Rotary electric machine

Abstract

A rotary electric machine includes a frame; a stator whose stator-slot number Ns is 12; a rotor whose rotor-pole number Np is 8, the rotor being disposed inside the stator. The frame has a frame thickness T(θ) at mechanical angle θ, with respect to a reference line that connects the inner circumferential center of the frame with an arbitrary point, other than the center, around the center that is circularly expanded in a Fourier series. The difference between the stator-slot number Ns and the rotor-pole number Np is k (=|Ns−Np|). Stress-relieving spaces and are located in portions of the frame in an arrangement that does not have 90-degree mechanical angle rotational symmetry, in such a way that the sum P of inclusion ratios for the k-th component Tk and the Np-th component TNp, which are the Fourier series expansion coefficients for the frame thickness T(θ) expressed by equation (2) P = ( T k + T N ⁢ ⁢ p ) / ∑ n = 0 ∞ ⁢ T n × 100 ⁡ [ % ] , ( 2 ) is less than 12%. According to this configuration, mechanical strength of the frame and its producibility are maintained, and cogging torque caused by magnetic-circuit distortion in an iron core generated due to the frame shape is also reduced.

Dependencies are inferred from the claim text.