| 摘要 |
A centrifugal fan (3) is driven by a motor (4) which is controlled by an electronic circuit (11,7) including a radiating power component (7) such as a speed control circuit and a timer circuit (14). The power component lies near the periphery of the casing (1) by the end of the fluting (2) in the flow of the air. In normal operation, the flap (13) allows the air flow through a first exit hole (5) to a distribution module. When a signal indicates that it is to be switched off, the control circuit switches the flap to open a second exit hole (12) and close off the first for between 5 and 60 seconds, preferably 30 seconds, during which time the motor continues to operate.
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