Year: 1899

page_text: Date of Application, 22nd Dec., 1899-Accepted, 31st Mar., 1900
I, KARL CHRISTIAN SCHMID, of Villa Waldhaus, Glücksburg, on the Baltic Sea,
in the Kingdom of Prussia and German Empire, Engineer 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:-
In caloric engines, compressed superheated air is the driving force, air taking
up heat in a more suitable manner than any other substance, and a physical
alteration of the substance does not take place; such for instance as in the pro-
duction of steam from water, in which a large amount of heat is absorbed to
change the physical condition. Therefore the effect obtained in such hot air
engines is greater than in other motors.
This invention relates to an engine which is constructed on the principle of hot
air engines, and the exterior of which is similar to an ordinary steam engine.
The essence of my invention is that the heating of the compressed air is effected
in a separate chamber called the superheater, which is of suitable construction,
connected to the engine, and allows of direct contact of the fire with the air during
continuous operation. At the same time the fire or furnace can be regulated, so
that only such air is admitted which is required for the slow and regular combus-
tion without forced draught. This part of the air is brought to a high tempera-
ture and then mixed with the other quantity of air, which is introduced into the
smoke chamber; the air is thus reduced to a temperature suitable for the
engine. Further the longitudinal axes of the compressing cylinders are in lines
produced from the longitudinal axis of the working cylinders of the engine, the
dimensions of the working cylinders and compressing cylinders belonging thereto
are such that in the course of expansion in sections 1, 2, 3 etc., the latter give
working results, each of which is equal to that of the other, and the whole
produces an even effort and an even rotary velocity. The utilisation of the quantity
of air delivered by the three compressors is similar to that in a steam engine,
the heated quantity of air expanding successively in the cylinders 1, 2, 3, etc.
should be noted, that the pistons of the compressing cylinders are fixed on the
same piston rods as the pistons of the corresponding working cylinders, whereby a
period of compression in the working cylinder is saved.
It
In order that this invention may be the better understood, I now proceed to
describe an example of how it may be carried into effect, reference, being had, to
the accompanying drawings and to the letters and figures marked thereon, such
drawings illustrating the invention adapted to a marine engine.
Figure 1 shows a part sectional vertical view of the machine.
Figure 2 is a plan.
Figure 3 shows a vertical section through the cylinder of the machine.
Figures 4 and 5 show the furnace door of the superheater in section and
elevation.
This engine is similar in form and construction to the steam expansion
engines, a base plate 6 carrying a crank shaft a and standards which support a

page_text: working cylinder d. Compressing cylinders f are arranged above the working
cylinders, intermediate pieces e being interposed. The compressors are operated
by piston rods g of the working cylinders, the pistons of the working cylinder and
corresponding compressing cylinder being fixed to one piston rod: This arrange-
ment is designed to save a compression period in the working cylinder, the com-
pressors performing the necessary function. The compressing cylinders have
hollow covers h containing chambers i, which serve to stiffen the covers and to
hold the suction valves j and pressure.valves k for the air which passes through
the compressing cylinders, the valves being spring pressed to ensure precise
closure. The objectionable space in the compressing cylinders is obviated by
rubber plates m fixed to the pistons 7 of such cylinders. This arrangement is
absolutely necessary, because without it the compressed quantity of air will not be
pressed completely into the superheater, but will partly expand in returning, on
account of the great expansibility of air. The rubber plates m are thicker than
the distance between the piston 7 in its end position and the cylinder cover h.
Further the relative diameters and dimensions of the working cylinders and com-
pressing cylinders are such that though the pressure of the air passing from the
first working cylinder to the second, and from the latter to the third changes,
the working effect is the same, the diameter of the cylinders being different. The
air compressing cylinders are connected to the compressed air receptacle n.
The compressing cylinders are jacketed, the inner cylinder o being of metal so as
to be a good conductor of heat, and adapted to be cooled outside with water. The
superheating of the compressed air is effected so that a part thereof is forced
through a layer of glowing or incandescent coal q, in the fire box
of the super-
heater, the air being heated to about 1500° F.
The strongly superheated air is then mixed in the smoke chamber r of the super-
heater, with the other compressed air, so that a temperature of the mixed quantity
of air is obtained, which shall be suitable for the machine. The superheater is
similar in form to a twin or combined steam boiler with built in fire boxes p.
The latter are constructed of specially good material and are closed against the
outer atmosphere by wrought iron covers s or similar devices. The feeding of the
fire and the withdrawal of the ashes, cinders, etc. is effected through orifices
adapted to be closed during working by the pressure of the air. The interior
of the fire box p is lined completely with fire bricks u, in order to conserve the
heat of the fuel in superheater and boiler and preserve their structure and further
to limit the amount of water surrounding the fire box 7. The latter is connected
by a neck or channel t, also lined with fire bricks, to the smoke chamber r, and
may be closed or separated from the latter by a cover, which is operated by a
spindle w with hand wheel ¹. The fire gases and other compressed air are
mixed in the smoke chamber, thence these gases pass to the upper heating
chamber a, where the gases collect and the ashes and soot particles are deposited.
The exit into the pipe service is covered if desired by wire gauze, so as to
prevent articles of ashes, smoke, etc. being carried into the pipes and engine.
The water which surrounds the fire box, in order to prevent the destruction
thereof by the fire, evaporates and is collected as steam in the steam dome,
arranged on the heating chamber and provided with safety valves. The steam
may be used for suitable purposes, and may serve as pressure regulator by
entering the compressed air service y of the machine. When for instance
a ship fitted with these engines, is manoeuvring and differences of pressure occur
in the compressed air service, steam is permitted to enter the service from the
dome. When the pressure of the steam in the boiler of the superheater rises
above a desired degree, say above 10 atmospheres it passes through the valves,
which are suitably constructed for this purpose, into the main compressed air
service When the pressure rises and the steam enters into the main service
and thus into the machine, it will continue to do so until the difference of pressure
is equalised. The boiler and heating, chamber. are. of course provided with the
required fittings, and apertures are provided for inspecting the fire and cocks

page_text: for blowing out collected ashes. The regulation of admission must be such
that the coal will burn uniformly but not with forced draught.
The operation of the engine is as follows.
A ship provided with such an engine, and which carries (besides the super-
heater belonging to the engine) an auxiliary boiler to produce the steam for
the winches, pumps, etc., may be got ready in about three hours. The fire is
ignited on the grate of the superheater, the steam air pump for pumping up
the superheater is started, and all valves on the fire box cover of the super-
heater are closed. When after a little time the manometer of the compressed air
dome indicates the required pressure, the auxiliary valve on the same is opened
and part of the superheated air is conducted to the heating shell or jacket of the
engine. The escaping compressed air is always made good by the steam air
pump, thus causing strong air circulation in the furnace. When the machine
has been well heated, the working thereof may commence; during the first
revolutions the compressing cylinders are allowed to work empty, the pressure
service thereof being connected for the purpose with the free atmosphere.
The working cylinders o of the compressors are provided with cooling water
by a pump operated for this purpose from the engine. This cooling water enters
through a pipe service into the lower part of the cylinder jacket, and goes over-
board after passing the water chamber. Besides this indirect cooling of the
cylinders of the compressors, direct cooling takes place by injection or
spraying. For this purpose a number of extremely fine holes are made at half
the height of the inner cylinder o, which permit the cooling water to enter the
compressing cylinder. Thus a small amount of cooling water enters during
the second part of the suction period and during the first quarter of the com-
pression period and absorbes by evaporation during the later 3/4ths time of the
compression period a part of the heat of compression.
This arrangement effects a considerable saving of coal, and obviates frequenting
of coaling stations, further the number of attendants required is much less,
and there are other disadvantages connected with great consumption of coal.
which are reduced. Further the amount of feed water and condensation required
is decreased.
Having now particularly described and ascertained the nature of this invention
and in what manner the same is to be performed, we declare that what we
claim is-
1st. A caloric expansion engine in which the compressing cylinders are situated
in the axial direction of the working cylinder of the machine, and the pistons
of the working cylinder and the compressing cylinder are fixed to one piston rod,
so that the compressors save a compression period in the working cylinder, sub-
stantially as described.
2nd. In a caloric expansion engine as claimed in Claim 1, the heating of the
compressed air in a separate superheating chamber, substantially as described.
3rd. In a caloric expansion engine as claimed in Claim 2, a superheater
consisting of two combined heating chambers, fire boxes in the lower chamber
adapted to be surrounded by water; all adapted so that air required for the
combustion of the fuel at atmospheric pressure can enter beneath the fire
grate, and is heated while passing through the layer of burning fuel, then mixed
with the compressed air in the smoke chamber to enter the upper chamber at
temperature suitable for passing thence into the engine as a motor fluid, sub-
stantially as described.
4th. A caloric expansion engine as claimed in Claims 1-3, in which steam
formed in the lower part of the superheater enters the main service of the
engine automatically, when the pressures of the steam becomes too high or when
the pressure in the compressed air service is reduced, in order to regulate and
equalize the differences of pressure thus arising, substantially as described.
5th. A caloric expansion engine as claimed in Claim 1 in which the com-

page_text: pression cylinder is jacketed to form a chamber for conducting water around the
inner cylinder o in order to cool the same, substantially as described.
6th. A caloric expansion engine as claimed in Claims 1 and 5 having an inner
compressing cylinder o which is finely perforated for the purpose of direct
introduction of the cooling water into the compressing cylinder, so that water
is sprayed during the second part of the suction period and the first quarter
of the compression period in order to absorb heat of compression during the
period of compression, substantially as described.
7th. A caloric expansion engine as claimed in Claims. 1-5 in which the pistons
of the compressors are provided with an elastic lining m, thicker than the space
remaining at the end position between the piston / and the cover h in order
to fill up this empty space, substantially as described.
Dated this 22nd December 1899.
FELL & JAMES,
Agents for the Applicant.