WO2018091822A1

WO2018091822A1 - Fan for a rotor for a rotating electrical machine

Info

Publication number: WO2018091822A1
Application number: PCT/FR2017/053125
Authority: WO
Inventors: Jean-François GAUTRU; Pierre Faverolle; Erwan LE GOFF
Original assignee: Valeo Equipements Electriques Moteur
Priority date: 2016-11-15
Filing date: 2017-11-15
Publication date: 2018-05-24
Also published as: FR3058847A1; MX2019005602A; FR3058847B1; CN109690919A; CN109690919B; DE112017005731T5

Abstract

The present invention proposes a rotor for a rotating electrical machine, in particular of a motor vehicle, comprising: - a rotor body; - at least one fan (25, 26) mounted on the rotor body, said fan comprising a base (37) and a plurality of blades (39) protruding from the base, each blade having: - a radially outer end (40), - a first axial end (42) and a second axial end (43) axially opposite said first end, the first axial end extending in continuation of the base, - a first connecting portion (44) between the first axial end and the radially outer end - a second connecting portion (45) between the second axial end and the radially outer end, characterised in that at least one from among the first connecting portion and the second connecting portion has a rounded shape.

Description

FAN FOR ROTOR FOR ELECTRIC MACHINE

ROTARY

The invention particularly relates to a fan for a rotor for a rotating electrical machine.

The invention finds a particularly advantageous application in the field of rotating electrical machines such as alternators, alternator-starters or reversible machines. It will be recalled that a reversible machine is a rotating electrical machine able to work in a reversible manner, on the one hand, as an electric generator in alternator function and, on the other hand, as an electric motor for example to start the engine of the motor vehicle .

A rotating electrical machine comprises a rotor movable in rotation about an axis and a fixed stator surrounding the rotor, the rotor-stator assembly being mounted in bearings. In alternator mode, when the rotor is rotating, it induces a magnetic field to the stator which transforms it into electric current to power the vehicle's electrical consumers and recharge the battery. In motor mode, the stator is electrically powered and induces a magnetic field driving the rotor in rotation.

Fans are mounted on the rotor and have the function of creating an air flow inside the rotating electrical machine to cool the hottest active parts of said machine. In particular, the fans can be used to cool the power electronics, the bearings, the rotor winding and the stator winding.

The present fans are formed of a base extending radially from the axis of the machine and a plurality of blades protruding, generally in an axial direction, from the base. These blades have a rectangular shape. This rectangular shape is defined by first and second axial ends and by an inner radial end and an outer radial end; the inner radial end being closest to the axis of the machine and the first axial end extending continuously from the base of the fan. Each blade then has a connecting portion between the second axial end and the outer radial end.

Most of the blade link portions are wedge-shaped, i.e. they form a substantially rectangle angle. In certain configurations of rotating electrical machine, some blades may have a flat chamfer at their connecting portion. This chamfer mainly has a function of balancing the fan. In addition, in general, this chamfer is provided from the design of the fan, such a fan is naturally balanced.

Such fans generate a level of noise that can disturb the comfort of the user of the motor vehicle.

The present invention aims to avoid the disadvantages of the prior art.

Thus, the present invention aims to allow a reduction of the aerodynamic noise generated by the fans of the rotating electrical machine while maintaining a good level of cooling of said machine.

For this purpose, the subject of the present invention is therefore a rotor for a rotating electrical machine, in particular for a motor vehicle. According to the present invention, the rotor comprises:

a rotor body;

at least one fan mounted on the rotor body, said fan comprising a base and a plurality of blades projecting from the base, each blade has:

an external radial end,

a first axial end and a second axial end axially opposed to said first end, the first axial end extending continuously from the base,

a first connecting portion between the first axial end and the outer radial end,

a second connecting portion between the second axial end and the outer radial end. In addition according to the present invention, at least one of the first connecting portion and the second connecting portion has a rounded shape.

The fact that at least one of the connecting portions is of rounded shape makes it possible to reduce the interactions between the fan and the stator and those between the fan and the bearing of the rotating electrical machine by reducing the distance between the different elements.

This also makes it possible to reduce the disturbance of the air flow generated by the fan at the outlet of the blade and thus contributes to improving the cooling efficiency, that is to say that for the same air flow in fan inlet the flow of air at the outlet is increased.

Thus, the overall aerodynamic noise generated by the fans is decreased without impacting the cooling of the rotating electrical machine. In particular, certain harmonics such as the harmonic linked to the number of pairs of poles of the rotor no longer have any emergence with respect to the other harmonics. The noise that can be heard by the user of the motor vehicle are reduced.

By rounded shape is meant a form of curve. In other words, at least one of the first connecting portion and the second connecting portion has a convex shape relative to the axis of the rotor, that is to say curved. In other words, at least one of the first connecting portion and the second connecting portion is devoid of sharp edges. This rounded shape is different from a chamfer.

In one embodiment, the blades are disposed on an outer periphery of the base.

In one embodiment, the connecting portion extends over a transverse length greater than an axial thickness of the base. The transverse length is defined by the distance between the inner radial end and the outer radial end taken in a projection of the blade in a plane parallel to said blade. This simplifies the process of producing the fan.

In one embodiment, the connecting portion extends over a transverse length greater than or equal to 10% of the total length of the blade. . In one embodiment, the connecting portion extends over an axial height greater than an axial thickness of the base. The height is defined by the distance between the first axial end and the second axial end taken in a projection of the blade in a plane parallel to said blade. This also simplifies the process of producing the fan.

In one embodiment, the connecting portion extends over an axial height greater than or equal to 10% of the total height of the blade.

According to one embodiment, the connecting portion has a transverse length and an axial height, said length being different from said height. For example, the length is greater than the height. In another example, the length is less than the height.

According to an alternative embodiment, the connecting portion has a transverse length equal to its axial height.

In one embodiment, the first connecting portion and the second connecting portion have rounded shapes.

According to one embodiment, each rounded shape is defined by a radius and at least one center, the radius and / or the at least one center of the rounded shape of the first connecting portion being, respectively, different from those of the second portion. link.

In a variant, the radius and the at least one center of the first connecting portion are identical, respectively, to the radius and to the at least one center of the second connecting portion.

In one embodiment, the outer radial end is formed by a point.

According to one embodiment, a blade has, in addition, a third connecting portion between the second axial end and an inner radial end, said inner radial end being closer to the axis of the rotor, the third connecting portion having a rounded shape. .

According to one embodiment, each rounded shape is defined by a radius and at least one center, the radius and / or the at least one center of the rounded shape of the third connecting portion being, respectively, different those of the first connecting portion and those of the second connecting portion.

Alternatively, the radii and centers of all the connecting portions may be identical to form an arc or part of an ellipse.

According to one embodiment, at least half of the blades, in particular at least 80% of the blades, of the same fan have at least one rounded connection portion of the first connecting portion and the second connecting portion,

According to one embodiment, all the blades of the same fan have at least one rounded connection portion of the first connecting portion and the second connecting portion.

In one embodiment, all the blades of the same fan have an identical shape. Alternatively, the blades of the same fan may have different shapes.

According to one embodiment, all the blades of the same fan have the first connecting portion, the second connecting portion and the third connecting portion of rounded shape.

According to one embodiment, the fan comprises reinforcing ribs extending at least partly on the blades, a clearance being disposed between the first connecting portion and said rib. Thus, the rib does not extend over the first connecting portion.

According to one embodiment, the clearance is in particular greater than an axial thickness of the base.

In one embodiment, an angle measured from the base to the blade at a lateral face of said blade is between 40 ° and 140 °, the lateral face extending between the two axial ends.

For example, the blade is inclined with respect to the axial direction. In another example, the blade extends axially substantially perpendicular to the base, that is to say that said angle is substantially equal to 90 °.

In one embodiment, the blade extends along a straight line between the inner radial end and the outer radial end. As a variant, the blade may extend along a curve concave with respect to the axis of the rotor between the inner radial end and the outer radial end.

In another variant, the blade may extend in a convex curve relative to the axis of the rotor between the inner radial end and the outer radial end.

In one embodiment, the blades are made of material with the base.

In one embodiment, the fan is centrifugal type.

According to one embodiment, each bearing comprises axial air inlet openings facing a portion of the fan and radial air outlet openings facing the bun concerned winding.

The present invention also relates to a rotating electrical machine. The rotating electrical machine can advantageously form an alternator, an alternator-starter or a reversible machine.

The present invention may be better understood on reading the following detailed description of examples of non-limiting implementation of the invention and of examining the appended drawings, in which:

FIG. 1 represents, schematically and partially, a cross-sectional view of a rotating electrical machine according to an exemplary implementation of the invention,

FIG. 2 represents, schematically and partially, a perspective view of a fan of FIG. 1,

FIGS. 3 to 7 show, schematically and partially, a section of a blade of a fan according to the prior art and according to various embodiments of the present invention,

FIG. 8 shows several curves representing the overall noise level of the rotating electrical machine as a function of the speed of rotation for different fan configurations, and

FIG. 9 shows several curves representing the noise level of the harmonic linked to the number of pairs of rotor poles of the rotating electrical machine as a function of the speed of rotation for different fan configurations. Identical, similar or similar elements retain the same references from one figure to another.

The embodiments which are described below are in no way limiting; it will be possible to imagine variants of the invention comprising only a selection of characteristics described hereinafter isolated from the other characteristics described, if this selection of characteristics is sufficient to confer a technical advantage or to differentiate the invention compared to the state of the art. In particular, all the variants and all the embodiments described are combinable with each other if nothing stands in the way of this combination at the technical level. In such a case, mention would be made in the present description.

FIG. 1 represents a rotating electrical machine 10 which is compact and polyphase, in particular for a motor vehicle. This rotating electrical machine 10 transforms mechanical energy into electrical energy, into alternator mode, and can operate in motor mode to transform electrical energy into mechanical energy. This rotary electrical machine 10 is, for example, an alternator, an alternator-starter or a reversible machine.

The rotary electrical machine 10 comprises a housing 1 1. Inside this housing 1 1, it further comprises a shaft 13, a rotor 12 integral in rotation with the shaft 13 and a stator 15 surrounding the rotor 12. The rotational movement of the rotor 12 is around an X axis.

In the remainder of the description, the axial, radial, external and internal denominations refer to the axis X crossing at its center the shaft 13. The axial direction corresponds to the X axis while the radial orientations correspond to the planes concurrent, and in particular perpendicular, to the X axis. For the radial directions, the outer or inner denominations are evaluated with respect to the same axis X, the inner denomination corresponding to an element oriented towards the axis, or closer to the axis. axis relative to a second element, the outer denomination designating a distance from the axis. In this example, the housing 1 1 comprises a front bearing 16 and a rear bearing 17 which are assembled together. These bearings 16, 17 are hollow in shape and each carries a respective ball bearing 18, 19 for the rotational mounting of the shaft 13.

A pulley 20 is fixed on a front end of the shaft 13, at the front bearing 16, for example by means of a nut bearing against the bottom of the cavity of this pulley. This pulley 20 transmits the rotational movement to the shaft 13.

The rear end of the shaft 13 carries, here, slip rings 21 belonging to a manifold 22. Brushes 23 belonging to a brush holder 24 are arranged so as to rub on the slip rings 21. The brush holder 24 is connected to a voltage regulator (not shown).

The front bearing 16 and the rear bearing 17 may further comprise substantially lateral openings for the passage of air in order to allow the cooling of the rotary electric machine by air circulation generated by the rotation of a fan. before 25 on the front dorsal face of the rotor 12, that is to say at the level of the front bearing 16 and a rear fan 26 on the rear dorsal face of the rotor, that is to say at the level of the bearing back 17.

In this example, the rotor 12 is a claw rotor. It comprises two pole wheels 31 forming a rotor body. Each pole wheel 31 is formed of a flange 32 and a plurality of claws 33 forming magnetic poles. The flange 32 is of transverse orientation and has, for example, a substantially annular shape. This rotor 12 further comprises a cylindrical core 34 which is interposed axially between the pole wheels 31. Here, this core 34 is formed of two half-cores each belonging to one of the pole wheels. The rotor 12 comprises, between the core 34 and the claws 33, a coil 35 comprising, here, a winding hub and an electric winding on this hub. For example, the slip rings 21 belonging to the collector 22 are connected by wire bonds to said coil 35. The rotor 12 may also comprise magnetic elements interposed between two adjacent claws 33. In this exemplary embodiment, the stator 15 comprises a body 27 in the form of a pack of sheets with notches, for example of the semi-closed or open type, equipped with slot insulator for mounting an electric winding. 28. This coil 28 passes through the notches of the body 27 and form a front bun 29 and a rear bun 30 on either side of the stator body. The coil 28 is connected, for example, in a star or in a triangle.

Moreover, the winding 28 is formed of one or more phases. Each phase comprises at least one conductor passing through the notches of the stator body 27 and forms, with all phases, the buns. The coil 28 is electrically connected to an electronic assembly 36.

The electronic assembly 36 comprises at least one electronic power module for controlling a phase of the winding 28. This power module forms a voltage rectifier bridge to transform the alternating voltage generated by the alternator 10 into a DC voltage to power in particular the battery and the vehicle's electrical system.

When the electric winding is electrically powered from the brushes, the rotor is magnetized and becomes an inductor rotor with formation of magnetic north-south poles at the claws. This inductor rotor creates an alternating induced current in the stator induced when the shaft is rotating. The rectifier bridge then transforms this AC induced current into a direct current, in particular to supply the loads and the consumers of the onboard network of the motor vehicle as well as to recharge its battery.

The function of the fans 25, 26 is to create a circulation of a cooling fluid, in this case air, for cooling the hottest active parts of the rotary electrical machine 10. These hot parts are, for example, diodes or transistors of the electronic assembly 36, the bearings 18, 19, the coil 35 of the rotor or the winding 28 of the stator.

Various openings are provided in the bearing 1 1 to allow the flow of air flow. For example, each level 16, 17 has axial air intake openings facing a portion of the fan and radial air outlet openings facing the bun concerned winding 28.

As described in the example of Figure 2, each fan 25, 26 has a base 37 shaped annular plate substantially flat and transverse orientation. The base 37 is provided with a circular central opening 38 for the passage of the rotor shaft 13. Each fan 25, 26 further comprises a series of blades 39 projecting axially relative to the base 37. Preferably, the blades are disposed on an outer periphery of the base 37. Outwardly diverging ventilation channels are thus formed by the blades.

Each blade 39 has an outer radial end 40 and an inner radial end 41. The radial ends are the ends of the blade which protrude from the base 37, the inner radial end 41 being the end closest to the central opening 38.

Each blade 39 has, in addition, a first axial end 42 and a second axial end 43 axially opposite said first end. The axial ends are the ends of the blade which extend in a direction substantially parallel to the base 37, the first axial end 42 extending continuously from the base 37, that is to say that the first axial end 42 is in contact with the base 37. More specifically, the first axial end 37 extends continuously from one face of the base 37 which faces the rotor.

In addition, each blade 39 has different connecting portions: a first connecting portion 44 between the first axial end 42 and the outer radial end 40, a second connecting portion 45 between the second axial end 43 and the outer radial end 40 and a third connecting portion 46 between the second axial end 43 and the inner radial end 41.

Figure 3 illustrates a blade of the prior art. This blade has connecting portions whose shape is at right angles. The blade then has a global shape of rectangle. Figures 4, 5, 6 and 7 illustrate various embodiments of the present invention.

Figure 4 illustrates a first embodiment. In this first mode, the second connecting portion 45 has a rounded shape, that is to say that the connection between the second axial end 43 and the outer radial end 40 is by means of a curve and no longer from a right angle.

Preferably, the connecting portion extends over a transverse length L2 greater than an axial thickness E of the base 37.

Preferably, the connecting portion extends over an axial height

H2 greater than the axial thickness E of the base 37.

The length and height are, respectively, defined by the distance between the inner radial end and the outer radial end and between the first axial end and the second axial end taken in a projection in a plane parallel to the blade.

Preferably, the connecting portion extends over a transverse length L2 greater than or equal to 10% of the total length L1 of the blade 39. Similarly, the connecting portion extends over a height H2 greater than or equal to 10 % of the total height H1 of the blade 39.

In the example of Figure 4, the length L2 of the second connecting portion 45 is equal to half the total length L1. Still in this example, the height H2 of the second connecting portion 45 is equal to half of the total height H1.

Figure 5 illustrates a second embodiment. In this second mode, the first connecting portion 44 has a rounded shape, that is to say that the connection between the first axial end 42 and the outer radial end 40 is by means of a curve and no longer from a right angle.

In the example of Figure 5, the length L2 of the first connecting portion 44 is equal to 40% of the total length L1. Still in this example, the height H2 of the first connecting portion 44 is equal to 60% of the total height H1. Figure 6 illustrates a third embodiment. In this third mode, the first connecting portion 44 and the second connecting portion 45 have, respectively, rounded shapes. In this example, the length L2 of the first connecting portion 44 is equal to half of the total length L1. Still in this example, the height H2 of the first connecting portion 44 is equal to half of the total height H1. In addition, the length L2 of the second connecting portion 45 is equal to 70% of the total length L1 and the height H2 of the second connecting portion 45 is equal to half of the total height H1.

The rounded shape is defined by a radius and at least one center from which the radius is defined. In the example shown in FIG. 6, the radius and / or the center of the first connecting portion 44 are, respectively, different from the radius and / or the center of the second connecting portion 45. There is no of symmetry between the two curvatures of the connecting portions.

Alternatively, as shown in FIG. 7, the radius and the center of the first connecting portion 44 is identical, respectively, to the radius and the center of the second connecting portion 45. The link portions 44, 45 can then form a part of ellipse or an arc.

In this example as well as in that of Figure 6, the outer radial end 40 is a point.

Furthermore, in the example of FIG. 7, the third connecting portion 46 has a rounded shape, that is to say that the connection between the second axial end 43 and the internal radial end 41 is effected by means of 'a curve.

In this example, the radius and / or the center of the third connecting portion 46 are, respectively, different from the radius and / or the center of the first connecting portion 44 and / or those of the second connecting portion 45.

Alternatively, the radii and centers of all the connecting portions 44, 45, 46 may be identical to form an arc or part of an ellipse. All the ratio combinations between the length L2 with respect to the total length L1 and the ratio between the height H2 with respect to the total height H1 for the different connection portions 44, 45, 46 are possible without departing from the scope of the invention to optimize the compromise between a low level of aerodynamic noise and a good level of cooling.

Thus, the connecting portion 44, 45, 46 may have a transverse length L2 different from its axial height H2. For example, the length L2 is greater than the height H2. In another example, the length L2 is less than the height H2. In addition, in an alternative embodiment, the length L2 may be equal to the height H2.

Preferably, all the blades 39 of the same fan 25, 26 have at least one of the first connecting portion 44 and the second connecting portion 45 with a rounded shape. Preferably, all the blades 39 have the same rounded-shaped connection portion with an identical shape of curvature. In other words, the blades 39 of the same fan 25, 26 are identical to each other.

In an alternative embodiment, the blades 39 of the same fan 25, 26 may have different shapes from their curvature or from non-rounded connection portions for some of said portions.

In an exemplary embodiment, the blades 39 of the front fan 25 are identical to the blades 39 of the rear fan 26. In a variant, the blades 39 of the front fan 25 are different from the blades 39 of the rear fan 26.

As shown in FIG. 2, the fan 25, 26 may comprise reinforcing ribs 47. These ribs 47 may extend both on the base 37 and on the blades 39. Preferably, the rounded shape of the portions of links 44, 45, 46 does not extend over the rib. Preferably, the first connecting portion 44 extending adjacent to the reinforcing rib 47. Preferably, the angle measured from the base 37 towards the blade 39 at a lateral face of the blade is between 40 ° and 140 °, the lateral face extending between the two axial ends 42, 43 For example, the blade 39 is inclined with respect to the axial direction. In another example, the blade 39 extends axially substantially perpendicular to the base, that is to say that said angle is substantially equal to 90 °.

Preferably, the blade 39 extends along a straight line between the inner radial end 41 and the outer radial end 40. As a variant, the blade 39 can extend in a concave curve with respect to the base 37 between the internal radial end 41 and the outer radial end 40. In another variant, the blade 39 may extend in a convex curve relative to the base 37 between the inner radial end 41 and the outer radial end 40.

Preferably, the inner radial end 41 is not opposed radially to the outer radial end 40. Thus, the blades 39 are inclined with respect to an axis transverse to the X axis.

Each fan 25, 26 may comprise between one and fifty nine blades 39. The front fan 25 and the rear fan 26 may have a different number of blades.

The blades 39 are, for example, distributed angularly in a regular manner. As a variant, the blades 39 are not distributed angularly in a regular manner, that is to say that the circumferential intervals between two consecutive blades are not equal.

In addition, some blades 39 may have a total length L1 and / or a total height H1 different from other blades 39 of the same fan 25, 26. The blades here have a radially length L1 greater than their axial height H1.

Preferably, the fans 25, 26 are made of steel.

Preferably, the blades 39 are made of material with the base 37.

Preferably, each fan 25, 26 is formed from a cut plate of the specified shape on which parts are then bent to form the blades 39. The rounded shapes of the blades 39 are thus formed before folding.

Each fan 25, 26 thus formed is then fixed on the rotor 12, for example by spot welding or laser type through, by screwing or riveting or in any other way.

An angular indexing means can intervene for a good angular position of the fans 25, 26 and thus a good orientation of the blades 39.

As can be seen in particular in Figure 2, each fan 25, 26 may comprise a flange 48 which projects axially from the opening 38 and allows the centering of the fan relative to the shaft 13.

Preferably, each fan 25, 26 is in contact with the polar wheel 31 concerned. This contact is a direct or indirect contact. In the case of indirect contact, a means such as a coating or a layer may be interposed at least locally between the polar wheel 31 concerned and the fan 25, 26.

Preferably, each fan 25, 26 is of the centrifugal type. As a variant, each fan 25, 26 may, for example, be of axial or axial-centrifugal type.

FIG. 8 shows a first curve 81, a second curve 82 and a third curve 83 which represent the overall noise level of the rotating electrical machine 10 as a function of its speed of rotation. The first curve 81 is for a fan whose blades 39 do not have a rounded shape as illustrated in Figure 3. The first curve 81 thus illustrates a rotating electrical machine of the prior art. The second curve 82 is for a fan whose blades 39 have their first connecting portion 44 of rounded shape as illustrated by Figure 5. The third curve 83 is for a fan whose blades 39 have their first connecting portion 44 their second connecting portion 45 as well as their third connecting portion 46 with rounded shapes as illustrated by FIG. 7. It can be seen that the noise level is decreased on the second curve 82 with respect to the first curve 81 and even more diminished on the third curve 83. Such a rotating electrical machine thus has a reduced aerodynamic noise.

FIG. 9 shows a first curve 91, a second curve 92 and a third curve 93 which represent the noise level of the harmonic linked to the number of pairs of rotor poles of the rotating electrical machine 10 as a function of its rotational speed. This is for example the harmonic 6 in the case of a machine with 6 pairs of poles. The first curve 91 is for a fan whose blades 39 do not have a rounded shape as shown in Figure 3. The first curve 91 thus illustrates a rotating electrical machine of the prior art. The second curve 92 is for a fan whose blades 39 have their first connecting portion 44 of rounded shape as illustrated by Figure 5. The third curve 93 is for a fan whose blades 39 have their first connecting portion 44 their second connecting portion 45 as well as their third connecting portion 46 with rounded shapes as illustrated by FIG. 7.

It can be seen that the noise level of the harmonic linked to the number of pole pairs of the rotor is decreased on the second curve 92 with respect to the first curve 91 and even more diminished on the third curve 93. Such a rotating electrical machine has therefore a noise level of this harmonic reduces and a reduction of the emergence of said harmonic compared to other harmonics.

The present invention finds applications in particular in the field of rotor alternator or reversible machine but it could also apply to any type of rotating machine.

Of course, the foregoing description has been given by way of example only and does not limit the scope of the present invention which would not be overcome by replacing the various elements by any other equivalents.

Claims

1. Rotor for a rotary electric machine, especially for a motor vehicle, comprising:

a rotor body;

at least one fan (25, 26) mounted on the rotor body, said fan having a base (37) and a plurality of blades (39) projecting from the base, each blade (39) presents :

an outer radial end (40),

a first axial end (42) and a second axial end (43) axially opposed to said first end, the first axial end extending continuously from the base (37),

a first connecting portion (44) between the first axial end (42) and the outer radial end (40),

a second connecting portion (45) between the second axial end (43) and the outer radial end (40),

said rotor (12) being characterized in that at least one of the first connecting portion (44) and the second connecting portion (45) has a rounded shape.

2. Rotor according to claim 1, characterized in that the connecting portion (44, 45) extends over a transverse length (L2) greater than an axial thickness (E) of the base (37).

3. Rotor according to claim 1 or 2, characterized in that the connecting portion (44, 45) extends over an axial height (H2) greater than an axial thickness (E) of the base (37).

4. Rotor according to any one of claims 1 to 3, characterized in that the connecting portion (44, 45) has a transverse length (L2) and an axial height (H2), said length (L2) being different from said height (H2).

5. Rotor according to any one of claims 1 to 4, characterized in that the first connecting portion (44) and the second connecting portion (45) has a rounded shape.

Rotor according to claim 5, characterized in that each rounded shape is defined by a radius and at least one center, the radius and / or the at least one center of the rounded shape of the first connecting portion (44). being, respectively, different from those of the second connecting portion (45).

7. Rotor according to any one of claims 1 to 6, characterized in that a blade (39) has, in addition, a third connecting portion (46) between the second axial end (43) and an inner radial end (41), said inner radial end being closer to the axis of the rotor (12), the third connecting portion (46) having a rounded shape.

8. Rotor according to claim 7, characterized in that each rounded shape is defined by a radius and at least one center, the radius and / or the at least one center of the rounded shape of the third connecting portion (46) being , respectively, different from those of the first connecting portion (44) and those of the second connecting portion (45).

9. Rotor according to any one of claims 1 to 8, characterized in that the fan (25, 26) comprises reinforcing ribs (47) extending at least partly on the blades (39), a clearance, in particular greater than an axial thickness of the base (37), being disposed between the first connecting portion (44) and said rib (47).

10. Rotating electrical machine comprising a rotor according to any one of claims 1 to 9, the rotating electrical machine forming an alternator or an alternator-starter or a reversible machine.