IMPROVEMENTS IN GAS MOTOR ENGINES
Year: 1883

page_text: LETTERS PATENT to John Dougill of Choir Street, Broughton Lane,.
Manchester in the County Palatine of Lancaster Concretor. for an Invention
of IMPROVEMENTS IN GAS MOTOR ENGINES
PROVISIONAL SPECIFICATION left by the said John Dougill at the Office
of the Commissioners of Patents on the 22nd June 1883.
JOHN DOUGILL of Choir Street Broughton Lane, Manchester, in the County
Palatine of Lancaster Concretor IMPROVEMENTS IN GAS MOTOR ENGINES
The first part of my Invention relates to an improvement in the Slide Valve and
Valve Gear of Motor Engines especially Gas Motor Engines
I construct the Slide Valve, of four parts, namely: the Valve Seat, the Slide, the
Lesser Slide, and the Slide Cover.
The Valve seat contains five ports or passages The first is the port into the
Cylinder, the second and third are ports through which the Gas is introduced
and mixes with the Air previous to entering the Cylinder through the first port,
the fourth is for the admission of Air or Air and Gas as they mix in the cavity
adjoining this port, the fifth is for the exhaust Gasses to pass out from the Cylinder
after combustion,
The Slide differs from the ordinary flat Slide used in Gas Motor. Engines, in
that the middle part is cut away to allow of the insertion of the Stud hereinafter
mentioned and also of the Lesser Slide next hereinafter mentioned, but the Slide
contains the usual chamber formed in one end to carry a Gas flame for igniting the
mixture of Gas and Air as it passes into the cylinder through the first port. The
Slido controls the first port only.
In a portion of the Space cut away from the Slide I insert a Lesser Slide working
upon the same Valve seat as the Slide.
The Lesser Slide operates upon the second, third, fourth and fifth ports which
control the adinission of Gas and mixture of Air and Gas into the Cylinder and
also allows the products of combustion to pass from the Cylinder by way of the
first port through a passage in the body of the Lesser Slide and into the exhaust
pipe through the fifth port.

page_text: The Slide Cover is a flat plate with two ports, the first or smaller port serves to
supply Gas to the Chamber of the Slide wherein the igniting flame burns, the other
port communicates with the chimney formed at the back of the Slide Cover. The
two Slides are drawn backwards and forwards by rods worked by means of canis
upon Crank Shaft suitably timed.
By the above improvements I obtain greater speed in the Engine and a more
gradual expansion of the Gasses, I also reduce the strain upon the working parts
of the Engine and reduce the consumption of Gas.
The second part of the improvement consists of an improved method of holding
the Valve seat and Slide Cover firmly together and yet allow the Slides to be
easily moved backwards and forwards, and consists of a Stud which is inserted
into the Valve seat and through the Slide and Slide Cover. The end of the Stud
which protrudes through the Slide Cover has a thread to which is attached an
adjustable side weighted nut, by means of which I screw up the Slide Cover to the
required position. This prevents the Slides from being forced off their seats by the
pressure from within the Cylinder whilst at the same time allowing them, to move
easily when working, the object being to reduce the friction of the Slides in Motor
Engines by dispensing with springs and like appliances commonly used to keep the
Valve seat, and Slide Cover firmly together.
The Stud may be placed in and through other parts of the Valve, or two or more
Studs may be placed through it, or the Stud or Studs may be placed outside the
Valve at any point, but by preference I insert one Stud through the Valve near
the centre at that point where the space in the larger Slide is cut away for the
purpose of inserting the Stud and admitting of the Slide working without interfering
with the Stud. A modification of the above Stud and nut may be effected by
substituting a Stud with a slot in the end through which a taper pin or wedge
may be put.
The third part of the improvement consists in the application in combination of
the Gas supply Valve generally attached to Gas Engines with Governors and a
Relief Valve which communicates with the Engine Cylinder at-that-end where the
mixture of Gas and Air is situated before ignition
In this combination the object or function of the Relief Valve is to supply Air
to the Cylinder when the Governor closes the Gas supply from the Gas supply.
Valve and reduces the amount of vacuum which would be otherwise formed in the
Cylinder and thus enables the piston to complete its stroke with the least possible
resistance.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent and
of an Order of the Lord Chancellor filed by the said John Dougill in the
Patent Office on the 8th January 1884.
JOHN DOUGILL of Choir Street Broughton Lane in Manchester in the County
Palatine of Lancaster Concertor IMPROVEMENTS IN GAS MOTOR ENGINES
The first part of my invention relates to an improvement of the slide Valves and
valve gear of Gas Motor Engines. The slides are moved backward and forward by
means of rods worked by cams fixed upon the crank shaft. I construct the slide
valve in four parts viz:-the valve seat, the slide, a lesser slide and the slide cover.
The valve scat contains five ports or passages; the first is the port leading into
the Cylinder through which all the gas or gas and air passes to the Cylinder,
and it is found convenient in large size valves to construct this first port with a
double entrance having the appearance of two ports yet it is to be understood to
mean as before stated the first port. The second and third are ports through
which gas alone passes and becomes mixed with the air in or about the passage or
chamber immediately behind the fourth port,-atmospheric air enters this chamber
a little below where the gas enters and the mixture of gas and air then passes
through the fourth port along the space in slide through the first port into the
cylinder.
The slide differs from the ordinary flat slide used in Gas Engines in this
respect that I cut away the middle part so as to allow of the insertion of the
stud hereinafter mentioned and also of the lesser slide-The slide controls the first
port only-The slide contains the usual chamber formed in one end to carry the
gas flame for igniting the mixture of gas and air as it passes into the Cylinder
through the first port. In a portion of the space cut away from the slide I insert
a lesser slide working upon the same valve seat as the slide. This lesser slide
operates upon the second third fourth and fifth ports controlling the admission of
gas and the mixture of gas and air into the Cylinder and allows the products of
combustion to pass from the Cylinder by way of the first port through the
passage in the body of lesser slide and into the exhaust pipe through the fifth port.
The slide cover is a flat plato with two ports, the first or small port serves to
supply gas to the chamber in the slide wherein the igniting flame burns, the other.
port communicates with the chimney formed at the back of the slide cover. In
order to understand the working of the slides and by way of illustration I assume
the piston of the engine to have completed its in stroke, the slides at this time aro
in such a position that the first and fifth ports are open. The lesser slide then
moves outwards closing the exhaust or fifth port in the valve seat and at the same
time uncovers the fourth and third ports for the admission of gas and air. The
piston then moving outwards the air and gas rush along the open space in slide
through the first port into the Cylinder. When the piston has travelled to one
third of its stroke or thereabouts the Slide moves forward cutting off the supply of
gas and air to the Cylinder and at the same time igniting the mixture of gas and
air just supplied to the cylinder-the piston still moving on to complete its stroke.
The lesser slide immediately returns closing the third and fourth ports and opens
the fifth port-The slide returns and opens the first port to allow the products of
combustion to pass out of Cylinder as the piston moves inwards the products then
pass along the open space in the slide through the passage-in the body of the lesser
slide into the fifth port and on through the exhaust pipe

page_text: The second part of my invention, which is applicable to other gas motor engines,
relates to an improved method of keeping the surfaces of the valve seat, slides,
and slide cover in close contact without giving undue pressure and so allowing the
slides to move easily-It consists of a bolt or stud inserted into the valve seat
through the slide and slide cover, The end of the bolt or stud projecting through
the slide cover has a screw thread upon which fits an adjustable side weighted nut,
by means of which I screw up the slide cover to the required pressure, this side
weighted nut being sufficient to prevent the displacement of the valve cover by the
pressure from within the Cylinder and at the same time allowing the slides to
work with freedom thereby reducing the friction of the slides. This stud may
be placed in and through other parts of the valve or two or more studs may be
used but by preference I insert one stud through the valve near the centro at a
point where the space in the slide is cut away. A modification of the above stud
and nut may be effected by substituting a stud with a slot in the end through
which a taper pin or wedge may be placed.
The third part of my invention applies to Gas Motor Engines where the charge
is drawn into the Cylinder during a portion of the stroke only, and having a
governor to regulate the supply of gas (This class of Gas Engine is generally known
as Non-compression gas engines) My invention consists of a combination of the
gas supply valve and a relief valve that supplies air to the Cylinder when the
supply of gas is not required: This relief valve is placed in that end of
the Cylinder where the mixture of gas and air is taken in and at a point in the
Cylinder where the charge is usually ignited. This relief valve is of the class
known as the back pressure valve and performs its duties at a time when owing to
the increased speed of the Engine the gas-is cut off by the governor from the
cylinder and the air supply shut off by the slido. At this juncture the relief valve
supplies the air required so that a vacuum is avoided and the piston is thus enabled
to complete its stroke with freedom.
I will now proceed to describe the accompanying sheet of drawings referenco
being had to the figures and letters marked thereon; like letters indicate the saino
parts throughout the drawings:-
Fig 1 is a front elevation of a gas engine
Fig 2 is a plan of the general arrangement of a gas engine shewing part of my
improvements.
Fig 3 is an elevation of valve seat
Fig 4 is an elevation of slide
Fig 5 is an elevation of losser slide
Fig 6 is an elevation of valve cover
Fig 7 is a section of valve seat, slide, lesser slide and valve cover also section of
the stud and side weighted nut
«, Fig 5 and 7 represents the passage through the body of lesser slide b. Fig 4
represents the part cut away in the slide-c. d Fig G represents the two ports in
slide cover-e. Fig 4 represents chamber in slide in which the lighting flame
burns f. Fig 1. 2. 7 represents the chimney in which the fixed flame burns-
g Fig 1. 2. 7 represents the valve rods-h. Fig 1. 2 represents the cams-i. Fig 7
represents the stud upon which the side weighted nut is screwed-j. Fig 1. 2. 6. 7
represents the one side weighted nut screwed upon the stud-k Fig 1 represents
the gas supply valve.
Having now described the nature of my Invention in Gas Motor Engines
1 claim,
First The Slide Valve as described and set forth in the drawings
Second The method of keeping the surfaces of the slide valve in close contact
as described
Third―The combination of the Gas supply valve controlled by the Governor

page_text: and a relief valve situated at that end of the Cylinder where the mixture of gas
and air is taken in for ignition, as described
In witness whereof I the said John Dougill have hereunto set my hand and
seal this Seventeenth day of December in the year of our Lord one thousand
eight hundred and eighty three.
Signed sealed and delivered by
the said John Dougill in
the presence of
D. EDW. GRIFFITH
Solicitor Oldham
JOHN DOUGILL (L.S.)