| 摘要 |
PURPOSE: A ventilation fan is provided to control the installation of a blade by fitting a pin on a pin groove of a first half-socket portion and a pin groove of the blade. CONSTITUTION: A ventilation fan comprises the followings. An axis mounting part(11) for mounting the axis of an electric motor is formed on the center of a hub disc(10). A plurality of first half-socket portions(12) is formed on the circular perimeter of the hub disc at constant intervals. A tooth-shaped part(123) is formed on the first half-socket portion. A hub cap(20) is coupled on the hub disc through a plurality of bolts(41) and nuts(42). A plurality of half-socket portions(22) formed on the circular perimeter of the hub cap are arranged to be coupled with the first half-socket portion of the hub disc. A mounting part(31) of a blade(30) is mounted on the first half-socket portion of the hub disc and the second half-socket portion of the hub cap. A concavo-convex part(314) is formed on the mounting part, and the installation angle of the blade is determined due to tooth-shaped projections.
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