| 摘要 |
PURPOSE:To reduce noises by fitting, in a row, each one end of n sheets of lower blades on the outer periphery of a base plate which has been continuously provided to a blade boss, and fitting, in a row, each one end of (n+1) sheets of upper blades on the other end of the lower blade via a partition plate. CONSTITUTION:On the outer periphery of the base plate 2 of an impeller boss 1, each one end of n sheets of lower blades 3 is arranged so as to be fitted in a row. The other end of the lower blade 3 is fitted on one surface of a partition plate 4, and on the other surface of this partition plate 4 each one end of (n+1) sheets of upper blades 5 is arranged so as to be fitted in a row. Thus, since the number of upper blades 5 is greater than that of lower blades 3 by one sheet, noises are divided into the peak noise of the upper blades 5 and that of the lower blades 3, thereby the overall peak noise can be reduced.
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