Improvements in High-pressure Steam Engines.
Year: 1893

page_text: Date of Application, 10th Apr., 1893
Complete Specification Left, 5th Jan., 1894-Accepted, 10th Apr., 1894
PROVISIONAL SPECIFICATION.
Improvements in High-pressure Steam Engines.
I, WILHELM SCHMIDT, of Henkel Villa, Wilhelmshöhe, near Cassel, in the
Empire of Germany, Civil Engineer, do hereby declare the nature of this
invention to be as follows:-
Heretofore steam superheated to 650 degrees, could not be used with advantage,
owing to the packing of the piston and that of the inlet and outlet mediums not
being able to resist such a high pressure.
To produce an efficient piston packing has in particular been a failure as at such
high pressure no lubricant will stand and an external cooling of the cylinder causes
a great loss of power to render it sufficiently cool.
The steam engine hereinafter described renders the use of steam superheated, for
instance to 550 degrees possible without disadvantage to the engine and embodies
two improvements which are applied jointly to obviate the said defects, as
follows:--
And in order that my invention may be more fully understood I have caused to
be appended hereunto one sheet of drawings marked with letters of reference
indicating like parts in the various figures.
Firstly, the piston k having a packing ring r, is furnished with an extension a of
such a size and the steam cylinder prolonged correspondingly to such an extent,
that the piston rings will only move in that part of the cylinder with which the
already expanded steam will only come into contact, i.e. with such steam has
already lost its superheat through the expansion.
The piston rings thus never come into contact with the part of the cylinder
which is directly exposed to the action of the highly superheated steam. It will
be evident that the small amount of superheated steam, which is contained between
the cylinder wall and the piston extension at the beginning of the piston stroke,
owing to the respective small space, cannot be of any consequence to the cylinder
wall in respect of warming the same.
The size of the piston extension is generally dependent on the degree of the
superheat of the steam or degree of expansion and it may be taken into con-
sideration, that at higher steam pressures or by expansions to vacuum, the exhaust
of the steam will occur again at comparatively short parts of the piston strokes.
There is thus a correspondingly smaller piston extension necessary, whilst in the
contrary case a correspondingly larger piston extension is required.
Secondly, the inlet and outlet valves, of the engine which works with highly
superheated steam, are in this invention combined in such a manner in one casing,
that the inlet valve, which is hollow and conducts the highly superheated steam, is
cooled by the steam of the engine carried off by the outlet valve.
The substantial novelty of this valve gear consists in arranging in a casing inlet
and outlet valves which are apart from each other and moved separately, whereby a
double advantage is obtained, viz. that of the hollow inlet or expansion valve
being completely cooled by the exhaust steam and that of the outlet valve, which
is moved independent of the inlet valve permitting of any suitable compression.
Heretofore in engines with piston like valves, the inlet and outlet have been
effected by one valve only, or a special expansion valve has been arranged in the
Galva

page_text: Under ordinary circumstances a very high compression is obtained by the use of
one valve only for smaller volumes of steam as is well known, this will be the case
in a much larger degree, by superheated steam, because the' hot cylinders and
piston walls cannot take up more compression heat, on the contrary will impart
warmth to the steam which is to be compressed.
It is thus necessary to employ separate inlet and outlet valves in order to
provide for a proper cooling and prevent a too high compression.
The engine for superheated steam is shown in Figs. 1-3.
Fig. 1 shows the steam cylinder and outlet valve of the engine in section.
Fig. 2 shows a front view of the steam cylinder and a section through the inlet
and outlet valve of the engine.
Fig. 3 shows a horizontal section through the valve box.
Fig. 1 shows the conditions of temperature and pressure during one stroke of
the piston.
As will be seen, owing to the extension a, the piston rings r will always work in
those parts of the cylinder walls in which the steam has already expanded and
thus a considerable lowering of the temperature taken place. These parts of the
cylinder will therefore never be at a temperature which would render lubricant
inoperative. The steam for the cylinder is introduced by the pipe b, m is the inlet
valve for the steam cylinder, the lever for the outlet valve.
There are two cylinders provided, which are fed by the same inlet valve, the
outlet of the steam being controlled by one valve only and for which purpose
annular channels c, c', c² are arranged.
6 is the outlet pipe for the steam, and it will be seen that the same passes
through the annular channels c¹ & c when the outlet valve m' is lowered or raised
respectively and through the latter and as well as through the hollow inlet valve m
to the outlet pipe b' which must effect a cooling of the valve m.
Dated this 8th day of April 1893.
F. BOSSHARDT & Co.,
Agents to Applicant.
COMPLETE SPECIFICATION.
Improvements in High-pressure Steam Engines.
I, WILHELM SCHMIDT, of Villa Henkel, Wilhelmshöhe near Cassel, in the
Province of Hesse-Nassau, German Empire, 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:-
It has not been possible up to now to use strongly superheated steam (up
to 350° C.) with advantage in steam-engines, as the packings of the piston as well
as those of the inlet and outlet-organ were not sufficiently resistive to such high
temperatures. This refers especially to the piston, as there exists no lubricant
which can stand the said temperature; if, for properly cooling the inner surface
of the cylinder, the latter is cooled from the outside, considerable losses of power
are caused which highly decrease the effect of the engine.
By employing now the two arrangements hereinafter described, I have succeeded
in using with advantage superheated steam of from 300 to 350° C.; the said
arrangements refer to the piston as well as to the inlet and outlet, and I prefer to
employ both the new arrangements simultaneously, in order to attain the highest
degree of efficiency.
Concerning, first, the piston (k, Fig. 1), the latter has the packing-rings r, and
is provided at its rear with an elongation a of a diameter corresponding to that of
the piston proper. The cylinder, too, is elongated as much as required for the
elongation of the piston, and such a size is chosen for this latter elongation, that
the packing rings of the piston move but in that part of the cylinder which is

page_text: washed by the already expanded steam, i.e. by such steam that has lost the greatest
part of its hgh temperature by expansion. The packing-rings, thus, never touch
that part of the cylinder-wall which is washed by the highly superheated steam,
and the high temperature of the latter cannot be, therefore, of any noxious influence
on said rings.
The size of the elongation of the piston is dependent in general either on the
degree of superbeating or on the degree of expansion, and it should be borne in
mind, that at high tensions of steam or at expansion into a vacuum the saturation
of the steam arises already after a comparatively short way of the piston. There
is, thus, necessary, in either of these cases, a piston-elongation of but small size,
whilst in all contrary cases an elongation of a corresponding greater size is
required.
Concerning, further, the inlet- and outlet-organs which shall be passed by the
strongly superheated steam, the same are arranged in one casing in such a manner,
that the inlet-slide-valve, which is made hollow and which is exposed at its outside
to the high temperature of the highly superheated steam, is passed by the exhaust-
steam leaving the cylinder, this steam being led through the channel of the
inlet-slide-valve, thus cooling the latter.
The essential novelty of this arrangement lies in the employment of separate
and separately moved inlet and outlet-valves situated in one and the same casing,
by which arrangement I gain the double advantage of cooling the hot inlet-valve
completely by the waste steam, and of being able to use any desired compression,
as the outlet-valve is moved independent of the inlet-valve.
The inlet and outlet in piston-valve-engines has been performed hitherto either
by but one valve, or with the aid of a special expansion-valve arranged within the
outlet-valve. If but one valve is employed for low degrees of filling, a very high
compression is got under ordinary circumstances; this, however, is still far more
the case, if superheated steam is used, as the hot walls of the cylinder and piston
are unable of taking up any amount of the compression-heat, but, in contrary, add,
or give off, heat to the steam to be compressed. It is, therefore, necessary, to
employ separated inlet- and outlet-valves for the purpose of attaining a strong
cooling, and for preventing too high compressions.
In order to make my invention more clear, I refer to the accompanying drawing,
representing one mode of execution of my invention, and in which:
Fig. 1 shows a longitudinal section through the cylinder of a steam-engine
provided with my improvements.
Fig. 2 shows a vertical section through the valve-box and through the two
piston-like slide-valves.
Fig. 3 shows a horizontal section through the valve-box, and
Fig. 1 shows the conditions of temperature and pressure during one stroke of
the piston.
As to be seen from Figs. 1 & 1^, the packing-rings of the piston are working
always in that part of the steam-cylinder, which is not exposed to the high heat
of the superheated steam; when the piston has proceeded from its dead point a
distance corresponding to the length of its elongation, the temperature of the steam
is sunk then so much, that the latter cannot be of injury to the packing-rings and
to the lubricant used therefor.
The steam enters the valve-box through pipe b, and flows, first, into the annular
channel c, from which it is led into one or the other cylinder according to the
position of the inlet-valve m. The position of this valve, in Fig. 1, is such a one,
that the two annular channels c' and c² above and below channel c are closed,
i.e. are not in communication with said channel c, and it is to be seen from Fig. 2,
that the position of the outlet-valve m¹ is a like one.
If, now, for instance, channel c¹ belongs to the left-hand cylinder, Figs. 2 & 3,
and channel to the right-hand cylinder, and if both the valves m m' are lowered,
such a distance that channel c¹ comes into communication with the inner space of
valve m³, but not with that of valve m, the fresh steam will then pass the contracted

page_text: central part of valve m, and will enter the said right-hand cylinder through
channel, whilst the steam escaping out of the left-hand cylinder through
channel flows partly through the shorter hollow outlet valve m³, and partly
through the hollow inlet-valve m, so that this latter, consequently, is cooled, as
desired. Again, if both the valves m and m³ are raised, the fresh steam is led
through channel c¹ into the left-hand cylinder, whilst the waste-steam of the right-
hand cylinder now escapes through channel c³, and a part of it also flows
through the hollow valves m' and m, so that again this latter is cooled, 6' is
the waste-pipe.
The whole inner surface of the hollow inlet-valve m is, thus, washed by the
cooler waste-steam, whilst but a small part of the outer surface of valve m is
touched by the superheated steam, so that any intense heating of said valve is very
effectively prevented.
It will be seen, thus, that a steam-engine may well be driven by highly super-
heated steam, if both the improvements above described are employed simultaneously,
the more, as the effect of both arrangements is a good one not only in the beginning,
but remains so during the whole time of working.
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 I
claim is :-
:―
1. A steam-engine for the use of superheated steam, characterized by a piston
with an elongation or with elongations of such size, that the packing-rings of the
piston touch but that part of the cylinder which is washed by steam already partly
expanded or saturated, for the purpose as described.
2. A steam-engine for the use of superheated steam characterised by having its
inlet-valve or -valves and outlet-valve or -valves arranged in one and the same
valve-box, and by having said inlet-valve or -valves made hollow so that it or
they respectively may be passed by the exhaust-steam of the engine, for the
purpose as described.
3. A steam-engine for the use of superheated steam, characterised by having its
inlet-valve or valves and outlet-valve or -valves arranged in one and the same
valve-box and by having said valves made hollow, so that the exhaust-steam of the
engine may be led by the hollow outlet-valve or -valves to and through the hollow
inlet-valve or -valves, for the purpose of cooling the latter.
4. A steam-engine for the use of superheated steam, characterised by having
hollow piston-like inlet-valve or -valves arranged in one and the same casing, the
channel or channels of the outlet-valve or -valves being adapted to conduct the
exhaust-steam to the channel or channels of the inlet-valve or -valves, for the purpose
of cooling the latter.
5. In a steam-engine for the use of superheated steam, the combination with a
piston having an elongation or elongations of such size, that the packing-rings of
the piston touch but that part of the cylinder which is washed by steam already
partly expanded or saturated, of hollow inlet-valve or-valves adapted to be washed
by the exhaust-steam, for the purpose as described.
6. In a steam-engine for the use of superheated steam, the combination with a
piston having an elongation or elongations of such size, that the packing-rings of
the piston touch but that part of the cylinder which is washed by steam already
partly expanded or saturated, of hollow inlet-valve or -valves and hollow outlet-
valve or -valves, the latter being adapted to conduct the exhaust-steam to the
inlet-valve or -valves, these being adapted to conduct that steam to the waste-pipe,
for the purpose as described.
7. In a steam engine for the use of superheated steam, the combination with a
piston having an elongation or elongations of such size, that the packing-rings of
the piston touch but that part of the cylinder which is washed by steam already
partly expanded or saturated, of hollow piston-like inlet-valve or -valves, and
similar outlet-valve or -valves, all valves being arranged in one and the same

page_text: casing, the channel or channels of the outlet-valve or -valves being adapted to
conduct the exhaust-steam to the channel or channels of the inlet-valve or -valves
for the purpose of cooling the latter.
Dated this 4th day of January 1894.
F. BOSSHARDT & Co.,
4, Corporation Street, Manchester, Agents for the Applicant.