Centrifugal fan and impeller thereof

Abstract

A centrifugal fan includes a housing defining an inner space therein and an impeller rotatably received in the inner space of the housing. The impeller includes a hub, a blade ring surrounding the hub, a plurality of first blades extending from the hub to the blade ring, and a plurality of second blades extending from the blade ring. Each first blade includes an inner portion between the hub and the blade ring, and an outer portion extending from the blade ring. The second blades and the outer portions of the first blades are arranged in alternating fashion along a circumferential direction of the blade ring. In each pair of an outer portion and an adjacent second blade, the outer portion and the second blade are curved outwards away from each other toward substantially opposite directions.

1 . A centrifugal fan, comprising:
 a housing defining an inner space, an air inlet and an air outlet therein, the inner space communicating with the air inlet and air outlet, the air inlet being substantially perpendicular to the air outlet; and   an impeller rotatably received in the housing, the impeller comprising a hub, a blade ring surrounding the hub, a plurality of first blades extending from the hub to the blade ring, and a plurality of second blades on the blade ring, outer portions of the first blades on the blade ring and the second blades being curved such that each second blade and a corresponding adjacent outer portion of the first blade are oriented generally symmetrically opposite each other.   
     
     
         2 . The centrifugal fan of  claim 1 , wherein the first blades and the second blades are arranged in alternating fashion along a circumferential direction of the blade ring. 
     
     
         3 . The centrifugal fan of  claim 2 , wherein the outer portions of the first blades on the blade ring are arc-shaped and the second blades are arc-shaped, each second blade and the corresponding adjacent outer portion of the first blade forming a profile of a pair of parentheses. 
     
     
         4 . The centrifugal fan of  claim 1 , wherein the outer portions of the first blades curve outwards generally toward a rotation direction of the centrifugal fan, and the second blades curve outwards generally away from the rotation direction of the centrifugal fan. 
     
     
         5 . The centrifugal fan of  claim 4 , wherein each first blade further comprises an inner portion extending from the hub to the outer portion. 
     
     
         6 . The centrifugal fan of  claim 5 , wherein the inner portion of the first blade extends outwards generally away from the rotation direction of the centrifugal fan. 
     
     
         7 . The centrifugal fan of  claim 5 , wherein the inner portion of the first blade is straight. 
     
     
         8 . The centrifugal fan of  claim 1 , wherein the housing comprises two covers arranged parallel to each other, and a sidewall interconnecting the two covers, the air inlet being defined in the two covers, the air outlet being defined in the sidewall, and wherein the blade ring, the second blades, and the outer portions of the first blades are aligned with the covers, and other portions of the first blades and the hub are aligned with the air inlet. 
     
     
         9 . The centrifugal fan of  claim 1 , wherein the hub comprises a circular wall and an annular wall extending perpendicularly from a periphery of the circular wall, an end of the annular wall farthest from the circular wall being substantially coplanar with the blade ring. 
     
     
         10 . An impeller, comprising:
 a hub comprising a circular wall and an annular wall extending from a periphery of the circular wall;   a blade ring surrounding and spaced from the annular wall of the hub;   a plurality of first blades extending outwards from the hub to the blade ring, each first blade comprising an inner portion between the annular wall of the hub and the blade ring, and an outer portion extending from the blade ring; and   a plurality of second blades extending from the blade ring, the second blades and the outer portions of the first blades being arranged in alternating fashion along a circumferential direction of the blade ring, wherein in each pair of an outer portion and an adjacent second blade, the outer portion and the second blade are curved outwards away from each other toward substantially opposite directions.   
     
     
         11 . The impeller of  claim 10 , wherein the outer portions of the first blades and the second blades are arc-shaped, and the each pair of an outer portion and an adjacent second blade form a profile of a pair of parentheses. 
     
     
         12 . The impeller of  claim 10 , wherein the inner portion of the first blade is straight. 
     
     
         13 . The impeller of  claim 10 , wherein the blade ring is substantially coplanar with an end of the annular wall farthest from the circular wall. 
     
     
         14 . The impeller of  claim 10 , wherein the second blades and the outer portions of the first blades extend perpendicularly from the same side of the blade ring.