| 摘要 |
PROBLEM TO BE SOLVED: To improve a strength by forming a lateral vent hole perpendicularly crossed with a centerline of a lengthwise direction of a vent passage opened with both end faces of the lengthwise direction. SOLUTION: An opening of a lateral vent hole 6 assures a respiration even in the case of clogging the tail plug 1 in a throat in a lateral direction, and is formed as a pair as an air exit/entrance and the opening of the hole 6 opened at an outside wall of just opposite side. In the case that an appearance of the plug 1 is like a columnar shape, a direction of the plug 1 swallowed in a lateral direction cannot be specified, and hence it is preferable that at least adjacent lateral vent holes existed at 120 degrees or less. In this embodiment, since a part to be inserted into the barrel via an annular protrusion 5 through adjacent vent holes and a part protruding from the barrel are formed so that longitudinal positions are differentiated, many holes are not formed on the same circumference, thereby suppressing its damage or deformation due to a decrease in its strength as much as possible. |
