Abstract: A thin metal sheet is laminated to form in advance a plurality of core units (of a circular cylinder shape) having the thickness of 1/N (N is a natural number of more than 2) of a predetermined thickness in the laminating direction and this plurality of core units is laminated again for securing so that the whole stator does not cause any mode of oscillation in the diametric direction.

Abstract: A stator core which joint vibration in a radial direction and can suppress a vibration mode and a production process therefor. The stator core has a plurality of welded portions formed on the exterior or interior side of the cylinder in the same direction diagonal to the lamination direction of the metal sheet from the upper end to the lower end of the cylinder.

Abstract: A vehicle alternator includes a case having a pair of brackets placed back-to-back, in which ribs are disposed, which define ventilation windows (29; 74) in a bracket body. The ribs serve as heat passage members (54, 60; 73), which have higher thermal conductivity than the bracket body and are partially embedded in the bracket body. Therefore, heat resistance in the heat transfer passage between the stator and the ventilation windows is reduced, and heat generated by the stator is expelled efficiently from the ventilation windows to the outside air, and the temperature of the stator can be reduced.