Patent ID: 7683518

Claim:
A motor comprising: a stator including a stator iron-core formed of a salient iron-core and a yoke, and a winding wound on the stator iron-core; and a rotor facing an inner wall of the salient iron-core and held rotatably, the rotor including a rotor iron-core formed by laminating an iron sheet of high permeability, wherein the rotor iron-core includes a plurality of holes in which permanent magnets are to be buried, and the permanent magnets buried in the holes, wherein a magnetic pole centerline connecting a rotary center of the rotor to a magnetic pole center crosses an external shape of the rotor iron-core at end point X, and a magnetic-pole boundary line connecting the rotary center to a magnetic pole boundary point crosses the external shape of the rotor iron core at end point Z, and a straight line angled at a given angle “θa” from the magnetic pole centerline toward the magnetic boundary line and extending through the rotary center crosses the external shape of the rotor iron-core at end point A, wherein a sectional view of the rotor iron-core shows an arc drawn between end points X and A, and a center of the arc is the rotary center, and the end points A and Z are connected by at least one straight line, and the at least one straight line exists inside a circle drawn by an extension line of the arc at the same curvature, and wherein a minimum distance between an end of one of the plurality of holes and the external shape of the rotor iron-core is referred to as “Ln”, and a thickness of the iron sheet of high permeability is referred to as “d”, then a relation of d/2<Ln<2d is established.