Axial flow fan

摘要

An axial flow fan is disclosed. The axial flow fan comprises a hub, a plurality of blades extending radially outwardly from the hub, and an outer band surrounding peripheral ends of the blades. The median sweep angle of each blade increases gradually from 0 DEG along the outward radial direction. The leading sweep angle of each blade starts from an angle less than 0 DEG , increases gradually and terminates at an angle more than 40 DEG . The trailing sweep angle of each blade increases along the outward radial direction after it decreases from an angle more than 0 DEG along the outward radial direction. The chord length of each blade gradually increases along the outward radial direction. The pitch angle of each blade gradually decreases along the outward radial direction. <IMAGE>