US Patent 10479561 Stopper

The stopper is equipped with a stopper main body having a guiding path extending in an axial direction. A stopper member has a flow path extending in the axial direction and is inserted in the guiding path of the stopper main body. A sealing member inserts into the flow path of the stopper member in such a manner as to block the flow path. The stopper member is equipped with, at a position where the sealing member is inserted, a first peripheral wall section fixed in a manner as to extend in the axial direction and a second peripheral wall section separated from the first peripheral wall section in a circumferential direction and extending radially outward along the axial direction.