| 摘要 |
PURPOSE:To elastically bring a valve body into contact with a valve seat and obtain secure sealing by making a metal piece which is brought into contact with a projecting valve seat in a valve casing a pressed condition by means of an elastic element while fitting said metal piece into an annular recessed part of said valve casing. CONSTITUTION:An annular projecting valve seat 2 on the inner peripheral face of a valve casing A is formed in such a way that its wall thickness gets larger toward a closing direction. Two stages of annular step parts 8, 8' are formed on the outer peripheral part of a valve body 1, and an elastic element 4 and a metal piece 3 are integrally fitted into the step part 8 and a retainer board 7 having an annular projection 6 which is brought into contact with the elastic element 4 is fitted in from the outside. And, when a valve is closed, the metal piece 3 rides over the valve seat 2 and is gradually pressed into an annular recessed part 9 until the valve is completely closed, and the elastic element 4 which is fitted in on the top of the metal piece 3 is compressed in between the valve body 1 and the metal piece 3, and is vertically crushed and laterally expanded, being effectively brought into pressure contact with the projection 6 of the retainer board 7. By these members, the sealing between the valve body 1 and the metal piece 3 and between the valve seat 2 and the metal piece 3 can be completely performed.
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