Patent ID: 7067947

Claim:
An alternator for use in an automotive vehicle, the alternator comprising: a housing including a front frame and a rear frame; a cylindrical stator including an armature coil, the cylindrical stator being contained in the housing; a rotor rotatably disposed inside the cylindrical stator and supported in the housing; a rectifier mounted on the rear frame; a rear cover covering the rectifier, the rear cover being fixed to the housing; and a cooling fan for introducing cooling air into the housing through air inlets formed on a rear surface of the rear frame for cooling the rectifier, the cooling fan being connected to the rotor, wherein: the rectifier includes a minus heatsink plate on which minus rectifier elements are mounted and a plus heatsink plate on which plus rectifier elements are mounted, the minus heatsink plate being disposed to face the rear surface of the rear frame forming an air passage therebetween, the plus heatsink plate being disposed to face the rear cover, the minus heatsink plate and the plus heatsink plate forming a two-story structure in an axial direction; a lead terminal led out of each minus rectifier element extends in the axial direction of the rotor toward the rear cover; the minus heatsink plate includes cooling fins extending in the axial direction and forming radial air passages between the cooling fins; and the rear cover includes a plurality of radial openings that are open in a radial direction of the rotor and positioned radially outside of the cooling fins, so that the cooling air is introduced from the radial openings upon rotation of the cooling fan and flows through the radial air passages between the cooling fins and through the air passage between the minus heatsink plate and the rear surface of the rear frame.