Improvements in or relating to valves for Steam Engines.
Year: 1894

page_text: Date of Application, 7th May, 1894-Accepted, 12th Jan., 1895
Improvements in or relating to valves for Steam Engines.
A communication from KARL LAUSMANN, of Turjew (Dorpat), Russia,
Engineer.
I, ALFRED JULIUS BOULT, of 323 High Holborn in the County of Middlesex,
Chartered Patent Agent, 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 variable expansion gear for steam distribution with
equilibrated rotary slide or valve and it is so constructed that any desired distri-
bution with variable expansion may be obtained with only a single equilibrated
rotary slide or valve. Furthermore the new rotary slide may be so modified that
a single slide may be employed to effect the steam distribution for double cylinder
engines.
The new rotary slide consists of a hollow cylinder located in a cylindrical case,
and having double walls in its central portion its inner space being connected with
the steam admission while the outer space formed and enclosed by the double walls
is in constant communication with the exhaust outlets which is rendered possible by
the arrangement of the case in which the rotating slide moves having in its centre
an enlargement coinciding with an annular opening in the outer wall of the
central portion of the slide which has double walls, and running entirely round the
periphery thereof without any interruption other than at most a few ribs. Each
side of the working cylinder communicates through a channel (a tubular channel)
with the case of the rotating slide and the opening of the said channel in the said
case is divided by a web or small plate into two channels so that one of these
openings or ports during the revolution of the rotating slide communicates only
with the steam chest and the other only with the exhaust. This communication is
effected by providing openings in the walls of the rotating slide which during the
revolution of the slide are brought into coincidence with the case-passages.
The rotating slide revolves at the same speed as the crank-shaft; the dimensions
of the slide-passages are calculated and determined in accordance with the desired
steam distribution and they form, in so far as only regular expansion is to be
attained, rectangular ports. If the steam distribution with the same expansion is
intended to be utilised for the return-stroke then, besides the passages already
mentioned, other slide-passages are provided which, while in all respects similar to
the first-named, are separated therefrom by an angle of 180° on the periphery of
the rotating slide in relation to the direction of movement whereas in the longitudinal
direction of the axis of the rotating slide these additional passages are so far
removed from the former that they do not come into operation at all during the
forward stroke of the engine nor coincide with any of the case-passages; if the
engine is to be reversed the rotary slide is shifted or displaced in the direction of
its axis in such manner that during its revolution the first-named slide-passages
become inoperative, while the second are operative.
If the engine is to work with variable expansion the slide-passages for steam-
admission are made broader to correspond and at the same time in the form of a
trapezium in cross-section while the slide itself can be shifted or displaced in the
longitudinal direction of its axis either by hand or by means of the regulator. The
inclined edge of the trapezoidal slide-passages cuts off the steam-supply at a

page_text: placement.
U Tater Tu proportion to the extent of the said longitudinal dis-
The improved slide is illustrated in the accompanying drawings in which :-
Figure 1 is a plan of portion of a horizontal steam-engine.
Figure 2 represente in longitudinal section a slide for constant expansion (cut off
at 30% or a little less than a third).
Figure 3 is a development of the rotating slide represented in Figure 2 showing
in dotted lines the case-passages or ports.
Figure 4 is a cross-section of the slide and case on the line x x x of Figure 2.
Figure 5 is a cross-section on the line yyyyyy of Figure 2.
Figure 6 is a longitudinal section of an improved rotating slide, modified in
such manner as to serve for the simultaneous steam distribution of the high and
low pressure cylinders of a Woolf's steam engine with cranks opposed to each other
at an angle of 180°.
Figure 7 is a cross-section of Figure 6 on the line a.
Figure 8 is a cross-section of Figure 6 on the line y y y y y y.
In.
In the single-cylinder steam-distribution rotary slide-valve represented in
Figures 1 to 5 inclusive Z' (Figure 2) is the piston of the steam cylinder Z. The
rotary slide S is driven by the fly-wheel shaft h by means of the bevel-gear k
(Figure 1). From the interior of the cylinder Z the cylinder-passages C and C¹
lead, in the usual well-known manner from both sides of the piston to the rotary-
slide case G in such manner however that the former cylinder passage is divided
by a tightly fitting web or plate s into two case-passages A and B, or A' and B¹
(Figures 2 and 3). The former case-passages A, A¹ serve the purposes of steam-
admission the latter B B' for exhaust. To this end those parts of the rotary slide S
which cut off the live steam in the steam-chest D cover the case-passages A and A'
so that as the rotary slide revolves only steam can be admitted to the said
passages A and A' so far as the slide-passages a and a¹ coincide therewith.
like manner on the rotation of the valve the exhaust passages b and thereof
coincide with the case-passages B B. In the latter case the exhaust steam passes,
through the chamber F formed between the outer and inner walls of the slide and
thence through the valve ports e into the enlargement K of the slide-case and so.
escapes into the open air or into the condenser. Supposing for example that the
slide rotates in the direction shown by the arrows (Figures 3 and 4) when the.
piston Z is at the dead-point at the bottom or end of the cylinder, the cylinder-
passage C (Figure 2) is open and the live steam is admitted through A' into the
cylinder until the slide passage a' closes the passage A' at the predetermined cut-off
point (in this case 30%). At the opposite end the proper exhaust has already.
been established in connection with the slide-passage the waste steam escaping
through B into the chamber F of the valve and thence through the passage c and
the case-passage K into the open air. When the piston Z' reaches the opposite
(in the drawings the upper) end of the cylinder the slide has completed a half-
revolution as it rotates at the same speed as the crank-shaft and the live steam
which fills the passage D in the centre of the slide is admitted through the
slide-passage a into the case-passage A and cylinder passage C the exhaust steam
at the other end of the cylinder escaping through B' and c into the open air.
Figures 6 to 8 inclusive represent the slide so modified that it is adapted to effect.
the simultaneous steam-distribution to the high and low pressure cylinders of a
Woolf's steam engine. Here H is the high and N the low pressure cylinder.
The cylinder-passages in this case also have their connections divided in two.
parts by means of steam-tight partitions, the divided passages being as in the
preceding case indicated by A B, A' B'. Each case-passage has a corresponding
slide-passage, a b, a' b. The passages which serve as exhaust outlets for the
high pressure cylinder H discharge into a steam-chamber whence at the same
time the slide-passages a a¹ conduct to the low-pressure cylinder for which they
serve as admission inlets.
b
The slide-passages, band b¹ appertaining to the high pressure cylinder, and

page_text: a and a¹ appertaining to the low-pressure cylinder, which thus are connected with
the same steam-chamber R, are so situated opposite one another on the periphery
of the rotary slide, that one or the other pair say b and a' or ' and a is always
open at the same time and in communication. The chamber R thus serves as a
steam reservoir or chest.
If the cylinder-crauks were placed at right angles the passages must be arranged
in position correspondingly and the chamber R formed of such dimensions that
it may discharge the necessary functions of receiver for steam-engines of that
class.
For example, if the two cylinder-pistons are in the relative positions shown in
Figure 6, the case-passage A is open for the admission of live steam to the high
pressure cylinder H the steam finding its way through D and C into the high-
pressure cylinder until the slide-passage a cuts off the steam at the predetermined
point (in this case assumed to be 35%) and closes the admission inlet A.
At the other end of the high-pressure cylinder a properly corresponding exhaust
has been established by this time, the passage opened and the steam escapes
through the passage into the intermediate steam-chamber R of the slide
whence it is fed through the case-passage A and the cylinder-port C, into the
low-pressure cylinder N until this passage A is in its turn closed by the cut-off (in
this case 66%) to correspond.
Simultaneously at the opposite end of the slide, the exhaust-outlet B of the
low-pressure cylinder is opportunely opened, and the waste steam can escape through
the exhaust port C¹ and the case-passage B' into the exhaust chamber F and thence
through into the open air or into the condenser. When the pistons have made a
stroke, the rotary valve which is operated at the same speed as the crankshaft
has made a half revolution and the same series of working stages is repeated
throughout the return stroke, in relation to the other passages in the like manner.
It will be obvious that the most advantageous and favourable relations of steam
admission exhaust, compression and expansion, are attainable simply by the correct
arrangement of the slide-passages.
The passages and 'which open into the chamber F serve at one time to effect
the exhaust of the low-pressure cylinder N into the said chamber F, and at another
time to direct the exhaust from F into K these passages must therefore be so spaced
around the periphery of the slide that they effect the necessary compression in the
low-pressure cylinder.
The objects which hitherto have only been obtainable with Woolf's engine by
means of more than one distribution valve, and even then not without great loss of
steam-pressure, owing to condensation of the steam in passing from the high
to the low pressure cylinder, can now, through this invention be attained with the
single rotary slide or valve and without any such disadvantage as that mentioned
inasmuch as the steam passing from the high to the low pressure cylinder, has its
temperature raised by the live steam contained in the slide; and thus the slide acts
practically as if it were a superheated receiver.
Having now particularly described and ascertained the nature of the said
invention as communicated to me by my foreign correspondent and in what manner
the same is to be performed I declare that what I claim is :-
-;
1. A rotary distributing slide or valve such as S for steam-engines formed with
a central chamber or compartment having double walls which in combination with
the cylinder-passages or ports C and C" whereof each is subdivided into two
parts such as A A and B B effects the steam distribution while rotating by means
of its own passages a band a¹ in such manner that the passages a and a provided
in that portion of the slide where its walls are single only (i.e. at both of its ends)
overlap the parts A A' of the cylinder passages while the other passages b bl
provided in the central portion of the rotary valve where the walls are double overlap
the other parts B B of the cylinder passages substantially as describe and
illustrated in the accompanying drawings.

page_text: 2. The combination with a steam distribution slide such as described in Claim 1
modified for the distribution of steam to engines with more than one cylinder of
another chamber such as R wherein the slide-passages for the high and a a¹
for the low-pressure debouch as inlet and outlet respectively substantially as
described and illustrated in the accompanying drawings.
3. Steam distributing devices such as described in Claims 1 and 2 so far as a
variable expansion is thereby attained by the trapezoidal form given to the slide
passages for steam admission and by the rotary slide being made moveable in the
direction of its axis.
Dated this 7th day of May 1894.
W. P. THOMPSON & BOULT,
Of London, Liverpool, Manchester, and Nottingham,
Agents for the Applicant.