Patent ID: 7449806

Claim:
A brushless alternator comprising: a stationary field winding to create a magnetic flux; a rotor that has a rotary shaft and creates a rotating magnetic field with the magnetic flux created by the field winding; a bearing rotatably supporting an end portion of the rotary shaft; a stator to generate an AC power in the rotating magnetic field created by the rotor; a protective cover; and a rectifier covered by the protective cover, the rectifier including a plurality of main rectifying elements, a heat sink, and a plurality of auxiliary rectifying elements, the main rectifying elements to rectify the AC power generated by the stator to a first DC power that is to be output from the alternator to external, the heat sink having the main rectifying elements provided thereon to dissipate heat generated by operation of the main rectifying elements, the auxiliary rectifying elements to rectify the AC power generated by the stator to a second DC power to energize the field winding, the auxiliary rectifying elements being arranged in an axial space, the axial space located between the bearing and the protective cover and at least partially within a diameter of the bearing, and kept away from the heat sink, so as to minimize heat transfer from the heat sink to the auxiliary rectifying elements, wherein the protective cover has an air intake hole formed therethrough which is in alignment with one of the auxiliary rectifying elements in an axial direction of the rotary shaft.