Connecting element for connecting a blade to the hub in an industrial axial fan, and blade system comprising said connecting element

Abstract

The present invention concerns a connecting element for connecting a blade, or airfoil profile, to the hub of an industrial axial fan, a blade system comprising said connecting element, and an industrial axial fan comprising such blade system. The connecting element ( 1 ) for connecting a blade ( 10 ) to the hub ( 20 ) of an industrial axial fan according to the present invention, is realized in a single L-shaped piece comprising a first part ( 1 a ) having a substantially straight develop and a second part ( 1 b ) having a substantially straight develop, said first ( 1 a ) and second ( 1 b ) part being connected by a linking part ( 1 c ) presenting a curvature radius, said first ( 1 a ) and second ( 1 b ) parts lying on substantially perpendicular planes. The connecting element according to the present invention allows to achieve several advantages with respect to the prior art, one of said advantages consisting of its extremely simple shape and manufacturing process, which render the connecting element economically advantageous.

1 . Connecting element ( 1 ) for connecting a blade ( 10 ) to the hub ( 20 ) of an industrial axial fan, said connecting element ( 1 ) being realized in a single L-shaped piece comprising a first part ( 1   a ) having a substantially straight develop and a second part ( 1   b ) having a substantially straight develop, said first ( 1   a ) and second ( 1   b ) part being connected by a linking part ( 1   c ) presenting a curvature radius, said first ( 1   a ) and second ( 1   b ) parts lying on substantially perpendicular planes. 
     
     
         2 . Connecting element ( 1 ) according to  claim 1 , characterized in that said first part ( 1   a ) and said second part ( 1   b ) lie on planes inclined of an angle which realizes directly on the connecting element instead of on the hub the blade precone angle. 
     
     
         3 . Connecting element ( 1 ) according to  claim 1 , characterized in that said first part ( 1   a ) is shorter than said second part ( 1   b ). 
     
     
         4 . Connecting element ( 1 ) according to  claim 1 , characterized in that it has a quadrangular cross-section. 
     
     
         5 . Connecting element ( 1 ) according to  claim 1 , characterized in that it has a rectangular cross-section. 
     
     
         6 . Connecting element ( 1 ) according to  claim 1 , characterized in that it is made of metallic material. 
     
     
         7 . Connecting element ( 1 ) according to  claim 1 , characterized in that it is made of plastic material. 
     
     
         8 . Connecting element ( 1 ) according to  claim 1 , characterized in that it is made of fiber glass material. 
     
     
         9 . Connecting element ( 1 ) according to  claim 1 , characterized in that it is obtained by a manufacturing process comprising the following steps:
 providing a sheet of metallic, plastic or fiberglass material;   cutting and drilling said metallic sheet;   bending the cut and drilled sheet obtaining the final L-shaped piece.   
     
     
         10 . Connecting element ( 1 ) according to  claim 1 , characterized in that it is obtained by a manufacturing process comprising the following steps:
 providing a semi finished product obtained by extrusion or pulltrusion;   cutting and drilling said semi finished product;   bending the cut and drilled semi finished product.   
     
     
         11 . Blade assembly ( 100 ) of an industrial axial fan comprising:
 a blade ( 10 ),   a hub ( 20 ),   a connecting element ( 1 ),   
       characterized in that said connecting element ( 1 ) is realized in a single L-shaped piece comprising a first, shorter, part ( 1   a ) having a straight develop and a second part ( 1   b ) having a substantially straight develop, said first ( 1   a ) and second ( 1   b ) part being connected by a linking part ( 1   c ) presenting a curvature radius, said first ( 1   a ) and second ( 1   b ) parts lying on perpendicular planes. 
     
     
         12 . Blade assembly ( 100 ) according to  claim 11 , characterized in that said first ( 1   a ) and second ( 1   b ) part being connected by a linking part ( 1   c ) presenting a curvature radius, said first ( 1   a ) and second ( 1   b ) parts lying on planes inclined of an angle which realizes directly on the connecting element instead of on the hub the blade precone angle. 
     
     
         13 . Blade assembly ( 100 ) according to  claim 11 , characterized in that said first part ( 1   a ) is shorter than said second part ( 1   b ), and in that said first part ( 1   a ) of said connecting element ( 1 ) is connected to the hub ( 20 ) and said second part ( 1   b ) of said connecting element ( 1 ) is connected to the blade ( 10 ).