IMPROVEMENTS IN GAS MOTOR ENGINES
Year: 1882

page_text: PROVISIONAL SPECIFICATION left by Joseph John Butcher at the Office of
the Commissioners of Patents on the 8th December 1882.
JOSEPH JOHN BUTCHER of the City of Newcastle-upon-Tyne Engineer
" IMPROVEMENTS IN GAS MOTOR ENGINES
"
When constructing gas motor engines which work upon the method of
compressing their gaseous charges within the same cylinder or cylinders and upon
the same side or sides of the piston or pistons in or upon which they are
subsequently exploded or burned I so arrange that in any such cylinder the
exhaust ports are open somewhat before the piston arrives at the end of its
outward stroke and somewhat after it has commenced its inward stroke. When
the expansion is completed so far as it is desirable for the working of the engine
(the gases being usually still at a pressure above that of the atmosphere) the
products of combustion are allowed by the first opening of the exhaust valves to
expand freely into the atmosphere into a suitable exhaust pipe. By this means
they are almost instantly reduced to atmospheric pressure, but the operation still
leaves within the cylinder a volume of the products of combustion equal or nearly
equal to that of the full internal capacity of such cylinder; and these gases occupy
the space into which the fresh charge for the next successive stroke requires to be
supplied. For the purpose of withdrawing these waste gases, or the major portion
of the same, I employ a separate pump the piston of which has just commenced its
suction stroke at the moment when the exhaust ports in the cylinder are opening,
and which when exhaustion has taken place down to the atmospheric pressure
is continuing its suction stroke so as to cause a slight vacuum within the cylinder
(the exhaust pipe connecting the same with the atmosphere being fitted with
a suitable back pressure valve to prevent the portion of the gases which has
already escaped from passing back again down it and thus destroying the slight
vacuum in the engine) and thus tend to withdraw its gaseous contents by suction
into the pump before named, and into the passages leading to the same. This
suction pump or discharger as it may be called is preferably made of large capacity
compared with that of the cylinder, and the vacuum that it produces in the same
allows the atmospheric air to expand freely into it through an ordinary inlet
valve of mitre or other type at the end of the motor cylinder opposite to that at
which the exhaust port or ports are situated. This valve is preferably made

page_text: self acting and of the back pressure type so that when the vacuum set up within
the cylinder is after the closure of the exhaust ports exchanged for a plenum in
consequence of the motion of instroke of the motor piston such inlet air valve
will close of itself and prevent the escape of the air from the cylinder. During
the process of influx of the air to the cylinder but preferably not at the first
commencement of such influx, suitable means are provided of admitting with it, so
as to mix effectually with the stream, a proportion of coal or other gas capable of
forming with air an inflammable mixture. Such gas might obviously be arranged
to be drawn in round the seating of the air inlet valve, but I also can arrange it to
enter through the slide or other kind of ignition valve employed for the ignition of
the gases so as to ventilate and charge the port in the cylinder used for igniting
the main portion of the charge, and in this case with the very latest portion of the
entering gaseous stream and when the same is nearly cut off a small portion of
air may be admitted with it so as to ensure that a strongly inflammable mixture is
formed in immediate juxtaposition to the igniting port. By this arrangement of
engine not only can the products of combustion from the last charge be almost
wholly withdrawn from the cylinder as the first air enters but the liability to the
escape of coal gas through the open exhaust port is minimised as pure air can be
ensured as the element entering during the first period of induction. But a third
advantage is also gained over those engines in which the constituents of combustion
are mixed in a separate cylinder and forced into the motor cylinder during the
time when the exhaust ports are open, as if the governor is arranged to control the
engines speed by wholly suppressing individual charges of gas such gas can be cut
off sharply.immediately prior to entering the motor cylinder so as to prevent the
waste of any gas that would otherwise be mixed with the air in the passages
leading to the same. Back explosions are also avoided as no mixture of the gases
takes place until actually within the motor cylinder. For this purpose I arrange
that the communication between the main gas supply pipe and the gas admission
valve to the engine is controlled by another small valve which, is only opened by
the action of the governor when the engine is not over-running the speed required
and which when it is over-running such speed is closed so as to prevent the entry
of gas.
To prevent the exhaust gases when first escaping at pressure from setting up a
momentary pressure in the cylinder of the discharger and in its ports and passages
I preferably arrange that on its escape from the cylinder it enters between a pair
of self acting mitre or other back pressure valves both of which open outwards
from the cylinder the one opening towards the atmosphere and the other towards
the discharger; these valves are rigidly coupled together through their spindle and
are so distanced apart that one of them must be open when the other is closed.
The valve opening towards the discharger I prefer to open downwards and so
arrange that its area exposed to gaseous pressure is less than that of the valve
opening upwards towards the atmosphere. Thus when the gases coming at pressure
from the exhaust enter between these valves the area of the one opening towards
the atmosphere being considerably larger than that of the one opening towards
the discharger ensures that it will be lifted and opened by the gases in the act
of doing which it necessarily closes the valve opening, towards the discharger.
When however the exhaust gases have fallen in pressure to that of the
atmosphere by the escape of gas through the former valve the weight of the
valves together with the suction caused by the discharger piston which is at the
time moving on its outward or suction stroke cause the pair of valves to come
down, the valve towards the discharger opening and the valve towards the
atmosphere closing. The further movement of the discharger piston removes the
remainder of the waste gases from the cylinder as before explained and when
the piston of the motor cylinder has returned a short distance upon its stroke and
the exhaust valves proper to the motor cylinder are closed the exhaust gases are
completely cut off from the same and may be discharged by the discharger piston
through a suitable eduction valve into the atmosphere. As these exhaust valves.

page_text: require to have a very large area of opening to pass the gases in the times required
I sometimes arrange them as ring valves. with two concentric seats to each valve
one inner and one outer. The valves close upon these two seats at once and
when open have an aperture equal to a pair of valves of their mean diameter.
I sometimes work the discharger piston in a vertical direction from. a pin in the
connecting rod (where the gas engine is of the horizontal type).. This pin travels
in an elliptical path and the long curve of its top travel enables mo by coupling
it with a short connecting rod to the discharger piston to practically neutralize
the action of this piston during that portion of the vertical movement of the
crank pin which takes place after the exhaust ports in the motor cylinder are
closed and when no continued movement of the discharger piston would be serviceable.
It is however obvious that this discharger piston could be worked by the crank or
by a separate crank and thus placed in any convenient or desirable position. As
the discharger piston, does, not need to cause any but a slight.vacuum I do not
always use packing rings for rendering it tight, but may simply turn a series of
grooves in its working. face so as to reduce the passage of air to an inappreciable
degree and avoid all needless friction in the working of the engine.
:
1
.
To ignite the charges in these engines I may use any suitable igniting and gas.
inlet valve or valves or a slide valve of special type such as I will now describe.
This valve is kept down upon its seat by means of a suitable cover and fastenings'
of any usual or convenient type and in an. aperture forming.a port, within it a
flame (Bunsen or other) is kept constantly burning. In the valve a small port is:
formed which when opposite the permanent flame makes open connection between
the igniting port in the engine face and the atmosphere. In one side of this valve
port a small hole is formed which at the moment that the port first opens to the.
igniting port in the engine is in communication through suitable passages with a
groove in the valve cover or engine face plate which is constantly supplied with
coal gas.
Within the igniting port of the engine is a small piston working within'
a bored sleeve and suitably packed so as to be gas tight and at the moment the
valves open connection between the igniting port in the engine and the atmosphere,
this piston is moving away from the port so as to cause an indraught from the
atmosphere and it is also so arranged as to sever the connection between the
igniting port and the interior of the cylinder with its inflammable charge. As the
little piston rises the permanent flame is drawn across the gas jet in the valve,
which is ignited thereby (if not previously ignited in the course of its backward
travel past the permanent jet) and a sheet of flame enters the sleeve in which the
piston moves. As the piston continues its motion the valve travels onward first
cutting off the connection with the atmosphere and immediately afterwards with
the supply of coal gas. Directly after this connection is broken a hole in the
valve communicating with the coal gas passages before named comes opposite a
hole in the engine face which is in connection with the interior of the cylinder¨
and through which inflammable gas mixture follows the coal gas through the same
supply passages into the flame chamber and thence into the sleeve in which the
small piston is moving. To avoid any inconvenience which might be caused by '
an accumulation of waste gas in the small passages which communicate between
the coal gas passages in the valve and the interior of the cylinder and which would
tend to precede the inflammable mixture in entering the flame chamber I some-
times provide a small pocket in the valve which will pass first over the passage in.
the engine face and into which the pressure will force the slight amount of waste
gas accumulated therein which in the further movement of the valve may be
discharged through a suitable passage into the atmosphere leaving the passage into
the engine filled with inflammable gas mixture. The inflammation of this gas
mixture beneath the little piston raises the pressure within the sleeve to that of
the compressed gas within the cylinder or somewhat above that pressure so that
when in the onward movement of the little piston communication is immediately
formed through suitable slots in the sides of the sleeve with the interior of the
engine a sheet of flame is prepared to strongly ignite the inflammable charge in
:
'

page_text: the same.
A further movement of the valve brings the exhaust or outlet passage
within it opposite the igniting port in the engine face so that on the return of the
little piston the gases accumulated within the sleeve may freely escape to the
atmosphere it being preferably arranged that they do so through a separate opening.
in the valve cover or engine face from that within which the permanent gas flame
is burning. I may fix a small spiral of platinum wire upon the piston so that by
its keeping hot it assists to give certainty to the ignition. The piston of this
igniting arrangement may be made to perform a second function and act as an
induction or exhaust valve and in the arrangement of engine described herein (to
which particular arrangement I do not intend to confine the use of the valve) it
may be conveniently employed for admitting the gas to this cylinder so as to mix
with the entering stream of air, and it may be also so arranged when desirable
that immediately prior to closing the induction gas passage it allows a small
portion of air to enter with the last of the gas so as to ensure that the ignition
apertures in the sleeve are surrounded by an inflammable mixture preparatory to
their being opened by the action of the piston so that ignition may take place.
•
To increase the temperature of the constituents of combustion prior to their
ignition as far as possible I sometimes pass them through a bath composed of the
hot exhaust gases which escape or are discharged from the engine or as the main
constituent of the charge is atmospheric air, it is sometimes sufficient to heat this
element only. To effect this purpose the supply pipe or pipes are surrounded by
an outer casing which forms a conduit for the exhaust gases and thus these latter
heat the incoming air or air and gas through the supply sides of the pipe or pipes
within which it or they are contained.
In cases where larger engines have to be started I sometimes effect the purpose
by so arranging that the fly wheel (which is not keyed fast upon the shaft as is
usual but is, when the engine is going driven by a clutch which is keyed or
otherwise conveniently fastened so that it always turns with the shaft, but which
clutch is also capable of being detached from the fly wheel) can, when it is desired
to start the engine be turned freely over the shaft, and without turning it so that
the inertia and friction of such fly wheel constitute all the resistance to be
overcome. When sufficient speed and consequent momentum have thus, by any
suitable or convenient means, been imparted to the fly wheel it is attached by
means of the clutch to the shaft so as to compel the latter, and also the other
moving parts of the engine to turn with it. The momentum thus conserved by
the flywheel is thus utilized in overcoming the resistance due to the act of
compression and when this operation is complete and an explosion ensues such
momentum is increased by the work done by the expanding gases. It is obvious
that a fly wheel so arranged might be started by hand or that it might be started
either by a small engine worked by gas or by water power such as that derived
from the ordinary town service pipes.
To effect the heating of the constituents of combustion (or of the air of which
they are in chief part formed) before they enter the cylinder of a gas motor
engine and when such constituents or constituent of combustion are at atmospheric
pressure or thereabouts by means of the waste heat of the exhaust gases, I prefer
to pass the former between pairs of plates which are heated upon their or from
their other sides by means of such exhaust gases. This may be done by giving
each of the plates a flat form, and forming a flange or distance piece along two of
its edges, but the distance pieces upon the edges of any plate projecting from its
surface upon one of its sides only. The plates will thus be of very flat channel
section. A number of these plates are built one on top of the other, with their
flanged faces all the same way, but so that plates 1, 3 and 5 &c have their flanged
edges in one direction, and plates 2, 4 and 6 &c have their flanged edges running
at right angles to them (the directions being referred to the planes of the plates)
then there will be formed a passage between each alternate pair of plates in one
direction and through each pair intermediate to these alternate pairs in the other
direction. When a number of such plates are packed together in a suitable box

page_text: or chamber so arranged that the exhaust gases pass into the chamber and between
alternate pairs of plates and out of the chamber in one direction and the incoming
constituent or constituents of combustion pass into the chamber and between pairs
of plates intermediate to the beforesaid alternate pairs and out of the chamber in
the other direction (care being taken in packing the plates and in the formation of
the chamber that the products of combustion do not mix with the constituents of
combustion) then such constituents of combustion will be exposed to the action of a
large heating surface and a considerable amount of the heat of the products of
combustion will be transferred to them.
I have herein before described a pair of valves (exchange valves they may be
called) to which the exhaust gases have access from the cylinder and the smaller
of which valves makes or breaks connection with the discharger. I in some cases
dispense with this smaller valve and leave the upper valve of the pair as a simple
back pressure valve opening towards the atmosphere by making suitable ports in
the sides of the discharger communicating with the exhaust passage of the motor
cylinder and so arranging that when first the exhaust gases are allowed to burst
away at pressure from the motor cylinder these ports in the displacer cylinder are
covered by the piston. The piston of the discharger when it is moving past these
ports drives out the remaining gas through an ordinary foot valve of the mitre or
back pressure type.