IMPROVEMENTS IN GAS MOTOR ENGINES
Year: 1878

page_text: LETTERS PATENT to Dugald Clerk, of Glasgow, in the County of Lanark,
North Britain, Analytical Chemist, for the Invention of "IMPROVEMENTS IN
GAS MOTOR ENGINES."
Sealed the 28th January 1879, and dated the 1st August 1878.
PROVISIONAL SPECIFICATION left by the said Dugald Clerk at the Office
of the Commissioners of Patents on the 1st August 1878.
DUGALD CLERK, of Glasgow, in the County of Lanark, North Britian, Analytical
Chemist. "IMPROVEMENTS IN GAS MOTOR ENGINES."
This Invention has for its object to improve the construction and action of motor
engines in which a combustible gas is employed as the source of power, such gas
being conbined with a suitable proportion of air and ignited within the engine, so
as to operate by its expansive force.
In a simple modification of gas motor engine embodying the improvements the
power is developed in one single-acting cylinder, having combined with it a second
cylinder, which is used as a compressing pump; the two pistons being connected
by rods to cranks on a first-motion shaft, which also carries eccentrics for working
the valves.
The air and gas are admitted to the pump by means of a valve, which is in the
form of a plate and slides between a port face and a cover, the air entering by a
port formed through the cover, and at the proper times passing through a port in
the valve into the port of a passage leading into the pump, whilst the gas finds its
way from an inlet port in the port face by a shallow cavity on the inner face of
the valve into the passage leading into the pump. The air and gas pass into the
pump when its piston moves outwards and becomes mixed therein, and on the
return inwards of the piston the mixture passes through a lift valve into an inter-
mediate chamber or reservoir, which may be of any shape, and is conveniently
formed in a casting, constituting the back end piece to both cylinders.
The intermediate chamber or reservoir consists by preference of two parts, one

page_text: .
part communicating immediately with the valve from the pump and the passage to
the cylinder, and the second part communicating only with the other part by a
small opening.
This arrangement is designed to make any change caused by the governor action
in the mixture supplied by the pump to tell immediately in the power cylinder
instead of being modified by the intermixture of the charges with the whole of the
contents of the reservoir.
The mixture of air and gas is admitted to the main or power cylinder by means
of a valve which is in the form of a plate and slides between a port face and a
cover; the mixture first passing from a port in the port face through one port in
the valve into a passage or small chamber in the cover, and thence by a second port
in the valve into the passage leading into the cylinder.
The valve having moved in one direction to admit the mixture cuts it off on its
return, and then moving further brings into position between the cylinder passage
and the cover passage a small quantity or bundle of platinum, which is sufficiently
heated (in a manner herein-after explained) to ignite the mixture of air and gas.
When this ignition occurs the cylinder piston is moving outwards, and the small
quantity of the mixture that is in the cover passage necessarily expanding causes a
current through the platinum, which passing in an ignited state into the cylinder
insures the rapid ignition of the whole of the mixture in the cylinder.
The platinum, folded so as to form a permeable bundle, is situated in a cavity
formed for it in the valve, and lined with asbestos or other suitable non-conducting
material; and when the valve is moved back it is subjected to the heating action
of a small ignited current of mixed air and gas.
In one modification of this igniting apparatus a small cavity in the port face is
supplied with the mixed air and gas from the intermediate chamber or reservoir;
and this mixture issues through wire gauze or perforated metal, outside of which
it is ignited, and its flame plays upon or passes through the platinum bundle.
In another modification the, platinum bundle is arranged in a cavity formed for
it in the valve, and on the side further from the port face wire gauze and perforated
metal are secured outside of the platinum by a steel or other suitable plate fixed in
the outer face of the valve, but having a port through it. A current of mixed air
and gas is directed through the wire gauze and perforated metal, and being ignited
by the platinum keeps up the heat thereof.
When the part of the valve having the platinum is not in position for igniting
the charge in the cylinder, it, on its inner side, communicates with one or other of
two cavities in the port face, which cavities are in communication with the
exhaust pipe.
The valve is by preference made hollow, and water is made to circulate through
it by means of flexible or jointed tubes.
The connecting rod which works this valve is made with a screw coupling or
equivalent connection, adjustable by means of a small hand wheel, so that the rod
can be lengthened or shortened for the purpose of controlling the action of the
engine, and more particularly for facilitating the starting of the engine by arranging
the valve action in a manner to make the engine act with a small compression of
the air and gas.
When working at full power the engine operates with the air and gas in a state
of considerable compression, and is on that account more economical than many
existing gas motor engines.
The cylinder is provided with an exhaust valve separate from the admission
valve, such exhaust valve being by preference a simple disc valve arranged at the
bottom of the cylinder and worked from an eccentric by a rod, which is in two
parts, connected together with a spring, to allow of a part of the stroke of the
eccentric being performed after the valve is closed..
A small centrifugal governor is fitted to the engine for controlling the speed by
acting on a regulator valve on the gas supply pipe. Whenever this valve is closed

page_text: by the governor it is held in that position by a catch, which is released temporarily
at the commencement of each stroke by a movement from the crank shaft, so that
when the speed becomes reduced the governor can re-open the valve only at the com-
mencement of a stroke, and thereby are avoided inconveniences arising from the
valve re-opening at other times.
The cylinders are kept sufficiently cool by water jackets, and the water in these
jackets and the valve is made to circulate through them and a tank, which last is
conveniently formed in the bed frame of the engine by a small centrifugal pump
which is worked by the governor spindle, or in any other convenient way.
Some of the improvements herein-before described are advantageously applicable
to existing gas motor engines.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Dugald Clerk in the Great Seal Patent Office on the 31st January
187.9..
DUGALD CLERK, of Glasgow, in the County of Lanark, North Britain.
PROVEMENTS IN GAS MOTOR ENGINES."
« IM-
My said Invention has for its object to improve the construction and action of
motor engines, in which a combustible gas is employed as the source of power,
such gas being combined with a suitable proportion of air, and ignited within the
engine, so as to operate by its expansive force.
In a simple modification of gas motor engines embodying my improvements the
power is developed in one single-acting cylinder, having combined with it a second
cylinder, which is used as a compressing pump, the two pistons being connected by
rods to cranks on a first-motion shaft, which also carries eccentrics for working the
valves.
The air and gas are admitted to the pump in suitable proportions by a valve
sliding between two faces, and are forced by the pump piston through a lift valve
into an intermediate chamber or reservoir, which consists by preference of a small
compartment conveniently formed at the back end of the pump, and of a larger
compartment communicating with the former by a comparatively small passage,
and formed beneath the pump and power cylinders.
The mixture of air and, gas is admitted to the power cylinder by means of a
valve, which is in the form of a plate, and slides between a port face and a cover,
the peculiarities of the valve and passages and other parts in connection therewith
being herein-after minutely described.
The connecting rod which works this valve is made with a screw coupling or
equivalent adjustable connection, so that the rod can be lengthened or shortened
for the purpose of controlling the action of the engine, and more particularly for
facilitating the starting of the engine by arranging the valve action in a manner
to make the engine act with a small compression of the air and gas,

page_text: When working at full power the engine operates with the air and gas in a state
of considerable compression, and is on that account more economical than many
existing gas motor engines.
The power cylinder is provided with. a separate exhaust valve, which is worked
by an eccentric, the rod of which is in two parts connected together with a spring
arranged to allow of a part of the stroke of the eccentric being performed after the
valve is closed.
A small centrifugal governor is fitted to the engine to act on a regulator valve
on the gas supply pipe, but the parts are arranged so that if the regulator valve is
closed it cannot open except at the commencement of a stroke, and thereby.pre
avoided inconveniences arising from the valve re-opening at other times.
And in order that my said Invention and the manner of performing the same
may be properly understood, I hereunto append two Sheets of explanatory Drawings
to be herein-after referred to, and representing a gas motor engine as made with
my improvements. In these Drawings the same reference numerals are used to
mark the same or like parts wherever they are repeated.
Figure 1, on Sheet 1 of the accompanying Drawings, is a side elevation of my
improved gas motor engine as with the valve cover and part of the admission valve
of the power cylinder removed; Figure 2 is a sectional plan.
Figure 3, Sheet 2, is a side elevation showing the side opposite to that shown in
Figure 1.
Figure 4 is a back end elevation partly in section.
The remaining Figures are herein-after described.
The parts of the engine are carried upon a kind of double base 1, 2, consisting of
a lower part 1 used as a tank to contain water, which is made to circulate through
various spaces 3 about the power cylinder 10 and its valves to prevent the parts
from becoming inconveniently heated.
The circulation may be effected by means of a centrifugal pump (not shown in
the Drawings) or in any other convenient way.
The upper part 2 of the base is partly occupied by a wrought-iron receiver,
indicated by dotted lines at 5 in Figures 3 and 4, and forming the larger com-
partment herein-before referred to for holding the compressed mixture of air and
gas.
The base 1, 2, is of an oblong rectangular form in plan, and the first-motion
or crank shaft 6 is placed horizontally in suitable bearings across one end of the
base, the shaft having a fly wheel 7 on one end, and on the other end a pulley 8
for a belt for transmitting the power from the machine.
The compressing cylinder or pump 9 and the power cylinder 10, which are both
single-acting, are placed horizontally side by side at the end of the base opposite
to that at which the crank shaft 6 is situated, and their admission valves are at
.their outer sides.
The cylinders 9, 10, are simple cylindrical shells held in a jacket or external
casting 11, and between it and an outer end casting 12, which latter has formed in
and on it the passages and port faces, and also other parts herein-after referred to.
This construction admits of the cylinders being renewed when requisite at very
small cost.
The admission passage 13 of the pump has its outer end or port in a vertical
port face 14, and the valve is a plate 15 working horizontally between that face
and a cover 16, which cover is carried on studs or bolts, and is pressed against the
valve by springs 17 adjustable on the bolts by screw nuts. The gas supply pipe 18
communicates (through a regulating valve 73 herein-after described) with a
'cavity 19 in the valve cover 16, whilst the air has access by ports 20 formed
through the cover above, and below a part of the cavity 19. The valve 15 is made
.with a single port 21 through it, and when the eccentric 22, to which the valve 15
is connected by a rod 23, moves the valve 15 so as to place its port 21 between the
ports 19, 20, and the passage 13, air and gas pass into the pump 9, the piston of
which is then moving towards the crank shaft.
When the piston of the pump 9 returns the valve 15 is in its closed position, and

page_text: the mixture of air and gas is compressed, and is forced through a simple spring
lift valve 24 into the intermediate chamber or reservoir 25 formed in the end
casting 12.
The compressed gaseous mixture passes from the reservoir 25 by a pipe 26,
which communicates with a pipe 27 leading to the admission valve of the power
cylinder 10, and also with a small pipe 28 leading through a stop valve 29 into
the reservoir 5 within the upper part 2 of the base.
Whilst the division of the space for the compressed gaseous mixture into two
compartments 25 and 5, with the communication 28 between them comparatively
small, is of advantage in causing any action of the governor to be immediately
effective, the larger compartment 5 can also be utilised for retaining or storing a
quantity of compressed gaseous mixture, when the action of the engine is stopped,
to be availed of on afterwards re-starting the engine. For this purpose the stop
valve 29 must be closed whenever the engine is stopped.
The gaseous mixture enters the power cylinder 10 by an admission passage 30
formed in the end casting 12 and having its outer end or port in a vertical port
face 31, seen as for the most part uncovered in Figure 1. A passage formed also in
casting 12 and having a port 32 in the port face 31 leads the gaseous mixture from
the pipe 27 to the valve 33. This admission valve 33 is a vertical plate working
horizontally between the port face 31 and the inside vertical face of a plate or
cover 34, held with a suitable pressure against the valve 33 by springs 35 on bolts
or studs, such springs being adjustable by screw nuts on the bolts. The valve 33
and the adjacent parts are shown as in horizontal section at different levels in
Figures 2 and 7, and Figures 8 and 9 are inner side elevations of the cover 34 and
valve 33 respectively. There are two ports 36, 37, through the valve 33, and when
the valve is in a certain position the gaseous mixture has access from the port _32
by one port 36 into a passage 38 formed in the cover 34, then through that
passage 38 and the other port 37 in the valve into the admission passage 30, and
thence into the cylinder 10.
The admission of the gaseous mixture into the cylinder 10 takes place whilst
the valve 33 is moving towards the crank shaft, and the combination of that
movement first cuts off the supply of gaseous nixture and immediately afterwards
brings between the passages 38 and 30 a bundle of incandescent platinum 39
contained in a port formed through the valve. At this time the piston of the
cylinder 10 is also moving towards the crank shaft which causes a slight expansion
of the gaseous mixture in it, and the gaseous mixture remaining in the passage 38
has in consequence a slight excess of pressure which is sufficient to make it expand
to the platinum bundle so as to become ignited. There being no outlet for the
ignited gaseous mixture it perforce expands into the cylinder 10 in a strong jet
which ignites the contents of the cylinder in a very complete manner.
platinum 39 and the part of the valve 33 containing it and also part of the cover 34
are shown enlarged and in horizontal section in Figure 5, whilst Figure 6 is a corre-
sponding face view of part of the valve 33.
The
The platinum 39 in the form of a thin sheet is bended from side to side to form
a bundle, with thin spaces for the passage of the gaseous mixture between its folds;
and it is held between pieces 40 of porcelain or other suitable refractory material
being secured by small flaps förmed on it and bent outwards upon the pieces 40,
whilst these pieces are protected by coverings of thin platinum.
The platinum 39 and its holding pieces 40 are packed with asbestos into a
cylindrical cavity 41 formed for them in the valve 33, such cavity being fitted with
a cover 42 having a rectangular opening 43 in it for the passage of the gaseous
mixture, whilst a similar opening 44 through, from the bottom of the cavity 41 to
the other side of the valve, allows the gaseous mixture to pass onwards.
The incandescence of the platinum 39 is maintained partly by the combustion of
the gaseous mixture passing through it from the passage 38 at the time of igniting
the charge in the power cylinder 10, and partly by the combustion of small
quantities of gaseous mixture which are led through it by special passages at times

page_text: when it is not in the position between the passages 38 and 30. The valve cover 34
has formed on its inner face two ports or cavities 45, 46, one on each side of the
after port of the passage 38, and both these cavities are provided with pieces of
wire gauze held between perforated metal plates to prevent flame from passing into
a passage 47 which supplies both cavities with gaseous mixture. The passage 47,
which is indicated by dotted lines in Figure 8, receives the gaseous mixture from a
branch pipe connected to the main pipe 27 at any convenient point, as 48, Figure 4,
but not shown in that Figure to avoid complexity.
In Figures 5 and 7 the platinum 39 is shown as opposite one, 45, of the two
cavities in the cover, and the gaseous mixture passes through the platinum and
through a passage 49 in the cylinder port face 14. When the valve 33 is in the
position with the platinum 39, opposite the other cavity 46, the gaseous mixture
after passing through the platinum enters a passage 50 in the port face 14. The
two passages 49, 50, unite and lead the products of combustion either immediately
into the atmosphere or into the main exhaust pipe. The pressure of the gaseous
mixture from the receivers 5, 25, is greater than is necessary either for maintaining
the incandescence of the platinum 39 in the manner just explained or for heating
up the platinum to the necessary temperature when starting the engine, and the
pressure is economised and utilised by means of an injector 51, fitted at the inlet
into the passage 47 in a manner to make a very small quantity of the compressed
gaseous mixture effect what is required. This injector 51 is formed with holes to
take in air, and has connected to it a small branch pipe 52 to admit combustible
gas to mix with the air taken by the inductive action of the small jet of compressed
gaseous mixture, so as to form a suitable gaseous mixture of the whole.. The
outermost cavity 45 is made to communicate by means of a small passage, seen in
section in Figure 5, with a port 53 in the outer end of the valve cover 34, and a
small slide 54 which ordinarily covers this port 53 is withdrawn when about to
start the engine, for the purpose of igniting the gaseous mixture and beating up
the platinum 39. The gas being turned on at the branch pipe 52, and also the
jet of compressed gaseous mixture, the mixture issues at the port 53 and is there
ignited, after which the appearance of the flame being a guide the stop-cocks are
adjusted and the cover 54 is then closed. The ignited gaseous mixture then passes
through the platinum 39 and heats it up, the valve 33 being of course placed in a
suitable position, that is, with the platinum 39 opposite the cavity 45, as shown
in Figure 5.
An important object I have had in view in the construction of my improved gas
motor engine, and more particularly in proportioning and arranging the passages
and ports and the valve mechanism is, the working of the engine with the gaseous
mixture in a state of considerable compression, whereby the power developed from
the gas employed is greatly increased as compared with that obtained in gas motor
engines working with a low compression. The parts are at the same time such as
to admit of the degree of compression being easily controlled and varied, and in
particular to allow of the engine being conveniently started with the gaseous
mixture of the low pressure.
If during the working of the engine the admission of gas and air to the pump 9
continues the same, an alteration of the admission valve 33 to the power cylinder 10,
such as will make it cut off earlier in the stroke, will not diminish the power
developed by the engine. Each stroke of the pump will force a certain quantity of
gaseous mixture into the reservoirs 5, 25, and if an equal quantity does not pass
into the power cylinder at each stroke the pressure in the reservoirs must
necessarily increase, and it will increase until with the earlier cut-off the same
quantity, but of greater pressure, is admitted as with the later cut-off. This equal
quantity admitted with the earlier cut-off, but at the increased pressure, must
necessarily develop increased power, so that the making of the cut-off carlier
increases the power developed from a given quantity of gaseous mixture.
For the purpose of varying the cut-off action of the admission valve 33 of the
power cylinder 10 in a simple and convenient manner; I connect it to the strap of

page_text: the eccentric 55 which works it so that the length of the rod can be altered, the
ports and passages being proportioned so as to be quite sufficient with any adjust-
ment of the valve 33, relatively to the eccentric 55 that may be adopted in practice.
In one arrangement, shown in Figure 10, a rod 56, connected to the valve 33 so
as to be free to turn, has its outer end screwed into a coupling piece 57 which is
jointed to the eccentric rod 58. The rod 56 has a longitudinal groove formed in
it, and in this groove there engages a key in the tubular boss of a hand wheel 59
which is held by a bracket 60. The rod 56 can move longitudinally through the
centre of the hand wheel 59, whilst it can be turned by that hand wheel inde-
pendently of its longitudinal motion, and when it is thus turned, it, by screwing
into or out of the coupling piece 57, adjusts the valve nearer to or further from the
eccentric.
Another simple arrangement for adjusting the valve 33, relatively. to the
eccentric 55, is shown in Figures 1, 2, 4, and 9, and in it the eccentric rod 58 is
forked and connected to the valve 33 by a pin which passes through short hori,
zontal slots in the valve and through an inclined slot in a bar 61, which is movable
vertically through a vertical slot in the valve. The bar 61 is connected by a long
link 62 to a hand lever 63, the link 62 accommodating itself to the reciprocation
of the valve, and the hand lever 63 being fixed in any desired position by a handled
pinching screw 64. The effect of adjusting the valve 33. nearer to the eccentric 55
is to make the cut-off earlier, and vice versa.
The power cylinder 10 is fitted with an exhaust valve 65 separate from the
admission valve 33, such exhaust valve being by preference a simple disc valve 65
opening into the cylinder 10, and worked by a rod 66, which is connected by a
lever 67 to a rod 68. The rod 68 is connected to the rod 69 of the eccentric 70,
which works it by a spring coupling 71 arranged so as to allow of a part of the
stroke of the eccentric being performed after the valve is closed, in order that there
may be a suitable interval between its closing and re-opening.
A small centrifugal governor 72 is fitted to the engines for regulating the speed
by acting on a valve 73 fitted in connection with the gas supply pipe 18. The
governor 72 is on a horizontal shaft, driven by means of a pulley 74 and a belt
from the crank shaft 6, and the governor sleeve 75 acts on a lever on a rocking
shaft 76, which has on it a second lever 77 connected to the spindle of the valve 73.
The rocking shaft 76 has also on it a small boss 78, on which there bears the end
of a lever 79 acting as a brake, and pressed against the boss 78 by a spring, and the
lever 79 has made in the same piece with it an elbow 80, the end of which projects
down slightly in the way of the top of the valve 15 when the lever 79 presses on
the boss 78. The pressure of the lever 79 prevents any movement of the regu-
lating valve 73, but at the commencement of each movement of the pump piston
towards the crank shaft the admission valve 15, by acting on the elbow 80, relieves
the pressure on the boss, and then allows the governor to act on the regulating
valve 73 if the speed has given it any tendency to do so.
Some of my improvements herein-before described are advantageously applicable
to existing gas motor engines.
Having thus particularly described my said Invention, and the manner of per-
forming the same, I have to state that I do not restrict myself to the precise
details herein described or delineated, but that what I believe to be novel and
original, and claim as the Invention secured to me by and in terms of the herein-
before in part recited Letters Patent is,--
1. The arranging or combining together of the parts of gas motor engines, sub-
stantially in the improved manner herein-before described.
2. The combination of the speed governor with the valve controlling the supply
of combustible gas, and with parts which prevent movements of the valve excepting
at the commencement of the taking-in movements of the pump piston, and which
are substantially such as are herein-before described.
3. The constructing of the admission valve of the power cylinder, and the ports

page_text: and passages in connection with it, substantially as and for the purposes herein-
before described.
4. The leading of the gaseous mixture when being admitted into the power
cylinder through a passage or space (38), wherein a portion is retained by the valve
action to assist in igniting the charge in the cylinder, substantially in the manner
herein-before described.
5. The employment of platinum for igniting the charges in the power cylinder,
such platinum being rendered incandescent by the combustion of a portion of the
gaseous mixture, substantially in the manner herein-before described.
6. The mode of arranging the platinum igniter, and the arrangements of the
passages and parts for heating it and for maintaining its incandescence, as herein-
before described.
.
7. The making of the connection between the admission valve of the power
cylinder and the eccentric which works it adjustable, substantially in the manner
and for the purposes herein-before described.
8. The special feature or peculiarity of the combination of parts forming my
improved gas motor engine, which consists in causing the gaseous mixture to operate
with the higher initial pressure by adjusting the cut-off so as to be earlier, substan-
tially as herein-before described.
In witness whereof, I, the said Dugald Clerk, have hereunto set my hand
and seal, this Twenty-ninth day of January, in the year of our Lord One
thousand eight hundred and seventy-nine.
Witness,
EDMUND HUNT,
Patent Agent,
Glasgow.
DUGALD CLERK. (L.S.)