| 摘要 |
In a roof ventilator with an electric drive motor arranged inside a protective housing, this protective housing is designed in two parts, a housing part bearing the motor being fastened to the overall cylindrical fan ventilator housing by means of guide blades which pass radially through the outgoing-air flow duct. The motor is held by distance pieces at a clear distance from the bottom of the protective housing part which has a central opening, through which the driven shaft of the motor passes. In this construction, fan wheels of the most different types, axial, radial or semi-axial fan wheels, can be attached to the motor. The cooling air supply to the motor, which is to be particularly protected in case of fire, takes place via cooling air supply pipes integrated into the guide blades. By means of a cylindrical guide plate arranged in the interior of the protective housing, it is brought about that an air flow generated by the cooling fan of the motor flows around the motor on all sides and is deflected outwards reliably through the central bottom opening of the protective housing. Provided on the fan wheel are ribs with a radial-fan effect which intensify the cooling air flow.
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