IMPROVEMENTS IN GAS ENGINES
Year: 1881

page_text: PROVISIONAL SPECIFICATION left by Robert Ord at the Office of the
Commissioners of Patents on the 24th February 1881.
ROBERT ORD, of Devizes, in the County of Wilts, Engineer. "IMPROVEMENTS
IN GAS ENGINES."
My Invention, has for its object rendering more certain the firing of the charge
of gas and air in the cylinder of gas engines in which the charge of gas and air is
not compressed.
According to one mode of carrying out my Invention in order to effect this
object, I make the slide valve (which is a rectangular, triangular, or other
conveniently shaped box, having ports or openings in its sides) travels vertically,
the downward motion being caused by a cam on the crank shaft, and the upward
motion caused by a spring or cam, as may be most convenient. The cylinder has
a straight port into it from the face, on which the slide valve works; from this port
to the bottom of the cylinder a piece is cut from inside the cylinder in order that
the charge when the piston is at the bottom of the cylinder may pass down and
under the piston; lower down the face a second port is made, but not quite
through to the cylinder; this port is bent upwards and joins the port first
mentioned. When the valve is in its lowest position air and gas pass through it
into the lower port of the cylinder upwards and through the first mentioned port;
at a certain part of the stroke of the piston the valve is suddenly forced upwards
by the action of the spring or cam; this motion closes the ports in the back plate,
and brings the firing chamber of the slide valve opposite the upper port or cylinder,
and ignites the charge of gas and air contained therein. While the valve is being
depressed by the cam, a pump forces pure air into the lighting chamber in the
valve, thus permitting the ignition of the gas which was at that time being
admitted to this chamber through a small port in the back plate.
According to another modification, where the valve travels vertically, driven as
before described, I put one or more straight ports (according to size of engine) from
the face on which the valve works to the cylinder, and form the valve in such a
manner that its upward motion closes the port or ports in the cylinder at the same
time that it closes those admitting air and gas through the ports in the back
plate, and opens wider a port in the valve to a cavity in the back plate. This
cavity conducts to the lighting chamber in the valve, and the latter to the cylinder,
so that the remains of the charge in the interior of the valve must pass through
the lighting chamber of the valve (now full of flame), and thus ignite the charge
n the cylinder.
In this arrangement also I employ a pump, either a long stroke driven directly
or indirectly by the piston, or a short stroke driven by an eccentric or cam or

page_text: similar arrangement, for insuring the lighting of the gas contained in the lighting
chamber of the slide valve by forcing pure air into the said chamber.
Another part of the Invention relates to an arrangement for moving the slide
valve horizontally; this is effected by a similar cam to that before mentioned
working on one end of a lever, and moving the slide valve by the other end in one
direction, and a cam or spring in the other direction. In this arrangement the
port or ports, according to size of engine, are placed with their length in the
direction of the length of the cylinder; the ports in the slide valve are so disposed
that when it is moved in one direction by the action of the cam and lever, air and gas
are admitted to the cylinder through the slide valve, also gas to the lighting chamber
in the slide valve, a pump being employed as before mentioned for forcing in fresh
air. The proper part of stroke being arrived at by the piston, the spring or cam
suddenly forces the slide valve into such a position that the only entrance into
the cylinder for the part of charge remaining in the interior of the slide valve is
through the cavity in the back plate and lighting chamber of valve, in its passage
through which the charge is. ignited.
In order to limit the travel of the slide valve in the direction in which it is
forced by the spring in either of the arrangements mentioned, I sometimes employ
a combination of two or more links or joints, which may be extended to the
distance the valves must travel, or two levers arranged to press against a spring in
such a manner that one constantly loses as the other gains power, or a flat spring
pressing against the side of the valve, or lever, or rod, or it may strike against a
spring or buffer of any suitable material.
In order to prevent the possibility of injury to the valve gearing through the
engine being turned in the wrong direction, the cam for driving the slide valve is
loose upon the shaft, and is driven by a catch in a sleeve on the shaft being made
to engage with a notch in the side of the cam by a spring. The engine may by
reversing the cam and altering the position of the eccentric which controls the
exhaust valve be made to run in either direction. In all these arrangements
a separate slide valve worked by an eccentric is employed to control the exhaust
of the spent gas and air. The slide valve worked by the cam and spring motion
in all cases admits to the cylinder air and gas and ignites the charge.
The back plate mentioned in the foregoing arrangement consists of a box or
chamber through which water can freely flow, the said box having passages
through which respectively gas, air, and flame may enter the slide valve as before
described.
Another part of my Invention relates to the construction and arrangement of
the valves of the gas engine, and it consists in the use of three valves so arranged
and timed in their action relatively to each other that one valve shall ignite the
charge only, another shall allow the gas and air forming the charge to enter the
cylinder, whilst the third valve exhausts after the explosion. These valves are
operated by cams or eccentrics as desired.
In lieu of employing a pump for forcing fresh air into the lighting chamber in
either of the arrangements hereinbefore described, I may use a jet derived from the
products of the combustion taken from the exhaust, or a gas jet obtained from any
other source in the shape of an ejector or injector, connected with the back plate
in such manner that the foul air shall be drawn out of the lighting chamber and
other passages in the valve and back plate, and fresh air admitted so as to ensure
the ignition of the gas in the lighting chamber.
These arrangements are applicable to either vertical and horizontal double or
single acting gas engines.