MAGNETIC STRUCTURE WITH A NUMBER OF SINGLE MAGNETS WITH REINFORCED CONNECTION

Description

[0001] The present invention relates to a magnet structure with several unit magnets with reinforced bonding between the magnets and to an electromagnetic motor or generator equipped with at least one such magnet structure.

[0002] The present invention finds an advantageous but not limiting application for a rotary electromagnetic actuator delivering high power with a high rotor rotation speed, which is obtained by using one or more magnet structures according to the present invention.

[0003] Thus, advantageously but not limitingly, the actuator can be a rotary actuator comprising at least one rotor framed by two stators, these elements being able to overlap each other while being separated by at least one air gap on the same shaft.

[0004] 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 translating part, i.e. the rotor or the linearly translating element, in order to improve the reliability of the system.

[0005] In a high-power motor, the rotor spins at high speeds. The main disadvantage of a high-speed motor is the high probability of the rotor magnet(s) detaching and at least partially breaking the rotor. Therefore, the rotor of such a motor must be capable of withstanding these high speeds.

[0006] It is also necessary to reduce losses to obtain optimal yield.

[0007] For an axial flux motor, these losses can occur in the rotor(s) of the electric motor or in the magnets.

[0008] With regard to rotors, eddy current losses in magnets have been considerably reduced, notably by proposing ironless rotors or by proposing magnet poles made up of a plurality of small unit magnets.

[0009] For example, document EP3602743 (A1) proposes a three-dimensional magnet structure made up of a plurality of unit magnets. Each unit magnet is in the form of an elongated pad with a length extending according to the thickness of the magnet structure.

[0010] The individual magnets are positioned in the magnet structure at a distance from each other in order to be electrically insulated from each other.

[0011] This configuration has proven highly effective in reducing eddy current losses. However, it requires a complex manufacturing process due to the need for precise positioning of the individual magnets relative to one another. Furthermore, it has been found that the mechanical strength of such a magnet structure must be increased in certain operating conditions.

[0012] To mitigate these drawbacks, it has also been proposed to locally join the individual magnets by creating a common flat base for all the individual magnets, located halfway up the magnet structure. This solution has proven deficient in terms of losses per individual magnet, thus negating all the benefits of using individual magnets compared to a magnet pole composed solely of a single large magnet. Consequently, there is strong prejudice against the use of such a technique for joining individual magnets together in a magnet structure using a common base.

[0013] Document CN112039238(A) describes a three-dimensional magnet structure with 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 by each forming two parts in the direction of the cutout's height and leaving a space filled with material between the two parts of the same cutout.

[0014] The material-filled intervals of a group of cutouts form a portion of an organ that can be likened to a single-piece heel common to all groups of cutouts, the cutouts delimiting between them unitary magnets held together by the heel.

[0015] In this document CN112039238(A), the cutouts are in the form of shallow grooves. The space filled with material between pairs of grooves, each on one of two opposite sides of the magnet structure forming the heel-like element, extends over a very large portion of the magnet structure's height. This has the disadvantage that the reduction of eddy currents, which was the objective of document CN112039238(A), is weakened due to the lack of separation of the individual magnets by cutouts.

[0016] The problem underlying the present invention is to design a magnet structure for an electromagnetic actuator that can withstand high working speeds while providing a strong magnetic field, while being simple to manufacture and exhibiting high mechanical strength.

[0017] To this end, the present invention relates to a three-dimensional magnet structure having a height, the magnet structure having cutouts extending along the height of the magnet structure and forming groups of cutouts, the cutouts of each group being interrupted by each forming two parts in the direction of the height of the cutout and leaving a space filled with material between the two parts of the same cutout, the space filled with material of a group of cutouts forming a portion of a single-piece base common to all the groups of cutouts, the cutouts delimiting between them unit magnets held together by the base, where each space filled with material has a height of between 2 and 20% of a total height of the cutout, between the two parts of which said space remains,at least one material-filled gap between a cutout of one group located at a different height and at least one material-filled gap between a cutout of another group so that the heel portions of the different groups of cutouts extend at least partially over different height levels in the magnet structure.

[0018] It had been proposed to replace one or more large magnets with a plurality of small magnets. In this case, magnetic flux is therefore created by a multitude of small magnets, the number of which can be at least 20 and can even exceed 100 per magnet pole.

[0019] The present invention aims to retain these advantages while making each magnet structure even more robust. Indeed, the presence of a common base connecting the individual magnets reinforces this strength. A prior art review concerning magnet structures incorporating a common base revealed a prejudice against the use of this method of connecting individual magnets via a shared base.

[0020] It has indeed been observed that the presence of a common flat base for unit magnets in the magnet structure cancels out or significantly reduces all the advantages provided by the use of unit magnets, notably by the appearance of eddy current losses.

[0021] In a completely unexpected manner, the applicant observed that a heel, made of a single piece of magnetized material, but also composed of successive heel portions specific to groups of cuts, these successive heel portions extending at different heights in the magnet structure and thus giving the whole a shape that can be zig-zag by not extending in a single plane made it possible to retain the advantages provided by the use of unit magnets in the magnet structure while reinforcing the solidity of the magnet structure.

[0022] According to the present invention, unlike a flat base connecting individual magnets according to prior art, the base portions are continuous but extend to different levels within the magnet structure depending on their group of cutouts. Therefore, there are differences in height or steps between two adjacent edges of successive base portions associated with two different groups of cutouts.

[0023] It turned out that these differences in height level or height jumps made it possible to reduce eddy current losses compared to a magnet structure with a flat base, these losses being substantially equivalent to those of unit magnets without a base.

[0024] The height of the filled intervals, which corresponds to the thickness of the heel, must meet two contradictory requirements.

[0025] Firstly, the height of the gaps filled with material must be large enough to reinforce the strength of the magnet structure and the bonding of the individual magnets together.

[0026] Secondly, and in contradiction with the first requirement, this height of the intervals filled with material must be low enough not to increase eddy current losses.

[0027] The applicant found that a range of 2 to 20%, preferably 2 to 10%, for the height of the intervals filled with material relative to the total height of the cutouts met these two requirements.

[0028] The present invention therefore makes it possible to combine the advantages of a heel magnet structure, including 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 mentioned.

[0029] The heel thus formed is of the same magnetic material as the unit magnets, the whole being obtained by working from a rough draft of the magnet structure in magnetic material.

[0030] Advantageously, the cutouts pass completely through the magnet structure, extending from one side to the opposite side. A group of cutouts associated with one side intersects with at least one group of cutouts associated with another side, or a group of cutouts is extended by at least one other group of cutouts around the individual magnets. For example, for a rectangular or square section of the magnet structure, the groups of cutouts form a grid by intersecting.

[0031] 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 cuts of a group of cuts along one of the sides are complemented by cuts along two or more other sides.

[0032] Advantageously, the cuts of the same group of cuts extend parallel to each other.

[0033] Advantageously, the material-filled intervals have the same dimension taken in the height of the magnet structure for all cutting groups.

[0034] Advantageously, the cuts within the same group of cuts have their material-filled intervals at at least two different height levels. This results in heel portions associated with the same group of cuts exhibiting steps, giving a common heel with even more steps than for groups of cuts each having cuts with material-filled intervals at the same height.

[0035] Advantageously, in a vertical holding position of the height of the magnet structure, said at least one material-filled gap between the cut of one group has its highest end at a height equal to the height of a lowest end of said at least one material-filled gap between the cut of another group.

[0036] This is a preferred but not limiting embodiment of the present invention. This configuration exhibits the fewest eddy current losses.

[0037] Advantageously, the heel portions of the cutting groups extend at least partially over a number of height levels less than or equal to the number of sides of a unit magnet.

[0038] For example, for a rectangular or square section of the magnet structure, there are two groups of cutouts with cutouts in the first group perpendicular to cutouts in the second group.

[0039] 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 of unit magnets, there may be more than three different groups of cutouts, this number being at most equal to half the sides of the unit magnets.

[0040] Advantageously, each unit magnet undergoes an auxiliary cut extending along the height of the magnet structure and separating the unit magnet into two equal portions, the auxiliary cuts of the unit magnets also being interrupted by each forming two parts in the direction of the height of the magnet structure and leaving a space filled with material between the two parts of the same auxiliary cut.

[0041] Unit magnets with a triangular cross-section can thus be obtained from unit magnets with a square or rectangular cross-section.

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

[0043] Providing a mid-height support for the individual magnets reinforces the strength of the magnet structure by equalizing its support at the top and bottom. Advantageously, the cutouts are filled with a layer of non-conductive composite material that encases the individual magnets.

[0044] This further strengthens the bond between the individual magnets and the stability of the magnet structure. Advantageously, the ratio of the cross-sectional area of ​​an individual magnet to the cross-sectional area of ​​the magnet structure is less than 20%, with the perimeter of each individual magnet being smaller than its height.

[0045] This increases the advantages conferred by unit magnets. The smaller the cross-section of the unit magnets, with a greater number of unit magnets in the magnet structure, and the more the advantages of using unit magnets mentioned above are reinforced.

[0046] The invention also relates to a linear or rotary electromagnetic motor or generator, characterized in that it comprises such a single magnet structure or several such magnet structures, the magnet structure(s) forming magnet poles in a rectangular assembly or forming part of a rotor rotating around its center, the magnet structure(s) being arranged concentrically to the rotor.

[0047] Such a motor can advantageously be an axial flux motor.

[0048] For example, for an axial flux motor, one or more prior art rotors could comprise from 1 to 10 large magnets forming magnet poles, whereas the present invention provides for many more small magnets in each magnet structure forming a magnet pole.

[0049] It is important not to confuse a magnet pole, a rotor being able to carry for example five to ten or even more, with individual magnets which are significantly more numerous, a rotor being able to carry for example several hundred.

[0050] This makes it possible to obtain a rotor which, among other advantages, can rotate at high speed and which does not contain iron, thus limiting rotor losses.

[0051] Furthermore, due to a heel extending in a non-planar manner in the or each magnet structure, the strength of the or each magnet structure is reinforced while the previously mentioned advantages obtained by the use of small unit magnets are retained.

[0052] Advantageously, each magnet structure is individually encased in a layer of composite.

[0053] This measure further strengthens the mechanical resistance of the magnet structure as a whole.

[0054] The invention also relates to a method for manufacturing such a magnet structure, according to claim 14. This leads to a simplified manufacturing process for the magnet structure. In a prior art method for manufacturing a multi-magnet structure, when the individual magnets are not bonded together before being joined by a composite layer, these individual magnets are difficult to hold in position. The presence of a mesh to hold the individual magnets may therefore be required, which complicates the manufacturing process.

[0055] Similarly, when implementing a process for manufacturing a magnet structure according to the prior art, it might be necessary to cut the blank of the magnet structure leaving a stub for holding the unit magnets, inject a composite around the unit magnets, cut the stub and then inject the composite a second time, unlike the present invention for which the portions of the stub remain permanently in the magnet structure by forming the stub over several heights connecting all the unit magnets together.

[0056] The attached drawings illustrate the invention: [ Fig 1 ] represents a perspective view of a magnet structure according to a first embodiment of the present invention, [ Fig 2 ] represents a cross-sectional view along arrows A and B of the magnet structure shown in the figure 1 , [ Fig 3] represents a cross-sectional view along arrow C of the magnet structure shown in the figure 1 , [ Fig 4 ] represents a perspective view of a magnet structure according to a second embodiment of the present invention, [ Fig 5 ] represents a cross-sectional view along arrows A and B of the magnet structure shown in the figure 4 , [ Fig 6 ] represents a cross-sectional view along arrow C of the magnet structure shown in the figure 4 , [ Fig 7 ] represents a perspective view of a magnet structure according to a third embodiment of the present invention, [ Fig 8 ] represents a cross-sectional view along arrow C of the magnet structure shown in the figure 7 , [ Fig 9 ] represents a perspective view of a magnet structure according to a fourth and fifth embodiment of the present invention, [ Fig 10 ] represents a cross-sectional view along arrow C of the magnet structure shown in the figure 9 , this for the fourth embodiment of the present invention, [ Fig 11 ] represents a cross-sectional view along arrow C of the magnet structure shown in the figure 9 , this for the fifth embodiment of the present invention, [ Fig 12 [ ] represents a front view of a rotor that can be associated with a magnet structure as shown in the figures 1 to 11 in order to form an electromagnetic motor or generator according to the present invention.

[0057] In what follows, 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.

[0058] In the figures, when present, only a unit magnet is referenced 3 and only a magnet structure or magnet pole is referenced 2, but what is stated respectively for the unit magnet 3 and the structure or magnet pole 2 is valid for all unit magnets and magnet structures.

[0059] By referring primarily to figures 1 to 11 The present invention relates to a three-dimensional magnet structure of which one height.

[0060] This magnet structure 2 can be triangular in cross-section (three sides), square or rectangular (four sides), or polygonal with a number of sides greater than or equal to 4. When present, opposite sides of the magnet structure 2 are not necessarily parallel.

[0061] It is also possible that the structure of magnet 2 has a circular cross-section and is cylindrical in shape.

[0062] The same will apply to the individual magnets that make up this magnet structure 2.

[0063] In accordance with an essential feature of the present invention, during its manufacture, the magnet structure 2 has cutouts 4 to 7, 20, 21 extending along the height of the magnet structure 2 and forming groups of cutouts, as can be seen more particularly in Figures 1 , 4 , 7 And 9 .

[0064] Cuts 4 to 7, 20, 21 of each group are interrupted, each forming two parts 4, 6; 5, 7; 20, 21 along the height of the cut. A gap filled with material then remains between the two parts 4, 6; 5, 7; 20, 21 of the same cut, the material also being magnetic because it comes from the magnet structure 2.

[0065] The filled intervals of a group of cuts 4 to 7, 20, 21 form a portion 8a to 8d of a stub. This stub will be a single piece common to all groups of cuts, while retaining specific characteristics for each group of cuts 4 to 7, 20, 21.

[0066] The cutouts 4 to 7, 20, 21 of different groups can intersect as in the case of a magnet structure 2 with a square or rectangular cross-section shown in particular in figures 1 to 8 or extend one another as shown for a magnet structure 2 with unit magnets 3 with hexagonal cross-section shown in figures 9 to 11 .

[0067] All the cutouts 4 to 7, 20, 21 taken together define unit magnets 3 held together by the base, which consists of several portions 8a to 8d of the base associated with different groups. To prevent the common base from being flat, at least one filled gap between a cutout of one group is located at a different height than at least one filled gap between a cutout of another group of cutouts.

[0068] Consequently, the 8a to 8d portions of the base of the different groups of cutouts extend at least partially over different height levels in the magnet structure 2 and provide a common base with steps. Without being limiting and purely illustrative, the individual magnets 3 are in the form of studs with a 1-millimeter base that can be positioned at mid-height of the individual magnet.

[0069] The state of the art proposes three configurations: a configuration with a solid magnet structure without cutting unit magnets, a configuration with a magnet structure with unit magnets not including a base, i.e. magnetized material of the magnet structure joining them, and a configuration with a magnet structure including a flat base of magnetized material joining the unit magnets.

[0070] The present invention proposes the main configuration with a magnet structure 2 with unit magnets 3 joined by a stepped heel extending to various heights in the magnet structure 2.

[0071] Experiments conducted by the applicant showed that the most favorable configuration for reducing eddy current losses was a unit magnet structure without a heel, in accordance with the second prior art configuration.

[0072] Eddy current losses with a magnet structure without unit magnets according to the first configuration are at least 60 times higher than for the second configuration and eddy current losses with a magnet structure with unit magnets joined by a flat base according to the third configuration are at least 9 times higher than for the second configuration.

[0073] On the other hand, the configuration according to the present invention with a magnet structure 2 with unit magnets joined by a stepped heel extending to various heights in the magnet structure 2 has losses only slightly higher than for the magnet structure 2 with unit magnets not joined by magnetized material by not having a heel, these losses being 1.16 times higher than for the second configuration of the prior art.

[0074] This increase in eddy current losses is, however, notably offset by the ease of manufacturing such a magnet structure 2 according to the invention. During the fabrication of a magnet structure with individual magnets not joined by a base, before the injection of composite material between the individual magnets to hold them together, these individual magnets tend to move apart.

[0075] Moreover, even with composite injection between the unit magnets, such a magnet structure according to the second prior art configuration will have less mechanical strength than the magnet structure 2 proposed by the present invention, the stepped heel connecting all the unit magnets 3 being of magnetized material in one piece with the unit magnets 3 considerably strengthening the mechanical strength of the magnet structure 2.

[0076] Cutouts 4 to 7 can pass completely through the magnet structure 2, that is, in both dimensions of the magnet structure 2 other than its height, extending from one side of the magnet structure 2 to an opposite side, with a group of cutouts 4, 6 associated with one side intersecting with at least one group of cutouts 5, 7 associated with another side. This is the case for the three embodiments shown in figures 1 to 8 , THE figures 1 to 6 showing a rectangular or square magnet structure 2 with rectangular or square unit magnets 3, the figures 7 to 8 showing an approximately square magnet structure 2 with unit magnets 3 separated into two halves of triangular section.

[0077] The magnet structure 2 shown at figures 1 to 8 may, however, have a different form than that shown in these figures. For example, for the figures 1 to 6The magnet structure 2 can be square or circular in cross-section with square or cylindrical unit magnets, and for the figures 7 and 8 , the magnet structure 2 can be rectangular or circular in cross-section with rectangular or cylindrical unit magnets 3.

[0078] For a square-section magnet structure 2, the unit magnets 3, also square-section, may not be divided into two triangular-section magnets and therefore retain their square section, contrary to what is shown in the figure 7 .

[0079] As illustrated in figures 1 to 8 The cuts 4, 6; 5, 7 of the same group of cuts can extend parallel to each other. In this case, there exists another group of cuts comprising cuts 4, 6 which extend perpendicularly to the cuts 5, 7 of the first group.

[0080] THE figures 1 to 3They show a rectangular magnet structure 2 with rectangular unit magnets 3. The cutouts 4, 6 extending vertically across the width of the magnet structure 2, referred to as lateral cutouts, have two parts, referenced respectively as 4 and 6, and are both interrupted at the same height. Between parts 4, 6 of these lateral cutouts, a lateral heel portion 8b is formed by the remaining material-filled gap between the two parts 4, 6 of these lateral cutouts.

[0081] In this first optional embodiment of the present invention, the vertical cutouts extending along the length of the magnet structure 2, called longitudinal cutouts 5, 7, have two parts referenced respectively 5 and 7 and are all interrupted at the same height level but at a different height from the lateral cutouts 4, 6.

[0082] Between parts 5, 7 of these longitudinal cuts is formed a longitudinal heel part 8a by the interval filled with material remaining between the two parts 5 and 7 of these longitudinal cuts.

[0083] To the figure 2 , which shows views according to arrows A and B of the figure 1 A line 9a is shown, depicting the lower end of the upper part 5 of the longitudinal cuts, and a line 9b shows the upper end of the lower part 7 of the longitudinal cuts. Lines 9a and 9b delimit a portion of the longitudinal heel 8a.

[0084] Also illustrated is line 10a showing the lower end of the upper part 4 of the lateral cutouts and line 10b showing the upper end of the lower part 6 of the longitudinal cutouts. Lines 10a and 10b delimit a portion of the longitudinal heel 8b.

[0085] It follows that, in the method of implementation of the figures 1 to 3 , all lower ends 9a, 10a of the longitudinal or lateral cut parts 5, 4 respectively are aligned with each other for each group and all upper ends 9b, 10b of the longitudinal or lateral cut parts 7, 6 respectively are aligned with each other for the same group of cuts.

[0086] As it can be best viewed at the figure 3 which is a view along arrow C of the figure 1 There are only two heel heights, each identified by specific hatching, for the common heel composed of a lateral heel part 8b and a longitudinal heel part 8a. The common heel is therefore staggered over two heights in the magnet structure 2.

[0087] In this first optional embodiment of the present invention, the material-filled intervals of the same group of cutouts can be at the same height level.

[0088] THE figures 4 to 6 represents a second optional embodiment of a square or rectangular magnet structure 2 according to the present invention. The magnet structure 2 is shown with a square cross-section, but what is stated can be applied to a rectangular magnet structure 2.

[0089] This second embodiment differs from the first in that not all lateral cuts and, respectively, all longitudinal cuts are interrupted at the same height. At the figure 1 , without limiting the first and third lateral cuts in two parts 4, 6 are interrupted at a different level than the second lateral cut in two parts 4a, 6a.

[0090] Similarly, the first and third longitudinal cuts in two parts 5, 7 are interrupted at a different level than the second longitudinal cut in two parts 5a, 7a.

[0091] It should be noted that there could be more than three longitudinal or lateral cutouts in the magnet structure 2.

[0092] Thus at the figure 5 Illustration shows line 9a, depicting the lower end of the upper part 5 of the first and third longitudinal cuts, and line 9b, depicting the upper end of the lower part 7 of the first and third longitudinal cuts. Lines 9a and 9b delineate a longitudinal heel section 8a1.

[0093] In addition, line 9b is shown, depicting the lower end of the upper part 5a of the second longitudinal cut, and line 9c shows the upper end of the lower part 7a of the second longitudinal cut. Lines 9a and 9b delineate a portion of the longitudinal heel 8a2.

[0094] It should be noted that the lower end of the upper part 5a of the second longitudinal cut is not necessarily at the same height as the upper end of the lower part 7 of the first and third longitudinal cuts, which is a non-limiting special case.

[0095] In this case, there are two steps for a longitudinal heel part 8a formed from the longitudinal heel parts 8a1 and 8a2.

[0096] The same applies to the lateral heel part 8b formed from the lateral heel parts 8b1 and 8b2 delimited respectively by lines 10a and 10b for the first and third lateral cuts with parts 4 and 6, and by lines 10b and 10c for the second lateral cut with parts 4a and 6a.

[0097] To the figure 5 which shows views according to arrows A and B of the figure 4 The lower end of the upper part 4a of the second lateral cutout is aligned with the upper end of the lower part 6 of the first and third lateral cutouts. This is not mandatory, although preferred.

[0098] As it can be best viewed at the figure 6 which is a view along arrow C of the figure 4, there can then be four heel heights, each identified by specific hatching, for the common heel composed of two lateral heel parts 8a1 and 8a2 and two longitudinal heel parts 8b1 and 8b2, this if one of the lateral heels 8a1 and 8a2 is not at the same height as one of the longitudinal heels 8b1 and 8b2.

[0099] The common heel is therefore staggered over at least three heights in the magnet structure 2.

[0100] Thus, in this second optional embodiment of a magnet structure 2 according to the present invention, the material-filled intervals of the same group of cutouts can be located at different levels. It is possible, in this case, to have alternating material-filled intervals at different levels, but this is not mandatory.

[0101] THE figures 7 and 8show a third optional embodiment of a magnet structure 2 according to the present invention.

[0102] To the figure 7 The structure of magnet 2 is square, as are the individual magnets, which again is not mandatory. figures 7 and 8 The diagram shows two-part lateral cuts 4 and 6, all stopping at the same height, while two-part longitudinal cuts 5 and 7 also stop at a different height than the interruption point of the lateral cuts. This is not a limitation for this third optional embodiment.

[0103] In this third optional embodiment, each unit magnet 3 can undergo an auxiliary cut 17 extending along the height of the magnet structure 2 and separating the unit magnet 3 into two equal portions, advantageously of triangular cross-section, without this being limiting.

[0104] Like the lateral and longitudinal cutouts, the auxiliary cutouts 17 of the unit magnets 3 can also be interrupted by each forming two parts in the direction of the height of the magnet structure 2 and leaving a space filled with material between the two parts of the same auxiliary cutout 17.

[0105] In the illustration of figures 7 and 8 , the auxiliary cutouts 17 join on one side a lateral cutout with parts 4, 6 and on the other a longitudinal cutout with parts 5, 7.

[0106] In addition to the lateral and longitudinal heel parts 8b and 8a, the magnet structure 2 has an auxiliary heel part 8c of auxiliary cutting 17 also in two parts.

[0107] As it can be best viewed at the figure 8 which is a view along arrow C of the figure 7, there are then three heel heights, each identified by specific hatching, for the common heel composed of a part of lateral heel 8b, a part of longitudinal heel 8a and a part of auxiliary heel 8c.

[0108] The common heel is therefore staggered over at least three heights in the magnet structure 2 when the height of the auxiliary heel part 8c is not equal to a height of either a lateral heel part 8b or a longitudinal heel part 8a.

[0109] For all these embodiments, in the vertical holding position of the height of the magnet structure 2, as shown in figures 2 And 5, it is possible but not obligatory that a material-filled interval between the cut of a group, for example a group of lateral cuts 4, 6 forming a part of lateral heel 8b, has its highest end at the same height as the lowest end of a material-filled interval between the cut of another group, for example a group of longitudinal cuts 5, 7 forming a part of longitudinal heel 8a.

[0110] The second and third optional embodiments of the present invention can also be combined with each other.

[0111] THE figures 9 to 11 illustrate a fourth and fifth optional embodiment of a magnet structure 2 according to the present invention.

[0112] THE figures 9 to 11 show a 2-faceted magnet structure giving it an approximately rectangular shape, but it could also be something else.

[0113] To figures 9 to 11 , the unit magnets 3, delimited by the cutouts 20, 21, are of hexagonal section but everything that will be stated below for this hexagonal section can be applied to any polygonal section with more than four sides.

[0114] The hexagonal section of the unit magnets 3 is delimited by six cutouts 20, 21 for a unit magnet which is not at the edge of the magnet structure 2.

[0115] To the figure 9 , reference 8d shows a portion of a common heel to all unit magnets 3 and to magnet structure 2, this common heel portion being visible on the periphery of magnet structure 2.

[0116] Each cut consists of two parts 20 and 21 leaving between them an interval filled with material between the two parts 20, 21 of the same cut.

[0117] The material-filled intervals of a group of cutouts 20, 21 form a portion of a common heel, as will be better seen in Figures 10 And 11 Furthermore, the intervals filled with material are located in an area framing, with plus or minus 20%, half the height of magnet structure 2.

[0118] THE Figures 10 And 11 illustrate two forms of embodiment differing in the number of heel sections located at two different heights, these different heel sections not having been visible at the figure 9 because internal to the structure of magnet 2.

[0119] By referring first to the Figure 10 which is a view along arrow C of the figure 9According to the fourth optional form, three different heel part height levels are shown, the three levels being illustrated by different hatching. A common heel 8d is composed of three types of heel parts 8d1, 8d2, 8d3, staggering the common heel 8d across three height levels.

[0120] Then, referring to the figure 11 which is a cross-sectional view along arrow C of the figure 9 According to the fifth optional form, six different heel part height levels are shown, the six levels being illustrated by different hatching. A common heel 8d is composed of six types of heel parts 8d1, 8d2, 8d3, 8d4, 8d5, 8d6, staggering the common heel 8d over six height levels.

[0121] As shown to Figures 10 to 11with hexagonal unit magnets 3, a magnet structure 2 can have cutting groups with a cutting group 20, 21 extended by at least one other cutting group, advantageously two other cutting groups.

[0122] The cuts 20, 21 of the same group of cuts can advantageously be parallel to each other.

[0123] Referring to all the figures, for all forms of embodiment, the intervals filled with material can have the same dimension taken in the height of the magnet structure 2 for all cutting groups.

[0124] In general, especially for unit magnets 3 with polygonal sections with more than four sides, the 8d1 to 8d6 heel portions of the cut groups can extend at least partially over a number of height levels less than or equal to the number of sides of a unit magnet 3.

[0125] For order of magnitude and without limitation, the intervals filled with material, therefore the thicknesses of parts 8a to 8d of heel can have a height between 2 and 20% of a total height of cuts 4 to 7, 20, 21.

[0126] During the manufacture of a magnet structure 2, the cutouts 4 to 7, 20, 21 can be filled with a layer of non-conductive composite encasing the unit magnets 3, the composite layer being advantageously reinforced with fibers.

[0127] Since the unit magnets 3 are of relatively small cross-section compared to the magnet structure 2 in order to have the greatest number of unit magnets for a magnet structure 2, a ratio of a cross-section of a unit magnet to a cross-section of the magnet structure 2 can be less than 20% and preferably less than 10%.

[0128] Similarly, the perimeter of each unit magnet 3 can be less than the height of the unit magnet 3, in order to have a unit magnet 3 in the form of an elongated block. As already mentioned but not shown in the figures, the unit magnets can be cylindrical, therefore having a circular cross-section.

[0129] It is then possible to cut each individual magnet by at least two complementary cuts which present intervals filled with material at different height levels.

[0130] It is also possible to provide, for at least two close-set individual magnets, cutouts, partial or complete, with material-filled intervals at different heights for each of the two individual magnets. It is also possible to combine these two configurations.

[0131] A cylindrical unit magnet is then surrounded by four cylindrical unit magnets with a section of the cutout of the unit magnet tangential at four different points respectively with a section of each of the cutouts of the neighboring unit magnets.

[0132] In this arrangement, areas of the magnet structure remain between the cutouts of the individual magnets. These areas can be retained as individual magnets because they are isolated from the other individual magnets by cutouts, even though they are not circular in cross-section. Alternatively, these areas can be removed from the magnet structure.

[0133] The invention also relates to a linear or rotary electromagnetic motor or generator comprising a single magnet structure 2 or several magnet structures 2 as previously described.

[0134] The magnet structure(s) 2 form magnet poles in a rectangular assembly for a linear electromagnetic motor, or form part of a rotor rotating around its center for a rotary electromagnetic motor. In this latter configuration, the magnet structure(s) 2 are arranged concentrically around the rotor.

[0135] There figure 12 shows such a rotor 18 with several magnet structures 2. In an electromagnetic machine according to the present invention, the rotor or each rotor 18 may comprise a plurality of magnet structures 2 as magnet poles, only one of which is referenced to the figure 12 .

[0136] The rotor or each rotor 18 can be made of composite material to reduce iron losses. Each magnet pole, which is in the form of a magnet structure 2, can be made up of a plurality of unit magnets 3 joined together by composite material, glue, or resin.

[0137] Furthermore, to reinforce the strength of magnet pole 2, each magnet pole 2 can be individually encased in a layer of composite.

[0138] In view of the figure 12 , it has been described previously essentially as a rotary electromagnetic motor with axial flux but the present invention can be applied to any type of motor, in particular a motor or generator with radial flux or with mixed rotary or linear flux.

[0139] With reference to all the figures, the invention finally relates to a method of manufacturing such a magnet structure 2.

[0140] The essential step of the process according to the invention is the making in a blank of magnet structure 2 of several groups of cuts, the cuts 4 to 7, 20, 21 of each group being interrupted by forming each of two parts 4, 6; 5, 7; 20, 21 in the direction of the height of the cut and leaving a space filled with material between the two parts 4, 6; 5, 7; 20, 21 of the same cut.

[0141] The draft magnet structure 2 may have the same external shape as the magnet structure 2 to be obtained.

[0142] Cuts 4 to 7, 20, 21 are interrupted at different heights so that at least one material-filled interval between a cut in one group is at a different height than at least one material-filled interval between a cut in another group, leaving a non-planar stub 8a to 8d comprising one or more steps.

[0143] Cuts 4 through 7, 20, and 21 can be made using several processes, for example, without limitation, by electrical discharge machining (EDM), equivalent wire cutting, or laser cutting. For complex shapes with more than four sides, a cutting bell can be used for all cuts 4 through 7, 20, and 21.

Claims

1. Three-dimensional magnet structure (2), one dimension of which is a height, the magnet structure (2) having cut-outs (4 to 7, 20, 21) extending along the height of the magnet structure (2) and forming groups of cut-outs, the cut-outs (4 to 7, 20, 21) of each group being interrupted, each forming two parts (4, 6; 5, 7; 20, 21) in the direction of the height of the cut-out and leaving a material-filled gap between the two parts (4, 6; 5, 7; 20, 21) of one and the same cut-out, the material-filled gaps of a group of cut-outs (4 to 7, 20, 21) forming a portion of a one-piece heel (8a to 8d) common to all the groups of cut-outs, the cut-outs (4 to 7, 20, 21) delimiting between them unitary magnets (3) held secured to one another by the heel (8a to 8d), wherein each material-filled gap (20) has a height of between 2 and 20% of a total height of the cut-out (4 to 7, 20, 21) between the two parts of which said gap remains, at least one material-filled gap between a cut-out (4, 6) of one group being at a height different from at least one material-filled gap between a cut-out (5, 7) of another group, so that the heel portions (8a to 8d) of the different groups of cut-outs extend at least partially at different height levels in the magnet structure (2).

2. Magnet structure (2) according to the preceding claim, in which the cut-outs (4 to 7) pass right through the magnet structure (2), extending from one side of the magnet structure (2) towards another side opposite thereto, a group of cut-outs (4, 6) associated with one side intersecting with at least one group of cut-outs (5, 7) associated with another side, or a group of cut-outs (20, 21) being extended by at least one other group of cut-outs around the unitary magnets (3).

3. Magnet structure (2) according to the preceding claim, in which the cut-outs (4, 6; 5, 7; 20, 21) of one and the same group of cut-outs extend parallel to one another.

4. Magnet structure (2) according to any one of the preceding claims, in which the material-filled gaps have a same dimension, taken in the height of the magnet structure (2), for all the groups of cut-outs.

5. Magnet structure (2) according to any one of the preceding claims, in which the cut-outs (4, 6; 5, 7; 20, 21) of one and the same group of cut-outs have their material-filled gaps at at least two different height levels.

6. Magnet structure (2) according to any one of the preceding claims, in which, in a position in which the height of the magnet structure (2) is held vertically, said at least one material-filled gap between the cut-out of one group has its uppermost end at a height equal to the height of a lowermost end of said at least one material-filled gap between the cut-out of another group.

7. Magnet structure (2) according to any one of the preceding claims, in which the heel portions (8a to 8d) of the groups of cut-outs extend at least partially over a number of height levels less than or equal to the number of sides of a unitary magnet (3).

8. Magnet structure (2) according to any one of the preceding claims, in which each unitary magnet (3) is subjected to an auxiliary cut-out (17) extending along the height of the magnet structure (2) and separating the unitary magnet (3) into two equal portions, the auxiliary cut-outs (17) of the unitary magnets (3) also being interrupted, each forming two parts in the direction of the height of the magnet structure (2) and leaving a material-filled gap between the two parts of one and the same auxiliary cut-out (17).

9. Magnet structure (2) according to any one of the preceding claims, in which the material-filled gaps are located in a zone framing, within plus or minus 20%, a mid-height of the magnet structure (2).

10. Magnet structure (2) according to any one of the preceding claims, in which the cut-outs (4 to 7, 20, 21) are filled with a layer of non-conductive composite coating the unitary magnets.

11. Magnet structure (2) according to the preceding claim, in which a ratio of a cross-section of a unitary magnet (3) to a cross-section of the magnet structure (2) is less than 20%, a perimeter of each unitary magnet (3) being less than the height of the unitary magnet.

12. Linear or rotary electromagnetic motor or generator, characterized in that it comprises a single magnet structure (2) or several magnet structures (2) according to any one of the preceding claims, the magnet structure or structures (2) forming magnet poles in a rectangular assembly or forming part of a rotor (18) rotatable about its centre, the magnet structure or structures (2) being arranged concentrically with the rotor (18).

13. Motor or generator according to the preceding claim, in which each magnet structure (2) is individually coated in a layer of composite.

14. Method for manufacturing a magnet structure (2) according to any one of claims 1 to 11, characterized by the following steps: - inserting several groups of cut-outs into a magnet structure blank (2), the cut-outs (4 to 7, 20, 21) of each group being interrupted, each forming two parts (4, 6; 5, 7; 20, 21) in the direction of the height of the cut-out and leaving a material-filled gap between the two parts (4, 6; 5, 7; 20, 21) of one and the same cut-out, each material-filled gap having a height of between 2 and 20% of a total height of the cut-out, between the two parts of which said gap remains, - at least one material-filled gap between a cut-out of one group being at a height different from at least one material-filled gap between a cut-out of another group.