IMPROVEMENTS IN GAS ENGINES
Year: 1885

page_text: I THOMAS STURGEON of Ilkley in the county of York Engineer do hereby
declare the nature of my invention for IMPROVEMENTS IN GAS ENGINES to be
as follows:-
My improvements consist in a novel arrangement for a gas-engine by which
certain important advantages are obtained-In this engine I use two working
pistons of the trunk form, working, by preference, in a vertical cylinder open at
both ends The charge of mixed gas and air is compressed between these two
pistons and when fired it forces one piston upwards and the other downwards the
motion being transferred through the medium of suitably arranged beams or
levers and connecting-rods, to a double crank-shaft. The two cranks are set
opposite to each other and one of these cranks is also connected to the piston of a
charging or supply cylinder which is placed at right angles or nearly so to the
working cylinder. The engine is provided with a suitable igniter or ignition valve
for igniting the charge at the proper moment. Certain ports are provided in the
working cylinder and the pistons open these ports by passing over them towards
the end of their outward stroke-One set of these ports is arranged to open sooner
than the other and is in communication with the exhaust pipe-The other set of
ports communicate with the charging cylinder. The action is as follows. On the
fly wheel being revolved in the proper direction a charge of mixed gas and air is
drawn into the charging cylinder through a suitable admission valve. The further
motion of the crank will then cause the charging piston to commence returning
into the charging cylinder thereby slightly compressing the charge it has just taken
in. At this moment the admission ports of the working cylinder are opened and
the charging piston which is now passing through the quickest part of its stroke
supplies a charge of mixed gas and air to the working cylinder. This charge is
then compressed by the inward movement of the two pistons and ignited when the
pistons reach that part of the stroke when they are nearest together-The
expansive force thus generated causes the pistons to make their outward stroke
and is communicated to the crank shaft as already described until those ports
which communicate with the exhaust pipe are opened-Any remaining presure
at once vanishes the contents of the cylinder falling to atmospheric pressure. The
4

page_text: admission ports are now opened and a new charge enters driving before it a portion
of the products of combustion from the previous charge, which pass out through
the exhaust ports and thence to the exhaust pipe-This new charge is then com-
pressed between the two pistons, is fired, and the series of operations already
described is repeated, the crank-shaft receiving a fresh impulse once in every
revolution.
Dated this 21st day of July 1885.
THOMAS STURGEON of Ilkley in the county of York, Engineer do hereby declare
the nature of my invention for IMPROVEMENTS IN GAS ENGINES and in what
manner the same is to be performed, to be particularly described and ascertained
in and by the following statement:-
My improvements consist in a novel arrangement for a gas engine by which
certain important advantages are obtained. I use two working pistons of the
trunk form working by preference in a vertical cylinder open at both ends. The
charge of mixed gas and air is compressed between these two pistons and when
fired it forces one piston upwards and the other downwards the motion being
transferred through the medium of suitably arranged beams or levers and con-
necting rods to a double crank shaft. The two cranks are set opposite to each
other and one of these cranks is also connected to the piston of a charging or
supply cylinder which is placed at right angles, or nearly so, to the working
cylinder. The engine is provided with a suitable igniter or ignition valve for
igniting the charge at the proper moment. Certain ports are provided in the
working cylinder and the pistons open these ports by passing over them towards
the end of their outward stroke. One set of these ports is arranged to open sooner
than the other and is in communication with the exhaust pipe. The other set of
ports communicate with the charging cylinder. The action is as follows. On the
fly wheel being revolved in the proper direction a charge of mixed gas and air is
drawn into the charging cylinder through a suitable admission valve. The further
motion of the crank will then cause the charging piston to commence returning
into the charging cylinder thereby slightly compressing the charge it has just taken
io. At this moment the admission ports of the working cylinder are opened and
the charging piston, which is now passing through the quickest part of its stroke,
supplies a charge of mixed gas and air to the working cylinder-This charge is
then compressed by the inward movement of the two pistons and ignited when the
pistons reach that part of the stroke where they are nearest together. The
expansive force thus generated causes the pistons to make their outward stroke

page_text: and is communicated to the crank shaft as already described until those ports
which communicate with the exhaust pipe are opened. Any remaining pressure
at once vanishes the contents of the cylinder falling to atmospheric pressure-
The
admission ports are now opened and a new charge enters driving before it a portion
of the products of combustion from the previous charge which pass out through
the exhaust ports and thence to the exhaust pipe. This new charge is then com-
pressed between the two pistons, is fired, and the series of operations already
described is repeated, the crank shaft receiving a fresh impulse once in every
revolution. In Figs. 1, 2, 3 and 4 of the accompanying drawings are shewn certain
views of a gas engine constructed in accordance with my invention. Fig. 1. is a
longitudinal section taken through the working cylinder. Fig. 2 is a longitudinal
section taken through the charging cylinder Fig. 3. a cross-section taken through
the admission valve box and the working cylinder, the pistons being omitted, and
Fig. 4. a partial front view shewing the double crank shaft-In these views similar
letters refer to the same parts. A. A. is the working cylinder which is water-
jacketed as is usual in gas engines the cold water entering by the pipe B and the
heated water passing off by the pipe B¹. The two working pistons are shewn at C
and C. The double crank shaft is shewn at D with the two cranks D¹ and D'.
The working pistons are connected to these cranks by means of the links E and E¹
the beams F F and the connecting rods G. G¹. In Fig. 5 is shewn a plan of the
bottom beam F. F. The charging cylinder is shewn at H, its piston I receiving its
to and fro motion from the connecting rod G in the manner shewn through the
connecting rod K. The admission valve is placed at L. The arrow shews the
direction in which the shaft runs. In Figs. 1 and 2 the pistons and cranks are
shewn in the position they occupy just when the charge in the working cylinder is
being fired. At this moment the gas and air valves at L are fully open and the
charging piston I is moving outwards at the quickest part of its stroke thereby
drawing a new charge of mixed gas and air into the charging cylinder-The charge
in the working cylinder being fired the working pistons commence making their
outward stroke impelling the crank shaft round by virtue of the explosive force
of the gases until the piston C in its upward course exposes the exhaust
ports M. M. which are a series of holes drilled through the wall' of the working
cylinder. Should the products of combustion at this moment be in excess of the
pressure of the atmosphere they will now pass through the annular space M¹ & the
branch M to the interior of the pillar M³, which forms an exhaust box and out
into the atmosphere by the pipe M. The contents of the working cylinder will
thus fall to atmospheric pressure. The shaft being still carried round under the
momentum of the fly wheel the lower piston C in completing its stroke, opens
the ports N N-In the meantime the admission valves have been closed and the
charging piston I has commenced its inward stroke-This charging piston makes
the greater part of its inward stroke during the time that the ports N are open.
The charge of mixed gas and air which has been taken into the charging cylinder
during the previous outward stroke of the charging piston will thus be driven
through the passages 0. O and the ports N. N. into the working cylinder. This
passage surrounds the working cylinder gradually diminishing in area as it
distributes the charge through the ports N. as is shewn in Fig. 6 which is a
sectional plan of these passages taken on line X. Y. Fig. 3. A fresh charge of
mixed gas and air being thus introduced into the working cylinder a corresponding
amount of the products of combustion remaining from the previous charge will be
displaced being forced through the exhaust ports and, the shaft still continuing to
rotate under the influence of the momentum of the fly wheel, the working pistons
will make their inward stroke until again reaching the position shewn in Fig. 1.
the new charge will be fired and the series of operations already described will be
repeated. As the exhaust box M³ might under some circumstances become filled
with mixed air and gas which might become accidentally ignited and so cause an
explosion in this box it should be provided with a safety valve as shewn at P in
Fig. 1. I will now proceed to describe the admission valves for the gas and air-

page_text: and the method of governing the engine which I prefer to adopt in connection
with my invention and which I have shewn in the drawings on a larger scale.
Fig. 7 is a longitudinal section through the admission valve and governors. Fig. 8
a side view Fig. 9 a front view of the governor and Fig. 10 a plan of the levers
by which the valves are worked and the stand for carrying them and the governors.
In these views H is a portion of the charging cylinder, L is the admission valve
box, O the passage leading from the admission valve to the charging cylinder
and thence to the working cylinder. A is a piston valve working in the valve
box L an up and down motion being imparted to it by means of the lever B keyed
on the same shaft as the lever C which is worked from the eccentric Q (Fig. 4) by
means of the rod D (Fig. 8). This valve is furnished with openings e. e. which at
the proper moment open to corresponding ports f. f. in the valve box L-In Fig. 7 it
is shewn in its open position. G is the gas valve which fits like a cap over the gas
box G¹, the gas box and valve being furnished with corresponding ports i. i. The
gas pipe is coupled up to the gas box at K. The gas valve G is worked by the
lever M which is keyed on the same shaft as lever N. (Figs. 8 and 10).
This lever (shewn in plan at Fig. 11), receives its motion as follows. On the
lever C is another leg P the end of which is formed into a boss carrying the
adjustable stud P¹. The end of the lever N is formed into a cup carrying a leather
pad N¹.
When the stud P¹ presses on the pad N¹ the gas valve is raised and it is
brought down again by the spring R. pulling on the extension of the lever M.
When the engine runs too fast the governors rise and cause the catch S to be
brought under the projecting blade T on the lever M. The gas valve is thus held,
up and retained in its closed position until the speed is sufficiently reduced. The
catch S has a projecting lip formed on it and is so arranged that it can only be
released on the lever M being raised a little. The catch S is therefore set
sufficiently low so that even when engaging the blade T the lever will always be
raised a little at the extremity of the upward stroke of the main admission valve,
this rise being sufficient to release the catch S if the speed has slowed down and
the governors are disposed to drop. Thus the lever M is prevented from being
released at an improper moment which might result in the gas valve being opened
when say the charging piston has made half its stroke and which would result in
upsetting the proper proportions between the gas and the air in the charge. The
governors are driven by means of a belt from the pulley U (Fig. 4) on the crank
shaft to the pulley U¹ (Fig. 9) on the governor shaft. V is an adjustable stop by
means of which the amount of opening allowed to the gas valve can be regulated.
In Figs. 12 to 19 inclusive I shew also on a larger scale the arrangement I prefer
to adopt for igniting the charge of mixed gas and air in the working cylinder.
This consists essentially of a slide valve the construction of which, so far as regards
the means for igniting the charge, is well understood by those who are acquainted
with gas engines. In Fig. 12 is shewn a partial section of the working cylinder
with its water jacket casing and a plan of the firing valve and cover. Fig. 13 is a
front view of this and Fig. 14 a section of the same. Fig. 15 shews the inside face.
of the slide valve cover. Fig. 16 is a front view of the jaws in which the slide
valve works shewing also the false face against which the valve works and which
is held to the face on the cylinder or rather the water jacket side by the cheese-
headed screws. Fig. 17 shews the inside face of the slide valve of which Fig. 18. is
the outside face Fig. 19 being a sectional plan. In these Figs. A. A. A. is the
slide valve, one face of which works against the false face or loose plate B. B. the
other working against the inside of the cover C. C. The firing pocket in this
valve is shewn at D, and the master light at E. The pocket D is fed with gas by
the pipe F, the gas passing along the groove G at the inside of the cover and
through the small passage H where it comes in contact with the air which is
passing up through this pocket in the direction of the arrows under the influence
of the draught caused by the chimney I. It is here lighted by the master light E
and, the valve, passing on beyond the ports in the cover, this burning air and gas
is for a moment bottled up, as it were in the pocket D until the port K at the

page_text: inside face of the valve opens to the port L in the loose plate. The port L being:
open to the hole through the hollow plug Z (Fig. 3) which passes throgh, the
water-jacket and cylinder castings, is in direct communication with the interior of
the working cylinder, thus when the flame which is bottled up in the pocket D is
exposed to the port L, it immediately fires the charge. The pocket D will now be
charged with old products of combustion of some considerable pressure which
would make a noise if they were allowed to blow straight out through the oponing
in the cover of the valve. I therefore cause the pocket D to first pass over the
series of openings O, O, (Fig. 15) in the cover and these holes open into the pipe P.
which may be carried into the exhaust box. T T are adjusting screws by means of:
which the position of the cover may be set to a nicety. The clamps, springs, and.
studs by which the valve cover is held to its face are shewn at Q. R. S (Fig. 12).
The slide valve receives its motion from the eccentric V on the crank shaft (Fig. 4)
to which is connected the eccentric rod V Fig. 12 & 13. It very often happens,.
however, that old products of combustion from previous charges will lodge in the
hollow plug and in the port L in the loose plate B preventing the flame being
communicated to the charge in the working cylinder-In order to insure regular
firing it will therefore be necessary to clear these ports of any old products of
combustion thus lodging in them. The best way to accomplish this is to inject.
through them some of the fresh charge of gas and air from the charging cylinder.
For this purpose these ports are momentarily put into communication with the
charging cylinder by means of the small port M on the inside face of the valve,
which at the proper moment (that is to say when the charging piston is making.
its inward stroke and before any compression takes place in the working cylinder)
opens a communication between the hole N and port L in the loose plate and the
hole N being in direct communication with the pipe W. W. Figs. 1. 2. 3. 12 & 16
leading from the charging cylinder, this port and the plug are scavenged or cleared.
of old products of combustion, new charge of mixed gas and air being substituted
therefor which will readily fire on contact with the flame in the pocket D. In fact tho
whole charge of mixed gas and air might be fed into the working cylinder in this
manner, the ports and the pipe being made of sufficient area for the purpose. In
this case both the upper and lower sets of ports in the working cylinder would be
used as exhaust ports being put into communication with the exhaust box.
This:
will be readily understood by a reference to Figs. 20 and 21 which are respectively.
a longitudinal section and a sectional plan of an engine so arranged. The charge:
is conveyed from the charging cylinder A along the pipe and passage Band through
the port C in the valve whence it passes through the port D into the working
cylinder. The upper and lower exhaust ports communicate with the exhaust box
by means of the annular spaces EE, E E and the branches F, F. The dotted
lines G, G shew the position of the faces of the pistons when at the end of their
inward stroke and the dotted lines H, H' shew the position they occupy when at
the end of their outward stroke, the pistons themselves being omitted for the sake
of clearness. The firing port which is here large enough to act also as an admission
port is shewn in dotted lines at I. The working cylinder and the water-jacket.
casing should in this case be cast together. In Fig. 22 is shewn a longitudinal
section and in Fig. 23 a partial plan of an engine in which the charge instead of
being driven in at the lower part of the working cylinder (as already described
and shewn in Figs. 1. 2. 3 and 4.) is driven in through the ports at the upper part
of the cylinder, the ports at the lower end of the cylinder being exhaust ports.
In this case motion is imparted to the piston of the charging cylinder by its being
connected to the connecting rod which is actuated by the upper piston. A is the
charging cylinder delivering its charge through the passage B into the upper
portion of the working cylinder. The lower ports communicate by means of the .
branch C with the exhaust box D. The admission valve is fixed at E (Fig. 23).
In this engine the shaft would run in the contrary direction to that already
described its course being indicated by the arrow. The cranks in this arrangement.
.

page_text: are brought close together as shewn in Fig. 23 the middle bearing being dispensed
with.
The apparatus for lubricating is shewn in Figs. 24 to 28 inclusive. Fig. 24 is
a section. Fig. 25 a front view. Fig. 26 a plan. A revolving barrel A is divided
into a number of recesses by the projecting flanges or blades B, B B and small
chains C hang loosely over the revolving barrel and dip into the oil in the
lubricator. These chains have motion imparted to them by the revolving barrel
in the direction of the arrow and as they come up charged with oil a portion of
this oil gets on to the flanges. The scraper or doctor D (shewn separate in plan
and section in Figs. 27 & 28) is fixed so that as the barrel revolves it will take the
oil off the edges of the flanges or blades. This doctor is divided into separate
cups or compartments which correspond with the flanges and also correspond and
are in communication with, holes e. e. drilled in the solid part of the lubricator
casting. To these holes are attached pipes f. by which the oil, deposited in the
cups of the doctor, can be conveyed to any part of the engine requiring regular
lubrication. Two or more chains can be arranged to feed one pipe according to
the amount of lubrication required. The barrel is rotated by means of worm
gear as shewn in Figs. 25 and 26. This lubricator (which may be driven by a belt
from the pulley U on the governor shaft (Fig. 9) should be fixed at some elevated
position on the engine as shewn at Z¹ (Fig. 3) so that the oil may flow down to
the highest part requiring lubrication.
Figs. 29 and 30 are partial sections of the upper and lower part of the working
cylinder shewing the means by which the oil is caused to deposit itself equally
round the two pistons. The oil being fed into the annular space a. a. Fig. 29
gradually rises until it reaches the small holes b. b. b. which should all be drilled
at the same level. It then flows equally through these holes into the narrow
annular groove c. c. cut in the inside of the cylinder and is here deposited uniformly
round the piston. In Fig. 30 which is the lower end of the working cylinder the
principle adopted is the same with the addition that the oil is first deposited in
the cup & whence it flows to the annular groove e. e. by passages which simply
consist of holes drilled through the metal and which have their outer ends plugged.
The oil may of course be supplied to the groove a. a. (Fig. 29) or the cup d (Fig. 30)
as required in regular quantities by the lubricator already described. The top
brasses of the link in the bottom piston should be "metalined" as they are in an
awkward position to lubricate with oil. The cycle of this engine may be described
as follows. Taking the course of the crank D¹. Fig. 1. 2. & 4 and referring to
diagram Fig. 31. Firing of the charge takes place when the crank is at 1 and it
is exerting its influence on the cranks while it is passing from 1 to 2. At the
point 2 the exhaust ports open and the contents of the cylinder fall to atmospheric
pressure. At 3 the admission ports open and the new charge is entering the
working cylinder while the crank is passing from the point to 4 where the
admission ports close, the exhaust ports closing a moment afterwards at 5.
Compression now commences and goes on till the point 1 is again reached when
the new charge is fired and the operation proceeds as before.
One advantage of this form of engine is that, without unduly increasing the
length of the engine, a proportionately long stroke may be obtained and thus more
power can be extracted from a given amount of gas than would be possible with
an engine of a short stroke and the noise caused by the exhaust is diminished.
For a cylinder of five inches diameter I give the engine a total stroke of eighteen
inches, that is to say there would be two four and a half inch cranks on the crank shaft.
And for this size of engine I use twelve three-sixteenth holes in the gas valve with
Manchester gas at about five tenths pressure. In the main admission valve there
may be twelve three-eighths or half inch holes. The passage O, (Figs. 3 & 6)
leading from the charging cylinder to the working cylinder should have a sectional
area of about two square inches the collective area of the inlet ports N being
about the same or a little more and the exhaust ports should be twice this. The
volume swept through by the charging piston should be about equal to that swept

page_text: through by one of the working pistons. The pistons should be furnished with
cast iron split rings turned true to the bore of the cylinder after being split.
Another advantage possessed by my engine is that the force of the expansion of
the ignited gases in the working cylinder is balanced being received on the crank
shaft at the same time in opposite directions and equal amounts. It will be seen
that the principal moving parts of the engine also balance each other.
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
A gas engine having a working cylinder in which work two pistons which act
on cranks set opposite to cach other on a crank shaft, the charge of mixed gas
and air being supplied to the working cylinder by means of a separate charging
cylinder.