Ventilation fan backflow prevention device with improved ventilation, and ventilation fan including the same

摘要

The present invention provides a shielding unit including an upper plate covering one side of a fan through which indoor air is sucked, a lower plate provided in the center of the upper plate, and a plate opening provided in the lower plate; and an opening/closing part fixed to the lower plate to close the plate opening by its own weight, but opening the plate opening by the suction force of the fan, wherein the lower plate is formed at a lower position than the upper plate It relates to a ventilation fan backflow prevention device.