| 摘要 |
<p>A fuel cap 10 of the invention has a pressure regulating valve 50, which includes a positive pressure valve 60 and a negative pressure valve 70. The positive pressure valve 60 has a positive pressure valve plug 61 and a first spring 68. The negative pressure valve 70 has a negative pressure valve plug 71 and a second spring 78. A ring-shaped projection 73c is protruded outward from the upper circumferential end of the negative pressure valve plug 71 to face a first valve flow path 25d, and functions as a restriction member. The restriction member narrows the passage area of the first valve flow path 25d in a closed position of the negative pressure valve plug 71, while widening the passage area of the first valve flow path 25d in an open position of the positive pressure valve plug 61 where the negative pressure valve plug 71 moves integrally with the positive pressure valve plug 61. This arrangement effectively improves the flow characteristics of the pressure regulating valve 50 in the open position of the positive pressure valve 60.</p> |
