Improvements in Electric Heating Apparatus.
Year: 1890

page_text: Date of Application, 21st Apr., 1890-Accepted, 25th Oct., 1890
R
COMPLETE SPECIFICATION.
Improvements in Electric Heating Apparatus.
I, MARK WESLEY DEWEY, of the 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 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 :-
The object of my invention is to provide simple, effective, and safe electrical heaters
for heating rooms, cars, and other inclosed spaces, and that will occupy little or no
valuable space, and yet be located in the most desirable and advantageous position
accessible.
The disadvantages common to usual modes of artificial heating that have been
heretofore employed is that in it the heat is concentrated, and is therefore not as
effective as it should be, since the parts of the room in the vicinity of the heater must
be heated to an undesirable degree in order that the parts more remote may be raised
to the required temperature, and the resistances must be so highly heated for this
purpose as to make it dangerous or liable to ignite surrounding combustible objects.
I employ in my invention heating devices having very largo surface area, and these
consequently have a very large or extended radiating-surface. On account of their
construction they are capable of developing a great amount of heat without becoming
very hot, and this without employing expensive resistances.
The heating devices I employ are in the shape of a floor-mat, which may extend
over the entire floor or only a part of the same, so that the heat may be equally
diffused throughout the room or apartment. As the heating devices have a large
radiating-surface and extend to all parts of the room upon the floor, said room will be
equally and comfortably heated, and this without raising the temperature of the heater
above 80° or 90° or thereabout.
In order to prevent undue heating of the devices or to keep their temperature
below the igniting-point of wood or other similar combustible material, I provide a
thermostatic cut-out or current-controller arranged so that it may be adjusted for any
desired degree of temperature and cut out the heating device when the temperature
rises above the desired degree.
It is evident that the lower a heater can be located in a room the more equal and
more comfortable will be the temperature. This form of heater is especially adapted
for street-cars, where the room under the seats is occupied-as, for instance, storage
battery cars-or, in fact, all cars employing the electric current for propelling or
lighting purposes.
In the accompanying drawings, Figure 1 represents a top view of floor-mats
coupled together and connected with a suitable source of electricity and a thermostatic
current-controller in circuit. Fig. 2 is an enlarged sectional view of a portion of the
mat on the left in Fig. 1, taken on line x, x. Fig. 3 is a similar view of the mat on
the right of the figure. Fig. 4 is an elevation of a mat clamp or connection from
which the mat can be removed. Fig. 5 is an enlarged top view of the floor-mat
couplings or detachable electric connections between the mats. Fig. 6 is a plan view
illustrating the arrangement of the heat-developing conductor in the mat to be
employed when the volume of the source is small. Fig. 7 is a transverse sectional view
of a floor-mat inlaid or countersunk in a floor. Fig. 8 is another form of mat.
Fig. 9 shows a portion of an edge view of a metallic floor-mat with protecting material
upon and under the same. Fig. 10 is a plan view of an open-work or ventilated fibre
mat upon a metallic electric mat to form a shield for the latter and also provent noise
when walked upon, and Fig. 11 is a side view of another and very simple form of inat
that can be used also for heating.

page_text: Referring specifically to the drawings, A and A¹ in Fig. 1 represent the floor-mats
to be heated by an electric current from a suitable source, as a secondary or primary
battery or a,dynamo-electric generator.
It will be unnecessary to describe a particular source of electricity herein, as any
suitable and well known source can be employed for the purpose.
For
In some cases, especially where cars are to be heated, a heating current may be
employed similar to that described in my prior U.S. Patents on electric heating
apparatus for railway systems, Nos. 401, 482 and 406, 890, dated, respectively,
April. 16th, 1889 and July 16, 1889. Such current is more economical and safer
than high-tension currents. There is no danger of receiving a shock in case of
contact with exposed parts of the mat, even though it may be uncomfortably hot
to touch, due to the passage through said, mat of the heating-current..
this reason, also, the current will not leave its conductors as readily as currents
of higher potential. The conductors a a leading from the source to the mat or
mats when a heavy heating current is used are formed of large metal rods or
stranded cables. The thermostatic cut-out located in one of the conductors a may
be of any suitable form, but preferably, as shown in Fig. 1, consists of two thin
strips of the same or different metals, placed one upon the other and fixed
jointly at one end to a post s on the base-plate T. If the strips are of the same
metal, they are insulated from each other; but if of different metals they may not
be insulated from each other. When insulated one from the other by non-conducting
varnish or a thin strip of mica, or other suitable material, the strip t through
which the current passes, will be heated more than the strip t¹ and consequently
cause the strips to warp and throw the free end u out of contact with the posts s²,
and thus break the circuit, allowing the heated mat to cool. The warping of the
strips is due to their unequal expansion as is well known. To regulate the action
of the strips t t under the influence of heat and thereby control the development
of heat in the mat, I employ an adjusting-screw inserted in a screw-threaded
post o', and standing at right angles to the plane of the thermostatic strips t t and
bearing upon the same, as shown in Fig. 1 of the drawings. By increasing the
pressure of the screw upon the said strips the separation of the strips from the
posts will be resisted, so as to require a higher degree of heat to effect said
separation. To guard against excessive heating of the mat, the screw-post o¹ may
be made to serve as a stop to the movement of the screw o by setting said post
in a position to bring the head of the screw in contact therewith when said screw
is adjusted to the required limit. On the same base-plate T is a common circuit-maker
and breaker or switch S. As shown in the same figure, the circuit is closed.
When the switch is moved, as shown by the dotted lines, the circuit is open.
The clamp B B connecting the conductors a a with the terminals of the
mats, may be greatly varied in form, and I do not limit myself to the precise
construction shown. One of the clamps B is clearly shown in Fig. 4, and consists
of a plate d to be screwed to the floor F. A binding post bis mounted upon
one end of the plate. 61 is a spring arm or clamp proper fixed to or forming a
part of the binding-post 6 and extending to and over the opposite end of the plated,
and holding a portion of a mat A between said spring-arm and plate, thereby
securely clamping the terminal of the mat and making a large surface contact with
the same.
The binding-screw 6" is employed for creating greater pressure upon
the terminal c of the mat.
When mats are large or too long to be handled conveniently, they are made in
sections with couplings or detachable connections between them to hold them together
and make electric connection between the parts. This coupling or connection, like
the clamps already described, may be greatly varied in construction, but it will be
sufficient herein for the purpose of this invention to describe clearly only the form
shown in the drawings.
Referring to Fig. 5 which is an enlarged view of the coupling, it will be seen
that the mats have end strips of metal ee to which the connecting parts are fixed.
The connecting parts on one strip consist of an arrow-head projecting from the

page_text: middle of one
strip, and a spring on each side of the arrow-head and fastened
to the strip at each end, the middle portions of the springs bowing outward from
from the strip to which it is attached to make good contact with the opposite
strip e. On the middle of the sal opposite strip are fixed two springs fl. These
springs extend outward from the strip and are formed to receive the arrow-head between
them and there hold the same. When the said arrow-head is inserted, the
springs on both sides of the same are in contact with the opposite strip, as
shown in Fig. 1. The latter strip is also provided with pins g¹, which enter
the springs gg and serve to hold the mats in place.
Both of the mats A and A' in Fig. 1 are formed of conducting and non-
conducting material, the conducting material forming the heat-developing and
radiating electric conductor or conductors, and the non-conducting material forming
the shield or protecting part. The conducting. part of the mat A is formed of
a strip or strips of metal, as iron, nickel, copper, or bronze. The metallic strips h
are waved or zigzagged in a suitable manner, preferably as shown, and placed
between slats of wood n or other suitable non-heat conducting material. The
wooden slats are thicker than the metallic portion of the mat, as shown clearly in
Figs. 2 and 3, and are therefore more prominent than the heat-developing conductor
and shield or protect the latter from contact with more combustible materials.
Rivets or small bolts connect the metallic strips through the wooden slats of
the mat.
On account of the form of construction the mat A in Fig. 1 is rigid or stiff; but
the mat A¹ in the same figure is flexible and may be rolled up. The metallic or
conducting part of this latter mat is formed of a series of springs leading through
the wooden slats n placed equidistantly apart. Pins p extend through the slats where
the springs pass through them to prevent the shifting of the slats on the springs. A
sectional view of a portion of the latter mat A! is clearly shown in Fig. 3 of the
drawings. The heat-developing devices of these mats may be said to be connected in
multiple are, which is the preferred form; but if the qualities of the current to be
utilized are not sufficient to produce the required amount of heat with such a mat the
heat-developing conductor of the mat can be connected with the terminals of the same
in series, thereby allowing the employment of a current of moderately-low volume, as
shown clearly in Fig. 6 of the drawings.
Fig. 7 represents an edge view of a floor-mat A inlaid or let in the surface of the
floor F representing a section of the floor. In order to prevent ignition, if the mat is
designed to be heated to a high temperature and the floor is composed of a combustible
material, fire-proof and non-heat-conducting tiling & is placed on the floor underneath
and around the mat. In some cases a perforated asbestos mat may be employed to
cover the heating- mat as a shield and protection, as hereinafter. fully described and
shown in another figure. The electric connection to this wat is effected by leading
the conductors a a from the source of electricity and underneath the floor to the
binding posts or clamps B which extend from the under side of the terminals c c of
the mat through the floor. In some cases the mat may simply lie upon the said posts,
and in other cases to obtain more perfect contact between the parts screws m m may
be inserted through the mat into the posts B B as shown in the figure.
Fig. 8 represents a mat composed entirely of metal, preferably of iron or nickel.
Such a mat is very simple and inexpensive and can be cast in one piece. The edge
view of this form of mat is shown in Fig. 7. The terminals c c are shown located at
the corners on one side of said mat, but it is obvious that said terminals can be located
on any suitable part of the mat-as, for instance, on the ends, where they are shown.
in dotted lines and lettered c¹ c¹.
Fig. 9 represents a portion of the edge view of the saine mat with non-heat-
conducting material k underneath the same, with a mat upon it formed of wooden slats
strung on wires and equidistantly apart to allow the circulation of heat through the
same and to form a shield for the metallic mat beneath. This metallic mat, or the end
portion of same, is shown in Fig. 10, with an open-work, or braided fibre mat upon
the metallic one. The fibre mat is loosely woven, to allow the ventilation of heat

page_text: through the interstices thereof. This fibre mat may be made of asbestos, and thereby
rendered fire-proof when it is desired to heat the metallic mat to a high temperature.
In Fig. 11 is shown a mat formed of fluted or corrugated sheet-iron. In the right-
hand portion of the.same figure wooden slats are shown placed in the hollows of the
iron on the upper side of the mat and riveted therein. This mat may be constructed in
either style.
It will be evident that if the heating-mat is sufficiently large it will be unnecessary
to heat it above the igniting-point of wood, and therefore the precautions against
setting fire to combustible surrounding objects, described and shown herein, are not
absolutely necessary in all cases.
I propose in some cases to have one or more holes through the floor beneath the
mat to increase ventilation and diffusion of heat.
I do not desire to be limited to the precise form and construction of the floor-mats,
as this may be greatly varied, according to circumstances. The mats may be connected
in the circuit either in series or parallel, if required.
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 1
claim is
1-A floor-mat composed partly or wholly of metallic material and containing one
or more heat developing and radiating electric conductors, and a suitable source of
electricity connected to said mat.
2-A floor-mat composed partly of metallic electric conducting material and partly
of non-conducting material and containing one or more heat developing and radiating
electric conductors, and a suitable source of electricity connected to said mat.
3-In an electric heating apparatus, a floor-mat composed partly of electric
conducting material and partly of non-conducting material, said non-conducting
material projecting above the plane of the conducting material to serve as a protecting-
shield for the latter, one or more heat developing and radiating electric conductors in
said mat, and a suitable source of electricity connected to said mat.
4-In an electric heating apparatus, a floor-mat comprising one or more heat-
developing electric conductors, and a covering or shield of non-heat-conducting
material, and a suitable source of electricity connected to said mat.
5 In an electric heating apparatus, a floor-mat comprising one or more heat-
developing electric conductors, and a ventilated covering or shield of non-heat-
conducting material, and a suitable source of electricity connected to said mat.
6 A floor-mat comprising one or more flexible metallic heat-developing electric
conductors, and a suitable source of electricity connected to said mat.
7-An electric heating apparatus comprising a suitable source of electricity and a
floor-mat composed partly or wholly of heat developing electric conductors removably
connected to the aforesaid source of electricity.
8-An electric heater consisting of two or more floor-mats comprising one or more
heat-developing electric conductors, a detachable electric connection between the mats,
and a suitable source of electricity connected to said mats.
9 An electric heating apparatus consisting of a suitable source of electricity, two
or more floor-mats comprising one or more heat-developing electric conductors
detachably connected to said source of electricity, and a detachable electric connection
between the mats.
10 In an electric heating apparatus, a floor-mat comprising one or more beat
developing electric conductors, a suitable source of electricity connected to said mat,
and a thermostatic current-controller to prevent an excessive heating of the mat.
11-In an electric heating apparatus consisting of a suitable source of electricity,
a floor-mat comprising one or more heat-developing electric conductors connected to
said source of electricity, a thermostatic current controller to prevent an excessive
heating of the mat, and a regulator for controlling the action of the said current-
controller, as set forth.
12-In an electric heating apparatus consisting of a suitable source of electricity,

page_text: a floor-mat comprising one or more heat-developing electric conductors connected to
aid source of electricity, a thermostatic current controller to prevent an excessive,
heating of the mat, a regulator for controlling the action of the said current-controller
and a stop for limiting the movement of the regulator, as set forth.
13 In an electric heating apparatus, a removable floor-mat comprising one or more
heat-developing electric conductors, a suitable source of electric heating-current, and
stationary clamps adapted to connect the said wat in circuit with the source of heating-
current.
14-In an electric heater, a floor-mat comprising one or more heat developing and
radiating electric conductors countersunk in a floor, a suitable source of electricity.
and connections leading from said source and beneath the floor to said mat.
Dated this 11th day of April 1050.
MARK WESLEY DEWEY.
Haseltine, Lake & Co.,
45, Southampton Buildings, London, Agents for the Applicant.