WO2018042124A1

WO2018042124A1 - Rotor for a rotary electric machine provided with at least one deformable portion for filling a cavity

Info

Publication number: WO2018042124A1
Application number: PCT/FR2017/052303
Authority: WO
Inventors: Jean-François GAUTRU; Benoit WALME; Mamy Rakotovao; Cordula QUITSCH; Nam-Gook Kim; Maxime PAGNARD; Patrycja DABROWSKA
Original assignee: Valeo Equipements Electriques Moteur
Priority date: 2016-08-31
Filing date: 2017-08-30
Publication date: 2018-03-08
Also published as: FR3055485A1; FR3055485B1

Abstract

The invention mainly relates to a rotor (10) for a rotary electric machine, particularly for a motor vehicle, comprising: - a body (15) 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; - at least one cavity (26) intended to receive at least one permanent magnet (27), characterised in that the stack of laminations (16) further comprises: - a recess (30), and - a wall (31) separating the cavity (26) from the recess, - the wall (31) comprising at least one deformable portion (32) arranged to at least partially fill the recess (30) during deformation thereof.

Description

ROTOR OF ROTATING ELECTRIC MACHINE WITH AT LEAST ONE DEFORMABLE PORTION FOR FILLING A CAVITY

The invention relates to a rotary electric machine rotor provided with at least one deformable portion for filling a cavity. 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 desired magnetic performance which is very high (the compressor must be able to be driven in a time of less than 500ms up to 100000 rev / min in certain life situations), there is the need to to minimize the parasitic air gaps that may exist between the magnets and the faces of the cavities.

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

a body comprising a stack of sheets stacked on top of one another,

- 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 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 during its deformation.

The deformation may be elastic or plastic type. The invention thus makes it possible to reduce or even eliminate the air gap due to the filling of the recess by the deformable portion during the insertion of the corresponding permanent magnet. The invention also has an economic nature, insofar as the structure of the sheet package can be easily modified to form the recess and the deformable portion of the wall separating the cavity relative to the recess.

In one embodiment, the deformable portion and the recess extend over a substantially equal length, the length being measured in a direction perpendicular to a radius of the rotor.

In one embodiment, the rotor has an axis of rotation and an outer circumference.

In one embodiment, the wall has an inner edge located on the side of the axis of rotation of the rotor and an outer edge located on the side of the outer circumference of the rotor.

According to one embodiment, the magnet has an inner face extending in an orthoradial direction and located on the side of the axis of the rotor and the magnet has an outer face extending in a orthoradial direction and located on the circumference side. external rotor.

In one embodiment, the deformable portion is arranged to exert a force on the magnet in a radial direction. According to one embodiment, said rotor comprises at least one permanent magnet configured to deform the deformable portion when it is inserted into the cavity.

According to one embodiment, the wall and the recess are arranged so that after insertion of the magnet into the cavity, the inner edge of the wall is in contact with the sheet package, in particular on at least 1/3 of its length, and the outer edge is in contact with the inner face, in particular on at least 1/3 of the width of the inner face.

This makes it possible to greatly reduce or even eliminate the air gap present in the recess. According to one embodiment, the deformable portion is arranged so that, on a radius of the rotor passing through the middle of the magnet, the outer circumference of the sheet metal bundle, the magnet, the deformable portion, the bundle of sheets and the tree. In one embodiment, the deformable portion is in contact with the magnet at said radius.

In one embodiment, the deformable portion is in contact with the sheet package at said radius.

According to one embodiment, the cavity extends in an orthoradial direction, in particular for the permanent magnet to generate a magnetic flux in a radial direction.

In one embodiment, the wall comprises a single deformable portion.

As a variant, the cavity may have a different orientation for machines with axial, radial or transverse flux. In one embodiment, the deformable portion is an edge of a sheet metal of the sheet package.

According to one embodiment, the wall comprises a plurality of deformable portions along an axis in which the rotor extends.

In the case of identical sheets, each sheet of the package comprises a deformable portion.

According to one embodiment, the wall comprises a non-deformable portion arranged in radial recess with respect to the deformable portion.

According to one embodiment, the deformable portion has a curved shape towards the interior of the cavity, especially when the cavity is in its state before insertion of the magnet.

In one embodiment, the curved portion is centered relative to the width of the cavity, the width of the cavity being particularly considered in a orthoradial direction. This makes it possible to greatly reduce or even eliminate the air gap present in the recess.

According to one embodiment, the deformable portion extends in a width at least equal to 1/3 of the width of the cavity, the dimensions being measured in an orthoradial direction.

According to one embodiment, the deformable portion extends over a width substantially equal to the width of the magnet.

This allows, after insertion of the magnet, to maximize the width of the area free of air space and in which passes the magnetic flux generated by the magnet.

According to one embodiment, when the cavity is devoid of permanent magnet, the smallest width of the cavity is strictly less than a width of the permanent magnet.

In one embodiment, the permanent magnet has a rectangular parallelepiped shape.

In one embodiment, the permanent magnet has a curved face so as to have a tile shape.

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

In one embodiment, the cavity is closed at its outer circumference by the sheets of the sheet package.

In other words, the sheet package is configured to close the cavity on the outer circumference of the rotor.

In one embodiment, the permanent magnet is buried.

According to another aspect, the subject of the invention is a rotary electrical 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. Alternatively, the invention is applicable to a rotor surrounding the stator, which is external teeth. Such a stator has teeth delimiting notches receiving the phases, these teeth extending outwardly of the stator yoke.

In one embodiment, the cavity opens axially through the sheet package. Alternatively, the cavity may be blind. According to one embodiment, the thickness of the deformable portion is between 0.1 mm and 5 mm.

In one embodiment, the rotor body has a continuous cylindrical outer wall. In other words, the gap is constant. Alternatively, the gap may be variable depending on the circumference of the rotor. The body may have flat portions to reduce the acoustic noise. Thus the rotor body has a shape that is not perfectly cylindrical with, at the edge of its section, arcs of circles and straight successively.

In one embodiment, the magnet has a tile shape complementary to that of the rotor body. The magnet is thus in surface contact with the rotor body.

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 laminations of the rotating electrical machine according to the present invention;

Figures 3a and 3b are partial cross-sectional views of the rotor illustrating the configuration of a deformable portion respectively before and after insertion of a magnet within the corresponding cavity;

FIGS. 4a and 4b are perspective views respectively of a sheet provided with a deformable portion and of a conventional sheet without such a portion that can be used in combination to form the bundle of sheets 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 made in a radial direction perpendicular to the axis of 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 800 A, 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 rotor 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.

On the other hand, the rotation axis rotor X shown in detail in FIG. 2 is permanent magnets. The rotor body 15 comprises a pack 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 fixing means, for example rivets 22, passing axially through the stack of sheets 19.

The rotor body 15 may be rotatably connected to the shaft 11 in various ways, for example by force-fitting the splined shaft 11 into the central opening 23 of the plate package 16 or using a keyed device. The rotor body 15 has an inner periphery delimiting the central opening 23 having an internal diameter D1, for example of the order of 10 mm, and an outer periphery having an external diameter D 2 of between 20 mm and 50 mm, in particular between 24 mm. and 34mm, and preferably the order of 28mnn. 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. Each cavity 26 is closed at its outer circumference. The closure of the cavities 26 on the side of their outer periphery is obtained by the fact that the body has a continuous cylindrical outer wall. Such a rotor configuration is said to have buried permanent magnets, insofar as the magnets are enclosed by four of their faces by a corresponding cavity 26, the two axial faces of the magnet 27 being enclosed by attached machine flanges. on the ends of the plate package 16. 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 an 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. 2, where the letters N and S respectively correspond to the North and South poles, the magnets 27 located in two consecutive cavities 26 are of alternating polarity.

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. Thus, it is possible to use a single magnet 27 inside each cavity 26, or several magnets 27 stacked one inside the other inside the same cavity 26, in particular two magnets stacked. The bundle of sheets 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 shown in FIG. 3a, the deformable portion 32 has a curved shape towards the inside of the cavity 26. It should be noted that when the cavity 26 is devoid of a permanent magnet 27, the smallest width L1 of the cavity 26 is strictly lower than the width L2 of the magnet 27. These widths L1, L2 are measured in a radial direction with respect to the X axis. Thus, as illustrated by FIG. 3b, following the insertion a magnet 27 inside a cavity 26, the deformable portion 32 is deformed by the magnet 27 so as to at least partially fill the recess 30. This reduces or even eliminate the air gap present in the recess 30. In addition, the deformable portion 32 exerts by reaction a force on the magnet 27 to maintain it inside the corresponding cavity 26.

In an exemplary embodiment, the thickness L3 of the deformable portion 32 is between 0.1 mm and 5 mm.

Moreover, there are two spaces 35 on either side of the magnet 27 in an orthoradial direction. These spaces 35 are delimited by orthoradial end faces of the magnets 27 and the faces of the cavity 26 vis-à-vis. These spaces 35 are intended to receive holding elements 38 of the magnets 27, such as springs.

As can be seen in FIGS. 4a and 4b, each generally annular sheet metal sheet 19 has a central opening 23 and a plurality of holes 41 forming an axial portion of the cavities 26. Each sheet 19 also comprises recesses 42 corresponding to an axial portion of the recesses 30 of the sheet package 16. The holes 41 are separated from the recesses 42 by an edge 43 of small thickness. The axial stacking of the edges 43 of the sheet metal sheet 19 forms the wall 31 of the package. According to a first embodiment, all the plates 19 comprise a curved edge 43 constituting a deformable portion 32. Thus, the wall 31 has a plurality of deformable portions 32 along the X axis in which the rotor 10 extends. Another embodiment, a plate 19 on K (K being an integer) comprises a deformable curved edge 43, the other plates 19 being devoid of hollow 42 and having a non-deformable portion 44 delimiting the hole 41, as shown in FIG. Figure 4b. The non-deformable portion 44 is arranged in radial recess with respect to the deformable portion 32, that is to say that the non-deformable edge 43 is closer to the central opening 23 than the deformable portion 32. In other words, the Sheet package 16 is formed from two types of sheet 19, the stack of which can be alternated.

The inner faces 271 and outer 272 of each magnet 27 are in this case flat, like the other faces of each magnet 27. Alternatively, the inner face 271 and / or the outer face 272 are curved (see dashed lines in the figure 3b), so that each magnet 27 generally has a tile shape. 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) comprising a stack of sheets (16) stacked on each other,

the package of plates (16) comprising:

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

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

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,

- The wall (31) having at least one deformable portion (32) arranged to at least partially fill the recess (30) during its deformation.

2. Rotor according to claim 1, characterized in that it comprises at least one permanent magnet (27) configured to deform the deformable portion (32) during its insertion into the cavity (26).

3. Rotor according to claim 1 or 2, characterized in that the cavity (26) extends in a orthoradial direction, in particular for 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 deformable portion (32) is an edge of a sheet (19) of the package of sheets (16).

5. Rotor according to any one of claims 1 to 4, characterized in that the wall (31) has a plurality of deformable portions (32) along an axis (X) in which the rotor (10) extends.

6. Rotor according to any one of claims 1 to 5, characterized in that the wall (31) comprises a portion (44) non deformable arranged in radial recess with respect to the deformable portion (32).

7. Rotor according to any one of claims 1 to 6, characterized in that the deformable portion (32) has a curved shape towards the interior of the cavity (26).

8. Rotor according to any one of claims 1 to 7, characterized in that when the cavity (26) is devoid of permanent magnet (27), the smallest width (L1) of the cavity (26) is lower strictly at a width (L2) of the permanent magnet (27).

9. Rotor according to any one of claims 1 to 8, characterized in that the permanent magnet (27) has a rectangular parallelepiped shape.

10. Rotor according to any one of claims 1 to 8, characterized in that the permanent magnet (27) has a face (271, 272) curved so as to have a tile shape.

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 the permanent magnet (27) is buried.

13. Rotating electrical machine, 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, in particular surrounding the rotor (10).