Improvements in Gas Engines.
Year: 1893

page_text: COMPLETE SPECIFICATION.
Improvements in Gas Engines.
I CYRA BISSELL WATTLES of 540 Jefferson Avenue, Elizabeth Union Co. N.J.
in the United States of America do hereby declare the nature of this invention and
in what manner the same is to be performed to be particularly described and ascer-
tained in and by the following statement :-
This invention relates to that class of single acting gas engines in which an
impulse is secured for each revolution of the crank shaft.
The invention consists primarily in forming the engine with two concentric
cylinders adjacent to but independent of each other and fitted with pistons adapted to
reciprocate simultaneously therein, combined with separate inlet and exhaust valves
for each cylinder operated by a common valve mechanism.
Heretofore it has been proposed to provide a gas engine with communicating
cylinders and pistons arranged as above described; but by permitting the expansion
of a single charge in both cylinders, only a single set of valves has been required,
while the motor so constructed has been able to furnish only a single impulse for
each alternate turn of the crank shaft. By my invention I am enabled to secure
double the power of the ordinary gas engine giving the same intensity of impulse,
while the motion imparted to the crank shaft is much more uniform than in other
constructions in which the same aggregate piston area has been provided; and the
heavier parts of the machine do not require to be duplicated, as in ordinary duplex
engines, the power of the engine being thus greatly increased without materially
altering the floor space it requires.
In the annexed drawing,
Fig. 1 is a plan of the engine in horizontal section on the center line of the
cylinders; Fig. 2 is a front elevation, Fig. 3 a side elevation, and Fig. 4 a rear
elevation of the same;
Fig. 5 is a side view and Fig. 6 a front view of the differential piston;
Fig. 7 is a transverse section of the cylinder and one set of supply valves, on the
center line of the latter; Fig. 8 is a similar section, on the center line of the corre-
sponding exhaust valve; and
Fig. 9 is a longitudinal vertical section through the centers of all the valves and
the valve mechanism.
Figs. 5 to 9 inclusive are drawn upon double the scale of the preceding
figures.
a and b are the cylinders, supported upon the bed A of the engine, the latter
cylinder being of double the area of the former so that the difference in their areas
may equal the area of the smaller cylinder to insure an impulse of equal intensity
in both cylinders upon the operative faces e¹ and c, respectively, of the differential
piston c. The piston is connected with the crank d by the single connecting rod e
pivoted upon the pin e¹.
The crank shaft D carries at one end the fly wheel F and at the other end the
pulley P for transmitting the power developed in the cylinders. Both cylinders are
enclosed in a water jacket j in the usual manner.
All the valves employed are of the poppet type and self-closing, the air supply
valve being opened by the suction of the piston only. The valve chests are
provided with removable caps f' directly over the air and exhaust valves h and I,
respectively, to make the latter accessible; and the gas chamber u, surmounted by
the gas valve I, is made removable to afford access to the latter.
As the set of valves for one cylinder is a counterpart of that for the other

page_text: cylinder, the valves for the larger cylinder only are shown and described specifically
herein.
Each valve chest is divided into a mixing chamber M at the top connected with
its respective cylinder by a port M', an air chamber N closed by the air valve h
connected with the space under the engine bed by a channel N¹ and enclosing the
gas chamber 21, and the exhaust chamber communicating with the atmosphere
through the channel O' in the bed A. The air and exhaust valves are provided
with wings to guide them to their seats, and the gas valves are provided with
stems g' guided by suitable bearings and projected through the lower side of the
gas chamber to engage the valve mechanism.
The valve operating mechanism comprises the cam shaft connected to the crank
shaft to rotate at one-half the speed of the latter by means of the spiral gears m
suitably proportioned. Upon the shaft are fixed the cams n and o for actuating,
respectively, the gas and exhaust valves. A shifter rod is mounted parallel and
adjacent to the cam shaft and carries the levers or tappets (Figs. 3, 7 & 9) to
engage the cam n and lower end of the stem of the gas valve g. The shifter rod
is coupled to or formed continuous with the spindle of a centrifugal governor s
connected with the cam shaft by gears s; whereby the divergence of the governor
balls forces the shifter rod backward from the same and disengages the levers or
tappets from contact with the gas valve stems, thus preventing the cam from
actuating the gas valve to supply the explosive mixture to the cylinders until the
speed of the engine is reduced to the normal rate.
2:
The stem 13 of the exhaust valve I is provided upon its lower end with a collar
notched in its under side to receive the cam o which bears upon a transverse pin
across the notch, in order to press the valve stem upward at the required intervals
to open the valve. The air valve requires no positive mechanism for opening it, as
the suction of the piston in the cylinder from which the spent gases have been
expelled is sufficient to admit the required amount of air through such valve.
Both the gas and exhaust valves are provided with springs for seating them
positively, but the air valve is closed merely by gravity.
The gas and exhaust valves for each cylinder are actuated at the required instant
in the cycle of the engine by setting their respective cams at about 90° apart, that
of the former in advance of the latter; and the corresponding valves of each
cylinder at the same point in alternate strokes of the piston by setting their
respective cams at 180° apart upon the cam shaft.
The ignition is effected by the penetration of the explosive mixture from the
mixing chamber through the passage into the heated tubes t¹ (Fig. 9) which are
enclosed with a suitable heating burner within a casing t, as indicated in Figs. 2, 3
and 4.
In the position of the piston indicated in Fig. 1, the explosion may be considered
to have just occurred in the cylinder a and the heated products of combustion are
thus exerting an impulse upon the contiguous face c¹ of the piston; while the other
face of the piston, by its simultaneous movement, is drawing a mixture of air and
gas through their respective valves into the cylinder b. The return stroke of the
piston compresses the explosive mixture just drawn into the cylinder b, the supply
valves having closed at the end of the outward stroke; and the spent products of
combustion are simultaneously driven from the cylinder a through its exhaust valve
which was previously opened by its cam at the end of the outward stroke of the
piston. At the end of the return stroke, the compressed mixture in the cylinder b
is exploded, from which point the second half of the cycle is duplicated in the other
cylinders from those mentioned above.
From the foregoing description of the operation of the engine, it will be observed
that the details of construction shown and described herein are not material parts
of the invention, and that one or both of the cylinders may be made movable
instead of both pistons without departing from the principle of the invention, the
essential features of which are,
First, forming the two adjacent concentric cylinders without inter-communication

page_text: to operate wholly independent of each other, and providing separate supply and
exhaust valves for each cylinder; and, second, connecting the governor with the
shifter rod which carries the tappets for engaging the cams and valve stems, to
communicate a longitudinal motion thereto, whereby the disengagement of the
tappets with the valve stems may be effected by any abnormal increase in the speed
of the engine; and therefore,
Having now particularly described and ascertained the nature of my said inven-
tion and the nanner in which the same is to be performed, I declare that what I
claim herein is,―
1. A gas engine comprising two independent or non-communicating cylinders
arranged adjacent to and concentric with each other and provided with pistons
adapted to reciprocate simultaneously, and separate inlet and exhaust valves for
each cylinder controlled by a valve-operating mechanism driven from the crank
shaft.
2. The mechanism for actuating the gas valves, in the engine described in
Claim 1, which consists in a cam shaft having cams fixed thereon adjacent to the
valve stems, and a shifter rod connected with the centrifugal governor and carrying
tappet arms each normally engaging one of the cams and the end of the adjacent
valve stem simultaneously, but adapted to be shifted out of engagement with the
valve stem when the shifter rod is actuated by the governor.
1000
E. P. ALEXANDER & SON, Fels. Chartered Inst. Patent Agents,
19, Southampton Buildings, Chancery Lane, London, W.C.,
For the Applicant.