Patent ID: 8405271
Filing Date: 2013-03-26
Classification: H02K

Abstract:
1. An interior permanent magnet type brushless direct current (BLDC) motor comprising: a stator having a plurality of slots and a stator coil wound on the slots; and a rotor configured to rotate with respect to the stator and having a rotor core, a plurality of permanent magnets positioned in the rotor core, and a plurality of cut off portions, wherein a plurality of first cut off portions each positioned between adjacent permanent magnets, a plurality of second cut off portions each configured to have a different shape from the first cut off portions and positioned between the first cut off portions, and a plurality of non cut off circumferential portions each positioned between one of the first cut off portions and one of the second cut off portions, wherein a maximum gap between the rotor and the stator is defined by the first cut off portions, wherein a minimum gap between the rotor and the stator is defined by the non cut off portions, and wherein a ratio of the depth of the first cut off portions to the minimum gap is in the range of 1.0 to 4.0.