IMPROVEMENTS IN GAS ENGINES
Year: 1884

page_text: I ABRAHAM DAVY, Junior of 2 Elmore Road, Moor Oaks, Sheffield, in the
County of York, Engineer, do hereby declare the nature of the said invention for
"IMPROVEMENTS IN GAS ENGINES," to be as follows:-
My Invention relates to improvements in that class of motive power engines in
which the power is obtained by the explosion or rapid combustion of coal gas and
air or other combustible elastic fluid and air.
The object of the improvement is to economise the heat generated by such
combustion and which in gas motors generally is to a large extent wasted by being
absorbed by the water circulating through the cooling jacket whilst the heat
remaining in the products of combustion after they have driven out the piston, is
allowed to pass away directly through the exhaust pipe into the atmosphere.
According to my Invention I effect economy of heat by the use of a steam
generator in combination with the motor, the water in the generator circulating
around the explosion chamber and absorbing a certain amount of the heat con-
sequent upon an explosion or combustion of gases and forming steam which is
collected in the generator.. A portion of the products of combustion (after an
explosion and after the piston has been driven to the top of its stroke) is also
passed through tubes into the generator, heating the water on its way and the
heat contained in these products of combustion is utilised in assisting evaporation
of the water by direct contact in the generator in which they intimately mix with
steam already formed and collected therein. The mixture of steain and products
of combustion thus obtained is used for driving the piston in an opposite direction
to that effected by the explosion of air and gas.
Instead of the mixture of steam and products of combustion being used for
driving back the piston in the working cylinder, it may be used in a cylinder of
larger area in combination with the working cylinder.
In operation the explosive mixture of air and gas or other elastic fluid and air,
is forced by a pump through the delivery valve and a pipe from which it is
admitted through a valve into the explosion chamber. The admission valve is
then closed and an ignition of the explosive mixture is made through the slide
whilst the piston is at the bottom of its stroke, said slide being worked by a lever
and eccentric, which latter also works a valve for admitting the products of
combustion to the generator as well as the exhaust valve and the feed pump of the
generator.

page_text: Upon an ignition of the explosive mixture the piston is driven upwards by the
expansion of the gases and upon the piston nearing the top of its stroke, the valve
for admitting the products of combustion to the generator is opened by means of a
lever and the products of combustion pass through said valve and a check valve
along a passage and through the tubes into the generator; at the same moment the
slide valve in a valve chest at the top end of the working cylinder, which is in
communication with the upper part of the generator, worked by an eccentric,
opens the steam port and admits a charge from the generator at the upper side of
the piston. When the piston has travelled the greater portion of its downward
stroke, the valve for admitting the products, of combustion to the generator closes
and retains in the explosion chamber some of the products of combustion and the
slide valve having in the meantime opened a communication between the top side
of the piston and the atmosphere, the piston is driven upwards by the expansion
of the products of combustion retained in the explosion chamber when the valve
was closed. The piston having again arrived nearly at the top of its stroke the
exhaust valve of the explosion chamber is opened by a lever worked by an
eccentric and the remaining products of combustion are allowed to pass away into
the atmosphere, and the slide valve again uncovering the steam port another charge
is admitted to the top side of the piston, from the generator.
When the piston is nearly at the bottom of its stroke, the exhaust valve closes
and the valve for admitting air and gas to the explosion chamber is opened by
means of a lever and cam.
In order that the explosive mixture should not be much reduced in pressure-by
expanding into the explosion chamber, the ram of the air and gas pump does not
terminate its downward stroke until after the piston has arrived at the bottom of
its stroke, thus compensating somewhat for the reduction of pressure in the
explosive mixture arising from its having to expand into the explosion chamber.
The shaft for working the valves makes one revolution to two of the crank
shaft so that an explosion occurs at every second revolution of the crank shaft
when the engine is working at full power.
The governors. are of the ordinary pendulous type and are made to act on the
delivery valve of the air and gas pump in such a manner that when the governors
are in their highest position they cause a lever to hold open said valve which
allows the air and gas to flow back into the pump barrel on an upward stroke
instead of the pump taking in a fresh supply through the suction and gas valves.
When the governors are in their lower position, the lever disengages with the valve
and the pump is then again in action.
Either tappet valves or slide valves may be used for admitting air and gas from
the pump and for the ignition of same and also for adınitting the products of
combustion into the generator, and for exhausting the same from the working
cylinder the said valves being worked by eccentrics as previously described.
Dated this 10th day of September 1884

page_text: COMPLETE SPECIFICATION.
I ABRAHAM DAVY, Junior, of 2 Elmore Road Moor Oaks, Sheffield in the
County of York, Engineer do hereby declare the nature of my invention for
"IMPROVEMENTS IN GAS ENGINES" and in what manner the same is to be
performed, to be particularly described and ascertained in and by the following
statement: -
My Invention relates to improvements in that class of motive power engines in
which the power is obtained by the explosion or rapid combustion of coal gas (or
other combustible elastic fluid) and air.
The object of the improvement is to economise the heat generated by such com-
bustion and which in gas motors generally is to a large extent wasted. According
to my Invention I effect economy of heat by the use in combination with the motor
of a steam generator the water in which circulates around the explosion chamber
and absorbs part of the heat developed by the explosion and forms steam whilst a
portion of the products of combustion is exhausted into the generator and
intimately mixed with steam already formed and collected therein heating the
water on its way by surface conduction and also by direct contact in the generator,
the mixture of steam and products of combustion thus obtained being used for
working the piston on its return stroke, or for working a piston in a cylinder of
larger area the two pistons either being on the same rod, or each driving the crank
shaft by its own connecting rod and crank as ordinarily arranged in compound
steam engines.
Reference is to be had to the accompanying drawings forming part of this
Specification wherein figure 1 is a section of an engine of the vertical type, figure 2
a plan, figure 3 a plan showing the valve levers figure 4 an end elevation and
figure 5 a transverse section of the valves between the explosion chamber and the
steam generator. Figure 6 is a cross section of the explosion chamber showing
slide valves in lieu of tappet valves. The same letters of reference indicate the
same parts in all the figures.
A is the working cylinder, B the explosion chamber thereof, C is the.
steam generator D the air and gas pump E the valve for admitting the explosive
mixture from pump D to the explosion chamber B the valve being loaded to a
suitable pressure and worked by a cam V on a counter shaft and through a
lever Y. F is the valve for admitting a portion of the products of combustion.
from the explosion chamber into the steam generator. G is the exhaust valve to
the atmosphere. H is the ignition slide and I the slide valve controlling the
admission of the mixture of steam and products of combustion from the generator
to the upper end of the working cylinder.
In operation the explosive mixture of gas (or other elastic fluid) and air is forced
by the pump D through the delivery valve K and the pipe L which is of sufficient.
capacity to form a small reservoir and from which it is admitted through the
valve E into the explosion chamber B. The admission valve E is then closed and
the explosive mixture is ignited through the slide H whilst the piston M is at the
bottom of the stroke said slide being worked by the lever N on a rock shaft Z

page_text: worked by an eccentric O on the counter shaft a, which driven from the main
shaft of the engine by an intermediate shaft c, mitre gear b, b and bevel gear d, d,
having a ratio of 2 to 1 so that the counter shaft a makes one revolution to two of
the main shaft. The said rock shaft Z also works the valve F by means of lever Q
for admitting the products of combustion to the steam generator, the exhaust
valve G by means of lever X, and the feed pump of the generator by means of
lever P.
T
By the expansion consequent on the ignition of the explosive mixture the
piston M is driven upwards and upon the piston nearing the top of its stroke the
valve F is opened and the products of combustion pass through said valve F and
through a check valve R along the passage S and through the rising tubes T, into
the steam space generator; at the same moment the slide valve I worked by an
eccentric U and whose chest is in communication by pipe W with the steam space
of the generator admits a mixture of steam and products of combustion from the
generator to the upper side of the piston. When the piston M has travelled the
greater portion of its downward stroke, the valve F closes and the piston M
cushions against some of the products of combustion thus retained in the explosion
chamber B and the slide valve I having in the meantime opened a communication
between the top side of the piston and the atmosphere, the piston is driven
upwards again by the expansion of the said products of combustion. The piston
having again arrived nearly at the top of its stroke the exhaust valve G is opened
and the remaining products of combustion are exhausted into the atmosphere the
slide valve I at the same time again admitting steam &c from the generator to the
top side of the piston.
When the piston is nearly at the bottom of its stroke, the exhaust valve Ɑ is
closed and the valve E is again opened to admit a fresh charge of explosive mixture
to chamber B.
In order that the explosive mixture should not be much reduced in pressure by
expanding into the explosion chamber the ram of the pump D is timed so as not to
terminate its downward stroke until after the piston M has arrived at the bottom
of its stroke.
The counter shaft a makes one revolution to two of the main shaft so that an
explosion occurs not oftener than at every second revolution of the main shaft when
the engine is working at full power.
The Governors are of the ordinary pendulous type and are made to act on the
delivery valve K of the air and gas pump D in such a manner that when the
governors are in their highest position they cause the lever h to hold open said
valve which allows the air and gas to flow back into the pump barrel on the
upward stroke instead of the pump drawing in a fresh supply through the suction
valve i and gas valve k.
When the governors are in their lower position the lever h, disengages with the
valve K and the pump is then again in action.
Slide valves may be used instead of tappet valves as shown in figure 6 where 1
is the slide for admitting air and gas from the pump and for the ignition of same
and 2 the slide for admitting part of the products of combustion into generator and
for exhausting what remains in the working cylinder into the atmosphere. Theso
slide valves 1-2 are worked by eccentrics on the countershaft a as previously
described for the tappet valves the action being the same in both cases.
Having now particularly described and ascertained the nature of the said
Invention and in what manner the same is to be performed I would observe
that I lay no claim to the utilization of the waste heat of the explosion chamber
for the generation of steam to be used for assisting in working the engine but
I declare that what I do claim is
1. A gas engine wherein the waste heat of the explosion cylinder is utilized for
generating steam and wherein a portion of the products of combustion after per-
forming their work in the working cylinder is exhausted into the steam space of a

page_text: steam generator and caused to heat the water and form steam therein by surface
heating on its way into the generator and by direct contact with the surface of the
water substantially as specified..
2. A gas engine wherein a portion of the products of combustion after performing
their work in the working cylinder is exhausted into a steam generator and mixed
with the steam therein and the mixture of steam and heated gases is used for
working the piston on its return stroke in the opposite direction to that in which
it was moved by the explosion or combustion of the combustible mixture, or for
working a piston of larger area substantially as specified.
3. The combination with the working cylinder of a gas engine, of a steam
generator the water space of which is in direct connection with a water jacket
surrounding the explosion chamber of the working cylinder and which contains
tubes rising through said water space whereby the steam space can be put into
communication with the interior of the explosion chamber and of valve gear
whereby such communication is effected periodically so as to exhaust the products
of combustion after they have performed their work in the explosion cylinder into
the steam space of the generator substantially as and for the purpose specified.
4. A Gas Engine in which the working cylinder is double acting and its piston is
worked in the one direction by explosions occurring not oftener than every second
stroke, and by the reexpansion of part of the products of combustion (cushioned or
compressed in the explosion chamber) at the intervening stroke or strokes, and in
the opposite direction by a mixture of steam and the products of combustion which
have done work in the explosion chamber, admitted to the other end of the
cylinder at every return stroke of the piston substantially as specified.
5. In a gas engine the combination of double acting working piston and cylinder
having an explosion chamber at one end, a water jacket surrounding said explosion
chamber, a steam generator in communication with said water jacket, tubes rising
through the water space of the generator into the steam space and in communi-
cation below with a passage controlled by valves and leading from the explosion
chamber, valves operated from a counter shaft driven from the main shaft for
controlling the exhaustion of the products of combustion partly into the generator
and partly into the open air, and passages and valve gear for effecting the periodical
admission of the mixture of steam and gases from the steam generator to the end of
the working cylinder opposite to the explosion chamber and its exhaustion there-
from substantially as described and shown in the drawings.
6. The general combination of parts of the gas engine arranged and operating
substantially as herein described and illustrated in the drawings.
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ليم
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