IMPROVEMENTS IN GAS ENGINES
Year: 1881

page_text: LETTERS PATENT to Arthur Thomas Allcock, of Newark-on-Trent, in the
County of Nottingham, Engineer, for an Invention of "IMPROVEMENTS IN
GAS ENGINES"
PROVISIONAL SPECIFICATION left by the said Arthur Thomas Allcock at
the Office of the Commissioners of Patents on the 9th February 1881.
ARTHUR THOMAS ALLCOCK, of Newark on Trent, in the County of Nottingham,
Engineer. "IMPROVEMENTS IN GAS ENGINES."
My Invention has for its object an improved method of regulating the admission
and ignition of the mixture of gas and air to the working cylinders of gas engines.
To effect this in simple gas engines working with a charge of gas and air drawn into
the cylinder at atinospheric pressure by the onward motion of the piston, I admit
a mixture of gas and air, in fixed and definite proportions of each, into the cylinder
by means of a main slide valve, formed with both admission and exhaust ports,
and worked from an eccentric on the crank shaft in the ordinary manner. To control
the admission of the mixture of gas and air through the main valve into the cylinder I
use a secondary cut off valve communicating with the main valve by means of a
port, and worked by a radius rod sliding in a curved link formed in or fixed to
the eccentric rod of a second eccentric on the crank shaft. This second valve also
carries the ignition port, and is so arranged with its radius rod that when the
position of the radius rod in the link is altered either by hand or by a governor
the point of cut off of the mixture of gas and air to the cylinder is also altered, as
well as that of ignition, which immediately follows that of the.cut off, and thereby
regulating the power and speed of the engine.
In engines working with a compressed mixture of gas and air I retain the same
general arrangement of valves and valve gear for admission, ignition, and exhaust,
but supply them from a small receiver, into which a compressor delivers a mixture
of gas and air of definite and fixed proportions. As the quantity of the mixture
required varies in accordance with the point of cut off I regulate the amount
delivered by the compressor into the receiver by the following means:-A lever
pivotted at one end to the radius rod of the cut off valve has its fulcrum on one
end of a small radius bar pivotted to a convenient part of the engine frame; the

page_text: other end of the lever gives motion by means of a connecting rod to a bell crank lever.
This bell crank lever has one of its arms engaging into the slotted head of the stalk
of the compressor suction valve, so that as the position of the radius rod in its link,
and with it the point of cut off, is altered it gives motion to the bell crank lever,
causing it to hold back the suction valve from its seat for a longer or shorter
period, according to the cut off. This allows the surplus quantity of the mixture
of gas and air that is in the compressor over and above the requirements of the
engine to escape back through the suction valve into a chamber provided for the
purpose, so retaining the density of the mixture of gas and air in the receiver
always at one determined point, the compressor always taking in a full charge but
only delivering the exact amount according to the requirements of the engine. In
lieu of the bell crank acting direct on the suction valve, as above described, motion
may be given from the lever to a small valve working in a bye pass between the
compressor cylinder and the suction chamber, and the same result obtained. Should
it be required to alter the degree of compression and density of the mixture of gas
and air delivered into the receiver, and with which the engine is working, the
fixed centre of the radius bar on the engine frame can be made adjustable either by
an eccentric, or a slot in the frame and a clamping bolt, and furnished if desired
with an index. The alteration of the position of this centre has the effect of
causing a uniform acceleration or diminution of the time of closing the suction
valve or its equivalent according to the position the centre occupies, the actual
time of such closing being determined by the cut off gear above described. A
curved guide attached to the frame of the engine may take the place of the radius
bar to carry the fulcrum of the lever, in which case the angle at which the guide
is set will determine the degree of density of the mixture of gas and air delivered
from the compressor.
The cut off valve which, as before described, carries the ignition port has the
outer end of the chamber in which it works furnished with a foot valve, through
which it draws in gas and air on its out stroke, compressing and discharging them
on the in stroke into the ignition port, either through a small valve formed through
the body of the cut off valve, or through a bye pass provided in the wall of the
valvė chamber for that purpose. As the cut off valve bas a variable motion given
to it by the means above described, it regulates at the same time both the motion
of the engine and the requisite amount of gas and air required for the purpose of
ignition.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Arthur Thomas Allcock in the Great Seal Patent Office on the
9th August 1881.
ARTHUR THOMAS ALLCOCK, of Newark upon Trent, in the County of Nottingham,
Engineer. "IMPROVEMENTS IN GAS ENGINES."
Figure 1 represents a side elevation, partly in section, of my improvements
applied to a single acting gas engine working with a charge of gas and air drawn.
into the cylinder at atmospheric pressure by the onward motion of the piston. A is
the main slide valve, receiving motion from the eccentric a, with a constant lead
and travel, and formed with an induction port a¹ and the exhaust port a²; B is a
secondary cut off valve, working in its own chamber outside the main valve A, and
communicating with it by a port b; a variable motion is given to the valve B
from the eccentric D by means of the curved link d formed in or attached to the,
eccentric strap, and guided by the radius bar d¹, which is pivotted at one end to a
suitable part of the engine frame, and at the other to the curved link a. The
radius rod d slides in the curved link d, its position therein being regulated from.
the lever d³, either by hand, as in Figure 1, or by a governor, as in Figure 2. The
effect of this arrangement is that a quick accelerated motion is given to the valve B
in the same direction as the piston, so that the nearer the position of the radius
rod d is to the outer end of the link d the quicker is the motion given to the
valve B, and the sooner it closes the port b, thereby cutting off any further supply,
of gas and air from the cylinder from the inlet 62. The valve B carries an ignition
port b³, charged with a mixture of gas and air, and ignites the charge in the
cylinder from the permanent flame F through the induction port a' in the main
valve A. The ignition of the charge in the cylinder follows immediately after the
port has been closed by the valve B, and the supply of gas and air from the inlet b
cut off.
Figure 2 is a front elevation, partly in section, of my improvements applied to a
single acting gas engine working with a compressed charge of gas and air.
Figure 3 is a back elevation, and Figure 4 is a plan, both partly in section, of
portions of the same arrangement. The same general arrangement of the valves A
and B for admission, ignition, and exhaust are used, as before described, the main
valve A being driven from its own eccentric a, and the valve B from its eccentric D
and curved link in connection with the governor lever d³. The outer end of the
cylinder H is used for the admittance and ignition of the charge, the inner end Ex,
Figure 4, being used as the compressor in the usual and well known manner. The
compressor Ex on its out stroke, due to the momentum. of the engine, draws in a
charge of gas and air in fixed and definite proportions of each through the suction
valve c from the suction chamber G, which is furnished with a foot valve g and a
gas supply g'. On its instroke the compressor delivers its charge through the back
pressure valve c¹ into the receiver C; the pipe 2 connects the receiver C with the
chamber of the cut off valve B, and supplies the engine. As the quantity of the
compressed mixture of gas and air required by the engine varies in accordance with
the point at which it is cut off and ignited by the valve B, I regulate the amount
delivered by the compressor Ex into the receiver C by the following means:-A
lever d' having one of its arms pivotted to the radius rod d² has its fulcrum on the
outer end of a small radius bar d³, which is pivotted at J to a convenient part of
the engine frame; the other end of the lever d' gives motion through a connecting
rod to the bell crank lever E. One of the arms of this bell crank lever E
engages into the slotted head e of the stalk of the compressor suction valve c, so
that as the position of the radius rod d² is altered in its link d, and with it the

page_text: point of cut off, it gives a differential motion to the bell crank lever E, causing it to
hold back the suction valve c from its seat for a longer or shorter period, according
the cut off. This allows any surplus quantity of the mixture of gas and air that is
in the compressor over and above the requirements of the engine to escape back
through the suction valve c into the suction chamber G, so retaining the density of 5
the mixture of gas and air in the receiver C always at one determined point, the
compressor always taking in a full charge, but only delivering into the receiver C
the exact amount according to the requirements of the engine.
In lieu of the bell crank E acting direct on the suction valve c, as above
described, motion may be given from the lever E to a small auxiliary valve working
in a bye passage between the compressor cylinder and the suction chamber G, and
the same result obtained. Should it be required to alter the degree of compression
and density of the mixture of gas and air delivered into the receiver C, and with
which the engine is working, the fixed centre J of the radius bar d' on the engine
frame can be made adjustable, either by a slot and a clamping bolt, as shown at j,
Figure 1, or by an eccentric, as at j in Figure 5, and furnished, if required, with an
index. The alteration of the position of this centre J has the effect of causing a
uniform acceleration or diminution of the time of closing the suction valve c or its
equivalent, according to the position the centre J occupies, the actual time being deter-
mined by the cut off gear, as before described. A modification is shown in Figure 6,
where a curved guide d³ may take the place of the radius bar to carry the fulcrum
of the lever d'. In this case the angle at which the guide d³ is set will determine
the degree of density of the mixture of gas and air delivered from the compressor.
An adjustment for regulating this angle is shown at j.
The cut off valve B, which, as before described, carries the ignition port 6³, has
the outer end of the chamber in which it works furnished with a foot valve K,
a gas supply k, and air passages shown by the arrows are formed in the foot valve;
through these on its outward stroke the valve B draws in gas and air, compressing
and discharging them on the in stroke into the ignition port 63, either through a
small valve formed in the body of the valve B, as shown at in Figure 1, or
through a bye pass K¹ provided in the wall of the valvo chamber, as shown in
Figures 2 and 7. As the cut-off valve B has a variable motion given to it by the
means before described it regulates at the same time both the motion of the engine
and the requisite amount of gas and air required in the ignition port b³ for the
purpose of igniting the charge in the cylinder from the permanent flame F.
The main valve A and the cut off valve B are shown in Figures 1, 2, and .4 as
piston valves. Figure 7 shows an application of them as flat double faced valves
made in the ordinary manner with the addition of the piston K2 for working the
ignition charge as before described. I. would also have it clearly understood that I
do not confine myself to particular position and method of working the compressor,
as shown in Figure 4, as it may be detached from the working cylinder and driven
from a separate crank or by a prolongation of the piston rod through the working
cylinder cover in the ordinary and usual manner. Where a double acting engine
is required, working with a charge of gas and air on each side of the piston, I
make the valves A and B in duplicate for each end of the cylinder, and provide the
compressor with a double set of suction and delivery valves c and c arranged and
worked from the cut off gear in the same manner as before described, thereby
making it double acting.
Having now described my Invention for improvements in gas engines, and in
what manner the same is to be carried into effect, what I claim is,-
1st. The general arrangement of the valves A and B shown in Figures 1, 2, 4,
and 7, whereby the admission of the charge to the cylinder and the exhaust from
it are regulated and governed by the main valve A alone and rendered constant,
the time of cut off and of ignition being determined by the cut off valve B alone,
the ignition taking place through the port a¹ in the main valve A.
2nd. The method of actuating such an arrangement of valves in combination
with them, as described and shown in Figures 1 and 2.

page_text: 3rd. The means described of supplying an ignition charge to the ignition port b³
of the valve B, as described and shown in Figures 1, 2, and 7.
4th. The arrangement of parts for causing the compressor to deliver only so
much gas and air to the receiver as is required in accordance with and governed
by the point of cut off, as described and shown in Figures 2, 3, and 4.
5th. The arrangement of parts whereby the density of the mixture of gas and
air which the compressor delivers to the receiver may be adjusted, as described and
shown in Figures 2, 5, and 6.
6th. The general arrangement of parts, as, described and shown, for the purpose
of rendering gas engines automatic in all their working detail, and controlled from
one common source.
In witness whereof, I, the said Arthur Thomas Allcock, have hereunto set my
hand and seal, this Sixth day of August, in the year of our Lord One
thousand eight hundred and eighty one.
ARTHUR THOMAS ALLCOCK. (L.S.)