Abstract: The invention relates to the blades of a fan wheel. The invention particularly relates to a hollow profiled blade for a fan wheel. A hollow profiled blade according to the invention for a fan wheel is made from a planar semi-finished product and has a leading edge and a trailing edge as well as a compression side and a suction side. A hollow area is formed in the interior of the hollow profiled blade whereby the part of the planar semi-finished product forming the one side of the hollow profiled blade extends over the part of the planar semi-finished product forming the other side of the hollow profiled blade.

Abstract: An impeller has an inlet and outlet. A bottom disc has an external diameter. A top disc concentric to the bottom disc at an axial distance therefrom has a suction opening for the inlet. A plurality of forward-curved blades are arranged between the bottom disc and the top disc. A flow channel has an inner inlet side and an outer outlet side formed between adjacent blades. The channel is curved convexly viewed in the running direction of the impeller. The external diameter of the bottom disc is at least 20% greater than the internal diameter of the suction opening. The top disc forms a guiding surface and an angle is formed between a tangent on the guiding surface at the inlet to the suction opening and a tangent on the guiding surface at the outlet from the flow channel on the air outlet side is at least 30°.