Improved Means for Preventing “Back Ignition" in Hydrocarbon Engines.
Year: 1886

page_text: Date of Application, 22nd Apr.. 1886
Complete .Left, 22nd Jan., 1887.
Complete Accepted, 22nd Feb., 1887.
Improved Means for Preventing “Back Ignition" in Hydrocarbon
Engines.
1, JOHN JOSEPH REVELEY HUMES, of 18 Lilford Road, Camberwell, in the County
of Surrey, Engineer, do hereby declare the nature of this Invention to be as follows
In motor engines operated by the combustion of a gaseous or liquid hydrocarbon,
there prevails a tendency for the inflammation of the carburetted air or other combustible
mixture to spread from the cylinder or other chamber in which ignition takes place to
the vessel whence the inflammable charge is drawn notwithstanding the interposition
of a valve or other device intended to check return flow. Such back ignitions not only
result in a wasteful expenditure of fuel, but cause severe shocks to the apparatus and
are attended with danger.
My invention relates to means applicable to hydrocarbon engines for the prevention
of the objectionable effect above referred to, these means being of the following
description.
Between the cylinder or other chamber in which ignition of the inflammable charge
is effected and the chamber or other source of supply whence the gas or combustible
mixture is drawn, I form a passage which for several inches of its length is filled with
wires arranged longitudinally and of small diameter. The gas or other inflammable
fluid, on its way to the explosion chamber, traverses the narrow interstices between the
wires. Under ordinary circumstances, I find a passage from six to eight inches long
completely charged with longitudinal wires of the diameter known as No. 20 B. W. G.
adapted for my requirements.
An appliance of the kind described operates in the following manner to prevent
back ignition in hydrocarbon engines :-Assuming that the inlet valve.to the cylinder,
or other chamber in which ignition takes place, has not closed with the requisite
promptness, and that from this or other cause gas in a state of combustion is escaping
back through the inlet passage, the flame arrives at the wire-charged section thereof.
Entering the interstices between the said wires, the gases are subjected to a rapid

page_text: :
cooling effect the wires presenting a large superficial area in proportion to the
sectional area of their interstices. The gases having travelled a short distance in
contact with the wires, the temperature of the former becomes reduced below that
corresponding with combustion, and the flame is extinguished.
I am aware that wire-gauze in one or more thicknesses has been proposed for
arresting flame; but where the latter is urged by even a moderate pressure, such
means are inadequate.
Although I have described what I regard as the best mode of carrying my invention
into effect, I do not confine myself strictly to the use of wires closely packed in a
passage of sufficient length; as continuous narrow interstices or channels of the kind
described may be formed by other means and the same effect produced without
departing from the principle of my invention.
G. G. M. HARDINGHAM.
191, Fleet Street, London, E.C.,
Agent for the Applicant.

page_text: COMPLETE SPECIFICATION.
Improved Means for Preventing "Back Ignition" in Hydrocarbon
Engines.
1, JOHN JOSEPH REVELEY HUMES, of 18 Lilford Road, Camberwell, in the County
of Surrey, Engineer, do hereby declare the nature of this invention and in what
manner the same is to be perforined to be particularly described and ascertained in
and by the following statement:-,
In motor engines operated by the combustion of a gaseous or liquid hydrocarbon,
there prevails a tendency for the inflammation of the carburetted air, or other
combustible mixture, to spread from the cylinder, or other chamber in which ignition
takes place, to the vessel whence the inflammable charge is drawn, notwithstanding the
interposition of a valve or equivalent device intended to check return flow. Such
back ignitions not only result in a wasteful expenditure of fuel, but cause severe shocks
to the apparatus and are attended with danger.
My invention relates to means, applicable to hydrocarbon engines, for the prevention
of the objectionable effect above referred to, these means being of the following
description.
Between the cylinder, or other chamber in which ignition of the inflammable charge
is effected, and the chamber, or other source of supply whence the gas or combustible
mixture is drawn, I form a passage which, for several inches of its length, is fitted with
wires arranged longitudinally and of small diameter. The gas or other inflammable
fluid, on its way to the explosion chamber, traverses the narrow interstices between the
wires. Under ordinary circumstances, I find a passage from six to eight inches long
completely charged with longitudinally arranged wires of the diameter known as
No. 20 B. W. G. adapted for my requirements. In order to prevent the wires becoming
displaced, either by the suction or by the back pressure resulting from the explosion,
it is expedient to provide them at each end with a perforated diaphragm or grating.
An appliance of the kind described operates in the following manner to prevent
back ignition in hydrocarbon engines. Assuming that the inlet valve to the cylinder,
or other chamber in which ignition takes place, has not closed with the requisite
promptness, and that from this or other cause gas, in a state of combustion, is searching
back through the inlet passage, the flame arrives at the wire-charged section thereof.
Entering the interstices between the said wires, the gases are subjected to a rapid
cooling effect the wires presenting a large superficial area in proportion to the
sectional area of their interstices. The gases, after travelling a short distance in
contact with the wires, become reduced to a temperature below that corresponding
with combustion, and the flame is extinguished.
Instead of charging a certain length of the inlet passage with closely packed wires
as and for the purpose above described, a sheet or sheets of wire gauze, or other
suitable material, may be rolled in numerous convolutions, preferably upon a solid
core, and placed longitudinally in the passage so as to fill same. I am aware that

page_text: wire gauze in one or more thicknesses has been proposed for arresting flame; but
where the latter is urged by even a moderate pressure, such means are inadequate,
unless a considerable number of sheets be interposed, in which case the resistance
offered to the passage of the incoming gas is undesirably augmented. When, however,
the sheets are arranged longitudinally with the passage as above described, instead of
transversely thereto, continuous narrow interstices or channels are formed, which the
inflammable gas or vapour traverses, on its way to the combustion chamber, with com-
parative facility whilst the return of flame through such narrow interstices is
prevented by the cooling effect of the material forming the walls of the channels, as
in the method of construction embodying the use of longitudinally disposed wires. It
will be obvious that sheet metal may be substituted for the roll of wire gauze; care
being however taken to establish and maintain the several coils or layers of metal at
narrow and regular intervals from one another.
in
Having thus particularly described and ascertained the nature of this invention and
n what manner the same is to be performed, I claim :—
-
The improved means substantially as herein described for preventing back ignition
in hydrocarbon engines; such means consisting in furnishing an adequate length of
the passage conveying the inflammable charge to the combustion chamber with closely
packed wires arranged longitudinally, or with other suitable material disposed in such
a manner that narrow, but continuous and approximately direct, channels are formed
in a longitudinal direction through the mass thereof.
G. G. M. HARDINGHAM,
191, Fleet Street, London, E.C.,
Agent for the Applicant.