Patent ID: 7116022

Claim:
An AC generator for a vehicle comprising: a rotor which is rotated by a torque transmitted thereto; a frame rotatably supporting the rotor; a cooling fan fixed to the rotor and for taking in a cooling wind from outside by rotating integrally with the rotor; a protection cover disposed outside of the frame so that the frame and the protection cover form a gap therebetween for taking in the cooling wind; and a rectifier disposed between the frame and the protection cover and having a first end face facing the frame and a second end face opposite to the frame, wherein: an axial extent of the frame, which is measured in an axial direction of the rotor, is not overlapped with an axial extent of an outer peripheral wall of the protection cover, which is measured in the axial direction of the rotor; the frame has a slant face facing the rectifier; a clearance between the slant face and the first end face of the rectifier increases toward outer side in a radial direction of the frame, and a plurality of heat radiation ribs disposed on the first end face of the rectifier, each of the heat radiation ribs extending in an airflow direction of the cooling wind, wherein a height of each of the heat radiation ribs gradually increases toward outer side in the radial direction so that a ridge of each of the heat radiation ribs extends along the slant face.