Variable Pitch Axial Flow Fan Impeller

摘要

An impeller for a variable pitch axial flow fan having an actuator (25) arranged to rotate the blades (5) towards their maximum pitch angle, and in which the inherent blade tuning moment of the blades when the impeller is rotating provides the restoring force for moving the blades towards their minimum pitch angle, thus avoiding the need for blade counterweights and a heavy return spring.