A brushless AC generator is mounted on a vehicle such as a truck, a
farming vehicle or a construction vehicle. The generator is composed of a
housing, stator fixedly contained in the housing, a rotor, for supplying
a magnetic field to the stator, rotatably supported in the stator, and
other associated components including a voltage regulator and a
rectifier. The housing is composed of a front housing and a rear housing.
An outside fan is connected to a rotor shaft and disposed at a front
side. Cooling air is introduced into the generator by the outside fan
through windows formed in the rear housing. A fringe surface of the
window facing a shoulder portion of the rotor is sloped, so that the
cooling air is smoothly introduced along the sloped surface thereby to
improve cooling efficiency.