METHOD FOR FASTENING AT LEAST ONE MAGNET TO A LAMINATED CORE OF A ROTOR FOR AN ELECTRIC MOTOR, A ROTOR, AND AN ELECTRIC MOTOR HAVING THE ROTOR

Abstract

A method for fastening a magnet to a laminated core of a rotor for an electric motor includes providing the magnet and the laminated core, providing an adhesive tape, and winding the adhesive tape around the magnet to form a bondable magnet. The adhesive tape includes a backing tape formed by an open-pored nonwoven material, and an adhesive that coats only one side of the backing tape at room temperature and penetrates the open-pored nonwoven material and bonds to the laminated core of the rotor when a temperature of the adhesive is increased by at least 20° C. relative to room temperature. The laminated core may include a cavity for the bondable magnet, and the method may include the step of inserting or fitting the bondable magnet into the cavity. The bondable magnet may be inserted or fitted into the cavity without stress or mostly without stress.

Claims

1.-10. (canceled)

11. A method for fastening a magnet to a laminated core of a rotor for an electric motor, comprising: providing the magnet and the laminated core; providing an adhesive tape comprising: a backing tape formed by an open-pored nonwoven material; and an adhesive that coats only one side of the backing tape at room temperature and penetrates the open-pored nonwoven material and bonds to the laminated core of the rotor when a temperature of the adhesive is increased by at least 20° C. relative to room temperature; and winding the adhesive tape around the magnet to form a bondable magnet.

12. The method of claim 11 wherein the laminated core comprises a cavity for the bondable magnet, the method further comprising the step of inserting or fitting the bondable magnet into the cavity.

13. The method of claim 12, wherein the bondable magnet is inserted or fitted into the cavity without stress or mostly without stress.

14. The method of claim 12 further comprising the step of inductive heating the laminated core.

15. The method of claim 14, wherein, during the inductive heating, at least a portion of the adhesive liquifies or melts to form a bond between the bondable magnet and the laminated core.

16. The method of claim 15 further comprising the step of cooling the laminated core to cure the bond.

17. The method of claim 15 further comprising the step of magnetizing the bondable magnet after the bond is formed.

18. The method of claim 11 wherein the laminated core comprises a cavity for the bondable magnet, the method further comprising the steps of: forming a bondable magnet assembly by positioning a plurality of bondable magnets in a row or stacking a plurality of bondable magnets on top of one another; and inserting or fitting the bondable magnet assembly into the cavity.

19. The method of claim 18, wherein the bondable magnet assembly is inserted or fitted into the cavity without stress or mostly without stress.

20. The method of claim 18 further comprising the step of inductive heating the laminated core.

21. The method of claim 20, wherein, during the inductive heating, the at least a portion of the adhesive liquifies or melts to form a bond between the bondable magnet assembly and the laminated core.

22. The method of claim 21 further comprising the step of cooling the laminated core to cure the bond.

23. The method of claim 11, wherein the adhesive comprises a reaction resin.

24. The method of claim 23, wherein the reaction resin is an epoxy resin.

25. A rotor comprising the magnet fastened to the laminated core by the method of claim 11.

26. An electric motor for a vehicle comprising the rotor of claim 25.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Further features, advantages and effects of the disclosure will become apparent from the following description of illustrative embodiments of the disclosure. In the drawings:

[0027] FIG. 1 shows a perspective side view of a rotor with magnet assemblies and a plan view of a segment of one end of the rotor;

[0028] FIG. 2a shows a method step of a method for fastening a magnet to the rotor in FIG. 1, wherein an adhesive tape is being wound around a magnet;

[0029] FIG. 2b shows a further method step of the method, wherein magnets wound with the adhesive tape are stacked one on top of the other to form a magnet assembly;

[0030] FIG. 2c shows an additional method step, in which the magnet assembly is fitted in a cavity of the rotor;

[0031] FIG. 2d shows a further method step, in which the rotor and the fitted magnet assembly are heated;

[0032] FIG. 2e shows an additional method step, in which the rotor with the fitted magnet assembly is cooled; and

[0033] FIG. 2f shows the finished rotor, which can be integrated into an electric motor. In the figures, corresponding or identical parts are in each case provided with the same reference signs.

DETAILED DESCRIPTION

[0034] FIG. 1 shows a perspective side view of a rotor 1 having a plurality of magnet assemblies 3a, 3b, 3c, 3d, 3e, 3f, 3g, 3h, 3i, 3j, 3k. FIG. 1 furthermore shows an enlarged segment of an end of the rotor 1, starting from which a first magnet assembly 3a is integrated into a corresponding cavity 4 (FIG. 2c) in the rotor 1.

[0035] The rotor 1 includes a laminated core 6, which is formed from core plates. It is designed for integration into an electric motor. The electric motor is designed for integration into an electric vehicle, e.g., an electrically driven passenger car. There, it is provided for the purpose of producing traction torques for driving the wheels of the vehicle.

[0036] Cavities 4 are introduced into the laminated core 6 of the rotor 1. These are stamped into the core assembly 6, for example. A magnet assembly 3a, 3b, 3c, 3d, 3e, 3f, 3g, 3h, 3i, 3j, 3k is introduced and/or fitted without stress or mostly without stress into each cavity 4 and bonded.

[0037] Each magnet assembly 3a, 3b, 3c, 3d, 3e, 3f, 3g, 3h, 3i, 3j, 3k includes a plurality of magnets, e.g. seven magnets 2a, 2b, 2c, 2d, 2e, 2f, 2g. The magnets are permanent magnets. Each of the magnets 2a, 2b, 2c, 2d, 2e, 2f, 2g is surrounded completely by an adhesive tape 5, and, as a result, bondable magnets 20a, 20b, 20c, 20d, 20e, 20f, 20g are formed. Each magnet assembly 3a, 3b, 3c, 3d, 3e, 3f, 3g, 3h, 3i, 3j, 3k is formed by juxtaposing and/or stacking the bondable magnets 20a, 20b, 20c, 20d, 20e, 20f, 20g. Thus, the adhesive tape 5 completely surrounds the outsides of the respective magnet assembly 3a, 3b, 3c, 3d, 3e, 3f, 3g, 3h, 3i, 3j, 3k, thereby making said assembly bondable. At least one ply of the adhesive tape 5 is arranged without interruption between the individual bondable magnets 20a, 20b, 20c, 20d, 20e, 20f, 20g.

[0038] The adhesive tape 5 includes a backing tape composed of nonwoven material, which is coated with at least one adhesive, preferably with two different adhesives. Here, therefore, phenolic resin and epoxy resin are applied on one side of the backing material. The side on which the at least one adhesive is applied faces the respective magnet 2a, 2b, 2c, 2d, 2e, 2f, 2g and makes contact with the latter. The uncoated side of the backing tape forms the outside of the respective bondable magnet 20a, 20b, 20c, 20d, 20e, 20f, 20g.

[0039] FIGS. 2a-2f show an illustration of individual method steps of a method by which the magnets 2a, 2b, 2c, 2d, 2e, 2f, 2g are combined to form a first magnet assembly 3a. The fastening of the first magnet assembly 3a to the laminated core 6 in corresponding method steps of the method is furthermore illustrated.

[0040] A first bondable magnet 20a is shown in FIG. 2a. The first bondable magnet 20a is formed from a first magnet 2a and the adhesive tape 5. To form the bondable magnet 20a, said tape is wound around the first magnet 2a, and therefore the adhesive tape 5 surrounds the magnet 2a completely and without interruption.

[0041] FIG. 2b shows the first magnet assembly 3a. The first bondable magnet assembly 3a is formed by winding the adhesive tape 5 around each of the magnets 2a, 2b, 2c, 2d, 2e, 2f, 2g and then arranging the bondable magnets 20a, 20b, 20c, 20d, 20e, 20f, 20g in a row or stacking them one on top of the other. All the other bondable magnet assemblies 3b, 3c, 3d, 3e, 3f, 3g, 3h, 3i, 3j, 3k are formed in the same way.

[0042] It is thus possible, in a manner which is simple and saves manufacturing time, to combine a plurality of bondable magnets 20a, 20b, 20c, 20d, 20e, 20f, 20g, e.g., an unlimited number of magnets, to form the magnet assemblies 3a, 3b, 3c, 3d, 3e, 3f, 3g, 3h, 3i, 3j, 3k, which can then be fitted as units into the corresponding cavities 4 of the laminated core 6 of the rotor 1 and bonded therein. Moreover, it is possible to dispense with the use of auxiliary tools and templates for fitting the individual bondable magnets 20a, 20b, 20c, 20d, 20e, 20f, 20g into the cavities 4. In contrast to the use of liquid adhesive, as known from the prior art, there is no significant metering technology, process monitoring and process development required since the complete winding of the individual magnets 20a, 20b, 20c, 20d, 20e, 20f, 20g with the adhesive tape 5 ensures full-surface bonding to insides of the cavity 4 and, as a result, the risk of unbonded locations is prevented. In particular, it is thereby possible to save manufacturing time and costs. Another advantage of the use of the adhesive tape 5 is that it entails lower costs than conventionally used liquid adhesive.

[0043] FIG. 2c shows a section through the laminated core 6 of the rotor 1 along an axis of rotation 7 about which the subsequent rotor 1 can be rotated. Two cavities 4 are shown, wherein another magnet assembly 3k has already been fitted into one of the two cavities 4. The first magnet assembly 3a is inserted into the cavity 4 which is still free. Like all the other magnet assemblies 3b, 3c, 3d, 3e, 3f, 3g, 3h, 3i, 3j, 3k it is fitted into the cavity 4 in such a way that a transition fit is formed. Fluctuations in the size of the gap between the laminated core 6 and the magnet assemblies 3b, 3c, 3d, 3e, 3f, 3g, 3h, 3i, 3j, 3k can be compensated for by a flexible adhesive tape 5 and the selective application thereof. In this way, stresses between the laminated core 6 of the rotor 1 and the respective magnet assembly 3a, 3b, 3c, 3d, 3e, 3f, 3g, 3h, 3i, 3j, 3k can mostly be avoided. In particular, a risk of damage, change to technical properties and associated power losses of the magnets 2a, 2b, 2c, 2d, 2e, 2f, 2g caused by pressure stresses when the magnets 2a, 2b, 2c, 2d, 2e, 2f, 2g are pressed into the cavities 4 can be avoided.

[0044] According to FIG. 2d, the first magnet assembly 3a, the further magnet assembly 3k and all the other magnet assemblies 3b, 3c, 3d, 3e, 3f, 3g, 3h, 3i, 3j (FIG. 1) are fitted into the corresponding cavities 4 of the laminated core 6. The laminated core 6 is then heated with the fitted magnet assemblies 3a, 3b, 3c, 3d, 3e, 3f, 3g, 3h, 3i, 3j, 3k by supplying inductive heat 8. As a result of the heat 8, the adhesive on the adhesive tape 5 is at least partially liquefied and/or melts. As a result, the bondable magnets 20a, 20b, 20c, 20d, 20e, 20f, 20g of the respective magnet assembly 3a, 3b, 3c, 3d, 3e, 3f, 3g, 3h, 3i, 3j, 3k are bonded to one another. These, in turn, are bonded to the side walls of the laminated core 6 in the corresponding cavity 4, with the result that they are fastened by a secure adhesive bond. In particular, the simply and easily applied adhesive tape 5 ensures that the magnets 2a, 2b, 2c, 2d, 2e, 2f, 2g are completely surrounded with adhesive after the inductive heating. It is thereby possible to avoid a situation where there is unwanted detachment of the now bonded magnet 21a, 21b, 21c, 21d, 21e, 21f, 21g or magnet assembly 30a, 30b, 30c, 30d, 30e, 30f, 30g, 30h, 30i, 30j, 30k in the corresponding cavity 4, this being associated with troublesome noise and/or damage of the finished rotor 1.

[0045] The adhesive of the adhesive tape 5, e.g., the two different adhesives, insulates the corresponding bonded magnet assemblies 30a, 30b, 30c, 30d, 30e, 30f, 30g, 30h, 30i, 30j, 30k electrically from the laminated core 6, and it is therefore possible to ensure an unrestricted functioning and performance capacity of the subsequent rotor 1 in the electric motor. Moreover, the electric insulating effect of the ensures that the bonded magnet assemblies 30a, 30b, 30c, 30d, 30e, 30f, 30g, 30h, 30i, 30j, 30k are protected from media in the environment, e.g. saltwater and/or transmission oil.

[0046] FIG. 2e shows another method step, in which the laminated core 6 is cooled by a cooling device 9. By means of the cooling, the adhesive bond between the individual bonded magnets 21a, 21b, 21c, 21d, 21e, 21f, 21g, the bonded magnet assemblies 30a, 30b, 30c, 30d, 30e, 30f, 30g, 30h, 30i, 30j, 30k and the side walls of the laminated core 6 in the respective cavity 4 is cured.

[0047] If the magnets 2a-g or magnet assemblies 3a-k are formed from a magnet material which does not yet have any magnetic properties, the cooling process may be followed by magnetization of the magnets 2a-g or magnet assemblies 3a-k, which imparts to them the required magnetic properties.

[0048] FIG. 2f shows the rotor 1 produced from the laminated core 6 and the magnet assemblies 30a, 30b, 30c, 30d, 30e, 30f, 30g, 30h, 30i, 30j, 30k in the form in which it can be integrated into an electric motor. In the electric motor, the rotor 1 forms a rotating, magnetically acting element which is in magnetic operative connection with a stator of the electric motor. The stator is formed from a core plate assembly, around which copper wire coils are wound. When the stator is supplied with electric energy, e.g. from a traction battery of the vehicle, the rotor rotates due to the current flow through the copper wire coils and the magnetic fields generated thereby. The torque of the rotor is converted by a transmission of the vehicle and transmitted to a driven axle of the vehicle, with the result that the wheels of the vehicle are driven.

REFERENCE NUMERALS

[0049] 1 rotor

[0050] 2a-g magnet

[0051] 3a-k magnet assembly

[0052] 4 cavity

[0053] 5 adhesive tape

[0054] 6 laminated core

[0055] 7 axis of rotation

[0056] 8 inductive heat supply

[0057] 9 cooling unit

[0058] 20a-g bondable magnet

[0059] 21a-g bonded magnet

[0060] 30a-k bonded magnet assembly