IMPROVEMENTS IN GAB ENGINES to be as follows:-
Year: 1885

page_text: I, HENRY THOMAS DAWSON of Salcombe in the County of Devon Gentleman
do hereby declare the nature of my invention for "IMPROVEMENTS IN GAB
ENGINES to be as follows:-
"
This invention has for its object improvements in gas engines and is applicable
especially to gas engines for driving sewing machines and for other such like
purposes-Gas engines of larger size may however be constructed in accordance
with the invention.
In the improved gas engine the air and gas are admitted by separate apertures
and they are ignited before a complete admixture is effected.
I employ a cylinder with a piston within it. The piston is elongated and fits
the outer cylinder over the whole length of the piston. The piston contains
within it a cylindrical chamber in which the combustion of the gas takes place.
This chamber is closed in front and open in rear. At the rear end of the outer
cylinder there is a cover and this carries a third cylinder projecting inwards and
having its end in proximity to the closed end of the piston when this is at the
inner end of its stroke. There are thus three concentric cylinders, one within the
other-the outer fixed cylinder, the moving cylinder forming part of the piston
and fitting and sliding within the outer cylinder, and the cylinder attached to the
cover which enters within the second cylinder but does not fit it closely. The
combustion chamber is the variable space within the moving cylinder between its
closed end and the fore part of the cover. The combustion taking place within
the moving chamber the fire does not reach the frictional surfaces to which
lubrication is applied. The piston is furnished with a connecting rod which is
connected with it in front by a ball or other universal joint. The connecting rod
transmits the movement of the piston to a crank pin carried by a shaft, which is
also provided with a fly wheel.
The admission of gas and air to the combustion chamber and the expulsion of
the products of combustion take place by holes or passages formed through the
sides of the stationary outer cylinder and, the moving cylinder. One pair or set
of holes or passages serves for the admission of gas a second for that of air,
a third for firing the charge and a fourth for the expulsion of the products of
combustion.

page_text: When the piston is at the inner end of its stroke, a hole or passage in the side
of the moving cylinder coincides with another hole or passage in the outer cylinder
to which gas is supplied by means of a pipe-another hole in the moving cylinder
coincides also at this time with a hole in the outer cylinder by which air enters.
When a portion of the stroke has been completed these holes or passages cease to
Immediately
coincide and the admission of gas and air consequently ceases.
afterwards another hole in the moving cylinder arrives at a position in which it
coincides with a vent in the side of the outer cylinder, where a flame is kept
constantly burning. The charge of gas and air in the moving cylinder is then
ignited, and the, combustion causes an expansion which drives the piston to the
end of its stroke. During the return stroke the admission and emission passages
in the two cylinders do not again come together because a partial rotary motion_is
imparted to the piston and moving cylinder by means bereinafter described. In
the return stroke however the exhaust apertures in the moving cylinder coincide
with a corresponding passage in the outer cylinder, and the products of combustion
are free to escape. The exhaust is open throughout the whole of the return
stroke, the exit in the moving cylinder taking the form of a series of holes which
in close succession are brought to correspond with the exit passage upon the outer
cylinder.
It will thus be seen that the moving cylinder serves also as the valve by which
the flow of the gas, air, and products of combustion are controlled. The piston
may receive the necessary axial movement very conveniently by means of an arm
upon the connecting rod at a short distance from the end connected with the piston
-this arm enters between two lugs upon the piston near its periphery, it carries a
cylinder or ball which works between these lugs and ensures steady movement.
The angular motion which the connecting rod receives from the crank thus causes
partial rotation of the piston such that, as already explained, the holes in the sides
of the moving cylinder take a different path during the return stroke from that
over which they travel during the outward or effective stroke.
I provide an air valve on the cylinder cover which opens to admit air into the
cylinder during the earlier part of the stroke but closes when the gases are fired
to prevent an escape outwards. The valve should be so constructed as to give a
free admission whilst rising only a very short distance from its seat, as it. is
necessary that it should close very promptly when the gases are fired-this valve
may conveniently consist of a series of concentric rings all of a piece' and connected
together by radial ribs-the cylinder cover is similarly formed, and the apertures
between the rings of the cover are closed by the rings of the valve. The valve is
held up to its seat by a spring.
of
:
The gas is supplied to the engine from a flexible bag contained in a cavity in
the base where the bag is safe from injury. The gas enters the bag from an
ordinary gas pipe past a cock which can be closed to cut off the supply of gas
when desired. On leaving the bag the gas enters a valve box in which there is a
small stop valve. This valve when upon its seat will still allow a small quantity
gas to pass sufficient to keep the engine in movement at a convenient rate when
unloaded. When the work is thrown upon the engine this stop valve is at the
same time lifted; this is effected by means of a lever operating upon the valve
and connected also. with the starting and stopping gear of the machine which the
gas engine is adapted to drive. Or the engine may drive through dynamometer
mechanism and this may be made to open the gas valve during its movement
resulting from the application of the load. Thus on the machine being started the
engine receives a full supply of gas, and when the machine is stopped the gas
supply to the engine is checked and only so much passes as is necessary to keep
the motor in imovement. There is also a tap to regulate the gas after it has passe
the stop valve and this tap serves to fix the maximum speed of the engine.
I provide a burner for the purpose of warming the cylinders before starting, a
the engine does not run well when cold, especially when solid. lubricants are used
This burner I supply with gas from the same valve box, and the regulating ta

page_text: which controls the maximum flow of gas will serve also to regulate the supply of
gas to this burner, the flame from the burner playing on the outer cylinder soon
raises the apparatus to a suitable working temperature. The engine works best
when the cylinders are heated to about 300 degrees, and to prevent the temperature
much exceeding this when the engine is put to continuous work I provide a small
water cistern in connection with the frame. The frame conducts away the surplus
heat and communicates it to the water.
The ignition of the gas within the cylinder is effected by means of a small gas
flame contained within a tube which protects it from draughts. This flame plays
against a small perforated earthenware button let into the side of the outer
cylinder. This perferation forms the firing vent. The ignition of the charge takes
place when a hole in the side of the moving cylinder comes to coincide with the
vent. The slight indraught then carries the flame through the vent into the
cylinder and the charge is ignited. I form the vent in earthenware or like non-
conducting material in order that the flame in passing through may not be so far
cooled as to cause the ignition to fail. I supply the igniting flame by a pipe
direct from the gas supply pipe, and I also provide a second flame immediately
above the igniting flame, so that if the first should in any case be blown out it
may be immediately lighted again and ready to act on the next stroke of the
engine.
For domestic purposes the gas engine may be enclosed in a box lined with felt
or other non-conducting material to deaden any noise which may result from its
working.
A tube may be provided to supply cool air from outside to the large air valve.
In order to ensure an effective ignition of the charge I provide a deflecting plate
upon the piston-I usually so arrange this plate as to direct the gas entering the
cylinder away from the igniting aperture in order that the ignition may not fail
from an excess of gas being found at this point; it may also in some cases be
required to deflect the air from the igniting aperture.
The lubrication of the piston may be effected by means of an ordinary siphon
lubricator mounted on the side of the outer cylinder in such a manner that any
gases leaking past the piston are able to find vent otherwise than by the tube of
the lubricator, so that the wick of the lubricator may not be displaced by gas
pressure.
Solid paraffin is a suitable lubricant.

page_text: I, HENRY THOMAS DAWSON of Salcombe in the County of Devon Gentleman 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 has for its object engines to be operated by the combustion of gas
or gaseous fuel and is applicable especially to engines to work at a high speed.
In the improved gas engine the air and gas are admitted by separate apertures
and they are ignited before a complete admixture is effected. Such complete
admixture requiring time, is not allowed to take place by reason of the arrange-
ment of the apertures and the speed at which the engine is driven.
I employ a cylinder with a piston within it. The piston is elongated and fits
the outer cylinder over the whole length of the piston. The piston contains
within it a cylindrical chamber in which the combustion of the gas takes place.
This chamber is closed in front and open in rear. At the rear end of the outer
cylinder there is a cover and this carries a third cylinder projecting inwards and
having its end in proximity to the closed end of the piston when this is at the
inner end of its stroke. There are thus three concentric cylinders one within the
other-the outer fixed cylinder the moving cylinder forming part of the piston and
fitting and sliding within the outer cylinder and the cylinder attached to the cover
which projects within the second cylinder but does not fit it closely. The com-
bustion chamber is the variable space within the moving cylinder between its
closed end and the fore part of the cover. The combustion taking place withiu
the moving chamber the fire does not to any extent reach the frictional surfaces to
which lubrication is applied. The piston is furnished with a connecting rod which
is connected with it in front by a ball or other universal joint. The connecting
rod transmits the movement of the piston to a crank pin carried by a shaft, which
is also provided with a fly wheel.
The admission of gas and air to the combustion chamber and the expulsion of
the products of combustion take place by holes or passages formed through the
sides of the stationary outer cylinder and the moving cylinder. One pair or set of
holes or passages serves for the admission of gas or gas and air a second for that
of air alone, a third for firing the charge and a fourth for the expulsion of the
products of combustion.
When the piston is at the inner end of its stroke a hole or passage in the side of
the moving cylinder coincides with another hole or passage in the outer cylinder
to which gas or gas and air is supplied by means of a pipe or pipes. Auother
hole in the moving cylinder coincides also at this time with a hole in the opposite
side of the outer cylinder by which air enters. When a portion of the stroke has
been completed these holes or passages cease to coincide and the admission of
gas and air by these ports consequently ceases. Immediately another hole in the
moving cylinder arrives at a position in which it coincides with a vent in the

page_text: side of the outer cylinder where a flame is kept constantly burning. The charge
of gas and air in the moving cylinder is then ignited and the combustion causes an
expansion which drives the piston to the end of its stroke, During the return
stroke the admission and ignition passages in the two cylinders do not again come
together because a partial rotary motion is imparted to the piston and moving
cylinder by means hereinafter described. In the return stroke however the
exhaust apertures in the moving cylinder coincide with a corresponding passage in
the outer cylinder and the products of combustion are free to escape. The exhaust
is open throughout the whole of the return stroke, the exit in the moving cylinder
taking the form of a series of holes which in close succession are brought to
correspond with the exit passage upon the outer cylinder,
It will thus be seen that the moving cylinder serves also as the valve by which
the flow of the gas, air and products of combustion are controlled. The piston
may receive the necessary rotative axial movement very conveniently by means of
an arm upon the connecting rod at a short distance from the end connected with
the piston this arm enters between two lugs upon the piston near its periphery
it carries a cylinder or ball which works between these lugs and ensures steady
movement, The angular motion which the connecting rod receives from the
crank thus causes partial rotation or oscillation of the piston such that as already
explained, the holes in the sides of the moving cylinder take a different path
during the return stroke from that over which they travel during the outward or
effective stroke.
I provide an air valve on the cylinder cover which opens to admit air into the
cylinder both while the admission ports are open and after they have closed, but
it closes when the gases are fired to prevent an escape outwards. The object of
this valve is to reduce the suction upon the igniting flame, as strong suction is
fatal to rapid action. The valve should be so constructed as to give a free
admission whilst rising only a very short distance from its seat as it is necessary
that it should close very promptly when the gases are fired-this valve may
conveniently consists of a series of concentric rings all of a piece and connected
together by radial ribs the cylinder cover is similarly formed and the aperturos
between the rings of the cover are closed by the rings of the valve. The valve is
held up to its seat by a light spring.
The gas is supplied to the engine from a flexible bag contained in a cavity in
the base where the bag is safe from injury. The gas enters the bag from an
ordinary gas pipe past a cock which can be closed to cut off the supply of gas
when desired. On leaving the bag the gas enters a valve box in which there is a
small stop valve. This valve when upon its seat will still allow a small quantity
of gas to pass
sufficient to keep the engine in movement at a convenient rate when
unloaded. When the work is thrown upon the engine this stop valve is at the
same time lifted; this is effected by means of a lever operating upon the valve
and connected also with the starting and stopping gear of the machine which the
gas engine is adapted to drive. Thus on the machine being started the engine
receives a full supply of gas and when the machine is stopped the gas supply to
the engine is checked and only so much passes as is necessary to keep the motor
in movement. There is also a tap to regulate the gas after it has passed the stop
valve and this tap serves to fix the maximum speed of the engine.
I provide a burner for the purpose of warming the cylinders before starting as
the engine does not run well when cold especially when solid lubricants are used.
This burner I supply with gas from the same valve box, and the regulating tap
which controls the maximum flow of gas will serve also to regulate the supply of
gas to this burner, the flame from the burner playing on the outer cylinder soon
raises the apparatus to a suitable working temperature. The engine works best
when the cylinders are heated to about 300 degrees and to prevent the temperature
much exceeding this when the engine is put to continuous work I provide a small
water cistern in connection with the frame. The frame conducts away the surplus.
heat and communicates it to the water.
'

page_text: The ignition of the gas within the cylinder is effected by means of a small gas
Hame contained within a tube which protects it from draughts. This flame plays
against a small perforated earthenware button let into the side of the outer
cylinder. This perforation forins the firing vent.
:
The ignition of the charge takes place when a hole in the side of the moving
cylinder comes to coincide with the vent. The slight indraught then carries the
flame through the vent into the cylinder and the charge is iguited. 'I form the
vent in earthenware or like non-conducting material in order that the flame iu
passing through may not be so far cooled as to cause the ignition to fail. I supply
the igniting fame by a pipe direct from the gas supply pipe, and I also provide a
second flame immediately above the igniting flame so that if the first should in
any case be blown out it may be immediately lighted again and ready to act on
the next stroke of the engine.
+
For domestic purposes the gas engine may be enclosed in a box lined with felt
or other non-conducting material to deaden any noise which may result from its
working.
A tube may be provided to supply cool air from outside to the large air valve.
In order to ensure an effective ignition of the charge I provide a deflecting plate
upon the piston I usually so arrange this plate as to direct the gas entering the
cylinder away from the igniting aperture in order that the ignition may not fail
from an excess of gas being found at this point, it may also in some cases be
required to deflect the air from the ignition aperture.
>
The lubrication of the piston may be effected by means of an ordinary siphon
lubricator mounted on the side of the outer cylinder in such a manner that any
gases leaking past the piston are able to find vent otherwise than by the tube of
the lubricator so that the wick of the lubricator may not be displaced by gas
.pressure.
Solid paraffin is a suitable lubricant.
In order that my said invention may be most fully understood and readily
carried into effect I will proceed to describe the drawings hereunto annexed.
Figure 1 is a longitudinal section of the gas engine.
Figures 2, 3, 4 and 5 are transverse sections.
Figure 6 is an elevation and Figure 7 is a longitudinal section of the piston and
its connecting rod.
Figure 8 represents the surface of the piston developed and shows the ports
therein.
Figure 9 represents a development of the inner surface of the cylinder.
Figure 10 is a side elevation, Figure 10% an end elevation and Figure 11 a
longitudinal section of the cylinder cover with the hollow cylindrical projection
forming a part thereof and also the valve which this part carries.
Figures 12 and 13 show the burner by which the ignition is effected with its
chimney and relighting jet.
A is the main cylinder fixed to the frame of the engine. B is the piston, it is
of cylindrical form and partly hollow, it works gas tight within the cylinder A,
between its surface, and that of the cylinder paraffin or other lubricant is applied.
C is a connecting rod, a ball and socket joint connects it at one end with the
piston, and at the other end it is jointed to a crank pin D¹ on the face of the
disc D³ on the main shaft D of the engine on which a fly wheel D is also carried.
There is an arm C' projecting from the side of the connecting rod, it terminates
in a stud on which the globular roller C is mounted so as to be able to turn freely,
and it can also travel endwise along the stud, this roller is received between two
jaws B B attached to the piston B. From this construction it results that the
piston in moving to and fro within, the cylinder also partially rotates. E is the
end cover of the cylinder A and E is the hollow cylindrical projection upon it
entering within the interior of the hollow piston B. The end of the projection E'
and the piston B with its hollow cylindrical sides enclose between them the
combustion chamber or space in which the gas is burned. In the end of the

page_text: projection a series of annular slits are formed as is clearly shown by Figure 11
and these are closed by a plate or valve E in which similar slits are formed and
which by a light spring is held up to the surface of E¹ whenever however the
pressure within the combustion chamber falls below atmospheric pressure, as it
does when the ports are closing the valve lifts slightly from its seat and allows air
to enter.
The admission of air by this valve serves several purposes, it furnishes some
portion of the charge for use in the combustion chamber but this is not its
main object for another inlet is provided to do this and it is opened and closed
mechanically at proper times. The air admitted by this valve also lessens the
resistance against which the engine works during the outstroke, and before the
charge is fired; it cools the cylinder and finally its main object is to prevent too
great an inrush of air taking place at the firing port which would at high speed
interfere with the ignition of the charge when the firing port is opened. This
light suction is essential to high speed in the engine and is best attained as herein
shown by means of a valve of large area in free communication with the cylinder
and operating independently of the main admission of air to consume the gas of
the charge.
The gas enters the combustion chamber from a bag by the passage A¹ in the
side of the cylinder A at the time when this passage corresponds with another
passage B³ in the side of the cylindrical piston B.
A valve is shown in connection with the gas supply passage A¹ it can be opened
or closed by a treadle or in other convenient manner.
In place of admitting gas alone by these passages A¹ and B³ gas and air may be
supplied. The combustion chamber is also simultaneously supplied with air alone
through the passage A in the cylinder A and the passage B³ in the cylindrical
piston B. The section Figure 4 shows the parts in the position, which they occupy
as the charge enters the combustion chamber. It is a feature in this engine that
it requires no separate gas inlet, exhaust, and ignition valves.
F is the burner by which the ignition is effected it supplies simply a small gas
flame which plays continuously against a perforated earthenware button fixed into
an aperture at-A³ in the side of the cylinder A, above the igniting burner a small
gas flame is kept constantly burning at F1 to relight the igniting flame, if, as may
sometimes occur, it should be blown out. B is the igniting aperture in the side
of the cylindrical piston B as soon as this comes to coincide with the aperture A³
the charge in the combustion chamber is fired.
Figure 2 shows the parts in this position, the piston then receives an impulse
forward which is communicated to the crank and fly wheel. The piston now passes
to the end of its stroke and returns, during the return of the piston the products of
combustion are in great part discharged out of the cylinder. The passages B6 in
the piston B come in position to coincide with the exit passage A' in the side of
the cylinder A.
Figure 3 shows the parts when during the return stroke the passages are open
for the escape of the products of combustion.
G is a water cistern formed in connection with the frame of the engine it is
employed in order to prevent the parts from becoming overheated but as already
stated the engine works more advantageously when fairly hot than when cold.
His a gas tap which serves to control the supply of gas to the engine also when
the engine is not at work it can be used to turn gas on to the burner I which is
for warming up the cylinder before starting. The supply of gas to the engine is
drawn as is usual from a flexible bag by which greater uniformity is obtainable than
when the gas is taken from the gas supply pipe direct. J is a valve operated by a
lever J and a rod J leading to a treadle; the same treadle also operates a friction
clutch by which the machine to be driven is connected with the engine. When the
machine is unclutched the valve J is closed so as only to pass just enough gas to
keep the engine in motion, When the treadle is released the clutch drops in and
the valve J is opened by a spring,

page_text: 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
1. A gas engine in which the charges are admitted to the combustion chamber
fired when only partially mixed and the products of combustion discharged
through ports in the side of the cylinder and in the piston.
.2. A gas engine in which the charges are admitted to the combustion chamber
and the products of combustion discharged through ports in the side of the
cylinder and in the piston, such piston as it moves to and fro within the cylinder
being also caused to partially rotate so that in the out stroke of the piston the
supply ports and also the firing ports are brought at the proper times to coincide
whilst in the return stroke the coincidence of the exit ports occurs.
-
3. A gas engine having in addition to an air inlet which is opened and closed
mechanically at proper times, an automatic valve of large area for the direct
admission of air to the combustion chamber so as to reduce the suction upon the
igniting flame when the ignition aperture opens thereby admitting of greater
rapidity of ignition and higher speeds in the engine.
4. A gas engine provided with a regulating gas valve, also with a clutch or liké
gear which throws the work on or off the engine and with mechanism actuating
these simultaneously so that while always running the engine gets more gas when
the work is put on and vice versa.