Improvements in Gas Engines.
Year: 1894

page_text: Date of Application, 4th Apr., 1894
Complete Specification Left, 3rd Jan., 1895-Accepted, 9th Feb.,
1895
Improvements in Gas Engines.
I, PERCY ARCHIBALD Low, of Maybury Lodge, Thames Ditton, in the
County of Surrey, Engineer, do hereby declare the nature of this invention to be
as follows:-
:-
This invention relates to improvements in the valve arrangements of gas engines
in which a pair or pairs of cylinders are set tandem fashion that is in a line with
one another-the pistons of both being fixed on one piston rod coupled by a
connecting rod to the crank shaft of the engine-and in which the arrangement is
such that an explosion takes place once for every revolution-the explosion in the
outer end of one cylinder taking place in the outer end or that which is furthest
from the crank shaft whilst the outer end of the other is filling with a mixture of
gas and air ready for the next explosion.
In an engine where the air and gas above the pistons are alone relied on for
holding down power, to check the upward momentum of the parts, the quantity of
air cannot be varied. By my arrangement this can be done and the holding down
power only slightly diminished.
The air and gas are introduced first into the space under the top piston, and
from this receiver space are transferred alternately to the top and bottom working
cylinders. If the quantity of air and gas passing at each stroke into the receiver
space under the top piston is reduced by the governor there will be a partial vacuum
under the top piston, which will assist in holding down the parts, and partly
compensate for the loss of pressure due to compression which is at that time taking
place in one or other of the working cylinders.
For admitting the mixture of gas and air to the space below the top piston and
from thence to the working end of one or other of the cylinders and for controlling
the exhaust I use three balanced piston valves.
One balanced piston valve acted on by a governor I use for controlling the
supply of gas and air or gas only-
-one piston of the balanced valve controlling the
opening by which gas is admitted and the other the opening through which air is
This first valve
admitted to a passage leading to the second balanced piston valve.
may be dispensed with if desired and gas supply controlled by a cam in the usual
manner.
The second piston valve is worked by an eccentric on the crank shaft.
In the cylinder in which this pair of pistons work are three sets of ports the
middle set opening into the receiver space below the top piston so that this space
may always be open to the space between the pair of pistons-a second set opening
to the gas and air supply passage and closed or opened by one of the pistons of the
pair. The third set of ports opening into a passage which leads to the third
balanced valve and which is always open to the space between the two pistons of
this third balanced valve. This space may be divided by a third piston between
the other two to reduce the capacity of it.
This third set of ports is by the second piston of the balanced pair either opened
to the exhaust or to the gas and air receiver. In this way the receiver space can
by the to and fro movement of the balanced valve be alternately placed in
communication with the air and gas supply whilst at the same time the space
between the pistons of the third balanced valve is opened to the exhaust or this

page_text: space between the pistons of the third balanced valve can be put in communication
with the air and gas receiver.
The third balanced valve is worked by an eccentric which makes half a
revolution for each revolution of the crank shaft-one of the pistons of this pair
controls the opening or closing of ports leading to the working end of one cylinder-
the other controls the opening or closing of ports leading to the working end of
the other cylinder.
Consequently during one down stroke and one up stroke of the pistons, the space
between the two pistons is in connection with the working end of one cylinder
and during the next up stroke and down stroke of the pistons is in connection with
the working end of the other cylinder.
The result of this arrangement is that the receiver is on every up stroke filled
with air and gas and on every down stroke empties its charge alternately to the top
and bottom cylinders and when explosion takes place in the working end of one
cylinder gas and air are delivered into the working end of the other cylinder from
the receiver space and on the return stroke the gas and air so delivered into this
cylinder are compressed whilst the other cylinder is opened to the exhaust. The
supply of air and gas is as above stated regulated by the first balanced valve which
may be controlled either by an ordinary centrifugal governor so as to vary the
amount of opening of the ports through which gas and air are admitted or by a
governor which allows them to open fully for a greater or less period of the stroke
of the pistons of the working cylinders.
In similar engines where the gas and air are drawn directly into the cylinders
without first going into the receiver, the same arrangement of valves is used, the
ports and valves being arranged so as to take air and gas directly from the air and
gas supplies to the working ends of the cylinders.
The ignition may be done by an electric spark and can be made to take place at
any part of the stroke by the action of the governor. This can be done by
causing two brushes (one in connection with the igniting mechanism of one cylinder
and the other with the igniting mechanism of the other cylinder) to bear against
a spindle caused to revolve at half the speed of the main shalt and to alternately
come into contact with contact bars carried by the spindle one on one side of it
and the other on the other side. By placing these contact bars in a position
inclined to the axis of the spindle and by carrying the two brushes by a bar which
is parallel with the spindle and moved to and fro by the action of the governor
the brushes may by the action of the governor be made to come into contact with
the contact bars earlier or later in the stroke as may be required. Both contact
bars may be in connection with a ring surrounding the spindle and be supplied with
current through a brush constantly bearing on this ring.
Dated this 3rd day of April 1894.
Improvements in Gas Engines.
I, PERCY ARCHIBALD LOW, late of Maybury Lodge, now of Ember House
Thames Ditton, in the County of Surrey, Engineer, 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 :-
The object of this invention is to improve the arrangement of gas engines,
working on the Otto cycle, with two tandem cylinders having an explosion, once
every stroke, in alternate cylinders.
In this arrangement the compression of air is usually employed to ensure the
moving parts being kept in "constant thrust."

page_text: By my invention the air may be diminished in quantity or entirely cut off
without spoiling the constant thrust.
To accomplish this the air and gas are admitted into the space under the upper
piston, hereinafter called "the receiver," and from this are transferred alternately
to the top and bottom cylinders.
If the air and gas are cut off there will be a vacuum formed under the top
piston which will keep the moving parts from flying upwards at the top of the
stroke.
For admitting the mixture of gas and air to the space below the top piston and
from thence to the working end of one or other of the cylinders aud for controlling
the exhaust I use balanced piston valves.
of
One balanced piston valve acted on by a governor I use for controlling the supply
gas and air or gas only-one piston of the balance i valve controlling the opening
by which gas is admitted and the other the opening through which air is admitted
to a passage leading to the second balanced piston valve. This first valve may
be dispensed with if desired and gas supply controlled by a
manner.
cam in the usual
The second piston valve is worked by an eccentric on the crank shaft.
In the cylinder in which this pair of pistons work are three sets of ports the
middle set opening into the receiver space below the top piston so that this space
may always be open to the space between the pair of pistons-a second set opening
to the gas and air supply passage and closed or opened by one of the pistons of
the pair. The third set of ports opening into a passage which leads to the third
balanced valve and which is always open to the space between the two pistons of
this third balanced valve. This space may be divided by a third piston between
the other two to reduce the capacity of it.
This third set of ports is by the second piston of the balanced pair either
opened to the exhaust or to the gas and air receiver. In this way the receiver
space can by the to and fro movement of the balanced valve be alternately placed
in communication with the air and gas supply whilst at the same time the space
between the pistons of the third balanced valve is opened to the exhaust or this
space between the pistons of the third balanced valve can be put in communication
with the air and gas receiver.
The third balanced valve is worked by an eccentric which makes half a
revolution for each revolution of the crank shaft-one of the pistons of this pair
controls the opening or closing of ports leading to the working end of one cylinder-
the other controls the opening or closing of ports leading to the working end of
the other cylinder.
Consequently during one down stroke and one up stroke of the pistons, the space
between the two pistons is in connection with the working end of one cylinder and
during the next up stroke and down stroke of the pistons is in connection with the
working end of the other cylinder.
The result of this arrangement is that the receiver is on every up stroke filled
with air and gas and on every down stroke empties its charge alternately to the
top and bottom cylinders and when explosion takes place in the working end of one
cylinder gas and air are delivered into the working end of the other cylinder from
the receiver space and on the return stroke the gas and air so delivered into this
cylinder are compressed whilst the other cylinder is opened to the exhaust. The
supply of air and gas is as above stated regulated by the first balanced valve which
may be controlled either by an ordinary centrifugal governor so as to vary the
amount of opening of the ports through which gas and air are admitted or by a
governor which allows them to open fully for a greater or less period of the stroke
of the pistons of the working cylinders.
In similar engines where the gas and air are drawn directly into the cylinders
without first going into the receiver, the same arrangement of valves is used, the
ports and valves being arranged so as to take air and gas directly from the air and
gas supplies to the working ends of the cylinders.

page_text: The ignition may be done by an electric spark and can be made to take place
at any part of the stroke by the action of the governor. This can be done by
causing two brushes (one in connection with the igniting mechanism of one cylinder
and the other with the igniting mechanism of the other cylinder) to bear against
a spindle caused to revolve at half the speed of the main shaft and to alternately
come into contact with contact bars carried by the spindle one on each side of it
and the other on the other side. By placing these contact bars in a position
inclined to the axis of the spindle and by carrying the two brushes by a bar which
is parallel with the spindle and moved to and fro by the action of the governor
the brushes may by the action of the governor be made to come into contact with
the contact bars earlier or later in the stroke as may be required.
Both contact
bars may be in connection with a ring surrounding the spindle and be supplied
with current through a brush constantly bearing on this ring.
Figure 1 of the drawings annexed is a vertical section of an engine constructed
as above described.
Figures 2, 3 and 4 are diagrams illustrating the action of the valve
mechanism.
Figure 5 is a diagram view of the igniting mechanism.
In Figure 1C and C' are the working cylinders and P and P¹ the pistons,
connected by a piston rod and working on to the crank S. The crank shaft has
upon it an eccentric T which drives the valves V3 and V4 at the same number of
strokes per minute as are made by the pistons, and also a worm and wheel A¹ A¹
which drive the shaft A³ at half the number of revolutions of the main shaft and
by means of the eccentric A.' drive the valves V1 V2 at half the number of strokes
per minute that are made by the pistons.
The result of this is that during one down stroke and one up stroke of the
pistons the space X is in connection with the cylinder C by means of the port e
and the passage a during the next up stroke and down stroke of the pistons
the cylinder C is in connection with this same space by way of the port g.
The space X is opened alternately to exhaust or to the receiver R under the
top piston by means of the ports f, h, and the passage b, the valve V³ alternately
coming below and above the port h and so opening the passage b to exhaust o or to
the receiver R.
This receiver is alternately opened through the port to the passage bas
described or, when the port h is closed, it is opened by the valve V₁ to the
passage d by the port j; this will be on every up stroke and air and gas will be
drawn into the receiver R through the passage d'and the ports and i.
The result is that this receiver is on every up stroke filled with air and gas
and, on every down stroke, empties its charge alternately to the top and bottom
cylinders.
The supply of air and gas is regulated by the valves VV, hich are controlled
either by an ordinary centrifugal governor, so that they vary the amount of opening
of the ports, in for gas and for air, or by a governor which allows them to open
fully for a greater or less period of the stroke of the pistons PP.
The arrangement of electrical ignition mechanism for enabling ignition to be
effected at any part of the stroke is illustrated at Figure 5.
S' is a spindle revolving at half the speed of the crank shaft S and having
standing out from it a ring a and arms a' a². The ring and arms are kept
continuously in connection with one pole of a battery Z by a brush Z¹ bearing on
the ring. 2 are two brushes with which the arms a' a² are brought into contact
as the shaft revolves.
When the arm a¹ comes into contact with the brush a circuit is completed
through the top cylinder igniter Y and when the arm a² comes into contact with
the brush the battery circuit is completed through the bottom cylinder
ignition Y
The brushes
are connected to a rod which is moved by the governor and, as
they are moved along in a horizontal path, they will meet the arms a¹, a², earlier or

page_text: later in the revolutions of the shaft S¹ and so make ignition take place earlier or
later in the stroke of the main pistons.
In the illustrations-Figure 1 shows the pistons at top stroke.
The cylinder C is open by the port e to the space X and this space (which has
just been open to exhaust) is now just opening to the receiver R, by the ports f
and on the downward stroke therefore the cylinder C will fill with mixture from
the receiver R. Reference to Figures 2, 3, 4 will show that on the next "up
stroke this mixture is compressed, then exploded and expanded on the second
"down" stroke and, finally, exhausted on the second "up" stroke.
29
In Figure 1 the piston P¹ has just been compressing the charge and it is now
exploded and will expand on the first down stroke; the other operations follow
in the same order as in the cylinder C.
The spaces ware water jackets.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
1. The arrangement of the closed receiver between the two cylinders to which
gas and air are admitted first and transferred to the top and bottom cylinders
alternately substantially as described.
2. The employment of vacuum substantially as described as a means of ensuring
constant thrust when the supply of gas and air is cut off from the cylinders.
3. The valve arrangement substantially as described and illustrated at Figures 2, 3
and 4.
4. The arrangement of contacts substantially as described for controlling the
times of ignition.
5. The construction of gas engines substantially as herein before described.
Dated this 2nd day of January 1895.
PERCY ARCHIBALD LOW.