| 摘要 |
PROBLEM TO BE SOLVED: To provide a ball valve simple in structure, which prevents uneven wear of a seal surface with time, and secures the sealing ability over a long period of time. SOLUTION: This ball valve 1 is so constructed that in a gas passage 21, a valve element 3 having an annular projecting seal surface formed partially of a spherical surface is rotatably disposed, a cylindrical seat ring 4 formed partially of the spherical surface and having an annular recessed seal surface 40 sliding on the annular projecting seal surface 34 is elastically held in the direction orthogonal to a valve shaft 31 of the valve element 3 and in the circumferential direction, and a regulating member 5 for regulating the displacement of the seat ring 4 is provided. The rotating shaft 31 of the valve element 3 is set with eccentricity to the radial direction so that the center of the spherical surface of the projecting seal surface 34 moves away from the recessed seal surface 40 of the seat ring 4 with an increase in turning angle in the valve opening direction, the projecting seal surface 34 is set to separate from the recessed seal surface 40 at the outer peripheral position from the eccentric position by the regulating member 5, and further an eccentric direction energizing means 7 is provided to energize the seat ring 4 in the eccentric direction of the valve shaft 31. COPYRIGHT: (C)2011,JPO&INPIT
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