Motor with rotor and / or stator sleeve of polymer material

Abstract

The invention relates to a rotor for an electric motor, where the rotor comprises a rotor core and a rotor sleeve circumferentially surrounding the rotor core, where the rotor core comprises one or more magnets, where the rotor sleeve comprises plastic and fibers, where the fibers have a tensile strength greater than or equal to 4440 MPa. The invention also relates to a stator for an electric motor comprising a gap tube, where the gap tube comprises a plastic and fibers, where the fibers have a tensile strength greater than or equal to 4440 MPa and a dry fiber tensile modulus in the range of 200 GPa to 450 GPa. The rotor and stator may be used in an electric motor assembly, preferably for a vehicle. The air gap can be reduced using the gap tube and / or the rotor sleeve according to the invention. This results in improved overall motor efficiency and performance.

Description

Technical Field

[0001] The invention relates to a rotor for an electric motor comprising a rotor sleeve and a stator for an electric motor comprising a can. The rotor and the stator for an electric motor can be used in the automotive industry. Background Art

[0002] An electric motor typically comprises a moving rotor and a stator core. In a rotor comprising magnetized components (such as permanent magnets), the physical distance between the rotor and the electromagnetic components of the stator is called an air gap. An air gap is a basic requirement for the operation of a motor. The presence of an air gap allows the rotor to rotate freely under all conditions of use and prevents contact between the rotor and the stator. If the air gap is too small, the rotating rotor and stator will come into contact during operation, for example due to deflection, resulting in motor failure. However, the air gap needs to be as small as possible to maximize the strength of the magnetic circuit. Therefore, the wider the air gap, the lower the efficiency and performance of the motor.

[0003] Since the size of the air gap in an electric motor is inherently linked to motor performance, it is highly desirable to achieve as small an air gap as reliably as possible across all operating and manufacturing variables.

[0004] The electric motor may include a clearance tube and a rotor sleeve.

[0005] The rotor sleeve is an optional component of the rotor. The rotor can be composed of several components, such as permanent magnets, poles of conductive steel, and a yoke of the same material. For optimal motor performance, the magnets in the rotor must be physically constrained in a way that optimizes mechanical retention and electromagnetic field structure. In a common configuration, the rotor components are retained with a rotor sleeve made of non-electromagnetic material that maintains the rotor structural integrity under high centripetal forces.

[0006] The gap tube is an optional component of the stator. The motor usually contacts the oil or cooling fluid to the hot area (mainly the conductor in the stator). A challenge of circulating the oil or cooling fluid across the large area of ​​the stator assembly is to approach the electrical steel rotor rotating at high speed. This may cause significant fluid power losses on the rotor, and makes it more challenging to control the contact / residence time of the fluid at the surface of the hot conductor in the stator without some separation and sealing components. The gap tube can be used as this separation and sealing component.

[0007] DE102019207078 A1 discloses a can arranged between the rotor and the stator of an electric machine. The purpose of the can is to seal the rotor and the stator from each other and to reduce magnetic losses in the air gap between the rotor and the stator. The can is made of a composite material such as a thermosetting plastic.

[0008] WO 2011 / 099603 A1 discloses a canned electric motor, which includes a can made of a single-layer fiber-reinforced plastic, the single-layer fiber-reinforced plastic containing a resin selected from polyetheretherketone (PEEK), polyamide (PI) polyesteramideimide, polyhydantoin, isocyanurate-modified polyesterimide, polyamideimide, polyester and epoxy, which is reinforced with carbon fiber or glass fiber or aramid fiber. The purpose of the can is to separate the stator and the rotor.

[0009] EP2348614 A1 discloses a rotor comprising a peripheral active element and a binding band surrounding the peripheral active element. The binding band is in the form of a cylindrical sleeve and comprises polyetheretherketone (PEEK) reinforced with glass fibers, carbon fibers or polyparaphenylene terephthalamide fibers. The purpose of the binding band is to provide a good hold of the peripheral active element.

[0010] US Pat. No. 5,900,689 A discloses a binding for a winding head of an electric machine rotor, the binding comprising a plastic matrix in which a fiber material is embedded, the binding being formed by winding a fiber tape onto the winding head, wherein the plastic matrix is ​​a thermoplastic.

[0011] There is a need for an electric motor in which the air gap has been reduced and the efficiency and performance of the motor has been improved. Summary of the invention

[0012] In some electric motors, it is important to have a rotor sleeve and / or a gap tube. In such electric motors, the inventors of the present invention surprisingly found that the use of a gap tube and / or a rotor sleeve according to the present invention can reduce the air gap. This improves the overall motor efficiency and performance.

[0013] In particular, the inventors surprisingly found that the use of plastic gap tubes and / or rotor sleeves reinforced with fibers having a specific tensile strength and / or dry tensile modulus results in a reduced air gap. This is demonstrated in the Examples section below.

[0014] A rotor including a rotor sleeve as described herein further enables higher rotor speeds, higher rotor temperatures, improved reliability, increased manufacturing efficiency and safety, and / or improved manufacturing robustness, and improved recyclability.

[0015] The gap tube according to the present invention allows improved cooling performance, thereby producing higher continuous power density, torque and / or efficiency for a given rotor and stator configuration. In addition, during manufacturing trials of the rotor sleeve and gap tube described herein, it was found that the present invention can further improve manufacturing efficiency and productivity by consuming less material and energy, and / or improve the recyclability of materials.

[0016] According to a first aspect of the present invention, a rotor for an electric motor is provided, wherein the rotor comprises a rotor core and a rotor sleeve circumferentially surrounding the rotor core, wherein the rotor core comprises one or more magnets, wherein the rotor sleeve comprises plastic and fiber, wherein the fiber has a tensile strength greater than or equal to 4440 MPa.

[0017] According to a second aspect of the present invention, there is provided a method for producing a rotor comprising a rotor core and a rotor sleeve, the method comprising the following steps:

[0018] - providing a rotor core comprising one or more magnets;

[0019] - Providing a material comprising a plastic and fibers, wherein the fibers have a tensile strength greater than or equal to 4440 MPa;

[0020] - Winding the material around the rotor core such that the material is tensioned and forms a rotor sleeve circumferentially surrounding the rotor core.

[0021] According to a third aspect of the present invention, there is provided a stator for an electric motor, the stator comprising a gap tube, wherein the gap tube contains plastic and fiber, wherein the fiber has a tensile strength greater than or equal to 4440 MPa and a dry fiber tensile modulus in the range of 200 GPa to 450 GPa.

[0022] According to a fourth aspect of the present invention, there is provided a method for producing a stator comprising a lamination stack and a gap tube, the method comprising the following steps:

[0023] (i) providing a stator including a lamination stack;

[0024] (ii) providing an interstitial tube comprising a plastic and fibers, wherein the fibers have a tensile strength greater than or equal to 4440 MPa and a dry fiber tensile modulus in the range of 200 GPa to 450 GPa; and

[0025] (iii) Mechanically adhering the gap tube to the stator laminations.

[0026] According to a fifth aspect of the present invention, there is provided an electric motor assembly, the electric motor assembly comprising:

[0027] A rotor comprising a rotor core and a rotor sleeve circumferentially surrounding the rotor core, wherein the rotor core comprises one or more magnets, wherein the rotor sleeve comprises plastic and fiber, wherein the fiber has a tensile strength greater than or equal to 4440 MPa; and

[0028] A stator comprising a gap tube, wherein the gap tube comprises a plastic and a fiber, wherein the fiber has a tensile strength greater than or equal to 4440 MPa and a dry fiber tensile modulus in the range of 200 GPa to 450 GPa;

[0029] And wherein an air gap is arranged between the rotor sleeve and the gap tube.

[0030] According to a sixth aspect of the present invention, there is provided a vehicle comprising the above assembly.

[0031] Attached photos

[0032] Figure 1 A cross section of an electric motor including a rotor and a stator according to an embodiment of the invention is shown.

[0033] Figure 2 A cross section of an electric motor including a rotor and a stator according to an embodiment of the invention is shown.

[0034] Figure 3 A side view of an electric motor including a rotor and a stator according to one embodiment of the present invention is shown.

[0035] Figure 4 A front view of an electric motor including a rotor and a stator according to one embodiment of the present invention is shown. DETAILED DESCRIPTION

[0036] Throughout this specification, the term "comprising" means including the specified components but not excluding the presence of other components. The term "consisting essentially of" means including the specified components but not including other components except materials that appear as impurities, unavoidable materials that appear as processing results for providing components, and components added for purposes other than achieving the technical effects of the present invention. The term "consisting of" means including the specified components but not including other components.

[0037] Whenever appropriate, depending on the context, use of the term "comprising" may also be used to include the meaning "consisting essentially of" and may be used to include the meaning "consisting of.

[0038] The optional and / or preferred features described herein may be used alone or in combination with each other where appropriate, particularly in combination as described in the appended claims. The optional and / or preferred features of each aspect or exemplary embodiment of the invention as described herein are also applicable to any other aspect or exemplary embodiment of the invention where appropriate. In other words, the technician reading this specification should consider the optional and / or preferred features of each aspect or exemplary embodiment of the invention to be interchangeable and combinable between different aspects or exemplary embodiments.

[0039] Rotor

[0040] In a first aspect of the present invention, a rotor for an electric motor is provided, wherein the rotor comprises a rotor core and a rotor sleeve circumferentially surrounding the rotor core, wherein the rotor core comprises one or more magnets, wherein the rotor sleeve comprises plastic and fiber, wherein the fiber has a tensile strength greater than or equal to 4440 MPa.

[0041] One configuration of an electric motor includes a stator and a rotor. The term rotor has its usual meaning in the art. The rotor is the rotating part of the electric motor that transmits power. The rotor includes a core, which includes one or more magnets. The magnets can be permanent magnets. In one embodiment, the rotor core can include a plurality of permanent magnets, a plurality of poles of conductive material, and a yoke of conductive material. In this embodiment, the components of the rotor core are fastened and retained in the assembly by a compressed rotor sleeve, whereby the air trap is retained outside the magnet between the poles and the yoke, thereby eliminating electromagnetic eddy currents that may occur in other common rotor embodiments.

[0042] The rotor according to the present invention comprises a rotor sleeve. The term rotor sleeve has its usual meaning in the art. When the rotor rotates in use, the active elements (such as magnets) are subjected to high centrifugal forces. For optimal motor performance, the magnets in the rotor must be physically constrained in a manner that optimizes mechanical retention and electromagnetic field structure. The rotor sleeve completely circumferentially surrounds and physically constrains the rotor core including one or more magnets to optimize mechanical retention and electromagnetic field structure. In practice, mechanical retention means that the yoke, poles and magnet components remain in physical contact under all operating conditions.

[0043] The rotor sleeve comprises plastic and fibers. The rotor sleeve may comprise a plastic matrix in which the fibers are embedded. The plastic may be a thermosetting plastic or a thermoplastic or a mixture thereof. Preferably, the plastic is a thermoplastic. Thermoplastic is advantageous because it is easier to process and recycle; it produces higher pre-tension, higher toughness and lower void content, which means that the rotor sleeve is more structurally stable.

[0044] In one embodiment, the thermoplastic material can be selected from polyaryletherketone (PAEK), such as polyetheretherketone (PEEK) or polyetherketoneketone (PEKK), polyphenylene sulfide (PPS), polyetherimide (PEI), polycarbonate (PC), polyethylene terephthalate (PET), polyamide (PA), poly(methyl methacrylate), or mixtures thereof.

[0045] Preferably, the plastic is a thermoplastic comprising polyaryletherketone (PAEK), such as polyetheretherketone (PEEK). PAEKs are advantageous because they have high temperature and chemical resistance and low permeability.

[0046] In particular, PAEK may comprise repeating units of the formula:

[0047]

[0048] Wherein t1 and w1 independently represent 0 or 1, and v1 represents 0, 1 or 2.

[0049] Preferred PAEKs have repeating units where t1=1, v1=0 and w1=0; t1=0, v1=0 and w1=0; t1=0, w1=1, v1=2; or t1=0, v1=1 and w1=0. More preferred PAEKs have repeating units where t1=1, v1=0 and w1=0; or t1=0, v1=0 and w1=0. Most preferred PAEKs have repeating units where t1=1, v1=0 and w1=0.

[0050] In a preferred embodiment, PAEK is selected from polyetheretherketone, polyetherketone, polyetherketoneetherketoneketone and / or polyetherketoneketone, and / or a copolymer comprising polyetheretherketone and polyetherdiphenyletherketone. In a more preferred embodiment, PAEK is selected from polyetherketone and / or polyetheretherketone, and / or a copolymer comprising polyetheretherketone and polyetherdiphenyletherketone. In a particularly preferred embodiment, PAEK is selected from polyetheretherketone, and / or a copolymer comprising polyetheretherketone and polyetherdiphenyletherketone.

[0051] PAEK suitably comprises at least 50 mol% (e.g. 50 mol% to 99.8 mol%), preferably at least 60 mol% (e.g. 60 mol% to 100 mol%), more preferably at least 68 mol% (e.g. 68 mol% to 100 mol%) of repeating units of formula I, especially such units wherein t1=1, v1=0 and w1=0. In particularly preferred embodiments, PAEK comprises at least 90 mol%, preferably at least 95 mol%, more preferably at least 98 mol%, especially at least 99 mol% of repeating units of formula I, especially repeating units wherein t1=1, v1=0 and w1=0. The other repeating units in PAEK may be different repeating units of formula I or may comprise a -Ph-Ph- moiety, wherein Ph represents an unsubstituted phenylene moiety (especially wherein two -Ph- moieties are linked to each other and to adjacent repeating units at the 4,4' position). Other repeating units may comprise a Ph moiety bonded to two moieties selected from a carbonyl moiety and an ether moiety and a -Ph-Ph- moiety bonded to two ether moieties.

[0052] PAEK may be a copolymer comprising a first moiety of formula I, and a second moiety comprising a -Ph-Ph- moiety, wherein Ph represents an unsubstituted phenylene moiety (which suitably comprises a 4,4' linkage to an adjacent moiety).

[0053] In one embodiment, the PAEK may be selected from: polymers comprising at least 98 mol% of repeating units of formula I (especially such units wherein t1=1, v1=0 and w1=0); and copolymers comprising repeating units of the formula:

[0054] -O-Ph-O-Ph-CO-Ph-II

[0055] and a repeating unit of the formula:

[0056] -O-Ph-Ph-O-Ph-CO-Ph- III

[0057] wherein Ph represents a phenylene moiety. Preferably, the repeating units of the copolymer consist essentially of repeating units II and III.

[0058] In a preferred embodiment, PAEK is a homopolymer polyetheretherketone (PEEK) having repeating units consisting of the following formula II:

[0059] -O-Ph-O-Ph-CO-Ph-II

[0060] Or a copolymer having a repeating unit consisting of a repeating unit of formula II and a repeating unit of the following formula III:

[0061] -O-Ph-Ph-O-Ph-CO-Ph- III.

[0062] The ends of the polymer may be provided by the same monomers as those making up the repeating units, or may be provided by other compounds specifically added to provide end-capping.

[0063] The PAEK may preferably include at least 98 mol % (eg, 98 mol % to 99.9 mol %) of the repeating unit of Formula I, or a copolymer including the repeating units of Formulae II and III.

[0064] In the copolymer, the relative molar ratio VI:VII of repeating units II and III is preferably from 50:50 to 95:5, more preferably from 60:40 to 95:5, even more preferably from 65:35 to 95:5.

[0065] The phenylene moiety (Ph) in each repeating unit II and III can independently have a 1,4-para-bond or a 1,3-meta-bond to the atom to which it is bonded. In the case where the phenylene moiety contains a 1,3-bond, the moiety will be in the amorphous phase of the polymer. The crystalline phase will contain phenylene moieties with 1,4-bonds. It is generally preferred that PAEK or PEEK is semi-crystalline, for example, having a crystallinity of about 25% to 35%, and therefore, PAEK or PEEK preferably contains a high level of phenylene moieties with 1,4-bonds.

[0066] In a preferred embodiment, at least 95%, preferably at least 99%, of the number of phenylene moieties (Ph) in the repeating units of formula II have 1,4-bonds to the moiety to which they are bonded. Particularly preferably, each phenylene moiety in the repeating units of formula II has a 1,4-bond to the moiety to which it is bonded.

[0067] In a preferred embodiment, at least 95%, preferably at least 99%, of the number of phenylene moieties (Ph) in the repeating units of formula III have 1,4-bonds to the moiety to which they are bonded. Particularly preferably, each phenylene moiety in the repeating units of formula III has a 1,4-bond to the moiety to which it is bonded.

[0068] Preferably, the phenylene moiety in the repeating unit of formula II is unsubstituted. Preferably, the phenylene moiety in the repeating unit of formula III is unsubstituted.

[0069] The repeating unit of formula II preferably has the structure:

[0070]

[0071] The repeating unit of formula III preferably has the structure:

[0072]

[0073] The copolymer may comprise at least 50 mol%, preferably at least 60 mol%, of repeating units of formula IV. Particularly advantageous copolymers may comprise at least 62 mol%, or in particular at least 64 mol% of repeating units of formula IV. The copolymer may comprise less than 90 mol%, suitably 82 mol% or less of repeating units of formula IV. The copolymer may comprise 58 mol% to 82 mol%, preferably 60 mol% to 80 mol%, more preferably 62 mol% to 77 mol% of units of formula IV.

[0074] The copolymer may contain at least 10 mol%, preferably at least 18 mol%, of repeating units of formula V. The copolymer may contain less than 42 mol%, preferably less than 39 mol%, of repeating units of formula V. Particularly advantageous copolymers may contain 38 mol% or less; or 36 mol% or less of repeating units of formula V. The copolymer may contain 18 mol% to 42 mol%, preferably 20 mol% to 40 mol%, more preferably 23 mol% to 38 mol% of units of formula V.

[0075] The sum of the mol% of units of formula IV and V in the copolymer is suitably at least 95 mol%, preferably at least 98 mol%, more preferably at least 99 mol%.

[0076] In one embodiment, the rotor sleeve may be formed from plastic and fiber.

[0077] The plastic may contain optional fillers or additives.

[0078] The rotor sleeve contains fibers having a tensile strength greater than or equal to 4440 MPa. The inventors have found that the use of fibers having such a tensile strength results in a reduction in the working air gap of the electric motor. This is demonstrated in the examples below. The reduction in the air gap is extremely beneficial because it improves the motor efficiency.

[0079] In one embodiment, the fibers have a tensile strength greater than or equal to 5000 MPa, more preferably greater than or equal to 5500 MPa, more preferably greater than or equal to 6000 MPa, more preferably greater than or equal to 6500 MPa. In one embodiment, the fibers have a tensile strength less than or equal to 10000 MPa, preferably less than or equal to 9000 MPa, preferably less than or equal to 8000 MPa, preferably less than or equal to 7000 MPa. It has been found that the use of a rotor sleeve comprising fibers having a tensile strength within this range results in a reduction in the air gap in the electric motor.

[0080] In one embodiment, the fibers are selected from carbon fibers, aramid fibers or glass fibers. Preferably, the fibers are carbon fibers.

[0081] In one embodiment, the fibers have a dry fiber tensile modulus in the range of 200 GPa to 450 GPa, preferably 240 GPa to 350 GPa. It has been found that a rotor sleeve comprising fibers having a tensile modulus in this range results in a reduction in the air gap in the electric motor. This is believed to be in part because the pre-tension of the rotor sleeve can be increased, which results in a more rigid rotor sleeve. A more rigid rotor sleeve can therefore be thinner, resulting in a reduced air gap.

[0082] In one embodiment, the rotor sleeve comprises fibers having a dry fiber tensile modulus of 276 GPa and / or a tensile strength of 5600 MPa.

[0083] In one embodiment, the rotor sleeve comprises fibers having a dry fiber tensile modulus of 313 GPa and / or a tensile strength of 6800 MPa.

[0084] The tensile strength of the fiber can be measured according to ISO 11566.

[0085] Dry fiber tensile modulus can be measured according to ISO 11566.

[0086] Commercially available fibers that may be used in the rotor sleeve include IM7 (Hexcel), IM10 (Hexcel), T1100 (Toray), and AS4 (Hexcel).

[0087] In one embodiment the rotor sleeve comprises between 30% and 70% fibres by volume, more preferably between 40% and 60% fibres by volume.The inventors have found that this fibre volume produces a rotor sleeve with optimum strength whilst ensuring the plastic matrix retains structural integrity.

[0088] In one embodiment, the rotor sleeve has a thickness of less than 2.5 mm, preferably between 0.3 mm and 1.8 mm. The rotor sleeve may have a thickness between 0.4 mm and 1.5 mm. The inventors have found that by using a rotor sleeve comprising plastic and fibers as described herein, a thinner and more rigid rotor sleeve can be obtained. A rotor sleeve made of a different material needs to be thicker in order to ensure that the rotor components are constrained during rotation.

[0089] In one embodiment, the rotor sleeve may include one or more layers. The one or more layers may be formed from composite tapes. This means that the plastic forms a matrix into which the fibers are embedded. The fibers may be continuous fibers. The tape may be a unidirectional tape.

[0090] In one embodiment, the rotor sleeve has a tensile modulus between 45 GPa and 400 GPa, more preferably between 65 GPa and 360 GPa. The tensile modulus of the rotor sleeve laminations may be measured according to ISO 527. It has been found that a rotor sleeve having a tensile modulus within this range produces a reduced air gap.

[0091] In one embodiment, the plastic may contain fillers or additives to enhance mechanical or electromagnetic properties or to achieve additional functionality (eg, barium sulfate).

[0092] In one embodiment, the rotor sleeve contains magnetic fillers. This improves the magnetic flux performance, thereby increasing motor efficiency.

[0093] The rotor sleeve may include one or more sensors. The one or more sensors may be embedded in the rotor sleeve. The sensors may be used to measure properties such as temperature, strain, pressure, leak detection or air gap monitoring. The sensors may be piezoelectric sensors.

[0094] The rotor sleeve may be adapted to enhance motor cooling. The rotor sleeve may include one or more cooling channels. The rotor sleeve may include one or more Peltier elements.

[0095] In one embodiment, the rotor sleeve has a pre-tension of between 10% and 60%, preferably between 20% and 40%, and more preferably 35% of the tensile strength of the rotor sleeve. The pre-tension compresses the rotor core so that the centripetal load at normal operating speeds relaxes the magnet contact interface rather than causing separation of the magnets, yokes, and poles. In addition, because the pre-tension and centripetal load are additive, the pre-tension must not be so high as to cause rotor sleeve failure at maximum rotor speed.

[0096] In another aspect of the present invention, there is provided a method for producing a rotor comprising a rotor core and a rotor sleeve, the method comprising the following steps:

[0097] - providing a rotor core comprising one or more magnets;

[0098] - Providing a material comprising a plastic and fibers, wherein the fibers have a tensile strength greater than or equal to 4440 MPa;

[0099] - Winding the material around the rotor core such that the material is tensioned and forms a rotor sleeve circumferentially surrounding the rotor core.

[0100] The rotor in the method may have any of the preferred features described above.

[0101] In this method, the rotor sleeve is manufactured directly on the rotor components (ie the rotor core and one or more magnets). The rotor components may already be glued together for the assembly process. Alternatively, the rotor components may not yet have been glued together.

[0102] In one embodiment, the material is pre-tensioned to compress the rotor core.

[0103] In one embodiment, the material can be a fiber, a filament, a tape, a sheet or a ribbon. Preferably, the material is a tape. The fiber can be a continuous fiber. The tape can be a unidirectional tape.

[0104] In one embodiment, one or more magnets may be magnetized prior to assembling the rotor. Alternatively, one or more magnets may be magnetized after the rotor has been assembled. This has the associated benefit of increasing process temperature exposure.

[0105] In another aspect of the invention there is provided the use of a rotor sleeve for reducing an air gap in an electric motor comprising a rotor and a stator as described herein.

[0106] stator

[0107] In one aspect of the present invention, a stator for an electric motor is provided, the stator comprising a gap tube, wherein the gap tube contains plastic and fiber, wherein the fiber has a tensile strength greater than or equal to 4440 MPa and a dry fiber tensile modulus in the range of 200 GPa to 450 GPa.

[0108] One configuration of an electric motor includes a stator and a rotor. The term stator has its usual meaning in the art. The stator is the static component of the electric motor. The stator may include one or more stator windings and one or more stator laminations. The stator includes a gap tube. The gap tube is a separate component that provides a seal between the stator and the rotor by preventing oil / cooling fluid circulating across a large area of ​​the stator assembly from contacting the high-speed rotating electric rotor.

[0109] The gap tube comprises plastics and fiber. The gap tube can comprise a plastic matrix in which the fiber is embedded. The plastic can be a thermosetting plastic or a thermoplastic or a mixture thereof. Preferably, the plastic is a thermoplastic. The thermoplastic is advantageous because it is easier to process and recycle; produce higher toughness and lower void content, which means that the gap tube is more stable in structure, and the permeability to the dielectric fluid is lower. In addition, during manufacturing experiments, it was surprisingly found that when plastics was polyaryletherketone (PAEK), the gap tube showed lower void content and improved resin distribution, thereby realizing thinner gap tube without fluid leakage path, which further realizes improved motor performance, less material and faster processing.

[0110] In one embodiment, the thermoplastic material can be selected from polyaryletherketone (PAEK), such as polyetheretherketone (PEEK) or polyetherketoneketone (PEKK), polyphenylene sulfide (PPS), polyetherimide (PEI), polycarbonate (PC), polyethylene terephthalate (PET), polyamide (PA), poly(methyl methacrylate), or mixtures thereof.

[0111] Preferably, the plastic is a thermoplastic comprising polyaryletherketone (PAEK), such as polyetheretherketone (PEEK).PAEKs are advantageous because they have high temperature and chemical resistance and low permeability.

[0112] In particular, PAEK may comprise repeating units of the formula:

[0113]

[0114] Wherein t1 and w1 independently represent 0 or 1, and v1 represents 0, 1 or 2.

[0115] Preferred PAEKs have repeating units where t1=1, v1=0 and w1=0; t1=0, v1=0 and w1=0; t1=0, w1=1, v1=2; or t1=0, v1=1 and w1=0. More preferred PAEKs have repeating units where t1=1, v1=0 and w1-0; or t1=0, v1=0 and w1=0. Most preferred PAEKs have repeating units where t1=1, v1=0 and w1=0.

[0116] In a preferred embodiment, PAEK is selected from polyetheretherketone, polyetherketone, polyetherketoneetherketoneketone and / or polyetherketoneketone, and / or a copolymer comprising polyetheretherketone and polyetherdiphenyletherketone. In a more preferred embodiment, PAEK is selected from polyetherketone and / or polyetheretherketone, and / or a copolymer comprising polyetheretherketone and polyetherdiphenyletherketone. In a particularly preferred embodiment, PAEK is selected from polyetheretherketone, and / or a copolymer comprising polyetheretherketone and polyetherdiphenyletherketone.

[0117] PAEK suitably comprises at least 50 mol% (e.g. 50 mol% to 99.8 mol%), preferably at least 60 mol% (e.g. 60 mol% to 100 mol%), more preferably at least 68 mol% (e.g. 68 mol% to 100 mol%) of repeating units of formula I, especially such units wherein t1=1, v1=0 and w1=0. In particularly preferred embodiments, PAEK comprises at least 90 mol%, preferably at least 95 mol%, more preferably at least 98 mol%, especially at least 99 mol% of repeating units of formula I, especially repeating units wherein t1=1, v1=0 and w1=0. The other repeating units in PAEK may be different repeating units of formula I or may comprise a -Ph-Ph- moiety, wherein Ph represents an unsubstituted phenylene moiety (especially wherein two -Ph- moieties are linked to each other and to adjacent repeating units at the 4,4' position). Other repeating units may comprise a Ph moiety bonded to two moieties selected from a carbonyl moiety and an ether moiety and a -Ph-Ph- moiety bonded to two ether moieties.

[0118] PAEK may be a copolymer comprising a first moiety of formula I, and a second moiety comprising a -Ph-Ph- moiety, wherein Ph represents an unsubstituted phenylene moiety (which suitably comprises a 4,4' linkage to an adjacent moiety).

[0119] In one embodiment, the PAEK may be selected from: polymers comprising at least 98 mol% of repeating units of formula I (especially such units wherein t1=1, v1=0 and w1=0); and copolymers comprising repeating units of the formula:

[0120] -O-Ph-O-Ph-CO-Ph-II

[0121] and a repeating unit of the formula:

[0122] -O-Ph-Ph-O-Ph-CO-Ph- III

[0123] wherein Ph represents a phenylene moiety. Preferably, the repeating units of the copolymer consist essentially of repeating units II and III.

[0124] In a preferred embodiment, PAEK is a homopolymer polyetheretherketone (PEEK) having repeating units consisting of the following formula II:

[0125] -O-Ph-O-Ph-CO-Ph-II

[0126] Or a copolymer having a repeating unit consisting of a repeating unit of formula II and a repeating unit of the following formula III:

[0127] -O-Ph-Ph-O-Ph-CO-Ph- III.

[0128] The ends of the polymer may be provided by the same monomers as those making up the repeating units, or may be provided by other compounds specifically added to provide end-capping.

[0129] The PAEK may preferably include at least 98 mol % (eg, 98 mol % to 99.9 mol %) of the repeating unit of Formula I, or a copolymer including the repeating units of Formulae II and III.

[0130] In the copolymer, the relative molar ratio VI:VII of repeating units II and III is preferably from 50:50 to 95:5, more preferably from 60:40 to 95:5, even more preferably from 65:35 to 95:5.

[0131] The phenylene moiety (Ph) in each repeating unit II and III can independently have a 1,4-para-bond or a 1,3-meta-bond to the atom to which it is bonded. In the case where the phenylene moiety contains a 1,3-bond, the moiety will be in the amorphous phase of the polymer. The crystalline phase will contain phenylene moieties with 1,4-bonds. It is generally preferred that PAEK or PEEK is semi-crystalline, for example, having a crystallinity of about 25% to 35%, and therefore, PAEK or PEEK preferably contains a high level of phenylene moieties with 1,4-bonds.

[0132] In a preferred embodiment, at least 95%, preferably at least 99%, of the number of phenylene moieties (Ph) in the repeating units of formula II have 1,4-bonds to the moiety to which they are bonded. Particularly preferably, each phenylene moiety in the repeating units of formula II has a 1,4-bond to the moiety to which it is bonded.

[0133] In a preferred embodiment, at least 95%, preferably at least 99%, of the number of phenylene moieties (Ph) in the repeating units of formula III have 1,4-bonds to the moiety to which they are bonded. Particularly preferably, each phenylene moiety in the repeating units of formula III has a 1,4-bond to the moiety to which it is bonded.

[0134] Preferably, the phenylene moiety in the repeating unit of formula II is unsubstituted. Preferably, the phenylene moiety in the repeating unit of formula III is unsubstituted.

[0135] The repeating unit of formula II preferably has the structure:

[0136]

[0137] The repeating unit of formula III preferably has the structure:

[0138]

[0139] The copolymer may comprise at least 50 mol%, preferably at least 60 mol%, of repeating units of formula IV. Particularly advantageous copolymers may comprise at least 62 mol%, or in particular at least 64 mol% of repeating units of formula IV. The copolymer may comprise less than 90 mol%, suitably 82 mol% or less of repeating units of formula IV. The copolymer may comprise 58 mol% to 82 mol%, preferably 60 mol% to 80 mol%, more preferably 62 mol% to 77 mol% of units of formula IV.

[0140] The copolymer may contain at least 10 mol%, preferably at least 18 mol%, of repeating units of formula V. The copolymer may contain less than 42 mol%, preferably less than 39 mol%, of repeating units of formula V. Particularly advantageous copolymers may contain 38 mol% or less; or 36 mol% or less of repeating units of formula V. The copolymer may contain 18 mol% to 42 mol%, preferably 20 mol% to 40 mol%, more preferably 23 mol% to 38 mol% of units of formula V.

[0141] The sum of the mol% of units of formula IV and V in the copolymer is suitably at least 95 mol%, preferably at least 98 mol%, more preferably at least 99 mol%.

[0142] In one embodiment, the interlayer tube may be formed from plastic and fiber.

[0143] The plastic may contain optional fillers or additives.

[0144] The gap tube contains fibers having a tensile strength greater than or equal to 4440 MPa. The inventors have found that the use of fibers having such a tensile strength results in a reduction in the air gap of the electric motor. This is demonstrated in the examples below. The reduction in the air gap is extremely beneficial because it improves the motor efficiency.

[0145] In one embodiment, the fibers have a tensile strength of greater than or equal to 5000 MPa, more preferably greater than or equal to 5500 MPa, more preferably greater than or equal to 6000 MPa, more preferably greater than or equal to 6500 MPa. In one embodiment, the fibers have a tensile strength of less than or equal to 10000 MPa, preferably less than or equal to 9000 MPa, preferably less than or equal to 8000 MPa, preferably less than or equal to 7000 MPa. It has been found that the use of a gap tube containing fibers with a tensile strength in this range results in a reduction in the air gap in the electric motor. This is because it allows for a thinner gap tube wall thickness, which enables the air gap to be reduced and the motor efficiency to be improved.

[0146] In one embodiment, the fibers are selected from carbon fibers, aramid fibers or glass fibers. Preferably, the fibers are carbon fibers.

[0147] The gap tube contains fibers having a dry fiber tensile modulus in the range of 200 GPa to 450 GPa, preferably 240 GPa to 350 GPa. It has been found that a gap tube containing fibers having a tensile modulus in this range leads to a reduction in the air gap in the electric motor.

[0148] In one embodiment, the interstitial tube comprises fibers having a dry fiber tensile modulus of 276 GPa and / or a tensile strength of 5600 MPa.

[0149] In one embodiment, the interstitial tube comprises fibers having a dry fiber tensile modulus of 313 GPa and / or a tensile strength of 6800 MPa.

[0150] The tensile strength of the fiber can be measured according to ISO 11566.

[0151] Dry fiber tensile modulus can be measured according to ISO 11566.

[0152] Commercially available fibers that can be used for the interstitial tube include IM7 (Hexcel), IM10 (Hexcel), T1100 (Toray), and AS4 (Hexcel).

[0153] In one embodiment, the gap tube may contain between 30% and 70% by volume of fibers, more preferably between 40% and 60% by volume of fibers. The inventors have found that this fiber volume produces a rotor sleeve with optimal strength while ensuring that the plastic matrix maintains structural integrity.

[0154] In one embodiment, the gap tube can have a thickness between 0.1 mm and 3 mm, more preferably 0.28 mm to 2.8 mm. The inventors have found that by using a gap tube comprising plastic and fiber as described herein, a thinner gap tube can be obtained. Because the gap tube according to the present invention is thinner than the existing gap tube, this produces several advantages. For example, assembly efficiency and robustness are improved, partly because the variability between parts is small, which enables more efficient assembly. In addition, since less material is required to make thinner gap tubes, the environmental footprint is reduced. Using less material also means that the manufacturing process is faster, thereby achieving increased manufacturing output.

[0155] In one embodiment, the gap tube may include one or more layers. The one or more layers may be formed from composite tapes. This means that the plastic forms a matrix into which the fibers are embedded. The fibers may be continuous fibers. The tape may be a unidirectional tape.

[0156] In one embodiment, the gap tube comprises one or more thermoplastic film layers on the outer and / or inner and / or intermediate layer. The purpose of this layer is to seal the gap tube against fluid intrusion.

[0157] In one embodiment, the gap tube has a tensile modulus between 45 GPa and 400 GPa, more preferably between 65 GPa and 360 GPa. The tensile modulus of the gap tube can be measured according to ISO 527. It has been found that gap tubes with a tensile modulus within this range produce reduced air gaps.

[0158] The gap tube may include one or more sensors. The one or more sensors may be embedded in the gap tube. The sensor may be used to measure properties such as temperature, strain, pressure, leak detection or air gap monitoring. The sensor may be a piezoelectric sensor.

[0159] The interstitial tube may be adapted to enhance stator cooling. The interstitial tube may include one or more Peltier elements to supplement or replace stator fluid. The interstitial tube may contain axially aligned conductive fibers and contact with conductive material on the ends to improve cooling.

[0160] In one embodiment, the plastic may contain fillers or additives to enhance mechanical or electromagnetic properties or to achieve additional functionality (eg, barium sulfate).

[0161] In one embodiment, the gap tube contains magnetic filler. This improves the magnetic flux performance, thereby increasing motor efficiency.

[0162] In one aspect of the present invention, a method for producing a stator comprising a lamination stack and a gap tube is provided, the method comprising the following steps:

[0163] - providing a stator comprising a lamination stack;

[0164] - providing an interstitial tube comprising a plastic and fibers, wherein the fibers have a tensile strength greater than or equal to 4440 MPa and a dry fiber tensile modulus in the range of 200 GPa to 450 GPa; and

[0165] - Adhering the gap tube to the stator lamination.

[0166] The stator in the method may have any of the preferred features described above.

[0167] The gap tubes may be adhered to the stator laminations chemically, mechanically or covalently, or a combination thereof.

[0168] There are several advantages to adhering the cans to the stator laminations. First, the fluid pressure is controlled in the stator channels, thereby reducing the forces on the cans due to the fluid pressure and enabling the cans to be thinner to achieve the same mechanical properties. Second, the adhering of the cans to the stator radially strengthens the cans, also enabling the cans to be thinner to achieve the same mechanical properties (radial stiffness). Thus, this method of adhering the cans to the stator laminations further reduces the air gap and improves the efficiency of the electric motor because it allows the cans to be thinner and therefore the air gap to be smaller.

[0169] In one embodiment, the adhering is selected from the group consisting of adhesives, mechanical interlocking, laser welding, torch welding, ultrasonic bonding, centrifugal casting, and injection molding.

[0170] In one embodiment, the gap tube may be bonded to the stator using heat and / or pressure to melt the plastic at the interface with the stator, thereby creating micro- and / or macro-mechanical adhesion.

[0171] In one embodiment, the can may be bonded to the stator by overmolding the can directly onto the stator component or assembly.

[0172] In one embodiment, the stator laminations may be surface treated before the gap tubes are mechanically adhered. The surface treatment may include a chemical etching process, mechanical treatment, and / or other surface activation methods.

[0173] The gap tube can be made by any known technology. It can be made of a strip containing plastic and fiber. It can be made via a mandrel and automatic strip placement or filament winding machine. The strip can be consolidated in situ to form the gap tube.

[0174] In another aspect of the invention, there is provided the use of a gap tube for reducing an air gap in an electric motor comprising a rotor and a stator as described herein.

[0175] Electric Motor Components

[0176] In one aspect of the present invention, there is provided an electric motor assembly, the electric motor assembly comprising:

[0177] A rotor comprising a rotor core and a rotor sleeve circumferentially surrounding the rotor core, wherein the rotor core comprises one or more magnets, wherein the rotor sleeve comprises plastic and fiber, wherein the fiber has a thickness greater than or equal to 100 mm.

[0178] A tensile strength equal to 4440 MPa; and

[0179] A stator comprising a gap tube, wherein the gap tube comprises a plastic and a fiber, wherein the fiber has a tensile strength greater than or equal to 4440 MPa and a dry fiber tensile modulus in the range of 200 GPa to 450 GPa;

[0180] And wherein an air gap is arranged between the rotor sleeve and the gap tube.

[0181] The rotor may have any of the optional features described above.

[0182] The stator may have any of the above-mentioned optional features.

[0183] The electric motor may be any type of electric motor.

[0184] The term "air gap" is well known in the art. It is defined as the space between the magnetized components of the rotor (e.g., one or more magnets in the rotor core) and the stator laminations. The inventors have found that the combined use of a gap tube for the stator and a rotor sleeve for the rotor as described herein results in a significant reduction in the air gap. This improves the efficiency of the electric motor. The rotor sleeve and gap tube as described herein form part of the air gap, but the rotor sleeve and gap tube can be made thinner by using plastics and fibers with the required tensile strength and / or dry tensile modulus. Due to the rigid nature of the rotor sleeve and the gap tube, the flexing of the parts of the electric motor during use is reduced, and therefore the mechanical clearance (i.e., the space between the rotor sleeve and the gap tube) can be significantly reduced.

[0185] In one embodiment, the air gap has a distance of 0.9 mm to 5.5 mm, preferably 1.1 mm to 3 mm.

[0186] In one embodiment, the gap tube has a thickness of 0.3 mm to 3 mm; the rotor sleeve has a thickness of 0.3 mm to 2 mm, and the air gap has a distance of 0.9 mm to 5.5 mm.

[0187] In one embodiment, the electromagnetic separation of the yoke and poles in the rotor core achieved by the rotor sleeve increases the simulated torque output of the electric motor by 21% through reduced leakage flux and increased reluctance torque. In another embodiment, the combination of the gap tube and the rotor sleeve further increases the maximum power output of the electric motor by 22% and increases the maximum efficiency by 0.5%. In another embodiment, the gap tube can increase the continuous motor torque by 30% and increase the continuous motor power by 40% compared to a water-jacket cooled motor of similar size and mass.

[0188] In one embodiment, the electric motor is designed to operate at a motor speed in the range of 20,000 rpm to 45,000 rpm, preferably 25,000 rpm to 40,000 rpm, more preferably 30,000 rpm to 40,000 rpm.

[0189] vehicle

[0190] In one aspect of the invention, there is provided a vehicle comprising an electric motor assembly, the electric motor assembly comprising:

[0191] A rotor comprising a rotor core and a rotor sleeve circumferentially surrounding the rotor core, wherein the rotor core comprises one or more magnets, wherein the rotor sleeve comprises plastic and fiber, wherein the fiber has a thickness greater than or equal to 100 mm.

[0192] A tensile strength equal to 4440 MPa; and

[0193] A stator comprising a gap tube, wherein the gap tube comprises a plastic and a fiber, wherein the fiber has a tensile strength greater than or equal to 4440 MPa and a dry fiber tensile modulus in the range of 200 GPa to 450 GPa;

[0194] And wherein an air gap is arranged between the rotor sleeve and the gap tube.

[0195] In one embodiment, the vehicle may be selected from a light passenger vehicle, a high performance vehicle, a car, a truck, a bus, or a train. BRIEF DESCRIPTION OF THE DRAWINGS

[0196] Figure 1 and Figure 2A cross section of an electric motor 11 including a rotor 9 and a stator 10 according to one embodiment of the present invention is shown. The rotor 9 includes a rotor yoke 1, magnets 2 and poles 3. These form a rotor core 8. There are two performance categories that the rotor core geometry must accommodate: mechanical and electromagnetic. The rotor 9 must have sufficient strength to withstand high rotational speeds and torque transmission through the yoke. At the same time, the rotor core 8 must be constructed to optimize the electromagnetic field geometry to achieve electric motor efficiency. One purpose of the rotor sleeve 4 is to alleviate the compromise between mechanical geometry and electromagnetic geometry by supplementing the mechanical load of the rotor core 8 with the rotor sleeve 4, thereby achieving a more preferred electromagnetic configuration of the rotor core 8, contributing to the increased efficiency and / or power of the electric motor 11. The magnet 2 may be a permanent magnet. The rotor yoke 1 and the poles 3 may be made of a conductive material such as steel. The rotor 9 includes a rotor sleeve 4, which circumferentially surrounds the rotor core. The rotor sleeve 4 contains plastic and fiber, wherein the fiber has a tensile strength greater than or equal to 4440 MPa.

[0197] The stator 10 includes a stator winding 6, a stator lamination 7 and a gap tube 5. Typically, the continuous operating limit of the stator is thermally limited to below the instantaneous maximum power output of the motor. Therefore, the motor power output and efficiency applied in the application may be greatly affected by the thermal management of the stator. A preferred method of stator cooling is oil cooling of the stator winding. When the oil coolant contacts the rotor 9, this will cause fluid power losses. The purpose of the gap tube 5 is to separate the stator 10 and the rotor 9. The gap tube 5 contains plastic and fiber, wherein the fiber has a tensile strength greater than or equal to 4440MPa and a dry fiber tensile modulus in the range of 200GPa to 450GPa.

[0198] Air gap 14 in Figure 1 The air gap is the space between the rotor magnetized components (rotor yoke 1, magnets 2 and poles 3) and the stator laminations 7. This distance should be minimized to maximize electromagnetic efficiency. Figure 1 Also shown is a mechanical gap 13, which is the running gap between the rotor sleeve 4 and the clearance tube 5. This is required for mechanical efficiency and to prevent binding. Figure 1 An electromagnetic gas trap 12 is also shown.

[0199] Figure 3 A side view of an electric motor 11 including a rotor 9 and a stator 10 according to one embodiment of the present invention is shown. The stator 10 is cylindrical and includes a plurality of windings 6 around its circumference. The stator 10 has a hollow center in which the rotor 9 is held. The rotor 9 includes a plurality of magnets 2 and poles 3 located within a rotor core 8. Figure 4 Shows Figure 3 A front view of the electric motor 11 in FIG.

[0200] Example

[0201] Example 1

[0202] In Example 1, a 2D analysis model of the rotor sleeve as a simplified thin-walled tube was combined with a linear elastic finite element model (FEM: Altair Hyperworks) for comparative analysis of the rotor sleeve, while a linear elastic composite finite element model was used for comparative analysis of the gap tube. The results are shown in Tables 1 and 2.

[0203]

[0204] Table 1: Rotor sleeve

[0205] As can be seen from the results in Table 1, the rotor sleeve according to the present invention (comprising fibers having a tensile strength higher than 4440 MPa) produces a reduced air gap.

[0206]

[0207] Table 2: Clearance tube

[0208] As can be seen from the results in Table 2, the gap tube according to the present invention (comprising fibers having a tensile strength higher than 4440 MPa and a dry tensile modulus in the range of 200 GPa to 450 GPa) produces a reduced air gap.

[0209] Example 2

[0210] In Example 2, a 2D analytical-numerical model (AVL simulation tool chain AVLeSUITE for electromagnetic design) was used. TM ), which simulates the benefits of a particular embodiment of a rotor sleeve and a gap tube relative to a baseline motor configuration of a permanent magnet synchronous motor (PMSM) with water jacket cooling ("Baseline" in Table 3). The following benefits in Table 3 have been determined, indexed relative to the baseline.

[0211] Existing technology implementation plan (baseline) Embodiment 1 of the present invention Embodiment 2 of the present invention Comparison torque Baseline +30％ +30％ Comparison power Baseline +40％ +40％ Maximum Power Baseline +0％ +25％ efficiency Baseline +5％ +5.5％

[0212] Table 3: Performance simulation benefits

[0213] Inventive Embodiment 1: Baseline machine with direct stator cooling using a can according to the invention similar to Test 8d in Table 2 above instead of the baseline water jacket.

[0214] Embodiment 2 of the present invention: An electric motor according to Embodiment 1 of the present invention, to which a rotor sleeve according to the present invention similar to Test 3 in Table 1 above is added.

[0215] Through additional simulation scenarios, it was found that for every 1 mm reduction in air gap, there was typically a corresponding increase in efficiency of 1%.

[0216] Further optimizations are expected due to system design changes that reflect and optimize the duty cycle for specific vehicle platforms.

[0217] Example 3

[0218] In Example 3, two configurations of interlayer tubes according to the present invention were produced.

[0219] Configuration 1: PAEK resin gap tube with a thickness of 0.4 mm; fiber modulus of 240 GPa and fiber tensile strength of 4440 MPa. This was manufactured using industry standard thermoplastic composite manufacturing methods, specifically Automated Fibre Placement (AFP).

[0220] Configuration 2: PAEK resin gap tube with a thickness of 0.8 mm; fiber modulus of 240 GPa and fiber tensile strength of 4440 MPa. This was manufactured using industry standard thermoplastic composite manufacturing methods, specifically Automated Fibre Placement (AFP).

[0221] In this example, it was surprisingly found that reduced thickness improved the quality measured by outer diameter uniformity. It was found that due to the presence of PAEK resin and fiber distribution, the tolerance stack-up could be reduced by approximately 40%, resulting in a thinner product that still maintained impermeable properties.

[0222] A thinner gap tube with higher dimensional quality manufactured as above will achieve:

[0223] Improved component efficiency and robustness

[0224] Reduced debris and waste

[0225] Increased manufacturing output

[0226] Reduced environmental footprint

[0227] This also affects the overall size of the inner surface of the can, thereby achieving further benefits as described in Table 3 of Example 2.

Claims

1. A rotor for an electric motor, wherein the rotor comprises a rotor core and a rotor sleeve circumferentially surrounding the rotor core, wherein the rotor core comprises one or more magnets, wherein the rotor sleeve comprises plastic and fiber, wherein the fiber has a tensile strength greater than or equal to 4440 MPa.

2. A rotor according to claim 1, wherein the fibers are selected from carbon fibers, aramid fibers or glass fibers, preferably wherein the fibers are carbon fibers.

3. A rotor according to any preceding claim, wherein the fibres have a tensile strength greater than or equal to 5000 MPa, more preferably greater than or equal to 5500 MPa, more preferably greater than or equal to 6000 MPa, more preferably greater than or equal to 6500 MPa.

4. A rotor according to any preceding claim, wherein the fibres have a dry fibre tensile modulus in the range 200 GPa to 450 GPa, preferably 240 GPa to 350 GPa.

5. The rotor according to claim 4, wherein the dry fiber tensile modulus is 276 GPa and / or the tensile strength is 5600 MPa.

6. The rotor according to claim 4, wherein the dry fiber tensile modulus is 313 GPa and / or the tensile strength is 6800 MPa.

7. A rotor according to any preceding claim, wherein the rotor sleeve has a thickness of less than 2.5 mm, preferably between 0.3 mm and 1.8 mm, preferably 0.4 mm to 1.5 mm.

8. A rotor according to any preceding claim, wherein the rotor sleeve comprises between 30 and 70% by volume of fibres, preferably between 40 and 60% by volume of fibres.

9. A rotor according to any preceding claim, wherein the plastic is a thermoplastic, preferably wherein the thermoplastic comprises polyaryletherketone (PAEK).

10. A rotor according to any preceding claim, wherein the rotor sleeve has a pre-tensioning force of between 10% and 60%, preferably between 20% and 40%, of the rotor sleeve tensile strength.

11. A method for producing a rotor comprising a rotor core and a rotor sleeve, the method comprising the following steps: - providing a rotor core comprising one or more magnets; - Providing a material comprising a plastic and fibers, wherein the fibers have a tensile strength greater than or equal to 4440 MPa; - Winding the material around the rotor core such that the material is tensioned and forms a rotor sleeve circumferentially surrounding the rotor core.

12. The method of claim 11, wherein the material is a fiber, a filament, a tape, a sheet or a ribbon.

13. A stator for an electric motor, the stator comprising a gap tube, wherein the gap tube comprises plastic and fibers, wherein the fibers have a tensile strength greater than or equal to 4440 MPa and a dry fiber tensile modulus in the range of 200 GPa to 450 GPa.

14. The stator according to claim 13, wherein the fibers are selected from carbon fibers, aramid fibers or glass fibers, preferably wherein the fibers are carbon fibers.

15. The stator according to claim 13 or 14, wherein the fibers have a tensile strength greater than or equal to 5000 MPa, more preferably greater than or equal to 5500 MPa, more preferably greater than or equal to 6000 MPa, more preferably greater than or equal to 6500 MPa.

16. A stator according to any one of claims 13 to 15, wherein the fibres have a dry fibre tensile modulus in the range of 240 GPa to 350 GPa.

17. A stator according to any one of claims 13 to 16, wherein the fibres have a dry fibre tensile modulus of 276 GPa and / or a tensile strength of 5600 MPa.

18. A stator according to any one of claims 13 to 16, wherein the fibres have a dry fibre tensile modulus of 313 GPa and / or a tensile strength of 6800 MPa.

19. The stator according to any one of claims 13 to 18, wherein the gap tube has a thickness between 0.3 mm and 3 mm.

20. The stator according to any one of claims 13 to 19, wherein the interspace tube contains between 30 and 70% by volume of fibers, more preferably between 40 and 60% by volume of fibers.

21. A stator according to any one of claims 13 to 20, wherein the plastic is a thermoplastic, preferably wherein the thermoplastic comprises polyaryletherketone (PAEK).

22. A method for producing a stator comprising a lamination stack and a gap tube, the method comprising the following steps: - providing a stator comprising a lamination stack; - providing an interstitial tube comprising a plastic and fibers, wherein the fibers have a tensile strength greater than or equal to 4440 MPa and a dry fiber tensile modulus in the range of 200 GPa to 450 GPa; as well as - Adhering the can to the stator laminations.

23. The method according to claim 22, wherein the adhesion is selected from mechanical adhesion, such as laser welding, torch welding, ultrasonic bonding, centrifugal casting and injection molding; or chemical adhesion or covalent adhesion or a combination thereof.

24. An electric motor assembly, the electric motor assembly comprising: a rotor comprising a rotor core and a rotor sleeve circumferentially surrounding the rotor core, wherein the rotor core comprises one or more magnets, wherein the rotor sleeve comprises a plastic and a fiber, wherein the fiber has a tensile strength greater than or equal to 4440 MPa; and A stator comprising a gap tube, wherein the gap tube comprises a plastic and a fiber, wherein the fiber has a tensile strength greater than or equal to 4440 MPa and a dry fiber tensile modulus in the range of 200 GPa to 450 GPa; And wherein an air gap is provided between the rotor sleeve and the can.

25. A vehicle comprising an assembly according to claim 24.

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