Improved Method and Means for Working Two-stroke Cycle Gasmotor Engines.
Year: 1899

page_text: Date of Application, 21st Nov., 1899
Complete Specification Left, 27th July, 190C-Accepted, 15th Sept., 1900
PROVISIONAL SPECIFICATION.
Improved Method and Means for Working Two-stroke Cycle
Gasmotor Engines.
I. CHARLES DENTON ABEL, of Birkbeck Bank Chambers, Southampton Build-
ings, in the County of London, Consulting Engineer and Chartered Patent
Agent, do hereby declare the nature of this invention (as communicated to me
from abroad by The Gasmotoren Fabrik Deutz, of Koeln-Deutz, in the Empire
of Germany, Manufacturers), to be as follows:-
This invention relates to an improved method and means for working two-
stroke cycle gasmotor engines, whereby homogeneous compressed charges of
gas and air mixture are introduced and ignited within the working cylinder
after this has been cleared of combustion residues and still burning gas particles,
whereby an absolutely reliable ignition is insured while the heat generated by
the combustion is utilised to the greatest possible extent.
According to this improved method of operating there is forced through the
engine cylinder (which has no compression space), shortly before the piston
reaches the inner dead centre, a scavenger charge of air which carries with it the
remaining combustion gases and any particles of still burning gas mixture
and discharges the same through the discharge valve; on the piston arriving
at the dead centre, the discharge valve and scavenger air valve are closed, and a
previously formed homogeneous mixture of gas and air is introduced into the
cylinder through a charging valve while the piston is performing a certain por-
tion of its outstroke, after which, the charging valve being closed, the charge
is ignited and the expansive action due to the heat generated causes the piston
to complete its outstroke in doing work.
This method differs from the known methods of working of two-stroke gas
engines heretofore employed in that the premature ignition of the charges is
avoided which frequently occurs with the known arrangements owing to the
entering combustible charge becoming fired by residual burning gas particles
or by highly heated combustion residues of the previous charge."
On account of this premature ignition it was generally speaking not practic-
ally possible to work two-stroke motors by means of previously formed homo-
geneous explosive mixtures, as the store thereof contained in the reservoir would
be liable to be exploded by such premature ignitions; the two parts of the
mixture, namely the air and gas had therefore to be stored separately in different
reservoirs, or in the same reservoir, without being mixed before entering the
cylinder, and owing to the shortness of the charging period, they had not time
to mix thoroughly so as to ensure a reliable ignition and rapid combustion.
The present improved method of working, as above stated, effectually avoids
the liability to premature ignition by causing the combustion residues and
particles of burning gas to be swept out of the cylinder by a scavenger charge

page_text: of air, enabling explosive charges to be used of a perfectly homogeneous nature
previously formed outside the cylinder.
On the other hand in the case of those two-stroke gas motors in which a
scavenger charge of air has already been used for clearing out a compression
space existing in the cylinder behind the piston when at the end of instroke;
differ essentially from the present improved method, both as to the manner of
forming the charges and as to the volume of the scavenger charge of air
required.
With these motor engines the ignition of the charges is effected when the
piston arrives at the inner dead centre, so that the introduction of the charges
must necessarily be effected already during the compression period.
Consequently not only the compression space but also a considerable portion
of the space passed through by the piston requires to be filled with clearing air
or air for combustion, into which the gas then enters, and therefore the mixing
of the gas and air constituting a combustible charge can only take place in the
cylinder itself, while, as already stated, according to the present invention the
charge enters the cylinder already in an intimately mixed condition, and is not
there mixed with any appreciable further quantity of air.
Furthermore, with the said existing method a considerable quantity of air
is necessary for the scavenger charge, as this has to force out a large volume of
combustion gases contained in the compression space and a large portion of the
cylinder.
The scavenger charge remaining in the cylinder no doubt serves as the air
supply for the next explosive charge, but owing to the unavoidable mixture of
the scavenger charge with the combustion gases, a very large volume of air
must be employed in excess of that required for the explosive charge if all the
combustion gases are to be expelled.
According to the present invention on the other hand, only a comparatively
small quantity of air is required for the scavenger charge, namely only slightly
more than the volume represented by the small dead space or clearance between
piston and cylinder end, so that a saving is effected both as to work done and
weight of engine.
Lastly, by the improved method of working, a very energetic cooling and
clearing of the pistons surface is effected, as the scavenger charge has to force
its way at a high speed through the very narrow clearance or dead space
between piston and cylinder end, whereas with the existing method the scavenger
charge has to pass through the beforementioned large capacity of the com-
pression space and part of cylinder, in which it consequently only travels at a
slow speed, and with imperfect contact for cooling purposes.
On the accompanying drawing Fig. 1 shews an indicator diagram of
the improved method of working while Figs. 2 and 3 shew respec-
tively a diagrammatic longitudinal section and end view of a gas motor
engine working according to the present invention. A is the engine cylinder
B, the piston, C the discharge valve, d the admission or charging valve for the
explosive charge, e the valve for the scavenger air charge and R the reservoir
for the compressed explosive mixture. Towards the end of the discharging
period (point I of diagram Fig. 1) the air valve e is opened and the entering air
(supplied in any suitable manner) drives the remaining combustion products
out through the open discharge valve c. At the dead centre (II) both the said
valves are closed; on the other hand the charging valve d is opened and admits
compressed explosive mixture into the cylinder during the first part of the
pistons out-stroke (III to IV of diagram) which charge is ignited directly at
the point IV that is, directly after closing the charging valve.
The pressure in the cylinder then suddenly rises to point V and then gradually
decreases according to the expansion curve V to VI during the remainder of
the pistons outstroke, after which the discharge valve is opened.
The valves are actuated in the arrangement shewn by means of a way shaft f

page_text: driven from the engine shaft and having cam discs 9 g¹ g¹¹ which effect the
opening of the valves through rollers and levers h h h¹."
The valve gear may however be arranged in any other suitable known way
for effecting the above described operations.
The regulation of the gas motor engine is effected by varying the duration
of the admission of explosive mixture, and consequently the volume of each
explosive charge.
Fig. 1 shews a series of indicator diagrams varied in this manner for pro-
ducing variable amounts of work. With this arrangement the ignition of the
charges must be made dependent upon the working of the charging valve in
such manner that the ignition in every case occurs immediately after the closing
of the valve.
Figs. 4, 4 and 5, 5", shew two different arrangements for this purpose.
In the arrangement at Fig. 4 there is combined with the stem of the charging
valve d, through the medium of a blade spring k, a body i which is ordinarily
held by a stop in a definite position relatively to the valve stem, in which
position a contact piece carried by the body and connected to one part of
an electric circuit is kept out of contact with the fixed contact piece 7 connected
to the other part of the circuit.
The lever of the charging valve is actuated by means of a moveable cam mn
with inclined following face m as shewn in side view at Fig. 4ª and controlled
by a governor in the known manner.
When the charging valve, after being held open by lever h for a length of
time determined by the position of cam m n, is closed by the action of its
spring, the body i in moving with the valve spindle continues to move to
the left hand by reason of the impetus imparted to it after the valve has closed,
and thereby causes contact to be made between 1 and thus closing the electric
circuit in which is included the igniting device and effecting the ignition of
the charge in the cylinder by an electric spark in the well known manner.
In the arrangement at Fig. 5, the cam m n for actuating the charging valve
has joined to it a lower long cam no which extends almost completely round
the cam boss, leaving only a small portion of the latter free. With the lever h
of the charging valve is connected an electrical contact which is only closed
when the roller of the lever moves over the free part m o of the boss, the circuit
being open as long as the roller runs over the cams on or n m.
Consequently immediately after the roller has run off the inclined following
side of m of the charging cam m n, the lever h causes the contacts to close
the electric circuit and effect the firing of the charge, the circuit being broken
again as soon as the roller passes on to the cam o n.
With the motor engine can be combined any suitable known arrangement
of force pump for forcing the gas and air mixture, or a separate gas and air
pump for producing and compressing the mixture of gas and air, or the said
compressed gaseous mixture can be produced independently of the motor engine.
The only essential feature in this respect is the interpolation of a reservoir
for compressed gas and air mixture between the engine cylinder and the force
pump, in order to enable a thoroughly homogeneous mixture of the gas and
air to be effected before entering the cylinder.
The said homogeneous mixture may contain in addition to combustible gas
and air any other suitable gas of a neutral or inert nature.
Dated this 21st day of Nonamkon 1900
ABEL & IMRAY,
Agents for the Application.

page_text: Improved Method and Means for Working Two-stroke Cycle
Gasmotor Engines.
I, CHARLES DENTON ABEL, of Birkbeck Bank Chambers, Southampton Build-
ings, in the County of London, Consulting Engineer and Chartered Patent
Agent, do hereby declare the nature of this invention (as communicated to me
from abroad by The Gasmotoren Fabrik Deutz, of Koeln-Deutz, in the Empire
of Germany, Manufacturers,) and in what manner the same is to be performed,
to be particularly described and ascertained in and by the following statement:-
This invention relates to an improved method and means for working two-
stroke cycle gasmotor engines, whereby homogeneous compressed charges of
gas and air mixture are introduced and ignited within the working cylinder
after this has been cleared of combustion residues and still burning gas particles,
whereby an absolutely reliable ignition is insured while the heat generated by
the combustion is utilised to the greatest possible extent.
According to this improved method of operating there is forced through the
engine cylinder (which has no compression space), shortly before the piston
reaches the inner dead centre, a scavenger charge of air which carries with it the
remaining combustion gases and any particles of still burning gas mixture.
and discharges the same through the discharge valve; on the piston arriving
at the dead centre, the discharge valve and scavenger air valve are closed, and a
previously formed homogeneous mixture of gas and air is introduced into the
cylinder through a charging valve while the piston is performing a certain por-
tion of its outstroke, after which, the charging valve being closed, the charge
is ignited and the expansive action due to the heat generated causes the piston
to complete its outstroke in doing work.
This method differs from the known methods of working of two-stroke gas
engines heretofore employed in that the premature ignition of the charges is
avoided which frequently occurs with the known arrangements owing to the
entering combustible charge becoming fired by residual burning gas particles
or by highly heated combustion residues of the previous charge."
On account of this premature ignition it was generally speaking not practic-
ally possible to work two-stroke motors by means of previously formed homo-
geneous explosive mixtures, as the store thereof contained in the reservoir would
be liable to be exploded by such premature ignitions; the two parts of the
mixture, namely the air and gas had therefore to be stored separately in different
reservoirs, or in the same reservoir, without being mixed before entering the
cylinder, and owing to the shortness of the charging period, they had not time
to mix thoroughly so as to ensure a reliable ignition and rapid combustion.
The present improved method of working, as above stated, effectually avoids
the liability to premature ignition by causing the combustion residues and
particles of burning gas to be swept out of the cylinder by a scavenger charge
of air, enabling explosive charges to be used of a perfectly homogeneous nature
previously formed outside the cylinder.
On the other hand in the case of those two-stroke gas motors in which a
scavenger charge of air has already been used for clearing out a compression
space existing in the cylinder behind the piston when at the end of instroke;
differ essentially from the present improved method, both as to the manner of

page_text: forming the charges and as to the volume of the scavenger charge of air
required.
With these motor engines the ignition of the charges is effected when the
piston arrives at the inner dead centre, so that the introduction of the charges
must necessarily be effected already during the compression period.
Consequently not only the compression space but also a considerable portion
of the space passed through by the piston requires to be filled with clearing air
or air for combustion, into which the gas then enters, and therefore the mixing
of the gas and air constituting a combustible charge can only take place in the
cylinder itself, while, as already stated, according to the present invention the
charge enters the cylinder already in an intimately mixed condition, and is not
there mixed with any appreciable further quantity of air.
Furthermore, with the said existing method a considerable quantity of air
is necessary for the scavenger charge, as this has to force out a large volume of
combustion gases contained in the compression space and a large portion of the
cylinder.
The scavenger charge remaining in the cylinder no doubt serves as the air
supply for the next explosive charge, but owing to the unavoidable mixtare of
the scavenger charge with the combustion gases, .a very large volume of air
must be employed in excess of that required for the explosive charge if all the
combustion gases are to be expelled.
According to the present invention on the other hand, only a comparatively
small quantity of air is required for the scavenger charge, namely enly slightly
more than the volume represented by the small dead space or clearance between
piston and cylinder end, so that a saving is effected both as to work done and
weight of engine.
Lastly by the improved method of working, a very energetic cooling and
clearing of the pistons surface is effected, as the scavenger charge has to force
its way at a high speed through the very narrow clearance or dead space
between piston and cylinder end, whereas with the existing method the scavenger
charge has to pass through the beforementioned large capacity of the com-
pression space and part of cylinder, in which it consequently only travels at a
slow speed, and with imperfect contact for cooling purposes.
On the drawing accompanying my Provisional Specification Fig. 1 shews an
indicator diagram of the improved method of working while Figs. 2 and 3 shew
respectively a diagrammatic longitudinal section and end view of a gas motor
engine working according to the present invention. A is the engine cylinder,
B, the piston, C the discharge valve, d the admission or charging valve for the
explosive charge, e the valve for the scavenger air charge and R the reservoir
for the compressed explosive mixture. Towards the end of the discharging
period (point I of diagram Fig. 1) the air valve e is opened and the entering air
(supplied in any suitable manner) drives the remaining combustion products
out through the open discharge valve c. At the dead centre (II) both the said
valves are closed; on the other hand the charging valve d is opened and admits
compressed explosive mixture into the cylinder during the first part of the
pistons out-stroke (III to IV of diagram) which charge is ignited directly at
the point IV that is, directly after closing the charging valve.
The pressure in the cylinder then suddenly rises to point V and then gradually
decreases according to the expansion curve V to VI during the remainder of
the pistons outstroke, after which the discharge valve is opened.
The valves are actuated in the arrangement shewn by means of a way shaft f
driven from the engine shaft and having cam discs gg which effect the
opening of the valves through rollers and levers h h h"."
The valve gear may however be arranged in any other suitable known way
for effecting the above described operations:
The regulation of the gas motor engine is effected by varying the duration

page_text: of the admission of explosive mixture, and consequently the volume of each
explosive charge.
Fig. 1 shews a series of indicator diagrams varied in this manner for pro-
ducing variable amounts of work. With this arrangement the ignition of the
charges must be made dependent upon the working of the charging valve in
such manner that the ignition in every case occurs immediately after the closing
of the valve.
Figs. 4, 4 and 5, 5ª, shew two different arrangements for this purpose.
In the arrangement at Fig. 4 there is combined with the stem of the charging
valve d, through the medium of a blade spring k, a body i which is ordinarily
held by a stop in a definite position relatively to the valve stem, in which
position a contact piece carried by the body and connected to one part of
an electric circuit is kept out of contact with the fixed contact piece / connected
to the other part of the circuit.
The lever of the charging valve is actuated by means of a moveable cam mn
with inclined following face m as shewn in side view at Fig. 4" and controlled
by a governor in the known manner.
When the charging valve, after being held open by lever h for a length of
time determined by the position of cam m n, is closed by the action of its
spring, the body in moving with the valve spindle continues to move to
the left hand by reason of the impetus imparted to it after the valve has closed,
and thereby causes contact to be made between and thus closing the electric
circuit in which is included the igniting device and effecting the ignition of
the charge in the cylinder. by an electric spark in the well known manner.
In the arrangement at Fig. 5 the cam m n for actuating the charging valve
has joined to it a lower long cam no which extends almost completely round
the cam boss, leaving only a small portion of the latter free. With the lever h
of the charging valve is connected an electrical contact which is only closed
when the roller of the lever moves over the free part m o of the boss, the circuit
being open as long as the roller runs over the cams on or n m.
Consequently immediately after the roller has run off the inclined following
side m of the charging cam m n, the lever h causes the contacts to close
the electric circuit and effect the firing of the charge, the circuit being broken
again as soon as the roller passes on to the cam o n.
With the motor engine can be combined any suitable known arrangement
of force pump for forcing the gas and air mixture, or a separate gas and air
pump for producing and compressing the mixture of gas and air, or the said
compressed gaseous mixture can be produced independently of the motor engine.
The only essential feature in this respect is the interpolation of a reservoir
for compressed gas and air mixture between the engine cylinder and the force
pump, in order to enable a thoroughly homogeneous mixture of the gas and
air to be effected before entering the cylinder.
The said homogeneous mixture may contain in addition to combustible gas
and air any other suitable gas of a neutral or inert nature.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that what
I claim is:-
1. A method of working two-stroke cycle gas motor engines having no
compression space in the cylinder, which consists in forcing in a scavenger
charge of air into the small space intervening between the piston and cylinder
end just before the piston reaches the inner dead centre, so as to clear such
space of combustion residues, then introducing a charge of previously intimately
mixed gas and air during a portion of the outstroke of the piston and after
closing the charging valve, firing the charge, substantially as described.
2. Means for regulating a gas motor engine of the kind referred to in the

page_text: first claim, whereby the charging valve for the explosive mixture is arranged
to be held open for variable lengths of time while the device for firing the
charges is so arranged in conjunction with the charging valve that the firing
of the charge always takes place directly after the closing of the valve, whether
this occurs sooner or latter, substantially as described.
Dated this 27th day of July 1900.
ABEL & IMRAY,
Agents for the Applicant.