Rotor for an electric machine comprising shims for retaining permanent magnets

Abstract

A rotor (10) for an axial flux electric machine, comprising a star-shaped body (8) comprising a hub (1) and branches (2) extending radially outwards from the hub, a slot (3) being formed between each pair of adjacent branches, each slot being configured to accommodate a magnet block (4), each slot being delimited by a first wall (7) of the hub at the bottom and by one face of each of the adjacent branches flanking the slot on each side, as well as comprising, in the first wall, a recess (6) receiving an elastomeric shim (5), inserted between the first wall and a magnet block, the magnet blocks being bordered radially on the outer side by a cylindrical hoop (9) configured to exert a radial force on each of said magnet blocks so as to compress the elastomeric shim between a magnet block and the hub.

Description

[0001] DESCRIPTION

[0002] TITLE OF THE INVENTION: Rotor of an electric machine comprising shims for holding permanent magnets

[0003]

[0001] The present invention relates generally to rotors of electrical machines and more specifically to a rotor with permanent magnets, the rotor comprising shims for holding the permanent magnets. The present invention also relates to an electrical machine equipped with such a rotor.

[0004] The focus here is on electrical machines used in motor vehicles, especially electric and hybrid vehicles. However, the proposed rotor and the electrical machine equipped with it can be used in applications other than automotive electric traction.

[0005]

[0003] An electrical machine generally comprises a rotor forming a rotating part around a machine axis, and a stator forming a complementary non-rotating part, all housed in a casing.

[0006] There are many configurations of so-called 'radial' flux machines. In this document, however, we are particularly interested in so-called axial flux machines. The magnetic field in the air gap is oriented mainly parallel to the machine axis.

[0007] In axial flux machine configurations, the rotor has a general shape of a thick disc which has a thickness much smaller than its diameter.

[0008] As illustrated in document WO2020065488, an exemplary axial flux rotor comprises a star-shaped body, with a hub and radial legs, a magnet being disposed in the available gap between each pair of adjacent legs.

[0009]

[0007] The electrical machines in question can reach high rotation speeds, for example at least 12,000 revolutions per minute (200 rpm), or even higher speeds.

[0010] Furthermore, to optimize the efficiency of the electric machine, particularly from the torque point of view, the magnets must be placed as far as possible from the axis.

[0011] As a result, the level of centrifugal force experienced by the rotor magnets is very high, and at the same time it is essential to ensure and maintain the mechanical cohesion of the rotor throughout the life cycle of the electrical machine.

[0012]

[0010] It is known to constrain the rotor magnets by a permanent prestress directed radially inwards using a peripheral hoop. The radial inward prestress opposes the effects of centrifugal force. However, the prestress can decrease over time, in particular due to the creep of the materials.

[0013]

[0011] The inventors sought to propose a solution for arranging and maintaining the magnets in an axial flux rotor, capable of supporting very high rotation speeds while maintaining good mechanical cohesion, and maintaining satisfactory dynamic balancing.

[0014] For this purpose, a rotor for an axial flux electrical machine is proposed, comprising a star-shaped body comprising a hub and branches extending radially outwards from the hub, a location being formed between each pair of adjacent branches, the rotor comprising magnet blocks, each location being configured to accommodate a magnet block, each location being delimited on the one hand at the bottom by a first wall of the hub, and on the other hand on each side respectively by a face of the adjacent branches framing the location, the magnet blocks being bordered radially on the outer side by a cylindrical hoop, characterized in that there is provided in the first wall, a housing capable of receiving an elastomer shim, interposed between the first wall and a magnet block,the cylindrical hoop being configured to exert a radial force on each of said magnet blocks so as to compress the elastomeric shim between a magnet block and the hub.,

[0015]

[0013] Advantageously, the elastomer shim is compressed in the radial direction and absorbs part of the radial prestressing forces. Furthermore, the material of the elastomer shim is not subject to significant creep and its prestressing force absorption remains constant over the life cycle of the rotor.

[0016]

[0014] This forms a reliable and robust radial setting, compatible with very high rotation speeds and a very severe mission profile.

[0017]

[0015] The term 'elastomer shim' means a shim made of elastic or resilient material, the term elastomer being interpreted broadly and covering any type of elastic material.

[0018]

[0016] The presence of the elastomer shim and its elasticity also makes it possible to take into account possible dispersions in the chain of ribs between the branches, the magnet block and the cylindrical hoop.

[0019]

[0017] It is noted that the rotor is configured to rotate around a rotor axis denoted A. The rotor has two main faces which extend perpendicular to the axis.

[0020]

[0018] In this document, a cylindrical spatial reference is used based on the machine axis merged with the rotor axis A, as illustrated in Figure 2 top right. The expressions "radially inwards" and "radially outwards" must be understood in relation to the rotor axis A. "Axially" characterizes a direction parallel to the axis or merged with the axis. "Tangentially" characterizes a direction perpendicular to the local radius and perpendicular to the axis.

[0021]

[0019] According to one embodiment, the elastomer wedge comprises a support sole and a support head.

[0022] The retaining plate is housed in the housing. The bearing head projects from the plate relative to the first wall, radially outwards. The retaining plate does not project relative to the first wall.

[0023]

[0021] According to one embodiment, the hub comprises a groove extending in the hub axially at the level of the first wall, the retaining sole has a shape complementary to said groove so as to allow the insertion of the sole into the groove.

[0024] [C The complementary shapes provide positive and reliable support of the wedge in the desired position.

[0025]

[0023] According to one embodiment, the groove has a cylindrical section, at least in part, with an opening towards the location, radially outwards. The wedge comprises a neck between the sole and the head. Said neck between the sole and the head passes into the opening of the groove.

[0026]

[0024] According to one embodiment, the groove opens onto at least one main face, i.e. one side of the hub, so as to make the elastomer shim visible when the magnet block is mounted in the location.

[0025] According to an alternative embodiment, the housing comprises a dovetail groove to allow the sole of the shim to expand under compressive stress. Expressed differently, the compression of the shim causes the sole to widen, filling the lateral edges of the dovetail-shaped housing, which reinforces the retention of the shim inside the housing.

[0027] Advantageously, the housing is formed by a single stroke of the machining cutter.

[0028]

[0027] The housing comprises a bottom and a mouth. The housing is dead-end. The housing comprises a first rectilinear portion of trapezoidal section and a second bottom portion of circular shape corresponding to the cutting part of the cutter.

[0029] According to one embodiment, the direction of insertion of the wedge is parallel to the machine axis A. As a result, the effects of centrifugal force are reduced compared to the direction of insertion of the wedge which is perpendicular to the local radial direction. Indeed, the centrifugal force generated by the rotational speed does not tend to move the wedge back.

[0030] According to one embodiment, the elastomer shim is made of silicone.

[0031] This material can withstand temperatures up to 140°C without degradation of mechanical properties and without long-term deterioration.

[0032]

[0031] According to another embodiment, depending on the more or less demanding constraints in temperature resistance, the elastomer shim can be made of polyurethane.

[0033] [C According to one embodiment, the support head is symmetrical with respect to a median transverse plane of the rotor. Advantageously, the compression reaction does not create an axial component. The dynamic balancing of the rotor is not altered.

[0034]

[0033] According to one embodiment, the support head is symmetrical with respect to a median axial plane of the location and the housing.

[0035]

[0034] According to one embodiment, an injected glue is provided from an injection point, preferably close to the shim, the injected glue being configured to fill at least one available gap between the first wall and the magnet block.

[0036]

[0035] Cleverly, the presence of the glue prevents the shim from coming out of its housing. Preferably the glue is of the thermosetting type; it is noted that once the assembly of the rotor is finished, the rotor cannot be dismantled, it is formed as a definitive and durable assembly.

[0037]

[0036] According to one embodiment, the support head has a circular disc shape, preferably with a diameter between 0.4 x E1 and 0.85 x E1, where E1 is the axial thickness of the hub. It is preferably possible to have a support head diameter between 0.5 x E1 and 0.85 x E1.

[0038]

[0037] According to one embodiment, the support head may have a diamond shape in front view. This type of shape can improve the penetration and progression of the glue at the time of injection and its path to surround the support head of the wedge.

[0039]

[0038] According to one embodiment, the glue continuously surrounds the support head at least in a tangential section.

[0039] According to one embodiment, the glue fills all the space left free between the first wall and the magnet block and between the magnet block and the faces of the adjacent branches framing the location.

[0040] The present invention also relates to an electrical machine comprising at least one stator and at least one rotor as described previously, the electrical machine having a machine axis merged with the rotor axis, and the electrical machine being intended to move a motor vehicle.

[0041]

[0041] According to one embodiment, the electric machine may be intended to move a land vehicle of any kind, e.g. a railway vehicle, or even an aeronautical vehicle, or a maritime vehicle.

[0042] The present invention also relates to a method of mounting a rotor as described above, said method comprising the steps:

[0043] - Mounting of at least one elastomer shim at the bottom edge of the hub,

[0044] - Mounting a magnet block in the hub housing so that the magnet block comes into contact with the at least one elastomer shim, and

[0045] - Mounting the cylindrical hoop around the hub, said cylindrical hoop exerting radial pressure on the magnet block so as to compress the elastomer shim between the hub and the magnet block, thus holding the magnet block in place between the hub and the cylindrical hoop.

[0046]

[0043] According to one embodiment, the method may further comprise a step of compressing the elastomer shim prior to mounting the cylindrical hoop, said hoop making it possible to keep the elastomer shim compressed.

[0047]

[0044] According to one embodiment, the method may further comprise a step of injecting glue between the hub and the magnet block so as to fix the magnet block to the hub or at least to fill the spaces between the magnet block and the hub, the elastomer shim being at least partly covered by said glue.

[0048]

[0045] The invention will be further detailed by the description of non-limiting embodiments, and on the basis of the appended figures illustrating variants of the invention, in which:

[0049] - [Fig.1] illustrates very schematically an axial flux electric machine;

[0050] - [Fig.2] shows, schematically, in a cross-section through the axis, a first example of embodiment of a rotor according to the invention, two blocks of magnets being missing, figures 2 to 10 illustrating said first example of embodiment;

[0051] - [Fig.3] schematically illustrates in perspective view and partially the body of the rotor with a single magnet block in place;

[0052] - [Fig.4] illustrates an area of ​​the hub with the mounting of an elastomer shim, seen from the front (portion 4A) and seen from the side (portion 4B);

[0053] - [Fig.5] illustrates in transverse view to the axis the assembly of an elastomer shim, before assembly of the shim;

[0054] - [Fig.6] illustrates in perspective view and partially an example of a rotor with a missing magnet block, after assembly of the wedge and compression;

[0055] - [Fig.7] illustrates in perspective view and partially an example of a rotor with a missing magnet block; - [Fig.8] illustrates in perspective view and partially an example of a rotor with a missing magnet block, from another point of view;

[0056] - [Fig.9] illustrates a sectional view of a side slice of magnet block received in branch grooves, along section line IX-IX shown in Figure 2 view;

[0057] - [Fig.10] illustrates a variant where the support head of the wedge has a diamond shape,

[0058] - [Fig.11] shows, partially, in a cross-section to the axis, a second exemplary embodiment of a rotor according to the invention, with a single magnet block represented, figures 11 to 14 illustrating said second exemplary embodiment,

[0059] - [Fig.12] is similar to figure 11 and illustrates in perspective view and partially the second example of rotor with a magnet block,

[0060] - [Fig.13] illustrates in perspective view the hub with the locations for the magnet blocks and the housings for the shims,

[0061] - [Fig.14] illustrates in perspective view an example of an elastomer shim.

[0062] In the various figures, the same references designate identical or similar elements. For reasons of clarity of the presentation, certain elements are not necessarily represented to scale.

[0063]

[0047] The present document focuses on electrical machines used in motor vehicles. These may be machines of fairly substantial power belonging to an electromotive group capable of moving the vehicle, i.e. so-called traction machines.

[0064] The electrical machine in question can operate in motor mode or in generator mode depending on certain operating phases.

[0065]

[0049] It should however be noted that the principle and the technical solution put forward in the present document can be applied to electrical machines other than traction machines or even outside of use in a motor vehicle.

[0066] The machine of interest can be installed on a land vehicle of any kind, e.g. a railway vehicle, or even an aeronautical vehicle, or a maritime vehicle.

[0067] General architecture (1st and 2nd examples of realization)

[0068] As already mentioned in the introductory part and visible in figure 1, an axial flux electric machine marked 100 generally comprises a rotor 10 forming a rotating part around a machine axis A, and at least one stator forming a complementary non-rotating part.

[0069]

[0053] In the example illustrated, two stators 91, 92 are provided, namely one stator on either side of the rotor.

[0070]

[0054] The rotor 10 is securely connected to a machine shaft denoted 11, as will be seen later. The rotor shaft is mounted to rotate around the axis A, relative to the casing by means of bearings as known per se.

[0071] The rotor carries a series of permanent magnets, also called magnet blocks 4 here, while a series of coils are carried by the stators.

[0072] When the coils are supplied with an electric current, the rotor, which is secured to the machine shaft 11, is subjected to a torque resulting from the magnetic field (the magnetic flux created being an axial flux for an axial flux electric machine).

[0073]

[0057] The rotor 10 has the general shape of a thick disc centered on the machine axis A. The rotor has a thickness denoted E1 which is much smaller than its diameter D9. D9 can take a value between 150 mm and 450 mm.

[0074] In practice, the axial dimension of the rotor E1 can be chosen from 7 mm to 25 mm. Depending on a particular embodiment, E1 can be between 12 mm and 15 mm.

[0075]

[0060] The rotor 10 has two main faces, marked 17 and 18 respectively, circular and opposite. Each of these faces 17, 18 is flat except in the central zone of the hub where it may have through holes.

[0076]

[0061] Figures 2 to 10 illustrate a first embodiment / exemplary embodiment of the invention, in which it is provided to inject glue in addition to the presence of the elastic shim as will be described later. The term “glue” also describes an agent for filling the gaps between the hub and the magnet.

[0077] [C Figures 11 to 14 illustrate a second embodiment / exemplary embodiment of the invention. It should be noted from the outset that in this second exemplary embodiment, the presence of the glue is optional; the glue may be completely absent.

[0078]

[0063] As shown in Figures 1 to 3, the rotor 10 comprises a star-shaped body marked 8. The star-shaped body 8 comprises a hub 1 and branches 2 extending radially outward from the body. The axial thickness of the hub is substantially identical to the axial thickness of the branches which also corresponds substantially to the axial thickness E1 of the rotor.

[0079] According to one example, the star-shaped body 8 is made of a composite material, for example based on glass fibers embedded in a polymer resin.

[0080] It is not excluded to manufacture the star body in metal or in synthetic material with high mechanical performance.

[0081] A location 3 is formed between each pair of adjacent branches.

[0082] The rotor 10 comprises magnet blocks 4. Each location 3 is configured to accommodate a magnet block 4.

[0083] The number of magnet blocks 4 is the same as the number of branches 2 and the number of locations. In the example shown, this is a configuration with 12 magnet locations and 12 branches. The number in question could also be 16. It is not excluded that this number is smaller than 12 or larger than 16.

[0084]

[0069] The magnet blocks 4 are bordered radially on the outer side by a cylindrical hoop 9. It is noted that the hoop 9 may or may not be in contact with the distal ends 23 of the branches. The hoop 9 exerts a radial compression force FC. The hoop 9 absorbs the radial forces generated by the inertial forces exerted on the magnet blocks 4.

[0085]

[0070] According to a preferred embodiment, the hoop 9 is made of carbon fibers wound under tension.

[0086]

[0071] According to a variant, the hoop could be made of steel, aluminum alloy or titanium alloy, for example heated prior to assembly.

[0087] Each location 3 is delimited on the one hand at the bottom by a first wall 7 of the hub, and on the other hand on each side respectively by a face 21, 22 of the adjacent branches framing the location. In cross-section, each location 3 has a generally trapezoidal shape, or more complex, capable of receiving a magnet block 4 by complementarity of shapes.

[0073] Each magnet block 4 is encapsulated in a plastic case.

[0088]

[0074] Each magnet block may comprise a plurality of juxtaposed unit magnets.

[0089]

[0075] As is more particularly apparent from FIG. 3, each magnet block 4 here has a generally trapezoidal shape. Each magnet block 4 thus comprises two main faces 46, 47 of substantially trapezoidal shape, extending transversely to the axis A.

[0090]

[0076] Each magnet block 4 comprises two lateral faces 41, 42. Within the rotor 10, each lateral face 41, 42 faces a branch 21, 22.

[0091]

[0077] Each magnet block 4 also comprises an internal face 48, facing the hub 1. Finally, each magnet block 4 comprises an external face 49. The external face 49 is located on the periphery of the rotor 10 and generally has an arc-shaped curvature. The external face 49 is put under pressure by the hoop 9.

[0092]

[0078] According to one option, all the magnet blocks 4 are identical. A mechanical keying device 74 may be provided which makes it possible to avoid mounting the magnet block upside down.

[0093]

[0079] Each magnet block 4 is clamped between two adjacent branches by means of sliding connections, here of the groove-rib type, which serve to retain the magnet block stressed by forces along the axis A.

[0094] To produce sliding connections, in the example illustrated here, in particular illustrated in figure 9, each branch face comprises a hollow groove 25 which extends in a direction of extension of the branch 2, along the respective face 21, 22.

[0095]

[0081] In return, each magnet block 4 comprises, at each of its lateral faces 41, 42, a rib 45, configured to be inserted into one of the aforementioned grooves 25. Such an assembly limits the position of the magnet blocks 4 in translation along the axis A. The position is subsequently locked by the injection of an element filling the spaces between the magnet block 4 and the hub 1 as will be described later.

[0096] Of course, it would be possible to use reversed shapes, namely a rib on the branch and a groove on the magnet block.

[0097] Wedges (1st example of realization)

[0098] Figure 5 is a more detailed view of the area of ​​the shim 5 and its mounting in the housing 6.

[0099] The elastomer wedge 5 comprises a support sole 51 and a support head 52.

[0100] In one example, the elastomer shim 5 is made of silicone. In another example, the elastomer shim may be made of polyurethane or any other thermoplastic material.

[0101]

[0087] The support sole 51 is parallelepipedal with a thickness E6. The thickness E6 may be between 1 mm and more than 3 mm, preferably between 1 mm and 3 mm. The support sole is generally parallelepipedal. The support sole has a length H5 and a width L5.

[0102] The width L5 can be for example 0.4 x E1 and 0.85 x E1. The length H5 can be for example 0.7 x E1 and 0.85 x E1.

[0103] The shim is inserted in the W direction, parallel to A, over a stroke approximately equal to H5. The housing being in a dead end, the insertion ends when the semi-circular part of the sole comes to a stop against the bottom of the dovetail housing.

[0104] The support head 52 is symmetrical with respect to a median transverse plane of the rotor PTM. This is visible in particular in Figure 4. The median transverse plane is located halfway through the thickness of the rotor, equidistant from the main faces of the rotor.

[0105]

[0091] The support head 52 has a thickness E7 which can be between 1 mm and more than 3 mm, preferably between 1 mm and 3 mm. The total thickness of the shim denoted E5 is equal to the sum of E6 and E7.

[0106] [C Under a compressive stress of 500 Newton, the total thickness of the shim 5 can decrease by 0.7 mm (in the case of a thickness less than 3 mm) due to its partial crushing.

[0107] When the wedge is compressed, as seen in Figure 6, the sole flares inside the dovetail profile 61.

[0108] In addition, the bearing head is symmetrical about a median axial plane of the PAM location. The median axial plane PAM passes through the A axis and separates the magnet block into two symmetrical parts.

[0109]

[0095] According to the example illustrated, the support head has the shape of a circular disc, preferably with a diameter E2 of between 0.4 x E1 and 0.85 x E1, E1 being the axial thickness of the hub 1.

[0110] It is preferable to have a support head diameter E2 of between 0.5 x E1 and 0.8 x E1.

[0111] The housing 6 includes a dovetail groove 61, to allow the sole of the wedge to expand under stress.

[0112] Glue (1st example of production)

[0113] According to this configuration, it is planned to use a glue rated GF also called in the trade 'gap filler'. The glue is injected while it is in a pasty phase, with sufficient fluidity to fit into all the spaces available in the cavity defined by an injection mold in which the rotor is placed.

[0114]

[0100] The GF glue is injected from an injection point 16 near the wedge, with an injection channel 15. Of course, the rotor 10 is placed in an injection mold so that the glue cannot overflow from the main faces 17, 18 of the rotor.

[0115] The injected glue is configured to fill at least one available gap between the first wall 7 and the magnet block 4. From the injection channel 15, the GF glue continues its progression inside the spaces left empty on either side of the support head via the channels 72 provided for this purpose. A vent may be provided to allow the air that is expelled by the advance of the glue to escape.

[0116] Preferably, according to one embodiment, as visible in figures 7 and 8, the glue fills all the space left free between the first wall 7 and the magnet block 4 and the glue fills all the space left free between the magnet block 4 and the faces 21, 22 of the adjacent branches framing the location.

[0117] Generally speaking, the injected GF glue is configured to fill at least one available gap between the first wall 7 and the magnet block 4.

[0118]

[0104] The glue can be of the thermosetting type. After injection and filling of the empty spaces, the rotor is placed in the oven to solidify the GF glue.

[0119] Then the solidified glue confines the wedge in its position.

[0106] It is noted that GF glue can be subject to a creep phenomenon over time and long exposure to inertial forces in a high temperature environment (100°C or more).

[0120] Wedges and housings (2nd example of realization)

[0121] As shown in Figures 11 to 13, the hub 1 of the rotor comprises at the location of each location 3 for magnet block 4 a groove 6 which extends parallel to the axis of the rotor. This groove forms a housing for receiving at least part of the elastic shim which is shown in Figure 14.

[0122] The groove has a cylindrical section, at least in part, with an opening 64 open towards the opposite location 3. In other words, the opening 64 opens the groove along its length, radially outwards.

[0123] The groove opens axially through a mouth 67 at least on at least one main face 17 or 18, i.e. on one side of the hub. It is through this axial mouth noted 67 that the shim 5 is inserted.

[0124] It is noted that the elastomer shim remains visible when the magnet block 4 is mounted in location 3. It is thus possible to check the presence and correct positioning of the shim once their rotor is fully equipped.

[0125] The groove may open on one side only, in which case a groove bottom 60 is provided opposite the mouth 67.

[0126] The retaining sole 51 of the wedge has a diameter D8, for example between 3 mm and 8 mm, the height of the wedge is uniform on the retaining sole and the head, it is noted H8, H8 can be between 5 mm and 12 mm.

[0127] The support head has a thickness of E7. E7 can be between 1 mm and 3 mm.

[0128] The support head has a width of W8. W8 can be between 10 mm and 25 mm.

[0129] E7 + D8 represents the total dimension of the shim in the radial direction.

[0130] The shim 5 comprises a neck 54 between the sole 51 and the head 52. Said neck 54 between the sole and the head passes into the opening 64 of the groove, and is housed there without play, which contributes to the blocking of the shim 5. The dimension D7 of the neck can be, according to an evaluation example, close to half the diameter D8.

[0131] The hollow shape marked 68 in figure 13 allows, if necessary, glue to be injected into the gap remaining between the magnet block and the hub 1. However, as already mentioned above, the presence of glue is not an obligatory option.

[0132] Additional features and various characteristics

[0133] Regarding the rotor assembly, the shims 5 are first placed in the housings 6 (one shim per housing and per location, twelve in all in the example illustrated).

[0134] The shims hold well in place because for the first embodiment, the width L5 can be chosen slightly greater than the width of the upper opening of the dovetail housing, hence a slight tightening during insertion. For the second embodiment, the diameter D8 can be chosen slightly greater than the diameter of the groove 6.

[0135] Then we place the magnet blocks 4 in the locations 3 (one per location).

[0136]

[0123] Then the hoop 9 is placed or formed. The radial stress may result from the actual assembly of the hoop or from a subsequent operation. Then, for the first embodiment, the glue injection step explained above is carried out.

[0137] Note that it is not excluded to proceed with the glue injection step before installing the hoop 9.

[0138]

[0126] Furthermore, it may be provided that the method comprises a step of compressing the elastomer shims prior to mounting the cylindrical hoop, said hoop making it possible to keep the elastomer shim compressed.

[0139] The shaft can be fixed to the rotor via a flange by bolting which uses the holes 14 visible in figure 7. This assembly is known in itself and therefore not described in detail here.

[0140] Alternatively or additionally, the transmission of torque between the hub 1 and the shaft 11 can be done by means of a key 13 as shown in Figure 2.

[0141]

[0129] It can be seen in Figure 5 that the root of the branches 2 includes a fillet 78 which makes it possible to reduce local stresses and increase resistance to stresses and reduce any possible fatigue phenomenon.

[0142]

[0130] Concerning the radial dimensions, the radius R1 of the hub bore can typically be between 10 mm and 90 mm. The radial dimensions in question are to be adapted according to the sizing, e.g. the desired power for the electric machine, the number of rotors and the thickness of these rotors.

[0143] The radius R2 of the hub can typically be between 20 mm and 100 mm. The radius R3 at the end of the branches can typically be between 80 mm and 200 mm. The radius R9 (D9 / 2) outside the hoop 9 can typically be between corresponds to R3 to which is added the thickness of the hoop which can range from less than 6 mm to 35 mm, preferably from 6 mm to 35 mm.

[0144] As illustrated in Figure 8, it is provided to be possible to check the correct presence of the shim 5 in the housing 6 even after filling the interstices with the GF glue, thanks to the flush end 53 of the sole 51 of the shim 5.

[0145]

[0133] The axial thickness E4 of the ribs 45 can be between 1 / 5 and 1 / 3 of E1.

[0146] As illustrated in Figure 10, the support head 52 may have, instead of a circular section, in front view, a diamond shape or a square shape. Depending on the viscosity of the glue, this arrangement can facilitate the progression of the glue and the filling of all the available volume gaps.

[0147]

[0135] Other forms of support head are of course possible, preferably with symmetry relative to the median transverse plane PTM as well as symmetry relative to the median axial plane PAM.

[0148]

[0136] Of course, the invention is not limited to the examples which have just been described and numerous adjustments can be made to these examples without departing from the scope of the invention. In particular, the characteristics of the different variant embodiments of the invention envisaged in this application can be combined to achieve the invention, insofar as these variants are not incompatible with each other. It should be noted that concerning the second exemplary embodiment, everything which is not described again is assumed to be identical or similar to what was described for the first exemplary embodiment.

Claims

CLAIMS 1. Rotor (10) for an axial flux electrical machine, comprising a star-shaped body (8) comprising a hub (1) and branches (2) extending radially outwards from the hub, a location (3) being formed between each pair of adjacent branches, the rotor comprising magnet blocks (4), each location being configured to accommodate a magnet block (4), each location being delimited on the one hand at the bottom by a first wall (7) of the hub, and on the other hand on each side respectively by a face of the adjacent branches framing the location, the magnet blocks being bordered radially on the outer side by a cylindrical hoop (9), characterized in that there is provided in the first wall, a housing (6) capable of receiving an elastomer shim (5), interposed between the first wall and a magnet block,said cylindrical hoop (9) being configured to exert a radial force on each of said magnet blocks (4) so ​​as to compress the elastomer shim (5) between a magnet block (4) and the hub (1).

2. Rotor according to claim 1, in which the elastomer shim comprises a holding sole (51) and a support head (52).

3. Rotor according to the preceding claim, in which the hub comprises a groove extending axially at the level of the first wall (7), the holding base has a shape complementary to said groove so as to allow the insertion of the base into the groove.

4. Rotor according to claim 2, characterized in that the housing comprises a dovetail groove (61) to allow the wedge retaining sole to expand under compressive stress.

5. Rotor according to one of claims 1 to 4, characterized in that the insertion direction (W) of the wedge is parallel to the rotor axis (A).

6. Rotor according to any one of claims 1 to 5, in which the elastomer shim is made of silicone.

7. Rotor according to any one of claims 1 to 6, in which there is provided an injected glue from an injection point (16), preferably close to the shim, the injected glue being configured to fill at least one available gap between the first wall and the magnet block.

8. Electrical machine comprising at least one stator and at least one rotor according to any one of claims 1 to 7, the electrical machine having a machine axis merged with the rotor axis, and the electrical machine being intended to move a motor vehicle.

9. Method for mounting a rotor according to one of claims 1 to 7, said method comprising the steps of: - Mounting of at least one elastomer shim (5) at the level of a bottom edge of the hub (1), - Mounting a magnet block (4) in the housing of the hub (1) so that the magnet block (4) comes into contact with the at least one elastomer shim (5), and - Mounting the cylindrical hoop (9) around the hub (1), said cylindrical hoop (9) exerting radial pressure on the magnet block (4) so ​​as to compress the elastomer shim (5) between the hub (1) and the magnet block (4), thus holding the magnet block (4) in place between the hub (1) and the cylindrical hoop (9).

10. Method according to the preceding claim, further comprising a step of compressing the elastomer shim prior to mounting the cylindrical hoop, said hoop making it possible to keep the elastomer shim compressed.

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