Year: 1895

page_text: We, DUGALD CLERK, of Driffold Villa, Sutton Coldfield, in the County of
Warwick, Engineer, and FREDERICK WILLIAM LANCHESTER, of 13 Bedford
Row, London W.C. Engineer, do hereby declare the nature of this invention to be
as follows:
Our invention relates to gas and like engines and is in part applicable to
compound engines.
The object of the invention is to reduce the loss of heat to the sides of the
cylinder and so increase the economy of the engines.
In compression gas engines as at present constructed the cylinder is charged
with a mixture of gas and air at or near atmospheric pressure and the piston
compresses the mixed gases into a clearance space at the end of the cylinder. This
compressed mixture is ignited and furnishes the motive power.
It has been proved by Clerk and others that the theoretical efficiency of a gas
engine of this type depends upon the ratio of the compression space to the total
volume of the cylinder and space.
We have discovered that this theoretical efficiency is constant given a certain
ratio between clearance space and cylinder whatever the atmospheric pressure
be before the piston begins to compress the charge into the clearance space, and
we have also found by experiment that the loss of heat to the sides of the cylinder
is approximately the same in a given space whether the mixture be compressed or
not, and we find that at high pressures of compression the proportional loss of
heat is much less than at low pressures.
Part of our invention consists in charging the cylinder of a gas engine with
mixture at a higher pressure than atmosphere to begin with so that while the piston
is at or near the end of its stroke the contents are at a higher pressure than
atmosphere. After the piston has compressed the gases into the space at the end
of the cylinder the pressures obtained are therefore much greater and the pressure
of explosion is also greater.
We find that in an ordinary Otto cycle engine the economy of gas consumption
and the power exerted may be greatly improved by displacing all the exhaust
products and by charging the cylinder while the piston is at the out end of its
stroke with gases compressed to a notable extent above atmosphere. We also find
that in a compound engine having the compression space and cylinder of about the
ratio at present used in ordinary Otto engines viz. the compression space about
one third of the volume swept by the piston, that we can advantageously super-
compress to about 15 lbs. above atmosphere, so that the atmospheric pressure as it
may be called existing in the cylinder to begin with about 30 lbs. instead of 15.
By so super-compressing we readily obtain maximum explosion pressures of 600 lbs.
per square inch giving an average available pressure throughout the stroke of about
200 lbs. per square inch and providing heavy exhaust pressures to be utilized in the
second cylinder.
In one method of carrying the invention into effect as applied to an Otto cycle
gas engine, devices are applied to displace the exhaust gases in the clearance space
by air and to supply the engine cylinder with a charge at a higher pressure than

page_text: atmosphere. For this purpose a double acting compressing pump is added to the
engine and actuated in any convenient manner either from the crank shaft by a
separate crank pin or from the motor piston to nove in time with it.
Two chambers are arranged one of which communicates with the ordinary
charge inlet valve of the engine and the other communicates with a special valve
preferably a lift valve opening into the clearance space. The double acting pump
is caused on one side to pump into the first mentioned chamber a mixture of gas
and air and on the other side to pump into the second chamber air alone. The
pressure in the first chamber is raised to five, ten, fifteen pounds above atmosphere
or any other pressure at which it is desired to supply the engine cylinder. The
air pressure in the second chamber is raised to a few pounds above atmosphere say
from two to five, just sufficient to allow the air to blow through the cylinder to
clear out the exhaust products.
When the motor piston makes its exhausting stroke at a certain point the air
from the air chamber is blown through the cylinder to displace the exhaust gases
through the exhaust valve. The exhaust valve is suitably placed for this purpose
sometimes in the side of the cylinder. At a certain point the exhaust valve closes
and pure air remains in the cylinder and is compressed to the end of the stroke
into the compression space. The compression is arranged so that the pressure just
rises to the same as that in the first mentioned chamber. The gas and air inlet
valve is then opened and the motor piston moves forward taking in a charge of
gas and air at five, ten, fifteen pounds more or less above atmosphere as determined
by the pressure in the chamber.
The engine is thus charged with gas and air at a higher pressure than atmosphere
and when the piston completes its usual compression stroke the compression pressure
attained is proportionally higher.
In another arrangement the additional pump also preferably double acting is
operated by a crank pin at about right angles to the motor crank pin and it is
caused to pump air only.
Inlet valves are arranged at both ends of the pump cylinder, preferably
automatic, and one end of the said pump cylinder communicates by a pipe or
passage with the inlet valve of the motor cylinder while the other end com-
municates by a pipe or passage with a lift valve opening into a port in the side
of the cylinder.
The action is as follows-When the motor piston has nearly completed its
exhausting stroke the pump piston is compressing air on one side into the engine
inlet valve passage or pipe; the inlet valve is opened while the exhaust valve is
still open and air is discharged into the clearance space by the pump and displaces
the burned gases filling the space with air. Gas may also be injected if desired.
The
The motor piston then proceeds on its charging stroke and a mixture of gas and
air is drawn in at atmospheric pressure. When the charging stroke is almost
complete the air pump piston on its other side begins compressing air into the
cylinder through the check valve and compresses its air charge into the cylinder
before the motor piston has returned much on its compressing stroke.
cylinder is thus charged at the out end of its stroke at a higher pressure than
atmosphere. The extra air charge is preferably so injected into the cylinder
as to thoroughly mix with the gas and air already in the cylinder. The charge
is passed in at a position such as to avoid disturbing the explosive mixture in the
ignition port.
The mixture drawn into the cylinder by the motor piston is preferably rich in
gas and may indeed be overcharged with gas in order to supply sufficient gas for
the super-compressed charge.
The pump is proportioned to produce the desired amount of super-compression.
During the idle strokes of the air pump the air is simply compressed and
expanded into and from the respective pipes or passages.
According to this arrangement one side of the piston may also be used both for
scavenging and super-compression.

page_text: In another arrangement a loose piston is operated on one side by the exhaust
gases from the engine cylinder and air is compressed by the movement of the said
piston through two clack valves into two chambers; one of these chambers opens
or communicates to the gas and air inlet valve and the other communicates with an
automatic lift valve opening into the cylinder by a port uncovered by the motor
piston at the out end of its stroke.
The first chamber discharges its air to clear out the exhaust gases from the
clearance space and the second chamber discharges its air charge when the motor
charging stroke is complete and so gives the desired pressure above atmosphere at
the end of the stroke. The loose piston is operated by the exhaust gases admitted
under it and it moves till a part at the side of its cylinder is uncovered when the
gases escape to the atmosphere. The piston remains up till the exhaust is
discharged when it falls again the gases under it also passing to atmosphere by a
regulated aperture. The piston is properly cushioned at both ends and an inlet
valve is provided as well as two discharge valves to the chambers.
The loose piston may be caused to perform the operations of clearing and
super-compression without discharge valves by arranging ports in the side and
suitably timing the flight of the piston to charge the chambers as required in
succession.
The principle of super-compressing is of great advantage when applied to
compound gas engines as the exhaust pressure is very high at the end of the motor
expansion stroke.
It may be applied in many modifications giving very great economy of gas
consumption.
One engine carrying it into effect is constructed and operates as follows-Two
cylinders are preferably used; one the high pressure cylinder is single acting
operating on the Otto cycle; the other the low pressure cylinder is double acting
and one end serves as the low pressure motor cylinder while the other serves as an
air pump to supply air for scavenging and super-compressing.
The end through which the piston rod passes is preferably the pump end. The
high pressure crank leads by a right angle or a little more, and as the high
pressure piston approaches the end of its stroke it runs over a port leading directly
into the motor end of the low pressure cylinder in which the piston is just beginning
its out stroke. The gases are expanded in the low pressure cylinder while the
high pressure piston is crossing the port to open it and returning to close it. The
high pressure exhaust valve is then opened and the motor piston is ready to return
discharging the exhaust gases. Before this however the pump side of the low
pressure piston has compressed a charge of air into a chamber connected with the
engine feed valve and when the said inlet or feed valve is opened air rushes into
the engine clearance space and discharges the exhaust gases by the exhaust valve.
The high pressure piston thus proceeds on its charging stroke with pure air in the
space, and it draws into the cylinder a mixture of gas and air preferably rich or
even overcharged with gas. During the completion of the charging stroke the
port opening to the low pressure cylinder is closed by a rotating or other straight-
way valve and the motor end of the low pressure cylinder is charged with air
sucked through a suitable valve preferably a lift valve to be discharged again
through an exhaust valve which in this cylinder is operated at every stroke.
While the high pressure piston crank is crossing the out centre the air charge in the
front or pump end of the low pressure cylinder is again being compressed and as the
feed valve is closed the air passes by a pipe or passage from the air chamber to a
lift valve opening into a port discharging into the high pressure cylinder at a point
towards the out end of the stroke. The charge in the high pressure cylinder is
thus super-compressed and may be raised to any pressure desired depending on the
relative dimensions of the pump and motor cylinders.
The high pressure piston then proceeds on its compression stroke and compresses
the charge into the compression space. The ignition is caused in any usual
manner, and the expansion high pressure stroke follows, succeeded by the expansion

page_text: low pressure stroke of the low pressure piston as the high pressure crank crosses the
out centre.
The inlet clack or other valve for the air pump end may be caused to serve the
feed chamber also.
In an engine of this kind a super-compression of 15 lbs. per square inch can be
successfully applied giving pressures of nearly 170 lbs. per square inch upon
complete compression and pressures of explosion of about 500 to 600 lbs. per
square inch. The average working pressure on the high pressure stroke will thus
exceed 200 lbs. per square inch and the exhaust gases will enter the low pressure
cylinder for expansion at a pressure of about 100 lbs. per square inch above
atmosphere.
The governing of such an engine may be accomplished in the usual manner by
cutting off the gas.
The high pressure and low pressure cylinders and cranks are of course pro-
portioned to take these high pressures.
Such an engine will give an advantage of about 30 % in gas consumption.
Part of the invention consists in this super-compression and pumping in stages
as applied to gas engines whether of the simple or compound type and part consists
in mechanism of application.
The invention may be applied to impulse every revolution engines and to
petroleum engines.
The scavenging and super-compression may also be performed by a loose piston
coupled to an air pump piston and so arranged that one stroke is made by the
pressure of the exhaust gases while the return stroke is made by an air cushion
compressed on the first stroke. One stroke forces air at one side of the pump
piston for scavenging and the return stroke forces air from the other side of the
pump piston for super-compressing.
Inflammable mixture may be used instead of air.
MARKS & CLERK,
18 Southampton Buildings, London, W.C., and
13 Temple Street, Birminghain, Agents for the Applicants.
MARAD & CLERK,
18 Southampton Buildings, London, W.C., and
13 Temple Street, Birminghain, Agents for the Applicants.
COMPLETE SPECIFICATION.
Improvements in Gas and like Engines.
We, DUGALD CLERK, of Driffold Villa, Sutton-Coldfield, in the County of
Warwick, Engineer, and FREDERICK WILLIAM LANCHESTER, of 13 Bedford
Row, London W.C. 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 :—
Our invention relates to gas and like engines and is in part applicable to
compound engines.
The object of our invention is to reduce the loss of heat to the sides of the
cylinder and so increase the economy of the engine.
In compression gas engines as at present constructed the cylinder is charged
with a mixture of gas and air at or near atmospheric pressure and the piston
compresses the mixed gases into a clearance space at the end of the cylinder. This
compressed mixture is ignited and furnishes the motive power.
.
It has been proved by Clerk and others that the theoretical efficiency of a gas
engine of this type depends upon the ratio of the compression space to the total
volume of the cylinder and space.
We have discovered that this theoretical efficiency is constant given a certain
ratio between clearance space and cylinder, whatever the atmospheric pressure be,

page_text: before the piston begins to compress the charge into the clearance space, and we
have also found by experiment that the loss of heat to the sides of the cylinder is
approximately the same in a given space whether the mixture be compressed or
not, and we find that at high pressures of compression the proportional loss of
heat is much less than at low pressures.
Part of our invention consists in charging the cylinder end of a gas engine with
mixture at a higher pressure than atmosphere to begin with, so that while the
piston is at or near the end of its stroke the contents are at a higher pressure thin
atmosphere. After the piston has compressed the gases into the space at the end
of the cylinder the pressures obtained are therefore much greater and the pressure
of explosion is also greater.
We find that in an ordinary "Otto" cycle engine the economy of gas con-
sumption and the power exerted may be greatly improvel by displacing all the
exhaust products and by charging the cylinder while the piston is at the out end
of its stroke with gases compressed to a notable extent above atmosphere. We
also find that in a compound engine having the compression space and cylinder of
about the ratio at present used in ordinary Otto cycle engines viz. :-the com-
pression space about one third of the volume swept by the piston, that we can
advantageously super-compress to about 15 lbs. above atmosphere, so that the
atmospheric pressure as it may be called existing in the cylinder to begin with is
about 30 lbs. instead of 15. By so super-compressing we readily obtain maximum
explosion pressures of 600 lbs. per square inch giving an average available pressure
throughout the stroke of about 200 lbs. per square inch and providing heavy
exhaust pressures to be utilized in the second cylinder.
In one method of carrying the invention into effect as applied to an Otto cycle
gas engine, devices are applied to displace the exhaust gases in the clearance space
by air and to supply the engine cylinder with a charge at a higher pressure than
atmosphere. For this purpose a double acting compressing pump is added to the
engine and actuated in any convenient manner either from the crank shaft by a
separate crank pin or from the motor piston to move in time with it.
Two chambers are arranged one of which communicates with the ordinary charge
inlet valve of the engine and the other communicates with a special valve preferably
a lift valve opening into the clearance space. The double acting pump is caused
on one side to pump into the first mentioned chamber a mixture of gas and air and
on the other side to pump into the second chamber air alone. The pressure in the
first chamber is raised to five, ten, fifteen pounds above atmosphere or any other
pressure at which it is desired to supply the engine cylinder. The air pressure in
the second chamber is raised to a few pounds above atmosphere say from two to
five, just sufficient to allow the air to blow through the cylinder to clear out the
exhaust products.
When the motor piston makes its exhausting stroke, at a certain point the air
from the air chamber is blown through the cylinder to displace the exhaust gases
through the exhaust valve. The exhaust valve is suitably placed for this purpose
sometimes in the side of the cylinder. At a certain point the exhaust valve closes
and pure air remains in the cylinder and is compressed to the end of the stroke into
the compression space. The compression is arranged so that the pressure just rises
to the same as that in the first mentioned chamber. The gas and air inlet valve is
then opened and the motor piston moves forward taking in a charge of gas and air
at five, ten, fifteen pounds more or less above atmosphere as determined by the
pressure in the chamber.
The engine is thus charged with gas and air at a higher pressure than atmosphere
and when the piston completes its usual compression stroke the compression pressure
attained is proportionally higher.
In another arrangement the additional pump also preferably double acting is
operated by a crank pin at about right angles to the motor crank pin and it is
caused to pump air only.
Inlet valves are arranged at both ends of the pump cylinder, preferably automatic,

page_text: and one end of the said pump cylinder communicates by a pipe or passage with the
inlet valve of the motor cylinder while the other end communicates by a pipe or
passage with a lift valve opening into a port in the side of the cylinder.
The action is as follows:-When the motor piston has nearly completed its
exhausting stroke the pump action is compressing air on one side into the engine
inlet valve passage or pipe; the inlet valve is opened while the exhaust valve is
still open and air is discharged into the clearance space by the pump and displaces
the burned gases filling the space with air. Gas may also be injected if desired.
The motor piston then proceeds on its charging stroke and a mixture of gas and
air is drawn in at atmospheric pressure. When the charging stroke is almost
complete the air pump piston on its other side begins compressing air into the
cylinder through the check valve and compresses its air charge into the cylinder
before the motor piston has returned much on its compressing stroke. The cylinder
is thus charged at the out end of its stroke at a higher pressure than atmospheric.
The extra air charge is preferably so injected into the cylinder as to thoroughly mix
with the gas and air already in the cylinder. The charge is passed in at a position
such as to avoid disturbing the explosive mixture in the ignition port.
The mixture drawn into the cylinder by the motor piston is preferably rich in gas
and may indeed be overcharged with gas in order to supply sufficient gas for the
super-compressed charge.
The pump is proportioned to produce the desired amount of super-compression.
During the idle strokes of the air pump the air is simply compressed and expanded
into and from the respective pipes or passages.
According to this arrangement one side of the piston may also be used for
both scavenging and super-compression.
In another arrangement a loose piston is operated on one side by the exhaust gases
from the engine cylinder and air is compressed by the movement of the said piston
through two clack valves into two chambers; one of these chambers opens or
communicates to the gas and air inlet valve and the other communicates with an
automatic lift valve opening into the cylinder by a port uncovered by the motor
piston at the out end of its stroke.
The first chamber discharges its air to clear out the exhaust gases from the
clearance space and the second chamber discharges its air charge when the motor
charging stroke is complete and so gives the desired pressure above atmosphere at
the end of the stroke. The loose piston is operated by the exhaust gases admitted
under it and it moves till a port at the side of its cylinder is uncovered when the
gases escape to the atmosphere. The piston remains up till the exhaust is discharged
when it falls again the gases under it also passing to atmosphere by a regulated
aperture. The piston is properly cushioned at both ends and an inlet valve is
provided as well as two discharge valves to the chambers.
The loose piston may be caused to perform the operations of clearing and super-
compression without discharge valves by arranging ports in the side and suitably
timing the flight of the piston to charge the chambers as required in succession.
The principle of super-compression is of great advantage when applied to
compound gas engines as the exhaust pressure is very high at the end of the motor
expansion stroke.
It may be applied in many mcdifications giving very great economy of gas
consumption.
One engine carrying the invention into effect is illustrated in the accompanying
drawings:-
--
Figure 1 is a part sectional elevation on A B of the engine.
Figure 2 is a side elevation.
Figure 3 is a sectional plan.
Figure 4 is a partial end elevation.
Figure 5 is a part sectional elevation of a modification of the valve gear.
Referring to Figures 1, 2, 3, and 4.-Two cylinders are preferably used; one
the high pressure cylinder C is single acting in the "Otto "cycle; the other the

page_text: low pressure cylinder D is double acting, its inner end E serves as the low pressure
motor cylinder, while the outer end F serves as an air pump to supply air for
scavenging when used, and super-compressing.
The end F through which the piston trunk C passes is preferably the pump end
as shown in Figure 3. The high pressure crank H leads by a right angle or a
little more the low pressure crank I and as the high pressure piston J approaches
the ends of its working outstroke it runs over a port K leading into the motor
end E of the low pressure cylinder in which the low pressure piston L is just
beginning its out stroke. The intercepting valve M which may be a rotating, or a
straight way valve as shown, (preferably operated by the rod N and lever O from
the cam shaft P) is held open at this time, and the gases, are thus allowed to
expand into the low pressure cylinder and perform work; this taking place while
the high pressure piston J is crossing the port K to open it and returning to close
it. The high pressure exhaust valve Q (preferably operated by lever R from the
cam shaft P) is now opened and the piston J returns discharging the exhaust
gases. The high pressure piston J now proceeds in its out charging stroke and
draws into its cylinder C a mixture of gas and air preferably rich or even over-
charged with gas. The intercepting valve M is kept closed except when the
piston Lis making its working out stroke expanding the hot gases from the high
pressure cylinder.
The pump side F of the low pressure piston L is charged with air through the
air valve S by way of the port T, see Figure 1, during its exhaust stroke and just
as the high pressure crank H is crossing the out centre after drawing in its charge
of gas and air, the piston L delivers the air charge by way of the port T and
through the valve U which is lifted at the proper time; (by a lever V from the cam
shaft P) into the high pressure cylinder C. The charge in the high pressure
cylinder is thus super-compressed and may be raised to any pressure desired
depending on the relative dimensions of the pump and motor cylinders.
The high pressure piston J then proceeds in its compression stroke and further
compresses the charge into the compression space. The ignition is caused in any
usual manner, and the expansion high pressure stroke follows, succeeded by the
expansion low pressure stroke, of the low pressure piston as the high pressure
crank J crosses the out centre.
The valve gear used in this engine is preferably operated by a two to one
gearing from the crank shaft. In the accompanying drawings we illustrate a two
to one chain gear W W Figure 2. The inner end of the low pressure cylinder is
exhausted on the completion of its working stroke by the exhaust valve X, this
valve being actuated by a cam and lever from the cam shaft P. On the idle stroke
of the low pressure piston L at the inner end we preferably allow it to suck in air
and discharge it again.
The gas and air feed valves for the high pressure cylinder are shown clearly at
Figure 2. Y is the gas valve and Z the air and gas feed valve. These are
actuated from the cam shaft P.
Figure 5 illustrates a slight alteration in the engine described and illustrated at
Figures 1, 2, 3, and 4 by which all the products of combustion in the high pressure
cylinder left after expansion may be scavenged out. A sina! chamber A¹ is in
communication with the port T leading to the pump side of the low pressure
cylinder D and the idle stroke of this pump side is used to compress a charge into
the chamber A¹ and the charge being previously sucked in by the automatic lift
valve B¹; just as exhaust is being completed in the high pressure cylinder the air
is admitted through the feed valve Z by way of the pipe C and thus sweeps out all
the exhaust products.
In an engine of this kind a super-compression of 15 lbs. per square inch can be
successfully applied giving pressures of nearly 170 lbs. per square inch npon
complete compression and pressures of explosion of about 500 to 600 lbs. per square
inch. The average working pressure on the high pressure stroke will thus exceed
200 lbs, per square inch and the exhaust gases will enter the low pressure

page_text: cylinder for expansion at a pressure of about 100 lbs. per square inch above
atmosphere.
The governing of such an engine may be accomplished in the usual manner by
cutting off the gas.
The high pressure and low pressure cylinders and cranks are of course
proportioned to take these high pressures.
Such an engine will give an advantage of about 30% in gas consumption.
Part of the invention consists in this super-compression and pumping in stages as
applied to gas engines whether of the simple or compound type and part consists in
mechanism of application.
The invention may be applied to impulse every revolution engines and to
petroleum engines.
The scavenging and super-compression may also be performed by a loose piston
coupled to an air pump piston and so arranged that one stroke is made by the
pressure of the exhaust gases while the return stroke is made by an air cushion
compressed on the first stroke. One stroke forces air at one side of the pump
piston for scavenging and the return stroke forces air from the other side of the
pump piston for super-compressing.
Inflammable mixture may be used instead of air
Having now particularly described and ascertained the nature of our inven-
tion and in what manner the same is to be performed, we declare that what we
claim is :-
1. In a compound gas and like engine charging a gas engine cylinder while the
piston is at or near the end of its outstroke with inflammable mixture at a
higher pressure than atmosphere so that on the completion of the compressing
stroke of the power piston the charge is compressed to a high pressure and
high explosion and working pressures are obtained thereby diminishing the
proportional loss of heat to the sides of the cylinder substantially as hereinbefore
described.
2. In a compound gas or like engine, the combination of a high pressure cylinder
taking in its charge of gas mixed with air at atmosphere pressure and an air pump
forcing a charge of air into the said charge at or near the out end of the piston
stroke to raise the pressure in the cylinder above atmosphere before the ordinary
return compressing stroke begins, so that on the completion of the said com-
pressing stroke the charge is compressed to a high pressure and high explosion and
working pressures are obtained substantially as and for the purposes hereinbefore
described.
3. In a compound gas or like engine, the combination of a high pressure cylinder
supercharged with gas and air as described and claimed in the preceding Claim 1
or 2 and a low pressure cylinder supplied from the high pressure cylinder by way
of a port over run by the high pressure piston, the low pressure cylinder at one end
acting as an air pump to supercharge the high pressure cylinder substantially as
described.
4. In a compound gas or like engine operating the air compressing pump by
exhaust pressure as herein before described.
5. The compound gas engine hereinbefore described with reference to the
accompanying drawings
Dated this 96th day of Sentember 1805
MARKS & CLERK,
18 Southampton Buildings, London, W.C., and
13 Temple Street, Birmingham, Agents for the Applicants.