| 摘要 |
<p>PURPOSE:To reduce the noise level of a cooling fan by providing in exposing a sound absorbing material along the ridgeline of a housing to a place near an opening at the upper part of the housing. CONSTITUTION:The sounds produced at an entrance of a fan are radiated into a cover 2 from an upper sucking opening part 6 of a housing 9 in the direction opposite to the air flowing direction. These sounds intend to go into the rear side by a diffraction phenomenon of a sound wave and are radiated to the outside through a cover opening part 10 after passing through a path between the cover 2 and the housing 9. Therefore it is needed to bond a sound absorbing material at a position having high energy density of sound in order to reduce the noise level without increasing the fluid resistance level. The sound absorbing material is bonded at a ridgeline part 8, i.e., a rack of a diffraction part of the sound wave as well as a ridgeline part 12 of the part 10 since these parts have the highest energy density. Thus the noise level can be extremely reduced.</p> |
