Improvements in and relating to Electric Heaters.
Year: 1898

page_text: Date of Application, 12th Apr., 1898-Accepted, 18th June, 1898
COMPLETE SPECIFICATION.
Improvements in and relating to Electric Heaters.
I, EDWIN FORSYTHE PORTER, a subject of the Queen of Great Britain and Ireland,
residing at 109, Bower Street, in the Town of Roxbury, County of Suffolk and State
of Massachusetts, United States of America, Gentleman, do hereby declare the
nature of this 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 improvements in electric heaters and especially to that
class of electric heaters known as electric fan heaters, and described in Patent Speci-
fication No. 5595, of M. W. Dewey, dated March 31, 1891.
The object of my invention is to electrically heat the blade of a fan without
adding thereto or mounting thereon any resistance material, the blade being itself
heated directly by a current passing through it. Heretofore electric fan heaters have
been constructed by mounting the electrical heating resistances on the blades of the
fan, the blade being either solid or in skeleton. This form is disadvantageous because
of the complication of parts necessary for its construction, whereas, in the form
which I adopt absolute simplicity is attained, as a material, such as carbon, is used
for the blade which has the required mechanical strength for moving the air and also
the requisite electrical qualities to form a heating resistance.
This construction as compared to previous constructions is simpler, cheaper and
more compact, as there is but one part, namely, the blade, which both agitates the
air and heats the air.
My invention consists of certain novel features hereinafter described and particu-
larly pointed out in the claims.
In the accompanying drawings which illustrate a construction embodying my
invention,
Figure 1 is a perspective view of an electric fan heater embodying my
invention.
Figure 2 is a perspective view of one of the fan blades.
Figure 3 is a plan view of one of the blades.
•
Figure 4 is a detail perspective view showing the manner of arranging the
blades in series, two blades being shown to illustrate the circuit entering and
leaving.
Like letters of reference refer to like parts throughout the several views.
A represents a support upon which is mounted a suitable electric motor B, on the
shaft C of which is mounted the hub D. Secured to said hub are a series of arms E
of insulating material and by means of suitable screws F also of insulating material
each blade G is securely fastened to its arm E. The blade G is moulded of carbon
in an integral mass or may be made of any other material which has, like carbon,
sufficient mechanical strength to resist the pressure of the air in its revolution and
which also offers sufficient resistance to the current to become heated during its
passage. The resistance of the blade is increased by partially dividing it in the
center by a longitudinal division G¹ which gives a greater length of material for the
current to pass through, and because of the necessary increase in width of the fan
blade toward its outer end, the blade is decreased in thickness (see Figure 2) propor-
[Price 81

page_text: tionately to its increase in width for the purpose of equalizing the resistance
throughout the entire length of the blade which resistance would decrease as the
blade becomes wider if the thickness of the blade were uniform throughout. By
thus varying the thickness of the blade to correspond with the varying width thereof,
the blade is uniformly heated throughout. The resistance of the blade may be still
further increased by a number of transverse divisions G2 which will give a still
greater length for the current to travel without increasing the area of the blade. By
this construction a blade of a smaller area will offer a greater resistance to the passage
of the current than a blade of the same area of the ordinary construction, that is,
without the divisions. These transverse divisions may be utilized for the purpose of
equalizing the resistance throughout the blade of uniform thickness and gradually
increasing width by making them more numerous or closer together as they approach
the outer and wider end of the blade.
The current enters through the wire H to the brush H¹ to the collector ring H2
mounted on the insulating drum C and then by the wire H³ to the binding post H*,
and the current traversing the blade, as indicated in Figure 3, to the binding
post H5, out through the wire J (see Figure 4) to the blade represented by the
loop J¹, and then by the wire J2 to the blade represented by the loop J³, and
then by the wire J to the blade represented by the loop J, and then by the
wire J6 to the blade represented by the loop J7, and then by the wire J8 to the last
blade G of the series, as shown at the top of Figure 4, and then after passing through
said blade, the current passes by the wire H to the collector ring H7 mounted on
the insulating drum C to the brush Hs and out through the wire H⁹.
In this construction it is not necessary for each individual blade to offer much
resistance to the passage of the current as the blades are all placed in series and the
desired effect is attained by the sum of the resistance of all the blades.
While the blades are shown heated in series, yet it will be understood that they
could be arranged in multiple, in which case the resistance in each blade would have
to be increased to obtain the same degree of heat.
A suitable guard I surrounds the fan for safety during the revolution of the same.
From the foregoing it will be clearly understood that a simple and strong blade
may be constructed for a fan heater wherein all complication of parts, which have
heretofore been necessary for the purpose of giving mechanical strength and support
to electrical heating resistances, are avoided; for instance such as a blade supporting
the resistance wires on insulating pins, or a skeleton frame supporting wire gauze
which forms a heating resistance, and other forms which show a resistance and a
blade supporting the resistance disclosed in the Dewey patent previously referred to,
whereas, in my construction, the blade which does the work of fanning the air is
itself the electrical heating resistance.
I do not limit myself to the arrangement and construction shown, as the
same may be varied without departing from the spirit of my invention.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I declare that what I
cl im, is :-
1. In an electric heating apparatus, a heating fan blade composed of a heat
developing electric resistance material, and an electric circuit adapted to pass through
said blade to heat the same.
2. In an electric heating apparatus, a heating fan blade composed of a heat
developing electric resistance material and provided with means for increasing the
resistance in said blade, and an electric circuit adapted to pass through said
blade to heat the same.
3. In an electric heating apparatus, a heating fan blade composed of a heat
developing electric resistance material and decreasing in thickness from its inner
to its outer end to equalize the resistance throughout the blade as said blade increases
in width to heat the same uniformly, and an electric circuit adapted to pass through
said blade to heat the same.

page_text: 3. In an electric heating apparatus, a heating fan blade composed of a heat
developing electric resistance material and decreasing in thickness from its inner
to its outer end to equalize the resistance throughout the blade as said blade increases
in width to heat the same uniformly and provided with means for increasing the
resistance in the blade, and an electric circuit adapted to pass through said blade to
heat the same.
5. In an electric heating apparatus, a heating fan composed of heat developing
electric resistance inaterial and decreasing in thickness from its inner to its outer
end to equalize the resistance throughout the blade as said blade increases in
width to heat the same uniformly, and provided with dividing spaces for increasing
the resistance in the blade, and an electric circuit adapted to pass through said
blade to heat the same.
6. In an electric heating apparatus, a series of heating fan blades composed of a
heat developing electric resistance material, a motor, a motor shaft, a hub mounted
on said motor shaft, insulating arms projecting from said hub to which said blades
are secured.
7. In an electric heating apparatus, a heating fan blade composed of a heat
developing electric resistance material in an integral mass, and an electric circuit
adapted to pass through said blade to heat the same.
8. In an electric heating apparatus, one or more heat developing electric con-
ductors of carbon, an electric circuit adapted to pass through said conductor or
conductors to heat the same, and movable means for removing or displacing the
heated air from said conductor or conductors.
9. In an electric heating apparatus, one or more heat developing electric con-
ductors moulded of carbon in an integral mass, an electric circuit adapted to pass
through said conductor or conductors to heat the same, and movable means for
removing or displacing the heated air from said conductor or conductors.
101 1
1000
Dated this 12th
day of April 1908.
JENSEN & SON,
77, Chancery Lane, London, W.C., Patent Agents.