Robert Boschgmbh

Robert W Stairs

William M Stevens

David S Greeley

The present invention provides an axial fan including a hub adapted for rotation about a central axis and a plurality of blades extending radially outwardly from the hub and arranged about the central axis. Each of the blades includes a root, a tip, a leading edge between the root and the tip, and a trailing edge between the root and the tip. Each of the blades defines a blade radius between the blade tips and the central axis. Each of the blades defines a decreasing skew angle within the outer 20% of the blade radius. The ratio of blade pitch to average blade pitch increases from a lowest value to a highest value within the outer 20% of the blade radius. The highest value is about 30% to about 75% greater than the lowest value.

Axial fan assembly

The present invention provides an axial fan assembly including a motor having an output shaft rotatable about a central axis and a shroud coupled to the motor. The shroud includes a substantially annular outlet bell centered on the central axis. The axial fan assembly also includes an axial fan having a hub coupled to the output shaft for rotation about the central axis, a plurality of blades extending radially outwardly from the hub and arranged about the central axis, a substantially circular band coupled to the tips of the blades, and a plurality of leakage stators positioned radially outwardly from the band and adjacent the outlet bell.

An efficient axial flow fan comprises a central hub, a plurality of blades, and a band, and is designed to operate in a shroud and induce flow through one or more heat exchangers&mdash;in an automotive engine cooling assembly, for example. The fan blades have a radial distribution of pitch ratio that provides high efficiency and low noise in the non-uniform flow field created by the heat exchanger(s) and shroud. The blade has either no sweep, or is swept backward (i.e. opposite the direction of rotation) in the region between the radial location r/R&equals;0.70 and the tip (r/R&equals;1.00). The blade pitch ratio increases from the radial location r/R&equals;0.85 to a radial location between r/R&equals;0.90 and r/R&equals;0.975, and then decreases to the blade tip.

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Westwood, MA, United States of America

Robert W Stairs