SCAVENGER FAN WITH AUTOMATIC OPENING AND CLOSING BLADES

The utility model relates to a domestic electric appliance, in particular to a ventilation fan with blades capable of opening and closing automatically, comprising a frame, an electric motor, a blade frame, blades, a guide wheel, a centrifugal balancing block, a torsion spring, a fastening cover, etc. The utility model is characterized in that a shutter of a normal angle ventilation fan is omitted; under the action when the guide wheel, the centrifugal balancing block and the torsion spring rotate with the electric motor, the blades can automatically spread out or be folded with the blades superimposed on each other, and simultaneously, the air passage is opened or closed. The utility model has the advantages of simple structure, reliable work, prevention of flow velocity attrition, strong wind power, and the efficiency of the ventilation fan is raised. When the ventilation fan doesn't work, the unclean and hot outdoor air can be effectively prevented from entering rooms.