| 摘要 |
PROBLEM TO BE SOLVED: To certainly prevent a gasket from falling off by a method wherein a cylindrical fall-preventing rib is provided in projection at the inner bottom of a tank cap so that it can expand outward, and a plurality of slits are provided at the fall-preventing rib. SOLUTION: A fall-preventing rib 13 for a gasket is formed in a cylindrical shape expanding gradually outward from the center at the inner bottom of a tank cap main body 10 and provided in downward projection. The diameter of the rib is made smaller than the diameter of a injection port 9, and the fall-preventing rib 13 is arranged so that it does not interfere with the injection port 9. The fall-preventing rib 13 is formed in a shape wherein the diameter thereof expands downward and an edge part is formed at the outside on the lowermost part thereof so that a gasket 14 can be held therewith at its inside Slits 15, 15... provided at several parts on the circumference of the fall- preventing rib 13 are for making the tank cap 10 easily detachable from a metal mold when the tank cap is produced by injection molding. The gasket 14 is inserted from the inner side of the tank cap 10 and fitted into the fall- preventing rib 13. |
