Rotor for electromagnetic motor with two-part magnet structure

Abstract

The rotor (1) of an electromagnetic motor has a body (25a, 25b) with an internal hub (2) concentric with a central axis of rotation (7). Branches (3) extend radially from the internal hub (2) toward frets (8) that form the outer periphery of the rotor (1). A magnetic structure (10) is housed between two adjacent branches (3), and takes the form of two substructures (11, 12), an inner and an outer, extending radially between the two branches (3). When the rotor (1) is not rotating, the innermost surface of the inner substructure (11) is in at least partial contact with the internal hub (2), and the side surfaces facing one of the two branches (3) mechanically engage the opposing portions of the branches (13, 14), providing axial stop and free radial movement. The outermost surface of the outer substructure (12) faces the frets (8) relative to the rotor (1).

Description

[Technical Field]

[0001] The present invention relates to a rotor for an axial flux electromagnetic motor or generator having an advantageously enlarged hub from which branches extend, with a two-part magnet structure between two adjacent branches.

[0002] The invention further relates to an electromagnetic motor or generator equipped with a rotor of this type. [Background technology]

[0003] The present invention has advantageous, but not exclusive, application to electromagnetic motors in which the rotor rotates at high speeds and provides high power output, achieved by the particular properties of the rotor according to the invention. This type of motor can be used, for example, as the electromagnetic motor in a fully electric or hybrid vehicle.

[0004] Advantageously, but not exclusively, the electromagnetic motor or generator may include at least one rotor framed by two stators, whereby these elements are superimposed on one another and separated by at least one air gap on the same shaft.

[0005] In high speed applications, the rotating part, i.e. the rotor, needs to have very high mechanical strength to improve the reliability of the system.

[0006] In the case of an axial flux electromagnetic machine, the rotor comprises a body in the form of a disk-shaped support for the magnets, with two circular faces connected by a thickness, the disk being defined between an outer rim formed by frets and an inner circumference defining a recess for the rotating shaft.

[0007] The magnets are each held to a disk-shaped support by a holding means, leaving spaces between the magnets.

[0008] In axial flux motors, the peripheral speed of the rotor generates centrifugal forces at the level of the magnets which can become significant and limit the maximum allowable speed.

[0009] In the case of the magnet or pole structure, most of the force is absorbed by the peripheral frets and also by the adhesive on the contours of the magnet structure that connects it to the branches.

[0010] Axial flux motors are often used as motors that have a higher torque density than radial flux motors, and therefore can be used in lower speed applications.

[0011] For high-speed applications, the rotor design of axial-flux motors becomes more complex because centrifugal forces create very high mechanical stresses on the rotor. Furthermore, if the rotor section is made of conductive materials, eddy current losses become significant in both the magnets and the rotor section.

[0012] The main drawback of high-speed motors is that the magnets are likely to become dislodged from the rotor, causing at least partial damage to the rotor. Therefore, the rotor of this type of motor must be able to withstand high speeds.

[0013] The prior art teaches those skilled in the art to reinforce the disk-shaped support of the magnet to resist the centrifugal force, which requires a specific material for the disk-shaped support and requires the disk-shaped support to be thicker and larger in size to increase the rigidity of the disk-shaped support.

[0014] This solution is not entirely satisfactory, since a motor or generator with a disk-shaped support would be heavy and expensive to manufacture.

[0015] One solution is to build a mesh of elongated unit magnets out of a fiber and resin structure to reduce eddy currents, use a rotor made of a non-conductive composite material, ideally a fiberglass rotor, and place frets around the rotor to contain the forces caused by centrifugal effects.

[0016] However, in very high speed applications, the mechanical stresses become so great that the weight of the magnets must be reduced to achieve these rotational speeds. However, the torque that an electric machine must supply is proportional to the surface area of ​​the magnets that interact with the magnetic field generated by the stator. Therefore, as the surface area of ​​the magnets decreases, the torque decreases, and so does the power of the machine.

[0017] The closest prior art, EP-A-0353042, describes a rotor for an electromagnetic motor or generator, comprising an inner hub concentric with a central axis of rotation of the rotor, branches extending radially from the inner hub relative to the central axis of rotation towards frets forming a circular periphery of the rotor, at least one magnet housed in each space between two adjacent branches, the width of each branch decreasing with distance from the inner hub and terminating in a tapered point towards the frets, and the width of each magnet increasing with distance from the inner hub and terminating in the frets surrounding the rotor.

[0018] This prior art document does not allow for a support for multiple permanent magnets that, on the one hand, effectively compensates for centrifugal forces while effectively holding the permanent magnets that the rotor supports so that the magnets do not fall out of the rotor, and, on the other hand, has the mechanical strength to allow the rotor to rotate at very high speeds.

[0019] FR-A-1475501 does not describe a rotor, but only describes a magnet structure including a plurality of unit magnets, and does not specify the use of this magnet structure. Although it suggests that the use of this type of magnet structure having a plurality of unit magnets can overcome the shortcomings of the two priority documents referenced above, this document makes no mention of using this type of magnet structure for a rotor.

[0020] The problem that the present invention aims to solve is the design of a rotor for an axial flux electromagnetic machine for supporting multiple permanent magnets, with frets, which, on the one hand, can effectively hold the permanent magnets it supports by preventing the magnets from falling off the router while effectively compensating for centrifugal forces, and, on the other hand, has the mechanical strength to allow the rotor to rotate at very high speeds. [Prior art documents] [Patent documents]

[0021] [Patent Document 1] EP-A-0353042 [Patent Document 2] FR-A-1475501 Summary of the Invention

[0022] To this end, the present invention provides a rotor for an electromagnetic motor or generator, comprising a body, the body comprising: 1. A rotor for an electromagnetic motor or generator comprising: an inner hub concentric with the central axis of rotation of the rotor; branches extending radially from the inner hub to frets forming the circular periphery of the rotor, relative to the central axis of rotation; and magnetic structures forming magnetic poles, the magnetic structures being housed in each space defined between two adjacent branches associated with the magnetic structures, each magnet structure being in the form of two separate substructures, inner and outer respectively depending on their position within the rotor, extending radially between two associated adjacent branches, the inner substructure of the rotor having its innermost surface in at least partial contact with the internal hub when the rotor is not rotating, and a side of said inner substructure facing each of the two associated branches mechanically engaging an opposite portion of said associated adjacent branch, providing an axial stop in the direction of the rotor and free radial movement relative to the rotor; the outer substructure outer with respect to the rotor has its outermost surface with respect to the rotor facing the frets; The present invention relates to a rotor for an electromagnetic motor or generator, characterized in that

[0023] The mechanical engagement according to the present invention makes it possible to retain the inner substructure axially relative to the rotor while allowing for slight radial displacement, which was not possible when the one-piece magnet structure was adhesively connected laterally to the branches.

[0024] The inventive step of the present invention is to modify the geometry of each magnet structure housed between two adjacent branches by creating two separate parts or substructures: forces exerted on the outer substructure are absorbed by the frets, and forces exerted on the inner substructure are absorbed by the part of the branch adjacent to the rotor hub through mechanical absorption.

[0025] The invention therefore allows for absorption of centrifugal forces that is specifically adapted to the location of the substructures within the rotor, the absorption being different for inner and outer substructures.

[0026] This allows the rotor to rotate at speeds in excess of 15,000 rpm when the rotor diameter is approximately 300 millimeters.

[0027] As mentioned above, in the rotor of an axial flux machine, the magnets are adhesively connected to the branches, which allows them to transmit to the branches part of the centrifugal force, which varies depending on the elastic modulus of the adhesive and therefore its temperature coefficient.

[0028] In the present invention, adhesives for distributing the load on the branches are no longer needed, mainly on the inner substructure, and the portion of the force transmitted to the branches is no longer a function of temperature, but only of the distribution of mass on the two substructures of the magnet structure.

[0029] In addition to being able to increase the rotational speed of the rotor, an additional advantage is that more of the magnet mass can be located at the outer radius of the rotor, which facilitates torque generation for the magnet structure in the monolithic magnet block at the same speed and with the same magnet mass relative to the rotor of an axial flux machine.

[0030] Advantageously, mechanical engagement between each side of the inner substructure of each magnet structure and the opposing portion of the associated adjacent branch can be achieved by engaging a male part carried laterally by each inner substructure with a female part carried by a portion of the opposing branch of the inner substructure, or vice versa in terms of the arrangement of the male and female parts.

[0031] These measures can optionally ensure that the inner substructure is axially retained within the rotor, while ensuring that centrifugal forces acting on the inner substructure are transmitted to the branches.

[0032] Each inner substructure is advantageously embedded in a first composite layer that completely covers the inner substructure, the first composite layer being configured to form male components, each male component being laterally supported on one side by a respective inner substructure.

[0033] The two inner and outer substructures of each magnet structure between two adjacent branches are embedded in a second composite layer that completely covers the magnet structure, and the rotor is also covered by a third composite layer.

[0034] The rotor therefore has three coatings, the composition of which can vary depending on their role. The first coating relates to the coating of the substructure. This coating can be more flexible to allow deformation of the substructure. The second coating is the coating of the magnet structure or poles and can contain more fibers to make it more rigid. Finally, the third coating relates to the rotor itself and is also advantageously reinforced.

[0035] Providing three coatings that complement each other ensures that the high mechanical strength required for rotors rotating at high speeds is achieved, especially since the composition of each coating is specifically selected depending on its position within the rotor and the elements it surrounds.

[0036] Advantageously, the cross section of the legs is in the shape of a rhombus connected to the inner hub by feet that become wider as they approach the hub, the two innermost faces of the rhombus on the rotors of two associated adjacent legs surrounding the inner substructure of each magnet structure, the two outermost faces of the rhombus on the rotors of two associated adjacent legs surrounding the outer substructure of each magnet structure, the inner substructure of each magnet structure completely filling a first housing delimited between the two innermost faces of the rhombus of the two associated branches in the space between the two associated adjacent branches, and the outer substructure of each magnet structure completely filling a second housing delimited between the two outermost faces of the rhombus of the two associated branches in the space between the two associated adjacent branches.

[0037] This type of diamond-shaped configuration allows limiting the radial displacement of the inner substructure while at the same time allowing for the placement of larger mass magnets towards the outside of the rotor, near the frets, relative to the outer substructure.

[0038] Advantageously, the bases of two associated adjacent branches that contact the inner hub are separated by an intermediate portion of the inner hub, the intermediate portion being in at least partial contact with the innermost surface on the rotor of the inner substructure.

[0039] Advantageously, the inner and outer substructures of each magnet structure are separated by a clearance gap.

[0040] A running clearance is desired to prevent the inner substructures from contacting the associated outer substructures, so that each inner substructure does not contact the wall of the opposing branch, and therefore all centrifugal forces are absorbed by the frets rather than by the opposing portion of the branch on the rotor body.

[0041] The actuation gaps can be filled with a flexible resin or adhesive that is more flexible than the body branches so that the centrifugal load of each inner substructure is not transmitted to the frets.

[0042] Advantageously, at least one of the substructures of each magnet structure is constituted by a plurality of unit magnets held together by a fibre-reinforced insulating material.

[0043] An additional synergy achieved by the present invention is that the rotor can have unit magnets grouped in inner or outer substructures between each branch.

[0044] This allows for the provision of substructures with a large number of unit magnets, which have been found to be very insensitive to the space harmonics or currents generated by the stator windings, resulting in very low losses in the substructure and very high power output, especially at high speeds.

[0045] One of the options of the present invention is to divide the inner or outer substructure, which can be the entire magnet or a pole depending on the technology, into multiple miniature or micro-magnets.

[0046] Large magnets have higher losses due to eddy currents than small or micro magnets, and the use of small or micro magnets can reduce these losses, which can adversely affect the operation of the electromagnetic actuator.

[0047] Applicant has discovered that when multiple unit magnets are present in a magnetic structure, n unit magnets result in a magnetic structure that has substantially the same magnetic properties as a single magnet having a surface area equal to n times the base surface area of ​​the n unit magnets, while having much higher mechanical strength.

[0048] Advantageously, each unit magnet has an elongated shape extending in the axial direction of the rotor, each unit magnet having a polygonal shape or an at least partially oval contour, the elongated shape or oval contour including a first portion forming the body of the unit magnet, the first portion having a larger cross-sectional area and extending over a longer length than at least a second longitudinal end portion directed towards the associated longitudinal end of the unit magnet, the cross-section of which decreases as it approaches the longitudinal end.

[0049] It is well known that to obtain a magnetic field of optimum strength, the ideal volume of a magnet should approach that of a cube or cylinder whose length is equal to its diameter, and that no increase in magnetic field is achieved by increasing the length of the magnet.

[0050] However, in an alternative embodiment, the present invention goes against this prejudice regarding the use of elongated unit magnets.

[0051] The length of the unit magnet is, contrary to common practice, significantly greater than the diameter or diagonal of its planar longitudinal surface.

[0052] The ovoid magnets can have facets, which creates unit magnets in the form of "crystals" that are related to each other and not linked across the entire surface of the facets or longitudinal faces, but the layers of resin and adhesive form a mesh network at the edges of the multi-faceted block with limited contact area between the magnets.

[0053] Alternatively, for unit magnets that are perfectly oval in shape with a rounded first portion, the contact between two adjacent unit magnets may be small, resulting in only a spot contact, which essentially corresponds to a small arc between the two unit magnets.

[0054] A groove may be cut to the size of the contact arc between two adjacent unit magnets to receive an adhesive, preferably in the form of a resin.

[0055] Advantageously, each unit magnet is in the form of a slice whose thickness is at least one-tenth of its length, the slices forming the unit magnets being separated into at least one substructure of each magnet structure by cutouts in orthogonal radial faces in the rotor.

[0056] Advantageously, at least one of the substructures of each magnet structure constituted by a plurality of unit magnets includes at least one mesh structure having cells, each cell defining a housing for a respective unit magnet, each housing having internal dimensions allowing a unit magnet to be introduced therein, the space between the housing and the unit magnet being filled with a fiber-reinforced insulating material, and the mesh structure being made of the fiber-reinforced insulating material.

[0057] The mesh structure can be coated with a composite layer so that it remains in place. This type of mesh structure has the advantage of being able to hold the unit magnets during the fabrication of the substructure and represents an additional solidification element for the substructure; the mesh structure can also include reinforcing fibers.

[0058] For example, honeycomb mesh structures are known to enhance the strength of elements, in this case substructures. Unit magnets are inserted into hexagonal housings, which hold them in place. The walls of the housings act as electrical insulators, allowing for a significant increase in the density of the housings within the substructure. Honeycomb cell structures can be made from fiber-reinforced insulating composite materials.

[0059] The inner hub and prongs may advantageously be made of fiberglass cast in resin.

[0060] These glass or reinforcing fibers help to increase the strength of the rotor, particularly its bending strength and resistance to buckling.

[0061] The rotor has circular faces bounded in the axial direction, and preferably a cover disk is arranged on at least one circular face of the rotor.

[0062] This applies primarily, but not exclusively, to substructures of magnet structures that include multiple unit magnets. The large magnets used in prior art rotors dissipated large amounts of heat. This heat dissipation prevented the use of axial retention means in the form of composite cover disks, and the heat dissipation could affect the performance of the coating and accelerate aging of the coating and magnets.

[0063] Therefore, composite cover disks have not been widely used in the prior art because they cannot withstand the heat dissipation generated by the magnets.

[0064] The present invention advantageously uses multiple unit magnets instead of the compact magnets of the prior art, thereby reducing heat dissipation and allowing the use of composite cover disks as axial retention means, these cover disks advantageously replacing the axial retention means between the magnet and the rotor body, possibly requiring modifications to the magnet or its coating to provide additional attachment means with the attachment means held by the rotor.

[0065] Advantageously, the distal end of each branch is supported against a fret, and the rotor body is formed by two equal body portions axially aligned within the rotor.

[0066] This makes it possible to achieve part of the mechanical engagement between the associated branches and the inner substructures by creating a female part between the two body parts, for example in the form of a groove, that receives a male part carried by each inner substructure.

[0067] The invention further provides a method for manufacturing a rotor of this type, comprising the steps of: introducing an inner substructure between each pair of two associated adjacent branches of one of the two bodies; joining the two bodies together; introducing outer substructures between each pair of two associated adjacent branches of the body, each outer substructure being a radial extension of the inner substructure; and placing a fret against the distal end of each branch and adhesively connecting the outer substructure to the fret; The present invention relates to a method for producing a medicament for the treatment of a brain ulcer, comprising the steps of:

[0068] In this way, manufacturing is facilitated by using a rotor consisting of two parts adhesively connected to one another, leaving a gap between them, and in which part of the mechanical engagement between each inner substructure and its associated branch is achieved in the form of a female part that can accommodate one or more male parts of each inner substructure.If the magnetic structure is coated as a whole, this method can be modified by replacing the first step with introducing the magnetic structure and its inner and outer substructures between each pair of associated two adjacent branches of one of the two body parts, and omitting the third step.

[0069] The present invention relates to an axial flux electromagnetic motor or generator comprising at least one rotor as described above and at least one stator carrying at least one winding, the electromagnetic motor or generator comprising one or more air gaps between the at least one rotor and the at least one stator.

[0070] Advantageously, the electromagnetic motor or generator comprises at least one rotor associated with two stators. [Brief explanation of the drawings]

[0071] The invention is illustrated in the accompanying drawings: [Figure 1] 1 is an exploded view of one embodiment of a rotor according to the present invention. [Figure 2] 1 is a highly schematic axial cross-sectional view of one embodiment of a magnet structure forming part of a rotor according to the present invention, with elements shown separated from one another for better visibility; [Figure 3] FIG. 2 is a front perspective view of one embodiment of an inner substructure of a magnet structure forming part of a rotor according to the present invention. [Figure 4] 1 is a radial cross-section of one embodiment of a magnetic structure forming part of a rotor according to the present invention; [Figure 5] 1 is a perspective view of one embodiment of a body consisting of an inner hub and prongs forming part of a rotor according to the present invention; FIG. [Figure 6] FIG. 6 is an enlarged perspective view of a branch portion of the main body shown in FIG. 5. [Figure 7] 1 shows a first alternative embodiment of a unit magnet included in a substructure of a magnetic structure forming part of a rotor according to the invention; FIG. [Figure 8] 10 shows a second alternative embodiment of a unit magnet included in a substructure of a magnetic structure forming part of a rotor according to the invention; FIG. [Figure 9] 10 shows a third alternative embodiment of a unit magnet included in a substructure of a magnetic structure forming part of a rotor according to the invention; FIG. [Figure 10] 10A and 10B show separately a fourth alternative embodiment of a unit magnet included in a substructure of a magnetic structure forming part of a rotor according to the invention; DETAILED DESCRIPTION OF THE INVENTION

[0072] The embodiments shown in the accompanying drawings are given by way of example and are not intended to limit the present invention. These are schematic diagrams for facilitating understanding of the present invention and are not necessarily drawn to the scale of an actual application. In particular, the dimensions of the various components do not reflect reality.

[0073] For the sake of brevity, the term "magnet" is not repeated after the word "substructure" because a structure that includes two substructures is a magnet structure, and this applies to both the inner and outer substructures.

[0074] In the following, where applicable, reference will be made to only one adjacent branch 3, one magnet structure 10, one inner substructure 11, and one outer substructure 12. The same applies to the single unit magnets of Figures 2 and 7-10, as well as to the single adhesive layer between the unit magnets and, where applicable, the single mesh.

[0075] However, anything said about one of these referenced elements applies to all similar elements not referenced.

[0076] With reference to all figures, particularly figures 1 to 6, and in particular figures 1, 2 and 5, these figures show a rotor 1 with two branches 3 between which is interposed a magnetic structure, shown split and made up of an inner substructure 11 and an outer substructure 12.

[0077] This type of rotor 1 is used in an electromagnetic motor or generator, preferably an axial flux motor or generator. The rotor 1 has a body 25a, 25b that is preferably substantially circular and includes an inner hub 2 that is concentric with the central axis of rotation 7 of the rotor 1 or the central longitudinal axis of the rotor 1.

[0078] The branches 3 extend radially within the rotor 1 from the inner hub 2 to frets 8 that form the circular outer periphery of the rotor 1 relative to a central axis of rotation 7 .

[0079] At least one magnetic structure, referred to in FIG. 10, is housed in each space bounded between two adjacent branches 3 by its inner substructure 11 and outer substructure 12 .

[0080] Thus, according to the invention, each magnet structure 10 takes the form of two different substructures 11, 12, respectively an inner and an outer, depending on its position in the rotor 1. Each pair of two different substructures 11, 12, respectively an inner and an outer, has its outer substructure 12 extending radially from its inner substructure 11 between the two adjacent branches 3 associated therewith.

[0081] Each inner substructure 11 on the rotor 1 presents an innermost surface opposite the inner hub 2, which surface is not connected to the inner hub 2, and the inner substructure 11 is in at least partial contact with the inner hub 2, at least when the rotor 1 is not rotating and centrifugal force is not pushing each inner substructure 11 towards the periphery of the rotor 1.

[0082] The side of each inner substructure 11 on the rotor 1 faces each of the two associated adjacent branches 3 and is mechanically engaged 13, 14 with the opposing portions of the associated adjacent branches.

[0083] The mechanical engagements 13 , 14 ensure axial stopping of the rotor 1 and limited freedom of movement radially relative to the rotor 1 from the inner hub 2 towards the frets 8 .

[0084] To avoid unwanted radial movements such as vibrations during rotation of the rotor 1, it is advantageous to provide limited radial friction in the mechanical engagements 13, 14 between the branches 3 associated with each inner substructure 11. The coefficient of friction can be selected taking into account the desired rotational speed of the rotor 1 and the magnitude of the centrifugal forces acting on the inner substructure 11 at that time.

[0085] Each outer substructure 12 on the rotor 1 has its outermost surface in relation to the rotor 1 in contact with a fret 8 .

[0086] As can be seen particularly in Figures 3, 5 and 6, the mechanical engagement 13, 14 between each side of the inner substructure 11 of each magnet structure and the opposing portion of the associated adjacent branch may be achieved by a male part 13 held laterally by each inner substructure 11 housed in a female part 14 held on the part of the branch 3 facing the inner substructure 11.

[0087] The reverse may also be possible by providing a female part on the inner substructure 11 and a male part on the branch.

[0088] For example, a rail as a male part 13 carried laterally by each inner substructure 11 can be inserted into a groove as a female part 14 carried by a portion of the branch 3 on the opposite side of the inner substructure 11. A tenon can also be used as the male part 13, fitting into a mortise or recess carried by the branch 3, or vice versa.

[0089] Any mechanical connection may be used, as long as the connection used ensures axial stop of the rotor 1 and limited radial freedom of movement of the rotor 1 .

[0090] With particular reference to FIGS. 2 and 3, each of the inner substructure 11 or outer substructure 12 may be embedded in a first composite layer 15 that completely encases the inner substructure 11 or outer substructure 12 .

[0091] In the case of the inner substructure 11, the first composite layer 15 may be configured to form the male components 13, each of which is laterally mounted on one side of the inner substructure 11.

[0092] With particular reference to FIG. 2 , the two substructures, the inner substructure 11 and the outer substructure 12, of each magnetic structure 10 of two adjacent branches 3 may be embedded in a second composite material layer 16 that completely encases the magnetic structure 10.

[0093] In this case, if present, the second composite layer 16 may be molded to carry the male component 14 on either side thereof.

[0094] Furthermore, the rotor 1 can also be embedded in a third composite layer 17 , which can also cover at least one cover disc 27 .

[0095] In this Figure 2, a portion of the third composite layer 17 is shown separated from the second composite layer 16 and the cover disc 27 for clarity of illustration, but in reality this third composite layer is adjacent to the second composite layer, with or without the cover disc 27 therebetween.

[0096] The composite layers may include reinforcing fibers. The fiber content may vary from layer to layer. Thus, without limitation, the first composite layer 15 of the inner substructure 11 may have a lower fiber content than the second or third composite layers 16, 17, and may be slightly more flexible, allowing the inner substructure 11 to move slightly closer to the outer substructure 12 as the rotor rotates.

[0097] The magnet volume of each outer substructure 12 can be larger than the magnet volume of each inner substructure 11. This is shown in Figure 4, where the outer substructures can be in the shape of a truncated cone that opens towards the frets 8.

[0098] By positioning each outer magnet substructure 12 so that its largest opening faces the outer periphery of the rotor 1, i.e., the frets 8, it is possible to increase the portion of the magnets positioned on the outer periphery of the rotor 1 and thereby increase the total magnetic surface area.

[0099] As best shown in FIG. 5 for a single branch, the bases of two adjacent branches 3 may be separated by an intermediate portion 9 of the inner hub 2 .

[0100] The inner hub 2 and prongs 3 can be made of glass fiber cast in resin, or strong plastic fibers can be used to increase the strength of the rotor 1, especially its bending strength and resistance to buckling.

[0101] To strengthen the rotor 1, the rotor body 25a, 25b can be integrated with the branches 3. The branches 3 may or may not be connected to the frets 8 by tapered tips 3b.

[0102] As can be seen particularly when considering Figures 1, 2, 5 and 6 in combination, Figure 6 is an enlarged view of the portion of the branch circled in Figure 5 and designated by reference numeral A, where branch 3 has, in cross section, a diamond shape 19 which is connected to inner hub 2 by feet 18 which increase in width towards the outside of diamond 19 as they approach hub 2.

[0103] The two cross sections of the rhombus 19 of the two associated adjacent branches 3 that are innermost with respect to the rotor 1 may surround the inner substructure 11 of each magnet structure 10. The two cross sections of the rhombus 19 of the two associated adjacent branches 3 that are outermost with respect to the rotor 1 may surround the outer substructure 12 of each magnet structure 10.

[0104] The inner substructure 11 of each magnetic structure 10 can completely fill the first housing 20 defined between the two innermost cross sections of the diamonds 19 of the two associated branches 3 in the space between the two associated adjacent branches 3.

[0105] The inner substructure 11 of each magnet structure 10 may leave a lateral cavity opposite the feet 18. This lateral cavity may be less than 5% of the surface area filled by the inner substructure 11.

[0106] The outer substructure 12 of each magnetic structure 10 can completely fill the second housing 21 defined between the two outermost cross sections of the diamonds 19 of the two associated branches 3 in the space between the two associated adjacent branches 3.

[0107] The bases of two adjacent associated branches 3 in contact with the inner hub 2 may be separated by an intermediate portion 9 of the inner hub 2. The intermediate portion 9 of the inner hub 2 may be in at least partial contact with the innermost surface of the inner substructure 11 with respect to the rotor 1.

[0108] The inner substructure 11 and outer substructure 12 of each magnet structure 10 may be separated by a clearance 22 .

[0109] The clearance 22 may be circular, and the continuation of the clearance 22 in the magnetic structure of the rotor 1 may form a circle centered on the center of the rotor 1 through which the central axis of rotation 7 passes.

[0110] The working clearance 22 can be filled with a soft resin or adhesive that is softer than the branches 3 of the rotor 1 so that the centrifugal loads of the inner substructure 11 are not transmitted to the frets 8 .

[0111] Alternatively, this clearance 22 may be left empty.

[0112] Although it is possible for at least one inner substructure 11 or outer substructure 12 to have only one magnet, with reference to Figures 7 to 10, reference numbers not shown in these figures refer to other figures, at least one of the substructures 11, 12 of each magnet structure 10 may be made up of a plurality of unit magnets 4, 4c, 4d bonded together by a fibre-reinforced insulating material 23.

[0113] As shown in Figure 7, each unit magnet 4, 4c, 4d may be elongated so as to extend in the axial direction of the rotor 1. The unit magnet 4, of which only one is shown in Figure 7, should not be confused with the magnet structure 10 or a larger magnet not shown in the figure.

[0114] Each magnet structure 10 is therefore three-dimensional and may be made up of a number of unit magnets 4, 4c, 4d.

[0115] In FIG. 7, each unit magnet 4 of the plurality of unit magnets has a polygonal, preferably parallelepiped, shape.

[0116] In FIG. 9, four parallelepiped unit magnets 4 are shown, which are larger than the unit magnets 4 of FIG. 7 and therefore fewer in number, specifically four in this FIG.

[0117] In FIG. 10, each unit magnet 4c can have an at least partially oval outline.

[0118] This egg-shaped unit magnet 4c has a first portion 4a forming the body of the unit magnet 4c, the first portion 4a having a larger cross-sectional area than at least a second longitudinal end portion 4b and extending over a longer length of the unit magnet 4c, the second longitudinal end portion 4b being directed towards the associated longitudinal end of the unit magnet 4c and having a decreasing cross-sectional area as it approaches the longitudinal end.

[0119] Regardless of the type of unit magnet, the unit magnets can be directly adjacent to each other and partially in contact with each other. Individual unit magnets 4 can be connected to each other with adhesive. Multiple unit magnets 4, 4c, 4d form a magnetic mesh without any holding element other than adhesive, and each unit magnet 4, 4c, 4d is in direct contact with adjacent magnets.

[0120] It is possible to have a magnet structure 10 with inner and outer substructures 11, 12 each containing a different unit magnet.

[0121] In FIG. 2, in the inner substructure 11 of the magnetic structure 10, the unit magnets 4 are connected to each other by adhesive bonding without any mesh between them, while in the outer substructure 12, the unit magnets are connected to each other by adhesive bonding with a mesh structure 24 interposed therebetween.

[0122] Thus, at least one of the substructures 11 , 12 of each magnetic structure 10 consisting of a plurality of unit magnets can include at least one mesh 24 having cells defining the housing of the respective unit magnet 4 .

[0123] Each housing has an internal dimension large enough to allow a unit magnet 4 to be inserted therein, and a space is left between the housing and the unit magnet 4 to be filled with fiber-reinforced insulating material, and the mesh structure is made of fiber-reinforced insulating material.

[0124] In FIG. 2, reference numeral 23 denotes an insulating material that fills the space between the two unit magnets 4 .

[0125] The magnet structure 10 can also be designed without mesh on its inner and outer substructures 11, 12.

[0126] Thus, the unit magnets can be pixelated magnets of square, rectangular or other shapes. Resin or adhesive 23 can be injected between the magnets to form the rough blanks for both the inner and outer substructures.

[0127] The pixels can be realized in a tilted orientation at any angle relative to the axis of symmetry of the inner or outer substructure 11 or 12 that contains them.

[0128] It is possible to provide different unit magnets in one substructure 11 or 12 and in one associated substructure 12 or 11 within the same magnet structure 10 .

[0129] In another embodiment, each unit magnet can be in the form of a slice 4d having a thickness at least one-tenth of its length, as shown in Figure 8. Figure 8 shows six unit magnets 4d, each in the form of a slice.

[0130] The slices 4d forming the unit magnets can be separated by cutouts in orthogonal radial planes with respect to the rotor 1 in at least one of the substructures 11, 12 of each magnet structure 10. The empty space between two slices 4d can be filled with resin or adhesive as an insulating material 23.

[0131] The inner hub 2 and prongs 3 may be made of fiberglass cast in resin and may be single or multi-piece.

[0132] The frets 8 of the rotor 1 may be made of fiberglass or carbon fiber. The frets 8 may circumferentially surround a magnetic structure 10 on the outer periphery of the rotor 1.

[0133] The frets 8 contribute, if necessary, to radial retention of the magnet structure 10 and mechanical engagement between the inner substructure 11 and the branches 3. The distal ends of the branches 3 may or may not be attached to the frets 8, but are in contact with the frets 8. The frets 8 can be seen particularly in Figures 1 and 4.

[0134] The rotor 1 may have circular faces that delimit the rotor 1 in the axial direction, and cover discs 27, which can be seen in Figure 2, are arranged on at least one circular face of the rotor 1, advantageously one cover disc 27 is arranged on each circular face of the rotor 1.

[0135] This prevents axial movement of the magnet structure 10 between the two branches 3. The cover disk 27 is shown very diagrammatically in Figure 2 and is separated from the magnet structure 10 so that it can be seen more clearly.

[0136] As can be seen in particular in FIG. 1, the body of the rotor 1 can be made up of two identical body portions 25a, 25b axially aligned with respect to the rotor 1, preferably two concentric disks adhesively connected to each other.

[0137] The spacing between the two discs makes it possible to locally realize, in the branches 3, female parts 14 on opposing portions of the inner substructure 11, as can be seen in particular in Figures 5 and 6, which, in cooperation with respective male parts 13 mounted laterally on either side of each inner substructure 11, are necessary to realize the mechanical engagement 13, 14 of each side of the inner substructure 11 of each magnetic structure 10 with the opposing portion of the associated adjacent branch.

[0138] As can be seen particularly in Figures 5 and 6, for the single body 25a shown, this is also true for the other bodies 25b, but in one preferred embodiment each body 25a, 25b comprises an inner contour 26a that is smaller in size and diamond shaped, similar to the outer contour of each body 25a.

[0139] 1, 5 and 6, when the two body portions 25a, 25b are pressed together with their inner contours 26a facing each other, a groove 14 is formed, forming a female portion defined inside the two pressed body portions 25a, 25b.

[0140] Instead of a two-part body, it is also possible to envisage a one-piece body with grooves in the sides of the branches as the female part.

[0141] The invention further relates to a method for manufacturing a two-part rotor 1 as described above, the first step of which is to introduce pre-formed inner substructures 11, each forming a closed entity, each of which is housed between a pair of two adjacent associated branches 3 of one of the two body parts 25a, 25b of the rotor 1.

[0142] The second step is to join the two body parts 25a, 25b together, for example by adhesive.

[0143] The third step is to introduce an outer substructure 12 between each pair of two adjacent branches 3 associated with the body 25a, 25b.

[0144] Each outer substructure 12 is a radial extension of an inner substructure 11 .

[0145] The fourth step is to place a fret 8 against the distal end of each branch, followed by bonding an outer substructure 12 to the fret 8.

[0146] Note that the inner substructure 11 is not adhesively connected to the branches 3 or the inner hub 2 .

[0147] Alternatively, it is possible to manufacture a complete magnet structure comprising an inner substructure 11 and an outer substructure 12, each of which forms a separate whole and which are each joined together, the first step of the alternative method being to introduce a pre-formed magnet structure 10, each of which forms a closed entity, between each pair of two adjacent branches 3 associated with one of the two body portions 25a, 25b of the rotor 1.

[0148] In this alternative variation, the third step of the above process is omitted.

[0149] Finally, the present invention relates to an axial flux electromagnetic motor or generator comprising at least one such rotor 1, which comprises at least one stator having at least one winding, and which comprises one or more air gaps between the at least one rotor 1 and the at least one stator.

[0150] The electromagnetic motor or generator may preferably include at least one rotor 1 associated with two stators.

Claims

1. A rotor (1) for an electromagnetic motor or generator, comprising a body (25a, 25b), said body (25a, 25b) comprising: A rotor (1) for an electromagnetic motor or generator, comprising: an inner hub (2) concentric with a central axis of rotation (7) of the rotor (1); branches (3) extending radially from the inner hub (2) towards frets (8) forming a circular periphery of the rotor (1) with respect to the central axis of rotation (7); and magnetic structures (10) forming magnetic poles, the magnetic structures (10) being housed in each space defined between two adjacent branches (3) associated with the magnetic structure (10), each said magnetic structure (10) in the form of two separate substructures (11, 12), respectively inner and outer depending on its position within said rotor (1), extending radially between two associated adjacent said branches (3), the inner substructure (11) of said rotor (1) having its innermost surface in at least partial contact with said internal hub (2) when said rotor (1) is not rotating, and the side of said inner substructure (11) facing each of said two associated branches (3) mechanically engaging (13, 14) with the opposite part of said associated adjacent branch, providing an axial stop in the direction of said rotor (1) and free radial movement with respect to said rotor (1); an outer substructure (12) on the outer side of the rotor (1) with its outermost surface facing the frets (8); A rotor (1) for an electromagnetic motor or generator, characterized in that:

2. the step of mechanically engaging (13, 14) each side of the inner substructure (11) of each said magnetic structure (10) with the opposing part of the associated adjacent branch is performed by male parts (13) carried laterally on both sides of each said inner substructure (11) housed in female parts (14) carried by the part of the branch (3) facing said inner substructure (11), or by the positioning of said male parts (13) and said female parts (14) vice versa; A rotor (1) according to claim 1, characterized in that it

3. Each of the inner substructures (11) is embedded in a first composite layer (15) that completely covers the inner substructure (11), the first composite layer (15) being configured to form the male portions (13), each of the male portions (13) being carried laterally on one side by each of the inner substructures (11); A rotor (1) according to claim 2,

4. 4. A rotor (1) according to claim 3, characterized in that the two inner and outer substructures (11, 12) of each magnetic structure (10) between two adjacent branches (3) are embedded in a second composite layer (16) that completely covers the magnetic structure (10), and the rotor (1) is also covered by a third composite layer (17).

5. the branches (3) have a cross section in the shape of a diamond (19) connected to the internal hub (2) by legs (18) that become wider as they approach the internal hub (2), and the two faces of the diamond (19) of the two associated adjacent branches (3) in the cross section closest to the rotor (1) surround the inner substructure (11) of each of the magnetic structures (10), and the two faces of the diamond (19) of the two associated adjacent branches (3) in the cross section farthest from the rotor (1) surround the outer substructure (12) of each of the magnetic structures (10), the inner substructure (11) of each of the magnetic structures (10) completely fills a first housing (20) bounded by the two innermost rhombus-shaped (19) faces in cross section of the two associated adjacent branches (3) in the space between the two associated adjacent branches (3); and the outer substructure (12) of each of the magnetic structures (10) completely fills a second housing (21) bounded by the two outermost rhombic (19) faces of the two associated branches (3) in the space between the two associated adjacent branches (3); A rotor (1) according to any one of claims 2 to 4.

6. A rotor (1) according to any one of claims 1 to 5, characterized in that the inner and outer substructures (11, 12) of each magnetic structure (10) are separated by a clearance (22).

7. 7. The rotor (1) according to claim 1, wherein at least one of the substructures (11, 12) of each of the magnet structures (10) is composed of a plurality of unit magnets (4, 4c, 4d) bonded together by a fiber-reinforced insulating material (23).

8. 8. The rotor (1) according to claim 7, characterized in that each of the unit magnets (4, 4c) is elongated and extends in the axial direction of the rotor (1), each of the unit magnets (4) being polygonal in shape or each of the unit magnets (4c) having an at least partially oval outline, the oval shape or outline being such that a first portion (4a) forming the body of the unit magnet (4c) has a larger cross-sectional area and extends over a longer length than a second longitudinal end portion (4b) towards the associated longitudinal end of the unit magnet (4c) by decreasing in cross-sectional area at least towards the longitudinal end.

9. 8. The rotor (1) according to claim 7, characterized in that each of the unit magnets (4, 4c, 4d) is in the form of a slice (4d) having a thickness of at least one-tenth of its length, the slices (4d) forming unit magnets being separated by cutouts in orthogonal radial planes in the rotor (1) in at least one of the substructures (11, 12) of each of the magnetic structures (10).

10. 10. The rotor (1) according to any one of claims 7 to 9, characterized in that at least one of the substructures (11, 12) of each of the magnet structures (10) consisting of a plurality of the unit magnets (4, 4c, 4d) incorporates at least one mesh structure (24) having cells, each of the cells defining a housing for a respective one of the unit magnets (4, 4c, 4d), each of the housings having an internal dimension that allows the unit magnets (4, 4c, 4d) to be introduced therein, a space filled with a fiber-reinforced insulating material (23) remaining between the housing and the unit magnets (4, 4c, 4d), and the mesh is made of the fiber-reinforced insulating material.

11. A rotor (1) according to any one of the preceding claims, characterized in that the inner hub (2) and the branches (3) are made of glass fibre cast in resin.

12. 12. The rotor (1) according to any one of claims 1 to 11, characterized in that the rotor (1) has a circular surface bounded in the axial direction, and a cover disk (27) is arranged on at least one of the circular surfaces of the rotor (1).

13. A rotor (1) according to any one of claims 1 to 12, characterized in that the distal end of each branch (3) is in contact with the fret (8), and the body (25a, 25b) of the rotor (1) is formed by two equal body portions (25a, 25b) axially aligned within the rotor (1).

14. A method for manufacturing a rotor (1) according to claim 13, comprising: introducing an inner substructure (11) between each pair of two associated adjacent branches (3) of one of the two bodies (25a, 25b); joining the two bodies (25a, 25b); introducing an outer substructure (12) between each pair of two associated adjacent branches (3) of the body (25a, 25b), each outer substructure (12) being in radial extension of the inner substructure (11); placing a fret (8) against the distal end of each of said branches (3) and adhesively connecting said outer substructure (12) to said fret (8); A method comprising:

15. An axial flux electromagnetic motor or generator comprising at least one rotor (1) according to any one of claims 1 to 13, at least one stator with at least one winding, and one or more air gaps between the at least one rotor (1) and the at least one stator.

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