it may concern:

Be it known that I, Willis W. Hale, citizen of the United States, residing at Cleveland, in the county of Cuyahoga and δ State of Ohio, have invented certain new and useful Improvements in Electrical Insulating Mediums, of which the following is a specification.

The present invention relates to electrical 10 insulating mediums, and has for its object to provide a novel electrical insulating substance which is a good conductor of heat and which can accordingly be used to great advantage in the manufacture and constructs tion of electrical heating and cooking appliances.

Further objects of the invention are to provide a. heat, conducting electrical insulating substance which can be produced at a 20 comparatively small cost, which can be handled and worked in the same manner as any insulating medium, which will not break down under the action of the electric current, and which is an effective 25 and dependable electric insulator.

The invention is explained more fully in the following description, and in connection therewith reference is to be had to the accompanying drawings, in which:—

Fig. 1 is a perspective view of several superposed thicknesses including outside sheet metal plates and inner insulating thicknesses which embody the invention and are utilized to insulate an electric resist35 ance wire from the sheet metal plates, portions being broken away and shown in section.

Fig. 2 is a perspective view showing this same assemblage of elements as reversely 40 bent back and forth to provide a portion of an electric heater, portions being broken away and shown in section.

Corresponding and like parts are referred to in the following description and indi45 cated in all of the views of the drawing by like reference characters.

In carrying out the invention some suitable electrical insulating medium having a porous or fibrous body or otherwise adapted 50 to be treated with a liquid is saturated with a solution of silicate of soda or water glass (NaSiO₂), and then permitted to become thoroughly dry. It has been found in practice that an electrical insulating medium 55 which has been thus treated with silicate of soda retains practically all of its electrical insulating properties although it is thereby rendered a good conductor of heat. The original insulating medium thus treated may be asbestos, fire clay, or any other analogous 60 insulating material, and the finished product is very useful in the construction of electric heaters and cookers where it is necessary to insulate the electric current and at the same time conduct the heat away from the resist- 65 ance element as expeditiously and with as little retention as possible.

In the drawings, the reference character A designates a sheet of electrical insulating material, such as asbestos, which has a 70 porous or fibrous formation and can accordingly be readily saturated with a liquid medium. Preparatory to use this sheet A is treated with a solution of silicate of soda. A resistance wire 1, which may have any 75 suitable composition, may be interposed between two of these insulating sheets A, and the insulating sheets in turn interposed between sheet metal plates 2. In Fig. 2 the sheet metal plates are shown as reversely 80 curved back and forth, although it will be understood that this is merely illustrative of one out of many practical uses for the invention. The insulating sheets A form effective electrical insulators for the resist- 85 ance wire 1, although the heat is readily conducted to the sheet metal plates 2 which have a large superficial area and quickly radiate the heat in the desired manner.