Patent ID: 7977846

Claim:
A rotor for a vehicular alternating current generator, comprising: a rotary shaft; a pair of Lundell type pole cores, each of the pole cores having an axial hole in which the rotary shaft is press-fitted; a field coil wound on the pair of Lundell type pole cores; axial inner end faces of the pair of Lundell type pole cores being in close contact with each other; and a relief space portion having an annular configuration with a larger diameter than the axial holes of the pair of Lundell type pole cores and formed adjacent the axial inner end faces between the axial holes of the pair of Lundell type pole cores and the rotary shaft, the relief space portion receiving therein a plastically deformed portion produced when the rotary shaft is press-fitted in the axial holes of the pair of Lundell type pole cores, the relief space portion having a same diameter and an average radial space width which is set to be larger than an average radial space width between the axial holes and the rotary shaft at a substantially press-fitted portion of the rotary shaft and the axial holes located axially outward of the relief space portion, wherein the diameter of the relief space portion being constant along an axial direction of the relief space portion.