Abstract: A centrifugal fan includes a housing, a driving device, and a fan impeller. The housing has a hollow chamber which has a central axis. The driving device is located at the central axis of the hollow chamber. The fan impeller is disposed in the hollow chamber and includes a hub, several blades, and several fins. The hub is connected with the driving device. The blades are disposed around the hub. Each blade has a windward surface and a leeward surface. Each fin extends from the windward surface of one of the blades, outward by an arc surface from the windward surface starting from a location near the central axis, and further extends to the leeward surface of an adjacent blade.

Abstract: A centrifugal fan includes a centrifugal impeller, a first housing, a second housing, an annular guide ring and a driving device. The centrifugal impeller has a hub and blades connected to and disposed around the hub. The first housing and the second housing cooperatively define a hollow chamber and an air outlet. An air inlet is formed in a central section of the second housing. A first arc structure is located on an inner surface around the air inlet of the second housing. Support brackets respectively extend from an end close to a tongue of the second housing and an end away from the tongue of the second housing. The support brackets are perpendicular to the second housing. The annular guide ring has a second arc structure close to an outermost margin of inner surfaces of the blades. The driving device is used for rotating the centrifugal impeller.

Abstract: A centrifugal fan includes a housing, a driving device, and a fan impeller. The housing has a hollow chamber which has a central axis. The driving device is located at the central axis of the hollow chamber. The fan impeller is disposed in the hollow chamber and includes a hub, several blades, and several fins. The hub is connected with the driving device. The blades are disposed around the hub. Each blade has a windward surface and a leeward surface. Each fin extends from the windward surface of one of the blades, outward by an arc surface from the windward surface starting from a location near the central axis, and further extends to the leeward surface of an adjacent blade.

Abstract: A centrifugal fan includes a centrifugal impeller, a first housing, a second housing, an annular guide ring and a driving device. The centrifugal impeller has a hub and blades connected to and disposed around the hub. The first housing and the second housing cooperatively define a hollow chamber and an air outlet. An air inlet is formed in a central section of the second housing. A first arc structure is located on an inner surface around the air inlet of the second housing. Support brackets respectively extend from an end close to a tongue of the second housing and an end away from the tongue of the second housing. The support brackets are perpendicular to the second housing. The annular guide ring has a second arc structure close to an outermost margin of inner surfaces of the blades. The driving device is used for rotating the centrifugal impeller.