| 摘要 |
A vacuum relief system for a fuel tank is provided to save necessity of dedicatedly supplying makeup air for compensating a vacuum in a steam space of the fuel tank by maintaining an opened state of a vacuum-relief controller even after the air in the fuel tank is removed. A vacuum relief system for a fuel tank(16) is adopted to a filler neck cap(12) that comprises a closure, a vacuum relief controller, and a maintaining unit. The closure is connected to a filler neck(14) to close an opening of the filler neck, and includes a vent hole opened to the ambient air. The vacuum relief controller moves with respect to the closure. More specifically, when pressure in the filler neck drops to be lower than a predetermined atmospheric pressure, the vacuum relief controller moves from a closing position that interrupts an airflow through the vent hole, to an opening position that allows the airflow. Even after the pressure in the filler neck increases to be greater than the predetermined atmospheric pressure, the vacuum relief controller stays in the opening position to allow flow of the air and fuel steam through the vent hole.
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