ENGINE COOLING FAN

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).

DETAILED DESCRIPTION OF THE FIGURES

FIGS. 1-3disclose an engine cooling fan100according to the present invention. The fan comprises a hub102and a plurality of blades104which extend radially from the hub102. In the embodiment ofFIGS. 1-3, the fan comprises twelve blades104which are spaced apart equidistantly along the circumference of the hub102. Each blade defines an air moving part106and an attachment part108, seeFIG. 4. The air moving part106is designed such that when the engine cooling fan100is rotated as indicated by arrow110, a flow of air is generated as indicated by arrow112.

The width of the air moving part106of each blade—in the area of the hub—is wider than the distance between two neighbouring attachment parts. Thus in order to make it possible to arrange the blades, the chord of the blades extend in a direction which is transverse to a plane relative to which the rotational axis defines a normal.

This may also be seen when looking on the pitch of different points of the blade. Accordingly, the pitch per distance (i.e. the first derivative of the pitch) between the reference lines114and118is smaller than the pitch per distance between the reference points116and118.

This is exemplified in the following example:

The distance between the lines114and118may in the example be 0.352 meter while the relative pitch between the two lines is 24 degrees. At the same time the distance between the lines116and118may be 0.0922 meters, while the relative pitch between the lines is 14.3 degrees. Accordingly, the pitch per distance between the lines114and118is 24 degrees divided by 0.352 meter i.e. 68 degrees per meter. At the same time the pitch between the lines116and118is 14.3 degrees divided by 0.0922 meters i.e. 155 degrees per meter. Accordingly, the first derivative of the hub zone (the hub zone being defined between the lines116and118) is larger than in the tip zone (the tip zone being defined between lines118and114).

In order to prohibit the blade from deflecting during use, the air moving part106of the blade is curved such that the center line of the blade (not illustrated) does not coincide with a radial line120(which defines a right angle with the rotational axis of the fan). InFIG. 9this is evident from the fact that the blade is curved in a direction away from the radial line120. It will be appreciated thatFIG. 9discloses a cross-section through the center line of the blade. The cross-section being in the longitudinal direction of the blade.

The curve of the blade is chosen such that for any position on the center line, the resulting vector122at any point along the center line of all forces acting on the point defines a tangent124to the respective point on the center line. InFIG. 9two forces acts on the blade, namely the centrifugal force126and the aerodynamic force128.

As the resulting force defines a tangent to the point, the only effect of the resulting force is an insignificant elongation of the blade due to the resulting force being a tensile force.

The curve of the blade may also be seen inFIG. 8, where the distance130indicates the distance between the center line at the tip of the blade and the radial line120.