Improvements in Electric Heating Apparatus.
Year: 1893

page_text: Date of Application, 28th Mar., 1893-Accepted, 17th June, 1893
COMPLETE SPECIFICATION.
Improvements in Electric Heating Apparatus.
I, MARK WESLEY DEWEY, of Kirk Block, corner of South Salina and West
Fayette Streets, City of Syracuse, in the County of Onondaga and State of New
York, United States of America, Electrician, do hereby declare the nature of my
invention, 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 resistance or heat
developing conductor is of small size or cross-section.
The object of my invention is to provide a simple, cheap, durable and efficient
electric heater that will have a large radiating surface and yet occupy a small
space.
My invention consists, broadly, in the combination of a thin body of suitable
material, notches in one or more of its edges, and a wire forming part of an electric
circuit wrapped around said body, across both faces thereof and lying in said
notches.
My invention also consists in the combination in an electric heater of a support,
a plate on the support, saddles of insulating material on two edges of the plate, and
a resistance-conductor wound around the plate and saddles.
My invention consists also in the combination in an electric heater of a support
consisting of a case or enclosure divided longitudinally in two parts, supports or
holding devices on the interior of the case, a plate or thin body held by said
devices parallel to and in the plane of the meeting edges of the parts of the case, a
resistance-conductor wound around the plate, supply conductors leading through
the case to the terminals of said resistance-conductor and means to hold the parts
of the case together and the plate or thin body in position.
And my invention consists also in certain other combinations of parts hereinafter
described and specifically set forth in the claims.
By my arrangement I am enabled to use less expensive wire having a lower
resistance, a greater radiating surface, and a larger gauge than the wire usually
employed and to confine it to a small space without the liability of a short circuit
being formed by contact between two convolutions thereof.
When the heater is limited in size German silver wire may be used or other high
resisting material, and when irou is used it may be galvanized or coated with copper
or other suitable material to keep it from rusting when not in use and exposed to a
humid atmosphere.
In the accompanying drawings, Figure 1 is a side elevation of the complete
heater, Figure 2 is an end elevation, Figure 3 is a top view, Figure 4 is a view of
the heater with a half or one of the parts of the support or casing removed,
Figure 5 is a cross section on line x, x, of Figure 1, Figure 6 shows a side
elevation of the plate inside of the case with the saddles on the edges and the
resistance-conductor partly wound around the same, Figure 7 is a cross section of
the plate, etc., on line y, y, of Figure 6, Figure 8 is a side elevation of one of the
saddles of insulating material enlarged, Figure 9 is a cross-section on line z, z, of
Figure 8, and shows also edges of plates both round and chamfered, Figure 10 is
an enlarged side view of a terminal fixed to a corner of a plate, Figure 11 is
another side elevation of the terminal with the plate and bushing in section,
Figure 12 is a plate without saddles and made of insulating material or metal
covered with insulating material, and Figure 13 shows a heater having a plurality
of plates arranged parallel side by side.
Referring specifically to the drawings, A represents the support, screen or case

page_text: holding and enclosing the plate and resistance-conductor. This case has a square
or rectangular shape and has perforations or slots a on the top and bottom to allow
the circulation of the air therethrough. The slots extend to and in the sides of
the case, those in the top being the longest. The top is the warmest part of the
heater, and therefore is provided with larger apertures to permit the heated air to
escape rapidly. The casing A is divided in the middle vertically and longitudinally
in two parts, one of the parts being of the same shape, but the reverse of the other
part.
The
Each part has a foot or leg a¹ at each end to raise it from the floor.
parts are held together by screws or bolts a passing through extensions on the
top and bottom of the parts. In the top of the case, at each end, between
the meeting edges is a hole with an insulating or porcelain bushing therein
for the supply conductors or terminals to enter. When the case is not made of
metal, which, however, is the material preferred, but of earthenware, as porcelain
or some other insulating material, the bushings will not of course be required.
B is the plate around which the resistance conductor or wire C is wound, and
which is supported, held and enclosed by the case A. The said plate may be of
metal, slate or porcelain or other suitable material. If the plate or thin body is
made of slate or porcelain or other insulating and heat-resisting material, saddles D
will not be absolutely necessary on the edges thereof, but said saddles are preferably
used even then in order to allow thin plates to be used so that the heater will be
light, to hold the wire a distance from the plates so that they will not be highly
heated, and so that the heat may radiate from all sides of the wire. When the
plate B is made of metal such as cast or sheet iron the saddles D are used to
insulate the bare resistance wire C from the plate and to hold the convolutions
apart or separated from each other. Said plate is supported in the center of
the case A parallel to and in the plane of the junction of the parts of the case
and extends the entire length of the case between its ends. The said plate
only comes in contact with the case at its ends where it is held by suitable
holding devices consisting of projections d at each corner of each part of the
case. When the plate B is placed in position and the parts of the case A are
fastened or clamped together by the screws a", the plate will be held firmly between
the said projections so that it cannot come in contact with the sides of the case.
The plates may be plain, perforated or ribbed as desired.
The saddles D on the edges of the plate B are U-shaped in cross-section and
made of porcelain, mica or other suitable vitrified or heating resisting material.
The porcelain saddles are moulded with notches in or teeth e on the sides or round
part to hold the convolutions of the wire C equal distances apart and to serve as a
measure and guide when winding the wire. The notches or spaces between the teeth
should be somewhat larger than the wire used.
The saddles D are preferably divided in sections and placed end to end, as shown
in Figure 6, as they are liable to warp when vitrified if made long.
The lower ends of the terminals or binding screws c for the heater are bifurcated
so that they may extend on both sides of the plate B. If the plate is made of
insulating material, a screw passed through a hole in plate and the bifurcated
end of the terminal will secure the latter to the plate, but if the plate is constructed
of metal as preferred, a bushing of porcelain or other insulating material is
extended through the plate and insulates the latter from the said terminal and screw.
The said screw not only serves to secure the terminal c to the plate B but forms a
binding screw for the terminal of the resistance-conductor. C.
Projections g may be formed on the two edges of a plate for the end saddles to
abut against, but this is unnecessary as the wire when wound around the plate and
saddles will hold the latter firmly in place.
In Figure 9 I have shown in dotted lines teeth e upon the sides of the saddles,
but I prefer to use only one row of teeth which are placed on the bend as shown
in full lines in the same figure. The edge of the plate can be made either round
or chamfered to fit the groove in the porcelain or said edge may be made flat with
square corners.

page_text: do not limit myself to plates with saddles for I can employ a thin slab of slate,
soapstone or terra cotta or many other kinds of insulating material may be used or
even metal when covered with an insulating material where the wire would come in
contact with the plate when it is wound thereon. Any enamel or glaze may be
applied to the plate for this purpose, that will resist heat and insulate the metal
plate from the wire. The slab B shown in Figure 12 is provided with notches or
indentations e in both of its side edges.
In Figure 13 a plurality of flat slabs B are supported within a casing side by
side, parallel, an equal distance apart and facing each other. The slabs are held
in a vertical position by notched or grooved strips secured to the interior of the
casing, the end edges of the slabs are inserted in the said notches or grooves. The
casing A is supported upon short legs and the bottom and top is perforated to allow
the air to circulate therethrough.
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 heater, a plate, saddles of insulating material on two edges of
the plate, and resistance-conductor wound around the plate alternately across
opposite planes thereof, but not in contact therewith, and a perforated case, as and
for the purpose described.
2-In an electric heater, a perforated case, a metal plate held at or near its corners
by the case, saddles of insulating material on two edges of the plate, and a resistance-
conductor wound around the plate alternately across opposite planes thereof but not
in contact therewith, as and for the purpose described.
3-In an electric heater, a perforated case, a metal plate held in said case, two
electric terminals or binding screws secured to but insulated from the plate, saddles
of insulating material on two edges of the plate, and a resistance-conductor wound
around the plate and saddles, but not in contact with the plate, as and for the
purpose described.
4 In an electric heater, a support consisting of a case or screen enclosing the
resistance-conductor, made in two parts, holding devices at each end of the case, a
body around which the resistance-conductor is wound between said holding devices,
apertures between the two parts of the case, and electric terminals connected to the
ends of the resistance-conductor and extending through the case between the two
parts thereof as and for the purpose described.
5-In an electric heater, a support consisting of a case or screen, enclosing the
resistance-conductor, made in two parts, perforations in the bottom and top of the
case, holding devices at each end of the case, a body around which the resistance-
conductor is wound between said holding devices, and electric terminals connected
to the ends of the resistance-conductor and extending through the case between the
two parts thereof as and for the purpose described.
6 In an electric heater, a metal plate, a perforation near the end of the plate, a
binding screw, a yoke secured thereto and extending on both sides of the plate, a
screw connecting the ends of the yoke through the perforations and an insulating
bushing to insulate the yoke and screw from the metal plate.
7-In an electric heater, a slotted case made in two parts, a body or bodies of
insulating material supported in and by the ends of the case, a resistance-conductor
around the body or bodies of insulating material, conductors leading to the interior
of the case between the two parts, and screws or bolts extending through the parts
of the case to hold them together and thereby to hold the said body or bodies in
position within the case.
8-In an electric heater, a support consisting of a case or enclosure divided
longitudinally in two parts, supports or holding devices on the interior of the case,
a plate or thin body held by said devices parallel to and in the plane of the meeting
edges of the parts of the case, a resistance-conductor wound around the plate,
supply conductors leading through the case to the terminals of said resistance-

page_text: conductor, and means to hold the parts of the case together and the plate or thin
body in position.
9-The combination in an electric heater, of a thin body of suitable material with
its sides or faces having the greatest surface area plain or ungrooved notches or
indentations in and extending across one or more of its edges, and a wire forming
part of an electric circuit wrapped around said body across both faces thereof, and
lying in said notches, as and for the purpose described.
10 The combination in an electric heater, of a plurality of plates arranged side
by side with air spaces between, means to hold said plates apart, wire forming part
of an electric circuit wrapped around each of said plates across both faces thereof,
and a perforated case for the purpose described.
Dated this 1st day of March 1893.
MARK WESLEY DEWEY.
Haseltine, Lake & Co.,
45, Southampton Buildings, London, Agents for the Applicant.