| 摘要 |
PROBLEM TO BE SOLVED: To provide a butterfly valve causing no fluid leakage from the periphery of a valve shaft even if high pressure fluid is flowed, the butterfly valve being constructed with a seat ring, exposing the outer peripheral surface of an annular core and having both sides and the inner peripheral surface coated with an elastic material, provided inside the valve body. SOLUTION: The core used is wider than a contact surface, considered as a reference, between a valve element and the seat ring which are normally in contact with each other around a valve shaft inserting hole. The contact surface is formed into a spherical surface with its radius being the radius of the valve element and its center being the center of the valve element. A swelled and protruded part extending annularly around the valve shaft inserting hole is provided in the contact surface on the seat ring side, having the top of the swelled and protruded part brought into pressure contact with the outer peripheral surface of the valve element. COPYRIGHT: (C)2004,JPO&NCIPI
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