Patent ID: 7602095

Claim:
A tandem alternator comprising: a rotary shaft; a first field and a second field which are arranged in tandem on the rotary shaft; and a first and a second armature which are arranged in tandem in an axial direction of the rotary shaft, the first armature being provided on an outer periphery of the first field to constitute, together with the first field, a first electric power generation unit, the second armature being provided on an outer periphery of the second field to constitute, together with the second field, a second electric power generation unit, wherein the first and second fields are arranged to abut each other in the axial direction of the rotary shaft, the first and second fields are configured to respectively create a first and a second magnetomotive force whose directions are opposite to each other, the first field includes a first lundell-type field core mounted on the rotary shaft and a first field winding wound around the first field core, and the second field includes a second lundell-type field core mounted on the rotary shaft and a second field winding wound around the second field core, each of the first and second field cores includes a pair of inside and outside disc portions that are spaced in the axial direction of the rotary shaft with a corresponding one of the first and second field windings interposed therebetween, the inside disc portion of the first field core is integrally formed with the inside disc portion of the second field core, the first and second field cores include the same number of claw portions extending axially outward from the respective inside disc portions, the claw portions extending from the inside disc portion of the first field core are alternately arranged in a circumferential direction of the rotary shaft with the claw portions extending from the inside disc portion of the second field core, and a difference in electrical angle between each circumferentially adjacent pair of one of the claw portions extending from the inside disc portion of the first field core and one of the claw portions extending from the inside disc portion of the second field core is equal to 180 electrical degrees.