Rotor for an axial flux machine, axial flux machine with one rotor, and motor vehicle with an axial flux machine

Abstract

The invention relates to a rotor (10) for an axial flux machine (100), comprising a hub (20), a toroidal core (30) which is at least indirectly rotationally fixed to the hub (20), and at least one magnetic element (40) which is fixed to the toroidal core (30) by means of an adhesive layer (50) extending in the radial direction (R) of the rotor (10) between the toroidal core (30) and the at least one magnetic element (40). The adhesive layer (50) has a greater thickness (S) with respect to an axial direction (A) of the rotor (10) at an inner edge region (42) of the magnetic element (40) located in the radial direction (R) than at a central region (44) of the magnetic element (40) located further out in the radial direction (R).The invention further relates to an axial flux machine (100) with a rotor (10) and a motor vehicle (K) with an axial flux machine (100).

Description

[0001] The invention relates to a rotor for an axial flux machine, comprising a hub, a toroidal core which is at least indirectly rotationally fixed to the hub, and at least one magnetic element which is fixed to the toroidal core by means of an adhesive layer extending in the radial direction of the rotor between the toroidal core and the at least one magnetic element. Further aspects of the invention relate to an axial flux machine with such a rotor and to a motor vehicle with an axial flux machine.

[0002] DE 20 2012 012 228 U1 discloses a rotor for a machine shaft of an electric axial flux machine. The rotor has a central bearing bore for the machine shaft. Several permanent magnets are arranged circularly around the bearing bore and the machine shaft, each extending through an opening in the rotor and each held in the rotor against axial and radial displacement.

[0003] The object of the present invention is to provide a simple-to-manufacture and reliable rotor of the type mentioned above, as well as an axial flux machine with such a rotor and a motor vehicle with a correspondingly reliable axial flux machine.

[0004] This problem is solved by a rotor with the features of claim 1, by an axial flux machine with the features of claim 5, and by a motor vehicle according to claim 6. Advantageous embodiments with expedient further developments of the invention are specified in the dependent claims.

[0005] A first aspect of the invention relates to a rotor for an axial flux machine, comprising a hub, a toroidal core which is at least indirectly rotationally fixed to the hub, and at least one magnetic element which is fixed to the toroidal core by means of an adhesive layer extending in the radial direction of the rotor between the toroidal core and the at least one magnetic element. The toroidal core can also be referred to as an electrical steel sheet.

[0006] According to the invention, the adhesive layer has a greater thickness in the radially inner edge region of the at least one magnetic element than in the radially outer central region of the at least one magnetic element. This is advantageous because, due to the greater layer thickness, smaller mechanical stress peaks occur within the adhesive layer in the radial direction at the level of the radial edge region of the at least one magnetic element, and the adhesive layer is therefore subjected to less stress when the rotor is rotating.

[0007] The invention is based on the understanding that at high rotor speeds, correspondingly large centrifugal forces act on the at least one magnetic element, which can cause strong loads, particularly in the form of shear stresses, in the adhesive layer in the region of the inner edge of the magnetic element. These loads can, in turn, lead to cracking in the adhesive layer and ultimately to the undesirable detachment of the at least one magnetic element from the ring core. The invention addresses this issue and leads to a surprisingly significant reduction of these loads. Thus, with the greater layer thickness in the region of the inner edge of the magnetic element (located radially in the direction of extension) compared to the central area, a uniform load distribution and the avoidance of harmful shear stress peaks can be achieved.

[0008] In an advantageous embodiment of the invention, the at least one magnetic element has at least one chamfer extending outwards in the radial direction from the inner edge region of the magnetic element, resulting in a greater layer thickness at the inner edge region than at the central region. This is advantageous because the chamfer at the inner edge region of the magnetic element creates a less sharp edge between the at least one magnetic element and the adhesive layer than would be the case with a chamferless magnetic element. Instead, it results in particularly low or even no stress peaks and a uniformly low load in the area of ​​the inner edge region of the magnetic element. A chamfer height of more than 0.5 mm, and preferably 0.6 mm, has proven to be particularly advantageous.With such a chamfer height, the adhesive layer is particularly durable even at high rotor speeds, and the rotor is correspondingly reliable.

[0009] In a further advantageous embodiment of the invention, the at least one chamfer has a chamfer angle in the range between 5° and 20° inclusive, preferably between 10° and 15° inclusive. A chamfer angle in such a range leads to particularly low shear stresses in the adhesive layer, making it especially durable. A chamfer angle of 15° has proven particularly suitable in this context.

[0010] In a further advantageous embodiment of the invention, the adhesive layer extends outwards in the radial direction and alongside the chamfer with a uniform thickness between the at least one magnetic element and the toroidal core. This is advantageous because the at least one magnetic element and the toroidal core can each have easily manufactured and parallel bonding surfaces on which the adhesive layer can extend with a uniform thickness. This simplifies the manufacture of the rotor.

[0011] A second aspect of the invention relates to an axial flux machine with a rotor according to the first aspect of the invention. Such a rotor has a particularly durable adhesive bond between the at least one magnetic element and the toroidal core.

[0012] A third aspect of the invention relates to a motor vehicle with an axial flux machine according to the second aspect of the invention. Such an axial flux machine is particularly reliable and fail-safe to operate.

[0013] The preferred embodiments and their advantages presented with respect to one of the aspects apply accordingly to the other aspects of the invention and vice versa.

[0014] The features and combinations of features mentioned above in the description, as well as the features and combinations of features mentioned below in the figure description and / or shown in the figures alone, can be used not only in the combination specified in each case, but also in other combinations or on their own, without leaving the scope of the invention.

[0015] Further advantages, features and details of the invention will become apparent from the claims, the following description of preferred embodiments and the drawings.

[0016] The invention is explained below again using a specific embodiment. This is illustrated by: Fig. 1. A schematic perspective view of a section of a rotor, which is part of a schematically represented axial flux machine, which is arranged in a similarly schematically represented motor vehicle and serves therein as a traction machine; and Fig. 2 a sectional view of the section of the rotor of the axial flux machine.

[0017] Fig. Figure 1 shows a schematic representation of a motor vehicle K with a schematically represented axial flux machine 100. The axial flux machine 100 has a rotor 10, which comprises a hub 20 and a toroidal core 30 connected to the hub 20 in a rotationally fixed manner, at least indirectly. The toroidal core 30 can also be referred to as electrical steel. The hub 20 can be directly connected to a support element 60 of the rotor 10. The toroidal core 30 can be, as shown in Fig. 1 is recognizable as being connected, for example joined, to the support element 60. The support element 60 can generally be designed as a steel beam and can, for example, be referred to as a rotor steel beam. However, the rotor 10 can also be - as in Fig. Figure 2 shows a sheet metal part 70, which can be arranged in the axial direction A between the hub 20 and the support element 60. The sheet metal part 70 can generally be designed as a shim, in particular as a stainless steel shim.

[0018] At least one magnetic element 40 of the rotor 10 is fixed to the toroidal core 30 by means of an adhesive layer 50 extending in the radial extension direction R of the rotor 10 between the toroidal core 30 and the at least one magnetic element 40.

[0019] The adhesive layer 50 has a greater layer thickness S with respect to an axial direction A of the rotor 10 at an inner edge region 42 of the at least one magnetic element 40 located in the radial direction R than at a central region 44 of the at least one magnetic element 40 located further outwards in the radial direction R.

[0020] This is achieved by the at least one magnetic element 40 having at least one chamfer 46, which extends outwards from the inner edge region 42 of the magnetic element in the radial direction R and by virtue of which the layer thickness S at the inner edge region 42 of the magnetic element is greater than at the central region 44. At the central region 44 as well as at other adhesive layer regions spaced apart from the chamfer 46, the adhesive layer 50 has a layer thickness S1 that is smaller than the layer thickness S.

[0021] In order to fix the at least one magnetic element 40 to the ring core 30 even more reliably, the rotor 10 has an adhesive bead 52 extending at least partially in the circumferential direction of the rotor 10 along the inner edge region 42 of the magnetic element and connecting the at least one magnetic element 40 to the ring core 30 in addition to the adhesive layer 50.

[0022] The adhesive layer 50 can extend outwards in the radial extension direction R and next to the chamfer 46 with a uniform thickness between the at least one magnetic element 40 and the toroidal core 30.

[0023] The chamfer 46 has a chamfer angle α, the magnitude of which lies in the range between 5° and 20° inclusive, preferably between 10° and 15° inclusive. In this case, the magnitude of the chamfer angle α corresponds to a value of 15°.

[0024] The invention summarizes and demonstrates in general terms how magnets (magnetic element 40) can be bonded horizontally, i.e., parallel to the ring core 30, to the rotor 10 by means of an adhesive (adhesive layer 50). During the operation of the axial flux machine 10, the rotor 10 experiences very high centrifugal forces due to its rapid rotation. If the adhesive layer 50 did not hold the magnet element 40 in place and transmit the centrifugal forces to the ring core 30, the magnet element 40 would be pulled outwards in the radial direction R, i.e., away from the hub 20, due to its own inertia. In order to avoid excessively high shear stresses in the adhesive layer 50 during the rotation of the rotor 10, the magnetic element 40 and the other magnetic elements of the rotor 10, which are not shown here, are not provided at right angles in the area of ​​the inner edge region 42 of the magnetic element as in known systems, but with the chamfer 46.This ensures that – unlike with conventional, right-angled magnets – no stresses concentrate at the sharp magnetic edge and are transferred to the adhesive layer 50. Instead, the chamfer 46 allows for a significant reduction in stress, particularly shear stress, thus preventing any cracking in the adhesive layer 50 and ensuring that the magnetic elements 40 do not detach.

[0025] The invention enables an overall reduction of singular stresses or a lowering of stress gradients as well as a shift of high stresses in the direction of the central area 44 by means of a specific geometric optimization of a bottom area of ​​the at least one magnetic element 40, by attaching the chamfer 46 to the magnetic base.

[0026] In particular, the application of the chamfer 46 results in a partial axial geometric adaptation of the magnetic base to reduce operating stresses in the adhesive layer 50 for the axial flux machine 100. Reference symbol list 10 Rotor 20 hub 30 toroidal core 40 magnetic elements 42 Magnetic element inner edge area 44 Middle range 46th phase 50 adhesive layer 52 adhesive bead 60 support element 70 sheet metal parts 100 Axial flux machine A Axial extension direction K motor vehicle R Radial extension direction S layer thickness S1 smaller layer thickness α chamfer angle QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 20 2012 012 228 U1

[0002]

Images