WO2019011760A1

WO2019011760A1 - Rotor for a rotating electric machine provided with tabs for retaining permanent magnets

Info

Publication number: WO2019011760A1
Application number: PCT/EP2018/068171
Authority: WO
Inventors: Jean-François GAUTRU; Mamy Rakotovao; Patrycja DABROWSKA; Cordula QUITSCH; Benoit WALME
Original assignee: Valeo Equipements Electriques Moteur
Priority date: 2017-07-12
Filing date: 2018-07-05
Publication date: 2019-01-17
Also published as: FR3069115A1; FR3069115B1

Abstract

The invention mainly relates to a rotor (10) for a rotating electric machine, particularly for a motor vehicle, comprising: - a body (15) having an axis (X) comprising a stack of laminations (16) stacked one on top of the other, - the stack of laminations (16) comprising: - a central opening (23) for the passage of a rotor shaft (11); - at least one cavity (26) intended to receive at least one permanent magnet (27), characterized in that the cavity (26) is delimited by a face (263) provided with at least one deformable tab (28) projecting out from the inside of the cavity (26) and configured to apply a force to the permanent magnet (27) in an orthoradial direction as a result of its deformation by the permanent magnet (27).

Description

ROTOR OF ROTATING ELECTRIC MACHINE PROVIDED WITH HOLDING TABS OF PERMANENT MAGNETS

The invention relates to a rotary electric machine rotor provided with permanent magnet holding tabs. In known manner, the rotating electrical machines comprise a stator and a rotor secured to a shaft. The rotor may be integral with a driving shaft and / or driven and may belong to a rotating electrical machine in the form of an alternator, an electric motor, or a reversible machine that can operate in both modes. The stator is mounted in a housing configured to rotate the shaft for example by means of bearings. The stator comprises a body constituted by a stack of thin sheets forming a ring, the inner face of which is provided with notches open towards the inside to receive phase windings. In a distributed corrugated type winding, the windings are obtained for example from a continuous wire coated with enamel or from conductive elements in the form of pins connected together by welding. Alternatively, in a "concentric" type winding, the phase windings are constituted by closed coils on themselves which are wound around the teeth of the stator. These windings are polyphase windings connected in star or in triangle or star - delta whose outputs are connected to a control electronics. The system can be double three-phase.

Furthermore, the rotor comprises a body formed by a stack of sheets of sheet metal held in pack form by means of a suitable fastening system, such as rivets axially passing through the rotor from one side to the other, or by means of staples or buttons, or by laser welding or by gluing the sheets together. The rotor has poles formed by permanent magnets housed in cavities in the rotor body. Rotating electrical machines are known that are coupled to a shaft of an electric compressor. This electric compressor compensates at least in part the power loss of small displacement engines used on many motor vehicles to reduce the consumption and emissions of particulate pollutants (so-called principle of "downsizing" in English). For this purpose, the electric turbocharger, disposed on the intake duct upstream or downstream of the engine, comprises a turbine for compressing the air to optimize the filling of the cylinders of the engine. The electric machine is activated to drive the turbine in order to minimize the torque response time, in particular during the transient phases during acceleration, or in the automatic restart phase of the engine after a standby ("stop and start" operation in English).

Given the small size of the machine and the sought-after magnetic performances which are very high (the compressor must be able to be driven in a time of less than 500 ms up to 100000 rev / min in certain life situations), there is the need to ensure a precise balancing of the rotor. Indeed, during the insertion of the magnets inside the cavities, the plating of the magnets against the faces of the cavities is random (some magnets are pressed against an end face of the cavity and other magnets are pressed against the opposite end face), which creates an uncontrolled unbalance and therefore a risk of deterioration of the rotor.

The present invention aims to meet this need by proposing a rotating electric machine rotor, particularly for a motor vehicle, comprising:

a body provided with an axis comprising a stack of sheets stacked one on top of the other,

- the package of plates comprising:

a central opening for the passage of a rotor shaft,

at least one cavity intended to receive at least one permanent magnet,

characterized in that the cavity is delimited by a face provided with at least one deformable tongue extending projecting inside the cavity and configured to exert a force on the permanent magnet in a orthoradial direction following its deformation by the permanent magnet.

The invention thus makes it possible, thanks to the deformable tongue, to ensure that during the insertion of the magnets, all the magnets will be pressed against the same end face of the corresponding cavities, which makes it possible to precisely control the unbalance and therefore balancing the rotor of the rotating electrical machine.

According to one embodiment, in a sectional plane perpendicular to the axis of the rotor body, the permanent magnet bears against an abutment located on the opposite side to the deformable tongue.

According to one embodiment, in a section plane perpendicular to the axis of the rotor body, the cavity has a greater length extending in an orthoradial direction, in particular for the permanent magnet to generate a magnetic flux in a radial direction. According to one embodiment, the sheet package further comprises:

- a recess, and

a wall separating the cavity relative to the recess,

- The wall comprising at least one deformable portion arranged to at least partially fill the recess following its deformation by the permanent magnet. This makes it possible to eliminate the presence of the air knives inside the cavities and thus to improve the magnetic performance of the rotating electrical machine.

In one embodiment, the deformable portion has at least one curved shape towards the inside of the cavity. According to one embodiment, said rotor comprises a plurality of cavities, the deformable tongues of the various cavities being configured to exert a force on the permanent magnets in the same orthoradial direction corresponding to a given direction of rotation.

In one embodiment, the sheet package is formed by a stack of identical sheets, each sheet having a deformable tongue from an edge of a single cavity. According to one embodiment, the rotor comprising N cavities, two successive plates are angularly offset from each other by an angle corresponding to 360 degrees divided by N so as to alternate the positioning of the deformable tongues inside the cavities. According to one embodiment, in a sectional plane perpendicular to the axis of the rotor, when the cavity is devoid of permanent magnet, a smaller length of the cavity is strictly less than a length of the permanent magnet.

According to one embodiment, in a section plane perpendicular to the rotor axis, when the cavity is devoid of permanent magnet, a smaller width of the cavity is strictly less than a width of the permanent magnet.

In one embodiment, the cavity is closed at its outer circumference.

According to one embodiment, in a plane of a sheet, at least one rounded portion provides a connection between an anchoring end of the deformable tongue and an edge of the cavity. This allows, during the insertion of the magnet, a more flexible folding of the tongue avoiding the breakage of the latter and a deformation of the sheet package.

According to one embodiment, a rounded connection portion is located on each side of the deformable tongue. This particular arrangement of the tongue allows an optimal compromise between sufficient flexibility of the tongue and an ability to maintain a force on the magnet after deformation.

In one embodiment, the free end of the tongue has a shape having a rounded portion.

In one embodiment, the free end of the tongue has an arcuate shape.

In one embodiment, the free end of the tongue has an arcuate shape extending over the entire width of the tongue. Such a free end of the tongue allows a good maintenance of the magnet while avoiding scratching it when inserted.

The invention also relates to a rotating electrical machine, especially for a motor vehicle, characterized in that it comprises a rotor as defined above and a stator, in particular surrounding the rotor.

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 sectional view of a turbocharger comprising a rotary electric machine according to the present invention;

Fig. 2 shows a perspective view of the rotor of the rotating electrical machine according to the present invention without the magnets;

Fig. 3 shows a perspective view of the rotor of the rotating electrical machine according to the present invention with the magnets; Figure 4 is a perspective view of a sheet that can be used to form the sheet package according to the invention.

Identical, similar or similar elements retain the same reference from one figure to another.

Furthermore, in the following description, the faces of an element called "internal" are located on the side of the axis of the rotor and the so-called "external" faces are located on the side of the gap of the electric machine.

FIG. 1 shows an electric compressor 1, comprising a turbine 2 equipped with fins 3 able to suck, via an inlet 4, uncompressed air coming from an air source (not represented) and to repress the compressed air via the outlet 5 after passing through a volute referenced 6. The output 5 may be connected to an inlet distributor (not shown) to optimize the filling of the cylinders of the engine. In this case, the suction of the air is performed in an axial direction, that is to say along the axis of the turbine 2, and the discharge is carried out in a radial direction perpendicular to the axis of the turbine 2. Alternatively, the suction is radial while the discharge is axial. Alternatively, the suction and the discharge are made in the same direction relative to the axis of the turbine (axial or radial). For this purpose, the turbine 2 is driven by an electric machine 7 mounted inside the housing 8. This electric machine 7 comprises a stator 9, which may be polyphase, surrounding a rotor 10 with the presence of an air gap. This stator 9 is mounted in the housing 8 configured to rotate a shaft 1 1 through bearings 14. The shaft 1 1 is connected in rotation with the turbine 2 and with the rotor 10. The stator 9 is preferably mounted in the housing 8 by hooping.

The electric machine 7 has a short response time between 100 ms and 600 ms, in particular between 200 ms and 400 ms, for example being of the order of 250 ms to go from 5000 to 100000 rev / min. Preferably, the operating voltage is 12V or 48V and a steady state current is in the range of 150A to 260A. Preferably, the electric machine 7 is able to provide a peak current, that is to say a current delivered over a continuous period of less than 3 seconds, between 150 A and 800A, in particular between 180 A and 220 A. Alternatively, the electric machine 7 is able to operate in alternator mode, or is a reversible type electric machine.

More specifically, the stator 9 comprises a body 91 consisting of a stack of thin sheets forming a ring, whose inner face is provided with notches open inward to receive phase windings of a coil 92. In a winding of corrugated type, the windings are obtained for example from a continuous wire covered with enamel or from U-shaped pin-shaped conductive elements whose free ends are connected to each other by welding. Alternatively, in a "concentric" type winding, the phase windings are constituted by closed coils on themselves which are wound around the teeth of the stator 9. The protection between the stator body and the winding wire is ensured either by a paper-type insulator, either by plastic by overmolding or by means of an insert. These windings are polyphase windings connected in star or delta whose outputs are connected to a control electronics.

Furthermore, the rotor 10 shown in detail in Figures 2 and 3 is permanent magnets. The rotational axis rotor body X comprises a bundle of sheets 16 formed by an axial stack of sheets 19 on each other. Each sheet 19 extends in a radial plane perpendicular to the axis X. This rotor body 15 is made of ferromagnetic material. The sheets 19 are held by fastening means, for example rivets, passing axially through the stack of the sheets via fixing holes 22. The rotor body 15 can be connected in rotation to the shaft 1 in various ways, for example by force-fitting the splined shaft 1 1 inside the central opening 23 of the plate package 16 or with a key device.

The rotor body 15 has an internal periphery delimiting the central opening 23 having an internal diameter, for example of the order of 10 mm, and an external periphery having an external diameter of between 20 mm and 50 mm, in particular between 24 mm and 34 mm. , and preferably of the order of 28mm. Furthermore, an outer diameter of the stator 9 is between 35mm and 80mm, in particular between 45mm and 55mm, for example between 48mm and 52mm.

The rotor 10 comprises a plurality of cavities 26 intended to each receive at least one permanent magnet 27. Each cavity 26 passes axially through the pack of sheets 16 from one side to the other.

The cavities 26 preferably extend in an orthoradial direction, that is to say that in a section plane P perpendicular to the axis X of the rotor body 15, the cavity 26 has a greater length s'. extending in orthoradial direction.

In this case, the permanent magnets 27 have a rectangular parallelepiped shape whose angles can be beveled. The magnets 27 are radially magnetized, that is to say that the two faces parallel to each other having a orthoradial orientation are magnetized so as to be able to generate a magnetic flux in a radial orientation with respect to the X axis. As is clearly visible in FIG. 3, where the letters N and S respectively correspond to the North and South poles, the magnets 27 situated in two consecutive cavities 26 are of alternate polarities.

The magnets 27 are preferably made of rare earth in order to maximize the magnetic power of the machine 7. Alternatively, however, they may be made of ferrite according to the applications and the desired power of the electric machine 7. The number of cavities 26 is preferably equal to four. It is however possible to increase the number of cavities 26 and magnets 27 depending on the application. In particular, it is possible to use a single magnet 27 inside each cavity 26, or several magnets 27 stacked one inside the other within the same cavity 26, in particular two stacked magnets. Each cavity 26 is closed at its outer circumference. Such a rotor configuration is said to be buried permanent magnets, insofar as the magnets 27 are enclosed by the faces of the cavities 26, the two axial end faces of the magnet 27 being enclosed by attached flanges fixed on the ends In each case, each cavity 26 is delimited by two faces 261, 262 facing each other in a orthoradial direction and two faces 263, 264 facing each other. screw one of the other oriented in a direction slightly inclined relative to the radial direction. The faces 263, 264 are called orthoradial end faces. An orthoradial end face of each cavity 26, here the face 263, is provided with at least one deformable tongue 28 projecting inside the cavity 26. The end faces 263 of the cavities 26 provided at least one tongue 28 are located on the same side with respect to a given direction of rotation around the rotor (clockwise or counterclockwise), that is to say that the tongues 28 are all located on the face of the rotor. orthoradial end through which one enters the orthoradial end face by which one leaves when one follows the direction of rotation given. In addition, in the section plane P perpendicular to the axis X, when the cavity 26 is devoid of permanent magnet 27, a smaller length L1 of the cavity measured at a tongue 28 is strictly shorter than a length. L2 of the permanent magnet 27. These length L1, L2 are measured in a direction orthoradial with respect to the axis X.

Thus, when a magnet 27 is inserted inside a cavity 26, the tongues 28 are deformed and exert a force on the corresponding magnet 27 in a orthoradial direction. Given the positioning of the tabs 28 on the same side of the cavities 26, the tabs 28 exert a force on the magnets 28 in the same orthoradial direction corresponding to a given direction of rotation. In this case, the force F is applied in the rotational direction R time in FIG. 3. This ensures that all the magnets 27 are pressed against the same orthoradial end face of the cavities 26. In addition, in the cutting plane P, the magnet 27 bears against an abutment 29 situated on the opposite side to the deformable tongue 28. This abutment 29 is for example formed by a shoulder formed in the sheet package 16.

The bundle of sheets 16 further includes recesses 30 each associated with a cavity 26. Each cavity 26 is separated from the recess 30 by a wall 31 having at least one deformable portion 32. As illustrated by FIG. 3a, the deformable portion 32 has a curved shape towards the inside of the cavity 26. In a variant, the deformable portion 32 has more than one convex shape, in particular two or three convex shapes. It should be noted that in the plane P, when the cavity 26 is devoid of a permanent magnet 27, the smallest width L3 of the cavity 26 is smaller than the width L4 of the magnet 27. These widths L3, L4 are measured in a radial direction with respect to the X axis.

Thus, as illustrated by FIG. 3, following the insertion of a magnet 27 inside a cavity 26, the magnet 27 is pressed against the deformable portion 32 and deforms the deformable portion 32 in such a way that at least partially to fill the recess 30. This reduces or even eliminate the air gap in the cavity 26. In addition, the portion deformable 32 exerts by reaction a force on the magnet 27 to ensure its maintenance inside the corresponding cavity 26.

According to an exemplary embodiment illustrated in FIG. 4, each sheet 19 of generally annular shape has a central opening 23 and a plurality of cavities 26. Each sheet 19 also comprises recesses 30 of the sheet package 16. The sheet 19 has an edge curved 35 constituting a deformable portion 32.

A single cavity 26 of the plate 19 comprises a tongue 28 resulting from an orthoradial end edge 36, the other cavities 26 being devoid of tongue 28.

Advantageously, in a plane of the plate 19, at least one rounded portion 37 provides a connection between an anchoring end of the deformable tongue 28 and the edge 36 of the cavity. This allows, during the insertion of the magnet 27, a more flexible folding of the tongue 28 avoiding the breakage of the latter and a deformation of the sheet package 16.

Preferably, a rounded connecting portion 37 is located on each side of the deformable tongue 28. This particular arrangement of the tongue 28 allows an optimal compromise between sufficient flexibility of the tongue and an ability to maintain a force on the magnet after deformation.

In some embodiments, the free end of the tongue 28 may also have a rounded shape. The free end of the tongue 28 advantageously has an arcuate shape. The arcuate shape may extend over the entire width of the tongue 28. Such a free end of the tongue 28 allows a good retention of the magnet 27 while avoiding scratching it during its insertion.

In order to form the bundle of sheets 16, the rotor comprising N cavities 26, two successive plates 19 of the sheet bundle 16 are angularly offset from each other by an angle of 360 degrees divided by N so as to alternate the positioning of the tabs 28 to inside the cavities 26. Here N is worth four, therefore two successive plates 19 of the plate package 16 are shifted between them by 90 degrees or by a multiple of 90 degrees.

The inner and outer faces of each magnet 27 are in this case planar, like the other faces of each magnet 27. Alternatively, the inner face and / or the outer face may be curved, so that each magnet 27 generally has a shape of tile. The cavities 26 of the rotor 10 may have a shape complementary to that of the magnets 27 to ensure a surface contact between the magnets 27 and the rotor body 15. Such a configuration makes it possible to improve the retention of the magnet 27 inside. of a cavity 26.

The rotor body 15 may also comprise two holding flanges (not shown) plated on either side of the rotor 10 on its axial end faces. These holding flanges provide axial retention of the magnets 27 inside the cavities 26 and also serve to balance the rotor. The flanges are non-magnetic material, for example aluminum or very little magnetic such as stainless steel.

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. In addition, the various features, variations, and / or embodiments of the present invention may be associated with each other in various combinations, to the extent that they are not incompatible or exclusive of each other.

Claims

1. Rotor (10) of a rotary electrical machine, in particular for a motor vehicle, comprising:

a body (15) provided with an axis (X) comprising a stack of sheets (16) stacked on one another,

the package of plates (16) comprising:

a central opening (23) for the passage of a rotor shaft (1 1),

at least one cavity (26) intended to receive at least one permanent magnet (27),

characterized in that the cavity (26) is delimited by a face (263) provided with at least one deformable tongue (28) projecting into the cavity (26) and configured to exert a force on the permanent magnet (27) following an orthoradial direction following its deformation by the permanent magnet (27).

2. Rotor according to claim 1, characterized in that, in a cutting plane (P) perpendicular to the axis (X) of the rotor body (15), the permanent magnet (27) bears against a stop (29) located on the side opposite to the deformable tongue (28).

3. Rotor according to claim 1 or 2, characterized in that, in a cutting plane (P) perpendicular to the axis (X) of the rotor body (15), the cavity (26) has a greater length s extending in an orthoradial direction, in particular for the permanent magnet (27) to generate a magnetic flux in a radial direction.

4. Rotor according to any one of claims 1 to 3, characterized in that the sheet package (16) further comprises:

a recess (30), and

a wall (31) separating the cavity (26) with respect to the recess (30),

- The wall (31) having at least one deformable portion (32) arranged to at least partially fill the recess (30) following its deformation by the permanent magnet (27).

5. Rotor according to claim 4, characterized in that the deformable portion (32) has at least one curved shape towards the interior of the cavity (26).

6. Rotor according to any one of claims 1 to 5, characterized in that it comprises a plurality of cavities (26) and in that the deformable tongues (28) of the various cavities (26) are configured to exert effort on the permanent magnets (27) following the same orthoradial direction corresponding to a given direction of rotation (R).

7. Rotor according to any one of claims 1 to 6, characterized in that the sheet package (16) is formed by a stack of identical sheets (19), each sheet (19) having a deformable tongue (28) issue an edge of a single cavity (26).

8. Rotor according to claim 7, characterized in that the rotor having N cavities (26), two successive plates (19) are angularly offset from each other by an angle corresponding to 360 degrees divided by N so as to alternate the positioning of the deformable tongues (28) within the cavities (26).

9. Rotor according to any one of claims 1 to 8, characterized in that, in a cutting plane (P) perpendicular to the axis of the rotor (X), when the cavity (26) is devoid of permanent magnet (27), a shorter length (L1) of the cavity (26) is strictly less than a length (L2) of the permanent magnet (27).

Rotor according to Claim 4, characterized in that, in a cutting plane (P) perpendicular to the rotor axis, when the cavity (26) is devoid of a permanent magnet (27), a smaller width ( L3) of the cavity (26) is strictly less than a width (L4) of the permanent magnet (27).

1 1. Rotor according to any one of claims 1 to 10, characterized in that the cavity (26) is closed at its outer circumference.

12. Rotor according to any one of claims 1 to 1 1, characterized in that in a plane of a sheet (19), at least one rounded portion (37) provides a connection between an anchoring end of the deformable tongue (28) and an edge (36) of the cavity.

13. Rotor according to claim 12, characterized in that a rounded connecting portion (37) is located on each side of the deformable tongue (28).

14. Rotating electrical machine (7), especially for a motor vehicle, characterized in that it comprises a rotor (10) as defined in any one of the preceding claims and a stator (9), in particular surrounding the rotor (10). ).