| 摘要 |
PROBLEM TO BE SOLVED: To increase rotation speed difference and to improve fan efficiency although there is a problem wherein fixed flow rate control by using characteristics of a fan is normally made by detecting rotation speed under a low pressure high flow rate condition and under a high pressure low flow rate condition, but difference between rotation speed under the low pressure high flow rate condition and rotation speed under the high pressure low flow rate condition is not large and fan efficiency is low in a former multi-blade fan. SOLUTION: A diameter D of a main plate is smaller than an outer diameter D2 of a suction port side blade and a blade provided on an opposite side of the suction port side, and is larger than an inner diameter D1 of the suction port side blade and the blade provided on the opposite side of the suction port side. Outlet anglesβ2 which are outlet angles of the suction port side blades 8 are different sequentially in an axial direction. Outlet anglesβ4 which are outlet angles of the blades 9 on the opposite side of the suction port side are made smaller than outlet anglesβ6 at the main plate part of the suction port side blades 8. Fixed flow rate control is thereby made easy and a multi-blade fan 1 of good fan efficiency is provided. COPYRIGHT: (C)2008,JPO&INPIT
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