Air interchanger of civil air defense door

The utility model discloses an air interchanger of a civil air defense door, which belongs to the technical field of civil air defense doors and comprises a door plate, a ventilation opening is formed in the outer side wall of the door plate in a penetrating manner, a cover plate is fixedly mounted at an air outlet of the ventilation opening, a port is formed in the right side wall of the cover plate in a penetrating manner, and a sealing plate is mounted in the cover plate. A fixing frame is fixedly installed at the bottom of the cover plate, and a connecting rod is movably installed in the fixing frame, so that when a ventilation opening in the door plate needs to be opened, a screw rod moves to push a limiting frame to move leftwards, a sealing plate is promoted to be separated from the cover plate, then a port of the cover plate is opened, ventilation is achieved, and when ventilation is finished, a hand wheel is rotated reversely, and the door plate is opened. And the screw rod pulls the limiting frame t