| 摘要 |
PURPOSE:To improve vibration responsive property and blowing effect, reduce noise and simplify construction of a propeller fan by connecting boss portions of the propeller fan to form a hub portion, thickening the boss portion and thinning the motor side to provide a double stepped inner surface of the hub portion. CONSTITUTION:A propeller fan 6 is formed of a blade 10 and a cylindrical hub 8. The hub 8 has a 2 stepped construction in which the boss portion 7 is thickened and the motor side thinned in the thickness of the hub wall. Thus, in this propeller fan 6, vibration responsive level is generally lowered in the frequency zone of about 100Hz-120Hz, and particularly in the frequency of 100Hz on which emphasis is laid, an extremely low level is obtained. Also abnormal noises in the frequency of about 100Hz can be removed economically with an extremely simple construction.
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