Rotor for an electric machine, preferably an electric motor, and method for producing a rotor

Abstract

The invention relates to a rotor intended for an electric machine, the rotor having a rotor shell (2) and an end wall (6) at one end of the rotor shell (2). The rotor shell (2) and the end wall (6) consist of magnetizable material and are at least partially magnetized. The rotor is produced from a magnetizable material. The rotor shell (2) and the end wall (6) are magnetized by way of a combined radial and axial Halbach array.

Description

[0001] Rotor for an electrical machine, preferably an electric motor, and method for producing a rotor

[0002] The invention relates to a rotor for an electrical machine, preferably an electric motor, according to the preamble of claim 1 and to a method for producing such a rotor according to the preamble of claim 13.

[0003] Electric motors are known in which the rotating rotor surrounds a stator (external rotor topology). Examples of such electric motors are permanent magnet synchronous motors, which have magnets on the inside of the rotor shell that are suitably attached to the rotor shell.

[0004] They interact in a familiar way with the current-carrying windings of the stator during operation of the electric motor. The magnets are generally free of rare earth elements and have a low torque density. Such permanent magnet synchronous motors are subject to the problem of noise and vibration excitation due to cogging torque. Furthermore, such rotors are complex and expensive to manufacture. If the rotor of external rotor motors has a soft magnetic rotor yoke, the problem of a high rotor moment of inertia also arises.

[0005] The invention is based on the object of designing the generic rotor and the generic method in such a way that the described disadvantages do not occur or only occur to a negligibly small extent.

[0006] This object is achieved in the generic rotor according to the invention with the characterizing features of claim 1 and in the generic method according to the invention with the characterizing features of claim 13. The rotor according to the invention is characterized in that the rotor shell and the end wall of the rotor are each at least partially magnetized. The material used for the rotor shell and the end wall is a correspondingly magnetizable material that can be magnetized with a suitable magnetizing device. Since both the rotor shell and the end wall of the rotor are magnetized, a three-dimensional magnet geometry with a high torque density is obtained. As a result of the design according to the invention, a steel yoke in the rotor can be partially, but advantageously completely, eliminated.This results in a very low rotor moment of inertia because the magnetized end wall can also be used to drive the rotor. In particular, a magnetic bonding process, which is necessary for attaching the magnets to the rotor shell in conventional rotors, can be eliminated.

[0007] In a preferred design, a multipole Halbach array is present in the rotor shell and the end wall. Compared to other magnetic anisotropies, Halbach magnetization enables a very low cogging torque. This significantly reduces electromagnetic excitation.

[0008] Advantageously, the rotor shell has a predominantly radial magnetic polarization.

[0009] The end wall, on the other hand, advantageously has a predominantly axial magnetic polarization.

[0010] The radial and axial polarization of the rotor shell and the end wall results in a three-dimensional magnetic geometry with a high torque density. In the transition area between the rotor shell and the end wall, a polarization can be provided that lies between an axial and a radial magnetic polarization, which primarily has diagonal magnetic polarization components. It is advantageous, especially with regard to manufacturing, if the rotor shell and the end wall have an even number of poles.

[0011] Preferably, the rotor shell and the end wall have the same number of poles.

[0012] A particularly advantageous design is achieved when the rotor shell and the end wall are formed as a single piece. This allows for simple rotor production.

[0013] The rotor shell is advantageously magnetized in such a way that it has the greatest flux density on its inner side, which decreases towards the outer side.

[0014] To further reduce the rotor mass inertia, it is advantageous if the rotor shell has at least one recess on its outer side in the region of low flux densities.

[0015] The recess advantageously extends over the height of the rotor shell.

[0016] The recesses can have a wide variety of contours, viewed in the axial direction of the rotor. The recesses also allow for savings in material used in rotor manufacturing.

[0017] A particularly suitable material for the rotor is a plastic-bonded magnetic material, which allows for simple and reliable rotor production. Such materials are advantageously plastic-bonded permanent magnet materials, which allow the rotor to be manufactured cost-effectively using injection molding or die-casting processes.

[0018] In the method according to the invention, the end wall and the rotor shell are made of a magnetizable material, and the rotor shell and the end wall are magnetized using a combined radial and axial Halbach magnetizing device. This magnetizing process is simple to perform and enables straightforward rotor production.

[0019] The rotor can advantageously be manufactured using an injection-molding or die-casting process. A suitable material is used for this, preferably a plastic-bonded permanent magnet material, which is cost-effective and allows for problem-free production.

[0020] In a preferred embodiment, the rotor shell and the end wall are magnetized during the manufacturing process. This creates an anisotropic magnet. The magnetization is thus already performed during the rotor manufacturing process.

[0021] If a magnetic field is omitted during the manufacturing process, an isotropic magnet is created. Magnetization of the rotor shell and end wall is then advantageously performed after the manufacturing process.

[0022] The processes can further be combined so that a partial orientation of the magnetic material is achieved during the manufacturing process and the rotor is then completely magnetized using a magnetizing device.

[0023] The subject matter of the application arises not only from the subject matter of the individual patent claims, but also from all information and features disclosed in the drawings and the description. Even if they are not the subject matter of the claims, they are claimed as essential to the invention insofar as they are novel, individually or in combination, over the prior art. Further features of the invention emerge from the further claims, the description, and the drawings.

[0024] The invention will be explained in more detail with reference to some embodiments shown in the drawings.

[0025] Fig. 1 shows a schematic representation of a rotor according to the invention in side view,

[0026] Fig. 2 shows a schematic representation of an end wall of the rotor according to Fig. 1 with the magnetic flux drawn in,

[0027] Fig. 3 shows a schematic front view of the casing of the rotor according to Fig. 1 with magnetic flux lines,

[0028] Fig. 4 shows a schematic representation of the rotor according to Fig. 1 together with a magnetizing device,

[0029] Fig. 5 is a front view of the magnetizing device according to Fig. 4,

[0030] Fig. 6 shows in axial view the casing of the rotor according to Fig. 4 with the magnetizing device and the magnetic flux lines in the rotor casing,

[0031] Fig. 7 shows a schematic representation and an axial view of another embodiment of a rotor shell of a rotor according to the invention,

[0032] Fig. 8 shows a schematic representation of a further embodiment of a rotor according to the invention with a magnetizing device for the casing and end wall with a one-piece coil and field lines drawn in the end wall, Fig. 8a shows a schematic and perspective representation of the magnetizing device according to Fig. 8,

[0033] Fig. 8b and 8c in a representation corresponding to Fig. 8a further embodiments of bevelled magnetizing devices,

[0034] Fig. 9 shows in axial half-section a concrete embodiment of an electric motor with a rotor according to the invention,

[0035] Fig. 10 in a representation corresponding to Fig. 9 a further embodiment of an electric motor with a rotor according to the invention.

[0036] Fig. 9 shows, in axial half-section, part of an electric motor with a rotor 1 which has a cylindrical casing 2 which surrounds a stator 3 at a short distance. It is only shown schematically because its design is known. The stator 3 has a stator bushing 4 into which a rotor shaft 5 projects. Its right-hand end in Fig. 9 is fastened in an end wall 6 of the rotor 1. This end of the rotor shaft 5 is advantageously held in an insert bushing 7 which is advantageously embedded in the end wall 6. The insert bushing 7 is advantageously introduced during the shaping production process of the rotor 1 so that the insert bushing 7 is embedded in the end wall 6. An additional fastening process for the insert bushing 7 is therefore not necessary.

[0037] Instead of the insert bushing 7, any other suitable connecting element can be used to fasten the rotor shaft 5.

[0038] The rotor shaft 5 is rotatably mounted in the stator bushing 4 by means of at least one bearing 7, preferably two bearings 8. They are axially spaced from one another and, in this embodiment, are ball bearings. Other rolling bearings can also be used. Even plain bearings are possible for the rotary mounting of the rotor shaft 5 in the stator 3. The bearings 8 are suitably mounted in the inner wall 9 of the stator bushing 4 and on the rotor shaft 5.

[0039] The stator bushing 4 is adjoined by a stator flange 10 which extends radially outwards from the stator bushing 4 and is advantageously formed integrally with the stator bushing 4.

[0040] A housing (not shown) can be attached to the stator flange 10 in a known manner, which housing, for example, a power electronics unit of the electric motor.

[0041] Attachments, such as a fan impeller, can be provided on the rotor 1. Such an impeller is then provided on the casing 2 of the rotor 1. Cooling fins, for example, can also be provided on the casing 2, which are provided on an outer flange of the casing 2 and are advantageously directed toward the stator flange 10.

[0042] Cooling fins may also be present on the stator flange 10, facing the cooling fins of the rotor-side flange. The cooling fins of the stator flange 10 and the rotor shell 2 serve to cool the electric motor during operation.

[0043] In the illustrated embodiment, the casing 2 and the end wall 6 are made of a magnetizable material. Such a material can be, for example, a plastic-bonded permanent magnet material, such as hard ferrite p, ReFeB p, AlNiCo p, and the like. Rotor 1 can be manufactured using these materials using an injection-molding or die-casting process.

[0044] For the rotor 1, an isotropic plastic-bonded permanent magnet is considered, which is subsequently magnetized, or an anisotropic plastic-bonded permanent magnet which is magnetized during the manufacturing process by means of a magnetizing / aligning device. The rotor 1 has different directions of the magnetic flux, as can be seen by way of example from Fig. 9. The corresponding magnetic polarizations J are indicated in Fig. 9. In the region of the rotor shell 2, a radial component Jradiai of the magnetic polarization J is present, and in the region of the end wall 6, an axial field component Jaxiai of the magnetic polarization J is present. In the transition region between the shell 2 and the end wall 6, a diagonal component Jdiag of the magnetic polarization J is present.

[0045] If an isotropic plastic-bonded permanent magnet is used as the material for rotor 1, it is magnetized after the rotor 1 is manufactured. For this purpose, an axial and a radial Halbach magnetizing head are used in combination.

[0046] In the case of an anisotropic permanent magnet, the magnetic polarization J is established during the manufacture of the rotor 1 by means of an alignment device.

[0047] As shown in Fig. 9, the three-dimensional guidance of the magnetic flux in rotor 1 is provided by the combination of a radially tangential and an axially tangential Halbach magnet system. This significantly increases the torque density. During the manufacturing process, the external magnetic field is applied in such a way that a multi-pole Halbach array is created in both the radial and axial directions. This advantageously makes it possible to at least partially or even completely eliminate the need for a steel yoke in rotor 1. This has the consequence that the rotor moment of inertia can be reduced. A magnetic bonding process, as required for conventional rotors with bonded magnets, is no longer necessary. Compared to other magnetic anisotropies, Halbach magnetization enables the lowest cogging torque and thus reduces the electromagnetic excitations of the electric machine.In the exemplary embodiment, the entire casing 2 and the entire end wall 6 are made of the magnetizable material. In principle, it is also possible to manufacture the rotor casing 2 and the end wall 6 from a magnetizable material only in those areas that are subsequently to be magnetized.

[0048] In the embodiment shown in Fig. 10, the casing 2 and the end wall 5 of the rotor 1 are separate parts. The end wall 6 is a flat disc that is attached to one end face 11 of the cylindrical casing 2 in such a way that it does not protrude radially beyond the casing 2. Advantageously, the casing 2 and the end wall 6 have the same outer diameter.

[0049] The connection between the shell 2 and the end wall 6 can be made in any suitable manner. For example, the end wall 6 can be glued to the end face 11 of the shell 2. The disc-shaped end wall 6 can also be inserted into the mold during the manufacturing process, so that it is firmly connected to the rotor shell 2. Pressing, screwing, riveting, or the like to connect the end wall 6 to the rotor shell 2 is also possible.

[0050] The rotor shaft 5 can be connected to the end wall 6 in a rotationally fixed manner according to the previous embodiment.

[0051] In accordance with the previous embodiment, the rotor shaft 5 is also rotatably mounted in the stator bushing 4 of the stator 3 via at least one bearing 8, preferably via two bearings arranged at an axial distance from one another.

[0052] In this embodiment, the rotor shell 2 is designed according to the previous embodiment, having the magnetic polarization J radiai . The end wall 6 has the magnetic polarization J axiai . The rotor shell 2 can be made entirely or in part from the magnetizable material, as explained with reference to the previous embodiment.

[0053] Figs. 1 to 3 schematically show the rotor 1 according to the embodiment shown in Fig. 10. The rotor 1 has the cylindrical shell 2 and the end wall 6. The rotor shaft 5 is non-rotatably attached to the end wall 6. It projects axially beyond the rotor shell 2 on the side facing the end wall 6.

[0054] The casing 2 and the end wall 6 are made of plastic-bonded magnetic material into which inserts can be integrated during the manufacturing process, as explained with reference to Figs. 9 and 10.

[0055] The end wall 6 is provided with an axial-tangential Halbach anisotropy or is treated with axial-tangential magnetization. This means that during the magnetization process, the magnetic field lines from the magnetizing device first enter the end wall 6 axially, run tangentially there, and exit the end wall 6 axially again.

[0056] Fig. 2 shows schematically the course of the corresponding magnetic field lines in the end wall 6.

[0057] The rotor shell 2 exhibits a radial-tangential Halbach anisotropy, or rather, has been treated with a radial-tangential magnetization. This means that during the magnetization process, the magnetic field lines from the magnetizing device enter the rotor shell 2 radially, run tangentially within the rotor shell 2, and exit the rotor shell 2 radially.

[0058] Fig. 3 shows schematically the course of the magnetic field lines in the rotor shell 2.

[0059] Advantageously, the number of poles and the polarity of the magnetization of the end wall 6 and the rotor shell 2 are the same. Any even number of poles (2, 4, 6, 8, etc.) is conceivable. As explained by way of example with reference to Fig. 9, the transition of the magnetization or magnetic anisotropy from the end wall 6 to the rotor shell 2 can optionally be provided with a mixed radial, tangential, and axial Halbach component jdiag.

[0060] Fig. 4 shows a schematic representation of two magnetizing devices 12, with which the rotor shell 2 and the end wall 6 are magnetized. The magnetizing device 12 has a single- or multi-part magnetizing or alignment device 13, which comprises electrically excited field coils or permanent magnets. Furthermore, the magnetizing device 12 is provided with an axial-tangential magnetizing or alignment device 14.

[0061] The rotor shell 2 is magnetized with the magnetizing / aligning device 13 and the end wall 6 of the rotor 1 is magnetized with the magnetizing / aligning device 14.

[0062] Fig. 4 shows a schematic representation of the magnetic field strength H. It is the result of a magnetic field created around the current-carrying conductors of the magnetizing / aligning devices 13, 14.

[0063] The magnetizing / aligning device 13 for the rotor shell 2 has two pole cores 16, 17, each surrounded by current-carrying coils (not shown). The pole cores 16, 17 are parallel to one another and parallel to the axis 44 of the rotor shell 2. In the exemplary embodiment, the magnetizing device 12 has four magnetizing / aligning devices 13, 14, which are evenly distributed over the circumference of the rotor shell 2. It is advantageous if the magnetizing / aligning devices 13, 14 are radially and / or axially adjustable so that they can each be optimally adjusted with respect to the cylindrical inner side of the rotor shell 2 or the end face 6. Fig. 6 shows a schematic and exemplary illustration of a magnetizing device 12 having eight magnetizing / aligning devices, of which only the magnetizing / aligning devices 13 for the rotor shell 2 are shown. They are designed in the same way as the magnetizing / aligning devices 13, 14 according to Fig.4 and 5.

[0064] The pole cores 16, 17 are surrounded by corresponding current-carrying coils and are located at a short distance from the inner side 15 of the rotor shell 2 (Fig. 6) and the underside of the end wall 6.

[0065] According to the previous embodiment, the magnetizing / aligning devices 13, 14 can be axially and / or radially adjustable.

[0066] The magnetizing / aligning devices 13, 14 are each of identical design and have a large pole width 24 and a small pole transition width 25. The length of the pole cores 16, 17 measured in the axial direction of the rotor 1 determines the axial dimension of the magnetization of the rotor shell 2.

[0067] As shown in Fig. 6, adjacent magnetizing / aligning devices 13, 14 are arranged at 180° angles to each other. The pole cores 16, 17 form the radial-tangential magnetizing / aligning device 13.

[0068] The ends of the pole cores 16, 17 facing the end wall 6 are connected to one another by a pole core 18. It is advantageously arcuate (Fig. 5) and is surrounded by at least one current-carrying coil (not shown). The pole core 18 forms the axial-tangential magnetizing / aligning device 14, with which the end wall 6 is magnetized. The axial-tangential magnetizing / aligning device 14 is located within the interior space 30 of the rotor 1, enclosed by the rotor shell 2, at a short distance from the underside of the end wall 6.

[0069] The pole cores 18 are each approximately semicircular and provided with the electrically excitable field coils used to magnetize the end wall 6. The pole cores 18 are advantageously of identical design and have a pole width of 31 and a pole depth of 32.

[0070] The pole cores 18 are arranged at a distance from one another such that the pole transition width 33 is relatively small.

[0071] Relative to the circular disk-shaped end wall 6, the pole cores 18 are distributed over the circumference of the end wall 6. The pole cores 18 are spaced apart from the underside of the end wall 6 at a distance 34 (Fig. 4). Advantageously, the pole cores 18 are designed so that they have a constant thickness along their length. Then, the pole cores 18 are located below the end wall 6 at a distance 34. Advantageously, the distance 34 is minimal.

[0072] According to Fig. 5, adjacent pole cores 18 are arranged rotated by 180° to each other, so that the current-carrying ends of adjacent magnetizing / aligning devices 14 are adjacent to each other.

[0073] The pole cores 18 are positioned such that they do not protrude beyond the edge of the end wall 6, but their pole ends are a short distance from the edge of the end wall 6.

[0074] The magnetizing / aligning device 14 is designed such that the pole cores 18 have an optimized ratio of the largest possible pole width 31, the largest possible pole depth 32, and the smallest possible pole transition width 33. With the pole pitch TP (Fig. 5), an optimal pole width results at values ​​between % to approximately 1 * Tp with a pole transition width 33 of 0 to approximately % • TP. An optimal pole depth 32 is achieved with values ​​of approximately 30% to approximately 50% of the outer diameter of the magnetizing / aligning device 14.

[0075] The magnetizing device 12 with the magnetizing / aligning devices 13, 14 can be designed in one piece, but also in several parts.

[0076] Instead of the electrically excited field coils, the magnetizing / aligning devices 13, 14 can also have permanent magnets with which the rotor shell 2 and the end wall 6 can be magnetized.

[0077] As can be seen from Figs. 3 and 4, the magnetic field H of the magnetizing / aligning device 13 acts in the radial and tangential directions relative to the cylindrical rotor shell 2. The magnetizing / aligning device 14, on the other hand, acts in the axial and tangential directions relative to the end wall 6 of the rotor 1 (Figs. 2 and 4).

[0078] This design of the magnetizing / aligning device 12 allows the magnetization with the components J radiai and J axiai and, if applicable, Jdiag to be produced easily and reliably.

[0079] The magnetizing device 12 represents a Halbach magnetizing head, which can be used to create a combination of a radial-tangential and an axial-tangential Halbach magnet system on the rotor 1. This combination of a radial-tangential and an axial-tangential Halbach magnet system results in a rotor 1 with a three-dimensional magnetic flux pattern that can be generated in a single magnetization process.

[0080] The magnetizing device 12 can be used for magnetization during the injection molding or compression molding process for producing the rotor 1. The magnetizing device 12 is inserted into the mold so that the magnetization process can take place within the mold. When the rotor 1 is removed from the mold, it is already magnetized to the required degree. This process creates an anisotropic magnet.

[0081] However, it is also possible to first manufacture the rotor 1 and then magnetize it with the magnetizing device 12. This creates an isotropic magnet.

[0082] For the subsequent magnetization after the manufacture of the rotor 1, the same magnetizing device 12 can be used as previously described by way of example.

[0083] Fig. 6 shows the magnetic field lines in the rotor shell 2. The magnetizing device 12 or the magnetizing / aligning device 13 creates circumferentially adjacent magnetic field sectors 36 in the rotor shell 2, which have a high magnetic flux density on the cylindrical inner side 15 of the rotor shell 2. The magnetic flux density of the magnetic field sectors 36 decreases radially outward.

[0084] The magnetic field sectors 36 extend over the circumference of the rotor shell

[0085] 2 together.

[0086] Fig. 7 shows the exemplary possibility of providing recesses 38 on the outer side 37 of the rotor 1, which are advantageously arranged evenly distributed over the circumference of the rotor shell 2 and extend over the axial height of the rotor shell 2. The recesses 38 are provided in the region of low flux densities, for example in the predominantly radial Halbach sectors. The shape of the recesses 38 can basically be arbitrary. In the illustrated embodiment, the recesses 38 have a concavely curved bottom 39 that extends to the outer side 37. The bottom 39 can also have straight sections, for example, so that the recess 38, viewed in the axial direction of the rotor 1, has an approximately rectangular or trapezoidal shape.

[0087] Since the recesses 38 are provided in the area of ​​low flux densities, the function of the rotor 1 for the electric motor is not impaired. Furthermore, the recesses 38 have the advantage of minimizing the rotor's mass inertia. Less material is also required for the rotor 1.

[0088] Fig. 8 and 8a show a magnetizing device 12 in which the magnetizing / aligning device 14 for the end wall 6 of the rotor 1 and the magnetizing / aligning device 13 for the rotor shell 2 are formed integrally with one another.

[0089] The two magnetizing / aligning devices 13, 14 are connected to one another in accordance with the previous embodiment in such a way that both the end wall 6 and the rotor shell 2 can be magnetized simultaneously.

[0090] Several such magnetizing devices 12 can be arranged over the circumference of the rotor shell 2, as shown by way of example in Fig. 5.

[0091] According to the number of magnetizing devices 12, the rotor shell 2 and the end wall 6 have a corresponding number of poles.

[0092] The magnetizing device 12 has two pole cores 41, 42, which are provided with current-carrying coils (not shown), which are located opposite the inner side 15 of the rotor shell 2 during the magnetizing process. The two pole cores 41, 42 are connected to one another at one end by a curved pole core 43 formed integrally with them. It extends transversely, preferably perpendicularly, to the pole cores 41, 42, which extend parallel to one another. The pole core 43 is located opposite the end wall 6 and is also surrounded by at least one current-carrying coil (not shown).

[0093] As in the previous embodiments, the magnetizing device 12 ensures that the magnetic flux density is densest not only on the cylindrical inner wall 15 of the rotor shell 2, but also on the underside 40 of the end wall 6. The magnetic flux density decreases radially outward, or toward the outer side 41 of the end wall 6, as can be seen from Fig. 8 for the end wall 6 and from Figs. 6 and 7 for the rotor shell 2.

[0094] With the aid of the magnetizing device 12, it is possible in the described embodiments to provide a slanted topology of magnetization on the rotor shell 2. For this purpose, the corresponding coils or permanent magnets of the magnetizing devices 12 are arranged at a corresponding angle to produce the desired slant. In this way, a continuous slant, a staggered slant, a V-slant and the like can be created. With a continuous slant, the slant runs continuously at an angle across the height of the rotor shell 2. With a staggered slant, the slant only runs over part of the height of the rotor shell 2, with adjacent slant points being staggered relative to one another. With a V-slant, a corresponding slant across the height of the rotor shell 2 results in a V-shape, viewed in the radial direction of the rotor shell 2.

[0095] Fig. 8b shows an example of such a magnetizing device 12, with which the described oblique magnetization topology can be achieved. The magnetizing device 12 is fundamentally designed in the same way as the embodiment according to Fig. 8a. The only difference is that the mutually parallel pole cores 41, 42 do not run parallel to the axis 44 of the rotor shell 2, but rather at a helix angle α, viewed perpendicular to the rotor shell axis 44. Fig. 8c shows a magnetizing device 12 that has permanent magnets 45, 46 for magnetizing the rotor shell 2 and the end wall 6 of the rotor 1. The permanent magnets 46 form the magnetizing / aligning device 14 for magnetizing the end wall 6 and the permanent magnets 45 form the magnetizing / aligning device 13 for magnetizing the rotor shell 2. In the vertical direction of the magnetizing device 12, the permanent magnets 45 are offset from one another according to the desired helix angle a.

[0096] Fig. 8c clearly shows the Halbach structure of the magnetizing device 12. The required orientation of the permanent magnets is indicated in the usual way.

[0097] In the manner described with reference to the various embodiments, a multi-pole Halbach array is formed on the rotor shell 2 and on the end wall 6 in both the radial and axial directions. By using the Halbach structure, the steel yoke typically provided in the rotor 1 can be at least partially, and advantageously even completely, eliminated. The Halbach magnetization described enables the lowest cogging torque compared to conventional magnetic anisotropies. This reduces the electromagnetic excitations of the electrical machine in which the rotor 1 is installed. Since not only the rotor shell 2 but also the end wall 6 is magnetized, the end wall 6 contributes to generating the torque of the rotor 1. This has the advantage of increasing the torque density.

Claims

Claims 1 . Rotor for an electrical machine, preferably an electric motor, with a rotor shell (2) and an end wall (6) at one end of the rotor shell (2), characterized in that the rotor shell (2) and the end wall (6) consist of magnetizable material and are at least partially magnetized.

2. Rotor according to claim 1, characterized in that a multi-pole Halbach array is present in the rotor casing (2) and in the end wall (6).

3. Rotor according to claim 1 or 2, characterized in that the rotor shell (2) has a predominantly radial magnetic polarization (Jradiai).

4. Rotor according to one of claims 1 to 3, characterized in that the end wall (6) has a predominantly axial magnetic polarization (Jaxiai).

5. Rotor according to one of claims 1 to 4, characterized in that a predominantly diagonal magnetic polarization (Jdiag) is present in the transition region between the rotor shell (2) and the end wall (6).

6. Rotor according to one of claims 1 to 5, characterized in that the rotor shell (2) and the end wall (6) have an even number of poles.

7. Rotor according to one of claims 1 to 6, characterized in that the rotor shell (2) and the end wall (6) have the same number of poles.

8. Rotor according to one of claims 1 to 7, characterized in that the rotor shell (2) and the end wall (6) are formed integrally with one another.

9. Rotor according to one of claims 1 to 8, characterized in that the rotor shell (2) has the greatest flux density on its inner side (15), which decreases towards the outer side (37).

10. Rotor according to one of claims 1 to 9, characterized in that the rotor shell (2) has at least one recess (38) on its outer side (37) in the region of low flux densities.

11. Rotor according to claim 10, characterized in that the recess (38) extends over the height of the rotor shell (2).

12. Rotor according to one of claims 1 to 11, characterized in that the rotor (1) consists of plastic-bonded magnetic material.

13. A method for producing a rotor (1) according to one of claims 1 to 12, characterized in that the rotor (1) is made of a magnetizable material and that the rotor shell (2) and the end wall (6) are magnetized by means of a combined radial and axial half-axis magnetizing device (12).

14. Method according to claim 13, characterized in that the rotor (1) is manufactured by means of an injection or die-casting process.

15. Method according to claim 14, characterized in that the rotor shell (2) and the end wall (6) are magnetized during the manufacturing process.

16. Method according to claim 13 or 14, characterized in that the rotor shell (2) and the end wall (6) are magnetized after the manufacturing process.

Images