IMPROVEMENTS IN GAS MOTOR ENGINES
Year: 1879

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 12th December 1879, and dated the 18th June 1879,
PROVISIONAL SPECIFICATION left by the said Dugald Clerk at the Office
of the Commissioners of Patents on the 18th June 1879.
DUGALD CLERK, of Glasgow, in the County of Lanark, North Britain, Analytical
Chemist. "IMPROVEMENTS IN GAS MOTOR ENGINES."
This Invention comprises various improvements in gas motor engines of the
kind described in the Specification of Letters Patent granted to the present
applicant and dated 1 August 1878 (No. 3045), such improvements or some of
them being also applicable to other kinds of gas motor engines.
One improvement relates to the parts acted on by the speed governor, and which
control the admission of the combustible gas and air to the compressing pump. In
carrying out this improvement there is connected to the admission valve plate or
slide, by a spring, a stop plate, which, when moving with the valve slide, covers
the ports opened by that slide, and thereby prevents the entrance of gas and air.
When the engine is moving at the proper speed a pin or catch, movable by the
governor, enters a slot or notch in the stop plate, so as to prevent it from moving
with the valve slide and allow the latter to act in the ordinary way, the connecting
spring being then alternately strained and relaxed by the movement of the valve
slide. When the speed of the engine becomes too great the governor releases the
stop plate, which then moves with the valve slide and prevents the admission of
gas and air. Along with the hereinbefore described arrangement there is fitted in
the pipe or passage by which the mixture of gas and air passes from the reservoir
to the power cylinder a stop valve movable by a piston in a small cylinder which
is in communication with the compressing cylinder. Whenever the supply of gas
and air to the compressing cylinder is stopped the consequent reduction of pressure
in that cylinder causes the closing of the stop valve and for the time shuts off the
supply to the power cylinder. Whenever the speed becomes sufficiently reduced
the governor action causes the stop plate to be arrested, and gas and air being then
admitted to the compression cylinder the pressure therein becomes increased and
the stop valve is opened to allow the mixed gas and air to pass to the power-
cylinder.
A second improvement relates to the balancing or partial balancing of the
pressure on the power-cylinder admission valve when constructed as described in
the Specification herein before referred to. In the cover of this valve there is fixed
by means of a ring or frame a diaphragm of copper or other suitable slightly
[Pric

page_text: flexible metal the inner surface of which covers a shallow recess communicating
with the passage in the valve cover. A plate is applied to the outside of the
diaphragm, and is connected by a screw pin to a stationary bar fixed to the framing
of the machine. The effective area of the diaphragm is inade approximately equal
to the maximum area of the cover exposed to outward pressure from the gases in
the valve passages, and as such gases get between the diaphragm and the cover
they exert on the latter an inward counterbalancing pressure.
By a third improvement, more especially designed for comparatively small
engines, a new combination is substituted for the power cylinder admission valve
In this
details described in the earlier Specification hereinbefore referred to.
combination a valve slide arranged partly like the former admission valve is
employed for effecting the ignition of the mixed gas and air, and is worked by an
eccentric or cam, whilst a separate simple conical valve is used for admitting the
mixed gas and air to the cylinder, and is worked by a separate cam or in connection
with the valve slide. In order to cause the ignition the valve slide brings its ports
and the cavity containing the platinum between a port communicating with the
main admission passage and a port in the cover communicating with a cavity, in
which cavity there is at the time less pressure than in the admission passage. In
consequence of this difference of pressure the combustible mixture expands towards
the cavity in the cover, and in doing so becomes ignited by the platinum. The
pressure in the cover cavity is afterwards reduced again in consequence of the valve
slide having a port through it which forms a communication through to the cylinder
passage at the time when the exhaust is taking place. Instead of this the cavity
in the cover might be open to the atmosphere, but such an arrangement would
cause a little unnecessary noise.
The platinum may be heated or kept heated in the manner described in the
earlier Specification hereinbefore referred to; it is not however generally necessary
to have more than one subsidiary stream of gaseous mixture supplied to it. With
a suitable proportioning of the parts the platinum may be dispensed with, the
cavity in the valve slide becoming filled with flame from the subsidiary gaseous
stream, and retaining that flame long enough to ignite the gaseous mixture in the
main admission passage.
A fourth improvement consists in substituting for the piston of the power
cylinder a trunk or plunger fitted to work through suitable packing at the neck or
end of the cylinder and through an external stationary guide, which last is by
preference bored to fit the plunger. The packing consists of metallic rings, of
which there are two or more in contact with the plunger, whilst these are covered
by a single external ring or band. The inner rings are cut through to admit of
their closing on the plunger; and the outer ring or band is also cut to admit of its
contracting, and it is pressed on externally by six or other convenient number of
.curved blade springs, which are adjustable by ineans of screws passing through the
sides of the box. The use of the outer ring is to distribute the pressure of the
springs uniformly over the inner rings.
With this arrangement extremely little lubricant is required and is not exposed
to the great heat of the ignited gases. The lubricant may be conveniently applied
by means of loose fibrous matter placed in an annular recess formed in the packing
box further from the cylinder than the recess containing the rings. The plunger
or trunk is jointed to the connecting rod with a spherical or cylindrical joint, the
ball or the cylindrical joint surface being formed on the end of the rod.
By a fifth improvement the inner end of the plunger or trunk and the inner end
of the cylinder are protected. by layers of asbestos or other suitable refractory
material held in their places by plates of iron or other suitable metal, such plates
becoming considerably heated and thereby enhancing the power developed by the
ignited gases.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Dugald Clerk in the Great Seal Patent Office on the 17th December
1879.
DUGALD CLERK, of Glasgow, in the County of Lanark, North Britain, Analytical
Chemist. 'IMPROVEMENTS IN GAS MOTOR ENGINES."
"
My said Invention comprises various improvements in gas motor engines of tho
kind described in the Specification of Letters Patent granted to me and dated
1 August 1878 (No. 3045), such improvements or some of them being also applicable
to other kinds of gas motor engines.
The improvements comprised in my present Invention are shown on the
accompanying Sheet of explanatory Drawings, in which the same reference
numerals are used to mark the same or like parts wherever they are repeated.
Figure 1 is a side elevation, and Figure 2 is a horizontal section showing a
modification of my first improvement, which relates to the parts acted on by a speed
governor of the ordinary centrifugal or other suitable kind, and which parts control
the admission of the combustible gas and air to the compressing pump. In carrying
out this improvement according to the modification now being described, there is
connected to the admission valve plate or slide 8 by a spring 9 a stop plate 10,
which when moving with the valve slide covers the ports opened by that slide, and
thereby prevents the entrance of gas and air. When the engine is moving at the
proper speed a pin or catch 11 movable by the governor enters a slot or notch in
the stop plate 10 so as to prevent it from moving with the valve slide 8, and
allow the latter to act in the ordinary way, the connecting spring 9 being then
alternately strained and relaxed by the movement of the valve slide. When the
speed of the engine becomes too great the governor by lifting the pin 11 releases
the stop plate 10, which then moves with the valve slide 8, and prevents the admission
of gas and air. The stop plate 10 has ports 12 formed through it so as to be
opposite the cylinder ports 13 (dotted in Figure 2), when the plate is held by the
pin 11, at which time also a cavity on the inner face of the plate 10 allows the
combustible gas to get access to the cylinder port. Along with the herein before
described arrangement there is fitted in the pipe or passage by which the mixture
of gas and air passes from the reservoir to the power cylinder, a stop valve 14
shown in section in Figure 3, and movable by a piston 15 in a small cylinder 16
which is in communication by a passage 17 with the compressing cylinder. When-
ever the supply of gas and air to the compressing cylinder is stopped the consequent
reduction of pressure in that cylinder causes the closing of the stop valve 14, and
for the time shuts off the supply to the power cylinder. Whenever the speed
becomes sufficiently reduced the governor action causes the stop plate 10 to be
arrested, and gas and air being then admitted to the compression cylinder the
pressure therein becomes increased and the stop valve 14 is opened to allow the
mixed gas and air to pass to the power cylinder. A second improvement relates to
the balancing or partial balancing of the pressure on the power-cylinder admission
valve when constructed as described in the Specification herein before referred to, and
is shown in horizontal section in Figure 4. In the cover 18 of this valve there is
fixed by means of a ring or frame 19 a diaphragm of copper or other suitable
slightly flexible metal, the inner surface of which covers a shallow recess com-
municating with the passage 20 in the valve cover. A plate 21 is applied to tho
outside of the diaphragmn, and is connected by a screw pin 22 to a stationary bar 23
fixed to the framing of the machine. The effective area of the diaphragm is mado
approximately equal to the maximum area of the cover 18 exposed to outward
pressure from the gases in the passages of the valve 24, and as such gases get
between the diaphragm and the cover they exert on the latter an inward counter-
balancing pressure.
By a third improvement, more especially designed for comparatively small engines,

page_text: a new combination, shown in horizontal section in Figure 5, is substituted for the
power-cylinder admission-valve details described in the earlier Specification herein-
before referred to. In this combination a valve slide 25 arranged partly like the
former admission valve, is employed for effecting the ignition of the mixed gas and
air, and is worked by an eccentric or cam, whilst a separate simple conical valve 26
is used for admitting the mixed gas and air to the cylinder by the passage 27, and
is worked by a separate cam or in connection with the valve slide 25. In order to
cause the ignition the valve slide brings its ports and the cavity containing the
platinum between a port 28 communicating with the main admission passage 27,
and a port 29 in the cover 18 communicating with a cavity 30, in which cavity
there is at the time less pressure than in the admission passage 27. In consequence
of this difference of pressure the combustible mixture expands towards the cavity 30
in the cover 18, and in doing so becomes ignited by the platinum. The pressure in
the cover cavity 30 is afterwards reduced again in consequence of the valve slide 25
having a port through it which forms a communication through to the cylinder
passage 27 at the time when the exhaust is taking place. Instead of this the
cavity 30 in the cover 18 might be open to the atmosphere, but such an arrangement
would cause a little unnecessary noise.
The platinum may be heated or kept heated in the manner described in the
earlier Specification herein before referred to; it is not however generally necessary
to have more than one subsidiary stream of gaseous mixture supplied to it. The
state of the platinum can be inspected through a small sight hole 31.
With a
suitable proportioning of the parts the platinum may be dispensed with, the cavity
in the valve slide 25 becoming filled with flame from the subsidiary gaseous stream
directed on it from the port 32, and retaining that flame long enough to ignite the
gaseous mixture in the main admission passage.
A fourth improvement is shown in Figures 6 and 7, which are a longitudinal
section and a sectional end elevation, and consists in substituting for the piston of
the power cylinder a trunk or plunger 33, fitted to work through suitable packing
at the neck or end of the cylinder and through an external stationary guide, which
last is by preference bored to fit the plunger. The packing consists of metallic
rings 34, of which there are two or more in contact with the plunger, whilst these
are in some cases covered by a single external ring or band. The inner rings are
cut through to admit of their closing on the plunger, and the outer ring or band is
also cut to admit of its contracting, and it is pressed on externally by six or other
convenient number of curved blade springs 35, which are adjustable by means of
screws 36, passing through the sides of the box. The use of the outer ring is to
distribute the pressure of the springs uniformly over the inner rings. The rings 34
are placed with their cut parts in different positions. With this arrangement
extremely little lubricant is required, and is not exposed to the great heat of the
ignited gases. The lubricant may be conveniently applied by means of loose fibrous
matter placed in an annular recess 37 formed in the packing box further from the
cylinder than the recess containing the rings. The plunger or trunk 33 is jointed
to the connecting rod with a spherical or cylindrical joint, the ball 38 or the
cylindrical joint surface being formed on the end of the rod.
By a fifth improvement the inner end of the plunger or trunk 33 and the inner
end of the cylinder are protected by layers of asbestos or other suitable refractory
material, held in their places by plates of iron 39 or other suitable metal, such plates
becoming considerably heated and thereby enhancing the power developed by the
ignited gases.
Figures 8, 9, 10 show a modification of my first improvement, Figure 8 being an
elevation; Figure 9, a vertical section as at right angles to Figure 8; and Figure 10,
a horizontal section. Instead of as in the first modification (Figures 1 and 2)
applying directly on the outside of the main admission valve slide S a plate (10) for
cutting off the access of gas and air to that slide a separate small slide valve 41 is
applied in a box 42, having a port face with four ports in it. Air enters from
the box by the uppermost and lowermost ports when uncovered by the

page_text: valve 41, and gas is supplied by an inlet 43 to one of the two other ports, which
are put in communication with each other by a cavity in the valve when
it is in the position for admitting air. The air and gas pass by three passages
to the port face of the inain valve slide 8, and going through that slide at one
part proceed through a passage 44 in the cover 45, and then through the
slide 8 again into the cylinder passage 13. At the part of the slide 8 where the air
and gas first pass through it there is a small box, aud the gas entering this box
passes partly through perforations in the sides into the air passages. Some of the
gas passes through perforations in the end of the box into a thin space confined by
a plate, and issues thence in films into the air passages, the object of these arrange-
ments being to insure the intimate mixture of the gas and air. The valve 41 is
worked vertically by a rod 46 jointed to a lever 47, which is centered on a stud 48,
an arm 49 in the same piece with the lever 47 being jointed to a vertical rod 50
moving in a guide 51. A pin fixed to the upper end of the rod 50 carries loosely
ou it a conical roller 52 made with a grooved boss to be acted upon by a forked
lever 53 (shown in Figure 12), which lever is moved by the governor 54. Beneath
the roller 52 there passes the rod 55, which moves the admission valve slide 8,
being itself actuated by an eccentric on the crank shaft; and on this rod 55 there
is fixed a cam block 56 (of a kind shown to a larger scale in Figure 11), being
formed with four longitudinal bevilled surfaces, each fitting the conical pulley 52,
and each having a raised part, as at 57, Figure 11, to raise up the pulley 52, and
with it the rod 50 and lever arm 49. The raised part 57 extends to a different
distance on each of the four bevilled surfaces and corresponds to a different point
of cut-off. The raising of the lever arm 49 causes the other arm 47 to lower the
valve 41 and admit air and gas, and the valve rises again and cuts off the supply
as soon as the raised part 57 of the cam 56 passes the pulley 52. The rod 55 does
not act on the pulley 52 when returning, as the vertical movement which the
eccentric gives it in combination with its horizontal movement takes it too low
down for it to do so.
Figure 12 is a transverse vertical section, showing the governor 54 and some of
the details last hereinbefore referred to for controlling the admission of gas and air
to the compressing cylinder. This Figure also shows details which have to do
with the admission valves of the power cylinder in carrying out one modification
of what is herein before termed my third improvement, partly shown in Figure 5 ;
Figures 13 and 14 are a plan and side elevation of parts at the left hand side of
Figure 12. In this modification the valve 26 for admitting the mixed gas and air
is worked in connection with the valve slide 25, the rod 58 which works that
slide having fixed on it a cam block 59 shown enlarged in Figure 11, and like the
one (56) herein before described as forming part of the details for regulating the
admission to the compressing cylinder. The cam block 59 acts on a conical pulley 60
on a pin fixed in one arm of a bell crank 61, the other arm is jointed to the rod 62
of the valve 26. As the rod 58 moves backwards and forwards and oscillates, the
cam block 59 by one or other of its raised parts (57, Figure 11) causes the valve 26
to be opened, the duration of the opening depending on the position of the pulley 60.
This pulley 60 is movable on its carrying pin, and is formed with a grooved boss to
be acted on by a forked lever 63.
The two levers 53, 63, are jointed to opposite ends of a rod 64, which is in two
parts screwed together, and passing through the base 65 of the governor frame or
bracket, the rod 64 being jointed to a lever 66, which is acted on by the governor
sleeve. The governor spindle is horizontal, and the centrifugal force is opposed by
a helical spring acting between a shoulder on the rod 64 and the inner end of u
tube 67 screwed into the base 65, and conveniently adjustable by screwing in
or out.
Having thus particularly described my said Invention and the manner of
performing the same, I have to state that I do not restrict myself to the precise
details herein described and delineated, but that what I believe to be novel and

page_text: 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 combination of parts herein before described with reference to Figures 1,
2, and 3 of the accompanying Drawings for regulating the speed of the engine by
means of a centrifugal or other suitable governor.
2. The arrangement for balancing or partially balancing the pressure on the cover
of the adinission valve of the power cylinder, hereinbefore described with reference
to Figure 4 of the accompanying Drawings.
3. The combination of admission valve and ignition slide details, herein before
described with reference to Figure 5 of the accompanying Drawings.
4. The application of a trunk or plunger piston in a single-acting gas-motor
cylinder, such piston working through packing rings, arranged as herein before
described with referénce to Figures 6 and 7 of the accompanying Drawings.
5. The application of asbestos or other suitable refractory material to the inner
end of the piston or plunger, and to the inner end of the cylinder, such material
being held in place by a thin metallic shell or cover, substantially as and for the
purposes herein before described.
6. The combination of parts herein before described with reference to Figures 5,
11, 12, 13, 14, for moving the admission valve (26) by means of the eccentric rod
(58), which works the valve slide (25).
7. The application in connection with the compressing cylinder admission valves
of parts similar to those referred to in the next preceding claim, and the con-
nection of those parts with a centrifugal or other suitable governor, substantially as
herein before described.
In witness whereof, I, the said Dugald Clerk, have hereunto set my hand
and seal, this Sixteenth day of December, in the year of our Lord One
thousand eight hundred and seventy-nine.
Witness,
EDMUND HUNT,
Patent Agent,
Glasgow.
DUGALD CLERK. (L.S.)