EP1735894A1

EP1735894A1 - Rotating electrical machine, in particular motor vehicle alternator, whereof the inputs/outputs comprise fins inclined relative to the fan blades

Info

Publication number: EP1735894A1
Application number: EP05744604A
Authority: EP
Inventors: Claudiu Vasilescu
Original assignee: Valeo Equipements Electriques Moteur SAS
Current assignee: Valeo Equipements Electriques Moteur SAS
Priority date: 2004-03-26
Filing date: 2005-03-25
Publication date: 2006-12-27
Also published as: JP4527765B2; BRPI0509098A; KR20060131982A; FR2869477B1; WO2005093930A1; US20070222311A1; JP2007531481A; CA2549520A1; CN1918772A; AU2005226131A1; FR2869477A1

Abstract

The invention concerns a rotating electrical machine comprising an outer shell (10), a stator, a rotor, and a fan (50) with blades (51) arranged on one first axial side of the rotor, the shell (10) having on its outer periphery radial ports (71) consisting each of an opening (80) subdivided by fins (90) each elongated according to a particular profile of its own, at least one fin (90) of at least one of the radial ports (71) is inclined such that the edges of the blades (51) facing said port sweep gradually across the fin (90) according to its profile while rotating about the rotary shaft, in a shearing movement whereby each time only one substantially point-shaped portion of the edge of the blade (51) is opposite the fin (90).

Description

"Rotating electric machine, in particular a motor vehicle alternator, the air inlets / outlets of which include fins inclined relative to the blades of the fans".

Field of the Invention The invention generally relates to rotary electrical machines, in particular motor vehicle alternators. More specifically, the invention relates to a rotary electric machine, in particular a motor vehicle alternator, comprising a longitudinal axis, an outer casing of hollow form, a stator fixed in the casing, a rotary shaft passing through the stator along the longitudinal axis , a rotor secured to the rotating shaft inside the stator, and a paddle fan driven in rotation by the shaft and disposed on a first axial side of the rotor inside the envelope, this envelope having, on the one hand, at its outer periphery radial louvers and on the other hand, at at least one of its axial ends with axial louvers to constitute air inlet and air outlet louvers arranged so that the fan creates an air flow from the inlet to the outlet, the inlet and outlet louvers each consisting of an opening cut in the envelope and subdivided by mechanical holding fins cha cune elongated according to its own profile.

State of the art

Machines of this type are known from the prior art, and typically comprise cylindrical radial outlet openings, the fins of which have the form of blades extending in respective radial planes. They are particularly noisy when they are fitted with fans, the blades of which also extend in radial planes and which are in motion in front of the fixed obstacles formed by these fins.

Subject of the invention

In this context, the present invention aims to overcome the above-mentioned defect and to provide a particularly silent machine. To this end, the machine of the invention, moreover conforms to the generic definition given by the preamble above, in which a radial hole is formed on a radial face, generally of longitudinal orientation, of the envelope. and has a generally substantially cylindrical shape coaxial with the longitudinal axis, is essentially characterized in that at least one fin, known as a radial fin, of said radial hole, considered in the plane tangent to this hearing at said radial fin, extends in a general direction forming an angle greater than 0 ° with respect to the longitudinal direction so that the edges of the blades of the fan turned towards said hole gradually sweep the radial fin according to its profile by turning around the shaft rotary, according to a shearing movement according to which at each instant only a substantially punctual portion of the edge of the blade is opposite the fin you.

Thanks to the invention, noise and pressure drops are reduced.

More precisely, the shocks between the cooling fluid, such as air, are reduced with the radial fin. The flow of the coolant, such as air, is stabilized with more flow.

The phenomena of vibrations due to turbulence are reduced.

The fan efficiency is therefore improved.

In addition, when the radial opening is an outlet opening, the risks of detachment of the stream of coolant, such as air, are reduced compared to the radial fins. The flow of the coolant is stabilized.

The formation of vortices between the radial fins is limited by making it difficult, if not impossible, a movement of the cooling fluid in the rear direction towards the buns of the stator of the machine, which allows better heat dissipation. In a possible embodiment of the invention, the angle is advantageously less than 30 °. This angle further improves the efficiency of the fan. In a possible embodiment of the invention, the radial inlet or outlet opening may comprise at least one radial fin which, considered in section in a plane perpendicular to the longitudinal axis, is inclined relative to the direction radial to further improve the coolant flow and further reduce noise.

Furthermore, an axial air inlet or outlet opening can be provided on an axial face of the outer casing generally oriented perpendicular to the longitudinal axis, and be delimited on a radially inner side by an edge. substantially circular interior, at least one fin, called an axial fin, of said opening, considered in a plane perpendicular to the longitudinal axis, extending in a general direction forming an angle less than 90 ° relative to the tangent to the inner edge passing through said fin. In this case, the angle is preferably greater than 60 °. The axial fin is preferably inclined according to the direction of rotation of the fan to further reduce the pressure drops and further facilitate the flow of the cooling fluid, such as air. In an advantageous embodiment, the radial hearing comprises at least one radial fin which, considered in section in a plane perpendicular to the longitudinal axis, is inclined relative to the radial direction, while the axial fin, considered in section in a plane perpendicular to the longitudinal axis, is inclined relative to the radial direction in the same direction as the radial fin. Thanks to this arrangement, a better reduction of noise is obtained as well as a very good circulation of the cooling flow such as air. This stabilizes the flow of coolant with even more flow and less noise. The turbulence of the cooling flow passing through the envelope is even more reduced. Advantageously, the radial openings are outlet openings and the axial openings of the inlet openings in the case where electronic means are carried by one envelope. In general, the fan for example can be of the axial, centrifugal, helico-centrifugal, centripetal or helico-centripetal type, so that the vents can be air outlet or inlet vents. Advantageously, the machine can comprise a second fan with blades driven in rotation by the shaft and disposed on a second axial side of the rotor opposite to the first inside the envelope, this envelope having second inlet openings d 'air and air outlet arranged so that the second fan creates an air flow from the inlet to the outlet, the second inlet and outlet openings each consisting of an opening cut in the envelope and subdivided by mechanical retaining fins each elongated according to its own profile, at least one fin of at least one of the second inlet and / or outlet openings being inclined so that the edges of the blades of the second fan turned towards said hearing progressively sweep the fin according to its profile by turning around the rotary shaft, according to a shearing movement according to which at each instant only a substantially punctual portion of the fin is opposite the edge of the blade. The machine may also have one or more of the following characteristics. The fins have, perpendicular to their profile, a section of constant size. The fins have, perpendicular to their profile, a section of variable size along this profile to further reduce aerodynamic resistance. The fins have, perpendicular to their profile, a rectangular section. The fins have, perpendicular to their profile, a round section. The fins have, perpendicular to their profile, an elliptical section. The fins have, perpendicular to their profile, a relatively thicker profiled section on a radially inner side and relatively thinner on a radially outer side to further reduce aerodynamic resistance. The fins have a straight profile. The fins have a curved profile. At least one of the fins of at least one of the inlet and outlet openings has an edge facing the inclined fan so that the edges of the blades facing towards said outlet progressively sweep said edge of the wing in rotating around the rotating shaft, to further increase the flow rate and further reduce noise. All of these features are to be considered in isolation and / or in combination.

Thanks to the invention, the flow rate of the coolant, such as air, can be increased without increasing the noise.

Brief description of the drawings

Other characteristics and advantages of the invention will emerge clearly from the description which is given below, at. indicative and in no way limiting, with reference to the appended figures, among which: FIG. 1 is a half-view in longitudinal section of a rotary electrical machine according to the invention, FIG. 2 is a partial perspective view of the Figure 1, showing the respective positions of the fan blades and the air outlet fins, Figure 3 is a side view in a centripetal radial direction, according to arrow III of Figure 2, Figure 4 is a axial view along arrow IV of FIG. 1, showing the respective positions of the fan blades and the air inlet fins, Figure 5 is a view similar to that of Figure 3, for an alternative embodiment in which the fins are curved, and Figure 6 is a partial sectional view in a plane perpendicular to the longitudinal axis, considered under 1 ' incidence of arrows VI in FIG. 1.

Description of embodiments of the invention

The rotary electrical machine represented in FIG. 1 is a polyphase alternator of a motor vehicle with internal ventilation, comprising an outer casing 10 of hollow form, a stator 20 fixed in the casing 10, a rotary shaft 30 passing through the stator 20 along an axis longitudinal, and a rotor 40 integral with the shaft 30 rotating inside the stator 20. The axis of the shaft 30 defines the longitudinal axis. The stator 20 typically comprises a cylindrical body coaxial with the longitudinal axis, formed of a pack of sheets 21 on the radially inner face of which are formed a series of axially traversing notches, extending in respective radial planes, and phase windings arranged inside the notches and forming on two opposite axial sides of the sheet package 21 stator buns 22 extending substantially in the axial extension of the sheet package 21. There is at least one winding per phase that includes the alternator. The windings can be of the type with separate coils, with entangled coils or of the bar type, for example in the shape of a U as described in document WO 92/06527. The rotor 40 comprises two pole claw wheels 41 and an excitation winding 42 disposed between the pole wheels 41. Each pole wheel 41 has a flange extending substantially perpendicular to the longitudinal axis, carrying at its periphery teeth 43 of axial orientation directed towards the flange of the other pole wheel. The teeth of the two wheels are circumferentially offset and interpenetrate, so that one finds following the circumference of the rotor alternately teeth belonging to the two wheels. These teeth each have a generally trapezoidal shape, and point towards the opposite pole wheel. The flanges are each pierced with a central bore receiving the rotary shaft 30, and are secured to this rotating shaft by ribs, such as knurling, cooperating with grooves made in the shaft 30. The winding 42 is disposed under the teeth 43, that is to say on a radially inner side thereof, and is wound around a core. The core is interposed axially between the two flanges of the pole wheels 41, 42. This core is in an embodiment distinct from the flanges of the pole wheels 41, 42. As a variant, as shown in FIG. 1, the core is in two parts, each part being from one of the flanges. The wheels and the core are preferably made of ferromagnetic material. When the winding 42 is electrically powered, the teeth of one of the pole wheels 41 define North poles, while the teeth of the other pole wheel 42 define South poles. The rotor 40 rotates inside the stator 20, a determined air gap separating the radially outer face of the rotor 40, defined by the teeth 43, from the inner face of the stator, defined by the pack of sheets 21. The casing 10, forming a housing, is intended to be fixed to the vehicle and has a generally cylindrical shape coaxial with the longitudinal axis. This envelope is preferably made of moldable material. It is made for example of aluminum, or of an alloy comprising aluminum. It is divided along a median plane perpendicular to the longitudinal axis into two cylindrical parts called front and rear bearings 11 and 12 of hollow form, each comprising a radial face 13 substantially of longitudinal orientation and an axial face 14, 15 substantially perpendicular to the longitudinal axis, closing the radial face on one side, the other side of the radial face remaining open. In FIG. 1, the radial 13 and axial 14, 15 faces are respectively of longitudinal orientation and of orientation perpendicular to the longitudinal axis. As a variant, the radial and axial faces can be inclined so that each bearing 11, 12 has at its external periphery a radial face substantially of longitudinal orientation and at one of its axial ends an axial face substantially of orientation perpendicular to the 'longitudinal axis. The front and rear bearings 11 and 12 are applied to the body 21 of the stator by the open sides of their respective radial faces and fixed to one another, for example by tie rods not shown, the axial faces of the front bearings and rear 11 and 12 thus constituting respectively the front and rear axial faces 14 and 15 of the outer casing 10. As a variant, the bearings 11, 12 are applied to one another by the open sides of their radial faces. The front and rear axial faces 14 and 15 are pierced by respective central openings each receiving a ball bearing 31, these bearings supporting the front and rear end parts 32 and 33 of the shaft 30. The front end part 32 is extends axially beyond the front axial face 14, to carry a movement transmission member 34 in the form of a pulley, which is fixed on this part outside of the casing 10 and is integral in rotation with the shaft 30, here by means of a nut (not referenced) mounted on the threaded end of the front end 32. Thus the pulley is intended to cooperate with a V-grooved belt (not shown) by which the heat engine of the motor vehicle drives the shaft 30 and the whole of the rotor 40 when the electric machine, in this case the alternator, operates in electric generator mode, in particular for recharging the vehicle battery and supplying the consumers of the vehicle on-board network. As a variant, the alternator is reversible and operates in generator mode, as mentioned above, and in electric motor mode. This pulley and the belt associated with it also allow the electric machine to drive the motor in the opposite direction. thermal, when said machine operates in starter mode in particular to start the thermal engine. Such a reversible alternator is called an alternator-starter and is described in more detail, for example in document WO 01/69762 to which reference will be made for more details. The transmission of movement between the shaft 30 and the alternative engine of the vehicle may comprise gears, at least one chain of pulleys with variable spacing, and / or at least one belt. Thus, the movement transmission member 34 can have many configurations and consist of a gear, a toothed wheel, a pulley, etc. The rear end portion 33 of the shaft 30 carries rings 35 connected by wire connections at the ends of the winding 42, these rings being arranged outside the casing 10. The rear bearing 12 carries on an outside side of the casing 10 a brush-carrying member 121 carrying brushes cooperating with the rings 35, a voltage regulator connected to the winding 42 via the brushes of the brush-holder 121 and electronic means 122 for rectifying the alternating current produced by the alternator and for controlling the machine. These means typically include the voltage regulator for controlling the excitation winding of the machine and a rectifier bridge for the alternating current produced by the stator. This bridge is connected to the phase windings of the stator and is for example a diode bridge, two of these diodes mounted head to tail being visible in FIG. 1, or a transistor bridge of the MOSFET type in the case of an alternator-starter. . There are also provision for connection terminals to the electrical circuit of the vehicle, at least one of these terminals being for example carried by the electronic means 122. The diode bridge here comprises at least six diodes at the rate of at least three diodes , say negative diodes, carried by the rear bearing and at least three diodes, say positive diodes carried by a dissipator. The bridge may alternatively include twelve diodes as described in document WO 03/009452 to which reference will be made. The machine further comprises a cover 5, for example made of perforated plastic, fixed to the rear bearing 12 on an outside side of the rear axial face 15 of the casing 10, and covering the brush holder member 121 and the voltage regulator as well as the rectifier bridge of the electronic means 12. Of course, as a variant, the rectifier bridge and / or the voltage regulator of the electronic means 122 are mounted in an external box connected by a device for connection to the rotating electric machine. The casing 10 has, on a first axial side of the rotor 40, for example on the rear side, at least one hearing axial 61 formed in the rear axial face 15, and at least one radial hole 71 formed in the radial face 13 of the rear bearing 12. The holes 61, 71 are formed respectively at one of the axial ends of the casing and at the outer periphery of the envelope as described below. The machine further comprises, for example on the rear side, a fan 50 with blades 51 rotated by the shaft 30 and disposed on the first axial side of the rotor 40 inside the casing 10. Likewise, the casing 10 has, on a second axial side of the rotor 40, for example on the front side, at least one second axial hole 62 formed in the front axial face 14, and at least one second radial hole 72 formed in the radial face 13 of the bearing before 11. The machine also comprises a second fan 55 with blades driven in rotation by the shaft 30 and disposed on the second axial side of the rotor 40 inside the casing 10. The fans 50, 55 are integral with the rotor by for example by welding points or by crimping. In this embodiment, the envelope has several axial and radial openings which are respectively air inlet and outlet openings. The axial air inlet vents 61/62 and radial air outlet vents 71/72 are (FIG. 2) each constituted by an opening respectively 180, 80 cut from the envelope 10 and subdivided by fins respectively 190 , 90 each stretched out according to its own profile. The shape of this fin 90 when we follow it over its greatest length is therefore called the profile of a fin 190.90. Note that the number of radial louvers is greater than the number of axial louvers. In a plane perpendicular to its profile, each radial fin 90 has a section of small dimensions with regard to its length along its profile. The openings 180 of the axial openings 61/62, substantially perpendicular to the longitudinal axis (FIGS. 1 and 4), each favorably have the general shape of a ring sector centered on the longitudinal axis and surrounding the bearing 31, and are delimited by inner and outer circular edges 801 and 802. The fins 190 connect the edges 801, 802 to each other. For simplicity, not all the fins 190 have been shown in FIG. 4. The edge 801 delimits the external periphery of a sleeve delimiting a housing for mounting the bearing 31 concerned in FIG. 1. This sleeve is not referenced in FIG. 1. The edge 802 delimits the internal periphery of a zone 803 affected at its external periphery by the openings 80 of the radial openings 72/71. In FIG. 1, this zone 803 is a zone for mounting the diodes of the rectifier bridge fitted here by force into the axial face 15 of the rear bearing 12. As a variant, these diodes are brazed on the axial f 15. The openings 80 of the radial louvers 72/71 (FIGS. 1 to 3), generally of longitudinal orientation, have a generally cylindrical shape of revolution around the longitudinal axis, comprising a cylindrical part 81 respectively constituting the front or rear end of the radial face 13, extended by an annular part 82 constituting the outer edge respectively of the front and rear axial faces 14/15. The part 82 makes it possible to obtain the gills 72/71 by demolding and affects the area 803. The cylindrical parts 81 extend opposite the chignon 22 of the stator 20 and are delimited on the side of the median plane of the casing 10 by edges respective central circulars 811 adjacent to the sheet metal package 21. The annular portions 82 are delimited on a radially inner side by respective lateral circular edges 821. The parts 82 are generally perpendicular to the longitudinal axis. The fins 90 of the same radial opening have the same general shape, and are favorably regularly spaced at the outer periphery of the envelope 10, locally dividing the latter into a plurality of openings 80 in the form of sectors of the same general shape. (figure2). It is the same for the fins 190 The radial fins 90 of the radial vents 71/72 are each secured by one end of the central edge 811, here delimiting a strip of material which extends to the free open end of the axial face 13, and by the opposite end of the lateral edge 821 belonging to the axial face 14/15. The axial fins 190 of the axial vents are, as mentioned above, each secured by one end of the inner circular edge 801 and by the opposite end of the outer circular edge 802. These fins 90, 190 both have a mechanical connection function between different parts of the bearing, and a function of dissipation of the thermal energy released by the machine in operation. The fans 50/55 each comprise a hub 52 typically extending in a plane perpendicular to the longitudinal axis, this hub being typically pressed and fixed, for example by welding points, on the flange of the pole wheel 41 located on the corresponding axial side, rear and front sides respectively. The hub 52 can be solid or cut. The blades 51 of the fans 50/55 are thin webs, extending axially from the hub 52 respectively backwards and forwards. In an exemplary embodiment, the fans 50/55 are centrifugal and the blades 51 are arranged in radial planes and regularly distributed angularly around one longitudinal axis. They may for example each have a generally rectangular shape, delimited on a radially outer side by an outer edge 511 straight axial turned towards the radial hole 71/72, and on an axial front or rear side by a radial edge 512 straight facing the axial hearing 62/61. When the rotor 40 is rotated by the shaft 30, the fans 50/55 create currents of coolant, here air, inside the casing 10, represented by the arrows in the figure 1. In general, for simplicity, the cooling fluid will be called air. The air penetrates axially through the axial vents 61/62 acting as air inlets, is propelled radially through the chignon 22, and leaves the envelope 10 through the radial vents 71/72 serving as outlet outlets. air. According to a characteristic of the invention, at least one radial fin 90 of at least one of the radial openings is inclined so that the edges of the blades 51 facing towards said openings gradually sweep the fin 90 according to its profile by turning around of the rotary shaft 30, according to a shearing movement in which at each instant only a substantially punctual portion of the edge of the blade 51 is opposite the fin 90. It is preferably the same in this case which relates to the axial vanes 190 of at least one of the axial apertures, which is inclined so that the edges of the blades 51 turned towards said aperture gradually sweep the fin 190 according to its profile by rotating around the rotary shaft 30 , according to a shear movement according to which at each instant only a substantially punctual portion of the edge of the blade 51 is opposite the fin 190. As a variant, the axial fin is not inclined. Preferably, these are all the radial 90 and axial fins 190 of all the air inlets and outlets which are inclined. The fins 90, 190 in one embodiment are inclined in the opposite direction by considering the direction of rotation of the fan concerned. Preferably, according to one characteristic, the fins 90, 190 are inclined in the same direction as the direction of rotation of the fan. Thus, in a plane perpendicular to its profile, each radial fin has a section of small dimensions with regard to its length along its profile, this section belongs to an axial part, hereinafter called butt, inclined circumferentially in the same direction as an axial fin 190. According to a characteristic, therefore, the radial hearing (71) comprises at least one radial fin 90 which, considered in section in a plane perpendicular to the longitudinal axis, is inclined relative to the radial direction. The axial hole 61 comprises at least one axial fin 190 which, considered in section in a plane perpendicular to the longitudinal axis, is inclined relative to the radial direction in the same direction as the radial fin 90.

We will first describe a first embodiment in which the fins 90, 190 are substantially straight, corresponding to FIGS. 2 to 4. As can be seen in FIG. 2, the radial fins 90 of the radial opening 71 each have a profile consisting of a straight portion extending in the cylindrical part 81 of an opening 80, and of a stock extending the straight portion and extending in the annular part 82. The straight portion is not parallel to the longitudinal axis, but on the contrary extends in a direction inclined relative to this axis. As can be seen in FIG. 3, each radial fin 90 of the radial hearing 71, considered in the plane tangent to said hearing 71 at the level of said wing, extends in a general direction which is specific to it. In the embodiment illustrated here, this general direction is a straight line inclined relative to the longitudinal axis, corresponding to the direction in which the first portion of the fin 90 extends. This general direction forms an angle α greater at 0 ° to the longitudinal direction. In a preferred embodiment, the angle α is less than 30 °, the optimum being reached for an angle of the order of 15 °. Such an angle allows the fins to fulfill their mechanical connection function between the radial and axial faces of the bearings very satisfactorily, while significantly reducing the noise associated with the rotation of the fan. It is clearly seen in Figure 3 that, due to the different orientations of the blade 51 and the fin 90, only a very short portion of the outer edge 511 of the blade 51 is opposite an inner edge 91 of the fin 90 at all times. Said portion varies while the blade 51 rotates. In the embodiment illustrated in FIG. 3, it is first a rear end portion of the outer edge 511 which is located opposite a central part of the fin 90. When the blade 51 rotates, said portion moves forward, this portion being progressively opposite a part of the inner edge 91 of the fin 90 which shifts forward. It will be noted that the fin 90 can be inclined either, as in FIG. 3, so that the blade 51 moves from the rear towards the front along the fin 90, either in the opposite direction, so that the blade moves from front to rear along the fin 90, as illustrated in FIG. 5. Furthermore, the fins 90 typically have sections perpendicular to their elongated profiles in a main direction. substantially radial. In an alternative embodiment illustrated in FIG. 6, this main direction is inclined relative to the radial direction, with an angle adapted so that said main direction is parallel to the flow of air passing through the radial opening 71. As seen in Figure 4, the fins 190 of the axial hole 61 each have a straight profile. This profile is not radial, but on the contrary extends in a direction inclined with respect to the radial direction. Considered in a plane perpendicular to the longitudinal axis, these fins 90 extend in a general direction forming an angle β less than 90 ° relative to the tangent to the inner edge 801 passing through the end of said fin 90 integral with said edge 801. In a preferred embodiment, the angle β will be greater than 60 °, the optimum being reached for an angle β of the order of 70 °. Such an angle allows the fins to fulfill their mechanical connection function between the radially inner and outer parts of the axial faces very satisfactorily, while significantly reducing the noise associated with the rotation of the fan. It is clearly seen in Figure 4 that, due to the different orientations of the blade 51 and the fin 90, only a very short portion of the edge radial 512 of the blade 51 is opposite the edge of the fin 90 facing the fan at all times. Said portion varies while the blade 51 rotates. In the embodiment illustrated in FIG. 4, it is first of all an outer portion of the radial edge 512 which is opposite the end of the fin 90 secured to the outer circular edge 802. When the blade 51 turns, said portion moves inward, this portion being progressively opposite a portion of the edge of the fin 90 which shifts inward. It will be noted that the fin 190 can be inclined indifferently either, as in FIG. 4, so that the blade 51 moves from the outside towards the inside along the fin 90, either in the opposite direction, so that the blade moves from the inside to the outside along the fin 90. We will now describe a second embodiment in which the fins 90 of the radial opening 71 have curved profiles, reference to FIG. 5. Only the points which differ from the first embodiment will be detailed. Each fin 90 of the radial hearing 71, considered in the plane tangent to said hearing 71 at the level of said fin, has a profile of curved shape, in an arc of a circle elongated in a first general direction specific to it, of concavity. turned to the circumferential side towards which the blades move 51. The concavity could also be turned to the opposite circumferential side. In the embodiment illustrated here, the first general direction is a straight line D inclined with respect to the longitudinal axis, shown in FIG. 5, and corresponding substantially to the straight line passing through the two opposite ends by which the fin 90 is attached to the central circular edge 811 and to the lateral circular edge 821. This first general direction forms with respect to the longitudinal axis an angle α greater than 0 °, preferably less than 30 °, 15 ° constituting an optimum. The inner edge of the fin 90 follows a curve substantially parallel to the profile of said fin. As described above, the fin 90 with a curved profile may also have, at right angles to its profile, an inclined section. The fins 190 of the axial openings 61/62 can also have curved profiles. It will be noted that the blades 51 may not extend in radial planes, but rather in planes inclined relative to the radial planes, or even have curved shapes. In these cases, the edges of the blades turned towards the fins can respectively be oblique or curved. The fins are then arranged so that these oblique or curved edges progressively travel through the fin according to its profile, as explained above. The fins 90, 190 of the inlet and outlet openings may also have sections of variable sizes along their profile. These sections can for example be relatively larger on a radially inner side and relatively smaller on a radially outer side for the axial vents 61/62. There have been described above fins 90, 190 whose profile was straight or in an arc. The fins may have other shapes of profiles, for example forming waves, or made up of several line segments of different inclinations, or any other possible shape different from a line parallel to the axis of rotation. The fins 90, 190 may further extend along a curved surface, for example a portion ellipsoid or a portion of another quadric surface. The edge of the fin facing the fan may then not be parallel to the profile of the fin. In this case, it will be sought to obtain that the edge of the fin and its profile are both inclined with respect to the edges of the blades facing the fins. The fan of the machine described above may not be centrifugal, but rather of the helico-centrifugal, axial, centripetal or helico-centripetal type. In the case of a helical-centrifugal fan, the axial hole constitutes the air inlet, and the radial hole is offset axially relative to the fan towards the side of the machine opposite to the inlet hole and constitutes the exit hearing. The air flow passing through the outlet opening forms an angle between 0 and 90 ° relative to the longitudinal axis. In the case of an axial fan, the axial opening constitutes the air inlet, the casing not comprising a radial opening but comprising another axial opening on the side opposite to the first constituting the air outlet. The fan can also be centripetal or helico-centripetal, in which case the envelope comprises a radial opening constituting the air inlet and an axial opening constituting the air outlet. The radial hole is located axially at substantially the same level as the fan in the case of a centripetal fan, and is offset axially towards the side opposite to the axial hole in the case of a helical-centripetal fan. It is therefore clear that the machine described above has multiple advantages. Because the blades progressively scan the fins by following the profiles of these fins, the noise generated by the crossing of a given blade and a given fin is greatly reduced. This noise is much stronger when the blade appears parallel to the fin. The invention applies to all types and shapes of blades, and to all types and shapes of fins. The blades can be arranged in radial planes or not, have planar or curved shapes. The fins may have straight or curved profiles, sections inclined in a plane perpendicular to their profile. It applies to machines fitted with all types of fans, centrifugal, helico-centrifugal, axial, centripetal or helico-centripetal. The blades of these fans may have external edges 511 inclined relative to the longitudinal axis. They may also have edges 512 facing forwards or backwards that are not radial, concave, convex, S-shaped, or others. The blades can be distributed angularly in a non-regular manner around the axis of rotation, and not symmetrical with respect to a plane containing this axis. Finally, the axial openings 71/72 can be arranged on axial faces 14/15 which are not perpendicular to the longitudinal axis, for example inclined at an angle of less than 90 ° relative to this axis, or on faces slightly curved axial, for example in portions of spheres. The invention also applies to machines comprising a rotor with salient poles. As a variant, the machine comprises a rotor with salient poles alternating with permanent magnets as described in document WO 02/0545566. The rear fan 51, more powerful than the front fan 51, can be a double fan comprising two series of blades as described for example in document WO 2004/106748. This is made possible because, thanks to the invention, it is possible to increase the flow rate of the cooling air passing through the casing 10 without increasing the noise. The presence of the front fan is not mandatory. One of the bearings 11, 12 may have a chamber for the circulation of a cooling fluid, such as the cooling fluid of the thermal engine of the vehicle. The envelope 10 may have more than two parts. For example, the bearings 11, 12 can be mounted on either side of a central part internally carrying the package of stator sheets. This central part can carry a cooling chamber. The openings 80, 180 of the radial or axial openings may not have a symmetry of revolution around the shaft 30, but rather have an elongated oblong shape in a determined radial direction.

Claims

1. Rotating electric machine, comprising a longitudinal axis, an outer casing (10) of hollow form, a stator (20) fixed in the casing (10), a rotary shaft (30) passing through the stator (20) according to the longitudinal axis, a rotor (40) integral with the shaft (30) rotating inside the stator (10), and a fan (50) with blades (51) driven in rotation by the shaft (30) and disposed on a first axial side of the rotor (40) inside the casing (10), this casing (10) having on the one hand, at its external periphery, radial openings (71, 72) and on the other hand, at at least one of its axial ends, axial openings (61, 62) to constitute air inlet and air outlet openings arranged in such a way that the fan (50) creates a flow of air from the inlet to the outlet, the inlet and outlet openings each consisting of an opening (80, 180) cut from the envelope (10) and subdivided by fins (90,190) mechanical support, each elongated according to its own profile, in which a radial opening (71) is formed on a radial face (13) generally of longitudinal orientation, of the casing (10) and has a generally substantially cylindrical shape coaxial with the longitudinal axis, characterized in that at least one fin (90), called a radial fin, of said radial opening (71), considered in the plane tangent to this opening (71) at the level of said radial fin, extends in a general direction forming an angle greater than 0 ° with respect to the longitudinal direction so that the edges of the blades (51) of the fan turned towards said opening progressively sweep the radial fin (90) according to its profile in rotating around the rotary shaft (30), in a shearing movement in which at each instant only a substantially portion point of the edge of the blade (51) is opposite the fin (90).

2. Machine according to claim 1, characterized in that the angle is less than 30 °.

3. Machine according to claim 1, characterized in that the radial hole (71) comprises at least one radial fin (90) which, considered in section in a plane perpendicular to the longitudinal axis, is inclined relative to the direction radial.

4. Machine according to claim 1, characterized in that at least one axial hole (61) is formed on an axial face of the outer casing (10), generally of orientation perpendicular to the longitudinal axis, and is delimited on a radially inner side by a substantially circular inner edge (801), at least one fin (190), called the axial fin, of said opening, considered in a plane perpendicular to the longitudinal axis, extending in a general direction forming an angle less than 90 ° relative to the tangent to the inner edge (801) so that said axial fin, considered in section in a plane perpendicular to the longitudinal axis, is inclined relative to the radial direction.

5. Machine according to claim 4, characterized in that the angle is greater than 60 °. 6 Machine according to claim 4, characterized in the radial opening (71) comprises at least one radial fin (90) which, considered in section in a plane perpendicular to the longitudinal axis, is inclined relative to the radial direction and in this that the axial fin (190), considered in section in a plane perpendicular to the longitudinal axis, is inclined relative to the radial direction in the same direction as the radial fin (90). .7. Machine according to claim 1, characterized in that the radial fins (90) have, perpendicular to their profile, a section of constant size. 8. Machine according to claim 1, characterized in that the radial fins (90) have, perpendicular to their profile, a section of variable size along this profile. 9. Machine according to claim 8, characterized in that the fins (90) have a curved profile. 10. Machine according to claim 1, characterized in that at least one of the fins (190,90) of at least one of the axial and radial vents (61, 71) has an edge facing the fan (50) inclined so that the edges of the blades (51) of the fan (50) turned towards said opening progressively sweep said edge of the fin (90) by turning around the rotary shaft (30).