US1892298A - Electrical heating element - Google Patents

Description

Dec. 27, 1932. G. BRAY ELECTRICAL HEATING ELEMENT Filed Jan. 28, 1931 INVENTOR l atented Dec. 27, 1932 1 UNITED STATES PATENT OFFICE GEORGE BRAY, OF LEEDS, ENGLAND, ASSIGNOR TO GEO. BRAY & COMPANY LIMITED, 01

. LEEDS, ENGLAND ELECTRICAL HEATING ELEMENT Application filed January 28, 1931, Serial No. 511,909, and in Great Britain February 8, 1980.

This invention relates to electrical heating elements of the type comprising a resistor enveloped in a mass of refractory material enclosed within a shallow sheet metal casing made in two parts connected together by spinning or flanging the edge of one over the edges of the other.

It is found that when in use for instance in hot plates used for cooking or boiling there is a liability of moisture creeping past the joint and deteriorating the interior refractory insulating material.

In the known form of heating element one part of the sheet metal casing has been of channel section and the other part flat or substantially flat over which the ed es of the channel are deflected or flanged, ut it has been found that such fiangin does not prevent liquid spille on the upper surface from soaking into the heating element which is assisted by capillary orces which are set up between thetwo metal surfaces.

The inventioncomprises a metal casing for the interior insulating refractory material of two channel shaped parts one fitted within the other, the flanges of the outer channel being partially turned over the flanges of the other andextended downwards to form drip edges.

The heating element which may be either annular as shown or of straight or strip form is constructed with armetal casing A enclosing a resistor element B embedded in a .refractory material C the resistor element B being of known construction and the refractory material C of'known composition.

of the edges According to the invention the sheet metal casing A is made of two channel sections, the lower one forming a container which is filled with the refractory material C compressed around the electric resistor element B, is fitted into the upper.

The upper or outer channel is dee er than the inner channel and the sides or anges a thereof pro'ect downwards below the lower channel a dlstance substantially equal to the de th of the casing.

he projecting sldes a are turned inwards at a to embrace the underside of the lower channel to hold the two channels together leaving a downwardly projecting flange or menzber a to direct liquid away from the ]01I1 Terminals D are inserted in the casing A in known manner to connect with the resistor elements B and bifurcated or other rivets E or screwed studs are attached to the inner or lower channel member by which to aflix it to a support.

This construction of double walls to the sides of the sheet metal casing and the annular depending drip edge a gives rotection agalnst creepage and the entry of oreign matter 1nto the interior. The depending edges gave a stiffer unit and the incomplete turnover at a avoids cracking of the metal.

What I claim as my invention and desire to protect by Letters Patent is 1. A casing for an electric heating element of the type referred to comprising an upper channel s aped part, a lower channel shaped container to fit inside the upper part to form a double wall around the periphery and a downwardly projectin continuous flange on the upper part exten ing substantially the depth of the casing below the lower edge of the lower channel.

2. A casing for an electric heating element of the type referred to comprising an upper channel shaped part, a lower channel shaped "container to fit inside the upper part to form a double wall around the periphery, a

flanged-in portion on the upper art to em- I brace the underside of the lower c annel and a downwardly projecting continuous flange on the upper part extending substantially the de th of the casing below the lower edge of the ower channel.

3. An electric heating element comprisin the combination of an inner channel shape container, refractory material therein, a resistor element embedded in the refractory material and an outer and upper channel shaped part to close the container, a flanged-in portion on the upper part to embrace the underside of the lower channel and a downwardly projecting continuous flange on the u per part extending substantially the depth 0 the container below the lower edge thereof.

In testimony whereof I have hereunto set my hand this 9th day of Januar 1931.

GEORG BRAY.

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