Rotor comprising fixing medium, electric motor, motor vehicle, and method for producing a rotor

Abstract

The present invention relates to a rotor (1) for an electric motor (2) for driving a motor vehicle (3), the rotor comprising a rotor main body (4) which extends along a rotor longitudinal axis (L) and has a plurality of rotor teeth (5) distributed in the circumferential direction (U), wherein a rotor groove (6) is formed between each pair of adjacent rotor teeth (5). A rotor winding (7) made of a winding wire (8) is arranged in the rotor grooves (6) and peripherally surrounds the rotor teeth (5). A fixing medium (9) for fixing the winding wire (8) in the rotor grooves (6) is arranged in the rotor grooves (6). The fixing medium (9) has a substrate (10) and a binder (11), wherein the substrate (10) is connected to the winding wires (8) and the rotor teeth (5) by means of the binder (11). The invention also relates to an electric motor (2) for driving a motor vehicle (3), to a motor vehicle (3), and to a method for producing a rotor (1) for an electric motor (2) for driving a motor vehicle (3).

Description

[0001] 24-0269 PIF

[0002] 1

[0003] Description

[0004] Rotor with fixing medium, electric motor, motor vehicle and method for manufacturing a rotor

[0005] The present invention relates to a rotor for an electric motor for powering a motor vehicle. Furthermore, the invention relates to an electric motor for powering a motor vehicle, a rotor of the generic type, a motor vehicle with an electric drive system, and a method for manufacturing a rotor for an electric motor for powering a motor vehicle.

[0006] Rotors for electric motors are known that have a rotor body with several rotor teeth distributed circumferentially. A rotor slot is formed between adjacent rotor teeth. A rotor winding made of a winding wire is arranged in the rotor slots, completely surrounding the rotor teeth and thus forming a winding head at each of the two end faces of the rotor body.

[0007] As the rotor's rotational speed increases, so do the centrifugal forces acting on the rotor winding, which can sometimes lead to unwanted relative movements or displacements of the winding wires. This can, for example, damage wire insulation and thus cause short circuits.

[0008] To prevent such relative movements, it is common practice, for example, to fill the rotor slots with a potting compound after arranging the rotor windings in them. For this purpose, casting resins are used, with which the rotor slots are filled using a technically very complex process. This results in high costs. Furthermore, a rotor filled in this way has a relatively high weight due to the density of the casting resin. 24-0269 PIF

[0009] 2

[0010] It is therefore an object of the present invention to eliminate, or at least partially eliminate, the disadvantages described above in a rotor for an electric motor for driving a motor vehicle. In particular, it is an object of the present invention to provide a rotor for an electric motor for driving a motor vehicle, an electric motor for driving a motor vehicle, a motor vehicle with an electric drive system, and a method for manufacturing a rotor for an electric motor for driving a motor vehicle, all of which feature a simpler process and / or a reduced overall rotor weight in a simple and cost-effective manner.

[0011] The aforementioned problem is solved by the claims. Accordingly, the problem is solved by a rotor for an electric motor for driving a motor vehicle with the features of independent claim 1, by an electric motor for driving a motor vehicle with the features of dependent claim 8, by a motor vehicle with an electric drive system with the features of dependent claim 9, and by a method for manufacturing a rotor for an electric motor for driving a motor vehicle with the features of dependent claim 10. Further features and details of the invention will become apparent from the dependent claims, the description, and the drawings.Features and details described in connection with the rotor according to the invention naturally also apply in connection with the electric motor, the motor vehicle according to the invention and the method according to the invention, and vice versa, so that with regard to the disclosure of the individual aspects of the invention, mutual reference is always made or can be made.

[0012] According to a first aspect of the invention, the problem is solved by a rotor for an electric motor for powering a motor vehicle. The rotor has a rotor body extending along a rotor longitudinal axis with several rotor teeth distributed circumferentially, wherein a rotor groove is formed between adjacent rotor teeth. A 24-0269 PIF is located in the rotor grooves.

[0013] 3

[0014] A rotor winding made of a winding wire is arranged, which completely surrounds the rotor teeth. Furthermore, a fixing medium is arranged in the rotor slots for fixing the winding wire in the rotor slots. According to the invention, the fixing medium comprises a substrate and a binder, wherein the substrate is bonded to the winding wires and the rotor teeth via the binder.

[0015] The rotor body extends along the rotor's longitudinal axis. Preferably, the rotor body is formed from several rotor disks, in particular sheet metal disks, arranged coaxially to one another. The rotor disks are preferably made of electrical steel and more preferably have electrical insulation, such as a coating of baking varnish, to prevent current flow through the rotor body along the rotor's longitudinal axis. More preferably, the rotor body is arranged on a rotor shaft that extends coaxially to the rotor's longitudinal axis.

[0016] The rotor body incorporates several rotor teeth that extend radially outwards and are uniformly spaced from one another circumferentially. The rotor teeth are preferably congruent. Preferably, the rotor teeth have a tooth cap at their end pointing away from the rotor's longitudinal axis. This tooth cap has a greater circumferential extent than the tooth winding area formed between the tooth cap and the rotor's longitudinal axis, around which the rotor winding is arranged. Thus, the tooth cap secures the rotor winding against slipping radially away from the tooth winding area.

[0017] A rotor groove is formed between each pair of adjacent rotor teeth. This groove is open radially and at both ends of the rotor body. The rotor winding, made of winding wire, is arranged in the rotor grooves. The winding wire is preferably copper wire with an electrically insulating coating. Within the rotor grooves, the winding wire extends parallel or at least substantially parallel to the rotor's longitudinal axis. At each end of the rotor body, the winding wire forms a winding head of the rotor winding. Thus, the rotor winding completely surrounds the rotor teeth. 24-0269 PIF

[0018] 4

[0019] To better secure the winding wire to the rotor body, the fixing medium is arranged in the rotor slots. According to the invention, the fixing medium has at least two differently designed components, namely the substrate and the binder.

[0020] The substrate is wetted with or surrounded by the binder and connected to the winding wires and rotor teeth via the binder.

[0021] Preferably, the volume ratio of the substrate to the binder is at least 2:1, more preferably at least 3:1. Further preferably, the substrate has a lower density than the binder. Preferably, the density of the substrate is 80% or less than the density of the binder.

[0022] According to the invention, the fixing medium can also be arranged between the winding wires at the winding heads of the rotor. The substrate surface is preferably rough, ensuring a particularly advantageous and durable bond between the binder and the substrate.

[0023] A rotor according to the invention for an electric motor for powering a motor vehicle has the advantage over conventional rotors that a secure connection of the winding wires within the rotor slot is ensured using simple and cost-effective means, while reducing manufacturing effort. Furthermore, the weight of the rotor can be advantageously reduced by integrating the substrate into the fixing medium. Capillary action allows the binder to bond to the substrate in such a way that flow of the binder is prevented. In this way, the requirements for the tightness of the rotor body, and thus the manufacturing costs, can be reduced.

[0024] According to a preferred embodiment of the invention, the binder in a rotor can be a resin. A preferred resin is, for example, a trickle resin. Alternatively, a conventional adhesive that meets the mechanical stresses of the rotor can be used. In this context, the binder preferably has a temperature resistance sufficient for the operating temperature range of the rotor. 24-0269 PIF

[0025] 5 exceeds. Furthermore, the binder, in its cured state, preferably exhibits a strength that ensures a secure hold of the winding wire in the rotor slot even at maximum rotor speed and across the entire operating temperature range of the rotor or electric motor. This has the advantage that a rotor with a particularly low overall weight and particularly high mechanical strength can be provided using simple and cost-effective means.

[0026] According to the invention, it is preferred that the binder is cured. Preferably, the binder is completely cured. For the purposes of this invention, a cured binder is understood to be a binder that has solidified and is therefore no longer flowable. Displacements of the winding wires and the substrate within the rotor slot are thus prevented by the binder. This has the advantage that a rotor with particularly high mechanical strength can be provided using simple and cost-effective means.

[0027] Preferably, the substrate is in the form of granules. The granules have a specific grain size, preferably smaller than the diameter of the winding wire. Preferably, the cross-sectional area of ​​the winding wire is twice or larger than the cross-sectional area of ​​the substrate. More preferably, the cross-sectional area of ​​the winding wire is at most ten times larger than the cross-sectional area of ​​the substrate. Particularly preferably, the substrate is spherical. Such a substrate is particularly easy to arrange in the spaces between the winding wires and can be bonded to the winding wires and the inner wall of the rotor slot via the bonding agent. This has the advantage that a rotor with particularly high mechanical strength can be provided using simple and cost-effective means.

[0028] In a particularly preferred embodiment of the invention, a rotor may be provided that the substrate has an externally closed inner cavity, and / or that the substrate has an externally open cavity. An externally closed cavity is a void, such as an air pore, 24-0269 PIF

[0029] 6. An air void is formed within a substrate particle and has no opening to the surrounding environment. Therefore, no binder can penetrate the closed cavity. Such air voids reduce the weight of the fixing medium. An outwardly open cavity is a hollow space, such as an air void, that is also formed within a substrate particle and has an opening to the surrounding environment. The binder can penetrate the substrate particle through this opening, thus achieving better adhesion to the substrate. Preferably, the substrate has several closed cavities and / or several open cavities. The substrate can, for example, be porous. This has the advantage that the overall weight of the rotor can be further reduced and / or the mechanical strength of the rotor can be further improved in a simple and cost-effective manner.

[0030] Preferably, the substrate comprises or is made of a plastic. The plastic is preferably a thermoplastic. Preferred substrate materials include, for example, PA, PE, PP, PEEK, TPU, ABS, acrylic, or similar materials. The plastic is preferably temperature-resistant across the operating temperature range of the rotor or electric motor. This has the advantage of further improving the mechanical strength of the rotor in a simple and cost-effective manner.

[0031] According to a preferred embodiment of the invention, the substrate exhibits dimensional stability at room temperature and standard pressure. It is therefore preferred that the substrate exhibits at least some dimensional stability under deformation forces acting on it due to its own weight and under the influence of gravity. Preferably, the substrate is dimensionally stable when no or only slight compressive forces, for example 10 N / mm², are applied. 2 , acting on the substrate. This has the advantage that a high mechanical load-bearing capacity of the rotor is ensured using simple means and in a cost-effective manner.

[0032] According to a second aspect of the invention, the problem is solved by an electric motor for powering a motor vehicle. The electric motor features 24-0269 PIF

[0033] Figure 7 shows a stator with a longitudinal axis. According to the invention, the electric motor has a rotor according to the invention, which is rotatably mounted coaxially with respect to the stator's longitudinal axis. Preferably, the electric motor has a motor housing that completely surrounds the stator and the rotor. The rotor is preferably rotatably mounted on the motor housing via a rotor shaft.

[0034] The electric motor according to the invention offers all the advantages already described for a rotor according to the first aspect of the invention. Accordingly, the electric motor according to the invention has the advantage over conventional electric motors that a secure connection of the winding wires within the rotor slot is ensured using simple and cost-effective means, while reducing manufacturing effort. Furthermore, the weight of the rotor can be advantageously reduced by integrating the substrate into the fixing medium. Capillary action allows the binder to bond to the substrate in such a way that flow of the binder is prevented. In this way, the requirements for the tightness of the rotor body, and thus the manufacturing costs of the electric motor, can be reduced.

[0035] According to a third aspect of the invention, the problem is solved by a motor vehicle. The motor vehicle has an electric drive system.

[0036] According to the invention, the electric drive system for propelling the motor vehicle comprises an electric motor according to the invention. More preferably, the electric drive system for supplying the electric motor with electrical energy comprises a traction battery. The traction battery preferably has a voltage between 400 V and 800 V.

[0037] The motor vehicle according to the invention offers all the advantages already described for a rotor according to the first aspect of the invention and for an electric motor according to the second aspect of the invention. Accordingly, the motor vehicle according to the invention has the advantage over conventional motor vehicles that a secure connection of the winding wires within the rotor slot is ensured with simple means and in a cost-effective manner, while reducing manufacturing effort. (24-0269 PIF)

[0038] 8. Furthermore, the integration of the substrate into the fixing medium advantageously reduces the weight of the rotor. Capillary action allows the binder to adhere to the substrate in such a way that flow of the binder is prevented. In this way, the requirements for the tightness of the rotor body and thus the manufacturing costs of the vehicle can be reduced.

[0039] According to a fourth aspect of the invention, the problem is solved by a method for manufacturing a rotor for an electric motor for powering a motor vehicle. The method comprises:

[0040] Providing a rotor body with multiple rotor teeth and rotor grooves formed between adjacent rotor teeth,

[0041] Arranging a rotor winding made of winding wire in the rotor slots, introducing a flowable fixing medium into the rotor slots, wherein the fixing medium comprises a solid substrate and a binder, and curing the binder.

[0042] First, the rotor body is prepared. For this purpose, several rotor lamination discs are preferably arranged coaxially to each other and on a rotor shaft and pressed together. The axial fixation of the rotor body to the rotor shaft can be achieved, for example, using a thermal joining process that utilizes thermal expansion.

[0043] The winding wire is then arranged on the rotor body. It is positioned in the rotor slots and wound multiple times around the rotor teeth. This process forms winding heads of the rotor winding at the end faces of the rotor body.

[0044] The fixing medium is introduced into the rotor slots, preferably after the rotor winding has been arranged. The fixing medium comprises the solid substrate and the binder. The binder can be flowable, viscous, gel-like, plastic, or the like, and is preferably designed to form a bond upon contact with the substrate, the winding wire, and the inner wall of the rotor slot. The fixing medium is preferably introduced under pressure so that it also reaches the spaces between the 24-0269 PIF

[0045] 9

[0046] Rotor windings that are formed in a radial direction closer to the rotor longitudinal axis, for example over 50% of the height of the rotor winding, over 75% of the height of the rotor winding or up to 100% of the height of the rotor winding.

[0047] Finally, the binder is cured. This can be achieved, for example, by aging, drying, heating, chemical additives, or similar methods. In its cured state, the rotor winding is securely held to the rotor body by the fixing medium.

[0048] The inventive method for manufacturing a rotor for an electric motor for powering a motor vehicle offers all the advantages already described for a rotor according to the first aspect of the invention, an electric motor according to the second aspect of the invention, and a motor vehicle according to the third aspect of the invention. Accordingly, the inventive method has the advantage over conventional methods that a secure connection of the winding wires within the rotor slot is ensured with simple means and in a cost-effective manner, while reducing manufacturing effort. Furthermore, the weight of the rotor can be advantageously reduced by integrating the substrate into the fixing medium. Capillary action allows the binder to bond to the substrate in such a way that flow of the binder is prevented.In this way, requirements for the tightness of the rotor body and thus the manufacturing costs of the rotor can be reduced.

[0049] A rotor, an electric motor, a motor vehicle, and a method according to the invention are explained in more detail below with reference to the drawings. The drawings schematically show:

[0050] Figure 1 shows a sectional view of a rotor according to a preferred embodiment of the invention at a first time point during the execution of a method according to the invention, 24-0269 PIF

[0051] 10

[0052] Figure 2 shows a section of the rotor from Figure 1 in a sectional view at a second point in time during the execution of a method according to the invention.

[0053] Figure 3 shows a side view of an electric motor according to a preferred embodiment of the invention.

[0054] Figure 4 shows a side view of a preferred embodiment of a motor vehicle according to the invention, and

[0055] Figure 5 shows a flowchart illustrating a preferred embodiment of a method according to the invention.

[0056] Elements with the same function and mode of operation are each provided with the same reference symbols in Figures 1 to 5.

[0057] Figure 1 shows a schematic cross-sectional view of a rotor 1 according to a preferred embodiment of the invention at a first point in time during the execution of a method according to the invention. The rotor 1 has a rotor base body 4, which is composed of several components arranged coaxially to a rotor longitudinal axis L (see Figure 3) and is rotationally fixed to a central rotor shaft 14.

[0058] In this example, the rotor body 4 has four rotor teeth 5 extending radially away from the rotor shaft 14 in direction R. According to the invention, more or fewer rotor teeth 5, such as three or six, can also be provided. The rotor teeth 5 have a tooth winding area 15 arranged adjacent to the rotor shaft 14 and a tooth cap 16 at a tooth end pointing away from the rotor shaft 14, by which the tooth winding area 15 is bounded outwards in the radial direction R.

[0059] A rotor groove 6 is formed between each pair of rotor teeth 5 adjacent in the circumferential direction U. A rotor winding 7 made of winding wire 8 is arranged in the rotor grooves 6 such that the tooth winding areas 15 of the 24-0269 PIF

[0060] 11

[0061] The rotor teeth 5 are wound. The tooth caps 16 have a greater extent in the circumferential direction U than the tooth winding area 15, so that the rotor winding 7 is secured against slipping off the rotor base body 4. At the first stage shown during the execution of the method according to the invention, no fixing medium 9 is yet arranged in the rotor grooves 6.

[0062] Fig. 2 schematically shows a section of the rotor 1 from Fig. 1 at a second point in time during the execution of a method according to the invention. At the second point in time shown during the execution of the method according to the invention, the fixing medium 9 is arranged in the rotor slots 6. The fixing medium 9 has a substrate 10 formed as spherical granules, on the surface of which a binder 11 is arranged. The substrate 10 fills the spaces formed within the rotor slots 6 next to the winding wires 8 of the rotor winding 7. The substrate 10 is firmly bonded to the winding wires 8 and the inner walls of the rotor slots 6 via the binder 11.

[0063] Figure 3 shows a schematic side view of an electric motor 2 according to a preferred embodiment of the invention. The electric motor 2 has a stator 12 extending axially A along a longitudinal stator axis S. A rotor 1 according to the invention is rotatably mounted within the stator 12. The rotor 1 extends axially A along the rotor longitudinal axis L, which is arranged coaxially with the stator longitudinal axis S. A portion of the rotor 1 projects axially A out of the stator 12. A motor housing is not shown.

[0064] Fig. 4 schematically shows a preferred embodiment of a motor vehicle 3 according to the invention in a side view. The motor vehicle 3 has an electric drive system 13 with an electric motor 2 according to the invention for driving the motor vehicle 3 and a traction battery 17 for providing electrical energy to operate the electric motor 2.

[0065] Fig. 5 shows a preferred embodiment of a method according to the invention for manufacturing a rotor 1 for an electric motor 2 for driving a 24-0269 PIF.

[0066] 12

[0067] The process of manufacturing a motor vehicle 3 is schematically illustrated in a flowchart. In a first process step 100, a rotor base body 4 is provided. The rotor base body 4 is designed as a rotor lamination stack consisting of several coaxially assembled lamination disks and is preferably arranged in a rotationally fixed manner on a rotor shaft 14. In a second process step 200, a rotor winding 7 made of winding wire 8 is arranged around rotor teeth 5 such that a predominant part of the winding wire 8 is arranged in rotor slots 6 of the rotor base body 4.

[0068] In a third process step 300, a flowable fixing medium 9 is introduced into the rotor slots 6 such that the spaces left open by the rotor winding 7 in the rotor slots 6 are filled by the fixing medium 9. The fixing medium 9 comprises a solid substrate 10 and a binder 11. Depending on the volume ratio between the substrate 10 and the binder 11, the substrate 10 can, for example, be wetted by the binder 11 or be arranged to float freely within the binder 11. In a fourth process step 400, the binder 11 is cured so that the rotor winding 7 is fixed in the rotor slots 6 via the fixing medium 9.

[0069] 24-0269 PIF

[0070] 13

[0071] Reference symbol list

[0072] 1 Rotor

[0073] 2 electric motors

[0074] 3 Motor vehicle

[0075] 4 Rotor base bodies

[0076] 5 rotor tooth

[0077] 6 rotor slots

[0078] 7 Rotor winding

[0079] 8 Winding wire 9 Fixing medium

[0080] 10 substrate

[0081] 11 Binders

[0082] 12 Stator

[0083] 13 electric drive system

[0084] 14 Rotor shaft

[0085] 15 Tooth wrapping area

[0086] 16 Tooth cap

[0087] 17 Traction battery

[0088] A axial direction

[0089] L Rotor longitudinal axis

[0090] R radial direction

[0091] S Stator longitudinal axis

[0092] U circumferential direction

[0093] 100 first procedural action

[0094] 200 second procedural action 300 third procedural action

[0095] 400 fourth procedural action

Claims

24-0269 PIF 14 Patent claims 1. Rotor (1) for an electric motor (2) for driving a motor vehicle (3), comprising a rotor body (4) extending along a rotor longitudinal axis (L) with several rotor teeth (5) distributed in the circumferential direction (U), wherein a rotor groove (6) is formed between adjacent rotor teeth (5), wherein a rotor winding (7) made of a winding wire (8) is arranged in the rotor grooves (6), which surrounds the rotor teeth (5) circumferentially, wherein a fixing medium (9) for fixing the winding wire (8) in the rotor grooves (6) is arranged in the rotor grooves (6), characterized in that the fixing medium (9) comprises a substrate (10) and a binder (11), wherein the substrate (10) is connected to the winding wires (8) and the rotor teeth (5) via the binder (11).

2. Rotor (1 ) according to claim 1 , characterized in that the binder (11 ) comprises a resin.

3. Rotor (1 ) according to at least one of the preceding claims, characterized in that the binder (11 ) is cured.

4. Rotor (1 ) according to at least one of the preceding claims, characterized in that the substrate (10) is formed as granules.

5. Rotor (1 ) according to at least one of the preceding claims, characterized in that the substrate (10) has an externally closed inner cavity and / or that the substrate (10) has an externally open cavity. 24-0269 PIF 15 6. Rotor (1 ) according to at least one of the preceding claims, characterized in that the substrate (10) comprises a plastic or is formed from a plastic.

7. Rotor (1 ) according to at least one of the preceding claims, characterized in that the substrate (10) has dimensional stability at room temperature and standard pressure.

8. Electric motor (2) for driving a motor vehicle (3), comprising a stator (12) with a stator longitudinal axis (S), characterized in that the electric motor (2) has a rotor (1) according to one of the preceding claims, which is rotatably mounted coaxially to the stator longitudinal axis (S) relative to the stator (12).

9. Motor vehicle (3) comprising an electric drive system (13), characterized in that the electric drive system (13) comprises an electric motor (2) according to claim 8.

10. Method for manufacturing a rotor (1) for an electric motor (2) for driving a motor vehicle (3), comprising: Providing a rotor body (4) with several rotor teeth (5) and rotor slots (6) formed between adjacent rotor teeth (5), arranging a rotor winding (7) made of winding wire (8) in the rotor slots (6), Introducing a flowable fixing medium (9) into the rotor grooves (6), wherein the fixing medium (9) comprises a solid substrate (10) and a binder (11), and Curing of the binder (11 ).

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