IMPROVEMENTS IN GAS ENGINES WITH TWO PISTONS
Year: 1878

page_text: LETTERS PATENT to The Hannoversche Maschinenbau-Actien-Gesellschaft,
vormals Georg Egestorff, at Linden, near Hannover, Prussia, for the Invention
of "IMPROVEMENTS IN GAS ENGINES WITH TWO PISTONS." A communication
from Wilhelm Wittig and Wilhelm Hees, of Hannover, Prussia.
Sealed the 15th November 1878, and dated the 17th May 1878.
PROVISIONAL SPECIFICATION left by the said The Hannoversche Maschi-
nenbau-Actien-Gesellschaft at the Office of the Commissioners of Patents on
the 17th May 1878.
THE HANNOVERSCHE MASCHINENBAU-ACTIEN GESELLSCHAFT, vormals Georg
"IMPROVEMENTS IN GAS ENGINES
Egestorff, at Linden, near Hannover, Prussia.
WITH TWO PISTONS." A communication from Wilhelm Wittig and Wilhelm Hees,
of Hannover, Prussia.
This Invention relates to a gas engine in which the motive power is produced by
causing a mixture of gas and air to explode after the same has been compressed to
a certain extent, such compression enhancing the power developed by a given
quantity of gas, and consequently increasing the effect of the engine.
The arrangement of engine which my correspondents have designed for utilizing
the power thus produced consists of a cylinder open at both ends, in which two
pistons move in contrary directions. From the upper piston of this cylinder, which
is by preference placed vertically, motion is transmitted to two parallel cranks of a
fly wheel shaft by means of a piston rod, a cross head, and two connecting rods.
The lower piston is directly jointed to a single connecting rod acting on a third
crank, which is arranged on the same shaft between the said two cranks but
opposite to them. The pistons therefore recede from and approach each other
simultaneously, but when they are at the shortest distance from each other they
leave a space for the compressed gas and air between them. This space communi-
cates by one channel or port with the slide valve, which admits air and gas, and by
another channel with an exhaust valve.

page_text: .
The pistons at the first stroke outward, i.e., when receding from each other, aspire
gas and air, the admission valve being in such a position as to open suitable com-
munications for this purpose. The aspired gas mixture having thereupon been
compressed by the first inward stroke is caused to be ignited and to explode imme-
diately after the pistons have commenced to recede from each other the second
time. This ignition is effected in the following manner:-In the said admission
slide valve there is a passage or chamber, which by a perforation in the slide and a
small channel in the cylinder may communicate with the space containing the com-
pressed gas mixture. This communication is oponed a few moments before tho
explosion is to take place; at the same time the said chamber in the slide valve is
open on the outside towards a gas flame constantly burning. When the valve is
in this position the pressure in the cylinder forces a jet of gas and air through the
said perforation into the said chamber. Within the latter a tube is arranged by
which this jet is directed in such a manner as to cause a draught through the
chamber towards an eduction channel in the slide face of cylinder, the said gas
flame being thereby sucked into the chamber of the valve ignites the gas mixture
of the same.
The valve now rising further transports the burning gas mixture
upward until communication is established between the chamber and the inlet port
of cylinder, whereupon explosion takes place, driving the pistons outward and
developing power. At the subsequent in stroke the combustion gases are driven
out through the exhaust valve.
The admission valve and the exhaust valve are actuated by a crank or eccentric
and a cam disk respectively, which are each keyed on a shaft driven at half the
number of rotations of the crank shaft.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said The Hannoversche Maschinenbau-Action-Gesellschaft in the Great
Seal Patent Office on the 16th November 1878.
THE HANNOVERSCHE MASCHINENBAU-ACTIEN-GESELLSCHAFT, vormals George
Egestorff, at Lindon, near Hannover, Prussia. "IMPROVEMENTS IN GAS ENGINES
WITH TWO PISTONS." A communication from Wilhelm Wittig and Wilhelm Hees,
both of Hannover, in the Kingdom of Prussia.
This Invention relates to a gas engine in which the motive power is produced by
causing a mixture of gas and air to explode after the same has been compressed to
a certain extent, such compression enhancing the power developed by a given
quantity of gas, and consequently increasing the effect of the engine.
On the accompanying two Sheets of Drawings the arrangement of engine which
our correspondents have designed for utilizing the power thus produced is represented,
Figs. 1 and 2 being vertical sections at right angles to each other; Fig. 3, a plan of
bed plate and shaft; Fig. 4, a top view; Figs. 5-9 show detail views of slide valve.
A is a cylinder, open at both ends, and placed, by proference, vertically. Within
the same two pistons a and b move in contrary directions. From the upper piston
motion is transmitted to two parallel cranks c, c, of a fly wheel shaft f by means of
a piston road a', a cross head p', and two connecting rods d, d. The lower piston b
is directly jointed to a single connecting rod g acting on a third crank c', which is
arranged on the same shaft f between the two cranks c, c, but opposite to them.
The pistons a and b therefore recede from and approach each other simultaneously,
but when they are at the shortest distance from each other they leave a space for
the compressed air and gas between them, see Fig. 1. This space communicates by
the channel or port h with the slide valve n which admits air and gas, and by the
channel with the exhaust valve u.
The pistons at the first stroke outward, i.e., when receding from each other, aspiro
gas and air, the admission slide valve n being in such a position that its channel i,
Fig. 7, opens communication between port h on the one hand, and the gas-supply
channel e and air aperture ; on the other. The aspired gas mixture having there-
upon been compressed by the first inward stroke is caused to be ignited and to
explode immediately after the pistons have commenced to recede from each other
the second time. This ignition is effected in the following manner :-In the slido
valve n there is a passage or chamber le into which a tube 7 projects from the side,
as shown by Figs. 6 and 7. At a certain point of stroke of the slide, i.c., a few
moments before the explosion is to take place, a perforation in the slide corre-
sponding with the core of the tuber enters into communication with the channel p,
Figs. 6 and 9, leading into the cylinder. At the same time the chamber k in the
slide valve is open on the outside towards a gas flame_fed from gas pipe z, and
constantly burning in the slot t of the valve cover, see Fig. 8. When the valve n
is in this position the pressure in the cylinder forces a jet of gas and air through
channel P and tuber into the chamber k of the slide. By the described tube rand
cone 8 slightly projecting into the conical bore of the former this jet is directed in
such a manner as to cause a draught through the chamber k towards an eduction
channel 9 in the slide face of cylinder. The said gas flame being thereby sucked
into the chamber k ignites the gas mixture in the same.
The valve n now rising
further transports the burning gas mixture upward until communication is
established between the chainberk and the inlet port of cylinder, whereupon
explosion takes place, driving the pistons outward and developing power. At the
subsequent in stroke the combustion gases pass out through the exhaust valve u.
The slide valve n is actuated by a crank n' (for which an eccentric may be sub-
stituted), and the exhaust valve by a cam discu³. The crank is keyed on a shaft n³,
aud the cam disc on a shaft u², which are both driven at half the number of
rotations of the crank shaft f, as may be seen from Figs. 3 and 4.

page_text: The speed of the engine is regulated by a governor w, Fig. 2, acting on a throttle
valve in the gas-supply pipe.
The advantages to be attained by this arrangement of gas engine are the
following:
Firstly. The explosive power developed by the gas mixture is greater than other-
wise on account of its being compressed before the ignition.
Secondly. The necessary gas for the intermediate flame which ignites the com-
pressed gas mixture being supplied from the cylinder no special gas jet is required
for this purpose.
Thirdly. The cylinder being open at both ends its inside walls are cooled by the
atmospheric air, consequently less water is required for cooling than in the case of
closed cylinders.
Having thus described the nature and object of this Invention, as communicated
to us by our correspondents, and the manner in which it is to be or may be carried
out in practice, we wish it to be understood that we do not claim the two pistons
moving in a single cylinder in general, but we claim as new and essential features
of the Invention,―
1. In combination with the cylinder A and the two pistons a and b the slide
valve n, having the channel i for admitting gas from channel e and air from
aperture, and actuated by crank n', revolving at half the number of revolutions
of shaft, substantially as and for the purposo specified.
2. In combination with the cylinder A and the two pistons a and b the slide
valve n, provided with chamber and tube r, moreover the channels p and q, and
finally the gas pipe z, as and for the purpose stated.
In witness whereof, we, the said Hannoversche Maschinenbau-Actien-Gesell-
schaft, vormals George Egestorff, have hereunto set our hand and seal, this
Twenty-fourth day of October, in the year of our Lord One thousand eight
L
ad savante night
HANNOVERSCHE MASCHINENBAU-ACTIEN-
GESELLSCHAFT, VORMALS G. EGESTORFF,
Linden, vor Hannover.
(L.S.)