US2489190A - Electric heating element - Google Patents

Description

Nov. 22, 1949 .1. LELONG 2,489,190

ELECTRIC HEATING ELEMENT Filed July 12, 1946 Patented Nov. 22, V1949 ELECTRIC HEATING ELEMENT ll'ean Lelong, Claye Souilly, France, assignor to Procedes Sauter, Paris, France, a. corporation of France Application July 12, 194s, serial No. 683,110 In France J uly 13, 1945 3 claims. (cram-19) The present invention concerns the construction of electric heating elements for all purposes adapted in general to all cooking and heating apparatus, and more particularly radiant elements for the arches of electric furnaces, grills and radiators.

Generally, known heating bodies of such apparatus present the following disadvantages: They are heavy; by their arrangement they reduce the useful height of the furnaces, and they often necessitate a complicated system of connections: pins, recesses, insulating members and so on.

The present invention avoids these disadvantages by constructing the heating body of a number of indepedent heating elements, directly connected together and adapted to be fitted in grooves formed in the upper part of the furnace. Each heating element is itself constructed of easily detachable parts, which facilitates repair or replacement of the parts. In case of a failure in the operation of a furnace, it is sufficient to replace the faulty element and not the whole heating body.

The present invention has for its object to provide an electric radiant heating element having a resistance located in recesses formed in an insulating refractory lining disposed in a metal casing, characterised in that the refractory lining is constituted by a series of detachable abutting plates, the whole being held in the casing by an insulating member fixed on the latter and adapted to carry the connecting terminals of the resistance.

The annexed drawing shows a preferred embodiment of the present invention. It shows a bar unit, but it is obvious that the present invention is not limited to this straight form and the heating element could be of any other form suitable for the heating zone to be obtained.

In the drawing, Fig. 1 is a cross-section of the heating bar.

Fig. 2 is a plan view.

Fig. 3 is a side view partly in longitudinal section.

Referring to the drawings, the heating element forming the subject of the present invention, is of the type in which the heating resistance 'is exposed and radiates directly over the areas to be heated. The heating resistance 2 which may advantageously be constituted by a resistance wire, preferably of circular section and helically wound, is located in insulating refractory parts 3, which support the wire while leaving it exposed, at least partly, permitting it to radiate its heat 2 directly and protecting it against any accidental contact.

Any number of longitudinal recesses 9, arranged to support the resistances, may be used. However an even number is recommended, because it permits of arranging all the connecting terminals 5 at the same one end of the heating element. The construction comprising two recesses or grooves is the simplest and the most advantageous. These recesses are of a reduced width near the surface of the refractory material so as to hold the resistance in place.

The insulating members supporting the resistances are detachable plates 3 of the same cross section and placed end to end. The heating element may comprise one or more of them. The optimum number will be determined by a judicious compromise between the two following extreme constructions; either a small number of long parts which are diicult to manufacture, or a large number of small parts which are easier to make, but the large number of which leads to a higher total cost.

The insulating refractory parts are assembled by a metal cover or casing l, made preferably of rustless steel, which can advantageously be constructed as shown in Fig. 1: the casing l has the form of a channel the upper edges of which are bent over at right angles to prevent the plates from falling out when the bar is mounted, for example, in the arch of a furnace. These refractory and insulating plates are mounted by passing them in at one end, and the unit is held in'place by a special insulating member 4 carrylng the connecting terminals which member 4, as shown in Fig. 3, has a depending portion extending substantially beyond and below casing l and terminal s is on its outer free edge, and the insulating member 4 can be held tight to the casing by any simple device, for example, a screw 5, which passes through an aperture in flat tongue I0, which tongue is an integral eX- tension of metal casing I and passes through a narrow slot in insulating member 4. The screw 5 is bolted tightly on tongue it by a nut, and is positioned on tongue I0 to hold the end of casing I, and the small plates 3 contained therein, from falling away from the opposite face of insulating member 4. The tongue Il) also constitutes a convenient handle by which the operator can grasp the casing containing the plates and heating elements when introducing the same into the furnace.

At the other end of the element is provided a suitable device permitting the resistance wire to pass from one groove into the following groove: for example, an insulating part 'I provided with a recess which provides for the insulating, the protection and the passage of the resistance, can be used. As shown, the casing I has at its end opposite insulating member 4, an integral end Wall against which terminal insulating part l bears.

Finally, the metal casing may advantageously be provided, at the end opposite the connecting terminals with a more or less flexible tongue 8 such as a resilient blade which provides for the mounting and locking in position of the heating element in a furnace.

As shown in Fig. 3, the tongue 8 is preferably formed as an integral continuing part of the end wall of metal channel casing I and bears against the adjacent insulating piece 1. As shown, the end wall of the casing may be cut open adjacent the tongue.

I claim:

1. In a radiant electric heating element, a metal casing, said easing being a channel member of rectangular cross section open on one side and provided with inturned flanges on said open side, said channel member being open at one end and having at its other end an integral end wall at least partially closing said channel member, an insulating refractory lining contained within said casing and comprising a series of adjoined small plates, said plates being provided with grooves, an electrical resistance element contained within said grooves and having both of its terminals at the same rst end of said casing, an insulating piece xedly attached to said casing and abutting the terminal one of said plates, connecting posts on said insulating piece to which the terminals of said heating element are connected, and a re silient blade carried by the end wall of said casing opposite said insulating piece and extending outwardly and axially of said casing and adapted to engage a furnace wall, whereby said plates are held between said insulating piece and said blade.

2. In a radiant electric heating element, a metal casing, said casing being a channel member of rectangular cross section open on one side and provided with inturned flanges on said open side, said channel member being open at one end and having at its other end an integral end wall at least partially closing said channel member, an insulating refractory lining contained within said casing and comprising a series of adjoined small plates, said plates being provided with grooves, an electrical resistance element contained within said grooves and having both of its terminals at the same first end of said casing, an insulating piece fixedly attached to said casing and abutting the terminal one of said plates, connecting posts on said insulating piece to which the terminals of said heating element are connected, said insulating piece having a depending portion eX- tending substantially beyond said casing and said connecting posts being positioned on the outer free edge of said depending portion substantially offset from said casing, and a resilient blade integral with the end wall of said casing opposite said insulating piece and extending outwardly and axially of said casing and adapted to engage a furnace Wall, whereby said plates are held between said insulating piece and said blade.

3. In a radiant electric heatingr element, a metal casing, said casing being a channel member of rectangular cross section open on one side and provided with inturned iianges on said open side, said channel member being open at one end and having at its other end an integral end wall at least partially closing said channel member, an insulating refractory lining contained within said casing and comprising a series of adioined small plates, said plates being provided with grooves, an electrical resistance element contained within said grooves and having both or its terminals at the same 'first end of said casing, an insulating piece lixedly attached to said casing and abutting the terminal one of said plates, connecting posts on said insulating piece to which the terminals of said heating element are connected, the end wall of said casing opposite said insulating piece having an open portion and having an integral resilient blade portion adjacent said open portion, said blade portion extending outwardly and axially of said casing and being adapted to engage the furnace wall and bear against the adjacent terminal plate within said casing, whereby said plates are held between said insulating piece and said blade portion.

JEAN LELONG.

REFERENCES CITED The following references are of record in the fLle of this patent:

UNITED STATES PATENTS Number Name Date 1,549,773 Hynes Aug. 18, 1925 1,680,404 Woodson Aug. 14, 1928 2,271,978 Hjelmgren Feb. 3, 1942 FOREIGN PATENTS Number Country Date 798,633 France May 22, 1936

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