| 摘要 |
PURPOSE:To increase dynamic pressure ventilation performance with no increase of a noise level, by forming an end part internal wall, placed in a side oppositely facing to a bell mouth-shaped suction port, of a blade in a smooth circular arc shaped while an internal diameter of the bell mouth-shaped suction port larger than the intermediate value between an internal and an external diameter of the blade. CONSTITUTION:A centrifugal multi-blade fan 1 forms an end part internal wall 1c, placed in a side opposed to a bell mouth-shaped suction port 2, of a blade 1a in a smooth circular arc shape, and a circular arc-shaped peripheral edge part (a) smoothly continues to an external diameter part of the blade. While the relation of an internal diameter Da and an external diameter Db of the centrifugal multi-blade fan 1 to an internal diameter D2 of the bell mouth- shaped suction port 2 is formed in a relation such that the internal diameter D2 of the bell mouth-shaped suction port 2 is formed larger than the intermediate value D2approx.=(Da+Db)/2 of the blade 1a. Consequently, dynamic pressure ventilation performance can be increased with no increase of a noise level.
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