| 摘要 |
PROBLEM TO BE SOLVED: To provide a valve capable of completely restraining generation of cavitation by simplifying its structure and facilitating its manufacture. SOLUTION: In a butterfly valve, for example, having a valve casing 1, a valve element 2, and a valve stem 3, with the valve element 2 stored in the valve casing 1 rotatably around the valve stem 3, together with the valve stem, the surface of the valve body 2 and the internal surface of the valve casing 1 are formed with a number of protrusions 5 to separate flows (fluid), to restrain the growth of eddies generated on the downstream side of a flow reducing portion 4 for reducing a flowing cross-section. Thus, the back pressure of the valve element 2 is relieved, that is, by minimizing a back pressure, cavitation can be positively restrained. COPYRIGHT: (C)2004,JPO
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