An automotive alternator according to the present invention includes: a shaft having an end portion rotatably supported by a rear bearing housed inside a rear bearing housing portion of a rear bracket; a rectifier for converting an alternating current into a direct current; and a first centrifugal fan for cooling a rotor, a stator, and the rectifier by sucking in external air through a suction inlet in the bracket when the rotor rotates, the rectifier has a positive-side heat sink for cooling a plurality of positive-side diodes, the suction inlet is formed in a vicinity of the rear bearing housing portion, and a plurality of rear bearing cooling fins extending in a direction perpendicular to the shaft are formed on a side of the suction inlet near the rear bearing housing portion.

A small-diameter fin and a large-diameter fin, each extending in a direction normal to an axial direction of a rotor, are disposed at both sides of a terminal base so as to be overlapped in the axial direction of the rotor. The small-diameter fin is disposed far from the rotor compared with the large-diameter fin. The small-diameter fin is provided with a plurality of independent ribs each protruding in the axial direction of the rotor and extending in a radial direction of the rotor from or along an opening periphery of the receiving hole of the rectifying element.

A multi-phase alternating-current rotational electric machine wherein semiconductor switching devices are electrically insulated from heat sinks, and the heat sinks are grounded to the housing and thermally separated in each phase.

A vehicle AC generator includes a rotor, a stator, a frame supporting the rotor and the stator, a rear cover having an air intake window, a rectifying unit including a pair of cooling fins and a plurality rectifier elements, a brush unit including a pair of brushes and a brush-holder, a connector case having a terminal for transmitting and receiving electric signals and an IC regulator. The pair of cooling fins has a common cutout section forming an accommodation space between the frame and rear cover, and the connector case is disposed in the accommodation space so as to form a cooling air passage connecting the air intake window around the connector case. The IC regulator is disposed in the cooling air passage to face the rear cover so that the heatsink is disposed opposite the air intake window. Therefore, the IC regulator is cooled effectively and direct heat radiation on the IC regulator from the cooling fins and the brush holder is prevented.

The slip ring end (SRE) frame is an SRE frame of popular small dimension designed to allow available larger rectifier assemblies having larger heat sinks to be fitted into the SRE frame, thus providing increased heat dissipation capability. Two flattened frame mounting bore wells are provided in an inner cylindrical side wall of the SRE so that larger rectifier assemblies of choice having increased current carrying capability can fit inside the SRE frame. Specially configured rectifier heat sink mounting holes are provided so that the larger rectifier assemblies may be properly and securely mounted in the SRE frame. Additionally, the small SRE frame features strategically placed ventilation apertures of larger dimension to permit greater air flow through the device, thus producing cooler alternator running temperatures and providing higher durability.