| 摘要 |
A vacuum cleaner having a suction nozzle and a dust bag (12) which is connected to the nozzle, for instance, by a tube connection, and a turbo-fan unit (27) driven by an electric motor and placed after the dust bag seen in the flow direction. The impeller (29) of the turbo-fan unit is driven at a speed above 50,000 rpm. A primary air stream created by the turbo-fan unit (27) leaves the unit via an outlet (30) to atmosphere. The vacuum cleaner also creates a secondary air stream which at least partially cools the electric motor (32) and which flows into the electric motor via one or several cooling air inlets (44) which are separated from the primary air stream. The secondary air stream can be created by a cooling fan which is separate or integral with the impeller, by a venturi-type nozzle, or by suction created by the impeller. The primary air stream flows in one direction through a channel surrounding a motor shell and the secondary air stream flows in a second, opposite direction through the motor shell and is thereafter redirected and mixed with the primary air stream.
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