Rotor

A rotor comprising:

• a cylindrically shaped hub secured to an output shaft;
• an annularly shaped rotor core disposed radially outward of the hub and connected to the hub with a plurality of ribs therebetween so as to be formed integrally with the hub;
• holes formed between the hub and the rotor core so as to be provided among the ribs;
• and
• permanent magnets retained in openings that are formed on a circumference of the rotor core so as to be substantially equally spaced apart from one another in a circumferential direction,
• wherein salient poles are each formed between neighboring openings among the openings on the circumference of the rotor core and, when viewed from a front along a line of axis of the rotor, a recessed portion that is formed by causing one portion of an inner circumferential surface of the rotor core to bulge radially outward of another portion is provided in a region enclosed by a first virtual line connecting a center of the hub and a circumferential middle position on the circumference of a magnetic pole of the rotor core having the permanent magnets provided therein and a second virtual line connecting the center of the hub and a circumferential middle position on the circumference of the salient pole adjacent to the magnetic pole at a leading side in a rotational direction of the rotor.