Year: 1886

page_text: We, MATTHEW MILBURN, of Kirkintilloch, in the County of Dumbarton, North
Britain, Chemist, and ROBERT HANNAN, of 14 Woodside Place, Glasgow, in the
County of Lanark, North Britain, Merchant, 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, that is to say :-
Our said Invention has for its object to obtain improved results from motors
worked by combustible gas or vapor, and to avoid various inconveniences and
objections appertaining to existing gas or vapor motors.
In carrying out our Invention according to one modification a single motor
cylinder is employed and is fitted with a piston connected in the usual way by a
connecting rod to a crank on the main shaft; but the cylinder is extended beyond
the inner end of the stroke of the piston (hereinafter termed the motor piston) and
in the extended part there is a relief piston which is not connected to any part by
a rod or otherwise. The relief piston is formed with an internal cavity, and is
fitted with check valves on both sides of the cavity, whilst the inner end of the
cylinder is fitted with check valves for admitting air. At one outer stroke of the
motor piston it draws the relief piston after it and causes air to enter into the space
between the relief piston and the inner end of the cylinder. After moving out-
wards a certain distance the motor piston uncovers port through which a
combustible mixture of gas or vapor and air enters to form the next explosive
charge. On the return stroke of the motor piston the explosive:charge and the
air (separated from the explosive charge by the relief piston) are compressed;
when the greatest compression has been attained and the motor piston is beginning
to move outwards again, the charge is ignited. The pressure due to the explosion
acts partly on the motor piston and also on the relief piston and in moving the
latter, so as to further compress the air behind it, diminishes the violence of the
action on the motor piston. Towards the latter part of the motor stroke the reaction
of the compressed air operating like a spring maintains considerable pressure on
the motor piston; and the arrangement causes the force of the explosion to be
better distributed throughout the stroke than in existing gas or vapor motors. At
the next inward stroke of the motor piston an exhaust port is open and the
products of combustion are expelled as completely as possible.
and

page_text: And in order that our said Invention and the manner of performing the same
may be properly understood we hereunto append a sheet of explanatory drawings
to be hereinafter referred to and representing a gas motor as made with our
improvements.
Figure, 1, on the accompanying sheet of drawings is a sectional elevation of the
gas motor; figure, 2, is a vertical section as at right angles to figure, 1; and
figure, 3, is an enlarged section of the relief piston; whilst figure, 4, is a horizontal
section showing the inlet for the combustible mixture and the exhaust port. In
these drawings the same reference numerals are used to mark the same or like parts
wherever they are repeated.
In the engine shown in the drawings the motor cylinder, 5, is vertical being
bolted down to a base, 6, and having a flared upper end and flange, 7, on which
are bolted bearing pedestals, 8, for the main or erank shaft, 9. This shaft, 9, has
fixed on one end of it a flywheel, 10, whilst a pulley, 11, for a belt for transmitting
the power is fixed on the other end. A connecting rod, 12, jointed on the
crank, 13, in the usual way has its lower end jointed to a long motor piston or
plunger, 14, working in the cylinder, 5. The cylinder, 5, extends downwards
beyond the point reached by the piston, 14, at the inner end of the stroke; and in
the extended part of the cylinder there is a relief piston, 15, which is fitted to work
freely in the cylinder, and is made with an internal cavity, 16, whilst check valves,
17, 18, allow of the passage upwards of air into the cavity, 16, and of its passago
thence to the space above the relief piston, but the lower check valves, 17, are
loaded with springs for a purpose hereinafter explained. Check valves, 19, are
fitted to the bottom end of the cylinder, 5, to admit air when the internal pressure
is less than that of the atmosphere but preventing its return. The air entering
through the bottom valves, 19, has access to them through holes in the base, 6, and
through wire gauze, 20, which keeps back dust.
The motor piston, 14, is represented as about to commence its inward stroke
immediately after an outward explosive stroke, at which time the relief piston, 15,
should be in the position shown, being sustained by the air beneath it which air is
of a pressure corresponding to the spring load on the lower valves, 17. The
exhaust port, 21, is just above the relief piston when in the position shown, and
being open the products of combustion are forced out by the descent of the motor
piston, 14. A simple conical plug valve, 22, is shown as controlling the exhaust
port, and is worked by means of a lever, 23, fixed on it and connected by a rod, 24,
to a crank on a short shaft, 25, turned at half the speed of the crank shaft, 9, by
means of a pinion, 26, and spurwheel, 27. Any other convenient form of exhaust
valve may however be employed.
The inlet port, 28, for the combustible mixture is considerably nearer the upper
end of the cylinder, 5, than the exhaust port, 21; and when the motor piston, 14,
moves outwards after an inward exhaust stroke it does not uncover the inlet
port, 28, until past the middle of its stroke. Consequently, during the first part of
the stroke outwards the motor piston produces a partial vacuum which causes the
relief piston, 15, to follow it upwards; and on the pressure beneath the relief
piston becoming less than that of the atmosphere air enters by the bottom
valves, 19. After the bottom of the motor piston passes the inlet port, 28, then
combustible mixture enters during the remainder of the outward stroke. The
inlet port, 28, is controlled by a valve, 29, shown as a conical plug valve, but which
may be of any convenient kind; and this valve is connected by means of a lever, 30,
rod, 31, and lever, 32, to a speed governor, 33, but is never otherwise closed by the
action of the engine. The air and combustible gas are supplied by pipes, 34, 35,
fitted with regulating stopcocks, 36, 37, and also with check valves, 38, 39, which
latter prevent the pressure due to the explosions from acting in the supply pipes,
34, 35. When the speed of the engine is too great the governor acts by simply
diminishing the supply of combustible mixture for each stroke; and in consequence
of this action the relief piston, 15, rises higher than it otherwise would do, so that
the space between it and the motor piston, 14, is at the end of the outstroke less

page_text: than at other times, but the combustible mixture in it is of the same proportionate
composition being simply diminished in quantity, but not diluted. There is thus
no more difficulty in igniting the smallest charge than the largest one; whilst the
number of ignitions relatively to the revolutions of the engine will not be
diminished when the engine is working with diminished power and resistance.
The action of the engine will consequently be much more regular than that of those
existing gas motors, which can only work at diminished powers by governing
appliances, causing the missing of ignitions.
Any suitable known form of igniting apparatus may be used, that shown
consisting of a thin metal tube, 40, fixed through the side of the cylinder, 5, at
about the level of the exhaust port, the outer end of this tube being closed and the
tube kept sufficiently hot for igniting the combustible mixture when in its compressed
state by a jet of gas, 41, arranged to burn round it as shown.
When the relief piston, 15, is forced down by the explosion some of the air com-
pressed beneath it is by the compression made to pass through its lower valves, 17,
into its cavity, 16, and this air afterwards passes through the upper valve, 18,
towards the end of the motive stroke and assists in maintaining the motive
pressure.
The cylinder, 5, may be placed horizontally or in an inclined position; and two
or more cylinders may be combined in one engine.
We expect that the temperature to which the motor cylinder will be raised will
be so moderate that the usual water jacket may be dispensed with, but such jacket
may be added if found desirable.
Having now particularly described and ascertained, the nature of our said
Invention and in what manner the same is to be performed we declare that what
we claim is:
--
•
1: The combination of parts constituting the improved gas or vapor motor
substantially as hereinbefore described and shown in the accompanying drawings.
2. The so-called relief piston with its cavity, 16, and check valves, 17, 18, and
with the air inlet check valves, 19, arranged and operating substantially as herein-
before described.
3. The mode of varying the power developed, in accordance with the action of
a speed governor, by a valve varying the quantity of a uniform combustible
mixture, such mixture in its smaller or larger quantities being separated by a
so-called relief piston or its equivalent from air occupying the remainder of the
cylinder substantially as hereinbefore described.