IMPROVEMENTS IN GAS MOTOR "
Year: 1881

page_text: LETTERS PATENT to John Fielding, of the Atlas Works, Gloucester, in the
County of Gloucester, for an Invention of "IMPROVEMENTS IN GAS MOTOR
"
PROVISIONAL SPECIFICATION left by the said John Fielding at the Office
of the Commissioners of Patents on the 8th February 1881.
JOHN FIELDING, of the Atlas Works, Gloucester, in the County of Gloucester.
"IMPROVEMENTS IN GAS MOTOR ENGINES."
My Invention has reference to the class of gas motor engines in which the mixed
air and gas, and by whose explosion or combustion and consequent expansion the
engine is worked, is ignited whilst in a compressed state.
According to my Invention the fluid charge to be exploded or ignited, or part
thereof, is admitted into the working cylinder by a port or ports so situated in the
barrel of the cylinder as to be uncovered by the piston when it approaches the end
of its acting stroke, and covered again soon after the piston has commenced its
return stroke. In such an engine, according to one arrangement, the said cylinder
is closed at one end by a suitable cover, and at the other end opens into a casing
within which revolves a crank that works in suitable bearings in one or both sides
of such casing. The piston is connected to the crank by a connecting rod to
convert the reciprocatory motion into a rotary motion. The first named end of the
cylinder is that in which the combustible mixture is compressed and ignited, and
for clearness I will call it the outer end of the cylinder. The opposite end, namely,
that opening into the crank casing, acts as a pump supplying the mixture of air
and gas which it forces at a slight pressure into a reservoir (which may conveniently
surround the cylinder). In connection which the crank casing and reservoir there
are provided suitable inlet and delivery valves for both air and gas; these valves
control the flow of air and gas into the crank casing, and thence into the reservoir.
Also there is a valve near the outer end of the cylinder or in the cover thereof
for the escape of the waste products of combustion.
A port (which may be annular) is formed in the cylinder barrel as already
stated in such a position that it is uncovered by the piston when the latter
approaches the end of its acting stroke. This port establishes a communication

page_text: -
between the reservoir and the acting end of the cylinder. Immediately before
this port is uncovered the escape valve is opened by any suitable ineans operated
by the engine itself to allow of the escape of the spent gases, and upon the port being
opened or uncovered the fresh charge of gas and air escapes from the reservoir, and
being slightly under pressure drives out the remaining or most of the remaining
spent gases before the piston returns and recloses the port. After the piston on its
return stroke has reclosed the port, the fresh charge is compressed (the escape valve
baving been closed at about the same time that the port was covered by the piston)
and also such portion of the spent gases as may not have escaped.
When the piston has completed its compressing or return stroke the compressed
charge is ignited by any suitable means which may be such as are at present in use
in connection with gas motor engines.
It will be understood that in order to start the engine at least one complete
revolution must be made by hand or ather extraneous agency.
In a modified arrangement the separate reservoir is dispensed with, and a port in
the cylinder barrel establishes direct communication between the outer end of the
cylinder and the crank (or pump) casing.
Also instead of the air and gas being admitted to the crank casing together a
separate gas pump may be used so that the spent gases may be driven out by air
only, the gas pump delivering into the main cylinder after the spent gases are
ejected.
Instead of the crank and connecting rod being arranged within a crank casing
as above described, the construction may be modified by providing the piston
with a rod extending through a casing arranged to serve as the pump casing and
through a stuffing box, such rod being furnished with a crosshead and connected to
the crank by a connecting rod.
As is obvious, other modifications of gas motor engines may be constructed to
operate on the principle of my Invention as hereinabove set forth.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said John Fielding in the Great Seal Patent Office on the 8th August
1881.
JOHN FIELDING, of the Atlas Works, Gloucester, in the County of Gloucester.
"IMPROVEMENTS IN GAS MOTOR ENGINES."
My Invention has reference to the class of gas motor engines in which the mixed
air and gas, by whose explosion or combustion and consequent expansion the
engine is worked, is ignited whilst in a compressed state.
According to my Invention the fluid charge to be exploded or ignited, or part
thereof, is admitted into the working cylinder by a port or ports so situated in the
barrel of the cylinder as to be uncovered by the piston when it approaches the end
of its acting stroke, and covered again soon after the piston has commenced its
return stroke. In such an engine, according to one arrangement, the said cylinder
is closed at one end by a suitable cover, and at the other end opens into a casing
within which revolves a crank that works in suitable bearings in one or both sides
of such casing. The piston is connected to the crank by a connecting rod to
convert the reciprocatory motion into a rotary motion. The first named end of the
cylinder is that in which the combustible mixture is compressed and ignited, and
for clearness I will call it the outer end of the cylinder. The opposite end, namely,
that opening into the crank, casing, acts as a pump supplying the mixture of air
and gas which it forces at a slight pressure into a reservoir (which may conveniently
surround the cylinder). In connection with the crank casing and reservoir there
are provided suitable inlet and delivery valves for both air and gas; these valves
control the flow of air and gas into the crank casing, and thence into the reservoir.
Also there is a valve near the outer end of the cylinder or in the cover thereof for
the escape of the waste products of combustion.
A port (which may be annular) is formed in the cylinder barrel, as already stated,
in such a position that it is uncovered by the piston when the latter approaches the
end of its acting stroke. This port establishes a communication between the
reservoir and the acting end of the cylinder. Immediately before this port is
uncovered the escape valve is opened by any suitable means operated by the engine
itself to allow of the escape of the spent gases, and upon the port being opened or
uncovered the fresh charge of gas and air escapes from the reservoir, and being
under a slight pressure drives out the remaining or most of the remaining spent
gases before the piston retains and recloses the port. After the piston on its
return stroke has reclosed the port the fresh charge is compressed (the escape valve
having been closed at about the same time that the port was covered by the
piston), and also such portion of the spent gases as may not have escaped.
When the piston has completed its compressing or return stroke the compressed
charge is ignited by any suitable means which may be such as are at present in use
in connection with gas motor engines. It will be understood that in order to start
the engine at least one complete revolution must be made by hand or other
extraneous agency.
Instead of the crank and connecting rod being arranged within a crank casing
as above described the construction may be modified by providing the piston with
a rod extending through a casing arranged to serve as the pump casing and through
a stuffing box, such rod being furnished with a crosshead and connected to the
crank by a connecting rod.

page_text: with the cylinder placed above the crank shaft and the crank and connecting
rod working within a closed chamber; Fig. 4 shews in longitudinal section
an arrangement of a gas motor engine with piston rod and stuffing box,
crosshead, and guides suitable for working with the connecting rod and crank shaft
exposed.
In Figs. 1 and 2, A is the piston working within the cylinder B and connected
by the rod C to the crank D, both of which work within a casing E. The upper
portion of the cylinder B is that in which the explosion of the combustible charge
takes place, the lower portion and the casing E acting as a pump for drawing in and
slightly compressing the successive charges of air and mixed gas and air, previous
to their entry into the upper part of cylinder B. F is the gas supply pipe; G the
gas inlet valve operated by the cam G₁ and the tappet lever G³; H is the air inlet
valve, which may be operated either by the pressure of the atmosphere or by a
suitable cam and tappet lever or their equivalents; I is a valve which when raised
by means of the cam I¹ and tappet lever I permits the flow of air past the valve H,
through the chamber J and passage K during the upward stroke of the piston A.
The valve I however is not raised until the piston has advanced so far on its
upward stroke as to cover the ports L in the cylinder B. The valve I may be held
open by means of its cam and tappet lever during the whole of the downward
stroke of the piston, to permit the contents of the casing E being driven into the
chamber J, or it may be allowed to close as soon as the piston has reached the
upper end of its stroke, the compression of the contents of casing E by the down-
ward stroke of the piston being sufficient to lift the valve again from its seat, when
it will simply act as a non-return valve, preventing the re-expansion of the contents
of the chamber J into the casing E during that part of the upward stroke of the
piston in which it moves, from the lowest point to that at which it closes the
ports L in the cylinder B.
From the arrangement of the valve G, H, and I and the chamber J, it will be
evident that when the piston is at the top of its stroke, the casing E is full of a
mixture of gas and air and the chamber J contains air only, so that during the
downward stroke of the piston the explosive mixture is forced from the casing E
into the chamber J, the air in the latter being forced towards its upper part
into the ports L, the contents of the chamber J at the moment when the ports L are
uncovered by the piston, being divided into two strata, of which the upper is air
and the lower an explosive mixture of gas and air, and these strata enter the cylinder
in the same order, viz., air first and then the mixed air and gas. This arrange-
ment is to obviate liability to premature explosion, which might result were the
explosive mixture allowed to come into direct contact with the heated products
of combustion; the introduction of the air into the cylinder in advance of the gas
and air prevents such contact taking place.
M is the exhaust valve operated by means of the cam M' and levers M², M³,
and M. N is a small chain working upón a toothed wheel N' fitting the chain
and a second wheel N; the former is securely keyed upon the crank pin O, and the
latter is allowed to run loosely upon the crosshead gudgeon P in the piston A. The
casing E being partially filled with oil and the crank dipping into or working
wholly submerged in it, the chain acts as an elevator carrying oil upwards to the
upper end of connecting rod and also to the surface of the piston, suitable channels
being provided to convey the oil from the small wheel N to the pin P and to the
surface of the piston A.
The ignition of the explosive charge in the cylinder may be effected by any of
the usual and well known means at present in use in connection with gas motor
engines.
Having thus described the nature of the said Invention; and the manner in which
it is to be performed, I claim in a gas motor engine :—
1. Introducing the charge into the cylinder through a port or ports in the wall
thereof, uncovered or opened by the main piston itself when it approaches the end
of its acting stroke, substantially as described.

page_text: 2. In a gas inotor engine wherein one side of the piston acts as an air and gas
pump, and the other receives the force of the explosion causing the successive fresh
charges of gas and air to flow from that side of the piston which acts as air and
gas pump to the opposite side of the piston through a port or ports in the wall of
the cylinder uncovered by the said piston itself as it approaches the end of its
acting stroke, substantially as described.
3. The arrangement of the intermediary chamber J, air valve H, valve I and
valve G, substantially as and for the purpose described and shewn.
In witness whereof, I, the said John Fielding, have hereunto set my hand
and seal, this Sixth day of August, in the year of our Lord One thousand
eight hundred and eighty one.
JOHN FIELDING. (L.S.)