Fan blade structure

Abstract

A fan blade structure includes a plurality of blades circumferentially spaced on a sidewall of a hub. The hub has upper and lower surfaces, which are downwind and upwind side, respectively; a front and a rear edge sequentially arranged in a rotation direction of the blade; and a root portion and a tip portion. Areas of the blade located between the tip and the root portion are divided into at least one first section located adjacent to the tip portion and one second section located between the first section and the root portion. The second section may have a thickness larger than or smaller than that of the first section, such that a stepped configuration is formed on the upwind side of the blade to provide a height difference thereon, which can effectively decrease flow resistance to reduce fan power consumption and upgrade fan efficiency.

What is claimed is: 
     
         1 . A fan blade structure, comprising:
 a hub having a top wall and a sidewall extended outward from a periphery of the top wall; and   a plurality of blades being circumferentially spaced on the sidewall of the hub; each of the blades having an upper and a lower surface defining a downwind side and an upwind side, respectively, and having a front edge, a rear edge, a root portion connected to the sidewall of the hub, and a tip portion located opposite to the root portion; areas on each of the blades between the tip portion and the root portion being divided into at least one first section and one second section; the first section being located between the second section and the tip portion, and the second section being located between the first section and the root portion; and the second section having a thickness larger than that of the first section, such that a stepped configuration defining a height difference is formed on the upwind side of the blade.   
     
     
         2 . The fan blade structure as claimed in  claim 1 , wherein the stepped configuration includes at least one stepped surface, which is an inclined surface. 
     
     
         3 . The fan blade structure as claimed in  claim 2 , wherein the upwind side of the blade is a non-smooth surface. 
     
     
         4 . The fan blade structure as claimed in  claim 1 , wherein the stepped configuration includes one single step, which is located in the first section of the blade. 
     
     
         5 . The fan blade structure as claimed in  claim 2 , wherein the step has a profile the same as and corresponding to that of the tip portion of the blade.