Patent ID: 6815849
Filing Date: 2004-11-09
Classification: H02K

Abstract:
A magneto generator comprising:a magnet rotor having a cup-shaped rotor yoke with a peripheral wall and a bottom wall and a permanent magnet mounted to an inner periphery of the peripheral wall of the rotor yoke; and an armature placed inside the magnet rotor, wherein the bottom wall of said rotor yoke is drilled at a portion closer to an outer periphery to provide a plurality of circumferential air vents in said peripheral wall, a hollow cooling air introducing portion is provided for each of the plurality of air vents in the bottom wall of said rotor yoke, each cooling air introducing portion is formed to protrude in an opposite direction to an opening in the peripheral wall of said rotor yoke and cover at least a part of a corresponding air vent, and a cooling air introducing passage is formed inside the cooling air introducing portion, an end of the cooling air introducing passage inside said cooling air introducing portion communicates with the inside of said rotor yoke through a corresponding air vent, the other end of the cooling air introducing passage inside said cooling air introducing portion opens forward in the rotational direction of said magnet rotor through an opening end provided in the cooling air introducing portion, said cooling air introducing portion has an outer side wall provided to extend in a sloping direction from near a corresponding air vent toward an outer peripheral portion of said rotor yoke and reach said opening end, and the opening end of said cooling air introducing portion is directed in a sloping direction toward an inner diameter of said rotor yoke with respect to the direction orthogonal to a reference plane including both a straight line between the center of the bottom wall of said rotor yoke and the center of a corresponding air vent, and a central axis of said rotor yoke.