Improvements relating to Gas, Petroleum, and similar Engines.
Year: 1898

page_text: Date of Application, 28th Apr., 1898-Accepted, 28th Apr., 1899
COMPLETE SPECIFICATION.
Improvements relating to Gas, Petroleum, and similar Engines.
I, DONAT BANKI, of Roisahegy-utca 6, Budapest, in the Kingdom of Hungary,
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 a motor working in the "Otto" cycle there are produced great compression-
pressures in consequence of the diminution of the compression chamber A O
(Fig. 1). The pressure produced at the end of the compression stroke in the
cylinder can be calculated and represented by a curve the abscissue of which
represent the cubical contents of the compression chambers and the ordinates
of which give the explosion pressures (Fig. 2). In explosion motors the com-
pression generally approaches the adiabatic, for in gas machines there is no
further deduction of heat except the eventual cooling effect of the cylinder walls,
and in petroleum motors, where especially at higher compression pressures some
cooling takes place by the admission of liquid combustibles, the introduction of
quantities superfluous for the combustion is for evident reasons avoided. The
compression can thus be generally considered as adiabatic. Under this supposi-
tion I have drawn in Fig. 2 the curve a b of the final adiabatic compression
pressures, while the curve c d shows the isothermal compression. After the com-
pression has ceased we suppose a certain quantity of heat is admitted to the
mixture, that is to say, first at constant volume, and second constant pressure..
For the first case there is drawn in Fig. 2 a curve e f of the pressures after the
admission of heat, namely explosion pressures, in case of adiabatic compression,
and the curve gh for the same explosion pressures in case of isothermal com-
pression; for the second case the ordinates of the compression curves give simul-
taneously the maximum pressures produced in the motor.
For any supposed cubic capacity of compression chamber I can calculate the
indicated as well as the effective horse power of the motor for both cases. If I
represent the calculated values of the efficiency by means of curves as in Fig. 3
in which expresses the efficiency of an explosion motor with adiabatic com-
pression of an explosion motor with isothermal compression, and m n of a
slow combustion motor with adiabatic compression. I see (Fig. 3), that from a
certain disposable quantity of heat there is to be obtained a quantity of work
inversely proportional to the capacity of the compression chamber or directly
proportional to the compression pressure. Only at very high compression pres-
sures, which, however can not be attained in known piston engines, the efficiency
decreases. It can therefore be admitted as a principle of construction to employ
in the cylinder as high a pressure as technical means permit If we suppose a
certain maximum pressure we can find from Fig. 2 the corresponding size of the
compression chamber for an explosion motor, as also for a motor with slow com-
bustion. For instance for a tension A. P. (say 35 atmospheres) for the explosion
motor, we get the compression, chamber A 0, and for the motor with slow com-
bustion A O₁. If we transfer these compression chambers to Fig. 3, we obtain

page_text: the efficiency L, and O, L. The indicator diagrams corresponding with these
two cases are shown in Fig. 4; the diagram of the explosion motor is dis-
tinguished by cross hatching. It can be seen from Fig. 3, that there is only a
small difference in efficiency between the two cases. Comparison will be still
easier, if we represent the efficiency or, as is the case in Fig. 5, the percentage
efficiency, for explosion motors as also for motors with slow combustion at the
maximum tensions, as ordinates, and draw the curves. We see now quite clearly
from Fig. 5 that slow combustion gives the best effect, but the difference with
regard to the explosion motors is not considerable; they are nearly equivalent
with regard to the percentage efficiency.
These curves show clearly, that in motors with slow combustion when using
low tensions the efficiency is not so good as with explosion motors, and that they
surpass the explosion motors only at higher pressures (above about 10 atmos-
pheres). At such high pressures there are produced with adiabatic compression
high temperatures, which are above the igniting temperature. For preventing
early ignitions air and gas have had to be brought separately to the high pressure
and then mingled together, when using high compression pressures. This
method has been already used. The danger of early ignition by the heat of
compression exists also in explosion motors, but especially in motors, working
with petroleum on account of the inflammability of the petroleum at proportion-
ally low temperatures; for this reason one must renounce in the hitherto known
constructions either the advantages of the high compression or, one must intro-
duce the petroleum after the compression has been effected.
Now the purpose of this invention is to provide means for ensuring ignition
at the right time namely near the dead point while also avoiding the danger of
early ignition also at high compression pressures. It is evident that early
ignition cannot take place, if we prevent dangerous increase of temperature
during compression, that is to say, if we obtain by cooling a compression differing
from the adiabatic and approaching the isothermal line. Although it is not
necessary to carry the cooling so far that the compression curves coincide with
isothermal lines, we can however examine this case as an extreme limit.
In Fig. 2 the isothermal compression pressures as also the isothermal explosion
pressures upon the previously supposed admission of heat are represented by
the curves cd, g h and the respective efficiencies are indicated in Fig. 3. The
percentage efficiency is also shown in Fig. 5 for the case of isothermal compres-
sion. For the supposed tension A. P. we find the compression chamber
capacity A 0, and the indicator diagram in Fig. 6 is constructed on this value.
We see now from the figures and most clearly from Fig. 5, that the cooling of
the mixture to an equal final temperature has a scarcely perceptible influence on
the percentage efficiency of the motor, and as with less cooling the deviations will
become still more unessential, the cooling of the mixture for preventing early
ignitions is not unsuitable.
There now remains the question, in what manner the cooling of the mixture
should take place, in order to attain the effect desired. A cooling of the cylinder
walls is insufficient and indeed proportionally unsuccessful the larger the
cylinder diameter: for this reason in larger engines smaller compressions would
be necessary and better utilization of the combustible would be had, than in
smaller motors. A water injection, in the form of a jet, will not satisfy the pur-
pose as can be easily seen. "When the injected water has only to be evaporized
to assist in the expansion, and simultaneously to save lubricating material, it has
been sufficient for this purpose to introduce water in a jet through a pipe directly
into the cylinder. As far as I can remember all previous experiments to send
water into the cylinder, have pursued the same purpose but none has the purpose
of using high compressions without the danger of previous ignition. An injection
in the form of a jet would not have corresponded to this purpose as the cooling of
the mixture, that is here intended must extend to every point, almost for instance
to cach gas molecule, whilst an injection which leaves single places uncooled

page_text: does not correspond to the purpose intended. During the very quick process of
compression one cannot suppose, that the temperature will be equal throughout
the whole contents of the cylinder and an increase of the temperature to the
ignition point may occur in some place although other places in the cylinder
chamber are perhaps cooler.
On these grounds the water introduced for avoiding early ignition in motors
with high compression must occur in a finely dispersed state in the mixture of
air and combustible.
The construction of such cooling apparatus corresponding to these conditions
is represented in Figs. 7 and 8 in longitudinal section and in cross section respec-
tively. In the suction pipe there is arranged a disperser for liquid fuel, for
instance; the known disperser A, behind the disperser there is a second dis-
perser A' for water. With this arrangement a float casing S communicating
with the disperser A for regulating the height of the liquid is in connection with
a petroleum vessel whilst a similar one S is in connection with a water vessel.
The throttle valve 1) serving for regulating the air admission is arranged behind
the dispersers or also between the two dispersers.
The operation of the thus combined disperser is as follows. By opening the
regulating cone at A' the air passing to the petroleum disperser is wetted by finely
dispersed water, and in this wet air there occurs the also mist like dispersion of
the petroleum. One can also exchange the two dispersers and saturate with
water the air charged first with petroleum.
When the motor has to work with gas, coal gas, acetylene gas, benzine gas,
etc., instead of with dispersed fuel the petroleum disperser is replaced by any
known mixing apparatus for gas and air.
As can be seen from this description, the new process consists in passing the
air through two dispersing apparatus successively, of which the one disperses
water and the other one disperses fuel. As dispersers there can be used any
known dispersing apparatus. The two dispersers can be also arranged one within
the other instead of one behind the other, as shown in Figs. 9 and 10, in which
arrangement the same process occurs, as in the first described arrangement. The
two dispersers are here arranged concentrically, the inner one does not differ
from the one before described, the exterior one however differs somewhat since
the liquid tube and its regulating come are annular.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed I declare that what I
claim is:-
-
The introduction of water in a finely dispersed state mixed with the mixture
of air and combustible for avoiding early ignitions in explosion motors with high
compression, obtained by two dispersing apparatus arranged in sequence or
within one another, of which to the one water is conducted and to the other one
liquid fuel or combustible gas, such disperser being also replaceable by any
known mixing apparatus.
T
L 1
1000
HERBERT HADDAN & Cb.,
Agents to Applicant,
18, Buckingham Street, Strand, W.C, London.