Radial fan impeller has rearwards curved blades which consist of at least two layers of material which is sheet metal, and blades are doubled by bending over around their leading edge

摘要

The radial fan impeller has rearwards curved blades (10) which consist of at least two layers of material. The material of the blades is sheet metal, and the blades are doubled by the bending over around their leading edge. The trailing edge (14) of each blade has a three-layered construction by the folding down of a folded edge over a middle layer in this place. The blades on their longitudinal edges have tongues (16) which passing through corresponding openings in the front and rear walls fix the blades in position on the front and rear walls.