Patent ID: 7291948

Claim:
An alternator for a vehicle, comprising a cooling fan which is disposed on at least one of an axial-directional end surface of a Lundell type rotor having a plurality of nail-shaped magnetic poles, a plurality of fan bases fixedly attached to the axial-directional end surface of the rotor by fixing members, such as welding members and a plurality of fan blades, respectively, disposed to stand on the corresponding fan base along an axial direction of the cooling fan, and the cooling fan generating a cooling wind for cooling a heat generating portion while being integrally rotated with the rotor, wherein a portion of one fan blade extending from a boundary portion, at which a boundary line between the one fan blade and the correspond fan base crosses over a side line of one of the nail-shaped magnetic poles facing another one of the nail-shaped magnetic poles, is placed over the one nail-shaped magnetic pole, the corresponding fan base has an opposing surface which is opposite to the another one of the nail-shaped magnetic poles, and on the opposing surface of the corresponding fan base, among a plurality of fixing portions corresponding to the another one nail-shaped magnetic pole, a distance L 1 between a first fixing portion placed on an outer-diameter side with respect to a rotational axis of the rotor and the boundary portion is set to be almost equal with a distance L 2 between a second fixing portion placed on an inner-diameter side and the boundary portion.