| 摘要 |
PURPOSE:To reduce the air flow noise by partitioning the annular wind path on the outercircumference of casing spirally with a partition board then fixing a tapered muffler member thereby forming a wind collecting section having gradually increasing cross-section in the direction of wind and a muffler section having constant cross-section. CONSTITUTION:An annular wind path 5 is provided on the outercircumference of casing 2 while surrounding a motor 4 and partitioned in spiral through a partition board 6 surrounding approximately entire outercircumference. A tapered muffler member 7 having gradually decreasing axial dimension is fixed to the end section of said partition board 6 to form a wind collecting section 5a having gradually increasing cross-section in the direction of wind and a muffler section 5b having constant cross-section and communicating with said section 5a. Consequently, the air flow noise can be reduced efficiently through compact structure.
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