| 摘要 |
<p>PROBLEM TO BE SOLVED: To enable restriction of simple noise of a centrifugal fan and restriction of resonance sound of the entire device including the centrifugal fan to be attained together.SOLUTION: In this invention, a cylindrical impeller having a plurality of blade pieces vertically installed from an outer edge portion of a rotary plate is stored in a scroll casing and axial one end side of a rotating shaft is covered by a cover plate provided with a bell mouth-shaped opening for guiding air inside the impeller. Then, the opening is arranged while a center of the opening is set to be eccentric to a direction approaching a tongue part (a connected portion between the small diameter side of the scroll casing and an air blowing passage). With this arrangement, a space where a flow of air flowing from the opening toward the blade piece is disturbed by a back flow near the tongue part can be reduced more than a case where the opening is not set to be eccentric. As a result, it is possible to restrict simple noise caused by the back flow while an opening area of the opening is reduced and resonance sound is restricted.</p> |
