Electromagnetic motor having surface magnets

Abstract

The invention relates to an electromagnetic motor (1) comprising an inner rotor (2) and an outer rotor (2a) which are concentric to a central axis of rotation (3), wherein the rotors (2, 2a) interpose between them a stator (10) with an air gap (14, 14a) between the stator (10) and each rotor (2, 2a). Each rotor (2, 2a) is provided with a magnetic circuit (8) for circulating magnetic flux opposite a respective air gap (14, 14a) and carries magnets (6). For the inner and outer rotors (2, 2a), the magnets are surface magnets (6) positioned in or on the associated magnetic circuit (8) flush with the magnetic circuit (8) towards the respective air gap (14, 14a).

Description

[0001] DESCRIPTION

[0002] Title: Electromagnetic motor with surface magnets

[0003] The invention relates to an electromagnetic motor for driving a member at least partially surrounding it, in particular by integrating it into its interior, or by being attached to the motor, this motor having surface magnets.

[0004] In a non-limiting embodiment of the present invention, the motor may be housed in a wheel of a vehicle for the propulsion of said vehicle, thereby forming what is called a wheel motor. In the case of a vehicle with several wheels, such a motor may be located in each wheel of the vehicle.

[0005] Such a motor for driving a component is particularly suitable for low speed and high torque applications in a restricted space requirement of a substantially discoid shape.

[0006] To do this, it is known to use an electromagnetic motor comprising a rotor carrying permanent magnets and a stator carrying windings, the stator and the rotor delimiting an air gap between them.

[0007] Such a single-air-gap motor, although of reduced size which is favorable to its installation in a component to be driven, has the major disadvantage of not delivering a high torque.

[0008] Document FR 2 881 290 A1 describes an electric wheel or wheel motor comprising a motor incorporated in a wheel for its drive. The motor comprises a stator and a rotor connected to a torque transmission system in order to transmit torque to the wheel.

[0009] In one embodiment, the rotor has two rotors or field generators each delimiting with the stator an air gap, each rotor comprising magnets with poles magnetized in a radial direction relative to an axis of rotation of the motor and magnetized yoke magnets each of which is placed between two adjacent pole magnets to strengthen the magnetic field formed by the pole magnets.

[0010] The presence of cylinder head magnets, however, reduces the space allocated to the pole magnets in the necessarily reduced size of the engine.

[0011] Documents CN 113 612 362 A and EP 1 102 385 A2 describe an electromagnetic motor comprising an internal rotor and an external rotor concentric with respect to a central axis of rotation, the rotors interposing between them a stator with an air gap between the stator and each rotor.

[0012] Each rotor is provided with a magnetic circuit for circulating magnetic flux opposite a respective air gap and carrying surface magnets for the inner and outer rotors, the surface magnets being positioned in or on the associated magnetic circuit. In these documents, firstly, the surface magnets are compact magnets, which is disadvantageous for the reduction of eddy currents and for the energy dissipation created during their use. Secondly, the surface magnets do not protrude from the magnetic circuit towards the respective air gap, which does not allow them to deliver a maximum magnetic field, the magnetic field delivered by such surface magnets flush with the magnetic circuit being similar to the magnetic field delivered by buried magnets.

[0013] Document JP 2016093052 A discloses an electric motor with first and second rotors. The first and second rotors have a first magnet that applies an electromagnetic force independent of the magnetic field without forming a magnetic circuit.

[0014] No magnet described in this document is a surface magnet positioned to protrude from any magnetic circuit.

[0015] Document US 11,128,186 B2, belonging to the applicant, shows an electromagnetic motor or generator comprising at least one rotor and at least one stator. The or each rotor comprises permanent magnets rotating around a central shaft in the form of magnet structures forming magnet poles, each magnet structure being composed of a plurality of pixelated unit magnets.

[0016] In this document, none of the magnet structures protrude from a magnetic circuit towards the air gap between stator and rotor, being able to be similar to a surface magnet.

[0017] The problem underlying the present invention is to design an electromagnetic motor intended for driving a member delivering increased power density while remaining as compact as possible by a significant increase in the magnetic exchange surfaces compared to a motor according to the state of the art.

[0018] To this end, the present invention relates to an electromagnetic motor comprising an inner rotor and an outer rotor concentric with respect to a central axis of rotation, the rotors interposing between them a stator with an air gap between the stator and each rotor, each rotor being provided with a magnetic circuit for circulating magnetic flux opposite a respective air gap and carrying surface magnets for the inner and outer rotors, the surface magnets being positioned in or on the associated magnetic circuit, characterized in that the surface magnets protrude from the magnetic circuit towards the respective air gap, each surface magnet being segmented in at least two directions into a multitude of at least fifty pixelated unit magnets.

[0019] By surface magnet in the context of the present invention, it is understood magnets protruding at least partially from the magnetic circuit. These surface magnets can be secured to the magnetic circuit by any means, in particular by gluing without penetrating into the magnetic circuit. In the context of the present invention, these surface magnets can be semi-buried in the magnetic circuit until they only protrude slightly from the magnetic circuit, therefore not completely buried on all sides by the magnetic circuit.

[0020] Such a motor makes it possible to achieve a high volume torque in a reduced size, by better use of the allocated volume, hence a better power density. The use of surface magnets makes it possible to increase the useful magnet volume necessary for creating torque.

[0021] In order to obtain a high volume torque, current densities of between 15 and 20 A / mm are allowed to be reached. 2 . Such a motor also makes it possible to achieve a low air gap value, around 0.8 millimeters or less. When a motor has a high number of pole pairs, its architecture generally has a large internal bore diameter, a consequence of a large air gap diameter conducive to the creation of torque. This observation is valid whether the motor has an internal or external rotor.

[0022] A solution to be able to gain even more torque is to use this internal volume by switching to a double air gap architecture with a stator and two rotors, which is what the present invention recommends, with rotors equipped with surface magnets.

[0023] By allowing the electromagnetic exchange surface to be increased by positioning, for example, both an internal rotor around an internal axis and an external rotor on the periphery, we have the equivalent of "two motors in one". This makes it possible to increase the torque of the motor in the given space.

[0024] Surface magnets deliver a stronger magnetic field than buried magnets.

[0025] Advantageously, the unit magnets are in the form of elongated pads with a circular, cylindrical or polygonal or ovoid section, the pads extending partially into a thickness of the associated rotor.

[0026] The pixelated unit magnets are therefore in the form of elongated studs or rods of small section compared to segmented bar magnets. Their semi-buried portions extend according to the thickness of the rotor.

[0027] A large magnet is subject to greater eddy current losses than its equivalent in small or micro-magnets. The use of small or micro-magnets therefore makes it possible to reduce these losses which are detrimental to the operation of the rotor.

[0028] Therefore, in each rotor, the current losses of

[0029] Foucault forces in magnets have been significantly reduced by proposing ironless rotors or by proposing magnet poles consisting of a plurality of small unit magnets.

[0030] Considering a unit magnet as an elementary element in the form of a stud or rod, the ideal shape of this stud is a symmetrical ellipsoid of revolution also called an ovoid shape, approximately a flattened sphere, which due to its topology is difficult to demagnetize because its magnetic field relative to the magnetization is shapeless. There is no rotating field in the corners.

[0031] From this observation, it is advantageous to constitute a mesh of unit magnets which individually come as close as possible to the ellipsoid of revolution.

[0032] Several embodiments are possible and the ovoid shape of the unit magnet can be more or less perfect by having a convex rounded end portion at one longitudinal end or at both longitudinal ends.

[0033] A relatively perfect ovoid shape with two convex longitudinal ends is optimal but difficult to achieve by machining. On the other hand, it is the ideal shape to combat demagnetization of the unit magnet.

[0034] Alternatively, a unit magnet based on a poly-facet structure with a first portion called a body with longitudinal facets and at least one end portion with inclined facets whose angles are between 0 and 45° can also be envisaged, making it possible to increase the magnetic field relative to the magnetization while retaining significant active faces at the ends of the unit magnets in the form of pads. Between these two embodiments, many other shapes more or less approaching an ovoid shape are also possible.

[0035] Advantageously, a number of magnet poles on the inner rotor is equal to a number of magnet poles on the outer rotor.

[0036] This represents a simplification of the motor architecture, in order to seek to maximize the volume torque but also the mass torque by notably greatly simplifying the architecture of the stator winding and by extension the compactness of the stator.

[0037] This can also allow the two rotors to operate together in a dependent manner, which has the advantage at a given torque of reducing the difference in diameter between the external and internal diameter.

[0038] Advantageously, each surface magnet carried by the inner rotor is directly opposite a surface magnet of the same polarity carried by the outer rotor. This allows synchronous operation of the motor and maximizes the magnetic flux.

[0039] Advantageously, each surface magnet carried by the internal rotor is offset in electrical degrees by 1 to 30° relative to a surface magnet of the same polarity carried by the external rotor.

[0040] In the case of the presence of a so-called reluctant torque, for example for surface magnets of the semi-buried type in the magnetic circuit while being flush with the magnetic circuit towards the air gap, a slight offset between the rotors can make it possible to maximize the torque. Advantageously, the stator comprises an armature core carrying teeth having flanges at each of their longitudinal ends oriented towards a respective rotor, two adjacent teeth leaving between them a notch for a winding, the notch being narrowed by the flanges of the two adjacent teeth at each of their longitudinal ends.

[0041] Advantageously, the motor comprises at least one hoop circumferentially covering the magnets of the internal rotor.

[0042] Advantageously, the masses of the magnets of the inner and outer rotors are respectively selected relative to each other so that the inner and outer rotors achieve an equivalent induction level. An equivalent induction level is a necessary condition for the correct dimensioning of the magnetic circuit of a motor in general.

[0043] Advantageously, the motor is radial flux, the external and internal rotors being respectively in the form of a crown perpendicular to the axis of rotation, each crown being extended by a cylindrical portion connected to the external edge of the crown and extending at a distance along the axis of rotation.

[0044] Advantageously, the rotors are mechanically connected to each other by a connecting piece relative to the plane orthogonal to the axis of rotation.

[0045] From a theoretical point of view, a mechanical connection by connecting piece is not necessary but in practice it greatly simplifies the stability of the motor by making it impossible for a rotor to come loose.

[0046] The invention also relates to a member driven by such a motor, the member being arranged externally to the motor, at least partially surrounding it or being placed against the motor. Advantageously, the member is a wheel driven in rotation by said motor, the wheel housing the motor inside it.

[0047] The invention finally relates to a means of transport comprising at least one such member in the form of a wheel driven in rotation by said motor, the means of transport having a means of suspending the wheel while leaving the wheel free to rotate.

[0048] The accompanying drawings illustrate the invention:

[0049] [ Fig 1 ] represents a radial sectional view of a portion of an electromagnetic motor with a stator interposed between two rotors carrying surface magnets according to an embodiment of the present invention,

[0050] [ Fig 2 ] represents a perspective view of the inner and outer rotors carrying surface magnets according to an embodiment of the present invention,

[0051] [ Fig 3 ] represents a curve of total magnetic torque delivered by an electromagnetic motor according to the present invention,

[0052] [ Fig 4 ] represents a surface magnet segmented into several longitudinal bars each forming a unit magnet, such surface magnets being able to be carried by each rotor of an electromagnetic motor according to the present invention,

[0053] [ Fig 5 ] represents a surface magnet segmented into several lateral bars each forming a unit magnet, such surface magnets being able to be carried by each rotor of an electromagnetic motor according to the present invention,

[0054] [ Fig 6 ] represents a surface magnet pixelated into several small unit magnets in the form of square section pads, such surface magnets being able to be carried by each rotor of an electromagnetic motor according to the present invention,

[0055] [Fig 7] represents a surface magnet pixelated into several small unit magnets in the form of hexagonal cross-section pads, such surface magnets being able to be carried by each rotor of an electromagnetic motor according to the present invention, [Fig 8] represents a sectional view of a wheel rim comprising an electromagnetic motor according to the present invention, [Fig 9] represents a bottom view of a means of transport comprising four wheels, each of the wheels being provided with an electromagnetic motor according to the present invention.

[0056] In the following, reference is made to all figures taken in combination. When reference is made to a specific figure, this figure is to be taken in combination with the other figures for the recognition of the designated reference numerals. In the figures, when present, only one magnet or magnet pole and only one small unit magnet forming part of a magnet forming a magnet pole are referenced but what is stated respectively for the magnet forming a pole and the unit magnet is valid respectively for all the magnets forming a pole and all the unit magnets. The same applies in Figure 1 to the stator elements which are referenced only for a single element of the same type.

[0057] Referring to all the figures and in particular firstly to figures 1, 2 and 8, the invention relates to a drive motor 1 which is intended to be associated with a member 15 to be driven by being housed at least partially in the member 15 or by being placed against the member 15.

[0058] The motor 1 comprises an inner rotor 2 and an outer rotor 2a concentric with respect to a central axis of rotation 3, the rotors 2, 2a interposing between them a stator 10 with an air gap 14, 14a between the stator 10 and each rotor 2, 2a. Each rotor 2, 2a is provided with a magnetic circuit 8 for circulating magnetic flux opposite a respective air gap 14, 14a and carrying magnets 6.

[0059] According to the invention, for the inner and outer rotors 2, 2a, the magnets 6 are surface magnets positioned in or on the associated magnetic circuit 8, flush with the magnetic circuit 8 towards the respective air gap 14, 14a.

[0060] For a first type of surface magnet 6, the magnet 6 is positioned on the magnetic circuit 8 of the associated rotor without the presence of a housing to receive it, therefore glued to the magnetic circuit 8.

[0061] A second type of surface magnet groups together magnets 6 partially inserted into a housing but protruding at least slightly from their housing, these magnets being described as semi-buried magnets.

[0062] These semi-buried or embedded magnets 6 have the advantage of adding a reluctant torque that can be used to limit the magnet volume or the current intensity at a given torque. The theoretical gains should, however, be put into perspective because of the potential leaks between the magnets, which are then greater.

[0063] The advantages of a surface magnet 6 of the first or second type are an optimal use of the magnet 6 for the creation of torque to the internal and external rotors 2, 2a and a limitation of the inter-magnet leakage flux. As can be seen in particular in Figures 1 and 2, in an optional embodiment of the present invention, the magnets 6 of the same polarity can be positioned facing each other.

[0064] A number of magnet poles 6 on the inner rotor 2 can be equal to a number of magnet poles 6 on the outer rotor 2a. In this configuration, the field lines therefore cross both rotors 2, 2a.

[0065] The advantage of this solution is to avoid adding a loop of the field lines in slots 12 of the stator 10 containing the winding, which would reduce the space available for the winding windings. However, in this case, the inner and outer rotors 2, 2a of the motor 1 operate in a manner dependent on each other, which reduces the degrees of freedom during design.

[0066] In another optional embodiment, adding an angle between the two rotors 2, 2a may be of interest in reducing the torque ripple or in using a resulting torque.

[0067] Thus, each surface magnet 6 carried by the internal rotor 2 can be offset in electrical degrees by 1 to 30° relative to a surface magnet 6 of the same polarity carried by the external rotor 2a.

[0068] Similarly, an architectural asymmetry between the two rotors 2, 2a can be advantageous.

[0069] Masses of the magnets 6 of the inner and outer rotors 2, 2a may be selected respectively relative to each other so that the inner and outer rotors 2, 2a achieve an equivalent induction level. With regard to the stator 10, the stator 10 may be without a yoke and be made up of teeth 11 which may have flanges 13, also called isthmuses, at each of the longitudinal ends of the teeth 11. The teeth 11 may be carried by an armature core, a notch 12 being interposed between two adjacent teeth 11 to receive a winding.

[0070] The flux looping then takes place in a magnetic circuit 8 present in each of the rotors 2, 2a. In order not to penalize the creation of torque between the two rotors 2, 2a, the notch depth 12 can be significantly increased compared to a single air gap structure, in order to increase the number of turns. Each notch 12 left between two adjacent teeth 11 can be narrowed laterally by the collars 13 of the two adjacent teeth 11 at each of their longitudinal ends.

[0071] Without this being limiting, for purely illustrative purposes, motor 1 can have 28 pairs of poles and 84 slots.

[0072] It can be estimated that the external rotor 2a participates in the creation of the total torque in a proportion of approximately two thirds when the internal rotor 2 only participates in one third.

[0073] The difference in radius between the two rotors 2, 2a has a direct impact on the torque but also on the quantity of magnets if we want to keep a similar thickness. From a magnetic point of view, we reach in a tooth 11 inductions of the order of 2.1 Tesla, which is at the limit. A close induction level between the internal and external rotors 2, 2a may be desired to have an optimal power density.

[0074] Figure 3 shows the total electromagnetic torque referenced C mag t and measured in Newton, meter or N / m as a function of time. In this figure, a high torque ripple of the order of 25% can be observed. The current density can reach 18 A / mm 2. While it is possible to achieve this current density at peaks with water cooling, continuous operation may require oil cooling. The rationale for cooling will also depend on the thermal time constant of motor 1 and the actual temperature rise in the coil windings during the operating time.

[0075] Such an engine 1 can have an active parts mass estimated at almost 70 kg, which implies a relatively low power density despite the high torque.

[0076] The dual rotor architecture of the motor 1 according to the present invention has made it possible, with the help of an increase in current density, to increase the torque value.

[0077] Referring in particular to Figures 4 to 6, the magnets 6 may be segmented or pixelated.

[0078] Indeed, it has been found that, for a motor 1 according to the present invention with the previously mentioned characteristics seeking the highest possible volume torque and / or mass torque for rotation speeds of the order of 1,500 rotations per minute, the losses could remain high.

[0079] In addition, the high compactness of the motors 1 makes the extraction of losses a real challenge, beyond performance considerations. Among all the loss items, the most difficult to evacuate are those present at each rotor 2, 2a, linked to the rotary movement of the latter. It is thus optionally sought to reduce one of the main loss items in the motor 1 linked to the magnets 6.

[0080] Due to the non-zero electrical conductivity of the ferromagnetic materials constituting the magnets 6, these are subject to the presence of eddy currents, sources of losses which are all the more significant as the field passing through them is strong.

[0081] To reduce the presence of these circulating currents, the objective was to reduce the average conductivity of the medium without having too strong an impact on the magnetic properties of the material.

[0082] A first solution involves segmenting the magnets 6 into multiple bars 7. These bars 7 are spaced from each other by the presence of an electrically insulating material, for example a non-conductive varnish. This process makes it possible to drastically reduce the formation of circulating currents without excessively deteriorating the magnetic performance.

[0083] Bars 7 extending longitudinally in the magnet 6 forming unit magnets 7 are shown in Figure 4 while Figure 5 shows bars 7 extending in the lateral direction of the magnet. These bars 7 may advantageously be of parallelepiped shape.

[0084] In Figures 4 and 5, it is visible that a large magnet intended to become a surface magnet 6 can be cut into more than five unit magnets 7 for longitudinal bars and into more than twenty unit magnets 7 for lateral bars.

[0085] In case this solution is not sufficient, it is possible to go further with pixelization. According to this technique, the magnets 6 will be segmented in two directions following rules similar to that of the tiling of the regular plane in the plane orthogonal to the direction of the flux or to the direction of polarization of the magnets 6.

[0086] Conventional patterns used for pixelation may be square, rectangular, cylindrical, or polygonal, including hexagonal or ovoid. The unit magnets 7 in this configuration may be in the form of elongated studs or rods. The unit magnets 7 may extend lengthwise within the thickness of a large magnet or a magnet structure formed by a grouping of the unit magnets 7 secured to each other.

[0087] Thus, a large magnet intended to become a surface magnet 6 can be cut into a multitude of unit magnets 7 much smaller than bars. In Figures 6 and 7, more than fifty unit magnets 7 are shown as part of a single surface magnet 6. The surface magnets 6 can be cut by laser. A layer of insulating and adhesive varnish or an insulating composite resin can be inserted between the unit magnets 7.

[0088] However, to hold the unit magnets 7 relative to each other before bonding, it may be advantageous to leave in the cut surface magnet 6 a heel which joins all the unit magnets 7 together. Such a heel may have a zigzag shape, that is to say be non-planar by extending over several successive planes, which has been shown to reduce the eddy currents created by a similar but planar heel.

[0089] Particularly in the case of segmented or pixelated surface magnets 6, as the inner and outer rotors 2, 2a can rotate at high speed and be subjected to a high centrifugal force, the motor 1 can comprise at least one hoop circumferentially covering the magnets 6 of the inner rotor 2. For the outer rotor 2a, it is the casing of the motor 1 which can serve as a hoop but it is also possible to provide a hoop for the outer rotor 2a.

[0090] As shown in Figure 1, the electromagnetic motor 1 according to the present invention may be radial flux. However, the present invention is not limited to a radial flux motor.

[0091] In this case, the external and internal rotors 2, 2a may respectively be in the form of a crown 9 perpendicular to the axis of rotation 3, each crown 9 being extended by a cylindrical portion 9a connected to the external edge of the crown 9 and extending at a distance along the axis of rotation 3. The references relate to the crown 9 and the cylindrical portion 9a of the external rotor 2a but the internal rotor 2 has the same configuration.

[0092] The rotors 2, 2a may be mechanically connected to each other by a connecting piece. This piece may be offset from the plane orthogonal to the axis of rotation 3.

[0093] As shown in Figure 8, the invention also relates to a member 15 driven by an electromagnetic motor 1 as previously described. A connecting piece ensures torque transmission between the electromagnetic motor 1 and the driven member 15. The driven member 15 is in this Figure 8 a wheel rim 15. The member 15 can be arranged external to the motor 1 by at least partially enveloping it, which is the case for a wheel motor for which the motor 1 is entirely or mostly integrated in the wheel. Alternatively, the member 15 can be attached to the electromagnetic motor 1 by being secured to one of the sides of the motor 1.

[0094] In the non-limiting case of a wheel motor, a common name for a wheel comprising an electromagnetic motor 1 inside it for its drive, the wheel motor can be part of a means of transport 17 by being associated with one or more other wheel motors, the means of transport 17 having a means of suspending the wheel motor while leaving it free to rotate.

[0095] As shown in Figure 9, the means of transport 17 may comprise a battery 21, advantageously high voltage, supplying the wheel motor(s), the wheel motor also being able to serve as a generator for recharging the battery 21. This is valid for an electromagnetic motor 1 according to the present invention which can also serve as a generator.

[0096] The electromagnetic motor(s) 1 present in the wheel(s) 16 can be controlled by an electronic unit 18 for controlling the means of transport.

Claims

DEMANDS 1) An electromagnetic motor (1) comprising an internal rotor (2) and an external rotor (2a) concentric with respect to a central axis of rotation (3), the rotors (2, 2a) interposing between them a stator (10) with an air gap (14, 14a) between the stator (10) and each rotor (2, 2a), each rotor (2, 2a) being provided with a magnetic circuit (8) for circulating magnetic flux opposite a respective air gap (14, 14a) and carrying surface magnets (6) for the internal and external rotors (2, 2a), the surface magnets (6) being positioned in or on the magnetic circuit (8), characterized in that the surface magnets (6) extend from the magnetic circuit (8) towards the respective air gap (14, 14a), each surface magnet (6) being segmented in at least two directions into a multitude of at least fifty individual pixelated magnets (7). 2) Motor (1) according to the preceding claim, in which the unit magnets (7) are in the form of pads with circular, cylindrical, polygonal or ovoid cross-section, the pads extending partially into a thickness of the associated rotor. 3) Motor (1) according to the preceding claim, in which a number of magnet poles (6) on the internal rotor (2) is equal to a number of magnet poles (6) on the external rotor (2a). 4) Motor (1) according to claim 3, in which each surface magnet (6) carried by the internal rotor (2) is directly opposite a magnet surface magnet (6) of the same polarity carried by the external rotor (2a). ) Motor (1) according to claim 3, in which each surface magnet (6) carried by the internal rotor (2) is offset in electrical degrees from 1 to 30° with respect to a surface magnet (6) of the same polarity carried by the external rotor (2a). ) Motor (1) according to any one of the preceding claims, in which the stator (10) comprises an armature core carrying teeth (11) having flanges (13) at each of their longitudinal ends oriented towards a respective rotor (2, 2a), two adjacent teeth (11) leaving between them a notch (12) for a winding, the notch (12) being narrowed by the flanges (13) of the two teeth (11) adjacent at each of their longitudinal ends. ) Motor (1) according to any one of the preceding claims, wherein the motor (1) comprises at least one ring circumferentially covering the magnets (6) of the internal rotor (2).) Motor (1) according to any one of the preceding claims, wherein the masses of the magnets (6) of the internal and external rotors (2, 2a) are respectively selected relative to each other so that the internal and external rotors (2, 2a) achieve an equivalent level of induction. ) Motor (1) according to any one of the preceding claims, wherein the motor (1) is radial flux, the external and internal rotors (2, 2a) being respectively in the form of a ring (9) perpendicular to the axis of rotation (3), each ring (9) being extended by a portion. cylindrical (9a) connected to the outer edge of the crown (9) and extending at a distance along the axis of rotation (3). 10) Motor (1) according to any one of the preceding claims, wherein the rotors (2, 2a) are mechanically linked to each other by a connecting piece with respect to the plane orthogonal to the axis of rotation (3). 11) Component (15) characterized in that it is driven by a motor (1) according to any one of the preceding claims, the component (15) being disposed externally to the motor (1) by at least partially enveloping it or by being attached to the motor (1) • 12) Component (15) according to the preceding claim, which is a wheel (16) driven in rotation by said motor (1), the wheel (16) housing the motor (1) inside it. 13) Means of transport (17), characterized in that it comprises at least one component (15) in the form of a wheel (16) driven in rotation by said motor (1) according to the preceding claim, the means of transport having a means of suspending the wheel (16) leaving the wheel (16) free to rotate.

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