Improvements in Steam or other Fluid Pressure Engines.
Year: 1896

page_text: Date of Application, 13th Aug., 1896-Accepted, 31st Oct., 1896
COMPLETE SPECIFICATION.
Improvements in Steam or other Fluid Pressure Engines.
I, WILLIAM BATEMAN CRICHTON, of 16 Marlborough Road, Bradford, County
of York, 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:-
This invention relates to fluid-pressure engines and particularly to the valves
and their related parts in single-acting engines. The term "single-acting engine
is, in this specification and its claims, meant to include not only an engine with
one cylinder which is single-acting but also a single-acting cylinder in an engine
which may have two or more cylinders whether the other cylinders be single-
acting or not; and the term "active side" of the piston means that side of a single-
acting piston on which the working fluid acts in producing the effective stroke,
the other side being termed the "idle" side.
One of the objects of this invention is to improve the working of single-acting
engines and render their running smoother by providing means whereby a suitable
compression in the cylinder is obtained; another object being the provision of
means to enable the amount of compression to be varied to suit the different
speeds at which the engine, under different conditions, may ruu.
According to one part of this invention the compression is regulated and the
running of the engine improved by a novel equilibrating and exhaust valve
distinct from the admission valve, and so arranged and operated in relation to
special ports and passages that during the first part of the period of exhaust
from the active side of the piston it permits the working fluid to flow from the
active to the idle side thereof to put both sides of the piston in equilibrium, and
afterwards causes the idle side of the piston to be put into communication with the
atmosphere, or the condenser, or otherwise effects what is ordinarily understood as
the operation of exhaust. The combined equilibrating and exhaust valve is
hereinafter described, by way of example, as a slide valve, although it need not
necessarily be so.
According to another part of this invention means are employed, preferably in
conjunction with an equilibrating and exhaust valve of the kind above referred to,
whereby some of the exhaust fluid can be diverted out of the engine during the
equilibration of the piston, so as to lower the pressure on both sides of the piston,
for the purpose of ensuring that the working fluid shut in before the returning
piston shall not be at so high a pressure as to give rise to excessive compression;
if the engine is intended to work under conditions which are practically constant
the devices employed for diverting the exhaust fluid as aforesaid can be fixed or
permanent, but it is preferable that they should have an adjustable valve herein-
after termed the "auxiliary valve" so that the amount of exhaust fluid diverted
can be varied if desired. For instance, this valve would be fitted to all engines
which normally exhaust into a condenser, but which may at times be required to
work non-condensing, so as to enable the engine to exhaust more freely when
exhausting into the atmosphere than when exhausting into the condenser; the
auxiliary valve would be of service also to regulate the amount of compression in
accordance with variations in the vacuum when the engine is exhausting into the
condenser.
A further part of this invention comprises an engine with two sets of cylinders,
each arranged tandem-fashion; the two cylinders of the lower pair have each a
valve for equilibration and exhaust. of the kind hereinbefore described. and have

page_text: a single admission valve chamber with a single admission-valve in it performing
the functions of admission only for both the cylinders of the lower pair; one end
of this valve controls the admission of the working fluid to one of the cylinders
and the opposite end of the valve controls its admission to the other cylinder.
Preferably this valve is placed between the two cylinders which it controls.
In the accompanying drawings-
Figure 1 is a vertical central section through the cylinder and valve chests of a
single-cylinder single-acting engine fitted with the auxiliary valve and constructed
according to this invention.
Figure 2 is a sectional plan on the line 2. 2 of Figure 1, parts of the exhaust-
valve chamber immediately above the plane of section being indicated in chain
lines;
Figure 3 is a vertical section on the line 3. 3 of Figure 2;
Figure 4 is a vertical section through the four cylinders of a double tandem-
compound engine, with opposite cranks, and single equilibrating and exhaust valve
for each of the low-pressure cylinders, a single steam-admission valve serving both
those cylinders, all according to the present invention; and
Figure 5 is a plan of the engine shown in Figure 4, partly in section on the
line 5. 5 of Figure 4.
Like letters indicate like parts throughout the drawings.
With reference first to Figures 1, 2 and 3, A is the cylinder. B is the piston.
C is the admission valve, and D is the valve chest therefrom. J is the piston rod.
All these parts are substantially the same as are used ordinarily in similar
engines, and operate for the usual purposes; there is however a material difference
between this engine and ordinary engines, which consists in the employment of the
equilibrating and exhaust valve K fixed on the spindle K' and quite distinct from
the admission valve being operated in its own valve chest L by an eccentric or
other valve-operating device specially appropriated to it, in order to control the
operations of equilibration and exhaust in succession in the manner hereinbefore
referred to.
The equilibrating and exhaust valve K, as will be seen from the drawing, is a
cylindrical piston-valve closed at one end.
L' is a passage leading from the cylinder A at its upper end, that is to say,
from the active side of the piston B, into the upper end of the valve chest Li
L2 is a port leading from the lower end of the valve chest L into the lower end of
the cylinder A. L³ is a port leading from the valve chest L at a point just below
the port L' to the exhaust opening L connected with the condenser or atmosphere
or otherwise arranged to divert the exhaust steam out of the engine. The equili-
brating or exhaust valve K in its central position or thereabouts closes both the
ports L' and L³ as in Figure 1. The ports L' L' are formed as is customary, in
a portion of the valve chamber L in which the piston valve K fits and slides, the
valve being of such axial length, and so set, that when the piston is at the top of
its stroke, the port L' is shut, and also that it shall move down to uncover the
port L' at the desired point in the down stroke of the piston B at which it is
desired to put the active and idle sides of that piston into equilibrium; such
equilibration is effected by allowing the steam to flow from the active side of that
piston through the port L and through a passage M (Figures 2 and 3) connecting
the upper and lower parts of the valve chamber L, and by way of the port L' into
the bottom end of the low-pressure cylinder. The equilibrium and exhaust valve K
then moves upward and after having closed the port L' opens the port L³ leading
to the exit L, whereupon the steam from the lower side of the piston B exhausts
through the port L³. The equilibrating and exhaust valve K returns upward
sufficiently scon to imprison a portion of what may be termed the "equilibrating"
steam, to be compressed at the active side of the piston for a purpose well under-
stood by engineers. It will be evident that in this engine the amount of com-
pression will depend on the pressure of the "equilibrating steam at the instant
that the equilibrating and exhaust valve K recloses the port L¹.

page_text: In the operation described the pressure of the "equilibrating" steam is
practically constant throughout the operation of equilibration; but it is possible
to lower the pressure of the equilibrating steam and thereby control the pressure
existing at the moment when the equilibrating and exhaust valve K shuts in some
of the equilibrating steam above the piston for compression; and it is obvious that
by controlling the pressure existing in the cylinder at the commencement of
compression, the amount of compression, may be regulated as desired. To lower
the pressure for this purpose some of the exhausting fluid can be diverted out of
the engine; for this purpose it is preferable unless the conditions under which the
engine operates are constant, to employ the combination with the equilibrating
and exhaust valve operating as described, the auxiliary valve O to control the
amount of the working fluid diverted in accordance with the differing amounts of
compression which may be desired to suit different speeds of the engine or
differences in the working conditions.
From Figures 2 and 3 it will be seen that the equilibrating and exhaust valve K
is closed at its upper end by a diaphragm K, so that there is no clear passage way
through it, the passage M in the valve-chamber leading round the valve froin one
end to the other. Around the middle portion of the valve-chamber proper is an
exhaust jacket N, quite distinct from the passage-way M; into this jacket the
port L' opens, and from this exhaust-jacket connection is made with the condenser
or atmosphere by way of the opening L. In the wall N¹ of the jacket N,
between the latter and the passage M, is an opening M under the control of the
auxiliary valve O which can be operated from outside the engine in any manner
desired, for instance by the hand-wheel O¹ secured on the spindle O which is
screw-threaded and passed through a screw-threaded guide on the wall M' of the
passage M. As the steam to equilibrate the piston B passes from the port L'
past the upper end of the equilibrating and exhaust valve K and into the passage M
towards the port L, part of it can be diverted through the jacket N and passage L*
to exhaust, by opening the valve O, thus varying as may be desired the pressure
available in the operation of equilibration and ennsequently affecting to a propor-
tionate extent the amount of the compression obtained when a portion of the
equilibrating stean is shut in by the return of the equilibrating and exhaust
valve K upward over the port L.
If desired the valve O may be caused to close entirely the passage M; in this
case none of the equilibrating fluid is diverted. In some cases the valve O may
be dispensed with and the passage M, be made of such a size as regulate the
flow to an extent which will give the required compression. This arrangement
would be adopted in the case of engines working under constant conditions of
speed, load, and back-pressure in the exhaust pipe.
In the engine shown in Figures 4 and 5 A are the high-pressure cylinders,
B the high-pressure pistons, E the low-pressure cylinders and F the low-pressure
pistons. The crank shaft P is provided with two cranks P1 P2 set at 180° apart
and each operated by one pair of the tandem pistons BF through connecting
ruds Q Q respectively.
Each of the cylinders E has its own equilibrating and exhaust valve K operating
substantially as and for the purpose hereinbefore described.
The low-pressure steam-valve G and its valve chest H are situated between the
two cylinders; the upper edge G' of the valve G operates to control the steam-
admission port E, leading from the valve chest into one of the cylinders E, and
the lower edge G operates to control the port E³ leading into the other cylinder E.
By reason of the cranks P1 P2 being set at 180° apart the operations of steam-
distribution in one cylinder E are alternate with the like operations in the other
cylinder E, so that the port E' is closed when the port E' is open and vice versa,
and as these ports E E are respectively disposed near opposite ends of the
valve G it follows that if that valve be for instance moving up its upper edge G¹
will close the port E³, while its lower edge G2 opens the port E³, the converse
operation taking place when the valve descends. If a single steam-valve be

page_text: employed in this manner for both the cylinders E, it is placed between the two
cylinders in the manner indicated in Figures 4 and 5, and operated by an eccentric
or other valve-operating device, suitably set upon or controlled from the crauk
shaft P, and enables a very simple and compact engine to be produced.
It is to be clearly understood that the valve G is used only for admitting steam
to both cylinders E and that it does not effect any of the other operations of
distribution of the working fluid.
Although no valve O is shown in connectiou with the passage M, Figure 5 it is
obvious that one night be fitted therein in the manner previously described with
reference to Figure 2.
Conveniently the valve spindle G³ of the valve G can be extended upward as
shown to operate an ordinary steam and exhaust piston-valve C controlling both
the high-pressure cylinders A.
The piston-valves herein before referred to may be solid or recessed cylindrical
bodies provided with piston rings, grooves or otherwise made steam tight; or flat
valves or rotary valves may be employed.
No special mention has herein before been made of the remaining details of the
engines illustrated, for they may be such as are customarily employed in similar
cases.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is.-
1. In a single-acting engine an equilibrating and exhaust valve, a passage M
and ports such as L L L³ operating substantially as and for the purpose
specified.
2. In a single-acting engine a sliding equilibrating and exhaust valve K and a
passage M and ports such as L' L2 L3 under its control operating substantially as
and for the purpose specified.
3. In a single-acting engine the combination with an equilibrating and exhaust
valve of means whereby the pressure of the working fluid producing the
equilibration can be lowered for the purpose specified.
4. In a single-acting engine the combination with an equilibrating and exhaust
valve operating substantially as and for the purpose specified, of an auxiliary
valve for the purpose described.
5. In a single-acting engine the combination with two cylinders such as E,
their pistons operating opposite cranks, and an equilibrating and exhaust valve
of the kind described, of a single admission-valve such as G serving both
cylinders and arranged and operating substantially as and for the purpose
described.
6. The combination and arrangement of parts constituting an equilibrating and
exhaust valve and valve-chest for a single-acting engine with or without the
auxiliary valve O substantially as and for the purpose described and illustrated in
Figures 1, 2, and 3 of the accompanying drawings.
7. The combination and arrangement of parts constituting a single-acting engine
substantially as and for the purpose described and illustrated in Figures 4 and 5 of
the accompanying drawings.
GULYUK
W. B. CRICHTON.
Boult & Wade,
Agents for the Applicant.
W. B. CRICHTON.
Boult & Wade,
Agents for the Applicant.