| 摘要 |
PROBLEM TO BE SOLVED: To provide a valve element structure and a cavitation preventer structure for a butterfly valve for suppressing the occurrence of cavitation. SOLUTION: This control valve comprises an approximately cylindrical valve body 2, and a valve element 3 arranged in the valve body 2 for opening/closing a flow path, wherein a valve seat 205 on which the valve element 3 is seated is located eccentric to the center of a valve rod 5 in the flowing direction of fluid and the center of the valve rod 5 is located at a double eccentric position eccentric to the direction perpendicular to the flow-down direction of the fluid and to the downstream side in the flow-down direction of the fluid. Around a nozzle-side edge portion 309 on the upstream-side face of the valve element 3, an upstream-nozzle-side raised portion 310 is formed which is raised toward the upstream side into a relatively large hill shape. The downstream-side face of the valve element is inclined around the valve rod 5 at 5-20°clockwise to a seal face where the valve seat 205 abuts on a valve element valve seat 302. An orifice-side edge portion of the valve element 3 is swollen outward in the radial direction, relative to the nozzle-side edge portion. COPYRIGHT: (C)2009,JPO&INPIT
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