Centrifugal fan

Abstract

A centrifugal fan includes a spiral housing, a driving mechanism and multiple internally mounted impellers. The driving mechanism and the centrifugal impeller, rotated by the driving mechanism, are installed in the spiral housing. A spiral flow channel is defined between the centrifugal impeller and the spiral housing. When the centrifugal impeller rotates, airflow is sucked axially into the spiral housing through an inlet opening and moves along each blade of the centrifugal impeller into the spiral flow channel. The centrifugal impeller includes a hub and multiple blades. Each blade is secured to the hub at one end and has at least one vertical convex strip or vertical concave strip at an opposite end, wherein the vertical convex strip or vertical concave strip on each of blade disturbs the airflow across thereof and reduces narrow-band noise.

1 . A centrifugal fan, comprising:
 a housing, having an inlet opening;   a driving mechanism mounted in the housing;   a centrifugal impeller, driven by the driving mechanism, a flow channel is defined between the centrifugal impeller and the housing, the centrifugal impeller comprising:
 a hub; and 
 multiple blades, each of the multiple blades secured to the hub at one end and having at least one vertical convex strip at an opposite end, when the centrifugal impeller rotates, airflow is sucked axially into the housing through the inlet opening, and moves along each of the multiple blades, wherein the vertical convex strip at each of the multiple blades disturbs the airflow across thereof and reduces narrow-band noises. 
   
   
   
       2 . The centrifugal fan of  claim 1 , wherein the driving mechanism is a motor. 
   
   
       3 . A centrifugal fan, comprising:
 a housing, having an inlet opening;   a driving mechanism, mounted in the housing;   a centrifugal impeller, driven by the driving mechanism, a flow channel is defined between the centrifugal impeller and the housing, the centrifugal impeller comprising:
 a hub; and 
 multiple blades, each of the multiple blades secured to the hub at one end and having at least one vertical concave strip at an opposite end, when the centrifugal impeller rotates, airflow is sucked axially into the housing through the inlet opening, and moves along each of the multiple blades, wherein the vertical concave strip at each of the multiple blades disturbs the airflow across thereof and reduces narrow-band noise. 
   
   
   
       4 . The centrifugal fan of  claim 3 , wherein the driving mechanism is a motor.