Centrifugal fan

Abstract

A centrifugal fan is provided. The centrifugal fan includes a shaft and a plurality of blades. The blades is disposed on the shaft and surround the shaft, and outer edges of the blades define a circle. The circle includes an outer region adjacent to a boundary of the circle, each of the blades includes a first contour line and a second contour line within the outer region, and the neighboring blades include an air channel therebetween, which expands toward the outer edges of the blades according to an interval expanding ratio.

What is claimed is: 
     
         1 . A centrifugal fan, comprising:
 a shaft; and   a plurality of blades, disposed on the shaft and surrounding the shaft, wherein outer edges of the blades define a circle, the circle has an outer region adjacent to a boundary of the circle, each of the blade has a first contour line and a second contour line within the outer region, and the neighboring blades form an air channel therebetween, which expands toward the outer edges of the blades according to an interval expanding ratio.   
     
     
         2 . The centrifugal fan according to  claim 1 , wherein the interval expanding ratio is less than 25%. 
     
     
         3 . The centrifugal fan according to  claim 1 , wherein a ratio of a difference between a maximum thickness and a minimum thickness of the blade to the maximum thickness of the blade is greater than 30%. 
     
     
         4 . The centrifugal fan according to  claim 1 , wherein each of the blades has a thickness variation. 
     
     
         5 . The centrifugal fan according to  claim 1 , wherein a quantity of the blades is greater than 30. 
     
     
         6 . The centrifugal fan according to  claim 1 , wherein the first contour line and the second contour line are respectively located on a pressurized surface and a rear surface of the blade. 
     
     
         7 . The centrifugal fan according to  claim 1 , wherein the interval expanding ratio is a fixed value. 
     
     
         8 . The centrifugal fan according to  claim 1 , wherein the second contour line is defined according to the first contour line and the interval expanding ratio. 
     
     
         9 . The centrifugal fan according to  claim 1 , wherein the first contour line has a plurality of nodes, and an expansion value of the air channel corresponding to two neighboring nodes is proportional to a product of the interval expanding ratio and a distance between the two neighboring nodes.