Ventilating device for rotary electrical machine

aabbababababababThe ventilating device fixed on a rotor of a rotary electrical machine, comprises a first fan having a radial plate portion, at least one second fan having a radial plate portion, and means for fastening the two fans, each fan having, at the outer peripheiy of its radial plate portion, first branches and second branches which extend radially outwards, at least some of the branches having a blade, while at least one first branch and at least one second branch includes a first and a second mutual overlapping portion to define an overlap zone (Z), the said fastening means being at least partly arranged at the level of the overlap zone.