Iм- PROVEMENTS 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 7th June 1878.
MATTHEW PIERS WATT BOULTON, of Tew Park, in the County of Oxford. "Iм-
PROVEMENTS IN GAS MOTOR ENGINES."
This Invention relates to engines worked by the combustion of a mixture of gas
and air or other inflammable mixture of elastic fluids, the products of the
combustion acting within the engine.
In gas engines as ordinarily constructed the cylinder is kept cool by an external
casing or envelope of cold water; owing to this the heat imparted to the metal of
the cylinder by the combustion is in a great measure abstracted uselessly, and
heat is abstracted from the fluid while it is performing work which causes loss of
efficiency.
The object of this Invention is to remedy in a great measure these defects,
providing means whereby the needful cooling of the interior is effected without the
external cooling of the cylinder, and also providing means whereby the heat
imparted to the metal by the combustion of the inflammable mixture is afterwards
imparted to the fluid while performing work, and so utilised.
I provide a cylinder which receives the inflammable charge, and in which it is
ignited, which I call the charging cylinder, and also another larger cylinder in
which the piston which drives the engine works, which I call the main cylinder.
I also provide a refrigerator or vessel kept cool by extended surface of pipes
cooled with water or by any known method of refrigeration, and I provide a
chamber or receptacle containing a certain quantity of air or incombustible elastic
fluid, which I place between the refrigerator and the charging cylinder.
Passages and valves are provided by means of which circulation can be caused to
take place through the space in the cylinder containing the fluid which has
performed work and the refrigerator at such times as is desired.
In order to cause the circulation I provide a fan or other suitable rotating
instrument, or otherwise it may be caused by a piston in a cylinder.

page_text: And in order to make the contents of the space previously mentioned in the
main cylinder pass through the refrigerator, I arrange inlet and outlet passages
opening into the cylinder at its end.
The current caused by the fan issuing through the inlet with velocity, is carried
up through the space to the piston and afterwards passes out of the cylinder by the
outlet, thus sweeping through the space. Or otherwise I attach to the piston of
the main cylinder a pipe arranged to work in a tube external to the cylinder, the
pipe and tube being of such length as to constitute a channel through which at
every stage of the piston's movement the passage of fluid previously described can
take place.
I proceed to give a discription of the mode of operation.
It will be understood that some of the details mentioned admit of variation, some
of the variations being pointed out by me afterwards.
The charging cylinder is filled with its charge of inflammable mixture. Com-
munication is open between it and the receptacle containing air or incombustible
elastic fluid. Communication between this fluid and the refrigerator is prevented
by a valve. The charge is ignited and products of combustion rush from the
charging cylinder into the receptacle just mentioned, heating the fluid within it
and raising its pressure. At the same time heat is imparted to the metal sides of
the charging cylinder and the receptacle, the former especially being highly heated.
Just after the ignition a valve is opened between the charging cylinder and the
main cylinder. Products of combustion enter the main cylinder and propel its
piston.
As the pressure of the expanding fluid falls, fluid issues from the receptacle and
passes through the charging cylinder into the main cylinder. In passing through
the charging cylinder it abstracts heat from its heated surface, this enabling it to
expand with less rapid fall of pressure and so performing work. The fluid expands
till its pressure falls to that in the refrigerator, immediately after which the valve
between the refrigerator and the receptacle opens, and fluid issues from the
refrigerator, passing through the receptacle, and afterwards through the charging
cylinder into the main cylinder and further abstracting heat from their metal, which
heat is utilised as previously explained.
•
When the piston of the main cylinder has arrived at or near the end of its stroke,
communication is opened by the valve provided for the purpose between the
refrigerator and the main cylinder, and circulation is caused by the fan or other
instrument employed, through the refrigerator and space occupied by the fluid
which has performed work. The piston in the main cylinder now returns,
compressing the fluid which has performed work. Circulation through the re-
frigerator is still maintained, and thus the heat due to compression or the larger
portion of it is abstracted by the refrigerator.
When the pressure of the fluid has been raised to the atmospheric, a valve opens,
and as the piston proceeds a portion of fluid is expelled.
The fluid may remain at this pressure during the remainder of the stroke, but if
it is desired to work with compressed or high-pressure fluid, by employing which a
higher efficiency is obtainable, the escape valve is closed after a certain time and
the fluid is compressed during the remainder of the stroke.
While the main piston is performing its return stroke, the charging cylinder
receives a fresh charge of inflammable mixture. The return stroke having been
completed and the charging cylinder having received its charge, the operations are
ready to be repeated.
When the engine is so worked as to produce high pressure at the end of the
stroke, the time during which the escape valve remains open or its area of discharge
is made adjustable, so that the quantity of fluid permitted to escape can be varied
at pleasure. And the valve may be regulated by regulating apparatus connected
with a governor, so as to vary the quantity of discharge, according to the speed of
the engine.
In the description above given I suppose the inflammable charge and the fluid in

page_text: the receptacle to be introduced at the same pressure; but I consider that the
highest efficiency is attainable when the fluid in the receptacle is raised to a
pressure higher than that of the inflammable charge before its ignition, viz., to a
pressure nearly equal to that produced in the charging cylinder by the ignition of
the mixture. In this case a valve is provided between the receptacle and the
charging cylinder, which is opened just after the ignition of the mixture. And no
valve need in this case be provided between the receptacle and the refrigerator.
On first working the engine the charge and the fluid in the receptacle may be at
the atmospheric pressure.
After the engine has been put to work, the compressing action may be brought
into play, and the inflammable charge and the incombustible fluid acted on may be
compressed to such degrees as is thought proper.
The engine may be double acting, the parts and operations being duplicated.
When the engine is so worked as to produce by expansion a sufficiently low
temperature, the refrigeration of the fluid may be produced by causing it to pass
through water or through a saline solution of high boiling point, or to be brought
in contact with it in any way desired.
The piston of the charging cylinder may be protected by a shield, so as to work
in a part of the cylinder which is never subjected to great heat.
If it is desired to generate and use steam, then the pipes or surfaces in the
refrigerator which abstract heat, have on the other side of them water or liquid
contained within a boiler, and the steam or vapour generated from this liquid is
employed to assist in working the engine in any manuer desired.
For the purpose of regulating the engine, I fit in the passage which supplies the
gas to the charging cylinder, a valve or moving piece worked by a governor, so
that as the speed of the engine increases, the area of this passage is diminished and
less gas is supplied to the combustible mixture, and conversely, when the speed
of the engine decreases the area of passage is increased and more gas is supplied.
When inflammable vapour is used instead of gas to work a gas engine, this
vapour may be generated from benzole or a hydrocarbon of low boiling point. In
boiling such a liquid inconvenience is caused by priming. As one means of
preventing this I place water or a saline solution of high boiling point within the
vessel in which the benzole or liquid is to be boiled, maintaining the water or
saline solution at a heat above the boiling point of the benzole, and I cause the
benzole to pass through the water or saline solution in small streams or particles,
the water or saline solution being, by preference, kept in a state of agitation
As another means I subject the vapour of the benzole or liquid to heat in a
separate vessel, so as to convert into vapour the liquid particles suspended in it.
One mode of doing this is to cause the vapour to pass in bubbles or finely divided
streams through water or saline solution heated to a degree above the boiling point
of the benzole or liquid.
The warming of the pipes through which the vapour flows to the cylinder may be
effected by fluid discharged from the engine.