Improvements in Apparatus for Electric Cooking and Heating.
Year: 1891

page_text: Date of Application, 2nd Oct., 1891-Accepted, 12th Dec., 1891
CORE DELE
Improvements in Apparatus for Electric Cooking and Heating.
I, FRIEDRICH WILHELM SCHINDLER-JENNY of Kennelback near Bregenz, in
the Empire of Austria, Electrician do hereby declare the nature of my said inven-
tion, 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 establish a system for cooking and heating by
electricity in employing suitable and improved devices and apparatus, which I am
about to describe.
My invention is based upon the well known principle that a sufficiently strong
electric current, when passed through a suitable conductor, will cause the same to
heat and to glow.
To bring a conductor of this kind as, for instance, platinum wire, as employed by
me by preference, in immediate contact with metallic or other cooking vessels,
however, would be impracticable for obvious reasons, while on the other hand, in order
to utilize as much as possible the heating effect of the wire, the same should be
brought in as close proximity to the vessels or surfaces to be heated, as possible.
In order to find a practical solution of this question, I have made numerous
experiments, the results of which form the subject of the following Specification.
Before I enter upon the detailed description of my invention, however, I wish to
state that I am well aware, that others have already made experiments in the same
direction, which however have never led to any real practical results, while I have
succeeded in constructing a system of cooking baking and heating by electricity,
which, after serious tests has given satisfactory results.
My system essentially consists in passing an electric current through a suitable
conductor, which is placed in numerous windings upon the surface of a refractory
non conducting plate. Upon the conductor, so arranged, I place by preference, a
thin covering of refractory, insulating material, which for its protection may again
be provided with a metallic cover. The insulating cover last mentioned may be
dispensed with, when the conducting wire is imbedded in the insulating refractory
bottom plate.
As the best suited conductor 1 employ by preference thin platina wire and as the
best suited form for arranging it, I use the spiral. The refractory, insulating
bodies or covers I make of fireclay, mica, or any other refractory, insulating
material or composition.
In the annexed drawings I have shown by way of example a number of devices
constructed after my invention.
Fig. 1 shows in perspective view a cooking range plate with three heaters.
Fig. 2 shows a heater in cross section.
Fig. 3 is a top view of a heater, with metal and insulating covers removed.
Fig. 4 shows a heater for boiling purposes in perspective view and
Fig. 5 the same in vertical section, standing inside of a vessel.
Fig. 6 shows a kettle for boiling with a heater attached to the bottom thereof.
Fig. 7 shows a plate warmer or device for similar purposes with covering plate
removed.
Fig. 8 shows in perspective view a complete electric cooking range.
Fig. 9 is a perspective view of the interior box or body of the baking oven.
Fig. 10 shows the end view of a fish boiler with heater in section.
Fig. 11 is a top view of this heater.
Fig. 12 shows a modification of a heater in section.

page_text: Fig. 14 is a top view of the insulating, plate for this iron.
Fig. 15 is a vertical longitudinal section of this-smoothing iron and
Fig. 16, is a cross section, of the same.
Fig. 17 shows a modified heater for boiling, in perspective view.
Fig. 18 is a cross section of the same &
Fig. 19 shows the heater with its outside covering removed.
In all figures similar letters of reference indicate corresponding parts.
a a a are the heaters, which may be placed in the top plate of a range in any
desired number.
1
A heater of this kind consists of the refractory insulating bottom part, or plate
by preference of fire clay. This plate is upon its surface provided with a double
spiral groove, returning to its starting point. Into this groove the conductor, in
this case thin platina wire, is placed either direct or wound round an asbestos or
other string. According to requirement the spiral groove may be double as shown
or morefold. The ends of the platina wire are by preference at the periphery of 1
plate b, for instance at 6' 6", connected with the circuit. The platina spiral e thus
solidly and evenly imbedded in the groove of plate I cover with an insulating
refractory plate d, which must be as thin as possible, and which, for this reason
make by preference of mica sheet. For the protection of this sheet d, I place on
top of it a cover of thin metal or other suitable material. Or plate with platina 2
spiral c and mica sheet d, as shown in Fig. 2 may be placed into a metal box or
casing and provided with the metal cover a¹; the whole may be held together by
a number of screws fff, which will also serve to prevent a warping of the thin-top
plate a by the heat. Instead of a case or box only a top and bottom plate may be
employed, between which the plate with platina spiral and mica cover may be 2
held by means of the said screws fff.
A still more simple construction is that indicated in Fig. 12. Here the groove in
the refractory, insulating plate b is made deeper than required by the thickness of
the wire, so that the same is situated quite below the surface. After the wire has
been placed into the groove, the latter is by preference filled out with refractory,
insulating material, for instance with fire clay, the same as plate b, so that the
platina wire is completely encased in the said material. In this case the insulating
(mica) covering and even the metal top plate may be dispensed with.
In all cases, I prefer to make the spiral so, that its windings may be wider apart
in the centre and narrowing towards the periphery of the plate in order to obtain
an even distribution of the heat upon the entire surface, while in employing a spiral
of uniform equidistant windings the centre part of the plate would receive a greater
quantity of heat than the other parts, which might also cause a warping of the thin
metal top plate. Heaters constructed according to the above description may be
employed in any desired way for cooking and similar purposes.
By preference I place one or more of such heaters in a range plate A, provided
with suitable openings as shown in Fig. 1, or I may provide them with any other
suitable support.
The ends of the platina wire are connected with an electric circuit so that the
current, which may be regulated by the interposition of suitable resistances, in
passing through the platina spiral, will cause the same to glow and heat the
refractory, insulating bodies band c. By placing cooking vessels upon such heaters,
all the different cooking manipulations may be performed, the same as upon a
common cooking runge.
For making liquids boil, I employ by preference a special heater, as shown in
Figs. 4 and 5. This heater is essentially of the same construction as those before
described and consists of a platina spiral, enclosed between two refractory, insulating
plates or bodies b and d; in this case I employ by preference two sheets of mica for
the purpose. The whole is here, however, enclosed in a watertight receptacle g g
provided with a handle h h', through which the wires are passed, which connect the
platina spiral with the circuit. If any liquid is to be heated or made to boil,
the heater just described is immersed therein, and the electric current is closed; the

page_text: platina spiral is thereby made to glow, and the whole body of the heater becomes
hot enough to cause the liquid to boil within a short time.
Instead of dish shaped this heater may also be made in any other suitable form,
for instance in the shape of a ring, as shown in Figures 17, 18 and 19. In this case
the platina wire is insulated in the same manner as before described, and wound in
spirals inside of the ring shaped capsule'y g, which, the same as the one before
described must be watertight. The wire is here passed through the tubes g¹¹ into
the handle h, and through this to the connection with the circuit. This kind of
heater is different from the dish-shaped one only in so far, as here the heating is
effected from the side, whereas in the latter one this is done from the bottom.
In place of the solid homogeneous insulating plates, there may also be employed
Band or any other sufficiently refractory insulating material in granulated or
powdered form. In this case the platina spiral is by preference sewn or otherwise
fixed to a sheet of paper, placed upon an insulating, refractory plate, such as mica
for instance, and the whole is put into a receptacle containing sand. After being
well covered over, and packed in with the sand, the platina wire is made to glow by
the passage of an electric current, which causes the paper support of the spiral to
burn or char away, leaving the spiral in proper position, imbedded in the sand.
As shown in Figs. 6,-10 and 11, the heaters may also be attached to the bottom
of cooking vessels, so that the same may be used for cooking etc., independent of
any range. The construction of these heaters is the same as that of the others, with
the only difference, that they are provided with a rim or flange e', by means of
which they may be attached to the bottom part of the vessel. The connection
of the platina wire with the circuit may be established at the side as shown or
at any other convenient place.
The construction shown in Fig. 7 is intended to serve as a plate warmer or
for keeping the dishes hot on the table. Here the platina wire is by preference
not laid in the form of a spiral, but in some other form, such for instance as
shown in the drawing. The wire may be imbedded in sand as shown, or placed
between two refractory insulating plates as described. The fish boiler shown in
Figs. 10 and 11 is constructed in the same manner, only the wire is here laid
in more numerous windings and is imbedded in a plate of fire clay.
In Fig. 8 a complete clectric cooking range is illustrated. Top-plate A is
supported by a suitable frame, and is provided with three heaters a a a. In
the centre part of the range the switch board is arranged, which contains the
switches for the different heating parts of the range, as well as for the eventual
resistances required. Below plate A the range contains on one side a roasting
and baking oven H and on the other side a water tank T. As it is necessary
in roasting and baking that the oven should supply heat, not only from the bottom,
but from all sides, two, three or four sides of the oven may be provided with heaters
of the kind described. I prefer however to employ an oven of one of the following
constructions. II.make the oven of thin sheet metal in form of a box open in
front, but provided with a slide or door for closing it. This box I enclose in,
or wrap with refractory insulating. material, such as, for instance, asbestos paper,
on top of which I wind the platina wire in coils around the whole box. These
platina coils I cover again with refractory, insulating material, enclosing the
whole by preference in another metal box to be placed in the range. Or instead
of the arrangement just described, the box may also be made of fire clay or other
similar refractory insulating material entirely. A box of this kind is shown in Fig. 9.
Box H is provided around its outside with grooves hh which form a continuous
coil around it, and which are of such depth, that they only leave material
enough at the bottom to ensure the solidity of the box, so that the platina wire,
when placed into these grooves will be as near the inner surface of the box as
possible. The platina wire is as usual connected with the electric circuit.
The water tank is made so, that it can be pulled out like a drawer, and the
water contained therein, is by preference heated, by placing a heater of the
kind shown in Figs. 4 and 5 or Figures 17, 18 and 19 into the tank.

page_text: The smoothing iron shown in Figs. 13, 14, 15, and 16 illustrates the manner
of employing my system for heating purposes. The iron consists of the hollow
body K, inside, upon the bottom of which rests the heater. This heater con-
sists of the refractory insulating plate 6 of fire clay or similar material, into a
suitable groove in the bottom of which the platina wire is placed in the manner
above described. Between the plate and the bottom of the iron, a sheet of
mica may be placed, or the wire may be deeply sunk into plate b. At b¹ 611
the wire is connected with the circuit. The iron is closed by a top K" with
handle L L. The free space in the iron may be filled with a suitable weight K³.
Having now particularly described and ascertained the nature of my inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
=
1.) A system for the practical utilization of the electric current for cooking
and heating purposes, consisting in passing the current through a conductor
enclosed in windings between two flat, refractory, insulating plates, or imbedded
in one such plate, substantially as described.
2.) In electric cooking apparatus a platina wire, which can be made to glow,
by the passage through it of an electric current, disposed in form of a flat
spiral between two refractory, insulating plates, substantially as described.
3.) In electric cooking apparatus of the kind herein described, the employ-
ment of refractory insulating plates of fire clay, mica or other suitable material
provided on their surface with spiral grooves for the reception of a platina wire,
the platina spiral covered by a refractory, insulating plate, or imbedded in the
lower plate; substantially as described.
4.) A heater for electric cooking purposes consisting of a platina spiral
enclosed between two refractory, insulating plates or sheets, the whole encased
in a watertight capsule or box 9 g, by preference provided with a handle / h¹
through which the conducting wires are passed, substantially as described.
5.) A modification of the herein described system, principally for roasting
and baking purposes consisting of a box H of refractory insulating material,
around which the platina wire is conducted in deep grooves gg; substantially
as described.
6.) A modification of the herein described heater consisting of a capsule g 9,
made in ring or similar shape, in which the platina wire is enclosed between
two refractory, insulating plates; substantially as described.
7.) An electric smoothing iron constructed after the system herein described,
consisting of body K with cover K", enclosing a platina wire between two
refractory insulating bodies b and c; substantially as described.
Dated this 2nd day of October 1891
FREDERIC PRINCE,
1. Quality Court, Chancery Lane, London, W.C.,
Agent for Applicant.
FREDERIC PRINCE,
1. Quality Court, Chancery Lane, London, W.C.,
Agent for Applicant.