Improvements in Equilibrium Slide Valves for Engines.
Year: 1899

page_text: Date of Application, 11th Nov.. 1899
Complete Specification Left, 9th Aug., 1900-Accepted, 22nd Sept.,
1900
PROVISIONAL SPECIFICATION.
Improvements in Equilibrium Slide Valves for Engines.
I, WILHELM SCHMOLKA, of Pola, in the Empire of Austria-Hungary, Marine
Engineor, do hereby declare the nature of this invention to be as follows:-—
This invention relates to improvements in equilibrium slide valves, and has
reference to an arrangement for balancing plane slide-valves in largo engines,
but more especially those used in connection with marine-engines.
The arrangement for balancing the valve is characterized by the fact that
the steam-admission is effected from underneath, or from within the valve, while
the exhaust is disposed without the valve; said valve being pressed against the
cylinder face or seating by suitable pistons.
In consequence of this arrangement, the effect resulting from the steam-
pressures is not to force the valve against the cylinder face but to lift, and this
ouly to a small extent, which is balanced by the pressure of the pistons upon the
upper side of the valve.
As hereinbefore mentioned, the steam admission takes place from within the
valve and the exhaust from without the same; one port acting as an admission
port, while the valve-chest communicates with the exhaust, or with the con-
denser, or other suitable outlet.
The constructional modifications resulting from the reversing of the ordinary
arrangements with regard to the valve, consist merely in adapting the admission
and exhaust ports to the same reversed order and causing the external lap of the
steam-ports to take the place of the internal lap, and vice-versa.
With the object of preventing the high-pressure steam within the valve from
lifting the latter off the cylinder face, a number of suitable pistons are provided
formed with guides fitting into stuffing boxes in the upper portion of closed
cylinders, which latter are fixed in apertures of the valve-chest cover and adapted
to be supplied with pressure by means of water, air, steam or the like through
suitable pipes.
The pistons are hollow and are formed with internal ribs and rectangular base
plates strengthened by ribs and arranged externally of their cylinders; such
base-plates being arranged more in suitable guides.
The base-plates, as also the upper surface of the slide-valve, are formed with
friction surfaces provided with lubricating grooves.
The pressure upon the pistons, is so regulated as to balance the internal
steam pressure of the valve, and press the lutter upon the cylinder face with a
suitable amount of force.
The effects resulting from the improved arrangement as compared with ordinary
arrangements will be clear from the following comparison.
In designating the specific pressure of admission by p; the specific pressuro
in the receiver or condenser by p' the face of the valve upon the cylinder face
by F, the sum of the superficial area of the ports below the valve as; the sum
of the superficial area of the ports of the valve as fl; the ordinary arrangement

page_text: in which the admission, and the exhaust ports would give a pressure upon the
slide valve equal to the difference between external and internal pressure, or
P
=
p (F) p¹ƒ:
-
This pressure is but slightly reduced by any of the devices hitherto em-
ployed, and it is so great as to render the employment of plane-slide-valves for
large high pressure engines quite impossible.
The upward pressure P₁ in connection with the improved arrangement with
reversed admission and exhaust ports, is equal to the difference between the
internal and external pressure, thus
P pf p' (F — f¹)
=
-
As the value F-f is much greater than that off, it follows that the value
of P is much less than that of P, and from calculation it has been found that
the value of P is about % to 1% of P, showing that in large multiple-expansion
engines the pressure on the valve, which is a constant danger, is from ¼ to ½
of its former amount.
The upwardly directed pressure of the steam in the interior of the valve is
balanced by the pistons herein before described, and the pressure exerted by
these latter upon the valve, exceed the internal steam pressure by about 5 to 10
per cont.
Dated this 11th day of November 1800
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C.,
Agents for the Applicant.
Парготещение ш сушногти опие VHIVES 1orges.
I, WILHELM SCHMOLKA, of Pola, in the Empire of Austria-Hungary, Marine
Engineer, do hereby declare the nature of this invention and in what mauner the
samo is to be performed, to be particularly described and ascertained in and by
the following statement:-
This invention relates to improvements in equilibrium slide valves and has
for its object to provide an arrangement for balancing plane slide-valves in large
engines, but more especially those used in connection with marine-engines.
The arrangement for balancing the valve is characterized by the fact that
the steam-admission is effected from underneath, or from within the valve, while
the exhaust is disposed without the valve; said valve being pressed against the
cylinder face or seating by suitable pistons.
In consequence of this arrangement the effect resulting from the steam-
pressures is not to force the valve against the cylinder face but to lift and this
only to a small extent, which is balanced by the pressure of the pistons upon the
upper side of the valve.
The invention will be readily understood by reference to the accompanying
drawings, which illustrates a slide valve of the well known "Pann" type con-
structed according to my invention.
Figure 1 is a vertical longitudinal section through the valve-chest of a Pann's
slide-valve.
Figure 2 is a plan, partly in section, of the cover of the valve chest, and
Figure 3 is a cross-section taken on the line A B of Figure 2.

page_text: As hercin before mentioned, the steam-admission takes place from within the
valve a and the exhaust from without the same; one port c acts as an admission
port, while the valve-chest b communicates with the exhaust f, or with the con-
denser, or other suitable outlet d.
The constructional modifications resulting from the reversing of the ordinary
arrangements with regard to the valve a consist merely in adapting the admission
and exhaust ports to the same reversed order, and causing the external lap of
the steam-ports to take the place of the internal lap, and vice-versa.
With the object of preventing the high-pressure steam within the valve from
lifting the latter off the cylinder face a number of suitable pistons are pro-
vided adapted to fit into stuffing boxes i in the upper portion of closed cylinders &
which latter are fixed in apertures of the valve-chest cover and adapted to be
supplied with pressure by means of water, air, steam or the like through suit-
able pipes t.
T
The pistons are hollow and are formed with internal ribs and rectangular base
plates strengthened by ribs m and arranged externally of the cylinders; such
base-plates being adapted to move in suitable guides n.
The base-plates r, as also the upper surface of the slide-valve, are formed with
friction surfaces provided with lubricating grooves.
The pressure upon the pistons is so regulated as to balance the internal steam
pressure of the valve, and press the latter upon the cylinder face with a suitable
amount of force.
The effects resulting from the improved arrangement as compared with ordinary
arrangements will be clear from the following comparison.
In designating the specific pressure of admission by p the specific pressure in
the receiver or condenser by p¹ the face of the valve upon the cylinder face by F
the sum of the superficial area of the ports vr below the valve as f; the sum
of the superficial area of the ports to of the valve as fl; the ordinary arrangement
in which to to are the admission, and eve the exhaust ports, would give a pressure
upon the slide valve equal to the difference between external and internal pressure

page_text: .
position to ordinary slide-valves, and means for keeping the valve upon its mirror,
substantially as hereinbefore described.
2. In combination with a slide-valve as claimed in Claim 1, a series of weighted
or pressure-pistons working within cylinders and operated by separate motive
fluid in such a manner as to force the slide-valve upon its mirror with a pressure
alightly exceeding that of the internal steam pressure, substantially as herein-
before described with reference to the accompanying drawing.
Dated this 9th day of August 1900
HASELTINE, LAKE & Co.,
45, Southampton Buildings, Loudon, W.C.,
Agents for the Applicant.