Impeller for axial-flow heat-dissipating fan

Abstract

An impeller for an axial-flow heat-dissipating fan includes a hub and a plurality of blades symmetrically formed on an outer periphery of the hub and extending in an inclined angle with respect to a longitudinal direction parallel to a rotational axis of the hub. Each blade includes a leading edge, a trailing edge, a radial inner edge, and a radial outer edge. Two adjacent blades overlap with each other in the longitudinal direction such that each blade has first and second overlapped areas. The first overlapped area on each blade extends outward from the leading edge and the radial inner edge but spaced from the radial outer edge of the blade. The second overlapped area on each blade extend outward from the trailing edge and the radial inner edge but spaced from the radial outer edge of the blade. The air inlet amount is increased and blowing noise is lowered.

1 . An impeller for an axial-flow heat-dissipating fan, comprising: 
 a hub including an outer periphery; and    a plurality of blades symmetrically formed on the outer periphery of the hub and extending in an inclined angle with respect to a longitudinal direction parallel to a rotational axis of the hub;    each said blade including a leading edge, a trailing edge, a radial inner edge, and a radial outer edge;    two of the blades adjacent to each other overlapping with each other in the longitudinal direction such that each said blade having a first overlapped area and a second overlapped area;    the first overlapped area on each said blade extending outward from the leading edge and the radial inner edge but spaced from the radial outer edge of the blade, the second overlapped area on each said blade extending outward from the trailing edge and the radial inner edge but spaced from the radial outer edge of the blade, thereby increasing an air inlet amount and lowering blowing noise.    
   
   
       2 . The impeller for an axial-flow heat-dissipating fan as claimed in  claim 1  wherein the trailing edge of each said blade projects on an adjacent blade along a rear projection line, and wherein the first longitudinal overlapped area is defined by the rear projection line, the leading edge of the adjacent blade, and the radial inner edge of the adjacent blade.  
   
   
       3 . The impeller for an axial-flow heat-dissipating fan as claimed in  claim 2  wherein: 
 the leading edge of each said blade intersects the radial inner edge of the blade at a front base point;    the rear projection line intersects the leading edge of the adjacent blade at an overlapped point; and    a distance between the front base point and the overlapped point is ⅕-⅘ of a length of the leading edge.    
   
   
       4 . The impeller for an axial-flow heat-dissipating fan as claimed in  claim 2  wherein: 
 the leading edge of each said blade intersects the radial inner edge of the blade at a front base point;    the rear projection line intersects the radial inner edge of the adjacent blade at an overlapped point; and    a distance between the front base point and the overlapped point is ⅙-⅚ of a length of the radial inner edge.    
   
   
       5 . The impeller for an axial-flow heat-dissipating fan as claimed in  claim 1  wherein the trailing edge of each said blade projects on an adjacent blade along a front projection line, and wherein the second longitudinal overlapped area is defined by the front projection line, the trailing edge of the adjacent blade, and the radial inner edge of the adjacent blade.  
   
   
       6 . The impeller for an axial-flow heat-dissipating fan as claimed in  claim 5  wherein: 
 the trailing edge of each said blade intersects the radial inner edge of the blade at a rear base point;    the front projection line intersects the trailing edge of the adjacent blade at an overlapped point; and    a distance between the rear base point and the overlapped point is ⅕-⅘ of a length of the trailing edge.    
   
   
       7 . The impeller for an axial-flow heat-dissipating fan as claimed in  claim 5  wherein: 
 the trailing edge of each said blade intersects the radial inner edge of the blade at a rear base point;    the front projection line intersects the radial inner edge of the adjacent blade at an overlapped point; and    a distance between the rear base point and the overlapped point is ⅙-⅚ of a length of the radial inner edge.    
   
   
       8 . The impeller for an axial-flow heat-dissipating fan as claimed in  claim 1  wherein: 
 the leading edge of each said blade is at an angle between 10 degrees and 90 degrees with the trailing edge of an adjacent blade when viewed from the longitudinal direction parallel to the rotational axis of the hub.    
   
   
       9 . The impeller for an axial-flow heat-dissipating fan as claimed in  claim 1  wherein: 
 the leading edge of each said blade intersects the radial outer edge of the blade at a front end point;    the trailing edge of each said blade intersects the radial outer edge of the blade at a rear end point;    a line passing through the front end point of the leading edge and the rear end point of the trailing edge of each said blade is at an angle between 10 degrees and 70 degrees with a plane orthogonal to the rotational axis of the hub.    
   
   
       10 . The impeller for an axial-flow heat-dissipating fan as claimed in  claim 3  wherein: 
 the rear projection line intersects the radial inner edge of the adjacent blade at a second overlapped point; and    a distance between the front base point and the second overlapped point is ⅙-⅚ of a length of the radial inner edge.    
   
   
       11 . The impeller for an axial-flow heat-dissipating fan as claimed in  claim 10  wherein the trailing edge of each said blade projects on an adjacent blade along a front projection line, and wherein the second longitudinal overlapped area is defined by the front projection line, the trailing edge of the adjacent blade, and the radial inner edge of the adjacent blade.  
   
   
       12 . The impeller for an axial-flow heat-dissipating fan as claimed in  claim 11  wherein: 
 the trailing edge of each said blade intersects the radial inner edge of the blade at a rear base point;    the front projection line intersects the trailing edge of the adjacent blade at a third overlapped point; and    a distance between the rear base point and the third overlapped point is ⅕-⅘ of a length of the trailing edge.    
   
   
       13 . The impeller for an axial-flow heat-dissipating fan as claimed in  claim 12  wherein: 
 the front projection line intersects the trailing edge of the adjacent blade at a fourth overlapped point; and    a distance between the rear base point and the fourth overlapped point is ⅙-⅚ of a length of the trailing edge.