| 摘要 |
PROBLEM TO BE SOLVED: To provide a centrifugal blower capable of expanding a frequency range of reducible noise, and capable of adjusting a frequency of the reducible noise, in the centrifugal blower used for a ventilating air-blowing apparatus. SOLUTION: This centrifugal blower capable of expanding the frequency range of the reducible noise is provided by forming a centrifugal blower 1 having an electric motor 6 connected with an impeller 5, a casing 10 surrounding the periphery of the impeller 5 and having a bell-mouth-shaped suction opening 7 on one surface, and a bell-mouth-shaped orifice 19 concentric with the suction opening 7 and having an opening part 18 of a diameter equal to or less than the suction opening 7, in the contour 3, and forming a resonance type sound absorption structure, with a member for blocking up a clearance part 22 between an end part 21 of the orifice 19 and the casing 10 as a sound absorbing structural material, and with a space 20 formed of the orifice 19 as a back air layer 24. COPYRIGHT: (C)2008,JPO&INPIT
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