US Patent 7868503 Embedded magnet motor and manufacturing method of the same

In an embedded magnet motor, radial magnets and first inclined magnets form north poles. The radial magnets and second inclined magnets form south poles. Core sheets each include preformed radial accommodating slots the number of which is expressed by P/2. Some of the preformed radial accommodating slots are short slots and the rest are long slots. The short slots are located at some parts of each radial accommodating slot along the axial direction. Radially inner ends of the short slots restrict the radial magnets from moving radially inward.