External rotor motor and draught fan comprising the same

An external rotor motor, comprising:

• a front end cover, the front end cover comprising a first bearing chamber in which a front bearing is disposed;
• a rear end cover;
• a sleeve casing;
• a rotary shaft;
• a stator assembly;
• and
• an external rotor assembly;
• wherein
• the front end cover and the rear end cover are disposed at two ends of the sleeve casing, respectively;
• the external rotor assembly is disposed on and integrated with the rotary shaft;
• the rear end cover comprises a cover body and a sleeve base protruding upwards from the cover body;
• the sleeve base comprises a second bearing chamber in which a rear bearing is disposed;
• the stator assembly sleeves the sleeve base;
• the external rotor assembly is disposed in the sleeve casing and sleeves the stator assembly;
• the rotary shaft comprises a head, a middle part, and a tail;
• the tail of the rotary shaft is supported by the rear bearing on the rear end cover;
• the middle part of the rotary shaft is supported by the front bearing on the front end cover;
• and
• the head of the rotary shaft extends out of the front end cover to form a shaft extension connected to a load.