Patent ID: 7339296

Claim:
An ac generator for a vehicle comprising: a rotor having a field coil; a stator having a stator winding disposed around said rotor to provide ac power in cooperation with said rotor; a rectifying unit having a pair of diode cooling fins that has an accommodation space at a peripheral portion thereof; a brush unit having brushes for supplying field current to the field coil, said brush unit being disposed in said accommodation space near a rotation axis of said rotor, a voltage regulator for controlling output voltage of the ac power, said voltage regulator having a regulator circuit section and a heat sink that is disposed in said accommodation space radially outside of said brush unit at a space from the same; a housing for covering said rotor, stator, rectifying unit, brush unit and voltage regulator, said housing having an air intake window over said heat sink; a centrifugal cooling fan fixed to a side of said rotor near said rectifying unit to take in cooling air from said air intake window into an inside portion of said cooling fan; and wherein said heat sink has a plurality of axially projecting cooling fins that extends in a circumferential direction of said rotor so as to form a plurality of cooling air passages guiding the cooling air to flow along the circumferentially opposite surfaces of said voltage regulator to the accommodation space, thereby detouring the brush unit, wherein said heat sink has a generally rectangular surface from which said cooling fins project in the axial direction of said rotor, and wherein the rectangular surface of said heat sink has a radial length and a circumferential length that is shorter than the radial length to provide a maximum space for introducing the cooling air in the accommodation space.