AXIAL FAN ROTOR FOR COOLING THE RADIATOR OF THE COOLING SYSTEM OF AN INTERNAL COMBUSTION ENGINE FOR MOTOR VEHICLES

Abstract: An axial fan rotor (1) for cooling the radiator of the cooling system of an internal combustion engine for motor vehicles, including a hub (2) carrying a ring of radial blades (3) shaped so as to improve the effi­ ciency and reduce the operating noise of the rotor.

Description: The present invention relates in general to axial fans intended to be used for cooling the radiator of the cooling system of internal combustion engines for motor vehicles. More particularly, the invention concerns an axial fan rotor of the type comprising a hub carrying a ring of radial blades, of the type generally known from GB-A-388991. The object of the present invention is to produce an axial fan rotor of the above-specified type, having a conformation which provides improved performance in terms of efficiency and quietness of operation. According to the invention, this object is achieved by virtue of the fact that each blade has the following combination of characteristics: the leading edge is curved backwardly and has a hyperbolic profile when viewed both from the front and from the side; the trailing edge is straight, and the angle of keying and twisting of succesive cylindrical sections of the blade in respect to the hub is a hyperbolic function of the radial co-ordinate of the blade. The invention will now be described in detail with reference to the appended drawings, provided purely by way of non-limiting example, in which: Figure 1 is a schematic perspective view of an axial fan rotor according to the invention, Figure 2 is a view taken on the arrow II of Figure 1, on an enlarged scale, Figure 3 is a view taken on the arrow III of Figure 1, on an enlarged scale, and Figure 4 is a view taken on the arrow IV of Figure 1, on an enlarged scale. With reference to the drawings, an axial fan rotor for cooling the radiator of the cooling system of an internal combustion engine for motor vehicles is generally indicated 1. The rotor 1, which is conveniently made in one piece from moulded plastics material, comprises a central hub 2 from which a circumferential ring of curved radial blades 3 extends. According to the invention, each blade 3 has a leading edge 3a which, as can clearly be seen in Figures 3 and 4, is curved backwardly (i.e. is concave towards the rear end of the hub 2) and has a hyperbolic profile when viewed both from the side (Figure 3) and from the front (Figure 4). The trailing edge 3b of each blade 3 is straight. Furthermore, the angle at which each blade 3 is keyed and the successive cylindrical sections of the blade are twisted in respect to the hub 2 varies hyperbolically in dependence on the radial co-ordinate of the blade. This angle, also named as "blade setting", is defined as the pitch angle of the cylindrical helix (corresponding to the chord of the developed profile) on the plane normal to the fan axis. By virtue of the above-described conformation, the fan according to the invention enables a better performance and quieter operation to be achieved in use, compared with conventional rotors.

Claims: An axial fan rotor for cooling the radiator of the cooling system of an internal combustion engine for motor vehicles, including a hub carrying a ring of radial blades, characterised in that each blade (3) has the following combination of characteristics: the leading edge (3a) is curved backwardly and has a hyperbolic profile when viewed both from the front and from the side; the trailing edge (3b) is straight, and the angle of keying and twisting of successive cylindrical sections of the blade in respect to the hub is a hyperbolic function of the radial co-ordinate of the blade (3).

Inventors: ANNOVAZZI, LORELLA
Applicants: INDUSTRIE MAGNETI MARELLI S.P.A.
Application year: 1988
Main classification: F04D29
IPC codes: F04D29