Image Number 4 for United States Patent #7472717.
A first valve port is set to have a seal diameter smaller than that of a second valve port. Due to a pressure reception area of a first valve body port being small, the attachment force of the first valve body portion is reduced with respect to a valve seat. It thus becomes possible to open the first valve port as the attachment of the first valve body portion is released with respect to the valve seat without increasing the weight of the float. After the first valve port is opened, the pressure difference is reduced between inside of a fuel tank and a connecting pipe on the side of a canister, and the attachment force acting on a second valve body portion is also reduced. In this manner, the second valve body portion is opened with certainty. As a result, it becomes possible to go through the operation of opening the second valve port that is larger in diameter than the first valve port without increasing the weight of a sub float.