| 摘要 |
PURPOSE: A backflow prevention apparatus having a multi-blade structure and an air current blocking method using the same are provided to prevent the inflow of outdoor air or external noise by the consecutive rotation of multiple disks. CONSTITUTION: A backflow prevention apparatus blocks a ventilating path connected to left and right sides and blocks the flow structure of air in a lower drain hole. A central axis support portion of the backflow prevention apparatus is provided on the inner side wall of pipes which forms a lower drain hole. The backflow prevention apparatus is multiple rotating vanes(30). The angle between the vanes is 45-180°. The central axis of the vane is fixed to the support part of the pipe inner wall. |
