| 摘要 |
<p>An exhaust valve device for a fuel tank allows gas to smoothly circulate without increasing the device in size. The exhaust valve device for a fuel tank includes casings partitioning an inside into an upper chamber and a lower chamber by a bulkhead including a through hole; and a float valve. A portion defining the upper chamber of the casing includes a cylinder portion in which an exhaust port is formed, and a circular plate closing an upper end of the cylinder portion. A cylinder body is provided around an upper chamber side of a communication hole, and a first ventilation hole is formed in a side wall on a side opposing an exhaust port side of the cylinder body. At a boundary portion between an inner circumferential face of the cylinder portion and a lower face of the circular plate, a corner portion having a curved surface shape smoothly connecting between the inner circumferential face of the cylinder portion and the lower face of the circular plate is extended. A curvature of the corner portion is the smallest on a side opposing a side forming an exhaust hole, and gradually increases as moving toward the side forming the exhaust hole in a circumferential direction.</p> |
