Centrifugal fan with a multistage impeller

Abstract

A centrifugal fan with a multistage impeller includes a hub and a multistage impeller having at least two stages of blade assemblies. The hub has a top section and a circumferential section extending from the top section. At least one extension section outward extends from the circumferential section. The multistage impeller is connected with one end of the extension section. The multistage impeller includes a first-stage blade assembly and a second-stage blade assembly. The second-stage blade assembly has a diameter larger than that of the first-stage blade assembly. The centrifugal fan can be installed in an application environment with limited space without being interfered with by peripheral parts. Also, the centrifugal fan is able to provide an optimal flow and wind pressure at the same rotational speed to lower the load on the motor and reduce the noise.

1 . A centrifugal fan with a multistage impeller, the centrifugal fan comprising:
 a hub having a top section and a circumferential section extending from the top section, at least one extension section outward extending from the circumferential section in a direction away from the top section; and   a multistage impeller having at least two stages of blade assemblies, the multistage impeller including a first-stage blade assembly and a second-stage blade assembly, each of the first-stage blade assembly and the second-stage blade assembly including multiple blades annularly arranged around the hub, the first-stage blade assembly being connected with one end of the extension section, the second-stage blade assembly being positioned on one side of the first-stage blade assembly, the second-stage blade assembly having a diameter larger than that of the first-stage blade assembly.   
     
     
         2 . The centrifugal fan with the multistage impeller as claimed in  claim 1 , wherein the centrifugal fan is mounted in a multistage fan housing. 
     
     
         3 . The centrifugal fan with the multistage impeller as claimed in  claim 1 , wherein a first connection section is connected between each two adjacent 
     
     
         4 . The centrifugal fan with the multistage impeller as claimed in  claim 1 , wherein a second connection section is connected between each two adjacent blades of the second-stage blade assembly, the blades of the second-stage blade assembly being annularly connected with each other by means of the second connection sections to form the second-stage blade assembly in an annular form. 
     
     
         5 . The centrifugal fan with the multistage impeller as claimed in  claim 1 , wherein a first-stage annular plate is positioned between the first-stage blade assembly and the second-stage blade assembly, the second-stage blade assembly being arranged on one side of the first-stage blade assembly via the first-stage annular plate. 
     
     
         6 . The centrifugal fan with the multistage impeller as claimed in  claim 5 , wherein a second-stage annular plate is positioned on the other side of the second-stage blade assembly, which side is distal from the first-stage blade assembly, a third-stage blade assembly being arranged on the other side of the second-stage annular plate. 
     
     
         7 . The centrifugal fan with the multistage impeller as claimed in  claim 6 , wherein the second-stage annular plate has a diameter larger than that of the first-stage annular plate. 
     
     
         8 . The centrifugal fan with the multistage impeller as claimed in  claim 6 , wherein the third-stage blade assembly includes multiple blades annularly arranged around the hub, a third connection section being connected between each two adjacent blades of the third-stage blade assembly, the blades of the third-stage blade assembly being annularly connected with each other by means of the third connection sections to form the third-stage blade assembly in an annular form. 
     
     
         9 . The centrifugal fan with the multistage impeller as claimed in  claim 8 , wherein the third-stage blade assembly has a diameter larger than that of the second-stage blade assembly.