Alternating-current generator for vehicles and heat sink incorporated therein

An automotive alternator comprising:

• a rotor housed inside a case and supported so as to rotate freely by means of a rotor shaft;
• a stator disposed inside said case so as to surround the outer circumference of said rotor;
• and
• a rectifier provided with a positive-side and a negative-side heat sinks supporting positive-side and negative-side unidirectional conducting elements, respectively, for rectifying alternating current generated by said rotor,
• wherein said both heat sinks are composed of flat bases having planar horseshoe shapes with different inside diameters from each other, and are disposed such that the planes of each of horseshoe shapes lie generally on a same plane perpendicular to the axis of the shaft and said both bases overlap radially,
• wherein the positive-side and negative-side unidirectional conducting elements are supported on one surface of their respective bases,
• and wherein said heat sink disposed radially inside is a die cast provided with:
• a plurality of fins disposed on the other surface of said base at a radial pattern at even angular pitch in the circumferential direction of said base, each rising perpendicularly from the other surface of said base, the projecting height (H) of said fins from said base being five or more times the thickness (T) of said fins, and said plurality of fins being formed such that the thickness (T), height (H), and pitch (P) of said fins at the inner circumferential end satisfy expressions
• T≦1 mm and 0.35≦T/P≦0.6.