WO2004106749A1 - Alternator-cooling device - Google Patents

Abstract

The invention relates to an alternator-cooling device. The inventive device comprises: at least one fan (10, 11) which is mounted around a rotating shaft (2) of the alternator; suction inlets (8a, 9a) which draw an air flow into the alternator along an axial path and outlets (8b, 9b) which release said air flow from the alternator along a radial path; and means (12, 13) for guiding the air flow inside the alternator from the axial path to the radial path.

Description

 Alternator cooling device

Field of the invention

The invention relates to a device for cooling an alternator, in particular for a motor vehicle, comprising an air guide improving the circulation of air in the alternator. The invention finds applications in the field of the automobile industry and, in particular, in the field of alternators and alternator-starters for motor vehicles.

STATE OF THE ART In a motor vehicle, the alternator makes it possible to transform a rotational movement of the inductor rotor, driven by the vehicle's heat engine, into an electric current induced in the stator windings. The alternator can also be reversible. It then constitutes an electric motor, which can rotate the thermal engine of the vehicle via the rotor shaft. This reversible alternator is called an alternator-starter and allows mechanical energy to be transformed into electrical energy, and vice versa. Thus, an alternator-starter can start the engine of the motor vehicle, constitute an auxiliary motor to drive, for example, an air conditioning compressor, or even operate in engine mode to drive the motor vehicle.

In operation, certain elements constituting the alternator or alternator-starter, such as the electronic control circuit of the alternator and the stator winding, produce heat. However, overheating of these elements can damage the alternator. It is therefore necessary to cool the alternator. This is generally achieved by means of at least one fan integrated in the alternator. Usually, this fan is placed at the back of the rotor. There may also be a second fan placed in front of the rotor. These fans, by their rotation, make it possible to draw an air flow from the outside towards the inside of the alternator. The circulation of this air flow through the alternator makes it possible to cool the various elements of the alternator.

In Figure 1, there is shown a sectional view of a conventional alternator, comprising a conventional cooling device. In this figure, only half of the alternator is shown, the other half being symmetrical with respect to the axis of symmetry XX. This alternator of the Figure 1 comprises a movement transmission member 1 belonging to a movement transmission device, not shown in the figure, acting between the engine of the vehicle and the alternator. This member can be, for example, a gear, a pulley, etc. It is traversed, in part, by a rotation shaft 2, whose axis of axial symmetry XX constitutes the axis of rotation of the machine.

This rotation shaft 2, driven by the pulley 1, carries a rotor 4 surrounded by a wound stator 5. This stator 5 comprises a magnetic circuit consisting of a pack of sheets 104 having grooves in which is housed an induced winding, generating an electric current. The current generated in the stator is rectified by means of a rectifier bridge 104 composed for example of diodes.

On either side of the axial ends of the stator sheet package, the stator winding extends in the form of winding buns 100. The stator 5 is mounted, at least in part, on a front bearing 8 and a rear bearing 9, which hold the rotation shaft 2 carrying the rotor 4, via a bearing 3a, 3b.

To cool the interior of the alternator, in particular the rectifier bridge and the chignon of the induced winding, air passages 8a, 8b, 9a, 9b are made in the front (pulley side) and rear bearings. These air passages are openings called gills; they allow the introduction and evacuation of air flows in the alternator.

In the example of Figure 1, a front fan 10 and a rear fan 11 are fixed on the rotor 4 to ensure the suction of these air flows inside the alternator. These fans can be of the centrifugal or helico-centrifugal type, for example. Some alternators have a single fan, generally the rear fan 11, which is more powerful than the front fan 10. Each fan has a flange 103 which carries the blades. In the example of FIG. 1, an air flow is sucked axially by the front fan 10, through suction openings 8a. The air then circulates through the various elements of the alternator and exits radially by exhaust vents 8b. Symmetrically, an air flow is drawn axially by the rear fan 11, through suction openings 9a. The air then flows through the different elements of the alternator and leaves radially by the evacuation openings 9b. The suction outlets are arranged in the front and rear landing.

The air is therefore sucked mainly in the axis of the alternator, that is to say along an axial path. The air flow is then discharged radially by the exhaust vents provided in the rear and front bearings. The path traveled by the air flows in the alternator of FIG. 1 is represented by arrows F1, F2. As these arrows show, the air first follows an axial path, that is to say substantially parallel to the rotation shaft 2, then it follows a radial path, that is to say substantially parallel to the faces axial of the front and rear bearings, before being evacuated by the evacuation vents 8b and 9b of the alternator. It is therefore understood that the air flow undergoes a significant change of direction between the axial path and the radial path, by an angle of the order of 90 °. This change of direction takes place suddenly, which can cause turbulence and, consequently, noise and / or losses of the air flow by change of direction and by recirculation. These losses result in a decrease in the air flow driven by the fan and therefore poor cooling performance. Disclosure of the invention The object of the invention is precisely to remedy the drawbacks of the techniques described above. To this end, the invention provides a device for cooling an alternator in which the change of direction of the air flow is facilitated by an air guide.

More specifically, the invention relates to a device for cooling an alternator comprising a fan mounted around a rotation shaft of the alternator, suction outlets for sucking in an air flow along an essentially axial path in the 'alternator and exhaust vents for exhausting the air flow out of the alternator along an essentially radial path, characterized in that it comprises means for guiding the air flow, inside the alternator, from the axial path to the radial path.

Advantageously, the means for guiding the air flow comprise a deflector placed at an angle between the axial path and the radial path. This deflector can be coupled to one or more other deflectors placed in different locations but all located in the zone of change of air flow direction.

Brief description of the drawings

Figure 1, already described, shows an example of a conventional alternator with a conventional cooling device. Figure 2 shows the alternator of Figure 1 with a cooling device according to the invention.

Figure 3 shows an embodiment of the device of the invention mounted on the front of the alternator.

FIG. 4 represents an embodiment of the deflector of FIG. 3.

Figures 5 and 6 show two examples of fans with the deflector of Figure 4.

Figures 7 to 10 show different embodiments and fixing of the deflector of the invention. Detailed description of preferred embodiments of the invention

Figure 2 shows the alternator of Figure 1 equipped with the cooling device of the invention. This alternator therefore comprises elements identical to those of the alternator in FIG. 1, but a different cooling device.

This cooling device comprises, as before, a front fan 10 and a rear fan 11, fixed to the rotor 4. It can comprise, depending on the alternator considered, a single fan.

The cooling device of the invention further comprises air intake vents 8a, 9a and air evacuation vents 8b, 9b.

It further comprises means intended to guide the air, inside the alternator, to help the air flow to change direction between the axial path and the radial path. These means for guiding the air (or air guide) form channels placed inside the alternator at the junction between the axial path and the radial path.

In the embodiment of FIG. 2, a direction change channel is placed above the flange 103 of each fan to guide the air flows towards the exhaust vents. In this FIG. 2, the means for guiding the air at the front of the alternator is referenced 12 and the means for guiding the air at the rear of the alternator is referenced 13. These means for guiding the air 12 and 13 can be produced by a deflector or several deflectors located in one or more angle (s) for changing the direction of the air flow. Several angles can be considered: for example, the angle A1 located between the support 6 of the outer ring of the front bearing housed in the front bearing and the flange of the front fan 10, or the angle A2 between the support outer ring of the bearing rear and the flange of the rear fan 11, or else the angle A3 located between the front bearing 8 and the blades of the fan 10 or the angle A4 located between the rear bearing 9 and the blades of the fan 11. In general , all the angles located at the junction between the axial path and the radial path can be considered as an angle of change of direction of the air flow. A deflector or a set of deflectors can therefore be positioned at each of these angles to avoid a sudden change in direction of the air flow between the essentially axial and radial directions of the air flow. The deflectors thus make it possible to bring the cooling air to the level of the blades with a laminar flow thus reducing the losses by change of direction or by recirculation which also contributes to a strong reduction in aerolic noise. This air flow is then expelled through the outlet outlets after having, for example, cooled the buns 100 of the stator winding. The deflector thus placed at a change of direction of the air flow thus forms a channel whose curve in the form of a round makes it possible to obtain a laminar flow. This channel can advantageously be better delimited by a second deflector situated for example opposite the first deflector. The air flow thus guided is advantageously directed so that it co-operates essentially in its entirety with the entire extent of the blades, that is to say, from the base 101 of the blades in contact with the flange of the fan up to 'at the axial free end 102 of the blades. This provides efficient and low noise cooling.

In Figure 3, there is shown, in more detail, the cooling device of the invention mounted on the front of the alternator. This figure 3 shows the rotation shaft 2 on which the rotor 4 is mounted. The front fan 10 is mounted integral with the rotation shaft 2 or with the rotor 4. The rotation shaft 2 is held on the front bearing 8 by means of a bearing 3, itself held by an outer ring support 6. In the embodiment of FIG. 3, the means for guiding the air is a deflector 12 positioned around the rotation shaft 2, between the bearing 3 and the rotor 4. Thus positioned, this deflector 12 makes it possible to guide the flow of air sucked by suction outlets (not shown) from the front bearing 8 towards the vents for evacuating the front bearing, that is to say in practice towards the blades 10a of the fan 10.

FIG. 4 shows, in a perspective view, an example of a deflector 12 which can be positioned around the rotation shaft 2, as shown in FIG. 3. This deflector has substantially the shape of a curved crown. More specifically, this ring comprises a flat base 12a and a central zone 12b curved relative to the flat base. In other words, the section of this deflector has the form of a half-section of gutter.

Thus, the air enters the alternator axially, by a path substantially parallel to the rotation shaft, it licks the central curved zone 12b of the deflector and follows the curvature of the deflector up to the flat base 12a. The air flow is then in a path substantially perpendicular to the axial path by which it was introduced into the alternator. It then follows a radial path substantially parallel to the bearing.

In the example of FIG. 4, the central curved zone 12b has a height approximately equivalent to the width of the planar base 12a. In a variant of the invention, the height of the central curved zone can be markedly different from the width of the flat base, for example an upper one, thus forming a sort of chimney. Such a variant has the advantage of allowing a greater curvature between the curved central zone and the flat base for an even more flexible change of direction.

The deflector as just described can be fixed directly around the rotation shaft, for example by force fitting. It can also be fixed to the rotor by welding, gluing, riveting, screwing or any other known fixing means. The deflector can be an integral part of the fan or can be fixed to the flange of the fan. It can be obtained by molding, folding or stamping.

The deflector can also be fixed on the outer ring support 6 of the bearing 3, as shown in FIG. 9. In this case, it can be fixed, for example, by a screw 15. In a variant, the deflector can be integrated in the outer ring support 6 of the bearing, that is to say it can be molded at the same time as the outer ring support. The deflector then constitutes the outer ring support for the bearing. This variant has the advantage of having only one piece to mount which forms both the deflector and the outer ring support. In this variant, the plate 16 for closing the bearing 3, which keeps the bearing in the housing provided for this purpose, is also fixed on the outer ring support 6, for example by a screw.

In a variant, shown in FIG. 7, the deflector 12 is integrated with the plate 16 for closing the bearing 3. In this case, the plate 16 and the deflector 12 form a single piece fixed on the outer ring support 6, for example by a screw 15. The plate and the deflector can be molded. This variant has the advantage of being simple to assemble and economical.

In a variant shown in FIG. 10, the deflector 12 is fixed, by any fixing means described above, to the plate 16 for closing the bearing.

The deflector 12 can also be positioned on the internal face of the front or rear bearing of the alternator so as to assist in the change of direction between the axial plane parallel to the axis of rotation and the radial plane formed by the bearing, as shown in FIG. 8. In this case, the base 17a of the deflector, placed at one end of the curved zone 17b, is fixed against the bearing by any fixing means mentioned above. The curved central zone 17b of the deflector is then located substantially opposite the fan blades. In another embodiment, the curved zone 17b can also be placed upstream of the blades, that is to say in the direction of the axis of rotation of the machine so that the air flow passes over the entire extent radial blades.

In a variant of the invention, the deflector can be molded directly with the bearing, during the production of this bearing. The deflector then partially constitutes the bearing of the alternator, that is to say that it is integrated into the bearing.

As shown in this figure 8, two deflectors 12 and 17 can be associated to provide a better change of direction of the air flow. For example, a first deflector 12 can be fixed under the bearing 8 and a second deflector 17, in dotted lines in FIG. 8, can be fixed on the plate 16 of the bearing 3 or else on the fan, the rotation shaft or the outer ring support, as in the previous variants. Thus, by combining these two deflectors 12 and 17, a kind of corridor or channel is created for the circulation of air. According to the invention, the alternator may comprise only one or the other of the first 12, 13 and second deflectors 17 depending on the applications. The first deflector positioned at the level of the fan flange guides the air flow at the base 101 of the blades while the second deflector guides the air flow at the top 102 of the blades. It is thus understood that the same deflector can be positioned at different locations, that is to say at different junction angles between the axial path and the radial path. However, the dimensions of the deflector must be adapted according to the angle in which it will be positioned and the alternator considered. The modifiable dimensions can be, for example, the interior radius, the exterior radius, the curvature, the height of the curved central zone. The choice of material (for example a metallic material, a plastic, etc.) making the deflector and the thickness of this material can also vary depending on the applications.

In the preferred embodiment of the invention, the deflector is positioned on the flange of the fan. An example of such a deflector mounted on the flange of a fan is shown in perspective in Figure 5. We see, in this figure 5, a fan 10 with blades 10a and a flange 10b covered by the deflector 12 In this example, the fan is a simple series of blades. It can be a metal fan, for example made of sheet metal, or a fan with a metal insert molded in plastic.

In this embodiment, the deflector 12 is fixed to the flange of the fan by welding, by gluing or by any other known fixing means. It can also be manufactured so that it fits perfectly into the fan flange; it can then be force-fitted onto the rotation shaft, at the same time as the fan.

The deflector can also be integrated into the flange of the fan so that it constitutes a single piece with the flange. In a first variant, the deflector is made of a metallic material and forms the fan insert. In this case, the metal deflector can be molded by plastic forming the blades of the fan. In another variation, the fan insert is made of metal and the deflector is molded in plastic on the insert. Such a fan is for example described in the document FR 2,673,738.

The fan can also include two series of blades belonging to one or two fans as described for example in document FR 2,741,912. In the case where they belong to two fans, these two fans are then superimposed, as in the example of FIG. 6. This FIG. 6 represents, in a perspective view, a lower fan forming a first series of blades 10a and a upper fan forming a second series of blades 10c, provided with a deflector of the invention. Such a set of fans has the advantage of improving, by itself, the suction of air in the alternator. It is the same in the case of a single fan having two sets of blades. In these two cases, the effect of the deflector is added to the effect of the double series of blades.

In the case of a fan with two sets of blades, the fan may include a metal insert molded in plastic. It comprises a first series of blades and a second series of blades. The first series of blades can be, for example, metal and the second series of plastic blades, or the reverse. The two sets of blades can also be of the same material, plastic or metal.

In this embodiment, the deflector 12 can be fixed to the flange 10b of the fan by welding, by gluing or by any other known fixing means. It can also be manufactured so that it fits perfectly into the fan flange; it can then be force-fitted onto the rotation shaft, at the same time as the fan.

In the case of two superimposed fans, as shown in Figure 6, the fans each have a series of blades. The two sets of blades can be made from the same material or, on the contrary, from different materials.

In the embodiment of FIG. 6, the deflector is, for example, integrated directly with the upper fan (or external fan) comprising the second series of blades 10c. In this case, the deflector is made of metal, formed by deformation in the cutting of the blades and is an integral part of the upper fan. Alternatively, the lower fan (which is placed between the upper fan and the rotor) can also carry the deflector.

It will be understood that the deflector of the invention can be used alone in an alternator, that is to say positioned at a single angle of the change of direction. It is also possible to couple several deflectors together, that is to say to position several deflectors at several angles of the change of direction. For example, you can couple a deflector under the bearing (in the angle A3 or A4 in Figure 2) with a deflector in the flange of the fan (in the angle A1 or A2 in Figure 2). Such a deflector and, a fortiori, several deflectors ensure a laminarization of the air flow and, consequently, less losses by change of direction or by recirculation than in the known devices and less noise. The cooling efficiency is therefore improved by this or these deflectors. In the foregoing description, only the means 12 for guiding the air have been described. It is understood that the means 13 for guiding the air, located in the rear part of the alternator, may be identical to the means 12. Only the dimensions of the deflector vary to be adapted to the rear part of the alternator. It will also be understood that the deflector of the invention can be applied to all types of alternators or alternator-starters, whatever their dimensions, whether they comprise a single fan or several fans.

Claims

1 - Cooling device of an alternator comprising at least one fan (10, 11), provided with blades (110,111), mounted around a rotation shaft (2) carrying a rotor (4), suction openings (8a, 9a) formed in a bearing (8, 9) for sucking in an air flow along an essentially axial path in the alternator and exhaust vents (8b, 9b) formed in the bearing (8, 9) for exhausting the air flow out of the alternator by an essentially radial path, characterized in that it comprises means (12, 13, 17) for guiding the air flow, inside the alternator , from the axial path to the radial path towards the blades (110,111) of the fan. 2 - Cooling device according to claim 1, characterized in that the means for guiding the air flow comprise at least a first deflector (12, 13) placed at a first angle (A1, A2) of junction between the axial path and the radial path. 3 - Cooling device according to the preceding claim, characterized in that the means for guiding the air flow comprise at least a second deflector (17) placed at a second angle (A3, A4) of junction between the axial path and the radial path. 4 - Cooling device according to claim 1, characterized in that the means for guiding the air flow comprise at least a first deflector (17) placed at a second angle (A3, A4) of junction between the axial path and the radial path. 5 - Cooling device according to claim 2, characterized in that the deflector is fixed to a flange (103) of the fan (10). 6 - Cooling device according to claim 2, characterized in that the deflector is integrated in a flange (10b) of the fan. 7 - Cooling device according to claim 6, characterized in that the deflector is metallic and constitutes an insert for the fan comprising a plastic overmolding. 8 - Cooling device according to claim 5, characterized in that the deflector is molded in plastic on a metal insert of the fan. 9 - Cooling device according to claim 8, characterized in that the deflector is integrated with a stage of blades (10c) of the fan. 10 - Cooling device according to claim 3 or 4, characterized in that the deflector is fixed on the internal face of a bearing (8, 9) of the alternator. 11 - Cooling device according to claim 3 or 4, characterized in that the deflector constitutes at least partially a bearing (8, 9) of the alternator. 12- Cooling device according to claim 2, characterized in that the deflector is fixed on an outer ring support (6) of a bearing (3) of the alternator. 13 - Cooling device according to claim 2, characterized in that the deflector constitutes at least partly an outer ring support (6) of a bearing (3) of the alternator. 14- Cooling device according to claim 2, characterized in that the deflector is fixed on a closure plate (16) of a bearing of the alternator. 15 - Cooling device according to claim 2, characterized in that the deflector constitutes at least partially a closing plate (16) of a bearing of the alternator. 16 - Alternator or alternator-starter of a motor vehicle comprising a cooling device according to any one of the preceding claims.