US Patent 7594800 Ventilation assembly for wind turbine rotor hub

A ventilation assembly for a wind turbine rotor hub is provided, the ventilation assembly comprising a frame fixedly mountable to the rotor hub, the frame including at least one opening, and a cover for said at least one opening, the cover being mounted to said frame to be freely rotatable with respect to said frame, wherein the cover has at least one ventilation opening to allow the ingress and egress of air and has a shielding member for shielding the at least one ventilation opening against ingress of liquid running down the rotor hub.