Rotor, axial flux machine and powertrain for a motor vehicle

Abstract

The invention relates to a rotor (1) for an axial flux machine (2), in particular for an axial flux machine (2) within a powertrain (3) of a motor vehicle (4), comprising an annular disc-shaped rotor body (5) which is coupled in a torque-transmitting manner to a rotor shaft (6), wherein on the rotor shaft (6) at least one rotor bearing (7) is arranged by means of which the rotor shaft (6) can be rotatably supported with respect to a stator (8), wherein between the rotor body (5) and the rotor shaft (6) a dielectric (9) is arranged such that the rotor body (5) and the rotor shaft (6) are electrically insulated with respect to each other such that a rotor shaft capacity (C Rotor Welle) of predefined capacity is formed, which reduces an electric voltage (U welle) occurring over the at least one rotor bearing (7) during operation of the axial flow machine (2) to a predefined voltage level.

Description

[0001] Rotor, axial flux machine and drive train for a motor vehicle

[0002] The present invention relates to a rotor for an axial flux machine, in particular for an axial flux machine within a drive train of a motor vehicle, comprising an annular disk-like rotor body coupled to a rotor shaft in a torque-transmitting manner. At least one rotor bearing is arranged on the rotor shaft, via which the rotor shaft can be rotatably mounted relative to a stator. The invention further relates to an axial flux machine and an electrically operable drive train for a motor vehicle.

[0003] Electric motors are increasingly being used to power motor vehicles, creating alternatives to combustion engines that require fossil fuels. Considerable efforts have already been made to improve the everyday suitability of electric drives and also to provide users with the same level of driving comfort they are accustomed to.

[0004] A detailed description of an electric drive can be found in an article in the magazine ATZ 113th year, 05 / 2011, pages 360-365 by Erik Schneider, Frank Fickl, Bernd Cebulski and Jens Liebold with the title: Highly integrated and flexible electric drive unit for electric vehicles, which arguably represents the closest state of the art. This article describes a drive unit for one axle of a vehicle which comprises an electric motor which is arranged concentrically and coaxially to a bevel gear differential, with a switchable 2-speed planetary gear set being arranged in the power train between the electric motor and bevel gear differential, which is also positioned coaxially to the electric motor or the bevel gear differential or spur gear differential. The drive unit is very compact and, thanks to the switchable 2-speed planetary gear set, allows a good compromise between climbing ability, acceleration and energy consumption.Such drive units are also referred to as e-axles or electrically operated drive trains. Axial flux machines are increasingly being used in such e-axles. An axial flux machine is a dynamoelectric machine in which the magnetic flux between the rotor and stator runs parallel to the rotor's axis of rotation. Both the stator and rotor are often largely disc-shaped. Axial flux machines are particularly advantageous when the axially available installation space is limited in a given application. This is often the case, for example, with the electric drive systems for electric vehicles described above. In addition to the shortened axial length, a further advantage of the axial flux machine is its comparatively high torque density. The reason for this is the larger air gap area available in a given installation space compared to radial flux machines.Furthermore, a smaller iron volume is required compared to conventional machines, which has a positive effect on the efficiency of the machine.

[0005] In addition to mechanical wear caused by shaft rotation, electrical currents flowing through the bearings from the rotor shaft to ground are another cause of wear in the bearings of an axial-flux machine. Voltages of a certain magnitude can overcome the insulating properties of the bearing lubrication, generating sparks that can lead to pitting, ridged surfaces, fusion craters, and ultimately premature failure of the bearings and motor. Bearing voltage—the voltage between the two bearing shells—usually correlates with shaft voltage—the voltage between the shaft and ground.

[0006] Due to capacitive coupling between the stator winding and the rotor and the high-frequency control of the stator phases, a voltage potential builds up at the rotor bearings, which can damage the bearings through so-called discharge currents. Countermeasures include insulating the bearings (e.g., using ceramic balls) or grounding the shaft using a sliding ground contact (electrically parallel to the bearings).

[0007] Furthermore, a device and a method for compensating a shaft voltage on a shaft are already known from DE 10 2017 109 049 A1. A compensation circuit for generating a compensation voltage couples the compensation voltage directly or indirectly to the rotor shaft via a coupling element. The shaft voltage is detected directly or indirectly on the rotor shaft via a tapping element. The object of the invention is to provide a rotor for an axial flux machine in which the shaft voltage and the resulting bearing currents are reduced. Furthermore, the object of the invention is to realize an optimized axial flux machine and an optimized drive train for a motor vehicle.

[0008] This object is achieved by a rotor for an axial flux machine, in particular for an axial flux machine within a drive train of a motor vehicle, comprising an annular disk-like rotor body which is coupled to a rotor shaft in a torque-transmitting manner, wherein at least one rotor bearing is arranged on the rotor shaft, via which rotor bearing the rotor shaft can be rotatably mounted relative to a stator, wherein a dielectric is arranged between the rotor body and the rotor shaft, so that the rotor body and the rotor shaft are electrically insulated from one another in such a way that a rotor-shaft capacitance CRotor of predetermined capacitance is formed, which continuously reduces an electrical voltage occurring across the at least one rotor bearing during operation of the axial flux machine to a predetermined voltage level.

[0009] This has the advantage that the voltage (or voltage potential) applied across the rotor bearing is reduced, so that the probability of spark discharges is reduced and the energy / power of the discharges that still occur is limited, with the result that bearing damage due to electrical discharges is reduced.

[0010] Furthermore, the emission of electromagnetic interference can be reduced, as the voltages on the shaft and the power coupled to the shaft are significantly reduced. These voltages / powers coupled to the shaft can be radiated outward via the shaft stub and optional gear stages. Reducing the voltage / power also results in less power being radiated. This can also reduce or even completely prevent damage to downstream components of the axial flux machine, such as a gear stage.

[0011] According to the invention, a dielectric is arranged between the rotor body and the rotor shaft. This means that the dielectric can be arranged at any location between the rotor shaft and the outer contour of the rotor body. For example, it is possible for the dielectric to rest on the outer contour of the rotor shaft on the one hand and on the inner contour of the rotor body on the other. However, it is also conceivable for the dielectric to be arranged in the rotor body and separate a radially inner rotor section from a radially outer rotor section, in which case the inner rotor section is preferably connected to the rotor shaft.

[0012] It is understood that the dielectric reduces both the voltage and the current that can flow, in particular, through a bearing and / or a gear.

[0013] Further advantageous embodiments of the invention are specified in the dependent claims. The features listed individually in the dependent claims can be combined with one another in a technologically expedient manner and can define further embodiments of the invention. Furthermore, the features specified in the claims are further specified and explained in the description, where further preferred embodiments of the invention are presented.

[0014] The rotor of an electric axial flux machine can be designed, at least in part, as a laminated rotor. A laminated rotor is constructed with radially layered elements. Alternatively, the rotor of an axial flux machine can also have a rotor carrier, which is equipped with magnetic laminations and / or SMC material and with magnetic elements designed as permanent magnets. A rotor shaft is a rotatably mounted shaft of an electric machine to which the rotor or rotor body is rotationally coupled.

[0015] A rotor bearing is preferably designed as a rolling bearing. Rolling bearings can be used, in particular, to enable rotary movements with the lowest possible friction losses. Rolling bearings can be used, in particular, for the fixation and / or support of axles and shafts. Depending on their design, they absorb radial and / or axial forces while simultaneously enabling the rotation of the shaft or the components mounted on an axle.

[0016] For this purpose, rolling elements are arranged between an inner and outer ring of the rolling bearing. Between these three main components—inner ring, outer ring, and the rolling elements—the friction within the rolling bearing is generally primarily rolling friction. Since the rolling elements in the inner and outer rings can roll preferentially on hardened steel surfaces with optimized lubrication, the rolling friction of such bearings is relatively low.

[0017] The inner ring can, in particular, connect the shaft accommodating the rolling bearing to the rolling bearing or the rolling elements. In this case, the shaft can, in particular, be connected to the side of the inner ring's outer surface facing the shaft, with the rolling elements of the rolling bearing rolling on the inner ring raceway opposite this outer surface. The inner ring can be made of a metallic and / or ceramic material. It is generally conceivable for the inner ring to be constructed in one or more parts, particularly in two parts.

[0018] The inner ring may have an inner ring recess. A cover plate, sealing plate, and / or seal may be arranged in an inner ring recess, particularly in a force-fitting and / or form-fitting manner. The inner ring recess is preferably formed as a circumferential groove in the inner ring.

[0019] The outer ring can, in particular, connect the bearing accommodating the rolling bearing to the rolling bearing or the rolling elements. In this case, the bearing can, in particular, be connected to the side of the outer ring's lateral surface facing the bearing, with the rolling elements of the rolling bearing rolling on the outer ring raceway opposite this lateral surface. The outer ring can be formed from a metallic and / or ceramic material. It is generally conceivable for the outer ring to be constructed in one or more parts, particularly in two parts.

[0020] The outer ring may have an outer ring recess. A cover plate, sealing plate, and / or seal may be arranged in an outer ring recess, particularly in a force-fitting and / or form-fitting manner. The outer ring recess is preferably formed as a circumferential groove in the outer ring.

[0021] Depending on the bearing design, the rolling elements are shaped like a ball or a roller. They roll along the raceways of the bearing and are responsible for transferring the force acting on a radial rolling bearing from the outer ring to the inner ring and vice versa. In a thrust rolling bearing, the rolling elements transfer the forces acting on the thrust rolling bearing between the raceways. Roller-shaped rolling elements are also called roller rolling elements, and spherical rolling elements are called bearing balls.

[0022] Roller-shaped rolling elements can, for example, be selected from the group of symmetrical spherical rollers, asymmetrical spherical rollers, cylindrical rollers, needle rollers and / or tapered rollers.

[0023] Rolling elements can be guided and spaced apart from each other in a cage or by rolling element spacers. It is also conceivable to design a cageless rolling bearing, which is also referred to as a full complement rolling bearing. In full complement rolling bearings, adjacent rolling elements can contact each other.

[0024] The rolling elements can roll within the rolling bearing, in particular on the inner ring raceway of the inner ring. For this purpose, the surface of the inner ring raceway can advantageously be designed to be abrasion-resistant, for example, through an appropriate surface treatment process and / or by applying an appropriate additional material layer. The inner ring raceway can be flat or profiled. A profiled design of the inner ring raceway can, for example, serve to guide the rolling elements on the inner ring raceway. A flat design of the inner ring raceway, on the other hand, can, for example, allow a certain degree of axial displacement of the rolling elements on the inner ring raceway.

[0025] The rolling elements can roll within the rolling bearing, particularly on the outer ring raceway of the outer ring. For this purpose, the surface of the outer ring raceway can advantageously be designed to be abrasion-resistant, for example, by means of an appropriate surface treatment process and / or by applying an appropriate additional material layer.

[0026] The outer ring raceway can be flat or profiled. A profiled outer ring raceway can, for example, serve to guide the rolling elements on the outer ring raceway. A flat outer ring raceway, on the other hand, can allow a certain degree of axial displacement of the rolling elements on the outer ring raceway.

[0027] A rolling bearing may have a cage, which guides the rolling elements. The cage is designed to space the rolling element balls and / or rollers apart from each other, for example, to minimize friction and heat generation of the rolling elements. Furthermore, the cage keeps the rolling element balls and / or rollers at a fixed distance from each other during rolling, thereby achieving even load distribution. The cage can be constructed in one piece or in multiple pieces.

[0028] A rolling bearing may have a seal to prevent lubricant from escaping from the bearing or dirt or moisture from entering the bearing. For this purpose, the seals used may be equipped with one or more sealing lips that can be in contact with a component of the rolling bearing. These are designed to seal the bearing as effectively as possible over its entire service life, while also minimizing excessive friction caused by the seal.

[0029] The rotor bearing preferably does not have a grounding element. Most preferably, the rotor, in particular the rotor shaft, also does not have a grounding element. Particularly preferably, the rotor-to-shaft capacitance formed between the rotor body and the rotor shaft is a maximum of fifty percent of the rotor-to-mass capacitance formed between the rotor body and the ground. The rotor-to-mass capacitance is essentially determined by the winding-to-rotor capacitance formed between the winding and the rotor body and the rotor-to-stator capacitance formed between the rotor body and the stator.

[0030] According to a further preferred development of the invention, it can also be provided that the dielectric has a permeability that is dimensioned such that it approximately corresponds to the permeability of air, in particular has a relative permeability that corresponds to twice the permeability of air, particularly preferably to 1.5 times the permeability of air, and most preferably to 1.1 times the permeability of air. This makes it possible to keep the capacitance formed between the rotor body and the shaft as small as possible under given geometric conditions.

[0031] Furthermore, according to a likewise advantageous embodiment of the invention, it can be provided that the dielectric is formed at least predominantly by air, thereby enabling a structurally simple and space-saving design and eliminating the need for filler material and the associated process for introducing the filler material. According to an alternative embodiment of the invention, it can be provided that the dielectric is formed at least predominantly by polystyrene foam. This material is also easy to process and offers significant advantages both with regard to its electrically insulating properties and its mechanically supporting properties.

[0032] Furthermore, the invention can also be further developed such that the rotor body is arranged at a distance from the rotor shaft in an electrically insulated manner by at least one electrically insulating connector element, or that the rotor carrier is interrupted or electrically insulated between the permanent magnets and the rotor shaft. Preferably, the at least one connector element is designed such that the rotor body is held centered and coaxially spaced from the rotor shaft.

[0033] This makes it possible to find a structurally simple and cost-effective way of aligning the rotor body with respect to the rotor shaft and, at the same time, electrically insulating it from the rotor shaft.

[0034] Advantageously, the rotor can have a first connector element designed as a rotor body clamping ring at its first axial end and a second connector element designed as a rotor body clamping ring at its second axial end for insulatingly spacing the rotor body and the rotor shaft. This can ensure, in particular, simplified assembly of the rotor.

[0035] According to an advantageous embodiment of the invention, the dielectric can be shaped like an annular disk, with its inner surface resting against the rotor shaft and its outer surface resting against the rotor body. The annular disk-like shape of the dielectric enables a uniform distribution of the electrical insulation between the rotor body and the rotor shaft, which leads to a more effective reduction of the electrical voltage. Furthermore, the arrangement of the dielectric between the rotor body and the rotor shaft enables a compact design of the rotor, which is particularly advantageous in applications with limited installation space, such as in a motor vehicle drive train.

[0036] According to a further preferred development of the invention, it can also be provided that the inner lateral surface of the dielectric is connected to the rotor shaft in a form-fitting and / or material-fitting and / or force-fitting manner and / or the outer lateral surface of the dielectric is connected to the rotor body in a form-fitting and / or material-fitting and / or force-fitting manner.

[0037] Furthermore, according to a likewise advantageous embodiment of the invention, it can be provided that the dielectric is designed in the shape of an annular disk and rests against an end face of the rotor body. According to a further particularly preferred embodiment of the invention, it can be provided that the dielectric is designed in several parts. If the dielectric is designed in several parts, this can lead to easier production of the rotor, since the individual parts of the dielectric can be manufactured separately and then joined together. Furthermore, such an arrangement of the dielectric can enable a more even distribution of the electrical insulation, since each part of the dielectric can be attached to a specific location on the rotor to ensure effective reduction of the electrical voltage. This can further minimize the risk of electrical breakdowns and malfunctions and extend the service life of the rotor bearings.

[0038] It is particularly preferred that the dielectric is formed in several parts, wherein the individual parts of the dielectric are connected to one another in a form-fitting and / or material-fitting and / or force-fitting manner.

[0039] According to a further preferred embodiment of the invention, the dielectric can have a radially inner annular disk, from which a plurality of radially extending webs extend outward. The dielectric thus preferably has a star-shaped contour.

[0040] In this context, it is further advantageous if circumferentially adjacent magnetic elements are each supported on one of the webs of the dielectric. The star-shaped dielectric projects into the intermediate regions between the magnetic elements of the rotor and can thus form a positive connection with the magnetic elements for torque support. A non-magnetic material (p-relative ~ 1) is preferably arranged between the magnetic elements, which fixes the magnetic elements. Particularly preferably, a torque-resistant connection of these webs between the magnetic elements and the rotor shaft is made of an electrically non-conductive material, so that the electrical insulation and torque transmission between the magnetic elements and the rotor shaft can be realized. Alternatively, there can also be individual webs which are connected to the rotor shaft.Furthermore, it may also be preferred for the dielectric to have a radially outer annular disc aligned coaxially with the radially inner annular disc, wherein the inner annular disc and the outer annular disc are connected to one another by the webs. This makes it particularly possible for a rotor with a magnetic yoke to have, in addition to the star-shaped dielectric, a radially outer annular disc-shaped region which radially supports and / or centers the rotor yoke. Support in the axial direction and protection against tilting of the yoke relative to the rotor shaft are also conceivable, wherein the webs between the magnetic elements can assist this support.

[0041] However, it is also possible, alternatively, for the rotor to have a radially outer annular disc aligned coaxially with the radially inner annular disc, with the inner annular disc and the outer annular disc being connected to each other by the webs. In this embodiment, the outer annular disc is therefore not a component of the dielectric and can therefore preferably also be made of an electrically conductive material.

[0042] The object of the invention can also be achieved by an axial flux machine, in particular for a drive train of a motor vehicle, comprising a rotor according to one of the preceding claims 1-8.

[0043] Depending on the application, it may be advantageous to design an axial flux machine in an I-arrangement or an H-arrangement. In an I-arrangement, the rotor is arranged axially next to a stator or between two stators. In an H-arrangement, two rotors are arranged on opposite axial sides of a stator. The axial flux machine according to the invention is preferably configured in an H-arrangement.

[0044] In principle, it is also conceivable for the axial flux machine to consist of exactly one stator and exactly one rotor. In principle, it is also possible for a plurality of I-type and / or H-type rotor-stator configurations to be arranged axially next to one another. In this context, it would also be possible to arrange several I-type rotor-stator configurations next to one another in the axial direction. In particular, it is also preferable for the H-type and / or I-type rotor-stator configurations to be essentially identical in design so that they can be combined in a modular manner to form an overall configuration. Such rotor-stator configurations can, in particular, be arranged coaxially to one another and connected to a common rotor shaft or to several rotor shafts.

[0045] The stator of the electric axial flux machine according to the invention preferably has a stator body with a plurality of stator windings arranged in the circumferential direction. The stator body can be formed as a single piece or segmented in the circumferential direction. The stator body can be formed from a stator core with a plurality of laminated layers of electrical steel. Alternatively, the stator body can also be formed from a pressed soft magnetic material, such as the so-called SMC (Soft Magnetic Compound).

[0046] The electric axial flux machine may further comprise a control device. A control device, as can be used in the present invention, serves in particular for the electronic control and / or regulation of one or more technical systems of the electric axial flux machine.

[0047] Control and / or regulation operations can be performed within the control device. It is particularly preferred that the control device comprises hardware configured to execute software. The control device preferably comprises at least one electronic processor for executing program sequences defined in the software.

[0048] The control device may further comprise one or more electronic memories in which the data contained in the signals transmitted to the control device can be stored and read out again. Furthermore, the control device may comprise one or more electronic memories in which data can be stored in a modifiable and / or non-modifiable manner.

[0049] A control device can comprise a plurality of control units, which are arranged, in particular, spatially separated from one another in the motor vehicle. Control units are also referred to as Electronic Control Units (ECUs) or Electronic Control Modules (ECMs) and preferably have electronic microcontrollers for performing computing operations for processing data, particularly preferably using software. The control units can preferably be networked with one another, enabling wired and / or wireless data exchange between control units. In particular, it is also possible to network the control units with one another via bus systems present in the motor vehicle, such as the CAN bus or LIN bus.

[0050] Most preferably, the control device has at least one processor and at least one memory, which in particular contains a computer program code, wherein the memory and the computer program code are configured, with the processor, to cause the control device to execute the computer program code.

[0051] The control unit can particularly preferably comprise power electronics for supplying current to the stator or rotor. Power electronics is preferably a combination of various components that control or regulate a current to the electrical machine, preferably including the peripheral components required for this purpose, such as cooling elements or power supplies. In particular, the power electronics contains one or more power electronic components that are designed to control or regulate a current. This particularly preferably involves one or more power switches, e.g.

[0052] Power transistors. The power electronics particularly preferably have more than two, particularly preferably three, separate phases or current paths, each with at least one dedicated power electronics component. The power electronics are preferably designed to control or regulate a power per phase with a peak power, preferably continuous power, of at least 1,000 W, preferably at least 10,000 W, particularly preferably at least 100,000 W.

[0053] The electric axial flux machine is intended in particular for use within a drive train of a hybrid or fully electric motor vehicle. In particular, the electric machine is dimensioned such that vehicle speeds greater than 50 km / h, preferably greater than 80 km / h, and in particular greater than 100 km / h can be achieved. The electric motor particularly preferably has an output greater than 50 kW, preferably greater than 100 kW, and in particular greater than 250 kW. It is further preferred that the electric machine provides operating speeds greater than 5,000 rpm, particularly preferably greater than 10,000 rpm, and most particularly preferably greater than 12,500 rpm. Most preferably, the electric machine has operating speeds between 5,000 and 15,000 rpm, and most preferably between 7,500 and 13,000 rpm.

[0054] Finally, the object of the invention can also be achieved by a drive train of a motor vehicle comprising an axial flux machine according to claim 9.

[0055] The electric axial flux machine can thus preferably be installed in an electrically operated axle drive train. An electric axle drive train of a motor vehicle comprises an electric axial flux machine and a transmission, wherein the electric axial flux machine and the transmission form a structural unit. In particular, it can be provided that the electric axial flux machine and the transmission are arranged in a common drive train housing. Alternatively, it would of course also be possible for the electric axial flux machine to have a motor housing and the transmission to have a transmission housing, wherein the structural unit can then be effected by fixing the transmission relative to the electric axial flux machine. This structural unit is occasionally also referred to as an electric axle.

[0056] The electric axial flux machine can particularly preferably also be intended for use in a hybrid module. In a hybrid module, components and functional elements of a hybridized powertrain can be spatially and / or structurally combined and preconfigured, allowing a hybrid module to be integrated into a motor vehicle's powertrain in a particularly simple manner. In particular, an axial flux machine and a clutch system can be present.

[0057] The invention will be explained in more detail below with reference to figures without limiting the general inventive concept.

[0058] It shows:

[0059] Figure 1 shows a first embodiment of an axial flow machine in a schematic axial section,

[0060] Figure 2 shows a second embodiment of an axial flow machine in a schematic axial section,

[0061] Figure 3 shows a motor vehicle with an electrically operated drive train in a schematic representation,

[0062] Figure 4 shows an embodiment of the rotor in a cross-sectional view.

[0063] Figure 5 shows a third embodiment of an axial flow machine in a schematic axial sectional view.

[0064] Figures 1-2 show a rotor 1 for an axial flux machine 2 in Fl configuration, in particular for an axial flux machine 2 within a drive train 3 of a motor vehicle 4, as also sketched in Figure 3.

[0065] The rotor 1 comprises an annular disk-like rotor body 5 which is coupled to a rotor shaft 6 in a torque-transmitting manner, two axially spaced rotor bearings 7 being arranged on the rotor shaft 6, via which the rotor shaft 6 can be rotatably mounted relative to a stator 8. A dielectric 9 is arranged between the rotor body 5 and the rotor shaft 6, so that the rotor body 5 and the rotor shaft 6 are electrically insulated from one another in such a way that a rotor-shaft capacitance CRotorweiie of predetermined capacitance is formed, which reduces an electrical voltage llweiie occurring across at least one rotor bearing 7 during operation of the axial flux machine 2 to a predetermined voltage level.

[0066] From Figure 1 it can be seen that the dielectric 9 can be shaped like an annular disc and rests with its inner surface 10 on the rotor shaft 6 and with its outer surface 11 on the outer end face 12 on the rotor body 5.

[0067] The inner lateral surface 10 of the dielectric 9 is connected to the rotor shaft 6 in a form-fitting and / or material-fitting and / or force-fitting manner. The outer lateral surface 11 of the dielectric 9 is also connected to the rotor body 5 in a form-fitting and / or material-fitting and / or force-fitting manner in an analogous manner.

[0068] Figure 4 shows an embodiment of a rotor 1 in which the dielectric 9 has a radially inner annular disk 13, from which a plurality of radially extending webs 15 extend outwards. This embodiment is also shown in an axial section in Figure 2. In this case, magnetic elements 16 which are adjacent in the circumferential direction each bear against one of the webs 15 of the dielectric 9. The dielectric 9 further has a radially outer annular disk 14 which is aligned coaxially to the radially inner annular disk 13, wherein the inner annular disk 13 and the outer annular disk 14 are connected to one another by the webs 15. In principle, it is also possible for the webs 15 to be formed separately from the inner annular disk 13, which is indicated in Figure 2 by the corresponding hatching. In this case, it is also conceivable for the webs 5 not to be a component of the dielectric 9 and therefore to have no electrically insulating effect.The webs 15 can, however, also be formed monolithically with the dielectric 9. Figure 5 shows a further embodiment of a rotor 1, in which a dielectric 9 is also arranged between the rotor body 5 and the rotor shaft 6. In this case, however, the dielectric 9 does not lie on the one hand against the outer contour of the rotor shaft 6 and on the other hand against the inner contour of the rotor body 5, as is the case, for example, in the embodiment in Figure 1, but rather the essentially annular dielectric 9 is arranged in the rotor body 5 and thus separates a radially inner rotor section from a radially outer rotor section, the inner rotor section then being connected to the rotor shaft 6.

[0069] The invention is not limited to the embodiments illustrated in the figures. The above description is therefore not to be considered restrictive, but rather explanatory. The following claims are to be understood in such a way that a stated feature is present in at least one embodiment of the invention. This does not exclude the presence of further features. Where the claims and the above description define 'first' and 'second' features, this designation serves to distinguish between two similar features without establishing a priority.

[0070] List of reference symbols

[0071] 1 rotor

[0072] 2 Axial flux machine 3 Drive train

[0073] 4 Motor vehicle

[0074] 5 rotor body

[0075] 6 Rotor shaft

[0076] 7 Rotor bearing 8 Stator

[0077] 9 Dielectric

[0078] 10 Shell surface

[0079] 11 Shell surface

[0080] 12 Front side 13 Ring disc

[0081] 14 Ring disc

[0082] 15 bridges

[0083] 16 magnetic elements

Claims

Claims 1. Rotor (1) for an axial flux machine (2), in particular for an axial flux machine (2) within a drive train (3) of a motor vehicle (4), comprising an annular disk-like rotor body (5) which is coupled to a rotor shaft (6) in a torque-transmitting manner, wherein at least one rotor bearing (7) is arranged on the rotor shaft (6), via which rotor bearing the rotor shaft (6) can be rotatably mounted relative to a stator (8), characterized in that a dielectric (9) is arranged between the rotor body (5) and the rotor shaft (6) so that the rotor body (5) and the rotor shaft (6) are electrically insulated from one another in such a way that a rotor-shaft capacitance (CRotorweiie) of predetermined capacitance is formed, which reduces an electrical voltage (llweiie) occurring across the at least one rotor bearing (7) during operation of the axial flux machine (2) to a predetermined voltage level.

2. Rotor (1) according to claim 1, characterized in that the dielectric (9) is shaped like an annular disc and rests with its inner surface (10) on the rotor shaft (6) and with its outer surface (11) on the rotor body (5).

3. Rotor (1) according to claim 1 or 2, characterized in that the inner circumferential surface (10) of the dielectric (9) is connected to the rotor shaft (6) in a form-fitting manner and / or by a material fit and / or by a force-fitting manner and / or the outer circumferential surface (11) of the dielectric (9) is connected to the rotor body (5) in a form-fitting manner and / or by a material fit and / or by a force-fitting manner.

4. Rotor (1) according to one of the preceding claims, characterized in that the dielectric (9) is formed in several parts, wherein the individual parts of the dielectric (9) are preferably connected to one another in a form-fitting and / or material-fitting and / or force-fitting manner.

5. Rotor (1) according to one of the preceding claims, characterized in that the dielectric (9) has a radially inner annular disc (13) from which a plurality of radially extending webs (15) extend outwards.

6. Rotor (1) according to claim 5, characterized in that circumferentially adjacent magnetic elements (16) are each supported on one of the webs (15) of the dielectric (9).

7. Rotor (1) according to one of the preceding claims 5-6, characterized in that the dielectric (9) has a radially outer annular disc (14) aligned coaxially to the radially inner annular disc (13), wherein the inner annular disc (13) and the outer annular disc (14) are connected to one another by the webs (15).

8. Rotor (1) according to one of the preceding claims 1 -6, characterized in that the rotor (1) has a radially outer annular disc (14) aligned coaxially to the radially inner annular disc (13), wherein the inner annular disc (13) and the outer annular disc (14) are connected to one another by the webs (15).

9. Axial flux machine (2), in particular for a drive train (3) of a motor vehicle (4), comprising a rotor (1) according to one of the preceding claims 1-8.

10. Drive train (3) of a motor vehicle (4) comprising an axial flux machine (2) according to claim 9.

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