Patent ID: 8866352

Claim:
An alternator for a vehicle comprising: a frame; a rotor retained by the frame; a stator which is so retained by the frame as to face the rotor, the stator working to produce ac voltage along with the rotor; a rectifier retained by the frame, the rectifier including rectifying devices to rectify the ac voltage into dc voltage; a heat dissipator which is disposed in the rectifier and has a first and a second surface opposed to each other through a given thickness, the heat dissipator working to establish an electrical communication between the rectifying devices and cool the rectifying devices; a cooling air generator which generates a flow of cooling air toward the rotor through the heat dissipator in the rectifier; and a plurality of sub-fins provided on the heat dissipator, each of the sub-fins being defined by a combination of a protrusion formed on the first surface of the heat dissipator and a recess formed in the second surface of the heat dissipator in coincidence with the protrusion in a direction of the given thickness; wherein a width of the recesses is greater than a width of the protrusions.