AN IMPROVE- MENT IN GAS MOTOR ENGINES
Year: 1884

page_text: I, JOHN JAMES PURNELL of N° 399 Kennington Road, in the county of Surrey,
Engineer, do hereby declare the nature of my said invention for "AN IMPROVE-
MENT IN GAS MOTOR ENGINES" to be as follows:-
My invention relates to a construction of gas motor engine arranged to operate.
in the following manner. At each forward stroke of the piston, when propelled
by the expansion of the charge, a quantity of air is compressed, and, just before
completion of the forward stroke, this air is blown through the cylinder behind
the piston, so as to displace the products of combustion and discharge them by an
exhaust valve that is for a time opened. During part of the return stroke of the
piston, the exhaust valve being then closed, the air bebind the piston is compressed,
and, at the same time, gas is forced into the cylinder by a pump worked by the
engine. At the end of the back stroke, the charge of gas and air is ignited,
effecting the forward stroke of the piston. For the purpose of compressing the
air, as above described, I utilise the front part of the cylinder as an air pump, the
piston during its backstroke drawing in air through a check valve and then
during its forward stroke compressing this air, until the piston passes, a lateral
port by which the compressed air finds its way to the space in the cylinder behind
the piston.
The exhaust valve, as well as a slide for admitting gas and effecting ignition of
the charge, is worked by an eccentric or cam, or it may be worked by a lever
actuated by the lateral movement of the connecting rod.

page_text: I, JOHN JAMES PURNELL, of N° 399 Kennington Road in the County of Surrey,
Engineer, do hereby declare the nature of my invention for "AN IMPROVEMENT IN
GAS MOTOR ENGINES" and in what manner the same is to be performed to be
particularly described and ascertained in and by the following statement:-
My invention relates to a construction of gas motor engine arranged to operate
in the following manner. At each forward stroke of the piston, when propelled
by the expansion of the charge, a quantity of air is compressed, and, just before
completion of the forward stroke, this air is blown through the cylinder behind
the piston, so as to displace the products of combustion and discharge them by an
exhaust valve that is for a time opened. During part of the return stroke of the
piston, the exhaust valve being then closed, the air behind the piston is compressed,
and, at the same time, gas is forced into the cylinder by a pump worked by the
engine. At the end of the back stroke, the charge of gas and air is ignited,
effecting the forward stroke of the piston. For the purpose of compressing the
air, as above described, I utilise the front part of the cylinder as an air pump, the
piston during its back stroke drawing in air through a check valve and then
during its forward stroke compressing this air, until the piston passes a lateral
port by which the compressed air finds its way to the space in the cylinder behind
the piston.
The exhaust valve, as well as a slide for admitting gas and effecting ignition of
the charge, is worked by an eccentric or cam, or it may be worked by a lever
actuated by the lateral movement of the connecting rod.
Fig. 1 of the accompanying drawings is a longitudinal section of a gas motor
engine according to my invention; Fig. 2 is a half plan of the cylinder and gas
pump and Fig. 3 is a part plan at the crank shaft end of the engine. The
cylinder A has around its front part an annular cavity B communicating with the
interior of the cylinder by two sets of apertures 6 and 6, the one sat close to
the cylinder lid, and the other set b' behind these at a distance a little exceeding
the depth of the piston C which is connected in the usual way to a crank on the
fly-wheel shaft D. There is an inlet for air to the cavity B, furnished with a
check valve opening inwards. At the side of the cylinder A is situated the
single acting gas pump E, the plunger of which is worked by an eccentric F that
pump
E
is fixed on the flywheel shaft a little in advance of the main crank. The
has a suitable suction valve, and a discharge valve from which a passage G lends
into the cylinder A. On the lower side of the cylinder A is fitted an exhaust
valve H, which may be worked by an eccentric or cam, or as shown in Fig. 1 by a
lover linked by a rod to the connecting rod of the engine. There is also at
the end of the cylinder a alide K linked to the exhaust valve lover and behind it
there is an igniting tube L heated by an external flame. The engine oporates in
the following manner: As the piston makes its outstroke propelled by the
expansion of the cylinder chargo, gas, or preferably a mixture of gas with a
proportion of air insufficient to render the mixture combustible, is drawn into the
pump E, and, at the same time, air, which had by previous instroke of the piston

page_text: When
been drawn through the check valve 63 is compressed into the cavity B.
the piston passes the apertures 6 the exhaust valve H, then beginning to open, the
compressed air rushes from B into the cylinder A, expelling therefrom the products
of previous combustion. During the instroke of the piston C, the exhaust valve H
remains open for a time allowing escape from the cylinder, and then closes 80
that the contents of the cylinder, chiefly air, become compressed, and, at the same
time, the gas or gaseous mixture is being forced by the pump E into the cylinder.
When the piston has completed its instroke, having drawn air into the cylinder in
front of it, the slide K gives passage for part of the contents of the cylinder into
the heated tube L whereby the compressed charge in the cylinder is ignited,
causing propulsion of the piston. This cycle of operation is then repeated. The
power of the engine may be regulated by a governor M which, when the velocity
becomes too great, throttles the admission to the pump E
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed I declare that what
I claim is
The construction of gas motor engine substantially as herein described and
illustrated by the drawings.