Improvements in Gas Engines.
Year: 1890

page_text: Date of Application, 26th Apr., 1890
Complete Specification Left, 26th Jan., 1891-Accepted, 25th Apr., 1891
PROVISIONAL SPECIFICATION.
Improvements in Gas Engines.
I, HENRY THOMAS DAWSON, of Salcombe, in the County of Devon, Gentleman,
do hereby declare the nature of this invention to be as follows:-
This invention has for its object improvements in gas engines.
1
The improved engine has four stages in its cycle of action; that is to say, (1) the
cylinder takes its charge during the outward movement of the piston--(2) the charge
is compressed by the return of the piston-(3) the charge is fired and the effective
outward movement of the piston takes place, and (4) the products of combustion
are discharged whilst the piston returns.
This cycle is attained in my gas engine without the use of valves or slides, the
piston itself operating as valves. This engine has a piston which besides recipro-
cating entirely revolves once for each cycle of the engine. The piston is practically
a tube about twice the length of the stroke, fitting well to the cylinder in which it
works.
I sometimes fit the cylinder with rings which are kept out of contact with the
piston by a wedge or lever arrangement worked by a cam so that the rings give an
intermittent pressure upon the piston, lasting while the gaseous pressure is high
and leaving the piston free from the friction of the rings at all other times. The
piston tube is closed by a diaphragm situate at about the fourth of its length from
the outer end of the tube. The cylinder is about thrice as long as the stroke; it
has long ports about its centre part. These ports extend spirally for about the
length of the stroke or rather less. The connecting rod at its outer end embraces
the crank pin and at its inner end terminates in a ball which is received into a
socket upon the diaphragm of the piston so that the piston may revolve freely
while it also reciprocates. Upon the connecting rod there is a sleeve carrying a
bevel wheel at its outer end which gears in a pinion fixed upon the crank pin. At
the inner end of the sleeve is an arm connected by a link with the piston. There
are ball joints at the ends of the link.
The piston has an aperture through its tubular part about the centre of its length
serving for all the purposes of admission ignition and exhaust. This aperture is
carried successively over the several ports in the cylinder.
The cover or end of the cylinder is made to extend into the tubular piston so as
The cover contains
to leave only a proper space for compressing the charge.
water, and water passages are formed upon the cylinder, the whole being in
connection with a cistern or other water supply.
The inner face of the piston diaphragm is covered with asbestos or other non-
conducting material firmly secured, to protect it from the burning charges. In
order to govern the speed of the engine a gas and air valve is fitted upon the
cylinder outside the admission port. This valve closes both gas and air passages at
once, the passages being conveniently concentric, and the valve is so constructed as
to pass nearly constant proportions of gas and air at the different lifts allowed to
the valve. The governor limits or prevents the rise of the valve when the engine
attains its proper speed. The control of the governor over the gas and air valve is
obtained by moving a wedge or other stop over the spindle of the said valve so as
to limit or stop its rise. If the governor is arranged to stop, or hold the valve
upon its seat, I construct the valve so as still to admit some air to reduce the vacuum
in the cylinder.
Ignition is given by means of a heated small thin tube or capsule enclosed in a
small furnace lined with refractory non-conducting material. The outer end of the

page_text: tube is closed. The ignition tube.at its end'.next the cylinder is fitted into a plate
or washer and this is reduced in thickness around the tube so as to stop the
conduction of heat from the tube as much as possible. A current of mixed gas
and air is forced into the furnace close to the cylinder through a wire gauge or
otherwise so as to give a strong combustion in the furnace. The heat is kept from
the cylinder by non-conducting material in the furnace around the ignition tube
where it joins the cylinder. A small passage is provided leading from the inner
end of the ignition tube to the open air for clearing the products of combustion
which otherwise might interfere with the ignition. This clearing passage may be
closed upon explosion by an automatic valve, or the passage may lead to the
cylinder bore and a port in the piston tube outside its diaphragm may be brought
to coincide with this passage at the proper moment.
The jet of air for forcing the furnace is supplied by a small air pump worked by
the engine from an eccentric acting on a slotted lever, so arranged that by shifting
the fulcrum the stroke may be varied. Or the pump may be worked by hand
either for starting the engine or while it is running. The air is heated before it
feeds the flame by waste heat from the furnace.
This improved construction and arrangement of igniting apparatus effects a con-
siderable saving of time and gas in heating the tube to start the engine and maintaining
the necessary heat. This results from placing the open end of the tube near to the
charge to be fired, the heat from which being imparted to the interior of the tube,
besides that given to its exterior by the hot blast, cause greater intensity and
rapidity of ignition necessary for high speeds.
The action of the engine is as follows:-
1. During the first outward stroke the port in the piston coincides with the
cylinder admission port when gas and air fill the cylinder. At the end of the out-
stroke the pisten by a further revolution cuts off the admission. 2. Compression
takes place during the whole of the next instroke. 3. At or immediately before
the commencement of the next outstroke the movement of the piston opens the
port therein to the ignition tube; explosion ensues and work is done during the
whole of the outstroke. 4. At or immediately before the end of the outstroke
the port in the piston opens to the exhaust port in the cylinder and remains open
during the whole of the return stroke.
In order to render the ignition more certain I adapt a short tube to the port
within the piston. Through this tube the cylinder receives its charge. The tube
retains a portion of the charge uncontaminated by products of combustion and
this is carried by the piston to the ignition tube. The charge being then under
pressure gas and air enters the ignition port driving before it through the previously-
imentioned clearing passage any products of combustion which may be contained
therein. The gas and air when they come against the heated surface of the tube
are ignited thereby.
I sometimes provide a packing ring upon the piston around the port and this
when internal pressure is present makes a gas tight joint against the walls of the
cylinder.
I also cover the wearing surfaces of the pistons with steel, nickel or other suitable
material applied preferably by electro deposition, for résisting and making up wear
of these surfaces.
Sometimes arrange six stages in the engine cycle in which case after the
products of combustion are expelled from the cylinder and before the next charge
is admitted air is drawn in and at the return stroke is again expelled. Thus most
of the products of combustion are removed from the cylinder before a new charge
enters.
For lubrication I provide a small oil vessel having a wick which touches the
piston each stroke, and the oil is maintained at a constant level at the point of
supply by a fountain arrangement. This apparatus only delivers oil while the
engine is running and is automatic. Passages are formed in the crank pin and
webs so that oil from the main bearings keeps the crank lubricated. Passages

page_text: in the main bearings or in the shaft lead the oil towards the crank and centrifugal
force drives it to the crank pin from depressions upon the cranks around the main
shaft.
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HENRY T. DAWSON.
COMPLETE SPECIFICATION.
Improvements in Gas Engines.
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 improvements in gas engines.
The improved engine has four stages in its cycle of action; that is to say (1)
the cylinder takes its charge during the outward movement of the piston, (2) the
charge is compressed by the return of the piston, (3) the charge is fired and the
effective outward movement of the piston takes place, and (4) the products of
combustion are discharged whilst the piston returns.
This cycle is attained in my gas engine without the use of valves or slides, the
piston itself operating as valves and besides reciprocating it entirely revolves once
for each cycle of the engine. In some cases two stages are added to the cycle
making six in all as hereinafter described.
An engine constructed in accordance with my invention is shown by the annexed
drawings.
Figure 1 is a side elevation. Figure 2 is an end elevation thereof and Figure 3
is a vertical section of the cylinder and piston and shows the connecting rod,
crank pin and some other parts. Figure 4 is an horizontal section. The Figures 5
to 13 show separate parts mostly to a larger scale. The remaining figures show
modifications.
In Figures 1 to 4 a is the cylinder, it is water jacketed to keep it cool. The
cylinder contains a piston 6 which by a connecting rode drives a crank on an
axis d. is a fly wheel and a belt pulley. is an eccentric on the axis
actuating an air pump e; the purpose served by this air pump is hereinafter
explained. is an elastic bag which receives the air from the pump. is a
casing containing a governor valve which opens for the admission of air and gas
to the cylinder. is an elastic bag serving to maintain an uniform gas pressure.
g is a governor controlling the gas and air supply. is a stop cock on the gas
supply pipe. is the ignition apparatus. is the exhaust or outlet from the
cylinder.
The piston is tubular and of about twice the length of the stroke, it fits well
to the cylinder in which it works. The piston tube 6 is closed by a diaphragm 2
situate at about the fourth of its length from the outer end of the tube. The
cylinder is about thrice as long as the stroke; it has long ports about its centre
part. These ports extend spirally in the cylinder walls for about the length of
the stroke or rather less.
Figure 5 shows to a larger scale the interior of the cylinder developed. The
full circles show the ports or passages formed in it. The ports a' al a a¹ in this
figure serve for the admission of air and gas, they all communicate with a passage
formed partly in the walls of the cylinder and partly by the ports cover and form
one clongated port as seen in Figure 6. They also communicate with the governor
valve by which the admission is controlled.
a² a² a² a² in Figure 5 are the exhaust passages, they also all communicate with
a passage formed partly in the cylinder walls and partly in the port cover and
operate as one passage obliquely cut through the cylinder. a³ in Figure 5 is the
firing port.

page_text: The connecting rod as is shown in Figures 1, 2 and 3 at its outer end embraces
the crank pin and at its inner end terminates in a ball e' which is received into
a socket upon the diaphragm of the piston so that the piston may revolve freely
while it also reciprocates. Upon the connecting rod there is a sleeve e carrying
a bevel wheel at its outer end which gears in a pinion d* fixed upon the crank
pin. At the inner end of the sleeve c² is an arm * connected by a link with the
piston as is seen in Figure 4. There are ball joints at the ends of the link.
Other arrangements of gear for rotating the piston may be provided and are
hereinafter described.
The piston has an aperture or port through its tubular part about the centre of
its length serving for all the purposes of admission, ignition and exhaust. This
aperture is shown in Figure 11 and in Figure 5 is indicated in dotted lines; it
is marked *; it is carried by the movement of the piston successively over the
several ports in the cylinder.
The aperture x is shown in Figure 5 in the position it occupies when the piston
is at the inner end of its stroke and the engine at the commencement of the cycle.
The full lines in Figure 5 represent the positions of the ends of the piston
tube when the piston is at the inner end of its stroke. The distance between the
dotted lines is the length of the stroke. In the outstroke the piston port *
ascends and passes in succession over the cylinder ports a¹ a¹ a' a' and during this
time the charge is taken into the cylinder through the governor valve.
Throughout the whole of the next instroke of the piston the port * is closed;
it does not pass over any of the ports in the cylinder and the charge is compressed.
At the commencement of the following outstroke the piston port 6x passes by the
cylinder port a (see also Figures 8 and 9) and the charge is fired. Afterwards
throughout the outstroke the port 6x is closed until at the turn of the stroke the
piston port comes to communicate with the first of the exhaust ports a² a² a² a²
and it remains open to these ports throughout the instroke and until the end of the
cycle.
The cover or lower end of the cylinder a is made to extend into the tubular
piston as is seen in Figure 3 so as to leave only a proper space for compressing
the charge. The cover contains water, and water passages are formed upon the
cylinder, the whole being in connection with a cistern or other water supply. The
water is admitted at the bottom of the jacket and overflows at the top.
The inner face of the piston diaphragm 2 is covered with asbestos or other non-
conducting material 3 firmly secured by means of a thin sheet metal cup 6' and
bolts as indicated in Figure 3.
This covering protects the piston diaphragm from the burning charges. In order
to govern the speed of the engine a gas and air valve shown by Figures 6 and 7 is
fitted upon the cylinder outside the admission port. is the valve casing. fis
the gas supply pipe. is the valve; when down it closes both the gas inlet at /3
and the air inlets at . The suction of the piston lifts the valve and then air and
gas both enter the cylinder, some of the gas passing from the annular groove f³
through perforations in the valve. is a guide stem fixed on the valve. Thus
the valve closes both gas and air passages at once, the passages being conveniently
concentric, and the valve is so constructed by proportioning the aforesaid
perforations as to pass nearly constant proportions of gas and air at the different
lifts allowed to the valve. The governor g limits or prevents the rise of the valve
when the engine attains its proper speed. The control of the governor over the
gas and air valve is obtained by moving a stop over the spindle of the said valve
so as to limit or stop its rise. The divergence of the governor weights gl acts
through the lever, rod and toggle links to lower the stop and finally it holds
the valve upon its seat. In some cases I so construct the valve that it still admits
some air when the gas passage is closed. This serves to reduce the vacuum in the
cylinder and is effected by making the valve disc covering the air ports of thin
metal, leather or other flexible material.
Ignition is given by means of apparatus shown at Figures 8 and 9. Figure 8 is

page_text: an horizontal section through the cylinder and the ignition. apparatus and Figure 9
is a longitudinal section. I provide a small metal or porcelain tube or capsule
enclosed in a furnace lined with asbestos or other refractory non-conducting
material. The outer end of the tube is closed and at its end next the cylinder
it is fitted into a plate or washer and this is reduced in thickness around the
tube so as to stop the conduction of heat from the tube as much as possible. A
current of mixed gas and air is forced into the furnace so as to give a strong
combustion in the furnace. The gas is supplied by a passage and air is admitted
by the nozzle ». The heat resulting from the combustion in the furnace is to a
great extent kept from the cylinder by non-conducting material in the furnace and
around the ignition tube where it joins the cylinder. A small passage is provided
leading from the inner end of the ignition tube to the open air for clearing the
products of combustion which otherwise might interfere with the ignition. This
clearing passage may be closed upon explosion by an automatic valve, or as is
shown in Figure 9 the passage may lead to the cylinder bore; a port in the
piston tube outside its diaphragm is in this case brought to coincide with the
passage at the proper moment.
The air pumpe which supplies the jet of air for forcing the furnace is shown in
section at Figure 10. e¹ is a reciprocating plunger in the cylinder e. is the
inlet valve and is the outlet. This air pump is worked by the engine from an
eccentric acting on a slotted lever e¹ (see Figure 2) so arranged that by shifting
the position of the lever in relation to the fulcrum e the stroke may be varied. Or
the pump may be worked by hand either for starting the engine or while it is
running to admit of this the lever may be disengaged entirely from the fulcrum e
upon which it is held only by the pressure of a spring plunger e
;
The spring plunger yields to allow the lever being withdrawn laterally when it
is desired to work the air pump by hand. The air is heated before it feeds the
flame by waste heat from the furnace, which it absorbs whilst traversing the coiled
pipe contained in the outlet from the furnace.
This improved construction and arrangement of igniting apparatus effects a
considerable saving of time and gas in heating the ignition tube to start the engine
and maintaining the necessary heat. This results from placing the open end of the
tube near to the charge to be fired. The hot blast keeps the tube in a state of
incandescence and causes a great intensity and rapidity of ignition, necessary for
high speeds."
In order to render the ignition more certain I adapt a short tube xx to the port,
within the piston as is shewn in section at Figure 11. Through this tube the
cylinder receives its charge. The tube retains a portion of the incoming charge
practically free from products of combustion some of which remain in the cylinder
from the previous stroke. The pure explosive mixture contained in the tube ** is
carried by the piston to the ignition tube. The charge being then under pressure
this pure gaseous mixture enters the ignition port driving before it through the
previously mentioned clearing passage any products of combustion which may
be contained therein. The combustible charge then comes in contact with the
interior surface of the incandescent tube and is ignited thereby.
I sometimes provide a packing ring upon the piston around the port and this
when internal pressure is present makes a gas tight joint against the walls of the
cylinder. This packing ring is seen in Figure 11 and a portion of it is drawn to a
larger scale at Figure 12 it is marked /,.
Figure 13 is a section of the gas cock ; it is provided with two plugs h¹ and h²
one within the other and both are provided with handles by which they can be
turned the first regulates the passage of gas to the cylinder and the latter the
supply of gas to the furnace of the igniter.
I make suitable provision for the lubrication of the working parts.
When porcelain or refractory earthenware ignition tubes or capsules are
employed there is danger of fracture and destruction of the tube from a too rapid
heating.

page_text: To avoid this inconvenience I provide for the slow and gradual heating of the
tube before the blast is applied. Figures 14 and 15 are similar to the Figures 8
and 9 previously described with this addition. ix are openings through the exterior
walls of my furnace. is a branch leading from the gas supply and are burners
emitting gas jets playing upon the tube within the furnace. To heat the furnace
the burners are lighted and the flames are regulated just to enter within the
furnace. After two or three minutes the flames are increased and continued until a
high temperature is reached-then the heating appliances already described arc
brought into operation and the engine is started.
Sometimes especially for large engines i employ a more elaborate form of ignition
apparatus which I will presently describe.
Sometimes I arrange six stages in the engine cycle in which case after the
products of combustion are expelled from the cylinder and before the next charge
is admitted air is drawn in and at the return stroke is again expelled. Thus most
of the products of combustion are removed from the cylinder before a new charge
enters. To effect this the gear for rotating the piston is made three to one and
additional ports are provided in the cylinder.
Sometimes in large engines I make the gear four to one and duplicate the ports,
in this way I obtain two cycles for one rotation of the piston.
Other ways of imparting the necessary rotation to the piston by means of the
crank and connecting rod are shewn by Figures 16, 17, 18 and 19. Figure 16 is
an end elevation and Figure 17 is a side elevation with a cap removed. 7 is
the crank pin, it has a worm cut upon it. s is a block upon the crank pin in
which the pin revolves. t is a rod fixed to the blocks and terminating in a
bearing at t is another rod, it is held in the blocks at one end and in the
bearing t¹. near the other end. In this block and bearing the rod u is able
to turn.
The lower end of the rod is connected with and actuates the piston in the
manner already described in respect to Figure 3. is a pinion engaging with the
worm on the crank pin and driven by it at the required speed . one revolution
for two revolutions (or in some cases three or four revolutions) of the crank
shaft.
Figure 18 is a side elevation of another connecting rod suitable for transinitting
rotary motion to the piston. Figure 19 is a section of the same. As before the
crank pin has a worm upon it with which a pinion engages the pinion is carried
upon the head of the connecting rod and has another pinion upon its axis. A
tube surrounds the connecting rod as already described in respect to Figure 3 and
this tube has a pinion upon it which by the aid of the pinions previously mentioned
serves to gear it with the worn on the crank pin. At the lower end of the tube
there is an arm and a link connects the arm with the piston.
Figures 20, 21, 22 and 23 shew a very complete form of ignition apparatus but
otherwise similar to that already described. Figure 20 is a vertical section,
Figure 21 is a section on the line A A in Figure 20. Figure 22 is a section at' B B
in Figure 20 and Figure 23 is an elevation with the cover removed.
vis the body casting of the furnace for heating the ignition tube, it is bolted to
the side of the cylinder a. c is a metal piece fitting into a recess in the cylinder
around the ignition port.
The front part of the piece w slightly projects from the cylinder face and when
the casting e is screwed on, it keeps w firmly on its bevelled seat.
A small space
is left under w to establish communication with the passage . ' are holes
preferably spirally cut as shewn, through the side of w and also through which
is non-conducting and refractory lining material such as asbestos. is a piece of
fine wire gauze around the holes. a is an ignition tube. y is a thin metal tube
lined with asbestos or other refractory material-it is fixed to a covery and studs y²
are arranged upon it; it fits with a bayonet joint into the main casting v.
z is a
Bunsen burner whose flame passes through holes in the casting for more gently
heating the ignition tube. The injector A delivers a supply of gas and air, the gas

page_text: entering and being regulated by the cock A' and air entering by the holes A².
The mixture enters the annular passage A³ and passes through the gauze w³, and
the holes and is burnt in the cavity around the tube the greatest heat being
produced near the holes. The waste heat passes around the tube up the chimney
orifice . B is a small screw valve for regulating the Bunsen .
In starting with an earthenware ignition tube, the liner is partially withdrawn
so as to uncover the holes in the casting . is then lighted and after being in
action till the tube and furnace generally has become fairly warmed up, A¹ is
turned partly on and the blast at A also turned on. The mixture passes through
the passages and the flame runs back to the gauze which prevents it from retreating
further and it consequently burns at and near its intensity is regulated by the
cock A by the force of the blast. When the flame at d is properly burning the
Bunsen may be put out and the lining tube put in the working position as it is
here shewn it is then in proper condition for working the engine. If metal tubes
are used the Bunsen need not be used. Horizontal and inverted engines may be
constructed in accordance with my invention.
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 having a reciprocating and rotating piston serving as a valve
and in which, by the action of the piston first a charge of gas and air is admitted
to the cylinder; then by the return of the piston this charge is compressed;
afterwards at the commencement of the next stroke the compressed charge is fired
and when the piston again returns the products of combustion are expelled from the
cylinder substantially as described.
2. In a gas engine a piston geared with the crank pin and thus rotated con-
tinuously in one direction such piston operating as a valve controlling the admission
of the gaseous charge to the engine; the ignition of the charge and the escape of
the products of combustion substantially as described.
3. A gas engine having a cylinder with spirally arranged ports coinciding with
the track of a port or ports in a reciprocating and continuously revolving piston so
arranged that the piston rerves as a valve for the admission of the gascous charge
to the cylinder and for the exhaust therefrom substantially as described.
4. A gas engine having a cylinder with spirally arranged ports coinciding with
the track of a port or ports in a reciprocating and revolving piston in combination
with a governor controlling a gas and air inlet valve and operating to close or
partially close the valve thereby varying the quantity of the charge whilst the
proportions of gas and air remain approximately constant substantially as
described.
5. A gas engine having an ignition apparatus consisting of a tube or capsule
contained in a furnace chamber and heated externally by the combustion of gas
urged by a blast substantially as described.
6. In combination with the tube or capsule of the ignition apparatus, the vent or
passage by which when the compressed charge is placed in communication with
the ignition apparatus a portion of the charge expels inert gas from the mouth of
the ignition tube or capsule and entering it becomes ignited substantially as
described.
7. A gas engine having a piston fitted with an internally projecting tube or
tubes through which the combustible charge is admitted; such tube also
serving to retain a portion of the entering charge and to carry it to the ignition
port or ports substantially as described.
8. A gas engine having an ignition apparatus consisting of a furnace chamber
lined with refractory nonconducting material partly sunk in the cylinder walls and
a tube or capsule so mounted therein as to lessen as much. as possible conduction to
the walls of the cylinder and heated by the combustion of gas within the furnace
chamber substantially as described.

page_text: 9. A gas engine having a reciprocating and rotating piston serving as a valve
and working with a six stage cycle thus: first by the action of the piston a charge
of gas and air is admitted to the cylinder, second, by the return of the piston this
charge is compressed, third, at the commencement of the next stroke this charge is
fired fourth, when the piston again returns the products of combustion are
expelled, fifth, during the next stroke air is drawn into the cylinder and sixth on
the return of the piston the air together with remaining products of combustion is
ejected substantially as described.
10. A gas engine in which the piston is geared with the crank pin in the manner
shewn by the Figures 1, 3, 15, 16, 17 and 18 so that the piston may rotate
continuously whilst it travels to and fro within the cylinder.
11. A gas engine substantially as described and illustrated by the annexed
drawings.
Dated this 23rd der of Januar 1801
HENRY T. DAWSON.