Patent ID: 8008825

Claim:
A disc-shaped electromagnetic steel plate for forming a rotor core, comprising: a disc-shaped plate member; first and second magnet holes having a first longitudinal side and a second longitudinal side, respectively, and provided in the disc-shaped plate member to accommodate first and second permanent magnets, respectively, the first and second magnet holes being provided such that the first longitudinal side and the second longitudinal side extend substantially in parallel with forward and rear extending directions, respectively, in a predetermined pole pitch angle between rear radial pole pitch line and a forward radial pole pitch line that is positioned at a forward position with respect to the rear radial pole pitch line in a rotational direction of normal rotation of the rotor core, the first and second magnet holes forming a substantially V-shape having a vertex which is substantially on a center diameter dividing the pole pitch angle to half, the first magnet hole being provided at a forward position with respect to the second magnet hole in the rotational direction, a forward acute angle between the forward extending direction and the center diameter being larger than a rear acute angle between the rear extending direction and the center diameter, a forward shortest distance between the first magnet hole and the forward radial pole pitch line being smaller than a rear shortest distance between the second magnet hole and the rear radial pole pitch line; and a center bridge located at the vertex of the V-shape to partition the first and second magnet holes.