Fan wheel

Abstract

A fan wheel comprises a hub and a plurality of blades extending radially outwardly from the hub. A ring is arranged in coaxial relationship with the hub and radially between the hub and the outside periphery of the fan wheel. The ring has a plurality of defined fixing positions distributed over the periphery thereof for mounting at least one balancing weight.

Description

CROSS-REFERENCES TO RELATED APPLICATIONS

This application claims the priority of German Utility model application Serial No 20 2005 006 043.7 filed Apr. 14, 2005, the subject-matter of which is incorporated herein by reference.

FIELD OF THE INVENTION

The invention concerns a fan wheel, for example for cooling an electric motor and parts thereof and dissipating waste heat produced thereby.

BACKGROUND OF THE INVENTION

A typical form of fan wheel which can be frequently used for example for cooling an electric motor and electronic components thereof and dissipating waste heat therefrom may comprise a hub with a plurality of blades extending radially therefrom. A ring is arranged coaxially with respect to the hub and radially between the hub and the outer periphery of the fan wheel. Such a fan wheel can be found for example in EP 0 761 979 A1. In that arrangement the ring disposed coaxially with respect to the hub and arranged radially between the hub and the outer periphery of the fan wheel contributes to stabilising the fan wheel and stiffening the blades which are spaced from each other in the peripheral direction of the fan wheel. In addition to that ring, the fan wheel further includes a second ring which extends along the outer periphery of the fan wheel. Now, while it may be desirable to balance a fan wheel in order to extend the service life thereof and in order to reduce operational noises generated thereby, that publication does not make any reference to being able to mount a balancing weight to the fan wheel.

Reference may also be made to DE 199 57 030 A1 disclosing a rotary body with a ring disposed at the outer periphery thereof. That publication teaches fixing balancing weights which are in the form of clip-on weights to curved fixing locations distributed over the periphery of that outer peripheral ring.

DE 1 960 505 discloses a device for balancing bladed wheels of air fans, insofar as balancing weights which are displaceable in the peripheral direction can be provided on the blades.

Furthermore in general terms there are fan wheels with a peripheral ring provided at the outer periphery of the wheel, in which balancing weights in the form of clips can be mounted to the peripheral ring which is a smooth ring, for balancing purposes. A disadvantage in that case is that the clip-on weights can move in position, upon acceleration of the fan wheel.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a fan wheel which is stable and which can be balanced with a good secure balancing result.

A further object of the present invention is to provide a fan wheel which while being of a simple rational structure affords reliable balancing operations.

Yet another object of the present invention is to provide a fan wheel which can be balanced in such a way that the balanced condition once attained can be reliably maintained over a period of operation of the fan wheel.

In accordance with the present invention the foregoing and other objects are attained by a fan wheel comprising a hub and a plurality of blades extending radially outwardly from the hub. A ring is arranged in coaxial relationship with the hub, radially between the hub and the outer periphery of the fan wheel. The ring has a plurality of defined fixing positions distributed over the periphery thereof for mounting thereto at least one balancing weight.

As will be seen from the description hereinafter of a preferred embodiment of the fan wheel according to the invention, the underlying notion of the invention is to provide means for definedly fixing at least one balancing weight in different selected positions to a stabilisation or stiffening ring which is spaced radially both from the outside diameter of the fan wheel and also from the hub thereof. The provision of those defined fixing positions prevents slippage of the balancing weights in a peripheral direction, in particular upon a change in the speed of rotation of the fan wheel as upon acceleration thereof. The fact that the fixing positions are provided on the ring means that they can be distributed over the entire periphery of the ring and thus the fan wheel, thereby permitting one or more balancing weights to be fitted to the fan wheel in a finely stepped relationship. The fact that the fixing positions are provided on the stabilisation ring means that a stabilisation function and a balancing function are achieved using just one common component part in the form of the ring.

Good balancing results can be achieved by arranging the fixing positions on the ring which is disposed at a radial spacing from the outer periphery of the fan wheel. The results which can be attained can be even more accurate than when one or more balancing weights is or are arranged at the outer periphery of the fan wheel. A further advantage of the fan wheel according to the invention is that the negative effects of weight tolerances in respect of the balancing weights on the balancing result are less significant than if the balancing weights were to be fixed to the outside diameter of the fan wheel.

The fact that the fixing positions are not provided on the blades of the fan wheel and the fact that the stabilisation ring on which the fixing positions are provided is disposed at a spacing from the outer periphery of the fan wheel can considerably reduce the risk of deformation of or damage to the blades when fitting a balancing weight.

In accordance with a preferred feature of the invention the defined fixing positions can be formed by a profiling of the ring. If for example the fan wheel is produced from plastic material in the form of an injection molding, the profile can be formed on the ring directly in production of the fan wheel.

In another preferred feature the profiling of the ring, at least in peripheral portions thereof, can be in the form of a sawtooth profiling. In that case the angles of all flanks of the sawtooth profiling with respect to the ring should be of equal magnitude. With that arrangement, for example a balancing weight in the form of a clip weight can be clamped between the sawtooth configurations. The inclined flanks of the profiling mean that the clip cannot be displaced in the peripheral direction. A further fixing option can provide that the balancing weights are of a complementary shape in relation to the profiling in order thereby to achieve an improved positively locking connection between the profiling of the ring and the respective balancing weight.

In a preferred feature the profiling is on the radially outward side of the ring. The large periphery at the outside of the ring means that a plurality of defined fixing positions can thus be provided on the ring. It will be appreciated that it is also possible additionally or alternatively to provide a profiling at the side of the ring which faces towards the hub and/or at the side faces of the ring which thus face in the axial direction of the fan wheel.

In a further preferred feature of the invention the fixing positions are formed by fixing bores which are suitably distributed over the periphery of the ring. When the balancing weights are of a suitable configuration they can be introduced into and then fixed in the bores. That can thus prevent subsequent displacement of the one or more balancing weights in relation to the ring.

In another preferred feature the fixing positions can be formed by receiving pockets which are distributed over the periphery of the ring, to receive the balancing weights.

If, in accordance with a further preferred feature of the invention, the ring is of a closed configuration in the peripheral direction, it is possible to provide a very large number of fixing positions for balancing weights on the closed ring.

In accordance with a further preferred feature, and on the basis of tests showing that a particularly good compromise can be achieved between optimum stabilisation and stiffening of the fan wheel and optimum balancing results, the diameter of the ring can correspond to approximately half the fan wheel diameter.

A preferred feature of the invention can provide that the blades extend continuously from the hub to the outside diameter of the fan wheel, thereby providing a good delivery output. Depending on the respective situation of use however it is also possible for the blades to be subdivided into two groups of blades, more specifically a first group of blades which extend radially between the hub and the ring and a second group which extends radially between the ring and the outer periphery of the fan wheel. In that case the blades of different groups can be arranged in mutually displaced relationship in the peripheral direction.

In many situations of use it is advantageous if the blades are mounted directly to the shaft of an electric motor, in which case therefore the hub of the fan wheel is formed by the actual motor shaft. That configuration can provide that the fan wheel can be produced in a particularly simple fashion integrally with the shaft, thereby eliminating the need to provide a hub in the true sense as a separate component part of the fan wheel.

In a further preferred feature it can be provided that the balancing weight is adapted to be fixed releasably to the ring, and is thus for example in the form of a clip which can be bent into position to hold it on the ring, in order in that way to ascertain the respective fixing position at which the best balancing effect is achieved with a respective balancing weight.

In order to achieve a good positively locking connection between the profiling of the ring and the balancing weight, the balancing weight may be of a complementary shape in relation to a peripheral portion of the profiling of the ring.

In yet another preferred feature of the invention, in addition to the ring disposed radially between the hub and the outer periphery of the fan wheel, the fan wheel may have a second ring which is arranged in coaxial relationship with the first-mentioned ring, for stabilisation and stiffness reasons. In an ideal situation that secorid ring can be arranged at the outside periphery of the fan wheel.

Further objects, features and advantages of the invention will be apparent from the description hereinafter of a preferred embodiment of the invention.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 shows a perspective view of a fan wheel according to the invention, and

FIG. 2 shows an enlarged detail from FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring firstly to FIG. 1 shown therein is a fan wheel which is identified generally by reference numeral 1 and which may comprise for example plastic material. The fan wheel 1 can be used for example for cooling an electric motor and electronic components thereof. For that purpose the fan wheel 1 has a hub 2, in the center of which there is provided an axially extending fitting opening 3, by means of which the fan wheel 1 can be fitted on to the shaft of an electric motor and secured relative to the shaft to prevent rotation with respect thereto.

The fan wheel 1 has a plurality of blades 4, in this embodiment five blades, which are distributed uniformly over the periphery of the fan wheel 1 and which extend substantially radially outwardly from the hub 2. It will be noted that all the blades 4 are identical and are curved in the peripheral direction in their radially outward extent and are set at an angle relative to the axial center line 5 of the fan wheel 1.

To stabilise and stiffen the blades 4 the fan wheel 1 has a ring 7 which is formed integrally with the blades 4. The ring 7 illustrated here is of a closed configuration. The shallow circular ring 7 extends in the peripheral direction entirely around the hub 2 and is arranged in coaxial relationship with the hub 2 and radially between the hub 2 and the outer periphery as indicated at 6 of the fan wheel 1. The ring 7 can widen to approximately the width of the blades 4 immediately adjacent to the blades 4, thereby enhancing the stability and resistance to fracture of the fan wheel 1. In the illustrated embodiment the diameter of the ring 7 approximately corresponds to half the diameter of the fan wheel 1 but it may also be larger or smaller, inter alia in dependence on the diameter of the fan wheel.

At its outward side 8 the ring 7 is provided with a profiling 9 illustrated in the form of a sawtooth profiling, with teeth 10 and tooth gaps 11 which alternate in the peripheral direction around the ring 7. The tooth gaps 11 provide defined fixing positions 12 for mounting one or more balancing weights (not shown) for balancing the fan wheel 1. The balancing weights used can be for example in the form of metal clips which are laterally inserted into one or more tooth gaps 11 as required and which bear against the inside 13 and the outside 8 of the ring 7 and thereby bear clampingly thereagainst. The provision of the defined fixing positions avoids displacement of the one or more balancing weights in the peripheral direction of the ring 7.

The profiling 9 is of such a configuration that the teeth 10 form isosceles triangles. It is particularly advantageous if the balancing weights are of a complementary shape to the profiling 9, at least in portions thereof, to provide a positively locking connection to the ring 7. In the present case therefore each balancing weight can have at least one tooth corresponding to a tooth 10 of the profiling 9 or a tooth gap corresponding to a tooth gap 11 of the profiling 9.

It will be seen that in the illustrated embodiment the profiling 9 is provided exclusively at peripheral portions 14 of the ring 7, which extend between the blades 4.

The blades 4 of the fan wheel 1 extend continuously from the hub 2 to the outside diameter 6 of the fan wheel 1. A second peripherally closed ring 15 extends along the outer periphery of the fan wheel 1 and thus additionally enhances the stability and stiffness of the fan wheel 1 and also closes it off radially outwardly.

Reference will now be made to FIG. 2 showing a portion of the fan wheel 1 of FIG. 1 on an enlarged scale. FIG. 2 clearly shows the sawtooth profiling 9 on the ring 7 with the peripherally alternate teeth 10 and tooth gaps 11. The depth of the tooth gaps 11 approximately corresponds to a quarter of the thickness of the ring 7.

It will be appreciated that the above-described embodiment has been set forth solely by way of example and illustration of the principles of the invention and that various modifications and alterations may be made therein without thereby departing from the spirit and scope of the invention.

Claims

1. A fan wheel comprising:

a hub,

a plurality of blades extending at least substantially radially outwardly from the hub,

a ring arranged in coaxial relationship with the hub and radially between the hub and the outside diameter of the fan wheel, and

on the ring a plurality of defined fixing positions distributed over the periphery thereof for mounting at least one balancing weight.

2. A fan wheel as set forth in claim 1

wherein the fixing positions are formed by a profiling of the ring.

3. A fan wheel as set forth in claim 2

wherein the blades are spaced in the peripheral direction and wherein the profiling is provided exclusively between the blades.

4. A fan wheel as set forth in claim 2

wherein the profiling is in the form of sawtooth profiling at least in peripheral portions of the ring.

5. A fan wheel as set forth in claim 2

wherein the profiling is on the radial outside of the ring.

6. A fan wheel as set forth in claim 1

wherein the fixing positions are formed by fixing bores distributed over the periphery of the ring.

7. A fan wheel as set forth in claim 1

wherein the fixing positions are formed by receiving pockets distributed over the periphery of the ring.

8. A fan wheel as set forth in claim 1

wherein the ring is closed in the peripheral direction.

9. A fan wheel as set forth in claim 1

wherein the ring is of a diameter which corresponds to half the fan wheel diameter.

10. A fan wheel as set forth in claim 1

wherein the blades extend continuously from the hub to the outside diameter of the fan wheel.

11. A fan wheel as set forth in claim 1

wherein the hub is in the form of a shaft.

12. A fan wheel as set forth in claim 11

wherein said shaft is the shaft of a motor.

13. A fan wheel as set forth in claim 1

wherein at least one balancing weight is fixed to the ring.

14. A fan wheel as set forth in claim 13

wherein said balancing weight is releasably fixed to the ring.

15. A fan wheel as set forth in claim 13

wherein the balancing weight is in the form of a clip.

16. A fan wheel as set forth in claim 13

wherein the balancing weight is of complementary form to a peripheral portion of the profiling.

17. A fan wheel as set forth in claim 1 including

in addition to said ring a second ring arranged in coaxial relationship with the ring.

18. A fan wheel as set forth in claim 17

wherein the second ring is a closed ring at the outside periphery of the fan wheel.