Wind turbine blade with carbon fibre tip

Abstract

The invention relates to a wind turbine blade ( 14 ) of fibre-reinforced polymer. The blade ( 14 ) is divided into an inner end portion ( 15 ) including the blade root and made substantially from fibre glass-reinforced polymer, and an outer end portion ( 17 ) including the blade tip and made substantially from carbon fibre-reinforced polymer.

1 . Wind turbine blade ( 14 ) of fibre-reinforced polymer characterised in that it is divided into an inner end portion ( 15 ) including the blade root and made substantially from fibre glass-reinforced polymer, and an outer end portion ( 17 ) including the blade tip and made substantially from carbon fibre-reinforced polymer.  
     
     
         2 . Wind turbine blade ( 14 ) according to  claim 1 , characterised in that the outer end portion ( 17 ) constitutes between 25 and 50% of the entire length of the blade ( 14 ).  
     
     
         3 . Wind turbine ( 14 ) according to  claim 1 , characterised in that the outer end portion ( 17 ) opposite the blade tip includes a transition zone ( 16 ) in which the carbon fibres are gradually replaced by glass fibres.  
     
     
         4 . Wind turbine blade ( 14 ) according to  claim 3 , wherein the length of the transition zone ( 16 ) is between 0.5 and 1 metre.  
     
     
         5 . Wind turbine blade ( 14 ) according to  claim 3 , characterised in that the two types of fibres are distributed such in the polymer matrix that carbon fibres or carbon fibre bundles ( 1 ) with varying lengths extend from a first end of the transition zone (II) and glass fibres or glass fibre bundles ( 2 ) extend from the opposite end of the transition zone (II).  
     
     
         6 . Wind turbine blade ( 14 ) according to  claim 3 , characterised in that the transition zone (II) is formed of a laminate of several fibre layers ( 6 , 7 ), in which each fibre layer has a boundary surface ( 10 ) at a position in the longitudinal direction, the fibre layer including carbon fibres ( 6 ) on one side of the boundary surface and glass fibres ( 7 ) on the other side of the boundary face, the boundary surfaces ( 10 ) of each fibre layer being displaced in relation to each other in the longitudinal direction of the blade ( 14 ).  
     
     
         7 . Wind turbine blade according to  claim 6 , wherein the boundary surfaces ( 11 ) are serrated in a sectional view parallel to the fibre layers ( 3 ,  4 ,  5 ).  
     
     
         8 . Wind turbine blade according to  claim 7 , wherein the tips ( 12 ) of the serrated boundary surfaces ( 11 ) are displaced in relation to each other in the transverse direction of the blade ( 14 ).