IMPROVEMENTS IN GAS ENGINES
Year: 1879

page_text: LETTERS PATENT to William Foulis, of Glasgow, in the County of Lanark,
North Britain, Civil Engineer, for the Invention of "IMPROVEMENTS IN GAS
ENGINES."
Sealed the 30th April 1880, and dated the 21st November 1879.
PROVISIONAL SPECIFICATION left by the said William Foulis at the Office
of the Commissioners of Patents on the 21st November 1879.
WILLIAM FOULIS, of Glasgow, in the County of Lanark, North Britain, Civil
Engineer. "IMPROVEMENTS IN GAS ENGINES."
This Invention, which relates to improvements in gas engines, is in part a further
developement of that arrangement or construction of such engines for which Letters
Patent were granted to the said William Foulis, dated 28th day of November,
A.D. 1878, and numbered 4843.
According to the first part of the present improvements flat, conical, or spherical
lift valves or piston valves are substituted for the cylindrical rotating valves
included in the Specification of the aforesaid Letters Patent.
The air and gas are drawn or forced either into the cylinder or into a mixing
reservoir during the up-stroke of the pistons through a measuring apparatus, so
arranged as to discharge the gas and air in proper proportions. This measuring
apparatus may consist of a pair of meters geared together so as to ensure one
meter constantly discharging the proper quantity of air, and the other the proper
quantity of gas. In place of meters a pump or pumps proportioned to discharge at
each stroke the proper proportions of air and gas may be adopted, or a mechanical
equivalent of meters or pumps so arranged may be substituted, the object being to
ensure a constant mixture of air and gas, which on explosion in the cylinder will
develop the maximum heat and pressure. A lift valve or valves may also be used
for this purpose, in which case the valve which opens the air passage may be
furnished with a second valve, which at the same time and to a proportionate
extent opens the gas way.

page_text: The compressed mixture of air and gas is admitted to the combustion chambers
of the cylinders by a piston valve arranged to admit it for the acting stroke. The
exhaust valve is or may be a ball valve seated upon an asbestos or other seating.
Piston valves may be however used for admitting gas and air both during the
inactive stroke and for the exhaust. The valves are or may be driven from
eccentrics on the driving shaft of the engine, which may be conveniently effected
as follows:-The rods or straps are coupled to levers, each on one end of tubular
shafts, that is to say, three shafts situated concentrically or inside one another, and
two of which are tubes, these said concentric shafts being horizontal and situated
immediately beneath or above the valve casings. By means of this concentric and
tubular arrangement of these shafts each piston valve is operated independently of
and without interfering with the operation of the other valves.
The improvements consist further in forming the combustion chamber so as to
project from the upper part of the cylinders into the interior thereof. The upper
side of the piston is or may be protected by fire clay or other refractory material,
and has in it a recess to receive the aforesaid combustion chamber on the
up stroke.
According to another improvement the upper part of the cylinder itself forms a
non-conducting combustion chamber, being lined at that part with fire clay,
asbestos, or other refractory non-conducting material, the piston top being covered
with the same.
Instead of diminishing the capacity of the space under the piston between the
cylinders and piston rods by the use of thick piston rods or trunks, as described in
the aforesaid Specification, cylinders of less capacity fitted with pistons for com-
pressing the air may be substituted, in which case the cylinders of the engine may
be made double acting, and less than three such cylinders may be employed.
The engines may be constructed so as to be reversible. This is effected by
having double eccentrics working a second set of valves, which can be brought
into operation whilst the others are thrown out of action, these valves opening the
ports in the necessary order to admit the compressed air and gases to the cylinders
at the time necessary to give the reverse action; or the same valves may be used
and the cylinders provided with a double set of pipes, so that admission from the
underside of the pistons of either of two cylinders may be opened to the upper
side of the other. The eccentrics may have the necessary alteration in their
position given to them by any of the known means for effecting that object.