| 摘要 |
<p>PROBLEM TO BE SOLVED: To avoid breakage of a root of a retainer caused by deformation, breakage of a leading end of a lead valve, and instability of performance by improving rigidity of a retainer which is expanded from a retainer plate so as to regulate an opening of the lead valve. SOLUTION: A retainer 40 has a long side 41 serving as an opening regulator for a lead valve 35a and a short side 42 serving as a connection part to a retainer plate 36. A intersection line 42a between the short side 42 and a base of the retainer plate is a curved line. A root of the short side 42 is three- dimensionally expanded from the base of the retainer plate 36. Strength from the root of the short side 42 over the whole is improved, and rigidity of the retainer 40 is improved.</p> |
