| 摘要 |
PURPOSE:To prevent the generation of NZ noise, by a method wherein the outlet part of the long blade of an impeller and the outlet part of the short blade thereof are positioned approximately on the same periphery. CONSTITUTION:An impeller 24 is divided into long blades 31 and short blades 32, and the outlet parts 33 and 34 of the long and short blades 31 and 32, respectively, are positioned on the same periphery. The blades 31 and 32 are caulked to front and rear plates 35 and 36, respectively, and 37 is a caulking head. This constitution increases a flow stream lining effect when an air flow is discharged, reduces air resistance due to a wide outlet and enables facilitation of movement of NZ noise to a high frequency region.
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