Patent ID: 7443073

Claim:
An electric fan comprising: a frame having a central tube extending therefrom, the frame defining an air inlet and an air outlet at two different sides thereof; a bearing received in the central tube; a stator mounted around the central tube, the stator comprising a stator core having a central cylinder, a plurality of radial posts extending from the central cylinder, a stator coil wound around each of the radial posts, and a plurality of magnetic poles formed at free ends of the posts, each magnetic pole comprising a lower portion adjacent to the air outlet and an upper portion adjacent to the air inlet, the upper portions expanding radially along a direction from the air inlet to the air outlet; and a rotor being rotatably supported by the bearing, the rotor having a hub surrounding the magnetic poles and having a profile substantially conforming a profile cooperatively formed by the magnetic poles, and a plurality of fan blades extending radially outwardly from the hub.