AC Generator with low noise claw tooth rotor

Claim 1

In an AC generator for a vehicle comprising an armature iron core, three-phase armature windings wound on said armature iron core and a rotor having a pair of finger magnetic poles in the circumference thereof, which is formed with a plurality of claw-shaped pole pieces to be energized to opposite polarities and disposed to oppose tooth portions of said armature iron core with a small gap therebetween, the improvement wherein: said claw-shaped pole pieces are deviated relative to said opposed tooth portions, thereby to cancel torque variation generated between said claw-shaped pole pieces and said opposed tooth portions and to greatly decrease magnetic sound, the deviated angle (Δθ) of each of said deviated claw-shaped pole pieces relative to said opposed tooth portions in the state where at least one claw-shaped pole piece and at least one tooth portion are positioned at the same angular position with each other being expressed by the equation Δθ=(θ/P)×n, wherein θ is one slot pitch angle, P is the number of at least two pole pieces to be used for cancelling torque variation and n is a constant of all of the integral numbers from 1 to P-1.