| 摘要 |
PROBLEM TO BE SOLVED: To implement a more effective cooling means responding to increase in the amount of heat generated by a motor and its control circuit accompanying size reduction or enhanced performance of a centrifugal fan. SOLUTION: The centrifugal fan has a casing, a multiblade impeller, and the motor and its control circuit disposed in a rotor boss holding the multiblade impeller. A ventilation hole is formed to a cylinder part near a top surface of the rotor boss, and another ventilation hole is formed to a circuit board or a portion near a circuit board opposed part of the casing, and ribs communicating to peripheries of respective ventilation holes are formed to an inner surface of the rotor boss. COPYRIGHT: (C)2009,JPO&INPIT
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