Patent ID: 8133009

Claim:
An impeller device for centrifugal fans, comprising: a centre wheel; at least one side disc; fan blades, where the fan blades have a radially inner leading edge, a radially outer trailing edge, a first side end and a second side end; where the at least one side disc comprises first support-providing attachment devices having recesses adapted to receive the first side end of the blade and abut against parts of the trailing edge of first side end of the blade to provide support against centrifugal forces; where the centre wheel comprises second support-providing attachment devices having protrusions protruding an axial distance from the centre wheel and extending in the radial direction of the centre wheel, where the protrusions are shaped to conform with parts of a peripheral edge of the second end of the blade to provide support for the blade; where the first support-providing attachment devices and the second support-providing attachment devices prevent the blades from moving in a radial direction; and bolt attachment devices for detachably securing the fan blades to the centre wheel and to the at least one side disc; where the at least one side disc comprise a curved area, where the recesses are provided in the curved area of the at least one side disc.