Patent ID: 8456057

Claim:
A laminated stator core, formed by laminating stator core sheets, each of the stator core sheets punched out from a magnetic metal sheet so as to have a common axis with a rotor core sheet, the rotor core sheet punched out from the magnetic metal sheet before the stator core sheet is punched out, each of the stator core sheets comprising: a yoke piece; a plurality of magnetic pole shaft pieces integrally formed inside the yoke piece; and a magnetic pole tooth piece integrally formed inside each of the magnetic pole shaft pieces, wherein each of the magnetic pole shaft pieces is provided with a thin section, the thin section having a rectangular cross-section, the thin section is formed by pressing a part or a whole of the magnetic pole shaft piece in a thickness direction thereof, and elongating the same in a radially inward direction, and further wherein i) each of the thin sections has a thickness within 50-95% of that of the magnetic metal sheet; ii) each of the thin sections has a radial length within 65-100% of that of the magnetic pole shaft piece; and iii) a required elongation of the magnetic pole shaft piece is determined by a formula: (a groove length×a groove depth)/a material thickness.