Improvements in Engines Operated by Steam or other Expansible Fluid.
Year: 1894

page_text: Date of Application, 19th Nov., 1894
Complete Specification Left, 19th Sept., 1895-Accepted, 16th Nov., 1895
PROVISIONAL SPECIFICATION.
Improvements in Engines Operated by Steam or other
Expansible Fluid.
I, WILLIAM HARDING SCOTT of Gothic Works, Norwich in the County of
Norfolk, Electrical Engineer do hereby declare the nature of my invention to be
as follows:-
My invention relates more especially to engines wherein the distribution of
motive fluid is effected as described in the Specification of Letters Patent
No. 1135 of 1892 granted to me and the object of my said invention is to combine
the advantages of such distribution with additional advantages due to the use of
short and direct ports and passages and such a symmetrical and compact arrange-
ment of parts that distortion of the cylinder by unequal expansion is obviated and
there is a minimum of radiating surface. According to my present invention 1
employ a valve of the piston-valve type arranged in the centre of the working
cylinder of the engine and other arrangements as hereinafter described.
The working piston of the cylinder is annular and has two or more piston rods
placed so as to leave the centre of the cylinder clear for a fixed casing for the
reception of the valve the annular piston fitting around the said casing and sliding
thereover it being made steam tight by packing which may be packing rings
applied in the usual way.
I will presume for convenience in the following description that the engine is
a vertical engine but it is to be understood that the invention is not limited to
vertical engines.
The upper end of the valve casing is arranged so that the valve inside it puts at
the proper times the upper part of the cylinder in connection with the steam boiler
or receiver or other place from which the motive fluid is supplied.
I arrange a piston valve inside the said valve casing the said valve being
worked from an eccentric or by other suitable means. I prefer to work it from
the connecting rod of the engine by means of a bell crank or cranks and connecting
levers or links or equivalent arrangements as hereinafter described.
I prefer to have separate ports for the motive fluid admission to above the piston
and for the transfer of motive fluid from above to below the piston and for the
exhaust arranged at three different levels although this is not essential as the two
Where I use three ports or
upper ports or sets of ports may be combined in one.
sets of ports the upper one is near the top of the cylinder for the admission of
motive fluid at initial pressure or from a receiver or its equivalent. The inter-
mediate one is for the passage of motive fluid from the upper side of the piston
into the centre of the valve casing. The lower one may serve both for the
passage of motive fluid from the centre of the valve or valve casing to the under-
side of the piston and also for the exhaust which is opened by the same movement
of the valve which admits motive fluid at initial pressure to the upper side of the
piston. The reverse movement of the valve first cuts off the admission of motive
fluid and later on closes the exhaust and then opens communication between the
upper and undersides of the piston. This communication remains open for a
portion of the upward stroke of the piston. When it is closed either by the
piston covering up the port or by the valve the motive fluid above the piston is
then compressed possibly to a pressure nearly as high as the initial pressure
whilst the motive fluid below the piston is expanded and is not exhausted until
the piston arrives near the top of its stroke.

page_text: To obtain this distribution with a single valve I operate the valve by means of
a bell-crank or its equivalent worked from the connecting rod by means of a short
link. The fulcrum of the bell-crank is so arranged that one end of the crank
which is linked to the connecting rod moves in such a path that the link makes a
much smaller angle with the connecting rod at the top of the stroke of the piston
than it does at the bottom of the stroke of the piston.
The effect of the arrangement of valve gear is approximately the same as would
be obtained from an eccentric if it were shifted during the first part of the revo-
lution from a position of small angularity with the crank so that the valve could
give an early cut off to one of larger angularity at a later part of the revolution
so as to get a later closing of the exhaust and if the eccentric were restored
quickly to its original angularity with the crank during the last part of tho
revolution. For applying the motion to double acting engines there would be a
separate valve and motion for each end of the cylinder.
The motion can be obtained with a single bell-crank by fixing the fulcrum of
the bell-crank at the back of the cross-head slipper or slippers and a little above
the highest point that the cross-head reaches. The upper arm of the bell crank
is then preferably arranged to be approximately horizontal at its mid-stroke and
to terminate sufficiently above the cross-head pin to allow of its movement, the
valve itself being driven from this point in the usual or any suitable way. The
link between the connecting rod and the other end of the bell-crank is a short one.
This motion is applicable to valves generally in which it is required to have an
early cut-off of the motive fluid without affecting the exhaust detrimentally
whether the valves be arranged inside or outside of the cylinder as by altering the
arrangement of the bell-crank. Other arrangements of the bell-crank or its
equivalent may be used that will give the same kind of motion to the link; for
instance the bell crank may be pivotted on or near to the crank-shaft. A slide
may be used to control the motion of the end of the link.
In order to allow for the different expansions due to the different temperatures
of the piston and the cross-head in an engine with an annular piston with two or
more piston rods as described, I may provide separate and distinct cross-head
slippers one fixed to each piston rod and overhung connecting rod pins which work
in these separate slippers so that the slippers themselves can give in the bearings
of the connecting rod pins.
For governing this or other engines in which the motive fluid enters a circular
valve casing from the outside, I employ a moveable slotted ring placed outside
the valve casing in any suitable way so that the slots in it can be made to coincide
with slots in the valve casing when full pressure of motive fluid is required but
which can be made to cover these slots or partly cover them to throttle the motive
fluid as required. The said ring can be moved up and down or round on the valve
casing by means of a link and rod passing through a stuffing box or in any other
suitable way and it can be operated by a governor or by band as desired.
The object of this arrangement is to throttle the motive fluid as close as possible
to the point where it enters the cylinder so as to give better regulation of speed,
and smaller variation of pressure of motive fluid in the cylinder.
In order to allow of the removal of the cylinder and valve cover in engines of
the kind in which the motive fluid enters the cylinder at its centre either through a
hollow piston rod or an extension of a hollow piston or through a fixed valve
casing as herein before described, I connect the admission pipe to the cylinder
itself and I prefer to arrange an annular space between the cylinder and the
outside casing thereof and into this aunular space I admit the motive fluid that
is to work the engine. I prefer to make this annular space only at the upper
part of the cylinder, so that only the upper part of the cylinder is jacketted by
the motive fluid that is passing to the cylinder. I carry this motive fluid from
this aunular space to the valve that is in the centre of the cylinder by means
of a space formed in the cylinder cover and I prefer to arrange this space so that
it makes a complete jacket to the cylinder cover. The inside and outside cylinder

page_text: covers which include this space between them may be in one or in separate castings
or pieces. The annular space around the cylinder can if necessary be drained by
means of a cock in any suitable way at a lower point than that at which the motive
fluid enters and I preferably arrange so that the motive fluid has to go partly round
the cylinder before it gets into the space in the cylinder cover. In this way the
annular space makes, when steam is used, a very efficient steam separator, and it,
as well as the space in the cylinder cover, makes a very efficient steam jacket.
The arrangement of engine with annular piston and central valve hereinbefore
described is very well adapted to receive the heating coil arrangement in the
clearance space above the piston as described in the Specification of my Patent
No. 1135 of 1892, as the motive fluid with this arrangement will enter the cylinder
in such a way that the heat from the coils will act upon it to the best advantage
and in order to prevent the heat of the said coils from overheating the central
piston valve. I place a ring or rings between the central valve casing and the coil
with a narrow space or spaces between this ring or rings and the valve casing and
one another so as to insulate as much as possible the valve casing and the valve
inside from the action of the heat of the coils.
The part of the valve casing which is situated inside the cylinder is preferably
made separate from the part that is inside the cylinder cover so as not to interfere
with the removal of the cover.
Dated this 19th day of November 1894.
JOHNSONS & WILLCOX,
47 Lincoln's Inn Fields, London, W.C., Agents..
COMPLETE SPECIFICATION.
Improvements in Engines Operated by Steam or other
Expansible Fluid.
I, WILLIAM HARDING SCOTT of Gothic Works, Norwich in the County of
Norfolk Electrical Engineer, do hereby declare the nature of this invention and
in what manner the same is to be performed to be particularly described and
ascertained in and by the following statement :-
My invention relates more especially to engines wherein the distribution of
motive fluid is effected as described in the Specification of Letters Patent No. 1135
of 1892 granted to me; and the object of my present invention when applied to
such engines is to combine the advantages of such distribution with additional
advantages due to the use of short and direct ports and passages, and such a
symmetrical and compact arrangement of parts that distortion of the cylinder by
unequal expansion and contraction is obviated and there is a minimum of radiating
surface. According to my present invention, 1 employ a valve of the piston valve
type, arranged in the centre of the working cylinder of the engine and other
arrangements as hereinafter described.
I will describe my invention with reference to the accompanying drawings.
Figure 1 represents in vertical section, the cylinder and valve portion of an
engine constructed in accordance with my invention.
Figure 2 is a view of parts of the cylinder and valve in section shewing
the addition of steam coils as hereinafter described.
Figure 3 is a section of another modification.
Figure 4 is a cross-section on the liue 1. 2. Figure 1.
Figure 5 shews an arrangement for operating the valve and Figure 6 is a diagram
illustrating the movements obtained thereby.
A is the working cylinder and B is the top cover thereof, and C is the working
piston. The said piston is annular and has two or more piston rods D D, placed
so as to leave the centre of the cylinder clear for a fixed casing E for the reception
of the piston valve F, the annular piston C fitting around the said valve casing E,

page_text: and sliding thereover, it being made steam tight by packing, which may be packing
rings applied in the usual way of applying packing rings to pistons.
I will presume for convenience in the following description that the engine is a
vertical steam engine, and such an engine is shewn in the drawings, but it is to be
understood that the invention is not limited to vertical steam engines.
The upper end of the valve casing E is arranged so that the valve inside it puts
at the proper times, the upper part of the cylinder in communication with the steain
boiler or receiver or other place from which the motive fluid is supplied.
The piston valve F inside the said valve casing E is worked from an eccentric or
by other suitable means and the pistons of the valve are so arranged as to control
the passage of motive fluid through the ports and to allow it to pass through the
valve casing as hereinafter described. prefer to work the said valve from the
connecting rod of the engine by means of a bell crank or cranks and connecting
levers or links, or equivalent arrangements as hereinafter described.
I prefer to have separate ports for the motive fluid admission to above the piston
and for the transfer of motive fluid from above to below the piston and for the
exhaust arranged at three different levels, although this is not essential as the two
upper ports or sets of ports may be combined in one as shewn in the arrangement
Figure 3.
When I use three ports or sets of ports, the upper port or ports G is or
are near the top of the cylinder A for the admission of motive Haid at initial
The intermediate port or ports H
pressure, or from a receiver, or its equivalent.
is, or are, for the passage of motive fluid from the upper side of the piston into the
centre of the valve casing. The lower port or ports I may serve both for the
passage of motive fluid from the centre of the valve casing, to the underside of
the piston, and also for the exhaust from the un lerside of the piston, which exhaust
is opened by the same movement of the valve which admits motive fluid at initial
pressure to the upper side of the piston. The reverse movement of the valve first
cuts off the admission of motive fluid and later ou closes the exhaust and then opens
communication between the upper and under sides of the piston. This communi-
cation remains open for a portion of the upward stroke of the piston. When it is
closed either by the piston covering up the port or by the valve, the motive fluid
above the piston is then compressed from terininal pressure possibly to a pressure
nearly as high as the initial pressure whilst the motive fluid below the piston is
expanded and is not exhausted until the piston arrives nearer to the top of its
stroke.
:
To obtain this distribution with a single valve, I operate the valve by means of
a bell crank lever K (Figure 5) or its equivalent worked from the connecting rod L
by means of a short link M. The fulcrum k, of the bell crank lever K, is so
arranged that the end N of the said crank lever which is linked to the connecting
rod L, moves in such a path that the link M makes a much smaller angle with the
connecting rod at the top of the stroke of the piston than it does at the bottom of
the stroke of the piston. This will be readily seen by reference to the diagram
Figure 6 where the lines which correspond to the bell-crank the connecting rod
and the link are marked with the same letters as in Figure 5. 1 is the point of the
upstroke for steam admission, 2 the point in the down stroke for steam cut off,
and 3, 4 and 5 the points in the down stroke respectively for exhaust cut-off, of
opening for transfer of motive fluid from one side of the piston to the other and of
the cut off of such transfer, and 6 is the point in the upstroke at which the exhaust
opens but it is to be understood that I do not limit myself to these particular points
of control. The effect of this arrangement of valve gear is approximately the
same as would be obtained from an eccentric if it were shifted during the first part
of the revolution from a position of small augularity with the crank, so that the
valve could give an early cut-off to one of larger angularity at a later part of the
revolution so as to get a later closing of the exhaust, and if the eccentric were
restored quickly to its original angularity with the crank during the last part of
the revolution.

page_text: For applying this motion to double acting engines there would be a separate
valve and motion for each end of the cylinder.
The motion can be obtained with a single bell-crank by fixing the fulcrum of
the bell-crank at the back of the cross-head slipper or slippers (not shewn in the
drawings) and a little above the highest point that the cross-head reaches.
The connecting rod L is a double one with a space between the parts. The upper
arm of the bell-crank is then preferably arranged to be horizontal, or very nearly
horizontal, at its mid-stroke, and to terminate sufficiently above the cross-head pin
to allow of its movement, the valve itself being driven from this point in the usual
or any suitable way.
The link between the connecting rod, and the other end of the bell-crank is
a short one. This motion is applicable to valves generally in which it is required
to have an early cut-off of the motive fluid without affecting the exhaust
detrimentally whether the valves be arranged inside or outside of the cylinder,
as by altering the arrangement of the bell-crank, other arrangements of the
bell-crank, or its equivalent, may be used, that will give the same kind of
motion to the link, for instance, the bell-crank may be pivotted on or near to
the crank shaft. A slide may be used to control the motion of the end of
the link.
In order to allow for the different expansions due to the different temperatures
of the piston and the cross-head in an engine with an annular piston with two
or more piston-rods as described, I may provide separate and distinct cross-head
slippers one fixed to each piston rod and overhung connecting rod-pins which work
in these separate slippers, so that the slippers themselves can give in the bearings
of the connecting rod pins.
For governing this or other eugines in which the motive fluid enters a circular
valve casing from the outside, I employ a moveable slotted ring e placed outside
the valve casing in any suitable way, so that the slots e in it can be made to
coincide with slots in the valve casing when full pressure of motive fluid is
required, but which can be made to cover these slots, or partly cover them, to
throttle the motive fluid as required. The said ring can be moved up and down,
or round on the valve casing by means of a link and rod passing through a
stuffing box or in any other suitable way, and it can be operated by a governor
or by hand as desired. In the arrangement shewn it is operated by being moved
round by a pinion e on the rod e*.
The object of this arrangement is to throttle the motive fluid as close as
possible to the point where it enters the cylinder, so as to give better regulation
of speed and smaller variation of pressure of motive fluid in the cylinder.
In order to allow of the removal of the cylinder and valve cover in engines of
the kind in which the motive fluid enters the cylinder at its centre, either
through a hollow piston rod or an extension of a hollow piston, or through a
fixed valve casing as herein before described, I connect the admission pipe to the
cylinder itself and as the passage to admit the motive fluid to the cylinder
I prefer to arrange an annular space A² between the cylinder, and the outside
casing A³ thereof and into this annular space A2 I admit the motive fluid that
is to work the engine by the admission pipe attached at A. I prefer to make
this annular space A only at the upper part of the cylinder, so that only the
upper part of the cylinder is jacketed by the motive fluid that passes through
this space to the cylinder. The motive fluid is conveyed from this annular
space to the valve that is in the centre of the cylinder by means of a space P,
formed in the cylinder cover B, and I prefer to arrange this space P so that it
makes a complete jacket to the cylinder cover. The inside and outside portions
of the cylinder cover which include this space between them may be in one
casting or piece, or in separate castings or pieces. The annular space A² around
the cylinder can if necessary be drained by means of a cock in any suitable way
at a lower point than that at which the motive fluid enters and I preferably

page_text: arrange so that the motive fluid has to go partly round the cylinder before it
gets into the space in the cylinder cover. In this way this annular space makes
when steam is used as the motive fluid a very efficient steam separator, and it,
as well as the space P in the cylinder cover, makes a very efficient steam jacket.
The exhaust opening is shewn in Figure 1 on the line of section for the sake
of clearness, but in practice it would be placed 90° round the cylinder, one way
or the other, so as not to come in the way of the piston rods.
The arrangement of engine with anuular piston and central valve hereinbefore
described is very well adapted to receive the heating coil arrangement in the
clearance space above the piston as described in the Specification of Letters
Patent No. 113 of 1892 granted to me as the motive fluid with this arrangement
will enter the cylinder in such a way that the heat from the coils will act upon it
to the best advantage. Figure 2 shews the coil Q thus applied, and the slight
modifications necessary or advisable to accommodate the said coil.
In order to prevent the heat of the coil or coils Q from overheating the central
piston valve, I place a ring R or rings between the central valve casing E and the
coil Q with a narrow space s or spaces, between this ring or rings, and the valve
casing so as to insulate as much as possible the valve casing and the valve inside
from the action of the heat of the coils.
The part of the valve casing E which is situated inside the cylinder (viz.: the
part from a to y) is preferably made separate from the part that is inside the
cylinder cover so as not to interfere with the removal of the cover.
The said part is attached to the bottom part of the cylinder in the arrangement
shewn.
In the arrangement shewn in Figure 3. there is a smaller amount of compression
above the piston and of expansion under it, the ports H (of Figure 1) being
.omitted, the ports h² auswering the purpose of the ports H in Figure 1, and the
valve controlling the passage for motive fluid through the port from above to
below the piston instead of its being controlled by the main piston through the
ports Has in the arrangement Figure 1. The part of the valve marked
Figure 1 is omitted in the arrangement Figure 3. and the port 2 being widened to
fit it to pass the motive fluid from one side of the piston to the other as well as to
Ladmit the live motive fluid to above the piston. This valve can be operated by an
.arrangement such as that shewn in Figure 5.
in
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 engines with an annular piston and a distributing valve working in a
central valve case, the arrangement of the valve, and means for operating it, so
that motive fluid is admitted into the one end of the cylinder from the motive
fluid chest, or receiver, and, after expansion of the said fluid, a communication
between the cylinder spaces on each side of the piston is opened, so that, during the
stroke, (or part of the stroke,) away from the crank shaft, motive fluid is transferred
from one side of the piston to the other, and, when the piston reaches the end of the
said stroke, (or thereabouts), the exhaust is opened; substantially as hereinbefore
described.
2. In engines as claimed by the preceding claiming clause, the arrangement of
the valve in combination with ports in the central valve casing which ports are so
arranged that the inner edge of the annular piston cuts off communication from
Souc side to the other of the piston, causing compression of the motive fluid, from
tera inal pressure, on one side of the piston, and expansion of the motive fluid on
the other side of the piston; substantially as herein before described.
3. In engines as claimed by the preceding first claiming clause, the arrangement.
of valve, in combination with ports in the central valve casing, so that the valve
cuts off communication from one side to the other of the piston, so as to cause

page_text: compression of the motive fluid, from terminal pressure, on one side of the
piston; substantially as hereinbefore described and shewn in Figure 3 of the
accompanying drawings.
4. An arrangement of valve gear, as described, by which a valve, or valves, is,
or are, worked through a bell-crank, or bell-cranks, (or its, or their, equivalent,) by
means of a short link worked from the connecting rod, the bell-crank fulcrum, or
fulcra, being so arranged that the end of the bell crank, or the like, which is
linked to the connecting rod, moves in such a path that the link makes a much
smaller angle with the connecting rod at one end of the stroke of the piston than
it does at the reverse end of the stroke of the piston, so as to give an early cut off
of the motive fluid which enters during the first named part of the stroke, and a
late closing and opening of the exhaust due to the angle of advance being altered
between the portions of the stroke; substantially as hereinbefore explained with
reference to Figures 5 and 6 of the accompanying drawings.
5. The arrangement of throttle valve, as described, in which an annular ring
placed round the outside of a fixed valve casing is made to throttle the motive
fluid by movement round, or upon, the casing, there being orifices in the casing
corresponding to orifices in the throttling ring, so that the orifices can be closed,
more or less, by operating the throttling ring; substantially as herein before
described.
6. In an engine with a central valve casing and valve and annular piston, or
wherein the motive fluid enters the cylinder at the centre through a hollow piston
rod, or an extension of a hollow piston; an annular space enclosed by a casing
outside of the cylinder, so that the motive fluid pipe can be fixed to the outside of
the said casing, and the motive fluid be led round to a space arranged between the
inner and outer parts of the cover of the cylinder and thence taken to the valve,
(or piston rod, or extension of the piston,) in the centre of the cylinder, and so
that the whole of the cylinder cover, and its attachments, can be taken off, and
the valve and piston examined, without breaking any motive fluid pipe joints ;
substantially as hereinbefore described.
7. The combination with engines having an annular piston and a central valve
as described, and having a heating coil in the clearance space to which live motive
fluid is admitted of a ring, or rings, to prevent over-heating of the valve casing and
valve; substantially as herein before described.
8. The arrangement of the valve casing in an engine with a central valve and
an annular piston in which, to enable the cover to be removed without disturbing
the valve casing, the said valve casing, or the part thereof within the cylinder, is
fixed to the end of the cylinder opposite to that from which the cover is to be
removeable; substantially as herein before described.
9. The arrangement and combination of parts substantially as, and for the
purpose, hereinbefore described, and shewn in Figure 1 of the accompanying
drawings.
10. The arrangements and combinations of parts constituting motive power
engines substantially as hereinbefore described and illustrated in Figures 1 and 5,
or in Figures 3 and 5, of the accompanying drawings; as a whole.
Dated this 19th day of September 1895.
JOHNSONS & WILLCOX,
Agents.