Improvements in or connected with the Valves of Steam Engines and other Fluid Pressure Motors.
Year: 1894

page_text: Date of Application, 7th Apr., 1894
Complete Specification Left, 7th Jan., 1895-Accepted, 16th Feb., 1895
PROVISIONAL SPECIFICATION.
Improvements in or connected with the Valves of Steam Engines
and other Fluid Pressure Motors.
I, WILHELM SCHMIDT, of Villa Henkel, Wilhelmshöhe, near Cassel, in the
Province of Hesse, Nassau, and Empire of Germany, Civil Engineer, do hereby
declare the nature of this invention to be as follows:-
This invention relates to steam engines and the like fluid pressure motors in
which the exhaust valve or valves is or are operated automatically or in which the
piston forms the exhaust valve and the object thereof is to effect the regulation of
the speed of the motor by means of an auxiliary exhaust port and valve which
controls the compression of the waste steam or other fluid remaining in the cylinder
after the main exhaust port is closed.
Now according to this invention I provide an auxiliary exhaust passage
(preferably parallel to the wall of the cylinder) which passage communicates with
the interior of the cylinder at one end and with the main exhaust passage at the
other.
The port communicating with the cylinder is closed by a valve normally held
open by means of a spring the amount of opening of the said valve being regulated
by means of an adjusting screw or other suitable means.
As soon as the piston has reached the end of its stroke and the exhaust port is
opened by a valve (or by the piston uncovering the same) the greater portion
working fluid escapes through the open port but on the return of the piston after
the main exhaust port is closed the steam or other fluid remaining in the cylinder
will be driven out through the auxiliary port. When however the piston
approaches the end of the return stroke the auxiliary port is closed either by the
piston passing it if the said port is in the wall of the cylinder or if the port is in
the cylinder cover by the piston coming in contact with a projection on the
auxiliary valve.
In the former case the fluid between the piston and the cylinder cover is
compressed until the pressure thereof rises sufficiently to overcome the pressure or
tension exerted on the auxiliary valve by the spring and closes the valve.
If the auxiliary valve is in the cylinder cover the said valve is closed by the
piston itself.
On the piston making the next stroke the entering steam or other fluid keeps
the auxiliary exhaust valve closed until the main exhaust port is opened.
If the speed of the motor increases the exhaust port will be closed before the
fluid has time to escape and the back pressure in the cylinder will close the
auxiliary exhaust valve and prevent racing.
Dated this 7th day of April 1894.
T. E. HALFORD,
11, Furnival Street, Holborn, London, E.C., Agent for the Applicant.

page_text: Improvements in or connected with the Valves of Steam Engines
and other Fluid Pressure Motors.
I WILHELM SCHMIDT of Villa Henkel Wilhelmshöhe near Cassel in the
Province of Hesse Nassau and Empire of Germany Civil 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 steam engines and the like fluid pressure motors in
which the eduction or exhaust valve or valves is or are operated automatically or
in which the piston forms the exhaust valve and the object thereof is to effect the
regulation of the speed of the motor by means of an auxiliary exhaust port and
valve which controls the compression of the waste steam or other fluid remaining
in the cylinder after the main exhaust port is closed.
Now according to this invention I provide an auxiliary exhaust passage or port
(parallel to the wall of the cylinder) which port communicates with the interior of
the cylinder at one end and with the main exhaust passage at the other.
The port communicating with the cylinder is closed by a valve normally held
open by means of a spring the amount of opening of the said valve being regulated
by means of an adjusting screw or other suitable means.
As soon as the piston has reached the end of its stroke and the exhaust port is
opened by a valve or by the piston uncovering the same the greater portion of the
working fluid escapes through the open port but on the return of the piston after
the main exhaust port is closed the steani or other fluid remaining in the cylinder
will be driven out through the auxiliary port. When however the piston
approaches the end of the return stroke the auxiliary port is closed either by the
piston passing it if the said port is in the wall of the cylinder or if the port is in
the cylinder cover by the piston coming in contact with a projection on the
auxiliary valve.
In the former case the fluid between the piston and the cylinder cover is
compressed until the pressure thereof rises sufficiently to overcome the pressure or
tension exerted on the auxiliary valve by the spring and closes the valve.
If the auxiliary valve is in the cylinder cover the said valve is closed by the
piston itself.
On the piston making the next stroke the entering steam or other fluid keeps
the auxiliary exhaust valve closed until the main exhaust port is opened.
If the speed of the motor increases the exhaust port will be closed before the
fluid has time to escape and the back pressure in the cylinder will close the
auxiliary exhaust valve and prevent racing.
In order to make my invention more clear, I will describe the same with reference
to the accompanying drawings, in which similar letters denote similar parts
throughout the different views, and in which:
Fig. 1. shows a vertical longitudinal section through the cylinder of a single-
acting engine, provided with my improved valve.
Fig. 2 is a modified form of the same.
Referring to Fig. 1. a is the cylinder of the engine, 6 the piston, c the induction
port, and d the eduction port.
This latter port extends parallel to the working cylinder and communicates with
the latter by the main outlet d' and the auxiliary outlet d 2. This latter terminates
in an annular channel or groove d3, the lower projecting rim a' forming the seat
for the auxiliary exhaust valve e.
The valve e is shaped in this mode of construction as a casing, the bottom e¹ of
which is kept at a certain distance from the cylinder-cover a 2 by an adjusting-

page_text: screw f, the space thus formed communicates by a channel d with the working-
cylinder a. A spring g tending to keep the valve e constantly open extends into
the inner space of the latter, thus pressing the bottom el against the adjusting
screw f.
This device now operates as follows:
As soon as the piston has reached the end of its forward-stroke (Fig. 1), and
the expanded working fluid escapes through the main-outlet d', the remainder of
the fluid after the outlet d' is closed by the returning piston, will be driven ont
by the latter through the auxiliary outlet d d into the channel d.
There is, consequently, no compression within cylinder a as long as the auxiliary
outlet d² remains open. As soon, however, as this channel is closed by the
returning piston, the small quantity of fluid now remaining in the rear part of
the cylinder is compressed, thus exerting a corresponding pressure on the rear-side
of the bottom e' of valve e.
The strength of spring g is such that the tension of the latter is overcome by the
ressure exerted on valve-bottom by the compressed steam.
The valve e therefore, is then pressed down on its seat a', so that the
communication between the auxiliary outlet d2 and the port d is interrupted
thereby.
The piston is at this time at the extreme end of its stroke and fresh fluid is
entering the cylinder. This fluid keeps as a matter of course the valve e closed,
and the same will remain closed until the piston on its down-stroke has cleared the
main outlet d. When the pressure on both sides of the bottom of the valve e, will
become equal, so that the valve is raised by spring g, and the remaining fluid can
again escape through the auxiliary channel d².
Supposing now the speed of the engine increases and the piston travels with
increased velocity (the same being the greatest in the middle of the stroke) the
exhaust fluid escaping through the annular space between the lower edge of valve e
and the seat a' of the latter will be throttled, the degree of throttling being
dependent on the velocity of the piston and also on the adjustment of screw f, as
will be clear without further explanation.
There arises thus in such a case a difference of pressure in the port d and the
cylinder a i.e. an excess-pressure arises within the latter more or less before the
auxiliary outlet d² is closed by the returning piston. As soon as this excess
pressure has become so great as to be capable of overcoming the tension of spring g.
the valve e will be pressed down on its seat so that the further escape of waste
Huid through channel d² is instantly interrupted.
The greater the velocity of the piston the earlier will this port be closed and the
greater consequently the back pressure created by the increased throttling action
of valve e. In either case the working fluid kept back within the cylinder will be
more or less compressed according to its quantity, so that the speed of the returning
piston and consequently that of the whole engine is correspondingly reduced.
Referring to the modified mode of constructed represented in Fig. 2 the auxiliary
exhaust valve e is arranged directly in the cylinder cover a² and is shown in this
figure in its closed position, the closure being maintained by the steam that after
the closing of the induction port e expands and drives the piston b forward.
As soon as the main outlet d¹ has been cleared by the piston, and the steam
escapes through the said outlet the valve e will be opened by the spring on
account of this latter overcoming now the reacting force of the nearly tensiouless
fluid. If now the piston is travelling inwards and the main-outlet d' has been closed
the remainder of the waste fluid within the cylinder is driven out through the small
annular space between the valve e and its seat into port d until finally, all that fluid
is removed from the cylinder. There is normally no compression at all of exhaust
fluid but the whole of this fluid is expelled.
The closing of the valve e before the admittance of fresh fluid is effected by the
impact of piston b against a projection e³ of the valve. The height of this projection
is so adjusted, that the valve e when being acted on by the piston is moved very

page_text: near its seat, but does not touch the same.
The valve is wholly closed only by the
fresh fluid entering the cylinder I prefer this procedure as otherwise the relative
dimensions of the parts in question would need be of mathematical exactness.
Although the auxiliary eduction valve above described may be used in connection
with any construction of induction-valve a most exact working of the motor may
be obtained by employing the automatic valve-motion described in my English
Patent No. 22490 dated November 23, 1893.
In order to make the co-operation of the said valve-motion with the improved
eduction valve above described and the advantages obtained thereby, perfectly clear
without necessitating reference to said former application I have shown this
combination in Fig. 1 of my drawing, in which the construction of the induction
valve has been slightly altered without influencing however the manner of operation
of the same.
The induction valve is constantly kept under the pressure of spring g', the latter
acting on the flange of the guide-cross h₁ of the said valve in such direction, that
the valve normally is kept open by said spring. The extent of opening of the
valve may be altered by the adjusting-screw f1.
Supposing valve is open and piston 6 has reached the end of its back-stroke
working fluid will enter the cylinder through the small annular space between
valve and its seat; this fluid will be throttled by valve h, in consequence of which
a difference in pressure arises between the fluid above and below the said valve;
that is to say, the fluid within the cylinder will be of a tension somewhat less than
that of the fluid within chamber a³ above the valve.
The piston now travels forward and the working fluid owing to the increasing
velocity of the piston from the end of its stroke to the middle of the same, flows
into the cylinder with a correspondingly increasing velocity, so that the excess of
pressure above valve h becomes greater and greater until finally the said excess has
become so great as to be sufficient for overcoming the counteracting tension of
spring g valve h, therefore is instantly closed at the moment when the piston has
reached its greatest velocity.
The working fluid expands now during the further movement of the piston and
is exhausted finally through the outlet d¹.
The outstroke of the piston being finished the direction of the latter changes as
usual and the remaining waste-fluid is acted on by the returning piston, and acts in
its turn on the auxiliary eduction valve e in the manner above described.
Supposing now the motor were not provided with the said auxiliary eduction
valve, the whole of the remaining waste-fluid would be compressed by the returning
piston this compressed fluid would at the end of the back stroke of the piston be
powerful enough to balance the initial pressure of the working fluid on the valve h.
As soon therefore as the pressures exerted on each side of valve h are equal, the
latter is opened by the spring g' and the cycle of operations is repeated.
In case the pressure of the compressed fluid below the valve h should not be
sufficient to balance the pressure of the fresh fluid above the said valve, the latter
may be provided with a projection extending into the cylinder so that the piston at
the end of its back-stroke will push upon the said projection and thus effect the
opening of the said valve.
It is necessary to provide the inlet-valve with such projections (h³, Fig. 1) when
combining in a motor the said induction valve with the said auxiliary eduction-
valve as normally the compression will be too small for balancing together the
tension of spring g' and the pressure of the fresh fluid.
The combination of both the said valves is on the whole advantageous as the
occurrence of too high a compression at a particularly high speed of the engine is
prevented thereby.
This cannot be attained when employing other constructions of inlets, as for
instance the common slide-valve (Fig. 2) and my improved auxiliary eduction-valve
is therefore especially suited to be used in combination with the automatic induction
notion referred to.

page_text: Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed, I declare that what [
claim is :-
1. In a steam-engine or similar fluid pressure motor an automatic eduction valve
constantly tending to be open, the said eduction valve being adapted to be closel
by an excess of pressure on one side thereof for the purpose as described.
2. In a steam-engine or similar fluid pressure motor an automatic eduction valve
constantly tending to be open the said valve being adapted to be closed by an
excess of pressure on the inside thereof arising from the throttling of the working
fluid, for the purpose as described.
3. In a steam-engine or similar fluid pressure motor an automatic eduction or
exhaust valve constantly tending to be open the said valve being adapted to be
closed by an excess of pressure on the inner side thereof arising from the throttling
of the compression of the waste working fluid for the purpose as described.
4. In a steam-engine or similar fluid pressure motor an automatic exhaust or
eduction valve constantly tending to be open, the said valve being adapted to be
closed by an excess of pressure on the inner face thereof arising from the throttling
action of the said exhaust valve on the waste-working fluid and from the
compression of the latter within the cylinder, for the purpose as described.
5. In a steam-engine or similar fluid pressure motor, an automatic valve espring g
tending to keep the said valve constantly open, the latter being adapted to be
closed by an excess of pressure in cylinder a over the pressure in the exhaust
port or channel d for the purpose as described.
6. In a steam-engine or similar fluid pressure motor, an automatic valve e a
spring 9 tending to keep the said valve constantly open, the latter being adapted
to be closed by an excess of pressure in cylinder a over the pressure in the exhaust
port d the stroke of the said eduction valve being adjustable for the purpose as
described.
7. In a steam-engine or similar fluid pressure motor an auxiliary eduction or
exhaust valve e arranged in the exhaust port d the latter communicating with
cylinder a by the main-outlet d' and the auxiliary outlet d' the latter being adapted
to be closed by valve e by an an excess of pressure of the compressed waste fluid in
cylinder a acting on the inner side e¹ of valve e through channel d spring 9 tending
to keep auxiliary channel d' constantly free of valve e substantially as described.
Dated this 7th day of January 1895.
T. E. HALFORD,
11, Furnival Street, London, E.C., Agent for Applicant.