| 摘要 |
A rubber (elastic substance) is attached by vulcanization and an annular sealing member 4 is formed in an annular groove 3 having a step and provided in the bottom wall of a body 2 of a valve disc 1 . The sealing member 4 has an annular portion 41 and an annular portion 42 . Most of the annular portions 41, 42 are located in a deep groove portion 31 and a shallow groove portion 32 , respectively, and the volume of the annular portion 41 is larger than the volume of the annular portion 42 . Furthermore, an annular protrusion 43 , which protrudes downward, is provided in the boundary region between the annular portions 41, 42 . An inclined section that is inclined at the prescribed inner angle Q is also formed in the boundary region.
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