To reduce magnetic flux leakage in a bridge part and to improve a magnetic characteristic of a brushless motor by devising a rotor core structure.
A rotor core 15 of a brushless motor 1 is formed by laminating a plurality of core plates 31, and a plurality of slit holes 32 are formed in the respective core plates 31. A bridge section 35 formed in an approximately T shape is arranged at an end of the slit hole 32. The bridge section 35 is constituted of an outer edge crosslinking section 36 and a partition wall section 37. Step parts 41 are formed at both ends of the outer edge crosslinking section 36 and a center side end of the partition wall section 37 by press working. Stress at the time of working is left in the step parts 41, and magnetic resistance becomes larger than the other parts of the core plate 31. The core plates 31 are laminated so that the step parts 41 are mutually overlapped in an axial direction.
WATANABE TAKASHI
MITSUOKA KEISUKE
