Rotor, electric machine comprising a rotor, and vehicle comprising an electric machine

Abstract

A rotor (100) is presented, comprising: - a rotor hub (110) of a first material; - a plurality of magnet retainers (120) of a second material, the second material being different from the first material, and the plurality of magnet retainers (120) being attached to the rotor hub (110) around a rotation axis (115) of the rotor; - a plurality of magnets (130) arranged around the rotation axis (115), wherein each magnet (130) is arranged between and held in place by two magnet retainers (120); wherein - each magnet retainer (120) is attached to the rotor hub (110) by a joint (121) 10, the joint comprising a male joint part (122) of the magnet retainer (120) that fits into a female joint part (112) of the rotor hub (110); and - the male joint part (122) comprises one or more cavities (125) confined within the male joint part (122).

Description

Technical Field

[0001] This invention relates to a rotor, and more particularly to a rotor for use in an electric motor. The invention also relates to an electric motor including a rotor, and to a carrier including an electric motor. Background Technology

[0002] The following background description constitutes the background of this invention; however, it does not necessarily have to constitute prior art.

[0003] An electric motor comprises a stator and a rotor, wherein the stator is configured to be stationary and the rotor is configured to rotate within the stator. Electrical energy flows through the stator to or from the rotating rotor. In an electric motor, electrical energy is converted into mechanical energy using interacting magnetic fields and current-carrying conductors / windings / coils. The stator provides the rotating magnetic field that drives the rotor. More specifically, alternating current supplied to the stator windings excites these windings to generate the rotating magnetic field. The rotating magnetic field in the air gap between the stator and rotor causes current to flow through the rotor windings. The rotating magnetic field and the resulting current provide the torque that rotates the rotor. Conversely, in a generator, the stator instead converts the rotating magnetic field from the rotor into current.

[0004] For some rotor types, the rotor magnets are oriented such that a portion of the rotating magnetic field that should pass through the air gap between the stator and rotor instead passes through the rotor hub, resulting in so-called leakage flux. This reduces the rotating magnetic field in the air gap and thus leads to a reduction in the torque provided by the electric motor. Summary of the Invention

[0005] Conventional solutions for reducing the magnetic field in the hub portion of the rotor involve using a non-magnetic material in the rotor hub.

[0006] However, using such non-magnetic materials for the rotor hub can lead to problems with rotor stability and / or integrity because conventional solutions for rotors often lack sufficient mechanical strength. Therefore, conventional solutions may cause the rotor to be unable to withstand the forces experienced during forward rotation, potentially leading to rotor breakage.

[0007] Therefore, the object of the present invention is to provide a rotor that at least partially solves these problems.

[0008] According to one aspect of the invention, this objective is achieved by the rotor mentioned above. The rotor comprises: - Rotor hub made of the first material; - A plurality of magnet holders made of a second material, which is different from the first material, and the plurality of magnet holders are attached to the rotor hub about the rotation axis of the rotor; - A plurality of magnets arranged around the axis of rotation, wherein each magnet is positioned between two magnet holders and held in place by the two magnet holders; wherein - Each magnet retainer is attached to the rotor hub via a connector, the connector including a male connector portion of the magnet retainer that mates with a female connector portion of the rotor hub; and - The male connector portion includes one or more cavities confined within the male connector portion.

[0009] Because the male connector portion has one or more cavities, it is elastically deformable, which imparts improved mechanical strength and robustness to the male connector portion and the connector as a whole compared to conventional solutions. Consequently, the risk of plastic deformation and / or breakage of the male connector portion is significantly reduced when the male connector portion is inserted into the female connector portion and during rotor rotation in motor operation.

[0010] The elastic deformation of the male connector portion, provided by one or more cavities confined within the male connector portion, causes the elasticity of the male connector portion and the connector itself. This elasticity ensures that the magnets remain intact (i.e., always in contact), allowing the magnets to be securely fixed to the magnet retainer and thus firmly attached to the rotor hub. Without this elasticity, i.e., for a very stiff magnet retainer, there is a risk that the slots / pockets between the magnet retainers (in which the magnets are arranged) may become larger than required (i.e., larger than the magnets) due to plastic deformation. This plastic deformation may lead to reduced motor performance and / or breakage of the magnet retainer and / or the magnets.

[0011] The improved mechanical strength of the joint allows all rotor components (including the rotor hub, magnet retainer, and magnets) to function as a single, integral unit, but which may consist of multiple assembled parts made of different materials. Since it is possible to provide improved rotor integrity by utilizing the improved mechanical strength of the joint, one or more materials for the rotor hub can be selected to minimize the magnetic field passing through it. This minimized magnetic field through the rotor hub, in turn, results in a maximized magnetic field passing through the air gap between the rotor and stator. Thus, improved torque can be provided by a motor comprising both a stator and a rotor.

[0012] The proposed rotor also eliminates the need for additional flexural supports (e.g., ring-shaped supports) for the magnet retainer and / or magnet, which are typically required in conventional solutions. Therefore, the proposed rotor simplifies rotor production and reduces its manufacturing costs.

[0013] According to an embodiment of the present invention, the one or more cavities are free of solid material and are arranged to be elastically contractible.

[0014] Since no solid material is arranged inside one or more cavities according to this embodiment, the size of the cavities can be reduced when the male connector portion is under pressure (e.g., when the male connector portion is inserted into the female connector portion and / or during rotor rotation). The elastic deformation / contraction of the one or more cavities thus provided results in elastic deformation of the male connector portion, allowing the volume of the outer surface of the male connector portion to be elastically reduced, thereby providing elasticity and increased mechanical strength.

[0015] According to embodiments of the present invention, the one or more cavities include one or more of the following: - At least one surface cavity of the male connector portion; and - At least one confined cavity inside the surface of the male connector portion.

[0016] One or more cavities may be configured / arranged according to the form and size of the male connector portion and / or the current implementation of the rotor. Thus, depending on the implementation, the number of cavities and / or the placement of the cavities may be selected to provide elastic deformation and / or cooling suitable for that implementation.

[0017] According to an embodiment of the present invention, the one or more cavities extend along the rotation axis from a first axial end of the male connector portion to a second axial end of the male connector portion.

[0018] Therefore, one or more cavities are arranged along the entire axial length of the male connector portion (i.e., along the entire axial length of the magnet retainer), and thus substantially along the axial length of the rotor. This allows coolant to be guided through at least one of the cavities, thereby providing cooling to the rotor. Furthermore, the manufacture of the magnet retainer is simplified by allowing one or more cavities to extend along the entire length of the male connector portion (i.e., along the length of the magnet retainer).

[0019] According to an embodiment of the present invention, at least one of the one or more cavities guides coolant from the first axial end to the second axial end.

[0020] Thus, one or more cavities provide a combination of improved mechanical strength of the joint and cooling of the rotor.

[0021] According to an embodiment of the present invention, at least one of the one or more cavities is filled with air.

[0022] This provides controlled and predictable elastic deformation of the male connector portion.

[0023] According to an embodiment of the present invention, - The cross-section perpendicular to the axis of rotation of the male connector portion has a male dovetail shape; and - The cross section perpendicular to the axis of rotation of the female connector portion has a female dovetail shape.

[0024] Due to the way the tails and pins of the male and female parts of the joint are shaped, the dovetail joint is a robust joint. Therefore, the joint is difficult to pull apart when mated. By using a dovetail joint with one or more cavities arranged in the male part of the dovetail joint, a robust and sturdy joint effect is also provided when the rotor hub and magnet retainer use different materials.

[0025] According to an embodiment of the present invention, - The male connector portion has a partially circular cross-section perpendicular to its axis of rotation; and - The cross-section perpendicular to the axis of rotation of the female connector portion has a partially circular female shape.

[0026] In some implementations, partially circular connectors are suitable for attaching magnet retainers to rotor hubs. By using partially circular connectors with one or more cavities arranged in the male connector portion, a robust and sturdy combination of connectors is also provided when the male and female connector portions are made of different materials.

[0027] According to an embodiment of the present invention, the male connector portion is attached to the female connector portion by an interference fit.

[0028] An interference fit (also known as a press fit or friction fit) utilizes the friction caused by the interference between the male and female parts after the male part is pushed / pressed against the female part. The breakage between the male and female parts is offset by the contact force generated by the interference fit, resulting in a strong and robust connection.

[0029] According to one aspect of the invention, the one or more cavities are arranged to provide one or more of the following: - The elastic deformation of the male connector portion when it is inserted into the female connector portion; and - The spring function between the male connector and the female connector when the rotor is rotating in the forward direction.

[0030] Because the male connector portion includes one or more cavities, it is elastically deformable when inserted into the female connector portion. This imparts improved mechanical strength and robustness to the male connector portion itself and the entire connector. The risk of plastic deformation and / or fracture of the male connector portion due to stiffness is significantly reduced because it is elastically deformable through one or more cavities.

[0031] The one or more cavities confined within the male connector portion also induce a spring function in the connector. Therefore, the one or more cavities provide elasticity to the male connector portion, which serves to robustly and securely hold the magnet to the magnet retainer. This elasticity significantly reduces the risk of the magnet being loosely held by the magnet retainer due to plastic deformation of the magnet retainer, resulting in slots / pockets between the magnet retainers being too large for the magnet. Therefore, the provided elasticity reduces the risk of rotor performance degradation, as well as the risk of the magnet retainer and / or the magnet breaking due to stiffness during rotor rotation.

[0032] According to one aspect of the invention, - The first material is at least partially low magnetic or non-magnetic; and - The second material is at least partially ferromagnetic.

[0033] By selecting a first material for the rotor hub that is at least partially low-magnetic or non-magnetic and a second material for the magnet retainer that is at least partially ferromagnetic, the magnetic field concentration in the air gap between the rotor and the surrounding stator is maximized. This is because the low-magnetic or non-magnetic material of the rotor hub effectively reduces the portion of the magnetic field that passes through the rotor hub.

[0034] According to one aspect of the invention, - The rotor is a spoked rotor; and - The magnet is a permanent magnet.

[0035] Compared to many other types of rotors, spoked rotors exhibit a higher magnetic field density in the air gap between the stator and rotor. However, some magnetic field still risks looping through the rotor hub due to the orientation of the magnets. The magnetic field density in the air gap is further increased when one or more cavities, as described herein, are arranged on the male connector portion of the magnet retainer of the spoked rotor. Therefore, spoked rotors utilizing the rotors described herein provide a large amount of useful magnetic field, which can be used to provide rotor rotation.

[0036] According to one aspect of the invention, each magnet is glued to the two magnet holders disposed therebetween.

[0037] Thus, the magnet is further secured to its adjacent magnet holder, thereby providing a more integrated rotor that functions as a single unit, but is composed of multiple components.

[0038] According to one aspect of the invention, this objective is achieved by an electric motor comprising: - Stator; and - As described herein, the rotor is arranged radially inside the stator.

[0039] The motor has the advantages mentioned above regarding the rotor.

[0040] According to one aspect of the invention, this objective is achieved by a vehicle comprising the motor described herein.

[0041] The carrier has the advantages mentioned above for the rotor. Attached Figure Description

[0042] Embodiments of the invention will now be illustrated in more detail with reference to the accompanying drawings, wherein similar reference numerals are used for similar parts, and wherein: Figure 1 An example vehicle in which embodiments of the present invention can be implemented is schematically shown. Figure 2 An electric motor in which embodiments of the invention can be implemented is schematically shown. Figure 3 A rotor according to some embodiments of the present invention is schematically shown. Figure 4a -f schematically illustrates examples of magnet holders according to various embodiments of the present invention, and Figure 5 A magnet holder according to an embodiment of the present invention is illustrated schematically. Detailed Implementation

[0043] Figure 1 An exemplary heavy-duty vehicle 500 (e.g., a truck or bus) is schematically illustrated to illustrate the embodiments presented herein. However, the embodiments are not limited to those described herein. Figure 1 It can be used not only in the vehicles shown, but also in lighter vehicles (such as cars or other types of vehicles).

[0044] like Figure 1 The vehicle 500, schematically shown, includes a plurality of wheels, at least one pair of which are drive wheels 503, 504. Furthermore, the vehicle 500 includes a transmission system 502 configured to transmit torque between at least one power source (e.g., at least one electric motor 501, or a combination of a gas turbine engine and at least one electric motor 501) realizing so-called hybrid drive and at least one pair of drive wheels 503, 504. At least one electric motor 501 is powered by at least one battery 510 coupled to at least one electric motor 501 and is controlled by at least one control unit / device / system 511.

[0045] The torque provided by the power source can be supplied to at least one pair of drive wheels 503, 504 via a central gear (e.g., a conventional differential) and a drive shaft connected to the central gear. As those skilled in the art will understand, one or more motors 501 may also be arranged substantially anywhere in the vehicle 500, such as adjacent to one or more of the drive wheels 503, 504, as long as the torque generated is supplied to the drive wheels 503, 504.

[0046] The vehicle can be braked by utilizing motor 501 (i.e., by utilizing regenerative braking). The vehicle 500 may also include at least one braking device arranged at each of the wheels of the vehicle, wherein the at least one braking device may be included in the braking system.

[0047] The control unit / device / system 511 can be configured to control one or more of the following: one or more motors 501, at least one battery 510, a braking system, and other suitable systems and / or components of the vehicle 500. However, in Figure 1 The illustrations are merely schematic representations of the units / devices / entities of the vehicle that are useful for understanding the invention.

[0048] Figure 2 Motor 501 is schematically shown. Motor 501 includes a stationary stator 200 and a rotor 100 configured to rotate within the stator 200. The rotor 100 rotates by a radius R about a rotation axis 115. The rotation axis 115 is, in this document, a longitudinal axis passing through the center of the rotor 100 about which the rotor 100 rotates. The stator 200 and the rotor 100 are separated by an air gap 201.

[0049] When motor 501 is used as an electric motor, stator 200 provides a rotating magnetic field that drives rotor 100 to rotate. The rotating magnetic field in the air gap 201 between stator 200 and rotor 100 then provides torque that causes rotor to rotate. Conversely, when motor 501 is used as a generator, for example during regenerative braking, stator 200 converts the rotating magnetic field provided by rotor 100 via air gap 201 into electric current.

[0050] Figure 3 An end view (i.e., a view perpendicular to the axis of rotation 115) of a rotor 100 according to an embodiment of the invention is schematically shown. The rotor 100 includes a rotor hub 110, a plurality of magnets 130, and a plurality of magnet retainers 120. The plurality of magnet retainers 120 and thus the plurality of magnets 130 are arranged here around the rotor hub 110 as spokes of a wheel and have a radial orientation outward from the rotor hub 110. A rotor 100 configured in this way (i.e., a rotor 100 including a plurality of spoke-shaped magnets 130 and / or magnet retainers 120 arranged around the rotor hub 110) is generally referred to as a spoked rotor.

[0051] For a spoked rotor, a portion of the rotating magnetic flux / field leaks through the magnet holder 120 and through the rotor hub 110 instead of through the radially outer side of the rotor 100 (i.e., as shown in the image). Figure 2 The risk of air gap 201 (shown between rotor 100 and stator 200).

[0052] The rotation R of rotor 100 is driven by the magnetic field in the air gap 201 between rotor and stator 200, as mentioned above. Therefore, if some of the magnetic field leaks and passes through rotor hub 110 instead of through air gap 201, the rotational force / torque on rotor 100 is reduced.

[0053] Therefore, to reduce the portion of the magnetic field passing through the rotor hub 110, the rotor hub 110 includes a first material (i.e., at least partially produced from a first material), which, according to various embodiments, is at least partially low-magnetic or non-magnetic. A plurality of magnet holders 120 include a second material (i.e., at least partially produced from a second material), which is different from the first material of the rotor hub 110. According to embodiments, the second material of the magnet holders is at least partially ferromagnetic, such as iron or electrical steel.

[0054] The different first and second materials of the rotor hub 110 and the magnet retainer 120 may cause stability and / or integrity problems of the rotor 100, which are related to the lack of sufficient mechanical strength of the magnet retainer 120 and their attachment to the rotor hub 110.

[0055] according to Figure 3 In the schematic embodiment shown, a plurality of magnet holders 120, also referred to as rotor teeth, are attached to the rotor hub 110 around the rotation axis 115 of the rotor. According to the embodiment, the plurality of magnet holders 120 are attached to the outer periphery of the rotor hub 110 and are equidistantly spaced there around / around the rotation axis 115.

[0056] Multiple magnets 130 are also arranged around / around the axis of rotation 115. According to an embodiment, the magnets are also equidistantly spaced around / around the axis of rotation 115. Each of these magnets 130 is arranged between two adjacent magnet holders 120 and held in place by the two magnet holders 120. Thus, each magnet 130 is axially, radially, and tangentially secured to the rotor hub 110 by its two adjacent magnet holders 120 arranged therebetween. According to an embodiment, the two adjacent magnet holders 120 form slots / pockets corresponding to the size and shape of the magnets 130, in which the magnets 130 fit / are held in place. According to some embodiments, for example when the rotor is a spoked rotor, the multiple magnets are permanent magnets.

[0057] According to an embodiment, each magnet retainer 120 having a second material is attached to a rotor hub 110 having a first material via a connector 121. The connector 121 includes a male connector portion 122 of the magnet retainer 120 having the second material, which is mated / attached / pressed into a female connector portion 112 of the rotor hub 110 having the first material.

[0058] In this document, the male connector portion 122 of the magnet retainer 120 is the inner radial end portion of the magnet retainer, which is closed / enclosed / retained by the female connector portion 112 when it mates / engages / attaches with the female connector portion. The male connector portion 122 may also be defined as being radially inside the waist 126 of the inner radial end portion of the magnet retainer 120, such as... Figure 4a As shown schematically in the diagram.

[0059] According to an embodiment, the male connector portion 122 includes one or more cavities / recesses / gaps 125 confined within the male connector portion 122, such as Figure 3 As shown in the diagram. Therefore, each inner radial end portion of the magnet retainer 120 includes one or more cavities 125. These one or more cavities 125 are arranged on the magnet retainer 120 such that they will be closed / encapsulated within the connector 121 (i.e., within the female connector portion 112) when the magnet retainer 120 is attached / engaged / fitted to the rotor hub 110.

[0060] One or more cavities 125 in the male connector portion 122 provide slight elastic deformation and / or elasticity of the male connector portion 122. This significantly reduces the risk of breakage of the male connector portion 122, for example, at the waist 126.

[0061] In addition, such as Figure 3 As schematically shown, rotor 100 includes a plurality of magnets 130, in this non-limiting example 16 magnets 130 (possibly permanent magnets), which are equidistantly spaced around a rotation axis 115 in the circumferential direction and extend radially outward from rotor hub 110. In a cross-section perpendicular to the rotation axis 115, each magnet has a substantially rectangular shape. In the axial / longitudinal direction of rotor 100, magnets 130 extend from a first axial end to a second axial end, corresponding to an axial length L of rotor 100.

[0062] The rotor 100 also includes a plurality of magnet holders 120, 16 in this non-limiting example, which are substantially fan-shaped in cross-section perpendicular to the axis of rotation 115 and arranged between magnets 130 to extend radially outward from the rotor hub 110. Thus, the number of magnet holders 120 is as many as the number of magnets 130, and each magnet 130 is arranged circumferentially between two magnet holders 120. In the axial / longitudinal direction of the rotor 100, the magnet holders 120 extend from a first axial end to a second axial end, substantially corresponding to the axial length L of the rotor 100. The second material of the magnet holders 120 may be a suitable ferromagnetic material, such as electrical steel or iron, and the magnet holders 120 may be made / produced from stacks / laminated layers of ferromagnetic material. Alternatively, each magnet holder 120 may be made from a solid block of ferromagnetic material.

[0063] like Figure 3 As shown, any two adjacent magnet holders 120 are positioned / arranged such that a magnet 130 is positioned between them. Thus, each magnet 130 is sandwiched between two adjacent magnet holders 120, for example, in a slot / pocket formed by the magnet holders. According to an embodiment, each magnet 130 is glued to the two magnet holders 120 where the magnet 130 is positioned / sandwiched. Thus, the magnet 130 is securely held in place by the magnet holders 120.

[0064] According to an embodiment, the rotor hub 110 includes a centrally located base portion 111 (e.g., a shaft) having a magnetic or non-magnetic material. The rotor hub also includes a mating portion 113 disposed radially outward of the base portion / shaft 111 and having at least partially low magnetic or non-magnetic material. A female connector portion 112 of the rotor hub 110 is disposed in the outer surface of the mating portion 113.

[0065] pass Figure 3 The rotor 100, schematically illustrated, has multiple magnet retainers 120 securely attached to the rotor hub 110 via strong and flexible joints 121. Furthermore, multiple magnets 130 are securely attached to the magnet retainers 120, for example, by gluing them to the magnet retainers. Thus, the entire rotor 100 is used as a single, integral component, but it is constructed from multiple parts, possibly made of different materials. Moreover, the rotor 100 comprises very few parts because the various locating rings and other fastening devices required in conventional solutions are unnecessary for securely attaching the multiple magnet retainers 120 and the multiple magnets 130 to the rotor hub 110. Therefore, the improved mechanical strength and elasticity provided by one or more cavities 125 of the male connector portion 122 render such additional fastening devices redundant.

[0066] Figure 4a-f illustrates a magnet retainer 120 according to various embodiments. Each of these figures shows a cross-section of a magnet retainer 120, which is transverse / perpendicular to the rotor's axis of rotation 115. A male connector portion 122 is arranged at the inner radial end portion of the magnet retainer 120. As mentioned above, the male connector portion 122 will be received / closed / encapsulated within a connector 121 (i.e., within a female connector portion 112) when the magnet retainer 120 is attached / engaged / fitted to the rotor hub 110. One or more cavities / recesses / gaps 125 are confined within the male connector portion 122 of the magnet retainer 120.

[0067] According to an embodiment, two magnet holders 120 adjacent to the magnet 120 form a slot / bag in which the magnet is held in place. The slot / bag is formed here by a waist 126 at the male connector portion 122, an outer edge 117, and a sidewall 118 of each or both magnet holders 120, as shown below. Figure 4a As shown in the diagram. Therefore, the magnet 120 is held in place in the radial direction by the waist 126 and the outer edge 117 of the magnet holder 120, and in the tangential direction by the sidewall 118 of the magnet holder 120.

[0068] According to an embodiment, Figure 4a The male connector portion 122 shown in -f has a male dovetail shape 129 in its cross-section. As those skilled in the art will understand, the corresponding cross-section of the female connector portion 112 also has a corresponding female dovetail shape 119, such as... Figure 3 As shown in the diagram. Therefore, when the magnet holder 120 is attached to the rotor hub 110, the dovetail male connector portions 122, 129 are pressed into and received by the corresponding dovetail female connector portions 112, 119.

[0069] According to various embodiments, one or more cavities 125 mentioned above, confined within the dovetail-shaped male connector portions 122, 129, may include at least one surface cavity 125a disposed on the surface 127 of the male connector portions 122, 129. Some non-limiting examples of such surface cavities 125a are described below. Figure 4a -e schematically shows a cross-sectional view of the magnet holder 120 and its male connector portion 122. There can be substantially any number of surface cavities 125a, and they can have substantially any cross-sectional shape. As a non-limiting example, Figure 4a Three surface cavities 125a with a partially triangular shape in cross section are shown. Figure 4b Three surface cavities 125a with a partially rectangular shape in cross-section are shown. Figure 4c Two surface cavities 125a with a substantially finger-like shape in cross-section are shown. Figure 4d Three surface cavities 125a with a partially circular shape are shown. Figure 4e Two surface cavities 125a with a lobed channel form (e.g., partially asymmetrical U-shaped or partially asymmetrical V-shaped) are shown.

[0070] According to various embodiments, the one or more cavities 125 mentioned above, confined within the dovetail-shaped male connector portions 122, 129, may further include at least one confined cavity 125b within the surface of the male connector portion 122. Thus, in a section perpendicular to the axis of rotation 115, at least one cavity 125 may include at least one closed gap (i.e., hole) of the body 128 of the male connector portion 122. Essentially any number and essentially any form of confined cavity 125b can be arranged in the male connector portion 122. As a non-limiting example, Figure 4e A circular hole / cavity 125b is disclosed in the cross-section of the male connector portion 122 of the magnet holder 120. Figure 4f A confined cavity 125b, in the form of an irregular polygon (demonstrated here as a trapezoid), is shown in the cross-section of the male connector portion 122. As shown... Figure 4e As demonstrated, at least one surface cavity 125a and at least one confined cavity 125b can be arranged in a male connector portion 122.

[0071] Figure 5 A schematic side view of the magnet retainer 120 is shown. According to an embodiment, one or more cavities 125 described herein extend along a rotation axis 115 (i.e., in the same direction as the rotation axis) from a first axial end 123 of the male connector portion 122 to a second axial end 124 of the male connector portion 122. Thus, the male connector portion 122 extends along the entire axial length L of the magnet retainer 120, which generally corresponds substantially to the axial length of the rotor 100, and one or more cavities 125 also pass through / extend along this entire length L.

[0072] According to an embodiment, one or more cavities 125 (e.g., at least one surface cavity 125a and / or at least one confined cavity 125b) contain no solid material, i.e., lack solid material. The one or more cavities 125 are thus arranged to be elastically contractible. This makes it possible for the male connector portion 122 to elastically contract under pressure / force from its external / surroundings, i.e., to elastically change / reshape into a smaller volume.

[0073] According to an embodiment, at least one of the cavities 125 may be filled with air, making it possible to provide controlled and predictable reshaping of the cavity.

[0074] According to an embodiment, at least one of the one or more cavities 125 may be arranged to guide / retain coolant, such that coolant can be delivered from the first axial end 123 of the male connector portion 122 to the second axial end 124 of the male connector portion 122. Therefore, one or more cavities 125 can be used to cool the rotor 100.

[0075] exist Figure 3 , Figure 4a -f and Figure 5 In the diagram, connector 121, its male connector portion 122, and its female connector portion 112 are shown as dovetail-shaped connectors. However, according to an embodiment, the male connector portion 122 has a partially circular male cross-section, wherein this cross-section is transverse / perpendicular to the rotor's axis of rotation 115. The female connector portion 112 then has a corresponding partially circular female cross-section, such that the male connector portion 122 mates with the female connector portion 112.

[0076] The embodiments described herein are generally applicable to virtually any type of male and female connector, wherein the dovetail and circular forms mentioned herein are merely two non-limiting examples. Thus, one or more cavities described herein can be confined within the male connector portion 122 of the magnet retainer 120, wherein the male connector portion 122 can have virtually any form and / or shape to mate with a correspondingly shaped female connector portion 112.

[0077] According to various embodiments, the magnet holder 120 may comprise two or more stacked / laminated axial layers and / or two or more stacked / laminated radial layers of ferromagnetic material. Alternatively, the magnet holder 120 may be made of a solid block of ferromagnetic material.

[0078] Furthermore, according to an embodiment, the magnet retainer 120 may include two or more circumferential portions in a cross section perpendicular to the rotation axis 115. For example, the magnet retainer 120 may include two mirror-image circumferential portions in a cross section, configured such that when both portions are attached to the rotor hub 110, the two portions together form the magnet retainer 120. As a non-limiting example, according to this embodiment, such as Figure 4a The magnet holder 120 shown can be vertically divided in the middle into a left part and a right part, which are mirror versions of each other.

[0079] According to an embodiment, the male connector portion 122 is attached to the female connector portion 112 via an interference fit. Therefore, the magnet retainer 120 is attached to the rotor hub 110 via an interference fit of the connector 121, such that the magnet retainer 120 and thus the magnet 130 are securely attached to the rotor hub 110. In some embodiments, it may be utilized here to cool the male connector portion 122 before insertion into the female connector portion 112 to reduce the size of the male connector portion.

[0080] When the male connector portion 122 is mated / forced into the female connector portion 112, one or more cavities 125 confined within the male connector portion 122 are arranged to provide elastic deformation of the male connector portion 122 upon insertion into the female connector portion 112. Therefore, due to the one or more cavities 125, the male connector portion 122 elastically deforms, i.e., deforms to the point that it can return to its initial form / shape. Thus, the male connector portion 122 is held very tightly within the female connector portion 112 after insertion, and the mechanical strength of both the connector 121 and the male connector portion 122 is improved.

[0081] When the rotor 100 is rotating, i.e., when the rotor 100 is in use, one or more cavities 125 confined in the male connector portion 122 are arranged to provide a spring function between the male connector portion 122 and the female connector portion 112. This spring function during rotor 100 rotation is caused by the compression and release of one or more cavities 125 when the magnet retainer 120 is subjected to tangential force, causing the male connector portion 122 to elastically change its form / shape according to the compression and release of the cavities 125. The male connector portion 122, and therefore the magnet retainer 120, is thus arranged to be elastic, thereby significantly reducing the risk of breakage or becoming loosened of the male connector portion 122 and / or the rest of the magnet retainer 120. This ensures that the magnet 130 is always tightly held in place by its adjacent magnet retainer 120, and ensures that there is no gap between the magnet retainer 120 and the magnet 130.

[0082] This invention is not limited to the embodiments described above. Instead, this invention relates to and covers all different embodiments included within the scope of the independent claims.

Claims

1. A rotor (100), comprising: - Rotor hub (110) of the first material; - A plurality of magnet holders (120) of a second material, which is different from the first material, and the plurality of magnet holders (120) are attached to the rotor hub (110) about the rotation axis (115) of the rotor. - A plurality of magnets (130) arranged around the axis of rotation (115), wherein each magnet (130) is arranged between two magnet holders (120) and held in place by the two magnet holders (120); in - Each magnet retainer (120) is attached to the rotor hub (110) via a connector (121), the connector (121) including a male connector portion (122) of the magnet retainer (120) that mates with a female connector portion (112) of the rotor hub (110); and - The male connector portion (122) includes one or more cavities (125) confined within the male connector portion (122).

2. The rotor (100) according to claim 1, wherein the one or more cavities (125) are free of solid material and are arranged to be elastically retractable.

3. The rotor (100) according to any one of claims 1-2, wherein the one or more cavities (125) comprise one or more of the following: - At least one surface cavity (125a) of the male connector portion; and - At least one confined cavity (125b) inside the surface of the male connector portion (122).

4. The rotor (100) according to any one of claims 1-3, wherein the one or more cavities (125) extend along the rotation axis (115) from a first axial end (123) of the male connector portion (122) to a second axial end (124) of the male connector portion (122).

5. The rotor (100) according to claim 4, wherein at least one of the one or more cavities (125) guides coolant from the first axial end (123) to the second axial end (124).

6. The rotor (100) according to any one of claims 1-4, wherein at least one of the one or more cavities (125) is filled with air.

7. The rotor (100) according to any one of claims 1-6, wherein - The cross section perpendicular to the axis of rotation (115) of the male connector portion (122) has a male dovetail shape (129); and - The cross section perpendicular to the axis of rotation (115) of the female connector portion (112) has a female dovetail shape (119).

8. The rotor (100) according to any one of claims 1-6, wherein - The cross-section perpendicular to the axis of rotation (115) of the male connector portion (122) has a partially circular male form; and - The cross section of the female connector portion (112) perpendicular to the axis of rotation (115) has a partially circular female shape.

9. The rotor (100) according to any one of claims 1-8, wherein the male connector portion (122) is attached to the female connector portion (112) by an interference fit.

10. The rotor (100) according to any one of claims 1-9, wherein the one or more cavities (125) are arranged to provide one or more of the following: - The elastic deformation of the male connector portion (122) when it is inserted into the female connector portion (112); and - The spring function between the male connector portion (122) and the female connector portion (112) when the rotor (100) is rotating in the positive direction.

11. The rotor (100) according to any one of claims 1-10, wherein - The first material is at least partially low magnetic or non-magnetic; and - The second material is at least partially ferromagnetic.

12. The rotor (100) according to any one of claims 1-11, wherein - The rotor (100) is a spoked rotor; and - The magnet (130) is a permanent magnet.

13. The rotor (100) according to any one of claims 1-12, wherein each magnet (130) is glued to the two magnet holders (120) arranged therebetween.

14. An electric motor (501), comprising: - Stator (200); as well as - The rotor (100) according to any one of claims 1-13 is arranged radially inside the stator (200).

15. A vehicle (500) comprising an electric motor (501) according to claim 14.

Images