Axial Flow Fan

Abstract

In an axial flow fan provided with a plurality of impeller blades ( 13 ) provided in a hub ( 14 ), and a plurality of bent portions ( 13 c ) each formed by bending an outer peripheral edge of each of the impeller blades ( 13 ) toward a negative pressure surface ( 13 e ) of each of the impeller blades ( 13 ), a protruding portion ( 13 f ) is provided in a portion in which a blowing wind speed is high and a pressure rising work is most effectively carried out, in a rear edge portion ( 13 b ) of each of the impeller blades ( 13 ). Each of the protruding portions ( 13 f ) protrudes to an inverse direction to a rotating direction of each of the impeller blades ( 13 ) with respect to a straight line L connecting a proximal end and an outer peripheral end in the rear edge portion ( 13 b ) of each of the impeller blades ( 13 ). In this case, if a vane area of each of the impeller blades ( 13 ) is enlarged by setting a protruding portion ( 13 f ) at a predetermined position in the rear edge portion ( 13 b ) of each of the impeller blades ( 13 ), it is possible to effectively compensate for shortage of an amount of rise in static pressure which is lowered by bending the outer peripheral edge of each of the impellers ( 13 ).

1 . An axial flow fan comprising a plurality of impeller blades ( 13 ) provided on a hub ( 14 ), and a plurality of bent portions ( 13   c ) each formed by bending an outer peripheral edge of each of the impeller blades ( 13 ) toward a negative pressure surface ( 13   e ) of the impeller blade ( 13 ),
 the axial flow fan being characterized in that a protruding portion ( 13   f ) is provided in a portion in which a blowing wind speed is high and a pressure rising work is most effectively carried out in a rear edge portion ( 13   b ) of each of the impeller blades ( 13 ), and each of the protruding portions ( 13   f ) protrudes to an inverse direction to a rotating direction of the impeller blades ( 13 ) with respect to a straight line L connecting a proximal end and an outer peripheral end in the rear edge portion ( 13   b ) of each of the impeller blades ( 13 ).   
   
   
       2 . The axial flow fan according to  claim 1 , characterized in that each of the bent portions ( 13   c ) is provided over the entirety of the corresponding impeller blade ( 13 ) from the front edge portion ( 13   a ) to the rear edge portion ( 13   b ). 
   
   
       3 . The axial flow fan according to  claim 1 , characterized in that each of the bent portions ( 13   c ) is provided in a portion from a position between the front edge portion ( 13   a ) and the rear edge portion ( 13   b ) in each of the impeller blades ( 13 ) to the rear edge portion ( 13   b ). 
   
   
       4 . The axial flow fan according to any one of  claims 1  to  3 , characterized in that a width of each of the bent portions ( 13   c ) is formed so as to become gradually larger toward the rear edge portion ( 13   b ) from the front edge portion ( 13   a ) of each of the impeller blades ( 13 ). 
   
   
       5 . The axial flow fan according to any one of  claims 1  to  4 , characterized in that, in each of the protruding portions ( 13   f ), a portion protruding most largely in the inverse direction to the rotating direction with respect to the straight line L is set in a region in which the value of an expression of (R−Rh)/(Rt−Rh) is between 0.65 and 0.85, where a radius of the axial flow fan is represented by Rt, a radius of the hub ( 14 ) is represented by Rh, and a distance in a radial direction from a center O of rotation of the axial flow fan is represented by R.