Patent ID: 7758305

Claim:
A centrifugal fan, comprising: a wheel mount having a shaft rotatable about a shaft axis; an impeller having a plurality of fan blades, a wheel back and a wheel front, the wheel front being fixed attached to a front end of the fan blades and the wheel back being fixedly attached to a back end of the fan blades and mounting the impeller to the shaft for rotation about the shaft axis, each fan blade extending a length between the wheel front and the wheel back; an inlet bell having a wall defining a passageway for directing air to a front end of the impeller, the passageway having a first opening and a second opening downstream from and of a lesser dimension than the first opening, the wall having a turbulator for inducing turbulence in the air passing through the passageway such that air passing into the impeller is contacted by the fan blades along essentially the length of each blade; and wherein the turbulator is formed integrally with the inlet bell wall as at least one arcuate surface projecting toward or away from the passageway to a greater extent than an adjacent surface of the wall, and the arcuate surface is located between the first opening and an axial midpoint of the inlet bell.