Backflow prevention valve

摘要

A valve body main unit has a circular step surface 101 facing a circular valve seat surface 124 of a valve chamber formed on a terminal end part of a fuel supply path to a fuel tank. A circular groove 102 with one groove wall 102b extends from the circular step surface 101 and is normally urged in a direction of closing an inflow port surrounded by the circular valve seat surface 124. The valve body main unit also has an elastic seal body 11 with a ring shape inserted into the circular groove 102 of the valve body main unit. The elastic seal body has a circular fin-shaped part 111 projecting from an outer perimeter part and pushed against the circular valve seat surface 124 by the urging of the valve body main unit to close the valve.