FR3079686A1 - ROTOR OF ROTATING ELECTRIC MACHINE PROVIDED WITH HOLDING TABS OF PERMANENT MAGNETS - Google Patents

Abstract

The invention relates mainly to a rotor (10) of rotating 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 each other; other, - the bundle of plates (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 tongue (28) projecting inside the cavity (26) and configured to exert a stress on the permanent magnet (27) in an orthoradial direction following its deformation by the permanent magnet (27).

Description

ROTOR OF A ROTATING ELECTRIC MACHINE PROVIDED WITH PERMANENT MAGNET HOLDING TABS

The invention relates to a rotor of a rotating electric machine provided with tongues for holding permanent magnets.

In a manner known per se, rotary electrical machines comprise a stator and a rotor secured to a shaft. The rotor can be integral with a driving and / or driven shaft and can belong to a rotating electrical machine in the form of an alternator, an electric motor, or a reversible machine capable of operating in both modes.

The stator is mounted in a casing 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 crown, 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 covered 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 coils closed on themselves which are wound around the teeth of the stator. These windings are polyphase windings connected in star or triangle or star - triangle 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 metal sheets held in the form of a package by means of a suitable fixing system, such as rivets axially passing through the rotor from side to side, 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 formed in the rotor body.

Rotating electric machines are known which are coupled to a shaft of an electric compressor. This electric compressor makes it possible to at least partially compensate for the loss of power of thermal engines of reduced displacement used on many motor vehicles to reduce consumption and emissions of polluting particles (principle known as downsizing in English).

To this end, the electric turbocharger, placed on the intake duct upstream or downstream of the heat engine, comprises a turbine to allow air to be compressed in order to optimize the filling of the cylinders of the heat engine. The electric machine is activated to drive the turbine in order to minimize the torque response time, especially during transient acceleration phases, or in the automatic restarting phase of the heat engine after a standby (stop and start operation in English) ).

Given the reduced size of the machine and the magnetic performance sought which are very high (the compressor must be able to be driven in a time of less than 500 ms up to 100,000 rpm in certain life situations), there is a need for '' ensure precise balancing of the rotor. In fact, during the insertion of the magnets inside the cavities, the plating of the magnets against the faces of the cavities is random (certain magnets are pressed against an end face of the cavity and other magnets are pressed against the opposite end face), which creates an uncontrolled imbalance and therefore a risk of damage to the rotor.

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

- a body provided with an axis comprising a packet of sheets stacked on top of each other,

- the sheet package 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 projecting inside the cavity and configured to exert a force on the permanent magnet in an 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 cutting plane perpendicular to the axis of the rotor body, the permanent magnet is in abutment against a stop located on the side opposite to the deformable tongue.

According to one embodiment, in a cutting plane perpendicular to the axis of the rotor body, the cavity has a greater length extending in an orthoradial direction, in particular so that the permanent magnet generates a magnetic flux in a radial direction.

According to one embodiment, the package of sheets further comprises:

- a recess, and

- a wall separating the cavity with respect to the recess,

- The wall comprising at least one deformable portion arranged to fill at least partially the recess following its deformation by the permanent magnet. This eliminates the presence of air gaps inside the cavities and therefore improves the magnetic performance of the rotating electric machine.

According to 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 different cavities being configured to exert a force on the permanent magnets in the same orthoradial direction corresponding to a given direction of rotation.

According to one embodiment, the pack of sheets is formed by a stack of identical sheets, each sheet having a deformable tongue coming from an edge of a single cavity.

According to one embodiment, the rotor comprising N cavities, two successive sheets are angularly offset between them 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 section 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.

According to 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 breakage of the latter as well as a deformation of the sheet pack.

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.

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

According to one embodiment, the free end of the tongue has a shape in an arc of a circle.

According to 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 good maintenance of the magnet while avoiding scratching it during its insertion.

The invention also relates to a rotary electric machine, in particular 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 only by way of illustration but in no way limit the invention.

Figure 1 is a sectional view of a turbocharger comprising a rotary electrical machine according to the present invention;

Figure 2 shows a perspective view of the rotor of the rotary electrical machine according to the present invention without the magnets;

Figure 3 shows a perspective view of the rotor of the rotary electrical machine according to the present invention with the magnets;

Figure 4 is a perspective view of a sheet which can be used to form the sheet pack according to the invention.

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

Furthermore, in the description which follows, the faces of a so-called internal element are located on the side of the axis of the rotor and the so-called external faces are located on the side of the air gap of the electric machine.

Figure 1 shows an electric compressor 1, comprising a turbine 2 provided with fins 3 able to suck, via an inlet 4, uncompressed air from an air source (not shown) and to discharge from the compressed air via the outlet 5 after passing through a volute referenced 6. The outlet 5 may be connected to an intake distributor (not shown) in order to optimize the filling of the cylinders of the heat engine. In this case, the air suction is carried out 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. As a variant, the suction is radial while the discharge is axial. Alternatively, suction and discharge are carried out in the same direction relative to the axis of the turbine (axial or radial).

To this end, the turbine 2 is driven by an electric machine 7 mounted inside the casing 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 casing 8 configured to carry a shaft 11 in rotation by means of bearings 14. The shaft 11 is linked in rotation with the turbine 2 as well as with the rotor 10. The stator 9 is preferably mounted in the casing 8 by shrinking.

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 100,000 revolutions / min. Preferably, the operating voltage is 12 V or 48 V and a steady-state current is around 150 A at 260A. Preferably, the electric machine 7 is capable of providing a current peak, 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. As a variant, the electric machine 7 is capable of operating in alternator mode, or is an electric machine of the reversible type.

More specifically, the stator 9 comprises a body 91 constituted by a stack of thin sheets forming a crown, the inner face of which is provided with notches open towards the inside to receive phase windings of a winding 92. In a winding of wavy type, the windings are obtained for example from a continuous wire covered with enamel or from conductive elements in the form of U-shaped pins whose free ends are connected together by welding. Alternatively, in a concentric type winding, the phase windings consist of coils closed on themselves which are wound around the teeth of the stator 9. Protection between the stator body and the winding wire is provided either by a paper-type insulation, either by plastic by molding or by means of an insert. These windings are polyphase windings connected in a star or a triangle, the outputs of which are connected to control electronics.

Furthermore, the rotor 10 shown in detail in FIGS. 2 and 3 is with permanent magnets. The rotor body 15 of axis of rotation X comprises a pack of sheets 16 formed by an axial stack of sheets 19 on top of 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 fixing means, for example rivets, passing axially right through the stack of sheets via fixing holes 22.

The rotor body 15 can be linked in rotation to the shaft 11 in different ways, for example by force fitting the splined shaft 11 inside the central opening 23 of the sheet pack 16 or to the using a keyed device.

The rotor body 15 has an internal periphery delimiting the central opening 23 having an internal diameter for example of the order of 10mm, and an external periphery having an external diameter between 20 mm and 50 mm, in particular between 24mm and 34mm , and preferably of the order of 28mm. Furthermore, an external 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 each intended to receive at least one permanent magnet 27. Each cavity 26 passes axially through the sheet pack 16 right through.

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 an orthoradial direction.

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

The magnets 27 are preferably made of rare earth in order to maximize the magnetic power of the machine 7. Alternatively, they may however be made of ferrite depending on 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. It is in particular possible to use a single magnet 27 inside each cavity 26, or several magnets 27 stacked one on the other inside the same cavity 26, in particular two magnets stacked.

Each cavity 26 is closed at its outer circumference. Such a rotor configuration is said to have permanent magnets buried, 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 axial of the sheet pack 16.

More specifically, each cavity 26 is delimited by two faces 261,262 facing each other oriented in an orthoradial direction and two faces 263, 264 facing each other oriented in a direction slightly inclined with respect 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 either on the face d orthoradial end by which one enters is on the orthoradial end face by which one exits when one follows the given direction of rotation.

In addition, in the cutting 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 the level of a tongue 28 is strictly less than a length L2 of the permanent magnet 27. These lengths L1, L2 are measured in an orthoradial direction relative 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 an orthoradial direction. Given the positioning of the tongues 28 on the same side of the cavities 26, the tongues 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 direction of rotation R clockwise 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 is in abutment against a stop 29 located on the side opposite to the deformable tongue 28. This stop 29 is for example formed by a shoulder formed in the pack of sheets 16.

The sheet pack 16 further comprises recesses 30 each associated with a cavity 26. Each cavity 26 is separated from the recess 30 by a wall 31 comprising at least one deformable portion 32. As illustrated in FIG. 3a, the deformable portion 32 has a curved shape towards the inside of the cavity 26. As a variant, the deformable portion 32 has more than one curved shape, in particular two or three curved 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 strictly less than the width L4 of the magnet 27. These widths L3, L4 are measured in a radial direction relative to the X axis.

Thus, as illustrated in 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 so at least partially filling the recess 30. This makes it possible to reduce or even eliminate the air gap present in the cavity 26. In addition, the deformable portion 32 exerts a reaction on the magnet 27 by reaction to ensure its maintenance at the interior of 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 has recesses 30 in the pack of sheets 16. The sheet 19 has an edge domed 35 constituting a deformable portion 32.

A single cavity 26 of the sheet 19 has a tongue 28 coming from an orthoradial end edge 36, the other cavities 26 being devoid of tongue 28.

Advantageously, in a plane of the sheet 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 breakage of the latter as well as a deformation of the sheet pack 16.

Preferably, a rounded connection 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 certain embodiments, the free end of the tongue 28 may also have a rounded shape. The free end of the tongue 28 advantageously has the shape of an arc of a circle. The circular arc shape can extend over the entire width of the tongue 28. Such a free end of the tongue 28 allows the magnet 27 to be held securely while avoiding scratching the latter during its insertion.

In order to form the sheet pack 16, the rotor comprising N cavities 26, two successive sheets 19 of the sheet pack 16 are angularly offset between them by an angle of 360 degrees divided by N so as to alternate the positioning of the tongues 28 to the interior of the cavities 26. Here N is four, so two successive sheets 19 of the pack of sheets 16 are offset between them by 90 degrees or by a multiple of 90 degrees.

The internal and external faces of each magnet 27 are in this case flat, like the other faces of each magnet 27. Alternatively, the internal face and / or the external face can 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 guarantee surface contact between the magnets 27 and the rotor body 15. Such a configuration improves the retention of the magnet 27 inside. a cavity 26.

The rotor body 15 may also include two retaining flanges (not shown) pressed on either side of the rotor 10 on its axial end faces. These retaining flanges provide axial retention of the magnets 27 inside the cavities 26 and also serve to balance the rotor. The flanges are made of 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 from which one would not depart by replacing the various elements with any other equivalent.

Furthermore, the various features, variants, and / or embodiments of the present invention can be combined with one another in various combinations, insofar as they are not incompatible or mutually exclusive of one another.

Claims (14)

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 pack of sheets (16) stacked one on the other, - the sheet package (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 tongue (28) s' extending projecting inside the cavity (26) and configured to exert a force on the permanent magnet (27) in 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 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 so that the permanent magnet (27) generates a magnetic flux in a radial direction. 4. Rotor according to any one of claims 1 to 3, characterized in that the sheet pack (16) further comprises: - a recess (30), and - a wall (31) separating the cavity (26) relative to the recess (30), - The wall (31) comprising at least one deformable portion (32) arranged to fill at least partially 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 domed shape towards the inside 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 different cavities (26) are configured to exert a force on the permanent magnets (27) in 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 pack (16) is formed by a stack of identical sheets (19), each sheet (19) comprising a deformable tongue (28) from from an edge of a single cavity (26). 8. Rotor according to claim 7, characterized in that the rotor comprising N cavities (26), two successive sheets (19) are angularly offset between them by an angle corresponding to 360 degrees divided by N so as to alternate the positioning of the deformable tongues (28) inside 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). 10. 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 permanent magnet (27), a smaller width ( L3) of the cavity (26) is strictly less than a width (L4) of the permanent magnet (27). 11. 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 11, 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 connection portion (37) is located on each side of the deformable tongue (28). 5 14. Rotating electric machine (7), in particular 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 ).