Improvements in Gas Engines.
Year: 1895

page_text: Date of Application, 15th Jan., 1895-Accepted, 16th Feb., 1895
COMPLETE SPECIFICATION.
Improvements in Gas Engines.
I, GEORGE CROYDON MARKS of 18 Southampton Buildings London, W.C.
Consulting Engineer and Patent Agent (a communication from abroad by Feodor
Hirsch of Steinway, Queens County, New York, United States of America,
Mechanical 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 :-
My improvements relate to gas engines generally but are especially applicable
to marine gas engines, and others where economy of space and concentration of
power is desirable.
In my English applications No. 13,333, of July 10th, 1894, and No. 24089 of
December 11th, 1894, I show opposed power cylinders and pistons connected
indirectly with a common crank shaft, the firing of a single central charge by a
single ignitor driving the pistons apart. The object of my present invention is to
apply the same principle of a single central charge and ignition to opposed power
cylinders in which the pistons, under the force of explosion, approach each other,-
in other words to apply the expansive force of the gases at the outer ends of the
cylinders instead of at the inner ends as in my said prior applications.
By this means I am enabled to retain all the advantages attained in my prior
construction, such as the perfect balancing of the parts, avoidance of jar, strain, &c.,
and at the same time simplify and cheapen the construction as a whole. Thus I
am enabled to dispense with the links, rock levers, and pitmen required in
connecting the outwardly-propelled pistons to the common crank shaft, since I connect
my inwardly impelled pistons directly to the crank pins on said crank shaft by
means of vibratory piston rods; and the cranks and connections with the pistons are
all enclosed and isolated centrally within the engine.
An important feature of my invention consists in utilizing the passage leading
from the central firing chamber to the inlet ports at the outer ends of the power
cylinders as compression chambers, whereby, although the force of the explosion
from the single charge of gas spreads instantly to the opposite ends of the motor,
the gases act upon the pistons mainly by expansion and the usual jar and concussion
arising from the explosion of the gases is avoided. As a result I not only obtain a
more durable and smooth-running motor, but am also euabled to reduce the length
of the power cylinders since the compression space heretofore indispensable therein
is done away with, and the pistons can travel right up to the inlet ports.
Another feature of my present invention is that of dispensing with the inter-
mediate cam shaft and gearing for operating the exhaust valve &c., since I now
arrange the exhaust. cam, and governor &c., directly upon the central power or
crank shaft. In this connection my invention includes the speciał construction and
arrangement of mechanism for connecting and disconnecting the cams with the
exhaust valve as hereinafter set forth.
I am enabled to construct my engine so low and compact in form, when compared
with others of a given power, that when used as a marine engine it can be
conveniently placed below the water line of the vessel, and a natural automatic
circulation of cooling liquid through its water jacket can be maintained, thereby
dispensing with the use of pumps or other means for effecting a forced circulation

page_text: through the water jacket, as has heretofore been necessary. The engine is so small
and low of structure than effective motor can readily be placed below the floor or
deck of an ordinary launch in such manner that it will be practically out of sight
as well as out of the way.
In the accompanying drawings,
Figure 1, is a front elevation of my improved motor;
Figure 2, is a plan of the same;
Figure 3, is a rear elevation the fly wheel being omitted;
Figure 4, is a horizontal section, partly in elevation;
Figure 5, a central vertical section taken upon plane of line u, ", Figure 4, the
cranks being shown in elevation ;
Figure 6, is an end elevation;
Figure 7, a central vertical section, partly in elevation;
Figure 8, a vertical section upon plane of line v, v, Figure 5;
Figure 9, a vertical section upon plane of line w, w, Figure 5;
Figure 10, a plan of the under side of the motor;
Figure 11, is a horizontal section upon plane of line,, Figure 3, taken from
the under side of the motor;
Figure 12, is an elevation of the under side of a portion of one of the cylinders,
showing the inlet and water ports ;
Figure 13, is a view of the upper side of the outer end of a conduit ;
Figure 14, is a rear view of the engine;
Figure 15, is a view of the inner side of the fly wheel;
Figure 16, is a transverse section upon plane of line y, y, Figure 3;
Figure 17, is an elevation of the inner side of one of the cylinder heads
removed;
Figure 18, is an enlarged view showing the exhaust cam lever &c.;
Figure 19, a similar view at right angles to Figure 18;
Figure 20, a detail of the governor cam lever;
Figure 21, a detail of the cams &c., taken from the side opposite to that shown
in Figure 18;
Figure 22, is an elevation of the exhaust cam lever detached ;
Figure 23, is a sectional elevation through the fly wheel, governor and exhaust
cam;
Figure 24, is a diagram illustrating the condition of the gas charge through the
successive revolutions of the crank shaft ;
Figure 25, is a view illustrating the use of my engine as a motor for vessels, its
position below the water line &c.
The opposed power cylinders A, A', are secured at their inner ends to a central
trunk or box B, in which the cranks c, c', of the shaft C, work. This box B, is
made in two parts b,, with the bearings 62, for the shaft C.
Below the trunk B, is the valve chest D, connected by the conduits d, d', with
the outer ends of the cylinders A, A'.
The trunk pistons E, E', are connected by swinging piston rods e, e¹, directly to
the cranks c, c', upon the power shaft C: and the stroke is such that they travel
outward as far as the ports a, a', which open into the cylinders A, A', close to the
heads a², a³, of the latter, so that the outer faces of the pistons E, E', are separated
from the inner surfaces of the heads a³, as, but slightly at the end of the outward
stroke, there being no special provision of compression spaces within the cylinders
as in other forms of gas engines. Hence the length of the cylinders A, A, may
be considerably reduced,-the compression of the gases taking place mainly in the
passages d², d³, which connect the ports a, a', with the central chamber d', into
which the supply valve F, and exhaust valve G, open, said central chamber d',
also affording space for the compression of the gases during the outward stroke of
the pistons E, E¹.
This compression of the charge takes place during the last half of the first
revolution. By reference to Figure 24, in which the circles, represent two

page_text: succeeding revolutions of the power shaft, it will be seen that during the first half
of the first revolution the charge of gas is drawn in, compressed during the second
half, fired during the first half of the second revolution, and discharged during the
second half, and so on continuously.
This is effected through the medium of the cam H, on the shaft C, said cam
operating the discharge valve G, through the medium of the rock lever I. The
cam H, is formed with two peripheral grooves h, h¹, which converge and cross
each other, as it were, at 2, so that the traveller i, traverses first one and then
the other of the grooves h, h¹, being shunted from one to the other by the side
walls of the grooves themselves in the well known manner of the endless screw
worm and traveller.
When the pivoted traveller i, enters and traverses the groove h', it rocks the
lever I, upon its fulcrum i, causing the lower end 2, of said lever I, to press the
valve stem g, inward against the resistance of the spring g'. When the traveller i,
enters the inner groove h, the lever is rocked in the opposite direction, allowing
the spring g', to close the valve G.
The lower end 2, of the rock lever I, is pivotally connected to the said lever 1,
as illustrated clearly in Figures 18, 19 and 22. The section 2, is formed with a
shoulder, which is held normally against a stop i, on the lever 1, by a spring .
It is also provided with a bearing roller, which rests against the face of the lower
arm j, of the bell crank lever J. The upper arm, of the latter rests against the
governor or relief cam K, which is feathered to the shaft C. When the eccentric
portion, of the cam K, rocks the upper arm mj, of the bell crank lever J, back-
ward, the lower arm j, presses the lower section 2, of the rock lever I, backward
against the resistance of the spring, as indicated in dotted lines in Figure 19,
thereby removing and releasing the valve stem g, from contact with the lever I,
when the spring g', will hold the valve G, closed until the lower end i, of the
lever I, is again restored to position.
The relief cam K, is so timed with relation to the discharge cam N, that its
eccentric or throw k¹, coincides with the portion of the groove h', which effects the
opening of the discharge valve G; and the cam K, would thus prevent the discharge
of the products of combustion continuously were it not that it is held and controlled
by the governor L, which normally holds the cam K, in such position on the
shaft C, that its eccentric portion or throw k', is not in alignment with the upper
arm of the bell crank lever J.
The governor L, is substantially the same construction as that shown and
described in my last application hereinbefore referred to excepting that in the
present case it is attached directly to the fly wheel M. Its inner arms 1, 1, engage
with notches in the sleeve k², extending backward from the cam K. When the
speed of the engine exceeds a prescribed degree the weighted arms ",", recede
against the resistance of the spring P, rocking the arms upon the pivots 13, 13,
and causing them to draw back the cam K, until its thrust kl, is brought into
alignment with the upper arm j, of the bell-crank lever J. Should this happen
while the thrust section k³, is on the side of the arm j, the latter yields laterally
until the cam has rotated sufficiently to allow it to spring back into position to
receive the thrust k¹. This I accomplish by making the arm j, of comparatively
thin elastic material as described in my last application which shows a similar
spring arm and cam.
From the foregoing it will be seen that the cam K, acts to close the discharge
valve G, only when the speed of the engine throws the governor L, into action, so
that the action of the discharge cam is not interfered with when the engine is
running within the limits of speed.
The charge is drawn in from the supply pipe O, through the puppet valve F, by
the suction created by the inward stroke of the pistons. It is exploded by an
ignitor P, of any desired or suitable form.
When the discharge valve G, is opened the products of combustion are forced
out through the exhaust pipe Q.

page_text: The engine cylinders A, A', heads a², a³, valve chest D, and conduits d, d', are
Where the
formed with water jackets which communicate with each other.
engine is used for marine purposes it is preferably placed below the water line, as
indicated in Figure 25, and the lower part of the water jacket system connected by
a supply pipe or pipes R, with the exterior of the hull, while the upper part of the
water jacket system is connected by a discharge pipe or pipes S, with the exterior
at a higher level. Thus arranged a natural circulation of the cooling liquid may
be maintained, the water as it becomes heated rising and being replaced by cold
water entering through the inlet R, and the flow being regulated by valves s, s, it
the discharge pipes S, S.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, what I claim is
First. In a gas engine, the combination of two opposed power cylinders having
closed outer ends; two trunk pistons in said cylinders connected directly by
swinging piston rods to cranks upon a common central shaft; said crank shaft;
a common valve chest; two conduits; one connecting the said common valve chest
with the outer end of one cylinder, and the other conduit connecting said common
valve chamber with the outer end of the other cylinder, said conduits acting as
both supply and exhaust passages for the said cylinders respectively; supply and
discharge valves opening into said common valve chest and an ignitor
communicating with said common valve chest; substantially in the manner and for
the purpose described.
Second. In a gas engine, the combination of two opposed power cylinders having
closed outer ends; a central trunk connecting the inner ends of said cylinders;
two trunk pistons in said cylinders connected directly by swinging piston rods to
cranks upon a common central shaft; said crank shaft; a common valve chest ;
two conduits; one connecting the said common valve chest with the outer end of
the one cylinder, and the other conduit connecting said common valve chamber
with the outer end of the other cylinder, said conduits acting as both supply and
exhaust passages for the said cylinders respectively; supply and discharge valves
opening into said common valve chest; and an ignitor communicating with said
common valve chest, substantially in the manner and for the purpose described.
Third. In a gas engine, the combination of two opposed power cylinders having
closed outer ends, two trunk pistons in said power cylinders connected directly by
swinging piston rods to cranks upon a common shaft, said crank shaft, a cam upon
said crank shaft, a rock lever connecting said cam with the discharge valve, and
said discharge valve opening into a passage communicating with the outer ends of
both cylinders, substantially in the manner and for the purpose described.
Fourth. In a gas engine, the combination of two opposed cylinders having closed
outer ends, two trunk pistons in said cylinders connected directly by swinging
piston rods to cranks upon a common shaft, said crank shaft, a fly wheel on said
crank shaft, a centrifugal governor on said Hy wheel, a cam on said crank shaft
controlled by said governor, mechanism operated by said cam to release the
discharge valve and said discharge valve opening into a passage communicating
with the outer ends of both cylinders in the manner and for the purpose
described.
Fifth. In a gas engine, the combination of two opposed cylinders having closed
outer ends, two trunk pistons in said cylinders connected directly by swinging
piston rods to cranks upon a common shaft, said crank shaft, a centrifugal
governor on said crank shaft, a cam on said crank shaft controlled by said governor,
a bell crank operated by said cam to trip the mechanism for opening the dis-
charge valve, and said discharge valve opening into a passage. communicating
with the outer ends of both cylinders, substantially in the manner and for the
purpose described.
Sixth. In a gas engine, substantially such as described, the combination of the
cam H, on the crank shaft, the rocking lever I, formed with the pivoted lower

page_text: end, the valve G, rod g, and the bell crank lever J, and the centrifugal
governor L, the whole arranged and operating substantially in the manner and for
the purpose described.
Dated this 15th day of January 1895.
MARKS & CLERK,
18, Southampton Buildings, London, W.C., Agents.