Engine cooling fan

Abstract

An engine cooling fan ( 100 ) comprising a hub ( 102 ) and a plurality of blades ( 104 ) each of which extends away from the hub ( 102 ), wherein the hub ( 102 ) defines a rotation axis about which the hub ( 102 ) is adapted to rotate during operation; wherein each blade ( 104 ) defines an attachment part ( 108 ), an air moving part ( 106 ), and a center line extending in a longitudinal direction of the blade ( 104 ) between a tip end and a hub end of the blade; wherein at least a first zone of the center line extends in a direction transverse to a normal of the rotation axis of the hub ( 102 ). Moreover the present invention relates to a blade ( 104 ) for use in the fan ( 100 ) and a kit comprising the blade ( 104 ) and the fan ( 100 ).

1 . An engine cooling fan comprising a hub and a plurality of blades each of which extends away from the hub, wherein the hub defines a rotation axis about which the hub is adapted to rotate during operation; wherein each blade defines an attachment part, an air moving part, and a center line extending in a longitudinal direction of the blade between a tip end and a hub end of the blade; wherein at least a first zone of the center line extends in a direction transverse to a normal of the rotation axis of the hub, and wherein the center line extends through a geometrical center of any cross-section of the air moving part which is orthogonal to the centre line. 
     
     
         2 . The engine cooling fan according to  claim 1 , wherein a second zone of the center line coincides with the normal. 
     
     
         3 . The engine cooling fan according to  claim 2 , the second zone is positioned closer to the hub end of the blade than the zone part. 
     
     
         4 . The engine cooling fan according to  claim 1 , wherein the center line extends through a geometrical center of any cross-section of the blade which defines a normal to the centre line. 
     
     
         5 . The engine cooling fan according to  claim 1 , wherein the air moving part of the blade is designed such that for any point on that part of the center line which extends through the air moving part, the resulting vector of all forces acting on the point defines a tangent to the respective point. 
     
     
         6 . The engine cooling fan according to  claim 1 , wherein the blade is designed such that for any point on the center line, the resulting vector, in a plane defined by the center line of the blade and the rotation axis of the hub, of all forces acting on the point defines a tangent to the respective point. 
     
     
         7 . The engine cooling fan according to  claim 1 , wherein the center line is curved such that it defines at least one concavity. 
     
     
         8 . The engine cooling fan according to  claim 1 , wherein the first derivative of the pitch in the hub end is larger than the first derivative of the pitch in the tip end. 
     
     
         9 . The engine cooling fan according to  claim 1 , wherein the second derivative of the pitch in the hub end is larger than the second derivative of the pitch in the tip end. 
     
     
         10 . The engine cooling fan according to  claim 1 , wherein the pitch decreases in the direction of the tip end. 
     
     
         11 . The engine cooling fan according to  claim 1 , wherein the first derivative of the pitch is 10 percent larger in a hub zone than in a tip zone. 
     
     
         12 . The engine cooling fan according to  claim 11 , wherein a width of each blade is defined between a leading edge and a trailing edge of the blade, and wherein the width of the blade in the tip zone is larger than the distance between the hub ends of two neighbouring blades. 
     
     
         13 . The engine cooling fan according to  claim 11 , wherein a width of each blade is defined between a leading edge and a trailing edge of the blade, and wherein the width of the blade in the hub zone is larger than the distance between the hub ends of two neighbouring blades. 
     
     
         14 . The blade for an engine cooling fan, according to  claim 1 . 
     
     
         15 . The kit comprising a hub and a plurality of blades according to  claim 1 .