Impeller for an axial-flow type fan

An impeller of an axial-flow type fan, for appliances for drying and dressing hair comprising hub structure having a cylindrical outer surface and an axis of rotation, a plurality of blades integrally formed with said circumferential outer surface of said hub structure and arranged on said hub structure in a rotationally symmetrical manner, each said blade having an inner edge at said outer surface of said hub structure, a leading edge, a trailing edge and an outer edge, each said blade being offset relative to an outer edge, each said blade being offset relative to an adjacent blade by an offset angle of rotation, in which adjacent blades completely overlap each other in the area of said leading edge of each blade and said trailing edge of the adjacent blade over the radial extent of said blades, in which an opening angle formed by a projection of said leading edge and said trailing edge of each blade on a plane normal to said axis of rotation satisfies the condition that said opening angle is smaller than or equal to said offset angle of rotation, the profile formed by said outer edge of each said blade has a curvature of constant sign, and all cross-sections of said blades normal to said axis of rotation form straight lines whose extensions intersect a respective imaginary line associated with a respective one of said blades.