Method for manufacturing a magnet structure with several unit magnets

Abstract

Method for manufacturing a magnet structure with several unit magnets. The method for manufacturing a magnet structure includes the step of creating, in a blank (15) of the magnet structure, at least two groups of cuts in the vertical direction of the magnet structure. The cuts in each group are interrupted vertically, each forming two parts and leaving a gap filled with material from the blank (15) between the two parts of the same cut. The two groups of cuts define unit magnets in the blank (15). The gaps in the cuts form an internal flange in the blank (15), joining the unit magnets together. The process also includes the step of injecting composite material into the cuts in a single injection to obtain the final magnet structure. Figure from the abstract: FIGURE 12

Description

Title of the invention: Method for manufacturing a magnet structure with several unit magnets

[0001] This application is filed under priority of application FR2101152 filed on 02 / 05 / 2021 and application FR2106912 filed on 06 / 28 / 2021.

[0002] The present invention relates to a method for manufacturing a magnet structure with several unitary magnets as well as a magnet structure obtained by this method and an electromagnetic motor or generator equipped with at least one such magnet structure.

[0003] The present invention finds an advantageous but non-limiting application for a rotary electromagnetic actuator delivering high power with a high rotor rotation speed, which is obtained by the use of one or more magnet structures according to the present invention.

[0004] Thus, advantageously but not limitatively, the actuator may be a rotary actuator which may comprise at least one rotor framed by two stators, these elements being able to be superimposed on each other while being separated by at least one air gap on the same shaft.

[0005] In high-speed applications, it is necessary to have not only a compact system made possible by reducing the mass and size of the electromagnetic actuator for optimal efficiency, but also very good mechanical strength of the rotating or translational part, i.e. the rotor or the element in linear translation, in order to improve the reliability of the system.

[0006] For a high-power motor, the rotor rotates at high rotational speeds. The main disadvantage of a high-speed motor is the high probability of detachment of the magnet or magnets from the rotor as well as at least partial breakage of the rotor. The rotor of such a motor must therefore be able to withstand high rotational speeds.

[0007] It is also necessary to reduce electromagnetic losses, particularly eddy currents, in order to obtain optimal efficiency.

[0008] For an axial flux motor, these losses can occur in the rotor(s) of the electric motor or in the magnets.

[0009] With respect to rotors, eddy current losses in magnets have been considerably reduced, notably by proposing ironless rotors or by proposing magnet poles consisting of a plurality of small unit magnets. dimensions consisting of a plurality of unit magnets. Each unit magnet is in the form of an elongated stud having a length extending along the thickness of the magnet structure.

[0011] The unit magnets are positioned in the magnet structure, grouped together while maintaining a minimum distance from each other in order to be electrically isolated from each other.

[0012] Such a configuration has given great satisfaction in terms of reducing eddy current losses. However, it requires a complicated manufacturing process due to the need to position and maintain the individual magnets relative to each other during the implementation of the process.

[0013] Indeed, during a method of manufacturing a magnet structure with several unitary magnets according to this state of the art, when the unitary magnets are not secured to each other before a layer of composite unites them, these unitary magnets are difficult to maintain in position. The presence of a mesh to maintain the unitary magnets may thus be required, which complicates the method of manufacturing the magnet structure.

[0014] Furthermore, it has been found that the mechanical strength of such a magnet structure needs to be increased in specific usage situations.

[0015] To reduce these drawbacks, it has also been proposed to locally join the unit magnets by forming a plane heel common to all the unit magnets, the plane heel being located at a high or low end of the magnet structure.

[0016] Thus, according to this second state of the art, it could be necessary to cut the blank of the magnet structure leaving a heel at a high or low end of the magnet structure for holding the unit magnets, to inject a composite around the unit magnets, to cut the heel then to inject composite a second time through the end having carried the heel.

[0017] Document CN112039238(A) describes a three-dimensional magnet structure including a height. The magnet structure has cutouts extending along the height of the magnet structure and forming groups of cutouts, the cutouts of each group being interrupted, each forming two parts in the direction of the height of the cutout and leaving a gap filled with material between the two parts of the same cutout.

[0018] The material-filled intervals of a group of cutouts form a portion of a member which can be likened to a single-piece heel common to all the groups of cutouts, the cutouts delimiting between them unitary magnets held together by the heel.

[0019] In this document CN112039238(A), the cutouts are in the form of shallow grooves. The space filled with material between two opposite grooves each on one of two opposite sides of the magnet structure forming the heel-like member extends over a very large part of the height of the magnet structure.

[0020] This has the disadvantage that the reduction of eddy currents which was nevertheless the aim of document CN112039238(A) is weakened due to the non-separation of the unit magnets by cutting.

[0021] Furthermore and above all, document CN112039238(A) describes a structure and not its manufacturing method.

[0022] The problem underlying the present invention is to make the manufacture of a magnet structure comprising multiple unit magnets easier to implement while guaranteeing the magnet structure high mechanical strength and optimal magnetic properties.

[0023] To this end, the present invention relates to a method for manufacturing a three-dimensional magnet structure including a height, characterized by the following steps: - creating in a blank of the magnet structure at least two groups of cutouts in the direction of the height of the magnet structure, the cutouts of each group being interrupted in height, each forming two parts and leaving an interval filled with material from the blank between the two parts of the same cutout, said at least two groups of cutouts delimiting unit magnets in the blank, the intervals filled with material from the cutouts forming an internal heel in the blank securing the unit magnets together, the intervals filled with material having a height of between 2 and 20% of a total height of the cutouts, - injecting composite into the cutouts in a single injection to obtain the final magnet structure.

[0024] This results in simplified manufacturing of the magnet structure. This is the first advantage obtained by implementing a method according to the invention.

[0025] In a method according to the invention, it is not necessary to cut the heel which remains permanently in the magnet structure, the heel being defined as internal to the structure.

[0026] The first advantage of the present invention lies in the fact that the injection is carried out in a single step simultaneously above and below the magnet structure.

[0027] There is therefore no need to cut an external heel to the structure as proposed in a prior art before injection.

[0028] The second advantage of the present invention is that the magnet structure thus manufactured is reinforced due to the presence of the heel internally of the magnet structure, while making it possible to reduce eddy currents in the magnet structure.

[0029] The height of the gaps filled with material which corresponds to the thickness of the heel must meet two contradictory requirements.

[0030] Firstly, this height of the material-filled gaps must be large enough to reinforce the solidity of the magnet structure and the bonding of the individual magnets to each other.

[0031] Secondly, and in contradiction with the first requirement, this height of the gaps filled with material must be sufficiently low so as not to increase eddy current losses.

[0032] The applicants found that a range of 2 to 20%, preferably 2 to 10%, of the total height of the cutouts met these two requirements.

[0033] Advantageously, said at least two groups of cutouts each have their cutouts extending parallel to each other in a section perpendicular to the height of the blank, the parallel cutouts of one group extending in a different direction than the parallel cutouts of at least one other of said at least two groups of cutouts.

[0034] Advantageously, the cutouts pass right through the magnet structure in a plane perpendicular to the height of the blank, a group of cutouts intersecting with at least one other group of cutouts of said at least two groups of cutouts or a group of cutouts being extended by at least one other group of cutouts of said at least two groups of cutouts around each unit magnet.

[0035] For example, for a rectangular or square section of the magnet structure, the groups of cutouts form a grid by intersecting each other.

[0036] In another configuration, for example for a hexagonal section of the magnet structure with hexagonal unit magnets and more broadly for a section with more than four sides, the cutouts of a group of cutouts along one of the sides are completed by cutouts along two or more other sides.

[0037] Advantageously, at least one gap filled with material of a cutout of a group is at a different height from at least one gap filled with material between a cutout of another group of said at least two cutting groups.

[0038] This makes it possible to have a heel having steps with the advantages which will be mentioned later with regard to the magnet structure comprising such a heel.

[0039] Advantageously, at least one gap filled with material of a cutout of a group is at a different height from at least one gap filled with material between another cutout of the same group.

[0040] This results in heel portions associated with the same group of cutouts having steps, which gives a common heel with even more steps than for groups of cutouts each having cutouts with intervals filled with material at the same height.

[0041] Advantageously, the intervals filled with material have the same dimension taken in the height of the magnet structure for all the cutting groups.

[0042] Advantageously, the intervals filled with material are located in an area framing with more or less 20% a half-height of the magnet structure.

[0043] Providing a heel at mid-height of the unit magnets reinforces the solidity of the magnet structure by equalizing its support in its upper and lower parts.

[0044] Advantageously, for a blank of the magnet structure having a larger cross-section than the magnet structure to be manufactured, groups of cutouts are produced delimiting a first set of unit magnets of equal dimensions and, when the dimensions of the blank do not allow unit magnets of the first set to be positioned at a periphery of the blank, a group of auxiliary cutouts is created delimiting, by removing material from the blank to give it the cross-section of the magnet structure, a second set of peripheral unit magnets of smaller cross-section than the dimensions of the unit magnets of the first set then being formed.

[0045] This makes it possible to place as many unit magnets as possible in the magnet structure by reducing the section of unit magnets positioned at the periphery of the magnet structure.

[0046] The invention also relates to a magnet structure manufactured in accordance with a method as described above, the magnet structure being in three dimensions including a height, characterized in that it has cutouts extending along the height of the magnet structure and forming groups of cutouts, the cutouts of each group being interrupted, each forming two parts in the direction of the height of the cutout and leaving a gap filled with material between the two parts of the same cutout, the gaps filled with material of the groups of cutouts forming a heel of a single common piece internal to the magnet structure, the cutouts delimiting between them unitary magnets held together by the heel.

[0047] In the first state of the art mentioned, it had been proposed to replace one or more large magnets with a plurality of small magnets. In this case, there is a creation of magnetic flux by a multitude of small magnets, the number of which may be at least 20 and may even exceed 100 per magnet pole.

[0048] A magnet structure according to the present invention intends to retain these advantages while still making each magnet structure stronger and easier to manufacture.

[0049] In a magnet structure according to the invention, the individual magnets, before being secured to each other by a layer of composite, are held in position given that a heel internal to the structure joins them together.

[0050] As this heel remains permanently in the magnet structure, the mechanical resistance of the structure does not depend only on the composite layer between the magnets but is reinforced by the presence of this heel in one piece with all the unit magnets.

[0051] More particularly, a magnet structure according to the present invention finds a preferential and non-limiting application in the case where the magnet structure has two groups of unit magnets, namely a first set of unit magnets and a second set of unit magnets smaller than those of the first set and which are distributed at a periphery of the magnet structure.

[0052] In such a magnet structure, the fact that the unit magnets of the second set at the periphery are also secured to each other and likewise to the unit magnets of the first set by a common heel, prevents their detachment from the magnet structure especially when this magnet structure is not entirely coated with a layer of composite over its entire periphery.

[0053] Indeed, for these peripheral unit magnets, holding the unit magnets by gluing may prove insufficient mainly due to their reduced section and their positioning at the periphery of the magnet structure.

[0054] This, in a magnet structure according to the present invention, is compensated for by the presence of a common heel between all the unit magnets securing all the unit magnets together.

[0055] Advantageously, at least one material-filled gap between a cutout of one group is at a different height than at least one material-filled gap between a cutout of another group so that the heel extends over at least two different height levels in the magnet structure.

[0056] The applicants have in fact found that the presence of a plane heel common to the unit magnets in the magnet structure could cancel out or significantly reduce all the advantages provided by the use of unit magnets, in particular by the appearance of eddy current losses. In this case, such a common plane heel proves to be very profitable during the manufacture of a magnet structure but not optimal for the magnet structure itself.

[0057] The applicants have however observed that a heel, made from a single piece of magnetized material but also composed of successive heel portions specific to groups of cutouts, these successive heel portions extending at different heights in the magnet structure and thus giving the assembly a shape which can be zig-zag by not extending in a single plane, made it possible to retain the advantages provided by the use of unitary magnets in the magnet structure while reinforcing the solidity of the magnet structure.

[0058] Thus, according to an optional feature of a magnet structure according to the present invention, as opposed to a planar heel connecting the unit magnets, the heel portions are of a single piece but extend at different levels in the magnet structure depending on their group of cutouts.

[0059] There are therefore differences in height level or steps between two adjacent edges of successive heel portions associated with two different groups of cuts.

[0060] It has been found that these height level differences or height jumps make it possible to reduce eddy current losses compared to a magnet structure comprising a flat heel, these losses being substantially equivalent to those of unit magnets not having a heel.

[0061] A non-planar heel in a magnet structure, an optional feature of the present invention, therefore makes it possible to combine the advantages of a heel magnet structure, namely ease of manufacture associated with greater retention of the unit magnets, with the advantages of a magnet structure with independent unit magnets, advantages which have been previously cited. This is achieved without increasing eddy currents in the magnet structure.

[0062] The heel thus formed is of the same magnetic material as the unit magnets, the whole being obtained by working from a blank of the magnet structure in magnetic material.

[0063] Advantageously, the magnet structure has a triangular or trapezoidal section.

[0064] Such a configuration may require the use of two sets of unit magnets, including peripheral unit magnets of smaller cross-section than another set of unit magnets, this configuration also meeting the desired external shape for a magnet structure.

[0065] Thus, the present invention makes it possible to solve the specific problems posed by a triangular or trapezoidal section of a magnet structure, which is a frequent configuration for such a structure.

[0066] Advantageously, a ratio of a section of a unit magnet to a section of the magnet structure is less than 20%, a perimeter of each unit magnet being less than the height of the unit magnet.

[0067] This increases the advantages provided by unit magnets. The smaller the cross-section of the unit magnets with more unit magnets in the magnet structure, the greater the advantages of using unit magnets previously mentioned.

[0068] The invention finally relates to a linear or rotary electromagnetic motor or generator, characterized in that it comprises a single magnet structure or several magnet structures as previously described, the magnet structure(s) forming magnet poles in a rectangular array or forming part of a rotor rotating around its center, the magnet structure(s) being arranged concentrically to the rotor.

[0069] Such a motor may advantageously be an axial flux motor.

[0070] For example, for an axial flux motor, one or more prior art rotors could include 1 to 10 large magnets forming magnet poles whereas the present invention provides many more small magnets in each magnet structure forming a magnet pole.

[0071] It is appropriate not to confuse a magnet pole, a rotor being able to carry for example five to ten or even more, with the unit magnets which are significantly more numerous, a rotor being able to carry for example several hundred. It is also appropriate not to confuse the unit magnets used in a magnet structure according to the invention by being grouped in a bouquet with one or more magnet bars forming a magnet structure according to the state of the art, the dimension of a unit magnet in a magnet structure according to the present invention not being comparable to a bar.

[0072] This makes it possible to obtain a rotor which, among other advantages, can rotate at high speed and which does not include iron, which limits rotor losses.

[0073] Additionally, due to a heel extending internally within the or each magnet structure, the strength of the or each magnet structure is enhanced while the previously mentioned advantages obtained by employing multiple unit magnets within the magnet structure are retained.

[0074] The attached drawings illustrate the invention:

[0075] [Fig-1] represents a perspective view of a magnet structure according to a first embodiment of the present invention,

[0076] [Fig.2] represents a sectional view along arrow A of the magnet structure shown in [Fig.l],

[0077] [Fig.3] represents a sectional view along arrow B of the magnet structure shown in [Fig.l],

[0078] [Fig.4] represents a perspective view of a magnet structure according to a second embodiment of the present invention,

[0079] [Fig.5] represents a sectional view along arrow A of the magnet structure shown in [Fig.4],

[0080] [Fig.6] represents a sectional view along arrow B of the magnet structure shown in [Fig.4],

[0081] [Fig.7] represents a perspective view of a magnet structure according to a third embodiment of the present invention,

[0082] [Fig.8] represents a sectional view along arrow A of the magnet structure shown in [Fig.7],

[0083] [Fig.9] represents a sectional view along arrow B of the magnet structure shown in [Fig.7],

[0084] [Fig. 10] represents a sectional view of the injection machine for implementing the method, the injection not yet being carried out in a blank of magnet structure,

[0085] [Fig. 11] represents a sectional view of the injection machine for implementing the method, the injection being finished,

[0086] [Fig. 12] represents a sectional view of the injection machine for implementing the method, the injection being completed,

[0087] [Fig. 13] shows a front view of a rotor which can be associated with a magnet structure as shown in Figures 1 to 9 in order to form an electromagnetic motor or generator in accordance with the present invention.

[0088] In the following, reference is made to all figures taken in combination. When reference is made to one or more specific figures, these figures are to be taken in combination with the other figures for the recognition of the designated numerical references.

[0089] In the figures, when present, only one unit magnet is referenced 2 or 2a and only one magnet structure or magnet pole is referenced 1 but what is stated respectively for the unit magnet 2, 2a and the magnet structure or pole 1 is valid respectively for all the unit magnets and the magnet structures.

[0090] Referring to all the figures, the invention relates to a method of manufacturing a magnet structure 1 with multiple unit magnets 2, 2a, the magnet structure 1 being in three dimensions including a height.

[0091] A unit magnet 2a is a unit magnet of smaller cross-section than one of the most common unit magnets in the magnet structure 1, the unit magnet of smaller cross-section 2a frequently being a peripheral magnet in the magnet structure 1.

[0092] The essential step of the method according to the invention is the creation in a blank 15 of magnet structure of at least two groups of cutouts in the direction of the height of the magnet structure 1.

[0093] The cutouts of each group are interrupted by each forming two parts 3, 4; 5, 6 in the direction of the height of the cutout and by leaving a gap filled with material between the two parts 3, 4; 5, 6 of the same cutout.

[0094] The two or more groups of cutouts delimit unit magnets 2, 2a in the blank, at least partially for the peripheral unit magnets 2a of smaller section.

[0095] The gaps filled with material of the cutouts form an internal heel 7a, 7b on the blank securing the unit magnets 2, 2a together. The gaps filled with material have a height between 2 and 20% of the total height of the cutouts, i.e. sufficient to ensure the internal maintenance of the magnet structure but not penalizing with regard to the creation of eddy currents.

[0096] Internal means that the heel is not at the periphery of the magnet structure 1 and will remain permanently in the magnet structure 1 after injection of composite into the cutouts.

[0097] The heel is made of the same magnetic material as the unit magnets 2, 2a and is made of a single piece with the unit magnets 2, 2a.

[0098] The blank 15 of the magnet structure may have the same external shape as the magnet structure 1 to be obtained or a larger external shape.

[0099] It is possible to make the cuts using several cutting methods, for example, without this being limiting, by electroerosion or wire cutting or equivalent or by using a laser. For complex shapes with more than four sides, it is possible to use a cutting bell for all the cuts.

[0100] According to an essential step of the present invention, a composite injection is carried out into the cutouts in a single injection to obtain the final magnet structure 1, this without any added means of holding the unit magnets 2, 2a together, the heel 7a, 7b being in one piece with the unit magnets 2, 2a and fulfilling this role.

[0101] By way of example, the injected composite may be thermosetting polymers, such as epoxies, silicones, in any applicable form, for example in the form of glue, resin, single-component or two-component casting, or even thermoplastic polymers.

[0102] such as Nylon or PPS (Polyphenylene sulfide).

[0103] Figures 10 to 12 show an injection machine 11 for implementing the method according to the invention with a movable upper plate 14 and a fixed lower plate 16. A piston 12 presses the composite 13 through an injection column towards the matrix located between the upper plate 14 and the lower plate 16, the matrix containing the blank 15 of the magnet structure previously cut during the first step of the method.

[0104] In [Fig. 10], the injection has not yet started and the piston 12 has not yet been introduced into the injection column.

[0105] In [Fig. 11], the injection has started and the piston 12 presses the composite 13 in the injection column towards the blank 15 of the magnet structure 1.

[0106] In [Fig. 12], the injection is complete and the piston 12 has reached its low point in the injection column. The composite has penetrated into all the interrupted cutouts of the blank 15 of the magnet structure 1, both in the upper and lower parts of the cutouts under the pressure of the piston, the portion of the composite 13 penetrating into the lower cutouts going around the blank 15.

[0107] In Figures 10 to 12, the upper and lower portions, black vertical lines in the blank 15 in Figures 10 to 12 are separated by a heel interposed between each upper vertical black line and its lower vertical black line.

[0108] Referring mainly to Figures 1 to 9, the present invention also relates to a three-dimensional magnet structure 1 including a height.

[0109] This magnet structure 1 may be of triangular section, therefore with three sides, square or rectangular, therefore with four sides, or polygonal with a number of sides greater than or equal to 4, in particular trapezoidal. When present, opposite sides of the magnet structure 1 are not necessarily parallel.

[0110] It is also possible for the magnet structure to be of circular section while being of cylindrical shape. The same will apply to the unit magnets that make up this cylindrical magnet structure.

[0111] Such a magnet structure 1 comprises a large number of unit magnets 2, 2a, this number being at least 20 unit magnets 2, 2a and possibly reaching several hundreds.

[0112] These unit magnets 2, 2a are grouped together to form a bouquet or cluster with each unit magnet 2, 2a surrounded on all sides by other unit magnets 2, 2a, except for the unit magnets 2a arranged at the periphery of the magnet structure 1 which are only partially surrounded by other unit magnets 2.

[0113] This configuration is common with a magnet structure disclosed by document EP3602743 A1 but cannot be compared with a magnet structure disclosed by document FR3004025 A1 in which the unit magnets are in the form of bars not grouped in a bouquet but form a succession of bars positioned consecutively one after the other.

[0114] Such a magnet structure according to the invention has its unit magnets 2, 2a extending between a front face and a rear face of the magnet structure 1.

[0115] These front and rear faces of the magnet structure 1 are recognizable from the other faces of the magnet structure 1 by having a larger surface area than the lateral faces of the magnet structure 1 and by being intended in particular to each open onto a working face of the support carrying it in a motor or an electromagnetic generator, as can be seen in [Fig. 13].

[0116] According to an essential characteristic of the present invention, during its manufacture, the magnet structure 1 has cutouts extending along the height of the magnet structure 1 and forming groups of cutouts, as seen more particularly in Figures 1, 4 and 7.

[0117] The cutouts of each group are interrupted by each forming two parts 3, 4; 5, 6 in the direction of the height of the cutout. A gap filled with material then remains between the two parts 3, 4; 5, 6 of the same cutout, the material of the interval also being magnetic because it comes from the magnet structure 1.

[0118] The material-filled intervals of a group of cuts form a portion of a heel 7a, 7b. This heel will be a single piece and common to all the groups of cuts, while retaining specificities for each group of cuts.

[0119] The cutouts of different groups can intersect as in the case of a magnet structure 1 with a square or rectangular or trapezoidal section, the latter shape being shown in particular in figures 1, 4 and 7.

[0120] All the cutouts taken together delimit between them unitary magnets 2, 2a held together by the heel consisting of several heel portions 7a, 7b associated with different groups.

[0121] In implementing the method, on the blank 15 placed in a vertical position, the cuts can be made simultaneously from the top and bottom of the blank 15. This has the advantage of speed of cutting but requires two cutting devices.

[0122] Alternatively, the cuts can be made by making one of the two parts 3, 5 of each cut and then turning the blank 15 over in order to make the other of the two parts 4, 6. This has the advantage of using only one cutting device but requires handling of the blank 15 between the two cuts.

[0123] As can best be seen in Figures 1, 4 and 7, the cutouts of the same group of cutouts may extend parallel to each other, this in a section perpendicular to the height of the blank. In this case there is another group of cutouts comprising cutouts which extend perpendicular to the cutouts of the first group.

[0124] The cutouts can pass right through the magnet structure 1, that is to say in the two dimensions of the magnet structure 1 other than its height, extending from one side of the magnet structure 1 to another side opposite it.

[0125] A group of cutouts associated with one side may intersect with at least one group of cutouts associated with another side. An interruption of the cutouts exists, however, in the direction of the height of the magnet structure 1, which forms an internal heel to the magnet structure 1.

[0126] Another configuration, not shown in the figures, in which a group of cutouts is extended by at least one other group of cutouts around each unit magnet is also possible.

[0127] Optionally but preferably, at least one gap filled with material between a cutout of a group may be at a different height from at least one gap filled with material between a cutout of another group of cutouts.

[0128] This gives an internal non-planar heel to the magnet structure 1 which is favorable for a reduction of eddy currents in the magnet structure 1.

[0129] As a result, the heel portions 7a, 7b of the different groups of cutouts extend at least partially over different height levels in the magnet structure 1 and provide a common heel with steps.

[0130] Without this being limiting and being purely illustrative, the unit magnets 2, 2a may be in the form of elongated studs, essentially of rectangular or polygonal section, connected to each other by a 1 millimeter heel which may be positioned at mid-height of the unit magnet 2, 2a and therefore of the magnet structure 1.

[0131] The present invention proposes as an optional configuration of a magnet structure 1 with unit magnets 2, 2a, a securing by a staggered internal heel extending at various heights in the magnet structure 1.

[0132] Experiments carried out by the applicants have shown that the configuration most favorable to the reduction of eddy current losses was a magnet structure 1 with unit magnets not comprising a heel, in accordance with the configuration of the state of the art mentioned in the introductory part of the present application.

[0133] The eddy current losses with a magnet structure 1 without unit magnets 2, 2a, therefore in the form of a single large magnet, are at least 60 times higher than for a structure with unit magnets 2, 2a without a heel.

[0134] The eddy current losses with a magnet structure 1 with unit magnets 2, 2a secured by a flat heel are at least 9 times higher than for a structure with unit magnets 2, 2a without heel.

[0135] On the other hand, the optional configuration according to the present invention with a magnet structure 1 with unit magnets 2, 2a secured by a staggered heel extending at various heights in the magnet structure 1 has losses that are barely higher than for the magnet structure 1 with unit magnets 2, 2a not secured by magnetized material by not having a heel, these losses then being only 1.16 times higher than for the magnet structure 1 without a heel.

[0136] This increase in eddy current losses is however clearly offset by the ease of manufacturing such a magnet structure 1 according to the invention and its improved mechanical resistance.

[0137] When manufacturing a magnet structure 1 with unit magnets 2, 2a not secured by a heel, whether flat or with steps, before an injection of composite between the unit magnets 2, 2a to hold them together, these unit magnets 2, 2a tend to move away from each other.

[0138] Furthermore, even with composite injection between the unit magnets 2, 2a, such a magnet structure 1 with unit magnets 2, 2a not secured by a heel will have less mechanical strength than the magnet structure 1 proposed by the present invention. invention, the flat or staggered heel connecting all the unit magnets 2, 2a by being made of magnetized material in a single piece with the unit magnets 2, 2a considerably reinforcing the mechanical resistance of the magnet structure 1.

[0139] Optionally, at least one material-filled gap of a cutout of a group may be at a different height than at least one material-filled gap between another cutout of the same group, which increases the steps in the heel common to all the unit magnets 2, 2a.

[0140] The gaps filled with material can have the same dimension taken in the height of the magnet structure 1 for all the cutting groups, which gives a heel of constant thickness.

[0141] The intervals filled with material may be located in an area framing with more or less 20% a half-height of the magnet structure 1.

[0142] Figures 11 3, 4 to 6, 7 to 9 respectively show an embodiment of a magnet structure 1. These figures show a magnet structure 1 of trapezoidal section but this is not limiting.

[0143] In Figures 1 and 4, the peripheral edge unit magnets 2a of the magnet structure 1 are cut to have a smaller cross-section than the unit magnets 2 arranged more centrally in the magnet structure 1. In [Fig.7], the peripheral edge unit magnets are not cut and have the same cross-section as the other unit magnets 2.

[0144] When manufacturing a magnet structure 1 according to the present invention, in a first optional mode, as shown in Figures 1 to 6 and 10 to 12, for a blank 15 of the structure having the same section as the magnet structure 1 to be manufactured, groups of cutouts may be created delimiting a first set of unit magnets 2 of equal dimensions.

[0145] When the dimensions of the blank 15 do not allow unit magnets 2 of the first set to be positioned at a periphery of the blank 15, the cutting can delimit a second set of peripheral unit magnets 2a of smaller section than the dimensions of the unit magnets 2 of the first set.

[0146] In this configuration, the unit magnets 2, 2a of the first and second sets are always secured to each other by the internal heel 7a, 7b.

[0147] When the dimensions of the blank 15 do not allow unit magnets 2 of the first set to be positioned at a periphery of the blank 15, a group of auxiliary cutouts may be created, delimiting them by removing material from the blank 15 to give it the section of the magnet structure 1.

[0148] A second set of peripheral unit magnets 2a of smaller section than the dimensions of the unit magnets 2 of the first set is then formed while being partially limited by the auxiliary cutouts. The auxiliary cutouts are complete in the height direction of the magnet structure 1 for material removal in order to reduce the size of the blank 15 to the desired size for the magnet structure 1.

[0149] In the configurations of Figures 1 to 9, the longitudinal cutouts are defined as extending perpendicular to the two bases of the trapezium formed by the magnet structure 1, the lateral cutouts being defined as extending parallel to the two bases.

[0150] In Figures 1 and 4, after auxiliary cutouts, unit magnets 2a on the edge are of triangular section, the other unit magnets 2 being of square section. In [Fig.7], all the unit magnets 2 have the same square section.

[0151] In Figures 1 to 9, the height cutouts extending across the width of the magnet structure 1, called lateral cutouts, have two parts referenced 5, 6. The lateral cutouts are all interrupted at the same height level, but this is not obligatory.

[0152] Between the parts 5, 6 of these lateral cutouts is formed a lateral heel part 7b by the gap filled with material remaining between the two parts 5, 6 of these lateral cutouts.

[0153] The height cutouts extending along the length of the magnet structure 1, called longitudinal cutouts, have two parts referenced respectively 3 and 4 and are all interrupted at the same height level but at a different height from the lateral cutouts.

[0154] Between the parts 3, 4 of these longitudinal cutouts is formed a longitudinal heel part 7a by the gap filled with material remaining between the two parts of these longitudinal cutouts.

[0155] In Figures 2, 5 and 8 which show a view along arrow A of Figures 1, 4 and 7, there is illustrated a line 8a showing the lower end of the upper part 3 of the longitudinal cutouts and a line 8b showing the upper end of the lower part 4 of the longitudinal cutouts. Lines 8a, 8b delimit between them a longitudinal heel part 7a.

[0156] In Figures 3, 6 and 9 which show a view along arrow B of Figures 1, 4 and 7, there is also illustrated a line 9a showing the lower end of the upper part 5 of the lateral cutouts and a line 9b showing the upper end of the lower part 6 of the longitudinal cutouts. Lines 9a, 9b delimit between them a lateral heel part 7b.

[0157] It follows that, in the embodiment of Figures 1 to 9, all the lower ends of the longitudinal or respectively lateral cutting parts are aligned with each other for each group and all the upper ends of the longitudinal or respectively lateral cutting parts are aligned with each other for a same group of cuts.

[0158] If, in these figures there are only two heel heights, there may be other heel height levels when longitudinal and / or lateral cutouts stop at different heights from the other cutouts of the same group, either longitudinal or lateral.

[0159] A heel common to all the unit magnets 2, 2a is therefore composed of a lateral heel part 7b and a longitudinal heel part 7a. The common heel can therefore be staggered over two heights in the magnet structure 1.

[0160] For all these embodiments, in the vertical position of maintaining the height of the magnet structure 1, it may be possible but not obligatory for an interval filled with material between the cutout of a group, for example a group of lateral cutouts forming a lateral heel portion 7b to have its highest end at a height equal to the height of a lowest end of an interval filled with material between the cutout of another group, for example a group of longitudinal cutouts forming a longitudinal heel portion 7a.

[0161] Referring to all the figures, for all the embodiments, the gaps filled with material can have the same dimension taken in the height of the magnet structure 1 for all the cutting groups.

[0162] The invention also relates to a linear or rotary electromagnetic motor or generator comprising a single magnet structure 1 or several magnet structures as previously described.

[0163] The magnet structure(s) form magnet poles in a rectangular array for a linear electromagnetic motor or as part of a rotor rotating around its center for a rotary electromagnetic motor. In the latter configuration, the magnet structure(s) are arranged concentrically to the rotor.

[0164] In this configuration, the unit magnets are aligned to form a compact group in the form of a bouquet such that their length passes through the rotor. A front face of the magnet structure 1 opens onto one face of the rotor while the rear face opens onto the opposite face of the rotor.

[0165] [Fig. 13] shows such a rotor 18 with a plurality of magnet structures 1. In an electromagnetic machine according to the present invention, the or each rotor 18 may comprise a plurality of magnet structures 1 as magnet poles, only one of which is referenced in [Fig. 13].

[0166] The or each rotor 18 may be made of composite to reduce iron losses.

[0167] Each magnet pole which is in the form of a magnet structure 1 can be consisting of a plurality of unit magnets 2 secured to each other, by composite, glue or resin in addition to being secured by the heel common to all the unit magnets 2 and internal to the magnet structure 1.

[0168] Additionally, to enhance the strength of the magnet pole, each magnet pole may be individually coated in a layer of composite. This is shown in [Fig. 13] for a magnet structure 1 that has been blackened.

[0169] Finally, the entire rotor 18 may also be coated in a layer of composite with or without the inclusion of a covering disk preventing axial movement of the magnet structures 1 or the unit magnets 2.

[0170] With regard to [Fig. 13], a rotary electromagnetic motor with axial flux has been described above, but the present invention can be applied to any type of motor, in particular a radial flux or mixed rotary or linear flux motor or generator.

Claims

Claims

1. Method for manufacturing a three-dimensional magnet structure (1) including a height, characterized by the following steps: - creating in a blank (15) of magnet structure at least two groups of cutouts in the direction of the height of the magnet structure (1), the cutouts of each group being interrupted in height, each forming two parts (3, 4; 5, 6) and leaving an interval filled with material of the blank (15) between the two parts (3, 4;5, 6) of the same cutout, the cutouts of the different groups intersecting, said at least two groups of cutouts delimiting unit magnets (2, 2a) in the blank (15), the intervals filled with material of the cutouts forming an internal heel (7a, 7b) to the blank (15) securing the unit magnets (2, 2a) together, the intervals filled with material having a height of between 2 and 20% of a total height of the cutouts and - injection of composite into the cutouts in a single injection to obtain the final magnet structure (1).;

2. Method according to the preceding claim, in which, on the blank (15) placed in a vertical position, the cuts are made simultaneously from the top and the bottom of the blank (15) or the cuts are made by making one of the two parts (3, 4; 5, 6) of each cut and then turning the blank (15) over in order to make the other of the two parts.

3. A method according to any one of the preceding claims, wherein said at least two groups of cuts each have their cuts extending parallel to each other in a section perpendicular to the height of the blank (15), the parallel cuts of one group extending in a different direction than the parallel cuts of at least one other of said at least two groups of cuts.

4. Method according to the preceding claim, in which the cutouts pass right through the magnet structure (1) in a plane perpendicular to the height of the blank (15), a group of cutouts intersecting with at least one other group of cutouts of said at least two groups of cutouts or one group of cutouts being extended by at least one other group of cutouts of said at least two groups of cutouts around each unit magnet (2, 2a).

5. Method according to any one of the preceding claims, in which the gaps filled with material have the same dimension taken in the height of the magnet structure (1) for all the cutting groups.

6. Method according to any one of the preceding claims, in which the gaps filled with material are located in an area framing with more or less 20% a half-height of the magnet structure (1).

7. Method according to any one of the preceding claims, in which, for a blank (15) of the magnet structure (1) having a larger section than the magnet structure (1) to be manufactured, groups of cutouts are produced delimiting a first set of unit magnets (2) of equal dimensions and, when the dimensions of the blank (15) do not allow unit magnets (2) of the first set to be positioned at a periphery of the blank (15), a group of auxiliary cutouts is created delimiting, by removing material from the blank (15) to give it the section of the magnet structure (1), a second set of peripheral unit magnets (2a) of smaller section than the dimensions of the unit magnets (2) of the first set then being formed.

8. Magnet structure (1) manufactured in accordance with a method according to any one of the preceding claims, the magnet structure (1) being in three dimensions including a height, characterized in that it has cutouts extending along the height of the magnet structure (1) and forming groups of cutouts, the cutouts of each group being interrupted by each forming two parts (3, 4; 5, 6) in the direction of the height of the cutout and by leaving a gap filled with material between the two parts (3, 4; 5, 6) of the same cutout, the gaps filled with material of the groups of cutouts forming a heel (7a, 7b) of a single common piece internal to the magnet structure (1), the cutouts of the different groups intersecting, the cutouts delimiting between them unitary magnets (2, 2a) held together by the heel (7a, 7b).

9. Magnet structure (1) according to the preceding claim, wherein at least one material-filled gap between a cutout of one group is at a different height than at least one material-filled gap between a cutout of another group so that the heel (7a, 7b) extends over at least two different height levels in the magnet structure (1).

10. Magnet structure (1) according to the preceding claim, wherein at least one material-filled gap of a cutout of a group is at a different height from at least one material-filled gap between another cutout of the same group.

11. Magnet structure (1) according to any one of the two preceding claims, which has a triangular or trapezoidal section.

12. Magnet structure (1) any one of the preceding three claims, wherein a ratio of a section of a unit magnet (2, 2a) to a section of the magnet structure (1) is less than 20%, a perimeter of each unit magnet (2, 2a) being less than the height of the unit magnet (2, 2a).

13. Linear or rotary electromagnetic motor or generator, characterized in that it comprises a single magnet structure (1) or several magnet structures according to any one of the four preceding claims, the magnet structure(s) (1) forming magnet poles in a rectangular assembly or forming part of a rotor (18) rotating around its center, the magnet structure(s) (1) being arranged concentrically to the rotor (18).

Images