Improvements in or relating to Steam Engine Cylinders.
Year: 1887

page_text: Date of Application, 2nd Aug., 1887
Complete Left, 1st May, 1888
Complete Accepted, 22nd June, 1888
Improvements in or relating to Steam Engine Cylinders.
I, FRIEDRICH WISKE of Barum near Brunswick, Germany, do hereby declare the
nature of this invention to be as follows:-
In steam engines working on the expansion system great loss of power is sustained
by the high pressure steam coming in contact with those parts of the cylinder (such
as the cylinder cover, exhaust port, and slide or, valve) which have been in contact
with the watery low pressure steam after great reduction of temperature.
The condensed water, cooled, and increased by the expansion increases the cooling
of these parts and thereby the condensation of the high pressure steam in a high
degree as the, conducting property of the cylinder jacket is not sufficient to replace the
abstracted heat.
To prevent or to decrease these disadvantages the exhaust port is differing from the
ordinary construction not placed at the end of the cylinder near the inlet port but is
arranged in the side of the cylinder in such a manner that the piston in its back
stroke passes quite or at least so far over the exhaust port that the high pressure
steam coming into contact with it has done already the greater or greatest part of its
work and is therefore already comparatively cooled and the condensation taking place
will therefore be comparatively small.
For double acting engines a single exhaust port is preferably arranged in the
middle of the side of the cylinder and opened and closed by a slide valve. This slide
valve is formed with a slot corresponding with the section of the exhaust port and is
operated by an eccentric on the crank shaft which is set at a lead angle of 60 degrees
to the crank.
The eccentricity of this eccentric may be 141 of the width of the slot of the slide
valve so that in a quarter revolution of the crank the exhaust port is alternately
opened and closed.
The following five positions of the slide valve and the piston will illustrate the
working of the arrangement.
1. The slide valve will begin to open when the crank is still 15 degrees and the
piston 0.02 degrees of its full stroke away from the dead point the steam will therefore
not be quite enclosed when not acting and cannot do any damage.

page_text: 2. The exhaust port will be opened 0.3 of its width when the piston begins again to
work at the dead point whereby the compensation of the pressure between cylinder
and condenser or the atmospheric air is nearly attained.
3. The exhaust port will be fully opened when the piston has only travelled 0·07 of
its full stroke.
4. When the piston has travelled 0.37 of its full stroke the exhaust port will be
closed again and the piston passing over the exhaust port will compress the enclosed
rest of the steam.
5. The slido valve and piston will be in a similar position to that explained in 1,
when the crank has made half a revolution and the same operation will be repeated
during the second half of the revolution.
As the wide exhaust port which is only open for a short time forces the steam from
both sides of the cylinder to expand towards the middle, no mixing motion of the
steam can take place in the depth of the cylinder and no opportunity is therefore
offered to abstract heat from the inner surface of the cylinder especially as the heat
radiating power of the sides of the cylinder is very small because of its polished
surface. Besides the steam jacket of the cylinder compensates the small loss of heat
during the expansion and keeps the cylinder sides at a uniform temperature.
As therefore the compressed rest of the steam does not find any condensing surfaces
it will fill the sinali noxious room as full pressure steam without loss, and the power
lost through the compressing is gained again through the following expansion.
To prevent an excess of compression the cylinder can be provided at the ends with
safety valves which may consist merely of loose cones.
Through this arrangement the two causes of wasting steam in the cylinder are
prevented without making the engine more complicated. In compound engines only
the effect of the first cause is diminished by the distribution of the expansion over two
or more cylinders.
It is evident that any other suitable valve or slide may be used instead of the herein
described slide valve and that an exhaust port may be arranged for each side of the
cylinder instead of one for each side of the cylinder in the middle as herein described;
but if so the exhaust port must be at least 15 per cent. of the stroke of the piston away
from the cylinder cover to prevent the latter and the sides of the cylinder from cooling
through the rotary motion of the steam to be exhausted.
Dated this 2nd day of August 1887

page_text: I, FRIEDRICH WISKE, of Barum, near Brunswick, in the German Empire,
Manager, 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:-
In steam engines working on the expansion system great loss of power is sustained
by the high pressure steam coming in contact with those parts of the cylinder (such
as the cylinder cover, exhaust port, slide or valve and partly the piston) which
have been in contact with the watery low pressure steam after great reduction of
temperature.
The condensed water forming increases the cooling of these parts in a high degree.
To prevent or to decrease these disadvantages the exhaust port, which is arranged
in the side of the cylinder at a distance from the cylinder cover of at least 15 per
cent. of the stroke of the piston, will not he opened by its valve motion regulated by
the crank shaft until the piston impelled by the steam has passed the exhaust port and
is at a distance from it of at least 15 per cent. of its stroke, and will be closed before
the piston has passed it on its return stroke. When the high pressure steam comes
into contact with the exhaust port it has already done the greater or greatest part of
its work and is therefore already comparatively cooled and the condensation taking
place will therefore be comparatively small.
The accompanying drawings represent a longitudinal section of a cylinder provided
with this arrangement.
For double acting engines a single exhaust port A is preferably arranged in the
This
middle of the side of the cylinder & and opened and closed by a slide valve n.
slide valve is formed with a slot corresponding with the section of the exhaust
port A and is operated by an eccentric on the crank shaft which is set at a lead
angle of 60° to the crank. The eccentricity of this eccentric may be 141 of the
width of the slot of the slide valve, so that in a quarter revolution of the crank the
exhaust port is alternately opened and closed.
The following five positions of the slide valve n and the piston k, represented in
the diagram below the cylinder will illustrate the working of the arrangement the
concentric circles representing relatively the revolution of the crank and of the
eccentric.
1. The slide valve n will begin to open when the crank is still 15° and the piston 0.02
of its full stroke away from the dead point (see radii a m and d m), the steam will
therefore not be quite enclosed when not acting and cannot do any damage.
2. The exhaust port will be opened 0-3 already of its width when the piston begins
again to work at the dead point (radii 6 m and e m) whereby the difference of the
pressure between cylinder and condenser or the atmospheric air is nearly equalized.
3. The exhaust port will be fully opened when the piston has only travelled 0.07 of
of its full stroke (radii s m and r m).

page_text: 4. When the piston has travelled 0.37 of its full stroke the exhaust port will be
closed again (radii cm and f m) and the piston passing over the exhaust port will
compress the enclosed rest of the steam.
5. The slide valve n and the piston k will be in a similar position to that explained
in 1, when the crank has made half a revolution (radii t m and um) and the same
operation will be repeated during the second half of the revolution.
As the wide exhaust port which is only open for a short time forces the steam from
both sides of the cylinder to expand towards the middle, no rotary motion of the
steam can take place in the cylinder and no opportunity is therefore offered to
abstract heat from the inner surface of the cylinder including the cylinder cover and
the piston, especially as the heat radiating power of the sides of the cylinder is very
small because of its polished surface. Besides the steam jacket of the cylinder
compensates the small loss of heat during the expansion and keeps the cylinder sides
at a uniform temperature.
As therefore the rest of the steam which is still to be compressed does not find any
condensing surfaces it will fill the clearance as full pressure steam without loss,
and the power lost through the compressing is gained again through the following
expansion.
To prevent an excess of compression the cylinder can be provided at the ends
with safety valves which may consist merely of loose cones.
These valves may
however be dispensed with if the admission valves are adapted to yield under
excessive pressure.
Through this arrangement the two causes of wasting steam in the cylinder, the
condensation against the inner surfaces and the clearance are prevented without
making the engine more complicated.
It is evident that any other suitable valve or slide may be used instead of the herein
described slide valve and that an exhaust port may be arranged for each direction of
action instead of the herein described exhaust port which serves for both sides; this
refers also to single acting cylinders. If the exhaust port is not far enough away
from the cylinder cover the cooling of the latter and of the adjacent parts of the
cylinder walls is not prevented because the steam to be exhausted being in rotary
motion touches these parts. The exhaust port must be at least 15 per cent. of the
stroke of the piston away from the cylinder cover. Further the exhaust port must
not be opened until the piston is 15 per cent. of its stroke away from it to prevent
also a rotary motion of the steam against the piston.
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 :-
In steam engines working on the expansion system a suitable valve mechanism,
actuated by an eccentric or equivalent on the crank shaft, which does not open the
exhaust port of the cylinder situated at least 15 per cent. of the stroke of the piston
away from the cylinder cover, until the piston has passed the exhaust port for at
least 15 per cent. of its stroke for the purpose of preventing the parts touched by the
live steam from being cooled by the current of the exhaust steam.
Dated this 1st day of May 1888
W. P. THOMPSON & BOULT,
Agents.