| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a protective cap capable of preventing flow-out of a large amount of gas from a gas hole of a plug by an unexpected accident when the plug is not used. <P>SOLUTION: An annular protrusion part 15a is formed at a bottom part 15 of a cap part 13. The annular protrusion part 15a annularly comes in press contact with a diameter expansion part 4b of the plug 4 when the cap part 13 is externally inserted in the plug 4 into a prescribed position. <P>COPYRIGHT: (C)2012,JPO&INPIT</p> |
