US Patent 8653710 Permanent magnet electric motor

A rotor has rotor cores divided in the axial direction. A permanent magnet is mounted at the position of each of the magnetic poles of cores. The permanent magnet of each magnetic pole is configured by a single tabular member that penetrates the two divided cores in the axial direction. Convex parts are respectively provided on the outer peripheries of the respective magnetic poles of the rotor cores along the axial direction of the rotor. The convex parts are provided to positions that are displaced for each of the two divided cores. The magnetic flux density increases in the convex parts, which becomes the magnetic pole center. Since the convex parts positions are displaced to each other, a skew function can be exhibited even if the permanent magnet is mounted at the same position.