Patent ID: 7122927

Claim:
An automotive alternator, comprising: a housing; a stator housed in the housing, the stator including a stator core and an armature winding wound on the stator core; a rotor rotatably supported in the housing and disposed inside the stator, the rotor including a rotor core and a field winding wound around the rotor core; and a cooling fan fixed to at least one axial end of the rotor core so as to rotate coaxially with the rotor, the cooling fan including a plurality of fan blades, wherein: the housing includes a plurality of cooling air intake windows formed in an axial end wall of the housing so that the windows face the cooling fan, each window being formed in a space between neighboring two spokes connecting an inner circular wall of the housing and an outer wall of the housing, the spokes connecting the inner circular wall of the housing to the outer wall of the housing extend straight in a radial direction, and a plurality of shroud surfaces, each formed at a radial outside of each window to have a substantially same total area common to all shroud surfaces, so that the shroud surfaces face an axial end of the fan blades; an area of each shroud surface facing the axial end of the fan blades gradually increases along a rotational direction of the cooling fan; and each shroud surface has an inner fringe defining a radial outer fringe of the window, the inner fringe curving continuously with an arcuate curvature along the rotational direction of the cooling fan, the arcuate curvature of the inner fringe of each shroud having a respective curvature center different from one another.