IMPROVEMENTS IN AND CONNECTED WITH GAS ENGINES
Year: 1879

page_text: PROVISIONAL SPECIFICATION left by William Donald at the Office of
the Commissioners of Patents on the 11th February 1879.
WILLIAM DONALD, Junior, of Paisley, in the County of Renfrew, North Britain,
Engineer. "IMPROVEMENTS IN AND CONNECTED WITH GAS ENGINES."
This said Invention has reference to special improvements in the construction and
combination of the parts of motive-power explosive gas engines, and appliances or
apparatus connected therewith; whereby such engines are more efficiently made
double-acting in their pistons and cylinders, and more regular or steady and
efficient in their motion, with less liability to derangement and wear and tear of
the parts, and greater economy in giving out much more power with less con-
sumption of explosive or coal gas than such gas engines as heretofore constructed.
And the nature and novelty of the Invention consist, first, in making the power
cylinder close at both ends, with double acting reciprocating piston, and connecting-
rod coupled to its piston rod and crosshead at one end, and at the other to the
crank or crank-pin of the crank-shaft of the engine; all by fitting the cylinder
with a duplex valve or valve plate and ports with back covers or casings at each
end of the cylinder at one side, for the admission of the gas and air by pipes,
preferably, through different sets of ports from pressure receivers, all as will herein-
after be explained; and further with a duplex ported valve or valve plate and
cover at each end of the cylinder, on the opposite side, for the ignition and explosion
of the gas and air by the one set of ports, and the exhaust or escape of the waste
gases or products of combustion by the other ports; all in an improved manner,
and actuated by an arrangement of connecting valve rod and cam or tappet, or
equivalent eccentric mechanism for each set of inlet and exhaust valves respectively,
on the opposite sides of the cylinder, and actuated preferably by regulating cams on
the crank shaft direct, these cams revolving within cau boxes mounted over the
cams and crank shaft in guides, and connected to the front ends of the valve rods
near the crank shaft. The inlet valves are preferred to have separate casings or
chambers, and sets of ports for the admission of the coal gas and the air respectively,
having the ports formed, preferably, in one or more transverse rows of small bored
holes through the valve and face plate of the cylinder at or near each end, and
angled towards each other, so as to make the current of gas and air passing through
them, when the valve opened cross each other, and so thoroughly mix as they

page_text: And
enter the cylinder from the separate close cases or chambers at the back of each
inlet duplex ported valve, and the explosive or coal gas and the air are led into
these valve chests at the back of the valves, under considerable pressure, through
pipes from separate close gas and air pressure receivers immersed in or surrounded
with circulating cold water receivers, or air or other refrigerating chambers, to keep
these and the compressed gas and air forced into them cold, which would otherwise
become hot by the quick compression of the force pumps, or other equivalent, used
for compressing the gas or air into these pressure receivers or accumulators.
for the like cooling purpose the cylinder of the engine would be formed with an
-annular-outer-water circulating_jacket_all_round, the inner working barrel, which,
in this improved double acting arrangement, might be formed by a steel or other
"liner," turned to fit the bored ends of the outer barrel or case formed with the
annular water jacket between the end valve chambers and close end flanges, with
covers fitted close to the ends of the "liner" and which might also be fitted with
water circulating jackets outside. These accumulating pressure supply chambers
or vessels might be loaded to the pressuré desired, and fitted to rise and fall, or have
movable pistons fitted to work in them, in either case jointed fluid pressure tight
by stuffing-boxes or other joints, formed with a column or pressure of water equal
to or greater than the pressure within. The improved cam of the exhaust and
igniting valves, has a triple projecting or tappet acting surface, and is so formed
and set on the crank in relation to the piston of the crank pin and piston, that
when the latter reaches the end of each stroke, its longest or major tappet closes
the exhaust and igniting port just before the piston reaches one end for a new
stroke, and opens the exhaust port at the other end; while just as this has been
done, the improved gas and air admission valve is actuated by its revolving cam
on the crank shaft, preferably, under this arrangement, by two cain or tappet
projections on the periphery of an otherwise nearly concentric cam, also so formed
and set in relation to the crank pin and piston that the advanced major or longest
stroke projection of the cam comes into action on the end of its cam box, so as to
open the valve at the end of the cylinder the piston has reached, to admit the
proper quantity of gas and air required, and fill the space between that end and
the space through which the piston has moved forward while the cam was opening
the valve to its full extent, and also while the minor or short cam tappet came into
action and shut the valve just, as the pistons traverse has thus measured the
quantity of gas and air required for its stroke; when the lowest or second cam
surface of the exhaust valves comes round and opens the igniting port or opening
at or near the back of the piston in this slightly forward position, still leaving the
exhaust port at this end closed, and the one at the other end open; while the
explosion of the compressed gas takes place, the next or mean cam closes the
igniting port, the gas expanding throughout the full length of the stroke with far
greater force than when explosive air and gas are not so forced in under pressure
to fill the said space, measured for them by the motion of the crank and piston in
relation to the action of the valves and cams, as stated, and which can be adjusted
to suit the degree of expansion desired; and just as the piston is nearing this end
of its acting stroke the third tappet comes into action and closes the exhaust and
igniting ports at the other end of the cylinder ready for the equivalent action of
the valves and cams to admit the gas and air and give the explosion, all as
described in reference to the other end, all intermittently and sequentially as the
crank comes round to its reverse end stroke. and the cams in relation thereto.
Other equivalent arrangements of cams, tappets, or eccentrics might be employed
to effect the said improved admission and enclosing or measuring of the compressed
air and gas, and produce the double action and circular motion of the crank with-
out knocking. The said inlet gas and air valves, and exhaust and igniting slide
valves at each end of the cylinder may be connected on their respective sides by a
sliding guide rod, connected by a lateral pin to the near end of their respective
actuating cam rods, which might also work through slide guides to carry the
weight of the rods and steady them in their action.

page_text: To regulate the admission of the proper proportions of gas and air to form the
best explosive mixture, either the size or number of the inlet ports or holes in the
valves or the pressures on the receivers may be made proportionate to effect this;
and to regulate the maximum pressure of the exploded and expanded gases desired,
and prevent danger or risk of breakage from an excess of explosive pressure of the
gas and air within the cylinder, each end of the cylinder would be fitted with a
spring or other valve, regulated by a lever and screw with index, or otherwise, to
the pressure desired to be sustained within the cylinder. The whole engine may
be made of any ordinary vertical or horizontal type, preferably with a crosshead
at the piston-rod and connecting-rod joint, and fitted with slide guides, all so as to
work the pistons of the gas and air pumps laid parallel thereto, and secured to the
sole plate of the engine between the crank and crosshead, having the rods of the
pump buckets directly attached to the crossbead. These pumps might be made
either double or single acting, or drawing and forcing pumps with the valves fitted
immediately at the end of the barrels, and the opening to the inlet and discharge
chambers close up to where the bucket worked, so as to leave no space for
containing undischarged or compressed air or gas to heat the pumps and waste
power. When hinged or flap valves are used they might be made in two parts,
working on angled faces of the bucket, and closing seats of the inlet and discharge
valve on each side of the bucket rod. The drawing and forcing valve chambers of
these pumps would be fitted with inlet and discharge pipes, the former led from
the gas supply pipe or chamber and the air supply, while the latter would be led
to their respective close loaded pressure chambers or accumulators herein before
described. The gas and air pumps are provided to give the required velocity and
pressure to the gas and air into their receivers, and a regular or steady pressure of
these within the cylinder, to give the sharpest and most effective expansion and
force of the exploded gases. The exhaust ports in this engine are preferred to be
kept open to very near the end of the stroke to allow of a free exhaust, and prevent
all chance of firing the charge through the piston should it get slightly slack or
leaky.