VENTILATION DEVICE

摘要

A ventilation device in which a closing member is adapted to be simply movable and the durability of an elastic seal material is advantageously enhanced. When an operation handle (43) is rotated to move the closing member (20) from a closed position (CP) to an open position (OP), in the initial stage of the movement of opening operation, the closing member (20) moves from the closed position (CP) toward the open position (OP) while increasing the gap (S) between a sealing surface (2004A) and an opening edge (18A), and after that, the closing member (20) moves while maintaining the gap (S) constant and reaches the open position (OP). On the other hand, when moving from the open position (OP) to the closed position (CP), the closing member (20) moves along a flat surface (P) while maintaining the gap (S) constant until the closing member (20) reaches the final stage of the movement of closing operation, and in the final stage, the closing member (20) reaches the closed position (CP) with the gap (S) reduced and presses the sealing surface (2004A) against the opening edge (18A).