A motor-driven fan, particularly for a motor vehicle heat exchanger

A motor-driven fan (1) comprises an electric motor (2) including a rotor (4) and a stator (5) in which the rotor (4) comprises an essentially cup-shape cap (10; 13) which extends at least partly around the stator (5) and has a plurality of lateral exit openings (19) adjacent the bottom wall (13), and an impeller or fan (3) including a hollow hub (27) from which extends a plurality of main outer fan blades (28). This hub (27) has a front wall (27a) fixed to the back wall (13) of the cap (10) of the rotor (4) and a lateral skirt (27b) which surrounds the lateral wall (11) of the said cap (10) in a radially spaced relationship. The said hub (27) is further provided with inner ventilation blades (29) acting in operation to generate a cooling air stream which passes through the motor (2) along a path which, from the end of the motor opposite the hub (27) of the fan (3) and towards the bottom wall of the said cap (11) lies within the motor (4) and then through the exit apertures (19) of the cap (10) of the rotor (4) and extends within an air gap (30) defined between the cap (10) and the skirt (27b) of the hub (27) of the fan (3), and then flows out from the said hub (27) in the region downstream of the main ventilation blades (28).