| 摘要 |
PROBLEM TO BE SOLVED: To prevent increase in pressure inside an upper lid and to prevent wash water from entering the upper lid. SOLUTION: A fin-like valve 12 inclining downward is formed on the external circumferential surface 3a of an outer tube 3 of an inner stopper 2 facing the internal circumferential surface 20a of an upper lid 20 when a lid is closed. |
