| 摘要 |
PURPOSE:To prevent plastic deformation of a raceway surface loaded when balls pass through on and to make it possible to reduce vibration and to use in higher speed and under higher tension by forming an outer race of a bearing in pulley side with steel having retained austenite less than a fixed value. CONSTITUTION:A rotary shaft 15 of an armature (rotor) 18 is supported freely rotably to frames 10, 11, having a stator 12 of an AC generator for a vehicle, via a couple of bearings 13, 14. A pulley 20 is provided on the end part of the rotary shaft 15 projected to outside of the frames 10, 11,and the rotary shaft 15 is made to rotate by an engine via this pulley 20. Among inner and outer races of these bearings 13, 14, at least, the outer race of the bearing in the pulley 20 side is formed with steel having retained austenite less than 10%. As the result of this construction, a raceway loaded when balls pass through on does not make plastic deformation, so together with reduced vibration, rolling frictional force become reduced to suppress heat building up, so the bearing can be used in higher speed and under higher tension.
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