IMPROVEMENTS IN GAS ENGINES
Year: 1882

page_text: LETTERS PATENT to Oliver Mobbs of Vulcan Iron Works, Northampton, in
the County of Northampton, Engineer for an invention of "IMPROVEMENTS IN
GAS ENGINES"
PROVISIONAL SPECIFICATION left by the said Oliver Mobbs at the Office
of the Commissioners of Patents on the 13th May 1882.
OLIVER MOBBS of Vulcan Iron Works Northampton in the County of
Northampton Engineer "IMPROVEMENTS IN GAS ENGINES
"
In gas engines of a well known type as hitherto constructed a space is formed
in the cylinder beyond the piston for containing a gaseous mixture or body of
air occurring between the explosive material and the piston for the purpose of
causing a gradual expansion of the explosive charge.
Now my invention has principally for its object to obviate the necessity of this
space by an improved construction and arrangement of gas engine having a metal
piston (or pistons) which is hollowed out at the inner or rear end of the piston rod,
so as to form a chamber thereat for the purpose of receiving the explosive charge
which is usually contained in the cylinder (or cylinders) By this means the space
required in the cylinder is not more than that usually found in ordinary steam
cylinders. I also dispense with the necessity of rings or packing segments to the
piston the expansion of the latter being sufficient to keep it tight to the cylinder.
By my invention no cushion of air is used to cause a gradual explosion in the
cylinder but such proportions of gas and air as will effect the most sudden and
violent explosion are mixed in the piston chamber.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Oliver Mobbs in the Great Seal Patent Office on the
13th November 1882.
OLIVER MOBBS of Vulcan Iron Works, Northampton, in the County of
Northampton, Engineer "IMPROVEMENTS IN GAS ENGINES"
In Gas Engines, as hitherto constructed, the pistons have been formed with a
flat or solid end to receive the explosive force, and have been fitted with steel
springs or packing segments to make what is called "tight pistons" the same as
are used in Steam Engines.
Now my Invention relates to a novel construction of pistons for Gas Engines,
whereby the inner or rear end is hollowed out, so as to form a chamber for receiving
the combustible charge. The explosion of the gases taking place in the hollow of
the piston causes the end of the piston to be expanded so as to make it spring
tightest to the cylinder at the moment of most violent explosion and slackest as
the power becomes expended. To make the expansion or spring of the piston more
effectual, the walls of the chamber in lieu of being plain may have a spiral cut
through the whole thickness of the metal, as shewn on accompanying drawing,
thereby forming the end of the piston into a spring.
In Gas Engines of a well known type as hitherto constructed, a space is provided
in the cylinder beyond the piston for containing a gaseous mixture or body of air
occuring between the explosive material and the piston for the purpose of causing
a gradual expansion of the explosive charge.
Now my Invention renders the space above referred to, unnecessary, and makes
no provision for the admittance of inert gases or cushion of air, to render the
explosion gradual. The clearance between the end of the piston and the end of
cylinder, is only what is usual in steam engines, and the hollow chamber in piston
is designed to receive only a simple mixture of gas and air of a like crude and
intimate relation as used in the earliest types of gas Engines to produce a sudden
and violent explosion.
On the accompanying drawing, Figure 1 is a longitudinal section of the cylinder
and elevation of the piston of a Gas Engine in which the piston is constructed
according to my invention.
A represents the piston hollowed out at the inner or rear end of the piston rod B,
so as to form a chamber C thereat. This chamber C receives the explosive charge,
or mixture of gas and air, which in Gas Engines as now made, occupies some of
the space between the solid end of the piston, and the end of the cylinder.
D represents a spiral cut through the walls of hollow piston A. The expansion of
the end of the piston thus formed (or plain) is sufficient to keep a tight cylinder,
and renders unnecessary any piston springs or packing segments.
Having now described and particularly ascertained the nature of my said
Invention and the manner in which the same is or may be used or carried into
effect I would observe in conclusion that what I consider novel and original and
therefore claim as my Invention, is :-
In Gas Engines the construction and use of piston hollowed out at its end so
as to form a chamber thereat, substantially as and for the purpose hereinbefore
described and illustrated by the accompanying drawing.
In Witness Whereof I the said Oliver Mobbs have hereunto set my hand
and seal this sixth day of November in the year of our Lord One thousand
eight hundred and eighty two.