Improvements in Steam Engines.
Year: 1892

page_text: Date of Application, 20th Jan., 1892
Complete Specification Left, 21st Nov., 1892-Accepted, 14th Jan., 1893
PROVISIONAL SPECIFICATION.
Improvements in Steam Engines.
I, WILLIAM HARDING SCOTT Electrical Engineer of Gothic Works King
Street Norwich do hereby declare the nature of this invention to be as
follows:
By means of this invention the steam can be expanded in two stages in one
cylinder first on one side of the piston & then on the other; and a simple and
efficient arrangement of valves is effected, which will give the requisite steam
distribution.
On one side of the piston, which I will call the top side, the steam is admitted
from a boiler or from a receiver; it is cut off, expanded, & at the end of the stroke
a communication is opened between the top and bottom of the piston, as in tlie old
Cornish engine & the steam passes from the top to the bottom side of the piston as
the piston rises. Now I, in order to get additional expansion of the steam and also
to provide a steam cushion to take up the inertia of the reciprocating parts, close
the valve or valves connecting the top and bottom sides of the piston; when the
piston is only part way up, say half-way, then the steam at the bottom of the
cylinder will be expanded and the steam at the top of the piston will be com-
pressed into the clearance that must be left in the cylinder at the top of the piston;
the amount of this compression should. be as nearly as possible, the same as the
expansion in the cylinder at the top of the piston.
To effect the steam distribution in the cylinder as described above, we may use a
single piston valve or to get the early cut-off requisite in most cases for the top of
the piston, the valve may have another piston valve inside it, working off a different
eccentric & it may be actuated by a governor on the Turner-Hartnell principle, or
we may use a rotary, valve or valves; in one arrangement we have for each
cylinder three flat disc valves with ports in them rotated by a shaft parallel to the
piston rod; the first valve is in the steam chest or receiver as the case may be & it
revolves in a seating which may form an extension of the cylinder cover; this valve
admits steam to the top of the piston. The second valve I should place directly
underneath the first, but in what is clearance space at the top of the piston; this
valve will control the distribution between the top and bottom of the piston. The
third valve should place at the bottom of the cylinder & it may be on an
extension of the cylinder cover; it will control the exhaust from the bottom part
of the cylinder. The ports in each of these valves can be arranged to give any
required opening or cut-off, quite independently of one another, and the pressure on
cach valve is only that due to the difference of pressure between, in the case of the
first valve, the steam chest of the cylinder at the top of the piston, in the second
valve, between the pressure in the cylinder at the top of the piston & at the bottom
of the piston, and in the third valve between the pressure in the bottom of the
piston and the exhaust pipe. In some cases I may place an additional valve
between the second and the third as herein before described, the space between the
second and this additional valve forming a receiver. These valves may be made to
rotate at the same speed as the engine shaft or at a less speed & may be driven by
bevel or worm gearing.
With these flat valves the point of cut-off may be very conveniently altered by
means of an additional disc valve with ports in it on the top of the revolving disc
valve and this may be placed on each or any of the disc valves, hereinbefore
described. These cut off discs would be held stationary by means of a rack and
pinion or other convenient means, which would enable then to be moved from one

page_text: position of cut-off to another from outside the engine by means of the governor or
by hand and the spindles of these pinions may be linked together in such a way
that the cut-off in the exhaust valves may vary the compression at the same time
that the cut-off valve in the admission valve varies the admission of the steam.
In another arrangement a single cylindrical rotary valve may be used with
admission & exhaust ports in its periphery. The steam would enter at the top of
the valve & the exhaust into the atmosphere receiver or condenser would go out at
the bottom, the communication between the top and bottom of the piston being
through the centre of the valve. The admission & exhaust pipes in this valve will
be opposite one another & and there will be, what amounts to, a diagonal partition
between them. The steam will enter the top of the cylinder & as the valve
revolves it will cut off steam at a certain point and the exhaust will open & be
cut off at the proper time as determined by the relative positions of the steam and
exhaust ports and their width. In this arrangement there will be distinct admission
& exhaust ports, both for the top of the piston and the bottom, & there will be a
receiver between the top of the piston and the bottom in which the steam is kept at
approximately constant pressure.
To prevent initial condensation with early cut-off in the top of the cylinder & to
as much as possible superheat the steam there I may place a flat coil or coils of
tubing in the clearance space at the top of the piston and heat these coils by means
of very high pressure steam generated in a coil boiler of the Perkins type the
condensed stean flowing back into the boiler; or the heating may be done by hot
water circulation in the coil as in the Perkins system of heating or it may be done
by the vapour of oil or other substance that boils at a high temperature or by the
liquid itself circulating.
Dated this 10th dox of Tam. 1905
COMPLETE SPECIFICATION.
Improvements in Steam Engines.
1, WILLIAM HARDING SCOTT of Gothic Works, King Street, Norwich, do
hereby declare the nature of this invention and in what manner the same is to
be performed to be particularly described and ascertained in and by the following
statement:-
By meaus of this invention the steam can be expanded in two stages in one
cylinder first on one side of the piston and then on the other, and a simple and
efficient arrangement of valves is provided which will give the requisite steam
distribution.
On one side of the piston steam is admitted from a boiler or from a receiver, it is
cut off and expanded which may be done in the usual manner and at the end of the
stroke a communication is opened to the other side of the piston as in the old
Cornish engine and the steam passes from the top to the bottom side of the piston
as the piston rises. I will for convenience of description refer to the first mentioned
side as the top side and to the other side as the bottom side although of course they
need not be actually in those positions. In order to get additional expansion of
the steam at the bottom side of the piston and also to provide a steam cushion at
the top side of the piston to take up the inertia of the reciprocating parts I cause the
valve or valves giving communication between the top and bottom sides of the
piston to close when the piston has made only part of its upstroke then the steam at
the bottom side of the piston will be expanded and the steam at the top of the
piston will be compressed into the clearance that must be left in the cylinder at the
top side of the piston.
The degree of this compression should ultimately be, as nearly as possible,
such that the clearance space at the top side of the piston is filled up with

page_text: steam compressed to initial pressure, the said clearance space and the point at
which compression is made to begin being proportioned with regard to the initial
pressure rate of expansion and length of stroke to obtain this result.
To effect the steam distribution in the cylinder as above described I use two
piston valves working one inside another and one of them may be actuated by a
governor on the Turner-Hartnell principle or I may use a rotary valve or valves.
In one arrangement illustrated in vertical section in Figure 1 and sectional plan
(on the line 1, 2 Figure 1) in Figure 2 I employ for each cylinder three flat disc
valves with ports in them rotated by a spindle A Figure 1 parallel to the piston
rod A.
The first valve B is in the steam chest or receiver C as the case may be (it is
shewn in steam chest) and I will call it the steam valve.
It revolves on a
seating B which is held in an extension of the cylinder cover. This valve admits
steam to the top side of the piston. The second valve D with its seating EI place
directly underneath the valve B but in what is clearance space D' above the piston.
This valve D controls the distribution of steam between the top and bottom sides of
the piston and I will call it the intermediate valve. The third valve F with its
seating GI place at the bottom of the cylinder. It controls the exhaust from the
bottom part of the cylinder and I will call it the exhaust valve. The ports in each
of these valves can be arranged to give any required opening or cut off quite
independently of one another and the pressure on each valve is only that due in
the case of the steam valve B to the difference of pressure between the steam
chest and the pressure in the cylinder at the top of the piston; in the case of the
intermediate valve D between the pressure in the cylinder at the top side of the
piston and the pressure at the bottom side of the piston and in the case of the exhaust
valve F between the pressure at the bottom side of the piston and the pressure in
the exhaust pipe or passage so that when each valve is open there is no pressure
on it due to the steam. These valves may be made to rotate at the same speed as
the engine shaft but to reduce friction I prefer to make them rotate at a speed
which is a dividend of the crank shaft speed the divisor being the number of ports
in the valves (and their seatings).
In Figure 3 is shewn a plan of one of these valves arranged to rotate at one fourth
the crank shaft speed the vertical spindle A may be driven by bevel or worm or
other convenient gearing and the widths of the ports in each valve are set out as
follows reference being had to Figures 4to 9. Figures 4 and 5 referring to the
steam valve. Figures 6 and 7 to the intermediate valve and Figures 8 and 9 to
the exhaust valve.
For each of the valves I describe a separate circle which I will call the crank pin
circle the direction of rotation of the crank pin being marked by the arrow and
through the centre of this circle I draw a vertical line ab which I will call the piston
stroke line. On this piston stroke line 1 mark the positions that I wish the piston to
be in at the time of opening and closing of the different valves (these positions are
shewn at respectively). Horizontal lines carried from these points to the
circumference of the circle shew the corresponding positions of the crank pin these
horizontal lines being drawn to the right or to the left of the vertical stroke line
according to the direction of rotation of the crank pin and the direction in which
the piston is travelling. For the direction of rotation indicated by the arrow on
circles in the diagrams Figures 4, 6 & 8 these horizontal lines are drawn to the
right of the vertical stroke line when the piston is making its down stroke and to
the left when the piston is making its upstroke.
The total width of all the ports in each valve plus width of all the ports in its
seat measured at a radius which is the same as the radius of the crank pin circle in
the diagrams must be the same as the distance between the point of opening and
closing of the valve measured on the crank pin circle as shewn by the thick part of
the circumferential line which thick part I will call the port line. The ports in
the valve and the seat I generally make of equal width so that with 4 ports the
width of each at the same radius as that of the crank pin circle will be th the length

page_text: of port line and thus I have shewn the steam and intermediate valves in Figures 5
and 7.
In the exhaust valve I have shewn the ports in the seating narrower than those
in the valve but the ports in the valve are made correspondingly wider so that the
two together in each port are one fourth the length of the port line in the diagram
above at the same radius. These valves are keyed onto the spindle A. Figure I
with collars ²² ƒ³and_spun_copper washer collars ³ ³ ³ above them as in
Figure 1 to prevent steam from leaking down by the spindle A the proper relative
positions for the valves on the spindle being arrived at from the diagrams during
erection of the engine. In setting each valve on the vertical spindle which is
geared up to the crank shaft the crank pin is brought to the angular position
indicated by the dotted radial line in each diagram and then the valve must be fixed
to the spindle in such a position that the ports are just opening.
With these flat valves the point of cut-off may be very conveniently altered by
means of additional disc valves B and D³ with radial edges for cutting off on the
top of the valves B and D. One of such disc valves (viz.-that B³) is shewn in
Figure 5. The cut-off disc valves are held.stationary and adjusted by means of a
rack and pinion or other convenient means as by operating rods passing through
stuffing boxes and connected to the said disc valves by pins as shown at d. This
enables the said disc valves to be moved from one position of cut off to another
from outside the engine by means of the governor or by hand and these spindles or
their equivalents may be fastened or linked together in such a way that the cut-off
in the intermediate valve may vary the compression at. the same time that the
cut-off valve on the steam valve varies the admission of the steam.
:
In another arrangement (shewn in vertical section in Figure 10 and in horizontal
section (on the line 3, 4 Figure 10) in Figure 11) a single cylindrical rotary
valve H may be used as shewn distributing steam for two cylinders with admission
and exhaust ports in its periphery. hand being admission and exhaust ports
respectively, and being the intermediate admission and exhaust ports. The
steam enters at the top of the valve and the exhaust, into the atmosphere receiver
or condenser would go out at the bottom at the communication between the top
and bottom of the respective pistons being through the centre of the valve as
at 15 by the ports 1 h. The admission and exhaust ports in this valve will be
nearly opposite one another, (as at hand hand and ²) and there will be what
amounts to a diagonal partition 8 between them. The steam will enter the top
of each cylinder alternately and as the valve revolves it will cut-off steam at a
certain point and the exhaust will open and be cut off at the proper time as
determined by the relative positions of the steam and exhaust ports and their
width. In this arrangement there will be distinct admission and exhaust ports,
both for the top side of the piston and for the bottom side and there will be
a receiver (constituted by the space ½³) between the top side of the pistons and the
bottom side in which the steam is kept at approximately constant pressure the
ports leading into and out of the receiver I will call the intermediate ports.
The method of setting out this valve is as follows:-
A diagram similar to Figure 4 is made as shewn at Figures 12 and 13 with the
position of steam admission, cut off intermediate valve opening, and closing, and
exhaust opening and closing, marked as follows:-Steam valve opens when the
piston is nearly at the top of the stroke at B, being the position of the crank pin
in the crank pin circle at that moment. Steam valve closes when crank pin is
at C. Intermediate valve opens when crank pin is at D and closes when crank pin
is at E. Exhaust valve now opens at B and closes at G and the valve can be set
out from the diagram as follows. It is convenient to set out the crank pin circle to
the same diameter as the valve then the distance round the crank pin circle between
the points of admission and cut off as from 13 to C or D to E width of the port
in the cylinder + the width of the port in the valve then the port H. Figure 13 in
the cylinder and in the valve are each half the distance round from B to C
and the distance between D and E being greater and the same port into the

page_text: =
cylinder is used as the valve rotates the extra distance must be put into the ports
in valve thus the port K in valve + the port K in cylinder from D to E. The
distance round the crank pin circle between the closing of the one valve and the
opening of another + the width of the port into the cylinder will give the distance
between the edge of one port in the valve and the other thus the distance round
the circumference of valve L M Figure 13, is the distance between C D
Figure 12+ N. L, Figure 13, and the distance NO is the distance E. B + N. L.
The exhaust port and bottom intermediate port can be set out in the same way-
they are shewn in dotted lines in Figure 13 and the valve for any other arrange-
ment of steam distribution can be set out by first making a diagram as in Figure 12
with the position of valve opening and closing set off as shewn there.
To prevent initial condensation with early cut off in the top of the cylinder and
as much as possible to superheat the steam therein I may place a flat coil or coils
of tubing in the clearance space of the cylinder at the top side of the piston as
shewn for instance at in Figure 1. and heat these coils to a temperature above
that of the steam of the main boiler by means of very high pressure steam generated
in a coil boiler of the Perkins type the condensed steam flowing back into the
boiler or the heating may be done by hot water circulation in the coil as in the
Perkins system of heating or it may be done by the vapour of oil or other substance
that boils at a high temperature or by the liquid itself circulating. A similar coil.
heated as above may. be used to prevent initial condensation and superheat the
steam in the clearance space or the equivalent of the clearance space in other types
of engines such as engines of the rotary or turbine type.
I am aware that what are called single acting engines are made with valves that
can be arranged so that when the piston gets towards the end of its stroke the steam
that is in the cylinder in the top of the piston can be compressed so that it takes up
the inertia of the reciprocating parts but I do not know of any of these engines
that have their valves specially arranged so that the steam on the underside of the
piston is expanded as hereinbefore explained, after the communication between the
top and bottom of the piston is cut off as with an ordinary reciprocating valve
the early closing of the communication between the top and bottom of the piston
involves necessarily an early opening of the exhaust so that the earlier the com-
pression is effected the carlier the exhaust at the bottom side of the piston is opened.
Now I specially arrange the valves so that when the communication between the
top and bottom of the piston is closed early to get a considerable amount of com-
pression the exhaust valve which lets the steam out at the under side of the piston
to the atmosphere condenser or receiver does not open before the piston reaches the
top part of its stroke except to such an extent as to insure that the steam in the
cylinder gets well away before the piston begins its downward stroke as is usual in
all reciprocating steam engines.
The following explain variations in the arrangements by which this double
expansion of the steam in upper and under side of the single piston can be effected.
Figure 14 shews two separate piston valves which would have to be worked off
different eccentrics. A operates the admission and exhaust from the upper part of
the cylinder and B the exhaust from the lower part of the cylinder and the
admission from the receiver C which forms a communication between the upper and
lower part of the piston. The underside of the valve A cuts off the communication
between the top of the piston and the receiver C and as it can be worked quite
independently of B it can be made to cut off the exhaust from the top of the piston C
during any part of the upstroke after which the steam underneath the piston will
be expanded until the piston is nearly at the end of its stroke and the valve B opens
to the exhaust. The valve A can in this case be very conveniently actuated by a
governor of the Turner-Hartnell type which will with an early steam cut off give
an early closing of the exhaust from the top of the piston to C so that when there
is greater expansion in the top of the cylinder there will be greater expansion in
the bottom of the cylinder and greater compression above the piston thus filling
up the clearance space.

page_text: In Figure 15 I have shewn another arrangement in which the valve B operates
the exhaust from the lower part of the cylinder and also the steam admission
to the upper part of the cylinder and when the piston gets to the bottom of its
stroke it also operates the exhaust opening from the top of the piston into the
receiver C through the special port D and thence into the bottom of the piston
but the steam cut off at the top of the piston and the cut off of the communi-
cation between the top and bottom of the piston I work by the valve A driven
off a different eccentric to the valve B so that these two cut-offs can be worked
independently of the exhaust from the under side of the piston and of the steam
admission to the upper side of piston. The valve A may be very conveniently
driven by a shifting eccentric worked by a governor so that as with the valve A
Figure 14 the compression in the upper part of the cylinder can be increased
when the expansion is increased.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed I declare that what I
claim is
1. In steam engines the combination with a cylinder and piston of a valve or
valves so arranged and operated that steam from the boiler is admitted to and
expanded at one side of the piston from which side after expansion it passes to
the other side through a valve timed to close so that the steam so passed is
expanded on the said other side of the piston the exhaust valve from this last
nained side not opening till the piston is nearly at the end of its stroke the
contents of the cylinder on the first named side of the piston being compressed
so as to attain, at the end of the piston's stroke, a pressure the same as, or
approaching that of the initial pressure.
2. In steam engines the construction or arrangement of disc rotary valves com-
bined with the steam chest or receiver and clearance spaces substantially as
hereinbefore described with regard to Figures 1 to 9 of the accompanying
drawings.
3. In steam engines the arrangement of cylindrical rotary valve with steam and
exhaust ports in its periphery substantially, as hereinbefore described and shewn in
Figures 10 and 11 of the accompanying drawings.
4.. In steam engines the combination of tubing situated in the clearance space
inward of the steam admission valve or its equivalent the said tubing being heated
by means of steam or other fluid of a higher temperature than that of the
steam supplied to the engine substantially as and for the purpose hereinbefore
described.
5. The several arrangements and combinations of parts constituting steam engines
substantially as herein before described and shewn in Figure 1 Figures 10 and 1]
and Figures 14 and 15 of the accompanying drawings.
Dated this 21st day of November 1892.
J. H. JOHNSON & Co.,
Agents.