Fan blade edge

Abstract

The invention relates to the blades of a fan wheel. The invention particularly relates to a hollow profiled blade for a fan wheel. A hollow profiled blade according to the invention for a fan wheel is made from a planar semi-finished product and has a leading edge and a trailing edge as well as a compression side and a suction side. A hollow area is formed in the interior of the hollow profiled blade whereby the part of the planar semi-finished product forming the one side of the hollow profiled blade extends over the part of the planar semi-finished product forming the other side of the hollow profiled blade.

1 . A hollow profiled blade for a fan wheel whereby the hollow profiled blade is manufactured from at least a first planar semi-finished product and has a leading edge and a trailing edge as well as a compression side and a suction side and whereby a hollow area is formed in the interior of the hollow profiled blade whereby the compression side has a first part of the first planar semi-finished product and the suction side has a second part of the first planar semi-finished product, characterized in that the hollow profiled blade has a wall thickness which is less than twice the wall thickness of the first planar semi-finished product in an area which is arranged in front of the trailing edge and directly adjacent to the trailing edge. 
     
     
         2 . A hollow profiled blade according to  claim 1  characterized in that the hollow profiled blade has a wall thickness in the area which essentially corresponds to the wall thickness of the first planar semi-finished product. 
     
     
         3 . A hollow profiled blade according to  claim 1  characterized in that the first part of the first planar semi-finished product extends beyond the second part of the planar semi-finished product in the area. 
     
     
         4 . A hollow profiled blade according to  claim 1  characterized in that the second part of the first planar semi-finished product extends over the first part of the planar semi-finished product in the area. 
     
     
         5 . A hollow profiled blade according to  claim 1  characterized in that the first part of the planar semi-finished product of the hollow profiled blade is connected tightly and flush with the second part of the first planar semi-finished product. 
     
     
         6 . A hollow profiled blade according to  claim 4  characterized in that the position of the bend of the first part of the first planar semi-finished product forms an abrupt change in thickness in the profile of the hollow profiled blade on the second part of the first planar semi-finished product. 
     
     
         7 . A hollow profiled blade according to  claim 6  characterized in that the first part of the planar semi-finished product of the hollow profiled blade is welded tightly and flush to the second part of the first planar semi-finished product by a fillet weld. 
     
     
         8 . A hollow profiled blade according to  claim 6  characterized in that the ratio of the magnitude of the abrupt change in thickness to the length by which the second part of the first planar semi-finished product of the hollow profiled blade extends over the position of the bend of the first part of the first planar semi-finished product lies in the range from 1:1 to 1:100. 
     
     
         9 . A hollow profiled blade according to  claim 6  characterized in that the ratio of the magnitude of the abrupt change in thickness to the length by which the second part of the first planar semi-finished product of the hollow profiled blade extends over the position of the bend of the first part of the first planar semi-finished product lies in the range from 1:2 to 1:20. 
     
     
         10 . A hollow profiled blade according to  claim 1  characterized in that, a stiffener profile is arranged in the interior of the hollow profiled blade. 
     
     
         11 . A hollow profiled blade according to  claim 10  characterized in that, the stiffener profile is formed from the bent portion of the first part of the first planar semi-finished product. 
     
     
         12 . A hollow profiled blade according to  claim 10  characterized in that the stiffener profile can be manufactured by bending. 
     
     
         13 . A hollow profiled blade according to  claim 1  characterized in that a part of the first planar semi-finished product lies flat on one side of the hollow profiled blade in the interior of the hollow profiled blade in the area of the trailing edge. 
     
     
         14 . A hollow profiled blade according to  claim 13  characterized in that the overlying part of the first planar semi-finished product in the area of the trailing edge lies flat on the suction side of the hollow profiled blade in the interior of the hollow profiled blade. 
     
     
         15 . A hollow profiled blade according to  claim 1  characterized in that the hollow profiled blade is made from precisely a first planar semi-finished product, 
     
     
         16 . A hollow profiled blade according to  claim 1  characterized in that, in the area a second planar semi-finished product is arranged whereby this second planar semi-finished product extends over the first planar semi-finished product in the direction of the trailing edge of the hollow profiled blade and whereby the wall thickness of the second planar semi-finished product is less than twice the wall thickness of the first planar semi-finished product. 
     
     
         17 . A hollow profiled blade according to  claim 16  characterized in that, the second planar semi-finished product extends into the interior of the hollow profiled blade. 
     
     
         18 . A hollow profiled blade according to  claim 16  characterized in that the first part of the first planar semi-finished product of the hollow profiled blade and/or the second part of the first planar semi-finished product is connected tightly and flush with the second planar semi-finished product. 
     
     
         19 . A hollow profiled blade according to  claim 18  characterized in that, the first part of the first planar semi-finished product of the hollow profiled blade and/or the second part of the first planar semi-finished product is welded to the second planar semi-finished product by a fillet weld. 
     
     
         20 . A hollow profiled blade according to  claim 16  characterized in that a stiffener profile is arranged in the interior of the hollow profiled blade. 
     
     
         21 . A hollow profiled blade according to  claim 20  characterized in that, the stiffener profile is formed from the second of the planar semi-finished products. 
     
     
         22 . A hollow profiled blade according to  claim 20  characterized in that the stiffener profile can be manufactured by bending. 
     
     
         23 . A fan wheel for a radial fan with a top plate and a base plate, characterized in that, the fan wheel has several hollow profiled blades between the top plate and the base plate. 
     
     
         24 . A fan wheel according to  claim 23 , characterized in that, the hollow profiled blades have lugs in its upper and/or lower narrow side, while the top plate and/or the base plate have slots into which the lugs can be inserted to secure the hollow profiled blades between the top plate and the base plate.