GB2348251A

GB2348251A - Shape of a moulded plastic fan centre bowl

Info

Publication number: GB2348251A
Application number: GB0002957A
Authority: GB
Inventors: Bruno Lucbernet; Daniel Martin
Original assignee: ECIA Equipements et Composants pour lIndustrie Automobile SA
Current assignee: ECIA Equipements et Composants pour lIndustrie Automobile SA
Priority date: 1999-02-10
Filing date: 2000-02-09
Publication date: 2000-09-27
Anticipated expiration: 2020-02-09
Also published as: GB0002957D0; DE10005857B4; DE10005857A1; FR2789448B1; FR2789448A1; GB2348251B

Abstract

A fan (20, fig 3) has a central bowl 22 and blades 26 connected to an exterior peripheral surface SE of the bowl. The peripheral surface SE has an upstream zone Z1 and a downstream zone Z2 separated axially by the blades 26. The upstream zone Z1 is divergent with respect to an operational airstream flow direction. Adjacent to upstream zone Z1 is a zone, having a surface shape which is not of revolution. In the illustrated embodiment this adjacent zone is downstream zone Z2, or it may be an additional zone (Z3, fig 9). A line L, which is common to two adjacent zones, may represent a parting line of a mould, so that adjacent zones meet without a shoulder, thus improving aerodynamic performance and release of the fan from the mould after manufacture. The fan may be used in a motor vehicle.

Description

2348251 B&S No. COO/6 1 Fan, Particularly for a Motor-Fan Unit The

invention relates to a fan, particularly for a motor-fan unit.

There is alreaay known in the state of the art, a fan of the type comprising a central bowl centred on the axis of rotation of the fan, blades connected to an exterior peripheral surface of the bowl with a non -zero pitch angle, this exterior peripheral surface including two zones separated axially by the blades, arranged respectively upstream and downstream when considering the direction of flow - of the airstream passing through the fan during operation, the upstream zone being delimited between the blades, by a zone adjacent to it.

Customarily, the bowl has an overall shape which is of revolution about the axis of rotation of the fan, particularly a circular cylindrical shape.

A fan for a motor vehicle motor-fan unit is generally made of moulded plastic. For this, use is made of a two-part mould comprising complementary moulding surfaces which, when these parts are pressed together, delimit a surface commonly known as the "parting line", although the line may not necessarily be straight.

The upstream and downstream zones of the exterior peripheral surface-Of the bowl are formed, respectively, by the f irst and -_ s - econd parts of the mould. The leading and trailing edges of the blades lie on the parting line.

To make the blade easier to remove from the mould, it is known practice for the upstream and downstream zones of the bowl to be given conical shapes of revolution which respectively diverge and converge when considering the direction of flow of the airstream passing through the fan during operation.

However, the angle between the axis of rotation of the fan and the generatrices which form the upstream and downstream zones (clearance angle) needs to be limited to a relatively small value generally not exceeding 110. If 2 this were not the case, the upstream and downstream zones would meet, between the blades and at the fan parting line, in the form' of- a shoulder which would correspond to a significant radial offset between these upstream and downstream zones.

This radial offset, all the more significant when the divergence or convergence of the upstream and downstream zones is pronounced (a high angle between the generatrices of these zones and the axis of rotation of the fan), disrupts the aerodynamic performance of the fan.

Furthermore, the aerodynamic performance of the fan is all the better when the upstream zone of the bowl is very divergent (high angle between the generatrices of the upstream zone and the axis of rotation of the fan).

The object of the invention is to manufacture a moulded plastic fan equipped with a bowl which has a divergent upstream zone so as to improve the aerodynamic performance of the fan, and to do so while at the same time avoiding the aforementioned radial offset between the adjacent upstream and downstream zones of the bowl.

To this end, the subject of the invention is a fan of the aforementioned type, characterized in that the upstream zone is divergent with respect to the axis of rotation of the fan directed in the direction of flow of the airstream, and in that at least one from the upstream zone and the zone adjacent to it, is not of revolution about the axis of rotation of the fan, so that the upstream zone and the zone adjacent to it meet, without a shoulder, along a common line.

According to other features of this fan:

- the zone adjacent to the upstream zone is the downstream zone; - the zone adjacent to the upstream zone is a zone adjacent to both the upstream zone and the downstream I I 3 zone, extending axially between this upstream zone and this downstream zone, the upstream zone and downstream zone meeting at the.'zone which is adjacent to them along two lines, the first of which is common to the upstream zone and the zone adjacent to it, and the second of which is common to the downstream zone and to the zone adjacent to it; - the profile of the upstream zone, considered in any radial plane of the bowl whatsoever, is delimited by a curve which, at its upstream end point, has a tangent which makes an angle of between 3 and 30 with respect to the axis of rotation of the fan and, at every point of non-zero curvature, has a concave side facing towards the axis of rotation of the fan; - the downs - t - r - eam zone is convergent towards the axis of rotation of the fan directed in the direction of flow of the airstream; - the profile of the downstream zone, considered in any radial plane of the bowl whatsoever, is delimited by a curve which, at its downstream end point, has a tangent making an angle of between 0 and 50 with respect to the axis of rotation-ofthe fan and, at every point of non zero curvature, has a concave side facing towards the axis of rotation of the fan; - the profile of the zone adjacent to the upstream zone, considered - in any radial plane of the bowl whatsoever, is delimited by a curve which, at every point, has a concave side facing towards the axis of rotation of the fan and a radius of curvature which is preferably between 0 and 100 mm.

Another subject of the invention is a motor fan unit for a motor vehicle, characterized in that it comprises a fan as defined hereinabove.

The invention will be better understood from reading the description which will follow, given merely

4 by way of example and made with reference to the drawings, in which:

- Figure 1 'isia diagrammatic view of a front unit of a motor vehicle equipped with a motor-fan unit comprising a fan according to the invention; - Figures 2 and 3 are perspective views of the fan of the motor-fan unit depicted in Figure 1 showing, respectively, the upstream and downstream faces of this fan (Figure 2 has a partial cutaway of the bowl); - Figure 4 is a development of the exterior peripheral surface of the bowl of the fan depicted in the preceding figures; - Figures 5 to 7 are diagrammatic views in section on the lines 5-7 of Figure 4; - Figure 8 is a view similar to Figure 6 of a first alternative form of the exterior peripheral surface of the bowl; - Figure 9 is a view similar to Figure 4 of a second alternative form of the exterior peripheral surface of the bowl; - Figure 10 is a diagrammatic view in section on the line 10 of Figure 9.

Figure 1 diagrammatically depicts a motor vehicle front unit denoted by the overall reference 12. This figure shows a combustion engine 14, a heat exchanger 16 and a motor-fan unit 18 equipped with a fan 20 according to the invention, made of moulded plastic.

Referring particularly to Figures 2 and 3, it may be seen that this fan 20 comprises a central bowl 22, a peripheral shroud 24 and blades 26, spaced uniformly apart and stretching between the bowl 22 and the shroud 24. Each blade 26, when projected in a plane of rotation of the fan 20, has the overall shape of a chevron converging from a leading edge BA towards a trailing edge BF of the blade.

I I - 5 The bowl 22 has a wall 28 of annular overall shape, centred on the axis X of rotation of the fan. This wall 28 is of roughly c'onst'ant thickness.

The bowl 22 is closed, for example, at its upstream end (when considering the direction of flow of a stream of air passing through the fan in operation and depicted by the arrow F in Figure 4) by a wall 30 which is roughly planar and parallel to a plane of rotation of the fan.

The blades 26 are connected to an exterior peripheral surface SE, delimiting the annular wall 28 of W4 the bowl,;.th a non-zero pitch angle.

The peripheral sur-face SE has two zones Z1, Z2 axially separated by the blades 26. When considering the direction F of flow of the airstre-am, the zone Z1 is upstream and the zone Z2 is downstream.

It will be noted that the suction face side of the blades faces towards the uDstream zone Z1, whereas the pressure face side of the blades faces towards the downstream zone Z2.

To imorove the aerodynamic performance of the fan, the upstream zone- Zi is divergent with respect to the axis X of rotation of the fan directed in the direction F of flow of the airstream.

Between the blades 26, the upstream zone Z1 is delimited by a zone adjacent to it. In the case of the example illustrated more specifically in Figures 4 to 7, this adjacent zone is the downstream zone Z2.

According to the invention, at least one from the upstream zone Z1 and the zone adjacent to it is not of revolution about the axis of rotation of the fan, so thac this upstream zone-and this adjacent zone can meet along a common line L, without any shoulder or radial offset between the two --zones stretching one on either side of the common line L.

As appropriate, the tangents to the zones separated 6 by the common line L are distinct along this line L, so as to form an angle of intersection.

The common li,ne L stretches between the points A and B depicted in Figures 4 to 6. These points A and B are points of intersection with the peripheral surface SE of, respectively, the leading edge BA and the trailing edge BF of two successive blades 26.

When the fan is moulded in a conventional two-part mould, the common line L extends along the surface commonly known as the "parting line".

The divergence of the upstream zone Z1 forms, in that part of the mould which is intended for moulding this zone Z1, a clearance angle which encourages the release of this zone Zi from the mould.

For similar purposes, the downstream zone Z2 is preferably convergent towards the axis X directed in the direction F of flow of the airstream. This convergence of the downstream zone Z2 specifically makes this zone Z2 easier to release from the part of the mould intended for forming it.

In the example more specifically illustrated in Figures 4 to 7, the upstream zone Z1 is delimited by a cone of revolution about the axis X and the downstream zone Z2 is delimited by a surface which is not of revolution about this axis X.

More specifically, the generatrices of the zone Z1 are inclined by a constant angle a, preferably of between 3 and 300, with respect to the axis X (see Figures 5 to 7).

The profile of the downstream zone Z2, considered in any radial plane of the bowl whatsoever, is delimited by a straight line which makes an angle P preferably of between 0 and 50. This angle P varies at different points about the axis, that is to say adopts different values in different radial planes of the bowl.

I 7 lane of the Figure 1 depicts, in a given radial p bowl, the distanc.es dle d2 and d3 I with respect to the axis X, of the' upstream end of the prof ile of the upstream zone Z1 (dl), of the ends common to the profiles of the upstream zone Z1 and downstream zone Z2 (d,) and of the downstream end of the profile of the downstream zone Z2 (d3), respectively. it will be noted that d, is constant whereas d?. and d3 increase from point A to point B about the axis X_ when referring to Figure 7, it will be noted that the section of the - blade 26 in certain radial planes of the bowl, for example in the plane of this Figure 7, is possibly offset from the theoretical point of intersection of -the straight lines generating the upstream zone Zi and downstream zone Z2, This is due, in particular, to the curved overall shape of the cross section of the blade as depicted in particular in Figure 4.

Figure 8 depicts a first alternative form of the exterior peripheral surface SE of the bowl 22.

In this alternative form, the profiles of the upstream zone Zi -_ and downstream zone Z2, considered in any radial plane of the bowl whatsoever, are delimited by curves which, at every point, have non-zero curvature and have a concave side facing towards the axis X.

As a preference, the tangent to the upstream end point of the profile of the upstream zone zi makes an angle (x of between 3 and 300 with respect to the axis X, and the tangent to the downstream end point of the profile of the downstream zone makes an angle of between 0 and 5 with respect to the axis X.

Figures 9 and 10 depict a second alternative form of the exterior peripheral surface SE of the bowl 22.

In this case the zone which, between the blades 26, is adjacent to the upstream zone Z1 is a zone Z3 adjacent 8 to both the upstream zone Zi and the downstream zone Z2, stretching axially between these zones Z1 and Z2.

The zone Z3.,is delimited by two lines L, L' stretching between the points A and B. The first line L is common to the zones Z3 and Zi. The second line L' is common to the zones Z3 and Z2.

The upstream zone Zi and downstream zone Z2 are delimited, for example, by cones of revolution. By contrast, the zone 3 adjacent to the preceding two zones is delimited by a surface which is not of revolution about the axis X. The parting line intersects the zone Z3 along the line passing through those points of the radial profiles of Z3 which are farthest from the axis X.

As a preference, the profile of the zone Z3, considered in any radial plane of the bowl whatsoever, is delimited by a curve which, at every point, has a concave side facing towards the axis X and a radius of curvature of, for example, between 0 and 100 mm (see Figure 10).

Also as a preference, the upstream zone Z1 and downstream zone Z2 comprise, at every point on the lines L, L I, except possibly at the points A and B, a tangent which is common to the zones Z1, Z3 and to the zones Z2, Z3, respectively.

The invention is not restricted to the embodiments described hereinabove.

In particular, it is the zone adjacent to the upstream zone which may be of revolution whereas this upstream zone is not. What is more, it is possible for both the upstream zone and the zone adjacent to it to not be of revolution about the axis of rotation of the fan.

Among the advantages of the invention, it will be noted in particular that it allows the upstream zone of the bowl to be shaped in such a way that this zone exhibits relatively pronounced divergence, optimizing the aerodynamic performance of the fan and making it easier I I 9 to release from the mould and does so while at the same time avoiding any radial offset between the upstream and downstream zones.of-,Ehe bowl.

Furthermore, the invention allows the downstream zone of the bowl to be shaped in such a way that this zone has convergence which makes the fan easier to release from the mould.

Claims

1. Fan of the type comprising:

- a central- bqW1 (22) centred on the axis (x) of rotation of the fan, blades (26) connected to an exterior peripheral surface (SE) of the bowl (22) with a non-zero pitch angle, this exterior peripheral surface (SE) including two zones (Z1, Z2) separated axially by the blades (26), arranged respectively upstream and downstream when considering the direction (F) of flow of the airstream passing through the fan during operation, the upstream zone (Zi) being delimited, between the blades (26), by a zone adjacent to it, characterized in that the upstream zone (Zl) is divergent with respect to the axis (X) of rotation of the fan directed in the direction (F) of flow of the airstream, and in that at least one from the upstream zone (Zl) and the zone adjacent to it, is not of revolution about the axis (X) of rotation of the fan, so that the upstream zone (Zi) and the zone adjacent to it meet, without a shoulder, along a common line (L; LI).

2. Fan according to claim 1, characterized in that the zone adjacent to the upstream zone (Zi) is the 2S downstream zone (Z2).

3. Fan according to claim 1, characterized in that the zone adjacent to the upstream zone (Zi) is a zone (Z3) adjacent to both the upstream zone (ZI) and the downstream zone (Z2), extending axially between this upstream zone (Zi) and this downstream zone (Z2), the upstream zone (Zi) and downstream zone (Z2) meeting at the zone (Z3) which is adjacent to them along two lines, the first (L) of which is common to the upstream zone and the zone adjacent to it, and the second (LI) of which is common to the downstream zone and to the zone adjacent to I I it.

4. Fan according to any one of claims 1 to 3, characterized in-thit the profile of the upstream zone (Zi), considered in any radial plane of the bowl whatsoever, is delimited by a curve which, at its upstream end point, has a tangent which makes an angle (a) of between 3 and 300 with respect to the axis (X) of rotation of the fan and, at every point of non-zero curvature, has a concave side facing towards the axis (X) of rotation of the fan.

S. Fan according to any one of claims 1 to 4, characterized in that the downstream zone (Z2) is convergent towards the axis W of rotation of the fan directed in the direction (F) of flow of the airstream.

6. Fan according to claim S, characterized in that the profile of the downstream zone (Z2), considered in any radial plane of the bowl whatsoever, is delimited by a curve which, at its downstream end point, has a tangent making an angle (P) of between 0 and 511 with respect to the axis (X) of rotation of the fan and, at every point of non-zero curvature, has a concave side facing towards the axis (X) of rotation of the fan.

7. Fan according to any one of claims 1 to 6, characterized in that the profile of the zone adjacent to the upstream zone ( Zi), considered in any radial plane of the bowl whatsoeve - r, is delimited by a curve which, at every point, has a concave side facing towards the axis of rotation of the fan and a radius of curvature which is preferably between 0 and 100 mm.

S. Motor-fan unit for a motor vehicle, characterized in that it comprises a fan according to any one of the preceding claims.

9. A fan as hereinbefore described and shown in the accompanying drawings.

10. A motor-fan unit for a motor vehicle as herein before described and shown in the accompanying drawings.