IMPROVEMENTS IN ENGINES A CYLINDER BY IGNITION OF County of Oxford, for an WHEREIN A PISTON IS PROPELLED INFLAMMABLE GAS OR FLUID
Year: 1881

page_text: LETTERS PATENT to Matthew Piers Watt Boulton, of Tew Park, in the
Invention of "IMPROVEMENTS IN ENGINES
A CYLINDER BY IGNITION OF
County of Oxford, for an
WHEREIN A PISTON IS PROPELLED
INFLAMMABLE GAS OR FLUID."
IN
PROVISIONAL SPECIFICATION left by the said Matthew Piers Watt
Boulton at the Office of the Commissioners of Patents on the 3rd August
1881.
MATTHEW PIERS WATT BOULTON, of Tew Park, in the County of Oxford.
IMPROVEMENTS IN ENGINES WHEREIN A PISTON IS PROPELLED IN A CYLINDER
BY IGNITION OF INFLAMMABLE GAS OR FLUID."
This Invention relates to engines in which a mixture of air with inflammable
gas or vapour or fluid is ignited behind a piston working in a cylinder, and propels
the piston.
One object which I have in view is to introduce the inflammable charge so that
it may be ignited when the piston is about to commence its stroke or is at the
dead point, moving slowly; and I also desire to work in such a manner that for
each ignition of the charge the piston shall not make more than one pair of strokes,
i.e., a forward and a return stroke.
Another object which I have in view, and desire to attain as nearly as possible,
is to introduce the inflammable charge in such a way that it shall be separated
from the surfaces of the piston and cylinder by air or elastic fluid which does not
undergo combustion, in order that this air or fluid may obstruct passage of heat
from the ignited charge to the metal.
I provide a cylinder fitted with a piston which works the engine. The piston
does not work through the whole length of this cylinder; that portion of it in
which the piston does not work is intended for the reception of the charge. The
eduction valve is situated at or near the point where the piston approaches most
nearly the charging end of the cylinder.
Means are provided for clearing out the exhaust fluid from the portion of the
cylinder designed for the reception of the charge by causing air to sweep through

page_text: it, which may be done either by forcing air through it by means of a pump or
forcing apparatus, or by opening communication with an air-vessel in which air is
contained at the requisite pressure; or again by drawing air through the space by
movement of the piston which works the engine, or by a combination of such
methods.
Means are also provided for introducing the gas or inflammable fluid in a similar
manner.
In describing the general course of operations I shall suppose that pumps are
employed in order to introduce the air and inflammable fluid at the charging end
of the cylinder, and I shall speak of the inflammable fluid as gas.
I shall suppose for starting point that the charge has been introduced behind
the piston, and that the piston is ready to commence its working stroke.
The charge is ignited, and the high pressure consequent on the ignition propels
the piston. When the expansion has proceeded to the degree desired the eduction
valve is opened. The pump for forcing air into the charging end of the cylinder
now begins to work. Air enters the cylinder at its charging end, and acting as a
fluid piston expels exhaust fluid from this part of the cylinder, occupying the space
vacated by the exhaust thus displaced. This action takes place while the piston
is still continuing its forward movement. The pump, injecting more air than is
needed to follow the advancing piston, expels a portion of exhaust through the
eduction valve. In this mannor the exhaust is expelled from the charging end of
the cylinder, and replaced with cool atmospheric air to such an extent as is
desired.
This having been done, the piston of the gas pump is brought into action and
injects the charge of gas into the charging end of the cylinder, while at the same
time the piston of the air-pump continues to inject air, and a portion of the gas and
air thus introduced mix together and form an inflammable mixture in the space
designed for the charge at the charging end of the cylinder.
The operation above described may be varied as respects timing. The introduc-
tion both of the air and gas might take place during the return stroke of the
piston; or it may take place partly while the piston is advancing on its forward
stroke and partly while it is returning. The latter seems generally to be the
preferable mode.
And it is evident that while the piston is advancing on its forward or working
stroke it might draw in both air and gas without the aid of pumps forcing
them in.
When the desired quantities of air and gas have been introduced, and before the
piston completes its return stroke, communication is closed between the cylinder
and the sources of supply of gas and air. As the piston approaches or reaches the
end of its return stroke the eduction valve is closed, and when the piston has
completed its return stroke the point previously taken at starting-point is
reached.
In the above description I have supposed the air and gas to be injected by
pumps, but is is evident that they might be introduced from vessels in which the
air and gas are contained under pressure. The pressure in these vessels might be
caused by pumps worked by the engine; or the air and gas might be stored in
reservoirs and supplied from these at regulated pressure to the cylinder.
The piston in the latter part of its return stroke may compress the charge, just
as very commonly in steam engines it compresses the exhaust when it is desired
to cushion the steam, and the degree of the compression thus caused may be varied
to any extent desired by the timing of the closure of the eduction-valve just as
ordinarily in steam-engines.
I consider that in one respect there is considerable advantage in employing
compression, in that it enables a higher initial pressure, and larger range of expan-
sion to be used, by means of which a larger amount of the heat is converted into
work. With this view it may be found desirable to use a high degree of
compression.

page_text: When it is desired to compress the charge to any considerable extent the
following construction is applicable :-
A plunger or loose fitting piston is attached to the piston on the side of it nearest
the charging end of the cylinder. This plunger, when the piston returns towards the
charging end of the cylinder, advances into the charge and compresses it, while
the packed or close-fitting part of the piston does not advance beyond the eduction
valve.
When a high range of expansion is used which, as above remarked, is important
for utilisation of the heat, difficulty is created in the working of the engine by the
great difference between the initial and the final pressures, this tending to create
shock or sudden acceleration when the initial pressure acts on the piston. Hence
in such a case, it is desirable to provide some means for lessening the inequality
of the pressures acting at different times on the piston.
In order to effect this the following construction is applicable.
The piston on that side of it which is not acted on by the ignited charge is
acted on by compressed air contained in an air vessel, so that a differential pressure
is obtained, reducing the amount of unbalanced pressure acting on it at the
moment of ignition and tending to equalise pressure generally. This arrangement
also lessens the amount of work imposed on the fly, since the compressed air drives
the piston in its return stroke.
To supply loss of the compressed air by leakage a pump is employed worked by
the engine.
In the above account I have not described any particular method of intro-
ducing the air and the gas. I will proceed now to describe the method which
I use.
One object which I have in view is to introduce the fluid as nearly as may be in
a direction parallel to to the axis of the cylinder in order that it may act as much
as possible like a fluid piston, so as to displace the exhaust air in front of it without
creating eddies or mixing much with it.
Another object which I have in view is, as previously mentioned, to introduce
the inflammable mixture in such a way that it shall in all parts be separated from
the metal by a certain portion of air, which does not undergo combustion when the
charge is ignited, in order to lessen transference of heat from the ignited gases to
the metal.
In one construction of Lenoir's, means were provided by which the combustible
mixture might be separated by a certain portion of air from the piston and from
the end of the cylinder. I desire so far to produce a like condition, but I desire
also to separate the combustible mixture from the sides or curved surface of the
cylinder.
The separation of the combustible mixture from the piston is effected in the
method which I use by properly adjusting the stroke of the gas pump, or, if the
gas is admitted from a reservoir, by properly timing the valve which admits it. In
this way it is provided that the gas when introduced shall not advance in the
cylinder further than is desired, so that when the piston returns there is a certain
portion of air between the piston and the combustible mixture.
The introduction of the air behind the combustible mixture is effected by the
timing of the valves, the valve which governs the admission of gas being closed
somewhat before the valve which governs the admission of air.
In order to separate the inflammable mixture from the sides of the cylinder, and
also to introduce the air and gas in the desired direction, viz., parallel to the axis
of the cylinder, I operate as follows:-
:-
At the charging end of the cylinder I provide a passage of cylindrical form, being
a prolongation of the cylinder, separated from the cylinder by a perforated plate
This passage communicates both with the source of supply, whence air is introduced
into the cylinder, and also with that whence gas is introduced. The air passes from
the valve for admission of air to the cylindrical passage, so as to enter it equally

page_text: all round the cylinder, for which purpose an oval or eccentric passage is provided
between the air-valve and the cylindrical passage.
The cylindrical passage communicates with the vessel or source of supply, whence
gas is introduced by another cylindrical passage of smaller diameter, the two
passages being concentric and separated by a perforated plate. Between the
smaller passage and the source of the gas supply is a valve governing the com-
munication; when this valve is opened gas passes through it into the smaller
cylindrical passage, and thence through the perforated plate into the larger
cylindrical passage, flowing into this in numerous streams parallel to the axis of
the cylinder, and mixing as it flows with the air in the larger cylindrical passage,
so that it forms in the central part of this a mixture of gas and air. This mixture
passes into the cylinder through the perforations in the perforated plate, which
divides the larger cylindrical passage from the cylinder, passing through a central
portion of these, whilst there is a certain annular space exterior to this through
which air passes into the cylinder unmixed with gas. Thus the inflammable
mixture when introduced into the cylinder occupies it in the manner desired, being
separated from the sides of the cylinder by an annular portion or stratum of air in
excess of the air needed for combustion.
The inflammable mixture thus introduced is not uniform in composition, but is
stratified in numerous strata or layers parallel to the axis of the cylinder, each of
these strata being graduated in its proportion of gas and air, this graduation being
principally in a radial direction.
In the above account I have spoken of gas as introduced from the gas pump or
gas supply, but the pump or apparatus instead of supplying pure gas, may supply
gas mixed with a certain amount of air.
In order to adjust the strength of the inflammable charge to the varying
requirements of the engine, the gas pump may be furnished with two supply valves,
one supplying gas the other air. By varying the opening of these valves the gas
drawn in or received by the pump can be mixed with air to any degree desired, so
as to lessen the amount of gas burnt in the cylinder to any desired degree, but
the quantity of air thus mixed with the gas is always less than that which would
form a combustible or explosive compound in the pump.
What has been said above of gas is applicable also when inflammable vapour is
used as an ingredient of the inflammable charge, which vapour may be generated
in a boiler or any suitable apparatus.
Again, instead of elastic fluid inflammable liquid might be injected so as to
mingle with the air in the form of spray, and form along with it a combustible
mixture in the cylinder situated within it in the manner previously described.
Although in the construction previously described transference of heat from the
ignited fluid to the metal is obstructed by the interposed air, yet it is to be
expected that nevertheless the metal may become a good deal heated. The heat
imparted to the metal may be removed by water applied externally, as is usual in
gas engines. But in some cases it may not be desirable to employ water for this
purpose, as, for instance, if the engine is used for locomotion. In such a case air
may be employed as the cooling agent, a current or currents of cold air being
created by a pump worked by the engine.
In such a case the following construction is applicable:-The air employed as
cooling agent is caused to issue in numerous jets from small orifices, so as to
impinge on the external surface of the cylinder. The orifices may conveniently be
disposed either in lines parallel to the axis of the cylinder or in lines concentric
with it, and many such lines may be employed.
Since I desire, as above explained, that the charge when ignited shall not be in
contact with metal, in order that it may not communicate its heat to the metal,
"I desire for like reason to ignite the charge in such a manner that no valve or
piece of metal shall be protruded into the cylinder, or so as to come into contact
with the inflammable charge at the moment of its ignition. The following is a
construction of igniting apparatus designed to carry out this purpose.

page_text: A chamber is provided in which a flame is to burn, which I shall call the flame
chamber. This chamber communicates by separate passages with the outer air,
and with the cylinder or vessel in which the inflammable mixture is to be ignited,
these passages being governed by slides.
In order to feed the flame in the chamber, gas and air are supplied to it
through separate passages by pumps. These passages are provided with check
valves, which allow flow from the pumps to the flame chamber but prevent flow
in the contrary direction. A flame is kept constantly burning in front of the
orifice through which the flame chamber communicates with the outer air.
Just after the charge in the cylinder has been ignited and communication
between the flame-chamber and cylinder closed, the pistons of the pumps make
their strokes of intake, and while they are doing this no flame is alight in the
flame chamber. At some point of time in this period communication is opened
between the flame chamber and the outer air. The pistons of the pumps then
make their strokes of delivery, sending air and gas into the flame-chamber, and
this is immediately ignited by the flame constantly burning outside. At this
period the pistons of the pumps move slowly, so that the flame in the flame-
chamber is not large. When it is desired to effect ignition, the communication
between the flame-chamber and outer air is closed, and the communication between
it and the cylinder opened; and at this period the pistons of the pumps move
rapidly, so that the flame in the flame chamber is increased. This flame passes
into the cylinder, and being made of sufficient size by the movement of the pistons
passes through the air or incombustible fluid between the side of the cylinder and
the inflammable charge, and pierces into the inflammable charge beyoud so as to
ignite it.
This having been done, the communication between the flame-chamber
and the cylinder is closed, and the pistons of the pumps make their intake strokes,
the point previously described being now reached.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Matthew Piers Watt Boulton in the Great Seal Patent Office on
the 3rd February 1882.
MATTHEW PIERS WATT BOULTON, of Tew Park, in the County of Oxford.
"IMPROVEMENTS IN ENGINES WHEREIN A PISTON IS PROPELLED IN A CYLINDER
BY IGNITION OF INFLAMMABLE GAS OR FLUID."
This Invention relates to engines in which a mixture of air with inflammable gas
or vapour or fluid is ignited behind a piston working in a cylinder and propels the
piston.
One object which I have in view is to introduce the inflammable charge, so that
it may be ignited when the piston is about to commence its stroke, or is at the
dead point moving slowly. And I also desire to work in such a manner that for
each ignition of the charge the piston shall not make more than one pair of
strokes, i.e., a forward and a return stroke.
Another object which I have in view and desire to attain as nearly as possible,
is to introduce the inflammable charge in such a way that it shall be separated
from the surfaces of the piston and cylinder by air or elastic fluid which does not
undergo combustion, in order that this air or fluid may obstruct passage of heat
from the ignited charge to the metal.
I provide a cylinder fitted with a piston which works the engine. The piston
does not work through the whole length of this cylinder. That portion of it in which
the piston does not work is intended for the reception of the charge. The eduction
valve is situated at or near the point where the piston approaches most nearly the
charging end of the cylinder.
Means are provided for clearing out the exhaust fluid from the portion of the
cylinder designed for the reception of the charge by causing air to sweep through
it, which may be done either by forcing air through it by means of a pump or
forcing apparatus, or by opening communication with an air vessel, in which air is
contained at the requisite pressure; or again by drawing air through the space by
movement of the piston which works the engine, or by a combination of such methods.
Means are also provided for introducing the gas or inflammable fluid in a similar
manner.
In describing the general course of operations, I shall suppose that pumps are
employed in order to introduce the air and inflammable fluid at the charging end
of the cylinder, and I shall speak of the inflammable fluid as gas.
I shall suppose for starting point that the charge has been introduced behind the
piston, and that the piston is ready to commence its working stroke.
The charge is ignited, and the high pressure consequent on the ignition propels
the piston. When the expansion has proceeded to the degree desired, the eduction
valve is opened. The pump for forcing air into the charging end of the cylinder
now begins to work. Air enters the cylinder at the charging end, and acting as a
fluid piston expels exhaust fluid from this part of the cylinder, occupying the space
vacated by the exhaust thus displaced. This action takes place while the piston is
still continuing its forward movement. The pump, injecting more air than is
needed to follow the advancing piston, expels a portion of exhaust through the
eduction valve. In this manner the exhaust is expelled from the charging end of
the cylinder and replaced with cool atmospheric air to such an extent as is desired
at this stage.
This having been done, the piston of the gas pump is brought into action and
injects the charge of gas into the charging end of the cylinder, whilst at the same
time the piston of the air pump continues to inject air, and a portion of the gas
and air thus introduced mix together and form an inflammable mixture in the space
designed for the charge at the charging end of the cylinder.
The operation above described may be varied as respects timing. The intro-

page_text: duction both of the air and gas might take place during the return stroke of the
piston, or it may take place; partly while the piston is advancing on its forward,
stroke and partly while it is returning. The latter seems generally to be the
preferable mode.
And it is evident that while the piston is advancing on its forward or working
stroke, it might drawn in both air and gas without the aid of pumps forcing
them in.
When the desired quantities of air and gas have been introduced, and before the
piston completes its return stroke, communication is closed between the cylinder'
and the sources of supply of gas and air. As the piston approaches or reaches the.
end of its return stroke the eduction valve is closed, and when the piston has.
completed its return stroke the point previously taken as starting point is reached.
In the above description I have supposed the air and gas to be injected by
pumps, but it is evident that they might be introduced from vessels in which the
air and gas are contained under pressure. The pressure in these vessels might
be caused by pumps worked by the engine; or the air and gas might be stored in
reservoirs and supplied from these at regulated pressure to the cylinder.
The piston in the latter part of its return stroke may compress the charge, just
as very commonly in steam engines it compresses the exhaust when it is desired
to cushion the steam, and the degree of the compression thus caused may be varied
to any extent desired by the timing of the closure of the eduction valve just as
ordinarily in steam engines.
I consider that in one respect there is considerable advantage in employing
compression, in that it enables a higher initial pressure and larger range of
expansion to be used by means of which a larger amount of the heat is converted
into work. With this view it may be found desirable to use a high degree of
compression.
When it is desired to compress the charge to any considerable extent the
following construction is applicable
A plunger or loose fitting piston is attached to the piston on the side of it
nearest the charging end of the cylinder. This plunger, when the piston returns
towards the charging end of the cylinder, advances into the charge and compresses
it, while the packed or close fitting part of the piston does not advance beyond the
eduction valve.
When a high range of expansion is used which, as above remarked, is important
for utilization of the heat, difficulty is created in the working of the engine by the
great difference between the initial and the final pressures, this tending to create
shock or sudden acceleration when the initial pressure acts on the piston. Hence
in such a case it is desirable to provide some means for lessening the inequality of
the pressures acting at different times on the piston.
In order to effect this the following construction is applicable.
The piston on that side of it which is not acted on by the ignited charge is acted
on by compressed air contained in an air vessel, so that a differential pressure is
obtained, reducing the amount of unbalanced pressure acting on it at the moment
of ignition and tending to equalise pressure generally. This arrangement also
lessens the amount of work imposed on the fly, since the compressed air drives the
piston in its return stroke.
To supply loss of the compressed air by leakage a pump is employed worked by
the engine.
In the above account I have not described any particular method of introducing
the air and the gas. I will proceed now to describe the method which I use. It
will be understood that this admits of many variations in detail.
One object which I have in view is to introduce the fluid in a direction
approximately parallel to the axis of the cylinder in order that it may act to a
great extent like a fluid piston, so as to displace the exhaust air in front of it
without creating eddies or mixing much with it.
Another object which I have in view is, as previously mentioned, to introduce

page_text: the inflammable mixture in such a way that it shall in all parts be separated from
the metal by a certain portion of air which does not undergo combustion when the
charge is ignited in order to lessen transference of heat from the ignited gases to
the metal,
In one construction of Lenoir's, means were provided by which the combustible
mixture might be separated by a certain portion of air from the piston and from
the end of the cylinder. I desire so far to produce a like condition, but I desire
also to separate the combustible mixture from the sides or curved surface of the
cylinder.
The separation of the combustible mixture from the piston is effected, in the
method which I use, by properly adjusting the stroke of the gas pump, or, if the
gas is admitted from a reservoir, by properly timing the valve which admits it.
In this way it is provided that the gas when introduced shall not advance in the
cylinder further than is desired, so that when the piston returns there is
portion of air between the piston and the combustible mixture.
certain
The introduction of the air behind the combustible mixture is effected by the
timing of the valves, the valve which governs the admission of gas being closed
somewhat before the valve which governs the admission of air.
In order to separate the inflammable mixture from the sides of the cylinder, and
also to introduce the air and gas in the desired direction, viz., parallel or nearly so
to the axis of the cylinder, I operate as follows :-
At the charging end of the cylinder I provide a passage of cylindrical form,
being a prolongation of the cylinder, separated from the cylinder by a perforated
plate. This passage communicates both with the source of supply whence air is
introduced into the cylinder, and also with that whence gas is introduced. The
air passes from the valve for admission of air to the cylindrical passage, so as to
enter it equally all round the cylinder, for which purpose an annular, oval, or
eccentric passage is provided between the air valve and the cylindrical passage.
The cylindrical passage communicates with the vessel or source of supply
whence gas is introduced, by another cylindrical passage of smaller diameter, the
two passages being concentric, and separated by a perforated plate. Between the
smaller passage and the source of the gas supply is a valve governing the
communication. When this valve is opened gas passes through it into the smaller
cylindrical passage, and thence through the perforated plate into the larger
cylindrical passage, flowing into this in numerous streams nearly parallel to the
axis of the cylinder, and mixing as it flows with the air in the larger cylindrical
passage, so that it forms in the central part of this a mixture of gas and air. This
mixture passes into the cylinder through the perforations in the perforated plate,
which divides the larger cylindrical passage from the cylinder, whilst there is a
certain annular space exterior to this through which air passes into the cylinder
unmixed with gas. Thus the inflammable mixture when introduced into the
cylinder occupies it in the manner desired, being separated from the sides of the
cylinder by an annular portion or stratum of air, in excess of the air needed for
combustion.
The inflammable mixture thus introduced is not uniform in composition, but
is stratified in numerous strata or layers parallel to the axis of the cylinder, each
of these strata being graduated in its proportion of gas and air, this graduation
being principally in a radial direction.
In the foregoing account I have supposed the vessel called the cylinder to be
parallel throughout, but this form may be somewhat varied. A slight taper may
be given to that part of the cylinder into which the charge is introduced so as to
make it smaller at the end at which the charge enters. If this taper is moderate
the object aimed at of making the charge act as a fluid piston may still be
Bufficiently secured.
In the above account I have spoken of gas as introduced from the gas pump or
gas supply, but the pump or apparatus instead of supplying pure gas may supply
gas mixed with a certain amount of air, and in this case the lower perforated
'

page_text: plate previously spoken of immediately over the gas valve may be dispensed
with.
In order to adjust the strength of the inflammable charge to the varying
requirements of the engine the gas pump may be furnished with two supply valves,
one supplying gas, the other air. By varying the opening of these valves the gas
drawn in or received by the pump can be mixed with air to any degree desired,
so as to lessen the amount of gas burnt in the cylinder to any desired degree.
But the quantity of air thus mixed with the gas is always less than that which
would form a combustible or explosive compound in the pump.
What has been said above of gas is applicable also when inflammable vapour is
used as an ingredient of the inflammable charge, which vapour may be generated
in a boiler or any suitable apparatus.
Again, instead of elastic fluid inflammable liquid might be injected so as to
mingle with the air in the form of spray, and form along with it a combustible
mixture in the cylinder situated within it in the manner previously described.
Although in the construction previously described transference of heat from the
ignited fluid to the metal is obstructed by the interposed air, yet it is to be
expected that nevertheless the metal may become a good deal heated. The heat
imparted to the metal may be removed by water applied externally, as is usual in
gas engines. But in some cases it may not be desirable to employ water for this
purpose, as for instance if the engine is used for locomotion. In such a case air
may be employed as the cooling agent, a current or currents of cold air being
created by a pump worked by the engine.
In such a case the following construction is applicable:-The air employed as
cooling agent is caused to issue in numerous jets from small orifices, so as to
impinge on the external surface of the cylinder. The orifices may conveniently
be disposed either in lines parallel to the axis of the cylinder or in lines concentric
with it, and many such lines may be employed.
Since I desire, as above explained, that the charge when ignited shall not be in
contact with metal in order that it may not communicate its heat to the metal, I
desire for like reason to ignite the charge in such a manner that no valve or piece
of metal shall be protruded into the cylinder, or so as to come into contact with
the inflammable charge at the moment of its ignition. The following is a
construction of igniting apparatus designed to carry out this purpose.
A chamber is provided in which a flame is to burn, which I shall call the flame-
chamber. This chamber communicates by separate passages with the outer air
and with the cylinder or vessel in which the inflammable mixture is to be ignited,
these passages being governed by slides. In order to feed the flame in the chamber
gas and air are supplied to it through separate passages by pumps. These
passages are provided with check valves which allow flow from the pumps to the
flame chamber, but prevent flow in the contrary direction. A flame is kept
constantly burning in front of the orifice through which the flame chamber
communicates with the outer air.
Just after the charge in the cylinder has been ignited and communication
between the flame chamber and cylinder closed, the pistons of the pumps make
their strokes of intake; and while they are doing this no flame is alight in the
flame chamber. At some point of time in this period communication is opened
between the flame chamber and the outer air. The pistons of the pumps then
make their strokes of delivery, sending air and gas into the flame chamber, and
this is immediately ignited by the flame constantly burning outside. At this
period the pistons of the pumps move slowly so that the flame in the flame-
chamber is not large. When it is desired to effect ignition, the communication
between the flame chamber and outer air is closed, and the communication between
it and the cylinder is subsequently opened, and at this period the pistons of the
pumps move rapidly, so that the flame in the flame-chamber is increased. This
flame passes into the cylinder, and being made of sufficient size by the movement.
of the pistons passes through the air or incombustible fluid between the side of the

page_text: cylinder and the inflammable charge and pierces into the inflammable charge
beyond so as to ignite it. This having been done the communication between the
flame chamber and the cylinder is closed, and the pistons of the pumps make their
intake strokes, the point previously described being now reached.
In the foregoing description the pumps of the igniting apparatus are supposed
to be worked by cams, and the flame enters the vessel B while the pumps are
moving rapidly. But these pumps may be driven by cranks, and the flame may
pass from the flame-chamber c into the vessel B while they are near the end of
their strokes of delivery and moving slowly.
according to my invention.
Figure 1a shews a portion of Figure 1 to a larger scale.
Figure 2, Sheet 1, is a cross section of the same.
Figure 3, Sheet 2, is an horizontal section of the same.
The same letters apply to all the above three views.
In the description I shall suppose that the engine is a vertical engine, but the
same construction remains generally applicable in whatever position the engine
may be placed.
C is the working cylinder open at the upper end to the atmosphere, fitted with
the piston P which drives the engine; B is a prolongation of the cylinder below C
into which the charge of gas and air is introduced. This prolongation has a
tapering or conical form, enlarging slightly from the lower end, where the charge
is introduced to the upper end; P₁ is a projecting body or plunger attached
at P; e is the eduction valve through which exhaust is expelled from C and B; n is
an annular passage of oval or eccentric form, serving as passage for the exhaust
between C and e.
A is the main air pump, which sends air into B, to drive out products of
combustion, and also to form part of the charge. This is fitted with a suction and
delivery valve, as shown; p is the tube by which air passes from A to B. At the
end of this tube nearest B is a second check valve u. From this valve the air
passes into m which is an annular passage of eccentric or oval form, and from this
it flows through the throat o into the space a.
x, x, x, is a plate perforated with numerous apertures or passages which have a
tapering form, enlarging as they ascend, so that air ascending through them may
be caused to spread. Between this plate and the curved surface of B is an annular
space through which air can pass. When the pump A delivers air into the space a,
this air passes from a through the perforations in x, x, and through the annular
space outside these into the vessel B.
G is a pump provided with two supply valves, as indicated in the Figure, one
connected with the atmosphere, the other with a gas supply. Each of these valves
is provided with a regulating cock or apparatus for adjusting the area of passage,
so that the proportions of gas and air taken in by the pump G can be adjusted as
desired. P g is the piston working in G.!
G delivers its charge through the delivery valve shewn into the tube t, and
thence into the space a, the communication being governed by a check valve v, as
shewn in the Figure, or by several such valves. From a the gas passes through
the perforations in x, x, and thence into the vessel B, mixing as it travels with a
further quantity of air.
In describing the course of operations I shall first describe one mode, it being
understood that it admits of variation in many respects. I shall suppose for
starting point that the working piston P is at the lower end of its cylinder, as
shown in the Figure, and that the charge of gas and air has been introduced into
the vessel B, and is ready for ignition.

page_text: Ignition is effected, and the rise of pressure consequent on it impels P, driving it
upwards. During this time the pistons of the air pump A and gas pump G are
making their strokes of intake.
When the pressure of the expanding fluid in C has fallen to the atmospheric, or
so far as is desired, u is opened, and Pa the piston of the air-pump A commences
its stroke of delivery. Air from this enters C at its lower end, following up the
exhaust fluid which follows the piston P.
An additional quantity of air may be injected by the pump A, so as to expel a
portion of exhaust through the eduction valve, which is opened for the purpose.
P having completed its up stroke commences its down-stroke, while A continues
to inject air into B as before. Exhaust is expelled by the action both of P and
of A. When a sufficient amount of air has thus entered B, Pg the piston of G
commences its stroke of delivery, and sends its charge of gas and air into B. While
it is thus delivering its charge Pa moves more slowly.
The mixture delivered by G into B becomes mixed with a further portion of air
as it enters B. But a certain portion of the air delivered by A, namely, that which
flows upwards next to the surface of B remains unmixed, or nearly so, with gas.
G having delivered its charge into B, the piston P g finishes its stroke of delivery
and v closes. Pa now moves again more rapidly and injects a further portion of
air into B, after which it finishes its stroke of delivery and u closes. At the same
time e the eduction valve closes.
The vessel B is now filled with elastic fluid in the following manner or
approximately so:-At both its ends, viz., its upper and lower ends, there is a
stratum or body of air, and all round its curved surface there is also a stratum of
air. The remaining portion of it is occupied by a mixture of gas and air in pro-
portions fit for combution when ignited within the cylinder.
After the closure of the eduction valve P continues to descend for some while
longer, and in doing this compresses the charge of gas and air beneath it. The
position of the charge in B when thus compressed is indicated by the dotted lines
in the Drawing. When P has completed its down stroke, and is about to commence
its up-stroke, the point previously taken as starting point is reached.
The quantity of gaseous mixture delivered into the vessel B may be varied by
varying the stroke of Pg the piston of the gas pump. This variation may be
made self-acting by means of a governor which adjusts the variation according to
the speed of the engine, so as to shorten the stroke and lessen the quantity of gas
delivered when the speed increases, and vice versa. As the means of adjusting
movements of this description by the action of a governor are well known, I do
not give any Drawing of apparatus for the purpose.
In the above account I have described the pump G as delivering a mixture of
gas and air; but this pump might deliver a charge of pure gas, the general con-
struction remaining the same.
Though I consider the perforated plate x, x, shown in the Figures, to be generally
useful it is not indispensable. If it were dispensed with I should consider it well
to prolong considerably the vessel B.
The charge of gas and air instead of being delivered by pumps into the space B
might be drawn in by the movement of the piston P. In such a case a valve is
provided in the same position as u, which governs communication with the atmo-
sphere, and a valve in the same position as v which governs communication with a
supply of gas, or of gas mixed with air. When P has advanced so far in its
working stroke that the pressure within C has fallen to that of the atmosphere or
just below it, u is opened or opens. The exhaust fluid within C follows P, while
the air entering from u in virtue of the atmospheric pressure, follows up the
exhaust fluid and takes the place at the lower end of B vacated by it.
When a
certain amount of air has thus entered B, v is opened and gas or gaseous mixture
is drawn in through it, and along with the air entering from u follows up the
exhaust fluid as this follows up P. When is opened the supply of air entering
through u may be diminished by a throttling of the passage governed by it.

page_text: When the proper charge of gas or gaseous mixture has been drawn in v is closed,
and the passage governed by u is again opened to full width, and an additional
portion of air is drawn in at the lower end of B. This continues till P reaches the
end of its up-stroke, P then descends and expels exhaust products of combustion
through e, while the air and gas continue to occupy the space within B, retaining
their position and arrangement with little change. At the proper time e closes,
after which P continues to descend, compressing the elastic fluid beneath it.
When P has completed its down-stroke the charge is ready for ignition.
The pump G instead of delivering gas or gas mixed with air may deliver
inflammable vapour, such as vapour of hydro-carbons, or a mixture of such vapour
with air. Such vapour may be generated in a boiler at or near the atmospheric
pressure, whence it is drawn or taken in as supply by the pump.
The heat of
the discharged products of combustion may serve in this case to generate the
inflammable vapour, and also when it is mixed with air to warm the air so
employed.
1
Figure 4 shews a construction in which compressed air acts on that side of the
piston which is not acted on by the ignited charge. Here C is the cylinder, P the
piston. The space E above P is not open to the atmosphere but closed at top,
the piston rod working through the gland and stuffing box 8. The space E com-
municates by the pipe p with A, an air-vessel containing compressed air; L is a
small pump worked by the engine which forces air into A, so as to supply loss by
leakage.
A variation of the construction is shewn in Figure 5. Here P the piston acted
on by the ignited gases in a trunk, and is connected with a larger piston P×
working in a cylinder of larger diameter. The upper part of this cylinder com-
municates with the air-vessel, as shown in the preceding Figure, the lower part
communicates with the atmosphere through apertures, as shewn.
When this construction is employed a lower pressure is employed in the air
vessel in obtaining the equalizing effect desired, and the compressing-pump worked
by the engine in order to supply leakage compresses to a lower pressure. Though
the employment of an air-vessel with compressed air is more especially useful when
a high degree of compression is given to the charge in B, yet it also remains useful
when little or no compression is given to the charge.
An apparatus for effecting ignition is shown in Figure 1. Here A is an air-
pump (which takes in air by a supply valve, as indicated,) and sends it along the
tube into the chamber a', the communication between q and a' being governed
by the check valve shown in the Figure.
G is a gas pump, which sends its charge of gas through the tuber into the
chamber g', communication between r and g¹ being governed by the check
valve shown in the Figure. The pump G' might be arranged so as to deliver a
mixture of gas and air. The gas sent into gl passes onwards through the orifice x¹
into the small chamber c which I call the flame-chamber, and the air sent from A¹
into a also passes into c, issuing into it through the annular orifice around g¹.
The chamber c is kept cool by a water casing w, or in any convenient manner.
For convenience of drawing the pumps A¹ and G' are shewn at some distance
from the flame-chamber c, but it is to be understood that they may be placed
nearer to it.
The chamber c communicates with the atmosphere
communication being governed by the slide k. In
constantly burning, this flame is represented by f.
municates with the vessel B through the orifice 0%,
governed by the slide Z.
through the orifice o', this
front of o¹ a flame is kept
The chamber c also com-
this communication being
The action of the apparatus is as follows:-The pumps A' and G¹ are making
their strokes of intake. At this period there is no flame in c, o² is closed, o¹ open.
The strokes of intake having been completed the pumps make their strokes of
delivery sending a current of air and gas into c. This issuing through the
opening o' is ignited by the flame f; o is now closed, and the pumps continue to

page_text: send air and gas into c so as to maintain the flame in it, while at the same time
the pressure in it rises. The pressure having been raised so as to become somewhat
superior to that in the vessel B the passage o² is opened, and the flame is forced
by the continued action of the pumps through o² into B. It passes through the
stratum of air next to its surface and piercing into the combustible mixture beyond
ignites it.
This having been done o' is closed and o' opened; the pumps commence their
strokes of intake, and the point previously taken as starting point is reached.
Instead of taking in pure gas the pump G' might take in a mixture of gas and air
and deliver this into the chamber c.
The following variation in the mode of working may also be made. The
pump Gin its stroke of intake first takes in its charge of gas or of mixed gas and
air, and afterwards takes in a certain quantity of pure air. In its stroke of
delivery it first sends in this pure air into the chamber c, and this along with the
air sent in by the pump A¹ clears out the chamber c of products of combustion.
This having been done the pump G₁ delivers its charge of gas or combustible
matter into the chamber c which is ignited therein, as previously explained.
An incandescent body may be employed in the chamber c in order to secure
maintenance of combustion in it while compression is going on. Asbestos is one
material which may be employed for this purpose, platinum another; also, instead
of an external flame, electricity may be employed internally to produce the
ignition. The various forms of apparatus used for the electrical light are
applicable for this purpose. The electricity employed may be generated by an
engine worked by the engine.
Figure 6 shows the cam for effecting the movement of Pa the piston of the air
pump A.
Figure 7 shows the cam for working the gas pump G.
Figure 8 shows the cam which governs the slide / between the flame chamber of
the igniting apparatus and the explosion chamber.
Figure 9 shows the cam which governs the slide k between the flame chamber
and the contact flame.
Figure 10 shows the cam which governs the exhaust valve e.
What I claim is,―
First. The method or process of introducing the explosive charge into the
cylinder or combustion-chamber of a gas engine (or engine worked by combustible
gas or fluid) in such manner that the said charge shall be enveloped with air, such
air being in excess of that needed for combustion and serving to keep the explosive
charge out of contact with the walls or surfaces of the cylinder or chamber in
which it is ignited, thereby obstructing the passage of heat from the ignited gases
to the walls or surfaces enclosing the said chamber.
Second. The igniting apparatus, substantially as described.
Third. The general construction and arrangement of a gas engine, substantially
as described in respect to Figures 1, 2, and 3 of the annexed Drawings.
Fourth. The modifications, illustrated by the Figures 4 and 5, of the engine
shown by the Figures 1, 2, and 3, in which modifications the piston P is subjected
to a pressure of air operating in a direction opposite to that in which the main
piston is propelled by the expansion of the charge when combustion takes place.
In witness whereof, I, the said Matthews Piers Watt Boulton, have hereunto
set my hand and seal, this Twenty sixth day of January, in the year of
our Lord One thousand eight hundred and eighty two.