Squirrel-cage rotor and rotating electric machine

A squirrel-cage rotor comprising:

• a shaft lying along an axial direction;
• and
• a rotor iron core that has a cylindrical shape, the rotor iron core being a group of laminations of circular plate parts, each of the circular plate parts having a circular hole at its center, the circular plate parts being stacked in the axial direction with the shaft passing through their circular holes,
• the rotor iron core having more than one slot which is arranged at regular intervals along a circumference side of the rotor iron core, the slot extending along the axial direction,
• the slot having
• an outside circumference edge which is positioned near an outer side of the rotor iron core, the outside circumference edge having a first corner at its one end, the outside circumference edge having a second corner at the other end thereof, the outside circumference edge having a shape which expands toward the outer side beyond a first virtual circle, the first virtual circle connecting the first corner and the second corner, the first virtual circle being concentric with the rotor iron core,
• an inside circumference edge which is positioned near an inner side of the rotor iron core, the inside circumference edge having a third corner at its one end, the inside circumference edge having a fourth corner at the other end thereof, the third corner having a curvature radius smaller than that of the first corner, the fourth corner having a curvature radius smaller than that of the second corner, the inside circumference edge having a shape which expands toward the outer side beyond a second virtual circle, the second virtual circle connecting the third corner and the fourth corner, the second virtual circle being concentric with the rotor iron core,
• a first side edge which connects the first corner and the third corner, and
• a second side edge which connects the second corner and the fourth corner.