IMPROVEMENTS IN GAS ENGINES
Year: 1882

page_text: LETTERS PATENT to Alexander Melville Clark of the firm of A. M and
W. Clark of 53 Chancery Lane in the County of Middlesex, Fellow of the
Institute of Patent Agents for an Invention of IMPROVEMENTS IN GAS
ENGINES Communicated to him from abroad by Victor Julien Laurent, of
Paris, France
PROVISIONAL SPECIFICATION left by the said Alexander Melville Clark
at the Office of the Commissioners of Patents on the 22nd December 1882.
ALEXANDER MELVILLE CLARK of the firm of A. M. and W. Clark of 53 Chancery
Lane in the County of Middlesex, Fellow of the Institute of Patent Agents,
'IMPROVEMENTS IN OAS ENGINES "
[Communicated to him from abroad by
Victor Julien Laurent, of Paris, France].
This Invention relates to an improved gas engine of which the following is the
general principle of working.
A mixture of gas and air in proportions regulated by butterfly valves is drawn
by a piston into a cold cylinder and there compressed by said piston, whilst an
abundant spray of cold water is injected into the cylinder to prevent the heating
of the gases. The gases compressed to a high pressure are then conducted to a
regenerator wherein their temperature is raised from two to three hundred degrees
Centigrade by utilising the sensible heat of the gases which after performing their
quota of work are expelled from the engine. The gases on leaving the regenerator
enter a heated cylinder by a valve which remains open during a portion only of
the stroke of the piston. On entering the cylinder the gases come in contact with
platinum wire rendered incandescent by an electric current, whereby the gases are
ignited. The platinum wire is coiled in a series of concentric circles so as to be
distributed uniformly over the whole area of the end of the cylinder. Each point
of the incandescent wire gives rise by contact with a series of molecules of the
gaseous matter in motion, to a jet of flame which gradually enlarges from the
point of ignition, so that the several jets of flame which emanate from the spiral
wire, unite at a little distance therefrom and the combustion which continues
during the whole time of admission of the gases, is complete almost immediately

page_text: after the admission is cut off, that is to say, from the time expansion commences.
This expansion terminates with the forward stroke of the piston, and during the
backward stroke the exhaust valve opens and the gaseous mixture, which by
expansion has cooled down to about 300°, passes out of the cylinder and escapes
into the atmosphere after having first passed through the regenerator above
mentioned where it gives up its sensible heat.
It is now generally thought that the heat is better utilised when the gaseous
mixture supplied to gas engines contains only just the necessary proportion of
combustible gas to ensure ignition, than when a mixture rich in inflammable gas
is employed, on condition that combustion terminates at the commencement of
expansion.
Now in poor gases the flame is propagated at a comparatively slow rate, so that
in using such a mixture in an engine in which ignition only takes place after the
cut off and by the contact of a single, or of a small number of incandescent points,
the combustion would not even be terminated at the end of the stroke of the
piston whose speed is necessarily high. The above described method of effecting
ignition is therefore intended to obviate this objection.
When a rich mixture is employed in which the propagation of the flame is rapid,
the temperature of combustion is very high and a considerable portion of the heat
generated is lost by radiation, and this is apparently the cause of poor mixtures
being advantageous of use in these motors.
The improved gas engine of this Invention is illustrated in the accompanying
drawings. In Figures 1 and 2 which show respectively an elevation and vertical
section of the engine, A Bare two cylinders joined together end to end in the saine
axial line. As the cylinders are kept at very different temperatures, they should
be so connected as to allow of free expansion, and for this purpose four keys C³ C³
are employed (two only being seen in Figure 2) they being received half their
thickness in the flange of each cylinder, while lengthwise they occupy the positions
of four radii at right angles to each other. A tight joint is obtained by means of
a copper ring contained in a triangular groove made in the lower cylinder and
compressed between it and the face of the flange of the upper cylinder. This ring
also closes a rectangular groove adjoining the triangular groove above mentioned
in which water is caused to circulate to prevent the heating of the lower cylinder
by its contact with the upper one. The space enclosed by the two superposed
cylinders is divided into two chambers whose relative capacity or volume varies
according to the position of piston c which is made by means of elastic packing
to accurately fit the internal surface of the lower cylinder. This piston which
drives a crank R through connecting rod S (not shown in Figure 2) carries a
plunger D of slightly less diameter than the internal diameter of cylinder B and of
a length to nearly fill it when the piston is at the upper end of its stroke. A is
the cold cylinder in which the negative work, i.e. the compression of the mixture
of air and gases is effected. Beneath this cylinder is placed the valve box E which
is divided into two separate compartments by a partition perpendicular to the
plane of Figure 2, and of which the piston rod stufting box is but an enlargement.
This partition is represented in dotted lines in Figure 4. The left hand compart-
ment communicates with the induction pipe of the gases by orifice d", and the
right hand compartment gives passage to the compressed gases at orifice o
Between box E and cylinder A is a thick plate perforated with two series of
holes M N respectively for the admission and exit of the gases to and from the
cylinder. Both series are closed by iron clack valves faced with felt or other
filamentous material attached by means of gum lac, each valve being held down
upon its seat by a small spiral spring. The joints of the plate in which the clack
valves are seated, with both the cylinder and valve box, are made by means of
indiarubber rings let into grooves, as shown in Figure 2.
The water for cooling
the gases in cylinder A is conveyed by a duct hi to a hollow ring or bush o
(Figures 4 and 5) the upper part of which is pierced with a ring of small holes
(less than 1 millimetre in diameter) around the piston rod. The water under

page_text: pressure escapes in horizontal jets from these perforations and strikes small pegs 0%
whereby it pulverised and projected upwards, the pegs being suitably shaped
for the purpose. These pegs are disposed regularly over the whole bottom end of
the cylinder and may also be placed upon the valves themselves, and upon the
plate in which the valves are seated. In the drawing a few only of these pegs are
shown, but they may be very numerous as by this means an abundant diffusion of
spray is produced. The valves being faced with filamentous matters, the water
injected will assist in making a tight closure. The water leaves the cylinder A by
the outlet valves together with the compressed gases, and is discharged by a pipe n'
communicating with a self acting purge cock not shown. The water is supplied
from a reservoir X and before reaching the injection orifices, is caused to pass
through the channel before mentioned at the upper end of cylinder A. The pipe
which connects with orifice d" of valve box E is supplied with air at orifice fil
regulated by a valvo, and with gas by a pipe g" similarly controlled by a valve..
By means of these valves the proportions of air and gas may be regulated to any
suitable degree, the mixture being rendered perfect by the agitation to which they
are subject in the cylinder. With mixtures containing but a small proportion of
inflammable gas, the homogeneity of the mixture is of importance in order that
the combustion may be as perfect as possible throughout the whole of the
mixture.
It has been before mentioned that the gaseous mixture after having been
compressed, is passed through a regenerator in which it is brought to a temperature
of from 200° to 300° C. by the utilisation of the sensible heat contained in the
gases which have done their work and have been expelled.
This apparatus is based on the same principle as those employed for heating one
gaseous current by another; the heating is methodical, that is to say, the heated
current travels in the reverse direction to that of the current being heated, and the
passage of the heat from one current to the other is effected through metallic
partitions in virtue of the small difference in temperature between the two
currents at each point of their course. All parts of the apparatus should however
be free to expand without allowing any escape, although the difference of pressure
between the heated and heating currents should be as much as several atmospheres.
These conditions can only be realized by the arrangements which I will proceed to
describe.
In Figures 1 and 3, Y is the regenerator which is also shown in detail on a
larger scale in Figures 10 and 11. It consists essentially of an assemblage of tubes
in which the current to be heated circulates upwardly, the heating current passing
in a downward direction around the tubes and escaping into the atmosphere.
The tubes are shown in horizontal section in Figure 11, but one only is shown in
Figure 10. Each of the tubes is surrounded by an iron wire helix serving to
strengthen it against the strong internal pressure of the ascending current, and to
cause the formation of small eddies in the descending heating current, which
bring all its molecules into contact with the surface of the tube. The ends of each
tube are closed by means of coned metal stoppers 6 and 7 which are driven into
the tubes and are connected and retained by screwthreaded tie rods 5. 5. Each
tube contains two iron wire helices, one coiled upon the tie rod, and the other
pressing against the interior surface of the tube to break up the ascending current
and favor the transmission of the heat. The ascending current is distributed to
the tubes from a chamber 1' connected with the valve box E Figure 2 by a branch
pipe i, baffle plates or deflectors 3. 3¹. being inserted to distribute the current
among the whole of the tubes. The tubes are driven tightly through the top and
bottom of the chamber 1' to which they serve as stays to support the internal
pressure thereon. The gaseous mixture enters the tubes through a number of
small holes. A similar chamber 1 collects the gases on their exit from the tubes,
whence they pass to valve G of the hot cylinder (Figure 2) by a branch pipe g¹.
The chamber 1 is exactly similar to 11. The descending current which surrounds
the tubes, passes out from the hot cylinder by a valve H Figure 2 through the

page_text: pipe h¹ to chamber 2 which is fitted gas tight to chamber 1. All the tubes pass
freely through holes in the circular bottom of the chamber which is set at a slight
inclination, the descending current entering the regenerator through the annular
orifices left around the tubes. The current is collected in chamber 2' which is
similar to chamber 2, whence it escapes into the atmosphere through the branch
pipe. The tubes are enclosed by a sheet iron casing which for convenience is
made in two parts and connected to chambers 2 and 2 by iron hoops which are
applied partly over the ends of the casing, and partly upon flanges cast on the
chambers. The expansion of the tubes can thus only cause a slight separation of
the two end chambers and cannot cause leakage unless the tubes expand unequally
which can only be caused by an irregular distribution of the ascending and
descending currents. To avoid this each tube has a small valve 8 (figure 10) to
regulate the proportion of the current passing through it. The regenerator is
connected to the valve boxes E, F by pipes having spherical joints with copper
packing rings (see Figure 12) the joints being tightened by iron tie rods k' l (seo
Figures 1, 2, 3, 10 and 11) placed within the pipes and exposed to an equal degree
of heat. The joints of the heads and nuts of the tie rods are made tight by copper
packing and the nuts are capped to prevent leakage at the screw threads. On
leaving the regenerator, the gaseous mixture is conducted to the left half of the
valve chest. F forming the top cover of cylinder D. A central passage puts the
cylinder in cominunication with either half of the chest F by openings controlled
by valves. G. H are the inlet and outlet valves respectively; they are identical
in arrangement and operation so that the description of one will apply to the
other. The valve is connected to its rod by a ball and socket in order that it may
fit true to its seat. It is made of metal enamelled and is faced with sheet asbestos
applied while the enamel is still hot which forms an elastic cushion and ensures a
tight joint. The valve rod also passes through a packing of asbestos in which is
inserted an annular gun metal channel t for the circulation around the rod of n
current of water entering at o" and escaping at 2 whereby the rod and the cover
of the valve chest are cooled. To prevent loss of heat, sheet asbestos is interposed
between the cover and the chest.
In entering and leaving the cylinder D the gases traverse a perforated distributing
diaphragm at the upper end of the cylinder, whereby the valves are protected
from the radiation of the flame (which is mostly produced below it) and the
gaseous current is distributed over the whole aron of the cylinder and thus prevent
eddies of the gases which would cause them to cool by contact with the cylinder.
To this end the perforations should not be equally distributed but should be
closer towards the circumference, a smaller passage being required at the centre
where the gases strike with force, than at the circumference where they arrive
with less energy. A suitable distribution and graduation of the holes can only be
ascertained by experiment.
This perforated distributor may be replaced by a helical arrangement similar to
the distributors of Fontaines' turbines (see Figure 16) and placed in the neck of
the trumpet mouth end of the cylinder. The gaseous molecules would acquire a
movement of rotation and a varying velocity whereby they would become.
distributed over the whole area of the cylinder in which case the trumpet mouth
should be hyperboloidal in form.
The mixture after passing through the distributor is ignited by contact with the
platinum wires 7 and 9" passing through a plug screwed in the cover F and
rendered incandescent by an electric current. The wire coils are represented in
plan in Figure 13, but instead of making the wire of uniform section, it may be
contracted at regular intervals, which points alone will become incandescent; this
will considerably diminish the resistance of the electrode to the current without.
greatly lessening the rapidity of combustion. The platinum coils may also be
replaced by an assemblage of incandescent points of any kind spread over the area
of the cylinder, or a number of small gas jets may be applied beneath the.
distributor supplied through a small central pipe passing down through the cover F

page_text: with a mixture of gas and air under pressure regulated by a small valve governed
by means of a diaphragm regulator in order to ensure a uniform supply to the
burners notwithstanding the variations of pressure in the cylinder. Opposite one
or more of these burners would be placed a wire of platinum, palladium, &c; which
would be rendered incandescent by the flame and serve to relight it in case of
momentary extinction The radiation of heat from this cylinder and also from the
regenerator is prevented by a jacket indicated in dotted lines, the cylinder being
heated by the combustion of the gases within it. To diminish tho cooling action
of the cylinder, it should have a very high temperature, but as it would be
dangerous to heat the cylinder, which is of cast iron, much above 300° C. it is
lined internally with sheet asbestos a few millimetres thick, which is made to
adhere to the cylinder either by silicate of potash or by a coat of enamel to which
it is applied when hot. Asbestos being a very poor conductor, the temperature of
its inner face, which is alone important, will be considerably higher than that of
the cast iron. If notwithstanding these precautions, it is necessary to cool the
cylinder externally, I may jacket it and pass therethrough the mixture of com-
pressed gases, leaving chamber E and thus heat the mixture so that the regenerator
will not be required. It may however happen in certain instances that the
quantity of heat necessary for the preliminary heating of the gases is not precisely
equal to that given up by the cylinder, and that the unequal expansion of the
cylinder and its casing would cause leakages difficult to prevent, and to guard
against these eventualities, it is preferred to employ the following arrangement,
which although more complicated inasmuch as it involves the use of a regenerator,
is however more practical. This consists in enclosing the hot cylinder a (figures 14
and 15) in a sheet iron casing b perforated at its upper part to admit cold air to
cool the cylinder drawn in by a small fan c communicating with the lower part of
the casing and leading into the same pipe à which discharges the gases of
combustion into the atmosphere. This arrangement is shown in elevation in
Figure 14, and in vertical section in Figure 15 and will be readily understood
without further description.
Instead of using a fun, air may be drawn into the casing by the induction of the
escaping gases, but this would cause an increase of back pressure which would be
objectionable.
The trunk D of piston C is cylindrical and made of hollow metal filled with
nonconducting material. The capacity is the same on both sides of the piston
(neglecting the displacement of the piston rod) but the gases occupy a much smaller
volume during the compression (below the piston) than during the working (above
the piston) owing to the difference of temperatures. and the effective work done on
the crank shaft is proportional to this difference. The lower cylinder is caused to
deliver a much smaller volume of gas than that taken in by the upper cylinder
owing to a dead space K (figures 4 and 5) in the box E which is in free commu-
nication with the cold cylinder. By the movement of the piston, the gas contained
in this space K becomes alternately compressed and expanded and diminishes to a
corresponding extent the volume admitted and discharged by valves M N. The
gas in this space K restores during the upward stroke of the piston the power
which it has absorbed during the down stroke and thus conduces to regularity of
motion.
In order that these successive abstractions and restitutions of power may be
effected without loss, they should take place at the same temperature and it is
therefore proposed to make the injection of water constant, the action of which
upon the gas in the space K will be to alternately cool it and prevent it from
cooling. The space K may also be varied by filling it more or less with water, and
for this purpose the three-way cock L is employed, by which said space may either
be emptied of its contents, or put in communication with reservoir X which is
filled with water under pressure for the purpose of filling it. Thus the power of
the engine may be controlled by means of a single cock.

page_text: The chamber K is strengthened by a part division plate seen in the section
Figure 5.
The gases are discharged from the hot cylinder D through valve H to the
regenerator, and thence into the atmosphere.
I will now describe the distributing mechanism. Instead of using the ordinary
guides for the piston cross head, I employ the parallel motion invented by O. Evans
which allows of using a shorter connecting rod. Figure 9 is a plan of the
mechanism, the parts of which are represented in a plane to avoid foreshortening.
The two principal levers e e' are prolonged beyond the slide ƒ so as, by means of
the two connecting rods g g', to operate the piston of a pump W drawing in water
by pipe h and discharging it into a chamber X which contains a float that controls
an exit orifice communicating with pipe m³ so as to maintain the water at a
constant level in the vessel ✗. Besides water, the pump draws in a small quantity
of air at each stroke of the piston through a hole i regulated by a screw plug.
This air passes into vessel ✗ with the water, and is intended by its compression to
form an elastic cushion; a safety valve j prevents an excessive pressure of the air.
Part of this water is utilized for cooling the lower cylinder as before described and
another portion is employed to operate to valves of the hot cylinder.
The following description of valve H applies equally to both valves.
The valve rod is screwed into the cylindrical extension (termed the plunger) of a s
gun metal piston working truly in a hole bored in a hollow frame r, r, rattached
to the cold cylinder by two arms, while the plunger passes through a cup leather
packing in the cover. The one side of the piston is kept in constant communi-
cation with the top of vessel X by a pipe q, so that the pressure acting upon the
front side of the piston has a tendency to keep the valve constantly open. The
space at the other side of the piston is connected by a pipe n with a distributing
valve VK (Figure 1) by which it is placed alternately in communication with a
discharge, pipe, open to the atmosphere and with vessel X: When communi-
cation is established with the discharge pipe, the valve H opens under the pressure
upon the front side of the piston but when communication is made with vessel X,
the valve H is closed on its seat, by the differential pressure of the water on the
front and rear sides of the piston. The piston in whichever direction it moves
gradually reduces the opening through which the water escapes from behind it and
at the end of its stroke the opening is almost completely closed so that the water
which can only escape slowly will cushion the piston and prevent shocks.
The distributing valve will be readily understood by the longitudinal and cross
sections Figures 6 and 7. cd are two hollow cylindrical valves mounted end to
end upon the same axis and rotating in a shell enclosed in two cast iron boxes V V₁
with annular spaces between the shell and boxes for the free circulation of water.
The box V is connected with the discharge pipe L, Z while box V is connected by 4
pipe with vessel X. The interior of the valves c' d' is in constant communication
with the rear side of piston J by the pipe n. Each valve has two narrow ports
which are presented twice at every revolution opposite corresponding ports made
in the shell thus putting the pipe n alternately in communication with the
discharge and with vessel ✗. The valves should be so adjusted that the two 4
communications can never be opened at one time and by turning the valves round
upon their spindle, the opening and closing of the valve H may be effected at any
desired moment. The shell as well as the valves have their ports diametrically
opposite two and two, in order to balance the pressure and prevent wear. The
valves therefore need make but half a turn for every complete revolution of the t
crank shaft.
This distributing valve is also applicable to steam and other engines. The
crank shaft is provided with a fly wheel not shown as also with a pulley or other
means for transmitting motion to the machinery to be driven

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Alexander Melville Clark in the Great Seal Patent Office on the
22nd June 1883.
ALEXANDER MELVILLE CLARK of the Firm of A, M, and W, Clark of 53 Chancery
Lane in the County of Middlesex Fellow of the Institute of Patent Agents
"IMPROVEMENTS IN GAS ENGINES." A communication to me from abroad by
Victor Julien Laurent of Paris France.
This Invention relates to an improved gas engine, of which the following is the
general principle of working.
A mixture of gas and air in suitably regulated proportions is drawn by a piston
into a cold cylinder and there compressed by said piston whilst an abundant spray
of cold water is injected into the cylinder to prevent the heating of the gases. The
gases compressed to a high pressure are then conducted to a regenerator wherein
their temperature is raised about two or three hundred degrees Cent. by utilising
the sensible heat of the gases which, having done their work, are being expelled
from the engine. The gases on leaving the regenerator enter a hot cylinder by a
valve which remains open during a portion only of the piston stroke. On entering
the cylinder the gases come in contact with a platinum wire rendered incandescent
by an electric current, whereby the gases are ignited. The platinum wire is
coiled in a series of concentric circles so as to be distributed uniformly over the
whole area of the end of the cylinder. Each point of the incandescent wire gives
rise, by its contact with a series of molecules of the gaseous matter in motion, to a
jet of flame which gradually enlarges from the point of ignition so that the several
jets of flame which emanate from the spiral wire, unite at a little distance
therefrom and the combustion which continues during the whole time of admission
of the gases is complete almost immediately after the admission is cut off, that is
to say, from the time expansion commences. This expansion terminates with
the forward stroke of the piston and during the backward stroke the exhaust
valve opens and the gaseous mixture, which by expansion has cooled down to
about 300°, passes out of the cylinder through the regenerator above mentioned
where it gives up its sensible heat and finally escapes into the atmosphere.
It is now generally thought that the heat is better utilised when the gaseous
mixture supplied to gas engines contains only just the necessary proportion of
combustible gas to ensure ignition than when a mixture rich in inflammable gas
is employed, on condition that combustion terminates at the commencement of
expansion.
Now in poor gases the flame is propagated at a comparatively slow rate so that
in using such a mixture in an engine in which ignition only takes place after the
cut off and by the contact of a single, or of a small number of incandescent points,
the combustion would not even be terminated at the end of the stroke of the piston-
whose velocity is necessarily high. The above described method of effecting
ignition is therefore intended to obviate this objection.
When a rich mixture is employed in which the propagation of the flame is rapid,
the temperature of combustion is very high and a considerable portion of the heat
generated is lost by radiation, and this is apparently the cause of poor mixtures
being advantageous for use in these engines.
The improved gas engine of this Invention is illustrated in the accompanying
drawings and will be described with reference thereto. It may here be mentioned'
that most of the bolts which unite the parts have been omitted from the drawings
for the sake of clearness.

page_text: In Figures 1 and 2 which show respectively an elevation and vertical section of
the engine, A B are two cylinders joined together end to end in the same axial
line. As the cylinders are kept at very different temperatures, they should be so
connected as to ensure their remaining concentric with one another, whilst
allowing of free expansion, and for this purpose four radial keys c³ ³ (two only
being seen in Figure 2) are fitted at equal distances apart, one half their thickness
being received in the flange of each cylinder. A tight joint is obtained by means
of a copper ring contained in a triangular groove made in the lower cylinder and
compressed between it and the face of the flange of the upper cylinder. This ring
also closes a rectangular groove countersunk beneath the triangular groove above
mentioned in which water is caused to circulate to prevent the heating of the
lower cylinder by its contact with the upper one. The space enclosed by the two
superposed cylinders is divided into two chambers whose relative capacity or
volume varies according to the position of piston C which is made by means of
elastic packing to accurately fit the internal surface of the lower cylinder. This
piston which drives a crank R through connecting rod S (not shown in Figure 2)
carries a plunger D of slightly less diameter than the internal diameter of
cylinder B and of a length to nearly fill it when the piston is at the upper end of
its stroke. A. is the cold cylinder in which the negative work, ie. the compression
of the mixture of air and gases is effected. Beneath this cylinder is placed the
valve box E which is divided into two separate compartments by a partition
perpendicular to the plane of Figure 2, and of which the piston rod stuffing box is
but an enlargement. This partition is represented in dotted lines in Figure 4.
The left hand compartment communicates with the induction pipo of the gases by
orificed, and the right hand compartment gives passage to the compressed gases
at orifice e". Between box E and cylinder A is a thick plato perforated with two
series of holes M N communicating respectively with the left and right hand
compartments of the box E for the admission and exit of the gases to and from the
cylinder. Both series are closed by iron clack valves faced with felt or other
filamentous material attached by means of gum lac, each valve being held down
upon its seat by a small spiral spring. The joints of the plate in which the clack
valves are seated with both the cylinder and valve box are made by means of
indiarubber rings let into grooves, as shown in Figure 2. The water for cooling
the gases in cylinder A is conveyed by a duct " to a hollow ring or bush o
(Figures 4 and 5) the upper part of which is pierced with a ring of small holes
(less than 1 millimetre in diameter) around the piston rod. The water under
pressure escapes in horizontal jets from these perforations and strikes small pegs o'
whereby it is pulverised and projected upwards the pegs being suitably shaped for
the purpose. These pegs are disposed regularly over the whole bottom end of the
cylinder and may also be placed upon the valves themselves and upon the plate in
which the valves are seated. In the drawing a few only of these pegs are shown,
but they may be very numerous as by this means an abundant diffusion of spray
is produced. The valves being faced with filamentous matters, the water injected
will assist in making a tight closure. The water leaves the cylinder A by the
outlet valves together with the compressed gases and is discharged by a pipe n'
communicating with a self acting purge cock not shown. The water is supplied
from a reservoir X and before reaching the injection orifices is caused to pass
through the channel before mentioned at the upper end of cylinder A. The pipe
which connects with orifice d" of valve box E is supplied with air at orifice"
regulated by a valve, and with gas by a pipe g² similarly controlled by a valve.
By means of these valves the proportions of air and gas may be regulated to any
suitable degree, the mixture being rendered perfect by the agitation to which they
are subject in the cylinder. With mixtures containing but a small proportion of
inflammable gas, the homogeneity of the mixture is of importance in order that the
combustion may be as perfect as possible throughout the whole of the mixture.
It has been before mentioned that the gaseous mixture, after having been
compressed is passed through a regenerator in which it is brought to a temperature

page_text: of from 200° to 300° C. by the utilisation of the sensible heat contained in the
gases which have done their work and have been expelled.
This apparatus is based on the same principle as those employed industrially for
heating one gaseous current by another; the heating is methodical, that is to say,
the heated current travels in the reverse direction to that of the current being
heated, and the passage of the heat from one current to the other is effected
through metallic partitions in virtue of the slight difference in temperature
between the two currents at each point of their course. All parts of the apparatus
should however be free to expand without allowing any escape, although the
difference of pressure between the heated and heating currents may be as much as
several atmospheres. These conditions can only be realised by the arrangements
which I will proceed to describe.
In Figures 1 and 3, Y is the regenerator which is also shown in detail on a
larger scale in Figures 10 and 11. It consists essentially of an assemblage of tubes
in which the current to be heated circulates upwardly, the heating current passing
in a downward direction around the tubes and escaping into the atmosphere. The
tubes are shown in horizontal section in Figure 11, but one only is shown in
Figure 10. Each of the tubes is surrounded by an iron wire helix serving to
strengthen it against the strong internal pressure of the ascending current, and to
cause the formation of small eddies in the descending heating current which bring
all its molecules into contact with the surface of the tube. The ends of each tube
are closed by means of coned metal stoppers 6 and 7 which are driven into the
tubes and are connected and retained by screwthreaded tie rods 5. 5. Ench tubo
contains two iron wire helices, one coiled upon the tie rod, and the other pressing
against the interior surface of the tube to break up the ascending current and
favor the transmission of the heat. The ascending current is distributed to the
tubes from a chamber 1' at the bottom of the regenerator connected with the
valve box E Figure 2 by a branch pipe i, baffle plates or deflectors 3. 3' being
inserted to distribute the current among the whole of the tubes. The tubes aro
driven tightly through the top and bottom of the chamber 1' to which they serve
as stays to support the internal pressure thereon. The gaseous mixture enters
the tubes through a number of small holes in the sides of the latter. A similar
chamber 1 at the top of the regenerator collects the gases on their exit from the
tubes whence they pass to valve Ģ of the hot cylinder (Figure 2) by a branch
pipe g'. The chamber 1 is exactly similar to 1'. The descending current which
surrounds the tubes passes out from the hot cylinder by a valve H Figure 2
through the pipe h' to a chamber 2 which is fitted gas tight to and immediately
beneath the top chamber 1. All the tubes pass freely through holes of sensibly
larger diameter than the tubes, made in the circular bottom of the chamber which
is set at a slight inclination, the descending current entering the regenerator
through the annular orifices left around the tubes. The current is collected in a
chamber 2 which is similar to chamber 2 whence it escapes into the atmosphere
through the branch pipe h³. The tubes are enclosed by a sheet iron casing which
for convenience is made in two parts and connected to chambers 2 and 2' by iron
hoops which are applied partly over the ends of the casing and partly upon flanges
cast on the chambers. The expansion of the tubes can thus only cause a slight
separation of the two end chambers and cannot cause leakage unless the tubes
expand unequally which can only be caused by an irregular distribution of the
ascending and descending currents. To avoid this, each tube has a small valve 8
(Figure 10) to regulate the proportion of the current passing through it. The
regenerator is connected to the valve boxes E F by pipes having spherical joints
with copper packing rings (see Figure 12) the joints being tightened by iron tie
rods (see Figures 1. 2. 3. 10 and 11) placed within the pipes and exposed to
an equal degree of heat. The joints of the heads and nuts of the tie rods are made
tight by copper packing and the nuts are capped to prevent leakage at the screw-
threads. On leaving the regenerator the gaseous mixture is conducted to the left
balf of the valve chest F forming the top cover of cylinder D. A central passage

page_text: puts the cylinder in communication with either half of the chest F by openings
controlled by valves. GH are the inlet and outlet valves respectively; they are
identical in construction and symmetrical in arrangement and their operative
mechanism is similar so that the description of one will apply to the other. The
valve is connected to its rod by a ball and socket in order that it may fit true to
its seat. It is made of metal enamelled and is faced with sheet asbestos applied
while the enamel is still hot which forms an elastic cushion and ensures a tight
joint. The valve rod also passes through a packing of asbestos in which is inserted
an annular gun metal channel t for the circulation around the rod of a current of
water entering at o² and escaping at p³ whereby the rod and the cover of the valve
chest are cooled. To prevent loss of heat sheet asbestos is interposed between the
cover and the chest, and a disc of the same material protects it from the heat on
the vacuum side of the chest. In entering and leaving the cylinder D the gases
traverse a perforated distributing diaphragm Q at the upper end of the cylinder
whereby the valves are protected from the radiation of the flame (which is mostly
produced below it) and the gaseous current is distributed over the whole area of
the cylinder, thus preventing eddies of the gases which would cause them to cool
by contact with the cylinder. To this end the perforations should not be equally
distributed but should be closer towards the circumference, a smaller passage being
required at the centre where the gases strike with force, than at the circumference
where they arrive with less energy. A suitable distribution and graduation of the
holes can only be ascertained by experiment. This perforated distributor may be
replaced by a helical arrangement similar to the distributors of Fontaine's turbines
(see Figure 16) and placed in the neck of the trumpet mouth end of the cylinder.
The gaseous molecules would acquire a novement of rotation and a varying
velocity whereby they would become distributed over the whole area of the
cylinder in which case the trumpet mouth should be hyperboloidal in form.
The mixture after passing through the distributor is ignited by contact with the
platinum wires and q passing through a plug screwed in the cover F and
rendered incandescent by an electric current. The wire coils are represented in
plan in Figure 13, but instead of making the wire of uniform section it may be
contracted at regular intervals which points alone will become incandescent; this
will considerably diminish the resistance of the electrode to the current without
greatly lessening the rapidity of combustion. The platinum coils may also be
replaced by an assemblage of incandescent points of any kind spread over the arci
of the cylinder, or a number of small gas jets may be applied beneath the
distributor supplied through a small central pipe passing down through the
cover F with a mixture of gas and air under pressure regulated by a small valve
governed by means of a diaphragm regulator in order to ensure a uniform supply
to the burners notwithstanding the variations of pressure in the cylinder. Opposite
one or more of these burners would be placed a wire of platinum, palladium, &c,
which would be rendered incandescent by the flame and serve to relight it in case of
momentary extinction. The radiation of heat from this cylinder and also from the
regenerator is prevented by a jacket indicated by dotted lines, the cylinder being
heated by the combustion of the gases within it. To diminish the cooling action of
the cylinder, it should have a very high temperature, but as it would be dangerous
to heat the cylinder, which is of cast iron, much above 300° C. it is lined
internally with sheet asbestos a few millimetres only in thickness which is made to
adhere to the cylinder either by silicate of potash or by a coat of enamel to which
it is applied when hot. Asbestos being a very poor conductor, the temperature of
its inner face, which is alone important, will be considerably higher than that of
the cast iron. If, notwithstanding these precautions, it is necessary to cool the
cylinder externally, I may jacket it and pass therethrough the mixture of com-
pressed gases leaving chamber E and thus heat the mixture so that tho regenerator
will not be required. It may however happen in certain instances that the
quantity of heat necessary for the preliminary heating of the gases is not precisely
equal to that given up by the cylinder and that the unequal expansion of the

page_text: cylinder and its casing would cause leakages difficult to prevent, and to guard
against these eventualities it is preferred to employ the following arrangement
which although more complicated inasmuch as it involves the use of a regenerator,
is however more practical. This consists in enclosing the hot cylinder a (Figures 14
and 15) in a sheet iron casing 6 perforated at its upper part to admit cold air to
cool the cylinder drawn in by a small fan c communicating with the lower part of
the casing and leading into the same pipe & which discharges the gases of com-
bustion into the atmosphere. This arrangement is shown in elevation in Figure 14
and in vertical section in Figure 15 and will be readily understood without further
description.
Instead of using a fan, air may be drawn into the casing by the induction of the
escaping gases, but this would cause an increase of back pressure which would be
objectionable.
The trunk D of piston C is cylindrical and made of hollow metal filled with
nonconducting material. The capacity is the same on both sides of the piston
(neglecting the displacement of the piston rod) but the gases occupy a much
smaller volume during the compression (below the piston) than during the working
(above the piston) owing to the difference of temperatures, and the effective work
done on the crank shaft is proportional to this difference. The lower cylinder is
caused to deliver a much smaller volume of gas than that taken in by the upper
cylinder owing to a dead space K (figures 4 and 5) in the box E which is in free
communication with the cold cylinder. By the movement of the piston the gas
contained in this space K becomes alternately compressed and expanded and
diminishes to a corresponding extent the volume admitted and discharged by
valves M N. The gas in this space K restores during the upward stroke of the
piston the power which it has absorbed during the down stroke and thus
conduces to regularity of motion.
In order that these successive abstractions and restitutions of power may be
effected without loss, they should take place at the same temperature, and it is
therefore proposed to make the injection of water constant, the action of which
upon tho gas in the space K will be to alternately cool it and prevent it from
cooling. The space K may also be varied by filling it more or less with water, and
for this purpose the three-way cock L is employed by which said space may either
be emptied of its contents or put in communication with reservoir X which is filled
with water under pressure for the purpose of filling it. Thus the power of the
engine may be controlled by means of a single cock.
The chamber K is strengthened by a part division plate seen in the section Figure 5.
The gases are discharged from the hot cylinder D through valve H to the
regenerator and thence into the atmosphere.
As (in case of any hitch in the working of the engine) the flame might spread
from the cylinder to the regenerator wherein the inflammable mixture is compressed
to about 10 atmospheres the consequence of which would be a sudden rise of
pressure to 40 or 50 atmospheres, I prefer to provide a safety valve to prevent such
a pressure being attained although the apparatus being constructed to support such
a pressure without risk. The valve is arranged to open instantaneously and to a
sufficient extent, for which purpose it is necessary that the pressure of the gases
should have but a relatively very small mass to displace in order to escape.
Figure 21 represents a section of the lower part of the regenerator before
described with this difference that the pipe a by which the mixture of cold
compressed gases enters is radial to the chamber ef as shown in the plan Figure 22
instead of tangential as in Figures 1. 10 and 11. The vertical tubes by which one
is shown at b do not in this case extend beyond the bottom c d of the regenerator.
The chamber cf extends downwards in a tubular form at g and is closed by a thin
cast steel doine shaped double beat valve h whose bottom rim is received in a
chamber i attached to the regenerator by tie rods j j. The valve is seated on
ndia rubber rings and land is mounted upon a central guide rod m and is kept
up to its seat by a coiled spring m. The valve has small orifices o in it which put

page_text: the chambers above and below the valve in communication so that the pressure of
the gases is normally the same in both, but as the effective area is greatest on the
under side of the valve, the upward pressure prevails and therefore under normal
Should however a sudden
conditions the valve will be kept tightly closed.
increase of pressure occur in the regenerator, it will cause the valve to open and
allow the gases to escape before the pressure can be transmitted to the underside of
the valve.
I will now describe the distributing mechanism. Instead of using the ordinary
guides for the piston cross head, I employ the parallel motion invented by O. Evans
which allows of using a shorter connecting rod. Figure 9 is a plan of the
mechanism, the parts of which are represented as lying in the same plane to avoid
foreshortening. The two principal levers e e¹ are prolonged beyond the slide f so
as, by means of the two connecting rods g g¹ to operate the piston of a pump W
drawing in water. by pipe h and discharging it into the chamber X which
contains a float that controls an exit orifice communicating with pipe m³ so as to
maintain the water at a constant level in the vessel X. Besides water the pump
draws in a small quantity of air at each stroke of the piston through a hole
regulated by a screw plug. This air passes into vessel X with the water and is
intended by its compression to form an elastic cushion; a safety valvej prevents
an excessive pressure of the air. Part of this water is utilised for cooling the
lower cylinder as before described and another portion is employed to operate the
valves of the hot cylinder.
The following description of valve H applies equally to both valves. The valve
rod is screwed into the cylindrical extension (termed the plunger) of a gun metal
piston working in a cylinder or guide formed in a hollow frame rrr (which is
attached to the cold cylinder by two arms) while the plunger passes through a cup
leather packing in the cover. The one side of the piston is kept in constant com-
munication with the top of vessel X by a pipe q so that the pressure acting upou
the front side of the piston (from whose area at this side is deducted that of the
plunger) has a tendency to keep the valve constantly open. The space at the other
side of the piston is connected by a pipe n with a distributing valve V V₁ (Figure 1)
by which it is placed alternately in communication with a discharge pipe ll open
to the atmosphere and with vessel X. When communication is established with
the discharge pipe the valve H opens under the pressure upon the annular front
side of the piston, but when communication is made with vessel X the valve H is
closed on its sent by the differential pressure of the water acting on the annular
front side and in the whole area of the rear side of the piston. The piston in
whichever direction it moves gradually reduces the opening through which the
water escapes from behind it, and at the end of its stroke the opening is almost
completely closed so that the water which can only escape slowly will cushion the
piston and prevent shocks.
The distributing valve will be readily understood by the longitudinal and cross
sections, Figures 6 and 7. c' d' are two hollow cylindrical valves mounted end to
end upon the saune axis and rotating in a shell enclosed in two cast iron boxes V V₁
with annular spaces between the shell and boxes for the free circulation of water.
The box V' is connected with the discharge pipe l, while box V is connected by
pipe k with vessel ✗. The interior of the valves cd is in constant communication
with the rear side of piston J by the pipe n. Each valve has two narrow ports
which are presented twice at every revolution opposite corresponding ports made
in the shell, thus putting the pipe n alternately in communication with the
discharge and with vessel X. The valves should be so adjusted that the two
communications can never be opened at one time, and by turning the valves round
upon their spindle, the opening and closing of the valve II may be effected at any
desired moment. The shell as well as the valves have their ports diametrically
opposite, two and two, in order to balance the pressure and prevent wear.
valves therefore need make but half a turn for every complete revolution of the
crank shaft.
The

page_text: Figures 17. 18. 19 and 20 show details of the distributing valve slightly modified
and combined directly with the piston which operates the valve of the hot
cylinder, Figure 17 being a longitudinal section, and Figures 18. 19 and 20
transverse sections of the same taken on lines 1-2, 3-4 and 5-6 of Figure 17
respectively. The letters of reference in these figures do not correspond to those in
the other figures.
The mode of working and action of the valve will be readily understood from
the following description. A is the piston attached to one of the valves of the hot
cylinder by its rod L. pp piston packing. B C are spaces to contain water for
retarding the piston and valve. E branch pipe in communication with reservoir X
Figure 1 containing water at a pressure of several atmospheres. F discharge open
to the atmosphere. H fixed gun metal shell surrounded by water in cc in com-
munication with E. The shell H has two ports e e diametrically opposite to each
other and parallel to the axis. I is another fixed shell surrounded by water at d d
communicating with the discharge F and also provided with ports h h. G is a
hollow cylindrical valve rotating with spindle M and provided with two ports g g
which coincide twice per revolution with those of shell I. D is another cylindrical
valve also rotating with the spindle and provided with ports ƒ ƒ (shown in dotted
lines only in Figure 18) which coincide twice per revolution with the ports e e of
shell H. The interior b of the shell is placed in communication by ports a a with
the rear side of the piston A. kk passage by which branch pipe E is kept in
constant communication with the front annular side of piston A. The single
headed arrows correspond to the motion of the piston which effects the closing of
the valve and the double headed arrows correspond to the stroke of the piston for
opening the valve. This distributing valve is also applicable to steam and other
engines.
The crank shaft is provided with a fly wheel not shown and also with a pulley
or other means for transmitting motion to the machinery to be driven.
Having described the nature of the said Invention and the manner of performing
the same, I declare that what I claim as the Invention to be protected by the
herein before in part recited Letters Patent is.
1 The addition to the cylinder in which the gas is compressed and cooled of a
dead space or chamber of variable capacity for the purpose of diminishing the
volume of compressed gas delivered at each stroke of the piston.
2nd The berein described arrangement for injecting water into the cold cylinder.
3rd Cooling the hot cylinder by means of a double external jacket through which
the compressed gas is passed on its way to the admission valve.
4th The perforated distributing diaphragm at the upper end of the hot cylinder
as and for the purpose specified.
5th Igniting the gases by means of platinum wires presenting a large number of
points spread over the entire area of the cylinder and rendered incandescent by an
electric current.
6th The combination of a regenerator with gas engines generally and particularly
the construction and arrangements of regenerator herein shown and described.
7th the mode of operating the valvos by means of hydraulic pressure as shown
and described.
8th The general arrangement and combination of parts constituting the improved
gas engines herein shown and described.
In Witness whereof I the said Alexander Melville Clark have hereunto set
my hand and seal this twenty second day of June. A D 1883