Year: 1886

page_text: Date of Application, 11th Mar., 1886.
Complete Left, 13th Dec., 1886.
Complete Accepted, 14th Jan., 1887.
I CHARLES DAVY of 24 Lawson Road, Sheffield, in the County of York Engineer,
do hereby declare the nature of this invention to be as follows:-
This Invention relates to Gas-Engines of the type in which the combustible mixture
of gas and air is compressed before ignition, and its object is to reduce, as far as possible,
the loss of heat through the walls of the cylinder and thus prevent chilling of the flame,
and defective combustion and other ill effects consequent thereon.
In such Gas-Engines the flame resulting from the explosion of the combustible
mixture usually comes into direct contact with the walls of the cylinder, and the
transference of heat thereby occasioned chills the flame, and impedes combustion. So
great is the loss of heat that it is usually necessary to water jacket the walls of the
chamber and cylinder to prevent overheating.
My Invention consists in more or less completely isolating the explosivo charge from
the walls of the cylinder by a circumferential non-conducting belt of air and inert
gases, whereby such loss of heat is reduced, and the use of a water jacket to a great
extent, or altogether, rendered unnecessary. The heat absorbed by the belt of non-
combustible gases is utilized by expanding those gases which thus work in the cylinder
besides serving to isolate the charge.
To carry out my Invention I inject, or introduce, into the axial centre of the
combustion chamber (which is already filled with air and a residuum of inert gases
compressed to a suitable pressure) the charge of gas and air in such manner as to form
a combustible core or cartridge encircled by a belt of non-combustible gases, which
more or less completely isolates the charge from the walls of the cylinder, the mode of
introducing the charge and the internal form of the explosion chamber being such as
to promote the circumferential arrangement of the air and inert gases.
C. DAVY.
By A. M. & Wm. Clark,
53, Chancery Lane, London,
Patent Agents.

page_text: An Improvement in Gas Engines.
I, CHARLES DAVY of 24 Lawson Road Sheffield in the County of York, Engineer
do hereby declare the nature of this invention and in what manner the same is to be
performed, to be particularly described and ascertained in and by the following
statement—
This Invention relates to gas-engines of the type in which the combustible mixture
of gas and air is compressed before ignition; and its object is to reduce, as far as
possible, the loss of heat through the walls of the cylinder and thus prevent chilling of
the flame, and defective combustion, and other ill effects consequent thereon. In such
gas-engines the flame resulting from the explosion of the combustible mixture usually
comes into direct contact with the walls of the cylinder, the consequent transference or
loss of heat being so great that it is usually necessary to water-jacket the walls of the
chamber and cylinder to prevent overheating of the metal.
The method of attaining the object of my Invention consists essentially in causing
the explosive charge to be more or less completely isolated from the walls of the
cylinder by an intervening circumferential non-conducting belt of air and inert gases,
whereby such transference and consequent loss of heat is reduced and the use of a
water-jacket to a great extent or altogether rendered unnecessary. The heat absorbed
by the belt of non-combustible gases is utilized by expanding those gases which thus
work in the cylinder besides serving to isolato the charge. In order to obtain this
concentric arrangement of the combustible charge and the non-conducting incombustible
gaseous envelope, the charge of gas and air is injected or introduced into the axial centre
of the combustion chamber (which is already filled with a mixture of air and residual
inert gases compressed to a suitable pressure) in such manner that it will occupy a
central longitudinal or axial position therein without spreading to any great extent in
the radial direction the arrangement being such that the charge will form a sort of
combustible core or cartridge encircled by a belt of non-combustible gases which moro-
or less completely isolates the charge from the walls of the cylinder.
Reference to be had to the accompanying drawings forming part of this specification
and which illustrate an arrangement of engine suitable for obtaining the object of my
Invention. I do not, however, in any way limit.myself to the particular construction
of engine herein described and illustrated, except in so far as the same is essential to
the obtainment of the concentric arrangement of the charge and of the inert gases, as
above described. Figure 1 is a central longitudinal vertical section, Figure 2a-plan,,
and figure 3 an end elevation, Figures 4 and 5 shew details of the valve gear,,
Figures 6, 7, and 8 shew a modified arrangement of the engine. The same letters of
reference indicate the same parts in all the figures.
A is the working cylinder, and B its piston giving motion to the crank shaft in the
ordinary way: C is the pump piston connected with the working piston B so that
both move together. In the example shewn, an arm to which the pump piston rod is
connected is cast on the piston B near its end and slides in a longitudinal guide slot in
the cylinder A. The pump cylinder D may be cast with or otherwise connected with
the working cylinder A. In the example illustrated in figures 1, 2, 3, it is parallel

page_text: with and above the working cylinder, a port or passage E leading from the end of the
pump cylinder D to the end of the working cylinder A, said passage being controlled
by the delivery valve F. This passage E is preferably of the form shewn, and it leads
centrally through the end of the portion of the working cylinder which constitutes the
explosion chamber, in order to give the combustible charge the requisite axial direction
of travel through the combustion chamber, and to favor this concentric arrangement the
passage E is of gradually increasing sectional area from the pump to the working
cylinder. The working cylinder is provided with an ignition slide valve G working
over a port leading into the passage E, the slide being constructed and working in any
suitable and known way for effecting the ignition of the explosive charge at the proper
moment. The pump is provided with a compound inlet valve H for gas and air,
opening inwards to the pump cylinder and the combustion chamber of the latter is
provided with an exhaust valve I opening against the pressure, these several valves
being, in the example shewn, all operated at proper times by cams on a shaft K driven
by bevel gear from the crank shaft at half the speed of the latter, the ignition slide G
being worked directly by a cam or eccentric on shaft K, the inlet valve H to the pump
and the delivery valve F to the working cylinder being both worked by the same
cam L on the shaft K acting through a rock shaft M having a lever arm m terminating in
a friction roller which runs in the groove of the cam L, and lever arms h and facting
on the spindles of the respective valves. The cam L (whose development is shewn by
figure 5) so shaped and is so placed in its angular relation to the crank shaft as to
open and close the valves at proper times, the valve H being actuated by the part * of
the cam L and the valve F by the part fx of said cam, both valves remaining closed
whilst the roller on the arm m is in the plain part of the cam groove. The valves may,
however, be actuated by separate cams in any convenient manner.
The valve H is
held to its seat by a spiral spring acting against a collar upon the valve spindle and is
opened by the pressure of the lever arm & against the end of the spindle. The valve F
is also held to its seat by a spiral spring and is opened by the arm fengaging in a
slotted head on the valve spindle. The exhaust valve I is actuated by a cam i on
shaft K acting through a bent lever fulcrumed at and bearing at one end by a
friction roller against the cam and at the other end against the end of the spindle of
the valve which is held to its seat by a spiral spring, and the cam i is so shaped and
is so placed in its angular relation to the crank shaft as to give the desired motion to
the valve. The exhaust passage is provided with valves N, O, placed in a valve box
as near as possible to the working cylinder, the valves opening and closing automatically,
the one N to permit the escape of the exhaust gases and the other O to admit a charge
of pure air to the working cylinder on the second outstroke of the piston, as hereafter
described. In some cases, an automatic valve for the admission of pure air
may be
substituted for the valves N, O, as shewn in figure 8, the cam i being in this.
case modified so as to open the exhaust valve I on or a little before the completion
of the first outstroke, and close it at or near the end of the first instroke.
The engine works on the well known four cycle principle, and in describing its
action I will assume there is a combustible charge in the combustion chamber of the
working cylinder, and that the valves F, H and I are closed, as in figure 1. On the
ignition of the charge through the ignition slide valve G, the pistons B and C
perform their first outstroke the piston B being propelled by the pressure due to the
combustion of the charge. The air and gas valve H and the delivery valve F being
closed; a vacuum is formed in the pump cylinder. When the pistons are near the
end of their outward stroke the exhaust valve I is opened and remains open during
the return or first instroke which is effected partly by the momentum of the fly-
wheel and partly by the vacuum formed in the pump cylinder during the preceding
outstroke. On the second outstroke, which is made by the momentum of the fly-
wheel, the exhaust valve I being still held open a charge of pure air is admitted to
the working cylinder wherein it mixes with the residue of the inert gases which were
produced by the combustion of the explosive charge. The valve H is opened at the
beginning of this second outstroke admitting a rich combustible charge of gas and
air to the pump cylinder and it is closed at or near the end of the stroke. The

page_text: second instroke, which completes the cycle, is also made by the momentum of the
fly-wheel the exhaust valve I being closed either at beginning of this stroke or when
the piston B has travelled through part of its stroke, and the air and inert gases
then contained in the cylinder become compressed. The combustible charge contained
in the pump cylinder also becomes compressed, and at a suitable point of the stroke
the delivery valve F is opened and allows the combustible charge to pass rapidly
into the working cylinder wherein it occupies a central longitudinal position forming
a sort of core or cartridge surrounded by a belt of a non-combustible mixture of air
and inert gases. The engine is then ready to recommence the cycle of operations.
The valve H closes against two concentric seats to the annular space q between
which seats gas is admitted, whilst air is admitted to the central space r. The
admission of gas to the space q is controlled by a valves (figure 2) operated as often
as necessary to maintain the proper working speed by the governor bringing a knife
edge (carried by a sliding arm T which bears against the end of the stem of the
valve s) into alignment with a V grooved plate u carried by the lever arm h, the
governor acting on the rod T through a rock shaft and connections, as will be readily
understood.
Instead of the pump cylinder being above the working cylinder, as in figure 2, or
alongside of it, as in figure 6, it may be fixed in line therewith and the pump piston
may be worked by any convenient means. Instead of conducting the combustible
charge direct from the pump to the working cylinder the mixture of gas and air
may be pumped into an intermediate receiver W, as shewn in figure 6, whence the
proper charge is withdrawn and is admitted by the valve F to the working cylinder
through the passage E. This engine differs somewhat in its construction and operation
from that previously described, but it will be readily understood from an inspection
of the drawing without further explanation, the combustible charge being encircled,
as before, by a belt of inert gases and air intervening between the charge and the
walls of the working cylinder.
Having now particularly described and ascertained the nature of the said Invention,
and in what manner the same is to be performed, I declare that what I claim is :—
A gas engine wherein a charge of a rich combustible mixture of gas and air is
injected at the proper moment into the axial centre of a compressed non-combustible
charge already contained in the working cylinder (such non-combustible charge
consisting of a residuum of inert gases from the previous explosion mixed with pure
air drawn into the working cylinder at the intermediate outstroke) so that the
combustible charge will be surrounded by a belt of non-combustible gas and air
which intervenes between the combustible charge and the walls of the cylinder as and
for the purpose specified.
CHAS. DAVY.
By A. M. & Wm. Clark,
53; Chancery Lame, London,
Patent Agents.