Centrifugal fan

Abstract

A centrifugal fan includes a housing including an air collecting portion, a first frame and a second frame. The air collecting portion has an air outlet defined in one end thereof. The first and second frames are located at two opposite sides of an opposite end of the air collecting portion. The first and second frames each define a receiving space therein for rotatably receiving an impeller. The first and second frames each further define a vent hole therein. The receiving spaces of the first and second frames communicate with the inner space of the air collecting portion via the vent holes thereof. Airflow generated by the two impellers travels to the inner space of the air collecting portion through the vent holes of the first and second frames, and exits the centrifugal fan through the air outlet of the air collecting portion.

1 . A centrifugal fan comprising:
 a housing comprising an air collecting portion, the air collecting portion having an air outlet defined in one end thereof;   a first frame and a second frame adjacent two opposite lateral sides of an opposite end of the air collecting portion, respectively, the first frame defining a first receiving space and a first vent hole therein, the second frame defining a second receiving space and a second vent hole therein, the receiving spaces of the first frame and the second frame communicating with an inner space of the air collecting portion via the first vent hole and the second vent hole, respectively; and   a first impeller rotatably received in the first receiving space and a second impeller rotatably received in the second receiving space;   wherein airflow generated by the first impeller is guided to the inner space of the air collecting portion via the first vent hole, airflow generated by the second impeller is guided to the inner space of the air collecting portion via the second vent hole, and resulting airflow at the air collecting portion is expelled out of the centrifugal fan through the air outlet of the air collecting portion.   
     
     
         2 . The centrifugal fan of  claim 1 , wherein the air collecting portion comprises a bottom plate, a top plate and two guide plates connected between the bottom plate and the top plate. 
     
     
         3 . The centrifugal fan of  claim 2 , wherein the two guide plates are parallel to each other, and a cross section of the air collecting portion taken along a plane spanning from the top plate to the bottom plate is rectangular. 
     
     
         4 . The centrifugal fan of  claim 3 , wherein each of the first frame and the second frame comprises a supporting plate, a cover plate, and a volute side plate connecting between the supporting plate and the cover plate, the first vent hole is defined in the side plate of the first frame, the second vent hole is defined in the side plate of the second frame, and the cover plates of the first frame and the second frame each define an air inlet therein. 
     
     
         5 . The centrifugal fan of  claim 4 , wherein a rear end of the side plate of the first frame connects with a rear end of the side plate of the second frame to form a connecting portion between the first and second impellers, and front ends of the side plates of the first frame and the second frame respectively connect with rear ends of the two guide plates of the air collecting portion. 
     
     
         6 . The centrifugal fan of  claim 5 , wherein the connecting portion is outside the air collecting portion and faces the center of the air collecting portion. 
     
     
         7 . The centrifugal fan of  claim 1 , wherein the first frame and the second frame are symmetrically disposed at the two opposite lateral sides of the opposite end of the air collecting portion. 
     
     
         8 . The centrifugal fan of  claim 1 , wherein the first frame and the second frame are arranged at the two opposite sides of the opposite end of the air collecting portion in an asymmetrical manner, with the first frame being closer to the air outlet of the air collecting portion than the second frame. 
     
     
         9 . The centrifugal fan of  claim 1 , wherein an area of the air outlet is less than a total area of the first vent hole and the second vent hole. 
     
     
         10 . The centrifugal fan of  claim 1 , wherein the first and second impellers rotate in opposite directions.