| 摘要 |
PROBLEM TO BE SOLVED: To solve a problem wherein a multiblade fan is requested to further reduce noise although the noise of an impeller has reached its limit. SOLUTION: This multiblade fan 5 is provided with a plurality of blades 6 mounted to be held by an annular side plate 10 and a main plate 11 having a restricted part of approximately truncated cone shape formed as a projecting part 8 on the side plate 10 side, inside a spiral casing 4 formed with an orifice 1 of bellmouth shape on one side and having a suction port 2 and a discharge port 3 with inner diameters equal to the inner diameter of the blade 6, and the back side shape in the cross section vertical to the rotation axis of the blade 6 has stepped parts 7 suddenly narrowed in a rear edge direction from a front edge direction. COPYRIGHT: (C)2006,JPO&NCIPI
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