Fan structure

Abstract

A fan structure includes a hub and at least one set of blades connected to and extending away from the hub, each of the blades having a plurality of steps with a height difference formed away from the periphery of the hub, the height of the inside one of the steps higher than that of the outside one of the steps, thereby providing a disturbed flow-guiding effect so as to enhance the air pressure and the air flow of the wind flow field.

What is claimed is: 
     
         1 . A fan structure, comprising:
 a hub; and   at least one set of blades, extending from the hub, each of the blades having a step structure radially formed away from the periphery of the hub.   
     
     
         2 . The fan structure of  claim 1 , wherein the set of blades is consisting of two blades. 
     
     
         3 . The fan structure of  claim 1 , wherein the set of blades is consisting of three blades. 
     
     
         4 . The fan structure of  claim 1 , wherein the hub includes an upper plate and a shrouding plate bended and extending from the periphery of the upper plate, the set of blades extending from the shrouding plate, respectively. 
     
     
         5 . The fan structure of  claim 4 , further comprising a shaft centrally connected to an inside portion of the upper plate and surrounded by the shrouding plate. 
     
     
         6 . The fan structure of  claim 1 , wherein the step structure has a fillet formed on the tip thereof. 
     
     
         7 . A fan structure, comprising:
 a hub; and   at least one set of blades connected to and extending away from the hub, each of the blades having a plurality of steps, the steps having a height difference and formed away from the periphery of the hub, a height of an inside one of the steps higher than a height of an outside one of the steps.   
     
     
         8 . The fan structure of  claim 7 , wherein the set of blades is consisting of two blades. 
     
     
         9 . The fan structure of  claim 7 , wherein the set of blades is consisting of three blades. 
     
     
         10 . The fan structure of  claim 7 , wherein the hub includes an upper plate and a shrouding plate bended and extending from the periphery of the upper plate, the set of blades extending from the shrouding plate, respectively. 
     
     
         11 . The fan structure of  claim 10 , further comprising a shaft centrally connected to the inside of the upper plate and surrounded by the shrouding plate. 
     
     
         12 . The fan structure of  claim 7 , wherein each of the blades has an upper arc surface and a lower arc surface correspondingly formed under the upper arc surface, a cutting line of the upper arc surface intersecting with an axle line of the hub. 
     
     
         13 . The fan structure of  claim 12 , wherein the inside one of the steps is disposed between the upper arc surface and the outside one of the steps, and the height of the inside step is lower than that of the upper arc surface. 
     
     
         14 . The fan structure of  claim 7 , wherein the outside step has a fillet formed on the tip thereof.