More Especially Applicable for Operating Corliss Valves.
Year: 1888

page_text: More Especially Applicable for Operating Corliss Valves.
A communication from abroad by RUDOLF DÖRFEL, I.R. Professor of the Technical
High School, of Prague, Bohemia, Empire of Austria.
I, WILLIAM PHILLIPS THOMPSON F.C.S. M.I.M.E. of the Agency for Foreign
Patent Solicitors, 6 Lord Street, Liverpool, and 6 Bank Street, Manchester, both in
the County of Lancaster, and 323 High Holborn, in the County of Middlesex, 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:-
The invention relates essentially to a peculiar arrangement of the valve gear for
operating and regulating induction valves of the Corliss type, the requisite movement
being obtained by the combination of two eccentric motions, as hereinafter described
and shown in the accompanying drawings.
In the drawing :-
Figures 1 and 3 show side views of two alternative arrangements of the new valve
gear, as applied to a steam cylinder.
Figures 2 and 4 show details of construction.
Figure 5 is a modified form of yalve rod engaging mechanism.
A, Figure 1, is the operating disc, such as is found in the ordinary Corliss gear. It
oscillates about the pin B, and is connected at C with the rod of the main distribution
eccentric. The disc A is provided at D with a pin supporting the horizontal arm of a
T-lever. The lower end E of the vertical arm of the said T-lever is connected with
the rod of the expansion eccentric, while the extremities F and G of the horizontal
arm actuate the gear of the induction valves. Owing to the combined movement of
the main and expansion eccentrics, the extremities F and G of the T-lever describe
curves such as are shown on the drawing, each having a part flattened inwards.
The rod arrangement connecting the pins For G with the end H of the rocking
arm that is keyed on the outer end of the induction valve spindle J, receives, con-
sequently, a peculiar transversal movement combined with the longitudinal movement
which opens the valve. Both these movements are employed for alternately effecting
го

page_text: the engagement and disengagement of any suitable spring or other releasing
mechanism arranged within or upon the connecting rod F, H. With this mechanism
it is possible to effect the above disengagement with the greatest accuracy at any
moment during the "induction" period.
In Figures 1 and 2 there is represented the releasing mechanism of the older typ
of Spencer Inglis valve gear, but with the disengaging cam or toe lever K applied in
a reversed position. If the path described by the toe lever K (which is represented
by dotted lines in the Figure), be examined, it will be found that during the com-
mencement of the opening movement of the valve, the movement of the toe lever K
is effected by the longitudinal (or opening) movement of the valve rod F, H, whilst
during the time the valve is being fully opened, the said toe lever is caused to move
in a transverse path by reason of the aforesaid transverse movement, which takes
place in an upward direction.
As soon as the toe lever K reaches a position in which the toes lie more or less
transversely to the valve rod, the spring clips of the latter are disengaged thereby,
and the induction valve is quickly closed by the action of a spring or springs, or by a
weight or a vacuum dash pot.
For the purpose of regulating the cut-off, the extremity L of the toe lever arm is
connected with the lever and pull rod of the regulator or governor, in such a manner
that the point L, when the governor rises, occupies its lower positions, which result in
shortened periods of steam admission, but as the speed of the governor decreases, the
said point rises higher and higher, and thereby increases the period during which
steam is admitted. The axis of rotation of the toe lever can be fitted either upon the
passive (that is the snapping) part of the gear, as in the Spencer Inglis gear (Figures 1
and 2), or upon the valve rod G, H, connected with the active parts of the gear, as
shown in Figures 3 and 4, which represent a modification of the gear shown in
Figures 1 and 2,
Figure 3 represents a modification in the construction of the T-lever E, F, G.
In this case the pin D of the disc of the ordinary Corliss valve gear is enlarged so as
to take the form of an eccentric sheave, oscillating about the pin B. The T-lever is
replaced by a strap surrounding this eccentric, and carrying the aforesaid pins F and G,
which are connected with the ends of the valve rods, and the pin E which is con-
nected with the end of the rod of the expansion eccentric. The rod of the main
distribution eccentric is connected with the pin C of the eccentric A.
By giving a proper amount of throw and angular advance to the main eccentric,
and to the expansion eccentric, the points G and H may be made to describe the same
curves as the corresponding points in the preceding case, and they may thus be
utilised in a similar manner. In both cases the re-engagement of the releasing
mechanism and valve rod takes place while the point F is travelling that portion of
the curve which is flattened inwards, the steepness of the curve at that part assisting
the said re-engagement.
The eduction valves are in both cases actuated by rods connected with pins M
and N, which are suitably arranged on the disc A (Figure 1), or on the eccentric A
in the modification shown in Figure 3.
Instead of the Spencer Inglis valve rod engaging mechanism, the spring catch rod
represented in Figure 5 may be used.
Having now particularly described and ascertained the nature of the said
invention, and in what manner the same is to be performed, as communicated to
me by my foreign correspondent, I declare that what I claim is :-
1. In a Corliss valve gear, the combination with a main eccentric gear and an
expansion eccentric gear of a T-lever such as E, F, G, pivotted on the ordinary
Corliss disc (or its equivalent) and connected on the one hand with the said expansion
gear, and on the other with the valve rod, whereby a combined longitudinal and
transversal movement of the valve rod is obtained, of such a nature that the release
of a spring catch arrangement in or upon the valve rod is rendered possible at any
moment of the induction period, substantially as described.

page_text: 2. The improved Corliss valve gear, consisting of a Corliss disc A (or its equivalent)
actuated by the main eccentric, and provided with a pin D, a T-lever (E, F, G,)
mounted on said pin and actuated by the expansion eccentric and valve rods (F, H, G, H)
each provided with a releasing mechanism, and each connected at one end with one
horizontal arm of the T-lever, and at the other end with the induction valve lever,
substantially as and for the purpose set forth.
3. The modified arrangement of Corliss valve gear having an oscillating eccentric
disc actuated by the main eccentric, and an eccentric strap (E, F, G) surrounding
said eccentric, both combined with the valve rods (F, H, G, H,) in a similar manner
to T-lever, herein set forth, and replacing the said T-lever, substantially as described
and shown in Figures 3 and 4.
4. In combination with either of the arrangements of Corliss valve gear such as
herein described, the reversed releasing mechanism of the Spencer Inglis type,
substantially as set forth.
WM. P. THOMPSON & Co.,
Of 6, Lord Street, Liverpool,
Agents for the Applicant.