Improvements in Certain Gas Engines.
Year: 1887

page_text: Date of Application, 2nd Apr., 1887
Complete Left, 2nd Jan., 1888
Complete Accepted, 3rd Feb., 1888
PROVISIONAL SPECIFICATION.
Improvements in Certain Gas Engines.
I THOMAS STURGEON of Ilkley in the county of York Engineer do hereby declare
the nature of this invention to be as follows:-
In the specification of a patent granted to me bearing date the 23rd July 1885
No. 8897 I describe a gas engine having two pistons working in one cylinder-These
two pistons work through the medium of levers or beams and connecting rods on to
a double crank shaft and in connection with this arrangement there is used a separate
charging cylinder. My present invention consists in a better arrangement of the
essential parts of such an engine. In my improved arrangement I place the charging
cylinder mid way between the two extremes of the working cylinder and I also
arrange the valve that the charge of mixed gas and air, after being drawn into the
charging cylinder, will be delivered therefrom mid way between the two pistons in
the working cylinder. For this purpose I prefer to use a slide valve which is so
arranged that it will first permit the charging piston to draw in a charge of mixed
gas and air and then, sliding into another position, will allow this charge to be
delivered into the working cylinder mid way between the two pistons as already
stated.
The products of combustion of the former charge pass out through the exhaust
ports formed near the two ends of the working cylinder.
On the return stroke of the valve a firing port or pocket which it contains is
opened to the port in the working cylinder through which the charge has just passed
and the charge, which by this time is compressed by the inward strokes of the
working pistons is thereby fired.
The arrangement above described may also be duplicated, that is to say, two sets
of similar cylinders with their respective pistons may be fixed side by side and work
on to the same double crank shaft, the cranks being made sufficiently wide to admit
the brasses of the necessary extra connecting rods.
In this arrangement while the charge is being fired in one of the working
cylinders the other will be open to the exhaust.
The top beams may be carried in independent bearings or may both rock on the

page_text: same fixed shaft. These beams would be straight that is to say each would have its
two arms in the same vertical plane. The two bottom beams, which are required to
be cranked, might be constructed as follows. The two arms of one might be cast in
different vertical planes upon a hollow shaft or barrel while the two arms of the
other beam are keyed in different vertical planes upon a strong shaft which passes
through the hollow shaft or barrel of the other beam.
An engine constructed with duplicate cylinders as above described would give two
impulses in every revolution of the crank shaft.
Dated this Thirty-first day of March 1887.
THOMAS STURGEON of Ilkley in the county of York Engineer 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 :-
In the Specification of a l'atent granted to me bearing date the 23rd July 1885
No. 8897 I describe a gas engine having two pistons working in one cylinder. These
two pistons work through the medium of levers or beams and connecting rods on to
a double crank shaft and in connection with this arrangement there is used a separate
charging cylinder. My present invention consists in a better arrangement of the
essential parts of such an engine-In my improved arrangement I place the charging
cylinder imidway between the two extremes of the working cylinder and I also arrange
the valve that the charge of mixed gas and air after being drawn into the charging
cylinder will be delivered therefrom midway between the two pistons in the working
cylinder. For this purpose 1 prefer to use a slide valve, which is so arranged that it
will first permit the charging piston to draw in a charge of mixed gas and air and
then sliding into another position, will allow this charge to be delivered into the
working cylinder midway between the two pistons as already stated.
The products of combustion of the former charge pass out through the exhaust
ports formed near the two ends of the working cylinder. On the return stroke of
the valve a firing port or pocket which it contains is opened to the port in the
working cylinder through which the charge has just passed and the charge
which by this time is compressed by the inward strokes of the working pistons, is

page_text: thereby fired. Fig. 1. in the accompanying drawings shews the pistons in the
working cylinder just as they have completed their inward stroke and the charge
confined between them has reached its maximum amount of compression. The
piston of the charging cylinder or pump is now at the quickest part of its outward
stroke, drawing in a fresh charge of gas and air for the next revolution.
In Fig. 2. the valve is shewn in the position it occupies at this moment, the air
and gas passages being fully open to the charging pump and the working cylinder
being in momentary communication with the igniter-Ignition of the charge in the
working cylinder now takes place, the two working pistons being driven apart.
When they have made about half their stroke and are in the position shown in
Fig. 3. the pump piston has arrived at the end of its outward stroke and completed
the drawing in of the new charge. This piston now commences slowly returning
and at the same time the working pistons are travelling through the quickest part
of their outward stroke (the expansive force of the charge being rapidly converted
into useful work). When this force has been almost entirely expended the working
pistons uncover the exhaust ports and any remaining pressure in the cylinder at
once vanishes. The working pistons now reach the end of their outward stroke the
relative positions being shewn in Fig. 4. The exhaust ports are now fully open and
the pump piston is at the quickest part of its inward stroke impelling the new charge
through the valve passage into the working cylinder-and thus driving the remaining
products of combustion through the exhaust ports. The position of the slide valve
at this moment is shewn in Fig. 5. The pistons in the working cylinder now
commence making their inward strokes and gradually compress this new charge
until they again reach the position shewn in Fig. 1. when it is again fired and the
series of operations already described is repeated. Similar letters refer to the same
parts in the drawings. A is the working cylinder. B the charging cylinder or pump.
Care the exhaust ports opening into the exhaust passages DD which lead to the
chamber E E. The two parts of this chamber being connected together by the
passage F F. The exhaust may then be carried off by the passage G in the bed to
which the exhaust pipe G may be attached in some convenient part. H H is a
passage leading from the bed by which the air is conducted to the slide valve which
it enters at I, the gas entering the valve through the small holes K in the slide valve
and mixing with the air on its passage to the charging cylinder-Lis the gas valve.
The proportion of the area of the air passage in the slide valve to the area of the gas
holes K should be such as to give a mixture of about 7 of air to 1 of gas. M is the
igniter which is of the ordinary construction being simply a small bent tube heated
by a Bunsen burner, the tube being within a chimney lined with asbestos-The
igniter and gas valve are carried on the slide-valve-cover which is kept up to its
place by springs and clamps in the ordinary manner.
The arrangement above described may also be duplicated, that is to say, two sots
of similar cylinders with their respective pistons may be fixed side by side and work
on to the same double crank shaft, the cranks being made sufficiently wide to admit
the brasses of the necessary extra connecting rods. In this arrangement while the
charge is being fired in one of the working cylinders the other will be open to the
exhaust.
The top beams may be carried in independent bearings or may both rock on the
same fixed shaft. These beams would be straight, that is to say, each would have its
two arms in the same vertical plane. The two bottom beams which are required to be
cranked, might be constructed as follows. The two arms of one might be cast in
different vertical planes upon a hollow shaft or barrel while the two arms of the other
beam are keyed in different vertical planes upon a strong shaft which passes through
the hollow shaft or barrel of the other beam.
An engine thus constructed is shewn in Figs. 6. 7 & S, Fig. 6. being a side
elevation Fig. 7 a front view and Fig. 8, a plan. The construction of this engine
will be at once understood from a glance at the drawings. It is simply a duplicated
arrangement of the engine already described. In the plan the beams and connecting
rods are supposed to be removed so as to prevent confusion. The connecting rods

page_text: of the charging piston are bent or have their bosses at the small ends to one side of
the rods and at their big ends the brasses fit on to the cranks between the brasses of
the working connecting rods as shewn at N. N Fig. 7. The construction of the
bottom beams is shewn at Fig. 9.
The two levers O. O are keyed or otherwise secured on the shaft P while the other
two beams QQ are cast on the barrel R.
The large openings at the front and back of the bed allow easy access to the small
brasses of the bottoin connecting rods and links.
An engine constructed with duplicate cylinders as above described would give two
impulses for every revolution of the crank shaft.
In Fig. 6. the mode of governing the engine is shewn. The slide valve carries a
projection S which works against an inclined lever T and thus causes an up and down
motion in the short lever with the projecting lip U. Underneath this lipped lever is
a block on a slide carried by the governor lever V. and this slide rests on the gas-
valve spindle W. Thus when the block is in position, the gas valve will be opened
each time the slide valve moves forward but when the engine runs too quick the
governors will rise and so the block will be carried away from underneath the lip
on the lever U and thus the gas valve will not be opened until the engine has
sufficiently slowed down to bring the block again under the lever U. The governor,
which is of ordinary construction, is shewn at X and is driven by a small helt from
the main shaft. The gas valve is an ordinary mushroom valve inverted and held to
its seat by a spring.
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. The improvements on my former patent No. 8897. 23rd July 1885 by which
the charge is delivered mid-way between the two working pistons.
2. The arrangements for duplicating the engine.