A Process for Producing Motive Work from the Combustion of Fuel.
Year: 1892

page_text: Date of Application, 14th Apr., 1892
Complete Specification Left. 27th Aug., 1892-Accepted. 8th Oct.. 1892
T
PROVISIONAL SPECIFICATION.
A Process for Producing Motive Work from the Combustion of Fuel.
I, RUDOLF DIESEL of Kurfurstendamm 113, Berlin, Prussia, Engineer, do
hereby declare the nature of this invention to be as follows:-
This invention relates to a process for producing motive work by means of heated
air, combustion gases or by means of a mixture of these gases with each other or
with other gases and vapours in such a manner, that first a quantity of air, very
large compared with the quantity of fuel, is employed, which is compressed to so
high a degree, that by the expansion subsequent to the combustion the air is cooled
about to atmospheric temperature, and that into this quantity of air, after its
compression, fuel is gradually introduced in such a manner, that the combustion heat
is converted immediately, by the expansion of the previously compressed air, into
work, and that, by the combustion of the gradually introduced material, a deter-
mined temperature, still possible without cooling from without, is not surpassed.
The final purpose of this process is to avoid the two large sources of loss of heat
inherent to all the hitherto known motor engines: as first any transmission of heat
to the outside during the working period, and secondly any loss of heat by the
exhaust gases is excluded in my new process.
From these points of views the process will be examined hereinafter, upon which
are based the hitherto known motor engines, viz. :—
The process in the furnace gas engines consists in introducing under pressure
combustion air into a closed fire place, and in causing the produced combustion gases
to expand in performing work.
As the air is always in presence of larger quantities of glowing fuel, just the
quantity of air, which theoretically is necessary for combustion (round 12 kilo-
grams of air per one kilogram of coal) comes to action, and the combustion gases
do not contain any excess of unburnt air or, only small accidental excesses
thereof.
In this kind of combustion, temperatures are necessarily produced, which are
higher than 2,500° C. These temperatures require an energetic cooling of the walls
of the furnace and of the working cylinders, as otherwise the engines are not
durable.
This cooling causes the first considerable loss of heat.
Air is compressed in these engines ordinarily to 3 or 4 metric atmospheres. At
the expansion from this pressure to the atmospheric pressure, air is cooled only for
100 or 130° C.
In spite of the expansion and of the energetic cooling of the cylinder the gases
are therefore after the expansion still in a very hot condition.
This heat of the exhaust gases constitutes the second great loss of heat.
The thermal balance of these motors in round numbers is therefore as follows.
1. Heat equivalent of work done, about
2. Heat absorbed by the cooling water, about
3. Heat of the exhaust gases
99
6%
42
46%

page_text: All the improvements, which have been attempted, have for their purpose to
reduce the losses above mentioned under 2. and 3. (but nearly without any success)
by trying to utilise in the machine the heat absorbed by the cooling water or the
heat contained in the exhaust gases.
An improvement of this process is unimaginable as the principal idea of the
process, the closed furnace, has not been abandoned, for :-
1. the quantity of air per one kilogram of coal will differ only insignificantly
from the theoretical quantity, it is therefore too small,
2. so high compressions, which are capable of rendering profitable afterwards the
high temperature fall (by expansion) are impossible, because a hot furnace and the
cylinders and distributing organs working at so high temperatures cannot endure
such pressures,
3. because a continuous cooling of furnace and cylinder is required,
4. because the exhaust gases are always in a very hot condition.
The process in gas (petroleum) motor engines consists in mixing the gaseous or
liquid fuel with the air of combustion, in compressing this mixture, in igniting the
same and in causing it to expand.
The limit, where the mixture becomes too diluted for being still capable of
taking fire is at 20 or 25 kilograms of air or combustion gases per one kilogram of
gas or of petroleum, that is to say nearly two times that of the furnace gas
engines. On the other hand the used fuel is considerably richer in caloric than in
the last mentioned engines.
It results therefrom that so high temperatures are produced, that a cooling of
the cylinder walls and of the distributing organs is unavoidable.
For the same reason the gases escape still in a very hot condition.
The thermal balance of these motor engines is about as follows:
Total
100%
This balance is more advantageous than that of the before mentioned engines, but
the two large sources of loss of heat exist still always as formerly and they could
not essentially be reduced in spite of various attempts.
An essential improvement is here likewise impossible as long as the principal
idea of the process, viz. the mixture of air and fuel has not been abandoned for:
1. the introduction of a larger quantity of air is limited by the capacity of the
mixture to take fire,
2. higher compressions cannot be applied on account of the construction, as owing
to the high temperatures the limit of tightness of the organs will very rapidly
be reached. At higher compressions (20 or 30 atmospheres) the mixture takes fire
spontaneously, in particular when hot gases resulting from precedent strokes are
admixed. But even compressions of such a height are still quite insufficient for
utilising by expansion the existing temperature falls.
3. A cooling of the cylinder walls is absolutely unavoidable in these motors.
4. The great heat of the exhaust gases cannot be eluded.

page_text: backward stroke of the piston, consequently not into a constant space, so that the
produced heat is entirely or partially absorbed by the increase of the volume,
respectively by the external work simultaneously produced, and so, that the
prescribed maximum temperature is not surpassed, and that finally during this
combustion no heat is led away to the outside.
Only after this exactly regulated process of combustion, expansion of the whole
quantity of gas takes place without any other supply of heat, and this in such a
manner, that the final temperature reaches as nearly as possible or entirely the
atmospheric temperature, so that there is no loss of heat caused by the exhaust
gases.
It is easy to show that the most favourable result is obtained, when the backward
stroke of the piston has been effected during the gradual supply of fuel in such a
manner, that the combustion took place at a constant (maximum) temperature.
As the quantity of fuel, in order to utilise rationally its calorific power, is
extremely small compared with the quantity of air, the gases produced by com-
bustion may be neglected, and we are therefore in presence of a nearly pure
hot air engine, the air of which is not heated from outside, but by gradual
(successive) introduction of fuel in the above described manner into the mass of
air. This machine realizes almost exactly Carnot's process and this between.
high difference of temperatures.
In carrying out this process it has been found, that maximum temperatures of
from 600 to 1200° C., may easily be realised, so that thermal effects of from 70
to 80% may be attained.
The compression of air may take place also without any injection of water;
this does not modify at all the character of the process. But in this case the
exhaust gases contain still some amount of heat, which however may be regulated
in such a manner, that it is not much more than the heat taken off at the
compression with injection of water. The combustion itself may also be
regulated in a somewhat other manner than with an entirely constant temperature.
All this does not modify the main feature of the process.
It is evident, that the fully described process, which takes place at a constant
temperature of combustion, is to be considered as the most perfect of all.
The above described process for producing motive work can be modified in
still maintaining the main features of the process, in such a manner, that the
final temperature of the exhaust gases differs from that of the atmosphere. The
so obtained exhaust gases can be employed for heating and cooling purposes.
I shall proceed to describe hereinafter a simple machine constructed according to
this process.
The machine consists of a single acting cylinder with plunger piston, an air-inlet
valve, an escape valve for the exhaust gases, and an introducing device for gradually
supplying fuel, finally an injection-nozzle for the water. The piston is disposed in
such a manner, that at the end of its stroke it cuts off an air chamber having a
determined capacity.
This machine works in the following manner :
1. Forward stroke of the piston and suction of atmospheric air at atmospheric
temperature through the inlet-valve.
2. Backward stroke under injection of water into the cylinder, consequently
compression, at constant temperature, of the air sucked up; then cutting off of
the water and completion of the compression to round 230 atmospheres, which
pressure corresponds to the chosen inaximum temperature, say 800° C., the
temperature being in this case higher than the temperature of ignition of the
fuel (pulverised dry burning coal).
3. Second forward stroke under kinematically, according to the piston stroke,
controlled, gradual supply of fuel, and spontaneous ignition of the fuel in the air
mass, which has been compressed at the precedent backward stroke and is now
expanding; then cutting off of the supply of fuel and further expansion of the
air and of the combustion gases to atmospheric temperature in avoiding at the

page_text: radiation, uncomplete combustion and escape of the combustion gases without
performing work, finally losses of temperature-fall by transmission to a vehicle.
Here also high compressions cannot be utilised by expansion as cylinder walls
heated to so high temperatures cannot sustain so high pressures and because the hot
working pistons etc. cannot be constructed sufficiently tight.
Energetic coolings are equally here required.
These machines have given the most unfavourable results and are at present
nearly abandoned.
It results from the above considerations, that no one of the above mentioned
processes is capable of essential improvements.
Differing from all the hitherto known processes the object of this invention
consists of the hereinafter described process for producing motive work from the
combustion of fuel.
To carry out this process so high a multiple of the quantity of air theoretically
necessary for combustion is employed, that during the combustion a maximum
temperature, previously determined and still admissible for the practical working
without leading heat away, is not exceeded.
The above mentioned maximum temperature, to be chosen at will, is so deter-
mined that the average temperature of the cylinder walls, including the expansion
period and other parts of the process (suction of air etc.) is so, that any artificial
cooling of the cylinder walls, piston etc. is excluded, but that on the contrary the
cylinder must be protected against any loss of heat by insulating same.
In taking these circumstances into consideration temperatures are employed in
practice, which are about between 600 and 1200° C.
The quantity of air per one kilogram of fuel is dependent on the calorific power
of the fuel and is scientifically so calculated, that at the combustion, the maximum
temperature determined according to the above explanations, is not exceeded.
These weights of air are considerable multiples of the theoretical air quantity or
of the admixture, which can be used in gas motor engines.
This quantity of air found in the above described manner for carrying out the new
process is compressed to so high pressures, that the expansion subsequent to the
combustion (which hereinafter will still be described) produces, without giving off
heat to the outside, so high a cooling of the gaseous mass, that the latter is cooled
to about atmospheric temperature, i.e. that it escapes without containing any amount
of heat or only a small amount of heat.
This compression is the most perfect, when first water is injected, that is to say
at constant temperature, and when it is completed after this without injecting water,
to the determined maximum temperature.
As the expansion subsequent to the combustion takes place between high
differences of pressure, the above mentioned high cooling of the expanding gases
takes place without any artificial cooling from without and the said gases may be
caused to escape without containing any amount of heat or only with a small loss of
heat.
According to the maximum temperature above marked as still admissible, the
required pressure of compression is of 100 aud more atmospheres. At this com-
pression the temperatures become usually so high that the fuel employed is
spontaneously ignited when it comes in contact with the compressed air.
In the air quantity above more exactly determined by weight and pressure of
compression, the combustion takes place in the hereinafter more fully described
manner:
The very small quantity of fuel exactly measured to its calorific power pro stroke
(the fuel may be in a solid, liquid or gaseous condition) is introduced by means of
a peculiar mechanism.
In carrying out the process the solid fuel, for the purpose of introducing same
gradually, must be, according to the nature of the fuel, either pulverised or
converted into a gaseous state.
This introduction does not take place at once, but gradually during the

page_text: same time any transmission of heat to the outside during the whole second
forward stroke. During the second forward stroke the chosen maximum tempera-
ture (800° C.) is not exceeded, because the heat of combustion is converted in
the status nascendi into external work. During the whole second forward stroke
any loss of heat to the outside is prevented, because the cylinder walls are
insulated.
4. Second backward stroke of the piston under expulsion of the gases through
the escape valve, the expelled gases having the atmospheric temperature.
The true process of combustion requires only 25th of the volume of the whole
cylinder. It is evident, that by the subsequent expansion of the compressed air
to very low temperatures and by the expulsion and suction of air at atmospheric
temperature and by the injection of water during the commencement of the
compression, the average temperature of the cylinder walls is lower than that in
any ordinary steam engine. The consequence thereof is, that not only no cooling
is required, but on the contrary, a careful protection against radiation of heat.
In consequence of this low average temperature, the usual ordinary lubrication
with any suitable material may be applied in this machine.
The residues of combustion, which are suspended in very small quantities as a
very fine dust in the quickly moved and whirling air are evacuated together with
the exhaust gases.
The distributing mechanism of this machine with a single cylinder chosen as an
example is limited to a suction valve and an escape valve for the air, the two
working only at about atmospheric temperature.
There is in addition to this still the device for introducing the solid pulverised
fuel chosen for the example.
In the present example it is assumed, that the coal powder falls out of a
funnel into the groove of a revolving cock, the speed of revolution fixing the
space of time, during which the powder falls gradually into the cylinder, and
consequently into the compressed air, and thus the duration of the combustion.
The revolving cock serves at the same time as a closure of the cylinder towards
the funnel containing the fuel.
On account of the maximum temperature of 800° C. chosen in the above
example and of the adopted dry burning and readily inflammable coal powder
an igniting device is not provided. The compression of air is produced by the
plunger piston rapidly pushed in and returning immediately after the compression,
without the agency of distributing organs (owing to the development of heat)
under higher pressure than the piston effected its forward stroke.
As during the compression in the cylinder, the air is to be considered as a cushion,
and as the backward stroke of the piston takes place under a pressure equal to the
pressure of compression and having the same direction; shocks are not produced, as
it is the case in gas motor engines, when an explosion takes place.
The process may of course be carried out in several distinct spaces or cylinders ;
the compression of air may be effectuated by means of a special pump feeding an
intermediate reservoir, from which air is taken for the further purposes intended
according to this invention. The compression as well as the expansion may be
simple or multiple.
The above described machine with one single acting cylinder, illustrating by way
of example in which manner the process may be performed, has only one working
course per 2 revolutions; two or more cylinders may be coupled together with
cranks secured in a displaced manner to the shaft, so that the working periods
follow more rapidly each other.
The cylinders may be single or double acting, and the pistons may be arranged as
plunger pistons or as disc-pistons. The side of the stuffing box of the cylinders may
be used for these periods of the process, which take place only at a low pressure
(suction, expansion), while the opposite side may be employed for the higher
pressures (compression and combustion).
The construction of the distributing mechanism is in particular very simple, as the

page_text: inner organs work only at quite normal temperatures and pressures; for the distribu-
tion all known organs such as valves, slides, cocks and the like may be used. The
exterior distributing mechanism and the crank mechanism do not differ at all from
other similar known constructions.
The device for gradually introducing fuel is dependent on the peculiar properties
of the employed material for solid pulverised substances in lieu of the described
revolving cock a powder-nozzle or a small pump may be used; in the case of liquid
fuel an atomizer or a small pump may be employed; for gases equally a small
pump or any other device may be used allowing to introduce the matter in a regular
and gradual manner.
As all known mechanisms can be employed in these engines I do not prefer a
special device and for this reason I do not illustrate the same by drawings.
In particular I beg to remark, that the thermal results of these motors are
independent on the nature of the employed gas. It is sufficient to maintain the
quantity of air, which is necessary for the combustion.
The other considerable quantity of gas, which serves only as a vehicle to the
caloric, may be composed of formerly already used gases of combustion, of admixed
foreign gases and vapors, also of water-steam, without modifying in any way the
result. It results therefrom, that also closed engines can be constructed, which at
each stroke suck up only the small quantity of fresh air necessary for assuring
combustion, but which work (a small expulsion excepted) always with the same
gaseous mass.
An essential advantage of these motors working according to the new process,
consists in the fact, that thermal motor engines of this construction have considerably
smaller cylinders than all the other hitherto known engines, steam engines com-
prised.
The starting of the motor may be effected by the aid of a reservoir containing
compressed air, which during the working is kept always in a filled state, or the
engine may be put in motion by introducing and igniting a small quantity of an
explosive substance.
The advantages of this new thermal motor engine consist in first place of the
considerable saving of fuel, the consumption of fuel is only a small fractional part
of that of all the actually known motor engines. This advantage is of proeminent
economical importance.
In second place the advantage consists of the absence of steam boilers, of open
furnaces, of chimneys etc. and in consequence thereof, any exhaust of smoke, steam
and the like will be avoided. This advantage alone would justify already the
introduction of the motor in substitution of the actually used engines.
There is still moreover to point out the independency of these motor engines on
central establishments such as gas works, electrical works, water works etc. (the
injection water constitutes only a small fractional part of the water required by
steam engines and, as above explained, it may also entirely be dispensed with at the
cost of the effect) furthermore I beg to mention its extraordinary smallness in com-
parison with all the other actually known motor engines and in consequence thereof
its mobility and easiness of transport.
All these qualities render the new motor particularly suitable for small industries;
with the possibility of uncentralizing these industries in lieu of accumulating them
in large central places, so that this new motor engine offers also advantages in
political, economical and hygienic respect.
It may scarcely be necessary to mention, that the absence of boilers and furnaces
will be of important influence on the construction of locomotives and marine engines,
and for the same reason the new motor engine may particularly advantageously be
employed for tramways and carriages.
Dated this 14th do of Anril 1809
ABEL & IMRAY,
Agents for the Applicant,

page_text: COMPLETE SPECIFICATION.
A Process for Producing Motive Work from the Combustion of Fuel.
1, RUDOLF DIESEL, of Kurfurstendamm 113, Berlin, Prussia, 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 :-
The working process of the hitherto known motor engines using the combustion
heat of fuels directly in the cylinder for performing work is characterised by the
theoretical indicator diagram shown in Figure 1 of the accompanying drawings.
On the curve 1, 2 a mixture of air and fuel is compressed, at point 2 the
combustible mixture is ignited; by the now following combustion a sudden increase
of pressure from 2 to 3 is produced which is accompanied by a very considerable
increase of temperature; the explosion like combustion is such a quick one, that the
stroke of the piston during the combustion is nearly zero. At point 3 the
combustion is essentially finished. From 3 to 1 an expansion takes place in
performing work, whereby pressure and temperature of the combustion gases
decrease again.
In all hitherto known combustion processes, the combustion process is left to
itself as soon as the ignition takes place, the pressure and the temperature of the
same are not regulated or controlled during the proper proceeding of combustion
in proportion to the then existing volume of the body of air.
From this wrong proportion between pressure, temperature and volume result
in all these processes the following inconveniences.
1. The temperature produced by the combustion is always so high, that the
attainment of such a mean temperature of the contents of the cylinder that will
render possible the maintaining the parts tight, the lubrication and in general the
practical working of the machine, can be obtained only by energetically cooling
the cylinders or furnace-walls respectively, wherefrom will result a great loss of heat.
2. The combustion-gases are insufficiently cooled by the expansion and they
escape while still in a very hot condition, which constitutes a second great loss of
heat.
Also, those motor engines in which pure air is compressed from 1 to 2 (see
Figure 1) and fuel is injected suddenly in the neighbourhood of point 2 while
igniting the same simultaneously, show the increase of pressure 2, 3 combined with
considerable increase of temperature.
The same takes place in motor engines which drive the compression to so high a
degree that the mixture is ignited spontaneously by the temperature produced by
the compression. The igniting points of the most part of fuels are very low, (of
petroleum for instance at from 70° to 100° C.); when by the compression this
temperature has been produced, which will be the case already at low pressures,
(in the case of petroleum at a pressure inferior to 5 atmospheres, in the case of gas at
about 15 atmospheres) the ignition will take place spontaneously; the combustion
following the ignition here also raises the temperature very considerably and produces
the increase of pressure 2, 3 (see Figure 1). The highest temperature or combustion
temperature occurring during the combustion is entirely independent of the burning
or igniting points, which depend only upon the physical properties of the fuel.
In practice the explosion or combustion process requires a material time, for this
reason the line 2, 3 is not quite vertical, but, as shewn in dotted lines, somewhat
inclined with the rounded transition at 3.
The characteristic feature of all these processes remains however :—
Increase of the pressure and of the temperature by the combustion and during
the latter, and the subsequent performance of work by expansion. The process

page_text: The new process hereinafter described differs completely from all the other
hitherto known processes. It is represented in the theoretical diagram shown in
Figure 2. In this process pure atmospheric air is compressed in a cylinder
according to curve 1, 2 to such a degree, that by this compression from the
beginning before any combustion takes place, the highest pressure of the diagram,
and by this at the same time the highest temperature is produced, that is to say,
the temperature at which the subsequent combustion has to take place namely the
combustion temperature (not the burning or igniting point).
If it be desired for instance that the later combustion shall take place at a
temperature of 700° C., the pressure will be of 64 atmospheres; for 800° C. the
pressure will be of 90 atmospheres and so on.
Into this compressed body of air is then gradually introduced from outside finely
divided fuel, which ignites as the air mass is heated by compression far above the
temperature necessary for inflammation, simultaneously with the gradual introduc-
tion of fuel an expansion of the body of air takes place, which is regulated in such
a manner that the cooling caused by the expansion destroys at each moment the
heat produced by the combustion of the several introduced particles of fuel, owing
to this the combustion shows its effect not by an increase of temperature but solely
by work done, and also not by an increase of pressure as it takes place in conse-
quence of the simultaneous expansion at decreasing pressure.
The combustion takes place according to the curve 2, 3 (Figure 2) consequently
it is not a sudden one, but it takes place during an exactly prescribed period of
admission of fuel during the piston stroke w, which period of admission is regulated
and determined by a distributing device and which has for its result, that the
combustion proceeding after the ignition is not left to itself, but is regulated during
its whole duration in such a manner that pressure, temperature and volume are in
a prescribed proportion. It is the duration of this admission period which is fixed
by the distributing device; the governor also influences the duration of this period
which, as with the admission period of steam-engines, may be of 10% and more of
the piston's stroke but under certain circumstances may be reduced to a less a
percentage of the pistons stroke.
If air is allowed to expand without any supply of fuel, the curve 2, 1 would be
formed i.e. the expansion would do no work, but give back simply to the piston the
previously employed work of compression; but by gradually introducing fuel a
pressure difference p is formed at any place between the curves 1, 2 and 2, 3, in
consequence whereof the expansion work becomes greater than the compression
work and a useful effect is performed.
At point 3 of the diagram the supply of fuel ceases and the expansion of the
combustion gases goes on automatically and performing work according to curve 3, 4.
As the pressure at point 2 for producing the highest temperature was very high
and is still very high at point 3, the expansion will produce from 3 to 4 so strong
a cooling of the gas volume that in leaving the engine it will carry away only
insignificant quantities of heat.
Here also the corner 2 of the diagram will not be sharply formed in practice, it
will rather assume the rounded form shown in dotted lines; also in the course of 4
the present Specification terms such as "combustion without increase of tempera-
ture and the like must not be understood in the exact mathematical sense, as regard
is to be paid to practice. I wish only to have it understood that in the new process
the highest pressure and the highest temperature are produced essentially not by
combustion but by mechanical compression and that by the combustion and during
the same
an increase of temperature does not take place at all or only to an
insignificant degree, at all events insignificant if compared to the heating by
compression.
=
The characteristic feature of the process remains always as follows:-
Increase of pressure and temperature up to about its maximum not by com- 5
bustion, but prior to the combustion by mechanical compression of pure air and
hereupon subsequent performance of work by gradual combustion during an

page_text: exactly prescribed part of the expansion, characterized by the period of admission
of fuel exactly determined by the distributing device.
According to what has been said above, the combustion itself, in opposition to
all the hitherto known processes of combustion, does not produce any increase of
temperature, or at least only an unessential one; the highest temperature is
produced by the compression of air; it is therefore under control and will be kept
correspondingly in moderate limits; as moreover the subsequent expansion cools
the body of gas in a very high degree, it is obvious, that no artificial cooling of the
cylinder walls is necessary; that rather the mean temperature of the cylinder
contents necessary for keeping the parts tight and lubricated, and in general for the
practical working of the engine, is obtained solely by the process itself, whereby
also it differs from all the known processes.
Figure 3 shows a further modification of the process consisting in that the first
period of the air-compression takes place under injection of water, whereby first the
flatter curve 1, 2 is formed, and that then only the second part of the compression
without water-injection takes place according to the steeper curve 2, 3, whereupon
the combustion and expansion is conducted exactly in the same manner as in
Figure 2. By this means I attain considerably higher compression-pressures than
in Figure 2 without reaching too high temperatures which would require a cooling
of the cylinder.
In consequence of the greater fall of pressure the subsequent expansion from
3 to 4 cools the body of the gas to a greater extent; the exhaust gases escape
therefore in a colder condition than in Figure 2 and carry away still less heat;
this modification of the process gives therefore higher useful effects.
The exhaust gases may in this case be cooled even below the atmospheric
temperature and be then led away to be utilized for refrigerating purposes. The
result of the new process compared with all the other hitherto known processes is
a considerable saving on fuel, the work done remaining the same.
Every kind of fuel in any state of aggregation is suitable for carrying out the
process.
In the case of liquids or gases or vapors respectively, a jet of gas or liquid is
dispersed under pressure in as divided a state as possible into the body of
compressed air during the period of admission and as long as the latter lasts. Solid
fuels may be introduced in a pulverulent or dust-like condition, such solid fuels
which in heating agglomerate, or are unsuitable for any other reasons for being
used, are previously gasified. Liquid fuels may be converted previously into
vapour and then introduced in this form. Matters inflammable with difficulty such
as anthracite and the like, may be mixed with readily inflammable substances such
as petroleum and the like.
The process may be carried out in a single or double acting, vertical or horizontal
cylinder with one or more pistons working on the same flywheel-shaft and with one
or more stages of compression and expansion. Figures 4 and 5 show a motor
engine with single acting cylinder C with plunger piston P, the details of which
are constructed for high pressures. Piston P is connected by the guide a,
connecting rod band crank e with the fly-wheel-shaft d in the usual manner.
The fly-wheel-shaft drives at f by means of hyperbolic toothed wheels the
vertically upward extending shaft 9 carrying the governor and driving the
horizontal distributing shaft h.
To the latter are secured cams i which at the right moment open the air-valve A
(Figure 5) and the fuel valve k. The gear for the latter is clearly shown in
Figure 4; for the valve A it is of similar construction. As soon as the cams i
are out of action, the two valves are pressed down against their seats by the
springs l.
The process which according to this invention takes place in the cylinder C is
as follows:-
1. Downward stroke of piston P produced by accumulated vis viva in the flywheel
from the preceding working strokes. Atmospheric air is sucked in through the open

page_text: valve A into the cylinder C, the lowest position of the piston is shown in dotted
lines in Figure 4 and marked with 1.
2. Upward stroke of the piston P produced also by the accumulated vis viva of
the fly wheel, the valve A being now closed. The air previously sucked in is
compressed to such high pressures, that the temperature at which later the
combustion has to take place, namely nearly the highest temperature of the process,
is produced by this compression alone.
This compression pressure is determined by the prescribed combustion tempera-
ture and it is produced by the piston P, which, in its dotted end position 2
(Figure 4) will have compressed the quantity of air drawn in to the volume
corresponding to the prescribed pressure.
Such pressures cannot be attained if from the beginning fuel is admixed to the
air such as for instance in gas- and petroleum-motors as in this case already at
low pressures at intermediate points of the stroke namely as soon as the igniting
point of the fuel has been attained (this temperature being in general very low)
ignition would take place, and in consequence thereof interruption of the prescribed
compression by combustion would ensue so that in such cases it would be impossible
to carry out the prescribed process.
3. Second downward stroke of the piston P or true working stroke.
The hopper B contains pulverised coal introduced through the lateral opening n
shewn in Fig. 5. This hopper is shut off from the cylinder C by means of a
cock D rotated by the distributing shaft by means of the hyperbolical wheels shown.
The cock is shewn to a larger scale in four positions at Fig. 6; it is provided
with a lateral groover which, when in its upper position a is charged with coal
dust arriving from the hopper B; when the cock revolves, the groove turns towards
the inside of the cylinder (see b); in this position the pressure between the interior
of the cylinder and the groove is first equalised as the loose powder does not offer
any obstacle thereto in the other positions, one of which is shewn at c, the cock
allows the coal dust to fall into the compressed air; owing to the high temperature
of this air the coal takes fire and produces heat, which immediately in the moment
of its production is converted into work by a corresponding forward movement of
the piston.
The introduction of the powder takes place gradually in a prescribed space of
time in a manner similar to the sand in an hour glass, the size of the inlet slit
determines the duration of the introduction during the prescribed period of
admission of the fuel. The quantity of coal is determined by the size of the groove
of the cock. These inner organs in combination with the outer distributing device
insure that the prescribed duration of admission is complied with and that the last
coal particles only pass in when the piston has arrived at the end of the period of
admission.
The gradual combustion just described consequently continues until the piston
has arrived in its position 3 (dotted line in Fig. 4). At this moment the groove of
the cock is emptied and passes in front of the inlet slit, the admission of fuel is
thereforo stopped. The air mixed with the combustion gases continues to expand
automatically, in performing work, while the whole gas body, owing to the great
fall of pressure, is cooled very considerably, and this solely by doing work and
without cooling the cylinder walls, the latter being suitably insulated by a jacket s
Fig. 4.
4. Second upward stroke of the piston P produced by the vis viva of the fly
wheel.
The gas body is driven out as by a blow pipe, through the valve A (or through
a separate blow off valve) into a pipe p Fig. 5 leading it away; as the said body
has been cooled already previously nearly entirely by expansion, it carries away, as
a loss, only insignificant quantities of heat. The residues of the combustion are
contained in very small quantity in the form of a fine dust suspended in the rapidly
moving and whirling gases of combustion and are consequently also simply
blown out.

page_text: Alter GULS Seconu upward stroke the above described cycle of operations 15
repeated.
The motor is started by introducing through the opening * (Fig. 4) compressed
air from a store-vessel by means of a pipe connected therewith at g. The store
vessel is kept filled with compressed air by the motor during the working. At qa
special device may be arranged by means of which the motor may be started by
igniting a small quantity of explosive matter.
The regulating of the machine is effected by means of a governor E of any
known construction, which, when the engine runs too fast, prevents the fuel from
falling from the hopper into the groove. The small coal valve k is opened at each
second revolution by means of the cam i and the rod m, and allows a certain
quantity of coal to fall into the groove.
When the machine works too fast the rod n connected to the governor sleeve
moves the rod m so as to bring the roller attached to the lower end thereof out of
the scope of the cam i; the valve & therefore remains closed and no coal falls into
the cock, and in consequence also not into the cylinder, until the normal speed has
been re-established.
The above described motor may also be arranged as a horizontal engine; in this
case the construction of the parts is not altered but only their position. In lieu of
a plunger piston a disc piston may be employed, so that the cylinder becomes a
double acting one.
In the described construction the engine has, as in most of the gas motors, only a
working stroke at every second revolution of the engine shaft. But two or more
such single acting cylinders may be coupled to the same fly wheel-shaft, whereby
the working of the motor becomes more uniform. The compression of the air as
well as the expansion of the combustion gases may take place by stages as is shewn,
by way of example in Fig. 7.
In this Fig. the valves are indicated only diagrammatically, the frame, the
connecting rod, the fly wheel etc. are omitted; all these parts are exactly the same
as shewn in Figs. 4 and 5. There are in Fig. 7 two cylinders C with plungers P,
that is to say, two combustion cylinders, the construction, distributing devices etc.
of which are identical to those of the cylinder represented in the Figs. 4 and 5.
These two cylinders C are connected by means of the controlled valves b to the
two sides of a larger central cylinder B; by the two valves a which are also
controlled, the two combustion cylinders are in communication with the air
vessel L.
The cranks of the two cylinders C are arranged in the same position, and they
form with the crank of the central cylinder B an angle of 180°.
The working of this construction is as follows:-The piston Q draws in air by
its upstroke through valve d, compresses the latter by its down stroke to a certain
pressure and then forces the air through valve g to the air vessel L.
The lower part of the central cylinder therefore only serves as an air pump and
effects the preparatory compression of the combustion air.
This preparatory compression should go only to such an extent, that the heating
of the air produced by this compression remains between moderate limits.
Water nozzles are arranged still at g g through which during the preparatory
compression, water may be injected at a low degree. This water is then discharged
again through the cock of the air vessel.
The process may be carried out either with or without injection of water.
The action in the cylinders C is exactly the same as has been described with
reference to Figs. 4 and 5, excepting that piston P does not draw in the air from
the atmosphere during its downstroke but from vessel L in which the air is already
under pressure. At its upstroke piston P therefore effects the second stage of the
compression up to the prescribed degree. The lower and upper end positions of
the piston are shewn in dotted lines and marked with 1 and 2.
Piston P now moves downward again to position 3, fuel being during this time
gradually introduced and the combustion controlled, as above described. At 3 the

page_text: admission of fuel ceases and the air continues to expand; when the piston has
arrived in its lowest position 1, valve 6 opens, piston Qis at this moment just in its
upper position owing to the arrangement of the cranks; piston P then moves
upward and piston Q downward, and a further expansion of the combustion gases
up to the volume of cylinder B takes place; hereupon valve b closes and valvej
opens, so that at the following upward stroke of piston Q the combustion gases
are expelled through valve into the atmosphere, in a perfectly cooled condition,
as their entire heat will have been consumed by the work done in expanding.
It has already been mentioned, that in this construction the exhaust gases can be
caused to escape with a temperature which is below that of the atmosphere so that
they may still serve for cooling purposes.
As the cylinders C have a combustion period only at each second revolution, I
attain by arranging two such cylinders at each revolution a combustion, that is to
say a working stroke as the combustion is made to take place alternately on the
right and left hand. There is no obstacle to using only one combustion cylinder in
place of two or, on the other hand more than two, in which case the lower part of
the cylinder B may then be used as an expansion cylinder; the air pump for the
preparatory compression should then be arranged separately and force previously
compressed air into the reservoir L.
The air of the reservoir L serves in this construction directly for starting the
motor, as the latter may be fed during some revolutions from this reservoir with
full pressure, the ignition only taking place after the fly wheel has attained the
necessary momentum.
The device for gradually introducing fuel is dependent on the peculiar properties
of the material employed.
For solid pulverised substances, in lieu of the described revolving cock, a powder
nozzle or a small pump may be used; for liquids a spray nozzle or a small pump
is employed; for gases also a small pump or any other suitable device permitting
the gradual introduction of the fuel, the quantity of the latter being in a definite
proportion to the piston's stroke.
Fig. 8 to 10 show another construction of a motor in which liquid fuel is
employed and at the same time the external distributing device, in particular the
device for gradually introducing fuel, is of a quite different construction.
This machine consists of two entirely identical single acting cylinders provided
with plunger-pistons, the cranks of which are arranged on the common fly wheel
shaft in the same position; the frame, fly wheel and distributing device are nearly
exactly the same as illustrated in Figs. 4 and 5 and therefore not represented.
The combustion in the cylinders takes place alternately, so that at each
revolution a working stroke is effected.
In Fig. 8 one of the cylinders is shewn in vertical section, the other in front
view with its insulating casing.
Fig. 9 is a front view of the cylinder with the distributing device, and
Fig. 10 a plan view with a section of the distributing devices.
The process in each cylinder is the same as described with reference to Figs. 4
and 5, víz. :
Drawing in of air through valve V, then compression by one stroke up to the
end position 2 of the piston shewn in dotted lines; introduction of liquid fuel
through nozzle D and combustion of same during the prescribed period of
admission 2, 3 (Fig. 8), finally expansion of the body of gas and escape of the same
through valve V as through a blow pipe into an outward leading pipe R.
As the drawing in follows immediately after the escape, the valve V remains
open during a whole revolution, and then closed during a whole revolution. This
simplest possible regulation is effected by the cam S (Figs. 9 and 10) by means of
the bent lever, as shewn in the drawing.
The cam S is carried by the distributing shaft W, which is driven by the shaft
of the fly wheel in a similar way as in Figs. 4 and 5. The nozzle D is kept closed
by the needle n and serves for gradually admitting the fuel. The liquid fuel is in

page_text: the inner spacer of the nozzle D and is maintained there by means of a feed pump
(not shewn) provided with an air-chamber under a pressure which is higher than
the highest pressure of compression of the air in the cylinder.
In Fig. 10 is shewn at t the branch pipe for the liquid fuel coming from the pump
and leading to the nozzle.
At the moment of the highest compression, i.e. when the piston is in the position 2,
the needle n is opened by the distributing gear and allows a sharp thin jet of liquid
to enter through the very small opening D, as the liquid is under a pressure
superior to the cylinder pressure. This entrance of fuel continues up to position 3
of the piston, where the distributing device cuts it off exactly whereupon the
combustion gases continue to expand automatically.
For regulating the jet of fuel I have provided here exactly the same construction;
by which in Sulzer's valve machines the period of steam admission is regulated.
An eccentric E moves the steel side piece q in an oviform curve up and down;
the steel block is attached to the rod which actuates needle n; as soon as the
piece moving downward strikes against the piece the needle is opened and
remains open until the steel piece 7 releases the piece r, as the piece is adjustable
from the governor by means of the rod St (see Fig. 9), the governor regulates
simultaneously in the two cylinders the duration of the period of admission of fuel,
and in consequence thereof the speed of the engine.
9.
In Figs. 8 and 10 there is formed round the nozzle D an annular spaces which
is in free communication with the interior of the cylinder.
When the piston moves backward under decreasing pressure the air flows from
this annular space back into the cylinder and serves in this way both for dividing the
jet of fuel and for producing turbulent motion for distributing the combustion heat
over the whole air volume. This annular space s is only of practical importance
and is not essential for the process.
There is moreover in Figs. 8 and 10 at O an opening for introducing compressed
air or gases from explosive substances serving to start the motor. When in Fig. 8
in place of liquid, gas or vapor is compressed in the inner space r of the nozzle D
the same construction may be employed. It is therefore not necessary to shew a
construction of engine for this application. It is especially to be remarked that
the thermal results are independent on the kind of gas contained in the cylinder; it
is sufficient if the quantity of air necessary for combustion, is provided, the other
considerable quantity of gas, which acts only as a carrier of heat, may consist of
former combustion gases, added foreign gases and vapours or aqueous vapour,
without in any way altering the result. It follows from the above that closed
engines might be arranged so as to take up at each stroke only a small quantity of
fresh air for insuring the combustion, but which retain essentially always the same
body of gas, a small exhaust excepted.
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 :-
1. The method of working combustion motors consisting in compressing in a
cylinder by a working piston, pure air, or other neutral gas or vapour together
with pure air, to such an extent, that the temperature hereby produced is far
higher than the burning or igniting point of the fuel to be employed; (curve 1-2
of the diagram in Fig. 2), whereupon fuel is supplied at the dead centre 50
gradually, that on account of the outward motion of the piston and the consequent
expansion of the compressed air or gas the combustion takes place without essential
increase of temperature and pressure (curve 2-3 of the diagram in Fig. 2)
whereupon, after the admission of fuel has been cut off, the further expansion of
the body of gas contained in the working cylinder takes place (curve 3-4 of the
diagram in Fig. 2) substantially as described.
2. The mode of carrying out the process referred to in the preceding claim with
multiple compression and expansion by providing the combustion cylinder on one

page_text: hand with a compressing pump and reservoir and on the other hand with an
expansion cylinder, or by coupling several combustion cylinders with each other or
with the said compressing pump and expansion cylinder, substantially as described.
Dated this 27th day of August 1892.
ABEL & IMRAY,
Agents for the Applicant.