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Патент USA US2412478

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mg, m, 1946.
'
J, $1M
'
2,412,478
STEAM vAC'I‘UATED PILOT CONTROLLED DISTRIBUTION VALVE FOR STEAM‘ ENGINES
Filed Dec. 28, 1944
2,412,478
Patented Dec. 10, _ 1946
UNITED STATES PATENT Tor-"Flee ‘
STEAM ACTUATED PILOT CONTROLLED
DISTRIBUTION VALVE FOR STEAM EN
GINES
James Sim, Cathcart, Glasgow, Scotland, assign
or to G. & J. Weir, Limited, Glasgow, Scotland,
a corporation of Great Britain
Application December 28, 1944, Serial No. 570,183
In Great Britain January 8, 1944
2 Claims. (01. 121-157)
1
This invention applies to steam distributing
valves of the type in which a main shuttle valve
is reciprocated by steam pressure under the
control of an auxiliary mechanically actuated
valve sliding on the back of the main valve.
Examples of this type are represented in Figs.
1, 2, and 3 of the speci?cation of British Letters
Patent No. 3,723 of 1394 and in Figs. 1 to 9 of the
speci?cation of British Letters Patent No. 1,023
of 1881, and in a modernized form in the speci
?cation of United States Letters Patent No.
2,093,963.
With the present day increase in boiler pres
sures and the high superheat temperatures now
being used, difficulties, particularly excessive
.
2
a
.
chined back'face. The valve spindle g passes
through the centre of the auxiliary valve. The
spindle, where it passes through the auxiliary
valve, is square in section and is a ?t on the
sides with clearance front and back so that the
auxiliary valve can bed down on the shuttle valve
back face but cannot, at the same time, be moved
sideways by the shuttle valve when the latter is
in motion. Two holes a‘ are drilled through the
auxiliary valve 1‘ to provide relief for steam leak
age at the back of the auxiliary valve 1‘. A ?oat
ing ring it is arranged on the back of and slides
on the valve 1‘ and bounds a space I which is
brought under exhaust pressure by connection to
the exhaust system of the auxiliary valve and
shuttle valve through the holes it The space I
wear, are experienced with steam slide valves of
is closed by the cover 112. The ring 7c is an easy
the type described in the speci?cations of the
sliding ?t in the body of the casing 11. Grooves n
said British Letters Patent. These difficulties
are provided to allow high pressure steam to act
are aggravated by the modern demand that the
exhaust from auxiliary engines should be oil 20 on the top of the ring is and press the ring
against the back of the auxiliary valve and thus
free. These requirements demand a steam slide
valve which will operate satisfactorily with high
steam pressure and superheat, without lubricat
ing oil, and without being subject to excessive
wear on the sliding surfaces.
The present invention consists of an arrange
ment of parts, particularly applicable to the
construction described in the speci?cation of the
aforementioned British Patent No. 3,723 of 1894.,
prevent high pressure steam leaking into the
space Z between the ring and the back of the
auxiliary valve 1‘.
The intensity of pressure between the ring R:
and the back of the auxiliary valve 1‘ may be re
duced to a satisfactory amount by the construc
tion shown in Fig. 3.
In Fig. 3 an internal ?angego is shown as
formed solid with the ring is. A recess p is formed
in the face of the ?ange o, and holes (1 are drilled
through from the bottom of the recess p.' This
operation is obtained at the highest pressures
construction increases the sliding area of the ring
and degrees of superheat without the need for
it in contact with the back of the auxiliary valve
internal lubrication.
Figs. 1, 2, 3, 4 and 5 are sectional views illus 35 1‘ without causing any increase in total loading
from the high pressure steam pressing on the
trating the invention as applied to the construc
ring is. The intensity of sliding pressure can
tion according to the aforementioned British
therefore be controlled to any desired amount
Patent No. 3,723 of 1894.
by the selection of suitable proportions.
In Figs. 1 and 2 a is the valve chest casing
Leakage of steam into the space Z at the outer
with inlet port 8 and exhaust port 9, b and c the 40
end or the end remote from the auxiliary valve
steam ports to the top and bottom of the steam
may be prevented by means known per se, such
cylinder driving the pump, d is the main steam
as shown in Figs. 3, 4 and 5.
valve or shuttle valve having steam ports I)’, c’
In Fig. 3 a ?exible metallic plate or disc 1‘ is
and an exhaust port a, e are bells or small cylin
ders which embrace the ends of the shuttle Valve, 45 shownjointed to the cover an. The high pressure
steam admitted by the grooves 11, presses the
and provide operating cylinders for the reciproé
plate 1 against the outer edge of the ring is and
cation of the shuttle valve. 1‘ is the auxiliary
prevents the leakage of steam into the space 1.
valve which slides on the back face of the shuttle
In Fig. 4 a packed stuf?ng box or gland s is
valve d. The valve J‘ is operated by the valve
spindle g driven in usual manner from the valve 50 shown incorporated in the cover m to prevent
the leakage of steam into the space Z.
gear levers of the pump. The ‘valve 1‘ is a sliding
In Fig. 5 normal type piston rings t are shown,
?t between the collar h and nuts 1‘ on the valve
housed in the cover m and adapted to ?t within
spindle g to ensure that the valve 1‘ will bed down
the ring lc to prevent the leakage of steam into
on the back face of the shuttle valve (1.
\
The auxiliary valve 1‘ is provided with a ma 65 the space I.
and so disposed as to reduce the loading on the
sliding surfaces to such a value that satisfactory
2,412,478
3
4
The sliding faces of the shuttle valve 11 and
the auxiliary valve f can be entirely relieved of
loading by equalising the cross-sectional areas
What is claimed is:
1. In a steam distribution valve of the type
referred to, the combination with a valve casing
of the exhaust cavity u of the shuttle valve, of
having a steam port and an exhaust port, of a
the exhaust cavity 0 of the auxiliary valve 1‘
shuttle Valve operative in said casing and pro
and of the cavity Z which is under exhaust pres
vided with steam inlet and exhaust ports and
sure because of its connection with the cavity
an exhaust cavity, an auxiliary valve slideable
11. by way of the holes 7'. The loading of these
on the back face of said shuttle valve, leaving
‘faces would be entirely relieved if the ring it
an exhaust space between the back of said shut
were solid with the body of the chest a, but this 10 tle valve and said casing, said auxiliary valve
would not be a good practical construction due
being provided with holes adapted to communi
to the precision necessary in manufacture; but
cate with said exhaust cavity, a cover for said
by making the ring is separate and an easy ?t
exhaust space, and a ?oating ring bounding said
in the chest a there is obtained a loading of the
exhaust space laterally, one end of said ring
sliding faces which depends on the thickness 15 bearing on the back face of said auxiliary valve,
chosen for the ring is and is thus controllable.
said ring being in engaging relation with said
A certain loading is desirable and is that just
cover, the effective cross-sectional area bounded
necessary to hold the faces in contact.
by said ring being approximately equal to the
It will be understood that the whole of the
exhaust port area of said shuttle valve.
interior of the chest is under high steam pres 20
2. The combination claimed in claim 1 includ
sure so that unbalance is caused solely by ex
ing means to prevent steam leakage into the
haust ports or cavities which are under exhaust
exhaust space bounded by the ring.
pressure.
JAMES SIM.
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