FR3036007B1 - IMPROVED ROTOR OF ELECTRIC ROTATING MACHINE COMPRISING AT LEAST ONE MAGNET PLATING ELEMENT - Google Patents

Abstract

The invention relates mainly to a rotor (10) with permanent magnets, in particular for a rotary electric machine, for example for an electric turbo charger, comprising: - a rotor body (11) defining a plurality of cavities (21), a set of permanent magnets (22), in particular with radial magnetization, housed in said cavities (21), characterized in that: at least one cavity (21) of said rotor body (11) comprises at least one plating element ( 51) for the plating of a corresponding permanent magnet (22) against an inner face (36) of said cavity (21) of said rotor body (11).

Description

IMPROVED ROTOR OF ELECTRIC ROTATING MACHINE COMPRISING AT LEAST ONE MAGNET PLATING ELEMENT The invention relates to an improved rotary electric machine rotor provided with at least one element for plating a magnet inside a corresponding 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. The protection between the package of sheets and the winding wire is provided either by a paper-type insulation, or 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 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 turbocharger. This electric turbocharger makes it possible to compensate, at least in part, for the loss of power of the reduced-displacement heat engines used on many motor vehicles in order to reduce their consumption and the emissions of pollutant particles (so-called "downsizing" principle). 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 high speed of rotation of the rotor (of the order 70000 revolutions / min in certain life situations) which generates very large centrifugal forces on the magnets, it is difficult to keep in position the permanent magnets inside. cavities of the rotor body.

The present invention therefore aims to effectively overcome this disadvantage by proposing a rotor with permanent magnets, in particular for a rotary electric machine, for example for an electric turbo-charger, comprising: a rotor body defining a plurality of cavities, a set permanent magnet, in particular with radial magnetization, housed in said cavities, characterized in that: at least one cavity of said rotor body comprises at least one plating element for the plating of a corresponding permanent magnet against an internal face of said cavity of said rotor body. The invention thus makes it possible, by placing the plating element in position inside the cavity, to effectively hold the magnets inside the cavities in position in the event of a high rotational speed of the rotor. and during the acceleration and deceleration phases. The plating element can be arranged so that it is in the passage of the magnetic flux generated by the corresponding permanent magnet.

According to one embodiment, the plating element is constituted by a spring, in particular spiral, housed at least partially in a space positioned on the side of one of the orthoradial ends of a corresponding permanent magnet. In one embodiment, the cavity comprises at least one space formed in an orthoradial end. This reduces the magnetic leakage of a machine equipped with such a rotor.

According to one embodiment, a portion of said spring is in abutment against a corresponding permanent magnet, in particular against a face of the magnet directed towards an axis of rotation of said rotor, for applying a force on the magnet in a radial direction. Such a configuration allows a radial retention of the magnet.

According to one embodiment, said spring comprises two wound portions interconnected by an arm.

According to one embodiment, said spring is arranged to center a corresponding permanent magnet with respect to spaces located on either side of said permanent magnet. In one embodiment, the spring is arranged to apply a force to the magnet in an orthoradial direction.

In one embodiment, each wound portion comprises at least one turn that is complete or incomplete.

According to one embodiment, said rotor comprises a recess, in particular distinct from a space, adapted to receive one of the wound portions.

According to one embodiment, one of the wound portions of said spring takes the form of a space located on the side of an orthoradial end face of a corresponding permanent magnet.

According to one embodiment, a permanent magnet and a corresponding space are arranged to allow free passage of the arm between said permanent magnet and said rotor body. Thus, we obtain a locking of the magnet in both axes with one piece.

According to one embodiment, said rotor comprises, in each cavity, a single spring, of length substantially equal to a height of a corresponding permanent magnet. Such a configuration improves resistance to centrifugation and speed variations.

According to one embodiment, said spring exerts a force in a bearing zone covering substantially all of a height of a corresponding permanent magnet.

In one embodiment, said spring has a bearing zone covering part of a height of a corresponding permanent magnet.

In one embodiment, a plurality of springs are inserted at least partially within a space.

According to one embodiment, each spring has a bearing zone covering a portion of a height of a corresponding permanent magnet, in particular at each axial end of said corresponding permanent magnet.

According to one embodiment, at least one spring is respectively located at each orthoradial end of a corresponding permanent magnet.

According to one embodiment, said spring is made of a non-magnetic material. This is made possible by the fact that the spring is not in the main path of the magnetic flux generated by the magnet. The turns on the orthoradial axis may be nonmagnetic, but the turns on the radial axis are preferably magnetic.

In one embodiment, said spring is made of a magnetic material.

According to one embodiment, said spring is made of a bi-material material, in particular magnetic and non-magnetic material.

According to one embodiment, said rotor comprises at least one orthoradial retention stopper of a permanent magnet. According to one embodiment, for each cavity, a stop and a single spring are used on the opposite side.

Alternatively, several springs are positioned on the same side in a corresponding space.

In one embodiment, said plating element is distinct from the rotor body.

In one embodiment, spaces positioned at orthoradial end faces of each permanent magnet are filled with a filler material such as glue and / or resin. The invention furthermore relates to a method for manufacturing a rotor of a rotating electrical machine, characterized in that said method comprises: a step of producing a rotor body defining a plurality of cavities, an insertion step , in particular simultaneous, a permanent magnet and a compressed plating element inside each cavity, and - a step of releasing the plating element so that the plating element provides a plating of the permanent magnet against an inner face of the body defining the corresponding cavity. The invention also relates to a rotating electrical machine comprising a wound stator and a rotor as previously defined.

According to one embodiment, said machine comprises a rotor provided with four permanent magnets.

According to one embodiment, said rotor body has an outer periphery delimited by a cylindrical face of external diameter between 20 mm and 50 mm, in particular between 24 mm and 34 mm, and preferably of the order of 28 mm.

According to one embodiment, said machine has a response time of 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 70,000 revolutions / min. 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;

Fig. 3 is a cross-sectional view of the rotor of the rotating electrical machine according to the present invention;

Fig. 4 is a perspective view of a permanent magnet for insertion into a cavity of the rotor according to the present invention;

Figure 5 shows a partial sectional view illustrating an alternative embodiment of the rotor of the electric machine according to the present invention.

Figure 6a is a perspective view of the rotor according to the present invention illustrating the use of a first embodiment of a magnet plating element consisting of a spring blade;

Figure 6b is a perspective view of an assembly formed by a magnet and a corresponding spring blade positioned within a cavity of the rotor of Figure 6a;

Figure 7a is a perspective view of the rotor according to the present invention illustrating the use of a second embodiment of a magnet plating element constituted by an elastic pin;

Figures 7b and 7c show respectively perspective views of the rotor body and a pin used for producing the rotor of Figure 7a;

Fig. 8a is a perspective view of the rotor according to the present invention illustrating the use of a third embodiment of a magnets plating element constituted by a spiral spring;

Figure 8b is a top view of a rotor cavity illustrating the use of a spiral spring used in combination with an orthoradial holding stop of the magnet;

Figures 8c and 8d are top views of a rotor cavity illustrating the use of spiral spring with incomplete turns;

Fig. 9a is a perspective view of the rotor according to the present invention illustrating the use of a fourth embodiment of a magnet plating element constituted by a curved spring;

Figure 9b is a perspective view of a curved spring used for producing the rotor of Figure 9a;

Fig. 10a is a perspective view of the rotor according to the present invention illustrating the use of a fifth embodiment of a magnets plating element constituted by a V-shaped spring;

Figure 10b is a perspective view of a V-shaped spring used for making the rotor of Figure 10a;

Figure 11 is a partial view from above of the rotating electrical machine illustrating the different air gaps in the presence.

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

FIG. 1 shows a turbocharger 1, referred to as an electric turbo-charger, comprising a turbine 2 equipped with fins 3 able to suck, via an inlet 4, uncompressed air coming from an air source (not shown ) and discharge 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) located upstream or downstream of the engine to optimize the filling of the cylinders of the heat 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 19 by means of bearings 20. The shaft 19 is connected in rotation with the turbine 2 as well as with the rotor 10. The stator 9 is preferably mounted in the housing 8 by hooping.

In order to minimize the inertia of the turbine 2 during an acceleration request from the driver, the electric machine 7 has a short response time of 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 70000 revolutions / min. Preferably, the operating voltage is 12 V and a steady state current is of the order of 150 A. 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 300 A, in particular between 180 A and 220 A. In a variant, the electric machine 7 is able to operate in alternator mode, or is an electric machine of the type reversible.

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 distributed corrugated type, the windings are obtained for example from a continuous wire coated with enamel or from conductive elements in the form of U-shaped pins whose free ends are interconnected 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 package of sheets 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 10 comprises a rotor body 11 formed here by a stack of sheets extending in a radial plane perpendicular to the axis X in order to reduce the eddy currents. This rotor body 11 is made of ferromagnetic material. The sheets are held by fixing means 14, for example rivets, passing axially through the stack of sheets, or with staples or by means of buttons, or by welding or bonding the sheets to form a manipulable and transportable set. For this purpose, a plurality of fixing holes 13 are made in the rotor body 11 to allow each passage of a fastening means 14 of the sheets of the rotor body 11. In this case, the fixing holes 13 are preferably through, that is to say that they open axially on each of the axial ends 17, 18 of the rotor body 11, so that it is possible to pass inside each hole 13 a rod 14 provided with a head 141 at one of its ends and the other end will be deformed for example by a method of pegging to ensure the axial retention of the sheet package. Alternatively, the rod 14 is devoid of head 141 and the two ends are then deformed by a method of bouterollage or striking. As a variant, the holes 13 may have a section of square, rectangular shape, or any other shape adapted to the passage of the fastening means 14.

The rotor body 11 can be rotatably connected to the shaft 19 in various ways, for example by force-fitting the splined shaft 19 inside the central opening 12 of the rotor 10, or by means of a keyed device.

The rotor body 11 has an inner periphery 15 delimiting the central cylindrical opening 12 having an internal diameter D1 for example of the order of 10 mm, and an outer periphery 16 delimited by a cylindrical face of external diameter D 2 between 20 mm and 50 mm, especially between 24 mm and 34 mm, and preferably of the order of 28 mm. The rotor body 11 also has two annular axial end faces 17, 18 extending between the inner periphery 15 and the outer periphery 16.

Furthermore, an outer diameter of the stator 9 is between 35 mm and 80 mm, in particular between 45 mm and 55 mm, for example between 48 mm and 52 mm.

The rotor 10 comprises a plurality of cavities 21 in each of which is housed a permanent magnet 22. Each cavity 21 passes axially through the rotor body 11 from one side to the other, that is to say from an axial end face 17 , 18 to the other. Alternatively, the cavities 21 may include a bottom for the axial retention of the magnet, on an axial end of the rotor body.

Two adjacent cavities 21 are separated by an arm 25 coming from a core 26 of the rotor 10, so that there is an alternation of cavities 21 and arm 25 when following a circumference of the rotor 10. The rotor body 11 also comprises polar walls 31 each located between two adjacent arms 25. Each pole wall 31 extends between an inner face 36 in contact with a permanent magnet 22 and the outer periphery of the rotor 10. In addition, each arm 25 is connected to a corresponding polar wall 31 via a bridge 32 .

Thus, as can be seen in FIG. 3, the cavities 21 are each delimited by two faces 35 of two adjacent arms 25 facing each other, a flat inner face 36 of a polar wall 31 extending following an orthoradial direction, a flat face 37 formed in the core 26 parallel to the face 36, and the inner faces 38 of two bridges 32. The junctions between the faces 35 and 38 may be rounded to facilitate the manufacture of parts.

In the present case, as is clearly visible in FIG. 4, the permanent magnets 22 have a rectangular parallelepiped shape whose angles are slightly bevelled. The magnets 22 thus have a substantially constant rectangular cross-section. The magnets 22 are radially magnetized, that is to say that the two faces 41, 42 parallel to each other having an orthoradial orientation are magnetized so as to be able to generate a magnetic flux in a radial orientation M with respect to the axis X. Among these faces 41, 42 parallel, there is the internal face 41 located on the X axis side of the rotor 10 and the outer face 42 located on the side of the outer periphery 16 of the rotor 10 .

As is clearly visible in FIGS. 3 and 5, where the letters N and S respectively correspond to the North and South poles, the magnets 22 located in two consecutive cavities 21 are of alternating polarity. Thus, from one cavity 21 to the other; the inner faces 41 of the magnets 22 bearing against the flat face 37 formed in the core 26 have an alternating polarity, and the outer faces 42 of the magnets 22 in contact with the inner face 36 of the corresponding polar wall 31 have an alternating polarity .

The inner 41 and outer 42 faces of each magnet 22 are in this case flat, like the other faces of each magnet 22. In a variant, as has been shown in FIG. 5, the outer face 42 of each magnet 22 is curved. , while the inner face 41 of the magnet 22 is flat, or vice versa. The inner face 36 of the polar wall 31 then has a corresponding curved shape. This improves the retention of the magnet 22 inside a cavity 21. Alternatively, the two lateral faces 41 and 42 are bent in the same direction (see dashed line 50), so that each magnet 22 presents overall a tile shape.

Furthermore, the magnets 22 do not completely fill the cavities 21, so that there are two voids 45 on either side of the magnet 22 following an orthoradial direction. These spaces are delimited by orthoradial end faces of the magnets 22 and the faces of the cavity 21 vis-à-vis. These spaces 45 extend longitudinally along the orthoradial end faces of the magnets 22. The volume of air delimited by the set of spaces 45 of the rotor 10 makes it possible to reduce the inertia of the rotor 10.

The magnets 22 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. Alternatively, the magnets 22 can be of different shades to reduce costs. For example, the cavities 21 are alternated with the use of a rare earth magnet and a less powerful but less expensive ferrite magnet. Some cavities 21 may also be left empty depending on the desired power of the electric machine 7. For example, two cavities 21 diametrically opposed may be empty. The number of cavities 21 is preferably, as shown, equal to four as the number of magnets 22 associated. It is however possible to increase the number of cavities 21 and magnets 22 depending on the application. Furthermore, a single permanent magnet 22 is preferably inserted inside each cavity 21. In a variant, it will be possible to use several magnets 22 stacked one on the other inside the same cavity 21. For example, it will be possible to use two permanent magnets 22 stacked axially or orthoradially on one another, which may, if necessary, be of different shades.

In addition, plating elements 51 are interposed between the rotor body 11 and each magnet 22, to ensure the maintenance of each permanent magnet 22 inside the corresponding cavity 21. Each plating element 51 is arranged, so that the plating element 51 is in the passage of the radial magnetic flux generated by the corresponding magnet 22. Each plating element 51 provides a plating of the magnet 22 against the inner face 36 of each cavity 21 by applying a radial direction force. Alternatively, the plating elements 51 could be positioned on the opposite side of the magnet 22 so as to ensure a plating of the magnet 22 against the opposite inner face 36.

In the embodiment of FIGS. 6a and 6b, the plating element 51 is constituted by a curved spring blade 511. A recess 55 of the curved blade 511 is directed towards a shaft of the rotor 10. When the blade 511, which is attached relative to the rotor body 11, is positioned between the body 11 and the magnet 22, the height hollow 55 decreases by elastic deformation so that the blade 511 is in a compressed state. By reaction, the blade 511 then applies a radial force against the corresponding magnet 22 so as to press against the inner face 36.

In the exemplary embodiment, the edges of the blade 511 substantially coincide with the edges of the magnet 22 as can be seen in FIG. 6b. This makes it possible to limit as much as possible the volume of air which disturbs the propagation of the magnetic flux.

In all cases, the leaf spring 511 has a surface at least equal to 40%, especially at least 60%, for example at least equal to 80% of the surface of the magnet 22 against which the blade comes into screws -a-vis.

The leaf spring 511 comprises axially holding tabs 52 of the magnet 22. Next to each of its axial end edges, the blade 511 thus comprises at least one tab 52 folded so as to bear against an end face axial axis of the magnet 22 and at least one lug 52 intended to bear against an end face of the rotor body 11.

In this case, the blade 511 comprises at each of its axial end edges two central lugs 52 folded so as to come into contact with an end face of a corresponding magnet 22, as well as two end tabs 52 folded back. so as to come into contact against an end face of the rotor body 11. In a variant, the arrangement of the lugs 52 plated on the face of the magnet 22 and the rotor 10 is reversed. The number and arrangement of the tabs 52 along the edges of the blade 511 can of course be adapted according to the application, and in particular the size of the magnet 22 to be maintained in the cavity 21. Such a configuration of the spring 511 thus makes it possible to eliminate the axial holding flanges of the magnets 22 inside the cavities 21.

The blade 511 may also include, if necessary, tabs 53 for lateral retention of a corresponding magnet 22 (see Figure 6b). This makes it possible to guarantee a centering of the magnet 22 in the cavity 21 with respect to the spaces 45. Alternatively or in addition to the tabs 52, 53, the rotor 10 may also include at least one stopper 54 for orthoradial retention of each magnet of the magnet. magnet assembly 22 so as to center it with respect to the spaces 45, as illustrated in FIG. 8b. The stop 54 may be formed by a longitudinal shoulder formed in the rotor body 11.

As can be seen in FIG. 11, the machine comprises a total gap Etot, measured along a radius R1 of the machine cutting a permanent magnet 22, the total air gap being the sum of a first air gap E1 between the stator 80 and the rotor 10 and a second gap E2 between a wall of the cavity 21 and a face of the corresponding permanent magnet 22. The total air gap Etot is preferably between 0.1 and 0.6 mm, for example substantially equal to 0.3 mm. Each permanent magnet 22 has an average thickness of about 2 to 5 mm, for example substantially equal to 3 mm.

A ratio between the smallest thickness E of a magnet 22 and the maximum width of the total gap Etot is between 3 and 50, especially between 10 and 15.

The blade 511 is preferably made at least partially, preferably completely, of a magnetic material such as iron or a steel shade in order to allow the transmission of the radial magnetic flux in the path of which the blade 511 is located.

In this case, the blade 511 exerts a force in a bearing zone covering substantially the entire height H of the magnet 22 measured in an axial direction. More generally, the blade 511 exerts a force in a bearing zone over at least 10% of the height H of the permanent magnet 22. In an alternative embodiment, a plurality of blades 511 each exerting a zone of pressing on part of the height of a corresponding permanent magnet 22. The spaces 45 positioned at the orthoradial end faces of each magnet 22 may if necessary be filled with a filling material, such as glue and / or resin, or any other suitable material.

In the embodiment of FIGS. 7a to 7c, the plating element 51 is constituted by a pin 512. The pin 512 has an elongated annular shape in an axial direction. The pin 512 is provided with a longitudinal slot 57 passing through an annular wall 58 from one side to give it its elasticity. The pin 512 thus has a split ring-shaped section. The ends 59 of the pin 512 clearly visible in Figure 7c are preferably beveled. In this case, the pin 512 is mounted compressed in a recess 60 made in the sheet package having a shape complementary to the pin 512 (see Figure 7a and 7b). The recess 60 thus delimits a cylinder portion shape. In the compressed state, the free ends of the ring delimited by the pin 512 are brought closer to each other, so that the pin 512 exerts a radial force on the magnet 22 in order to flatten the magnet 22 against the inner face 36.

In each cavity 21, the rotor 10 here comprises a single pin 512 which has a length substantially equal to the height H of the magnet 22. The pin 512 thus exerts a force in a bearing zone covering the entire height H of the magnet 22, which makes it possible to homogenize the bearing force on the magnet 22. The bearing zone is substantially linear, insofar as it corresponds to the intersection between a plane (the flat face 36 of the magnet 22) and a cylinder (corresponding to the outer periphery of the pin 512).

As a variant, several pins 512 are inserted inside each cavity 21. Each pin 512 may then have a bearing zone covering part of the height H 'of a corresponding permanent magnet 22, in particular at the level of each axial end of the magnet 22 (see Figure 7b). Each pin 512 preferably has a bearing zone covering at least 10%, especially 50%, of the height of the magnet 22. At least two pins 512 may be aligned substantially along the same axis.

Alternatively, a pin 512 is located respectively at each orthoradial end of the magnet 22, as in the case of the use of the spiral springs 513 (see Figure 8a). Several pins 512 may also be positioned at each orthoradial end of the magnet 22. Such a configuration makes it possible to avoid the disturbance of the flow in the central part of the magnet 22.

A ratio between a height L1 of a recess 60 measured along the radial axis relative to the outside diameter L2 of a corresponding pin 512 is between 0.4 and 0.7, especially between 0.5 and 0.6. Such a ratio makes it possible to optimize the compromise between the thrust force applied by the pin 512 on the magnet 22 and the limitation of the air gap (between the face 37 and the face opposite the magnet 22) disturbing the propagation of the flux in the rotor 10. The pin 512 is also made at least partially, preferably completely in a magnetic material so as not to disturb the transmission of the radial-oriented magnetic flux generated by the corresponding magnet 22. In the example shown, the diameter of a pin 512 is between 1 and 2.5 mm, and is for example of the order of 1.5 mm.

In the embodiment of FIGS. 8a to 8d, the plating element 51 is constituted by at least one spiral spring 513 housed at least partially in a space 45 positioned on the side of one of the orthoradial ends of the magnet 22. The spring 513 applies a force having a substantially radial direction on the corresponding magnet 22 so as to press the corresponding magnet 22 against the inner face 36. For this purpose, a portion of the spring 513 bears against the magnet 22.

More specifically, two springs 513 are positioned on either side of the magnet 22 in a orthoradial direction. Such a configuration thus makes it possible to reduce the magnetic leakage of the machine. Each spring 513, which is attached relative to the rotor body 11, has a first 61 and a second 62 wound portions interconnected by an arm 63, as can be seen in Figures 8a and 8b. In the example shown, each wound portion 61, 62 comprises a plurality of turns 64. As a variant, each wound portion 61, 62 comprises at least one turn 64 which may be complete or incomplete. Figures 8a and 8b thus illustrate springs 513 provided with portions 61,62 formed by incomplete turns 64 having reversed winding directions.

The first wound portion 61 is positioned inside one of the spaces 45, so as to match the shape of the space 45. The second wound portion 62 is positioned inside a recess 60 of corresponding shape arranged in the rotor body 11. The recess 60 thus has a cylinder portion shape. The magnet 22 and the corresponding space 45 are arranged so as to allow free passage of the arm 63 between the magnet 22 and the rotor body 11. As shown in FIG. 8a, positioning a wound portion 61 of a spring 513 in each space 45 makes it possible to guarantee the centering of the magnet 22 with respect to these spaces 45.

In the compressed state, the wound portions 61, 62 are angularly spaced from one another relative to their position in the rest state of the spring 513, so that the wound portion 62 exerts by reaction, following a bearing zone, a force having a substantially radial direction on the magnet 22 so as to press against the inner face 36. The bearing zone of the spring 513 against the magnet 22 is linear insofar as it corresponds at the intersection between the flat inner face 36 and the wound portion 62 of generally cylindrical shape. This bearing zone covers substantially the entire height H of the magnet 22.

Alternatively, several springs 513 are inserted inside each space 45. Each spring 513 has a bearing zone covering part of the height H 'of a permanent magnet 22, in particular at each axial end of the spring. magnet 22.

In the embodiment shown in Figure 8b, is used in each cavity 21 a single spring 513 and a stop 54 in the form of a longitudinal shoulder formed in the rotor body 11 to ensure orthoradial retention of the corresponding magnet 22 . Spaces 45 may if necessary be filled with glue and / or resin.

Since the springs 513 are positioned in abutment with the orthoradial ends of the magnet 22, the springs 513 do little to disturb the central magnetic flux generated by the magnet 22. As a result, the springs 513 can be made of a non-magnetic material. Alternatively, the springs 513 are made of a magnetic material. As a variant, each spring 513 is made of a bi-material material, that is to say that the wound portion 61 situated in a space 45 is made of non-magnetic material and the wound portion 62 bears against the magnet 22 is made of a magnetic material to minimize magnetic disturbances.

In the embodiment of FIGS. 9a and 9b, in order to maintain the magnets 22 inside the cavities 21, the rotor 10 comprises, in each cavity 21, a spring 514 mounted compressed by crushing along its height between the body of rotor 11 and the permanent magnets 22. Each spring 514 thereby deforms a radial force on the magnets 22 from the inside to the outside of the rotor 10. For this purpose, each spring 514 is positioned in a longitudinal recess 60. This recess 60 of rectangular section is provided to minimize the air gap between the magnet 22 and the inner face 37 vis-à-vis the magnet 22. As can be seen in Figure 9b, each spring 514, made for example of stainless steel, has a central rounded portion 67, and two rounded end portions 68 located on either side of the central portion 67.

The central portion 67 and the end portions 68 have inverted curvatures. The radius of curvature of the central portion 67 is greater than the radius of curvature of the end portions 68. This spring 514 and catches the games so that the manufacturing tolerances can be large. Each spring 514 preferably has a tapered end 69 to facilitate insertion into the cavity 21. Each spring 514 further includes a slot 70 along the tapered end 69 to reduce the rigidity of the beveled end.

In the present case, each spring 514 exerts a force in a bearing zone covering substantially the entire height H of the magnet 22. In a variant embodiment, a plurality of springs 514, each exerting a zone of rotation, is used. pressing on part of the height of a corresponding permanent magnet 22. Each spring 514 then exerts a force in a bearing zone over at least 10% of the height H of the permanent magnet 22.

In the embodiment of FIGS. 10a and 10b, the plating elements 51 each consist of a spring 515 comprising two plates 73 of rectangular shape interconnected by one of their common end edge 77 and inclined relative to one another. to the other so as to have a shape of V. Each spring 515 deforms a radial force on the magnets 22 from the inside to the outside of the rotor 10. For this purpose, each spring 515 is positioned in a recess 60 longitudinal of the sheet package provided to minimize the air gap between the magnet 22 and the inner face 36 vis-à-vis the magnet 22 on the side of the shaft. In addition, the free ends of the spring 515 being brought closer to each other, the spring 515 exerts a radial force against the magnet against the internal face 36 as a result of the reaction. Figure 10b, each spring 515 has two returns 74 each located on the side of an edge of one of the free ends of a wafer 73 corresponding. The returns 74 forming an angle with respect to the corresponding wafer 73 are intended to each bear respectively against a face of the rotor 10 and against an axial end face of the magnet 22. The spring 515 can be made for example in a magnetic material so as not to disturb the magnetic flux flowing in the rotor 10. Alternatively, the spring 515 is made of a non-magnetic material.

In the present case, each spring 515 exerts a force in a substantially flat support zone covering substantially the entire height H of the magnet 22. In a variant embodiment, a plurality of springs 515, each of which has a zone, is used. resting on part of the height H of a corresponding permanent magnet 22. Each spring 515 then exerts a force in a bearing zone over at least 10% of the height H of the permanent magnet 22.

The method of manufacturing a rotor 10 of rotating electrical machine which consists of producing the rotor body 11 defining a plurality of cavities 21 and then preferably simultaneously inserting a permanent magnet 22 and a plating element 51 is described below. , 511, 512, 513, 514, 515 compressed inside each cavity 21. The plating element 51 is then released, so that the plating element 51 provides a plating of the permanent magnet 22 against the inner face 36 of the body partially delimiting the cavity 21.

The rotor body 11 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 22 inside the cavities 21 and also serve to balance the rotor 10. The flanges are made of non-magnetic material, for example aluminum.

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 (13)

1. Rotor (10) with permanent magnets, in particular for a rotary electric machine, for example for an electric turbo-charger, comprising: - a rotor body (11) defining a plurality of cavities (21) and having an outer periphery delimited by a cylindrical face of external diameter between 20 mm and 50 mm, - a set of permanent magnets (22), in particular with radial magnetization, housed in said cavities (21), characterized in that: at least one cavity (21) said rotor body (11) comprises at least one plating element (51) for the plating of a corresponding permanent magnet (22) against an inner face (36) of said cavity (21) of said rotor body (11), the plating element being constituted by a spring (513), in particular spiral, housed at least partially in a space (45) positioned on the side of one of the orthoradial ends of a corresponding permanent magnet (22). 2. Rotor according to claim 1, characterized in that a portion of said spring (513) is in abutment against a permanent magnet (22) corresponding, in particular against a face of the magnet (22) directed towards an axis of rotation of said rotor (10) for applying a force on the magnet (10) in a radial direction. 3. Rotor according to claim 1 or 2, characterized in that said spring (513) is arranged to center a corresponding permanent magnet (22) with respect to spaces (45) located on either side of said permanent magnet (22). ). 4. Rotor according to any one of claims 1 to 3, characterized in that said spring (513) comprises two wound portions (61, 62) interconnected by an arm (63). 5. Rotor according to claim 4, characterized in that each wound portion (61, 62) comprises at least one turn (64) which is complete or incomplete. 6. Rotor according to claim 4 or 5, characterized in that said rotor (10) comprises a recess (60), in particular distinct from a space (45), adapted to receive one of the rolled portions (62). 7. Rotor according to any one of claims 4 to 6, characterized in that one of the wound portions (61) of said spring (513) takes the form of a space (45) located on the side of a face of orthoradial end of a corresponding permanent magnet (22). 8. Rotor according to any one of claims 4 to 7, characterized in that a permanent magnet (22) and a space (45) corresponding are arranged to allow free passage of the arm between said permanent magnet (22) and said rotor body (11). 9. Rotor according to any one of claims 1 to 8, characterized in that said rotor (10) comprises, in each cavity (21), a single spring (513), of length substantially equal to a height (H) d a corresponding permanent magnet (22). 10. Rotor according to any one of claims 1 to 9, characterized in that at least one spring (513) is located respectively at each orthoradial end of a corresponding permanent magnet (22). 11. Rotor according to any one of claims 1 to 10, characterized in that said rotor (10) comprises at least one stop (54) for orthoradial retention of a permanent magnet (22). 12. A method of manufacturing a rotor (10) of rotating electrical machine, characterized in that said method comprises: - a step of producing a rotor body (11) defining a plurality of cavities (21), - a insertion step, in particular simultaneous, of a permanent magnet (22) and a compressed plating element inside each cavity (21), and - a step of releasing the plating element in such a way that the plating element provides a plating of the permanent magnet (22) against an inner face (36) of the body defining the corresponding cavity (21). 13. A rotating electrical machine comprising a wound stator and a rotor (10) as defined in any one of claims 1 to 11.