Patent ID: 8029237

Claim:
A centrifugal fan, comprising: a housing comprising at least one air inlet, a first sidewall extending from an inner margin of the air inlet to create an air-gathering chamber in the housing and having a flange extending from the first side wall toward an inside of the air-gathering chamber directly to define an entrance to the air-gathering chamber, and an air outlet connected to the air-gathering chamber, wherein the first sidewall and the flange are integrally formed as a single piece; at least one blade structure disposed in the housing, comprising: a hub provided with a protrusion extending radially to the entrance of the air-gathering chamber; a first group of rotor blades disposed near the air inlet of the housing; and a second group of rotor blades facing the entrance of the air-gathering chamber and arranged outwardly and radially, wherein the first group of rotor blades and the second group of rotor blades are circumferentially disposed around the hub and extended along a direction from the air inlet to the entrance of the air-gathering chamber; and a driving device disposed in the hub without protruding out of the hub to rotate the rotor blades.