Improvements in Electric Heating Apparatus.
Year: 1891

page_text: Date of Application, 24th Mar., 1891-Accepted, 25th Apr., 1891
COMPLETE SPECIFICATION.
Improvements in Electric Heating Apparatus.
I, MARK WESLEY DEWEY, of 150, North Salina Street, in the City of
Syracuse, in the County of Onondaga, in the State of New York, United States
of America, Electrician, do hereby declare the nature of my invention for
"IMPROVEMENTS IN ELECTRIC HEATING APPARATUS," and in what manner
the same is to be performed, to be particularly described and ascertained in
and by the following statement :-
My invention relates to electric heating apparatus. wherein the resistances or
heat-developing electric conductors formed of platinum or other metal are of com-
paratively small size, raised to a high temperature by the passage therethrough of
an electric current, and covered, enveloped or surrounded by a refractory material
to prevent the temperature of the conductors being raised to a point sufficiently
high to melt and destroy them, and, to serve to conduct the heat therefrom, with
sufficient rapidity to the case, from which it is radiated.
The object of my invention is to provide a material with which to surround or
cover the resistances or wires, that will not conduct electricity, will conduct the
heat slowly, but with sufficient rapidity to prevent the burning of the wire, and to
provide a material of sufficient flexibility and elasticity to maintain the same in close
and constant contact with the conductor during all temperatures.
It
well known that a conductor varies in size in both its cross section and
length, according to the volume of current flowing through it, and. in. order to
conduct the heat from the conductor in any and all conditions, I provide an elastic
fibrous material that will maintain perfect and constant contact with said conductor
at all times, and that will make it impossible for the conductor to burn out by a
sudden rise of, temperature.
Referring to the drawings,
Fig. 1 shows a plan of my electric heater with one heat developing conductor
enveloped or covered by a loose fibrous refractory material,
Fig. 2 shows a plan of a heater having several heat-developing conductors con-
nected in parallel and surrounded by the same refractory material,
Fig. 3 is a side view of the heater with side of case removed, and showing ribs
on top and bottom of case,
Fig. 4 shows side of case with cover removed to show elasticity of the
refractory material within, the latter having raised of its own accord above the top
edge of the metallic case upon the removal of cover, and
Fig. 5 is an end view of a heater with end removed to show the resistance or
beat developing conductor in several layers, one above the other, with metallic
plates between the layers to aid in conducting the heat from the refractory packing
material to the case of the heater.
Referring specifically to the drawings, Figure 1 shows a resistance or heat-
developing conductor-A-formed of platinum, iron or other suitable material in
a serpentine form and supported by pins or hooks--of porcelain or other
suitable material. The portions bent around the hooks are preferably of greater
cross section than the other portions of the wire to prevent excessive heating of
the wire at these points. After the wire is suitably supported by the hooks-b-
within the metallic case-a,-the wire is covered, enveloped or surrounded with
fibrous asbestos-B-or other fibrous refractory material. The bed for the con-
luctors may be formed partly of a solid slab of refractory material as fire-brick
or plaster-paris, but this should not come in contact with the wires as it is not
yielding or elastic. --are the terminals of the heater.
If the pins or hooks-b-are made of metallic material, they are insulated from

page_text: the case by strips of insulation-d-d. The same letters of reference are used for
the other figures.
In Figure 2 the beat developing conductors are connected in parallel to
metallic strips-e-e-on each side of the interior of the case and insulated
therefrom by strips of insulation--d.
The case in Figs. 3, 4 and 5 is preferably ribbed on the exterior to aid in
radiating the heat therefrom, but may be corrugated or roughened in any suitable
manner for the same purpose.
Fig. 4 represents the cover removed from the case-a-to show the elasticity of
the fibrous packing material, it having raised slightly above the top edge of the
The cover, and screws employed for fastening it to the case, serve as a
binding device to maintain close, constant and continuous contact between the
fibrous refractory material and the conductor or conductors.
case.
Fig. 5 shows the resistance or heat developing conductor-A-arranged in
several planes or layers, with loose metallic plates--between the layers with
their edges preferably in contact with the interior sides of the case-a.
The metallic plates--are separated and insulated from the conductor or con-
ductors by the fibrous material which completely envelops said conductor or
conductors.
g are the feet of the heater which raises it above the floor to increase the
radiating surface thereof.
I do not limit myself to the metallic case as it may be made of earthenware.
The source of electric current for the heater may be a battery, dynamo or other
suitable source, well known, and not necessary to be herein shown and described.
Having now particularly described and ascertained the nature of my said
invention, and in what manner the same is to be performed, I declare that what
I claim is :-
1-In an electric heating apparatus, a suitable metallic case, one or more
resistances or heat-developing electric conductors within said case and formed in
layers, metallic plates between the layers, and a fibrous refractory material in
contact with and enveloping or covering the conductor or conductors, and means to
maintain said material in close and constant contact with the said conductor or
conductors.
2-In an electric heating apparatus, a corrugated or ribbed metallic case, one or
more resistances or heat-developing electric conductors supported in said case, and
a fibrous refractory material enveloping or covering the conductors and in a con-
tinuous contact with the same.
1
Dated this Fth day
MAUTOLL TOUTO
120CU
VILIO TU CYCL BAUTCH TUL.
MARK WESLEY DEWEY.
Haseltine, Lake & Co.,
45, Southampton Buildings, London, Agents for the Applicant.