| 摘要 |
PURPOSE:To prevent reduction of durability of a ball valve by forming a ball seat at a radially intermediate portion with an annular groove for imparting resilience. CONSTITUTION:A ball 4 of a ball valve is rotatably disposed within a body 1, and has a through hole 6 through which inlet and outlet ports 2, 3 communicate, as shown in the drawing. An annular ball seat 8 is attached to a mounting seat 9 to come in abutment against the ball 4. The ball seat 8 is formed in the rear surface 10 in abutment against an annular plane 9b with an annular groove 11 having such a large width as to impart resilience, the central diameter A of the annular groove 11 being substantially coincident with the central diameter B of an annular contact surface 12. With this construction, the ball seat 8 is in the form of a double end-supported beam in section, and the annular contact surface 12 is pushed at the position of the central diameter B by the ball 4, causing impact resilience for supporting the ball, so that durability can be improved.
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