Patent ID: 9729037
Date: 2017-08-08
CPC Classifications: F04D,H02K

Claim:
1. A brushless motor, comprising: a stator comprising a stator core having 6N teeth and a stator winding having 6N coils wound respectively around the teeth, where N is an integer equal to or greater than 1; and a rotor comprising a shaft, a rotor core fixed to the shaft and 6N±2 permanent magnets fixed to the rotor core, the rotor core comprising a cup-like shell comprising a shell end, the shell end defining a tubular boss at the center thereof, one end of the shaft being fixed to the shell by a press fit connection with the tubular boss; wherein the permanent magnets are arranged circumferentially around the stator core and face the teeth across an air gap, the radial thickness of the air gap is uneven along the circumferential direction of the motor, each permanent magnet has a circumferential center and two circumferential ends and the radial thickness of each permanent magnet at the center is greater than the radial thickness at the circumferential ends; and the radial thickness of the air gap is less at the center of the magnets than at the circumferential ends of the magnets; wherein the entire radially inner surface of each permanent magnet is an arcuate surface with the circumferential center of the magnet being closer to an aligned tooth than the circumferential ends thereof; wherein the shell end comprises a number of assembling holes for mounting a fan and a number of openings for air to flow through the interior of the motor; wherein each tooth of the stator core has at least one slot extending in the axial direction of the motor on the radially outer surface thereof.