MAGNET SYSTEM FOR A ROTOR AND PERMANENT MAGNET ELECTRICAL MACHINE

Abstract

A method a magnet system for a rotor of a permanent magnet electrical machine includes: a first module including a first support member; a second module includes a second support member; wherein the first module includes a first permanent magnet supported by the first support member and/or the second module includes a second permanent magnet supported by the second support member, wherein the first support member and the second support member have respective contact portions which are at least partly structurally complementary to each other allowing to arrange the first module and the second module adjacent to each other in the axial direction, while the contact portions contact each other and causing traverse shift in a direction travers to the axial direction, when pushed towards each other in the axial direction.

Claims

1. A magnet system for a rotor of a permanent magnet electrical machine, comprising: a first module comprising a first support member; a second module comprising a second support member; wherein the first module comprises a first permanent magnet supported by the first support member and/or the second module comprises a second permanent magnet supported by the second support member, wherein the first support member and the second support member have respective contact portions which are at least partly structurally complementary to each other allowing to arrange the first module and the second module adjacent to each other in the axial direction, while the contact portions contact each other and causing traverse shift in a direction travers to the axial direction, when pushed towards each other in the axial direction.

2. The magnet system according to claim 1, wherein the contact portion of each support member is arranged close to a side edge of the respective support member and/or at an axial end and/or wherein the contact portion is integrally formed with the respective support member.

3. The magnet system according to claim 1, wherein the contact portion of the first support member is arranged at an axial end of the first support member, wherein the first support member has another contact portion at another axial end, and/or wherein the contact portion of the second support member is arranged at an axial end of the second support member, wherein the second support member has another contact portion at another axial end.

4. The magnet system according to claim 1, wherein the contact portion and/or the other contact portion of the first support member comprises a tapered, protrusion protruding in the axial direction, wherein the contact portion and/or the other contact portion of the second support member is formed by a tapered, recess recessed in the axial direction.

5. The magnet system according to claim 1, wherein the protrusion partly deforms when pushed along the axial direction into the recess.

6. The magnet system according to claim 1, wherein the protrusion and material limiting the recess have complementary sliding surfaces tilted relative to the axial direction, thereby engaging in a wedge like manner and/or wherein the protrusion and the recess are shaped such that when the protrusion is entirely inserted into the recess, edges of the first support member and the second support member contact each other.

7. The magnet system according to claim 4, wherein the protrusion and/or the recess has trapezoid shape or triangular shape or tapered rectangular shape.

8. The magnet system according to claim 4, wherein the protrusion and/or the recess is over the whole thickness or over only a part of the thickness of the respective support member.

9. The magnet system according to claim 4, wherein the protrusion and/or the recess has an extent in axial direction of the support member of between 0.1 and 0.2 of an axial extent of the support member and/or wherein the first support member and/or the second support member is essentially configured as metal base plate.

10. The magnet system according to claim 4, wherein at least one of the following holds: the first support member and/or the second support have essentially the same shape; the first support member and/or the second support have the same shape and 180° rotation symmetry; the first support member and/or the second support have different shapes; the first support member and/or the second support have a mirror symmetry.

11. The magnet system according to claim 4, wherein the first support member and/or the second support has a protrusion as well as a recess or wherein the first support member and/or the second support has only at least one protrusion but no recess or wherein the first support member and/or the second support has no protrusion but only at least one recess.

12. A rotor for a permanent magnet electrical machine, comprising: a rotor yoke comprising plural axially extending rails; the magnet system according to claim 1 inserted between a first rail and a second rail spaced apart in the circumferential direction in the axial direction to push against a first axial stop and clamped between the first axial stop and a second axial stop.

13. The rotor according to claim 12, wherein the magnet system is inserted into the two adjacent rails such that the first support member is in contact with the first rail and the second support member is in contact with the second rail.

14. A permanent magnet electrical machine, comprising: a stator; and the rotor according to claim 13.

15. A wind turbine comprising the permanent magnet electrical machine according to claim 14.

Description

BRIEF DESCRIPTION

[0044] Some of the embodiments will be described in detail, with reference to the following figures, wherein like designations denote like members, wherein:

[0045] FIG. 1 schematically illustrates a rotor for a permanent magnet electrical machine according to an embodiment of the present invention;

[0046] FIG. 2 schematically illustrates a portion of the rotor illustrated in FIG. 1;

[0047] FIG. 3 schematically illustrates a magnet system according to an embodiment of the present invention as is for example installed in the rotor illustrated in FIG. 1;

[0048] FIG. 4 illustrates a magnet system according to an embodiment of the present invention; FIG. 5 illustrates a magnet system according to an embodiment of the present invention; FIG. 6 schematically illustrates a module two of which form a magnet system according to an embodiment of the present invention;

[0049] FIG. 7 schematically illustrates a magnet system according to an embodiment of the present invention;

[0050] FIG. 8 schematically illustrates a second support member of the magnet system illustrated in FIG. 7;

[0051] FIG. 9 schematically illustrates the material limiting the recess provides a sliding surface, along which a sliding surface of the protrusion can slide thereby exerting a clamping force.;

[0052] FIG. 10 illustrates a first magnet module comprised in the magnet system illustrated in FIG. 7; and

[0053] FIG. 11 schematically illustrates a protrusion only over a portion of the thickness of the first support member.

DETAILED DESCRIPTION

[0054] The illustration in the drawings is in schematic form. It is noted that in different figures, elements similar or identical in structure and/or function are provided with the same reference signs or with reference signs, which differ only within the first digit. A description of an element not described in one embodiment may be taken from a description of this element with respect to another embodiment.

[0055] The rotor 150 schematically illustrated in FIG. 1 in a cross-sectional view sectioned perpendicular to an axial direction 101 comprises a rotor yoke 103 comprising plural axially extending rails 105, 107. The rotor 150 further comprises at least one magnet system 100 according to an embodiment of the present invention which is inserted between a first rail 105 and a second rail 107 which are spaced apart in the circumferential direction 109. The magnet system 100 is inserted in the axial direction 101 between the first rail 105 and the second rail 107. In particular, the magnet system 100 comprises plural magnet modules (for example magnet modules 310a, 310b, 310c, 310d, 310e) as is illustrated in FIG. 3 in a view along the radial direction 311 which is indicated with reference sign 111 in FIG. 1.

[0056] The rotor 150 illustrated in FIG. 1 can be utilized in a permanent magnet electrical machine which further comprises a stator inside the rotor 150.

[0057] FIG. 2 schematically illustrates a portion of the rotor 150 illustrated in FIG. 1 which portion is labelled in FIG. 1 with reference sign 117. The portion 217 illustrated in FIG. 2 is a cross-sectional illustration seen along the axial direction 201, the circumferential direction is labelled with reference sign 209. As can be appreciated from FIG. 2, the first rail 205 has a “T”-shape in the cross-sectional view which also holds for the second rail 207.

[0058] From the magnet system 200, only a single magnet module, namely the magnet module 210, i.e. a first magnet module, is visible. A second and possibly even more magnet modules is/are arranged behind the first magnet module 210. The magnet module 210 comprises a first support member 242 for supporting a first magnet 244. The first support member 242 does not have equal thickness over the entire area but comprises a region at which the first magnet 244 is mounted which has a greater thickness than in a border area 246. The magnet 244 is mounted at an area where the thickness is greater than in the border or boundary area 246.

[0059] As can be seen in FIG. 2 between the stem 248 of the “T” and the circumferential edge 252 of the first support member 242, a gap is present which is denoted by reference sign 254. The gap may have a size between 0.5 mm and 0.01 mm. The gap 254 may allow to easily slide in the magnet module 210 between the first rail 205 and the second rail 207. However, in a conventional system, during operation, the magnet module 210 may move in the tangential direction 209 which may cause problems.

[0060] Therefore, in interface regions between adjacent magnet modules 310a, . . . , 310e, (see FIG. 3) respective contact portions are provided as will be explained in more detail with reference to FIGS. 4 to 11 below.

[0061] FIG. 3 schematically illustrates a magnet system 300 in a view along the radial direction 311 comprising six magnet modules 310a, 310b, 310c, 310d, 310e. The magnet modules are lined up in the axial direction 301 and are arranged between a first axial stop element 313 and a second axial stop element 315. In particular, the six magnet modules 310a, . . . , 310e are clamped between the first axial stop element 313 and the second axial stop element 315. In the circumferential direction 309, the chain of magnet modules is limited or hold by the first rail 305 and the second rail 307.

[0062] FIG. 4 illustrates, along the radial direction 411, a magnet system 400 according to an embodiment of the present invention comprising a first magnet module 410a and a second magnet module 410b. Each of the magnet modules 410a, 410b comprises a respective magnet 444a, 444b mounted on a respective first support member 442a and 442b, respectively. The two magnet modules 410a, 410b have a similar construction both comprising a recess 460a and 460b at an axial side and both also comprising a protrusion 470a, 470b. The protrusion 470a, 470b is wedge-like or slanted and has a complementary structure or shape complementary to the shape of the recess 460a, 460b. When inserted between the two rails (for example illustrated in FIG. 1 or 2), the first and second magnet modules 410a, 410b will contact each other with their axial ends 462, 464 and the protrusion 470a will completely or at least partly fill the space provided by the cavity 460b. Thereupon traverse forces 466, 468 are exerted to the first magnet module 410a and to the second magnet module 410b which are opposite to each other. Thereby, the two adjacent magnet modules 410a, 410b will be pushed traverse to the axial direction 401 such as to contact circumferentially limiting rail portions of the first rail 205 and the second rail 207, respectively.

[0063] As can be seen in FIG. 4, the contact portions are configured as protrusions and recesses 470, 460 and are arranged close to a side edge (in particular circumferential side edge) of the respective magnet modules. Further, the protrusions 470a, 470b are integrally formed with the respective support members 442a, 442b. It is also visible in FIG. 4 that the respective contact portions (implemented by the recesses 460 and the protrusions 470) are provided at two axial ends of the respective support members. The protrusion 470a, 470b is tapered which also holds for the recess 460a, 460b.

[0064] FIG. 5 schematically illustrates another magnet system 500 according to an embodiment of the present invention. While the support members 442a, 442b illustrated in FIG. 4 have similar structure or at least similar contact portions, the first support member 542a comprises protrusions 570a, 570b at both axial ends. Further, the second support member 542b comprises recesses 560a and 560b at both axial ends. When pushed against each other in the axial direction 511, the first support member 442a will be pushed by the traverse force 566 (to the right in FIG. 5) while the second support member 542b will be pushed by the traverse force 568 (to the left) in FIG. 5. Thus, the support members 442a, 442b will be pushed to different rails, for example one to the first rail 205 and the other to the second rail 207 illustrated in FIG. 2. The support member 542a, 542b or in general the magnet module 510a, 510b have a mirror symmetry with respect to a mirror plane running in the plane spanned by the circumferential direction 409 and the radial direction 411.

[0065] FIG. 6 illustrates one magnet module 610a as a part of a magnet system according to an embodiment of the present invention. A magnet system may be formed by two or more of the magnet modules 610a illustrated in FIG. 6. The magnet module 610a comprises a recess 660a as well as a protrusion 670a at a first circumferential edge. Further, the magnet module 610a comprises a protrusion 670b and a recess 660b at another circumferential edge. Further, the magnet module 610a has a 180° rotation symmetry around a rotation axis 671 running along the radial direction 611.

[0066] It is noted that the protrusions and recesses illustrated in FIGS. 4, 5 and 6 are provided over the whole thickness of the respective support member.

[0067] Embodiments of the present invention provide however also a magnet system, wherein contact portions of the respective magnet module are only over a part of the thickness of the respective support member. An example of a magnet system 700 is illustrated in FIG. 7 comprising a first magnet module 710a and a second magnet module 710b. The first magnet module 710a comprises a protrusion 770a and the second magnet module 710b comprises a recess 760b which is then partly filled by the protrusion 770a when the two magnet modules 710a, 710b are arranged close to each other and aligned in the axial direction 701.

[0068] FIGS. 8 and 9 illustrate in more detail the second magnet module 710b and FIGS. 10 and 11 illustrate in more detail the first magnet module 710a.

[0069] The support member 742b of the second magnet module 710b has the recess 760b at a corner such that the recess is only over a portion of the thickness of the support member 742b. In particular, the recess 760b is even beneath the magnet 744b.

[0070] In contrast, the first magnet module 710a illustrated in FIGS. 10 and 11 comprises a protrusion 770a only over a portion of the thickness of the first support member 742a.

[0071] As can be seen for example in FIG. 9, the material limiting the recess 760b provides a sliding surface 772, along which a sliding surface 774 of the protrusion 770a can slide thereby exerting a clamping force. Furthermore, the protrusion 770a has a trapezoid shape. The recess 760b has a triangular shape.

[0072] With reference to FIGS. 4, 5 and 6, the protrusion or tip 470a, 470b, 570a, 570b may be pushed into the space of the removed part (i.e., the recess 460a, 460b, 560a, 560b of the adjacent magnet base plate of support member). The removed part of the base plate or support member may be smaller than the protrusion or top so that the tip or protrusion can fill out the removed part plus the difference between the base plate width and the slot width. By hard pressing the protrusion or the tip, the tip or protrusion can even be deformed and may also thereby act as a lock. By adjusting the dimensions of the removed part and the tip, i.e., the dimension of the recess and the protrusion, and adjusting the pressing force there will be no/very little distance between the magnet modules.

[0073] The magnet modules may be pressed against the slot walls (also referred to as rail walls), preventing movement of the magnet/magnet module in the tangential direction in all operating conditions. The magnet blocks and the magnet cover may similarly as conventionally known. The tilt of the protrusions or recesses is selected such that upon acting an axial force to the magnet modules, the modules will be pushed in a direction traverse to the axial direction, thus towards the walls or sides of the rails or the slot, for example the rails 205 and 207 illustrated in FIG. 2. Thereby, the axial force may for example be exerted on the magnet module at the NDE of the slot. The protrusion may also be described as a conical tip and the recess may be referred to as a cut-out. The conical tip and the cut-out may act like one or two wedge(s) and thereby will exert tangential forces at the respective support members for pressing them towards the rail walls, thereby eliminating the gap 254 illustrated in FIG. 2 at one side.

[0074] Although the present invention has been disclosed in the form of preferred embodiments and variations thereon, it will be understood that numerous additional modifications and variations could be made thereto without departing from the scope of the invention.

[0075] For the sake of clarity, it is to be understood that the use of “a” or “an” throughout this application does not exclude a plurality, and “comprising” does not exclude other steps or elements.