Patent ID: 7629720

Claim:
A vehicle alternator comprising: a frame surrounding a stator, having a stator coil formed in multi-phase windings, and a rotor rotatably disposed in an area inside the stator; a bowl-shaped end cover, made of resin, which is mounted on an end face of the frame to cover the same for defining an electric component-part compartment; a rectifier unit fixedly mounted on the end face of the frame and accommodated in the electric component-part compartment; and stator leads extending through the frame from the stator coil of the stator into the electric component-part compartment; the rectifier unit including: a positive-side cooling fin to which cathode electrodes of upper arm-side rectifying elements and an output terminal are fixed; a negative-side cooling fin to which anode electrodes of lower arm-side rectifying elements are fixed; and a terminal block embedded with A.C. conductive segments for respective phases each providing electrical connection between a diode lead acting as the anode electrode of the upper arm-side rectifying element and a diode lead acting as the cathode electrode of the lower arm-side rectifying element for each phase, the terminal block including a resin board formed in a horseshoe-shape; wherein: the end cover includes a base wall portion, made of resin and mounted on the end face of the rear frame in face-to-face relation thereto, and a plurality of protective partitioned compartments, integrally formed with the base wall portion at circumferentially spaced positions for the multi-phase windings, respectively, which axially protrude from the base wall portion toward the frame and each of which has both radially outward ends contiguous with an inner periphery of a circumferential wall portion of the base wall portion; each of the protective partitioned compartments surrounds at least one circumference of a connecting portion between an exposed end portion of each of the A.C. conductive segments and the diode lead and a connecting portion between the exposed end portion of each of the A.C. conductive segments and the stator lead and each of the protective partitioned compartments encompasses a pair of the lower arm-side rectifying elements for each phase; and the positive-side cooling fin and the negative-side cooling fin have horseshoe-shapes, respectively, with the negative-side cooling fin begin larger in diameter than the positive-side cooling fin.