| 摘要 |
PROBLEM TO BE SOLVED: To enhance an efficiency of an axial-flow fan even at the time of normal and reverse operation in the axial-flow fan having a two-stage axis flow impeller and capable of switching an air-feeding direction to both directions. SOLUTION: Impellers 3a, 3b and cones 11a, 11b are provided on both sides of a rotation direction-reversible type electric motor 2. An air flow is switched to any one of A and B corresponding to a rotation direction of the electric motor 2. When the air is fed to the direction A, a blade 4b of the impeller 3b on the former stage side is rotated and a jet having an axial direction component and a circumferential velocity component is sprayed from the impeller. A stay 12 having a small diameter is provided between the impellers 3a, 3b and retains the electric motor 2. Since the diameter of the stay 12 is small, a flow is not almost obstructed and a gas flow flows into a latter stage impeller 3b without changing a flowing direction. Since the impeller 3b is rotated in the same direction at the same speed as the impeller 3a, the gas flow is not almost functioned and is fed from a suction port to the outside.
|
