Automotive alternator

1. An automotive alternator comprising:

a rotor that is fixed to a rotating shaft;

a case that rotatably supports said rotating shaft and that envelops said rotor;

a stator comprising:

a cylindrical stator core that is held by said case and that surrounds said rotor; and

a stator coil that is mounted to said stator core;

a rectifier comprising:

a positive-side heatsink that has a flat, arc-shaped positive-side base portion;

a positive-side rectifying element that is mounted to a front surface of said positive-side base portion;

a negative-side heatsink that has a flat, arc-shaped negative-side base portion; and

a negative-side rectifying element that is mounted to a front surface of said negative-side base portion,

said positive-side heat sink and said negative-side heat sink being disposed inside said case at a first end of said rotor so as to be separated axially such that said front surfaces of said positive-side base portion and said negative-side base portion face each other; and

a cooling fan that is fixed to a first end surface of said rotor,

said automotive alternator being characterized in that:

an air intake aperture is disposed through said case so as to face whichever heatsink of said positive-side heatsink and said negative-side heatsink is disposed farther away from said rotor, and an air discharge aperture is disposed through said case so as to be positioned radially outside said cooling fan;

a plurality of radiating fins are disposed so as to project from a rear surface of said base portion of whichever heatsink of said positive-side heatsink and said negative-side heatsink is disposed nearer to said rotor; and

said heatsink that is disposed nearer to said rotor is disposed such that said plurality of radiating fins are positioned radially outside said cooling fan, and a cooling airflow that flows out from said cooling fan passes through said plurality of radiating fins.

2. An automotive alternator according to claim 1 , wherein a coil end of said stator coil is disposed radially outside said cooling fan so as to face said plurality of radiating fins.

3. An automotive alternator according to claim 1 , wherein said plurality of radiating fins are arranged in a row circumferentially such that each of said radiating fins is parallel to a straight line that extends radially from a center of rotation of said rotor or is inclined forward in a direction of rotation relative to said straight line.

4. An automotive alternator according to claim 3 , wherein:

an inner circumferential angle of inclination of an inner circumferential end portion of said radiating fins relative to said straight line is greater than an outer circumferential angle of inclination of an outer circumferential end portion of said radiating fins relative to said straight line; and

said radiating fins are formed so as to have a curved shape in which an angle of inclination relative to said straight line gradually decreases from said inner circumferential angle of inclination to said outer circumferential angle of inclination.

5. An automotive alternator according to claim 3 , wherein an outer circumferential angle of inclination of an outer circumferential end portion of said radiating fins relative to said straight line is greater than or equal to an angle of inclination relative to said straight line of an air discharge rib that constitutes said air discharge aperture that is disposed through said case.

6. An automotive alternator according to claim 1 , wherein a corner portion of said radiating fins and an air discharge rib that constitutes said air discharge aperture that is disposed through said case is machined so as to have a tapered shape or a rounded shape.