IMPROVEMENTS IN GAS MOTOR ENGINES
Year: 1878

page_text: PROVISIONAL SPECIFICATION left by Matthew Piers Watt Boulton at the
Office of the Commissioners of Patents on the 29th June 1878.
_MATTHEW PIERS WATT BOULTON, of Tew Park, in the County of Oxford.
"IMPROVEMENTS IN GAS MOTOR ENGINES."
This Invention relates to engines worked by the combustion of an inflammable
mixture of elastic fluids, the products of combustion being used in the engine.
In the following descriptions I shall speak of gas and air as the ingredients used,
it being understood that what is said of these is applicable when other clastic fluids
are employed. Again, where I speak of the heat as generating steam from water,
it will be understood that other liquid might be converted into vapour, and this
utilised in like manner.
One form of engine according to my Invention is as follows:-I provide a vertical
cylinder fitted with a piston; the lower end of the cylinder is provided with apparatus
for the introduction of an inflammable mixture of gas and air and of other Huid to
be heated by their combustion. Any known apparatus for this purpose may be
employed. The upper end of the cylinder contains or is in communication with a
considerable space, which constitutes a steam space, as in a steam boiler; the piston
which works in the cylinder carries on its upper side a certain quantity of water
in contact with the interior surface of the cylinder, the supply of this water being
maintained by suitable feeding apparatus. The hot gases resulting from the com-
bustion of the inflammable mixture as they expand and drive the piston upwards
heat the metal of the cylinder. On the return stroke the descending piston brings
the water which it carries in contact with the heated surface, and in consequence
steam is generated in the space above the piston; thus the pressure of the steam in
the steam space always acts on the upper side of the piston, while on its under side
there is in the up stroke the high pressure of the heated gases, and in the down
stroke the low pressure of these gases after performance of work.
Two cylinders may be provided, the piston of the one cylinder being acted on by the
peated fluid, while the other is not so alternately; also the piston acted on, as above

page_text: described, may be a differential piston, the upper side of this which carries the water
having the smaller area. In this case, with the use of one cylinder, both strokes are
directly effective in driving the engine.
A portion of the steamn occupying the steam space above mentioned is admitted
for each up stroke into the space where the fluid is to be heated by the combus-
tion, and acts as working fluid. Compressed air or other fluid may be used in
conjunction with it.
Instead of introducing the inflammable mixture into the cylinder while the
steam therein is at high pressure, it may be introduced or drawn in later when the
pressure of the steam is reduced by expansion. The combustion then raises
the pressure of the mixed fluid, and it expands, driving the piston. At the same
period in like manner air or incombustible fluid may be introduced or drawn in,
which in addition to the steam is acted on by the heat of the combustion. The
fluid, after performing work in the cylinder, may be discharged into the atmosphere,
or into or through a condenser or refrigerator.
When it is desired to use compressed fluid to act along with the steam the com-
pression of such fluid may be effected by the piston in a portion of the return
stroke after a certain quantity of fluid has been discharged through an eduction
valve.
The fluid undergoing compression may be caused to pass through a refrigerator
or condenser.
The eduction valve is made capable of adjustment, so that the quantity of fluid
allowed to escape can be varied at pleasure, and the adjustment may be regulated
by a governor, so as to vary it according to the speed of the engine.
In cases where it is not desired to use steam under pressure, as above described,
the upper end of the cylinder may be open to the air, the water carried by the
piston serving to cool the metal of the cylinder during the return stroke; this heat
need not be abstracted from the cylinder during the working stroke, which is effected
by the expansion of the fluid or gases resulting from the combustion of the inflam-
inable mixture.
I proceed to describe a method of introducing the inflammable mixture; and
effecting the combustion which is applicable not merely to engines constructed as
above described, but generally to various forms of gas motor engines.
Pumps or cylinders fitted with pistons are provided, whereby the gas and air are
delivered into a chamber or space in proportions suitable for combustion, so as to
mix together as they issue from the delivering cylinders, and undergo combustion;
this combustion going on while the pistons of the aforesaid cylinders make their
strokes occupies a sensible time, and takes place quietly.
I prefer to make the mixture of the gas and air in two successive stages, so that
the gas is first mixed with a certain suitable portion of air, and afterwards the steam
of this mixed gas and air meets another stream of air, this final mixture undergoing
combustion.
The first mixture of gas and air may take place in a passage or chamber outside
the delivering cylinders; or one of these cylinders may be filled with the mixture
of gas and air, this having been effected previously.
The combustion of the gas and air is caused to take place within a close chamber
containing elastic incombustible fluid, and in consequence of the combustion rise of
pressure takes place in this chamber.
As the charges are expelled from the delivering cylinders fluid from the space or
chamber in which the combustion takes place, or from a space in connection with
this, enters behind their pistons, so that as the pressure rises in consequence of the
combustion, it rises equally or nearly so on both sides of the pistons.
When the fluid to be heated is at high pressure previous to combustion, the
delivering cylinders should be charged with the inflammable ingredients at an equal
pressure, having received them at this pressure from pumps or otherwise.
In thus operating the pressure outside, the delivering cylinders would rise owing

page_text: to the combustion sooner than the pressure within them, and this would tend to
cause some backward flow of fluid into these cylinders; this may be prevented by
causing the delivering pistons to move with a varying velocity, or by varying the
areas of the discharging apertures of the delivering cylinders; otherwise pumps may
be employed to force their charges into the high-pressure fluid which it is desired to
heat without their pistons being put in equilibrium, as above. explained.
The movement of the pistons employed to supply the inflammable ingredients is
by preference timed so that their stroke takes place while the working piston is
perforining a small portion of its stroke; this may be done by means of a cam, or
by any known suitable contrivance.
Another mode of operating is to fill the space in which the combustion is to
take place with air, and sond into it from a cylinder a charge of gas and air nixed
in such proportion as not to be combustible in the cylinder; this mixture undergoes
combustion in the air contained in the space. In this case it is advantageous to
provide channels in communication with the lower part of the cylinder or space in
which the combustion takes place, so that a circulation may be caused of the fluid
in that space, by means of which the lower part of the flame may be fed with air.
When steam is used a portion of it may be employed to drive the piston or pistons
employed to deliver the supply of fluid for the purpose of combustion, as above
explained, into the cylinder or space in which the combustion is caused to tako
place. In this case it is of advantage so to operate that the pressure of the steam
acting on the delivering piston or pistons, and that of the fluid in which the com-
bustion is taking place, shall remain nearly equal and shall be nearly equal at the
end of the combustion.
It is to be understood that in the constructions above described the space in
which the combustion is caused to take place may be a portion of the working
cylinder.
For the purpose of effecting the ignition of the inflammable mixture I employ the
following construction:-I provide a chamber, within which a gas flame is made to
burn at certain times at the ordinary or atmospheric pressure. The gas and air
which feed this flame are governed by valves, which may be self-acting, and the
chimney or tube by which the products of combustion pass away is governed by a
valve in like manner.
A passage is provided governed by a valve worked by the engine, so that com-
munication between this chamber or vessel containing the inflammable mixture
which it is desired to ignite is opened and closed at certain times. Outside the
mouth of the chimney of the flame chamber previously mentioned and near to it a
gas flame is kept constantly burning at the ordinary or atmospheric pressure.
When the time arrives at which it is desired to ignite the mixture the slide or
valve opens the passage previously mentioned, so as to make communication between
the flame chamber and the chamber containing the inflammable mixture.
I shall first suppose the inflammablo mixture in this chamber to have a higher
pressure than the pressure in the flame chamber. In virtue of this it rushes or
flows into the flame chamber, and is ignited by the flame there, and the ignition
strikes back into the chamber containing the inflammable mixture. Just at this
moment the valves which govern the communications of the flaine chamber with
the outer air and gas supply are closed; the supply of flame being cut off it is
extinguished.
The valve now closes the communication between the flame chamber and the
chamber in which the mixture was ignited, and the communications of the flame
chamber with the outer air and the gas supply are opened.
The gas and air supplied to the chamber rise through the chimney, and issuing
from its mouth come in contact with the flame there kept constantly burning. In
consequence of this they are ignited, and the ignition striking back lights the flame
in the chamber. The operation is then ready to be repeated.
When the combustible charge is drawn into the cylinder, as in many forms of
gas engines, then the action is as follows:-Other communications with the space

page_text: behind the advancing piston of the engine being closed, communication is opened
between it and the flame chamber. In consequence of this a portion of the flame is
sucked or drawn into the cylinder, so that it ignites the combustible charge within
it. In consequence of the rise of pressure caused by the combustion, fluid from the
cylinder rushes into the flame chamber, closes the valves which govern its commu- 5
nications with the air and gas, and puts out the flame. Afterwards, as previously
described, the communication between the flame chamber and cylinder is closed,
the other valves re-open, and the flame in the flame chamber is relighted.