IMPROVEMENTS IN THE CONSTRUCTION, ARRANGEMENT, AND METHOD OF ACTION OF GAS ENGINES
Year: 1880

page_text: LETTERS PATENT to John Roger Purssell, of Kingston Road, Mertọn, in the
County of Surrey, Engineer, for an Invention of "IMPROVEMENTS IN THE
CONSTRUCTION, ARRANGEMENT, AND METHOD OF ACTION OF GAS ENGINES."
PROVISIONAL SPECIFICATION left by the said John Roger Purssell at the
Office of the Commissioners of Patents on the 24th September 1880.
JOHN ROGER PURSSELL, of Kingston Road, Merton, in the County of Surrey,
Engineer. "IMPROVEMENTS IN THE CONSTRUCTION, ARRANGEMENT, AND METHOD
OF ACTION OF GAS ENGINES."
The object of this Invention is a new construction, arrangement, and method of
action of gas engines.
I employ a double piston, or two pistons (coupled), working within a single
cylinder having two explosion chambers, one at each end, the rod connecting the
two pistons through its cross head works from the centre of the cylinder upon the
fly wheel shaft by outside rods. The cylinder is open at each end, and other or
outer pistons work within them whose rods are 'connected to crank pins working
segmental wheels which gear into other segmental wheels, which cause the outer
pistons to travel towards the centre to act in conjunction with the inner pistons
moving from the centre to exhaust the residues of combustion after each
explosion.
The outer pistons, when released from the action of the segmental wheels, are
drawn back to their first positions, said motion occurring when the inner coupled
pistons make their move in the opposite direction to draw a fresh combustible
charge into the cylinder at that end.
The crosshead of the rod of the two centre pistons may have other rods attached
to work a second crank shaft carrying a fly wheel at the opposite end of the
cylinder in order that machinery may be driven from either end or from both ends,
the accumulated power from the momentum of the two fly wheels securing the full
value of power of the explosive charges.
The operations of my engine with reference to the coupled piston are, supposing
at, say, No. 1 end of the cylinder a charge is being taken in during the intravel of

page_text: piston A, and that a charge is being compressed in, say, No. 2 end of the same
cylinder by corresponding travel of piston B, the compressed charge in No. 2 end,
on being fired, causes piston B to travel in the reverso direction, and also piston A,
which compresses the charge in No. 1 end; this is next fired, and the travel of
piston A back again causes piston B to exhaust the residues of combustion from t
end No. 2 of cylinder.
These last two movements of the pistons A, B, are occasioned by the explosion
of the charges from opposite ends of the cylinder in successive order, the other
ends of the cylinder in the first case compressing the fresh charge, and in the
other causing the exhaust of the residues of combustion of an earlier fired
charge.
•
The next stroke of the coupled pistons causes an exhaust from No. 1 end and a
suction into No. 2 under the momentum of the fly wheel, as do also the suction at
No. 1 end, and a compression of the fresh charge in No. 2, after which the
compression in No. 1 recommences the series of operations under the expansivo 1
forces of the exploded charges, as before mentioned.
The next series of operations,' which are repeated as above described, being
maintained under the action of the fly wheel or wheels, by fitting two of such
cylinders, and connecting the coupled pistons to the same crank shaft or shafts,
the explosion can be caused to follow each other in successive order, following the
compression of each charge at either end of tho cylinders at every half revolution
of the crank shaft. -
-
The outer pistons, rods, and segmental gear are employed in connection
therewith, as with tho first described engine.
Sometimes I arrange two distinct cylinders with separate crank shafts to work
in.opposite directions-to-each-other.
By these means the usual power in gas engines during certain portions of their
working at present derived from and dependent upon the fly wheel is obviated,
whereby my engines can be made available for locomotivo and other purposes,
especially when compressed gas can be conveniently carried, such as in tram cars,
launches, and other vehicles and vessels, for which purposes, as well as for ordinary
purposes, for which gas engines are now almost exclusively employed.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said John Roger Purssell in the Great Seal Patent Office on the 24th
March 1881.
JOHN ROGER PURSSELL, of Kingston Road, Merton, in the County of Surrey,
Engineer. "IMPROVEMENTS IN THE CONSTRUCTION, ARRANGEMENT, AND METHOD
OF ACTION OF GAS ENGINES,"
The object of this Invention is a new construction, arrangement, and method of
action of gas engines.
I employ a double piston, or two pistons (coupled), working within a single
cylinder having two explosion chambers, one at each end, the rod connecting the
two pistons through its crosshead, which work from the centre of the cylinder upon
the fly wheel shaft hy outside rods. The cylinder is open at each end, and other
or outer pistons work within them, whose rods are connected to crank pins working
segmontal wheels, or their equivalents, which genr into other segmental wheels
which cause the outer pistons to travel towards the centre to act in conjunction
with the inner pistons moving from the centre to exhaust the residues of combustion
after each explosion.
The outer pistons, when released from the action of the segmental wheels are
drawn back to their first positions, said motion occuring when the inner coupled
pistons make their nove in the opposite direction to draw a fresh combustible
charge into the cylinder at that end.
The cross head of the rod of the two centre pistons may have other rods attached
to work a second crank shaft carrying a fly wheel at the opposite end of the
cylinder in order that machinery may be driven from either end or from both ends,
the accumulated power from the momentum of the two fly wheels securing the full
value of power of the explosive charges.
The operations of my engine with reference to the coupled piston are, supposing
at, say, No. 1 end of the cylinder a charge is being taken in during the intravel of
piston A, and that a chargo is being compressed in, say, No. 2 end of same cylinder,
by corresponding travel of piston B, the compressed charge in No. 2 end, being
fired, causes piston B to travel in the reverse direction, and also piston A, which
compresses the charge in No. 1 end. This is next fired, and the travel of piston A
back again causes piston B to exhaust the residues of combustion from end No. 2
of cylinder. These last two movements of the pistons A, B, are occasioned by the
explosion of the charges from opposite ends of the cylinders in successive order,
the other ends of the cylinder in the first case compressing the fresh charge, and in
the other causing the exhaust of the residues of combustion of an earlier fired
charge.
The next stroke of the coupled pistons causes an exhaust from No. 1 end and a
suction into No. 2 under the momentum of the fly wheel, as do also the suction at
No. 1 end and a compression of the fresh charge in No. 2, after which the com-
pression in No. 1 recommences the series of operations under the expansive forces
of the exploded charges, as before mentioned.
The next series of operations, which are repeated as above described, being
maintained under the action of the fly wheel or wheels. By fitting two of such
cylinders and connecting the coupled pistons to the crank shaft or shafts the
explosion can be caused to follow each other in successive order, following the
compression of each charge at either end of the cylinders at every half revolution of
the crank shaft.
The outer pistons, rods, and segmental gear are employed in connection therewith
as with the first described engine.
Sometimes I arrange two distinct cylinders with separate crank shafts to work

page_text: in opposite directions to each other. By these means the usual power in gas engines
during certain portions of their working, derived from and at present dependent
upon the fly wheels is obviated, whereby my engines can be made available for
locomotive and other purposes, especially when compressed gas can be conveniently
carried, such as in train cars, launches, and other vehicles and vessels, for which
purposes, as well as for ordinary purposes, for which gas engines are now almost
exclusively employed.
My Invention will be understood by the annexed Sheet of Drawings, in which I
show in Figure 1 a part sectional elevation, and in Figure 2 a plan of two coupled
cylinder engines, the inner pistons of both being connected in pairs to a crank shaft:
common to both, as before referred to.
A, B, are the two coupled cylinders; E, F, G, H, the piston therein; I, J, are
cross heads working with slide blocks K, L; and M, N, are the connecting rods
attached to cranks P, P, Q, Q, of the main shaft R, on which the fly wheel S is
mounted. T, T, are spur wheels on tho main shaft R, and U, U, are other spur
wheels gearing into T, T, for giving motion to shafts V, V, for operating the feed
valves W, W, by which the combustible mixture is admitted to the cylinders in
the desired order. On the shafts V, V, are arranged four sprocket wheels X, X, for
producing a rotation of the lighting valves Y, Y, through the intermediation of
chains Z, Z, and bevil gearing a, a. The cylinders, which are of larger diameter
at one end than at the other, are provided with loose yet gas tight moveable covers
or pistons b, b, which are drawn to- and -fro in the larger diameter portions by
levers c, c, operated by cams d, d, on the lower shuft V, V, at certain parts of the
stroke of the main or working pistons E, F, G, H,_the_moveable_ends.b,-b,-being-
locked-when-in-the-inner end of their stroke by locking bolts e, e, such as are shown
at Figure 3, this being an end view-detached. The locking bolts are caused to
pass into the chamber and behind the end covers under the action of cams f, f, on
the lower shafts, and to open out again under the return action of springs g, one
only of which is shown.
Figure 4 is an enlarged transverse section of one of the cylinders to show how
the feed valve W for the supply of the combustible (such as coal gas and air in
suitable proportions) is admitted. The valve W is double, and the space i between
them serves as the receptacle for the gas coming from the pipe j, in which space
the gas is pocketed until the double valve W is raised by the cam (Figures 4
and 5) which in its rotation acts upon the lever 1, and as the gas passes into the
cylinder, atmospheric air passes through the saine valve with it, and the two become
mixed to form the combustible body, this passing into the cylinder when the
working piston F is moving inwards, the loose end b of the same cylinder having
an outward motion at the same time that that portion of the cylinder becomes filled
with an agitated live charge, the working piston having by this time gone nearly
one third only of its outstroke, the loose end b is now suddenly forced to make its
instroke by its cam and lever to compress the charge between itself and the
working piston F, the locking bolts e being as suddenly acted upon to lock it in
that position that by the time the working piston has travelled about one third of
its stroke the charge has been drawn in and become compressed, the lighting
valve Y is at that instant brought round that its aperture m is opposite a holo n
in the cylinder for firing the charge which compels the piston under the impulse
and expansion to complete the stroke. The working piston then travels back, and
the residue or products of combustion are expelled through the valve p, the loose
end of the cylinder b still being kept locked by the bolts e.
Figure 6, 7, and 8 show details of my lighting valve composed of small rotating
barrel Y or tubing with the ends closed. This barrel Y works in a sleeve Z¹, and
has a nozzle or gas nipple q fitted in its side, which nipple is supplied with gas
passing into a segmental slot r from the pipes as it rotates, the nipple taking its
light from an outside flame through the aperture in the sleeve when brought
opposite to it. Other systems of lighting or firing the charge may be adopted,
such as by the usual slide with inside and outside flame, or by clectric current, if

page_text: found convenient. One pair of coupled cylinders may be arranged to work a
single crank from the same end, or cranks from opposite ends of the couplod
cylinders.
Having now described the nature of my said Invention, and in what manner the
same is to be performed, I declare that I claim,-
The general arrangement and disposition of cylinders and details of gas engine
shown in the annexed Drawings.
Secondly. I claim the compression, ignition, and expansion of combustible
charges in succession in cylinders, arranged substantially as set forth and shown in
the annexed Drawings, the compression being effected by pistons of larger
diameter, pushing the charges into smaller diameters of cylinders, within which
the working pistons are fitted as described.
In witness whereof, I, the said John Roger Purssell, have hereunto set my
hand and scal, this Twenty fourth day of March, in the year of our Lord
One thousand eight hundred and eighty one.
Witness,
H. GARDNER,
Patent Agont,
40, Fleet Street,
London.
J. R. PURSSELL. (L.S.)