Impeller of centrifugal fan

Abstract

An impeller of a centrifugal fan having a casing and a multi-blade impeller rotatably supported by a blade holding base in said casing, wherein when said impeller is rotated air is sucked from an air suction port formed on one side wall of said casing, and a centrifugal force is applied on said air, so that air of high pressure is taken out through an outlet formed on a portion of an outer peripheral surface of said casing. An inner peripheral surface of the impeller is formed of a conical surface having a large diameter at the suction port and a small diameter at the blade holding base. The small diameter at the blade holding base is in the range of 70 to 90% of the large diameter at the suction port. The diameter of the inner peripheral surface of the impeller is reduced linearly from a portion at the suction side to a portion at the blade holding base side.

What is claimed is:  
     
         1 . In an impeller of a centrifugal fan having a casing and a multi-blade impeller rotatably supported by a blade holding base in said casing, wherein when said impeller is rotated air is sucked from an air suction port formed on one side wall of said casing, and a centrifugal force is applied on said air, so that air of high pressure is taken out through an outlet formed on a portion of an outer peripheral surface of said casing, the improvement characterized in that an inner peripheral surface of the impeller is formed of a conical surface having a large diameter at the air suction port and a small diameter at the blade holding base.  
     
     
         2 . The impeller of the centrifugal fan according to  claim 1 , wherein the small diameter at the blade holding base is in the range of 70 to 90% of the large diameter at the air suction port.  
     
     
         3 . The impeller of the centrifugal fan according to  claim 1 , wherein the diameter of the inner peripheral surface of the impeller is reduced linearly from a portion at the air suction port to a portion at the blade holding base.  
     
     
         4 . The impeller of the centrifugal fan according to  claim 2 , wherein the diameter of the inner peripheral surface of the impeller is reduced linearly from a portion at the air suction port to a portion at the blade holding base.