| 摘要 |
A cap for closing the filler neck of a vehicle fuel tank is provided. The cap includes a valve body having an upper opening and movable between a normal lower position and an upper position. The valve body includes a ball disposed therein to seal the upper opening when the cap and filler neck are rolled over to a substantially inverted position and vent openings in the side wall that are located somewhat above the level of the ball when the cap and filler neck are substantially upright. When the valve body is in the normal lower position, fuel vapor is allowed to vent to the atmosphere through the vent openings and upper opening in the valve body. If the ball is upwardly and seals the upper opening prematurely, the fuel vapor will form the valve body to the upper position to allow the fuel vapor to continue to vent to the atmosphere around the valve body. In another embodiment of the invention, the cap may include an axially movable plunger to allow the ball to be manually displaced in the event the ball prematurely seals the upper opening.
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