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

Description

[0001] The invention relates to a method for attaching a plurality of magnets to a laminated core of a rotor for an electric motor, wherein each of the plurality of magnets is wrapped with an adhesive tape to form a plurality of bondable magnets. The adhesive tape comprises a carrier tape and at least one adhesive. The invention further relates to a rotor and an electric motor comprising the rotor.

[0002] Methods for attaching magnets to laminated cores to form a rotor are already known in the art. In addition to the possibility of pressing or caulking magnets into the corresponding cavities, it is also known to bond the magnets to the rotor or in the rotor cavities with liquid adhesive.

[0003] For example, the document DE 10 2011 117 946 A1 describes a method for applying a magnetic pole to a rotor with the following steps: Adhering a temporary adhesive, e.g. in the form of a double-sided adhesive tape, to a flat surface of an application tool, equipping the application tool with the temporary adhesive and at least one magnet, and applying the at least one magnet by means of a pressure unit to the rotor provided with an application adhesive.

[0004] The document DE 10 2006 049 866 A1 discloses an electric machine comprising a stator with a winding system arranged in slots, and a rotor on whose surface permanent magnets are arranged. The permanent magnets are fixed and positioned on the surface of the rotor by at least two different fastening means. The at least two fastening means are a double-sided adhesive tape and a liquid adhesive.

[0005] US 3,727,302 A and JP 9 163 649 A2 describe the attachment of magnets using double-sided adhesive tape. The problem here is that handling and inserting a magnet bonded with a double-sided adhesive tape into the openings of a rotor is difficult due to the adhesive tape's sticky surface facing the rotor.

[0006] DE 103 49 442 A1 discloses a rotor with permanent magnetic excitation by several permanent magnets that are coated with an electrically insulating and corrosion-protective layer and are inserted and fixed in recesses of a laminated core.

[0007] WO2013013128A2 discloses a rotor in which a magnet is attached with an adhesive tape.

[0008] The invention is based on the object of providing a simple and cost-effective method by which a plurality of magnets can be attached to a laminated core to form a rotor for an electric motor. This object is achieved by a method for attaching a plurality of magnets to a laminated core to form a rotor for an electric motor having the features of claim 1, by a rotor having the plurality of magnets having the features of claim 7, and by an electric motor having the rotor having the features of claim 8.

[0009] Preferred or advantageous embodiments of the invention emerge from the dependent claims, the following description and / or the attached figures. A method is proposed for attaching a plurality of magnets, in particular a plurality of permanent magnets, to a laminated core of a rotor for an electric motor. The electric motor is designed to drive a vehicle, in particular for an electric vehicle for transporting people, and can be integrated into the vehicle for this purpose. The rotor is in particular a rotating, magnetically acting element of the electric motor. The electric motor usually also comprises a stator, a stationary element wound with copper wire coils. Preferably, the rotor, like the stator, is formed from numerous electrical sheet metal parts that are punched and stacked to form sheet metal packages. In particular, each of the sheet metal parts is provided with an insulating layer relative to the other sheet metal part.Optionally, the electric motor draws electrical energy from the vehicle's traction battery. When current flows through the stator's copper wire coils, it creates magnetic fields that the rotor follows with its permanent magnets, causing the rotor to rotate. Preferably, the rotor's rotation is transmitted via a transmission to a drive axle to drive the vehicle's wheels.

[0010] According to the invention, the plurality of magnets are wrapped with an adhesive tape. Preferably, the plurality of magnets are completely wrapped with the adhesive tape. This forms a plurality of bondable magnets. In particular, the plurality of bondable magnets can be secured in a corresponding cavity of the rotor by means of an adhesive bond.

[0011] The adhesive tape comprises a carrier tape and at least one adhesive, wherein according to the invention the carrier tape is formed by an open-porous nonwoven material which is coated with the at least one adhesive on only one side at room temperature, wherein the at least one adhesive penetrates the open-porous nonwoven material and bonds to the laminated core of the rotor when the temperature increases by at least 20°C compared to room temperature.

[0012] The side of the adhesive tape, which is sticky at room temperature, is inserted facing the respective magnet. This is particularly advantageous because the nonwoven material on the side facing the rotor is non-sticky, thus allowing precise positioning of the bondable magnet in the rotor cavity. Inserting the bondable magnet into a rotor cavity and positioning it within the cavity is thus significantly simplified. Fixing the magnet in the cavity is achieved by simply heating the assembly consisting of a laminated core and several bondable magnets. This reduces the viscosity of the at least one adhesive, which in this state is able to penetrate the nonwoven material and move toward the laminated core, where it bonds to it. As the assembly cools, the at least one adhesive hardens, forming a permanent and strong bond between the magnet and the laminated core, or the magnet and the rotor.

[0013] According to the current state of the art, in addition to a double-sided adhesive tape with two sticky and therefore difficult-to-handle sides, an additional adhesive, such as liquid adhesive, is used to attach magnets to a rotor. This is time-consuming and costly due to complex dispensing technology, process monitoring, and process development. In particular, it must be ensured that the additional adhesive penetrates all areas of the cavity and wets the side walls to securely insulate and fix the magnets.

[0014] By means of the method according to the invention and the rotor according to the invention, adhesive can advantageously be dispensed with on one side of the adhesive tape and the use of liquid adhesive can be avoided, which further leads to cost savings.

[0015] The nonwoven material is preferably a textile material which in particular has a thickness in the range of 50 to 150 µm.

[0016] According to the invention, the laminated core has at least one cavity for the plurality of bondable magnets. One method step according to the invention provides that the plurality of bondable magnets are inserted into the at least one cavity and / or joined therein. The method step further provides that a plurality of bondable magnets are lined up and / or stacked on top of one another. Furthermore, at least one layer of adhesive tape is arranged between each of the magnets and on the outer sides of the magnets. In particular, this forms a bondable magnet core comprising at least two, three, four, or more bondable magnets. Specifically, the bondable magnet core is inserted into the corresponding cavity of the rotor. The method according to the invention thus offers the advantage that not only one magnet can be joined per cavity, but several magnets simultaneously, particularly when designed as the magnet core.A particularly advantageous feature is that the magnet package can be formed simply and cost-effectively. Because the magnet package is inserted and / or joined into the cavity as a whole, complex templates or auxiliary devices for precisely positioning individual magnets are eliminated.

[0017] By completely wrapping each of the multiple bondable magnets or the magnet package with the adhesive tape, the risk of adhesive-free areas between the respective magnet or magnet package and the inside of the respective cavity can be prevented. This ensures secure fixation in the cavity. Unintentional detachment of the respective magnet or magnet package from the cavity and the resulting noise or damage to the rotor can be advantageously avoided. In addition, each of the multiple bondable magnets or magnet package can be reliably electrically insulated from the environment by being completely wrapped with the adhesive tape. This ensures the performance of the respective magnet or magnet package and prevents malfunctions of the rotor.

[0018] It is particularly preferred that each of the several bondable magnets or the magnet package is inserted into the cavity in a stress-free or largely stress-free manner. For this purpose, the cavity preferably has dimensions that largely correspond to, and in particular are identical to, the respective magnet or magnet package. It is particularly possible to join the bondable magnets or the magnet package in a transition fit or clearance fit in the cavity.

[0019] In a further preferred method step, the laminated core with the bondable magnets inserted into the respective cavity or with the magnet core inserted into the respective cavity is heated. Preferably, the laminated core and the respective bondable magnet or magnet core are heated inductively. In this process, the at least one adhesive liquefies and penetrates the nonwoven material to form the connection between the respective magnet / magnet core and the laminated core.

[0020] A preferred embodiment of the invention provides that the adhesive tape comprises at least one adhesive in the form of a reactive resin, such as a phenolic resin and / or an epoxy resin. In particular, the adhesive tape comprises at least two adhesives in combination. It is particularly preferred that a first side of the adhesive tape, which is in particular directed towards the magnet(s) and / or contacts them, is coated. The at least one adhesive liquefies at least partially during inductive heating, in particular it melts. As a result, the magnet or the magnet stack in the cavity is bonded to the laminated core, in particular in a cavity.

[0021] To create a defined contact pressure between the bondable magnets or magnet stacks and the laminated core, the rotor is preferably set in rotation during the bonding process. The choice of rotation speed directly affects the level of contact pressure, i.e., the higher the rotation speed, the higher the contact pressure. This significantly improves the formation of a homogeneous and uniform bond.

[0022] A further method step involves cooling the laminated core, which was previously heated together with the bondable magnets or magnet core arranged in the corresponding cavity, if present. As a result of and / or during the cooling of the laminated core, the adhesive bond created by the at least one adhesive between the respective magnet or magnet core and the laminated core is cured, so that the latter is securely attached to the laminated core, in particular in a cavity of the laminated core.

[0023] At this point, it should be noted that a "magnet" within the meaning of the present invention can be an already magnetized component made of a magnetic material with magnetic properties. Alternatively, a magnet can also be bonded in the form of a component made of a not yet magnetized magnetic material. Magnetization of the magnetic material, which develops magnetic properties, then only occurs after bonding to the laminated core. Accordingly, the at least one magnet or the at least one magnet core can only be magnetized and acquire magnetic properties after bonding to the laminated core.

[0024] After the laminated core and the joined magnets or magnet stack have cooled, the rotor is complete. This can be integrated into an electric motor to power the vehicle.

[0025] A further subject of the invention is a rotor with a plurality of magnets, wherein the magnets are fastened to the laminated core to form the rotor according to the method according to the invention.

[0026] An electric motor for a vehicle, e.g., for a passenger car, in particular for an electric vehicle, with the rotor according to the invention forms a further subject of the invention. Optionally, the electric motor comprises the stator, which, when an electric current is applied, generates magnetic fields that cause the rotor to rotate.

[0027] In a preferred embodiment of the invention, the electric motor for driving the vehicle can be integrated into the vehicle. In particular, the electric motor is designed to generate a traction torque, or at least a portion of the traction torque, for the vehicle's wheels. Specifically, the electric motor can be mechanically coupled to the wheels, for example, via a reduction gear and drive shafts or via a manual transmission. Alternatively, the electric motor can be integrated into the respective wheel and can thus be designed as a wheel hub motor.

[0028] Further features, advantages, and effects of the invention will become apparent from the following description of preferred embodiments of the invention. These show: Figure 1 shows a perspective side view of a rotor with numerous magnet packages and a plan view of a section of a front side of the rotor; Figure 2a shows a method step of a method for attaching at least one magnet to the rotor from Figure 1 , wherein a magnet is wrapped with an adhesive tape; Figure 2b shows a further method step of the method, wherein several magnets wrapped with the adhesive tape are stacked on top of one another to form a magnet package; Figure 2c shows an additional method step in which the magnet package is joined in a cavity of the rotor; Figure 2d shows a further method step in which the rotor and the joined magnet package are heated; Figure 2e shows an additional method step in which the rotor with the joined magnet package is cooled; Figure 2f shows the finished rotor, which can be integrated into an electric motor. Corresponding or identical parts are provided with the same reference numerals in the figures.

[0029] Figure 1 shows a perspective side view of a rotor 1 with several magnet packages 3a, 3b, 3c, 3d, 3e, 3f, 3g, 3h, 3i, 3j, 3k. Figure 1 further shows an enlarged section of a front side of the rotor 1, from which a first magnet package 3a is arranged in a corresponding cavity 4 ( Fig. 2 ) is integrated in the rotor 1.

[0030] The rotor 1 comprises a laminated core 6 formed from numerous electrical sheet metal parts. It is designed for integration into an electric motor. The electric motor is designed for integration into an electric vehicle, in particular an electrically powered passenger car. There, it is intended to generate traction torque to drive the vehicle's wheels.

[0031] Numerous cavities 4 are incorporated into the laminated core 6 of the rotor 1. These cavities are, for example, punched into the laminated core 6. In each cavity 4, a magnet core 3a, 3b, 3c, 3d, 3e, 3f, 3g, 3h, 3i, 3j, 3k is inserted and / or joined and bonded in a stress-free or largely stress-free manner.

[0032] Each magnet package 3a, 3b, 3c, 3d, 3e, 3f, 3g, 3h, 3i, 3j, 3k comprises several, 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 completely surrounded by an adhesive tape 5, thus forming bondable magnets 20a, 20b, 20c, 20d, 20e, 20f, 20g. Each magnet package 3a, 3b, 3c, 3d, 3e, 3f, 3g, 3h, 3i, 3j, 3k is formed by arranging and / or stacking the bondable magnets 20a, 20b, 20c, 20d, 20e, 20f, 20g in a row. Thus, the adhesive tape 5 completely surrounds the outer sides of the respective magnet package 3a, 3b, 3c, 3d, 3e, 3f, 3g, 3h, 3i, 3j, 3k, making it bondable. At least one layer of the adhesive tape 5 is arranged uninterruptedly between the individual bondable magnets 20a, 20b, 20c, 20d, 20e, 20f, 20g.

[0033] The adhesive tape 5 comprises a carrier tape made of nonwoven material coated with at least one adhesive, preferably two different adhesives. Phenolic resin and epoxy resin are applied to one side of the carrier material. The side to which the at least one adhesive is applied is directed toward and contacts the respective magnet 2a, 2b, 2c, 2d, 2e, 2f, 2g. The uncoated side of the carrier tape forms the outer side of the respective bondable magnet 20a, 20b, 20c, 20d, 20e, 20f, 20g.

[0034] The Figures 2a - 2f show a representation of individual process steps of a method by which the magnets 2a, 2b, 2c, 2d, 2e, 2f, 2g are combined to form a first magnet package 3a. Furthermore, the attachment of the first magnet package 3a to the laminated core 6 is shown in corresponding process steps of the method.

[0035] In Figure 2aA first bondable magnet 20a is shown. The first bondable magnet 20a is formed from a first magnet 2a and the adhesive tape 5. The adhesive tape 5 is wound around the first magnet 2a to form the bondable magnet 20a, so that the adhesive tape 5 completely and seamlessly surrounds the magnet 2a.

[0036] Figure 2b shows the first magnet package 3a. The first adhesive magnet package 3a is formed by wrapping each of the magnets 2a, 2b, 2c, 2d, 2e, 2f, 2g with the adhesive tape 5, and then arranging or stacking the adhesive magnets 20a, 20b, 20c, 20d, 20e, 20f, 20g in a row. All other adhesive magnet packages 3b, 3c, 3d, 3e, 3f, 3g, 3h, 3i, 3j, 3k are formed in the same way.

[0037] Thus, several bondable magnets 20a, 20b, 20c, 20d, 20e, 20f, 20g, in particular an unlimited number of magnets, can be advantageously combined in a simple and time-saving manner to form the magnet packages 3a, 3b, 3c, 3d, 3e, 3f, 3g, 3h, 3i, 3j, 3k, which can then be joined as units into the corresponding cavities 4 of the laminated core 6 of the rotor 1 and bonded therein. Furthermore, the use of auxiliary tools and templates for joining the individual bondable magnets 20a, 20b, 20c, 20d, 20e, 20f, 20g in the cavities 4 can be dispensed with.Furthermore, it is advantageous that, in contrast to the use of liquid adhesive, as known from the prior art, no sophisticated dosing technology, process monitoring, or process development is required, since the complete wrapping of the individual magnets 20a, 20b, 20c, 20d, 20e, 20f, 20g with the adhesive tape 5 ensures full-surface bonding to the inside of the cavity 4, thus preventing the risk of unbonded areas. In particular, this can save production time and costs. A further advantage of using the adhesive tape 5 is that it is lower in cost than the conventionally used liquid adhesive.

[0038] In Figure 2c1 shows a section through the laminated core 6 of the rotor 1 along a rotation axis 7, about which the future rotor 1 is rotatable. Two cavities 4 are shown, with another magnet core 3k already inserted into one of the two cavities 4. The first magnet core 3a is inserted into the still free cavity 4. Like all the other magnet cores 3b, 3c, 3d, 3e, 3f, 3g, 3h, 3i, 3j, 3k, it is inserted into the cavity 4 in such a way that a transition fit is formed. Fluctuations in the gap between the laminated core 6 and the magnet cores 3b, 3c, 3d, 3e, 3f, 3g, 3h, 3i, 3j, 3k can be compensated for by applying a flexible adhesive tape 5 in a targeted manner. Thus, stresses between the laminated core 6 of the rotor 1 and the respective magnet core 3a, 3b, 3c, 3d, 3e, 3f, 3g, 3h, 3i, 3j, 3k can be largely avoided.In particular, a risk of damage, changes in technical properties and associated power losses of the magnets 2a, 2b, 2c, 2d, 2e, 2f, 2g caused by compressive stresses when pressing the magnets 2a, 2b, 2c, 2d, 2e, 2f, 2g into the cavities 4 can be advantageously avoided.

[0039] According to Figure 2d are the first magnet package 3a, the further magnet package 3k and all other magnet packages 3b, 3c, 3d, 3e, 3f, 3g, 3h, 3i, 3j ( Fig. 1) are joined in the corresponding cavities 4 of the laminated core 6. The laminated core 6 is then heated with the joined magnet cores 3a, 3b, 3c, 3d, 3e, 3f, 3g, 3h, 3i, 3j, 3k by applying inductive heat 8. The heat 8 causes the at least one adhesive on the adhesive tape 5 to at least partially liquefy and / or melt. As a result, the bondable magnets 20a, 20b, 20c, 20d, 20e, 20f, 20g of the respective magnet core 3a, 3b, 3c, 3d, 3e, 3f, 3g, 3h, 3i, 3j, 3k are bonded to one another. These, in turn, are glued to the side walls of the laminated core 6 in the corresponding cavity 4, thus forming a secure adhesive bond. In particular, the simple and easy-to-apply adhesive tape 5 ensures that the magnets 2a, 2b, 2c, 2d, 2e, 2f, 2g are completely surrounded by adhesive after inductive heating.This can prevent an unintentional release of the now bonded magnet 21a, 21b, 21c, 21d, 21e, 21f, 21g or magnet package 30a, 30b, 30c, 30d, 30e, 30f, 30g, 30h, 30i, 30j, 30k in the corresponding cavity 4, which could result in noise and / or damage to the finished rotor 1.

[0040] The at least one adhesive of the adhesive tape 5, in particular the two different adhesives, electrically insulates the corresponding bonded magnet packages 30a, 30b, 30c, 30d, 30e, 30f, 30g, 30h, 30i, 30j, 30k from the laminated core 6, so that the functionality and performance of the subsequent rotor 1 in the electric motor can be fully guaranteed. Furthermore, the electrical insulating effect of the at least one adhesive advantageously protects the bonded magnet packages 30a, 30b, 30c, 30d, 30e, 30f, 30g, 30h, 30i, 30j, 30k from ambient media, such as salt water and / or transmission oil.

[0041] Figure 2eshows a further process step in which the laminated core 6 is cooled by a cooling device 9. The cooling cures the adhesive bond between the individual bonded magnets 21a, 21b, 21c, 21d, 21e, 21f, 21g, the bonded magnet cores 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.

[0042] If the magnets 2a-g or magnet packages 3a-k are formed from a magnetic material that does not yet have magnetic properties, the cooling process is preferably followed by a magnetization of the magnets 2a-g or magnet packages 3a-k, which gives them the required magnetic properties.

[0043] Figure 2fshows the rotor 1, completed from the laminated core 6 and the magnet cores 30a, 30b, 30c, 30d, 30e, 30f, 30g, 30h, 30i, 30j, 30k, as it can be integrated into an electric motor. The rotor 1 forms a rotating, magnetically active element in the electric motor, which is in a magnetically active connection with a stator of the electric motor. The stator is formed from an electrical sheet core wound with copper wire coils. When the stator is supplied with electrical energy, e.g., from a vehicle's traction battery, the rotor rotates due to the current flow through the copper wire coils and the resulting magnetic fields. The torque of the rotor is converted via a vehicle's transmission and transmitted to a drive axle of the vehicle, so that the vehicle's wheels are driven. List of reference symbols

[0044] 1Rotor 2a-gMagnet 3a-kMagnetpaket 4Kavität 5Klebeband 6Blechpaket 7Rotationsachse 8induktive Wärmezufuhr 9Kühleinheit 20a-gverklebbarer Magnet 21a-gverklebter Magnet 30a-kverklebtes Magnetpaket

Claims

1. A method of fastening multiple magnets (2a, 2b, 2c, 2d, 2e, 2f, 2g) to a laminated core (6) of a rotor (1) for an electric motor, wherein each of the multiple magnets (2a, 2b, 2c, 2d, 2e, 2f, 2g) is wrapped with an adhesive tape (5), so that multiple bondable magnets (20a, 20b, 20c, 20d, 20e, 20f, 20g) are formed, wherein the adhesive tape (5) comprises a carrier tape and at least one adhesive, wherein the carrier tape is formed by an open-porous non-woven material, which is coated on only one side with the at least one adhesive at room temperature, wherein this adhesive side of the adhesive tape faces the magnet, and wherein the at least one adhesive penetrates the open-porous non-woven material at a temperature increase of at least 20°C compared to room temperature and bonds with the laminated core (6) of the rotor (1), wherein the laminated core (6) has at least one cavity (4) for the multiple bondable magnets (20a, 20b, 20c, 20d, 20e, 20f, 20g), characterised in that multiple bondable magnets (20a, 20b, 20c, 20d, 20e, 20f, 20g) are arranged in a row and / or stacked on top of one another, wherein at least one layer of the adhesive tape (5) is arranged between each of the magnets (2a, 2b, 2c, 2d, 2e, 2f, 2g) and on the outer sides of the magnets (2a, 2b, 2c, 2d, 2e, 2f, 2g), so that at least one bondable magnet pack (3a, 3b, 3c, 3d, 3e, 3f, 3g, 3h, 3i, 3j, 3k) is formed, wherein the at least one bondable magnet pack (3a, 3b, 3c, 3d, 3e, 3f, 3g, 3h, 3i, 3j, 3k) is inserted into and / or joined to the at least one cavity (4) and that the at least one magnet pack (3a, 3b, 3c, 3d, 3e, 3f, 3g, 3h, 3i, 3j, 3k) is magnetised and acquires magnetic properties only after it has been bonded laminated core (6).

2. The method according to claim 1, characterised in that the at least one bondable magnet pack (3a, 3b, 3c, 3d, 3e, 3f, 3g, 3h, 3i, 3j, 3k) is inserted into and / or joined to the at least one cavity (4) tension-free or largely tension-free.

3. The method according to one of the preceding claims, characterised in that the laminated core (6) is inductively heated with the bondable magnet pack (3a, 3b, 3c, 3d, 3e, 3f, 3g, 3h, 3i, 3j, 3k) inserted into the at least one cavity (4).

4. The method according to claim 3, characterised in that the at least one adhesive at least partially liquefies and / or melts during the inductive heating, so that the at least one bondable magnet pack (3a, 3b, 3c, 3d, 3e, 3f, 3g, 3h, 3i, 3j, 3k) is bonded to the laminated core (6) in the at least one cavity (4).

5. The method according to claim 4, characterised in that the laminated core (6) with the at least one bonded magnetic pack (30a, 30b, 30c, 30d, 30e, 30f, 30g, 30h, 30i, 30j, 30k) is cooled, so that a bond produced by the at least one adhesive between the at least one bonded magnetic pack (30a, 30b, 30c, 30d, 30e, 30f, 30g, 30h, 30i, 30j, 30k) and the laminated core (6) is cured.

6. The method according to one of claims 1 to 5, characterised in that the at least one adhesive comprises a reactive resin, in particular an epoxy resin.

7. A rotor (1) with the at least one bonded magnet pack (30a, 30b, 30c, 30d, 30e, 30f, 30g, 30h, 30i, 30j, 30k) and with the laminated core (6), wherein the at least one magnet pack (30a, 30b, 30c, 30d, 30e, 30f, 30g, 30h, 30i, 30j, 30k) has been fastened to the laminated core (6) and magnetised in accordance with the method according to one of claims 1 to 6.

8. An electric motor for a vehicle having the rotor (1) according to claim 7.