Patent ID: 7605502

Claim:
An automotive alternator comprising: a rotor having a rotary shaft and working to create a rotating magnetic field; a stator working to generate an AC power in the rotating magnetic field created by the rotor; a frame supporting the rotor and the stator; and a rectifier including: a plurality of rectifying elements that are electrically connected to the stator to rectify the AC power generated by the stator to a DC power, and a heat sink including: a plurality of fitting holes, wherein one of the rectifying elements is fitted in each of the plurality of fitting holes, a major surface on which the fitting holes open, and a plurality of substantially annular ribs, wherein each of the ribs is formed on the major surface of the heat sink around a corresponding one of the plurality of fitting holes, each of the ribs including: a first portion, and a second portion, wherein: the first portion lies in an area on the major surface where a minimum distance between an inner edge of the heat sink defining the corresponding one of the plurality of fitting holes and an outer edge of the heat sink defining an outline of the heat sink is smaller, the second portion lies in an area on the major surface where a minimum distance between the inner and outer edges is larger, and the first portion having a greater protruding height from the major surface of the heat sink than the second portion so as to enhance a strength of the heat sink.