IMPROVEMENTS IN GAS ENGINES
Year: 1884

page_text: I, JOHN MAGEE, of Glasgow, in the county of Lanark, Engineer, do hereby
declare the nature of my said Invention for "IMPROVEMENTS IN GAS ENGINES,"
to be as follows:-
This Invention relates to gas engines, and it consists of improvements in con-
struction (1) to provide for cutting off the admission of the combustible charge at
any part of the stroke; (2) to regulate the degree of compression to which the
combustible charge may be subjected within the cylinder; and (3) to facilitate the
starting of the engine; and it also embraces means whereby the heat parted with
to the cylinder on the combustion of one charge may be absorbed and utilised in
raising the temperature of the succeeding charge previous to explosion.
The improved gas engine comprises the ordinary form of cylinder which may
or may not be provided with a water jacket according as the mode hereinafter
described, of utilising the waste heat of combustion of the charge, is or is not
applied, and at any convenient point on the cylinder casing is fitted the valve
which regulates the admission, of gas and air into the cylinder, such valve being
in communication with the interior of the cylinder by a port formed at a point
near the end of the stroke of the working piston. The admission valve may be of
any ordinary form and may open and close the admission port by a reciprocating,
oscillating, or rotatory movement, but in every case the inlet orifice or port through
which the mixture of gas and air is admitted through the valve, is provided with
a movable cut-off plate, disc, or piston or similar device, whose position in the
orifice may be regulated by a hand screw, so that the admission of gas and air or
combustible mixture may be cut off at any point in the movement of the valve,
and therefore at any part of the stroke of the engino. The admission valve also
forms as usual the ignition valve, an ignition port being formed in it, and a gas jet
being kept constantly burning in a funnel in the valve casing. The ignition port
is by preference formed in a tube in the body of tho valve through which a portion
of the compressed combustible charge is admitted to carry the flame into the
cylinder.
The cylinder is of considerably greater length than the length of the stroke of
the piston, and in the end beyond the admission port is fitted an adjustable piston
or movable cylinder-end, which by means of a screw spindle or similar device can
be set to increase or diminish the size of the chamber beyond the end of the stroke

page_text: of the piston. By varying the cut-off as hereinbefore described, and thereby
regulating the quantity of the combustible mixture admitted to the cylinder, and
by varying the position of the adjustable piston, so that on the in-stroke of the
moving piston any desired dimensions of a compressing chamber may be left
between the pistons, the degree of compression to which the combustible charge
is subjected may be regulated; and the degree of compression may be maintained
constant by adjusting the piston while the admission of the combustible mixture
may be cut off earlier or later. By means of these arrangements a greater or less
supply of combustible mixture may be admitted and the engine worked to develop
any power within its maximum and minimum limits, while a charge is exploded at
every alternate revolution, instead of the power being varied as in the usual
arrangement by exploding the charge at greater or less intervals.
To facilitate the starting of the engine, a separate valve, which may be fitted on
the opposite side from the inlet valve casing, is provided, and through it is pumped
or otherwise forced a charge of gas and air, the working piston being prevented
from moving forward during the filling of the compression chamber of the cylinder
by a stop, which is pushed in front of an arm on the crank shaft or on the piston
rod or other moving part. The extra valve is preferably of the oscillating kind;
and after the starting charge is pumped into the cylinder the valve is turned to
bring an ignition port in communication with the port entering the cylinder, so
that the charge is fired, the lever which turns the valve being connected to the
stop which is withdrawn by the same movement to free the arm on the shaft or on
the piston rod.
•
The cylinder may be provided with the usual water jacket, but it is preferred to
utilise the heat which is parted with to the cylinder at each explosion, by admitting
a smaller volume of combustible mixture than will, at the normal pressure, fill the
cylinder, and causing the combustible charge to expand, and in doing so to absorb
the heat of the cylinder walls during the out-stroke of the piston. On the return
stroke the combustible charge is compressed, and it is fired when it has already
attained a comparatively high temperature. In this case an explosion of the
combustible mixture only takes place at each alternate stroke.
The engine may be made double-acting by providing admission, ignition and
exhaust valves at each end of the cylinder, and fitting an adjustable piston or
diaphragm at each end of the cylinder to form a compression chamber at each end
of the stroke of the working piston.

page_text: COMPLETE SPECIFICATION.
I, JOHN MAGEE, of Glasgow, in the county of Lanark, Engineer, do hereby
declare the nature of my invention for "IMPROVEMENTS IN GAS ENGINES," and in
what manner the same is to be performed, to be particularly described and
ascertained in and by the following statement:-
This invention relates to gas engines and it consists of improvemonts in con-
struction (1) to provide for cutting off the admission of the combustible charge
at any part of the stroke (2) to regulate the degree of compression to which tho
combustible charge may be subjected within the cylinder, and (3) to facilitate the
starting of the engine; and it also embraces means whereby the hoat parted
with to the cylinder on the combustion of one charge may be absorbed and
utilised in raising the temperaturo of tho succeeding charge previous to explosion.
The accompanying Drawings illustrato soveral modifications of gas engines
embodying my improvements. Figure 1 is a side elevation of one modification
of the improved gas engine, showing the admission valve in section, Figure 2
is a horizontal section of the same, Figure 3 is a transverse vertical section, and
Figures 4 and 5 is a sectional elevation and plan of the valve and valve casing,
slightly modified from that shown in Figures 1 to 3; and Figures 6 and GA show
other modifications of the valve and valve casing. Figures 7 and 8 are respectively
a vertical section and side elevation of a modification in which the engine cylinder
is fitted vertically instead of horizontally, and Figure 9 sbows a slightly different
modification of the valve mechanism in elevation corresponding to Figure 7.
Figures 10, 11 and 12 are respectively, a side elevation, horizontal section, and
enlarged transverse vertical section of a further modification, and Figure 13 is a
detached section of the admission valve.
Figures 14 and 15 are a sectional elevation and plan of a modification having
two working cylinders. Figures 16 and 17 are respectively a horizontal section
and end elevation showing a modified arrangement of the means for effecting the
compression of the combustible charge and the ignition valve details. Figure 18
shows a detail hereinafter referred to.
Referring particularly to the modification shown in Figures 1 to 6, the improved
gas engine comprises the ordinary form of a cylinder A, which may or may not be
provided with a water jacket a according as the mode hereinafter described of
utilising the waste heat of combustion of the charge is or is not applied, and at any
convenient point in the cylinder casing is fitted the valve B, which regulates the
admission of gas and air into the cylinder, such valve being in communication
with the interior of the cylinder by a port c, formed at a point near the end of the
stroke of the working piston D. The admission valve B may be of any ordinary
form, and may open and close the admission port by a rotatory movement, but in
every case the admission of combustible charge is cut off in one or other of the
ways hereinafter described. For example in the case where a uniform cut off is
desired the valve port may be made such as to cut off the admission of combustible
mixture at any fixed part of the stroke, as at one half, one third, or one fourth of
the stroke. Or the inlet orifice or port c¹ through which the mixture of gas and

page_text: air is admitted through the valve B, may be provided with a movable cut off plate,
disc, or piston, or similar device c³, whose position in the orifice may be regulated
by a hand screw c³, so that the admission of gas and air, or combustible mixture
may be cut off at any point in the movement of the valve, and therefore at any
part of the stroke of the engine.
In the example illustrated the valve B has a rotatory movement which is com-
municated to it through gearing F from a shaft F¹ geared at F to the crank
shaft G all revolving in the direction of the arrows. The valve B is made in
the form of a hollow conical plug to the centre or port c¹ of which the gas and
air are admitted, the gas entering by a port b in the valve, which comes opposite
an orifice b¹ in the valve casing B¹ at each rotation of the valve, and the air being
admitted through an opening a which may be in the centre of the valve. A port c¹
is also formed in the valve B, and this port el is in communication with the port c
in the cylinder at the time when the port b is opposite the orifice b', which is
while the piston D is on its outstroke, so that the action of the moving piston D,
is to draw in a charge of gas by the ports b, b, c, c', while air also enters by the
opening a and mixes with the inflowing gas in the port c'. The valve B is driven
through the gearing at half the speed of the crank, so that while gas and air are
admitted to the cylinder A at the part of the out-stroke, the admission is cut off by
the closing on each other of the ports e c', or of a movable cut-off plate c³ in the
valve (or its equivalent, an adjustable or removable piece c³ serving to vary the size
of the orifice of the valve port, as shown in Figure 6A) before the piston reaches
the end of its outstroke so as to expand the charge, within the cylinder, and so
that at the succeeding in-stroke, the ports being closed, the combustible mixture
within the cylinder may be compressed. While at the commencement of the next
out-stroke of the piston the ignition of the charge is effected by the admission
through the port c of a jet of flame from an ignition tube or port i, which has by
this time been carried round by the valve to the line of the port c, the combustible
charge being thereby exploded. The ignition tube iis fitted in the valve B and
is supplied with gas while in the position shown in figures 1 and 2 from a gas
pipe communicating with a recess in the valve B and casing B₁ below the
ignition tube. An orifice in the tube is then in communication with a funnel I
in which is burning a gas jet at 1¹ supplied by a pipe 2. The gas in the tube i is
thereby fired and is carried round to the port c in an ignited state and there
the flame is carried into the cylinder by a blast of the compressed combustible
charge within the cylinder which is at that moment injected from the cylinder
through the port i³ and tubo i back to the cylinder through the port c.
modification shown in figure 6 the two ends of the port i are extended on one side
in advance of the central part of the port in order that the blast or igniting charge
from the cylinder may enter from the two ports converge in the centre of the
port and thence enter the port c to ignite the combustible charge in the cylinder.
The exhaust takes place through a separate porte on the opposite side of the
cylinder into a chainber e in which is a valvo E normally closed by a spring
against its seat in the chamber but opened at the requisite intervals by a lever H
acted on by a can on the rotating shaft F. To prevent the valve B from rising
in its casing it is pressed into its seat by a lever J acted on by a spring j, the
pressure of the spring being as light as possible in order to avoid friction of the
valve in its seat, but in order to provide for a sufficiently high pressure on the valve
at the moment when the explosion occurs within the cylinder and when the valve
would be liable to rise, the end of the lever J is connected to a piston or flexible
diaphragm K fitting an orifice in the cylinder A. This plunger or diaphragm
receiving the shock and pressure of the explosion transmits the pressure to the
valve B and tends to hold it with greater firmness in place. In lieu of the single
piston or diaphragm there may be two pistons or diaphragmus K, K, acted on in
opposite directions as is indicated in Figure 18.
23
In the
The cylinder A is of considerably greater length than the length of the stroke
of the piston D, and in the end beyond the admission port c, is fitted an adjustable

page_text: piston or movable cylinder end P, which by means of a screw spindle p or similar
device, can he set to increase or diminish the size of the chamber beyond the end.
of the stroke of the piston D. By varying the cut-off as herein before described.
and thereby regulating the quantity of the combustible mixture admitted to the
cylinder, and by varying the position of the adjustable piston P, so that on the
in-stroke of the piston D any desired dimensions of a compressing chamber may
be left between the pistons D, P, the degree of compression to which the combus-
tible charge is subjected may be regulated; and the degree of compression may be
maintained constant by adjusting the piston P, while the admission of the com-
bustible mixture may be cut off earlier or later. By means of these arrangements
à greater or less supply of combustible mixture may be admitted and the engine
worked to develop any power within its maximum and minimum limits, while
a charge is exploded at every alternate revolution, instead of the power being
varied as in the usual arrangement by exploding the charge at greater or less
intervals.
In the examples shown in Figures 7, 8 and 9 the arrangements of various parts
are slightly modified to suit the vertical form of the engine, but in other respects
there is little divergence from the modification just described. The details and
passages of the supply and ignition valve B of this arrangement, are shown
detached in Figures 4 and 5. The pressure on the upper side of the valve B is in
this case maintained by a lever J and spring J' as before, shown acting on anti-
friction rollers J, but the piston K (or diaphragm) which conveys the pressure dne
to the shock of explosion is fitted in and forms the cover of the chamber or
casing e¹ of the exhaust valve E and entirely outside the cylinder A, as shown in
Figure 9. A governor L of novel form is also shown applied. To the collar of a
centrifugal ball governor is fitted a bell crank & carrying a bar whose end is fitted
with an antifriction roller in the path of a cam or wiper l'on a disc. On the
bar hangs a rod whose lower end is fitted with a plug or stop valve b³ arranged
to close off the gas supply when it falls. When the speed of the engine is normal
the roller on the arm is in the path of the cam and is raised at each revolution
of the cam and raises the gas supply valve b, but when the engine exceeds the
normal speed the roller on the arm l' is carried laterally out of the path of the
wiper and the supply valve is not raised..
To facilitate the starting of the engine, a valve M which may be fitted on the
opposite side from the inlet valve casing B₁, and may also serve as an exhaust
outlet, is in some cases provided and fitted as shown in figures 11 and 12, and
through it is pumped or otherwise forced into the cylinder A by a port f, a charge
of gas and air, the working piston D being prevented from, moving forward during
the filling of the compression chamber of the cylinder by a stop bar O, which is
pushed in front of an arm or into a notch o in a disc on the crank shaft G or on
the piston rod or other moving part. This starting valve M is preferably in the
form of an oscillating plug, and after the starting charge is pumped into the.
cylinder the valve is turned to bring in communication with the port e entering
the cylinder on that side, an ignition port m, which while the starting charge is
admitted is opposite a funnel m¹ in which a jet of gas burns, so that the charge is
tired by the burning gas carried round in the ignition port m, the lever N, which
turns the valve M being connected to the stop bar O, which is withdrawn by the
same movement to free the crank shaft. The exhaust valve E is in this case fitted
within the plug valve M, and the exhaust passages are also formed therein.
The working ignition valve is in this example a slide valve B' whose ignition
ports are arranged and the ignition effected in the manner described in reference to
Fig 6 and which is operated by an anchor lever Q with arms and antifriction
rollers g, which are acted on by cams or wipers q¹ on the shaft F. Both the
ignition valve B' and the starting plug valve M are pressed on to their seats by
levers J acted on by a spring j and plunger and diaphragm K fitting an orifice in
the cylinder in the manner already described. A peculiar arrangement is provided
in this example and in that shown in figures 14 and 15 whereby the admission and

page_text: cut-off of the combustible charge is regulated with certainty at the required point,'
and by which the period of cutting-off may be varied. This consists in fitting a
valve R in a passage T through which the combustible mixture is admitted to the
cylinder. This valve R is opened at the requisite intervals by a lever S operated
by a cam S on a rotating shaft F¹ to uncover small orifices through which the gas
passes from the casing r, to the under bearing face of the valve, and thence to the
interior of the passage T, the gas together with a supply of air from the inlet
chamber a being drawn in, while the valve R is open, by the out-stroke of the
piston D. When the valve R closes, the suction due to the motion of the piston
only tends to retain it the more firmly on its seat. At or near the inlet to the 1
cylinder from the passage T is a second valve R', which opens by the suction of:
the piston to admit the charge, but closes on the in-stroke of the piston and
prevents any action on the valve R. In figures 10 to 13 the actuating cam S¹ is
formed with a curved or tapered acting surface and is adjustable by the hand
lever S3, and the period of opening the valve R is determined by the position of 1
the adjustable cam.
In lieu of the regulating screw p in the former examples an hydraulic plunger U.
is employed to regulate the position of the piston P, the plunger being arranged to
recede when an undue pressure comes on the piston P and to return and press up
the piston P when the pressure is relieved.
In the double cylinder or twin engine shown in figures 14 and 15, the valve R
admits the charge to the oscillating plug valve B, provided with passages for the
supply and ignition of the charges for both cylinders; the valve R being actuated
by the lever arrangement R' and cam S on the short second motion shaft F¹; and
the valve B is reciprocated by the crank F and rods F" from a crank pin_or
eccentric on the wheel F actuated by the pinion F on the crank shaft G. The
cranks are placed in the same position on the crank shaft G, so that the valve B
may supply one cylinder at each alternate out-stroke and the other cylinder at the
intervening alternate out-strokes.
Figures 16 and 17 illustrate a mode of forming a movable end P' in the
cylinder A, in lieu of fitting an adjustable piston within the cylinder. The ignition
valve B is in this example a slide valve, and is fitted on the movable end P¹. To
provide for adjustment of the position of the cylinder end P', without disengaging
the connection between the slide valve B' and its operating mechanism, the ignition
valve B is formed with a slot B³ through which the end of the shaft B¹ passes and
is fitted with a crank arm sliding on the shaft F¹ and acting on the rollers q³ which
imparts the to-and-fro motion to the valve, which projects to a sufficient extent
beyond the end of the cylinder A to permit of the longitudinal movement of the
cylinder end P¹, so that the valve B' controls the ignition of the charge in the
manner described in reference to Fig. 6 and illustrated in figures 10 to 12.
The admission of the combustible charge and the exhaust of the products of
combustion may be effected by any of the arrangements hereinbefore described.
The cylinder of the engine may be provided with the usual water jacket, but it
is preferred to utilise the heat which is parted with to the cylinder at each
explosion by admitting a smaller volume of combustible mixture than will at the
normal pressure fill the cylinder, and causing the combustible charge to expand,
and in doing so to absorb the heat of the cylinder walls during the out-stroke of
the piston. On the return stroke the combustible charge is compressed, and it
is fired when it has already attained a comparatively high temperature. In
this case an explosion of the combustible mixture only takes place at each
alternate stroke.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I desire it to be
understood that I make no special claim to the following parts which I have had
occasion to describe and show in the drawings, namely, the arrangement of gas
inlet valve b², and manner of actuating the same by the governor L, in reference to

page_text: Figures 7 and 8; or of the arrangement of the valves R and R' for the admission
and cut-off of the combustible charge and the mode of actuating the same, in
roference to Figures 10, 11, 13, 14 and 15; and further of the slide ignition
valve B, and means of actuating the same in reference to Figures 10, 11, 12, 16
and 17: but I declare that what I claim is
1. The improvements in gas engines substantially as herein described and
illustrated.
2. In gas engines the arrangement in combination with the admission valve of a
cut-off piece in the admission port, adjustable by hand and serving to vary the
period of cutting off the supply of combustible mixture or the equivalent purpose
of varying the size of the admission orifice substantially as herein described.
3. The combination of parts herein described for cutting off the admission of the
combustible charge at any part of the stroke and correspondingly varying the
degree of compression to which the charge is subjected within the cylinder.
4. The arrangement within a gas-engine cylinder of a stationary piston or
cylinder end adjustable as to position for varying the degree of compression to
which the combustible charge may be subjected within the cylinder, in combination
with a cut-off valve arrangement, substantially as herein described.
5. In a gas engine, the starting valve M arranged to admit a starting charge of
combustible mixture to ignite the same, and to serve as the exhaust outlet,
substantially as herein described and illustrated.
6. In a gas engine, the arrangement of the stop O in combination with the
valve M for admitting a combustible charge to facilitate starting of the engine,
substantially as hereiu described and illustrated.
7. The mode herein described whereby the heat evolved in the combustion of
one charge within a gas-engine cylinder is absorbed and utilised in raising the
temperature of the succeeding charge, said mode consisting in admitting a charge
of combustible mixture, cutting-off at less than full stroke, expanding the charge
during the out-stroke to absorb the heat of the cylinder, compressing the charge
during the in-stroke and exploding the heated charge, substantially as herein
set forth,