| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a ceiling embedded ventilation fan capable of expanding a frequency band enabling sound attenuation and reducing noise even when the state of a fan load is changed. <P>SOLUTION: The ceiling embedded ventilation fan 1 is provided with: a casing 8 having a suction port 15; a centrifugal impeller 7 arranged inside the casing 8; an electric motor 6 for rotating the centrifugal impeller 7; an orifice plate 16 with a communication hole 17 arranged between the casing 8 and an opening 3 of an outer hull 4; and a sound attenuation means arranged between the orifice plate 16 and the opening 3 of the outer hull 4. Due to this structure, the ceiling embedded ventilation fan 1 can perform resonance and sound attenuation of noise emitted from the suction port 15 of the casing 8 in a space between the casing 8 and the orifice plate 16, at the same time attenuate noise emitted from the communication hole 17 of the orifice plate 16 by the sound attenuation means, and expand the frequency band enabling sound attenuation. <P>COPYRIGHT: (C)2010,JPO&INPIT</p> |
