Improvements in Motors Driven by a Mixture of Steam and Air.
Year: 1889

page_text: Date of Application, 23rd Nov., 1889
Complete Specification Left, 18th Aug., 1890-Accepted, 8th Nov.,
1890
PROVISIONAL SPECIFICATION.
Improvements in Motors Driven by a Mixture of Steam and Air.
I, WILHELM SCHMIDT, Engineer of Halberstadt, Plantagen Strasse 8, Germany,
do hereby declare the nature of this invention to be as follows:-
My invention consists of an apparatus for regulating the generation of power in
motors driven by a mixture of steam and air, particularly in such machines where
the firing is first employed to generate steam in a boiler, and then the combustion
gases used to superheat either a mixture of steam and air or air only.
It is acknowledged by those skilled in this branch of engineering, that although
a hot air machine is most economical the same is not practical, in that the fire-box
soon gets ruined by the heat.
The object of the present invention is to regulate the power-generation so, that
the mixture of steam and hot air necessary for the normal working of the engine,
shall contain the most practical and economical proportions of both elements thus
avoiding the danger of overheating the fire-box. On the engine being driven above
its normal speed the proportion of steam in the mixture is increased, the engine thus
working less economically as far as the actual consumption is concerned, but with less
wear and tear of its parts.
If the speed of the engine be decreased under the normal speed the proportion
of steam in the mixture is decreased so that the engine is driven almost by hot air
alone.
This regulation of the power generation consists therefore in regulating the
proportion of steam in the mixture of steam and air, and this is accomplished by
varying the heating surface of the boiler. At the same time the temperature of the
mixture of steam and air in the superheater is held constant.
This variation of the heating surface of the boiler may be effected either by allowing
the combustion gases generated in the fire-box to pass over a greater or less portion
of the heating surface or by dividing the combustion gases so that a part only of the
same serves to heat the boiler whilst the rest are conducted direct to the superheater.
In this manner it is possible to vary the proportion of steam in the mixture, or in
other words expressed, to use a greater or less percentage of the calorics generated in
the grate, for the production of steam, at the same time keeping the temperature of
the superheated mixture nearly constant.
Particular attention is directed to the fact, that my improved motor retains its
advantages as hot-air and steam engine, the temperature of the gases in the
superheater being so high, that the engine will work advantageously as a hot-air
machine.
If on diminishing the working effect of the engine this regulation does not take
place, the result is, that in such case the engine works more as a steam engine
c. with a greater percentage of steam. Such mixture of steam with compressed air
will only be heated to a slight degree and in consequence of the slight fall of
temperature the effect will be bad, as a hot-air engine since the combustion gases
will be too much cooled down on the extensive boiler heating surface.
My invention has the object of avoiding this disadvantage; when the amount of
work required to be done by the machine is lessened or increased, I am able to keep
the temperature of the combustion gases sufficiently high by regulating the extent
of the heating surface of the boiler so that the machine will work advantageously as
hot-air engine.
In order to make my invention more clear, 1 refer to the accompanying
drawings in which similar letters denote similar parts throughout the several
views.
Fig. 1 shows a vertical section of a motor driven by a mixture of steam and air,

page_text: on my system Figs. 2, 3, & 4 show in vertical sections, modifications of the same
principle.
In Fig. 1A is the boiler heated by fire-box ; T is the superheater, a the outlet
for the combustion gases which gases serve to heat the superheater. H is the hot
air and steam cylinder. L is the air-compression cylinder which drives the com-
pressed air through pipe into the steam boiler, underneath the water-line. The
mixture of steam and air passes along pipe to the superheater T and the super-
heated mixture of bot air and steam passes out of the superheater along pipe -³ to
the power cylinder H.
The arrangement described up to the present is well known, and forms no part
of my invention, which consists of the protecting plate or piston z vertically adjustable
by rod n in the fire-box of boiler A. By means of this adjustable protecting plate a
greater or less portion of the heating surface of the fire-box may be exposed to the
action of the fire. When the plate is lowered the upper part of the fire-box is
prevented from coming in contact with the flames. According therefore to the
position of the plate z in the firebox, the quantity of steam generated in the boiler will
vary and the mixture of steam and air for driving the engine will contain a greater
or less percentage of steam.
When the protecting plate is placed lower down the combustion gases, instead of
circulating all over the fire-box are forced into the superheater along the passage a.
The steam percentage in the mixture is thus reduced and the superheater receives at
the same time more heat so that the engine works advantageously and more as a hot-
air motor. .
The working of the engine is thus:
The mixture of hot air and steam generated in the boiler A passes along piper³
into the superheater T where it is superheated. From the superheater it passes along
pipe to the power cylinder. The combustion gases from the fire-box pass out of the
same at a and into the superheater T from there, out at chimney . The exhaust
pipe is situated in the chimney for increasing the draught in the customary
manner.
The air is compressed in cylinder L and driven along pipe into the boiler; it is
led into the boiler under the water-line and in passing through the water becomes
saturated with steam thus forming the mixture for driving the motor. If less work
be required of the engine, the protecting plate z is lowered and vice versa, in the case
of greater working effect.
In Fig. 2 this regulating is effected by a sort of throttle valve arrangement v
operating in the outlet a instead of the plate z. By this valve it is possible to
regulate the passage of the combustion-gases by allowing them either to pass in
circulation round the fire-box or directly into the superheater T.
Fig. 3 shows a combination of both arrangements.
A plate is fixed in the fire-box the regulation of the heating surface is effected by
the piston ; there aro in this construction two flues a a¹ for the escape of the
combustion gases.
When piston b covers the opening a¹, the gases will pass directly
into the superheater; on lowering the piston to cover the upper end of opening a,
the gases circulate round the fire-box, finally, passing through a¹ into the superheater.
In this arrangement the steam and air work separately in cylinder N.
Steam passes from the boiler A along pipe to the upper side of the piston
driving the same downwards and exhausting into chimney through pipe .
The air compressed in cylinder I is driven into the superheater through pipe,
is there superheated and passes to steam cylinder N through pipe 20 exhausting
through into the chimney.
Fig. 4 shows a modification in which the superheater is heated by an extra fire.
Dated this 23rd day of November 1889.

page_text: COMPLETE SPECIFICATION.
Improvements in Motors Driven by a Mixture of Steam and Air.
I, WILHELM SCHMIDT, of 8, Plantagenstrasse of Halberstadt, in the German
Empire, Engineer 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 :-
My invention consists of an apparatus for regulating the generation of power in
motors driven by a mixture of steam and air, particularly in such machines, where the
firing is first employed to generate steam in a boiler and then the combustion gases
used to superheat eithor a mixture of steam and air or air only.
It is acknowledged by those skilled in this branch of engineering, that though a hot-
air machine is most economical the same is not practical in that the fire-box soon gets
ruined by the heat.
The object of the present invention is to regulate the power-generation that the
mixture of steam and hot air necessary for the normal working of the engine, shall
contain the most practical and economical proportions of both elements thus avoiding
the danger of overheating the fire-box. On the engine being driven above its normal
speed the proportion of steam in the mixture is increased the engine thus working less
economically as far as the actual consumption is concerned but with less wear and tear
of its parts.
If the speed of the engine be decreased under the normal speed the proportion of
steam in the mixture is decreased so that the engine is driven almost by hot air alone.
This regulation of the power generation consists therefore in regulating the pro-
portion of steam in the mixture of steam and air, and this is accomplished by varying
the heating surface of the boiler. At the same time the temperature of the mixture of
steam and air in the superheater is held constant. This variation of the heating
surface of the boiler may be effected either by allowing the combustion gases generated
in the fire-box to pass over a greater or less portion of the heating surface or by
dividing the combustion gases so that a part only of the same serves to heat the boiler
whilst the rest are conducted direct to the superheater.
In this manner it is possible to vary the proportion of steam in the mixture, or in
other words expressed, to use a greater or less percentage of the calorics generated in
the grate for the production of steam, at the same time keeping the temperature of the
superheated mixture nearly constant.
Particular attention is directed to the fact, that my improved motor retains its
advantages as hot air and steam engine, the temperature of the gases in the superheater
being so high, that the engine will work advantageously as a hot-air machine.
If on diminishing the normal speed of the engine such regulation does not take
place, so that in such case the engine works more as a steam.-engine i.e. with a greater
percentage of steam, the mixture of steam with compressed air will only be heated to a
slight degree and in consequence of the slight fall of temperature the effect will be
bad as a hot-air engine since the combustion gases will be too much cooled down on
the extensive superheating surface.
My invention has the object of avoiding this disadvantage; when the amount of
work required to be done by the machine is lessened or increased, I am able to keep
the temperature of the combustion gases sufficiently high by regulating the extent of the
heating surface of the boiler so that the machine will work advantageously as a hot-
air engine.
In order to make my invention more clear, I refer to the drawings sent in with
Provisional Specification, in which similar letters denote similar parts throughout the
several views.
Fig. 1 shows a vertical section of a motor driven by a mixture of steam and air; on
my system. Figs. 2, 3 & 4 show in vertical sections modifications of the same
principle.
In Fig. 1 A is the boiler heated by fire-box r ; T is the superheater, a the outlet

page_text: for the combustion gases which gases serve to heat the superheater. H is the hot air
and steam cylinder. L is the air-compression cylinder which drives the compressed
air through pipe into the steam boiler underneath the water-line. The mixture of
steam and air passes along pipe 2 to the superheater T and the superheated mixture
of hot air and steam passes out of the superheater along pipe to the power
cylinder H.
The arrangement described up to the present is well known, and forms no part of
my invention which consists of the protecting plate or piston z vertically adjustable by
rod n in the fire-box of boiler A. By means of this adjustable protecting plate a
greater or less portion of the heating surface of the fire-box may be exposed to the
action of the fire. When the plate is lowered the upper part of the fire-box is
prevented from coming in contact with the flames. According therefore to the
position of the plate z in the fire-box the quantity of steam generated in the boiler will
vary and the mixture of steam and air for driving the engine will contain a greater or
less percentage of steam.
When the protecting plate z is placed lower down the combustion gases instead of
circulating all over the fire-box are forced into the superheater along the passage a.
The steam percentage in the mixture is thus reduced and the superheater received at
the same time more heat, so that the engine works advantageously and more as a hot-
air motor.
The working of the engine is thus :
The mixture of hot air and steam generated in the boiler A passes along pipe 2
into the superheater T where it is superheated. From the superheater it passes along
pipe to the power cylinder. The combustion gases from the fire-box pass out of the
same at a and into the superheater T from there out at chimney 7. The exhaust
pipe is situated for increasing the draught in the customary manner.
The air is compressed in cylinder L and driven along pipe into the boiler; it is
led into the boiler under the water-line and in passing through the water becomes
saturated with steam thus forming the mixture for driving the motor. If less work
be required of the engine, the protecting plate is lowered and vice versa, in the case
of greater working effect.
In Fig. 2 this regulating is effected by a
ご
sort of throttle valve arrangement v
operating in the outlet a instead of the plate z. By this valve it is possible to regulate
the passage of the combustion gases by allowing them either to pass in circulation
round the fire-box or directly into the superheater T.
Fig. 3 shows a combination of both arrangements.
A plate vis fixed in the fire-box the regulation of the heating surface is effected by
the piston 6; there are in this construction two flues a a¹ for the escape of the com-
bustion gases. When piston b covers the opening a¹, the gases will pass directly into
the superheater; on lowering the piston to cover the upper end of opening a, the
gases circulate round the fire-box, finally passing through a' into the superheater. In
this arrangement the steam and air work separately in cylinder N.
208
Steam passes from the boiler A along pipe to the upper side of the piston driving
the same downwards and exhausting into chimney through pipe 7. The air com-
pressed in cylinder L is driven into the superheater through pipe 8, is there super-
heated and passes to steam cylinder N through pipe exhausting through r² into the
chimney.
Fig. 4 shows a modification in which the superheater is heated by an extra fire.
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
claim is :-
In motors driven by a mixture of steam and hot air, generated by a firing, the gases
of which pass firstly a steam-boiler and secondly a superheater in which compressed
air or a mixture of steam and compressed air is beated:
1. The method of regulating the temperature of the working gases in the super-
heater by distributing the effect of the firing in different manner to the steam-boiler

page_text: and to the superheater produced by averting a part of the firing gases more or less
from the heating surface of the steam-boiler or by bringing the fire-gases out of
contact with a various part of the heating surface of the steam-boiler for the purpose
as described.
2. The modification that instead of the variation of the effective part of the heating
surface of boiler a separate firing is used for the purpose of heating the superheater as
described.
3. The arrangement of a protecting plate z in the fire-box of the steam-boiler,
movable in vertical direction by the bar n (Fig. 1) for the purpose as described.
4. The arrangement of a throttle-like device v in the fire-box of the steam-boiler
(Fig. 2) for regulating the passage of the combustion gases, for the purpose as
described.
5. The arrangement of a protecting plate v in the fire-box of the steam-boiler in
combination with the channels a a¹ and the piston b (Fig. 3) adapted to shut off the
combustion gases, for the purpose as described.
Dated this 18th day of Angust 1890
WILHELM SCHMIDT.
By Rayner & Cassell,
Agents for the Applicant.