Rotor for a rotary electric machine

Abstract

The invention relates to a rotor (1) for a rotary electric machine, the rotor comprising a rotor mass, the rotor mass comprising a plurality of cavities (2) for accommodating one or more permanent magnets (3) defining the magnetic poles (10) of the rotor (1), wherein each of the the magnetic poles (10) extends along a polar axis (X), wherein the cavities (2) of a magnetic pole (10) are arranged in at least one first (4) and one second row (5) of cavities (2), wherein the second row (5) of cavities (2) is closest to the surface (7) of the rotor mass, wherein the rotor mass comprises, at the surface for at least one given magnetic pole (10), a single central notch (6) through which the polar axis (X) of the corresponding magnetic pole (10) passes, and wherein the single central notch (6) is cut at the surface (7) of the rotor mass between the ends (5a, 5b) of the second row.

Description

[0001] Description

[0002] Title: Rotor of a rotating electric machine

[0003] The present invention claims priority from French application 2313802 filed on December 7, 2023, the content of which (text, drawings and claims) is incorporated herein by reference.

[0004] Technical field

[0005] The present invention relates to rotating electrical machines, and more particularly to the rotors of such machines, in particular rotors comprising housings arranged in one or more rows within the rotor mass.

[0006] The invention relates more particularly to synchronous or asynchronous alternating current machines. It relates in particular to traction or propulsion machines for electric motor vehicles (Battery Electric Vehicle) and / or hybrid vehicles (Hybrid Electric Vehicle - Plug-in Hybrid Electric Vehicle) and / or electric propulsion via the rear axle (eRAD for Electrical Rear Axle Drive), such as private cars, vans, trucks or buses. The invention also applies to rotating electrical machines for industrial and / or energy production applications, in particular naval, aeronautical or wind power applications.

[0007] Prior art

[0008] It is known to make notches on the rotor mass in order to reduce the torque ripple of the electric machine and obtain a general reduction in the amplitudes of the spatio-temporal harmonics linked to the active parts. They therefore allow the general improvement of the rendering of noise and vibrations within the machine.

[0009] Applications JP 2014 / 075882, EP 2 518 871 and EP 2 355 306 describe rotors having a single row of two housings arranged in a V. In applications EP 2 518 871, EP 2 355 306 and US 2017 / 201136, the rotor mass has a single notch per pole, said notch being symmetrical or asymmetrical with respect to the polar axis.

[0010] In US application 2022 / 0181927, there are several notches between the two ends of the row closest to the air gap.

[0011] Applications WO 2020 / 221543, WO 2022 / 035366, EP 4 096 064, US 2021 / 0184520, WO 2019 / 215853 describe rotors comprising a plurality of notches spaced from the polar axis, placed between the ends of the rows of magnets.

[0012] US2017 / 317540 discloses a rotor having groups of notches.

[0013] There is a need, particularly in the field of rotating electrical machines with multiple rows of housings within the rotor mass, to have rotating electrical machines with low torque ripple, minimizing noise and vibration within the machine, without risking a reduction in machine performance.

[0014] Statement of the invention

[0015] The present invention meets all or part of this need and thus relates to a rotor of a rotating electrical machine, comprising a rotor mass, the rotor mass comprising a plurality of housings for receiving one or more permanent magnets defining magnetic poles of the rotor, the magnetic poles each extending along a polar axis, the housings of a magnetic pole being arranged in at least a first and a second row of housings, the second row of housings being closest to the surface of the rotor mass, the rotor mass comprising on the surface for at least one given magnetic pole a single central notch crossed by the polar axis of the corresponding magnetic pole, the single central notch being cut on the surface of the rotor mass between the ends of the second row.

[0016] At least one of the magnetic poles of the rotor mass, better a majority of the magnetic poles, or even all of the magnetic poles, have a single central notch made on the surface of the rotor mass between the ends of the second row.

[0017] At least one of the magnetic poles of the rotor mass, better a majority of the magnetic poles, or even all of the magnetic poles, have a single central notch crossed by the polar axis of the corresponding magnetic pole.

[0018] The presence of a single central notch crossed by the axis of the corresponding magnetic pole improves the harmonic signature of the torque. It allows the reduction of torque ripple and the reduction of spatio-temporal harmonic amplitudes linked to the active parts. It therefore allows the general improvement of the rendering of noise and vibrations within the machine. It also allows better modulation of the harmonic sources of critical temporal mechanical orders which are likely to resonate with given spatial structural modes.

[0019] The presence of the single central notch within the rotor mass allows the interference of harmonics related to the stator slots, in order to reduce the interactions between the harmonics emitted by the rotor vibrations and those caused by the variation of the air gap reluctance. This can reduce the amplitude of these harmonic pressure orders and thus reduce the noise of the machine.

[0020] The angular extent of a magnetic pole can be between 10° and 90°, or even between 20° and 80°, or even between 30° and 70°, being for example 60°, or even between 40° and 50°, being notably 45°.

[0021] Summary of the invention

[0022] Central notch

[0023] The single central notch may be symmetrical about the polar axis of the corresponding magnetic pole. Each single central notch may be symmetrical about the polar axis of the corresponding magnetic pole. 'Symmetrical' means that the polar axis passes through the central notch in its middle. Alternatively, the central notch may be asymmetrical. The polar axis may pass through it at any point, delimiting a first part and a second part of the central notch. The first part may be larger than the second part. Alternatively, the first part may be smaller than the second part.

[0024] The central notch may have a notch bottom, the bottom of the central notch being able to extend circumferentially, in particular along an arc of a circle. The central notch may also have two lateral sides arranged on either side of the bottom of the central notch.

[0025] The lateral sides of the central notch may form a right angle with the surface of the rotor mass, in particular with the normal thereto. Alternatively, the lateral sides of the central notch may have an inclination other than 90° with respect to the surface of the rotor mass, in particular with the normal thereto. The angle of inclination may be between 5 and 85°, or even between 10 and 80°, better still between 15 and 75°, even better still between 20 and 70°, in particular between 25 and 65°, or even between 30 and 60°, being for example approximately 43°. Furthermore, the angle of inclination of a lateral side with the bottom of the central notch can be between 5 and 85°, or even between 10 and 80°, better still between 15 and 75°, even better still between 20 and 70°, in particular between 25 and 65°, or even between 30 and 60°, being for example approximately 43°.

[0026] The junction between the bottom of the central notch and the lateral sides on the one hand, and on the other hand between the lateral sides and the surface of the rotor mass can be made with a curvature. In one embodiment, each lateral side has two curvatures, respectively in connection with the bottom of the central notch and in connection with the surface of the rotor mass. The two curves can be substantially identical, with an identical radius of curvature. The radius of curvature can be between 0.1 mm and 0.5 mm, or even between 0.2 mm and 0.4 mm, being for example approximately 0.3 mm. Alternatively, the radii of curvature can be different.

[0027] The central notch may have a depth E. The depth E may be defined as the difference between the radius of the rotor mass independent of the central notch and the radius of the rotor mass measured in the bottom of the central notch. The depth E of the central notch may be between 0.1 mm and 0.5 mm, better between 0.2 mm and 0.4 mm, being in particular of the order of 0.3 mm, for example approximately 0.35 mm.

[0028] The central notch may have roughness. 'Roughness' refers to reliefs whose height remains strictly less than the depth E of the central notch. Alternatively, the central notch may not have roughness.

[0029] The depth of the central notch may be constant. In particular, in the case of the presence of asperities, the depth of the central notch may be substantially constant at locations without the presence of asperities. The depth of the central notch at the level of the asperities is, for example, less than 75%, even less than 50%, in particular less than 25% of the depth of the central notch at locations without the presence of asperities.

[0030] Side notches

[0031] The rotor mass may comprise on the surface for at least one given magnetic pole two lateral notches, in particular only two lateral notches, each lateral notch being cut on the surface of the rotor mass between one end of the first row of housings and one end of the second row of housings.

[0032] At least one of the magnetic poles of the rotor mass, better a majority of the magnetic poles, or even all of the magnetic poles, comprise two lateral notches, in particular only two lateral notches, each lateral notch being cut on the surface of the rotor mass between one end of the first row of housings and one end of the second row of housings.

[0033] The two lateral notches are each arranged on either side of the polar axis of the corresponding magnetic pole. They may be symmetrical to each other with respect to the polar axis of the corresponding magnetic pole. Alternatively, they may not be symmetrical to each other with respect to the polar axis.

[0034] The rotor may have a single lateral notch between one end of the first row of housings and one end of the second row of housings, on the same side of the polar axis of the corresponding magnetic pole. The lateral notches may be of a similar shape to the central notch. Alternatively, they may be of different shapes. The two lateral notches may be of a similar shape to each other. Alternatively, they may be of different shapes.

[0035] Each lateral notch may have a lateral notch bottom, the lateral notch bottom being able to extend circumferentially, in particular along an arc of a circle. The lateral notch may also have two lateral sides arranged on either side of the lateral notch bottom.

[0036] The lateral sides of the lateral notch may form a right angle with the surface of the rotor mass, in particular with the normal thereto. Alternatively, the lateral sides of the lateral notch may have an inclination other than 90° relative to the surface of the rotor mass, in particular with the normal thereto. The angle of inclination may be between 5 and 85°, or even between 10 and 80°, better still between 15 and 75°, even better still between 20 and 70°, being for example approximately 25°. Furthermore, the angle of inclination of a lateral side with the bottom of the lateral notch may be between 5 and 85°, or even between 10 and 80°, better still between 15 and 75°, even better still between 20 and 70°, being for example approximately 25°.

[0037] The junction between the bottom of the lateral notch and the lateral sides on the one hand, and on the other hand between the lateral sides and the surface of the rotor mass can be made with a curvature. In one embodiment, each lateral side has two curvatures, respectively in connection with the bottom of the lateral notch and in connection with the surface of the rotor mass. The two curves can be substantially identical, with an identical radius of curvature. The radius of curvature can be between 0.1 mm and 0.5 mm, or even between 0.2 mm and 0.4 mm, being for example approximately 0.3 mm. Alternatively, the radii of curvature can be different.

[0038] The lateral notches may have a depth E1 and E2 respectively. The depth E1, respectively E2, may be defined as the difference between the radius of the rotor mass independently of the lateral notch and the radius of the rotor mass measured in the bottom of the corresponding lateral notch. The depth E1 or E2 of a lateral notch may be between 0.1 mm and 0.5 mm, better between 0.2 mm and 0.4 mm, being in particular of the order of 0.3 mm, for example approximately 0.275 mm.

[0039] Each lateral notch may have roughness. 'Roughness' means reliefs whose height remains strictly less than the depth E1 or E2 of the corresponding lateral notch. Alternatively, the lateral notches may not have roughness.

[0040] Such a configuration with a single central notch and two lateral notches can allow an 83% reduction in harmonic amplitudes linked to the effect of the stator notches, in particular the twelfth electrical harmonic, compared to 55% for a two-notch configuration and 5% for a four-notch configuration.

[0041] The presence of three notches with a single central notch and two lateral notches also allows a significant reduction in harmonic amplitudes, particularly of the twelfth harmonic, compared to a configuration without a notch. The ratio between the amplitude of the twelfth harmonic for a configuration with three notches and a configuration without a notch is of the order of 0.17.

[0042] Table 1 below shows the results of the calculations obtained from the amplitude of the twelfth harmonic in Nm, the results of the torque ripple indicated as a percentage and the results of the average torque in Nm.

[0043] Table 1 compares these three measurements for five different rotor configurations:

[0044] (i) a rotor according to the invention, comprising a single central notch and two lateral notches between the ends of the first and second row of magnets,

[0045] (a) a rotor without a notch,

[0046] (b) a rotor with two side notches without a central notch,

[0047] (c) a rotor having three central notches between the ends of the second row of magnets, and

[0048] (d) a rotor with four notches. [Table 1]

[0049] Table 1

[0050] The rotor according to the invention allows a reduction in torque ripple compared to other configurations. The impact of the configuration of the notches as defined by the invention on the torque ripple also allows a reduction in the amplitude of the twelfth harmonic, compared to all other configurations.

[0051] The two lateral notches can each be separated by an angle [3 equal to the polar axis of the corresponding magnetic pole.

[0052] Alternatively, the two side notches can each be spaced apart at a different angle relative to the polar axis of the corresponding magnetic pole.

[0053] At least one lateral notch, or even both lateral notches, may be spaced from the polar axis of the corresponding magnetic pole by an angle [3 of between 10° and 20°, or even between 12° and 18°, or even between 13° and 16°, being in particular approximately 14.3°.

[0054] To measure the angular position of the side notch, we consider the angular position of the middle of the side notch.

[0055] The central notch may have an angular opening a greater than the angular opening of one of the two lateral notches, the angular opening a of the central notch being in particular between 3° and 10°, in particular between 5° and 8°, or even between 6° and 7°, being in particular approximately 6.64°.

[0056] The central notch may have an angular opening a greater than that of one of the two lateral notches. Alternatively, the central notch may have an angular opening less than that of one of the two lateral notches. Alternatively, the central notch may also have an angular opening a equal to that of one of the two lateral notches.

[0057] A ratio a / y between the angular opening a of the central notch and the angular opening y of one of the two lateral notches can be between 1.25 and 3, or even between 1.5 and 2.5, better between 1.75 and 2, being in particular approximately 1.95.

[0058] The angular opening a of the central notch may be less than the spacing between the first and second rows of housings at the surface of the rotor mass. Alternatively, the angular opening a of the central notch may be greater than the spacing between the first and second rows of housings at the surface of the rotor mass. Alternatively, the angular opening a of the central notch may be equal to the spacing between the first and second rows of housings at the surface of the rotor mass.

[0059] The angular opening between the two rows of housings can be between 2° and 10°, better between 4° and 7°, being in particular of the order of 5°, for example approximately 5.32°.

[0060] The spacing between the rows of housings at the surface of the rotor mass may be between 2 mm and 10 mm, better between 4 mm and 7 mm, being in particular of the order of 5 mm, for example approximately 4.92 mm.

[0061] The central notch may have a circumferential length L greater than a circumferential length Li of one of the two lateral notches, in particular a circumferential length L of between 5 mm and 8 mm, or even between 5.5 mm and 7.5 mm, better still between 6 mm and 6.3 mm. The circumferential length L of the central notch may in particular be of the order of 6.13 mm.

[0062] A ratio between a circumferential length L of the central notch and a circumferential length Li of one of the two lateral notches can be between 1.25 and 3, or even between 1.5 and 2.5, better between 1.75 and 2, being in particular approximately 1.95.

[0063] The circumferential length L of the central notch may be less than the circumferential length of the second row, in particular of the second V-shaped row, on the surface of the rotor mass. Their ratio may be between 0.3 and 0.7, or even between 0.4 and 0.6, being in particular approximately 0.46.

[0064] An angular opening of the second row, in particular of the second V-shaped row, measured at the surface of the rotor mass can be between 10° and 18°, or even between 12° and 16°, or even between 13° and 15°, being for example 14.42°.

[0065] A circumferential length of the second row, in particular of the second V-shaped row, measured at the surface of the rotor mass may be between 10 and 16 mm, or even between 12 and 14 mm, being for example 13.2 mm.

[0066] At least one lateral notch, or even each lateral notch, may have an angular opening y of between 2° and 5°, better between 3° and 4°, being in particular of the order of 3.4°.

[0067] The circumferential length Li of a lateral notch may be less than the circumferential length of the spacing between the first row and the second row on the surface of the rotor mass. Their ratio may be between 0.4 and 0.8, or even between 0.5 and 0.7, being in particular approximately 0.6.

[0068] The angular opening y of a lateral notch may be less than the angular opening of the spacing between the first row and the second row on the surface of the rotor mass. Their ratio may be between 0.4 and 0.8, or even between 0.5 and 0.7, being in particular approximately 0.6.

[0069] The rotor may comprise bridges of material between end housings of the first row and / or the second row and the surface of the rotor mass, the bridges of material having an angular opening j in particular between 1° and 8°, preferably between 2° and 6°, better still between 3° and 4°.

[0070] The central notch may have an angular opening a greater than the angular opening j of the material bridges. The central notch may have a circumferential length L greater than the angular opening j of the material bridges between the housings.

[0071] The lateral notches may have an angular opening smaller than the angular opening j of the material bridges. The lateral notches may have a circumferential length Li smaller than the angular opening j of the material bridges.

[0072] A ratio between the sum of the angular openings of the central notch and the lateral notches on the sum of the angular openings j of the material bridges can be between 0.5 and 1.5, better between 0.8 and 1.2.

[0073] A ratio j / a between the angular opening j of the material bridges and the angular opening a of the central notch can be between 0.1 and 1, or even between 0.2 and 0.9, better between 0.3 and 0.8, being for example of the order of 0.5.

[0074] Rotor

[0075] The rotor can have 6 or 8 magnetic poles.

[0076] The housings of the first row may be arranged in a U-shape. Alternatively, the housings of the first row may be arranged in a V-shape. The housings of the second row may be arranged in a V-shape. The angular opening of the second V-shaped row may be between 10 and 20°, or even between 12 and 18°, better still between 14 and 16°, being in particular approximately 14.42°.

[0077] The first row of housings may comprise three housings arranged in a U-shape, with a central housing and two side housings. The two side housings may be symmetrical to each other about an axis of the magnetic pole. The first row of housings may also comprise a recess extending from the side housing towards the central housing.

[0078] Advantageously, the presence of two rows of housings makes it possible to increase the number of magnets received in the rotor mass, and thus to increase the resulting power density. It is thus possible to obtain more torque with the same rotor size. The invention advantageously makes it possible to improve the reluctant torque of the machine.

[0079] The second row may be closer to the air gap than the first row. The first row may be further from the air gap than the second row.

[0080] The rotor mass may comprise one or more stacks of laminations stacked on top of each other. Each stack of laminations may comprise at least one housing receiving the permanent magnet. In the case where the rotor mass comprises several stacks of laminations stacked on top of each other, the rotor mass may comprise, for a housing, one or more permanent magnets, for example one permanent magnet per stack of laminations.

[0081] The side housings of the first row may be provided with permanent magnets. The permanent magnets of the side housings of the first row may be identical to each other. In particular, they may have the same cross-sectional size.

[0082] The central housing of the first row may be provided with one or more permanent magnets, or alternatively be without them. Depending on the choice of whether or not to have a central permanent magnet, the rotor can advantageously allow a certain modularity for the resulting machine.

[0083] The central housing of the first row can be provided with a permanent magnet of the same size as the permanent magnets in the side housings.

[0084] Alternatively, the central housing of the first row can be provided with a permanent magnet smaller than the permanent magnets of the side housings. This is advantageous from an electromagnetic point of view. Indeed, since the permanent magnet is smaller than the housing, there is a portion of the housing that is empty on the sides of the magnet, which empty portion reduces electromagnetic leakage.

[0085] The second row may in particular comprise two housings arranged in a V. They may be symmetrical to each other with respect to an axis of the magnetic pole. In one embodiment, all the housings of the second row are provided with permanent magnets. The V-shaped configuration of the second row saves space and avoids any risk of saturation of the magnetic circuit.

[0086] The permanent magnets in the second row can be identical to each other. In particular, they can have the same cross-sectional size. The permanent magnets in the second row can have a different size than the permanent magnets in the first row, for example, being smaller.

[0087] At least one housing may include at least one stop for holding the permanent magnet intended to be received in the housing. Each housing may include a stop located towards the air gap. The lateral housings may also include a stop, for holding the permanent magnet.

[0088] The housings are each separated from the air gap by a material bridge whose width is determined by the mechanical strength constraints. Their width is approximately equal to at least the thickness of the magnetic sheet. The length of these bridges is approximately equal to the width of the housings.

[0089] The rotor may be devoid of cooling fluid circulation in the housings. In particular, the recesses are not configured to allow the circulation of a cooling fluid.

[0090] The rotor mass may be composed of a plurality of packets arranged consecutively along an axis of rotation of the rotor, two consecutive packets being angularly offset around the axis of rotation of the rotor by a non-zero elementary angle 5.

[0091] The total twist angle 5t is the sum of the elementary angles 5 between all consecutive packets shifted in the same direction around the axis of rotation. If one or more packets are shifted in the other direction, their shift is not counted. The total angle 5t is the maximum angle obtained by taking the largest number of consecutive packets shifted in the same direction. We mean by n the number of consecutive packets shifted in the same direction around the axis of rotation.

[0092] The total twist angle 5t can be in particular of the order of 5° or 7.4°.

[0093] The rotor may comprise five packets in one embodiment.

[0094] The rotor mass packets may all be angularly offset in the same direction around the axis of rotation of the rotor. Alternatively, the rotor mass packets may be angularly offset successively in one direction then in the other, being arranged in a V shape. As a further variant, the rotor mass packets may be angularly offset successively in one direction then in the other, being arranged in a chevron or W shape.

[0095] Machine The invention also relates to a rotating electrical machine comprising a rotor as defined above. The machine may also comprise a stator.

[0096] The machine can be used as a motor or as a generator. The machine can be reluctance. It can be a synchronous motor or alternatively a synchronous generator.

[0097] The maximum rotation speed of the machine may be high, for example, greater than 10,000 rpm, better still greater than 12,000 rpm, for example, in the order of 17,000 rpm to 18,000 rpm, or even 20,000 rpm or 24,000 rpm or 25,000 rpm. The maximum rotation speed of the machine may be less than 100,000 rpm, or even 60,000 rpm, or even less than 40,000 rpm, better still less than 30,000 rpm.

[0098] The invention may be particularly suitable for high-power machines.

[0099] The machine has a stator. The stator has teeth defining notches between them. The notches can be open, particularly towards the air gap, or on the contrary closed on the air gap side.

[0100] The stator may comprise electrical conductors, at least some of the electrical conductors, or a majority of the electrical conductors, being U-shaped or I-shaped. Alternatively, the electrical conductors may comprise round wire.

[0101] The stator can be connected in star or delta.

[0102] The machine may have a number of poles, for example, between 2 and 48, better between 4 and 24, or even between 6 and 12, being for example 6 or 8.

[0103] The invention also relates to a method of manufacturing a rotor of a rotating electrical machine as defined above.

[0104] The method may comprise the step of longitudinally introducing, along the axis of rotation of the rotor, at least one permanent magnet into the housing.

[0105] In the case where the rotor mass comprises several stacks of laminations stacked on top of each other, the method may first comprise the step of longitudinally introducing at least one permanent magnet into the housing of each stack of laminations, then the step of stacking the stacks of laminations on top of each other, with the permanent magnets in the housings.

[0106] The invention also relates to an electric motor vehicle comprising such a rotating electric machine.

[0107] Brief description of the drawings

[0108] [Fig 1] Figure 1 is a schematic and partial cross-section of a rotating electrical machine according to the invention,

[0109] [Fig 2] Figure 2 is a detailed view of a magnetic pole of the rotor of Figure 1,

[0110] [Fig 3] Figure 3 is a view similar to Figures 1 and 2 of a magnetic pole of the rotor of Figure 1,

[0111] [Fig 4] Figure 4 is a detailed view of a central notch of the rotor of Figure 1,

[0112] [Fig 5] Figure 5 is a detailed view of one of the side notches of the rotor of Figure 1.

[0113] Detailed description

[0114] Figure 1 illustrates a magnetic pole 10 of a rotor 1 according to the invention. The rotor 1 of a rotating electrical machine comprises a rotor mass, the rotor mass comprising a plurality of housings 2 for receiving permanent magnets 3, as illustrated in Figure 2. The permanent magnets 3 define the magnetic poles 10 of the rotor 1, the magnetic poles 10 each extending along a polar axis X. The rotor 1 comprises in this example eight magnetic poles 10. The angular extent A of a magnetic pole 10 is here 45°.

[0115] The rotor mass is composed of a plurality of packets arranged consecutively along an axis of rotation of the rotor 1, two consecutive packets being angularly offset around the axis of rotation of the rotor by a non-zero elementary angle 5. The housings 2 of each magnetic pole 10 are arranged in at least a first 4 and a second row 5 of housings 2, the second row 5 of housings 2 being closest to the surface 7 of the rotor mass.

[0116] The housings 2 of the first row 4 are arranged in a U shape. The housings 2 of the second row 5 are arranged in a V shape. The angular opening q of the second V-shaped row 5 is approximately 14.42°.

[0117] The rotor mass has on its surface 7 for a given magnetic pole 10 a single central notch 6 crossed by the polar axis X of the corresponding magnetic pole 10. The single central notch 6 is cut on the surface of the rotor mass between the ends 5a and 5b of the second row 5. The single central notch 6 is symmetrical with respect to the polar axis X of the corresponding magnetic pole 10. The polar axis X crosses the central notch 6 in its middle.

[0118] As illustrated in Figure 3, the rotor mass also has on its surface 7 for a given magnetic pole 10 two lateral notches 11 and 12 each spaced apart by an angle [3 equal to the polar axis X of the corresponding magnetic pole 10. The two lateral notches 11 and 12 are spaced apart from the polar axis X of the corresponding magnetic pole 10 by an angle [3 of approximately 14.3°. To measure the angular position of the lateral notch 11, respectively 12, the angular position of the middle of the lateral notch 11, respectively 12 is considered.

[0119] The central notch 6 has an angular opening a greater than the angular opening y of a lateral notch 11, 12, the angular opening a of the central notch being in particular approximately 6.64°. Each lateral notch 11, respectively 12, has an angular opening y of the order of 3.4°. A ratio a / y between the angular opening a of the central notch and the angular opening y of one of the two lateral notches may in particular be approximately 1.95.

[0120] The circumferential length Li of a lateral notch 11, respectively 12, is less than the circumferential length G of the spacing between the first row 4 and the second row 5 at the surface 7 of the rotor mass. Their ratio is approximately 0.6. The circumferential length G of the spacing between the rows of housings at the surface 7 of the rotor mass can be approximately 4.92 mm. The angular opening y of a lateral notch 11, respectively 12, is less than the angular opening g of the spacing between the first row 4 and the second row 5 at the surface 7 of the rotor mass. Their ratio can be approximately 0.6.

[0121] The angular opening a of the central notch 6 is greater than the angular opening g of the spacing between the first 4 and second rows 5 of housings 2 at the surface 7 of the rotor mass. The angular opening g of the spacing between the two rows of housings 4 and 5 is approximately 5.32°. The spacing between the two rows of housings 4 and 5 corresponds to the angular opening separating the tangent of the second row 5 in the shape of a V and the tangent of the first row 4 in the shape of a U, these tangents passing through the axis of rotation X and the rounded edges of the material bridges.

[0122] The central notch 6 has a circumferential length L greater than a circumferential length Li of one of the two lateral notches 11, 12, in particular a circumferential length L of between 6 mm and 6.3 mm. The circumferential length of the central notch 6 is in particular of the order of 6.13 mm.

[0123] A ratio between a circumferential length L of the central notch and a circumferential length Li of one of the two lateral notches 11, 12 may in particular be approximately 1.95.

[0124] The circumferential length L of the central notch may be less than the circumferential length K of the second row, in particular of the second V-shaped row, on the surface of the rotor mass. Their ratio may in particular be approximately 0.46.

[0125] The angular opening q of the second V-shaped row, measured at the surface of the rotor mass, is 14.42°. The angular opening q is measured between the tangents at the inner lateral ends of the second row 5.

[0126] A circumferential length K of the second V-shaped row, measured at the surface of the rotor mass, is 13.2 mm.

[0127] The rotor comprises material bridges 15 between end housings 2 of the first row 4 and of the second row 5 and the surface 7 of the rotor mass, the material bridges 15 having, as illustrated in FIG. 4, an angular opening in particular between 3° and 4°. The circumferential length of the material bridges 15 may be between 2 mm and 4 mm, better between 2.5 mm and 3.5 mm, being for example of the order of 3.1 mm.

[0128] The central notch 6 has an angular opening a greater than the maximum width p of the material bridges 15. The central notch 6 may have a circumferential length L greater than the angular opening j of the material bridges 15 between the housings.

[0129] The lateral notches 11 and 12 have an angular opening y less than the angular opening ] of the material bridges. The lateral notches 11 and 12 have a circumferential length Li less than the circumferential length of the material bridges 15.

[0130] A ratio between the sum of the angular openings of the central notch a and of the lateral notches y on the sum of the angular openings j of the material bridges 15 is between 0.5 and 1.5, better between 0.8 and 1.2.

[0131] A ratio j / a between the angular opening j of the material bridges 15 and the angular opening a of the central notch 6 is for example of the order of 0.5.

[0132] The central notch 6 may have a bottom 8 of the notch 6, the bottom 8 of the central notch 6 extending circumferentially, in particular along an arc of a circle. The central notch 6 also has two lateral sides 8a and 8b arranged on either side of the bottom 8 of the central notch 6.

[0133] The central notch 6 has a depth E, as illustrated in Figure 4. The depth E can be defined as the difference between the radius of the rotor mass independent of the central notch 6 and the radius of the rotor mass measured in the bottom 8 of the central notch 6. The depth E of the central notch can be for example approximately 0.35 mm.

[0134] As illustrated in Figure 4, the lateral sides 8a and 8b of the central notch 6 have an inclination different from 90° with respect to the surface 7 of the rotor mass, in particular with the normal to it. The inclination angle h is approximately 43°.

[0135] The junction between the bottom 8 of the central notch 6 and the lateral sides 8a and 8b on the one hand, and on the other hand between the lateral sides 8a and 8b and the surface 7 of the rotor mass can be made with a curvature. In an embodiment illustrated in Figure 4, each lateral side has two curvatures Ri and R2, respectively in connection with the bottom of the central notch and in connection with the surface of the rotor mass. The two curves can be substantially identical, with an identical radius of curvature. The radii of curvature Ri and R2 are approximately 0.3 mm.

[0136] The rotor mass comprises on the surface, for a given magnetic pole 10, only two lateral notches 11 and 12, shown in figures 1 to 3, each lateral notch being cut on the surface 7 of the rotor mass between one end 4a, respectively 4b, of the first row 4 of housings 2 and one end 5a, respectively 5b, of the second row 5 of housings.

[0137] The two lateral notches 11 and 12 are each arranged on either side of the polar axis of the corresponding magnetic pole 10. In this example, they are symmetrical to each other with respect to the polar axis X of the corresponding magnetic pole.

[0138] As illustrated in Figure 5, the rotor 1 has a single lateral notch 11 between one end 4a of the first row 4 of housings 2 and one end 5a of the second row 5 of housings 2, on the same side of the polar axis X of the corresponding magnetic pole 10.

[0139] The two lateral notches 11 and 12 are of similar shape to each other. Each lateral notch 11, respectively 12, has a bottom 13 of the lateral notch 11. The bottom 13 of the lateral notch 11 extends circumferentially, in particular along an arc of a circle. The lateral notch 11 also has two lateral sides 13a and 13b arranged on either side of the bottom 13 of the lateral notch 11.

[0140] The lateral notches have a depth E1, as illustrated in Figure 5. The depth E1 can be defined as the difference between the radius of the rotor mass independently of the lateral notch 11 and the radius of the rotor mass measured in the bottom 13 of the corresponding lateral notch 11. The depth E1 of a lateral notch 11, respectively 12, is approximately 0.275 mm. The lateral sides 13a and 13b have a different inclination of 90° with respect to the surface of the rotor mass, in particular with the normal thereto. The inclination angle h is approximately 25°, as illustrated in Figure 5.

[0141] The junction between the bottom 13 of the lateral notch 11 and the lateral sides 13a and 13b on the one hand, and on the other hand between the lateral sides and the surface of the rotor mass can be made with a curvature. In one embodiment, each lateral side has two curvatures R3 and R4, respectively in connection with the bottom of the lateral notch and in connection with the surface of the rotor mass. The two curves R3 and R4 can be substantially identical, with an identical radius of curvature. The radius of curvature can be for example approximately 0.3 mm. Alternatively, the radii of the curvatures can be different.

Claims

Claims 1. Rotor (1) of a rotating electrical machine, comprising a rotor mass, the rotor mass comprising a plurality of housings (2) for receiving one or more permanent magnets (3) defining magnetic poles (10) of the rotor (1), the magnetic poles (10) each extending along a polar axis (X), the housings (2) of a magnetic pole (10) being arranged in at least a first (4) and a second row (5) of housings (2), the second row (5) of housings (2) being closest to the surface (7) of the rotor mass, the rotor mass comprising on the surface for at least one given magnetic pole (10) a single central notch (6) crossed by the polar axis (X) of the corresponding magnetic pole (10), the single central notch (6) being cut on the surface (7) of the rotor mass between the ends (5a, 5b) of the second row, the rotor mass comprising on the surface for at least minus one magnetic pole (10) given two lateral notches (11, 12),in particular only two lateral notches (11, 12), each lateral notch being cut on the surface of the rotor mass between one end of the first row (4) of housings (2) and one end of the second row (5) of housings (2)., 2. Rotor (1) according to claim 1, the single central notch (6) having a depth (E) of between 0.1 mm and 0.5 mm.

3. Rotor (1) according to claim 1 or claim 2, the single central notch (6) being symmetrical with respect to the polar axis (X) of the corresponding magnetic pole (10).

4. Rotor according to any one of the preceding claims, the two lateral notches (11, 12) each being spaced apart by an equal angle ([3) relative to the polar axis (X) of the corresponding magnetic pole (10).

5. Rotor according to any one of the preceding claims, at least one lateral notch (11, 12), or even both lateral notches (11, 12), being spaced from the polar axis (X) of the corresponding magnetic pole (10) by an angle ([3) of between 10° and 20°, or even between 12° and 18°, or even between 13° and 16°.

6. Rotor according to any one of the preceding claims, the central notch (6) having an angular opening (a) greater than the angular opening (y) of one of the two lateral notches (11, 12), the angular opening (a) of the central notch (6) being in particular between 3° and 10°, in particular between 5° and 8°, or even between 6° and 7°.

7. Rotor according to any one of the preceding claims, the central notch (6) having a circumferential length (L) greater than a circumferential length (Li) of one of the two lateral notches (11, 12), in particular a circumferential length (L) of between 5 mm and 8 mm, or even between 5.5 mm and 7.5 mm, better still between 6 mm and 6.3 mm.

8. Rotor according to any one of the preceding claims, at least one lateral notch (11, 12), or even each lateral notch (11, 12), having an angular opening y of between 2° and 5°, better still between 3° and 4°.

9. Rotor according to any one of the preceding claims, the rotor (1) comprising material bridges (15) between end housings (2) of the first row (4) and / or of the second row (5) and the surface of the rotor mass (7), the material bridges (15) having an angular opening j in particular between 1° and 8°, preferably between 2° and 6°, better still between 3° and 4°.

10. Rotor according to the preceding claim, a ratio (j / a) between the angular opening of the material bridges (15) and the angular opening a of the central notch (6) being between 0.1 and 1, or even between 0.2 and 0.9, better between 0.3 and 0.8, for example of the order of 0.

5.

11. Rotor according to any one of the preceding claims, the housings (2) of the first row (4) being arranged in a U.

12. Rotor according to any one of the preceding claims, the housings (2) of the second row (5) being arranged in a V.

13. Rotor according to any one of the preceding claims, the rotor (1) comprising 6 or 8 magnetic poles (10).

14. Rotor according to any one of the preceding claims, the rotor mass being composed of a plurality of packets arranged consecutively along an axis of rotation of the rotor, two consecutive packets being angularly offset around the axis of rotation of the rotor by a non-zero elementary angle 5.

15. Rotating electrical machine comprising a rotor (1) according to any one of the preceding claims.

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