Improvements in Valve-gear for Engines.
Year: 1890

page_text: Date of Application, 9th Apr., 1890
Complete Specification Left, 23rd Dec., 1890-Accepted, 24th Jan., 1.891
PROVISIONAL SPECIFICATION.
Improvements in Valve-gear for Engines.
I, LUDWIG CZISCHEK, of Hasengasse, Vienna. Austria, Imperial and Royal Professor,
do hereby declare the nature of this invention to be as follows:-
This invention has reference to valve gear for engines and its chief characteristic
feature is the employment of two excentrics, one being mounted upon the other,
or of a loose excentric mounted upon an excentric gudgeon or crank pin. By
this arrangement an exact distribution is ensured in steam engines and other
similar motors in such manner that the outer of the two excentrics on the weigh
shaft of a link (on the loose excentric mounted upon the excentric gudgeon of the
said weigh shaft one end of which link is adjustable by the governor, is compelled
during a revolution of the engine to move relatively to the inner excentric which
is keyed upon the weigh shaft or relatively to the excentric gudgeon so that the centre
of the loose excentric describes ellipse-like curves whose more or less inclined
positions correspond to the various points of cut-off in the cylinder. By the
relative displacement of the aforementioned link with reference to the valve rod,
an engine provided with such valve gearing may be arranged for working in the
opposite direction.
The distributing valve motion substantially as herein described may be modified so
as to admit of its application to valve, cock or slide valve systems, as will be readily
understood.
In carrying out the invention according to one modification there is keyed on
the weigh shaft an excentric which has mounted on it a second loose excentric.
This excentric has mounted on it links which are jointed to one end of a lever
whose other end is keyed to a shaft which can be turned from the governor. For
this purpose another lever which is also keyed on this shaft is connected by links
to the sleeve of the governor. It will be easily understood that when the centre
of the loose excentric describes ellipse-like curves by reason of the action of the
inner excentric and of the attached links the varying position of the curves or
displacement of the excentric which is dependent upon the governor through the
intermediation of the links, will control the cut-off. By this means the amount of
cut-off can be controlled or regulated within prescribed limits.
The regulation of the exhaust valve may be effected by a separate excentric or
directly from a suitably chosen point on the excentric strap. The levers of this valve
rest against hanging supports when the valves are opened and these supports when at
rest bear against adjustable stops by their own weight assisted by weak springs.
Another modification differs from that already described only in that the inner
excentric is replaced by an excentric gudgeon or crank pin. The motion of the
weigh shaft can be obtained indirectly by means of suitable wheel gearing.
For causing the engine to work in the opposite direction (reversing) the shaft
which is connected by a lever to the links as above described must be moved round
the weigh shaft so that the links come on the other side of the valve rod.
this Oth dor of Anil 1800

page_text: COMPLETE SPECIFICATION.
Improvements in Valve-gear for Engines.
I, LUDWIG CZISCHEк, of Hasengasse, Vienna, Austria, Imperial and Royal Professor,
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 has reference to valve gear for engines and its chief characteristic
feature is the employment of two excentrics, one being mounted upon the other, or of
a loose excentric mounted upon an excentric gudgeon or crank pin. By this arrange-
ment an exact distribution is ensured in steam engines and other similar motors in
such manner that the outer of the two excentrics on the weigh shaft of a link (or the
loose excentric mounted upon the excentric gudgeon of the said weigh shaft) one end
of which link is adjustable by the governor, is compelled during a revolution of the
engine to move relatively to the inner excentric which is keyed upon the weigh shaft
or relatively to the excentric gudgeon so that the centre of the loose excentric
describes ellipse-like curves the more or less inclined positions of which correspond to
the various volumes of steam admitted to the cylinder. By the relative displacement
of the aforementioned links with reference to the valve rod, an engine provided with
such valve gearing may be arranged for working in the opposite direction.
The distributing valve motion substantially as herein described may be mo lified so
as to admit of its application to valve cock or slide valve systems, as will be readily
understood.
In the drawings annexed to this Specification
Figure 1 represents the arrangement of improved valve gear with two excentrics
mounted one upon the other.
Figure 2 shows the modified arrangement of the improved valve gear in which the
inner excentric is dispensed with and for it an excentric gudgeon or crank pin is
substituted.
Figures 3 and 4 represent, on an enlarged scale, cross sections of the arrangements
shown in Figures 1 and 2 respectively.
As will be seen from the drawings, upon the weigh shaft a (Figure 1) is keyed an
excentric, upon which a second loose excentric c is mounted. To this loose
excentric care pivoted on opposite sides and at suitable points the links d jointed by
means of the bolt or pin e to one end of a lever, the other end of which is keyed
upon a shaft which can he turned by the governor. For this purpose upon this
shaft there is keyed another lever h, connected by means of the straps or links k to
the sleeve of the governor.
It will be readily seen that the centre of the loose excentric will describe a
somewhat elliptic curve under the combined influences of the excentric b, on the one
hand, and the links d on the other hand, the position of which elliptic curve relatively
to the axial line of the valve rod will vary according as this loose excentric c is more
or less displaced upon the excentric by the governor and through the gear described.
By this means the volume of steam admitted to the cylinder can be varied within
sufficient limits between 0 and the maximum.
The regulation of the exhaust valve may be effected by a separate excentric or
directly from a suitably chosen point m on the excentric strap. The levers n and n¹
of the valve rest against pendulous supports o o' when the valves are opened, and
these supports when at rest bear against adjustable stops p¹ by their own weight
assisted by weak springs.
The modification shown in Figure 2 differs from that already described and shown
in Figure 1 only in that the inner excentric is replaced by an excentric gudgeon or
crank pin 6 mounted on the weigh shaft. The motion of the weigh shaft in this case
can be obtained indirectly by means of suitable wheel gearing.
For reversing the motion of the engine the shaft g which is connected by a lever to
the links d as above described must be thrown over the weigh shaft a so that the

page_text: links d will lie on the opposite side of the valve rod, as shown in dotted lines in
Figure 2.
The following may be mentioned as the chief advantages of the improved valve
gear above described. The great simplicity of the arrangement in which the number
of joints is minimized; the increase of the efficiency and precision and the quick
starting of the notion of the valves; the relatively long maintenance of the valves in
their open position and rapid closing of the same; the facility of the regulation and
reversil &c.
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
www
1. In valve gear, two excentrics one of which encloses the other and can be
displaced by the governor by means of the links (d), whereby the position of the
ellipse-like curves described by the centre of the loose excentric is displaced and
accordingly the steam admission to the cylinder can be varied, substantially as
described and shown.
2. The modified arrangement of the valve gear specified in the foregoing claim in
which the inner excentric (6) keyed upon the weigh shaft (a) is dispensed with and
is replaced by an excentric gudgeon or crank pin (6) substantially as described and
shown.
3. Arranging the valve gear specified in claims 1 and 2 for reversal of the engine
motion, by enabling the shaft g to be moved by hand round the weigh shaft a so that
the links will be placed on the opposite side of the valve-rod, substantially as
described and shown."
4. In valve gear, the arrangement of pendulous supports o o¹ for the valve levers,
the said supports being arranged so as to bear against adjustable abutments p' under
the influence of their own weight, assisted by the action of weak springs p, sub-
stantially as described and shown and for the purpose specified.
Dated this 22nd
+000
J. C. MEWBURN,
55 & 56, Chancery Lane, London, Patent Agent.