Improved Method of and Apparatus for Working Gas or Oil Motor Engines Operating with Slow Combustion.
Year: 1894

page_text: Date of Application, 12th Nov., 1894
Complete Specification Left, 9th Aug.. 1395-Accepted, 21st Sept., 1895
[Communicated from abroad by THE GASMOTOREN FABRIK DEUTZ, of
Koeln-Deutz, Germany, Manufacturers.]
Improved Method of and Apparatus for Working Gas or Oil Motor
Engines Operating with Slow Combustion.
I, CHARLES DENTON ABEL, of No. 28 Southampton Buildings, Chancery
Lane, in the County of London, Consulting Engineer and Chartered Patent
Agent, do hereby declare the nature of this invention to be as follows:-
As is well known, gas or oil motor engines working with slow combustion operate
in such manner that a combustible mixture of gas or oil vapour and air under
pressure is forced into the engine-cylinder during the first part of the stroke of the
piston, the said mixture being at the same time ignited and made to burn gradually
without great increase of pressure, that is to say, with a corresponding increase of
volume. At a certain point of the piston's stroke, the inlet for the combustible
mixture is closed and the hot gaseous products of combustion in the cylinder are
made to expand to the end of the piston's stroke, and are then expelled on the
return stroke of the piston.
In order to work economically with this class of motor engine, very considerably
diluted combustible mixtures must be employed, because the richer the mixture is
in combustible gas, the higher will be the temperature of combustion, and the
greater will be the proportion of heat lost by conduction through the cylinder
walls.
But in diluting the mixture, a limit is soon reached at which the ignition thereof
becomes uncertain.
According to the present invention it is rendered possible to employ a rich
gaseous mixture in such engines and thus to insure certainty of ignition, and yet to
keep the temperature sufficiently low to prevent material loss, by first drawing in
air only, or an inert gas, at the commencement of the piston's stroke, and afterwards
admitting the charge of rich mixture.
The quantity of combustible mixture admitted under these conditions is so
proportioned that the increase of volume of the charge due to the heat generated
is about equal to the volume of the space formed in the cylinder by the motion of
the piston, so that the evolution of heat takes place without material increase or
decrease of pressure.
When the admission of the combustible mixture ceases, the
hot gases expand to the end of the stroke.
Thus, contrary to the mode of operating in existing gas motor engines working
with slow combustion, the ignition in the present case does not take place at or
about the dead centre of the stroke but only after the piston has moved through a
substantial part of its stroke.
With the existing engines, a sudden increase of pressure could easily occur on
ignition, which would operate prejudicially upon the uniform admission of fresh
combustible mixture.
This cannot occur with the above described improved method of operating, as at
the comniencement of ignition a considerable space already exists behind the piston
which is filled with air, so that the sudden increase of pressure of the first-admitted
particles of combustible mixture cannot cause any detrimental increase of pressure
of the charge in the cylinder.

page_text: In an engine operating according to this invention, the rear end of the cylinder
is provided with an inlet valve for combustible mixture of gas or oil vapour and
air under pressure, the gas being forced in by a force pump worked by the engine
shaft while the air enters from a reservoir for compressed air charged by a pump
worked by the engine, or otherwise, the air being made to mix with the gas on
entering through the valve. A second air admission valve is provided, also
communicating with the reservoir under pressure, through which the preliminary
charge of air is introduced during the first part of the outstroke. These valves are
operated by a countershaft driven at the same speed as the engine shaft and
having cams acting on levers connected to the said valves, and so arranged that the
cam for the admission of air under pressure alone opens the corresponding valve at
or slightly before the commencement of the outstroke and allows it to close shortly
afterwards, while the cam for the admission of combustible mixture opens the valve
after the piston has performed a certain portion of its outstroke and allows it to
close after a further portion of the stroke has been performed. The countershaft
has another cam acting on the discharge valve of the engine so as to open this at
the commencement of the return stroke.
The ignition of the combustible mixture as it is forced in is effected either by an
electrically heated wire, electric spark, or other known means.
Dated this 12th day of November 1894.
ABEL & IMKAI,
Agents for the Applicant.
Improved Method of and Apparatus for Working Gas or Oil Motor
Engines Operating with Slow Combustion.
I, CHARLES DENTON ABEL, of No. 28 Southampton Buildings, Chancery
Lane, in the County of London, Consulting Engineer, and Chartered Patent
Agent, 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:-
As is well known, gas or oil motor engines working with slow combustion
operate in such manner that a combustible mixture of gas or oil vapour and
air under pressure is forced into the engine cylinder during the first part of the
stroke of the piston, the said mixture being at the same time ignited and made
to burn gradually without great increase of pressure, that is to say,
with a
corresponding increase of volume. At a certain point of the piston's stroke, the
inlet for the combustible mixture is closed and the hot gaseous products of
combustion in the cylinder are made to expand to the end of the piston's stroke,
and are then expelled on the return stroke of the piston.
In order to work economically with this class of motor engine very considerably
diluted combustible mixtures must be employed, because, the richer the mixture is
in combustible gas, the higher will be the temperature of combustion, and the
greater will be the proportion of heat lost by conduction through the cylinder walls.
But in diluting the mixture, a limit is soon reached, at which the ignition thereof
becomes uncertain.
According to the present invention it is rendered possible to employ a rich
gaseous mixture in such engines and thus to ensure certainty of ignition, and yet
to keep the temperature sufficiently low to prevent material loss by first drawing
in air only, or an inert gas, at the commencement of the piston's stroke, and
afterwards admitting the charge of rich mixture.
The quantity of combustible mixture admitted under these conditions is so
proportioned that the increase of volume of the charge due to the heat generated is
about equal to the volume of the space formed in the cylinder by the motion of the

page_text: piston, so that the evolution of heat takes place without material increase or
decrease of pressure.
When the admission of the combustible mixture ceases, the hot gases expand to
the end of the stroke.
Fig. 1 of the accompanying drawing shews the theoretical indicator diagram of
an engine working according to this invention.
At the commencement of the outstroke air or inert gas under pressure is
admitted for a certain part of the stroke, such as to the point 2; from this point
the supply of air is cut off and a supply of combustible mixture under pressure
takes place which continues, say, up to the point 3 of the stroke, such mixture
being ignited as it enters and buruing gradually during the continuance of its
introduction, the heat generated being imparted to the charge of air or inert gas in
the cylinder, so that this charge expands and performs work conjointly with the
combustion gases. The quantity of the admitted combustible mixture is so pro-
portioned that the increase of volume due to the heat generated by its combustion
is about equal to the volume of the space produced in the cylinder by the forward
motion of the piston, so that the addition of heat is effected without appreciable
increase or decrease of pressure.
When the admission of combustible gas ceases at point 3 of the diagram, the
heated gases in the cylinder begin to expand and such expansion continues till the
end of the stroke i.e. from 3 to 4. At 4 the discharge of the combustion gases
commences and continues until near the end of the return stroke, at point 5, when
the discharge valve is closed.
Thus, contrary to the mode of operating in existing gas motor engines working
with slow combustion, the ignition in the present case does not take place at or
about the dead centre of the stroke but only after the piston has moved through a
substantial part of its stroke.
With the existing engines, a sudden increase of pressure could easily occur on
ignition which would operate prejudicially upon the uniform admission of fresh
combustible mixture.
This cannot occur with the above described improved method of operating, as at
the commencement of ignition a considerable space already exists behind the
piston which is filled with air, so that the sudden increase of pressure of the first
admitted particles of combustible mixture cannot cause any detrimental increase of
pressure of the charge in the cylinder.
Figs. 2, 3 and 4 of the drawings shew a construction of engine working according
to the above described method. Fig. 2 shews a longitudinal section on line I I, II II
of Fig. 3, Fig. 3 an end view, and Fig. 4 a sectional plan on line III III Fig. 3.
A is the engine cylinder, B the piston, C the inlet valve for combustible mixture,
D the inlet valve for air, E the discharge valve, i the electrical igniting device
consisting either of an incandescent platinum wire or a continuous electric spark,
and a wire gauze diaphragm for preventing any backward flash of the flame,
which device is advantageous but not necessary to the purposes of this invention.
The air supply is compressed in a reservoir G either by means of an air pump
worked by a crank on the engine shaft M, or by a separate pump, and is led thence
through pipes G G to the chambers of the valves C and D. The gas supply
from pipe I is compressed by a gas pump H operated by an eccentric L on the
engine shaft M and is forced through channel H¹ to the perforated seat of the
valve C, so that on the opening of this it mixes with the compressed air to form
the combustible mixture that burns as it enters the cylinder.
J
The valves are actuated by a countershaft F, driven by suitable gearing such as
indicated at K Fig. 3, at the same speed as the engine shaft and having cams n' n² n³
suitably formed for operating respectively upon the valves C. D. E. through
levers de having rollers r. The cams are so arranged that valve D is made to
open at point 1 of the diagram Fig. 1, or somewhat earlier, and is closed at point 2,
or somewhat later, and, that valve C is opened during the period from 2 to 3, and
valve E during the period from 4 to 5.
む

page_text: Although in the foregoing I have described the use of a separate air supply
valve D for the supply of air under pressure alone during the first part of the
outstroke of the piston, yet it will be obvious that this valve may be dispensed with,
and the supply of air under pressure during the first part of the stroke might be
effected by means of the same valve C that afterwards serves for the admission of
the charge of combustible mixture.
For this purpose it is merely necessary to form the cam n' on shaft F in such
manner that it opens valve C already at the commencement of the outstroke, in
which case an additional cam is provided for controlling an additional inlet valve on
the passage leading from the gas pump H to the valve seat of C, so that the gas
supply under pressure only enters and mixes with the air supply for forming the
combustible mixture when the piston has performed a part of its stroke as above
described. It is preferred however to admit the said charge of air at the beginning
of the stroke by means of a separate valve D as described.
Furthermore, in place of introducing the combustible mixture through a single
valve C, there might be provided for this purpose separate valves and corresponding
cams for the admission of the gas and the air supplies, in the required proportions
for forming the slow combustion mixture. In this case there would consequently
be three admission valves; one for gas, one for the air required for admixture with
the gas, and the third for the charge of air alone.
Lastly it is to be observed that the term "inert gas" herein employed for the
charge introduced during the period 1-2 of the diagram Fig. 1 is to be
understood in the widest sense, as steam or other inert vapours might be employed
for this purpose, in which case such steam might be formed in the engine cylinder
itself, for example by the injection of water into the cylinder during the first part
of the outstroke, which water would be at once converted into steam owing to the
high temperature of the cylinder.
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 :-
1. The method of working two stroke slow combustion cycle gas or oil motor
engines whereby compressed air or inert gas only is introduced into the engine
cylinder during the first part of the outstroke, after which combustible mixture
under pressure is admitted and is gradually burnt during its inflow, the hot
combustion gases being made to expand from the time when such inflow is cut off
to the end of the outstroke, and being afterwards expelled during the instroke,
substantially as described.
2. In a two stroke cycle slow combustion gas or oil motor engine, the combination
with a working cylinder and piston, of a pump for compressing combustible gas, a
pump for compressing air or inert gas into a reservoir, a valve for admitting
compressed air or inert gas from the reservoir to the cylinder during the first part
of the outstroke, a valve for admitting compressed combustible mixture of gas or
vapour and air during the following part of the outstroke, means for igniting such
combustible mixture as it enters the cylinder, a discharge valve for discharging the
combustion gases during the return stroke, and a countershaft running at the same
speed as the engine shaft, having cams for operating the said valves, substantially
as described.
Dated this 9th day of August. 1895
ABEL & IMRAY,
Agents for the Applicant.