WO2017093640A1

WO2017093640A1 - Claw rotor for a rotary electric machine having at least one chamfer produced in a claw

Info

Publication number: WO2017093640A1
Application number: PCT/FR2016/053094
Authority: WO
Inventors: Mostafa Kadiri; Amar DJEBBAR; Stéphane Desenclos; Benjamin Pouchelle; Stéphane CALON; Lionel MOMONT; Daniel BOUCLET
Original assignee: Valeo Equipements Electriques Moteur
Priority date: 2015-12-01
Filing date: 2016-11-25
Publication date: 2017-06-08
Also published as: FR3044485B1; CN108702045B; CN108702045A; DE112016005490T5; FR3044485A1

Abstract

The invention primarily relates to a rotor of a rotary electric machine of a motor vehicle, comprising at least one pole wheel (24, 25) comprising a plurality of claws (29), at least one claw (29) comprising: - a base (53) and an axially opposite free end (54), - a leading edge (51) and a trailing edge (52) extending between the base (53) and the free end (54), - a chamfer (57) produced in the trailing edge (52), the rotor being characterised in that a ratio of a width (CB1) of said chamfer (57) measured at the base (53) to a width (LB1) of the base of the claw (29) is between 0.17 and 0.23.

Description

ROTOR WITH CLUTCHES OF A ROTATING ELECTRIC MACHINE WITH AT LEAST ONE CHAMFER IN A CLUTCH

The present invention relates to a rotor rotor with rotary electric machine provided with at least one chamfer made in a claw. The invention finds a particularly advantageous, but not exclusive, application in the field of alternators and reversible electric machines for a motor vehicle. Such an alternator transforms mechanical energy into electrical energy. A reversible machine also makes it possible to convert electrical energy into mechanical energy, in particular to start the engine of the vehicle.

In a manner known per se, an alternator as described in document EP0762617 comprises a housing and, inside thereof, a claw rotor, fixed in rotation directly or indirectly to a shaft, and a stator which surrounds the rotor with the presence of a gap. A pulley is attached to the front end of the shaft.

The stator comprises a body in the form of a pack of sheets with notches equipped with notch insulation for mounting the stator winding. The coil comprises a plurality of phase windings passing through the notches of the body and forming, with all the phase windings, a front bun and a rear bun on either side of the stator body. The windings are obtained for example from a continuous wire coated with enamel or from bar-like conductor elements, such as U-shaped pins whose ends are interconnected for example by welding. These phase windings are, for example, three-phase windings connected in a star or in a triangle, the outputs of which are connected to at least one electronic rectification module comprising rectifying elements, such as diodes or transistors.

In addition, the rotor has two pole wheels. Each pole wheel has a flange of transverse orientation provided at its outer periphery claws for example of trapezoidal shape and axial orientation. The claws of one wheel are directed axially towards the flange of the other wheel. Each claw of a pole wheel enters the space between two claws adjacent to the other pole wheel, so that the claws of the pole wheels are nested relative to each other. A cylindrical core is interposed axially between the flanges of the wheels. This core carries at its outer periphery an excitation coil wound in an insulator radially interposed between the core and this coil.

It is known that this type of electrical machines emits an acoustic phenomenon due to the vibrations generated by the magnetic forces present. This acoustic phenomenon such as noise of magnetic origin is noticeable in a low rotation speed range, in particular between 1800 and 4000 rev / min and can cause discomfort. In fact, beyond the aeraulic noise of the fan covers the magnetic noise so that it is no longer necessary to reduce the latter. The aim of the invention is to effectively minimize magnetic noise by proposing a motor vehicle rotating electrical machine rotor comprising at least one pole wheel comprising a plurality of claws, at least one claw comprising:

a base and an axially opposite free end,

a leading edge and a trailing edge extending between the base and the free end,

a chamfer made in the trailing edge,

the rotor being characterized in that a ratio of a width of said chamfer measured at the base to a width of the base of the claw is between 0.17 and 0.23.

Such a chamfer configuration makes it possible to obtain a significant decrease in the sound level (of the order of 5 dB) without degrading the magnetic performance of the electric machine.

According to one embodiment, a ratio of a chamfer width measured at the free end of the claw over a width of the free end of the claw is between 0.34 and 0.5.

According to one embodiment, another chamfer is made in the edge attacking at least one claw.

In one embodiment, a ratio of a width of said other chamfer measured at the base of the claw over a width of the base of the claw is between 0.09 and 0.20. According to one embodiment, a ratio of a width of said other chamfer measured at the free end of the claw over a width of the free end of the claw is between 0.1 and 0.35.

In one embodiment, a chamfer surface decreases as one moves toward the free end of the corresponding claw. In one embodiment, the claw has an outer radial surface and the chamfer is formed on said outer radial surface.

In one embodiment, the chamfer extends axially between the base and the free end of the corresponding claw.

In one embodiment, a radial section of the chamfer extends along a straight line.

In one embodiment, said rotor comprises a first pole wheel and a second pole wheel and the claws of the two pole wheels are symmetrical.

In one embodiment, said rotor comprises a first pole wheel and a second pole wheel and the claws of the two pole wheels are asymmetrical.

According to one embodiment, the claws of one of the pole wheels are inclined in the direction of rotation of the rotor and the claws of the other pole wheel are inclined in the opposite direction to said direction of rotation, so as to have an inter-claw gap with parallel edges. Such a configuration allows easy integration of interpolar magnets of standard form between two successive claws.

In one embodiment, the claws of the pole wheels are inclined in the same direction. According to one embodiment, said rotor comprises a first pole wheel and a second pole wheel and the claws of one of the pole wheels are symmetrical and the claws of the other pole wheel are asymmetrical.

The subject of the invention is also a rotating electrical machine of the alternator type or a reversible machine characterized in that it comprises a rotor as defined above.

The invention will be better understood on reading the description which follows and on examining the figures which accompany it. These figures are given for illustrative but not limiting of the invention. Figure 1 is a schematic longitudinal sectional view of an alternator according to the present invention;

Figure 2 is a schematic top view of the pole wheels of a rotor according to the present invention, the claws are provided with double chamfers; FIG. 3 is a diagrammatic view from above showing the dimensions of the claws of the pole wheels involved in the definition of the specific ratios of the rotor according to the present invention;

FIG. 4 is a graph showing two curves representing the magnetic noise level of a three-phase alternator as a function of the speed of the machine respectively for a standard rotor and for a rotor according to the invention;

Fig. 5 is a schematic cross-sectional view of a polar wheel claw according to the present invention;

Figures 6a to 6c show schematic embodiments of the rotor according to the present invention provided with at least one asymmetrical claw pole wheel.

Identical, similar or similar elements retain the same reference from one figure to another. In the following description, it is considered that a "front" element is located on the side of the pulley of the machine and that a "back" element is located on the opposite side.

FIG. 1 shows a compact and polyphase alternator 10, in particular for a motor vehicle. This alternator 10 transforms mechanical energy into electrical energy and can be reversible. Such a reversible alternator 10, called an alternator / starter, makes it possible to convert electrical energy into mechanical energy, in particular to start the engine of the vehicle.

This alternator 10 comprises a housing 1 1 and, inside thereof, a claw rotor 12 mounted on a shaft 13, and a stator 16, which surrounds the rotor 12 with the presence of an air gap 17. A pulley 14 is attached to the shaft 13. This pulley belongs to a belt motion transmission device between the alternator 10 and the engine of the motor vehicle. The axis X of the shaft 13 forms the axis of rotation of the rotor 12.

The stator 16 comprises a body 19 in the form of a pack of sheets provided with notches, for example of the semi-closed type, equipped with slot insulator for mounting the phases of the stator 16. Each phase comprises at least one winding through the notches of the body 19 of the stator 16 and forms, with all phases, a front bun 20 and a rear bun 21 on either side of the stator body 19. The windings are obtained for example from a continuous wire covered with enamel or from conducting elements in the form of bar, such as pins connected together for example by welding. These windings are, for example, three-phase windings or windings comprising more than three phases connected in a star or in a triangle, the outputs of which are connected to at least one rectifier bridge comprising rectifying elements such as diodes or transistors of the MOSFET type, in particular when it is an alternator-starter as described for example in the document FR2745445.

The rotor 12 comprises two pole wheels 24, 25 each having a flange 28 of transverse orientation provided at its outer periphery with claws 29 for example of trapezoidal shape and axial orientation. The claws 29 of a wheel 24, 25 are directed axially towards the flange 28 of the other wheel. Each claw 29 of a pole wheel 24, 25 enters the space between two claws 29 adjacent to the other pole wheel, so that the claws 29 of the pole wheels 24, 25 are interleaved with each other. The outer periphery of the claws 29 defines with the inner periphery of the body 19 of the stator 16 the gap 17 between the stator 16 and the rotor 12. The inner periphery of the claws 29 is inclined, so that the claws 29 are thinner on the side their free end 54.

A cylindrical core 30 is interposed axially between the flanges 28 of the wheels 24, 25. In this case, the core 30 consists of two half-cores each belonging to one of the flanges 28. This core 30 carries at its outer periphery a excitation coil 31 wound in an insulator 32 interposed radially between the core 30 and the coil 31.

In addition, the casing 1 1 comprises front 35 and rear 36 bearings assembled together. The bearings 35, 36 are of hollow form and each bear a central bearing 37, 38 ball for the rotational mounting of the shaft 13 of the rotor. The rear bearing 36 carries a brush holder 40 provided with brushes 41 intended to rub against rings 44 of a manifold 45 connected by wire bonds to the excitation coil 31. The brushes 41 are electrically connected to a voltage regulator mounted outside the machine.

The front and rear bearings comprise substantially lateral front and rear openings 61 to allow the cooling of the alternator 10 by air circulation generated by the rotation of a fan 62 positioned on the front face of the rotor and another fan 63 positioned on the rear face of the rotor. Each fan 62, 63 is provided with a plurality of blades 64. The front lateral openings 60 and rear 61 are opposite the bunches respectively before 20 and rear 21.

More specifically, as can be seen in Figures 2 and 3, each claw 29 trapezoidal shape comprises a leading edge 51 entering first into contact with the air in the direction of rotation of the rotor 12 indicated by the arrow SR and a trailing edge 52 located on the opposite side from the leading edge 51. These edges 51, 52 extend between the base 53 of the claw 29, which coincides locally with the outer periphery of the flange 28 corresponding, and the free end 54 of the claw 29. The free end 54 is axially opposed relative at the base 53. In this case, a first chamfer 57 is made in the trailing edge 52 of each claw 29 of the pole wheels 24, 25, and a second chamfer 57 'is formed in the leading edge 51 of each claw 29 of the pole wheels 24, 25. The chamfers 57, 57 'are formed on the outer radial surface 56 of the corresponding claw 29. Each chamfer 57, 57 'extends axially between the base 53 and the free end 54 of the corresponding claw 29.

The surface of the chamfers 57, 57 'in this case of generally triangular shape decreases when moving towards a free end 54 of the claw 29. The surface of the chamfers 57, 57' is substantially zero at the end. free 54 of the claw 29.

Advantageously, a first ratio CB1 / LB1 between a width CB1 of the first chamfer 57 measured at the base 53 and a width LB1 of the base 53 of the claw 29 is between 0.17 and 0.23. Preferably, a second ratio Ce1 / LE1 between a width Ce1 of the first chamfer 57 measured at the free end 54 of the claw 29 and a width LE1 of the free end 54 of the claw 29 is between 0.34 and 0.5. .

Preferably, a third ratio CB2 / LB1 between a width CB2 of the second chamfer 57 'measured at the base 53 of the claw 29 and a width LB1 of the base 53 of the claw 29 is between 0.09 and 0.20. Still preferably, a fourth ratio Ce2 / LE1 between a width Ce2 of the second chamfer 57 'measured at the free end 54 of the claw 29 and a width LE1 of the free end 54 of the claw 29 is between 0.1 and 0.35.

In the embodiment of Figure 3, the width LB2 of the base 53 of the claw 29 of the front wheel 24 is equal to the width LB1 of the base 53 of the claw 29 of the rear wheel 25. Similarly, the width LE2 of the free end 54 of the claw 29 of the front wheel 24 is equal to the width LE1 of the free end 54 of the claw 29 of the rear wheel 25. In a variant, the width LB2 and the width LB1 may have different measures. Similarly, the width LE2 and the width LE1 may have different measures.

In the embodiment of Figure 3, at the free ends 54, the width Ce3 of the chamfer 57 made in the claw 29 of the front wheel 24 is equal to the width Ce1 of the chamfer 57 made in the claw 29 of the As a variant, the width Ce3 and the width Ce1 may have different measurements.

In the embodiment of Figure 3, at the free ends 54, the width Ce4 of the chamfer 57 'made in the claw 29 of the front wheel 24 is equal to the width Ce2 of the chamfer 57' made in the claw 29 As a variant, the width Ce4 and the width Ce2 may have different measurements.

In the embodiment of FIG. 3, at the level of the bases 53, the width CB3 of the chamfer 57 made in the claw 29 of the front wheel 24 is equal to the width CB1 of the chamfer 57 made in the claw 29 of the wheel As a variant, the width CB3 and the width CB1 may have different measures.

In the embodiment of FIG. 3, at the level of the bases 53, the width CB4 of the chamfer 57 'made in the claw 29 of the front wheel 24 is equal to the width CB2 of the chamfer 57' made in the claw 29 of FIG. As a variant, the width CB4 and the width CB2 may have different measurements.

The widths CB1, CB2, CB3, and CB4 are measured at the level of the base 53, that is to say that they are measured at a maximum distance h1 between the base 53 of the corresponding claw 29 and the measurement equal to 15. % of the total length Lg of the claw 29. In other words, the widths are measured in a plane parallel to the radial face of the flange 28 located at the distance h1 relative to the base of the claw 29. Thus, for a length of claw Lg of the order of 20mm, the length h1 is of the order of 3mm.

The widths Ce1, Ce2, Ce3, Ce4, as well as the widths LE1 and LE2 are measured at the free end 54 that is to say they are measured in a plane parallel to the radial face of the flange 28 located at a distance h2 relative to the base 53. This distance h2 is equal to the length Lg of the claw 29 minus the distance h1 above. Each chamfer 57, 57 'may have a flat shape. In this case, a radial section of the chamfer 57, 57 'extends along a straight line. Alternatively, each chamfer 57 has a rounded corner along a radius of curvature R1, R2, as can be seen in FIG. 5. The radii of curvature R1 and R2 may be identical or different from one another. The widths CB1, Ce1 (or CB2, Ce2) are then measured between a straight line D1, parallel to the median plane PM of the claw 29 and tangent to the corresponding rounded corner, and the intersection between the flat portion of the chamfer 57 and the radius of R3 machining of the rotor 12.

The angle K between the plane portion of the chamfer 57 and the median plane PM of the claw 29 may be identical or different from a chamfer 57, 57 'to the other. The angle K is for example between 60 and 78 degrees.

As can be seen from the graph of FIG. 4, such a configuration makes it possible to minimize the magnetic noise optimally over the entire operating range of the rotor 12, without degrading the magnetic performance of the electric machine. The average of the sound reduction of the rotor 12 provided with double-chamfered claws 29 (see curve C1) with respect to a standard rotor (see curve C2) is of the order of 5 dB.

In the embodiment of Figures 2 and 3, the claws 29 of the pole wheels 24, 25 are symmetrical, that is to say that the median M passing through the center of the base 53 also passes through the free end 54 of the claw 29.

Alternatively, the claws 29 of the pole wheels 24, 25 may be asymmetrical, that is to say that the median M passing through the center of the base 53 of a claw 29 is offset relative to a parallel straight line passing through the free end 54 of the corresponding claw 29. Thus, in the embodiment of FIG. 6a, the claws 29 of one of the pole wheels 24 are inclined in the direction of rotation of the rotor SR (see arrow F1) and the claws 29 of the other pole wheel 25 are correspondingly inclined in the opposite direction to said direction of rotation SR (see arrow F2). An inter-scratch space 66 with parallel edges is thus obtained. This allows easy integration of interpolar magnets 46 of standard shape inside the spaces 66 between two successive claws.

The magnets 46 may be positioned inside all the spaces 66 or only inside some of them and evenly distributed along the circumference of the rotor 12. The magnets 46 may be made of rare earth NeFeB ( Neodymium-Iron-Boron) or SmCo (Samarium-Cobalt). The choices of the material and the number of interpolar magnets 46 make it possible to easily adjust the magnetic properties of the rotor 12 to the desired power of the alternator. In the embodiment of Figure 6b, the claws 29 of the pole wheels 24 and 25 are inclined in the same direction. In this case, the claws 29 of the two pole wheels 24, 25 are inclined in the direction of rotation of the rotor 12 (see arrows F3 and F4), but alternatively, the inclination could be carried out in the opposite direction. In this case, the inter-claw spaces 66 have non-parallel edges. The degree of inclination of the claws 29 may be the same or different from one pole wheel to another.

In the embodiment of Figure 6c, the claws 29 of the pole wheel 24 are symmetrical, while the claws 29 of the other pole 25 are asymmetrical. In the figure, the claws 29 of the pole wheel 25 are inclined in the direction of rotation SR of the rotor 12 (see arrow F5), but could alternatively be inclined in the opposite direction.

In all cases, the configuration of the chamfers 57, 57 'formed in the claws 29 is the same as that previously described with reference in particular to FIG. 3. In a variant, each claw 29 comprises a single chamfer 57 or 57' made in the leading edge 51 or trailing edge 52. Of course, the foregoing description has been given by way of example only and does not limit the scope of the invention which would not be overcome by replacing the different elements by any other equivalent.

Claims

1. Rotor (12) of a rotating motor vehicle electrical machine comprising at least one pole wheel (24, 25) comprising a plurality of claws (29), at least one claw (29) comprising:

a base (53) and an axially opposite free end (54),

a leading edge (51) and a trailing edge (52) extending between the base (53) and the free end (54),

a chamfer (57) made in the trailing edge (52),

the rotor being characterized in that a ratio of a width (CB1) of said chamfer (57) measured at the base (53) to a width (LB1) of the base of the claw (29) is between 0.17 and 0.23.

2. Rotor according to claim 1, characterized in that a ratio of a width (Ce1) of the chamfer (57) measured at the free end (54) of the claw over a width (LE1) of the free end of the claw is between 0.34 and 0.5.

3. Rotor according to claim 1 or 2, characterized in that another chamfer (57 ') is formed in the leading edge (51) of at least one claw (29).

4. Rotor according to claim 3, characterized in that a ratio of a width (CB2) of said other chamfer (57 ') measured at the base (53) of the claw (29) over a width (LB1) the base (53) of the claw (29) is between 0.09 and 0.20.

5. Rotor according to claim 3 or 4, characterized in that a ratio of a width (Ce2) of said other chamfer (57 ') measured at the free end (54) of the claw (29) on a width (LE1) of the free end (54) of the claw (29) is between 0.1 and 0.35.

6. Rotor according to any one of claims 1 to 5, characterized in that a chamfer surface decreases when moving towards the free end (54) of the claw (29) corresponding.

Rotor according to one of Claims 1 to 6, characterized in that the claw (29) has an outer radial surface (56) and that the chamfer (57) is formed on said outer radial surface (56).

8. Rotor according to any one of claims 1 to 7, characterized in that the chamfer (57, 57 ') extends axially between the base (53) and the free end (54) of the claw (29). corresponding.

9. Rotor according to any one of claims 1 to 8, characterized in that a radial section of the chamfer (57) extends along a straight line.

10. Rotor according to any one of claims 1 to 9, characterized in that it comprises a first pole wheel (24) and a second pole wheel (25) and in that the claws (29) of the two pole wheels ( 24, 25) are symmetrical.

1 1. Rotor according to any one of claims 1 to 9, characterized in that it comprises a first pole wheel (24) and a second pole wheel (25) and in that the claws (29) of the two pole wheels (29) are asymmetrical.

12. Rotor according to claim 1 1, characterized in that the claws (29) of one of the pole wheels (24, 25) are inclined in the direction of rotation (SR) of the rotor and the claws (29) of the another pole wheel (24, 25) are inclined in the opposite direction to said direction of rotation (SR), so as to have an inter-claw gap with parallel edges.

13. Rotor according to claim 1 1, characterized in that the claws (29) of the pole wheels (24, 25) are inclined in the same direction.

14. Rotor according to any one of claims 1 to 9, characterized in that it comprises a first pole wheel (24) and a second pole wheel (25) and in that the claws (29) of one of the wheels polar (24, 25) are symmetrical and the claws (29) of the other pole wheel (24, 25) are asymmetrical.

15. Alternating type electrical rotating machine or reversible machine characterized in that it comprises a rotor as defined in any one of the preceding claims.