US 1870293 A
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Aug. 9, 1932. H MILLER STEAM VALVE Filed Sept. 30, 1929 Patented Aug. 9, 1932' UNITED STATES PATENT. OFFICE HANS MILLER, OF BERLIN-LICH'I'ERI ELDE, GERMANY, ASSIGNOR; T SIEMENS- SCHUGKEBTWERKE AKTIENGESELLSCHAFT, OF BERLIN -SIEMENSSTADT, GERMANY,
A OOBIORATION OF GERMANY Slim VALVE Application filed September 30, 1929, Serial No. 396,181; and in Germany October 2, 1928.
My invention relates to steam valves, and more particularly to steam valves which may be loaded on either side and in which the stop or closing member is balanced in whichever direction the steam flows. Such valves are, for instance, used in plants for cutting off individual steam boilers from a common steam main to which are connected a plurality of steam boilers. If such valves are computed according to the principles applied to low pressures, dimensions for the diameterof the valve stem would result with the materials at present available which would about correspond with the diameter of the stop member itself. The problem facing the designer is thus to relieve the valve stem of the pressure actin upon it.
. The plug of the va ve according to my .in-
vention is so designed that when the valve is closed the plug permits the passage of a small quantity ofsteam for the purpose of increasing the, closing pressure or facilitating the opening movement. This may, for "instance, be attained by providing the plug with bores or passages through whichca communication-is established between the spaces above and below the plug. This communication is preferably interrupted by an auxiliary valve with a spherical contact surface which is forced down on its seat by a spring.
The plug is provided with two seating faces,
one being formed on the plug body and the other on an elastic plate or disk rigidly connected with the plug. .If a high pressure acts on this elastic disk from underneath, this disk is able to rise sli htly off its seat and to pirmit the passage o the steam. a
embodiment of my invention is illustrated in longitudinal section in the drawing affixed to my specification.
In this drawing, 1 is a valve chest through which the steam flows by way of a duct portion 2 to the duct portion 3, or vice verse from the duct 3 to the duct 2. The fiow of seated plug which is forced down on its seat by means of the valve stem 5. Assuming that the normal steam flow is from the duct 2 to the duct 3, and that the valveis closed,
so a high pressure acts on the underside ofsteam is controlled by means of a doublevalve plug 4 which pressure is transmitted to the valve stem 5. To ensure tightness of the valve in spite of the high pressure to which it is exposed the valve stem would have to have a large diameter in order to give it the necessary mechanical strength to permit the exertion and maintenance of a sufficiently high closing or sealing pressure. The object of my invention is to make the valve stem of small diameter and to let the steam itself on the higher pressure side supply the major portion of the closing pressure. For this purpose valveplug 4 is provided with the bores 6 and 7 which put the space underneath plug 4 in communication with the space 8 above the plug. This communication is controlled by an auxiliary valve 9 which has a spherical seating surfacefand is forced downupon its stationar'yseat within the plug 4 b means of a spring 10. 4 If the pressure un erneath plug 4 is very' much greater than on the other side, auxiliary valve 9 is slightly forced off its seat and a small quantity of steam passes into chamber 8 through the bores 6 and 7 until the same pressure is set up in chamber 8 which prevails in duct 2. As soon as this state of balance has been attained lug 4 is relieved of its load from below, and only a relatively small force need be exerted-through valve spindle 5 to provide the necessary closing pressure to keep the valve tight. When the valve is opened with-the assumed flow direction from 2 to 3, the spindle on being raised lessens first the pressure upon spring 10 and then lifts valve 9 and thereby establishes a free communication between the underside of plug 4 and chamber 8, so that now the spindle only has to transmit the power necessary to overcome frictional resistances in lifting plug 4 when spindle collar 12 abuts against c'ap nut 14 on further raising of the spindle.
If .the steam flows in the opposite direction, from the duct 3 to the duct 2, a small quantity of steam can pass through passages 16. between the plugand its guide sleeve 15 into the chamber 8 because the upper seat of plug 4 consists of a resilient plate 11 which yields as long as he pressure below the plate in clearances 16 is greater than above it. As soon as the same pressure has been set up in the chamber 8 as in duct3, the plug is exposed at the top to the high pressure existing in duct 3,which assists materially the closing pressure exerted by spindle 5. If it is desired to open the valve, spindle 5 upon being raised, raises first the spherical valve 9 until the collar 12 comes in contact with the lower face 13 of the cap nut 14 in Y which valve spindle 5 is j ournalled. In this way communication is set up first between chamber 8 and duct 2, and the steam in chamber 8 escapes into duct 2 and thereby unloads the top of the valve and lessens the resistspindle for operating said plug, of a pressure chamber above said plug, two auxiliary ducts provided in said plug for connecting the two portions of the main duct to said pressure chamber, and yielding means for each auxiliary duct for closing it when the plug has closed the main duct, but adapted to yield to the higher of the two fluid pressures prevailing at the two ends of said main duct to permit fluid of higher pressure to enter said chamber, whereby any fluid pressure tending to lift the plug from its seat is substantially neutralized, said yielding means being tensioned by said valve spindle.
2. In a balanced valve for a two-way fluid passage the combination with a valve casing, a main fluid duct through said casing and a valve plug disposed intermediate the ends of said duct to control said duct, and a valve spindle for operating said plug, of a pressure chamber above said plug, an auxiliary duct connecting the underside of said plug and one end of the main duct with said pressure chamber, and a secondauxiliary duct connecting the other end of the main duct with said pressure chamber, a spring-controlled valve ',within said plug for closing the first auxiliary duct against fluid entry from the underside of the plug, and a spring disk on said plug closing the other auxiliary duct against fluid entry from the other end of the main duct, the spring of said valve and said spring dis being tensioned by the valve spindle whe the plug is seated, each of said two yielding elements yielding when the higher of the two fluid pressures, prevailing at the two main duct ends, is exerted against it, so that fluid of the higher pressure is permitted to enter said pressure chamber,