MAGNET POLE WITH A PLURALITY OF SINGLE MAGNETS HAVING A VARIABLE CROSS-SECTION

Abstract

Magnet pole (10) with a plurality of single magnets with variable cross sections

The present invention relates to a magnet pole (10) formed by a plurality of elongated single magnets grouped into a bundle, oriented magnetically longitudinally and extending parallel between a front face and a rear face of the magnet pole (10), and are connected to one another. A first group of single magnets (4) has a larger cross-section or a differently shaped cross-section than at least a second group of at least one single magnet (4 a), there being a greater number of single magnets (4) of the first group than the at least one single magnet (41) of the at least one second group.

Claims

1. A magnet pole (10) formed by a plurality of elongated single magnets (4, 4a to 4g) grouped to form a bundle, oriented magnetically longitudinally and extending parallel between a front face and a rear face of the magnet pole (10) and being connected to one another, characterized in that a first group of single magnets (4) has a larger cross-section or a cross-section of a different shape than at least one second group of at least one single magnet (4a to 4g), the single magnets (4) of the first group being more numerous than said at least one unit magnet (4a to 4g) of said at least one second group.

2. A magnet pole (10) according to claim 1, in which the single magnets (4, 4a to 4g) are connected to one another by forming an assembly of magnets, whereby one section of the assembly of magnets corresponding to a section of the front face or the rear face of the magnet pole (10) is smaller than it by less than 15%.

3. A magnet pole (10) according to claim 2, in which said at least one magnet (4a to 4g) of said at least one second group is locally inserted on the periphery of the assembly of single magnets (4, 4a to 4g).

4. A magnet pole (10) according to claim 1, in which the single magnets (4) of the first group form a series of single magnets aligned in two perpendicular directions and the single magnets (4a to 4g) of said at least one second group, when a number of single magnets (4a to 4g) of said at least one second group is greater than one, form series of single magnets aligned in at least one direction, optionally associated two-by-two perpendicular to said direction or are positioned in isolation in the magnet pole (10).

5. A magnet pole (10) according to claim 1, in which the single magnets (4, 4a to 4g) have an ovoid shape or the cross-sections of the single magnets (4, 4a to 4g) are rectangular, square, triangular, circular, trapezoidal or polygonal, the shapes of said at least one single magnet (4a to 4g) of said at least one second group being optionally different from the shapes of the single magnets (4) of the first group.

6. A magnet pole (10) according to claim 1, in which the single magnets (4, 4a to 4g) are advantageously adhesively connected to one another at least locally, or the single magnets (4, 4a to 4g) are housed in a mesh that has first cavities corresponding to the cross-sections of the single magnets (4) of the first group and at least second cavities corresponding to the cross-sections of the single magnets (4a to 4g) of said at least one second group.

7. A magnet pole (10) according to claim 1, which has an exterior shape with front and rear faces having a trapezoidal, triangular or circular cross-section.

8. A magnet pole (10) according to claim 1, in which a layer of composite at least partly coats the magnet pole (10).

9. A fabrication method of at least one magnet pole (10) according to any one of the preceding claims from a magnet block forming a blank, wherein the magnet pole (10) must have a predetermined cross-section, characterized in that the blank is cut along several directions to delimit, on one hand, single magnets (4) of the first group and, on the other hand, at least one single magnet (4a to 4g) of said at least one second group, the single magnets (4, 4a to 4g) being connected to one another by adhesive, at least locally, optionally with the interposition of a mesh structure between the single magnets (4, 4a to 4g) to form an assembly of unit magnets forming a magnet pole (10).

10. A method according to claim 9, in which the blank is previously configured to the proper dimensions and cut into single magnets (4) of the first group and into at least one single magnet (4a to 4g) of the second group so that the assembly of single magnets (4, 4a to 4g) has a cross-section corresponding to a cross-section of the front or rear face of the magnet pole (10), being smaller than it by less than 15%.

11. A method according claim 9, in which the cutting is done by wire, electrical discharge machining, milling or very high-pressure water jet cutting.

12. A method according to claim 9, in which, when at least two magnet poles (10) are fabricated from the blank, the cut blank with the single magnets (4, 4a to 4g) connected together is advantageously cut into said at least two magnet (10) poles.

13. A rotor (1) for an axial flux electromagnetic machine, characterized in that it contains at least one magnet pole (1), the single magnets extending axially with reference to the rotor (1) in the thickness direction of the rotor, the rotor being in the form of a disk with the front face of said at least one magnet pole piercing one face of the disc and the rear face of said at least one magnet pole piercing the opposite face of the disc.

14. A rotor according to claim 13, in which a periphery of the rotor (1) is formed by a layer of optionally fiber-reinforced composite coating.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0073] Additional characteristics, objectives and advantages of the present invention are described in greater detail below and with reference to the accompanying drawings which illustrate non-restricting examples, and in which:

[0074] FIG. 1 is a schematic representation of a front view of a rotor intended for an axial flux electromagnetic machine of the prior art, wherein the rotor carries magnet poles constituted by a plurality of individual magnets, with empty single magnet spaces remaining in each magnet pole,

[0075] FIG. 2 shows a magnet pole with a plurality of single magnets according to a first embodiment of the present invention, wherein a first group of single magnets has a square cross-section and a second group of single magnets consists of single magnets with a circular cross-section, for example ovoid single magnets, the cross-section of the magnets of the second group being smaller than the cross-section of the magnets of the first group,

[0076] FIG. 3 shows an enlarged detail of a branched rotor according to a first embodiment of the present invention, the rotor having magnet poles identical to the one shown in FIG. 2,

[0077] FIG. 4 shows a magnet pole with a plurality of single magnets according to a second embodiment of the present invention, a first group of single magnets having a square cross-section and a second group of single magnets having a triangular cross-section, the cross-section of the magnets of the second group being smaller than the cross-section of the magnets of the first group,

[0078] FIG. 5 shows an enlarged detail of a branched rotor according to a second embodiment of the present invention, wherein the rotor houses magnet poles identical to the one shown in FIG. 4,

[0079] FIG. 6 shows a magnet pole with a plurality of single magnets according to a third embodiment of the present invention, a first group of single magnets having a square or rectangular cross-section and a second group of single magnets having a rectangular cross-section, the cross-section of the magnets of the second group being smaller than the cross-section of the magnets of the first group,

[0080] FIG. 7 shows an enlarged section of a branched rotor according to a third embodiment of the present invention, wherein the rotor housing the magnet poles is identical to the one shown in FIG. 6.

[0081] All the accompanying figures are intended to be considered in combination and reference may be made in the following description of a figure to reference numbers that are found on one of the other figures.

[0082] A single magnet of a first or a second group is referenced in the figures, although what is said about the single magnet in question is valid for all the single magnets of the same group. The same is true for a single magnet pole referenced in FIGS. 1, 3, 5 and 7.

DETAILED DESCRIPTION OF THE INVENTION

[0083] FIG. 1 shows a rotor 1a of the prior art. The rotor 1a has branches 3 enclosing between them a magnet pole 10a constituted by a plurality of polygonal single magnets 4. A rotor 1a of this type is used in an electromagnetic motor or generator, advantageously an axial flux motor or generator.

[0084] The rotor 1a, which is advantageously essentially circular in the form of a ring, has a body comprising an internal hub 2 concentric with a central axis of rotation 7 of the rotor 1a or longitudinal median axis of the rotor 1a. Branches 3 extend radially into the rotor 1a with reference to the central axis of rotation 7 from the internal hub 2 toward a rotor binding 8 forming a circular external periphery of the rotor 1a.

[0085] The hub 2 and the branches 3 are in one piece and form a rotor body 2, 3. At least one magnet pole 10a comprising a plurality of small single magnets 4 grouped to form a bundle is housed in each space delimited between two adjacent branches 3.

[0086] According to the conventional definition, a bundle is an assembly of similar elements, i.e. in the present case an assembly of single magnets, with an elongated shape and bound together.

[0087] In all the figures accompanying the present application, the single magnets 4 are always similar and are grouped into a bundle forming a packet of single magnets and are not similar each to a magnetic bar.

[0088] FIG. 1 shows that empty spaces remain in the magnet pole 10a for single magnets. One of these spaces is identified as 11 in FIG. 1, although of course there are a plurality of the spaces in each magnet pole 10a. These spaces 11 are filled by connecting means of the single magnets 4 to one another and reduce the magnetic power of each magnet pole 10a.

[0089] With reference to FIGS. 2 to 7, the present invention relates to a magnet pole formed by a plurality of single magnets 4, 4a to 4g which are elongated, grouped into a bundle and are oriented magnetically longitudinally and extend parallel between a front face and a rear face of the magnet pole, and are connected to one another and can be perpendicular to the front and rear faces.

[0090] The front and rear faces are intended to be carried by a respective face of a disc-shaped rotor, the single magnets extending along the thickness direction of the rotor.

[0091] One or more large magnets are therefore broken down into a plurality of small or micro-magnets. A magnet with large dimensions is subject to losses from Foucault currents greater than its equivalent in small or micro-magnets. The use of small or micro-magnets therefore makes it possible to reduce these losses, which are prejudicial to the functioning of the rotor.

[0092] This was known from the closest prior art.

[0093] According to the invention, a first group of single magnets 4 has a larger cross-section or a cross-section of a different shape than at least one second group of at least one single magnet 4a to 4g. The single magnets 4 of the first group are more numerous than the single magnet or magnets 4a to 4g of the second group or of groups other than the first group.

[0094] This makes it possible to obtain an assembly of single magnets with dimensions and a shape that more closely matches the internal shape of the magnet pole that is to be achieved. By using single magnets 4 of the first group, it would not have been possible to complete the assembly, which would then have exceeded the required dimensions of the internal shape of the magnet pole 10.

[0095] It is necessary, however, to leave unoccupied in the magnet pole 10, at the time of its fabrication, sufficient space to ensure the retention of the single magnets among themselves, whether they are part of the first group or another group.

[0096] The single magnets 4, 4a to 4g can also be connected to form an assembly of magnets, whereby one section of the assembly of magnets corresponding to a section of the front face or the rear face of the magnet pole 10 is smaller than it by less than 15%.

[0097] Thus the single magnets 4, 4a to 4g occupy practically more than 85% of the magnet pole 10. The percentage of 85% depends on the connection means employed and the specifications that must be satisfied by the rotor, for example being capable of rotating at very high speeds, in which case the space reserved for the connection means, principally by means of adhesive and/or a mesh structure, can be increased to increase the strength of the rotor.

[0098] The single magnets 4a to 4g of the second group or of groups other than the first group can be inserted locally on the periphery of the assembly of single magnets. This is shown in the accompanying figures, but is not obligatory. Likewise, all the embodiment shapes shown in FIGS. 2 to 7 are not restricting and other embodiment shapes may exist.

[0099] For example, in FIGS. 2 to 7 the groups of single magnets other than the first group are positioned toward the periphery of the magnet pole 10, but this arrangement, although advantageous, is not obligatory. These other groups can also be distributed in the magnet pole 10 and even broken down into subgroups distributed differently in the magnet pole 10.

[0100] In FIGS. 2 to 7, the single magnets 4 of the first group are shown with a rectangular or square cross-section; although this cross-section is preferred, it is not obligatory.

[0101] In FIGS. 2 and 3, the single magnets 4 of the first group have a square cross-section and the single magnets 4a of the second group have a circular cross-section. These single magnets 4a of the second group can be ovoid or cylindrical, for example.

[0102] In FIGS. 4 and 5, the single magnets 4 of the first group have a square cross-section and the single magnets 4b of the second group have a triangular cross section.

[0103] The single magnets 4b of the second group can, for example, be grouped two-by-two to form a rectangular cross-section, advantageously square, or can be considered in isolation as illustrated toward a tip of the magnet pole 10 in FIG. 5.

[0104] In FIGS. 6 and 7, the single magnets 4 of the first group have a rectangular or square cross-section and there are more than two groups of single magnets. It is possible to distinguish five groups of single magnets 4c, 4d, 4e, 4f and 4g in addition to the first group of single magnets 4, only one single magnet being identified for each group.

[0105] It is therefore possible to consider that the first group can be separated into two subgroups, one subgroup comprising single magnets with a square cross-section, this subgroup being placed toward the middle of the width and in the top and bottom parts of the length of the magnet pole 10 in FIG. 6, and another subgroup comprising single magnets with a rectangular cross-section, this subgroup being placed in the middle of the width and the length of the magnet pole 10, i.e. in the central part of the magnet pole 10.

[0106] The single magnets 4c, 4d, 4e, 4f and 4g of the five groups have a smaller rectangular cross-section than that of the single magnets 4 of the first group, decreasing to a greater extent as the group other than the first group approaches the edges of the assembly of single magnets 4, 4c to 4g thus formed.

[0107] Certain of the single magnets 4c, 4d, 4e, 4f and 4g of a given group other than the first group can be truncated in relation to the single magnets of the same group, to better fit the internal configuration of the magnet pole 10 that contains them.

[0108] As shown in FIGS. 2 to 7 and with reference to these figures considered in combination, the single magnets 4 of the first group can form series of single magnets aligned in two perpendicular directions.

[0109] When a number of single magnets 4a to 4g of the second group or of groups other than the first group is greater than one, the single magnets 4a to 4g of the second group or of groups other than the first group can form series of single magnets aligned in at least one direction, optionally grouped two-by-two as shown in FIGS. 4 and 5, or being housed individually in the assembly of single magnets.

[0110] The single magnets 4, 4a to 4g of all the groups can have an ovoid shape, or the cross-sections of the single magnets 4, 4a to 4g can have a rectangular, square, triangular, circular, trapezoidal or polygonal shape.

[0111] In all cases, the shapes of the single magnet or magnets 4a to 4g of the second group or of groups other than the first group can optionally be different from the shapes of the single magnets 4 of the first group.

[0112] In a first optional configuration, the single magnets 4, 4a to 4g of all the groups can be adhesively connected to one another, at least locally.

[0113] In a second optional configuration, the single magnets 4, 4a to 4g of all the groups can be housed in a mesh structure having first cavities corresponding to the cross-sections of the single magnets 4 of the first group and at least second cavities corresponding to the cross-sections of the single magnets 4a to 4g of the second group or of groups other than the first group.

[0114] The magnet pole 10 can have an exterior shape with front and rear faces having a trapezoidal, triangular or circular cross-section. The above feature is not restricting. FIGS. 2 to 7 show a trapezoidal front face.

[0115] A layer of composite can coat the magnet pole 10 at least partly to strengthen it.

[0116] The invention further relates to a fabrication method for at least one magnet pole 10 of the type described above from a magnet block forming a blank, wherein the magnet pole 10 must have a predetermined cross-section.

[0117] In this method, the blank is cut in a plurality of directions to delimit, on one hand, single magnets 4 of the first group and, on the other hand, at least one single magnet 4a to 4g of the second group or of groups other than the first group.

[0118] The single magnets 4, 4a to 4g are then connected to one another by adhesive at least locally with the optional interposition of a mesh structure between the single magnets 4, 4a to 4g to form an assembly of single magnets forming the magnet pole 10. The mesh structure is not preferred, given that the single magnets 4, 4a to 4g are already positioned in the assembly of single magnets because they originate from the blank cut as described above.

[0119] The blank can be previously configured to the proper dimensions and cut into single magnets 4 of the first group and into at least one single magnet 4a to 4g of the second group so that the assembly of single magnets has a cross-section corresponding to a cross-section of the front or rear face of the magnet pole 10, being smaller than it by less than 15%.

[0120] The cutting can be performed by wire, electrical discharge machining, milling or very high-pressure water jet cutting.

[0121] In one preferential embodiment, when at least two magnet poles 10 are fabricated from the blank, the cut blank with the connected single magnets 4, 4a to 4g is sectioned into said at least two magnet poles 10.

[0122] The dimensions and the shape of the blank therefore take into account the dimensions and the shapes of at least two magnet poles 10 fabricated simultaneously.

[0123] The invention finally relates to a rotor 1 for an axial flux electromagnetic machine. This rotor 1 is identical to a rotor of the prior art shown in FIG. 1, with the difference that it comprises magnet poles 10 as described above and some of which are illustrated in FIGS. 2 to 7

[0124] The rotor one houses at least one magnet pole 10, the single magnets 4, 4a to 4g extending axially to the rotor 1 in a thickness direction of the rotor 1.

[0125] The rotor 1 is in the shape of a disk with the front face of said at least one magnet pole 10 piercing one face of the disc and the rear face of said at least one magnet pole 10 piercing the opposite face of the disc.

[0126] FIG. 1 describes a rotor 1a with branches 3 and circled by a rotor binding 8, although these characteristics are only optional. The same is true for the hub 2.

[0127] Advantageously but not restrictively, a periphery of the rotor 1 can be formed by a layer of composite coating optionally reinforced with fibers, with the optional insertion of a cover membrane for each face of the rotor 1.

[0128] The rotor 1 can be part of an axial flux electromagnetic machine associated with one or more stators. There can also be a plurality of rotors in the electromagnetic machine.

[0129] The invention is by no means limited to the embodiments described and illustrated, which are presented only by way of example.