A rotor and a stator are contained in a housing composed of front and rear frames, and a rectifier is mounted on the rear frame and covered with a rear cover having axial and radial openings. A minus heatsink plate having cooling fins extending in the axial direction is disposed to face the radial openings, forming radial air passages, and another air passage is formed between the minus heatsink plate and the rear frame. Cooling air introduced from the radial openings flows through the cooling fins and through the passage between the minus heatsink plate and the rear frame. Thus, efficiency for cooling the rectifier is enhanced.
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.
In a vehicle AC generator having a housing that covers a voltage regulator equipped with external cooling fins, and a cooling fan which rotates with the generator rotor to draw external air through the interior of the housing, an aperture is formed in the housing at a position corresponding to the voltage regulator, and outer end portions of the cooling fins protrude through the aperture to positions beyond the outer circumference of the housing, to dissipate heat from the vehicle-mounted regulator during low-speed operation of the generator, when the rate of air flow through the aperture is low.
