Improvements in Gas Engines.
Year: 1891

page_text: Date of Application, 22nd July, 1891
Complete Specification Left, 23rd May, 1392-Accepted, 25th June, 1892
Improvements in Gas Engines.
I DUGALD CLERK, of Driffold Villa, Manor Hill, Sutton Coldfield, in the
County of Warwick, Engineer, do hereby declare the nature of this invention to
be as follows:—
My invention relates to gas engines of the "Otto" cycle and its object is to
simplify the valve arrangements and dispense with the two to one gear at present
used on such engines.
In an engine to which my invention is applied I dispense with the usual valve
shaft rotating at half the rate of revolution of the engine, and actuate the exhaust
valve by means of compressed air compressed by a small piston. This piston
may be actuated from the motor piston, in which case air is compressed during
the forward stroke of the motor piston and admitted to a small piston or diaphragm
connected to the exhaust valve at or near the out end of the stroke, through a port
controlled by the small piston or the engine piston or a valve connected to either.
The compressed air opeus the exhaust valve at the end of every second stroke,
when the engine is working at full power, and the two to one action is given by
a small rotating valve, rotated by a reciprocating pawl and ratchet wheel. The
movement of the pawl on every second stroke rotates the valve through a certain
portion of the circle; and passages are so arranged in the rotating valve that every
second return stroke of the small pump piston, the cylinder is held open and air is
discharged, so that no pressure is accumulated to actuate the exhaust valve. The
exhaust valve is thereby opened on every second return stroke of the engine
gear
piston. The small pump may be driven from an eccentric, or by radial
the engine connecting rod, instead of by direct connection to the engine piston,
and this is an advantage; as the air supplied by the small piston, when it moves
with the engine piston, must be retained in the exhaust valve cylinder or chamber
until the exhausting stroke is completed, and then liberated when the piston has
completed its back stroke, by a passage controlled through either of the pistons,
or some connecting piece moved with them. When the pump is driven from an
eccentric or crank pin on the crank shaft the compression of the air may be timed
to open the exhaust valve and allow it to close at the proper time without
intermediate valves, only the ratchet rotating valve being required to cause the
small piston to miss compressing the air at every second stroke to give the two to
one action.
from
Suitable connecting passages or pipes are arranged to convey the air under
pressure to a piston acting on the exhaust valve. The small air compressing
piston is preferably arranged to work without valves other than that operated by
the pawl and ratchet, and it passes over an aperture in the side of the cylinder to
admit air, and permit the piston to move for a part of its stroke without
compressing. A similar side aperture may also be adopted in the small pump,
when actuated directly from the engine piston, to time the production of the
compression and therefore the opening of the exhaust valve; and the rotating
valve may be used to control air passing to the exhaust valve piston or diaphragm.
Instead of a rotating valve, a lift valve may be used to control the production
of pressure in the small pump cylinder, and it may be intermittently actuated by a
cam shaft rotated by pawl and ratchet.
To reduce the pressure of the residual gases upon the exhaust valve, the
engine cylinder may discharge through a port passed over by the piston at the
end of its stroke.
In this type of gas engine the charge is preferably admitted by an automatic

page_text: valve operated by the suction, and a gas mixing valve also automatic may be
used below the inlet valve next the cylinder.
The gas valve may be arranged to open, at every opening of the exhaust valve
and be held open by a catch or lever controlled by governor; or the opening may
be effected by the governor holding open the rotating valve to prevent compression
of air; this may be effected by lifting the pawl out of gear to leave the valve
open, or by opening another valve by the governor.
Sometimes govern by lifting out the pawl, so as to leave the rotating valve
shut, and in this case I close the gas inlet valve by governor so that an air charge
is drawn into the cylinder and discharged at every revolution of the engine. An
ordinary centrifugal governor may be adopted; but I prefer to use an oscillating
governor consisting of a balance wheel returned against a fixed buffer or stop, by a
spiral or other spring. A suitable connection to a reciprocating piece on the
engine moves the wheel for a portion of the stroke and when the stroke terminates
the momentum of the wheel causes it to continue moving against the spring. The
higher the speed of the engine the further the distance moved by the wheel against
the spring, because greater speed imparts greater energy to the wheel. If the
wheel moves beyond a certain distance it operates a catch plate or trigger which
controls the gas valve and other valves if required.
Air pressure from the small cylinder may also operate the gas supply valve, so
that air admitted under pressure into a small chamber by a check valve if required
actuates a diaphragm or piston to open the gas valve, and the governor acts by
opening a valve to the atmosphere which prevents the accumulation of pressure and
so allows the gas valve to shut.
To enable my improved gas engine to be started without manual labour I arrange
an auxiliary cylinder of suitable capacity with a free piston operated by lever
and piston rod. This piston is travelled by lever to one end of its stroke and takes
in a charge of gas and air, preferably from the gas and air suction valve, between
it and the upper lift valve; on the return stroke begun by hand lever the piston
forces in its charge of gas and air to the compression space by the upper valve,
taking in a charge of gas and air on the other side of the piston. When a certain
part of the stroke has been accomplished, the piston passes, a flame port and the
mixture is ignited and drives the piston completely to the end of its stroke
compressing the gas and air into the engine combustion space and causing the
mixture to ignite at the igniter tube. The engine crank has meantime been standing
over the centre on the explosion stroke, and the explosion starts it into rotation.
The starting piston may be kept moving by connection with the engine until
sufficient speed has been attained although in some cases, one ignition may be
enough to set it into sufficiently rapid motion to take the compression.
Dated this 21st day of July 1891.
MARKS & CLERK,
13, Temple Street, Birmingham, Agents for the Applicant.
MARKS & CLERK,
13, Temple Street, Birmingham, Agents for the Applicant.
COMPLETE SPECIFICATION.
Improvements in Gas Engines.
1, DUGALD CLERK, of Driffold Villa, Manor Hill, Sutton Coldfield, in the
County of Warwick, 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 :—
My invention relates to gas engines of the "Otto" cycle and its object is to
simplify the valve arrangements and dispense with the two to one gear at present
used on such engines.
In an engine to which my invention is applied I dispense with the usual valve
shaft rotating at half the rate of revolution of the engine, and actuate the exhaust
valve by means of compressed air compressed by a small piston. This piston may

page_text: be actuated from the motor piston, in which case air is compressed during the
forward stroke of the motor piston and admitted to a small piston or diaphragm
connected to the exhaust valve at or near the out end of the stroke, through a port
controlled by the small piston or the engine piston or a valve connected to either.
The compressed air opens the exhaust valve at the end of every second stroke when
the engine is working at full power, and the two to one action is given by a small
rotating valve, rotated by a reciprocating pawl and ratchet wheel.
Referring to the accompanying sheet of drawings which illustrate my invention,
Figure 1 is a side elevation part in section showing my new gear.
Figures 2, 3 and 4 are sections showing different positions of the rotating
valve.
Figure 5 shows on a larger scale my pawl and ratchet wheel arrangement for
rotating the valve.
Figure 6 shows a mode of connecting between the pawl and the gas valve,
so that when the pawl is raised out of gear by the governor the gas valve
is closed.
Figure 7 is a plan showing the small piston connected to main piston.
Figure 8 shows an arrangement of rotating ratchet wheel, and lift valve, to
operate the exhaust valve piston.
Figure 9 shows the ratchet with a governing disc on a larger scale.
The movement of the pawl K, on every second, that is every "in" stroke of the
engine, rotates the plug valve S through a certain portion of the circle; and
passages are so arranged in the rotating valve, that every second return stroke of
the small pump piston A, the cylinder is held open, and air is discharged, so that
no pressure is accumulated to actuate the exhaust valve D by its loose piston C.
The exhaust valve D is thereby opened on every second return stroke of the engine
piston. The small pump may be driven from an eccentric, whose centre is shown
at G Figure 1, cr by radial gear from the engine connecting rod, instead of by
direct connection to the engine piston, and this is an advantage; as the air
supplied by the small piston A to the loose piston C when it moves with the engine
piston, must be retained in the exhaust valve cylinder or chamber, under the
piston C, until the exhausting stroke is completed, and then liberated when the
engine piston has completed its back stroke by a passage controlled through either
of the pistons or some connecting piece moved with them. When the pump A is
driven from an eccentric or crank pin on the crank shaft, the compression of the
air may be and is timed as shown at. Figure 1, to open the exhaust valve D and
allow it to close at the proper time without intermediate valves, only the ratchet
rotating valve S being required to cause the small piston A to miss compressing the
air at every second stroke, to give the two to one action.
Suitable connecting passages or a pipe such as B is arranged to convey the air
under pressure from the small cylinder a, to a piston C, acting on the exhaust
valve D.
The small air compressing piston is preferably arranged to work without valves
other than that operated by the pawl K, and ratchet wheel L, and it passes over an
aperture in the side of the cylinder a, to admit air, and permit the piston to move
for a part of its stroke without compression. This aperture or gutter is cut in the
cylinder a, at the end nearest the crank and is uncovered by the piston A when
the piston is full out. A similar side aperture may also be adopted in the small
pump A when actuated directly from the engine piston as shown at Figure 7, to
time the production of the compression, and therefore the opening of the exhaust
valve; and the rotating valve may be used to control air passing to the exhaust
valve piston or diaphragm.
Instead of a rotating valve, a lift valve S (Figure 8) may be used to control the
production of pressure in the small pump cylinder, and it may be intermittently
actuated by a cam shaft T rotated by a pawl and ratchet wheel L. In either case
the piston A is caused to alternately compress air, and discharge it to the
atmosphere. This is clearly shown at Figures 2, 3 and 4. In Figure 2 the ratchet

page_text: wheel L has been turned by the pawl K, to leave the passager open to the pipe B,
but closed to the passage V leading to the atmosphere. The piston A thus com-
presses the air contained in the cylinder a, and forces the compressed air through
the pipe B to lift the valve D by the piston C. When the ratchet wheel has
turned the valve S to the position shown at Figure 3, then no pressure accumulates
in the cylinder a, as it is discharged to atmosphere by the passages t and r in the
plug valve and by the passage V. The valve D then remains closed and a
compression stroke occurs.
To reduce the pressure of the residual gases upon the exhaust valve, the engine
cylinder may discharge through a port passed over by the piston at the end of its
stroke in a well known manner.
In this type of gas engine the charge is preferably admitted by an automatic
valve F, operated by the suction and a gas mixing valve E, also automatic, may be
used below the inlet valve next the cylinder.
The gas valve may be arranged to open at every opening of the exhaust valve,
and be held open by a catch or lever controlled by governor as shown at Figure 6 ;
or the opening may be effected by the governor holding open the rotating valve to
prevent compression of air; this may be effected by lifting the pawl out of gear
to leave the valve open, or by opening another valve by the governor. Sometimes
I govern by lifting out the pawl, so as to leave the rotating valve shut, and in this
case I close the gas inlet valve by governor, so that an air charge is drawn into
the cylinder, and discharged at every revolution of the engine. An ordinary
centrifugal governor may be adopted, and the link M may connect to that governor
to lift the pawl K out of gear with the ratchet wheel L. The disc N' carries a
ledge N, and both disc and ledge rotate with the ratchet wheel L; the pin con-
necting the rod M to the pawl Kis projected, so as to pass under the ledge N and
so long as it is under that ledge the governor cannot raise the pawl K out of gear
with L. When the ledge is passed, however, the governor is free to raise the
pawl. The rod O connects between the link M, and the valve F and a pin in the
link M slides under the rod O or in a slot in the said rod, to allow of its oscillation
with the pawl K.
I prefer, however, to use an oscillating governor consisting of a balance wheel R
(Figure 9) returned against a fixed buffer or stop R³ by a spiral or other spring R'.
A suitable connection Q, to a reciprocating piece on the engine moves the wheel R
for a portion of the stroke, and when the stroke terminates, the momentum of the
wheel causes it to continue moving against the spring R². The higher the speed of
the engine the further the distance moved by the wheel against the spring R³,
because greater speed imparts greater energy to the wheel. If the wheel moves
beyond a certain distance it operates a catch plate or pin K², which controls the
pawl K by the incline R¹. This incline is moved forward when governing in
the direction of the arrow, and coming in contact with the pin K³ it raises the
pawl K.
Air pressure from the small cylinder may also operate the gas supply valve so
that air admitted under pressure into a small chamber by a check valve if required,
actuates a diaphragm or piston to open the gas valve, and the governor acts by
opening a valve to the atmosphere, which prevents the accumulation of pressure
and so allows the gas valve to shut.
In Figure 7, D is the engine connecting rod, and motion is imparted by it, direct
to the piston A, which is there of the same stroke as the engine piston. The
rod K' in all the drawings operates the pawl K and the ratchet wheel L.
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. In a gas or like engine, the method of operating an exhaust valve by com-
pressed air, compressed by a small separate piston connected to any moving part
of the engine, substantially as and for the purposes hereinbefore described,

page_text: 2. In a gas or like engine the combination of a small air cylinder and piston, a
pawl and ratchet wheel, a rotating plug or other valve and a piston operated
exhaust valve to obtain the alternate action of the exhaust valve operating
pneumatically, substantially as and for the purposes hereinbefore described and
illustrated in the drawings.
3. In a gas or like engine, a balance wheel governor acting by impetus, and
lifting a pawl out of a ratchet wheel, substantially as and for the purposes herein-
before described and illustrated in the drawings with reference to Figure 9.
Dated this 21st day of Mar 1892
MARKS & CLERK,
13, Temple Street, Birmingham, Agents for the Applicant.