GB2057586A - Fan wheel - Google Patents

Abstract

The wheel, e.g. for a motor vehicle generator, comprises a disc part (12) and fan vanes (14) bent out of the plane of the disc part, the thickness of each vane decreasing from its base (16) to its tip (17). The wheel may be cast or made from sheet metal. <IMAGE>

Description

SPECIFICATION Fan wheel The invention relates to a fan wheel, e.g. for electrical machines, especially for three phase generators for motor vehicles.

Fan wheels are already known which are made from sheet metal and in which the fan vanes are bent out of the plane of the disc part. However, these sheet metal fans could not satisfy the increased demands with respect to stability upon changes in rotational speed. On the other hand, cast fan wheels having a greater stability upon changes in rotational speed are known, although the hubs of cast fans are too thick and cannot satisfy requirements with respect to a smaller overall length of the machine.

According to the present invention there is provided a fan wheel comprising a disc part and fan vanes bent out of the plane of the disc part, the thickness of the fan vanes decreasing from the base of the vane to the tip of the vane.

The fan wheel of the present invention may, for example, be cast or made from sheet metal.

Advantages which may result from the present invention are: (i) that the mass of the vanes may be reduced and thus reducing the stress caused by centrifugal force. Thus, greater stability upon changes in rotational speed can be obtained.

(ii) the surface areas of the vanes, and thus the performance of the fan, are not affected by the invention.

(iii) the fan wheel may be produced by a simple manufacturing operation.

The invention will now be described further by way of example with reference to the accompanying drawings, in which: Figure 1 is a plan view of a fan wheel in accordance with the present invention, Figure 2 is a side elevation of the fan wheel of Figure 1, and Figure 3 is a side elevation of a second embodiment of the fan wheel of the invention.

Referring to Figures 1 and 2 there is shown a fan wheel 11 which includes a disc-shaped part 12 whose centre has an aperture 13 for insertion of a machine shaft. The outer periphery of the disc part 12 is serrated, and fan vanes 14 are bent out of the plane of the disc part. Corrugations 1 5 are provided for stiffening the disc part 12 and to reduce bending-up of the fan vanes 14 during operation of the fan wheel. The thickness of the fan vanes 14 decreases from the base 1 6 of the vanes to the ends 17 of the vanes. In the embodiment shown in Figures 1 and 2 the thickness decreases continuously. It has proved to be particularly advantageous for the thickness of the material at the ends 17 of the vanes to be approximately half the thickness of the material at the bases 1 6 of the vanes.Advantageously, the thickness of the fan vanes 14 is reduced by a stretching operation during manufacture of the fan wheel. Furthermore, it has proved to be advantageous to effect the stretching operation on the outwardly directed face 1 8 of the fan vanes 14, so that the diameter of the inner face of the vanes 14 remain constant and the diameter of the outer face 1 8 decreases from the base 1 6 to the tip 17.

Referring now to Figure 3, there is shown a second embodiment in which the thickness of the fan vanes 14 decreases in stages or steps from the base 16 of the vane to the end 17 of the vane. In this embodiment the diameter of the inner face of the vanes increases from the base 1 6 to the tip 17.

1. A fan wheel comprising a disc part and fan vanes bent out of the plane of the disc part, the thickness of the fan vanes decreasing from the base of the vane to the tip of the vane.

2. A fan as claimed in claim 1, in which the reduction of thickness is continuous.

3. A fan as claimed in claim 2, in which the reduction in the thickness is effected by a stretching operation.

4. A fan as claimed in claim 1, in which the thickness is reduced in a step-wise manner.

5. A fan as claimed in claim 4, in which the step-wise reduction of the thickness is effected by stamping the vanes.

6. A fan as claimed in one of the preceding claims, in which the thickness of the fan vanes decreases from the full thickness of the material at the bases of the vanes to at least half the thickness of the material at the tips of the vanes.

7. A fan as claimed in one of the claims 4 to 6, in which the stretching/stamping is performed such that the diameter of the outwardly directed face of the or each vane decreases from base to tip.

8. A fan wheel as claimed in any'one of the preceding claims, which is made from sheet metal.

9. A fan wheel constructed arid arranged substantially as hereinbefore described with reference to and as illustrated in Figures 1 and 2 or Figure 3 of the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (9)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Fan wheel The invention relates to a fan wheel, e.g. for electrical machines, especially for three phase generators for motor vehicles. Fan wheels are already known which are made from sheet metal and in which the fan vanes are bent out of the plane of the disc part. However, these sheet metal fans could not satisfy the increased demands with respect to stability upon changes in rotational speed. On the other hand, cast fan wheels having a greater stability upon changes in rotational speed are known, although the hubs of cast fans are too thick and cannot satisfy requirements with respect to a smaller overall length of the machine. According to the present invention there is provided a fan wheel comprising a disc part and fan vanes bent out of the plane of the disc part, the thickness of the fan vanes decreasing from the base of the vane to the tip of the vane. The fan wheel of the present invention may, for example, be cast or made from sheet metal. Advantages which may result from the present invention are: (i) that the mass of the vanes may be reduced and thus reducing the stress caused by centrifugal force. Thus, greater stability upon changes in rotational speed can be obtained. (ii) the surface areas of the vanes, and thus the performance of the fan, are not affected by the invention. (iii) the fan wheel may be produced by a simple manufacturing operation. The invention will now be described further by way of example with reference to the accompanying drawings, in which: Figure 1 is a plan view of a fan wheel in accordance with the present invention, Figure 2 is a side elevation of the fan wheel of Figure 1, and Figure 3 is a side elevation of a second embodiment of the fan wheel of the invention. Referring to Figures 1 and 2 there is shown a fan wheel 11 which includes a disc-shaped part 12 whose centre has an aperture 13 for insertion of a machine shaft. The outer periphery of the disc part 12 is serrated, and fan vanes 14 are bent out of the plane of the disc part. Corrugations 1 5 are provided for stiffening the disc part 12 and to reduce bending-up of the fan vanes 14 during operation of the fan wheel. The thickness of the fan vanes 14 decreases from the base 1 6 of the vanes to the ends 17 of the vanes. In the embodiment shown in Figures 1 and 2 the thickness decreases continuously. It has proved to be particularly advantageous for the thickness of the material at the ends 17 of the vanes to be approximately half the thickness of the material at the bases 1 6 of the vanes.Advantageously, the thickness of the fan vanes 14 is reduced by a stretching operation during manufacture of the fan wheel. Furthermore, it has proved to be advantageous to effect the stretching operation on the outwardly directed face 1 8 of the fan vanes 14, so that the diameter of the inner face of the vanes 14 remain constant and the diameter of the outer face 1 8 decreases from the base 1 6 to the tip 17. Referring now to Figure 3, there is shown a second embodiment in which the thickness of the fan vanes 14 decreases in stages or steps from the base 16 of the vane to the end 17 of the vane. In this embodiment the diameter of the inner face of the vanes increases from the base 1 6 to the tip 17. CLAIMS

1. A fan wheel comprising a disc part and fan vanes bent out of the plane of the disc part, the thickness of the fan vanes decreasing from the base of the vane to the tip of the vane.

2. A fan as claimed in claim 1, in which the reduction of thickness is continuous.

3. A fan as claimed in claim 2, in which the reduction in the thickness is effected by a stretching operation.

4. A fan as claimed in claim 1, in which the thickness is reduced in a step-wise manner.

5. A fan as claimed in claim 4, in which the step-wise reduction of the thickness is effected by stamping the vanes.

6. A fan as claimed in one of the preceding claims, in which the thickness of the fan vanes decreases from the full thickness of the material at the bases of the vanes to at least half the thickness of the material at the tips of the vanes.

7. A fan as claimed in one of the claims 4 to 6, in which the stretching/stamping is performed such that the diameter of the outwardly directed face of the or each vane decreases from base to tip.

8. A fan wheel as claimed in any'one of the preceding claims, which is made from sheet metal.

9. A fan wheel constructed arid arranged substantially as hereinbefore described with reference to and as illustrated in Figures 1 and 2 or Figure 3 of the accompanying drawings.