Patent ID: 9214838
Filing Date: 2015-12-15
Classification: H02K

Abstract:
1. A brushless motor capable of high speed rotation by field weakening operation, comprising: a rotor comprised of a generally cylindrical rotor core having permanent magnet receiving holes and formed with groups of slits, the slits in each group extending inward between one of the permanent magnet receiving holes and an outer circumference of the rotor core, wherein the groups of slits are configured such that an outer width between outer ends of the slits in each group and the outer circumference of the rotor core is substantially equal to an inner width between inner ends of the slit and the permanent magnet receiving hole, and the inner and outer widths are about twice or more wider than a minimum width between the permanent magnet receiving hole and a section of the outer circumference of the rotor core that is located between two adjacent permanent magnet receiving holes, and wherein torque ripples observable at a highest speed load point are 1 to 1.5 times higher than torque ripples observable at a low speed load point.