IMPROVEMENTS IN GAS ENGINES
Year: 1885

page_text: I, JAMES ATKINSON, of 3 Nassington Road, Hampstead, London, N.W. Engineer
do hereby declare the nature of my invention for IMPROVEMENTS IN GAS ENGINES
to be as follows:-
The improvements consist of an arrangement of parts forming a gas engine,
which, in one cylinder, and during one revolution only of the main shaft, draws in
the combustible mixture, compresses it, ignites it, developes its explosive force, and
expels it.
I employ a horizontal cylinder open at both ends, fixed near the base of the
engine, and fitted with two pistons, each of these pistons is connected by a rod to
the lower end of a beam, (one beam to each piston), the beams work on centres fixed
in the main framing of the engine, above the open mouths of the cylinder, and are
extended above these centres, where their upper ends are connected by short con-
necting rods to one crank pin, in a crank disc, fixed on the main shaft, which works
between the upper ends of the beams; the connecting rods are made very short, say
about one and one-half times the radius of the crank pin; the angularity of the
rods and beams cause the pistons to have a differential motion as regards each
other; they are quite close together when at one end of the cylinder, (hereinafter
called the preparing end), having driven the results of the last working charge into
the exhaust pipe; as the crank revolves the piston at the preparing end moves
very slowly towards the other end, (hereinafter called the working end), the other
piston, (hereinafter called the working end piston), travels very rapidly, so that the
pistons leave a considerable space between them, into which combustible mixture is
drawn; the preparing end piston now begins to travel faster than the working end
piston, until they arrive at the working end of the cylinder, when the pistons aro
closer together and have compressed the combustible mixture to a suitable pressure,
when it is ignited by the working end piston passing the entrance to an igniting
tube similar to that described by me in previous Letters Patents; just previously to,
or at the time of ignition, the pistons commence to swiftly increase the space
between them, the working end piston remaining almost stationary whilst the pre-
paring end piston is rapidly passing from the working end to the preparing end,
thus giving a very quick expansion; at the termination of this expansion, the
working end piston commences to overtake the preparing end piston, driving out
the products of combustion through the exhaust port. I prefer to make the space

page_text: between the pistons into which the ignited gases are expanded greater than the
space into which the combustible mixture is drawn, thus carrying the expansion
to a further extent than is usual in Gas Engines as hitherto constructed; the
relative proportions of these spaces and the capacities between the pistons, when at
the extremes of their strokes, are obtained by suitably proportioning the levers,
rods, and working centres; the short connecting rods between the crank pin and
upper ends of the beams being chiefly the cause of the great difference in the
relative speeds of the pistons, and the level of the main shaft as regards the upper
ends of the beams, principally determines the relative spaces for drawing in the
combustible mixture and for expansion.
The admission port and the exhaust port are at the preparing end of the cylinder
and the admission and exhaust are chiefly controlled by the preparing end piston
covering or uncovering them, they have self acting valves to prevent the passage
of air, gas, or the exhaust passing in the wrong direction; also the exhaust may be
provided with a self acting valve admitting air to the exhaust pipe, and preventing
the momentum of the exhaust drawing uniguited gas and air into the exhaust pipe,
but it might be allowed to draw a little air only through the small space between
the pistons.
The ignition may be caused by any other means than by the ignition tube
previously mentioned.
The cylinder may be placed vertically or inclined, and more than one cylinder
may be connected so as to form a combined engine.
The working gear may be differently arranged to suit different circumstances, as
for instance the beams may vibrate from one end, with the cylinder placed between
the shaft and these beam centres, or the shaft between the cylinder and the beam
centres. The essential point being to get the peculiar differential motion of the
two pistons.
No working gear is necessary as all the valves may be self acting; it may how-
ever be desirable to control the gas supply so that no gas may pass into the engine
excepting at the desired time, also for the purpose of governing the engine.
The engine will run in either direction, as started, but if required to work both
ways the spaces for drawing in the combustible mixture and for expansion should
be made equal or about equal.

page_text: I, JAMES ATKINSON, Engineer of 3 Nassington Road, Hampstead, in the county
of Middlesex 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:-
The improvements consist of an arrangement of parts forming a gas engine,
which, in one cylinder, and during one revolution only of the main shaft draws in
the combustible mixture, compresses it, ignites it, developes its expansive force, and
expels it.
An arrangement of a gas engine containing this invention is shown in the
accompanying sheets of drawings, in which like figures apply to like parts, and in
which Fig. 1. Sheet I is a front elevation of the engine, Fig. 2. Sheet I is a sectional
elevation, Fig. 3 Sheet II is a plan, and Figs. 4, 5, 6 and 7 Sheet II are
diagramatical illustrations for the purpose of more fully explaining its action.
is
I employ a horizontal cylinder 1 open at both ends, fixed near the base of the
engine, and fitted with two pistons 2 and 3, piston 2 being hereinafter called the
pumping piston, and piston 3 the working piston; these pistons 2 and 3 are con-
nected by links to the lower ends of the vibrating beams or levers 4 and 5, working
on centres fixed in the main framing of the engine; 4 is the pumping beam,
the working beam. These beams are connected at their upper ends by short
connecting rods 6 and 7, to one crank pin 8, fixed in a disc 9, which is keyed on
the main shaft 10, this shaft lying between the upper ends of the beams 4 and 5 ;
the connecting rods 6 and 7 are made very short, say about one and one-half times
the radius of the crank pin 8, the angularity of the rods 6 and 7 and beams 4 and 5,
cause the pistons 2 and 3 to have a special differential motion as regards each
other. The pistons 2 and 3 are quite close together when at one end of the
cylinder (hereinafter called the preparing end) as shown in Fig. 4 Sheet II, having
driven the products of the last working charge into the exhaust pipe through the
exhaust port 11, and self-acting exhaust valve 12. As the crank revolves the
working piston 3 moves very slowly towards the other end, (hereinafter called
the working end) and the pumping piston 2 travels more rapidly in the same
direction, until the position shown in Fig. 5 is attained; it will be seen that at this
time there is a considerable space between the pistons 2 and 3, which has been
filled with an explosive mixture of gas and air through the suction passage 13, and
self-acting suction valve 14; it will also be observed that the working piston 3 is
at or about this time cutting off all connection between the space enclosed between
the two pistons and the passages 11 and 13, and by the continued motions of the
pistons 2 and 3 towards the working end of the cylinder 1, the charge is enclosed
entirely between the pistons and the cylindrical walls of the cylinder 1, which
enclose the combustible charge by practically the smallest area of containing
surfaces; in this connection it will be understood that as gas engines transmit an
enorinous amount of heat through the walls of the cylinder, this is a matter of vital
importance respecting economical working; also that from this time until the

page_text: whole of the work is done, which is at the position shown at Fig. 7 Sheet II, the
working fluid is cut off entirely from all joints and passages. As the crank pin
revolves the position shown at Fig. 6 Sheet II is reached, the pistons during this
time continuing to travel at differential speeds towards the working end of the
cylinder 1, these differential speeds cause the pistons 2 and 3 to again approach
each other, compressing the combustible charge until it attains any desired pressure
above the atmosphere (45 lbs. has been found to be a suitable pressure), at the time
of this greatest pressure the piston 2 passes the mouth of the igniting tube 15, this
tube is similar to the igniting tube described and illustrated by mne in previous
letters patent, in this arrangement the tube, which may consist of wrought iron or
any other suitable material, is open at its lower end to a small hole or passage
drilled through the wall of the cylinder, it is closed at its upper end, and is kept
red hot near the cylinder so that when the piston 2 passes the small hole, a small
portion of the combustible charge rushes into it, is instantly ignited, Bashes back
into the cylinder and fires the charge contained therein. During the passage of the
crank pin 8 from the position shown at Fig. 6 Sheet 11 to the position shown at
Fig. 7, the pistons have very rapidly increased the space between them, during
the earlier part of this movement the piston 2 remains almost stationary, in fact, by
suitably proportioning the lovers and centres, chiefly by raising the upper centre of
the pumping beam 4 a little above the centre of the main shaft 10 (as shown in
the diagrams) the pumping piston 2 may be caused to have a momentarily con-
tinued backward motion, after the working piston 3 has started on its working
stroke, this ensures certainty of ignition, conduces to the rapid expansion of the
exploded charge, and assists to give economical working. At or about the position
shown at Fig. 7 the working piston 3 uncovers the exhaust passage 11, letting out
thereby, and by the self-acting exhaust valve 12, the consumed gases, which are
completely expelled by the pumping piston 2 as it travels into the position shown
in Fig. 4 Shect II, from which time the cycle of operations recommences, and is
repeated at each revolution of the crank shaft.
I prefer to make the space between the pistons 2 and 3, into which the ignited
gases are expanded (as shown at Fig. 7) greater than the space into which the
combustible mixture is drawn (as shown at Fig. 5) thus carrying the expansion to
a further extent than is usual in gas engines as hitherto constructed, which commonly
open the exhaust whilst there is a pressure in the cylinder of say 40 lbs, which is
thereby wasted; but by carrying the expansion to say 10 lbs. above the atmosphere
a considerable gain in economy is obtained.
The relative proportions of these spaces and the capacities between the pistons 2
and 3, when at the extremes of their strokes, are obtained by suitably proportioning
the beans 4 and 5, the connecting rods 6 and 7; and the positions of the various
working centres; the short connecting rods 6 and 7 being chiefly the cause of the
great difference in the relative speeds of the pistons, and the level of the main
shaft 10 as regards the upper ends of the beams 4 and 5 principally determines the
relative spaces for drawing in the combustible mixture, and for expansion, as
shown in Figs. 5 and 7 Sheet II.
The admission port 13, and the exhaust port 11, are at the preparing end of
the cylinder 1, and the admission and exhaust are chiefly controlled by the working
piston 3 covering or uncovering them. These passages have self-acting valves 14
and 12 which prevent the passage of air, gas, or the exhaust, passing in the wrong
direction. I wish it to be understood that I do not make any claim as regards the
construction of these valves, all that is necessary being to provide any suitable
form of self-acting valves for these purposes. In the arrangement shown in Figs. 1
and 2 Sheet I and Fig. 3 Sheet II a governor 16 is shown, which controls the
admission of the gas by the following arrangements:-the governor 16, which may
be any type of centrifugal governor, acts on an eccentric rod 17, which is operated
up and down at a suitable time by a spherical eccentric sheave 18, the governor 16
decides whether or not (and in some instances if it does to what extent) the
eccentric rod 17 operates on one end of the double lever 19 on its downward

page_text: movement; if it does, it lifts up the other end of the lever 19, which lifts up a
small gas valve contained in the valve box 20, thereby admitting gas to the engine,
which is drawn in and mised with the entering air. I also wish it to be known
that I do not claim in any way this method of governing gas engines.
The exhaust pipe beyond the exhaust valve 12 may be provided with a self-
acting valve admitting air to the exhaust pipe, and preventing the momentum of
the exhaust drawing unignited gas and air into the exhaust pipe, but the momentum
of the exhaust might be allowed to draw a little air only through the small space
between the pistons 2 and 3, when at the position shown at Fig. 4 Sheet II, for
the purpose of cooling the ends of the pistons and passages, also sweeping out the
last trace of residuum from the cylinder; when used in this manner the governor
valve admitting gas is not allowed to be opened by the eccentric and connections
until this action has ceased.
4
It will be seen that the method of ignition is very certain and it can be very
accurately timed, a matter of very great importance in an engine which does the
work in so rapid a manner; other methods of ignition may be used if desired.
The cylinder may be placed vertically or inclined, and more than one cylinder
may be connected so as to form a combined engine.
The working gear may be differently arranged to suit different circumstances;
as for instance, the beams may vibrate from one end, with the cylinder placed
between the shaft and the beam centres; or the shaft between the cylinder and the
beam centres. The essential point being to get in a direct and definite manner by
means of beams and connecting rods operated by one crank pin, the peculiar
differential motions of the two pistons 2 and 3, which enables a compression gas
engine to perform in one revolution the whole cycle necessary to its action; also
to enable the working fluid to be controlled entirely by the motions of the two
pistons 2 and 3, so that the whole of the necessary operations can be performed
without requiring any working gear to operate any valves. It may however be
desirable, and it is shown in the accompanying drawings how, to control the gas
supply, so that no gas is allowed to pass into the engine excepting at the desired
time, and also for the purpose of governing the engine. It will be seen that in the
arrangement shown and described, the gas admission valve is the only valve that
is controlled or operated by any working gear. I may however use the automatic
governing arrangement described by me in Letters Patent 16,404/84 by means of
which the engine may be made perfectly automatic in every respect.
The engine may be made to run in either direction as started; if required
however to work both ways the spaces for drawing in the combustible mixture and
for expansion, as shown in Figs. 5 and 7 Sheet II, should be equal or about equal.
It is known, and 'has been proved by experiments, that the amount of useful
work done by a specific quantity of gas varies enormously with the speed at which
the work is done; in this invention I have constructed an engine which will do
the work in less time than has hitherto been accomplished: it is obvious from an
inspection of Figs. 6 and 7 Sheet II that the work is done in about a quarter of a
revolution of the crank shaft 10, also from an inspection of Figs. 5 and 7 Sheet II,
that the expansion is carried to nearly double the original volume, thus work is
done after ignition at about four times the rate at which it is done in engines
which expand to the original volume only in half a revolution, as is usual in other
gas engines running at the same number of revolutions per minute. This source
of economy combined with the increased expansion, has an enormous influence
upon the economy to be attained by means of this invention, which also has the
advantage of doing away with, the necessity of requiring any slide valve, or valve
gear, of any description whatever.
The middle portion 21 of the cylinder 1 shown in the accompanying drawings is
water jacketed; owing to the increased rate at which the work is done and to a
smaller extent to the increased expansion very much less heat than is usual in
other engines passes through the walls of the cylinder, also a much smaller volume
of cooling water is required.

page_text: The arrangement of engine shown in the accompanying drawings is suitable for
engines of small and medium powers, for larger engines it would doubtlessly be.
advisable to place the cylinder, beams and crank shaft between two side frames, 'so.
that all strains may be central and sustained on each side.
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
1st The general construction and arrangements of parts forming a gas engine
substantially as described and illustrated.
2nd In a compression gas engine the arrangement of two pistons working with
a differential motion obtained directly from one crank pin, by means of rods and
beams, and of such a character as to enable the whole necessary cycle of operations
to be performed between them, in one cylinder, and in one revolution of the crank
shaft, substantially as described and illustrated.
3rd In a compression gas engine the arrangement of two pistons working with a
differential motion obtained directly from one crank pin, by means of rods & beams,
and of such a character as to enable the whole necessary cycle of operations to be
performed between them, in one cylinder, and in one revolution of the crank shaft,
and in which the admission of gas and air, and the exhaust of the waste products,
are through self-acting valves, also the timing of these operations, together with
the timing of the ignition, being governed by the passage of the pistons, substan-
tially as described and illustrated.
4th In a compression gas engine having. two pistons working with differential
motions in one cylinder, so arranging their actions as to produce a greater volume
between them before exhausting, than when the admission is completed, substan-
tially as described and illustrated.
5th In a compression gas engine the arrangement for igniting, consisting of the
igniting tube covered and uncovered by the piston, so as accuratly to time the
ignition, and ensure its certainty, as described and illustrated.
Dated this 20th day of November 1009.
Witnessed by
G. E. PRIDDLE,
2
16, Shirlock Road, London, N.W.
JAMES ATKINSON.