| 摘要 |
A funnel-shaped cover 10 of a sheet material is placed around the upper side of the valve disc 2 and an adjacent portion of the valve stem 1 at a distance from the surface 8 of the valve and fluid-tightly connected to the disc and the stem at its respective ends. In the interspace between the surface of the valve and the cover, a funnel-shaped screen 13 is at the top fluid- tightly connected to the valve stem while the lower end of the screen ends at a distance from the bottom of the interspace which is thereby being divided in an outward and an inward cooling medium passage 16, 17 which are connected in series via a circumferential passage 15 near the seating face of the valve disc. Channels 19, 20 in the valve stem above the screen and the cover serve as inlet and outlet of cooling medium to and from the passages 15-17, respectively. An efficient cooling of the valve is obtained, in particular of the area with its seating face, and the cooling medium passages are produced by simple machining operations which do not entail any weakening of the mechanical strength of the valve. <IMAGE>
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