Year: 1887

page_text: Date of Application, 31st Mar., 1887.
Specification Accepted, 19th July, 1887.
I, RUDOLF GEBURTH of Vienna, in the Empire of Austria, Manufacturer of Ovens
do hereby declare the nature of my said invention and in what manner the same is to
be performed, to be particularly described and ascertained in and by the following
statement :-
1
The essential features of this improved oven for baking are as follows:-
With reference to the drawings S is the chamber, being at its sides and upper part
hermetically sealed against the exterior air, having however at its lower portion an
opening B. so constructed as to effect a result like that obtained by a saucepan lid or
bell; and to prevent the air contained in the chamber S from escaping otherwise but
by the rear end of it communicates with a heating surface D (see Figure IX) which
warms the air contained in the chamber up to the temperature wanted for baking and
re-warms the air which has become cool, that is to say, it maintains the air in the
chamber at the proper baking temperature. In this chamber S bread, pastry or the
like is placed on plates ranged above one another. In consequence of the form of
the space for baking and by its contact with a heated surface a vivid circulation of the
air contained in the chamber takes place, as the air of the chamber when cooled by
the contact with the articles being cooked streams back to the surface for heating and
there takes up heat, enters again into the space for baking, gives up there its heat to
the bread and continues this circulation ad infinitum. Instead of the continual
circulation of air between the chamber and the hot surfaces, there may also take
place a continuous supply of fresh hot air from the heating surfaces to the baking
spaces. This air would enter the baking space above, descend downward and escape
below, or conducted to a chimney. The circulation of air above spoken of can take
place in each direction.
The shape of the hot surface and its position towards the baking chamber is not
essential. It may either be placed in a closed space and communicating with the
chamber for baking, or form a hollow space itself, or occupy a part of the baking
chamber itself, also the walls of the chamber themselves may form such a hot surface.
In this case the plates of bread or pastry would be a certain distance from the hot
walls to prevent the direct communicating of heat to the plate and the radiation of
heat from the walls to the pastry and to afford a circulation of air. This would be

page_text: equivalent to the construction of apparatus illustrated in Figures I and II with the
omission of the walls W and setting the hot walls in the place of the tubes R. The
surface for heating may be situated over or beneath the baking chamber or extend
along its sides. The circulation of the air between the chamber and the heating
surface may be produced both by the difference of the specific weights of the colder
and warmer air and by mechanical means such as blowers of any suitable kind. The
heating surface may be heated either directly by coal, coke, or wood, or by gas, steam,
or hot water.
From a small boiler or water box steam or water (evaporated by the high
temperature of the baking chamber) may be introduced into such chamber. The
greater part of the baking of the pastry must take place in super heated steam and not
in air. By reason of the form of the baking space it is possible to fill this space with
the steam generated. The steam introduced being lighter than air drives the air out
of the chamber and cannot escape itself. The baking chamber thus filled with super
heated steam is most effective for baking bread and all kinds of pastry.
The articles to be baked are introduced from below into the chamber filled with
steam by means of a conveying device which is raised, and when they are baked
enough lowered and taken away below. This conveying device is formed so as to
allow of a great number of horizontal plates being placed above one another in the
chamber. On these plates the pastry is spread.
To let any water or steam out of the chamber that may be produced by the baking
of such kinds of pastry where it is noxious an opening is provided on the upper
part of the baking chamber which can be regulated. Also for this purpose fresh hot
air may be brought from the heating surface D) (Figure IX) into the chamber. This
may be done by after having shut up the under opening for circulation a and made
another opening ẞ where the fresh air enters and rises in the baking space above, then
sinks down and escapes by the opening B or is conducted away into a chimney.
Description of a combination of the essential parts of the mechanical oven for
baking with air, which has been found convenient for heating with coal, coke, wood,
and the like.
With reference to Figures I. II. III. and X. O is a furnace. Rare tubes which
receive the gases of combustion and convey the heat to the chamber S through which
they pass. The chamber S is hermetically sealed above and at its sides and has at its
back end the aperture B. The tubes R terminate in a common chamber X from
which the gases of combustion flow into the large tube Y and are at a convenient
point in it led into the chimney. From the furnace however the smoke gases may
also be directly led into the tube Y and therefrom into the chimney without passing
the chamber for baking.
The damper V and the valve Z are connected and work together by means of a
lever so that one of them is shut when the other is open. During the process of
baking V is generally closed and Z is open, so that the hot gases pass through the
the tubes R. If during baking the temperature in the chamber S rises too high it
may be lowered immediately by opening the damper V and shutting the valve Z
W, are partition walls which divide the space for baking from the heating tubes and
establish the circulation of the air by means of the apparatus u-u. It would not be
departing from this construction if the walls W were omitted and there were employed
instead of the tubes R a heating surface of another form, the effect would be nearly
the same.
Cand C, are water kettles out of which by means of the cocks F and I,
water may be spouted into the chamber for baking in order to produce steam. T is a
thermometer on which the degree of temperature existing in the chamber may be seen
from without.
1
To let the steam out of the chamber S which is produced by the process of baking
with such kinds of pastry where the steam is noxious there is an aperture A on the
upper part of the baking chamber and fresh hot air is brought into the baking space.
To effect this the apertures u₁ are totally or partly shut and new openings are made
instead of them in this part of the chamber which contains the tubes R below so that
fresh air enters there, rises and is heated by the tubes, then goes into the baking space
'

page_text: above, sinks down and becomes cooled and finally escapes below or is conducted into
a chimney. In order to feed pastry or the like continually into the baking chamber
and to deliver it, there is constructed a conveying device or mechanism arranged to
make horizontal plates pass (rising and descending) through a passage or way closed
for itself so that the plates always remain parallel to each other. K is an endless
chain of novel construction. This chain consists of four or more parallel rows of flat
rectangular links, which are so long that the links of each row touch each other at
their tips; two ends of the rectangular pieces are rounded, the others remain sharp.
By this the chain is rendered flexible towards one side but rigid towards the other,
like a column, (Figure VIII). This chain runs over two chain wheels QQ: At
certain distances the chain is provided with links whose one side is lengthened to a
lever H. This lever is furnished with a projecting piece E bored as a bearing Gare
conveying baskets. The pin or spindle N fixed at the top and fore end of the
conveying basket is fitted into and works in the bearing E of the lever H. At the
back side the conveying basket has a second pin or spindle N¹ (Figures IV and X).
A second endless chain K¹ runs over the chain wheels QQ, this chain stands parallel
to the chain K and is of the same length, but is placed or arranged lower than the
chain K vertically by the distance between the two pins or spindles N N¹, of one
conveying basket. The pins N¹ of the conveying basket rest in the bearing E¹ of the
levers H of the chain K¹. The chain wheel Q₁ is fastened with a key on the axle I.
The other three chain wheels QQ, Q¹ run loosely as rollers on firm spindles. A fifth
chain wheel Q, which is fastened by a key on the axle I gears with the chain K¹.
Thus by the turning of the axle I both the chains are moved with equal quickness.
The axle is turned from without by means of a bent handle and toothed wheel trans-
mission gear. The conveying baskets follow the movement of the chain and when in
their highest and lowest positions are respectively reversed and move in the opposite
direction of the movement by the levers H without any upsetting, turning or swinging
of the basket, that is it always keeps its normal position and remains parallel during
the whole circulation. This conveying mechanism is particularly designed to produce
the movement required for the pastry in the baking space of the herein described
oven.
1
Each conveying basket carries one plate or tray, or more (Figure VI) on which the
goods are spread. These trays for baking have a bottom of strong twisted or woven
metal, such as copper. The bottom of the tray or plate is fastened to its frame by
small clamps and the trays fit exactly into the conveying basket (Figure V). The
tray or plate for baking is provided with small feet and the bottom of the conveying
basket has an oblong slot (Figure V) so that the air stream crossing the space for
baking surrounds the pastry lying on the plate or tray entirely. This is demonstrated
by arrows in Figure VII.
The material of which this oven is made may be metal, stone, or the like. The
apparatus represented in the drawings is made of metal plate and clad without with a
bad conductor of heat. Also two or threefold walls clad with asbestos are good to
retain the heat. The mode, of action of this apparatus consists as follows:-The
stream of hot air or steam entering the space for baking from above, by the apertures U
comes in contact with the goods lying on a number of the parallel trays or plates
ranged above each other; it then sinks down becoming cooler and flows back to the
hot tubes by the apertures U₁. It then rises and is heated and re-enters the baking
space and continues to operate in this manner. The heat delivered by the hot air (or
steam) to the pastry or other material effects the best possible baking of it.
When commencing to bake a fire is made in the furnace O. When the thermometer
indicates the temperature wanted for baking, water is spouted into the box by means
of the cocks F. F, until the steam issues out below. By means of the handle close to
the door a conveying basket is brought before the aperture B and is provided with
uncooked pastry and then raised up. by turning the handle. The next conveying
basket is now brought before the aperture and is likewise provided and elevated.
The feeding of the conveyor is continued until the basket first filled or provided

page_text: has arrived with its pastry in a finished state before the aperture B. The finished
pastry is taken off and the basket is replenished and thus the process is continued.
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 :-
First. A mechanical oven for baking consisting of a chamber that is hermetically
sealed at its upper part and at its sides, whilst near its lower extremity it is pro-
vided with a charging and discharging aperture B, the said oven having heating
surfaces R separated from the baking space by partition walls, substantially as set
forth.
Second. A conveying mechanism composed of endless chains & flexible in one (the
outward) direction and rigid in the other (the inward) direction, the links of the said
chain being furnished at certain distances with levers H such levers being provided to
convey baskets (G) in such a manner that one lever supports the lower side of the
basket so that the objects to be conveyed are always held, while moving up and
down, in a parallel position when the motion is reversed, substantially as and for
the purposes set forth.
Third. The baking plates set forth with reference to Figure V of the drawings, the
bottoms of which are of open work and which are constructed with feet for resting on
the bottom of the conveying baskets, the said plates being provided to carry the
objects to be baked substantially as set forth.
Fourth. The water kettles e arranged upon the outside of the oven and from which
the water may be conducted to the heated bottom of the baking chamber substantially
as set forth.
Fifth. A valve Z arranged in the tube G and corresponding to the slide V by which
the fire gases may be led either through the baking chamber or directly from the oven
into the chimney substantially as set forth.