Cooling fan impeller

摘要

An impeller of a centrifugal fan includes a hub and a plurality of blades arranged on and around the hub. Each of the blades includes a root portion and a tip portion. The tip portion of each of the blades has a concave surface and a convex surface in rear and front sides thereof respectively. In a rotational direction of the impeller, the tip portion of a rear blade protrudes towards a front blade.