ROTOR, MANUFACTURING METHOD, SYNCHRONOUS ELECTRIC MACHINE, AND VEHICLE - Patent application

Abstract

A rotor (1) is provided having N poles, N being an even integer, the rotor (1) not comprising permanent magnets containing rare earth elements, the rotor (1) comprising a cylindrical body (2) and a filler (16). The cylindrical body (2) extends along a body axis (X) and defines N adjacent angular sectors (4, 6) in a plane perpendicular to the body axis (X). Each angular sector (4, 6) defines a cylindrical cavity (8, 12, 14, 8', 12', 14') having a curved cross section, the concave surfaces (18, 20, 22, 18', 20', 22') of the cylindrical cavities (8, 12, 14, 8', 12', 14') being oriented in a direction opposite to the body axis (X). The filling material (16) at least partially fills the cylindrical cavities (8, 12, 14, 8', 12', 14') and comprises or consists of a polymer matrix. At least one first angular sector (6) defines a cylindrical cavity (8', 12', 14') having a first geometric shape (type A) and at least one second angular sector (4) defines a cylindrical cavity (8, 12, 14) having a second geometric shape (type B) different from the first geometric shape. The first angular sectors (6) are angularly alternating with the second angular sectors (4).

Description

[Technical field]

[0001] The present invention relates to a rotor including a cylindrical body and a filler.

[0002] The invention also relates to a method for manufacturing a rotor or a rotor module.

[0003] The invention also relates to a synchronous electric machine comprising a rotor as defined above, or a rotor obtained using the manufacturing method as defined above.

[0004] The invention also relates to an electric or hybrid vehicle comprising a synchronous electric machine as described above. [Background technology]

[0005] Reluctance motors are a type of motor whose technology dates back roughly a century, with the "Kostko" polyphase synchronous reaction motor dating back to 1923. Reluctance motors are characterized by a rotor structure that is magnetically anisotropic with no windings.

[0006] Reluctance motors are machines with technical limitations that make them unsuitable for large-scale use.

[0007] One technical limitation is the relatively low power factor due to the phase displacement angle between voltage and current: while an "active" quantity of current can generate useful mechanical power, another quantity of current that is 90° out of phase with the voltage is "reactive", and so although it can excite the rotor, it has no beneficial effect.

[0008] Another technical limitation is the torque ripple (vibration) generated by the rotor air chamber, resulting in noise and resonance.

[0009] US Patent Publication No. 2015 / 0372546, US Patent Publication No. 2019 / 207490, and WO 2017 / 021078 illustrate examples of rotors for reluctance motors according to the prior art. Summary of the Invention

[0010] After a long and intensive research and development effort, the Applicant has developed a rotor, a manufacturing method, a synchronous electric machine and a vehicle capable of adequately addressing the limitations, drawbacks and existing challenges, with the firm belief that reluctance motors will attract increasing interest over the coming years (e.g., but not exclusively, in the field of electric vehicles).

[0011] Indeed, the Applicant has surprisingly discovered that by introducing an asymmetry into the rotor cavity, it is possible to reduce the torque ripple (and therefore noise and resonance) of the rotor and to increase the average value of the torque of a synchronous electric machine comprising said rotor.

[0012] The present invention therefore relates to a rotor comprising a tubular body and a filler having the characteristics defined in the appended claims.

[0013] The invention also relates to a method for manufacturing a rotor or a rotor module having the features defined in the accompanying claims.

[0014] The invention also relates to a synchronous electric machine comprising a rotor as defined above, or a rotor obtained using the manufacturing method as defined above, having the characteristics defined in the appended claims.

[0015] The invention also relates to an electric or hybrid vehicle equipped with a synchronous electric machine as defined in the appended claims. [Brief description of the drawings]

[0016] Preferred embodiments of the invention are described below by way of non-limiting examples with reference to the drawings, in which:

[0017] [Figure 1] 1 shows a plan view of a rotor according to a possible embodiment of the invention; [Diagram 2]1 shows a plan view of a cylinder according to a possible embodiment of the invention. [Diagram 3] 4 shows an enlarged detail of a first angular sector according to a possible embodiment; [Figure 4] 4 shows an enlarged detail of the second angular sector according to a possible embodiment; [Diagram 5] 3 shows an enlarged detail of Zone V highlighted in FIG. 2 according to a possible embodiment. [Figure 6] 3 shows an expanded detail of Zone VI highlighted in FIG. 2 according to a possible embodiment. [Figure 7A] 1 shows a perspective view of a tubular body according to a possible embodiment. [Figure 7B] 1 shows a perspective view of a modular element according to a possible embodiment. [Figure 8] 4 shows rotor torque / position diagrams comparing torque ripple and average torque for an asymmetric rotor according to the present invention and a rotor with a symmetric axial cavity according to the prior art; [Figure 9] 1 shows a perspective view of a synchronous electric machine according to the invention; [Figure 10] 1 shows a longitudinal section through a synchronous electric machine according to the invention; [Figure 11] 1 shows a cross-sectional view of a synchronous electric machine according to the invention; [Figure 12] 3 shows an enlarged detail of zone V highlighted in FIG. 2 according to a further possible embodiment of the first angular sector; [Figure 13] 3 shows an enlarged detail of zone VI highlighted in FIG. 2 according to a further possible embodiment of the second angular sector. [Figure 14] 13 shows a plan view of a cylinder according to another possible embodiment of the present invention. [Figure 15] 15 shows an enlarged detail of a first angular sector according to the embodiment of FIG. 14. [Figure 16] 15 shows an enlarged detail of a second angular sector according to the embodiment of FIG. 14. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] With reference to the accompanying drawings, reference numeral 1 generally indicates a rotor 1 having N poles without permanent magnets containing rare earth elements (e.g. without neodymium and / or without samarium), the rotor 1 comprising a cylindrical body 2 and a filler material 16.

[0019] N is an even number, and is preferably 2, 4, 6, 8, 10, or 12, more preferably N=2, N=4, or N=6. More preferably, N=4 or N=6.

[0020] The cylinder 2 extends along a body axis X (or along the height of the cylinder) between a first cylinder base 60 and an opposite cylinder base 62. In a plane perpendicular to the body axis X, said cylinder 2 defines N adjacent angular sectors 4, 6 (where the number of angular sectors is equal to the number N of poles). Preferably, the cylinder 2 is delimited or circumscribed by an outer cylindrical surface 34.

[0021] In this specification, the terms "axial", "radial", "angular", "circumferential", "proximal", "distal" and "orthogonal" are always used with respect to the body axis X, unless otherwise specified.

[0022] The tubular body 2 is preferably traversed (from one end side to the other) by an axial bore 42. Preferably, the axial bore 42 has a substantially circular orthogonal cross section, which is suitably shaped so that it can, optionally, be connected to a transmission shaft 44 (as shown, for example, in FIG. 9). Preferably, said connection between the tubular body 2 and the transmission shaft 44 is a prismatic (or anti-rotational) connection or coupling, such that the tubular body 2 and the transmission shaft 44 are rotationally integral.

[0023] The cylindrical body 2 preferably has an outer diameter (or diameter of the base of the cylindrical body) comprised between 50 mm and 200 mm, more preferably between 60 mm and 150 mm, even more preferably between 80 mm and 100 mm, and even more preferably between 85 mm and 95 mm.

[0024] If the axial hole 42 is present, the cylindrical body 2 preferably has an inner diameter comprised between 20 mm and 150 mm, preferably between 25 mm and 100 mm, even more preferably between 30 mm and 50 mm.

[0025] The cylinder 2 is preferably made of a metal alloy, preferably an iron alloy, more preferably an iron-silicon alloy. Even more preferably, said alloy is an M400-50A or M330-35 alloy. The abbreviations M400 or M330-35A refer to the standard EN 10106:2015, in which the first three digits indicate the value in tenths and hundredths of the iron loss per kilogram of material under standard frequency and magnetic induction conditions, while the last two digits of each abbreviation indicate the layer thickness of said alloy, expressed in hundredths of millimeters.

[0026] It is noted that this standard, like all standards referred to herein, is considered to be the version in effect as of the priority date of this patent application.

[0027] Preferably, the tubular body 2 consists of a number of cylinder plates that are axially stacked and joined together, for example by form-fit and / or pressure-fit connections, by welding and / or by cohesive forces exerted by the filler material 16. The above-mentioned stack thickness refers to the thickness of the cylinder plates formed by the metal alloy.

[0028] The cylinder plates are preferably axially overlapped and joined such that the polarity (positive and negative) of each of the N poles of a cylinder plate axially corresponds to the polarity (positive and negative) of the N poles of an adjacent cylinder plate, in other words the polarity of a cylinder plate is out of phase (e.g. 90°) with respect to the polarity of an adjacent cylinder plate.

[0029] Preferably, each cylinder plate has a thickness (in the axial direction) comprised between 0.1 mm and 1 mm, preferably between 0.2 mm and 0.8 mm, more preferably between 0.3 mm and 0.6 mm, even more preferably between 0.35 mm and 0.5 mm.

[0030] As an example, the cylindrical body 2 is made up of a number of cylinder plates comprised between 10 and 500, preferably between 20 and 400, and even more preferably between 50 and 300.

[0031] The angular sectors are separated from one another by one or more separation planes P(i), said at least one separation plane P(i) including the body axis X.

[0032] 2 shows a rotor with two separation planes P1, P2 separating four angular sectors 4, 6, said separation planes P1, P2 here intersecting each other along the body axis X. The separation planes P1, P2 are preferably arranged at an angle of 90° to each other, so that all said angular sectors 4, 6 have the same angular development.

[0033] As a further example, Figure 14 shows a rotor with three separation planes P1, P2, P3 separating six angular sectors 4, 6, said separation planes P1, P2, P3 here intersecting each other along the body axis X. The separation planes P1, P2, P3 are preferably arranged at an angle of 60° to each other, so that all said angular sectors 4, 6 have the same angular development.

[0034] For a rotor with N poles, the separation planes P(i) are preferably arranged at angles to one another such that the angular sectors all have the same angular expansion.

[0035] Preferably, each of said N poles extends axially along the body axis X from the first cylinder base 60 to the second cylinder base 62 of the cylinder body 2 .

[0036] Each angular sector 4, 6 defines an axial cavity 8, 12, 14, 8', 12', 14', preferably a cylindrical cavity 8, 12, 14, 8', 12', 14' with a curved or inwardly curved cross section. The concave surface 18, 20, 22, 18', 20', 22' of said axial or cylindrical cavity 8, 12, 14, 8', 12', 14' is oriented in the opposite direction to the body axis X.

[0037] In this description, the expression "cylindrical" means that the aforementioned cavity is bounded by a cylindrical surface and therefore has a constant cross section. The same meaning shall apply to the recess 54 described below.

[0038] Preferably, the axial or cylindrical cavities 8, 12, 14, 8', 12', 14' are also bounded by convex surfaces 28, 30, 32, 28', 30', 32', which are located in front of the concave surfaces 18, 20, 22, 18', 20', 22' and face the body axis X.

[0039] Preferably, the axial or cylindrical cavities 8, 12, 14, 8', 12', 14' are tapered radially outwards.

[0040] Preferably, at least one of the cylindrical cavities 8, 12, 14, 8', 12', 14' is crossed by a radial midplane M.

[0041] Preferably, the separation plane P(i) divides an angular sector without intersecting the axial or tubular cavity and accommodates only the rotor and the majority of the axial bore 42 (if provided).

[0042] The filling material 16 at least partially (and preferably completely or nearly completely) occupies (or fills) said axial or tubular cavities 8, 12, 14, 8', 12', 14'.

[0043] According to a first embodiment, the filler material 16 comprises or consists of a polymer matrix incorporating one or more magnetizable or magnetized fillers.

[0044] According to a second embodiment, the filler 16 comprises or consists of a polymer matrix, wherein said polymer matrix preferably does not comprise one or more magnetizable or magnetized fillers embedded within said polymer matrix.

[0045] The presence of the filler 16 within the axial or tubular cavities 8, 12, 14, 8', 12', 14', particularly in embodiments in which the polymer matrix incorporates one or more magnetizable or magnetized fillers, provides a significant benefit to the power factor of the synchronous electric machine, which is unexpectedly higher, all other things being equal, than a corresponding synchronous electric machine in which the axial or tubular cavities are empty and thus occupied by air.

[0046] This benefit exists despite the fact that the filler material forms weaker magnets than rare earth-containing permanent magnets, which is due to the filler material's ability to "re-phase" a synchronous electric machine, i.e., at least in part, to reduce the phase shift angle between the voltage and current.

[0047] Preferably, the amount of the one or more magnetizable fillers in the filler 16 is preferably comprised between 50 and 98% by weight, preferably between 60 and 96% by weight, more preferably between 65 and 95% by weight, even more preferably between 75 and 94% by weight of the total weight of the filler.

[0048] Preferably, the filler 16 is and / or a residual magnetic flux density or remanence (Br), determined according to DIN 60404-5, comprised between 150 mT and 450 mT, preferably between 180 mT and 380 mT, more preferably between 220 mT and 320 mT, even more preferably between 250 mT and 310 mT; and / or and / or a coercive field strength or coercive force (jHc), determined according to DIN EN 60404-5, comprised between 130 kA / m and 350 kA / m, preferably between 150 kA / m and 320 kA / m, more preferably between 170 kA / m and 280 kA / m, even more preferably between 190 kA / m and 250 kA / m; 10kJ / m 3 ~20kJ / m 3 , preferably 12 kJ / m 3 ~18.5kJ / m 3 , more preferably 13 kJ / m 3 ~16kJ / m 3 , and even more preferably 14 kJ / m 3 ~15.8kJ / m 3 The maximum energy product (BH max), determined in accordance with DIN EN 60404-5, is comprised between

[0049] The filler density 16, determined according to ISO 1183, is preferably 3000.00 kg / m 3 ~4000.00kg / m 3 , more preferably 3500.00 kg / m 3 ~3700.00kg / m 3 , and even more preferably 3550.00 kg / m 3 ~3650.00kg / m 3 is included between.

[0050] Preferably, the filler 16 has one or both of the following rheological properties: a shrinkage in the machine direction, measured according to ISO 294-4, between 0.2% and 2%, preferably between 0.6% and 1.5%, more preferably between 0.7% and 1%, and even more preferably equal to 0.8%; and / or A shrinkage transverse to the machine direction, measured according to ISO 294-4, comprised between 0.2% and 2%, preferably between 0.5% and 1%, more preferably between 0.45% and 0.8%, and even more preferably equal to 0.5%.

[0051] The polymer matrix of the filler 16 is preferably a thermoplastic or thermosetting matrix.

[0052] The thermoplastic polymer matrix is ​​preferably selected from the group comprising or alternatively consisting of polyamide (PA), polyamide 6 (PA6), polyamide 6.6 (PA6.6), polyamide 12 (PA12), polyphenylene sulfide (PPS), liquid crystal polymer (LCP). More preferably, said polymer matrix is ​​PA, PA6 or PPS, even more preferably, said polymer matrix is ​​PA6 or PPS.

[0053] The thermosetting polymer matrix preferably comprises or alternatively is selected from the group consisting of polyester resins, vinyl ester resins, phenolic resins, epoxy resins, more preferably polyester resins or epoxy resins.

[0054] The at least one magnetizable filler is preferably selected from magnetite, ferrite, and mixtures thereof, more preferably said magnetizable filler is ferrite.

[0055] The ferrite preferably comprises one or more metallic elements selected from the group including or alternatively consisting of strontium, barium, manganese, nickel, zinc, and mixtures thereof, and more preferably the ferrite comprises strontium as the metallic element or comprises only strontium.

[0056] Preferably, the polymer matrix is ​​PA6 or PPS and the magnetizable filler is a ferrite containing only strontium as the metallic element.

[0057] As a non-limiting example, said filler material 16 is a product sold by BARLOG Plastics GmbH, 51491 Overath, Germany, under the code "KEBABLEND / M 14 / 22 PA6".

[0058] At least one first angular sector 6 defines an axial or tubular cavity 8', 12', 14' having a first geometric shape (a type A geometric shape) and at least one second angular sector 4 defines an axial or tubular cavity 8, 12, 14 having a second geometric shape (a type B geometric shape) different from said first geometric shape, the first angular sectors 6 angularly alternating with said second angular sectors 4.

[0059] Thus, according to an innovative aspect of the invention, due to the geometric asymmetry of the rotor's axial or tubular cavities (and therefore the angular sectors) and the angular alternating arrangement of sectors with different geometric shapes, the rotor according to the invention makes it possible to reduce the torque ripple (and therefore the noise and resonances) and to increase the average value of the torque of a synchronous electric machine.

[0060] With particular reference to the graph shown in Figure 8, said graph shows torque values ​​as a function of angular position for the various rotors tested. Dashed line T AB represents the torque ripple of a possible embodiment of a rotor according to the invention (for example in an alternating arrangement of the geometric shape ABAB, as shown in Figures 1 and 2), Curve T with a torque of approximately 12 Nm at 0° A shows the torque ripple of the first rotor of the prior art where only the angular sector of type A (AAAA) is present, Curve T with a torque of approximately 9 Nm at 0° B shows the torque ripple of the second rotor of the prior art where only the angle sector of type B (BBBB) is present.

[0061] From FIG. 8 it can be seen that the rotor according to the invention has smaller ripples compared to the other two rotors tested, in particular being characterized by a smaller amplitude and a longer period at 1 Nm.

[0062] Similar tests have been performed on rotors having numbers of poles, N, different from 4. The results of these tests are comparable to the progression shown in FIG.

[0063] The one or more cylindrical cavities 8, 12, 14, 8', 12', 14' are preferably separated from the outer cylindrical surface 34 by one or more partitions 56, each preferably having a variable thickness in the circumferential direction of the cylinder 2 and a minimum thickness point 58.

[0064] More preferably, the partition 56 is disposed between the radially outer ends of the cylindrical cavities 8, 12, 14, 8', 12', 14' and the outer cylindrical surface 34.

[0065] The minimum thickness point 58 is preferably determined by a radially outward taper of the axial or cylindrical cavity(ies) 8, 12, 14, 8', 12', 14'. By way of example, the axial or cylindrical cavity(ies) 8, 12, 14, 8', 12', 14' terminates in a substantially rounded end (with the cavity oriented toward the body axis X) that defines the minimum thickness point 58 at the outer cylindrical surface 34.

[0066] The variable thickness of the septum 56 is preferably present in all of the tubular cavities 8, 12, 14, 8', 12', 14' shown diagrammatically in Figures 5 and 6, although this feature is less evident in the distal axial cavities or tubular cavities 14, 14'.

[0067] The radial plane R includes the body axis X and the minimum thickness point 58 of the bulkhead 56. The radial plane R forms a predetermined angle α, β with the central plane M mentioned above.

[0068] According to this embodiment, at least one cylindrical cavity 8', 12', 14' bounded by a first angular sector 6 is preferably characterized by a first angle α. At least a corresponding cylindrical cavity 8, 12, 14 bounded by a second angular sector 4 is preferably characterized by a second angle β different from said first angle α.

[0069] The expression "corresponding" tubular cavities is understood to mean that the angles α, β must be taken into account between tubular cavities having similar radial arrangements and shapes in the first angular sector 6 and the second angular sector 4, in particular comparing the angles α, β between similar proximal axial cavities or tubular cavities 8, 8', intermediate axial cavities or tubular cavities 12, 12', and / or distal axial cavities or tubular cavities 14, 14', as shown, for example, diagrammatically in Figures 5 and 6.

[0070] According to an embodiment, the difference between the aforementioned angles α, β preferably determines the first geometrical shape (type A) or the second geometrical shape (type B) of the axial or tubular cavity and of the respective sectors.

[0071] Preferably, each axial or tubular cavity 8, 12, 14, 8', 12', 14' encloses an internal volume, is bounded by an outer periphery and has a specific radial arrangement within its angular sector 4, 6, whereby said internal volume, said outer periphery and said specific radial arrangement determine the geometric shape (type A or type B) of the axial or tubular cavity and thus of the respective sector. Thus, the axial or tubular cavity 8', 12', 14' bounded by a first angular sector 6 has an internal volume, a shape and / or length of the outer periphery and / or a specific radial arrangement different from those of the axial or tubular cavity 8, 12, 14 bounded by a second angular sector 4.

[0072] More preferably, the axial or tubular cavities 8, 12, 14, 8', 12', 14' include a proximal axial or tubular cavity 8, 8', at least one intermediate axial or tubular cavity 12, 12' (i.e., only one or more intermediate axial or tubular cavities), and a distal axial or tubular cavity 14, 14' radially spaced from the body axis X.

[0073] In each sector 4, 6, the proximal axial or tubular cavity 8, 8' and the at least one intermediate axial or tubular cavity 12, 12' preferably have mirror symmetry with respect to a radial bridge 24, 26 that divides said proximal axial or tubular cavity 8, 8' and said at least one intermediate axial or tubular cavity 12, 12' at the centre.

[0074] The presence of the radial bridges 24, 26 is an important feature when the internal volume of the axial or tubular cavities is large. More specifically, since each cavity constitutes a structural weakening of the rotor, the presence of at least one radial bridge 24, 26 ensures the structural integrity of the rotating rotor despite the large centrifugal forces acting on said rotor.

[0075] According to another embodiment (not shown): The proximal axial or tubular cavity 8, 8' and at least one intermediate axial or tubular cavity 12, 12' do not have a radial bridge or Each sector 4, 6 comprises one or more radial bridges 24, 26 dividing or passing through the proximal axial or tubular cavity 8, 8', at least one intermediate axial or tubular cavity 12, 12', and / or the distal axial or tubular cavity 14, 14', preferably said one or more radial bridges 24, 26 dividing said axial or tubular cavities asymmetrically.

[0076] Preferably, each radial bridge 24, 26 has an average thickness (perpendicular to the radial direction) comprised between 0.1 mm and 2 mm, preferably between 0.2 mm and 1 mm, even more preferably between 0.3 mm and 0.7 mm.

[0077] Preferably, the axial or tubular cavities 8', 12', 14' bounded by the first angular sector 6 have the following different properties compared to the axial or tubular cavities 8, 12, 14 bounded by the second angular sector 4: (i) the radial distance D1, D2 of the proximal axial or tubular cavity 8, 8' and / or at least one intermediate axial or tubular cavity 12, 12' from the body axis X; and / or (ii) the radial distances D3, D4 of the convex surfaces 28, 30, 32, 28', 30', 32' of said axial or tubular cavities 8, 12, 14, 8', 12', 14' to the outer cylindrical surface or circumference 34 of said rotor 1; and / or (iii) the length L1 and / or width L2 of the radial bridges 24, 26; and / or (iv) the radius of curvature C1, C2 of one or more of the concave surfaces 18, 20, 22, 18', 20', 22' or of parts of said concave surfaces; and / or (iv) the radius of curvature C3, C4 of one or more of the convex surfaces 28, 30, 32, 28', 30', 32' or of parts of said convex surfaces; and / or (iv) Optionally, the length, interleaving, and / or incidence of any straight sections T1, T2 located along one or more of the concave surfaces 18, 20, 22, 18', 20', 22'.

[0078] According to this embodiment, one or more of the characteristics (i) to (v), optionally (i) to (vi), determine the geometric shape (type A or B) of the axial or tubular cavity and of the respective sectors.

[0079] Preferably, the rotor 1 is bounded or surrounded by an outer cylindrical surface or circumference 34. This outer cylindrical surface 34 preferably comprises a number of cylindrical or axial recesses 54 extending from said cylindrical surface 34 towards the inside of the tubular body 2. Preferably, each axial or cylindrical recess 54 is bounded by a concave surface (preferably in the form of a circular or elliptical arc, preferably having a constant cross section along the body axis X) oriented in a direction opposite to the body axis X. See for example the embodiments of figures 14 to 16.

[0080] Preferably, each angular sector 4, 6 comprises at least one axial or cylindrical recess 54, more preferably a single axial or cylindrical recess 54, even more preferably a single axial or cylindrical recess 54 located approximately in the center of the angular sector 4, 6.

[0081] According to an embodiment, the filler material 16 at least partially occupies (or fills) (preferably completely or nearly completely) a plurality of axial or cylindrical recesses 54 .

[0082] According to another embodiment, the plurality of axial or cylindrical recesses 54 does not have a filler material 16 .

[0083] According to a preferred embodiment, the type A geometry is as shown in FIG. 3, 5, 12 or 15 and the type B geometry is as shown in FIG.

[0084] The invention also relates to a method for manufacturing a rotor 1 according to any one of the embodiments shown above, or a rotor module 36 having the same characteristics as said rotor 1.

[0085] In the present invention, the expression "rotor module" refers to a rotor segment that has a lower axial height than the rotor and is designed to be mechanically joined with one or more other rotor modules to give the rotor a predetermined axial length or height.

[0086] Naturally, the features mentioned for the rotor 1 are also valid for the rotor module, mutatis mutandis.

[0087] The above-mentioned manufacturing method includes: (I) a step of overlapping and joining a plurality of cylindrical plates to provide a modular element 36 or a tubular body 2, which defines, in a plane extending along and perpendicular to a body axis X, N adjacent angular sectors 4, 6, each angular sector 4, 6 defines an axial or tubular cavity 8, 12, 14, 8', 12', 14' with a curved cross section, in which the concave surfaces 18, 20, 22, 18', 20', 22' of said axial or tubular cavities 8, 12, 14, 8', 12', 14' are oriented in a direction opposite to the body axis X; (II) optionally preheating the module element 36 or the tubular body 2 of step (I) to a temperature comprised between 50° C. and 120° C., preferably between 60° C. and 100° C., and even more preferably between 70° C. and 90° C.; (III) at least partially (e.g. completely or substantially completely) filling the axial or tubular cavities 8, 12, 14, 8', 12', 14' of the cylinder 2 or modular element 36 of step (I) or (II) with a flowable precursor of said filler material 16 (e.g. a liquid, fluid precursor, or a precursor in the form of a flowable powder); (IV) solidifying said flowing precursor in the axial or tubular cavities 8, 12, 14, 8', 12', 14' of the cylinders 2 or module elements 36 obtained from step (III) so as to provide said rotor 1 or rotor module; (V) preferably, magnetizing the rotor 1 or rotor module obtained from step (IV).

[0088] Preferably, during the stacking step (I), the cylinder plates are stacked so as to align the axial or tubular cavities defined by each plate in such a way as to form an axial or tubular cavity of the cylindrical body.

[0089] Preferably, said filling step (III) subsequent to said step (I) or said step (II) comprises at least one moulding or injection moulding step.

[0090] Preferably, the fluid precursor of step (III) has a temperature comprised between 45°C and 350°C, preferably between 50°C and 100°C, in the case of a precursor of a thermosetting polymer matrix, or between 250°C and 300°C, in the case of a precursor of a thermoplastic polymer matrix.

[0091] Preferably, in the manufacturing process using a thermoplastic polymer matrix, the solidifying step (IV) following the filling step (III) comprises a step involving cooling to room temperature, said cooling being more preferably carried out in two stages: a first stage in the mould until the flowing precursor of step (III) is sufficiently solidified so as not to flow out of the axial or tubular cavity, and a second stage outside the mould until room temperature is reached.

[0092] Preferably, in the manufacturing process in which a thermosetting polymer matrix is ​​used, the solidifying step (IV) following the filling step (III) comprises heating to the crosslinking or thermosetting temperature of the thermosetting polymer matrix.

[0093] Preferably, following the solidifying step (IV), the method comprises a step (VI) of mechanically joining step (IV) or two or more rotor modules resulting from step (IV) so as to give said rotor 1 a predetermined axial length and height.

[0094] This embodiment may be useful when the rotor 1 has a long axial length and when there is a narrow and long axial or cylindrical cavity, in which case complete filling of said cavity may be difficult, even if the optional pre-heating step (II) is performed, since the precursor may solidify before filling the cavity in the desired way (e.g. completely or nearly completely).

[0095] Preferably, during the mechanical joining step (VI), two or more rotor modules are connected by a common transmission shaft 44. Preferably, during step (VI), said transmission shaft 44 is inserted at least partially (e.g. completely) inside the axial bores 42 of two or more axially adjacent rotor modules, preferably by means of a prismatic connection or coupling system.

[0096] Preferably, the magnetization step (V) is carried out following the solidification carried out in step (IV).

[0097] More preferably, when the method comprises a step (VI) of mechanically joining two or more rotor modules, the magnetizing step (V) is carried out after or before, preferably before, the mechanical joining step (VI).

[0098] The invention also relates to a synchronous electric machine 10 comprising a rotor 1 as described above or comprising a rotor 1 or a rotor module obtained using the manufacturing method as described above.

[0099] The electric machine 10 is understood to be synchronous since the magnetic field of the stator 40 rotates synchronously with the rotor 1 .

[0100] Preferably, said synchronous electric machine 10 is selected from a synchronous reluctance motor, a three-phase synchronous reluctance motor, a synchronous reluctance machine different from a three-phase motor (having more stator phases than three), a switched reluctance machine, a self-starting synchronous reluctance machine (wherein the rotor 1 defines a further axial or tubular cavity for inserting one or more squirrel cages). More preferably, said synchronous electric machine 10 is a synchronous reluctance motor.

[0101] The synchronous reluctance motor preferably comprises a stator 40 defining a stator compartment 38 within which the rotor 1 is housed for rotation about a rotation axis R1, which is preferably parallel to and more preferably coincident with the body axis X. The rotor 1 is preferably connected to a transmission shaft 44.

[0102] With reference to the embodiment according to FIGS. 9-11, the synchronous reluctance motor comprises a motor housing 46 which at least partially (eg completely) houses the stator 40 and the rotor 1 .

[0103] The motor housing 46 preferably has at least one housing flange 48 defining a through opening 50 in which a transmission shaft 46 which is rotationally locked to the rotor 1 is rotatably accommodated, the through opening 50 protruding from said housing flange 48.

[0104] The stator 40 is preferably made at least in part from the same material as the rotor, more preferably a metal alloy, even more preferably an iron alloy, and even more preferably a ferrosilicon alloy, for example M400-50A or M330-35A.

[0105] The transmission shaft 44 is preferably made from aluminum or a light aluminum alloy.

[0106] The motor housing 46 and the housing flange 48 are preferably made of a metal, preferably aluminum, a light aluminum alloy, or carbon steel, and more preferably aluminum or a light aluminum alloy (for its thermal conductivity).

[0107] The air gap 52 between the rotor and the stator is comprised between 0.1 mm and 0.8 mm, preferably between 0.2 mm and 0.6 mm, and even more preferably between 0.4 mm and 0.5 mm.

[0108] The angular speed of the rotor 1 of said synchronous electric machine 10 is preferably comprised between 500 rpm and 20,000 rpm, preferably between 700 rpm and 15,000 rpm, more preferably between 1,000 rpm and 10,000 rpm, even more preferably between 1,200 rpm and 1,800 rpm, for example between 1,300 rpm and 1,700 rpm.

[0109] Table 1 below shows example operating parameters for the synchronous electric machine 10.

[0110] [Table 1]

[0111] The invention also relates to an electric or hybrid vehicle comprising a synchronous electric machine 10 as described above.

[0112] According to innovative aspects, the rotor according to the invention makes it possible to obtain Pareto optimality in relation to the following parameters, compared to rotors of the prior art: (i) lower torque ripple, and (ii) Higher average torque values. In this manner, the rotor according to the present invention has a quieter operating performance and generates fewer resonances.

[0113] In fact, it has been calculated that compared to a conventional rotor without angular modification of the geometry (a rotor having only type A geometry or only type B geometry), the rotor according to the invention can achieve a torque ripple reduction of about 2 / 3, all other operating conditions being equal.

[0114] Advantageously, the presence of an "asymmetric" rotor makes it possible to double the number of independent parameters that can be varied to achieve the objectives of the present invention.

[0115] As an advantage, the rotor according to the invention does not have permanent magnets containing rare earth elements, making it less costly than rotors using permanent magnets containing this type of element, and furthermore, it is purposely isolated from possible future difficulties related to the supply of rare earth elements.

[0116] Advantageously, the rotor according to the present invention is designed to ensure high torque, saliency, power factor and efficiency.

[0117] Advantageously, the rotor according to the invention has an optimized flux barrier angle in the region of the axial or tubular cavity.

[0118] As an advantage, the zone of the cylinder in the region of the septum is designed to be a magnetically saturated zone and therefore has a magnetic behavior similar to that of air.

[0119] Advantageously, the angles α, β, and especially their difference, are one of the main factors that help reduce torque ripple.

[0120] In fact, without necessarily having to scientifically explain the phenomenon, the generation of torque in the air gap of a synchronous electric machine can be locally explained using the principle of reluctance minimization, where the magnetic flux lines crossing the area of ​​the synchronous electric machine will follow the path of least resistance, following the tendency of the physical system to reach a minimum energy state. The physical system will therefore generate forces aimed at reaching this minimum energy state. The reluctance of areas made of soft ferromagnetic materials is typically 100 to 10,000 less than air (this variation is due to nonlinear saturation effects). If, in the area of ​​the air gap, there is a recess in the stator originating from the bulkhead and a "pseudo-cavity" in the rotor, the magnetic flux lines will undergo a twisting relative to their straight path to pass inside the ferromagnetic area, with lower resistance despite a longer distance. This twisting action generates a local torque, which in the case of a symmetrical configuration is repeated n times along the circumference of the rotor, and therefore its effects are also additive. On the other hand, in the rotor according to the invention, as a result of the presence of asymmetry, the torques do not add up but even partially cancel each other out, which results in a beneficial effect on the overall torque ripple, which can be easily measured, for example as shown in the diagram of FIG.

[0121] As an advantage, the manufacturing method according to the invention also allows the quantitative filling of axial or tubular cavities with unfavourable geometrical proportions.

[0122] Advantageously, in a rotor according to the invention, the presence of multiple axial or cylindrical recesses can help increase the average torque and reduce torque ripple.

[0123] A person skilled in the art will be able to substitute or modify, as necessary, the features of the embodiments of the rotor, the manufacturing method, the synchronous electric machine and the vehicle described above, which embodiments should also be considered as falling within the scope of protection formally defined by the following claims.

[0124] It should also be pointed out that any embodiment may be practiced independently of the other embodiments described. [Explanation of symbols]

[0125] 1 rotor 2. Cylindrical body 4. Angular sectors, especially the second angular sector 6 Angular sectors, especially the first angular sector 8 Axial or tubular cavities, especially proximal axial or tubular cavities 8' Axial or tubular cavity, especially proximal axial or tubular cavity 10 Synchronous electric machine, preferably a synchronous reluctance motor 12 Axial or cylindrical cavity, in particular intermediate axial or cylindrical cavity 12' Axial or cylindrical cavity, in particular intermediate axial or cylindrical cavity 14 Axial or tubular cavities, especially distal axial or tubular cavities 14' Axial or tubular cavity, particularly a distal axial or tubular cavity 16 Filling material 18 Concave 18' concave 20 concave 20' concave 22 Concave 22' concave 24 Radial Bridge 26 Radial Bridge 28 Convex 28' convex 30 Convex 30' convex 32 Convex 32' convex 34 Outer circumference or outer cylindrical surface 36 Module Elements 38 Stator Compartment 40 Stator 42 Axial or cylindrical bore 44 Transmission shaft 46 Motor housing 48 Housing flange 50 Through opening 52 void 54 Axial recess or pseudo-cavity 56 Bulkhead (Barrier) 58 Minimum thickness bridge 60 First Cylinder or Module Base 62 Second Cylinder or Module Base α Angle between radial plane R and central plane M Β Angle between radial plane R and central plane M C1 Concave curvature radius C2 Concave curvature radius C3 Convex curvature radius C4 Convex curvature radius D1 Radial distance of proximal axial or tubular cavity from body axis D2 Radial distance of intermediate axial or cylindrical cavity from the body axis D3 Radial distance of the convex surface from the rotor periphery D4 Radial distance of the convex surface from the rotor periphery L1 Radial bridge length L2 Radial bridge width M center plane P1 separation plane P2 separation plane P3 separation plane R Radial plane T1 Straight line along the concave surface T2 Straight line along the concave surface X Body Axis

Claims

1. A rotor (1) having N poles, N being an even number, the rotor (1) not comprising permanent magnets containing rare earth elements, A cylindrical body (2) extending along a body axis (X) and defining, in a plane perpendicular to said body axis (X), N adjacent angular sectors (4, 6), each angular sector (4, 6) defining a cylindrical cavity (8, 12, 14, 8', 12', 14') having a curved cross section, the concave surfaces (18, 20, 22, 18', 20', 22') of said cylindrical cavities (8, 12, 14, 8', 12', 14') being oriented in a direction opposite to said body axis (X), Each of the N poles extends axially along the body axis (X) from a first cylinder base (60) of the tubular body (2) to a second cylinder base (62) opposite the first cylinder base (60), and the rotor (1) further comprises: a filling material (16) at least partially filling said cylindrical cavity (8, 12, 14, 8', 12', 14') and comprising or consisting of a polymer matrix, A rotor (1), in which at least one first angular sector (6) defines a cylindrical cavity (8', 12', 14') having a first geometric shape (type A) and at least one second angular sector (4) defines a cylindrical cavity (8, 12, 14) having a second geometric shape (type B) different from said first geometric shape, said first angular sectors (6) being angularly alternating with said second angular sectors (4).

2. 2. The rotor (1) according to claim 1, wherein the cylindrical body (2) is formed by a plurality of cylinder plates, the plurality of cylinder plates being overlapped and joined in the axial direction such that the polarity of each of the N poles of a cylinder plate axially corresponds to the polarity of the N poles of an adjacent cylinder plate.

3. 2. A rotor (1) according to claim 1, wherein at least one of the tubular cavities (8, 12, 14, 8', 12', 14') is intersected by a radial mid-plane (M), the tubular body (2) is surrounded by an outer cylindrical surface (34), and the tubular cavities (8, 12, 14, 8', 12', 14') are separated from the outer cylindrical surface (34) by a partition (56) having a variable thickness in the circumferential direction of the tubular body (2) and a minimum thickness point (58).

4. 4. A rotor (1) according to claim 3, wherein a radial plane (R) includes the body axis (X) and the minimum thickness point (58) of the bulkhead (56), the radial plane (R) forms an angle (α, β) with the central plane (M), at least one cylindrical cavity (8', 12', 14') bounded by the first angular sector (6) is characterized by a first angle (α) and at least one corresponding cylindrical cavity (8, 12, 14) bounded by the second angular sector (4) is characterized by a second angle (β) different from the first angle (α), the difference between the angles (α, β) determining the first geometrical shape (type A) or the second geometrical shape (type B) of the cylindrical cavity.

5. 2. A rotor (1) according to claim 1, wherein each cylindrical cavity (8, 12, 14, 8', 12', 14') encloses an internal volume, is bounded by an outer periphery and has a specific angular arrangement within an angular sector (4, 6), the cylindrical cavity (8', 12', 14') bounded by the first angular sector (6) having an internal volume, an outer periphery shape and / or length and a specific radial arrangement different from those of the cylindrical cavity (8, 12, 14) bounded by the second angular sector (4).

6. said tubular cavities (8, 12, 14, 8', 12', 14') comprising a proximal tubular cavity (8, 8'), at least one intermediate tubular cavity (12, 12'), and a distal tubular cavity (14, 14') radially spaced from said body axis (X), said proximal tubular cavity (8, 8') and said at least one intermediate tubular cavity (12, 12') having mirror symmetry with respect to a radial bridge (24, 26) that divides said proximal axial cavity (8, 8') and said at least one intermediate tubular cavity (12, 12') at their center; The cylindrical cavities (8', 12', 14') bounded by the first angular sector (6) have the following different properties compared to the cylindrical cavities (8, 12, 14) bounded by the second angular sector (4): (i) the radial distance (D1, D2) of said proximal axial cavity (8, 8') and said at least one intermediate tubular cavity (12, 12') from said body axis (X); (ii) the radial distance (D3, D4) of the convex surface (28, 30, 32, 28', 30', 32') of said tubular cavity (8, 12, 14, 8', 12', 14') to the outer cylindrical surface or circumference (34) of said rotor (1); (iii) the length (L1) and / or width (L2) of said radial bridges (24, 26); and (iv) the radius of curvature (C1, C2) of one or more concave surfaces (18, 20, 22, 18', 20', 22') or of a portion of said concave surface; (v) the radius of curvature (C3, C4) of one or more convex surfaces (28, 30, 32, 28', 30', 32') or of a portion of said convex surfaces; (vi) optionally, the length, interleaving, and / or extent of any straight sections (T1, T2) located along one or more of the concave surfaces (18, 20, 22, 18', 20', 22').

7. 2. A rotor (1) according to claim 1, wherein the first or type A geometry is as shown in Figure 3, 5, 12 or 15 and the second or type B geometry is as shown in Figure 4, 6, 13 or 16.

8. The filler (16) the residual flux density or residual magnetism (Br), determined according to DIN EN 60404-5, being comprised between 150 mT and 450 mT, a coercive field strength or coercive force (jHc), determined according to DIN EN 60404-5, comprised between 130 kA / m and 350 kA / m, and 10 kJ / m 3 2. The rotor (1) according to claim 1, having a maximum energy product (BH max), determined according to DIN EN 60404-5, comprised between 0.1 and 20 kJ / m3.

9. the polymer matrix is ​​a thermoplastic or thermosetting matrix; 2. The rotor (1) of claim 1, wherein the filler (16) comprises one or more magnetizable or magnetized fillers embedded in the polymer matrix, the magnetizable fillers being selected from magnetite, ferrite, and mixtures thereof.

10. 2. The rotor (1) according to claim 1, wherein the polymer matrix is ​​PA6 or PPS and the magnetizable filler is a ferrite containing only strontium as metallic element.

11. 10. A method for manufacturing a rotor (1) according to claim 1 or a rotor module having the same features as the rotor (1) according to claim 1, said method comprising the steps of: (I) a step of overlapping and joining a plurality of cylindrical plates to provide a modular element (36) or a cylindrical body (2) extending along a body axis (X) and defining, in a plane perpendicular to said body axis (X), N adjacent angular sectors (4, 6), each angular sector (4, 6) defining a cylindrical cavity (8, 12, 14, 8', 12', 14') having a curved cross section, the concave surfaces (18, 20, 22, 18', 20', 22') of said cylindrical cavities (8, 12, 14, 8', 12', 14') being oriented in a direction opposite to said body axis (X); (II) optionally preheating said modular element (36) or tubular body (2) of step (I) to a temperature comprised between 50°C and 120°C; (III) at least partially filling the cylindrical cavity (8, 12, 14, 8', 12', 14') of the cylindrical body (2) or of the modular element (36) of step (I) or (II) with a flowable precursor of a filler material (16); (IV) solidifying the fluid precursor within the cylindrical cavity (8, 12, 14, 8', 12', 14') of the cylinder (2) or module element (36) obtained from step (III) to provide the rotor (1) or rotor module; The method includes:

12. Following step (IV), the process further comprises:

12. The method according to claim 11, comprising a step (VI) of mechanically joining two or more rotor modules resulting from step (IV) or step (V) to give the rotor (1) a predetermined axial length and height.

13. A synchronous electric machine (10) comprising a rotor (1) according to claim 1 or a rotor (1) or a rotor module (36) obtained by the manufacturing method according to claim 11.

14. 14. The synchronous electric machine (10) of claim 13, wherein the synchronous electric machine (10) is a synchronous reluctance motor, the rotor (1) being rotatably housed about a rotation axis (R1) and connected to a transmission shaft (44).

15. An electric or hybrid vehicle comprising a synchronous electric machine (10) according to claim 13.

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