Patent ID: 7210907

Claim:
A centrifugal fan impeller ( 1 ) having an axis of rotation ( 6 ) and comprising one or more modules ( 2 ), comprising a mounting disc ( 4 ), at least one connecting ring ( 5 ) and a plurality of blades ( 3 ) extending between the mounting disc ( 4 ) and the connecting ring ( 5 ), the blades ( 3 ) being connected to the disc ( 4 ) and ring ( 5 ) at an angle (α) relative to the axis ( 6 ) of the impeller ( 1 ), the impeller being characterised in that the angle (α) at which the blades ( 3 ) are inclined is 10 degrees, in that the connecting ring ( 5 ) is positioned on an outer diameter in respect to the blades ( 3 ), whereby the inner part of the mould for producing the fan impeller ( 1 ) can be extracted axially from both sides of the fan impeller ( 1 ), in that the profile of each blade ( 3 ) at a root thereof is inclined at an angle (γl) ranging from 50 to 80 degrees, and in that the profile of each blade ( 3 ) at an end thereof is inclined at an angle (γ 2 ) ranging from 33 to 63 degrees, said angles (γ 1 , γ 2 ) at the root ( 7 ) and at the end ( 8 ) of the blade ( 3 ) being defined as the angles made by the profile of the blade ( 3 ), at the root and end of the blade respectively, with respect to an impeller radius (R 1 , R 2 ) passing through the leading edge (A) of the profile.